/Users/deen/code/yugabyte-db/src/postgres/src/interfaces/libpq/fe-connect.c

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/*-------------------------------------------------------------------------
 *
 * fe-connect.c
 *    functions related to setting up a connection to the backend
 *
 * Portions Copyright (c) 1996-2018, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *    src/interfaces/libpq/fe-connect.c
 *
 *-------------------------------------------------------------------------
 */

#include "postgres_fe.h"

#include <sys/stat.h>
#include <fcntl.h>
#include <ctype.h>
#include <time.h>
#include <unistd.h>

#include "libpq-fe.h"
#include "libpq-int.h"
#include "fe-auth.h"
#include "pg_config_paths.h"

#ifdef WIN32
#include "win32.h"
#ifdef _WIN32_IE
#undef _WIN32_IE
#endif
#define _WIN32_IE 0x0500
#ifdef near
#undef near
#endif
#define near
#include <shlobj.h>
#ifdef _MSC_VER         /* mstcpip.h is missing on mingw */
#include <mstcpip.h>
#endif
#else
#include <sys/socket.h>
#include <netdb.h>
#include <netinet/in.h>
#ifdef HAVE_NETINET_TCP_H
#include <netinet/tcp.h>
#endif
#endif

#ifdef ENABLE_THREAD_SAFETY
#ifdef WIN32
#include "pthread-win32.h"
#else
#include <pthread.h>
#endif
#endif

#ifdef USE_LDAP
#ifdef WIN32
#include <winldap.h>
#else
/* OpenLDAP deprecates RFC 1823, but we want standard conformance */
#define LDAP_DEPRECATED 1
#include <ldap.h>
typedef struct timeval LDAP_TIMEVAL;
#endif
static int ldapServiceLookup(const char *purl, PQconninfoOption *options,
          PQExpBuffer errorMessage);
#endif

#include "common/ip.h"
#include "common/scram-common.h"
#include "mb/pg_wchar.h"
#include "port/pg_bswap.h"


#ifndef WIN32
#define PGPASSFILE ".pgpass"
#else
#define PGPASSFILE "pgpass.conf"
#endif

/*
 * Pre-9.0 servers will return this SQLSTATE if asked to set
 * application_name in a startup packet.  We hard-wire the value rather
 * than looking into errcodes.h since it reflects historical behavior
 * rather than that of the current code.
 */
#define ERRCODE_APPNAME_UNKNOWN "42704"

/* This is part of the protocol so just define it */
#define ERRCODE_INVALID_PASSWORD "28P01"
/* This too */
#define ERRCODE_CANNOT_CONNECT_NOW "57P03"

/*
 * Cope with the various platform-specific ways to spell TCP keepalive socket
 * options.  This doesn't cover Windows, which as usual does its own thing.
 */
#if defined(TCP_KEEPIDLE)
/* TCP_KEEPIDLE is the name of this option on Linux and *BSD */
#define PG_TCP_KEEPALIVE_IDLE TCP_KEEPIDLE
#define PG_TCP_KEEPALIVE_IDLE_STR "TCP_KEEPIDLE"
#elif defined(TCP_KEEPALIVE_THRESHOLD)
/* TCP_KEEPALIVE_THRESHOLD is the name of this option on Solaris >= 11 */
#define PG_TCP_KEEPALIVE_IDLE TCP_KEEPALIVE_THRESHOLD
#define PG_TCP_KEEPALIVE_IDLE_STR "TCP_KEEPALIVE_THRESHOLD"
#elif defined(TCP_KEEPALIVE) && defined(__darwin__)
/* TCP_KEEPALIVE is the name of this option on macOS */
/* Caution: Solaris has this symbol but it means something different */
#define PG_TCP_KEEPALIVE_IDLE TCP_KEEPALIVE
#define PG_TCP_KEEPALIVE_IDLE_STR "TCP_KEEPALIVE"
#endif

/*
 * fall back options if they are not specified by arguments or defined
 * by environment variables
 */
#define DefaultTty    ""
#define DefaultOption ""
#define DefaultAuthtype     ""
#define DefaultTargetSessionAttrs "any"
#ifdef USE_SSL
#define DefaultSSLMode "prefer"
#else
#define DefaultSSLMode  "disable"
#endif

/* ----------
 * Definition of the conninfo parameters and their fallback resources.
 *
 * If Environment-Var and Compiled-in are specified as NULL, no
 * fallback is available. If after all no value can be determined
 * for an option, an error is returned.
 *
 * The value for the username is treated specially in conninfo_add_defaults.
 * If the value is not obtained any other way, the username is determined
 * by pg_fe_getauthname().
 *
 * The Label and Disp-Char entries are provided for applications that
 * want to use PQconndefaults() to create a generic database connection
 * dialog. Disp-Char is defined as follows:
 *    ""    Normal input field
 *    "*"   Password field - hide value
 *    "D"   Debug option - don't show by default
 *
 * PQconninfoOptions[] is a constant static array that we use to initialize
 * a dynamically allocated working copy.  All the "val" fields in
 * PQconninfoOptions[] *must* be NULL.  In a working copy, non-null "val"
 * fields point to malloc'd strings that should be freed when the working
 * array is freed (see PQconninfoFree).
 *
 * The first part of each struct is identical to the one in libpq-fe.h,
 * which is required since we memcpy() data between the two!
 * ----------
 */
typedef struct _internalPQconninfoOption
{
  char     *keyword;    /* The keyword of the option      */
  char     *envvar;     /* Fallback environment variable name */
  char     *compiled;   /* Fallback compiled in default value */
  char     *val;      /* Option's current value, or NULL     */
  char     *label;      /* Label for field in connect dialog  */
  char     *dispchar;   /* Indicates how to display this field in a
                 * connect dialog. Values are: "" Display
                 * entered value as is "*" Password field -
                 * hide value "D"  Debug option - don't show
                 * by default */
  int     dispsize;   /* Field size in characters for dialog  */
  /* ---
   * Anything above this comment must be synchronized with
   * PQconninfoOption in libpq-fe.h, since we memcpy() data
   * between them!
   * ---
   */
  off_t   connofs;    /* Offset into PGconn struct, -1 if not there */
} internalPQconninfoOption;

static const internalPQconninfoOption PQconninfoOptions[] = {
  /*
   * "authtype" is no longer used, so mark it "don't show".  We keep it in
   * the array so as not to reject conninfo strings from old apps that might
   * still try to set it.
   */
  {"authtype", "PGAUTHTYPE", DefaultAuthtype, NULL,
  "Database-Authtype", "D", 20, -1},

  {"service", "PGSERVICE", NULL, NULL,
  "Database-Service", "", 20, -1},

  {"user", "PGUSER", NULL, NULL,
    "Database-User", "", 20,
  offsetof(struct pg_conn, pguser)},

  {"password", "PGPASSWORD", NULL, NULL,
    "Database-Password", "*", 20,
  offsetof(struct pg_conn, pgpass)},

  {"passfile", "PGPASSFILE", NULL, NULL,
    "Database-Password-File", "", 64,
  offsetof(struct pg_conn, pgpassfile)},

  {"connect_timeout", "PGCONNECT_TIMEOUT", NULL, NULL,
    "Connect-timeout", "", 10,  /* strlen(INT32_MAX) == 10 */
  offsetof(struct pg_conn, connect_timeout)},

  {"dbname", "PGDATABASE", NULL, NULL,
    "Database-Name", "", 20,
  offsetof(struct pg_conn, dbName)},

  {"host", "PGHOST", NULL, NULL,
    "Database-Host", "", 40,
  offsetof(struct pg_conn, pghost)},

  {"hostaddr", "PGHOSTADDR", NULL, NULL,
    "Database-Host-IP-Address", "", 45,
  offsetof(struct pg_conn, pghostaddr)},

  /* Use YugaByte default port */
  {"port", "PGPORT", DEF_YBPORT_STR, NULL,
    "Database-Port", "", 6,
  offsetof(struct pg_conn, pgport)},

  {"client_encoding", "PGCLIENTENCODING", NULL, NULL,
    "Client-Encoding", "", 10,
  offsetof(struct pg_conn, client_encoding_initial)},

  /*
   * "tty" is no longer used either, but keep it present for backwards
   * compatibility.
   */
  {"tty", "PGTTY", DefaultTty, NULL,
    "Backend-Debug-TTY", "D", 40,
  offsetof(struct pg_conn, pgtty)},

  {"options", "PGOPTIONS", DefaultOption, NULL,
    "Backend-Debug-Options", "D", 40,
  offsetof(struct pg_conn, pgoptions)},

  {"application_name", "PGAPPNAME", NULL, NULL,
    "Application-Name", "", 64,
  offsetof(struct pg_conn, appname)},

  {"fallback_application_name", NULL, NULL, NULL,
    "Fallback-Application-Name", "", 64,
  offsetof(struct pg_conn, fbappname)},

  {"keepalives", NULL, NULL, NULL,
    "TCP-Keepalives", "", 1,  /* should be just '0' or '1' */
  offsetof(struct pg_conn, keepalives)},

  {"keepalives_idle", NULL, NULL, NULL,
    "TCP-Keepalives-Idle", "", 10,  /* strlen(INT32_MAX) == 10 */
  offsetof(struct pg_conn, keepalives_idle)},

  {"keepalives_interval", NULL, NULL, NULL,
    "TCP-Keepalives-Interval", "", 10,  /* strlen(INT32_MAX) == 10 */
  offsetof(struct pg_conn, keepalives_interval)},

  {"keepalives_count", NULL, NULL, NULL,
    "TCP-Keepalives-Count", "", 10, /* strlen(INT32_MAX) == 10 */
  offsetof(struct pg_conn, keepalives_count)},

  /*
   * ssl options are allowed even without client SSL support because the
   * client can still handle SSL modes "disable" and "allow". Other
   * parameters have no effect on non-SSL connections, so there is no reason
   * to exclude them since none of them are mandatory.
   */
  {"sslmode", "PGSSLMODE", DefaultSSLMode, NULL,
    "SSL-Mode", "", 12,   /* sizeof("verify-full") == 12 */
  offsetof(struct pg_conn, sslmode)},

  {"sslcompression", "PGSSLCOMPRESSION", "0", NULL,
    "SSL-Compression", "", 1,
  offsetof(struct pg_conn, sslcompression)},

  {"sslcert", "PGSSLCERT", NULL, NULL,
    "SSL-Client-Cert", "", 64,
  offsetof(struct pg_conn, sslcert)},

  {"sslkey", "PGSSLKEY", NULL, NULL,
    "SSL-Client-Key", "", 64,
  offsetof(struct pg_conn, sslkey)},

  {"sslrootcert", "PGSSLROOTCERT", NULL, NULL,
    "SSL-Root-Certificate", "", 64,
  offsetof(struct pg_conn, sslrootcert)},

  {"sslcrl", "PGSSLCRL", NULL, NULL,
    "SSL-Revocation-List", "", 64,
  offsetof(struct pg_conn, sslcrl)},

  {"requirepeer", "PGREQUIREPEER", NULL, NULL,
    "Require-Peer", "", 10,
  offsetof(struct pg_conn, requirepeer)},

#if defined(ENABLE_GSS) || defined(ENABLE_SSPI)
  /* Kerberos and GSSAPI authentication support specifying the service name */
  {"krbsrvname", "PGKRBSRVNAME", PG_KRB_SRVNAM, NULL,
    "Kerberos-service-name", "", 20,
  offsetof(struct pg_conn, krbsrvname)},
#endif

#if defined(ENABLE_GSS) && defined(ENABLE_SSPI)

  /*
   * GSSAPI and SSPI both enabled, give a way to override which is used by
   * default
   */
  {"gsslib", "PGGSSLIB", NULL, NULL,
    "GSS-library", "", 7, /* sizeof("gssapi") = 7 */
  offsetof(struct pg_conn, gsslib)},
#endif

  {"replication", NULL, NULL, NULL,
    "Replication", "D", 5,
  offsetof(struct pg_conn, replication)},

  {"target_session_attrs", "PGTARGETSESSIONATTRS",
    DefaultTargetSessionAttrs, NULL,
    "Target-Session-Attrs", "", 11, /* sizeof("read-write") = 11 */
  offsetof(struct pg_conn, target_session_attrs)},

  /* Terminating entry --- MUST BE LAST */
  {NULL, NULL, NULL, NULL,
  NULL, NULL, 0}
};

static const PQEnvironmentOption EnvironmentOptions[] =
{
  /* common user-interface settings */
  {
    "PGDATESTYLE", "datestyle"
  },
  {
    "PGTZ", "timezone"
  },
  /* internal performance-related settings */
  {
    "PGGEQO", "geqo"
  },
  {
    NULL, NULL
  }
};

/* The connection URI must start with either of the following designators: */
static const char uri_designator[] = "postgresql://";
static const char short_uri_designator[] = "postgres://";

static bool connectOptions1(PGconn *conn, const char *conninfo);
static bool connectOptions2(PGconn *conn);
static int  connectDBStart(PGconn *conn);
static int  connectDBComplete(PGconn *conn);
static PGPing internal_ping(PGconn *conn);
static PGconn *makeEmptyPGconn(void);
static bool fillPGconn(PGconn *conn, PQconninfoOption *connOptions);
static void freePGconn(PGconn *conn);
static void closePGconn(PGconn *conn);
static void release_conn_addrinfo(PGconn *conn);
static void sendTerminateConn(PGconn *conn);
static PQconninfoOption *conninfo_init(PQExpBuffer errorMessage);
static PQconninfoOption *parse_connection_string(const char *conninfo,
            PQExpBuffer errorMessage, bool use_defaults);
static int  uri_prefix_length(const char *connstr);
static bool recognized_connection_string(const char *connstr);
static PQconninfoOption *conninfo_parse(const char *conninfo,
         PQExpBuffer errorMessage, bool use_defaults);
static PQconninfoOption *conninfo_array_parse(const char *const *keywords,
           const char *const *values, PQExpBuffer errorMessage,
           bool use_defaults, int expand_dbname);
static bool conninfo_add_defaults(PQconninfoOption *options,
            PQExpBuffer errorMessage);
static PQconninfoOption *conninfo_uri_parse(const char *uri,
           PQExpBuffer errorMessage, bool use_defaults);
static bool conninfo_uri_parse_options(PQconninfoOption *options,
               const char *uri, PQExpBuffer errorMessage);
static bool conninfo_uri_parse_params(char *params,
              PQconninfoOption *connOptions,
              PQExpBuffer errorMessage);
static char *conninfo_uri_decode(const char *str, PQExpBuffer errorMessage);
static bool get_hexdigit(char digit, int *value);
static const char *conninfo_getval(PQconninfoOption *connOptions,
        const char *keyword);
static PQconninfoOption *conninfo_storeval(PQconninfoOption *connOptions,
          const char *keyword, const char *value,
          PQExpBuffer errorMessage, bool ignoreMissing, bool uri_decode);
static PQconninfoOption *conninfo_find(PQconninfoOption *connOptions,
        const char *keyword);
static void defaultNoticeReceiver(void *arg, const PGresult *res);
static void defaultNoticeProcessor(void *arg, const char *message);
static int parseServiceInfo(PQconninfoOption *options,
         PQExpBuffer errorMessage);
static int parseServiceFile(const char *serviceFile,
         const char *service,
         PQconninfoOption *options,
         PQExpBuffer errorMessage,
         bool *group_found);
static char *pwdfMatchesString(char *buf, const char *token);
static char *passwordFromFile(const char *hostname, const char *port, const char *dbname,
         const char *username, const char *pgpassfile);
static void pgpassfileWarning(PGconn *conn);
static void default_threadlock(int acquire);


/* global variable because fe-auth.c needs to access it */
pgthreadlock_t pg_g_threadlock = default_threadlock;


/*
 *    pqDropConnection
 *
 * Close any physical connection to the server, and reset associated
 * state inside the connection object.  We don't release state that
 * would be needed to reconnect, though, nor local state that might still
 * be useful later.
 *
 * We can always flush the output buffer, since there's no longer any hope
 * of sending that data.  However, unprocessed input data might still be
 * valuable, so the caller must tell us whether to flush that or not.
 */
void
pqDropConnection(PGconn *conn, bool flushInput)
{
  /* Drop any SSL state */
  pqsecure_close(conn);

  /* Close the socket itself */
  if (conn->sock != PGINVALID_SOCKET)
    closesocket(conn->sock);
  conn->sock = PGINVALID_SOCKET;

  /* Optionally discard any unread data */
  if (flushInput)
    conn->inStart = conn->inCursor = conn->inEnd = 0;

  /* Always discard any unsent data */
  conn->outCount = 0;

  /* Free authentication state */
#ifdef ENABLE_GSS
  {
    OM_uint32 min_s;

    if (conn->gctx)
      gss_delete_sec_context(&min_s, &conn->gctx, GSS_C_NO_BUFFER);
    if (conn->gtarg_nam)
      gss_release_name(&min_s, &conn->gtarg_nam);
  }
#endif
#ifdef ENABLE_SSPI
  if (conn->sspitarget)
  {
    free(conn->sspitarget);
    conn->sspitarget = NULL;
  }
  if (conn->sspicred)
  {
    FreeCredentialsHandle(conn->sspicred);
    free(conn->sspicred);
    conn->sspicred = NULL;
  }
  if (conn->sspictx)
  {
    DeleteSecurityContext(conn->sspictx);
    free(conn->sspictx);
    conn->sspictx = NULL;
  }
  conn->usesspi = 0;
#endif
  if (conn->sasl_state)
  {
    /*
     * XXX: if support for more authentication mechanisms is added, this
     * needs to call the right 'free' function.
     */
    pg_fe_scram_free(conn->sasl_state);
    conn->sasl_state = NULL;
  }
}


/*
 *    pqDropServerData
 *
 * Clear all connection state data that was received from (or deduced about)
 * the server.  This is essential to do between connection attempts to
 * different servers, else we may incorrectly hold over some data from the
 * old server.
 *
 * It would be better to merge this into pqDropConnection, perhaps, but
 * right now we cannot because that function is called immediately on
 * detection of connection loss (cf. pqReadData, for instance).  This data
 * should be kept until we are actually starting a new connection.
 */
static void
pqDropServerData(PGconn *conn)
{
  PGnotify   *notify;
  pgParameterStatus *pstatus;

  /* Forget pending notifies */
  notify = conn->notifyHead;
  while (notify != NULL)
  {
    PGnotify   *prev = notify;

    notify = notify->next;
    free(prev);
  }
  conn->notifyHead = conn->notifyTail = NULL;

  /* Reset ParameterStatus data, as well as variables deduced from it */
  pstatus = conn->pstatus;
  while (pstatus != NULL)
  {
    pgParameterStatus *prev = pstatus;

    pstatus = pstatus->next;
    free(prev);
  }
  conn->pstatus = NULL;
  conn->client_encoding = PG_SQL_ASCII;
  conn->std_strings = false;
  conn->sversion = 0;

  /* Drop large-object lookup data */
  if (conn->lobjfuncs)
    free(conn->lobjfuncs);
  conn->lobjfuncs = NULL;

  /* Reset assorted other per-connection state */
  conn->last_sqlstate[0] = '\0';
  conn->auth_req_received = false;
  conn->password_needed = false;
  conn->be_pid = 0;
  conn->be_key = 0;
}


/*
 *    Connecting to a Database
 *
 * There are now six different ways a user of this API can connect to the
 * database.  Two are not recommended for use in new code, because of their
 * lack of extensibility with respect to the passing of options to the
 * backend.  These are PQsetdb and PQsetdbLogin (the former now being a macro
 * to the latter).
 *
 * If it is desired to connect in a synchronous (blocking) manner, use the
 * function PQconnectdb or PQconnectdbParams. The former accepts a string of
 * option = value pairs (or a URI) which must be parsed; the latter takes two
 * NULL terminated arrays instead.
 *
 * To connect in an asynchronous (non-blocking) manner, use the functions
 * PQconnectStart or PQconnectStartParams (which differ in the same way as
 * PQconnectdb and PQconnectdbParams) and PQconnectPoll.
 *
 * Internally, the static functions connectDBStart, connectDBComplete
 * are part of the connection procedure.
 */

/*
 *    PQconnectdbParams
 *
 * establishes a connection to a postgres backend through the postmaster
 * using connection information in two arrays.
 *
 * The keywords array is defined as
 *
 *     const char *params[] = {"option1", "option2", NULL}
 *
 * The values array is defined as
 *
 *     const char *values[] = {"value1", "value2", NULL}
 *
 * Returns a PGconn* which is needed for all subsequent libpq calls, or NULL
 * if a memory allocation failed.
 * If the status field of the connection returned is CONNECTION_BAD,
 * then some fields may be null'ed out instead of having valid values.
 *
 * You should call PQfinish (if conn is not NULL) regardless of whether this
 * call succeeded.
 */
PGconn *
PQconnectdbParams(const char *const *keywords,
          const char *const *values,
          int expand_dbname)
{
  PGconn     *conn = PQconnectStartParams(keywords, values, expand_dbname);

  if (conn && conn->status != CONNECTION_BAD)
    (void) connectDBComplete(conn);

  return conn;

}

/*
 *    PQpingParams
 *
 * check server status, accepting parameters identical to PQconnectdbParams
 */
PGPing
PQpingParams(const char *const *keywords,
       const char *const *values,
       int expand_dbname)
{
  PGconn     *conn = PQconnectStartParams(keywords, values, expand_dbname);
  PGPing    ret;

  ret = internal_ping(conn);
  PQfinish(conn);

  return ret;
}

/*
 *    PQconnectdb
 *
 * establishes a connection to a postgres backend through the postmaster
 * using connection information in a string.
 *
 * The conninfo string is either a whitespace-separated list of
 *
 *     option = value
 *
 * definitions or a URI (refer to the documentation for details.) Value
 * might be a single value containing no whitespaces or a single quoted
 * string. If a single quote should appear anywhere in the value, it must be
 * escaped with a backslash like \'
 *
 * Returns a PGconn* which is needed for all subsequent libpq calls, or NULL
 * if a memory allocation failed.
 * If the status field of the connection returned is CONNECTION_BAD,
 * then some fields may be null'ed out instead of having valid values.
 *
 * You should call PQfinish (if conn is not NULL) regardless of whether this
 * call succeeded.
 */
PGconn *
PQconnectdb(const char *conninfo)
{
  PGconn     *conn = PQconnectStart(conninfo);

  if (conn && conn->status != CONNECTION_BAD)
    (void) connectDBComplete(conn);

  return conn;
}

/*
 *    PQping
 *
 * check server status, accepting parameters identical to PQconnectdb
 */
PGPing
PQping(const char *conninfo)
{
  PGconn     *conn = PQconnectStart(conninfo);
  PGPing    ret;

  ret = internal_ping(conn);
  PQfinish(conn);

  return ret;
}

/*
 *    PQconnectStartParams
 *
 * Begins the establishment of a connection to a postgres backend through the
 * postmaster using connection information in a struct.
 *
 * See comment for PQconnectdbParams for the definition of the string format.
 *
 * Returns a PGconn*.  If NULL is returned, a malloc error has occurred, and
 * you should not attempt to proceed with this connection.  If the status
 * field of the connection returned is CONNECTION_BAD, an error has
 * occurred. In this case you should call PQfinish on the result, (perhaps
 * inspecting the error message first).  Other fields of the structure may not
 * be valid if that occurs.  If the status field is not CONNECTION_BAD, then
 * this stage has succeeded - call PQconnectPoll, using select(2) to see when
 * this is necessary.
 *
 * See PQconnectPoll for more info.
 */
PGconn *
PQconnectStartParams(const char *const *keywords,
           const char *const *values,
           int expand_dbname)
{
  PGconn     *conn;
  PQconninfoOption *connOptions;

  /*
   * Allocate memory for the conn structure
   */
  conn = makeEmptyPGconn();
  if (conn == NULL)
    return NULL;

  /*
   * Parse the conninfo arrays
   */
  connOptions = conninfo_array_parse(keywords, values,
                     &conn->errorMessage,
                     true, expand_dbname);
  if (connOptions == NULL)
  {
    conn->status = CONNECTION_BAD;
    /* errorMessage is already set */
    return conn;
  }

  /*
   * Move option values into conn structure
   */
  if (!fillPGconn(conn, connOptions))
  {
    PQconninfoFree(connOptions);
    return conn;
  }

  /*
   * Free the option info - all is in conn now
   */
  PQconninfoFree(connOptions);

  /*
   * Compute derived options
   */
  if (!connectOptions2(conn))
    return conn;

  /*
   * Connect to the database
   */
  if (!connectDBStart(conn))
  {
    /* Just in case we failed to set it in connectDBStart */
    conn->status = CONNECTION_BAD;
  }

  return conn;
}

/*
 *    PQconnectStart
 *
 * Begins the establishment of a connection to a postgres backend through the
 * postmaster using connection information in a string.
 *
 * See comment for PQconnectdb for the definition of the string format.
 *
 * Returns a PGconn*.  If NULL is returned, a malloc error has occurred, and
 * you should not attempt to proceed with this connection.  If the status
 * field of the connection returned is CONNECTION_BAD, an error has
 * occurred. In this case you should call PQfinish on the result, (perhaps
 * inspecting the error message first).  Other fields of the structure may not
 * be valid if that occurs.  If the status field is not CONNECTION_BAD, then
 * this stage has succeeded - call PQconnectPoll, using select(2) to see when
 * this is necessary.
 *
 * See PQconnectPoll for more info.
 */
PGconn *
PQconnectStart(const char *conninfo)
{
  PGconn     *conn;

  /*
   * Allocate memory for the conn structure
   */
  conn = makeEmptyPGconn();
  if (conn == NULL)
    return NULL;

  /*
   * Parse the conninfo string
   */
  if (!connectOptions1(conn, conninfo))
    return conn;

  /*
   * Compute derived options
   */
  if (!connectOptions2(conn))
    return conn;

  /*
   * Connect to the database
   */
  if (!connectDBStart(conn))
  {
    /* Just in case we failed to set it in connectDBStart */
    conn->status = CONNECTION_BAD;
  }

  return conn;
}

/*
 * Move option values into conn structure
 *
 * Don't put anything cute here --- intelligence should be in
 * connectOptions2 ...
 *
 * Returns true on success. On failure, returns false and sets error message.
 */
static bool
fillPGconn(PGconn *conn, PQconninfoOption *connOptions)
{
  const internalPQconninfoOption *option;

  for (option = PQconninfoOptions; option->keyword; option++)
  {
    if (option->connofs >= 0)
    {
      const char *tmp = conninfo_getval(connOptions, option->keyword);

      if (tmp)
      {
        char    **connmember = (char **) ((char *) conn + option->connofs);

        if (*connmember)
          free(*connmember);
        *connmember = strdup(tmp);
        if (*connmember == NULL)
        {
          printfPQExpBuffer(&conn->errorMessage,
                    libpq_gettext("out of memory\n"));
          return false;
        }
      }
    }
  }

  return true;
}

/*
 *    connectOptions1
 *
 * Internal subroutine to set up connection parameters given an already-
 * created PGconn and a conninfo string.  Derived settings should be
 * processed by calling connectOptions2 next.  (We split them because
 * PQsetdbLogin overrides defaults in between.)
 *
 * Returns true if OK, false if trouble (in which case errorMessage is set
 * and so is conn->status).
 */
static bool
connectOptions1(PGconn *conn, const char *conninfo)
{
  PQconninfoOption *connOptions;

  /*
   * Parse the conninfo string
   */
  connOptions = parse_connection_string(conninfo, &conn->errorMessage, true);
  if (connOptions == NULL)
  {
    conn->status = CONNECTION_BAD;
    /* errorMessage is already set */
    return false;
  }

  /*
   * Move option values into conn structure
   */
  if (!fillPGconn(conn, connOptions))
  {
    conn->status = CONNECTION_BAD;
    PQconninfoFree(connOptions);
    return false;
  }

  /*
   * Free the option info - all is in conn now
   */
  PQconninfoFree(connOptions);

  return true;
}

/*
 * Count the number of elements in a simple comma-separated list.
 */
static int
count_comma_separated_elems(const char *input)
{
  int     n;

  n = 1;
  for (; *input != '\0'; input++)
  {
    if (*input == ',')
      n++;
  }

  return n;
}

/*
 * Parse a simple comma-separated list.
 *
 * On each call, returns a malloc'd copy of the next element, and sets *more
 * to indicate whether there are any more elements in the list after this,
 * and updates *startptr to point to the next element, if any.
 *
 * On out of memory, returns NULL.
 */
static char *
parse_comma_separated_list(char **startptr, bool *more)
{
  char     *p;
  char     *s = *startptr;
  char     *e;
  int     len;

  /*
   * Search for the end of the current element; a comma or end-of-string
   * acts as a terminator.
   */
  e = s;
  while (*e != '\0' && *e != ',')
    ++e;
  *more = (*e == ',');

  len = e - s;
  p = (char *) malloc(sizeof(char) * (len + 1));
  if (p)
  {
    memcpy(p, s, len);
    p[len] = '\0';
  }
  *startptr = e + 1;

  return p;
}

/*
 *    connectOptions2
 *
 * Compute derived connection options after absorbing all user-supplied info.
 *
 * Returns true if OK, false if trouble (in which case errorMessage is set
 * and so is conn->status).
 */
static bool
connectOptions2(PGconn *conn)
{
  int     i;

  /*
   * Allocate memory for details about each host to which we might possibly
   * try to connect.  For that, count the number of elements in the hostaddr
   * or host options.  If neither is given, assume one host.
   */
  conn->whichhost = 0;
  if (conn->pghostaddr && conn->pghostaddr[0] != '\0')
    conn->nconnhost = count_comma_separated_elems(conn->pghostaddr);
  else if (conn->pghost && conn->pghost[0] != '\0')
    conn->nconnhost = count_comma_separated_elems(conn->pghost);
  else
    conn->nconnhost = 1;
  conn->connhost = (pg_conn_host *)
    calloc(conn->nconnhost, sizeof(pg_conn_host));
  if (conn->connhost == NULL)
    goto oom_error;

  /*
   * We now have one pg_conn_host structure per possible host.  Fill in the
   * host and hostaddr fields for each, by splitting the parameter strings.
   */
  if (conn->pghostaddr != NULL && conn->pghostaddr[0] != '\0')
  {
    char     *s = conn->pghostaddr;
    bool    more = true;

    for (i = 0; i < conn->nconnhost && more; i++)
    {
      conn->connhost[i].hostaddr = parse_comma_separated_list(&s, &more);
      if (conn->connhost[i].hostaddr == NULL)
        goto oom_error;
    }

    /*
     * If hostaddr was given, the array was allocated according to the
     * number of elements in the hostaddr list, so it really should be the
     * right size.
     */
    Assert(!more);
    Assert(i == conn->nconnhost);
  }

  if (conn->pghost != NULL && conn->pghost[0] != '\0')
  {
    char     *s = conn->pghost;
    bool    more = true;

    for (i = 0; i < conn->nconnhost && more; i++)
    {
      conn->connhost[i].host = parse_comma_separated_list(&s, &more);
      if (conn->connhost[i].host == NULL)
        goto oom_error;
    }

    /* Check for wrong number of host items. */
    if (more || i != conn->nconnhost)
    {
      conn->status = CONNECTION_BAD;
      printfPQExpBuffer(&conn->errorMessage,
                libpq_gettext("could not match %d host names to %d hostaddr values\n"),
                count_comma_separated_elems(conn->pghost), conn->nconnhost);
      return false;
    }
  }

  /*
   * Now, for each host slot, identify the type of address spec, and fill in
   * the default address if nothing was given.
   */
  for (i = 0; i < conn->nconnhost; i++)
  {
    pg_conn_host *ch = &conn->connhost[i];

    if (ch->hostaddr != NULL && ch->hostaddr[0] != '\0')
      ch->type = CHT_HOST_ADDRESS;
    else if (ch->host != NULL && ch->host[0] != '\0')
    {
      ch->type = CHT_HOST_NAME;
#ifdef HAVE_UNIX_SOCKETS
      if (is_absolute_path(ch->host))
        ch->type = CHT_UNIX_SOCKET;
#endif
    }
    else
    {
      if (ch->host)
        free(ch->host);

/* YugaByte use localhost instead of local socket */
#pragma push_macro("HAVE_UNIX_SOCKETS")
#undef HAVE_UNIX_SOCKETS

#ifdef HAVE_UNIX_SOCKETS
      ch->host = strdup(DEFAULT_PGSOCKET_DIR);
      ch->type = CHT_UNIX_SOCKET;
#else
      ch->host = strdup(DefaultHost);
      ch->type = CHT_HOST_NAME;
#endif

#pragma pop_macro("HAVE_UNIX_SOCKETS")
/* YugaByte end */

      if (ch->host == NULL)
        goto oom_error;
    }
  }

  /*
   * Next, work out the port number corresponding to each host name.
   *
   * Note: unlike the above for host names, this could leave the port fields
   * as null or empty strings.  We will substitute DEF_PGPORT whenever we
   * read such a port field.
   */
  if (conn->pgport != NULL && conn->pgport[0] != '\0')
  {
    char     *s = conn->pgport;
    bool    more = true;

    for (i = 0; i < conn->nconnhost && more; i++)
    {
      conn->connhost[i].port = parse_comma_separated_list(&s, &more);
      if (conn->connhost[i].port == NULL)
        goto oom_error;
    }

    /*
     * If exactly one port was given, use it for every host.  Otherwise,
     * there must be exactly as many ports as there were hosts.
     */
    if (i == 1 && !more)
    {
      for (i = 1; i < conn->nconnhost; i++)
      {
        conn->connhost[i].port = strdup(conn->connhost[0].port);
        if (conn->connhost[i].port == NULL)
          goto oom_error;
      }
    }
    else if (more || i != conn->nconnhost)
    {
      conn->status = CONNECTION_BAD;
      printfPQExpBuffer(&conn->errorMessage,
                libpq_gettext("could not match %d port numbers to %d hosts\n"),
                count_comma_separated_elems(conn->pgport), conn->nconnhost);
      return false;
    }
  }

  /*
   * If user name was not given, fetch it.  (Most likely, the fetch will
   * fail, since the only way we get here is if pg_fe_getauthname() failed
   * during conninfo_add_defaults().  But now we want an error message.)
   */
  if (conn->pguser == NULL || conn->pguser[0] == '\0')
  {
    if (conn->pguser)
      free(conn->pguser);
    /* YugaByte default username to "postgres" */
    conn->pguser = strdup("postgres");
    if (!conn->pguser)
    {
      conn->status = CONNECTION_BAD;
      return false;
    }
  }

  /*
   * If database name was not given, default it to equal user name
   */
  if (conn->dbName == NULL || conn->dbName[0] == '\0')
  {
    if (conn->dbName)
      free(conn->dbName);
    conn->dbName = strdup("yugabyte");
    if (!conn->dbName)
      goto oom_error;
  }

  /*
   * If password was not given, try to look it up in password file.  Note
   * that the result might be different for each host/port pair.
   */
  if (conn->pgpass == NULL || conn->pgpass[0] == '\0')
  {
    /* If password file wasn't specified, use ~/PGPASSFILE */
    if (conn->pgpassfile == NULL || conn->pgpassfile[0] == '\0')
    {
      char    homedir[MAXPGPATH];

      if (pqGetHomeDirectory(homedir, sizeof(homedir)))
      {
        if (conn->pgpassfile)
          free(conn->pgpassfile);
        conn->pgpassfile = malloc(MAXPGPATH);
        if (!conn->pgpassfile)
          goto oom_error;
        snprintf(conn->pgpassfile, MAXPGPATH, "%s/%s",
             homedir, PGPASSFILE);
      }
    }

    if (conn->pgpassfile != NULL && conn->pgpassfile[0] != '\0')
    {
      for (i = 0; i < conn->nconnhost; i++)
      {
        /*
         * Try to get a password for this host from file.  We use host
         * for the hostname search key if given, else hostaddr (at
         * least one of them is guaranteed nonempty by now).
         */
        const char *pwhost = conn->connhost[i].host;

        if (pwhost == NULL || pwhost[0] == '\0')
          pwhost = conn->connhost[i].hostaddr;

        conn->connhost[i].password =
          passwordFromFile(pwhost,
                   conn->connhost[i].port,
                   conn->dbName,
                   conn->pguser,
                   conn->pgpassfile);
      }
    }
  }

  /*
   * validate sslmode option
   */
  if (conn->sslmode)
  {
    if (strcmp(conn->sslmode, "disable") != 0
      && strcmp(conn->sslmode, "allow") != 0
      && strcmp(conn->sslmode, "prefer") != 0
      && strcmp(conn->sslmode, "require") != 0
      && strcmp(conn->sslmode, "verify-ca") != 0
      && strcmp(conn->sslmode, "verify-full") != 0)
    {
      conn->status = CONNECTION_BAD;
      printfPQExpBuffer(&conn->errorMessage,
                libpq_gettext("invalid sslmode value: \"%s\"\n"),
                conn->sslmode);
      return false;
    }

#ifndef USE_SSL
    switch (conn->sslmode[0])
    {
      case 'a':     /* "allow" */
      case 'p':     /* "prefer" */

        /*
         * warn user that an SSL connection will never be negotiated
         * since SSL was not compiled in?
         */
        break;

      case 'r':     /* "require" */
      case 'v':     /* "verify-ca" or "verify-full" */
        conn->status = CONNECTION_BAD;
        printfPQExpBuffer(&conn->errorMessage,
                  libpq_gettext("sslmode value \"%s\" invalid when SSL support is not compiled in\n"),
                  conn->sslmode);
        return false;
    }
#endif
  }
  else
  {
    conn->sslmode = strdup(DefaultSSLMode);
    if (!conn->sslmode)
      goto oom_error;
  }

  /*
   * Resolve special "auto" client_encoding from the locale
   */
  if (conn->client_encoding_initial &&
    strcmp(conn->client_encoding_initial, "auto") == 0)
  {
    free(conn->client_encoding_initial);
    conn->client_encoding_initial = strdup(pg_encoding_to_char(pg_get_encoding_from_locale(NULL, true)));
    if (!conn->client_encoding_initial)
      goto oom_error;
  }

  /*
   * Validate target_session_attrs option.
   */
  if (conn->target_session_attrs)
  {
    if (strcmp(conn->target_session_attrs, "any") != 0
      && strcmp(conn->target_session_attrs, "read-write") != 0)
    {
      conn->status = CONNECTION_BAD;
      printfPQExpBuffer(&conn->errorMessage,
                libpq_gettext("invalid target_session_attrs value: \"%s\"\n"),
                conn->target_session_attrs);
      return false;
    }
  }

  /*
   * Only if we get this far is it appropriate to try to connect. (We need a
   * state flag, rather than just the boolean result of this function, in
   * case someone tries to PQreset() the PGconn.)
   */
  conn->options_valid = true;

  return true;

oom_error:
  conn->status = CONNECTION_BAD;
  printfPQExpBuffer(&conn->errorMessage,
            libpq_gettext("out of memory\n"));
  return false;
}

/*
 *    PQconndefaults
 *
 * Construct a default connection options array, which identifies all the
 * available options and shows any default values that are available from the
 * environment etc.  On error (eg out of memory), NULL is returned.
 *
 * Using this function, an application may determine all possible options
 * and their current default values.
 *
 * NOTE: as of PostgreSQL 7.0, the returned array is dynamically allocated
 * and should be freed when no longer needed via PQconninfoFree().  (In prior
 * versions, the returned array was static, but that's not thread-safe.)
 * Pre-7.0 applications that use this function will see a small memory leak
 * until they are updated to call PQconninfoFree.
 */
PQconninfoOption *
PQconndefaults(void)
{
  PQExpBufferData errorBuf;
  PQconninfoOption *connOptions;

  /* We don't actually report any errors here, but callees want a buffer */
  initPQExpBuffer(&errorBuf);
  if (PQExpBufferDataBroken(errorBuf))
    return NULL;     /* out of memory already :-( */

  connOptions = conninfo_init(&errorBuf);
  if (connOptions != NULL)
  {
    /* pass NULL errorBuf to ignore errors */
    if (!conninfo_add_defaults(connOptions, NULL))
    {
      PQconninfoFree(connOptions);
      connOptions = NULL;
    }
  }

  termPQExpBuffer(&errorBuf);
  return connOptions;
}

/* ----------------
 *    PQsetdbLogin
 *
 * establishes a connection to a postgres backend through the postmaster
 * at the specified host and port.
 *
 * returns a PGconn* which is needed for all subsequent libpq calls
 *
 * if the status field of the connection returned is CONNECTION_BAD,
 * then only the errorMessage is likely to be useful.
 * ----------------
 */
PGconn *
PQsetdbLogin(const char *pghost, const char *pgport, const char *pgoptions,
       const char *pgtty, const char *dbName, const char *login,
       const char *pwd)
{
  PGconn     *conn;

  /*
   * Allocate memory for the conn structure
   */
  conn = makeEmptyPGconn();
  if (conn == NULL)
    return NULL;

  /*
   * If the dbName parameter contains what looks like a connection string,
   * parse it into conn struct using connectOptions1.
   */
  if (dbName && recognized_connection_string(dbName))
  {
    if (!connectOptions1(conn, dbName))
      return conn;
  }
  else
  {
    /*
     * Old-style path: first, parse an empty conninfo string in order to
     * set up the same defaults that PQconnectdb() would use.
     */
    if (!connectOptions1(conn, ""))
      return conn;

    /* Insert dbName parameter value into struct */
    if (dbName && dbName[0] != '\0')
    {
      if (conn->dbName)
        free(conn->dbName);
      conn->dbName = strdup(dbName);
      if (!conn->dbName)
        goto oom_error;
    }
  }

  /*
   * Insert remaining parameters into struct, overriding defaults (as well
   * as any conflicting data from dbName taken as a conninfo).
   */
  if (pghost && pghost[0] != '\0')
  {
    if (conn->pghost)
      free(conn->pghost);
    conn->pghost = strdup(pghost);
    if (!conn->pghost)
      goto oom_error;
  }

  if (pgport && pgport[0] != '\0')
  {
    if (conn->pgport)
      free(conn->pgport);
    conn->pgport = strdup(pgport);
    if (!conn->pgport)
      goto oom_error;
  }

  if (pgoptions && pgoptions[0] != '\0')
  {
    if (conn->pgoptions)
      free(conn->pgoptions);
    conn->pgoptions = strdup(pgoptions);
    if (!conn->pgoptions)
      goto oom_error;
  }

  if (pgtty && pgtty[0] != '\0')
  {
    if (conn->pgtty)
      free(conn->pgtty);
    conn->pgtty = strdup(pgtty);
    if (!conn->pgtty)
      goto oom_error;
  }

  if (login && login[0] != '\0')
  {
    if (conn->pguser)
      free(conn->pguser);
    conn->pguser = strdup(login);
    if (!conn->pguser)
      goto oom_error;
  }

  if (pwd && pwd[0] != '\0')
  {
    if (conn->pgpass)
      free(conn->pgpass);
    conn->pgpass = strdup(pwd);
    if (!conn->pgpass)
      goto oom_error;
  }

  /*
   * Compute derived options
   */
  if (!connectOptions2(conn))
    return conn;

  /*
   * Connect to the database
   */
  if (connectDBStart(conn))
    (void) connectDBComplete(conn);

  return conn;

oom_error:
  conn->status = CONNECTION_BAD;
  printfPQExpBuffer(&conn->errorMessage,
            libpq_gettext("out of memory\n"));
  return conn;
}


/* ----------
 * connectNoDelay -
 * Sets the TCP_NODELAY socket option.
 * Returns 1 if successful, 0 if not.
 * ----------
 */
static int
connectNoDelay(PGconn *conn)
{
#ifdef  TCP_NODELAY
  int     on = 1;

  if (setsockopt(conn->sock, IPPROTO_TCP, TCP_NODELAY,
           (char *) &on,
           sizeof(on)) < 0)
  {
    char    sebuf[256];

    appendPQExpBuffer(&conn->errorMessage,
              libpq_gettext("could not set socket to TCP no delay mode: %s\n"),
              SOCK_STRERROR(SOCK_ERRNO, sebuf, sizeof(sebuf)));
    return 0;
  }
#endif

  return 1;
}


/* ----------
 * connectFailureMessage -
 * create a friendly error message on connection failure.
 * ----------
 */
static void
connectFailureMessage(PGconn *conn, int errorno)
{
  char    sebuf[256];

#ifdef HAVE_UNIX_SOCKETS
  if (IS_AF_UNIX(conn->raddr.addr.ss_family))
  {
    char    service[NI_MAXHOST];

    pg_getnameinfo_all(&conn->raddr.addr, conn->raddr.salen,
               NULL, 0,
               service, sizeof(service),
               NI_NUMERICSERV);
    appendPQExpBuffer(&conn->errorMessage,
              libpq_gettext("could not connect to server: %s\n"
                    "\tIs the server running locally and accepting\n"
                    "\tconnections on Unix domain socket \"%s\"?\n"),
              SOCK_STRERROR(errorno, sebuf, sizeof(sebuf)),
              service);
  }
  else
#endif              /* HAVE_UNIX_SOCKETS */
  {
    char    host_addr[NI_MAXHOST];
    const char *displayed_host;
    const char *displayed_port;
    struct sockaddr_storage *addr = &conn->raddr.addr;

    /*
     * Optionally display the network address with the hostname. This is
     * useful to distinguish between IPv4 and IPv6 connections.
     */
    if (conn->connhost[conn->whichhost].type == CHT_HOST_ADDRESS)
      strlcpy(host_addr, conn->connhost[conn->whichhost].hostaddr, NI_MAXHOST);
    else if (addr->ss_family == AF_INET)
    {
      if (inet_net_ntop(AF_INET,
                &((struct sockaddr_in *) addr)->sin_addr.s_addr,
                32,
                host_addr, sizeof(host_addr)) == NULL)
        strcpy(host_addr, "???");
    }
#ifdef HAVE_IPV6
    else if (addr->ss_family == AF_INET6)
    {
      if (inet_net_ntop(AF_INET6,
                &((struct sockaddr_in6 *) addr)->sin6_addr.s6_addr,
                128,
                host_addr, sizeof(host_addr)) == NULL)
        strcpy(host_addr, "???");
    }
#endif
    else
      strcpy(host_addr, "???");

    /* To which host and port were we actually connecting? */
    if (conn->connhost[conn->whichhost].type == CHT_HOST_ADDRESS)
      displayed_host = conn->connhost[conn->whichhost].hostaddr;
    else
      displayed_host = conn->connhost[conn->whichhost].host;
    displayed_port = conn->connhost[conn->whichhost].port;
    if (displayed_port == NULL || displayed_port[0] == '\0')
      /* Use YugaByte default port */
      displayed_port = DEF_YBPORT_STR;

    /*
     * If the user did not supply an IP address using 'hostaddr', and
     * 'host' was missing or does not match our lookup, display the
     * looked-up IP address.
     */
    if (conn->connhost[conn->whichhost].type != CHT_HOST_ADDRESS &&
      strcmp(displayed_host, host_addr) != 0)
      appendPQExpBuffer(&conn->errorMessage,
                libpq_gettext("could not connect to server: %s\n"
                      "\tIs the server running on host \"%s\" (%s) and accepting\n"
                      "\tTCP/IP connections on port %s?\n"),
                SOCK_STRERROR(errorno, sebuf, sizeof(sebuf)),
                displayed_host,
                host_addr,
                displayed_port);
    else
      appendPQExpBuffer(&conn->errorMessage,
                libpq_gettext("could not connect to server: %s\n"
                      "\tIs the server running on host \"%s\" and accepting\n"
                      "\tTCP/IP connections on port %s?\n"),
                SOCK_STRERROR(errorno, sebuf, sizeof(sebuf)),
                displayed_host,
                displayed_port);
  }
}

/*
 * Should we use keepalives?  Returns 1 if yes, 0 if no, and -1 if
 * conn->keepalives is set to a value which is not parseable as an
 * integer.
 */
static int
useKeepalives(PGconn *conn)
{
  char     *ep;
  int     val;

  if (conn->keepalives == NULL)
    return 1;
  val = strtol(conn->keepalives, &ep, 10);
  if (*ep)
    return -1;
  return val != 0 ? 1 : 0;
}

#ifndef WIN32
/*
 * Set the keepalive idle timer.
 */
static int
setKeepalivesIdle(PGconn *conn)
{
  int     idle;

  if (conn->keepalives_idle == NULL)
    return 1;

  idle = atoi(conn->keepalives_idle);
  if (idle < 0)
    idle = 0;

#ifdef PG_TCP_KEEPALIVE_IDLE
  if (setsockopt(conn->sock, IPPROTO_TCP, PG_TCP_KEEPALIVE_IDLE,
           (char *) &idle, sizeof(idle)) < 0)
  {
    char    sebuf[256];

    appendPQExpBuffer(&conn->errorMessage,
              libpq_gettext("setsockopt(%s) failed: %s\n"),
              PG_TCP_KEEPALIVE_IDLE_STR,
              SOCK_STRERROR(SOCK_ERRNO, sebuf, sizeof(sebuf)));
    return 0;
  }
#endif

  return 1;
}

/*
 * Set the keepalive interval.
 */
static int
setKeepalivesInterval(PGconn *conn)
{
  int     interval;

  if (conn->keepalives_interval == NULL)
    return 1;

  interval = atoi(conn->keepalives_interval);
  if (interval < 0)
    interval = 0;

#ifdef TCP_KEEPINTVL
  if (setsockopt(conn->sock, IPPROTO_TCP, TCP_KEEPINTVL,
           (char *) &interval, sizeof(interval)) < 0)
  {
    char    sebuf[256];

    appendPQExpBuffer(&conn->errorMessage,
              libpq_gettext("setsockopt(%s) failed: %s\n"),
              "TCP_KEEPINTVL",
              SOCK_STRERROR(SOCK_ERRNO, sebuf, sizeof(sebuf)));
    return 0;
  }
#endif

  return 1;
}

/*
 * Set the count of lost keepalive packets that will trigger a connection
 * break.
 */
static int
setKeepalivesCount(PGconn *conn)
{
  int     count;

  if (conn->keepalives_count == NULL)
    return 1;

  count = atoi(conn->keepalives_count);
  if (count < 0)
    count = 0;

#ifdef TCP_KEEPCNT
  if (setsockopt(conn->sock, IPPROTO_TCP, TCP_KEEPCNT,
           (char *) &count, sizeof(count)) < 0)
  {
    char    sebuf[256];

    appendPQExpBuffer(&conn->errorMessage,
              libpq_gettext("setsockopt(%s) failed: %s\n"),
              "TCP_KEEPCNT",
              SOCK_STRERROR(SOCK_ERRNO, sebuf, sizeof(sebuf)));
    return 0;
  }
#endif

  return 1;
}
#else             /* WIN32 */
#ifdef SIO_KEEPALIVE_VALS
/*
 * Enable keepalives and set the keepalive values on Win32,
 * where they are always set in one batch.
 */
static int
setKeepalivesWin32(PGconn *conn)
{
  struct tcp_keepalive ka;
  DWORD   retsize;
  int     idle = 0;
  int     interval = 0;

  if (conn->keepalives_idle)
    idle = atoi(conn->keepalives_idle);
  if (idle <= 0)
    idle = 2 * 60 * 60;   /* 2 hours = default */

  if (conn->keepalives_interval)
    interval = atoi(conn->keepalives_interval);
  if (interval <= 0)
    interval = 1;     /* 1 second = default */

  ka.onoff = 1;
  ka.keepalivetime = idle * 1000;
  ka.keepaliveinterval = interval * 1000;

  if (WSAIoctl(conn->sock,
         SIO_KEEPALIVE_VALS,
         (LPVOID) &ka,
         sizeof(ka),
         NULL,
         0,
         &retsize,
         NULL,
         NULL)
    != 0)
  {
    appendPQExpBuffer(&conn->errorMessage,
              libpq_gettext("WSAIoctl(SIO_KEEPALIVE_VALS) failed: %ui\n"),
              WSAGetLastError());
    return 0;
  }
  return 1;
}
#endif              /* SIO_KEEPALIVE_VALS */
#endif              /* WIN32 */

/* ----------
 * connectDBStart -
 *    Begin the process of making a connection to the backend.
 *
 * Returns 1 if successful, 0 if not.
 * ----------
 */
static int
connectDBStart(PGconn *conn)
{
  if (!conn)
    return 0;

  if (!conn->options_valid)
    goto connect_errReturn;

  /* Ensure our buffers are empty */
  conn->inStart = conn->inCursor = conn->inEnd = 0;
  conn->outCount = 0;

  /*
   * Ensure errorMessage is empty, too.  PQconnectPoll will append messages
   * to it in the process of scanning for a working server.  Thus, if we
   * fail to connect to multiple hosts, the final error message will include
   * details about each failure.
   */
  resetPQExpBuffer(&conn->errorMessage);

  /*
   * Set up to try to connect to the first host.  (Setting whichhost = -1 is
   * a bit of a cheat, but PQconnectPoll will advance it to 0 before
   * anything else looks at it.)
   */
  conn->whichhost = -1;
  conn->try_next_addr = false;
  conn->try_next_host = true;
  conn->status = CONNECTION_NEEDED;

  /*
   * The code for processing CONNECTION_NEEDED state is in PQconnectPoll(),
   * so that it can easily be re-executed if needed again during the
   * asynchronous startup process.  However, we must run it once here,
   * because callers expect a success return from this routine to mean that
   * we are in PGRES_POLLING_WRITING connection state.
   */
  if (PQconnectPoll(conn) == PGRES_POLLING_WRITING)
    return 1;

connect_errReturn:

  /*
   * If we managed to open a socket, close it immediately rather than
   * waiting till PQfinish.  (The application cannot have gotten the socket
   * from PQsocket yet, so this doesn't risk breaking anything.)
   */
  pqDropConnection(conn, true);
  conn->status = CONNECTION_BAD;
  return 0;
}


/*
 *    connectDBComplete
 *
 * Block and complete a connection.
 *
 * Returns 1 on success, 0 on failure.
 */
static int
connectDBComplete(PGconn *conn)
{
  PostgresPollingStatusType flag = PGRES_POLLING_WRITING;
  time_t    finish_time = ((time_t) -1);
  int     timeout = 0;
  int     last_whichhost = -2;  /* certainly different from whichhost */
  struct addrinfo *last_addr_cur = NULL;

  if (conn == NULL || conn->status == CONNECTION_BAD)
    return 0;

  /*
   * Set up a time limit, if connect_timeout isn't zero.
   */
  if (conn->connect_timeout != NULL)
  {
    timeout = atoi(conn->connect_timeout);
    if (timeout > 0)
    {
      /*
       * Rounding could cause connection to fail unexpectedly quickly;
       * to prevent possibly waiting hardly-at-all, insist on at least
       * two seconds.
       */
      if (timeout < 2)
        timeout = 2;
    }
  }

  for (;;)
  {
    int     ret = 0;

    /*
     * (Re)start the connect_timeout timer if it's active and we are
     * considering a different host than we were last time through.  If
     * we've already succeeded, though, needn't recalculate.
     */
    if (flag != PGRES_POLLING_OK &&
      timeout > 0 &&
      (conn->whichhost != last_whichhost ||
       conn->addr_cur != last_addr_cur))
    {
      finish_time = time(NULL) + timeout;
      last_whichhost = conn->whichhost;
      last_addr_cur = conn->addr_cur;
    }

    /*
     * Wait, if necessary.  Note that the initial state (just after
     * PQconnectStart) is to wait for the socket to select for writing.
     */
    switch (flag)
    {
      case PGRES_POLLING_OK:

        /*
         * Reset stored error messages since we now have a working
         * connection
         */
        resetPQExpBuffer(&conn->errorMessage);
        return 1;   /* success! */

      case PGRES_POLLING_READING:
        ret = pqWaitTimed(1, 0, conn, finish_time);
        if (ret == -1)
        {
          /* hard failure, eg select() problem, aborts everything */
          conn->status = CONNECTION_BAD;
          return 0;
        }
        break;

      case PGRES_POLLING_WRITING:
        ret = pqWaitTimed(0, 1, conn, finish_time);
        if (ret == -1)
        {
          /* hard failure, eg select() problem, aborts everything */
          conn->status = CONNECTION_BAD;
          return 0;
        }
        break;

      default:
        /* Just in case we failed to set it in PQconnectPoll */
        conn->status = CONNECTION_BAD;
        return 0;
    }

    if (ret == 1)      /* connect_timeout elapsed */
    {
      /*
       * Give up on current server/address, try the next one.
       */
      conn->try_next_addr = true;
      conn->status = CONNECTION_NEEDED;
    }

    /*
     * Now try to advance the state machine.
     */
    flag = PQconnectPoll(conn);
  }
}

/*
 * This subroutine saves conn->errorMessage, which will be restored back by
 * restoreErrorMessage subroutine.  Returns false on OOM failure.
 */
static bool
saveErrorMessage(PGconn *conn, PQExpBuffer savedMessage)
{
  initPQExpBuffer(savedMessage);
  appendPQExpBufferStr(savedMessage,
             conn->errorMessage.data);
  if (PQExpBufferBroken(savedMessage))
  {
    printfPQExpBuffer(&conn->errorMessage,
              libpq_gettext("out of memory\n"));
    return false;
  }
  /* Clear whatever is in errorMessage now */
  resetPQExpBuffer(&conn->errorMessage);
  return true;
}

/*
 * Restores saved error messages back to conn->errorMessage, prepending them
 * to whatever is in conn->errorMessage already.  (This does the right thing
 * if anything's been added to conn->errorMessage since saveErrorMessage.)
 */
static void
restoreErrorMessage(PGconn *conn, PQExpBuffer savedMessage)
{
  appendPQExpBufferStr(savedMessage, conn->errorMessage.data);
  resetPQExpBuffer(&conn->errorMessage);
  appendPQExpBufferStr(&conn->errorMessage, savedMessage->data);
  /* If any step above hit OOM, just report that */
  if (PQExpBufferBroken(savedMessage) ||
    PQExpBufferBroken(&conn->errorMessage))
    printfPQExpBuffer(&conn->errorMessage,
              libpq_gettext("out of memory\n"));
  termPQExpBuffer(savedMessage);
}

/* ----------------
 *    PQconnectPoll
 *
 * Poll an asynchronous connection.
 *
 * Returns a PostgresPollingStatusType.
 * Before calling this function, use select(2) to determine when data
 * has arrived..
 *
 * You must call PQfinish whether or not this fails.
 *
 * This function and PQconnectStart are intended to allow connections to be
 * made without blocking the execution of your program on remote I/O. However,
 * there are a number of caveats:
 *
 *   o  If you call PQtrace, ensure that the stream object into which you trace
 *    will not block.
 *   o  If you do not supply an IP address for the remote host (i.e. you
 *    supply a host name instead) then PQconnectStart will block on
 *    gethostbyname.  You will be fine if using Unix sockets (i.e. by
 *    supplying neither a host name nor a host address).
 *   o  If your backend wants to use Kerberos authentication then you must
 *    supply both a host name and a host address, otherwise this function
 *    may block on gethostname.
 *
 * ----------------
 */
PostgresPollingStatusType
PQconnectPoll(PGconn *conn)
{
  bool    reset_connection_state_machine = false;
  bool    need_new_connection = false;
  PGresult   *res;
  char    sebuf[256];
  int     optval;
  PQExpBufferData savedMessage;

  if (conn == NULL)
    return PGRES_POLLING_FAILED;

  /* Get the new data */
  switch (conn->status)
  {
      /*
       * We really shouldn't have been polled in these two cases, but we
       * can handle it.
       */
    case CONNECTION_BAD:
      return PGRES_POLLING_FAILED;
    case CONNECTION_OK:
      return PGRES_POLLING_OK;

      /* These are reading states */
    case CONNECTION_AWAITING_RESPONSE:
    case CONNECTION_AUTH_OK:
      {
        /* Load waiting data */
        int     n = pqReadData(conn);

        if (n < 0)
          goto error_return;
        if (n == 0)
          return PGRES_POLLING_READING;

        break;
      }

      /* These are writing states, so we just proceed. */
    case CONNECTION_STARTED:
    case CONNECTION_MADE:
      break;

      /* We allow pqSetenvPoll to decide whether to proceed. */
    case CONNECTION_SETENV:
      break;

      /* Special cases: proceed without waiting. */
    case CONNECTION_SSL_STARTUP:
    case CONNECTION_NEEDED:
    case CONNECTION_CHECK_WRITABLE:
    case CONNECTION_CONSUME:
      break;

    default:
      appendPQExpBufferStr(&conn->errorMessage,
                 libpq_gettext(
                         "invalid connection state, "
                         "probably indicative of memory corruption\n"
                         ));
      goto error_return;
  }


keep_going:           /* We will come back to here until there is
                 * nothing left to do. */

  /* Time to advance to next address, or next host if no more addresses? */
  if (conn->try_next_addr)
  {
    if (conn->addr_cur && conn->addr_cur->ai_next)
    {
      conn->addr_cur = conn->addr_cur->ai_next;
      reset_connection_state_machine = true;
    }
    else
      conn->try_next_host = true;
    conn->try_next_addr = false;
  }

  /* Time to advance to next connhost[] entry? */
  if (conn->try_next_host)
  {
    pg_conn_host *ch;
    struct addrinfo hint;
    int     thisport;
    int     ret;
    char    portstr[MAXPGPATH];

    if (conn->whichhost + 1 >= conn->nconnhost)
    {
      /*
       * Oops, no more hosts.  An appropriate error message is already
       * set up, so just set the right status.
       */
      goto error_return;
    }
    conn->whichhost++;

    /* Drop any address info for previous host */
    release_conn_addrinfo(conn);

    /*
     * Look up info for the new host.  On failure, log the problem in
     * conn->errorMessage, then loop around to try the next host.  (Note
     * we don't clear try_next_host until we've succeeded.)
     */
    ch = &conn->connhost[conn->whichhost];

    /* Initialize hint structure */
    MemSet(&hint, 0, sizeof(hint));
    hint.ai_socktype = SOCK_STREAM;
    conn->addrlist_family = hint.ai_family = AF_UNSPEC;

    /* Figure out the port number we're going to use. */
    if (ch->port == NULL || ch->port[0] == '\0')
      /* Use YugaByte default port */
      thisport = DEF_YBPORT;
    else
    {
      thisport = atoi(ch->port);
      if (thisport < 1 || thisport > 65535)
      {
        appendPQExpBuffer(&conn->errorMessage,
                  libpq_gettext("invalid port number: \"%s\"\n"),
                  ch->port);
        goto keep_going;
      }
    }
    snprintf(portstr, sizeof(portstr), "%d", thisport);

    /* Use pg_getaddrinfo_all() to resolve the address */
    switch (ch->type)
    {
      case CHT_HOST_NAME:
        ret = pg_getaddrinfo_all(ch->host, portstr, &hint,
                     &conn->addrlist);
        if (ret || !conn->addrlist)
        {
          appendPQExpBuffer(&conn->errorMessage,
                    libpq_gettext("could not translate host name \"%s\" to address: %s\n"),
                    ch->host, gai_strerror(ret));
          goto keep_going;
        }
        break;

      case CHT_HOST_ADDRESS:
        hint.ai_flags = AI_NUMERICHOST;
        ret = pg_getaddrinfo_all(ch->hostaddr, portstr, &hint,
                     &conn->addrlist);
        if (ret || !conn->addrlist)
        {
          appendPQExpBuffer(&conn->errorMessage,
                    libpq_gettext("could not parse network address \"%s\": %s\n"),
                    ch->hostaddr, gai_strerror(ret));
          goto keep_going;
        }
        break;

      case CHT_UNIX_SOCKET:
#ifdef HAVE_UNIX_SOCKETS
        conn->addrlist_family = hint.ai_family = AF_UNIX;
        UNIXSOCK_PATH(portstr, thisport, ch->host);
        if (strlen(portstr) >= UNIXSOCK_PATH_BUFLEN)
        {
          appendPQExpBuffer(&conn->errorMessage,
                    libpq_gettext("Unix-domain socket path \"%s\" is too long (maximum %d bytes)\n"),
                    portstr,
                    (int) (UNIXSOCK_PATH_BUFLEN - 1));
          goto keep_going;
        }

        /*
         * NULL hostname tells pg_getaddrinfo_all to parse the service
         * name as a Unix-domain socket path.
         */
        ret = pg_getaddrinfo_all(NULL, portstr, &hint,
                     &conn->addrlist);
        if (ret || !conn->addrlist)
        {
          appendPQExpBuffer(&conn->errorMessage,
                    libpq_gettext("could not translate Unix-domain socket path \"%s\" to address: %s\n"),
                    portstr, gai_strerror(ret));
          goto keep_going;
        }
#else
        Assert(false);
#endif
        break;
    }

    /* OK, scan this addrlist for a working server address */
    conn->addr_cur = conn->addrlist;
    reset_connection_state_machine = true;
    conn->try_next_host = false;
  }

  /* Reset connection state machine? */
  if (reset_connection_state_machine)
  {
    /*
     * (Re) initialize our connection control variables for a set of
     * connection attempts to a single server address.  These variables
     * must persist across individual connection attempts, but we must
     * reset them when we start to consider a new server.
     */
    conn->pversion = PG_PROTOCOL(3, 0);
    conn->send_appname = true;
#ifdef USE_SSL
    /* initialize these values based on SSL mode */
    conn->allow_ssl_try = (conn->sslmode[0] != 'd');  /* "disable" */
    conn->wait_ssl_try = (conn->sslmode[0] == 'a'); /* "allow" */
#endif

    reset_connection_state_machine = false;
    need_new_connection = true;
  }

  /* Force a new connection (perhaps to the same server as before)? */
  if (need_new_connection)
  {
    /* Drop any existing connection */
    pqDropConnection(conn, true);

    /* Reset all state obtained from old server */
    pqDropServerData(conn);

    /* Drop any PGresult we might have, too */
    conn->asyncStatus = PGASYNC_IDLE;
    conn->xactStatus = PQTRANS_IDLE;
    pqClearAsyncResult(conn);

    /* Reset conn->status to put the state machine in the right state */
    conn->status = CONNECTION_NEEDED;

    need_new_connection = false;
  }

  /* Now try to advance the state machine for this connection */
  switch (conn->status)
  {
    case CONNECTION_NEEDED:
      {
        /*
         * Try to initiate a connection to one of the addresses
         * returned by pg_getaddrinfo_all().  conn->addr_cur is the
         * next one to try.
         *
         * The extra level of braces here is historical.  It's not
         * worth reindenting this whole switch case to remove 'em.
         */
        {
          struct addrinfo *addr_cur = conn->addr_cur;

          /*
           * Advance to next possible host, if we've tried all of
           * the addresses for the current host.
           */
          if (addr_cur == NULL)
          {
            conn->try_next_host = true;
            goto keep_going;
          }

          /* Remember current address for possible error msg */
          memcpy(&conn->raddr.addr, addr_cur->ai_addr,
               addr_cur->ai_addrlen);
          conn->raddr.salen = addr_cur->ai_addrlen;

          conn->sock = socket(addr_cur->ai_family, SOCK_STREAM, 0);
          if (conn->sock == PGINVALID_SOCKET)
          {
            /*
             * Silently ignore socket() failure if we have more
             * addresses to try; this reduces useless chatter in
             * cases where the address list includes both IPv4 and
             * IPv6 but kernel only accepts one family.
             */
            if (addr_cur->ai_next != NULL ||
              conn->whichhost + 1 < conn->nconnhost)
            {
              conn->try_next_addr = true;
              goto keep_going;
            }
            appendPQExpBuffer(&conn->errorMessage,
                      libpq_gettext("could not create socket: %s\n"),
                      SOCK_STRERROR(SOCK_ERRNO, sebuf, sizeof(sebuf)));
            goto error_return;
          }

          /*
           * Select socket options: no delay of outgoing data for
           * TCP sockets, nonblock mode, close-on-exec.  Try the
           * next address if any of this fails.
           */
          if (!IS_AF_UNIX(addr_cur->ai_family))
          {
            if (!connectNoDelay(conn))
            {
              /* error message already created */
              conn->try_next_addr = true;
              goto keep_going;
            }
          }
          if (!pg_set_noblock(conn->sock))
          {
            appendPQExpBuffer(&conn->errorMessage,
                      libpq_gettext("could not set socket to nonblocking mode: %s\n"),
                      SOCK_STRERROR(SOCK_ERRNO, sebuf, sizeof(sebuf)));
            conn->try_next_addr = true;
            goto keep_going;
          }

#ifdef F_SETFD
          if (fcntl(conn->sock, F_SETFD, FD_CLOEXEC) == -1)
          {
            appendPQExpBuffer(&conn->errorMessage,
                      libpq_gettext("could not set socket to close-on-exec mode: %s\n"),
                      SOCK_STRERROR(SOCK_ERRNO, sebuf, sizeof(sebuf)));
            conn->try_next_addr = true;
            goto keep_going;
          }
#endif              /* F_SETFD */

          if (!IS_AF_UNIX(addr_cur->ai_family))
          {
#ifndef WIN32
            int     on = 1;
#endif
            int     usekeepalives = useKeepalives(conn);
            int     err = 0;

            if (usekeepalives < 0)
            {
              appendPQExpBufferStr(&conn->errorMessage,
                         libpq_gettext("keepalives parameter must be an integer\n"));
              err = 1;
            }
            else if (usekeepalives == 0)
            {
              /* Do nothing */
            }
#ifndef WIN32
            else if (setsockopt(conn->sock,
                      SOL_SOCKET, SO_KEEPALIVE,
                      (char *) &on, sizeof(on)) < 0)
            {
              appendPQExpBuffer(&conn->errorMessage,
                        libpq_gettext("setsockopt(%s) failed: %s\n"),
                        "SO_KEEPALIVE",
                        SOCK_STRERROR(SOCK_ERRNO, sebuf, sizeof(sebuf)));
              err = 1;
            }
            else if (!setKeepalivesIdle(conn)
                 || !setKeepalivesInterval(conn)
                 || !setKeepalivesCount(conn))
              err = 1;
#else             /* WIN32 */
#ifdef SIO_KEEPALIVE_VALS
            else if (!setKeepalivesWin32(conn))
              err = 1;
#endif              /* SIO_KEEPALIVE_VALS */
#endif              /* WIN32 */

            if (err)
            {
              conn->try_next_addr = true;
              goto keep_going;
            }
          }

          /*----------
           * We have three methods of blocking SIGPIPE during
           * send() calls to this socket:
           *
           *  - setsockopt(sock, SO_NOSIGPIPE)
           *  - send(sock, ..., MSG_NOSIGNAL)
           *  - setting the signal mask to SIG_IGN during send()
           *
           * The third method requires three syscalls per send,
           * so we prefer either of the first two, but they are
           * less portable.  The state is tracked in the following
           * members of PGconn:
           *
           * conn->sigpipe_so   - we have set up SO_NOSIGPIPE
           * conn->sigpipe_flag - we're specifying MSG_NOSIGNAL
           *
           * If we can use SO_NOSIGPIPE, then set sigpipe_so here
           * and we're done.  Otherwise, set sigpipe_flag so that
           * we will try MSG_NOSIGNAL on sends.  If we get an error
           * with MSG_NOSIGNAL, we'll clear that flag and revert to
           * signal masking.
           *----------
           */
          conn->sigpipe_so = false;
#ifdef MSG_NOSIGNAL
          conn->sigpipe_flag = true;
#else
          conn->sigpipe_flag = false;
#endif              /* MSG_NOSIGNAL */

#ifdef SO_NOSIGPIPE
          optval = 1;
          if (setsockopt(conn->sock, SOL_SOCKET, SO_NOSIGPIPE,
                   (char *) &optval, sizeof(optval)) == 0)
          {
            conn->sigpipe_so = true;
            conn->sigpipe_flag = false;
          }
#endif              /* SO_NOSIGPIPE */

          /*
           * Start/make connection.  This should not block, since we
           * are in nonblock mode.  If it does, well, too bad.
           */
          if (connect(conn->sock, addr_cur->ai_addr,
                addr_cur->ai_addrlen) < 0)
          {
            if (SOCK_ERRNO == EINPROGRESS ||
#ifdef WIN32
              SOCK_ERRNO == EWOULDBLOCK ||
#endif
              SOCK_ERRNO == EINTR)
            {
              /*
               * This is fine - we're in non-blocking mode, and
               * the connection is in progress.  Tell caller to
               * wait for write-ready on socket.
               */
              conn->status = CONNECTION_STARTED;
              return PGRES_POLLING_WRITING;
            }
            /* otherwise, trouble */
          }
          else
          {
            /*
             * Hm, we're connected already --- seems the "nonblock
             * connection" wasn't.  Advance the state machine and
             * go do the next stuff.
             */
            conn->status = CONNECTION_STARTED;
            goto keep_going;
          }

          /*
           * This connection failed.  Add the error report to
           * conn->errorMessage, then try the next address if any.
           */
          connectFailureMessage(conn, SOCK_ERRNO);
          conn->try_next_addr = true;
          goto keep_going;
        }
      }

    case CONNECTION_STARTED:
      {
        ACCEPT_TYPE_ARG3 optlen = sizeof(optval);

        /*
         * Write ready, since we've made it here, so the connection
         * has been made ... or has failed.
         */

        /*
         * Now check (using getsockopt) that there is not an error
         * state waiting for us on the socket.
         */

        if (getsockopt(conn->sock, SOL_SOCKET, SO_ERROR,
                 (char *) &optval, &optlen) == -1)
        {
          appendPQExpBuffer(&conn->errorMessage,
                    libpq_gettext("could not get socket error status: %s\n"),
                    SOCK_STRERROR(SOCK_ERRNO, sebuf, sizeof(sebuf)));
          goto error_return;
        }
        else if (optval != 0)
        {
          /*
           * When using a nonblocking connect, we will typically see
           * connect failures at this point, so provide a friendly
           * error message.
           */
          connectFailureMessage(conn, optval);

          /*
           * Try the next address if any, just as in the case where
           * connect() returned failure immediately.
           */
          conn->try_next_addr = true;
          goto keep_going;
        }

        /* Fill in the client address */
        conn->laddr.salen = sizeof(conn->laddr.addr);
        if (getsockname(conn->sock,
                (struct sockaddr *) &conn->laddr.addr,
                &conn->laddr.salen) < 0)
        {
          appendPQExpBuffer(&conn->errorMessage,
                    libpq_gettext("could not get client address from socket: %s\n"),
                    SOCK_STRERROR(SOCK_ERRNO, sebuf, sizeof(sebuf)));
          goto error_return;
        }

        /*
         * Make sure we can write before advancing to next step.
         */
        conn->status = CONNECTION_MADE;
        return PGRES_POLLING_WRITING;
      }

    case CONNECTION_MADE:
      {
        char     *startpacket;
        int     packetlen;

#ifdef HAVE_UNIX_SOCKETS

        /*
         * Implement requirepeer check, if requested and it's a
         * Unix-domain socket.
         */
        if (conn->requirepeer && conn->requirepeer[0] &&
          IS_AF_UNIX(conn->raddr.addr.ss_family))
        {
          char    pwdbuf[BUFSIZ];
          struct passwd pass_buf;
          struct passwd *pass;
          int     passerr;
          uid_t   uid;
          gid_t   gid;

          errno = 0;
          if (getpeereid(conn->sock, &uid, &gid) != 0)
          {
            /*
             * Provide special error message if getpeereid is a
             * stub
             */
            if (errno == ENOSYS)
              appendPQExpBufferStr(&conn->errorMessage,
                         libpq_gettext("requirepeer parameter is not supported on this platform\n"));
            else
              appendPQExpBuffer(&conn->errorMessage,
                        libpq_gettext("could not get peer credentials: %s\n"),
                        pqStrerror(errno, sebuf, sizeof(sebuf)));
            goto error_return;
          }

          passerr = pqGetpwuid(uid, &pass_buf, pwdbuf, sizeof(pwdbuf), &pass);
          if (pass == NULL)
          {
            if (passerr != 0)
              appendPQExpBuffer(&conn->errorMessage,
                        libpq_gettext("could not look up local user ID %d: %s\n"),
                        (int) uid,
                        pqStrerror(passerr, sebuf, sizeof(sebuf)));
            else
              appendPQExpBuffer(&conn->errorMessage,
                        libpq_gettext("local user with ID %d does not exist\n"),
                        (int) uid);
            goto error_return;
          }

          if (strcmp(pass->pw_name, conn->requirepeer) != 0)
          {
            appendPQExpBuffer(&conn->errorMessage,
                      libpq_gettext("requirepeer specifies \"%s\", but actual peer user name is \"%s\"\n"),
                      conn->requirepeer, pass->pw_name);
            goto error_return;
          }
        }
#endif              /* HAVE_UNIX_SOCKETS */

#ifdef USE_SSL

        /*
         * If SSL is enabled and we haven't already got it running,
         * request it instead of sending the startup message.
         */
        if (IS_AF_UNIX(conn->raddr.addr.ss_family))
        {
          /* Don't bother requesting SSL over a Unix socket */
          conn->allow_ssl_try = false;
        }
        if (conn->allow_ssl_try && !conn->wait_ssl_try &&
          !conn->ssl_in_use)
        {
          ProtocolVersion pv;

          /*
           * Send the SSL request packet.
           *
           * Theoretically, this could block, but it really
           * shouldn't since we only got here if the socket is
           * write-ready.
           */
          pv = pg_hton32(NEGOTIATE_SSL_CODE);
          if (pqPacketSend(conn, 0, &pv, sizeof(pv)) != STATUS_OK)
          {
            appendPQExpBuffer(&conn->errorMessage,
                      libpq_gettext("could not send SSL negotiation packet: %s\n"),
                      SOCK_STRERROR(SOCK_ERRNO, sebuf, sizeof(sebuf)));
            goto error_return;
          }
          /* Ok, wait for response */
          conn->status = CONNECTION_SSL_STARTUP;
          return PGRES_POLLING_READING;
        }
#endif              /* USE_SSL */

        /*
         * Build the startup packet.
         */
        if (PG_PROTOCOL_MAJOR(conn->pversion) >= 3)
          startpacket = pqBuildStartupPacket3(conn, &packetlen,
                            EnvironmentOptions);
        else
          startpacket = pqBuildStartupPacket2(conn, &packetlen,
                            EnvironmentOptions);
        if (!startpacket)
        {
          /*
           * will not appendbuffer here, since it's likely to also
           * run out of memory
           */
          printfPQExpBuffer(&conn->errorMessage,
                    libpq_gettext("out of memory\n"));
          goto error_return;
        }

        /*
         * Send the startup packet.
         *
         * Theoretically, this could block, but it really shouldn't
         * since we only got here if the socket is write-ready.
         */
        if (pqPacketSend(conn, 0, startpacket, packetlen) != STATUS_OK)
        {
          appendPQExpBuffer(&conn->errorMessage,
                    libpq_gettext("could not send startup packet: %s\n"),
                    SOCK_STRERROR(SOCK_ERRNO, sebuf, sizeof(sebuf)));
          free(startpacket);
          goto error_return;
        }

        free(startpacket);

        conn->status = CONNECTION_AWAITING_RESPONSE;
        return PGRES_POLLING_READING;
      }

      /*
       * Handle SSL negotiation: wait for postmaster messages and
       * respond as necessary.
       */
    case CONNECTION_SSL_STARTUP:
      {
#ifdef USE_SSL
        PostgresPollingStatusType pollres;

        /*
         * On first time through, get the postmaster's response to our
         * SSL negotiation packet.
         */
        if (!conn->ssl_in_use)
        {
          /*
           * We use pqReadData here since it has the logic to
           * distinguish no-data-yet from connection closure. Since
           * conn->ssl isn't set, a plain recv() will occur.
           */
          char    SSLok;
          int     rdresult;

          rdresult = pqReadData(conn);
          if (rdresult < 0)
          {
            /* errorMessage is already filled in */
            goto error_return;
          }
          if (rdresult == 0)
          {
            /* caller failed to wait for data */
            return PGRES_POLLING_READING;
          }
          if (pqGetc(&SSLok, conn) < 0)
          {
            /* should not happen really */
            return PGRES_POLLING_READING;
          }
          if (SSLok == 'S')
          {
            /* mark byte consumed */
            conn->inStart = conn->inCursor;
            /* Set up global SSL state if required */
            if (pqsecure_initialize(conn) != 0)
              goto error_return;
          }
          else if (SSLok == 'N')
          {
            /* mark byte consumed */
            conn->inStart = conn->inCursor;
            /* OK to do without SSL? */
            if (conn->sslmode[0] == 'r' || /* "require" */
              conn->sslmode[0] == 'v')  /* "verify-ca" or
                             * "verify-full" */
            {
              /* Require SSL, but server does not want it */
              appendPQExpBufferStr(&conn->errorMessage,
                         libpq_gettext("server does not support SSL, but SSL was required\n"));
              goto error_return;
            }
            /* Otherwise, proceed with normal startup */
            conn->allow_ssl_try = false;
            conn->status = CONNECTION_MADE;
            return PGRES_POLLING_WRITING;
          }
          else if (SSLok == 'E')
          {
            /*
             * Server failure of some sort, such as failure to
             * fork a backend process.  We need to process and
             * report the error message, which might be formatted
             * according to either protocol 2 or protocol 3.
             * Rather than duplicate the code for that, we flip
             * into AWAITING_RESPONSE state and let the code there
             * deal with it.  Note we have *not* consumed the "E"
             * byte here.
             */
            conn->status = CONNECTION_AWAITING_RESPONSE;
            goto keep_going;
          }
          else
          {
            appendPQExpBuffer(&conn->errorMessage,
                      libpq_gettext("received invalid response to SSL negotiation: %c\n"),
                      SSLok);
            goto error_return;
          }
        }

        /*
         * Begin or continue the SSL negotiation process.
         */
        pollres = pqsecure_open_client(conn);
        if (pollres == PGRES_POLLING_OK)
        {
          /*
           * At this point we should have no data already buffered.
           * If we do, it was received before we performed the SSL
           * handshake, so it wasn't encrypted and indeed may have
           * been injected by a man-in-the-middle.
           */
          if (conn->inCursor != conn->inEnd)
          {
            appendPQExpBufferStr(&conn->errorMessage,
                       libpq_gettext("received unencrypted data after SSL response\n"));
            goto error_return;
          }

          /* SSL handshake done, ready to send startup packet */
          conn->status = CONNECTION_MADE;
          return PGRES_POLLING_WRITING;
        }
        if (pollres == PGRES_POLLING_FAILED)
        {
          /*
           * Failed ... if sslmode is "prefer" then do a non-SSL
           * retry
           */
          if (conn->sslmode[0] == 'p' /* "prefer" */
            && conn->allow_ssl_try  /* redundant? */
            && !conn->wait_ssl_try) /* redundant? */
          {
            /* only retry once */
            conn->allow_ssl_try = false;
            need_new_connection = true;
            goto keep_going;
          }
          /* Else it's a hard failure */
          goto error_return;
        }
        /* Else, return POLLING_READING or POLLING_WRITING status */
        return pollres;
#else             /* !USE_SSL */
        /* can't get here */
        goto error_return;
#endif              /* USE_SSL */
      }

      /*
       * Handle authentication exchange: wait for postmaster messages
       * and respond as necessary.
       */
    case CONNECTION_AWAITING_RESPONSE:
      {
        char    beresp;
        int     msgLength;
        int     avail;
        AuthRequest areq;
        int     res;

        /*
         * Scan the message from current point (note that if we find
         * the message is incomplete, we will return without advancing
         * inStart, and resume here next time).
         */
        conn->inCursor = conn->inStart;

        /* Read type byte */
        if (pqGetc(&beresp, conn))
        {
          /* We'll come back when there is more data */
          return PGRES_POLLING_READING;
        }

        /*
         * Validate message type: we expect only an authentication
         * request or an error here.  Anything else probably means
         * it's not Postgres on the other end at all.
         */
        if (!(beresp == 'R' || beresp == 'E'))
        {
          appendPQExpBuffer(&conn->errorMessage,
                    libpq_gettext(
                          "expected authentication request from "
                          "server, but received %c\n"),
                    beresp);
          goto error_return;
        }

        if (PG_PROTOCOL_MAJOR(conn->pversion) >= 3)
        {
          /* Read message length word */
          if (pqGetInt(&msgLength, 4, conn))
          {
            /* We'll come back when there is more data */
            return PGRES_POLLING_READING;
          }
        }
        else
        {
          /* Set phony message length to disable checks below */
          msgLength = 8;
        }

        /*
         * Try to validate message length before using it.
         * Authentication requests can't be very large, although GSS
         * auth requests may not be that small.  Errors can be a
         * little larger, but not huge.  If we see a large apparent
         * length in an error, it means we're really talking to a
         * pre-3.0-protocol server; cope.
         */
        if (beresp == 'R' && (msgLength < 8 || msgLength > 2000))
        {
          appendPQExpBuffer(&conn->errorMessage,
                    libpq_gettext(
                          "expected authentication request from "
                          "server, but received %c\n"),
                    beresp);
          goto error_return;
        }

        if (beresp == 'E' && (msgLength < 8 || msgLength > 30000))
        {
          /* Handle error from a pre-3.0 server */
          conn->inCursor = conn->inStart + 1; /* reread data */
          if (pqGets_append(&conn->errorMessage, conn))
          {
            /* We'll come back when there is more data */
            return PGRES_POLLING_READING;
          }
          /* OK, we read the message; mark data consumed */
          conn->inStart = conn->inCursor;

          /*
           * The postmaster typically won't end its message with a
           * newline, so add one to conform to libpq conventions.
           */
          appendPQExpBufferChar(&conn->errorMessage, '\n');

          /*
           * If we tried to open the connection in 3.0 protocol,
           * fall back to 2.0 protocol.
           */
          if (PG_PROTOCOL_MAJOR(conn->pversion) >= 3)
          {
            conn->pversion = PG_PROTOCOL(2, 0);
            need_new_connection = true;
            goto keep_going;
          }

          goto error_return;
        }

        /*
         * Can't process if message body isn't all here yet.
         *
         * (In protocol 2.0 case, we are assuming messages carry at
         * least 4 bytes of data.)
         */
        msgLength -= 4;
        avail = conn->inEnd - conn->inCursor;
        if (avail < msgLength)
        {
          /*
           * Before returning, try to enlarge the input buffer if
           * needed to hold the whole message; see notes in
           * pqParseInput3.
           */
          if (pqCheckInBufferSpace(conn->inCursor + (size_t) msgLength,
                       conn))
            goto error_return;
          /* We'll come back when there is more data */
          return PGRES_POLLING_READING;
        }

        /* Handle errors. */
        if (beresp == 'E')
        {
          if (PG_PROTOCOL_MAJOR(conn->pversion) >= 3)
          {
            if (pqGetErrorNotice3(conn, true))
            {
              /* We'll come back when there is more data */
              return PGRES_POLLING_READING;
            }
          }
          else
          {
            if (pqGets_append(&conn->errorMessage, conn))
            {
              /* We'll come back when there is more data */
              return PGRES_POLLING_READING;
            }
          }
          /* OK, we read the message; mark data consumed */
          conn->inStart = conn->inCursor;

          /* Check to see if we should mention pgpassfile */
          pgpassfileWarning(conn);

#ifdef USE_SSL

          /*
           * if sslmode is "allow" and we haven't tried an SSL
           * connection already, then retry with an SSL connection
           */
          if (conn->sslmode[0] == 'a' /* "allow" */
            && !conn->ssl_in_use
            && conn->allow_ssl_try
            && conn->wait_ssl_try)
          {
            /* only retry once */
            conn->wait_ssl_try = false;
            need_new_connection = true;
            goto keep_going;
          }

          /*
           * if sslmode is "prefer" and we're in an SSL connection,
           * then do a non-SSL retry
           */
          if (conn->sslmode[0] == 'p' /* "prefer" */
            && conn->ssl_in_use
            && conn->allow_ssl_try  /* redundant? */
            && !conn->wait_ssl_try) /* redundant? */
          {
            /* only retry once */
            conn->allow_ssl_try = false;
            need_new_connection = true;
            goto keep_going;
          }
#endif

          goto error_return;
        }

        /* It is an authentication request. */
        conn->auth_req_received = true;

        /* Get the type of request. */
        if (pqGetInt((int *) &areq, 4, conn))
        {
          /* We'll come back when there are more data */
          return PGRES_POLLING_READING;
        }
        msgLength -= 4;

        /*
         * Ensure the password salt is in the input buffer, if it's an
         * MD5 request.  All the other authentication methods that
         * contain extra data in the authentication request are only
         * supported in protocol version 3, in which case we already
         * read the whole message above.
         */
        if (areq == AUTH_REQ_MD5 && PG_PROTOCOL_MAJOR(conn->pversion) < 3)
        {
          msgLength += 4;

          avail = conn->inEnd - conn->inCursor;
          if (avail < 4)
          {
            /*
             * Before returning, try to enlarge the input buffer
             * if needed to hold the whole message; see notes in
             * pqParseInput3.
             */
            if (pqCheckInBufferSpace(conn->inCursor + (size_t) 4,
                         conn))
              goto error_return;
            /* We'll come back when there is more data */
            return PGRES_POLLING_READING;
          }
        }

        /*
         * Process the rest of the authentication request message, and
         * respond to it if necessary.
         *
         * Note that conn->pghost must be non-NULL if we are going to
         * avoid the Kerberos code doing a hostname look-up.
         */
        res = pg_fe_sendauth(areq, msgLength, conn);
        conn->errorMessage.len = strlen(conn->errorMessage.data);

        /* OK, we have processed the message; mark data consumed */
        conn->inStart = conn->inCursor;

        if (res != STATUS_OK)
          goto error_return;

        /*
         * Just make sure that any data sent by pg_fe_sendauth is
         * flushed out.  Although this theoretically could block, it
         * really shouldn't since we don't send large auth responses.
         */
        if (pqFlush(conn))
          goto error_return;

        if (areq == AUTH_REQ_OK)
        {
          /* We are done with authentication exchange */
          conn->status = CONNECTION_AUTH_OK;

          /*
           * Set asyncStatus so that PQgetResult will think that
           * what comes back next is the result of a query.  See
           * below.
           */
          conn->asyncStatus = PGASYNC_BUSY;
        }

        /* Look to see if we have more data yet. */
        goto keep_going;
      }

    case CONNECTION_AUTH_OK:
      {
        /*
         * Now we expect to hear from the backend. A ReadyForQuery
         * message indicates that startup is successful, but we might
         * also get an Error message indicating failure. (Notice
         * messages indicating nonfatal warnings are also allowed by
         * the protocol, as are ParameterStatus and BackendKeyData
         * messages.) Easiest way to handle this is to let
         * PQgetResult() read the messages. We just have to fake it
         * out about the state of the connection, by setting
         * asyncStatus = PGASYNC_BUSY (done above).
         */

        if (PQisBusy(conn))
          return PGRES_POLLING_READING;

        res = PQgetResult(conn);

        /*
         * NULL return indicating we have gone to IDLE state is
         * expected
         */
        if (res)
        {
          if (res->resultStatus != PGRES_FATAL_ERROR)
            appendPQExpBufferStr(&conn->errorMessage,
                       libpq_gettext("unexpected message from server during startup\n"));
          else if (conn->send_appname &&
               (conn->appname || conn->fbappname))
          {
            /*
             * If we tried to send application_name, check to see
             * if the error is about that --- pre-9.0 servers will
             * reject it at this stage of the process.  If so,
             * close the connection and retry without sending
             * application_name.  We could possibly get a false
             * SQLSTATE match here and retry uselessly, but there
             * seems no great harm in that; we'll just get the
             * same error again if it's unrelated.
             */
            const char *sqlstate;

            sqlstate = PQresultErrorField(res, PG_DIAG_SQLSTATE);
            if (sqlstate &&
              strcmp(sqlstate, ERRCODE_APPNAME_UNKNOWN) == 0)
            {
              PQclear(res);
              conn->send_appname = false;
              need_new_connection = true;
              goto keep_going;
            }
          }

          /*
           * if the resultStatus is FATAL, then conn->errorMessage
           * already has a copy of the error; needn't copy it back.
           * But add a newline if it's not there already, since
           * postmaster error messages may not have one.
           */
          if (conn->errorMessage.len <= 0 ||
            conn->errorMessage.data[conn->errorMessage.len - 1] != '\n')
            appendPQExpBufferChar(&conn->errorMessage, '\n');
          PQclear(res);
          goto error_return;
        }

        /* Fire up post-connection housekeeping if needed */
        if (PG_PROTOCOL_MAJOR(conn->pversion) < 3)
        {
          conn->status = CONNECTION_SETENV;
          conn->setenv_state = SETENV_STATE_CLIENT_ENCODING_SEND;
          conn->next_eo = EnvironmentOptions;
          return PGRES_POLLING_WRITING;
        }

        /*
         * If a read-write connection is required, see if we have one.
         *
         * Servers before 7.4 lack the transaction_read_only GUC, but
         * by the same token they don't have any read-only mode, so we
         * may just skip the test in that case.
         */
        if (conn->sversion >= 70400 &&
          conn->target_session_attrs != NULL &&
          strcmp(conn->target_session_attrs, "read-write") == 0)
        {
          /*
           * Save existing error messages across the PQsendQuery
           * attempt.  This is necessary because PQsendQuery is
           * going to reset conn->errorMessage, so we would lose
           * error messages related to previous hosts we have tried
           * and failed to connect to.
           */
          if (!saveErrorMessage(conn, &savedMessage))
            goto error_return;

          conn->status = CONNECTION_OK;
          if (!PQsendQuery(conn,
                   "SHOW transaction_read_only"))
          {
            restoreErrorMessage(conn, &savedMessage);
            goto error_return;
          }
          conn->status = CONNECTION_CHECK_WRITABLE;
          restoreErrorMessage(conn, &savedMessage);
          return PGRES_POLLING_READING;
        }

        /* We can release the address list now. */
        release_conn_addrinfo(conn);

        /* We are open for business! */
        conn->status = CONNECTION_OK;
        return PGRES_POLLING_OK;
      }

    case CONNECTION_SETENV:

      /*
       * Do post-connection housekeeping (only needed in protocol 2.0).
       *
       * We pretend that the connection is OK for the duration of these
       * queries.
       */
      conn->status = CONNECTION_OK;

      switch (pqSetenvPoll(conn))
      {
        case PGRES_POLLING_OK:  /* Success */
          break;

        case PGRES_POLLING_READING: /* Still going */
          conn->status = CONNECTION_SETENV;
          return PGRES_POLLING_READING;

        case PGRES_POLLING_WRITING: /* Still going */
          conn->status = CONNECTION_SETENV;
          return PGRES_POLLING_WRITING;

        default:
          goto error_return;
      }

      /*
       * If a read-write connection is required, see if we have one.
       * (This should match the stanza in the CONNECTION_AUTH_OK case
       * above.)
       *
       * Servers before 7.4 lack the transaction_read_only GUC, but by
       * the same token they don't have any read-only mode, so we may
       * just skip the test in that case.
       */
      if (conn->sversion >= 70400 &&
        conn->target_session_attrs != NULL &&
        strcmp(conn->target_session_attrs, "read-write") == 0)
      {
        if (!saveErrorMessage(conn, &savedMessage))
          goto error_return;

        conn->status = CONNECTION_OK;
        if (!PQsendQuery(conn,
                 "SHOW transaction_read_only"))
        {
          restoreErrorMessage(conn, &savedMessage);
          goto error_return;
        }
        conn->status = CONNECTION_CHECK_WRITABLE;
        restoreErrorMessage(conn, &savedMessage);
        return PGRES_POLLING_READING;
      }

      /* We can release the address list now. */
      release_conn_addrinfo(conn);

      /* We are open for business! */
      conn->status = CONNECTION_OK;
      return PGRES_POLLING_OK;

    case CONNECTION_CONSUME:
      {
        conn->status = CONNECTION_OK;
        if (!PQconsumeInput(conn))
          goto error_return;

        if (PQisBusy(conn))
        {
          conn->status = CONNECTION_CONSUME;
          return PGRES_POLLING_READING;
        }

        /*
         * Call PQgetResult() again to consume NULL result.
         */
        res = PQgetResult(conn);
        if (res != NULL)
        {
          PQclear(res);
          conn->status = CONNECTION_CONSUME;
          goto keep_going;
        }

        /* We can release the address list now. */
        release_conn_addrinfo(conn);

        /* We are open for business! */
        conn->status = CONNECTION_OK;
        return PGRES_POLLING_OK;
      }
    case CONNECTION_CHECK_WRITABLE:
      {
        const char *displayed_host;
        const char *displayed_port;

        if (!saveErrorMessage(conn, &savedMessage))
          goto error_return;

        conn->status = CONNECTION_OK;
        if (!PQconsumeInput(conn))
        {
          restoreErrorMessage(conn, &savedMessage);
          goto error_return;
        }

        if (PQisBusy(conn))
        {
          conn->status = CONNECTION_CHECK_WRITABLE;
          restoreErrorMessage(conn, &savedMessage);
          return PGRES_POLLING_READING;
        }

        res = PQgetResult(conn);
        if (res && (PQresultStatus(res) == PGRES_TUPLES_OK) &&
          PQntuples(res) == 1)
        {
          char     *val;

          val = PQgetvalue(res, 0, 0);
          if (strncmp(val, "on", 2) == 0)
          {
            /* Not writable; fail this connection. */
            const char *displayed_host;
            const char *displayed_port;

            PQclear(res);
            restoreErrorMessage(conn, &savedMessage);

            /* Append error report to conn->errorMessage. */
            if (conn->connhost[conn->whichhost].type == CHT_HOST_ADDRESS)
              displayed_host = conn->connhost[conn->whichhost].hostaddr;
            else
              displayed_host = conn->connhost[conn->whichhost].host;
            displayed_port = conn->connhost[conn->whichhost].port;
            if (displayed_port == NULL || displayed_port[0] == '\0')
              /* Use YugaByte default port */
              displayed_port = DEF_YBPORT_STR;

            appendPQExpBuffer(&conn->errorMessage,
                      libpq_gettext("could not make a writable "
                            "connection to server "
                            "\"%s:%s\"\n"),
                      displayed_host, displayed_port);

            /* Close connection politely. */
            conn->status = CONNECTION_OK;
            sendTerminateConn(conn);

            /*
             * Try next host if any, but we don't want to consider
             * additional addresses for this host.
             */
            conn->try_next_host = true;
            goto keep_going;
          }

          /* Session is read-write, so we're good. */
          PQclear(res);
          termPQExpBuffer(&savedMessage);

          /*
           * Finish reading any remaining messages before being
           * considered as ready.
           */
          conn->status = CONNECTION_CONSUME;
          goto keep_going;
        }

        /*
         * Something went wrong with "SHOW transaction_read_only". We
         * should try next addresses.
         */
        if (res)
          PQclear(res);
        restoreErrorMessage(conn, &savedMessage);

        /* Append error report to conn->errorMessage. */
        if (conn->connhost[conn->whichhost].type == CHT_HOST_ADDRESS)
          displayed_host = conn->connhost[conn->whichhost].hostaddr;
        else
          displayed_host = conn->connhost[conn->whichhost].host;
        displayed_port = conn->connhost[conn->whichhost].port;
        if (displayed_port == NULL || displayed_port[0] == '\0')
          /* Use YugaByte default port */
          displayed_port = DEF_YBPORT_STR;
        appendPQExpBuffer(&conn->errorMessage,
                  libpq_gettext("test \"SHOW transaction_read_only\" failed "
                        "on server \"%s:%s\"\n"),
                  displayed_host, displayed_port);

        /* Close connection politely. */
        conn->status = CONNECTION_OK;
        sendTerminateConn(conn);

        /* Try next address */
        conn->try_next_addr = true;
        goto keep_going;
      }

    default:
      appendPQExpBuffer(&conn->errorMessage,
                libpq_gettext("invalid connection state %d, "
                      "probably indicative of memory corruption\n"),
                conn->status);
      goto error_return;
  }

  /* Unreachable */

error_return:

  /*
   * We used to close the socket at this point, but that makes it awkward
   * for those above us if they wish to remove this socket from their own
   * records (an fd_set for example).  We'll just have this socket closed
   * when PQfinish is called (which is compulsory even after an error, since
   * the connection structure must be freed).
   */
  conn->status = CONNECTION_BAD;
  return PGRES_POLLING_FAILED;
}


/*
 * internal_ping
 *    Determine if a server is running and if we can connect to it.
 *
 * The argument is a connection that's been started, but not completed.
 */
static PGPing
internal_ping(PGconn *conn)
{
  /* Say "no attempt" if we never got to PQconnectPoll */
  if (!conn || !conn->options_valid)
    return PQPING_NO_ATTEMPT;

  /* Attempt to complete the connection */
  if (conn->status != CONNECTION_BAD)
    (void) connectDBComplete(conn);

  /* Definitely OK if we succeeded */
  if (conn->status != CONNECTION_BAD)
    return PQPING_OK;

  /*
   * Here begins the interesting part of "ping": determine the cause of the
   * failure in sufficient detail to decide what to return.  We do not want
   * to report that the server is not up just because we didn't have a valid
   * password, for example.  In fact, any sort of authentication request
   * implies the server is up.  (We need this check since the libpq side of
   * things might have pulled the plug on the connection before getting an
   * error as such from the postmaster.)
   */
  if (conn->auth_req_received)
    return PQPING_OK;

  /*
   * If we failed to get any ERROR response from the postmaster, report
   * PQPING_NO_RESPONSE.  This result could be somewhat misleading for a
   * pre-7.4 server, since it won't send back a SQLSTATE, but those are long
   * out of support.  Another corner case where the server could return a
   * failure without a SQLSTATE is fork failure, but NO_RESPONSE isn't
   * totally unreasonable for that anyway.  We expect that every other
   * failure case in a modern server will produce a report with a SQLSTATE.
   *
   * NOTE: whenever we get around to making libpq generate SQLSTATEs for
   * client-side errors, we should either not store those into
   * last_sqlstate, or add an extra flag so we can tell client-side errors
   * apart from server-side ones.
   */
  if (strlen(conn->last_sqlstate) != 5)
    return PQPING_NO_RESPONSE;

  /*
   * Report PQPING_REJECT if server says it's not accepting connections. (We
   * distinguish this case mainly for the convenience of pg_ctl.)
   */
  if (strcmp(conn->last_sqlstate, ERRCODE_CANNOT_CONNECT_NOW) == 0)
    return PQPING_REJECT;

  /*
   * Any other SQLSTATE can be taken to indicate that the server is up.
   * Presumably it didn't like our username, password, or database name; or
   * perhaps it had some transient failure, but that should not be taken as
   * meaning "it's down".
   */
  return PQPING_OK;
}


/*
 * makeEmptyPGconn
 *   - create a PGconn data structure with (as yet) no interesting data
 */
static PGconn *
makeEmptyPGconn(void)
{
  PGconn     *conn;

#ifdef WIN32

  /*
   * Make sure socket support is up and running.
   */
  WSADATA   wsaData;

  if (WSAStartup(MAKEWORD(1, 1), &wsaData))
    return NULL;
  WSASetLastError(0);
#endif

  conn = (PGconn *) malloc(sizeof(PGconn));
  if (conn == NULL)
  {
#ifdef WIN32
    WSACleanup();
#endif
    return conn;
  }

  /* Zero all pointers and booleans */
  MemSet(conn, 0, sizeof(PGconn));

  /* install default notice hooks */
  conn->noticeHooks.noticeRec = defaultNoticeReceiver;
  conn->noticeHooks.noticeProc = defaultNoticeProcessor;

  conn->status = CONNECTION_BAD;
  conn->asyncStatus = PGASYNC_IDLE;
  conn->xactStatus = PQTRANS_IDLE;
  conn->options_valid = false;
  conn->nonblocking = false;
  conn->setenv_state = SETENV_STATE_IDLE;
  conn->client_encoding = PG_SQL_ASCII;
  conn->std_strings = false;  /* unless server says differently */
  conn->verbosity = PQERRORS_DEFAULT;
  conn->show_context = PQSHOW_CONTEXT_ERRORS;
  conn->sock = PGINVALID_SOCKET;

  /*
   * We try to send at least 8K at a time, which is the usual size of pipe
   * buffers on Unix systems.  That way, when we are sending a large amount
   * of data, we avoid incurring extra kernel context swaps for partial
   * bufferloads.  The output buffer is initially made 16K in size, and we
   * try to dump it after accumulating 8K.
   *
   * With the same goal of minimizing context swaps, the input buffer will
   * be enlarged anytime it has less than 8K free, so we initially allocate
   * twice that.
   */
  conn->inBufSize = 16 * 1024;
  conn->inBuffer = (char *) malloc(conn->inBufSize);
  conn->outBufSize = 16 * 1024;
  conn->outBuffer = (char *) malloc(conn->outBufSize);
  conn->rowBufLen = 32;
  conn->rowBuf = (PGdataValue *) malloc(conn->rowBufLen * sizeof(PGdataValue));
  initPQExpBuffer(&conn->errorMessage);
  initPQExpBuffer(&conn->workBuffer);

  if (conn->inBuffer == NULL ||
    conn->outBuffer == NULL ||
    conn->rowBuf == NULL ||
    PQExpBufferBroken(&conn->errorMessage) ||
    PQExpBufferBroken(&conn->workBuffer))
  {
    /* out of memory already :-( */
    freePGconn(conn);
    conn = NULL;
  }

  return conn;
}

/*
 * freePGconn
 *   - free an idle (closed) PGconn data structure
 *
 * NOTE: this should not overlap any functionality with closePGconn().
 * Clearing/resetting of transient state belongs there; what we do here is
 * release data that is to be held for the life of the PGconn structure.
 * If a value ought to be cleared/freed during PQreset(), do it there not here.
 */
static void
freePGconn(PGconn *conn)
{
  int     i;

  /* let any event procs clean up their state data */
  for (i = 0; i < conn->nEvents; i++)
  {
    PGEventConnDestroy evt;

    evt.conn = conn;
    (void) conn->events[i].proc(PGEVT_CONNDESTROY, &evt,
                  conn->events[i].passThrough);
    free(conn->events[i].name);
  }

  /* clean up pg_conn_host structures */
  if (conn->connhost != NULL)
  {
    for (i = 0; i < conn->nconnhost; ++i)
    {
      if (conn->connhost[i].host != NULL)
        free(conn->connhost[i].host);
      if (conn->connhost[i].hostaddr != NULL)
        free(conn->connhost[i].hostaddr);
      if (conn->connhost[i].port != NULL)
        free(conn->connhost[i].port);
      if (conn->connhost[i].password != NULL)
        free(conn->connhost[i].password);
    }
    free(conn->connhost);
  }

  if (conn->client_encoding_initial)
    free(conn->client_encoding_initial);
  if (conn->events)
    free(conn->events);
  if (conn->pghost)
    free(conn->pghost);
  if (conn->pghostaddr)
    free(conn->pghostaddr);
  if (conn->pgport)
    free(conn->pgport);
  if (conn->pgtty)
    free(conn->pgtty);
  if (conn->connect_timeout)
    free(conn->connect_timeout);
  if (conn->pgoptions)
    free(conn->pgoptions);
  if (conn->appname)
    free(conn->appname);
  if (conn->fbappname)
    free(conn->fbappname);
  if (conn->dbName)
    free(conn->dbName);
  if (conn->replication)
    free(conn->replication);
  if (conn->pguser)
    free(conn->pguser);
  if (conn->pgpass)
    free(conn->pgpass);
  if (conn->pgpassfile)
    free(conn->pgpassfile);
  if (conn->keepalives)
    free(conn->keepalives);
  if (conn->keepalives_idle)
    free(conn->keepalives_idle);
  if (conn->keepalives_interval)
    free(conn->keepalives_interval);
  if (conn->keepalives_count)
    free(conn->keepalives_count);
  if (conn->sslmode)
    free(conn->sslmode);
  if (conn->sslcert)
    free(conn->sslcert);
  if (conn->sslkey)
    free(conn->sslkey);
  if (conn->sslrootcert)
    free(conn->sslrootcert);
  if (conn->sslcrl)
    free(conn->sslcrl);
  if (conn->sslcompression)
    free(conn->sslcompression);
  if (conn->requirepeer)
    free(conn->requirepeer);
#if defined(ENABLE_GSS) || defined(ENABLE_SSPI)
  if (conn->krbsrvname)
    free(conn->krbsrvname);
#endif
#if defined(ENABLE_GSS) && defined(ENABLE_SSPI)
  if (conn->gsslib)
    free(conn->gsslib);
#endif
  /* Note that conn->Pfdebug is not ours to close or free */
  if (conn->last_query)
    free(conn->last_query);
  if (conn->inBuffer)
    free(conn->inBuffer);
  if (conn->outBuffer)
    free(conn->outBuffer);
  if (conn->rowBuf)
    free(conn->rowBuf);
  if (conn->target_session_attrs)
    free(conn->target_session_attrs);
  termPQExpBuffer(&conn->errorMessage);
  termPQExpBuffer(&conn->workBuffer);

  free(conn);

#ifdef WIN32
  WSACleanup();
#endif
}

/*
 * release_conn_addrinfo
 *   - Free any addrinfo list in the PGconn.
 */
static void
release_conn_addrinfo(PGconn *conn)
{
  if (conn->addrlist)
  {
    pg_freeaddrinfo_all(conn->addrlist_family, conn->addrlist);
    conn->addrlist = NULL;
    conn->addr_cur = NULL;  /* for safety */
  }
}

/*
 * sendTerminateConn
 *   - Send a terminate message to backend.
 */
static void
sendTerminateConn(PGconn *conn)
{
  /*
   * Note that the protocol doesn't allow us to send Terminate messages
   * during the startup phase.
   */
  if (conn->sock != PGINVALID_SOCKET && conn->status == CONNECTION_OK)
  {
    /*
     * Try to send "close connection" message to backend. Ignore any
     * error.
     */
    pqPutMsgStart('X', false, conn);
    pqPutMsgEnd(conn);
    (void) pqFlush(conn);
  }
}

/*
 * closePGconn
 *   - properly close a connection to the backend
 *
 * This should reset or release all transient state, but NOT the connection
 * parameters.  On exit, the PGconn should be in condition to start a fresh
 * connection with the same parameters (see PQreset()).
 */
static void
closePGconn(PGconn *conn)
{
  /*
   * If possible, send Terminate message to close the connection politely.
   */
  sendTerminateConn(conn);

  /*
   * Must reset the blocking status so a possible reconnect will work.
   *
   * Don't call PQsetnonblocking() because it will fail if it's unable to
   * flush the connection.
   */
  conn->nonblocking = false;

  /*
   * Close the connection, reset all transient state, flush I/O buffers.
   */
  pqDropConnection(conn, true);
  conn->status = CONNECTION_BAD;  /* Well, not really _bad_ - just absent */
  conn->asyncStatus = PGASYNC_IDLE;
  conn->xactStatus = PQTRANS_IDLE;
  pqClearAsyncResult(conn); /* deallocate result */
  resetPQExpBuffer(&conn->errorMessage);
  release_conn_addrinfo(conn);

  /* Reset all state obtained from server, too */
  pqDropServerData(conn);
}

/*
 * PQfinish: properly close a connection to the backend. Also frees
 * the PGconn data structure so it shouldn't be re-used after this.
 */
void
PQfinish(PGconn *conn)
{
  if (conn)
  {
    closePGconn(conn);
    freePGconn(conn);
  }
}

/*
 * PQreset: resets the connection to the backend by closing the
 * existing connection and creating a new one.
 */
void
PQreset(PGconn *conn)
{
  if (conn)
  {
    closePGconn(conn);

    if (connectDBStart(conn) && connectDBComplete(conn))
    {
      /*
       * Notify event procs of successful reset.  We treat an event proc
       * failure as disabling the connection ... good idea?
       */
      int     i;

      for (i = 0; i < conn->nEvents; i++)
      {
        PGEventConnReset evt;

        evt.conn = conn;
        if (!conn->events[i].proc(PGEVT_CONNRESET, &evt,
                      conn->events[i].passThrough))
        {
          conn->status = CONNECTION_BAD;
          printfPQExpBuffer(&conn->errorMessage,
                    libpq_gettext("PGEventProc \"%s\" failed during PGEVT_CONNRESET event\n"),
                    conn->events[i].name);
          break;
        }
      }
    }
  }
}


/*
 * PQresetStart:
 * resets the connection to the backend
 * closes the existing connection and makes a new one
 * Returns 1 on success, 0 on failure.
 */
int
PQresetStart(PGconn *conn)
{
  if (conn)
  {
    closePGconn(conn);

    return connectDBStart(conn);
  }

  return 0;
}


/*
 * PQresetPoll:
 * resets the connection to the backend
 * closes the existing connection and makes a new one
 */
PostgresPollingStatusType
PQresetPoll(PGconn *conn)
{
  if (conn)
  {
    PostgresPollingStatusType status = PQconnectPoll(conn);

    if (status == PGRES_POLLING_OK)
    {
      /*
       * Notify event procs of successful reset.  We treat an event proc
       * failure as disabling the connection ... good idea?
       */
      int     i;

      for (i = 0; i < conn->nEvents; i++)
      {
        PGEventConnReset evt;

        evt.conn = conn;
        if (!conn->events[i].proc(PGEVT_CONNRESET, &evt,
                      conn->events[i].passThrough))
        {
          conn->status = CONNECTION_BAD;
          printfPQExpBuffer(&conn->errorMessage,
                    libpq_gettext("PGEventProc \"%s\" failed during PGEVT_CONNRESET event\n"),
                    conn->events[i].name);
          return PGRES_POLLING_FAILED;
        }
      }
    }

    return status;
  }

  return PGRES_POLLING_FAILED;
}

/*
 * PQgetCancel: get a PGcancel structure corresponding to a connection.
 *
 * A copy is needed to be able to cancel a running query from a different
 * thread. If the same structure is used all structure members would have
 * to be individually locked (if the entire structure was locked, it would
 * be impossible to cancel a synchronous query because the structure would
 * have to stay locked for the duration of the query).
 */
PGcancel *
PQgetCancel(PGconn *conn)
{
  PGcancel   *cancel;

  if (!conn)
    return NULL;

  if (conn->sock == PGINVALID_SOCKET)
    return NULL;

  cancel = malloc(sizeof(PGcancel));
  if (cancel == NULL)
    return NULL;

  memcpy(&cancel->raddr, &conn->raddr, sizeof(SockAddr));
  cancel->be_pid = conn->be_pid;
  cancel->be_key = conn->be_key;

  return cancel;
}

/* PQfreeCancel: free a cancel structure */
void
PQfreeCancel(PGcancel *cancel)
{
  if (cancel)
    free(cancel);
}


/*
 * PQcancel and PQrequestCancel: attempt to request cancellation of the
 * current operation.
 *
 * The return value is true if the cancel request was successfully
 * dispatched, false if not (in which case an error message is available).
 * Note: successful dispatch is no guarantee that there will be any effect at
 * the backend.  The application must read the operation result as usual.
 *
 * CAUTION: we want this routine to be safely callable from a signal handler
 * (for example, an application might want to call it in a SIGINT handler).
 * This means we cannot use any C library routine that might be non-reentrant.
 * malloc/free are often non-reentrant, and anything that might call them is
 * just as dangerous.  We avoid sprintf here for that reason.  Building up
 * error messages with strcpy/strcat is tedious but should be quite safe.
 * We also save/restore errno in case the signal handler support doesn't.
 *
 * internal_cancel() is an internal helper function to make code-sharing
 * between the two versions of the cancel function possible.
 */
static int
internal_cancel(SockAddr *raddr, int be_pid, int be_key,
        char *errbuf, int errbufsize)
{
  int     save_errno = SOCK_ERRNO;
  pgsocket  tmpsock = PGINVALID_SOCKET;
  char    sebuf[256];
  int     maxlen;
  struct
  {
    uint32    packetlen;
    CancelRequestPacket cp;
  }     crp;

  /*
   * We need to open a temporary connection to the postmaster. Do this with
   * only kernel calls.
   */
  if ((tmpsock = socket(raddr->addr.ss_family, SOCK_STREAM, 0)) == PGINVALID_SOCKET)
  {
    strlcpy(errbuf, "PQcancel() -- socket() failed: ", errbufsize);
    goto cancel_errReturn;
  }
retry3:
  if (connect(tmpsock, (struct sockaddr *) &raddr->addr,
        raddr->salen) < 0)
  {
    if (SOCK_ERRNO == EINTR)
      /* Interrupted system call - we'll just try again */
      goto retry3;
    strlcpy(errbuf, "PQcancel() -- connect() failed: ", errbufsize);
    goto cancel_errReturn;
  }

  /*
   * We needn't set nonblocking I/O or NODELAY options here.
   */

  /* Create and send the cancel request packet. */

  crp.packetlen = pg_hton32((uint32) sizeof(crp));
  crp.cp.cancelRequestCode = (MsgType) pg_hton32(CANCEL_REQUEST_CODE);
  crp.cp.backendPID = pg_hton32(be_pid);
  crp.cp.cancelAuthCode = pg_hton32(be_key);

retry4:
  if (send(tmpsock, (char *) &crp, sizeof(crp), 0) != (int) sizeof(crp))
  {
    if (SOCK_ERRNO == EINTR)
      /* Interrupted system call - we'll just try again */
      goto retry4;
    strlcpy(errbuf, "PQcancel() -- send() failed: ", errbufsize);
    goto cancel_errReturn;
  }

  /*
   * Wait for the postmaster to close the connection, which indicates that
   * it's processed the request.  Without this delay, we might issue another
   * command only to find that our cancel zaps that command instead of the
   * one we thought we were canceling.  Note we don't actually expect this
   * read to obtain any data, we are just waiting for EOF to be signaled.
   */
retry5:
  if (recv(tmpsock, (char *) &crp, 1, 0) < 0)
  {
    if (SOCK_ERRNO == EINTR)
      /* Interrupted system call - we'll just try again */
      goto retry5;
    /* we ignore other error conditions */
  }

  /* All done */
  closesocket(tmpsock);
  SOCK_ERRNO_SET(save_errno);
  return true;

cancel_errReturn:

  /*
   * Make sure we don't overflow the error buffer. Leave space for the \n at
   * the end, and for the terminating zero.
   */
  maxlen = errbufsize - strlen(errbuf) - 2;
  if (maxlen >= 0)
  {
    strncat(errbuf, SOCK_STRERROR(SOCK_ERRNO, sebuf, sizeof(sebuf)),
        maxlen);
    strcat(errbuf, "\n");
  }
  if (tmpsock != PGINVALID_SOCKET)
    closesocket(tmpsock);
  SOCK_ERRNO_SET(save_errno);
  return false;
}

/*
 * PQcancel: request query cancel
 *
 * Returns true if able to send the cancel request, false if not.
 *
 * On failure, an error message is stored in *errbuf, which must be of size
 * errbufsize (recommended size is 256 bytes).  *errbuf is not changed on
 * success return.
 */
int
PQcancel(PGcancel *cancel, char *errbuf, int errbufsize)
{
  if (!cancel)
  {
    strlcpy(errbuf, "PQcancel() -- no cancel object supplied", errbufsize);
    return false;
  }

  return internal_cancel(&cancel->raddr, cancel->be_pid, cancel->be_key,
               errbuf, errbufsize);
}

/*
 * PQrequestCancel: old, not thread-safe function for requesting query cancel
 *
 * Returns true if able to send the cancel request, false if not.
 *
 * On failure, the error message is saved in conn->errorMessage; this means
 * that this can't be used when there might be other active operations on
 * the connection object.
 *
 * NOTE: error messages will be cut off at the current size of the
 * error message buffer, since we dare not try to expand conn->errorMessage!
 */
int
PQrequestCancel(PGconn *conn)
{
  int     r;

  /* Check we have an open connection */
  if (!conn)
    return false;

  if (conn->sock == PGINVALID_SOCKET)
  {
    strlcpy(conn->errorMessage.data,
        "PQrequestCancel() -- connection is not open\n",
        conn->errorMessage.maxlen);
    conn->errorMessage.len = strlen(conn->errorMessage.data);

    return false;
  }

  r = internal_cancel(&conn->raddr, conn->be_pid, conn->be_key,
            conn->errorMessage.data, conn->errorMessage.maxlen);

  if (!r)
    conn->errorMessage.len = strlen(conn->errorMessage.data);

  return r;
}


/*
 * pqPacketSend() -- convenience routine to send a message to server.
 *
 * pack_type: the single-byte message type code.  (Pass zero for startup
 * packets, which have no message type code.)
 *
 * buf, buf_len: contents of message.  The given length includes only what
 * is in buf; the message type and message length fields are added here.
 *
 * RETURNS: STATUS_ERROR if the write fails, STATUS_OK otherwise.
 * SIDE_EFFECTS: may block.
 *
 * Note: all messages sent with this routine have a length word, whether
 * it's protocol 2.0 or 3.0.
 */
int
pqPacketSend(PGconn *conn, char pack_type,
       const void *buf, size_t buf_len)
{
  /* Start the message. */
  if (pqPutMsgStart(pack_type, true, conn))
    return STATUS_ERROR;

  /* Send the message body. */
  if (pqPutnchar(buf, buf_len, conn))
    return STATUS_ERROR;

  /* Finish the message. */
  if (pqPutMsgEnd(conn))
    return STATUS_ERROR;

  /* Flush to ensure backend gets it. */
  if (pqFlush(conn))
    return STATUS_ERROR;

  return STATUS_OK;
}

#ifdef USE_LDAP

#define LDAP_URL  "ldap://"
#define LDAP_DEF_PORT 389
#define PGLDAP_TIMEOUT 2

#define ld_is_sp_tab(x) ((x) == ' ' || (x) == '\t')
#define ld_is_nl_cr(x) ((x) == '\r' || (x) == '\n')


/*
 *    ldapServiceLookup
 *
 * Search the LDAP URL passed as first argument, treat the result as a
 * string of connection options that are parsed and added to the array of
 * options passed as second argument.
 *
 * LDAP URLs must conform to RFC 1959 without escape sequences.
 *  ldap://host:port/dn?attributes?scope?filter?extensions
 *
 * Returns
 *  0 if the lookup was successful,
 *  1 if the connection to the LDAP server could be established but
 *    the search was unsuccessful,
 *  2 if a connection could not be established, and
 *  3 if a fatal error occurred.
 *
 * An error message is returned in the third argument for return codes 1 and 3.
 */
static int
ldapServiceLookup(const char *purl, PQconninfoOption *options,
          PQExpBuffer errorMessage)
{
  int     port = LDAP_DEF_PORT,
        scope,
        rc,
        size,
        state,
        oldstate,
        i;
#ifndef WIN32
  int     msgid;
#endif
  bool    found_keyword;
  char     *url,
         *hostname,
         *portstr,
         *endptr,
         *dn,
         *scopestr,
         *filter,
         *result,
         *p,
         *p1 = NULL,
         *optname = NULL,
         *optval = NULL;
  char     *attrs[2] = {NULL, NULL};
  LDAP     *ld = NULL;
  LDAPMessage *res,
         *entry;
  struct berval **values;
  LDAP_TIMEVAL time = {PGLDAP_TIMEOUT, 0};

  if ((url = strdup(purl)) == NULL)
  {
    printfPQExpBuffer(errorMessage, libpq_gettext("out of memory\n"));
    return 3;
  }

  /*
   * Parse URL components, check for correctness.  Basically, url has '\0'
   * placed at component boundaries and variables are pointed at each
   * component.
   */

  if (pg_strncasecmp(url, LDAP_URL, strlen(LDAP_URL)) != 0)
  {
    printfPQExpBuffer(errorMessage,
              libpq_gettext("invalid LDAP URL \"%s\": scheme must be ldap://\n"), purl);
    free(url);
    return 3;
  }

  /* hostname */
  hostname = url + strlen(LDAP_URL);
  if (*hostname == '/')   /* no hostname? */
    hostname = DefaultHost; /* the default */

  /* dn, "distinguished name" */
  p = strchr(url + strlen(LDAP_URL), '/');
  if (p == NULL || *(p + 1) == '\0' || *(p + 1) == '?')
  {
    printfPQExpBuffer(errorMessage, libpq_gettext(
                            "invalid LDAP URL \"%s\": missing distinguished name\n"), purl);
    free(url);
    return 3;
  }
  *p = '\0';          /* terminate hostname */
  dn = p + 1;

  /* attribute */
  if ((p = strchr(dn, '?')) == NULL || *(p + 1) == '\0' || *(p + 1) == '?')
  {
    printfPQExpBuffer(errorMessage, libpq_gettext(
                            "invalid LDAP URL \"%s\": must have exactly one attribute\n"), purl);
    free(url);
    return 3;
  }
  *p = '\0';
  attrs[0] = p + 1;

  /* scope */
  if ((p = strchr(attrs[0], '?')) == NULL || *(p + 1) == '\0' || *(p + 1) == '?')
  {
    printfPQExpBuffer(errorMessage, libpq_gettext("invalid LDAP URL \"%s\": must have search scope (base/one/sub)\n"), purl);
    free(url);
    return 3;
  }
  *p = '\0';
  scopestr = p + 1;

  /* filter */
  if ((p = strchr(scopestr, '?')) == NULL || *(p + 1) == '\0' || *(p + 1) == '?')
  {
    printfPQExpBuffer(errorMessage,
              libpq_gettext("invalid LDAP URL \"%s\": no filter\n"), purl);
    free(url);
    return 3;
  }
  *p = '\0';
  filter = p + 1;
  if ((p = strchr(filter, '?')) != NULL)
    *p = '\0';

  /* port number? */
  if ((p1 = strchr(hostname, ':')) != NULL)
  {
    long    lport;

    *p1 = '\0';
    portstr = p1 + 1;
    errno = 0;
    lport = strtol(portstr, &endptr, 10);
    if (*portstr == '\0' || *endptr != '\0' || errno || lport < 0 || lport > 65535)
    {
      printfPQExpBuffer(errorMessage, libpq_gettext(
                              "invalid LDAP URL \"%s\": invalid port number\n"), purl);
      free(url);
      return 3;
    }
    port = (int) lport;
  }

  /* Allow only one attribute */
  if (strchr(attrs[0], ',') != NULL)
  {
    printfPQExpBuffer(errorMessage, libpq_gettext(
                            "invalid LDAP URL \"%s\": must have exactly one attribute\n"), purl);
    free(url);
    return 3;
  }

  /* set scope */
  if (pg_strcasecmp(scopestr, "base") == 0)
    scope = LDAP_SCOPE_BASE;
  else if (pg_strcasecmp(scopestr, "one") == 0)
    scope = LDAP_SCOPE_ONELEVEL;
  else if (pg_strcasecmp(scopestr, "sub") == 0)
    scope = LDAP_SCOPE_SUBTREE;
  else
  {
    printfPQExpBuffer(errorMessage, libpq_gettext("invalid LDAP URL \"%s\": must have search scope (base/one/sub)\n"), purl);
    free(url);
    return 3;
  }

  /* initialize LDAP structure */
  if ((ld = ldap_init(hostname, port)) == NULL)
  {
    printfPQExpBuffer(errorMessage,
              libpq_gettext("could not create LDAP structure\n"));
    free(url);
    return 3;
  }

  /*
   * Perform an explicit anonymous bind.
   *
   * LDAP does not require that an anonymous bind is performed explicitly,
   * but we want to distinguish between the case where LDAP bind does not
   * succeed within PGLDAP_TIMEOUT seconds (return 2 to continue parsing the
   * service control file) and the case where querying the LDAP server fails
   * (return 1 to end parsing).
   *
   * Unfortunately there is no way of setting a timeout that works for both
   * Windows and OpenLDAP.
   */
#ifdef WIN32
  /* the nonstandard ldap_connect function performs an anonymous bind */
  if (ldap_connect(ld, &time) != LDAP_SUCCESS)
  {
    /* error or timeout in ldap_connect */
    free(url);
    ldap_unbind(ld);
    return 2;
  }
#else             /* !WIN32 */
  /* in OpenLDAP, use the LDAP_OPT_NETWORK_TIMEOUT option */
  if (ldap_set_option(ld, LDAP_OPT_NETWORK_TIMEOUT, &time) != LDAP_SUCCESS)
  {
    free(url);
    ldap_unbind(ld);
    return 3;
  }

  /* anonymous bind */
  if ((msgid = ldap_simple_bind(ld, NULL, NULL)) == -1)
  {
    /* error or network timeout */
    free(url);
    ldap_unbind(ld);
    return 2;
  }

  /* wait some time for the connection to succeed */
  res = NULL;
  if ((rc = ldap_result(ld, msgid, LDAP_MSG_ALL, &time, &res)) == -1 ||
    res == NULL)
  {
    /* error or timeout */
    if (res != NULL)
      ldap_msgfree(res);
    free(url);
    ldap_unbind(ld);
    return 2;
  }
  ldap_msgfree(res);

  /* reset timeout */
  time.tv_sec = -1;
  if (ldap_set_option(ld, LDAP_OPT_NETWORK_TIMEOUT, &time) != LDAP_SUCCESS)
  {
    free(url);
    ldap_unbind(ld);
    return 3;
  }
#endif              /* WIN32 */

  /* search */
  res = NULL;
  if ((rc = ldap_search_st(ld, dn, scope, filter, attrs, 0, &time, &res))
    != LDAP_SUCCESS)
  {
    if (res != NULL)
      ldap_msgfree(res);
    printfPQExpBuffer(errorMessage,
              libpq_gettext("lookup on LDAP server failed: %s\n"),
              ldap_err2string(rc));
    ldap_unbind(ld);
    free(url);
    return 1;
  }

  /* complain if there was not exactly one result */
  if ((rc = ldap_count_entries(ld, res)) != 1)
  {
    printfPQExpBuffer(errorMessage,
              rc ? libpq_gettext("more than one entry found on LDAP lookup\n")
              : libpq_gettext("no entry found on LDAP lookup\n"));
    ldap_msgfree(res);
    ldap_unbind(ld);
    free(url);
    return 1;
  }

  /* get entry */
  if ((entry = ldap_first_entry(ld, res)) == NULL)
  {
    /* should never happen */
    printfPQExpBuffer(errorMessage,
              libpq_gettext("no entry found on LDAP lookup\n"));
    ldap_msgfree(res);
    ldap_unbind(ld);
    free(url);
    return 1;
  }

  /* get values */
  if ((values = ldap_get_values_len(ld, entry, attrs[0])) == NULL)
  {
    printfPQExpBuffer(errorMessage,
              libpq_gettext("attribute has no values on LDAP lookup\n"));
    ldap_msgfree(res);
    ldap_unbind(ld);
    free(url);
    return 1;
  }

  ldap_msgfree(res);
  free(url);

  if (values[0] == NULL)
  {
    printfPQExpBuffer(errorMessage,
              libpq_gettext("attribute has no values on LDAP lookup\n"));
    ldap_value_free_len(values);
    ldap_unbind(ld);
    return 1;
  }

  /* concatenate values into a single string with newline terminators */
  size = 1;         /* for the trailing null */
  for (i = 0; values[i] != NULL; i++)
    size += values[i]->bv_len + 1;
  if ((result = malloc(size)) == NULL)
  {
    printfPQExpBuffer(errorMessage,
              libpq_gettext("out of memory\n"));
    ldap_value_free_len(values);
    ldap_unbind(ld);
    return 3;
  }
  p = result;
  for (i = 0; values[i] != NULL; i++)
  {
    memcpy(p, values[i]->bv_val, values[i]->bv_len);
    p += values[i]->bv_len;
    *(p++) = '\n';
  }
  *p = '\0';

  ldap_value_free_len(values);
  ldap_unbind(ld);

  /* parse result string */
  oldstate = state = 0;
  for (p = result; *p != '\0'; ++p)
  {
    switch (state)
    {
      case 0:       /* between entries */
        if (!ld_is_sp_tab(*p) && !ld_is_nl_cr(*p))
        {
          optname = p;
          state = 1;
        }
        break;
      case 1:       /* in option name */
        if (ld_is_sp_tab(*p))
        {
          *p = '\0';
          state = 2;
        }
        else if (ld_is_nl_cr(*p))
        {
          printfPQExpBuffer(errorMessage, libpq_gettext(
                                  "missing \"=\" after \"%s\" in connection info string\n"),
                    optname);
          free(result);
          return 3;
        }
        else if (*p == '=')
        {
          *p = '\0';
          state = 3;
        }
        break;
      case 2:       /* after option name */
        if (*p == '=')
        {
          state = 3;
        }
        else if (!ld_is_sp_tab(*p))
        {
          printfPQExpBuffer(errorMessage, libpq_gettext(
                                  "missing \"=\" after \"%s\" in connection info string\n"),
                    optname);
          free(result);
          return 3;
        }
        break;
      case 3:       /* before option value */
        if (*p == '\'')
        {
          optval = p + 1;
          p1 = p + 1;
          state = 5;
        }
        else if (ld_is_nl_cr(*p))
        {
          optval = optname + strlen(optname); /* empty */
          state = 0;
        }
        else if (!ld_is_sp_tab(*p))
        {
          optval = p;
          state = 4;
        }
        break;
      case 4:       /* in unquoted option value */
        if (ld_is_sp_tab(*p) || ld_is_nl_cr(*p))
        {
          *p = '\0';
          state = 0;
        }
        break;
      case 5:       /* in quoted option value */
        if (*p == '\'')
        {
          *p1 = '\0';
          state = 0;
        }
        else if (*p == '\\')
          state = 6;
        else
          *(p1++) = *p;
        break;
      case 6:       /* in quoted option value after escape */
        *(p1++) = *p;
        state = 5;
        break;
    }

    if (state == 0 && oldstate != 0)
    {
      found_keyword = false;
      for (i = 0; options[i].keyword; i++)
      {
        if (strcmp(options[i].keyword, optname) == 0)
        {
          if (options[i].val == NULL)
          {
            options[i].val = strdup(optval);
            if (!options[i].val)
            {
              printfPQExpBuffer(errorMessage,
                        libpq_gettext("out of memory\n"));
              free(result);
              return 3;
            }
          }
          found_keyword = true;
          break;
        }
      }
      if (!found_keyword)
      {
        printfPQExpBuffer(errorMessage,
                  libpq_gettext("invalid connection option \"%s\"\n"),
                  optname);
        free(result);
        return 1;
      }
      optname = NULL;
      optval = NULL;
    }
    oldstate = state;
  }

  free(result);

  if (state == 5 || state == 6)
  {
    printfPQExpBuffer(errorMessage, libpq_gettext(
                            "unterminated quoted string in connection info string\n"));
    return 3;
  }

  return 0;
}

#endif              /* USE_LDAP */

#define MAXBUFSIZE 256

/*
 * parseServiceInfo: if a service name has been given, look it up and absorb
 * connection options from it into *options.
 *
 * Returns 0 on success, nonzero on failure.  On failure, if errorMessage
 * isn't null, also store an error message there.  (Note: the only reason
 * this function and related ones don't dump core on errorMessage == NULL
 * is the undocumented fact that printfPQExpBuffer does nothing when passed
 * a null PQExpBuffer pointer.)
 */
static int
parseServiceInfo(PQconninfoOption *options, PQExpBuffer errorMessage)
{
  const char *service = conninfo_getval(options, "service");
  char    serviceFile[MAXPGPATH];
  char     *env;
  bool    group_found = false;
  int     status;
  struct stat stat_buf;

  /*
   * We have to special-case the environment variable PGSERVICE here, since
   * this is and should be called before inserting environment defaults for
   * other connection options.
   */
  if (service == NULL)
    service = getenv("PGSERVICE");

  /* If no service name given, nothing to do */
  if (service == NULL)
    return 0;

  /*
   * Try PGSERVICEFILE if specified, else try ~/.pg_service.conf (if that
   * exists).
   */
  if ((env = getenv("PGSERVICEFILE")) != NULL)
    strlcpy(serviceFile, env, sizeof(serviceFile));
  else
  {
    char    homedir[MAXPGPATH];

    if (!pqGetHomeDirectory(homedir, sizeof(homedir)))
      goto next_file;
    snprintf(serviceFile, MAXPGPATH, "%s/%s", homedir, ".pg_service.conf");
    if (stat(serviceFile, &stat_buf) != 0)
      goto next_file;
  }

  status = parseServiceFile(serviceFile, service, options, errorMessage, &group_found);
  if (group_found || status != 0)
    return status;

next_file:

  /*
   * This could be used by any application so we can't use the binary
   * location to find our config files.
   */
  snprintf(serviceFile, MAXPGPATH, "%s/pg_service.conf",
       getenv("PGSYSCONFDIR") ? getenv("PGSYSCONFDIR") : SYSCONFDIR);
  if (stat(serviceFile, &stat_buf) != 0)
    goto last_file;

  status = parseServiceFile(serviceFile, service, options, errorMessage, &group_found);
  if (status != 0)
    return status;

last_file:
  if (!group_found)
  {
    printfPQExpBuffer(errorMessage,
              libpq_gettext("definition of service \"%s\" not found\n"), service);
    return 3;
  }

  return 0;
}

static int
parseServiceFile(const char *serviceFile,
         const char *service,
         PQconninfoOption *options,
         PQExpBuffer errorMessage,
         bool *group_found)
{
  int     linenr = 0,
        i;
  FILE     *f;
  char    buf[MAXBUFSIZE],
         *line;

  f = fopen(serviceFile, "r");
  if (f == NULL)
  {
    printfPQExpBuffer(errorMessage, libpq_gettext("service file \"%s\" not found\n"),
              serviceFile);
    return 1;
  }

  while ((line = fgets(buf, sizeof(buf), f)) != NULL)
  {
    linenr++;

    if (strlen(line) >= sizeof(buf) - 1)
    {
      fclose(f);
      printfPQExpBuffer(errorMessage,
                libpq_gettext("line %d too long in service file \"%s\"\n"),
                linenr,
                serviceFile);
      return 2;
    }

    /* ignore EOL at end of line */
    if (strlen(line) && line[strlen(line) - 1] == '\n')
      line[strlen(line) - 1] = 0;

    /* ignore leading blanks */
    while (*line && isspace((unsigned char) line[0]))
      line++;

    /* ignore comments and empty lines */
    if (strlen(line) == 0 || line[0] == '#')
      continue;

    /* Check for right groupname */
    if (line[0] == '[')
    {
      if (*group_found)
      {
        /* group info already read */
        fclose(f);
        return 0;
      }

      if (strncmp(line + 1, service, strlen(service)) == 0 &&
        line[strlen(service) + 1] == ']')
        *group_found = true;
      else
        *group_found = false;
    }
    else
    {
      if (*group_found)
      {
        /*
         * Finally, we are in the right group and can parse the line
         */
        char     *key,
               *val;
        bool    found_keyword;

#ifdef USE_LDAP
        if (strncmp(line, "ldap", 4) == 0)
        {
          int     rc = ldapServiceLookup(line, options, errorMessage);

          /* if rc = 2, go on reading for fallback */
          switch (rc)
          {
            case 0:
              fclose(f);
              return 0;
            case 1:
            case 3:
              fclose(f);
              return 3;
            case 2:
              continue;
          }
        }
#endif

        key = line;
        val = strchr(line, '=');
        if (val == NULL)
        {
          printfPQExpBuffer(errorMessage,
                    libpq_gettext("syntax error in service file \"%s\", line %d\n"),
                    serviceFile,
                    linenr);
          fclose(f);
          return 3;
        }
        *val++ = '\0';

        if (strcmp(key, "service") == 0)
        {
          printfPQExpBuffer(errorMessage,
                    libpq_gettext("nested service specifications not supported in service file \"%s\", line %d\n"),
                    serviceFile,
                    linenr);
          fclose(f);
          return 3;
        }

        /*
         * Set the parameter --- but don't override any previous
         * explicit setting.
         */
        found_keyword = false;
        for (i = 0; options[i].keyword; i++)
        {
          if (strcmp(options[i].keyword, key) == 0)
          {
            if (options[i].val == NULL)
              options[i].val = strdup(val);
            if (!options[i].val)
            {
              printfPQExpBuffer(errorMessage,
                        libpq_gettext("out of memory\n"));
              fclose(f);
              return 3;
            }
            found_keyword = true;
            break;
          }
        }

        if (!found_keyword)
        {
          printfPQExpBuffer(errorMessage,
                    libpq_gettext("syntax error in service file \"%s\", line %d\n"),
                    serviceFile,
                    linenr);
          fclose(f);
          return 3;
        }
      }
    }
  }

  fclose(f);

  return 0;
}


/*
 *    PQconninfoParse
 *
 * Parse a string like PQconnectdb() would do and return the
 * resulting connection options array.  NULL is returned on failure.
 * The result contains only options specified directly in the string,
 * not any possible default values.
 *
 * If errmsg isn't NULL, *errmsg is set to NULL on success, or a malloc'd
 * string on failure (use PQfreemem to free it).  In out-of-memory conditions
 * both *errmsg and the result could be NULL.
 *
 * NOTE: the returned array is dynamically allocated and should
 * be freed when no longer needed via PQconninfoFree().
 */
PQconninfoOption *
PQconninfoParse(const char *conninfo, char **errmsg)
{
  PQExpBufferData errorBuf;
  PQconninfoOption *connOptions;

  if (errmsg)
    *errmsg = NULL;     /* default */
  initPQExpBuffer(&errorBuf);
  if (PQExpBufferDataBroken(errorBuf))
    return NULL;     /* out of memory already :-( */
  connOptions = parse_connection_string(conninfo, &errorBuf, false);
  if (connOptions == NULL && errmsg)
    *errmsg = errorBuf.data;
  else
    termPQExpBuffer(&errorBuf);
  return connOptions;
}

/*
 * Build a working copy of the constant PQconninfoOptions array.
 */
static PQconninfoOption *
conninfo_init(PQExpBuffer errorMessage)
{
  PQconninfoOption *options;
  PQconninfoOption *opt_dest;
  const internalPQconninfoOption *cur_opt;

  /*
   * Get enough memory for all options in PQconninfoOptions, even if some
   * end up being filtered out.
   */
  options = (PQconninfoOption *) malloc(sizeof(PQconninfoOption) * sizeof(PQconninfoOptions) / sizeof(PQconninfoOptions[0]));
  if (options == NULL)
  {
    printfPQExpBuffer(errorMessage,
              libpq_gettext("out of memory\n"));
    return NULL;
  }
  opt_dest = options;

  for (cur_opt = PQconninfoOptions; cur_opt->keyword; cur_opt++)
  {
    /* Only copy the public part of the struct, not the full internal */
    memcpy(opt_dest, cur_opt, sizeof(PQconninfoOption));
    opt_dest++;
  }
  MemSet(opt_dest, 0, sizeof(PQconninfoOption));

  return options;
}

/*
 * Connection string parser
 *
 * Returns a malloc'd PQconninfoOption array, if parsing is successful.
 * Otherwise, NULL is returned and an error message is left in errorMessage.
 *
 * If use_defaults is true, default values are filled in (from a service file,
 * environment variables, etc).
 */
static PQconninfoOption *
parse_connection_string(const char *connstr, PQExpBuffer errorMessage,
            bool use_defaults)
{
  /* Parse as URI if connection string matches URI prefix */
  if (uri_prefix_length(connstr) != 0)
    return conninfo_uri_parse(connstr, errorMessage, use_defaults);

  /* Parse as default otherwise */
  return conninfo_parse(connstr, errorMessage, use_defaults);
}

/*
 * Checks if connection string starts with either of the valid URI prefix
 * designators.
 *
 * Returns the URI prefix length, 0 if the string doesn't contain a URI prefix.
 *
 * XXX this is duplicated in psql/common.c.
 */
static int
uri_prefix_length(const char *connstr)
{
  if (strncmp(connstr, uri_designator,
        sizeof(uri_designator) - 1) == 0)
    return sizeof(uri_designator) - 1;

  if (strncmp(connstr, short_uri_designator,
        sizeof(short_uri_designator) - 1) == 0)
    return sizeof(short_uri_designator) - 1;

  return 0;
}

/*
 * Recognized connection string either starts with a valid URI prefix or
 * contains a "=" in it.
 *
 * Must be consistent with parse_connection_string: anything for which this
 * returns true should at least look like it's parseable by that routine.
 *
 * XXX this is duplicated in psql/common.c
 */
static bool
recognized_connection_string(const char *connstr)
{
  return uri_prefix_length(connstr) != 0 || strchr(connstr, '=') != NULL;
}

/*
 * Subroutine for parse_connection_string
 *
 * Deal with a string containing key=value pairs.
 */
static PQconninfoOption *
conninfo_parse(const char *conninfo, PQExpBuffer errorMessage,
         bool use_defaults)
{
  char     *pname;
  char     *pval;
  char     *buf;
  char     *cp;
  char     *cp2;
  PQconninfoOption *options;

  /* Make a working copy of PQconninfoOptions */
  options = conninfo_init(errorMessage);
  if (options == NULL)
    return NULL;

  /* Need a modifiable copy of the input string */
  if ((buf = strdup(conninfo)) == NULL)
  {
    printfPQExpBuffer(errorMessage,
              libpq_gettext("out of memory\n"));
    PQconninfoFree(options);
    return NULL;
  }
  cp = buf;

  while (*cp)
  {
    /* Skip blanks before the parameter name */
    if (isspace((unsigned char) *cp))
    {
      cp++;
      continue;
    }

    /* Get the parameter name */
    pname = cp;
    while (*cp)
    {
      if (*cp == '=')
        break;
      if (isspace((unsigned char) *cp))
      {
        *cp++ = '\0';
        while (*cp)
        {
          if (!isspace((unsigned char) *cp))
            break;
          cp++;
        }
        break;
      }
      cp++;
    }

    /* Check that there is a following '=' */
    if (*cp != '=')
    {
      printfPQExpBuffer(errorMessage,
                libpq_gettext("missing \"=\" after \"%s\" in connection info string\n"),
                pname);
      PQconninfoFree(options);
      free(buf);
      return NULL;
    }
    *cp++ = '\0';

    /* Skip blanks after the '=' */
    while (*cp)
    {
      if (!isspace((unsigned char) *cp))
        break;
      cp++;
    }

    /* Get the parameter value */
    pval = cp;

    if (*cp != '\'')
    {
      cp2 = pval;
      while (*cp)
      {
        if (isspace((unsigned char) *cp))
        {
          *cp++ = '\0';
          break;
        }
        if (*cp == '\\')
        {
          cp++;
          if (*cp != '\0')
            *cp2++ = *cp++;
        }
        else
          *cp2++ = *cp++;
      }
      *cp2 = '\0';
    }
    else
    {
      cp2 = pval;
      cp++;
      for (;;)
      {
        if (*cp == '\0')
        {
          printfPQExpBuffer(errorMessage,
                    libpq_gettext("unterminated quoted string in connection info string\n"));
          PQconninfoFree(options);
          free(buf);
          return NULL;
        }
        if (*cp == '\\')
        {
          cp++;
          if (*cp != '\0')
            *cp2++ = *cp++;
          continue;
        }
        if (*cp == '\'')
        {
          *cp2 = '\0';
          cp++;
          break;
        }
        *cp2++ = *cp++;
      }
    }

    /*
     * Now that we have the name and the value, store the record.
     */
    if (!conninfo_storeval(options, pname, pval, errorMessage, false, false))
    {
      PQconninfoFree(options);
      free(buf);
      return NULL;
    }
  }

  /* Done with the modifiable input string */
  free(buf);

  /*
   * Add in defaults if the caller wants that.
   */
  if (use_defaults)
  {
    if (!conninfo_add_defaults(options, errorMessage))
    {
      PQconninfoFree(options);
      return NULL;
    }
  }

  return options;
}

/*
 * Conninfo array parser routine
 *
 * If successful, a malloc'd PQconninfoOption array is returned.
 * If not successful, NULL is returned and an error message is
 * left in errorMessage.
 * Defaults are supplied (from a service file, environment variables, etc)
 * for unspecified options, but only if use_defaults is true.
 *
 * If expand_dbname is non-zero, and the value passed for the first occurrence
 * of "dbname" keyword is a connection string (as indicated by
 * recognized_connection_string) then parse and process it, overriding any
 * previously processed conflicting keywords. Subsequent keywords will take
 * precedence, however. In-tree programs generally specify expand_dbname=true,
 * so command-line arguments naming a database can use a connection string.
 * Some code acquires arbitrary database names from known-literal sources like
 * PQdb(), PQconninfoParse() and pg_database.datname.  When connecting to such
 * a database, in-tree code first wraps the name in a connection string.
 */
static PQconninfoOption *
conninfo_array_parse(const char *const *keywords, const char *const *values,
           PQExpBuffer errorMessage, bool use_defaults,
           int expand_dbname)
{
  PQconninfoOption *options;
  PQconninfoOption *dbname_options = NULL;
  PQconninfoOption *option;
  int     i = 0;

  /*
   * If expand_dbname is non-zero, check keyword "dbname" to see if val is
   * actually a recognized connection string.
   */
  while (expand_dbname && keywords[i])
  {
    const char *pname = keywords[i];
    const char *pvalue = values[i];

    /* first find "dbname" if any */
    if (strcmp(pname, "dbname") == 0 && pvalue)
    {
      /*
       * If value is a connection string, parse it, but do not use
       * defaults here -- those get picked up later. We only want to
       * override for those parameters actually passed.
       */
      if (recognized_connection_string(pvalue))
      {
        dbname_options = parse_connection_string(pvalue, errorMessage, false);
        if (dbname_options == NULL)
          return NULL;
      }
      break;
    }
    ++i;
  }

  /* Make a working copy of PQconninfoOptions */
  options = conninfo_init(errorMessage);
  if (options == NULL)
  {
    PQconninfoFree(dbname_options);
    return NULL;
  }

  /* Parse the keywords/values arrays */
  i = 0;
  while (keywords[i])
  {
    const char *pname = keywords[i];
    const char *pvalue = values[i];

    if (pvalue != NULL && pvalue[0] != '\0')
    {
      /* Search for the param record */
      for (option = options; option->keyword != NULL; option++)
      {
        if (strcmp(option->keyword, pname) == 0)
          break;
      }

      /* Check for invalid connection option */
      if (option->keyword == NULL)
      {
        printfPQExpBuffer(errorMessage,
                  libpq_gettext("invalid connection option \"%s\"\n"),
                  pname);
        PQconninfoFree(options);
        PQconninfoFree(dbname_options);
        return NULL;
      }

      /*
       * If we are on the first dbname parameter, and we have a parsed
       * connection string, copy those parameters across, overriding any
       * existing previous settings.
       */
      if (strcmp(pname, "dbname") == 0 && dbname_options)
      {
        PQconninfoOption *str_option;

        for (str_option = dbname_options; str_option->keyword != NULL; str_option++)
        {
          if (str_option->val != NULL)
          {
            int     k;

            for (k = 0; options[k].keyword; k++)
            {
              if (strcmp(options[k].keyword, str_option->keyword) == 0)
              {
                if (options[k].val)
                  free(options[k].val);
                options[k].val = strdup(str_option->val);
                if (!options[k].val)
                {
                  printfPQExpBuffer(errorMessage,
                            libpq_gettext("out of memory\n"));
                  PQconninfoFree(options);
                  PQconninfoFree(dbname_options);
                  return NULL;
                }
                break;
              }
            }
          }
        }

        /*
         * Forget the parsed connection string, so that any subsequent
         * dbname parameters will not be expanded.
         */
        PQconninfoFree(dbname_options);
        dbname_options = NULL;
      }
      else
      {
        /*
         * Store the value, overriding previous settings
         */
        if (option->val)
          free(option->val);
        option->val = strdup(pvalue);
        if (!option->val)
        {
          printfPQExpBuffer(errorMessage,
                    libpq_gettext("out of memory\n"));
          PQconninfoFree(options);
          PQconninfoFree(dbname_options);
          return NULL;
        }
      }
    }
    ++i;
  }
  PQconninfoFree(dbname_options);

  /*
   * Add in defaults if the caller wants that.
   */
  if (use_defaults)
  {
    if (!conninfo_add_defaults(options, errorMessage))
    {
      PQconninfoFree(options);
      return NULL;
    }
  }

  return options;
}

/*
 * Add the default values for any unspecified options to the connection
 * options array.
 *
 * Defaults are obtained from a service file, environment variables, etc.
 *
 * Returns true if successful, otherwise false; errorMessage, if supplied,
 * is filled in upon failure.  Note that failure to locate a default value
 * is not an error condition here --- we just leave the option's value as
 * NULL.
 */
static bool
conninfo_add_defaults(PQconninfoOption *options, PQExpBuffer errorMessage)
{
  PQconninfoOption *option;
  char     *tmp;

  /*
   * If there's a service spec, use it to obtain any not-explicitly-given
   * parameters.  Ignore error if no error message buffer is passed because
   * there is no way to pass back the failure message.
   */
  if (parseServiceInfo(options, errorMessage) != 0 && errorMessage)
    return false;

  /*
   * Get the fallback resources for parameters not specified in the conninfo
   * string nor the service.
   */
  for (option = options; option->keyword != NULL; option++)
  {
    if (option->val != NULL)
      continue;     /* Value was in conninfo or service */

    /*
     * Try to get the environment variable fallback
     */
    if (option->envvar != NULL)
    {
      if ((tmp = getenv(option->envvar)) != NULL)
      {
        option->val = strdup(tmp);
        if (!option->val)
        {
          if (errorMessage)
            printfPQExpBuffer(errorMessage,
                      libpq_gettext("out of memory\n"));
          return false;
        }
        continue;
      }
    }

    /*
     * Interpret the deprecated PGREQUIRESSL environment variable.  Per
     * tradition, translate values starting with "1" to sslmode=require,
     * and ignore other values.  Given both PGREQUIRESSL=1 and PGSSLMODE,
     * PGSSLMODE takes precedence; the opposite was true before v9.3.
     */
    if (strcmp(option->keyword, "sslmode") == 0)
    {
      const char *requiresslenv = getenv("PGREQUIRESSL");

      if (requiresslenv != NULL && requiresslenv[0] == '1')
      {
        option->val = strdup("require");
        if (!option->val)
        {
          if (errorMessage)
            printfPQExpBuffer(errorMessage,
                      libpq_gettext("out of memory\n"));
          return false;
        }
        continue;
      }
    }

    /*
     * No environment variable specified or the variable isn't set - try
     * compiled-in default
     */
    if (option->compiled != NULL)
    {
      option->val = strdup(option->compiled);
      if (!option->val)
      {
        if (errorMessage)
          printfPQExpBuffer(errorMessage,
                    libpq_gettext("out of memory\n"));
        return false;
      }
      continue;
    }

    /*
     * Special handling for "user" option.  Note that if pg_fe_getauthname
     * fails, we just leave the value as NULL; there's no need for this to
     * be an error condition if the caller provides a user name.  The only
     * reason we do this now at all is so that callers of PQconndefaults
     * will see a correct default (barring error, of course).
     */
    if (strcmp(option->keyword, "user") == 0)
    {
      /* Yugabyte default username to "yugabyte" */
      option->val = strdup("yugabyte");
      continue;
    }

    /*
     * Special handling for "dbname" option.
     */
    if (strcmp(option->keyword, "dbname") == 0)
    {
      /* Yugabyte default dbname to "yugabyte" */
      option->val = strdup("yugabyte");
      continue;
    }
  }

  return true;
}

/*
 * Subroutine for parse_connection_string
 *
 * Deal with a URI connection string.
 */
static PQconninfoOption *
conninfo_uri_parse(const char *uri, PQExpBuffer errorMessage,
           bool use_defaults)
{
  PQconninfoOption *options;

  /* Make a working copy of PQconninfoOptions */
  options = conninfo_init(errorMessage);
  if (options == NULL)
    return NULL;

  if (!conninfo_uri_parse_options(options, uri, errorMessage))
  {
    PQconninfoFree(options);
    return NULL;
  }

  /*
   * Add in defaults if the caller wants that.
   */
  if (use_defaults)
  {
    if (!conninfo_add_defaults(options, errorMessage))
    {
      PQconninfoFree(options);
      return NULL;
    }
  }

  return options;
}

/*
 * conninfo_uri_parse_options
 *    Actual URI parser.
 *
 * If successful, returns true while the options array is filled with parsed
 * options from the URI.
 * If not successful, returns false and fills errorMessage accordingly.
 *
 * Parses the connection URI string in 'uri' according to the URI syntax (RFC
 * 3986):
 *
 * postgresql://[user[:password]@][netloc][:port][/dbname][?param1=value1&...]
 *
 * where "netloc" is a hostname, an IPv4 address, or an IPv6 address surrounded
 * by literal square brackets.  As an extension, we also allow multiple
 * netloc[:port] specifications, separated by commas:
 *
 * postgresql://[user[:password]@][netloc][:port][,...][/dbname][?param1=value1&...]
 *
 * Any of the URI parts might use percent-encoding (%xy).
 */
static bool
conninfo_uri_parse_options(PQconninfoOption *options, const char *uri,
               PQExpBuffer errorMessage)
{
  int     prefix_len;
  char     *p;
  char     *buf = NULL;
  char     *start;
  char    prevchar = '\0';
  char     *user = NULL;
  char     *host = NULL;
  bool    retval = false;
  PQExpBufferData hostbuf;
  PQExpBufferData portbuf;

  initPQExpBuffer(&hostbuf);
  initPQExpBuffer(&portbuf);
  if (PQExpBufferDataBroken(hostbuf) || PQExpBufferDataBroken(portbuf))
  {
    printfPQExpBuffer(errorMessage,
              libpq_gettext("out of memory\n"));
    goto cleanup;
  }

  /* need a modifiable copy of the input URI */
  buf = strdup(uri);
  if (buf == NULL)
  {
    printfPQExpBuffer(errorMessage,
              libpq_gettext("out of memory\n"));
    goto cleanup;
  }
  start = buf;

  /* Skip the URI prefix */
  prefix_len = uri_prefix_length(uri);
  if (prefix_len == 0)
  {
    /* Should never happen */
    printfPQExpBuffer(errorMessage,
              libpq_gettext("invalid URI propagated to internal parser routine: \"%s\"\n"),
              uri);
    goto cleanup;
  }
  start += prefix_len;
  p = start;

  /* Look ahead for possible user credentials designator */
  while (*p && *p != '@' && *p != '/')
    ++p;
  if (*p == '@')
  {
    /*
     * Found username/password designator, so URI should be of the form
     * "scheme://user[:password]@[netloc]".
     */
    user = start;

    p = user;
    while (*p != ':' && *p != '@')
      ++p;

    /* Save last char and cut off at end of user name */
    prevchar = *p;
    *p = '\0';

    if (*user &&
      !conninfo_storeval(options, "user", user,
                 errorMessage, false, true))
      goto cleanup;

    if (prevchar == ':')
    {
      const char *password = p + 1;

      while (*p != '@')
        ++p;
      *p = '\0';

      if (*password &&
        !conninfo_storeval(options, "password", password,
                   errorMessage, false, true))
        goto cleanup;
    }

    /* Advance past end of parsed user name or password token */
    ++p;
  }
  else
  {
    /*
     * No username/password designator found.  Reset to start of URI.
     */
    p = start;
  }

  /*
   * There may be multiple netloc[:port] pairs, each separated from the next
   * by a comma.  When we initially enter this loop, "p" has been
   * incremented past optional URI credential information at this point and
   * now points at the "netloc" part of the URI.  On subsequent loop
   * iterations, "p" has been incremented past the comma separator and now
   * points at the start of the next "netloc".
   */
  for (;;)
  {
    /*
     * Look for IPv6 address.
     */
    if (*p == '[')
    {
      host = ++p;
      while (*p && *p != ']')
        ++p;
      if (!*p)
      {
        printfPQExpBuffer(errorMessage,
                  libpq_gettext("end of string reached when looking for matching \"]\" in IPv6 host address in URI: \"%s\"\n"),
                  uri);
        goto cleanup;
      }
      if (p == host)
      {
        printfPQExpBuffer(errorMessage,
                  libpq_gettext("IPv6 host address may not be empty in URI: \"%s\"\n"),
                  uri);
        goto cleanup;
      }

      /* Cut off the bracket and advance */
      *(p++) = '\0';

      /*
       * The address may be followed by a port specifier or a slash or a
       * query or a separator comma.
       */
      if (*p && *p != ':' && *p != '/' && *p != '?' && *p != ',')
      {
        printfPQExpBuffer(errorMessage,
                  libpq_gettext("unexpected character \"%c\" at position %d in URI (expected \":\" or \"/\"): \"%s\"\n"),
                  *p, (int) (p - buf + 1), uri);
        goto cleanup;
      }
    }
    else
    {
      /* not an IPv6 address: DNS-named or IPv4 netloc */
      host = p;

      /*
       * Look for port specifier (colon) or end of host specifier
       * (slash) or query (question mark) or host separator (comma).
       */
      while (*p && *p != ':' && *p != '/' && *p != '?' && *p != ',')
        ++p;
    }

    /* Save the hostname terminator before we null it */
    prevchar = *p;
    *p = '\0';

    appendPQExpBufferStr(&hostbuf, host);

    if (prevchar == ':')
    {
      const char *port = ++p; /* advance past host terminator */

      while (*p && *p != '/' && *p != '?' && *p != ',')
        ++p;

      prevchar = *p;
      *p = '\0';

      appendPQExpBufferStr(&portbuf, port);
    }

    if (prevchar != ',')
      break;
    ++p;          /* advance past comma separator */
    appendPQExpBufferChar(&hostbuf, ',');
    appendPQExpBufferChar(&portbuf, ',');
  }

  /* Save final values for host and port. */
  if (PQExpBufferDataBroken(hostbuf) || PQExpBufferDataBroken(portbuf))
    goto cleanup;
  if (hostbuf.data[0] &&
    !conninfo_storeval(options, "host", hostbuf.data,
               errorMessage, false, true))
    goto cleanup;
  if (portbuf.data[0] &&
    !conninfo_storeval(options, "port", portbuf.data,
               errorMessage, false, true))
    goto cleanup;

  if (prevchar && prevchar != '?')
  {
    const char *dbname = ++p; /* advance past host terminator */

    /* Look for query parameters */
    while (*p && *p != '?')
      ++p;

    prevchar = *p;
    *p = '\0';

    /*
     * Avoid setting dbname to an empty string, as it forces the default
     * value (username) and ignores $PGDATABASE, as opposed to not setting
     * it at all.
     */
    if (*dbname &&
      !conninfo_storeval(options, "dbname", dbname,
                 errorMessage, false, true))
      goto cleanup;
  }

  if (prevchar)
  {
    ++p;          /* advance past terminator */

    if (!conninfo_uri_parse_params(p, options, errorMessage))
      goto cleanup;
  }

  /* everything parsed okay */
  retval = true;

cleanup:
  termPQExpBuffer(&hostbuf);
  termPQExpBuffer(&portbuf);
  if (buf)
    free(buf);
  return retval;
}

/*
 * Connection URI parameters parser routine
 *
 * If successful, returns true while connOptions is filled with parsed
 * parameters.  Otherwise, returns false and fills errorMessage appropriately.
 *
 * Destructively modifies 'params' buffer.
 */
static bool
conninfo_uri_parse_params(char *params,
              PQconninfoOption *connOptions,
              PQExpBuffer errorMessage)
{
  while (*params)
  {
    char     *keyword = params;
    char     *value = NULL;
    char     *p = params;
    bool    malloced = false;

    /*
     * Scan the params string for '=' and '&', marking the end of keyword
     * and value respectively.
     */
    for (;;)
    {
      if (*p == '=')
      {
        /* Was there '=' already? */
        if (value != NULL)
        {
          printfPQExpBuffer(errorMessage,
                    libpq_gettext("extra key/value separator \"=\" in URI query parameter: \"%s\"\n"),
                    keyword);
          return false;
        }
        /* Cut off keyword, advance to value */
        *p++ = '\0';
        value = p;
      }
      else if (*p == '&' || *p == '\0')
      {
        /*
         * If not at the end, cut off value and advance; leave p
         * pointing to start of the next parameter, if any.
         */
        if (*p != '\0')
          *p++ = '\0';
        /* Was there '=' at all? */
        if (value == NULL)
        {
          printfPQExpBuffer(errorMessage,
                    libpq_gettext("missing key/value separator \"=\" in URI query parameter: \"%s\"\n"),
                    keyword);
          return false;
        }
        /* Got keyword and value, go process them. */
        break;
      }
      else
        ++p;     /* Advance over all other bytes. */
    }

    keyword = conninfo_uri_decode(keyword, errorMessage);
    if (keyword == NULL)
    {
      /* conninfo_uri_decode already set an error message */
      return false;
    }
    value = conninfo_uri_decode(value, errorMessage);
    if (value == NULL)
    {
      /* conninfo_uri_decode already set an error message */
      free(keyword);
      return false;
    }
    malloced = true;

    /*
     * Special keyword handling for improved JDBC compatibility.
     */
    if (strcmp(keyword, "ssl") == 0 &&
      strcmp(value, "true") == 0)
    {
      free(keyword);
      free(value);
      malloced = false;

      keyword = "sslmode";
      value = "require";
    }

    /*
     * Store the value if the corresponding option exists; ignore
     * otherwise.  At this point both keyword and value are not
     * URI-encoded.
     */
    if (!conninfo_storeval(connOptions, keyword, value,
                 errorMessage, true, false))
    {
      /* Insert generic message if conninfo_storeval didn't give one. */
      if (errorMessage->len == 0)
        printfPQExpBuffer(errorMessage,
                  libpq_gettext("invalid URI query parameter: \"%s\"\n"),
                  keyword);
      /* And fail. */
      if (malloced)
      {
        free(keyword);
        free(value);
      }
      return false;
    }

    if (malloced)
    {
      free(keyword);
      free(value);
    }

    /* Proceed to next key=value pair, if any */
    params = p;
  }

  return true;
}

/*
 * Connection URI decoder routine
 *
 * If successful, returns the malloc'd decoded string.
 * If not successful, returns NULL and fills errorMessage accordingly.
 *
 * The string is decoded by replacing any percent-encoded tokens with
 * corresponding characters, while preserving any non-encoded characters.  A
 * percent-encoded token is a character triplet: a percent sign, followed by a
 * pair of hexadecimal digits (0-9A-F), where lower- and upper-case letters are
 * treated identically.
 */
static char *
conninfo_uri_decode(const char *str, PQExpBuffer errorMessage)
{
  char     *buf;
  char     *p;
  const char *q = str;

  buf = malloc(strlen(str) + 1);
  if (buf == NULL)
  {
    printfPQExpBuffer(errorMessage, libpq_gettext("out of memory\n"));
    return NULL;
  }
  p = buf;

  for (;;)
  {
    if (*q != '%')
    {
      /* copy and check for NUL terminator */
      if (!(*(p++) = *(q++)))
        break;
    }
    else
    {
      int     hi;
      int     lo;
      int     c;

      ++q;        /* skip the percent sign itself */

      /*
       * Possible EOL will be caught by the first call to
       * get_hexdigit(), so we never dereference an invalid q pointer.
       */
      if (!(get_hexdigit(*q++, &hi) && get_hexdigit(*q++, &lo)))
      {
        printfPQExpBuffer(errorMessage,
                  libpq_gettext("invalid percent-encoded token: \"%s\"\n"),
                  str);
        free(buf);
        return NULL;
      }

      c = (hi << 4) | lo;
      if (c == 0)
      {
        printfPQExpBuffer(errorMessage,
                  libpq_gettext("forbidden value %%00 in percent-encoded value: \"%s\"\n"),
                  str);
        free(buf);
        return NULL;
      }
      *(p++) = c;
    }
  }

  return buf;
}

/*
 * Convert hexadecimal digit character to its integer value.
 *
 * If successful, returns true and value is filled with digit's base 16 value.
 * If not successful, returns false.
 *
 * Lower- and upper-case letters in the range A-F are treated identically.
 */
static bool
get_hexdigit(char digit, int *value)
{
  if ('0' <= digit && digit <= '9')
    *value = digit - '0';
  else if ('A' <= digit && digit <= 'F')
    *value = digit - 'A' + 10;
  else if ('a' <= digit && digit <= 'f')
    *value = digit - 'a' + 10;
  else
    return false;

  return true;
}

/*
 * Find an option value corresponding to the keyword in the connOptions array.
 *
 * If successful, returns a pointer to the corresponding option's value.
 * If not successful, returns NULL.
 */
static const char *
conninfo_getval(PQconninfoOption *connOptions,
        const char *keyword)
{
  PQconninfoOption *option;

  option = conninfo_find(connOptions, keyword);

  return option ? option->val : NULL;
}

/*
 * Store a (new) value for an option corresponding to the keyword in
 * connOptions array.
 *
 * If uri_decode is true, the value is URI-decoded.  The keyword is always
 * assumed to be non URI-encoded.
 *
 * If successful, returns a pointer to the corresponding PQconninfoOption,
 * which value is replaced with a strdup'd copy of the passed value string.
 * The existing value for the option is free'd before replacing, if any.
 *
 * If not successful, returns NULL and fills errorMessage accordingly.
 * However, if the reason of failure is an invalid keyword being passed and
 * ignoreMissing is true, errorMessage will be left untouched.
 */
static PQconninfoOption *
conninfo_storeval(PQconninfoOption *connOptions,
          const char *keyword, const char *value,
          PQExpBuffer errorMessage, bool ignoreMissing,
          bool uri_decode)
{
  PQconninfoOption *option;
  char     *value_copy;

  /*
   * For backwards compatibility, requiressl=1 gets translated to
   * sslmode=require, and requiressl=0 gets translated to sslmode=prefer
   * (which is the default for sslmode).
   */
  if (strcmp(keyword, "requiressl") == 0)
  {
    keyword = "sslmode";
    if (value[0] == '1')
      value = "require";
    else
      value = "prefer";
  }

  option = conninfo_find(connOptions, keyword);
  if (option == NULL)
  {
    if (!ignoreMissing)
      printfPQExpBuffer(errorMessage,
                libpq_gettext("invalid connection option \"%s\"\n"),
                keyword);
    return NULL;
  }

  if (uri_decode)
  {
    value_copy = conninfo_uri_decode(value, errorMessage);
    if (value_copy == NULL)
      /* conninfo_uri_decode already set an error message */
      return NULL;
  }
  else
  {
    value_copy = strdup(value);
    if (value_copy == NULL)
    {
      printfPQExpBuffer(errorMessage, libpq_gettext("out of memory\n"));
      return NULL;
    }
  }

  if (option->val)
    free(option->val);
  option->val = value_copy;

  return option;
}

/*
 * Find a PQconninfoOption option corresponding to the keyword in the
 * connOptions array.
 *
 * If successful, returns a pointer to the corresponding PQconninfoOption
 * structure.
 * If not successful, returns NULL.
 */
static PQconninfoOption *
conninfo_find(PQconninfoOption *connOptions, const char *keyword)
{
  PQconninfoOption *option;

  for (option = connOptions; option->keyword != NULL; option++)
  {
    if (strcmp(option->keyword, keyword) == 0)
      return option;
  }

  return NULL;
}


/*
 * Return the connection options used for the connection
 */
PQconninfoOption *
PQconninfo(PGconn *conn)
{
  PQExpBufferData errorBuf;
  PQconninfoOption *connOptions;

  if (conn == NULL)
    return NULL;

  /* We don't actually report any errors here, but callees want a buffer */
  initPQExpBuffer(&errorBuf);
  if (PQExpBufferDataBroken(errorBuf))
    return NULL;     /* out of memory already :-( */

  connOptions = conninfo_init(&errorBuf);

  if (connOptions != NULL)
  {
    const internalPQconninfoOption *option;

    for (option = PQconninfoOptions; option->keyword; option++)
    {
      char    **connmember;

      if (option->connofs < 0)
        continue;

      connmember = (char **) ((char *) conn + option->connofs);

      if (*connmember)
        conninfo_storeval(connOptions, option->keyword, *connmember,
                  &errorBuf, true, false);
    }
  }

  termPQExpBuffer(&errorBuf);

  return connOptions;
}


void
PQconninfoFree(PQconninfoOption *connOptions)
{
  PQconninfoOption *option;

  if (connOptions == NULL)
    return;

  for (option = connOptions; option->keyword != NULL; option++)
  {
    if (option->val != NULL)
      free(option->val);
  }
  free(connOptions);
}


/* =========== accessor functions for PGconn ========= */
char *
PQdb(const PGconn *conn)
{
  if (!conn)
    return NULL;
  return conn->dbName;
}

char *
PQuser(const PGconn *conn)
{
  if (!conn)
    return NULL;
  return conn->pguser;
}

char *
PQpass(const PGconn *conn)
{
  char     *password = NULL;

  if (!conn)
    return NULL;
  if (conn->connhost != NULL)
    password = conn->connhost[conn->whichhost].password;
  if (password == NULL)
    password = conn->pgpass;
  /* Historically we've returned "" not NULL for no password specified */
  if (password == NULL)
    password = "";
  return password;
}

char *
PQhost(const PGconn *conn)
{
  if (!conn)
    return NULL;

  if (conn->connhost != NULL)
  {
    if (conn->connhost[conn->whichhost].host != NULL &&
      conn->connhost[conn->whichhost].host[0] != '\0')
      return conn->connhost[conn->whichhost].host;
    else if (conn->connhost[conn->whichhost].hostaddr != NULL &&
         conn->connhost[conn->whichhost].hostaddr[0] != '\0')
      return conn->connhost[conn->whichhost].hostaddr;
  }

  return "";
}

char *
PQport(const PGconn *conn)
{
  if (!conn)
    return NULL;

  if (conn->connhost != NULL)
    return conn->connhost[conn->whichhost].port;

  return "";
}

char *
PQtty(const PGconn *conn)
{
  if (!conn)
    return NULL;
  return conn->pgtty;
}

char *
PQoptions(const PGconn *conn)
{
  if (!conn)
    return NULL;
  return conn->pgoptions;
}

ConnStatusType
PQstatus(const PGconn *conn)
{
  if (!conn)
    return CONNECTION_BAD;
  return conn->status;
}

PGTransactionStatusType
PQtransactionStatus(const PGconn *conn)
{
  if (!conn || conn->status != CONNECTION_OK)
    return PQTRANS_UNKNOWN;
  if (conn->asyncStatus != PGASYNC_IDLE)
    return PQTRANS_ACTIVE;
  return conn->xactStatus;
}

const char *
PQparameterStatus(const PGconn *conn, const char *paramName)
{
  const pgParameterStatus *pstatus;

  if (!conn || !paramName)
    return NULL;
  for (pstatus = conn->pstatus; pstatus != NULL; pstatus = pstatus->next)
  {
    if (strcmp(pstatus->name, paramName) == 0)
      return pstatus->value;
  }
  return NULL;
}

int
PQprotocolVersion(const PGconn *conn)
{
  if (!conn)
    return 0;
  if (conn->status == CONNECTION_BAD)
    return 0;
  return PG_PROTOCOL_MAJOR(conn->pversion);
}

int
PQserverVersion(const PGconn *conn)
{
  if (!conn)
    return 0;
  if (conn->status == CONNECTION_BAD)
    return 0;
  return conn->sversion;
}

char *
PQerrorMessage(const PGconn *conn)
{
  if (!conn)
    return libpq_gettext("connection pointer is NULL\n");

  return conn->errorMessage.data;
}

/*
 * In Windows, socket values are unsigned, and an invalid socket value
 * (INVALID_SOCKET) is ~0, which equals -1 in comparisons (with no compiler
 * warning). Ideally we would return an unsigned value for PQsocket() on
 * Windows, but that would cause the function's return value to differ from
 * Unix, so we just return -1 for invalid sockets.
 * http://msdn.microsoft.com/en-us/library/windows/desktop/cc507522%28v=vs.85%29.aspx
 * http://stackoverflow.com/questions/10817252/why-is-invalid-socket-defined-as-0-in-winsock2-h-c
 */
int
PQsocket(const PGconn *conn)
{
  if (!conn)
    return -1;
  return (conn->sock != PGINVALID_SOCKET) ? conn->sock : -1;
}

int
PQbackendPID(const PGconn *conn)
{
  if (!conn || conn->status != CONNECTION_OK)
    return 0;
  return conn->be_pid;
}

int
PQconnectionNeedsPassword(const PGconn *conn)
{
  char     *password;

  if (!conn)
    return false;
  password = PQpass(conn);
  if (conn->password_needed &&
    (password == NULL || password[0] == '\0'))
    return true;
  else
    return false;
}

int
PQconnectionUsedPassword(const PGconn *conn)
{
  if (!conn)
    return false;
  if (conn->password_needed)
    return true;
  else
    return false;
}

int
PQclientEncoding(const PGconn *conn)
{
  if (!conn || conn->status != CONNECTION_OK)
    return -1;
  return conn->client_encoding;
}

int
PQsetClientEncoding(PGconn *conn, const char *encoding)
{
  char    qbuf[128];
  static const char query[] = "set client_encoding to '%s'";
  PGresult   *res;
  int     status;

  if (!conn || conn->status != CONNECTION_OK)
    return -1;

  if (!encoding)
    return -1;

  /* Resolve special "auto" value from the locale */
  if (strcmp(encoding, "auto") == 0)
    encoding = pg_encoding_to_char(pg_get_encoding_from_locale(NULL, true));

  /* check query buffer overflow */
  if (sizeof(qbuf) < (sizeof(query) + strlen(encoding)))
    return -1;

  /* ok, now send a query */
  sprintf(qbuf, query, encoding);
  res = PQexec(conn, qbuf);

  if (res == NULL)
    return -1;
  if (res->resultStatus != PGRES_COMMAND_OK)
    status = -1;
  else
  {
    /*
     * In protocol 2 we have to assume the setting will stick, and adjust
     * our state immediately.  In protocol 3 and up we can rely on the
     * backend to report the parameter value, and we'll change state at
     * that time.
     */
    if (PG_PROTOCOL_MAJOR(conn->pversion) < 3)
      pqSaveParameterStatus(conn, "client_encoding", encoding);
    status = 0;       /* everything is ok */
  }
  PQclear(res);
  return status;
}

PGVerbosity
PQsetErrorVerbosity(PGconn *conn, PGVerbosity verbosity)
{
  PGVerbosity old;

  if (!conn)
    return PQERRORS_DEFAULT;
  old = conn->verbosity;
  conn->verbosity = verbosity;
  return old;
}

PGContextVisibility
PQsetErrorContextVisibility(PGconn *conn, PGContextVisibility show_context)
{
  PGContextVisibility old;

  if (!conn)
    return PQSHOW_CONTEXT_ERRORS;
  old = conn->show_context;
  conn->show_context = show_context;
  return old;
}

void
PQtrace(PGconn *conn, FILE *debug_port)
{
  if (conn == NULL)
    return;
  PQuntrace(conn);
  conn->Pfdebug = debug_port;
}

void
PQuntrace(PGconn *conn)
{
  if (conn == NULL)
    return;
  if (conn->Pfdebug)
  {
    fflush(conn->Pfdebug);
    conn->Pfdebug = NULL;
  }
}

PQnoticeReceiver
PQsetNoticeReceiver(PGconn *conn, PQnoticeReceiver proc, void *arg)
{
  PQnoticeReceiver old;

  if (conn == NULL)
    return NULL;

  old = conn->noticeHooks.noticeRec;
  if (proc)
  {
    conn->noticeHooks.noticeRec = proc;
    conn->noticeHooks.noticeRecArg = arg;
  }
  return old;
}

PQnoticeProcessor
PQsetNoticeProcessor(PGconn *conn, PQnoticeProcessor proc, void *arg)
{
  PQnoticeProcessor old;

  if (conn == NULL)
    return NULL;

  old = conn->noticeHooks.noticeProc;
  if (proc)
  {
    conn->noticeHooks.noticeProc = proc;
    conn->noticeHooks.noticeProcArg = arg;
  }
  return old;
}

/*
 * The default notice message receiver just gets the standard notice text
 * and sends it to the notice processor.  This two-level setup exists
 * mostly for backwards compatibility; perhaps we should deprecate use of
 * PQsetNoticeProcessor?
 */
static void
defaultNoticeReceiver(void *arg, const PGresult *res)
{
  (void) arg;         /* not used */
  if (res->noticeHooks.noticeProc != NULL)
    res->noticeHooks.noticeProc(res->noticeHooks.noticeProcArg,
                  PQresultErrorMessage(res));
}

/*
 * The default notice message processor just prints the
 * message on stderr.  Applications can override this if they
 * want the messages to go elsewhere (a window, for example).
 * Note that simply discarding notices is probably a bad idea.
 */
static void
defaultNoticeProcessor(void *arg, const char *message)
{
  (void) arg;         /* not used */
  /* Note: we expect the supplied string to end with a newline already. */
  fprintf(stderr, "%s", message);
}

/*
 * returns a pointer to the next token or NULL if the current
 * token doesn't match
 */
static char *
pwdfMatchesString(char *buf, const char *token)
{
  char     *tbuf;
  const char *ttok;
  bool    bslash = false;

  if (buf == NULL || token == NULL)
    return NULL;
  tbuf = buf;
  ttok = token;
  if (tbuf[0] == '*' && tbuf[1] == ':')
    return tbuf + 2;
  while (*tbuf != 0)
  {
    if (*tbuf == '\\' && !bslash)
    {
      tbuf++;
      bslash = true;
    }
    if (*tbuf == ':' && *ttok == 0 && !bslash)
      return tbuf + 1;
    bslash = false;
    if (*ttok == 0)
      return NULL;
    if (*tbuf == *ttok)
    {
      tbuf++;
      ttok++;
    }
    else
      return NULL;
  }
  return NULL;
}

/* Get a password from the password file. Return value is malloc'd. */
static char *
passwordFromFile(const char *hostname, const char *port, const char *dbname,
         const char *username, const char *pgpassfile)
{
  FILE     *fp;
  struct stat stat_buf;

#define LINELEN NAMEDATALEN*5
  char    buf[LINELEN];

  if (dbname == NULL || dbname[0] == '\0')
    return NULL;

  if (username == NULL || username[0] == '\0')
    return NULL;

  /* 'localhost' matches pghost of '' or the default socket directory */
  if (hostname == NULL || hostname[0] == '\0')
    hostname = DefaultHost;
  else if (is_absolute_path(hostname))

    /*
     * We should probably use canonicalize_path(), but then we have to
     * bring path.c into libpq, and it doesn't seem worth it.
     */
    if (strcmp(hostname, DEFAULT_PGSOCKET_DIR) == 0)
      hostname = DefaultHost;

  if (port == NULL || port[0] == '\0')
    /* Use YugaByte default port */
    port = DEF_YBPORT_STR;

  /* If password file cannot be opened, ignore it. */
  if (stat(pgpassfile, &stat_buf) != 0)
    return NULL;

#ifndef WIN32
  if (!S_ISREG(stat_buf.st_mode))
  {
    fprintf(stderr,
        libpq_gettext("WARNING: password file \"%s\" is not a plain file\n"),
        pgpassfile);
    return NULL;
  }

  /* If password file is insecure, alert the user and ignore it. */
  if (stat_buf.st_mode & (S_IRWXG | S_IRWXO))
  {
    fprintf(stderr,
        libpq_gettext("WARNING: password file \"%s\" has group or world access; permissions should be u=rw (0600) or less\n"),
        pgpassfile);
    return NULL;
  }
#else

  /*
   * On Win32, the directory is protected, so we don't have to check the
   * file.
   */
#endif

  fp = fopen(pgpassfile, "r");
  if (fp == NULL)
    return NULL;

  while (!feof(fp) && !ferror(fp))
  {
    char     *t = buf,
           *ret,
           *p1,
           *p2;
    int     len;

    if (fgets(buf, sizeof(buf), fp) == NULL)
      break;

    len = strlen(buf);

    /* Remove trailing newline */
    if (len > 0 && buf[len - 1] == '\n')
    {
      buf[--len] = '\0';
      /* Handle DOS-style line endings, too, even when not on Windows */
      if (len > 0 && buf[len - 1] == '\r')
        buf[--len] = '\0';
    }

    if (len == 0)
      continue;

    if ((t = pwdfMatchesString(t, hostname)) == NULL ||
      (t = pwdfMatchesString(t, port)) == NULL ||
      (t = pwdfMatchesString(t, dbname)) == NULL ||
      (t = pwdfMatchesString(t, username)) == NULL)
      continue;

    /* Found a match. */
    ret = strdup(t);
    fclose(fp);

    if (!ret)
    {
      /* Out of memory. XXX: an error message would be nice. */
      return NULL;
    }

    /* De-escape password. */
    for (p1 = p2 = ret; *p1 != ':' && *p1 != '\0'; ++p1, ++p2)
    {
      if (*p1 == '\\' && p1[1] != '\0')
        ++p1;
      *p2 = *p1;
    }
    *p2 = '\0';

    return ret;
  }

  fclose(fp);
  return NULL;

#undef LINELEN
}


/*
 *  If the connection failed due to bad password, we should mention
 *  if we got the password from the pgpassfile.
 */
static void
pgpassfileWarning(PGconn *conn)
{
  /* If it was 'invalid authorization', add pgpassfile mention */
  /* only works with >= 9.0 servers */
  if (conn->password_needed &&
    conn->connhost[conn->whichhost].password != NULL &&
    conn->result)
  {
    const char *sqlstate = PQresultErrorField(conn->result,
                          PG_DIAG_SQLSTATE);

    if (sqlstate && strcmp(sqlstate, ERRCODE_INVALID_PASSWORD) == 0)
      appendPQExpBuffer(&conn->errorMessage,
                libpq_gettext("password retrieved from file \"%s\"\n"),
                conn->pgpassfile);
  }
}


/*
 * Obtain user's home directory, return in given buffer
 *
 * On Unix, this actually returns the user's home directory.  On Windows
 * it returns the PostgreSQL-specific application data folder.
 *
 * This is essentially the same as get_home_path(), but we don't use that
 * because we don't want to pull path.c into libpq (it pollutes application
 * namespace).
 *
 * Returns true on success, false on failure to obtain the directory name.
 *
 * CAUTION: although in most situations failure is unexpected, there are users
 * who like to run applications in a home-directory-less environment.  On
 * failure, you almost certainly DO NOT want to report an error.  Just act as
 * though whatever file you were hoping to find in the home directory isn't
 * there (which it isn't).
 */
bool
pqGetHomeDirectory(char *buf, int bufsize)
{
#ifndef WIN32
  char    pwdbuf[BUFSIZ];
  struct passwd pwdstr;
  struct passwd *pwd = NULL;
  const char* home = NULL;

  (void) pqGetpwuid(geteuid(), &pwdstr, pwdbuf, sizeof(pwdbuf), &pwd);
  home = (pwd == NULL ? getenv("HOME") : pwd->pw_dir);
  if (home == NULL)
    return false;
  strlcpy(buf, home, bufsize);
  return true;
#else
  char    tmppath[MAX_PATH];

  ZeroMemory(tmppath, sizeof(tmppath));
  if (SHGetFolderPath(NULL, CSIDL_APPDATA, NULL, 0, tmppath) != S_OK)
    return false;
  snprintf(buf, bufsize, "%s/postgresql", tmppath);
  return true;
#endif
}

/*
 * To keep the API consistent, the locking stubs are always provided, even
 * if they are not required.
 */

static void
default_threadlock(int acquire)
{
#ifdef ENABLE_THREAD_SAFETY
#ifndef WIN32
  static pthread_mutex_t singlethread_lock = PTHREAD_MUTEX_INITIALIZER;
#else
  static pthread_mutex_t singlethread_lock = NULL;
  static long mutex_initlock = 0;

  if (singlethread_lock == NULL)
  {
    while (InterlockedExchange(&mutex_initlock, 1) == 1)
       /* loop, another thread own the lock */ ;
    if (singlethread_lock == NULL)
    {
      if (pthread_mutex_init(&singlethread_lock, NULL))
        PGTHREAD_ERROR("failed to initialize mutex");
    }
    InterlockedExchange(&mutex_initlock, 0);
  }
#endif
  if (acquire)
  {
    if (pthread_mutex_lock(&singlethread_lock))
      PGTHREAD_ERROR("failed to lock mutex");
  }
  else
  {
    if (pthread_mutex_unlock(&singlethread_lock))
      PGTHREAD_ERROR("failed to unlock mutex");
  }
#endif
}

pgthreadlock_t
PQregisterThreadLock(pgthreadlock_t newhandler)
{
  pgthreadlock_t prev = pg_g_threadlock;

  if (newhandler)
    pg_g_threadlock = newhandler;
  else
    pg_g_threadlock = default_threadlock;

  return prev;
}

YugabyteDB (2.13.0.0-b42, bfc6a6643e7399ac8a0e81d06a3ee6d6571b33ab)

Coverage Report

Created: 2022-03-09 17:30