fe-connect.c

PostgreSQL 8.1.4的源码 适用于Linux下的开源数据库系统

 * 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;

	initPQExpBuffer(&errorBuf);
	connOptions = conninfo_parse("", &errorBuf);
	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;

	/*
	 * Parse an empty conninfo string in order to set up the same defaults
	 * that PQconnectdb() would use.
	 */
	if (!connectOptions1(conn, ""))
		return conn;

	/*
	 * Absorb specified options into conn structure, overriding defaults
	 */
	if (pghost && pghost[0] != '\0')
	{
		if (conn->pghost)
			free(conn->pghost);
		conn->pghost = strdup(pghost);
	}

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

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

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

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

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

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

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

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

	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];

		printfPQExpBuffer(&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);
		printfPQExpBuffer(&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 */
	{
		printfPQExpBuffer(&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)),
						  conn->pghostaddr
						  ? conn->pghostaddr
						  : (conn->pghost
							 ? conn->pghost
							 : "???"),
						  conn->pgport);
	}
}


/* ----------
 * connectDBStart -
 *		Begin the process of making a connection to the backend.
 *
 * Returns 1 if successful, 0 if not.
 * ----------
 */
static int
connectDBStart(PGconn *conn)
{
	int			portnum;
	char		portstr[128];
	struct addrinfo *addrs = NULL;
	struct addrinfo hint;
	const char *node;
	int			ret;

	if (!conn)
		return 0;

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

	/*
	 * Determine the parameters to pass to pg_getaddrinfo_all.
	 */

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

	/* Set up port number as a string */
	if (conn->pgport != NULL && conn->pgport[0] != '\0')
		portnum = atoi(conn->pgport);
	else
		portnum = DEF_PGPORT;
	snprintf(portstr, sizeof(portstr), "%d", portnum);

	if (conn->pghostaddr != NULL && conn->pghostaddr[0] != '\0')
	{
		/* Using pghostaddr avoids a hostname lookup */
		node = conn->pghostaddr;
		hint.ai_family = AF_UNSPEC;
		hint.ai_flags = AI_NUMERICHOST;
	}
	else if (conn->pghost != NULL && conn->pghost[0] != '\0')
	{
		/* Using pghost, so we have to look-up the hostname */
		node = conn->pghost;
		hint.ai_family = AF_UNSPEC;
	}
	else
	{
#ifdef HAVE_UNIX_SOCKETS
		/* pghostaddr and pghost are NULL, so use Unix domain socket */
		node = NULL;
		hint.ai_family = AF_UNIX;
		UNIXSOCK_PATH(portstr, portnum, conn->pgunixsocket);
#else
		/* Without Unix sockets, default to localhost instead */
		node = "localhost";
		hint.ai_family = AF_UNSPEC;
#endif   /* HAVE_UNIX_SOCKETS */
	}

	/* Use pg_getaddrinfo_all() to resolve the address */
	ret = pg_getaddrinfo_all(node, portstr, &hint, &addrs);
	if (ret || !addrs)
	{
		if (node)
			printfPQExpBuffer(&conn->errorMessage,
							  libpq_gettext("could not translate host name \"%s\" to address: %s\n"),
							  node, gai_strerror(ret));
		else
			printfPQExpBuffer(&conn->errorMessage,
							  libpq_gettext("could not translate Unix-domain socket path \"%s\" to address: %s\n"),
							  portstr, gai_strerror(ret));
		if (addrs)
			pg_freeaddrinfo_all(hint.ai_family, addrs);
		goto connect_errReturn;
	}

#ifdef USE_SSL
	/* setup values based on SSL mode */
	if (conn->sslmode[0] == 'd')	/* "disable" */
		conn->allow_ssl_try = false;
	else if (conn->sslmode[0] == 'a')	/* "allow" */
		conn->wait_ssl_try = true;
#endif

	/*
	 * Set up to try to connect, with protocol 3.0 as the first attempt.
	 */
	conn->addrlist = addrs;
	conn->addr_cur = addrs;
	conn->addrlist_family = hint.ai_family;
	conn->pversion = PG_PROTOCOL(3, 0);
	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 (conn->sock >= 0)
	{
		pqsecure_close(conn);
		closesocket(conn->sock);
		conn->sock = -1;
	}
	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);

	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)
	{
		int			timeout = atoi(conn->connect_timeout);

		if (timeout > 0)
		{
			/*
			 * Rounding could cause connection to fail; need at least 2 secs
			 */
			if (timeout < 2)
				timeout = 2;
			/* calculate the finish time based on start + timeout */
			finish_time = time(NULL) + timeout;
		}
	}

	for (;;)
	{
		/*
		 * 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:
				return 1;		/* success! */

			case PGRES_POLLING_READING:
				if (pqWaitTimed(1, 0, conn, finish_time))
				{
					conn->status = CONNECTION_BAD;
					return 0;
				}
				break;

			case PGRES_POLLING_WRITING:
				if (pqWaitTimed(0, 1, conn, finish_time))
				{
					conn->status = CONNECTION_BAD;
					return 0;
				}
				break;

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

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

/* ----------------
 *		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)
{
	PGresult   *res;
	char		sebuf[256];

	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:
			break;

		default:
			printfPQExpBuffer(&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. */
	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. We fail when we run out of addresses
				 * (reporting the error returned for the *last* alternative,
				 * which may not be what users expect :-().
				 */
				while (conn->addr_cur != NULL)
				{
					struct addrinfo *addr_cur = conn->addr_cur;

					/* 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;

					/* Open a socket */
					conn->sock = socket(addr_cur->ai_family, SOCK_STREAM, 0);
					if (conn->sock < 0)
					{
						/*
						 * ignore socket() failure if we have more addresses
						 * to try
						 */
						if (addr_cur->ai_next != NULL)
						{
							conn->addr_cur = addr_cur->ai_next;
							continue;
						}
						printfPQExpBuffer(&conn->errorMessage,
							  libpq_gettext("could not create socket: %s\n"),
							SOCK_STRERROR(SOCK_ERRNO, sebuf, sizeof(sebuf)));
						break;
					}

					/*
					 * Select socket options: no delay of outgoing data for
					 * TCP sockets, nonblock mode, close-on-exec. Fail if any