fe-connect.c

PostgreSQL 8.1.4的源码 适用于Linux下的开源数据库系统

						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
						&& conn->allow_ssl_try	/* redundant? */
						&& !conn->wait_ssl_try) /* redundant? */
					{
						/* only retry once */
						conn->allow_ssl_try = false;
						/* Must drop the old connection */
						pqsecure_close(conn);
						closesocket(conn->sock);
						conn->sock = -1;
						conn->status = CONNECTION_NEEDED;
						goto keep_going;
					}
#endif

					goto error_return;
				}

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

				/* Get the password salt if there is one. */
				if (areq == AUTH_REQ_MD5)
				{
					if (pqGetnchar(conn->md5Salt,
								   sizeof(conn->md5Salt), conn))
					{
						/* We'll come back when there are more data */
						return PGRES_POLLING_READING;
					}
				}
				if (areq == AUTH_REQ_CRYPT)
				{
					if (pqGetnchar(conn->cryptSalt,
								   sizeof(conn->cryptSalt), conn))
					{
						/* We'll come back when there are more data */
						return PGRES_POLLING_READING;
					}
				}

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

				/* Respond to the request if necessary. */

				/*
				 * Note that conn->pghost must be non-NULL if we are going to
				 * avoid the Kerberos code doing a hostname look-up.
				 */

				/*
				 * XXX fe-auth.c has not been fixed to support PQExpBuffers,
				 * so:
				 */
				if (pg_fe_sendauth(areq, conn, conn->pghost, conn->pgpass,
								   conn->errorMessage.data) != STATUS_OK)
				{
					conn->errorMessage.len = strlen(conn->errorMessage.data);
					goto error_return;
				}
				conn->errorMessage.len = strlen(conn->errorMessage.data);

				/*
				 * 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 PQsetResult 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)
						printfPQExpBuffer(&conn->errorMessage,
										  libpq_gettext("unexpected message from server during startup\n"));

					/*
					 * 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;
				}

				/* We can release the address list now. */
				pg_freeaddrinfo_all(conn->addrlist_family, conn->addrlist);
				conn->addrlist = NULL;
				conn->addr_cur = NULL;

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

				/* Otherwise, 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;
			}

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

		default:
			printfPQExpBuffer(&conn->errorMessage,
							  libpq_gettext(
											"invalid connection state %c, "
								 "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;
}


/*
 * 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. Even though this is done in
	 * libpqdll.c, that is only for MSVC and BCC builds and doesn't work for
	 * static builds at all, so we have to do it in the main code too.
	 */
	WSADATA		wsaData;

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

	conn = (PGconn *) malloc(sizeof(PGconn));
	if (conn == NULL)
		return conn;

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

	conn->noticeHooks.noticeRec = defaultNoticeReceiver;
	conn->noticeHooks.noticeProc = defaultNoticeProcessor;
	conn->status = CONNECTION_BAD;
	conn->asyncStatus = PGASYNC_IDLE;
	conn->xactStatus = PQTRANS_IDLE;
	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->sock = -1;
#ifdef USE_SSL
	conn->allow_ssl_try = true;
	conn->wait_ssl_try = false;
#endif

	/*
	 * 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->nonblocking = FALSE;
	initPQExpBuffer(&conn->errorMessage);
	initPQExpBuffer(&conn->workBuffer);

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

	return conn;
}

/*
 * freePGconn
 *	 - free the PGconn data structure
 *
 * When changing/adding to this function, see also closePGconn!
 */
static void
freePGconn(PGconn *conn)
{
	PGnotify   *notify;
	pgParameterStatus *pstatus;

#ifdef WIN32
	WSACleanup();
#endif

	if (!conn)
		return;

	pqClearAsyncResult(conn);	/* deallocate result and curTuple */
	if (conn->sock >= 0)
	{
		pqsecure_close(conn);
		closesocket(conn->sock);
	}
	if (conn->pghost)
		free(conn->pghost);
	if (conn->pghostaddr)
		free(conn->pghostaddr);
	if (conn->pgport)
		free(conn->pgport);
	if (conn->pgunixsocket)
		free(conn->pgunixsocket);
	if (conn->pgtty)
		free(conn->pgtty);
	if (conn->connect_timeout)
		free(conn->connect_timeout);
	if (conn->pgoptions)
		free(conn->pgoptions);
	if (conn->dbName)
		free(conn->dbName);
	if (conn->pguser)
		free(conn->pguser);
	if (conn->pgpass)
		free(conn->pgpass);
	if (conn->sslmode)
		free(conn->sslmode);
#ifdef KRB5
	if (conn->krbsrvname)
		free(conn->krbsrvname);
#endif
	/* Note that conn->Pfdebug is not ours to close or free */
	pg_freeaddrinfo_all(conn->addrlist_family, conn->addrlist);
	notify = conn->notifyHead;
	while (notify != NULL)
	{
		PGnotify   *prev = notify;

		notify = notify->next;
		free(prev);
	}
	pstatus = conn->pstatus;
	while (pstatus != NULL)
	{
		pgParameterStatus *prev = pstatus;

		pstatus = pstatus->next;
		free(prev);
	}
	if (conn->lobjfuncs)
		free(conn->lobjfuncs);
	if (conn->inBuffer)
		free(conn->inBuffer);
	if (conn->outBuffer)
		free(conn->outBuffer);
	termPQExpBuffer(&conn->errorMessage);
	termPQExpBuffer(&conn->workBuffer);
	free(conn);
}

/*
 * closePGconn
 *	 - properly close a connection to the backend
 *
 * Release all transient state, but NOT the connection parameters.
 */
static void
closePGconn(PGconn *conn)
{
	PGnotify   *notify;
	pgParameterStatus *pstatus;

	/*
	 * Note that the protocol doesn't allow us to send Terminate messages
	 * during the startup phase.
	 */
	if (conn->sock >= 0 && conn->status == CONNECTION_OK)
	{
		/*
		 * Try to send "close connection" message to backend. Ignore any
		 * error.
		 */
		pqPutMsgStart('X', false, conn);
		pqPutMsgEnd(conn);
		pqFlush(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.
	 */
	if (conn->sock >= 0)
	{
		pqsecure_close(conn);
		closesocket(conn->sock);
	}
	conn->sock = -1;
	conn->status = CONNECTION_BAD;		/* Well, not really _bad_ - just
										 * absent */
	conn->asyncStatus = PGASYNC_IDLE;
	pqClearAsyncResult(conn);	/* deallocate result and curTuple */
	pg_freeaddrinfo_all(conn->addrlist_family, conn->addrlist);
	conn->addrlist = NULL;
	conn->addr_cur = NULL;
	notify = conn->notifyHead;
	while (notify != NULL)
	{
		PGnotify   *prev = notify;

		notify = notify->next;
		free(prev);
	}
	conn->notifyHead = NULL;
	pstatus = conn->pstatus;
	while (pstatus != NULL)
	{
		pgParameterStatus *prev = pstatus;

		pstatus = pstatus->next;
		free(prev);
	}
	conn->pstatus = NULL;
	if (conn->lobjfuncs)
		free(conn->lobjfuncs);
	conn->lobjfuncs = NULL;
	conn->inStart = conn->inCursor = conn->inEnd = 0;
	conn->outCount = 0;
}

/*
 * 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))
			(void) connectDBComplete(conn);
	}
}


/*
 * 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)
		return PQconnectPoll(conn);

	return PGRES_POLLING_FAILED;
}

/*
 * PQcancelGet: get a PGcancel structure corresponding to a connection.