fe-cancel.c File Reference

#include "postgres_fe.h"
#include <unistd.h>
#include "libpq-fe.h"
#include "libpq-int.h"
#include "port/pg_bswap.h"

Include dependency graph for fe-cancel.c:

Go to the source code of this file.

Data Structures
struct	pg_cancel_conn
struct	pg_cancel

Functions
PGcancelConn *	PQcancelCreate (PGconn *conn)
int	PQcancelBlocking (PGcancelConn *cancelConn)
int	PQcancelStart (PGcancelConn *cancelConn)
PostgresPollingStatusType	PQcancelPoll (PGcancelConn *cancelConn)
ConnStatusType	PQcancelStatus (const PGcancelConn *cancelConn)
int	PQcancelSocket (const PGcancelConn *cancelConn)
char *	PQcancelErrorMessage (const PGcancelConn *cancelConn)
void	PQcancelReset (PGcancelConn *cancelConn)
void	PQcancelFinish (PGcancelConn *cancelConn)
PGcancel *	PQgetCancel (PGconn *conn)
void	PQfreeCancel (PGcancel *cancel)
static bool	optional_setsockopt (int fd, int protoid, int optid, int value)
int	PQcancel (PGcancel *cancel, char *errbuf, int errbufsize)
int	PQrequestCancel (PGconn *conn)

Function Documentation

optional_setsockopt()

static bool optional_setsockopt ( int  fd, int  protoid, int  optid, int  value  )

static

Definition at line 431 of file fe-cancel.c.

{
    if (value < 0)
        return true;
    if (setsockopt(fd, protoid, optid, (char *) &value, sizeof(value)) < 0)
        return false;
    return true;
}

References fd(), and value.

Referenced by PQcancel().

PQcancel()

int PQcancel	(	PGcancel *	cancel,
		char *	errbuf,
		int	errbufsize
	)

Definition at line 463 of file fe-cancel.c.

{
    int         save_errno = SOCK_ERRNO;
    pgsocket    tmpsock = PGINVALID_SOCKET;
    int         maxlen;
    struct
    {
        uint32      packetlen;
        CancelRequestPacket cp;
    }           crp;
 
    if (!cancel)
    {
        strlcpy(errbuf, "PQcancel() -- no cancel object supplied", errbufsize);
        /* strlcpy probably doesn't change errno, but be paranoid */
        SOCK_ERRNO_SET(save_errno);
        return false;
    }
 
    /*
     * We need to open a temporary connection to the postmaster. Do this with
     * only kernel calls.
     */
    if ((tmpsock = socket(cancel->raddr.addr.ss_family, SOCK_STREAM, 0)) == PGINVALID_SOCKET)
    {
        strlcpy(errbuf, "PQcancel() -- socket() failed: ", errbufsize);
        goto cancel_errReturn;
    }
 
    /*
     * Since this connection will only be used to send a single packet of
     * data, we don't need NODELAY.  We also don't set the socket to
     * nonblocking mode, because the API definition of PQcancel requires the
     * cancel to be sent in a blocking way.
     *
     * We do set socket options related to keepalives and other TCP timeouts.
     * This ensures that this function does not block indefinitely when
     * reasonable keepalive and timeout settings have been provided.
     */
    if (cancel->raddr.addr.ss_family != AF_UNIX &&
        cancel->keepalives != 0)
    {
#ifndef WIN32
        if (!optional_setsockopt(tmpsock, SOL_SOCKET, SO_KEEPALIVE, 1))
        {
            strlcpy(errbuf, "PQcancel() -- setsockopt(SO_KEEPALIVE) failed: ", errbufsize);
            goto cancel_errReturn;
        }
 
#ifdef PG_TCP_KEEPALIVE_IDLE
        if (!optional_setsockopt(tmpsock, IPPROTO_TCP, PG_TCP_KEEPALIVE_IDLE,
                                 cancel->keepalives_idle))
        {
            strlcpy(errbuf, "PQcancel() -- setsockopt(" PG_TCP_KEEPALIVE_IDLE_STR ") failed: ", errbufsize);
            goto cancel_errReturn;
        }
#endif
 
#ifdef TCP_KEEPINTVL
        if (!optional_setsockopt(tmpsock, IPPROTO_TCP, TCP_KEEPINTVL,
                                 cancel->keepalives_interval))
        {
            strlcpy(errbuf, "PQcancel() -- setsockopt(TCP_KEEPINTVL) failed: ", errbufsize);
            goto cancel_errReturn;
        }
#endif
 
#ifdef TCP_KEEPCNT
        if (!optional_setsockopt(tmpsock, IPPROTO_TCP, TCP_KEEPCNT,
                                 cancel->keepalives_count))
        {
            strlcpy(errbuf, "PQcancel() -- setsockopt(TCP_KEEPCNT) failed: ", errbufsize);
            goto cancel_errReturn;
        }
#endif
 
#else                           /* WIN32 */
 
#ifdef SIO_KEEPALIVE_VALS
        if (!pqSetKeepalivesWin32(tmpsock,
                                  cancel->keepalives_idle,
                                  cancel->keepalives_interval))
        {
            strlcpy(errbuf, "PQcancel() -- WSAIoctl(SIO_KEEPALIVE_VALS) failed: ", errbufsize);
            goto cancel_errReturn;
        }
#endif                          /* SIO_KEEPALIVE_VALS */
#endif                          /* WIN32 */
 
        /* TCP_USER_TIMEOUT works the same way on Unix and Windows */
#ifdef TCP_USER_TIMEOUT
        if (!optional_setsockopt(tmpsock, IPPROTO_TCP, TCP_USER_TIMEOUT,
                                 cancel->pgtcp_user_timeout))
        {
            strlcpy(errbuf, "PQcancel() -- setsockopt(TCP_USER_TIMEOUT) failed: ", errbufsize);
            goto cancel_errReturn;
        }
#endif
    }
 
retry3:
    if (connect(tmpsock, (struct sockaddr *) &cancel->raddr.addr,
                cancel->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;
    }
 
    /* 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(cancel->be_pid);
    crp.cp.cancelAuthCode = pg_hton32(cancel->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)
    {
        /*
         * We can't invoke strerror here, since it's not signal-safe.  Settle
         * for printing the decimal value of errno.  Even that has to be done
         * the hard way.
         */
        int         val = SOCK_ERRNO;
        char        buf[32];
        char       *bufp;
 
        bufp = buf + sizeof(buf) - 1;
        *bufp = '\0';
        do
        {
            *(--bufp) = (val % 10) + '0';
            val /= 10;
        } while (val > 0);
        bufp -= 6;
        memcpy(bufp, "error ", 6);
        strncat(errbuf, bufp, maxlen);
        strcat(errbuf, "\n");
    }
    if (tmpsock != PGINVALID_SOCKET)
        closesocket(tmpsock);
    SOCK_ERRNO_SET(save_errno);
    return false;
}

References SockAddr::addr, pg_cancel::be_key, pg_cancel::be_pid, buf, CANCEL_REQUEST_CODE, closesocket, connect, EINTR, pg_cancel::keepalives, pg_cancel::keepalives_count, pg_cancel::keepalives_idle, pg_cancel::keepalives_interval, optional_setsockopt(), pg_hton32, PGINVALID_SOCKET, pg_cancel::pgtcp_user_timeout, pg_cancel::raddr, recv, SockAddr::salen, send, SOCK_ERRNO, SOCK_ERRNO_SET, socket, strlcpy(), and val.

Referenced by DisconnectDatabase(), handle_sigint(), PQrequestCancel(), ShutdownWorkersHard(), sigTermHandler(), and test_cancel().

PQcancelBlocking()

int PQcancelBlocking

(

PGcancelConn *

cancelConn

)

Definition at line 171 of file fe-cancel.c.

{
    if (!PQcancelStart(cancelConn))
        return 0;
    return pqConnectDBComplete(&cancelConn->conn);
}

References cancelConn, PQcancelStart(), and pqConnectDBComplete().

Referenced by disconnectDatabase(), test_cancel(), and try_complete_step().

PQcancelCreate()

PGcancelConn * PQcancelCreate

(

PGconn *

conn

)

Definition at line 65 of file fe-cancel.c.

{
    PGconn     *cancelConn = pqMakeEmptyPGconn();
    pg_conn_host originalHost;
 
    if (cancelConn == NULL)
        return NULL;
 
    /* Check we have an open connection */
    if (!conn)
    {
        libpq_append_conn_error(cancelConn, "connection pointer is NULL");
        return (PGcancelConn *) cancelConn;
    }
 
    if (conn->sock == PGINVALID_SOCKET)
    {
        libpq_append_conn_error(cancelConn, "connection not open");
        return (PGcancelConn *) cancelConn;
    }
 
    /*
     * Indicate that this connection is used to send a cancellation
     */
    cancelConn->cancelRequest = true;
 
    if (!pqCopyPGconn(conn, cancelConn))
        return (PGcancelConn *) cancelConn;
 
    /*
     * Compute derived options
     */
    if (!pqConnectOptions2(cancelConn))
        return (PGcancelConn *) cancelConn;
 
    /*
     * Copy cancellation token data from the original connection
     */
    cancelConn->be_pid = conn->be_pid;
    cancelConn->be_key = conn->be_key;
 
    /*
     * Cancel requests should not iterate over all possible hosts. The request
     * needs to be sent to the exact host and address that the original
     * connection used. So we manually create the host and address arrays with
     * a single element after freeing the host array that we generated from
     * the connection options.
     */
    pqReleaseConnHosts(cancelConn);
    cancelConn->nconnhost = 1;
    cancelConn->naddr = 1;
 
    cancelConn->connhost = calloc(cancelConn->nconnhost, sizeof(pg_conn_host));
    if (!cancelConn->connhost)
        goto oom_error;
 
    originalHost = conn->connhost[conn->whichhost];
    if (originalHost.host)
    {
        cancelConn->connhost[0].host = strdup(originalHost.host);
        if (!cancelConn->connhost[0].host)
            goto oom_error;
    }
    if (originalHost.hostaddr)
    {
        cancelConn->connhost[0].hostaddr = strdup(originalHost.hostaddr);
        if (!cancelConn->connhost[0].hostaddr)
            goto oom_error;
    }
    if (originalHost.port)
    {
        cancelConn->connhost[0].port = strdup(originalHost.port);
        if (!cancelConn->connhost[0].port)
            goto oom_error;
    }
    if (originalHost.password)
    {
        cancelConn->connhost[0].password = strdup(originalHost.password);
        if (!cancelConn->connhost[0].password)
            goto oom_error;
    }
 
    cancelConn->addr = calloc(cancelConn->naddr, sizeof(AddrInfo));
    if (!cancelConn->addr)
        goto oom_error;
 
    cancelConn->addr[0].addr = conn->raddr;
    cancelConn->addr[0].family = conn->raddr.addr.ss_family;
 
    cancelConn->status = CONNECTION_ALLOCATED;
    return (PGcancelConn *) cancelConn;
 
oom_error:
    cancelConn->status = CONNECTION_BAD;
    libpq_append_conn_error(cancelConn, "out of memory");
    return (PGcancelConn *) cancelConn;
}

References SockAddr::addr, pg_cancel::be_key, pg_conn::be_key, pg_cancel::be_pid, pg_conn::be_pid, calloc, cancelConn, conn, CONNECTION_ALLOCATED, CONNECTION_BAD, pg_conn::connhost, pg_conn_host::host, pg_conn_host::hostaddr, libpq_append_conn_error(), pg_conn_host::password, PGINVALID_SOCKET, pg_conn_host::port, pqConnectOptions2(), pqCopyPGconn(), pqMakeEmptyPGconn(), pqReleaseConnHosts(), pg_conn::raddr, pg_conn::sock, and pg_conn::whichhost.

Referenced by disconnectDatabase(), libpqsrv_cancel(), test_cancel(), and try_complete_step().

PQcancelErrorMessage()

char * PQcancelErrorMessage

(

const PGcancelConn *

cancelConn

)

Definition at line 306 of file fe-cancel.c.

{
    return PQerrorMessage(&cancelConn->conn);
}

References cancelConn, and PQerrorMessage().

Referenced by libpqsrv_cancel(), test_cancel(), and try_complete_step().

PQcancelFinish()

void PQcancelFinish

(

PGcancelConn *

cancelConn

)

Definition at line 334 of file fe-cancel.c.

{
    PQfinish(&cancelConn->conn);
}

References cancelConn, and PQfinish().

Referenced by disconnectDatabase(), libpqsrv_cancel(), test_cancel(), and try_complete_step().

PQcancelPoll()

PostgresPollingStatusType PQcancelPoll

(

PGcancelConn *

cancelConn

)

Definition at line 207 of file fe-cancel.c.

{
    PGconn     *conn = &cancelConn->conn;
    int         n;
 
    /*
     * We leave most of the connection establishment to PQconnectPoll, since
     * it's very similar to normal connection establishment. But once we get
     * to the CONNECTION_AWAITING_RESPONSE we need to start doing our own
     * thing.
     */
    if (conn->status != CONNECTION_AWAITING_RESPONSE)
    {
        return PQconnectPoll(conn);
    }
 
    /*
     * At this point we are waiting on the server to close the connection,
     * which is its way of communicating that the cancel has been handled.
     */
 
    n = pqReadData(conn);
 
    if (n == 0)
        return PGRES_POLLING_READING;
 
#ifndef WIN32
 
    /*
     * If we receive an error report it, but only if errno is non-zero.
     * Otherwise we assume it's an EOF, which is what we expect from the
     * server.
     *
     * We skip this for Windows, because Windows is a bit special in its EOF
     * behaviour for TCP. Sometimes it will error with an ECONNRESET when
     * there is a clean connection closure. See these threads for details:
     * https://www.postgresql.org/message-id/flat/90b34057-4176-7bb0-0dbb-9822a5f6425b%40greiz-reinsdorf.de
     *
     * https://www.postgresql.org/message-id/flat/CA%2BhUKG%2BOeoETZQ%3DQw5Ub5h3tmwQhBmDA%3DnuNO3KG%3DzWfUypFAw%40mail.gmail.com
     *
     * PQcancel ignores such errors and reports success for the cancellation
     * anyway, so even if this is not always correct we do the same here.
     */
    if (n < 0 && errno != 0)
    {
        conn->status = CONNECTION_BAD;
        return PGRES_POLLING_FAILED;
    }
#endif
 
    /*
     * We don't expect any data, only connection closure. So if we strangely
     * do receive some data we consider that an error.
     */
    if (n > 0)
    {
        libpq_append_conn_error(conn, "unexpected response from server");
        conn->status = CONNECTION_BAD;
        return PGRES_POLLING_FAILED;
    }
 
    /*
     * Getting here means that we received an EOF, which is what we were
     * expecting -- the cancel request has completed.
     */
    cancelConn->conn.status = CONNECTION_OK;
    resetPQExpBuffer(&conn->errorMessage);
    return PGRES_POLLING_OK;
}

References cancelConn, conn, CONNECTION_AWAITING_RESPONSE, CONNECTION_BAD, CONNECTION_OK, pg_conn::errorMessage, libpq_append_conn_error(), PGRES_POLLING_FAILED, PGRES_POLLING_OK, PGRES_POLLING_READING, PQconnectPoll(), pqReadData(), resetPQExpBuffer(), and pg_conn::status.

Referenced by libpqsrv_cancel(), pqConnectDBComplete(), and test_cancel().

PQcancelReset()

void PQcancelReset

(

PGcancelConn *

cancelConn

)

Definition at line 318 of file fe-cancel.c.

{
    pqClosePGconn(&cancelConn->conn);
    cancelConn->conn.status = CONNECTION_ALLOCATED;
    cancelConn->conn.whichhost = 0;
    cancelConn->conn.whichaddr = 0;
    cancelConn->conn.try_next_host = false;
    cancelConn->conn.try_next_addr = false;
}

References cancelConn, CONNECTION_ALLOCATED, and pqClosePGconn().

Referenced by test_cancel().

PQcancelSocket()

int PQcancelSocket

(

const PGcancelConn *

cancelConn

)

Definition at line 294 of file fe-cancel.c.

{
    return PQsocket(&cancelConn->conn);
}

References cancelConn, and PQsocket().

Referenced by libpqsrv_cancel(), and test_cancel().

PQcancelStart()

int PQcancelStart

(

PGcancelConn *

cancelConn

)

Definition at line 185 of file fe-cancel.c.

{
    if (!cancelConn || cancelConn->conn.status == CONNECTION_BAD)
        return 0;
 
    if (cancelConn->conn.status != CONNECTION_ALLOCATED)
    {
        libpq_append_conn_error(&cancelConn->conn,
                                "cancel request is already being sent on this connection");
        cancelConn->conn.status = CONNECTION_BAD;
        return 0;
    }
 
    return pqConnectDBStart(&cancelConn->conn);
}

References cancelConn, CONNECTION_ALLOCATED, CONNECTION_BAD, libpq_append_conn_error(), and pqConnectDBStart().

Referenced by libpqsrv_cancel(), PQcancelBlocking(), and test_cancel().

PQcancelStatus()

ConnStatusType PQcancelStatus

(

const PGcancelConn *

cancelConn

)

Definition at line 283 of file fe-cancel.c.

{
    return PQstatus(&cancelConn->conn);
}

References cancelConn, and PQstatus().

Referenced by test_cancel().

PQfreeCancel()

void PQfreeCancel

(

PGcancel *

cancel

)

Definition at line 417 of file fe-cancel.c.

{
    free(cancel);
}

References free.

Referenced by PQrequestCancel(), ResetCancelConn(), set_archive_cancel_info(), SetCancelConn(), and test_cancel().

PQgetCancel()

PGcancel * PQgetCancel

(

PGconn *

conn

)

Definition at line 349 of file fe-cancel.c.

{
    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;
    /* We use -1 to indicate an unset connection option */
    cancel->pgtcp_user_timeout = -1;
    cancel->keepalives = -1;
    cancel->keepalives_idle = -1;
    cancel->keepalives_interval = -1;
    cancel->keepalives_count = -1;
    if (conn->pgtcp_user_timeout != NULL)
    {
        if (!pqParseIntParam(conn->pgtcp_user_timeout,
                             &cancel->pgtcp_user_timeout,
                             conn, "tcp_user_timeout"))
            goto fail;
    }
    if (conn->keepalives != NULL)
    {
        if (!pqParseIntParam(conn->keepalives,
                             &cancel->keepalives,
                             conn, "keepalives"))
            goto fail;
    }
    if (conn->keepalives_idle != NULL)
    {
        if (!pqParseIntParam(conn->keepalives_idle,
                             &cancel->keepalives_idle,
                             conn, "keepalives_idle"))
            goto fail;
    }
    if (conn->keepalives_interval != NULL)
    {
        if (!pqParseIntParam(conn->keepalives_interval,
                             &cancel->keepalives_interval,
                             conn, "keepalives_interval"))
            goto fail;
    }
    if (conn->keepalives_count != NULL)
    {
        if (!pqParseIntParam(conn->keepalives_count,
                             &cancel->keepalives_count,
                             conn, "keepalives_count"))
            goto fail;
    }
 
    return cancel;
 
fail:
    free(cancel);
    return NULL;
}

References pg_cancel::be_key, pg_conn::be_key, pg_cancel::be_pid, pg_conn::be_pid, conn, free, pg_cancel::keepalives, pg_conn::keepalives, pg_cancel::keepalives_count, pg_conn::keepalives_count, pg_cancel::keepalives_idle, pg_conn::keepalives_idle, pg_cancel::keepalives_interval, pg_conn::keepalives_interval, malloc, PGINVALID_SOCKET, pg_cancel::pgtcp_user_timeout, pg_conn::pgtcp_user_timeout, pqParseIntParam(), pg_cancel::raddr, pg_conn::raddr, and pg_conn::sock.

Referenced by PQrequestCancel(), set_archive_cancel_info(), SetCancelConn(), and test_cancel().

PQrequestCancel()

int PQrequestCancel

(

PGconn *

conn

)

Definition at line 661 of file fe-cancel.c.

{
    int         r;
    PGcancel   *cancel;
 
    /* 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);
        conn->errorReported = 0;
 
        return false;
    }
 
    cancel = PQgetCancel(conn);
    if (cancel)
    {
        r = PQcancel(cancel, conn->errorMessage.data,
                     conn->errorMessage.maxlen);
        PQfreeCancel(cancel);
    }
    else
    {
        strlcpy(conn->errorMessage.data, "out of memory",
                conn->errorMessage.maxlen);
        r = false;
    }
 
    if (!r)
    {
        conn->errorMessage.len = strlen(conn->errorMessage.data);
        conn->errorReported = 0;
    }
 
    return r;
}

References conn, PQExpBufferData::data, pg_conn::errorMessage, pg_conn::errorReported, PQExpBufferData::len, PQExpBufferData::maxlen, PGINVALID_SOCKET, PQcancel(), PQfreeCancel(), PQgetCancel(), pg_conn::sock, and strlcpy().

Referenced by test_cancel().