@ -1,7 +1,7 @@
/*-------------------------------------------------------------------------
*
* fe - cancel . c
* functions related to setting up a connection to the backend
* functions related to query cancellation
*
* Portions Copyright ( c ) 1996 - 2025 , PostgreSQL Global Development Group
* Portions Copyright ( c ) 1994 , Regents of the University of California
@ -41,7 +41,6 @@ struct pg_cancel
{
SockAddr raddr ; /* Remote address */
int be_pid ; /* PID of to-be-canceled backend */
int be_key ; /* cancel key of to-be-canceled backend */
int pgtcp_user_timeout ; /* tcp user timeout */
int keepalives ; /* use TCP keepalives? */
int keepalives_idle ; /* time between TCP keepalives */
@ -49,6 +48,10 @@ struct pg_cancel
* retransmits */
int keepalives_count ; /* maximum number of TCP keepalive
* retransmits */
/* Pre-constructed cancel request packet starts here */
int32 cancel_pkt_len ; /* in network-byte-order */
char cancel_req [ FLEXIBLE_ARRAY_MEMBER ] ; /* CancelRequestPacket */
} ;
@ -83,6 +86,13 @@ PQcancelCreate(PGconn *conn)
return ( PGcancelConn * ) cancelConn ;
}
/* Check that we have received a cancellation key */
if ( conn - > be_cancel_key_len = = 0 )
{
libpq_append_conn_error ( cancelConn , " no cancellation key received " ) ;
return ( PGcancelConn * ) cancelConn ;
}
/*
* Indicate that this connection is used to send a cancellation
*/
@ -101,7 +111,15 @@ PQcancelCreate(PGconn *conn)
* Copy cancellation token data from the original connection
*/
cancelConn - > be_pid = conn - > be_pid ;
cancelConn - > be_key = conn - > be_key ;
if ( conn - > be_cancel_key ! = NULL )
{
cancelConn - > be_cancel_key = malloc ( conn - > be_cancel_key_len ) ;
if ( ! conn - > be_cancel_key )
goto oom_error ;
memcpy ( cancelConn - > be_cancel_key , conn - > be_cancel_key , conn - > be_cancel_key_len ) ;
}
cancelConn - > be_cancel_key_len = conn - > be_cancel_key_len ;
cancelConn - > pversion = conn - > pversion ;
/*
* Cancel requests should not iterate over all possible hosts . The request
@ -349,6 +367,8 @@ PGcancel *
PQgetCancel ( PGconn * conn )
{
PGcancel * cancel ;
int cancel_req_len ;
CancelRequestPacket * req ;
if ( ! conn )
return NULL ;
@ -356,13 +376,17 @@ PQgetCancel(PGconn *conn)
if ( conn - > sock = = PGINVALID_SOCKET )
return NULL ;
cancel = malloc ( sizeof ( PGcancel ) ) ;
/* Check that we have received a cancellation key */
if ( conn - > be_cancel_key_len = = 0 )
return NULL ;
cancel_req_len = offsetof ( CancelRequestPacket , cancelAuthCode ) + conn - > be_cancel_key_len ;
cancel = malloc ( offsetof ( PGcancel , cancel_req ) + cancel_req_len ) ;
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 ;
@ -405,6 +429,13 @@ PQgetCancel(PGconn *conn)
goto fail ;
}
req = ( CancelRequestPacket * ) & cancel - > cancel_req ;
req - > cancelRequestCode = ( MsgType ) pg_hton32 ( CANCEL_REQUEST_CODE ) ;
req - > backendPID = pg_hton32 ( conn - > be_pid ) ;
memcpy ( req - > cancelAuthCode , conn - > be_cancel_key , conn - > be_cancel_key_len ) ;
/* include the length field itself in the length */
cancel - > cancel_pkt_len = pg_hton32 ( cancel_req_len + 4 ) ;
return cancel ;
fail :
@ -412,6 +443,42 @@ fail:
return NULL ;
}
/*
* PQsendCancelRequest
* Submit a CancelRequest message , but don ' t wait for it to finish
*
* Returns : 1 if successfully submitted
* 0 if error ( conn - > errorMessage is set )
*/
int
PQsendCancelRequest ( PGconn * cancelConn )
{
CancelRequestPacket req ;
/* Start the message. */
if ( pqPutMsgStart ( 0 , cancelConn ) )
return STATUS_ERROR ;
/* Send the message body. */
memset ( & req , 0 , offsetof ( CancelRequestPacket , cancelAuthCode ) ) ;
req . cancelRequestCode = ( MsgType ) pg_hton32 ( CANCEL_REQUEST_CODE ) ;
req . backendPID = pg_hton32 ( cancelConn - > be_pid ) ;
if ( pqPutnchar ( ( char * ) & req , offsetof ( CancelRequestPacket , cancelAuthCode ) , cancelConn ) )
return STATUS_ERROR ;
if ( pqPutnchar ( cancelConn - > be_cancel_key , cancelConn - > be_cancel_key_len , cancelConn ) )
return STATUS_ERROR ;
/* Finish the message. */
if ( pqPutMsgEnd ( cancelConn ) )
return STATUS_ERROR ;
/* Flush to ensure backend gets it. */
if ( pqFlush ( cancelConn ) )
return STATUS_ERROR ;
return STATUS_OK ;
}
/* PQfreeCancel: free a cancel structure */
void
PQfreeCancel ( PGcancel * cancel )
@ -465,11 +532,8 @@ PQcancel(PGcancel *cancel, char *errbuf, int errbufsize)
int save_errno = SOCK_ERRNO ;
pgsocket tmpsock = PGINVALID_SOCKET ;
int maxlen ;
struct
{
uint32 packetlen ;
CancelRequestPacket cp ;
} crp ;
char recvbuf ;
int cancel_pkt_len ;
if ( ! cancel )
{
@ -571,15 +635,15 @@ retry3:
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 ) ;
cancel_pkt_len = pg_ntoh32 ( cancel - > cancel_pkt_len ) ;
retry4 :
if ( send ( tmpsock , ( char * ) & crp , sizeof ( crp ) , 0 ) ! = ( int ) sizeof ( crp ) )
/*
* Send the cancel request packet . It starts with the message length at
* cancel_pkt_len , followed by the actual packet .
*/
if ( send ( tmpsock , ( char * ) & cancel - > cancel_pkt_len , cancel_pkt_len , 0 ) ! = cancel_pkt_len )
{
if ( SOCK_ERRNO = = EINTR )
/* Interrupted system call - we'll just try again */
@ -596,7 +660,7 @@ retry4:
* read to obtain any data , we are just waiting for EOF to be signaled .
*/
retry5 :
if ( recv ( tmpsock , ( char * ) & crp , 1 , 0 ) < 0 )
if ( recv ( tmpsock , & recvbuf , 1 , 0 ) < 0 )
{
if ( SOCK_ERRNO = = EINTR )
/* Interrupted system call - we'll just try again */
Heikki Linnakangas
3 months ago