stream: Return 0 when receiving sctp notification SCTP_COMM_LOST

It was seen on a real pcap trace (sctp & gsmtap_log) that the Linux
kernel stack may decide to kill the connection (sending an ABORT) if
it fails to transmit some data after a while:
ABORT Cause code: "Protocol violation (0x000d)",
      Cause Information: "Association exceeded its max_retrans count".
When this occurs, the kernel sends the
MSG_NOTIFICATION,SCTP_ASSOC_CHANGE,SCTP_COMM_LOST notification when
reading from the socket with sctp_recvmsg(). This basically signals that
the socket conn is dead, and subsequent writes to it will result in
send() failures (and receive SCTP_SEND_FAILED notification upon follow
up reads).
It's important to notice that after those events, there's no other sort
of different event like SHUTDOWN coming in, so that's the time at which
we must tell the user to close the socket.
Hence, let's signal the caller that the socket is dead by returning 0,
to comply with usual recv() API.

Related: SYS#6113
Change-Id: If94d44f25b76a96a5ea402fec9fc14c4e6296ba3
This commit is contained in:
Pau Espin 2022-09-30 14:26:02 +02:00
parent 04572b2f6a
commit 96271688cf
1 changed files with 2 additions and 1 deletions

View File

@ -1490,7 +1490,8 @@ static int _sctp_recvmsg_wrapper(int fd, struct msgb *msg)
break;
case SCTP_COMM_LOST:
LOGPC(DLINP, LOGL_DEBUG, " LOST\n");
break;
/* Handle this like a regular disconnect */
return 0;
case SCTP_RESTART:
LOGPC(DLINP, LOGL_DEBUG, " RESTART\n");
break;