sctp: fix missing send up SCTP_SENDER_DRY_EVENT when subscribe it

We forgot to send up SCTP_SENDER_DRY_EVENT notification when
user app subscribes to this event, and there is no data to be
sent or retransmit.

This is required by the Socket API and used by the DTLS/SCTP
implementation.

Reported-by: Michael Tüxen <Michael.Tuexen@lurchi.franken.de>
Signed-off-by: Wei Yongjun <yjwei@cn.fujitsu.com>
Tested-by: Robin Seggelmann <seggelmann@fh-muenster.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index 6766913a53e626279a7a2f4eb543e1f9fa7b5263..08c6238802de1fad5b81d1e7943ebc61c7430952 100644 (file)
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -2073,10 +2073,33 @@ static int sctp_setsockopt_disable_fragments(struct sock *sk,
 static int sctp_setsockopt_events(struct sock *sk, char __user *optval,
                                  unsigned int optlen)
 {
+       struct sctp_association *asoc;
+       struct sctp_ulpevent *event;
+
        if (optlen > sizeof(struct sctp_event_subscribe))
                return -EINVAL;
        if (copy_from_user(&sctp_sk(sk)->subscribe, optval, optlen))
                return -EFAULT;
+
+       /*
+        * At the time when a user app subscribes to SCTP_SENDER_DRY_EVENT,
+        * if there is no data to be sent or retransmit, the stack will
+        * immediately send up this notification.
+        */
+       if (sctp_ulpevent_type_enabled(SCTP_SENDER_DRY_EVENT,
+                                      &sctp_sk(sk)->subscribe)) {
+               asoc = sctp_id2assoc(sk, 0);
+
+               if (asoc && sctp_outq_is_empty(&asoc->outqueue)) {
+                       event = sctp_ulpevent_make_sender_dry_event(asoc,
+                                       GFP_ATOMIC);
+                       if (!event)
+                               return -ENOMEM;
+
+                       sctp_ulpq_tail_event(&asoc->ulpq, event);
+               }
+       }
+
        return 0;
 }