[RFC PATCH v3] sctp: fix the sendmsg() flag SCTP_EOF to comply to

[Wei Yongjun <yjwei@cn.fujitsu.com>]

It should be possible to send a message and set the SCTP_EOF flag
at the same time, but we don't support it yet. This patch fix the
sendmsg() flag SCTP_EOF to comply to spec.

Signed-off-by: Wei Yongjun <yjwei@cn.fujitsu.com>
---
V2 -> V3:
  - return -EWOULDBLOCK in non-blocking limitation case
  - allow SCTP_EOF in CLOSED state
---
 net/sctp/socket.c |   39 +++++++++++++++++++++++++++++++--------
 1 files changed, 31 insertions(+), 8 deletions(-)

diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index 0af3a8c..fcd8128 100644
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -1555,13 +1555,11 @@ SCTP_STATIC int sctp_sendmsg(struct kiocb *iocb, struct sock *sk,
 		goto out_nounlock;
 	}
 
-	/* If SCTP_EOF is set, no data can be sent. Disallow sending zero
-	 * length messages when SCTP_EOF|SCTP_ABORT is not set.
-	 * If SCTP_ABORT is set, the message length could be non zero with
-	 * the msg_iov set to the user abort reason.
+	/* Disallow sending zero length messages when SCTP_EOF|SCTP_ABORT
+	 * is not set. If SCTP_ABORT is set, the message length could be
+	 * non zero with the msg_iov set to the user abort reason.
 	 */
-	if (((sinfo_flags & SCTP_EOF) && (msg_len > 0)) ||
-	    (!(sinfo_flags & (SCTP_EOF|SCTP_ABORT)) && (msg_len = 0))) {
+	if (!(sinfo_flags & (SCTP_EOF|SCTP_ABORT)) && (msg_len = 0)) {
 		err = -EINVAL;
 		goto out_nounlock;
 	}
@@ -1618,13 +1616,24 @@ SCTP_STATIC int sctp_sendmsg(struct kiocb *iocb, struct sock *sk,
 			goto out_unlock;
 		}
 
-		if (sinfo_flags & SCTP_EOF) {
+		/* Forbid SCTP_EOF and send a message combination
+		 * on non-blocking sockets.
+		 */
+		if ((sinfo_flags & SCTP_EOF) && msg_len != 0 &&
+		    sk->sk_socket->file &&
+		    (sk->sk_socket->file->f_flags & O_NONBLOCK)) {
+			err = -EWOULDBLOCK;
+			goto out_nounlock;
+		}
+
+		if (sinfo_flags & SCTP_EOF && msg_len = 0) {
 			SCTP_DEBUG_PRINTK("Shutting down association: %p\n",
 					  asoc);
 			sctp_primitive_SHUTDOWN(asoc, NULL);
 			err = 0;
 			goto out_unlock;
 		}
+
 		if (sinfo_flags & SCTP_ABORT) {
 
 			chunk = sctp_make_abort_user(asoc, msg, msg_len);
@@ -1644,7 +1653,7 @@ SCTP_STATIC int sctp_sendmsg(struct kiocb *iocb, struct sock *sk,
 	if (!asoc) {
 		SCTP_DEBUG_PRINTK("There is no association yet.\n");
 
-		if (sinfo_flags & (SCTP_EOF | SCTP_ABORT)) {
+		if (sinfo_flags & SCTP_ABORT) {
 			err = -EINVAL;
 			goto out_unlock;
 		}
@@ -1850,6 +1859,20 @@ SCTP_STATIC int sctp_sendmsg(struct kiocb *iocb, struct sock *sk,
 	else
 		err = msg_len;
 
+	if (sinfo_flags & SCTP_EOF) {
+		if (sctp_state(asoc, ESTABLISHED)) {
+			SCTP_DEBUG_PRINTK("Shutting down association: %p\n",
+					  asoc);
+			sctp_primitive_SHUTDOWN(asoc, NULL);
+		} else {
+			/* Delay to shutdown association until assoc enter
+			 * ESTABLISHED state
+			 */
+			asoc->timeouts[SCTP_EVENT_TIMEOUT_AUTOCLOSE] = HZ/20;
+			asoc->autoclose = 1;
+		}
+	}
+
 	/* If we are already past ASSOCIATE, the lower
 	 * layers are responsible for association cleanup.
 	 */
-- 
1.6.5.2