Re: [PATCH] sctp: fix the sendmsg() flag SCTP_EOF to comply to spec

[Vlad Yasevich <vladislav.yasevich@hp.com>]

Wei Yongjun wrote:
> 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.

Hi Wei

Good start, but I don't think this will work with implicit connection.

We are going to attempt to associate, queue the DATA, and then issue a
shutdown, which will call sctp_sf_cookie_wait_prm_shutdown() thus never
sending.

Also, we might want to forbid this combination on non-blocking sockets
since we would essentially need to run the whole thing in a separate task.

-vlad

> 
> Signed-off-by: Wei Yongjun <yjwei@cn.fujitsu.com>
> ---
>  net/sctp/socket.c |   15 ++++++++++-----
>  1 files changed, 10 insertions(+), 5 deletions(-)
> 
> diff --git a/net/sctp/socket.c b/net/sctp/socket.c
> index 89af37a..d48e18c 100644
> --- a/net/sctp/socket.c
> +++ b/net/sctp/socket.c
> @@ -1540,13 +1540,12 @@ 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.
> +	/* 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;
>  	}
> @@ -1603,7 +1602,7 @@ SCTP_STATIC int sctp_sendmsg(struct kiocb *iocb, struct sock *sk,
>  			goto out_unlock;
>  		}
>  
> -		if (sinfo_flags & SCTP_EOF) {
> +		if ((sinfo_flags & SCTP_EOF) && msg_len = 0) {
>  			SCTP_DEBUG_PRINTK("Shutting down association: %p\n",
>  					  asoc);
>  			sctp_primitive_SHUTDOWN(asoc, NULL);
> @@ -1835,6 +1834,12 @@ SCTP_STATIC int sctp_sendmsg(struct kiocb *iocb, struct sock *sk,
>  	else
>  		err = msg_len;
>  
> +	if (sinfo_flags & SCTP_EOF) {
> +		SCTP_DEBUG_PRINTK("Shutting down association: %p\n",
> +				  asoc);
> +		sctp_primitive_SHUTDOWN(asoc, NULL);
> +	}
> +
>  	/* If we are already past ASSOCIATE, the lower
>  	 * layers are responsible for association cleanup.
>  	 */