Re: [Qemu-devel] [PATCH 2/3] slirp: Propagate host TCP RST to the guest.

["Edgar E. Iglesias" <edgar.iglesias@xilinx.com>]

On Tue, Apr 05, 2016 at 05:14:31PM -0700, steven@steven676.net wrote:
> When the host aborts (RST) it's side of a TCP connection we need to
> propagate that RST to the guest. The current code can leave such guest
> connections dangling forever. Spotted by Jason Wessel.
> 
> [steven@steven676.net: coding style adjustments]
> Signed-off-by: Steven Luo <steven+qemu@steven676.net>
> ---
> Edgar proposed this patch many years ago:
> 
> https://lists.gnu.org/archive/html/qemu-devel/2008-06/msg00383.html
> 
> It doesn't appear that it was ever merged.  (It's the top Google result
> for "QEMU slirp RST".)  I've been unable to test the specific case it
> addresses (an established connection interrupted by RST), but the
> discussion from 2008 seems to imply it worked for the person reporting
> the problem then, and my next patch builds on this one.
> 
> As this patch isn't my work and did not come with a Signed-off-by line,
> I'm not entirely clear on how I should handle that.

Hi Steven,

I don't mind to leave it as is but you could also use the --author
argument to git commit to keep the authorship as edgar.iglesias@gmail.com

BTW, I had totally forgotten about this... thanks for picking it up!

Best regards,
Edgar


> 
>  slirp/socket.c | 17 ++++++++++++++++-
>  1 file changed, 16 insertions(+), 1 deletion(-)
> 
> diff --git a/slirp/socket.c b/slirp/socket.c
> index b836c42..4372ec2 100644
> --- a/slirp/socket.c
> +++ b/slirp/socket.c
> @@ -176,9 +176,24 @@ soread(struct socket *so)
>  		if (nn < 0 && (errno == EINTR || errno == EAGAIN))
>  			return 0;
>  		else {
> +			int err;
> +			socklen_t slen = sizeof err;
> +
> +			err = errno;
> +			if (nn == 0) {
> +				getsockopt(so->s, SOL_SOCKET, SO_ERROR,
> +					   &err, &slen);
> +			}
> +
>  			DEBUG_MISC((dfd, " --- soread() disconnected, nn = %d, errno = %d-%s\n", nn, errno,strerror(errno)));
>  			sofcantrcvmore(so);
> -			tcp_sockclosed(sototcpcb(so));
> +
> +			if (err == ECONNRESET
> +			    || err == ENOTCONN || err == EPIPE) {
> +				tcp_drop(sototcpcb(so), err);
> +			} else {
> +				tcp_sockclosed(sototcpcb(so));
> +			}
>  			return -1;
>  		}
>  	}
> -- 
> 2.1.4
>