Joakim Tjernlund wrote:
> I once wrote this patch to solve a problem which I logged to be:
> Let EAGAIN be fatal for write to socket. Needed
> to unlock a hung connection where the www client has
> stopped reading its socket.
Umm, if your code asks to wait forever until it can write, then that is what
it should do. The fix is nonsensical.
> I cannot remember the details so I post the patch in hope it makes
> sense to anyone. Possibly I have solved the problem at the wrong place.
> Anyhow, here goes the patch:
You definitely solved the problem in the wrong place. If you don't want to
wait forever for a write to be possible, then don't do that. But if you do
that, then that's what should happen.
> Index: crypto/bio/bss_conn.c
> ===================================================================
> --- crypto/bio/bss_conn.c (revision 31831)
> +++ crypto/bio/bss_conn.c (revision 31832)
> @@ -444,7 +444,11 @@
> if (ret <= 0)
> {
> if (BIO_sock_should_retry(ret))
> - BIO_set_retry_write(b);
> + if (get_last_socket_error() == EAGAIN) {
> + get_last_socket_error() = ECONNRESET;
> + shutdown(b->num, SHUT_WR);
> + } else
> + BIO_set_retry_write(b);
> }
> return(ret);
> }
> Index: crypto/bio/bss_sock.c
> ===================================================================
> --- crypto/bio/bss_sock.c (revision 31831)
> +++ crypto/bio/bss_sock.c (revision 31832)
> @@ -159,7 +159,11 @@
> if (ret <= 0)
> {
> if (BIO_sock_should_retry(ret))
> - BIO_set_retry_write(b);
> + if (get_last_socket_error() == EAGAIN) {
> + get_last_socket_error() = ECONNRESET;
> + shutdown(b->num, SHUT_WR);
> + } else
> + BIO_set_retry_write(b);
> }
> return(ret);
> }
A "hung connection" *should* remain locked if the client stops reading from
its socket. The client might continue reading from its connection in a day,
a week, or a year. If the server wants to timeout the connection, it can and
should do so.
DS
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