BUG/MEDIUM: mux-h1: Handle connection error after a synchronous send

Since commit d1480cc ("BUG/MEDIUM: stream-int: do not rely on the
connection error once established"), connection errors are not handled
anymore by the stream-connector once established. But it is a problem for
the H1 mux when an error occurred during a synchronous send in
h1_snd_buf(). Because in this case, the connction error is just missed. It
leads to a session leak until a timeout is reached (client or server).

To fix the bug, the connection flags are now checked in h1_snd_buf(). If
there is an error, it is reported to the stconn level by setting SF_FL_ERROR
flags. But only if there is no pending data in the input buffer.

This patch should solve the issue #1774. It must be backported as far as
2.2.

src/mux_h1.c

@@ -3729,6 +3729,9 @@ static size_t h1_snd_buf(struct stconn *sc, struct buffer *buf, size_t count, in
 		else
 			TRACE_DEVEL("h1c obuf not allocated", H1_EV_STRM_SEND|H1_EV_H1S_BLK, h1c->conn, h1s);
 
+		if ((h1c->conn->flags & (CO_FL_ERROR|CO_FL_SOCK_WR_SH)))
+			break;
+
 		if ((count - ret) > 0)
 			h1c->flags |= H1C_F_CO_MSG_MORE;
 
@@ -3740,7 +3743,7 @@ static size_t h1_snd_buf(struct stconn *sc, struct buffer *buf, size_t count, in
 			break;
 	}
 
-	if (h1c->flags & H1C_F_ST_ERROR) {
+	if (h1c->flags & H1C_F_ST_ERROR || ((h1c->conn->flags & CO_FL_ERROR) && !b_data(&h1c->ibuf))) {
 		se_fl_set(h1s->sd, SE_FL_ERROR);
 		TRACE_ERROR("reporting error to the app-layer stream", H1_EV_STRM_SEND|H1_EV_H1S_ERR|H1_EV_STRM_ERR, h1c->conn, h1s);
 	}