From: Willy Tarreau <w@1wt.eu>
Date: Wed, 19 Dec 2018 13:36:29 +0000 (+0100)
Subject: MINOR: connection: remove an unwelcome dependency on struct stream
X-Git-Tag: v1.9.0~18
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=94031d30d71eea0fcb4e7a29388e62ee151a7ddf;p=thirdparty%2Fhaproxy.git

MINOR: connection: remove an unwelcome dependency on struct stream

There was a reference to struct stream in conn_free() for the case
where we're freeing a connection that doesn't have a mux attached.
For now we know it's always a stream, and we only need to do it to
put a NULL in s->si[1].end.

Let's do it better by storing the pointer to si[1].end in the context
and specifying that this pointer is always nulled if the mux is null.
This way it allows a connection to detach itself from wherever it's
being used. Maybe we could even get rid of the condition on the mux.
---

diff --git a/include/proto/connection.h b/include/proto/connection.h
index 441b51df00..a7b596a50f 100644
--- a/include/proto/connection.h
+++ b/include/proto/connection.h
@@ -669,15 +669,14 @@ static inline void conn_free(struct connection *conn)
 		sess->resp_conns--;
 		LIST_DEL(&conn->session_list);
 	}
-	/* If we temporarily stored the connection as the stream_interface's
-	 * end point, remove it.
+
+	/* By convention we always place a NULL where the ctx points to if the
+	 * mux is null. It may have been used to store the connection as a
+	 * stream_interface's end point for example.
 	 */
-	if (conn->ctx != NULL && conn->mux == NULL) {
-		struct stream *s = conn->ctx;
+	if (conn->ctx != NULL && conn->mux == NULL)
+		*(void **)conn->ctx = NULL;
 
-		if (objt_conn(s->si[1].end) == conn)
-			s->si[1].end = NULL;
-	}
 	/* The connection is currently in the server's idle list, so tell it
 	 * there's one less connection available in that list.
 	 */
diff --git a/src/backend.c b/src/backend.c
index 237668cc43..2407f8a32e 100644
--- a/src/backend.c
+++ b/src/backend.c
@@ -1052,12 +1052,13 @@ static void assign_tproxy_address(struct stream *s)
 #if defined(USE_OPENSSL) && defined(TLSEXT_TYPE_application_layer_protocol_negotiation)
 /*
  * Pick the right mux once the connection is established, we should now have
- * an alpn if available, so we are now able to choose.
+ * an alpn if available, so we are now able to choose. In this specific case
+ * the connection's context is &si[i].end.
  */
 static int conn_complete_server(struct connection *conn)
 {
 	struct conn_stream *cs = NULL;
-	struct stream *s = conn->ctx;
+	struct stream *s = container_of(conn->ctx, struct stream, si[1].end);
 	struct server *srv;
 
 	task_wakeup(s->task, TASK_WOKEN_IO);
@@ -1066,8 +1067,6 @@ static int conn_complete_server(struct connection *conn)
 	if (unlikely(!(conn->flags & (CO_FL_WAIT_L4_CONN | CO_FL_WAIT_L6_CONN | CO_FL_CONNECTED))))
 		conn->flags |= CO_FL_CONNECTED;
 
-	if (!s)
-		goto fail;
 	if (conn->flags & CO_FL_ERROR)
 		goto fail;
 	si_detach_endpoint(&s->si[1]);
@@ -1338,7 +1337,7 @@ int connect_server(struct stream *s)
 		}
 #if defined(USE_OPENSSL) && defined(TLSEXT_TYPE_application_layer_protocol_negotiation)
 		else {
-			srv_conn->ctx = s;
+			srv_conn->ctx = &s->si[1].end;
 			/* Store the connection into the stream interface,
 			 * while we still don't have a mux, so that if the
 			 * stream is destroyed before the connection is