MINOR: connection: implement conn_release()

Several places reuse the same code to ensure a connection is properly
freed, either via its MUX or by calling the proper set of functions.
Factorize all of this in a new function conn_release().

This new function is now called via session_free() and
session_accept_fd(). It will also be reused on delete server to
proactively close idle connections.

include/haproxy/connection.h

@@ -89,6 +89,7 @@ void conn_delete_from_tree(struct connection *conn);
 void conn_init(struct connection *conn, void *target);
 struct connection *conn_new(void *target);
 void conn_free(struct connection *conn);
+void conn_release(struct connection *conn);
 struct conn_hash_node *conn_alloc_hash_node(struct connection *conn);
 struct sockaddr_storage *sockaddr_alloc(struct sockaddr_storage **sap, const struct sockaddr_storage *orig, socklen_t len);
 void sockaddr_free(struct sockaddr_storage **sap);

src/connection.c

@@ -603,6 +603,21 @@ void conn_free(struct connection *conn)
 	pool_free(pool_head_connection, conn);
 }
 
+/* Close all <conn> internal layers accordingly prior to freeing it. */
+void conn_release(struct connection *conn)
+{
+	if (conn->mux) {
+		conn->mux->destroy(conn->ctx);
+	}
+	else {
+		conn_stop_tracking(conn);
+		conn_full_close(conn);
+		if (conn->destroy_cb)
+			conn->destroy_cb(conn);
+		conn_free(conn);
+	}
+}
+
 struct conn_hash_node *conn_alloc_hash_node(struct connection *conn)
 {
 	struct conn_hash_node *hash_node = NULL;

src/session.c

@@ -89,18 +89,9 @@ void session_free(struct session *sess)
 	list_for_each_entry_safe(pconns, pconns_back, &sess->priv_conns, sess_el) {
 		list_for_each_entry_safe(conn, conn_back, &pconns->conn_list, sess_el) {
 			LIST_DEL_INIT(&conn->sess_el);
-			if (conn->mux) {
 			conn->owner = NULL;
 			conn->flags &= ~CO_FL_SESS_IDLE;
-				conn->mux->destroy(conn->ctx);
+			conn_release(conn);
-			} else {
-				/* We have a connection, but not yet an associated mux.
-				 * So destroy it now.
-				 */
-				conn_stop_tracking(conn);
-				conn_full_close(conn);
-				conn_free(conn);
-			}
 		}
 		MT_LIST_DELETE(&pconns->srv_el);
 		pool_free(pool_head_sess_priv_conns, pconns);
@@ -323,15 +314,8 @@ int session_accept_fd(struct connection *cli_conn)
 		     MSG_DONTWAIT|MSG_NOSIGNAL);
 	}
 
-	if (cli_conn->mux) {
 	/* Mux is already initialized for active reversed connection. */
-		cli_conn->mux->destroy(cli_conn->ctx);
+	conn_release(cli_conn);
-	}
-	else {
-		conn_stop_tracking(cli_conn);
-		conn_full_close(cli_conn);
-		conn_free(cli_conn);
-	}
 	listener_release(l);
 	return ret;
 }