MEDIUM: receivers: add an rx_unbind() method in the protocols

This is used as a generic way to unbind a receiver at the end of
do_unbind_listener(). This allows to considerably simplify that function
since we can now let the protocol perform the cleanup. The generic code
was moved to sock.c, along with the conditional rx_disable() call. Now
the code also supports that the ->disable() function of the protocol
which acts on the listener performs the close itself and adjusts the
RX_F_BUOND flag accordingly.

include/haproxy/protocol-t.h

@@ -95,6 +95,7 @@ struct protocol {
 	/* functions acting on the receiver */
 	void (*rx_enable)(struct receiver *rx);         /* enable receiving on the receiver */
 	void (*rx_disable)(struct receiver *rx);        /* disable receiving on the receiver */
+	void (*rx_unbind)(struct receiver *rx);         /* unbind the receiver, most often closing the FD */
 	int (*rx_suspend)(struct receiver *rx);         /* temporarily suspend this receiver for a soft restart */
 	int (*rx_resume)(struct receiver *rx);          /* try to resume a temporarily suspended receiver */
 

include/haproxy/sock.h

@@ -35,6 +35,7 @@ extern struct xfer_sock_list *xfer_sock_list;
 int sock_create_server_socket(struct connection *conn);
 void sock_enable(struct receiver *rx);
 void sock_disable(struct receiver *rx);
+void sock_unbind(struct receiver *rx);
 int sock_get_src(int fd, struct sockaddr *sa, socklen_t salen, int dir);
 int sock_get_dst(int fd, struct sockaddr *sa, socklen_t salen, int dir);
 int sock_get_old_sockets(const char *unixsocket);

src/listener.c

@@ -543,7 +543,8 @@ void dequeue_proxy_listeners(struct proxy *px)
  * LI_ASSIGNED state, except if the FD is not closed, in which case it may
  * remain in LI_LISTEN. Depending on the process' status (master or worker),
  * the listener's bind options and the receiver's origin, it may or may not
- * close the receiver's FD. Must be called with the lock held.
+ * close the receiver's FD, according to what is provided at the receiver
+ * level. Must be called with the lock held.
  */
 void do_unbind_listener(struct listener *listener)
 {
@@ -557,40 +558,18 @@ void do_unbind_listener(struct listener *listener)
 		goto out_close;
 	}
 
-	if (listener->state >= LI_PAUSED) {
-		if (listener->state >= LI_READY) {
-			listener->rx.proto->disable(listener);
+	if (listener->state >= LI_READY) {
+		listener->rx.proto->disable(listener);
+		if (listener->rx.flags & RX_F_BOUND)
 			listener_set_state(listener, LI_LISTEN);
-		}
-		listener->rx.proto->rx_disable(&listener->rx);
 	}
 
  out_close:
-	/* There are a number of situations where we prefer to keep the FD and
-	 * not to close it (unless we're stopping, of course):
-	 *   - worker process unbinding from a worker's FD with socket transfer enabled => keep
-	 *   - master process unbinding from a master's inherited FD => keep
-	 *   - master process unbinding from a master's FD => close
-	 *   - master process unbinding from a worker's FD => close
-	 *   - worker process unbinding from a master's FD => close
-	 *   - worker process unbinding from a worker's FD => close
-	 */
+	if (listener->rx.flags & RX_F_BOUND)
+		listener->rx.proto->rx_unbind(&listener->rx);
 
-	if (!stopping && !master &&
-	    !(listener->rx.flags & RX_F_MWORKER) &&
-	    (global.tune.options & GTUNE_SOCKET_TRANSFER))
-		return;
-
-	if (!stopping && master &&
-	    listener->rx.flags & RX_F_MWORKER &&
-	    listener->rx.flags & RX_F_INHERITED)
-		return;
-
-	listener->rx.flags &= ~RX_F_BOUND;
-	if (listener->rx.fd != -1)
-		fd_delete(listener->rx.fd);
-	listener->rx.fd = -1;
-	if (listener->state > LI_ASSIGNED)
+	/* we may have to downgrade the listener if the rx was closed */
+	if (!(listener->rx.flags & RX_F_BOUND) && listener->state > LI_ASSIGNED)
 		listener_set_state(listener, LI_ASSIGNED);
 }
 

src/proto_sockpair.c

@@ -72,6 +72,7 @@ static struct protocol proto_sockpair = {
 	.listen = sockpair_bind_listener,
 	.enable = sockpair_enable_listener,
 	.disable = sockpair_disable_listener,
+	.rx_unbind = sock_unbind,
 	.rx_enable = sock_enable,
 	.rx_disable = sock_disable,
 	.accept = &listener_accept,

src/proto_tcp.c

@@ -66,6 +66,7 @@ static struct protocol proto_tcpv4 = {
 	.disable = tcp_disable_listener,
 	.rx_enable = sock_enable,
 	.rx_disable = sock_disable,
+	.rx_unbind = sock_unbind,
 	.rx_suspend = tcp_suspend_receiver,
 	.rx_resume = tcp_resume_receiver,
 	.accept = &listener_accept,
@@ -90,6 +91,7 @@ static struct protocol proto_tcpv6 = {
 	.disable = tcp_disable_listener,
 	.rx_enable = sock_enable,
 	.rx_disable = sock_disable,
+	.rx_unbind = sock_unbind,
 	.rx_suspend = tcp_suspend_receiver,
 	.rx_resume = tcp_resume_receiver,
 	.accept = &listener_accept,

src/proto_udp.c

@@ -62,6 +62,7 @@ static struct protocol proto_udp4 = {
 	.disable = udp_disable_listener,
 	.rx_enable = sock_enable,
 	.rx_disable = sock_disable,
+	.rx_unbind = sock_unbind,
 	.rx_suspend = udp_suspend_receiver,
 	.rx_resume = udp_resume_receiver,
 	.receivers = LIST_HEAD_INIT(proto_udp4.receivers),
@@ -84,6 +85,7 @@ static struct protocol proto_udp6 = {
 	.disable = udp_disable_listener,
 	.rx_enable = sock_enable,
 	.rx_disable = sock_disable,
+	.rx_unbind = sock_unbind,
 	.rx_suspend = udp_suspend_receiver,
 	.rx_resume = udp_resume_receiver,
 	.receivers = LIST_HEAD_INIT(proto_udp6.receivers),

src/proto_uxst.c

@@ -61,6 +61,7 @@ static struct protocol proto_unix = {
 	.disable = uxst_disable_listener,
 	.rx_enable = sock_enable,
 	.rx_disable = sock_disable,
+	.rx_unbind = sock_unbind,
 	.rx_suspend = uxst_suspend_receiver,
 	.accept = &listener_accept,
 	.connect = &uxst_connect_server,

src/sock.c

@@ -73,6 +73,37 @@ void sock_disable(struct receiver *rx)
 		fd_stop_recv(rx->fd);
 }
 
+/* stops, unbinds and possibly closes the FD associated with receiver rx */
+void sock_unbind(struct receiver *rx)
+{
+	/* There are a number of situations where we prefer to keep the FD and
+	 * not to close it (unless we're stopping, of course):
+	 *   - worker process unbinding from a worker's FD with socket transfer enabled => keep
+	 *   - master process unbinding from a master's inherited FD => keep
+	 *   - master process unbinding from a master's FD => close
+	 *   - master process unbinding from a worker's FD => close
+	 *   - worker process unbinding from a master's FD => close
+	 *   - worker process unbinding from a worker's FD => close
+	 */
+	if (rx->flags & RX_F_BOUND)
+		rx->proto->rx_disable(rx);
+
+	if (!stopping && !master &&
+	    !(rx->flags & RX_F_MWORKER) &&
+	    (global.tune.options & GTUNE_SOCKET_TRANSFER))
+		return;
+
+	if (!stopping && master &&
+	    rx->flags & RX_F_MWORKER &&
+	    rx->flags & RX_F_INHERITED)
+		return;
+
+	rx->flags &= ~RX_F_BOUND;
+	if (rx->fd != -1)
+		fd_delete(rx->fd);
+	rx->fd = -1;
+}
+
 /*
  * Retrieves the source address for the socket <fd>, with <dir> indicating
  * if we're a listener (=0) or an initiator (!=0). It returns 0 in case of