MINOR: quic: reconnect quic-conn socket on address migration

UDP addresses may change over time for a QUIC connection. When using
quic-conn owned socket, we have to detect address change to break the
bind/connect association on the socket.

For the moment, on change detected, QUIC connection socket is closed and
a new one is opened. In the future, we may improve this by trying to
keep the original socket and reexecute only bind/connect syscalls.

This change is part of quic-conn owned socket implementation.
It may be backported to 2.7 after a period of observation.

Author: a-denoyelle

include/haproxy/quic_sock.h

@@ -63,7 +63,7 @@ static inline char qc_test_fd(struct quic_conn *qc)
 
 void qc_alloc_fd(struct quic_conn *qc, const struct sockaddr_storage *src,
                  const struct sockaddr_storage *dst);
-void qc_release_fd(struct quic_conn *qc);
+void qc_release_fd(struct quic_conn *qc, int reinit);
 
 void quic_accept_push_qc(struct quic_conn *qc);
 

src/quic_conn.c

@@ -4960,7 +4960,7 @@ void quic_conn_release(struct quic_conn *qc)
 	BUG_ON(qc->mux_state == QC_MUX_READY);
 
 	/* Close quic-conn socket fd. */
-	qc_release_fd(qc);
+	qc_release_fd(qc, 0);
 
 	/* in the unlikely (but possible) case the connection was just added to
 	 * the accept_list we must delete it from there.
@@ -6369,6 +6369,16 @@ static int qc_handle_conn_migration(struct quic_conn *qc,
 	 * peer's address, unless it has previously validated that address.
 	 */
 
+	/* Update quic-conn owned socket if in used.
+	 * TODO try to reuse it instead of closing and opening a new one.
+	 */
+	if (qc_test_fd(qc)) {
+		/* TODO try to reuse socket instead of closing it and opening a new one. */
+		TRACE_STATE("Connection migration detected, allocate a new connection socket", QUIC_EV_CONN_LPKT, qc);
+		qc_release_fd(qc, 1);
+		qc_alloc_fd(qc, local_addr, peer_addr);
+	}
+
 	qc->local_addr = *local_addr;
 	qc->peer_addr = *peer_addr;
 	HA_ATOMIC_INC(&qc->prx_counters->conn_migration_done);

src/quic_sock.c

@@ -748,12 +748,17 @@ void qc_alloc_fd(struct quic_conn *qc, const struct sockaddr_storage *src,
 		close(fd);
 }
 
-/* Release socket file-descriptor specific for QUIC connection <qc>. */
-void qc_release_fd(struct quic_conn *qc)
+/* Release socket file-descriptor specific for QUIC connection <qc>. Set
+ * <reinit> if socket should be reinitialized after address migration.
+ */
+void qc_release_fd(struct quic_conn *qc, int reinit)
 {
 	if (qc_test_fd(qc)) {
 		fd_delete(qc->fd);
 		qc->fd = DEAD_FD_MAGIC;
+
+		if (reinit)
+			qc_init_fd(qc);
 	}
 }