update stream sockets with bound address/port

when isc_nm_listenstreamdns() is called with a local port of 0,
a random port is chosen. call uv_getsockname() to determine what
the port is as soon as the socket is bound, and add a function
isc_nmsocket_getaddr() to retrieve it, so that the caller can
connect to the listening socket. this will be used in cases
where the same process is acting as both client and server.

lib/isc/include/isc/netmgr.h

@@ -729,3 +729,9 @@ isc_nmhandle_set_tcp_nodelay(isc_nmhandle_t *handle, const bool value);
  *
  * \li 'handle' is a valid netmgr handle object.
  */
+
+isc_sockaddr_t
+isc_nmsocket_getaddr(isc_nmsocket_t *sock);
+/*%<
+ * Return the local address of 'sock'.
+ */

lib/isc/netmgr/netmgr.c

@@ -2538,6 +2538,12 @@ isc_nmhandle_set_tcp_nodelay(isc_nmhandle_t *handle, const bool value) {
 	return (result);
 }
 
+isc_sockaddr_t
+isc_nmsocket_getaddr(isc_nmsocket_t *sock) {
+	REQUIRE(VALID_NMSOCK(sock));
+	return (sock->iface);
+}
+
 #if ISC_NETMGR_TRACE
 /*
  * Dump all active sockets in netmgr. We output to stderr

lib/isc/netmgr/streamdns.c

@@ -748,6 +748,11 @@ isc_nm_listenstreamdns(isc_nm_t *mgr, uint32_t workers, isc_sockaddr_t *iface,
 		return (result);
 	}
 
+	/* copy the actual port we're listening on into sock->iface */
+	if (isc_sockaddr_getport(iface) == 0) {
+		listener->iface = listener->outer->iface;
+	}
+
 	listener->result = result;
 	atomic_store(&listener->active, true);
 	atomic_store(&listener->listening, true);

lib/isc/netmgr/tcp.c

@@ -353,6 +353,7 @@ start_tcp_child_job(void *arg) {
 	int r, flags = 0;
 	isc_result_t result = ISC_R_UNSET;
 	isc_loop_t *loop = sock->worker->loop;
+	struct sockaddr_storage ss;
 
 	(void)isc__nm_socket_min_mtu(sock->fd, sa_family);
 	(void)isc__nm_socket_tcp_maxseg(sock->fd, NM_MAXSEG);
@@ -417,8 +418,25 @@ start_tcp_child_job(void *arg) {
 
 	atomic_store(&sock->listening, true);
 
+	if (sock->tid == 0) {
+		r = uv_tcp_getsockname(&sock->uv_handle.tcp,
+				       (struct sockaddr *)&ss,
+				       &(int){ sizeof(ss) });
+		if (r != 0) {
+			goto done;
+		}
+
+		result = isc_sockaddr_fromsockaddr(&sock->parent->iface,
+						   (struct sockaddr *)&ss);
+		if (result != ISC_R_SUCCESS) {
+			goto done_result;
+		}
+	}
+
 done:
 	result = isc_uverr2result(r);
+
+done_result:
 	atomic_fetch_add(&sock->parent->rchildren, 1);
 
 	if (result != ISC_R_SUCCESS) {

lib/isc/netmgr/tlsstream.c

@@ -937,6 +937,11 @@ isc_nm_listentls(isc_nm_t *mgr, uint32_t workers, isc_sockaddr_t *iface,
 		return (result);
 	}
 
+	/* copy the actual port we're listening on into sock->iface */
+	if (isc_sockaddr_getport(iface) == 0) {
+		tlssock->iface = tlssock->outer->iface;
+	}
+
 	/* wait for listen result */
 	isc__nmsocket_attach(tlssock->outer, &tsock);
 	tlssock->result = result;