Update max concurrent streams limit in HTTP listeners on reconfig

This commit ensures that HTTP listeners concurrent streams limit gets
updated properly on reconfiguration.

lib/isc/include/isc/netmgr.h

@@ -129,6 +129,25 @@ isc_nmsocket_set_tlsctx(isc_nmsocket_t *listener, isc_tlsctx_t *tlsctx);
  * \li	'tlsctx' is a valid pointer to a TLS context object.
  */
 
+void
+isc_nmsocket_set_max_streams(isc_nmsocket_t *listener,
+			     const uint32_t  max_streams);
+/*%<
+ * Set the maximum allowed number of concurrent streams for accepted
+ * client connections. The implementation might be asynchronous
+ * depending on the listener socket type.
+ *
+ * The call is a no-op for any listener socket type that does not
+ * support concept of multiple sessions per a client
+ * connection. Currently, it works only for HTTP/2 listeners.
+ *
+ * Setting 'max_streams' to '0' instructs the listener that there is
+ * no limit for concurrent streams.
+ *
+ * Requires:
+ * \li	'listener' is a pointer to a valid network manager listener socket.
+ */
+
 #ifdef NETMGR_TRACE
 #define isc_nmhandle_attach(handle, dest) \
 	isc__nmhandle_attach(handle, dest, __FILE__, __LINE__, __func__)
@@ -609,6 +628,21 @@ isc_nm_http_makeuri(const bool https, const isc_sockaddr_t *sa,
  * \li 'outbuf' is a valid pointer to a buffer which will get the result;
  * \li 'outbuf_len' is a size of the result buffer and is greater than zero.
  */
+
+void
+isc_nm_http_set_endpoints(isc_nmsocket_t	  *listener,
+			  isc_nm_http_endpoints_t *eps);
+/*%<
+ * Asynchronously replace the set of HTTP endpoints (paths) within
+ * the listener socket object.  The function is intended to be used
+ * during reconfiguration.
+ *
+ * Requires:
+ * \li	'listener' is a pointer to a valid network manager listener socket
+ object with TLS support;
+ * \li	'eps' is a valid pointer to an HTTP endpoints set.
+ */
+
 #endif /* HAVE_LIBNGHTTP2 */
 
 void

lib/isc/netmgr/http.c

@@ -2454,7 +2454,7 @@ httplisten_acceptcb(isc_nmhandle_t *handle, isc_result_t result, void *cbarg) {
 
 	new_session(httplistensock->mgr->mctx, NULL, &session);
 	session->max_concurrent_streams =
-		httplistensock->h2.max_concurrent_streams;
+		atomic_load(&httplistensock->h2.max_concurrent_streams);
 	initialize_nghttp2_server_session(session);
 	handle->sock->h2.session = session;
 
@@ -2481,14 +2481,10 @@ isc_nm_listenhttp(isc_nm_t *mgr, uint32_t workers, isc_sockaddr_t *iface,
 
 	sock = isc_mem_get(mgr->mctx, sizeof(*sock));
 	isc__nmsocket_init(sock, mgr, isc_nm_httplistener, iface);
-	sock->h2.max_concurrent_streams =
+	atomic_init(&sock->h2.max_concurrent_streams,
-		NGHTTP2_INITIAL_MAX_CONCURRENT_STREAMS;
+		    NGHTTP2_INITIAL_MAX_CONCURRENT_STREAMS);
 
-	if (max_concurrent_streams > 0 &&
+	isc_nmsocket_set_max_streams(sock, max_concurrent_streams);
-	    max_concurrent_streams < NGHTTP2_INITIAL_MAX_CONCURRENT_STREAMS)
-	{
-		sock->h2.max_concurrent_streams = max_concurrent_streams;
-	}
 
 	atomic_store(&eps->in_use, true);
 	isc_nm_http_endpoints_attach(eps, &sock->h2.listener_endpoints);
@@ -2953,6 +2949,23 @@ isc__nm_http_set_tlsctx(isc_nmsocket_t *listener, isc_tlsctx_t *tlsctx) {
 	isc_nmsocket_set_tlsctx(listener->outer, tlsctx);
 }
 
+void
+isc__nm_http_set_max_streams(isc_nmsocket_t *listener,
+			     const uint32_t max_concurrent_streams) {
+	uint32_t max_streams = NGHTTP2_INITIAL_MAX_CONCURRENT_STREAMS;
+
+	REQUIRE(VALID_NMSOCK(listener));
+	REQUIRE(listener->type == isc_nm_httplistener);
+
+	if (max_concurrent_streams > 0 &&
+	    max_concurrent_streams < NGHTTP2_INITIAL_MAX_CONCURRENT_STREAMS)
+	{
+		max_streams = max_concurrent_streams;
+	}
+
+	atomic_store(&listener->h2.max_concurrent_streams, max_streams);
+}
+
 static const bool base64url_validation_table[256] = {
 	false, false, false, false, false, false, false, false, false, false,
 	false, false, false, false, false, false, false, false, false, false,

lib/isc/netmgr/netmgr-int.h

@@ -872,7 +872,7 @@ typedef struct isc_nmsocket_h2 {
 	isc_nmsocket_t *httpserver;
 
 	/* maximum concurrent streams (server-side) */
-	uint32_t max_concurrent_streams;
+	atomic_uint_fast32_t max_concurrent_streams;
 
 	uint32_t min_ttl; /* used to set "max-age" in responses */
 
@@ -1817,6 +1817,10 @@ isc__nm_httpsession_detach(isc_nm_http_session_t **sessionp);
 void
 isc__nm_http_set_tlsctx(isc_nmsocket_t *sock, isc_tlsctx_t *tlsctx);
 
+void
+isc__nm_http_set_max_streams(isc_nmsocket_t *listener,
+			     const uint32_t max_concurrent_streams);
+
 #endif
 
 void

lib/isc/netmgr/netmgr.c

@@ -3373,6 +3373,23 @@ isc_nmsocket_set_tlsctx(isc_nmsocket_t *listener, isc_tlsctx_t *tlsctx) {
 	};
 }
 
+void
+isc_nmsocket_set_max_streams(isc_nmsocket_t *listener,
+			     const uint32_t max_streams) {
+	REQUIRE(VALID_NMSOCK(listener));
+	switch (listener->type) {
+#if HAVE_LIBNGHTTP2
+	case isc_nm_httplistener:
+		isc__nm_http_set_max_streams(listener, max_streams);
+		break;
+#endif /* HAVE_LIBNGHTTP2 */
+	default:
+		UNUSED(max_streams);
+		break;
+	};
+	return;
+}
+
 void
 isc__nmsocket_log_tls_session_reuse(isc_nmsocket_t *sock, isc_tls_t *tls) {
 	const int log_level = ISC_LOG_DEBUG(1);

lib/ns/interfacemgr.c

@@ -943,13 +943,26 @@ replace_listener_tlsctx(ns_interface_t *ifp, isc_tlsctx_t *newctx) {
 	}
 }
 
+#ifdef HAVE_LIBNGHTTP2
 static void
 update_http_settings(ns_interface_t *ifp, ns_listenelt_t *le) {
+	isc_nmsocket_t *listener;
+
 	REQUIRE(le->is_http);
 
 	INSIST(ifp->http_quota != NULL);
 	isc_quota_max(ifp->http_quota, le->http_max_clients);
+
+	if (ifp->http_secure_listensocket != NULL) {
+		listener = ifp->http_secure_listensocket;
+	} else {
+		INSIST(ifp->http_listensocket != NULL);
+		listener = ifp->http_listensocket;
+	}
+
+	isc_nmsocket_set_max_streams(listener, le->max_concurrent_streams);
 }
+#endif /* HAVE_LIBNGHTTP2 */
 
 static void
 update_listener_configuration(ns_interfacemgr_t *mgr, ns_interface_t *ifp,
@@ -969,6 +982,7 @@ update_listener_configuration(ns_interfacemgr_t *mgr, ns_interface_t *ifp,
 		replace_listener_tlsctx(ifp, le->sslctx);
 	}
 
+#ifdef HAVE_LIBNGHTTP2
 	/*
 	 * Let's update HTTP listener settings
 	 * on reconfiguration.
@@ -976,6 +990,8 @@ update_listener_configuration(ns_interfacemgr_t *mgr, ns_interface_t *ifp,
 	if (le->is_http) {
 		update_http_settings(ifp, le);
 	}
+#endif /* HAVE_LIBNGHTTP2 */
+
 	UNLOCK(&mgr->lock);
 }