TCP_FASTOPEN

READMEs/README.tcp_fastopen.md

@@ -0,0 +1,32 @@
+# `TCP_FASTOPEN` support in lws
+
+Lws supports enabling TCP_FASTOPEN oper-vhost for listen sockets.
+
+## Enabling per vhost serving
+
+Set the `info.fo_listen_queue` to nonzero at vhost creation.  Different
+platforms interpret this number differently, zero always disables it
+but on Linux, the number is interpreted as a SYN queue length.
+
+On FreeBSD, OSX and Windows, the number is basically a bool, with the
+extra restriction OSX and Windows only allows 0 or 1.
+
+## Enabling Linux for serving with TCP_FASTOPEN
+
+To configure the kernel for listening socket TCP_FASTOPEN, you need
+
+```
+# sysctl -w net.ipv4.tcp_fastopen=3
+```
+
+## Enabling BSD for serving with TCP_FASTOPEN
+
+At least on FreeBSD, you need to set the net.inet.tcp.fastopen.enabled
+sysctl to 1
+
+## Enabling Windows for serving with TCP_FASTOPEN
+
+```
+> netsh int tcp set global fastopenfallback=disabled
+> netsh int tcp show global
+```

include/libwebsockets/lws-context-vhost.h

@@ -854,16 +854,22 @@ struct lws_context_creation_info {
 
 #if defined(LWS_WITH_SYS_METRICS)
 	const struct lws_metric_policy		*metrics_policies;
-	/**< non-SS policy metrics policies */
+	/**< CONTEXT: non-SS policy metrics policies */
 	const char				*metrics_prefix;
-	/**< prefix for this context's metrics, used to distinguish metrics
-	 * pooled from different processes / applications, so, eg what would
-	 * be "cpu.svc" if this is NULL becomes "myapp.cpu.svc" is this is
+	/**< CONTEXT: prefix for this context's metrics, used to distinguish
+	 * metrics pooled from different processes / applications, so, eg what
+	 * would be "cpu.svc" if this is NULL becomes "myapp.cpu.svc" is this is
 	 * set to "myapp".  Policies are applied using the name with the prefix,
 	 * if present.
 	 */
 #endif
 
+	int					fo_listen_queue;
+	/**< VHOST: 0 = no TCP_FASTOPEN, nonzero = enable TCP_FASTOPEN if the
+	 * platform supports it, with the given queue length for the listen
+	 * socket.
+	 */
+
 	/* Add new things just above here ---^
 	 * This is part of the ABI, don't needlessly break compatibility
 	 *

lib/core-net/private-lib-core-net.h

@@ -535,6 +535,7 @@ struct lws_vhost {
 	int keepalive_timeout;
 	int timeout_secs_ah_idle;
 	int connect_timeout_secs;
+	int fo_listen_queue;
 
 	int count_bound_wsi;
 

lib/core-net/vhost.c

@@ -659,15 +659,16 @@ lws_create_vhost(struct lws_context *context,
 			vh->count_protocols++)
 				;
 
-	vh->options = info->options;
-	vh->pvo = info->pvo;
-	vh->headers = info->headers;
-	vh->user = info->user;
-	vh->finalize = info->finalize;
-	vh->finalize_arg = info->finalize_arg;
-	vh->listen_accept_role = info->listen_accept_role;
-	vh->listen_accept_protocol = info->listen_accept_protocol;
-	vh->unix_socket_perms = info->unix_socket_perms;
+	vh->options			= info->options;
+	vh->pvo				= info->pvo;
+	vh->headers			= info->headers;
+	vh->user			= info->user;
+	vh->finalize			= info->finalize;
+	vh->finalize_arg		= info->finalize_arg;
+	vh->listen_accept_role		= info->listen_accept_role;
+	vh->listen_accept_protocol	= info->listen_accept_protocol;
+	vh->unix_socket_perms		= info->unix_socket_perms;
+	vh->fo_listen_queue		= info->fo_listen_queue;
 
 	LWS_FOR_EVERY_AVAILABLE_ROLE_START(ar)
 	if (lws_rops_fidx(ar, LWS_ROPS_init_vhost) &&

lib/plat/unix/unix-sockets.c

@@ -220,6 +220,16 @@ lws_plat_set_socket_options_ip(lws_sockfd_type fd, uint8_t pri, int lws_flags)
 	int en;
 #endif
 
+#if 0
+#if defined(TCP_FASTOPEN_CONNECT)
+	optval = 1;
+	if (setsockopt(fd, IPPROTO_TCP, TCP_FASTOPEN_CONNECT, (void *)&optval,
+		       sizeof(optval)))
+		lwsl_warn("%s: FASTOPEN_CONNECT failed\n", __func__);
+	optval = (int)pri;
+#endif
+#endif
+
 #if !defined(__APPLE__) && \
       !defined(__FreeBSD__) && !defined(__FreeBSD_kernel__) &&        \
       !defined(__NetBSD__) && \

lib/roles/http/server/lejp-conf.c

@@ -119,6 +119,7 @@ static const char * const paths_vhosts[] = {
 	"vhosts[].ignore-missing-cert",
 	"vhosts[].error-document-404",
 	"vhosts[].alpn",
+	"vhosts[].fo-listen-queue",
 	"vhosts[].ssl-client-option-set",
 	"vhosts[].ssl-client-option-clear",
 	"vhosts[].tls13-ciphers",
@@ -187,6 +188,7 @@ enum lejp_vhost_paths {
 	LEJPVP_IGNORE_MISSING_CERT,
 	LEJPVP_ERROR_DOCUMENT_404,
 	LEJPVP_ALPN,
+	LWJPVP_FO_LISTEN_QUEUE,
 	LEJPVP_SSL_CLIENT_OPTION_SET,
 	LEJPVP_SSL_CLIENT_OPTION_CLEAR,
 	LEJPVP_TLS13_CIPHERS,
@@ -693,6 +695,9 @@ lejp_vhosts_cb(struct lejp_ctx *ctx, char reason)
 	case LEJPVP_CGI_TIMEOUT:
 		a->m.cgi_timeout = atoi(ctx->buf);
 		return 0;
+	case LWJPVP_FO_LISTEN_QUEUE:
+		a->info->fo_listen_queue = atoi(ctx->buf);
+		return 0;
 	case LEJPVP_KEEPALIVE_TIMEOUT:
 		a->info->keepalive_timeout = atoi(ctx->buf);
 		return 0;

lib/roles/http/server/server.c

@@ -24,6 +24,10 @@
 
 #include "private-lib-core.h"
 
+#if !defined(SOL_TCP) && defined(IPPROTO_TCP)
+#define SOL_TCP IPPROTO_TCP
+#endif
+
 const char * const method_names[] = {
 	"GET", "POST",
 #if defined(LWS_WITH_HTTP_UNCOMMON_HEADERS)
@@ -345,6 +349,29 @@ done_list:
 		vhost->lserv_wsi = wsi;
 		lws_pt_unlock(pt);
 
+#if defined(WIN32) && defined(TCP_FASTOPEN)
+		if (vhost->fo_listen_queue) {
+			int optval = 1;
+			if (setsockopt(wsi->desc.sockfd, IPPROTO_TCP,
+				       TCP_FASTOPEN,
+				       (const char*)&optval, sizeof(optval)) < 0) {
+				int error = LWS_ERRNO;
+				lwsl_warn("%s: TCP_NODELAY failed with error %d\n",
+						__func__, error);
+			}
+		}
+#else
+#if defined(TCP_FASTOPEN)
+		if (vhost->fo_listen_queue) {
+			int qlen = vhost->fo_listen_queue;
+
+			if (setsockopt(wsi->desc.sockfd, SOL_TCP, TCP_FASTOPEN,
+				       &qlen, sizeof(qlen)))
+				lwsl_warn("%s: TCP_FASTOPEN failed\n", __func__);
+		}
+#endif
+#endif
+
 		n = listen(wsi->desc.sockfd, LWS_SOMAXCONN);
 		if (n < 0) {
 			lwsl_err("listen failed with error %d\n", LWS_ERRNO);

minimal-examples/http-server/minimal-http-server-tls/minimal-http-server-tls.c

@@ -126,6 +126,7 @@ int main(int argc, const char **argv)
 		LWS_SERVER_OPTION_HTTP_HEADERS_SECURITY_BEST_PRACTICES_ENFORCE;
 	info.ssl_cert_filepath = "localhost-100y.cert";
 	info.ssl_private_key_filepath = "localhost-100y.key";
+	info.fo_listen_queue = 32;
 
 #if defined(LWS_WITH_PLUGINS)
 	info.plugin_dirs = plugin_dirs;