From a9390874c76d30f655c31be9a4a4ac7c646f1d7e Mon Sep 17 00:00:00 2001
From: Andy Green <andy@warmcat.com>
Date: Wed, 18 Apr 2018 18:45:27 +0800
Subject: [PATCH] tcp keepalive: user TCP_USER_TIMEOUT on linux if extant

https://github.com/warmcat/libwebsockets/issues/1223
---
 CMakeLists.txt                | 5 +++++
 cmake/lws_config_private.h.in | 2 ++
 lib/plat/lws-plat-unix.c      | 8 ++++++++
 3 files changed, 15 insertions(+)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index fdc1a09a..e12e1889 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1365,6 +1365,11 @@ endif()
 
 CHECK_C_SOURCE_COMPILES("#define _GNU_SOURCE\n#include <unistd.h>\nint main(void) {int fd[2];\n return pipe2(fd, 0);\n}\n" LWS_HAVE_PIPE2)
 
+# tcp keepalive needs this on linux to work practically... but it only exists
+# after kernel 2.6.37
+
+CHECK_C_SOURCE_COMPILES("#include <linux/tcp.h>\nint main(void) { return TCP_USER_TIMEOUT; }\n" LWS_HAVE_TCP_USER_TIMEOUT)
+
 set(CMAKE_REQUIRED_LIBRARIES ${temp})
 # Generate the lws_config.h that includes all the public compilation settings.
 configure_file(
diff --git a/cmake/lws_config_private.h.in b/cmake/lws_config_private.h.in
index 267a3484..1578aea3 100644
--- a/cmake/lws_config_private.h.in
+++ b/cmake/lws_config_private.h.in
@@ -81,6 +81,8 @@
 /* Define to 1 if you have the <unistd.h> header file. */
 #cmakedefine LWS_HAVE_UNISTD_H
 
+#cmakedefine LWS_HAVE_TCP_USER_TIMEOUT
+
 /* Define to 1 if you have the `vfork' function. */
 #cmakedefine LWS_HAVE_VFORK
 
diff --git a/lib/plat/lws-plat-unix.c b/lib/plat/lws-plat-unix.c
index 55d26d41..c5c0ce61 100644
--- a/lib/plat/lws-plat-unix.c
+++ b/lib/plat/lws-plat-unix.c
@@ -348,6 +348,14 @@ lws_plat_set_socket_options(struct lws_vhost *vhost, int fd)
 		 */
 #else
 		/* set the keepalive conditions we want on it too */
+
+#if defined(LWS_HAVE_TCP_USER_TIMEOUT)
+		optval = 1000 * (vhost->ka_time +
+				 (vhost->ka_interval * vhost->ka_probes));
+		if (setsockopt(fd, IPPROTO_TCP, TCP_USER_TIMEOUT,
+			       (const void *)&optval, optlen) < 0)
+			return 1;
+#endif
 		optval = vhost->ka_time;
 		if (setsockopt(fd, IPPROTO_TCP, TCP_KEEPIDLE,
 			       (const void *)&optval, optlen) < 0)