[Spice-devel] [PATCH spice-gtk] Detect timeout conditions more aggressively on Linux

[Jeremy White]

This mitigates a fairly rare problem we see with our kiosk mode clients.
That is, normally if something goes wrong with a client connection
(e.g. the session is killed, or the server is restarted ), the kiosk will
exit on disconnect, and we get a chance to retry the connection, or
present the user with a 'server down' style message.

But in the case of a serious network problem or a server hard power
cycle (i.e. no TCP FIN packets can flow), our end user behavior is not
ideal - the kiosk appears to hang solid, requiring a power cycle.

That's because we've got the stock keepalive timeouts, or about 2 hours
and 11 minutes, before the client sees the disconnect.

This change will cause the client to recognize the server has vanished
without a TCP FIN after 75 seconds.

See this thread:
  https://lists.freedesktop.org/archives/spice-devel/2017-March/036553.html

As well as this bug:
  https://bugzilla.redhat.com/show_bug.cgi?id=1436589

Signed-off-by: Jeremy White <jwhite at codeweavers.com>
---
 configure.ac        | 18 ++++++++++++++++++
 meson.build         | 15 +++++++++++++++
 src/spice-session.c | 15 +++++++++++++++
 3 files changed, 48 insertions(+)

diff --git a/configure.ac b/configure.ac
index 0666e2a8..9c64a8dd 100644
--- a/configure.ac
+++ b/configure.ac
@@ -82,6 +82,24 @@ AM_CONDITIONAL([HAVE_EGL],[test "$have_egl" = "yes"])
 AS_IF([test "$have_egl" = "yes"],
        AC_DEFINE([HAVE_EGL], [1], [Define if supporting EGL]))
 
+AC_CHECK_DECL([TCP_KEEPIDLE], [have_tcp_keepidle="yes"],,
+              [#include <netinet/tcp.h>])
+AS_IF([test "x$have_tcp_keepidle" = "xyes"],
+      [AC_DEFINE([HAVE_TCP_KEEPIDLE],1,[Define to 1 if <netinet/tcp.h> has a TCP_KEEPIDLE definition])],
+)
+AC_CHECK_DECL([TCP_KEEPINTVL], [have_tcp_keepintvl="yes"],,
+              [#include <netinet/tcp.h>])
+AS_IF([test "x$have_tcp_keepintvl" = "xyes"],
+      [AC_DEFINE([HAVE_TCP_KEEPINTVL],1,[Define to 1 if <netinet/tcp.h> has a TCP_KEEPINTVL definition])],
+)
+AC_CHECK_DECL([TCP_KEEPCNT], [have_tcp_keepcnt="yes"],,
+              [#include <netinet/tcp.h>])
+AS_IF([test "x$have_tcp_keepcnt" = "xyes"],
+      [AC_DEFINE([HAVE_TCP_KEEPCNT],1,[Define to 1 if <netinet/tcp.h> has a TCP_KEEPCNT definition])],
+)
+
+
+
 AC_CHECK_LIBM
 AC_SUBST(LIBM)
 
diff --git a/meson.build b/meson.build
index e0fba930..f2ef94a9 100644
--- a/meson.build
+++ b/meson.build
@@ -72,6 +72,21 @@ foreach func : ['clearenv', 'strtok_r']
   endif
 endforeach
 
+# TCP_KEEPIDLE definition in netinet/tcp.h
+if compiler.has_header_symbol('netinet/tcp.h', 'TCP_KEEPIDLE')
+  spice_gtk_config_data.set('HAVE_TCP_KEEPIDLE', '1')
+endif
+
+# TCP_KEEPINTVL definition in netinet/tcp.h
+if compiler.has_header_symbol('netinet/tcp.h', 'TCP_KEEPINTVL')
+  spice_gtk_config_data.set('HAVE_TCP_KEEPINTVL', '1')
+endif
+
+# TCP_KEEPCNT definition in netinet/tcp.h
+if compiler.has_header_symbol('netinet/tcp.h', 'TCP_KEEPCNT')
+  spice_gtk_config_data.set('HAVE_TCP_KEEPCNT', '1')
+endif
+
 #
 # check for mandatory dependencies
 #
diff --git a/src/spice-session.c b/src/spice-session.c
index 89528970..f6ec6a83 100644
--- a/src/spice-session.c
+++ b/src/spice-session.c
@@ -18,6 +18,7 @@
 #include "config.h"
 
 #include <gio/gio.h>
+#include <gio/gnetworking.h>
 #include <glib.h>
 #ifdef G_OS_UNIX
 #include <gio/gunixsocketaddress.h>
@@ -2254,6 +2255,20 @@ GSocketConnection* spice_session_channel_open_host(SpiceSession *session, SpiceC
         g_socket_set_timeout(socket, 0);
         g_socket_set_blocking(socket, FALSE);
         g_socket_set_keepalive(socket, TRUE);
+
+        /* Make Linux client timeouts a bit more responsive */
+        /*  TODO:  Support Windows.  It appears as though you can
+                   set KEEPIDLE and KEEPINTVL, but not KEEPCNT.
+                   See SIO_KEEPALIVE_VALS */
+#ifdef HAVE_TCP_KEEPIDLE
+        g_socket_set_option(socket, IPPROTO_TCP, TCP_KEEPIDLE, 30, NULL);
+#endif
+#ifdef HAVE_TCP_KEEPINTVL
+        g_socket_set_option(socket, IPPROTO_TCP, TCP_KEEPINTVL, 15, NULL);
+#endif
+#ifdef HAVE_TCP_KEEPCNT
+        g_socket_set_option(socket, IPPROTO_TCP, TCP_KEEPCNT, 3, NULL);
+#endif
     }
 
     g_clear_object(&open_host.client);
-- 
2.11.0