From ae3b37460b677ebd6f1ad12dab76055e7879fcaf Mon Sep 17 00:00:00 2001
From: james <james@e7ae566f-a301-0410-adde-c780ea21d3b5>
Date: Tue, 18 Nov 2008 05:15:22 +0000
Subject: Added --tcp-nodelay option: Macro that sets TCP_NODELAY socket flag
 on the server as well as pushes it to connecting clients.

git-svn-id: http://svn.openvpn.net/projects/openvpn/branches/BETA21/openvpn@3513 e7ae566f-a301-0410-adde-c780ea21d3b5
---
 helper.c  | 39 +++++++++++++++++++++++++++++++++++++++
 helper.h  |  1 +
 openvpn.8 | 25 +++++++++++++++++++++++++
 options.c | 10 ++++++++++
 options.h |  1 +
 5 files changed, 76 insertions(+)

diff --git a/helper.c b/helper.c
index 2abb417..a8bbea0 100644
--- a/helper.c
+++ b/helper.c
@@ -96,6 +96,14 @@ print_str_int (const char *str, const int i, struct gc_arena *gc)
   return BSTR (&out);
 }
 
+static const char *
+print_str (const char *str, struct gc_arena *gc)
+{
+  struct buffer out = alloc_buf_gc (128, gc);
+  buf_printf (&out, "%s", str);
+  return BSTR (&out);
+}
+
 static void
 helper_add_route (const in_addr_t network, const in_addr_t netmask, struct options *o)
 {
@@ -438,3 +446,34 @@ helper_keepalive (struct options *o)
 	}
     }
 }
+
+/*
+ *
+ * HELPER DIRECTIVE:
+ *
+ * tcp-nodelay
+ *
+ * EXPANDS TO:
+ *
+ * if mode server:
+ *   socket-flags TCP_NODELAY
+ *   push "socket-flags TCP_NODELAY"
+ */
+void
+helper_tcp_nodelay (struct options *o)
+{
+#if P2MP_SERVER
+  if (o->server_flags & SF_TCP_NODELAY_HELPER)
+    {
+      if (o->mode == MODE_SERVER)
+	{
+	  o->sockflags |= SF_TCP_NODELAY;	  
+	  push_option (o, print_str ("socket-flags TCP_NODELAY", &o->gc), M_USAGE);
+	}
+      else
+	{
+	  ASSERT (0);
+	}
+    }
+#endif
+}
diff --git a/helper.h b/helper.h
index 2677f58..52a3a40 100644
--- a/helper.h
+++ b/helper.h
@@ -33,5 +33,6 @@
 
 void helper_keepalive (struct options *o);
 void helper_client_server (struct options *o);
+void helper_tcp_nodelay (struct options *o);
 
 #endif
diff --git a/openvpn.8 b/openvpn.8
index 790501d..ab56e97 100644
--- a/openvpn.8
+++ b/openvpn.8
@@ -2866,6 +2866,31 @@ OpenVPN will start to drop outgoing packets directed
 at this client.
 .\"*********************************************************
 .TP
+.B --tcp-nodelay
+This macro sets the TCP_NODELAY socket flag on the server
+as well as pushes it to connecting clients.  The TCP_NODELAY
+flag disables the Nagle algorithm on TCP sockets causing
+packets to be transmitted immediately with low latency,
+rather than waiting a short period of time in order
+to aggregate several packets into a larger containing
+packet.  In VPN applications over TCP, TCP_NODELAY
+is generally a good latency optimization.
+
+The macro expands as follows:
+
+.RS
+.ft 3
+.nf
+.sp
+ if mode server:
+   socket-flags TCP_NODELAY
+   push "socket-flags TCP_NODELAY"
+.ft
+.LP
+.RE
+.fi
+.\"*********************************************************
+.TP
 .B --max-clients n
 Limit server to a maximum of
 .B n
diff --git a/options.c b/options.c
index 33234c5..44f12a1 100644
--- a/options.c
+++ b/options.c
@@ -402,6 +402,8 @@ static const char usage_message[] =
   "                  virtual address table to v.\n"
   "--bcast-buffers n : Allocate n broadcast buffers.\n"
   "--tcp-queue-limit n : Maximum number of queued TCP output packets.\n"
+  "--tcp-nodelay   : Macro that sets TCP_NODELAY socket flag on the server\n"
+  "                  as well as pushes it to connecting clients.\n"
   "--learn-address cmd : Run script cmd to validate client virtual addresses.\n"
   "--connect-freq n s : Allow a maximum of n new connections per s seconds.\n"
   "--max-clients n : Allow a maximum of n simultaneously connected clients.\n"
@@ -1764,6 +1766,8 @@ options_postprocess_verify_ce (const struct options *options, const struct conne
 	msg (M_USAGE, "--no-name-remapping requires --mode server");
       if (options->ssl_flags & SSLF_OPT_VERIFY)
 	msg (M_USAGE, "--opt-verify requires --mode server");
+      if (options->server_flags & SF_TCP_NODELAY_HELPER)
+	msg (M_USAGE, "--tcp-nodelay requires --mode server");
       if (options->auth_user_pass_verify_script)
 	msg (M_USAGE, "--auth-user-pass-verify requires --mode server");
 #if PORT_SHARE
@@ -2065,6 +2069,7 @@ options_postprocess_mutate (struct options *o)
    */
   helper_client_server (o);
   helper_keepalive (o);
+  helper_tcp_nodelay (o);
 
   options_postprocess_mutate_invariant (o);
 
@@ -4797,6 +4802,11 @@ add_option (struct options *options,
       VERIFY_PERMISSION (OPT_P_INSTANCE);
       options->disable = true;
     }
+  else if (streq (p[0], "tcp-nodelay"))
+    {
+      VERIFY_PERMISSION (OPT_P_GENERAL);
+      options->server_flags |= SF_TCP_NODELAY_HELPER;
+    }
 #endif /* P2MP_SERVER */
 
   else if (streq (p[0], "client"))
diff --git a/options.h b/options.h
index 7ea4191..a7a0391 100644
--- a/options.h
+++ b/options.h
@@ -346,6 +346,7 @@ struct options
   in_addr_t server_netmask;
 
 # define SF_NOPOOL (1<<0)
+# define SF_TCP_NODELAY_HELPER (1<<1)
   unsigned int server_flags;
 
   bool server_bridge_proxy_dhcp;
-- 
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