Added option for using TCP_DEFER_ACCEPT. Prevents the connection from being handed over to the daemon before data is ready from the client.

5 files changed, 101 insertions, 0 deletions

diff --git a/configure b/configure
index ccb487372..5a0bbd4e9 100755
--- a/configure
+++ b/configure
@@ -346,6 +346,18 @@ if (test_file($config{CC}, "eventfd.cpp")) {
 	print "no\n";
 }
 
+printf "Checking if a TCP deferring mechanism is available... ";
+if (test_file($config{CC}, "tcp_defer_accept.cpp")) {
+	$config{HAS_DEFER} = "TCP_DEFER_ACCEPT";
+	print "yes (TCP_DEFER_ACCEPT)\n";
+} elsif (test_file($config{CC}, "so_acceptfilter.cpp")) {
+	$config{HAS_DEFER} = "SO_ACCEPTFILTER";
+	print "yes (SO_ACCEPTFILTER)\n";
+} else {
+	$config{HAS_DEFER} = "false";
+	print "no\n";
+}
+
 print "Checking whether epoll is available... ";
 $has_epoll = test_header($config{CC}, "sys/epoll.h");
 print $has_epoll ? "yes\n" : "no\n";
@@ -875,6 +887,13 @@ print FILEHANDLE "#define MAXBUF " . ($config{MAXBUF}+2) . "\n";
 				$config{SOCKETENGINE} = "socketengine_select";
 			}
 		}
+
+		if ($config{HAS_DEFER} eq "TCP_DEFER_ACCEPT") {
+			print FILEHANDLE "#define USE_TCP_DEFER_ACCEPT";
+		} elsif ($config{HAS_DEFER} eq "SO_ACCEPTFILTER") {
+			print FILEHANDLE "#define USE_SO_ACCEPTFILTER"
+		}
+
 		print FILEHANDLE "\n#include \"threadengines/threadengine_pthread.h\"\n";
 		close(FILEHANDLE);
 		
diff --git a/docs/conf/inspircd.conf.example b/docs/conf/inspircd.conf.example
index eeed82237..f6dc96ecd 100644
--- a/docs/conf/inspircd.conf.example
+++ b/docs/conf/inspircd.conf.example
@@ -164,6 +164,17 @@
       # for ssl to work. If you do not want this bind section to support ssl,
       # just remove or comment out this option.
       ssl="gnutls"
+
+      # defer: When this is non-zero, connections will not be handed over to
+      # the daemon from the operating system before data is ready.
+      # In Linux, the value indicates the number of seconds we'll wait for a
+      # connection to come up with data. Don't set it too low!
+      # In BSD the value is ignored; only zero and non-zero is possible.
+      # Windows ignores this parameter completely.
+      # Note: This does not take effect on rehash.
+      # To change it on a running bind, you'll have to comment it out,
+      # rehash, comment it in and rehash again.
+      defer="0"
 >
 
 <bind address="" port="6660-6669" type="clients">
diff --git a/make/test/so_acceptfilter.cpp b/make/test/so_acceptfilter.cpp
new file mode 100644
index 000000000..0fd4cda4f
--- /dev/null
+++ b/make/test/so_acceptfilter.cpp
@@ -0,0 +1,27 @@
+/*
+ * InspIRCd -- Internet Relay Chat Daemon
+ *
+ *
+ * This file is part of InspIRCd.  InspIRCd is free software: you can
+ * redistribute it and/or modify it under the terms of the GNU General Public
+ * License as published by the Free Software Foundation, version 2.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+ * FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more
+ * details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <sys/socket.h>
+
+#ifndef SO_ACCEPTFILTER
+	#error
+#endif
+
+int main()
+{
+	return 0;
+}
diff --git a/make/test/tcp_defer_accept.cpp b/make/test/tcp_defer_accept.cpp
new file mode 100644
index 000000000..191b1ac70
--- /dev/null
+++ b/make/test/tcp_defer_accept.cpp
@@ -0,0 +1,27 @@
+/*
+ * InspIRCd -- Internet Relay Chat Daemon
+ *
+ *
+ * This file is part of InspIRCd.  InspIRCd is free software: you can
+ * redistribute it and/or modify it under the terms of the GNU General Public
+ * License as published by the Free Software Foundation, version 2.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+ * FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more
+ * details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <netinet/tcp.h>
+
+#ifndef TCP_DEFER_ACCEPT
+	#error
+#endif
+
+int main()
+{
+	return 0;
+}
diff --git a/src/listensocket.cpp b/src/listensocket.cpp
index 466b91c8b..f875bc646 100644
--- a/src/listensocket.cpp
+++ b/src/listensocket.cpp
@@ -22,6 +22,10 @@
 #include "socket.h"
 #include "socketengine.h"
 
+#ifdef USE_TCP_DEFER_ACCEPT
+#include <netinet/tcp.h>
+#endif
+
 ListenSocket::ListenSocket(ConfigTag* tag, const irc::sockets::sockaddrs& bind_to)
 	: bind_tag(tag)
 {
@@ -38,6 +42,19 @@ ListenSocket::ListenSocket(ConfigTag* tag, const irc::sockets::sockaddrs& bind_t
 	if (rv >= 0)
 		rv = ServerInstance->SE->Listen(this->fd, ServerInstance->Config->MaxConn);
 
+	int timeout = tag->getInt("defer", 0);
+	if (timeout && !rv)
+	{
+#ifdef USE_TCP_DEFER_ACCEPT
+		setsockopt(fd, IPPROTO_TCP, TCP_DEFER_ACCEPT, &timeout, sizeof(timeout));
+#elif defined USE_SO_ACCEPTFILTER
+		struct accept_filter_arg afa;
+		memset(&afa, 0, sizeof(afa));
+		strcpy(afa.af_name, "dataready");
+		setsockopt(fd, SOL_SOCKET, SO_ACCEPTFILTER, &afa, sizeof(afa));
+#endif
+	}
+
 #ifdef IPV6_V6ONLY
 	/* This OS supports IPv6 sockets that can also listen for IPv4
 	 * connections. If our address is "*" or empty, enable both v4 and v6 to