From 3bac586a043ca1ba576229541a0a6dde91f3652a Mon Sep 17 00:00:00 2001
From: Keith Winstein <keithw@mit.edu>
Date: Sat, 13 Aug 2011 19:33:56 -0400
Subject: [PATCH] Use temporary socket for path MTU discovery

---
 Makefile    |  2 +-
 network.cpp | 25 +++++++++++++++----------
 stm.cpp     |  3 ++-
 3 files changed, 18 insertions(+), 12 deletions(-)

diff --git a/Makefile b/Makefile
index e6f5f06..2ec10b8 100644
--- a/Makefile
+++ b/Makefile
@@ -5,7 +5,7 @@ repos = templates.rpo
 executables = parse termemu ntester encrypt decrypt stm-server stm
 
 CXX = g++
-CXXFLAGS = -g -O2 --std=c++0x -pedantic -Werror -Wall -Wextra -Weffc++ -fno-implicit-templates -fno-default-inline -pipe -D_FILE_OFFSET_BITS=64 -D_XOPEN_SOURCE=500 -D_GNU_SOURCE -D_BSD_SOURCE
+CXXFLAGS = -g --std=c++0x -pedantic -Werror -Wall -Wextra -Weffc++ -fno-implicit-templates -fno-default-inline -pipe -D_FILE_OFFSET_BITS=64 -D_XOPEN_SOURCE=500 -D_GNU_SOURCE -D_BSD_SOURCE
 LIBS = -lutil -lssl -lrt -lm -lprotobuf-lite
 PROTOC = protoc
 
diff --git a/network.cpp b/network.cpp
index d7f4afd..045370a 100644
--- a/network.cpp
+++ b/network.cpp
@@ -136,13 +136,23 @@ Connection::Connection( const char *key_str, const char *ip, int port ) /* clien
 
 void Connection::update_MTU( void )
 {
-  /* Temporarily connect socket so we can retrieve path MTU */
-  if ( connect( sock, (sockaddr *)&remote_addr, sizeof( remote_addr ) ) < 0 ) {
+  if ( !attached ) {
+    return;
+  }
+
+  /* We don't want to use our main socket because we don't want to have to connect it */
+  int path_MTU_socket = socket( AF_INET, SOCK_DGRAM, 0 );
+  if ( path_MTU_socket < 0 ) {
+    throw NetworkException( "socket", errno );
+  }
+
+  /* Connect socket so we can retrieve path MTU */
+  if ( connect( path_MTU_socket, (sockaddr *)&remote_addr, sizeof( remote_addr ) ) < 0 ) {
     throw NetworkException( "connect", errno );
   }
 
   socklen_t optlen = sizeof( MTU );
-  if ( getsockopt( sock, IPPROTO_IP, IP_MTU, &MTU, &optlen ) < 0 ) {
+  if ( getsockopt( path_MTU_socket, IPPROTO_IP, IP_MTU, &MTU, &optlen ) < 0 ) {
     throw NetworkException( "getsockopt", errno );
   }
 
@@ -150,14 +160,9 @@ void Connection::update_MTU( void )
     throw NetworkException( "Error getting path MTU", errno );
   }
 
-  /* Disconnect socket */
-  struct sockaddr disconnect;
-  disconnect.sa_family = AF_UNSPEC;
-
-  if ( connect( sock, (sockaddr *)&disconnect, sizeof( disconnect ) ) < 0 ) {
-    throw NetworkException( "connect", errno );
+  if ( close( path_MTU_socket ) < 0 ) {
+    throw NetworkException( "close", errno );
   }
-
 }
 
 void Connection::send( string &s, bool send_timestamp )
diff --git a/stm.cpp b/stm.cpp
index 14e73d8..6bf8d0a 100644
--- a/stm.cpp
+++ b/stm.cpp
@@ -180,7 +180,8 @@ void client( const char *ip, int port, const char *key )
 
     if ( (pollfds[ 0 ].revents | pollfds[ 1 ].revents)
 	 & (POLLERR | POLLHUP | POLLNVAL) ) {
-      break;
+      perror( "poll" );
+      //      break;
     }
   }
 }