From b84599f263b60ada4cc6f8ddb0b79031fc4e709f Mon Sep 17 00:00:00 2001
From: Keith Winstein <keithw@mit.edu>
Date: Wed, 3 Aug 2011 21:35:48 -0400
Subject: [PATCH] Correct path MTU discovery

---
 network.cpp | 16 +++++++++++-----
 network.hpp |  2 +-
 2 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/network.cpp b/network.cpp
index b5c71ab..60c928b 100644
--- a/network.cpp
+++ b/network.cpp
@@ -130,19 +130,25 @@ void Connection<Outgoing, Incoming>::client_connect( const char *ip, int port )
 }
 
 template <class Outgoing, class Incoming>
-void Connection<Outgoing, Incoming>::send( Outgoing &s )
+bool Connection<Outgoing, Incoming>::send( Outgoing &s )
 {
   assert( attached );
 
   string p = flow.new_packet( s ).tostring();
 
-  if ( sendto( sock, p.data(), p.size(), 0,
-	       (sockaddr *)&remote_addr, sizeof( remote_addr ) ) < 0 ) {
+  ssize_t bytes_sent = sendto( sock, p.data(), p.size(), 0,
+			       (sockaddr *)&remote_addr, sizeof( remote_addr ) );
+
+  if ( (bytes_sent < 0) && (errno == EMSGSIZE) ) {
+    update_MTU();
+    return false;
+  } else if ( bytes_sent == static_cast<int>( p.size() ) ) {
+    return true;
+  } else {
     perror( "sendto" );
     exit( 1 );
+    return false;
   }
-
-  update_MTU();
 }
 
 template <class Outgoing, class Incoming>
diff --git a/network.hpp b/network.hpp
index 26b7e78..3d1e2b7 100644
--- a/network.hpp
+++ b/network.hpp
@@ -78,7 +78,7 @@ namespace Network {
     Connection( bool s_server );
     
     void client_connect( const char *ip, int port );
-    void send( Outgoing &s );
+    bool send( Outgoing &s );
     Incoming recv( void );
     int fd( void ) { return sock; }
     int port( void );