added option to control TOS byte in peer traffic

docs/manual.html

@@ -2612,6 +2612,7 @@ struct session_settings
         int cache_size;
         int cache_expiry;
         std::pair<int, int> outgoing_ports;
+        char peer_tos;
 };
 </pre>
 <p><tt class="docutils literal"><span class="pre">user_agent</span></tt> this is the client identification to the tracker.
@@ -2768,6 +2769,10 @@ used to bind outgoing sockets to. This may be useful for users whose router
 allows them to assign QoS classes to traffic based on its local port. It is
 a range instead of a single port because of the problems with failing to reconnect
 to peers if a previous socket to that peer and port is in <tt class="docutils literal"><span class="pre">TIME_WAIT</span></tt> state.</p>
+<p><tt class="docutils literal"><span class="pre">peer_tos</span></tt> determines the TOS byte set in the IP header of every packet
+sent to peers (including web seeds). The default value for this is <tt class="docutils literal"><span class="pre">0x0</span></tt>
+(no marking). One potentially useful TOS mark is <tt class="docutils literal"><span class="pre">0x20</span></tt>, this represents
+the <em>QBone scavenger service</em>. For more details, see <a class="reference" href="http://qbone.internet2.edu/qbss/">QBSS</a>.</p>
 </div>
 <div class="section">
 <h1><a id="pe-settings" name="pe-settings">pe_settings</a></h1>

docs/manual.rst

@@ -2605,6 +2605,7 @@ that will be sent to the tracker. The user-agent is a good way to identify your
 		int cache_size;
 		int cache_expiry;
 		std::pair<int, int> outgoing_ports;
+		char peer_tos;
 	};
 
 ``user_agent`` this is the client identification to the tracker.
@@ -2800,6 +2801,13 @@ allows them to assign QoS classes to traffic based on its local port. It is
 a range instead of a single port because of the problems with failing to reconnect
 to peers if a previous socket to that peer and port is in ``TIME_WAIT`` state.
 
+``peer_tos`` determines the TOS byte set in the IP header of every packet
+sent to peers (including web seeds). The default value for this is ``0x0``
+(no marking). One potentially useful TOS mark is ``0x20``, this represents
+the *QBone scavenger service*. For more details, see QBSS_.
+
+.. _`QBSS`: http://qbone.internet2.edu/qbss/
+
 
 pe_settings
 ===========

include/libtorrent/proxy_base.hpp

@@ -101,6 +101,20 @@ public:
 		m_sock.async_write_some(buffers, handler);
 	}
 
+#ifndef BOOST_NO_EXCEPTIONS
+	template <class SettableSocketOption>
+	void set_option(SettableSocketOption const& opt)
+	{
+		m_sock.set_option(opt);
+	}
+#endif
+
+	template <class SettableSocketOption>
+	asio::error_code set_option(SettableSocketOption const& opt, asio::error_code& ec)
+	{
+		return m_sock.set_option(opt, ec);
+	}
+
 #ifndef BOOST_NO_EXCEPTIONS
 	void bind(endpoint_type const& endpoint)
 	{

include/libtorrent/session_settings.hpp

@@ -127,6 +127,7 @@ namespace libtorrent
 			, cache_size(512)
 			, cache_expiry(60)
 			, outgoing_ports(0,0)
+			, peer_tos(0)
 		{}
 
 		// this is the user agent that will be sent to the tracker
@@ -339,6 +340,13 @@ namespace libtorrent
 		// is useful for users that have routers that
 		// allow QoS settings based on local port.
 		std::pair<int, int> outgoing_ports;
+
+		// the TOS byte of all peer traffic (including
+		// web seeds) is set to this value. The default
+		// is the QBSS scavenger service
+		// http://qbone.internet2.edu/qbss/
+		// For unmarked packets, set to 0
+		char peer_tos;
 	};
 	
 #ifndef TORRENT_DISABLE_DHT

include/libtorrent/socket.hpp

@@ -185,6 +185,19 @@ namespace libtorrent
 		int m_value;
 	};
 	
+	struct type_of_service
+	{
+		type_of_service(char val): m_value(val) {}
+		template<class Protocol>
+		int level(Protocol const&) const { return IPPROTO_IP; }
+		template<class Protocol>
+		int name(Protocol const&) const { return IP_TOS; }
+		template<class Protocol>
+		char const* data(Protocol const&) const { return &m_value; }
+		template<class Protocol>
+		size_t size(Protocol const&) const { return sizeof(m_value); }
+		char m_value;
+	};
 }
 
 #endif // TORRENT_SOCKET_HPP_INCLUDED

include/libtorrent/variant_stream.hpp

@@ -256,6 +256,45 @@ namespace aux
       { return EndpointType(); }
   };
 
+// -------------- set_option -----------
+
+  template <class SettableSocketOption>
+  struct set_option_visitor
+    : boost::static_visitor<>
+  {
+      set_option_visitor(SettableSocketOption const& opt)
+        : opt_(opt)
+      {}
+
+      template <class T>
+      void operator()(T* p) const
+      { p->set_option(opt_); }
+
+		std::size_t operator()(boost::blank) const {}
+
+      SettableSocketOption const& opt_;
+  };
+
+  template <class SettableSocketOption>
+  struct set_option_visitor_ec
+    : boost::static_visitor<asio::error_code>
+  {
+      set_option_visitor_ec(SettableSocketOption const& opt, asio::error_code& ec)
+        : opt_(opt)
+        , ec_(ec)
+      {}
+
+      template <class T>
+      asio::error_code operator()(T* p) const
+      { return p->set_option(opt_, ec_); }
+
+		asio::error_code operator()(boost::blank) const
+      { return ec_; }
+
+      SettableSocketOption const& opt_;
+      asio::error_code& ec_;
+  };
+
 // -------------- local_endpoint -----------
 
   template <class EndpointType>
@@ -657,6 +696,22 @@ public:
         );
     }
 
+    template <class SettableSocketOption>
+    void set_option(SettableSocketOption const& opt)
+    {
+        TORRENT_ASSERT(instantiated());
+        boost::apply_visitor(aux::set_option_visitor<SettableSocketOption>(opt)
+            , m_variant);
+    }
+
+    template <class SettableSocketOption>
+    asio::error_code set_option(SettableSocketOption const& opt, asio::error_code& ec)
+    {
+        TORRENT_ASSERT(instantiated());
+        return boost::apply_visitor(aux::set_option_visitor_ec<SettableSocketOption>(opt, ec)
+            , m_variant);
+    }
+	 
     endpoint_type local_endpoint() const
     {
         TORRENT_ASSERT(instantiated());

src/peer_connection.cpp

@@ -235,6 +235,9 @@ namespace libtorrent
 		(*m_logger) << "*** INCOMING CONNECTION\n";
 #endif
 		
+		if (m_remote.address().is_v4())
+			m_socket->set_option(type_of_service(ses.settings().peer_tos), ec);
+
 #ifndef NDEBUG
 		piece_failed = false;
 #endif
@@ -3011,6 +3014,12 @@ namespace libtorrent
 			<< " rtt = " << m_rtt << "\n";
 #endif
 
+		if (m_remote.address().is_v4())
+		{
+			asio::error_code ec;
+			m_socket->set_option(type_of_service(m_ses.settings().peer_tos), ec);
+		}
+
 		on_connected();
 		setup_send();
 		setup_receive();