Allow p2p UDP packages to set DSCP

content/browser/renderer_host/p2p/socket_host_udp.cc

Index: content/browser/renderer_host/p2p/socket_host_udp.cc
diff --git a/content/browser/renderer_host/p2p/socket_host_udp.cc b/content/browser/renderer_host/p2p/socket_host_udp.cc
index bcfb282a2c42c52b3bf34de53a68ed25c05f2402..52ca71b01493d950c792e180427dce6ee9d81c00 100644
--- a/content/browser/renderer_host/p2p/socket_host_udp.cc
+++ b/content/browser/renderer_host/p2p/socket_host_udp.cc
@@ -50,11 +50,15 @@ uint64 GetUniqueEventId(const content::P2PSocketHostUdp* obj,
 namespace content {
 
 P2PSocketHostUdp::PendingPacket::PendingPacket(
-    const net::IPEndPoint& to, const std::vector<char>& content, uint64 id)
+    const net::IPEndPoint& to,
+    const std::vector<char>& content,
+    uint64 id,
+    net::DiffServCodePoint dscp_)
     : to(to),
       data(new net::IOBuffer(content.size())),
       size(content.size()),
-      id(id) {
+      id(id),
+      dscp(dscp_) {
   memcpy(data->data(), &content[0], size);
 }
 
@@ -65,7 +69,8 @@ P2PSocketHostUdp::P2PSocketHostUdp(IPC::Sender* message_sender, int id)
     : P2PSocketHost(message_sender, id),
       socket_(new net::UDPServerSocket(NULL, net::NetLog::Source())),
       send_pending_(false),
-      send_packet_count_(0) {
+      send_packet_count_(0),
+      last_dscp_(net::DSCP_CS0) {
 }
 
 P2PSocketHostUdp::~P2PSocketHostUdp() {
@@ -164,7 +169,8 @@ void P2PSocketHostUdp::HandleReadResult(int result) {
 }
 
 void P2PSocketHostUdp::Send(const net::IPEndPoint& to,
-                            const std::vector<char>& data) {
+                            const std::vector<char>& data,
+                            net::DiffServCodePoint dscp) {
   if (!socket_) {
     // The Send message may be sent after the an OnError message was
     // sent by hasn't been processed the renderer.
@@ -183,9 +189,9 @@ void P2PSocketHostUdp::Send(const net::IPEndPoint& to,
   }
 
   if (send_pending_) {
-    send_queue_.push_back(PendingPacket(to, data, send_packet_count_));
+    send_queue_.push_back(PendingPacket(to, data, send_packet_count_, dscp));
   } else {
-    PendingPacket packet(to, data, send_packet_count_);
+    PendingPacket packet(to, data, send_packet_count_, dscp);
     DoSend(packet);
   }
   ++send_packet_count_;
@@ -195,6 +201,17 @@ void P2PSocketHostUdp::DoSend(const PendingPacket& packet) {
   TRACE_EVENT_ASYNC_BEGIN1("p2p", "Udp::DoSend",
                            GetUniqueEventId(this, packet.id),
                            "size", packet.size);
+  if (last_dscp_ != packet.dscp && last_dscp_ != net::DSCP_NO_CHANGE) {
+    int result = socket_->SetToS(packet.dscp);
+    if (result == net::OK) {
+      last_dscp_ = packet.dscp;
+    } else if (!IsTransientError(result) && last_dscp_ != net::DSCP_CS0) {

[Sergey Ulanov, 2013/08/17 05:50:04]

IsTransientError() is used for errors returned from SendTo(). Why do we need it
here?

[hubbe, 2013/08/21 18:51:36]

On some platforms setsockopt() IP_TOS is a privileged operation. The idea is
that if setsockopt() fails permanently, we want to stop calling it. Since SetToS
returns errors of the same type as SendTo(), it seems reasonable to use the same
function.

+      // We receieved a non-transient error, and it seems we have
+      // not changed the DSCP in the past, disable DSCP as it unlikely
+      // to work in the future.
+      last_dscp_ = net::DSCP_NO_CHANGE;
+    }
+  }
   int result = socket_->SendTo(
       packet.data.get(),
       packet.size,