Allow p2p UDP packages to set DSCP

net/udp/udp_socket_win.cc

Index: net/udp/udp_socket_win.cc
diff --git a/net/udp/udp_socket_win.cc b/net/udp/udp_socket_win.cc
index 1f0c337fd4a609fcb783bb0382345a88ab4ecd34..3f3e13b93a2c58186f408538927f96704456dfdf 100644
--- a/net/udp/udp_socket_win.cc
+++ b/net/udp/udp_socket_win.cc
@@ -166,6 +166,7 @@ UDPSocketWin::UDPSocketWin(DatagramSocket::BindType bind_type,
       addr_family_(0),
       socket_options_(SOCKET_OPTION_MULTICAST_LOOP),
       multicast_time_to_live_(1),
+      dscp_(DSCP_CS0),
       bind_type_(bind_type),
       rand_int_cb_(rand_int_cb),
       recv_from_address_(NULL),
@@ -621,6 +622,22 @@ int UDPSocketWin::SetSocketOptions() {
     if (rv < 0)
       return MapSystemError(WSAGetLastError());
   }
+  if (dscp_) {
+    int rw;
+    DWORD dscp_and_ecn = dscp_ << 2;
+    if (addr_family_ == AF_INET) {
+      rv = setsockopt(socket_, IPPROTO_IP, IP_TOS,
+                      reinterpret_cast<const char*>(&dscp_and_ecn),
+                      sizeof(dscp_and_ecn));
+    } else {
+      rv = setsockopt(socket_, IPPROTO_IPV6, IPV6_TCLASS,
+                      reinterpret_cast<const char*>(&dscp_and_ecn),
+                      sizeof(dscp_and_ecn));
+    }
+    if (rv < 0) {
+      LOG(INFO) << "Failed to set dscp, errno=" << errno;
+    }
+  }
   return OK;
 }