Add a flag to filter out high-cost networks.

webrtc/p2p/base/portallocator.h

 /*
  *  Copyright 2004 The WebRTC Project Authors. All rights reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 42 matching lines @@
   // interface as seen by regular http traffic and the HOST candidate associated
   // with the default local interface.
   PORTALLOCATOR_DISABLE_ADAPTER_ENUMERATION = 0x400,
   // When specified along with PORTALLOCATOR_DISABLE_ADAPTER_ENUMERATION, the
   // default local candidate mentioned above will not be allocated. Only the
   // STUN candidate will be.
   PORTALLOCATOR_DISABLE_DEFAULT_LOCAL_CANDIDATE = 0x800,
   // Disallow use of UDP when connecting to a relay server. Since proxy servers
   // usually don't handle UDP, using UDP will leak the IP address.
   PORTALLOCATOR_DISABLE_UDP_RELAY = 0x1000,
+
+  // When multiple networks exist, do not gather candidates on the ones with
+  // high cost. So if both Wi-Fi and cellular networks exist, gather only on the
+  // Wi-Fi network. If a network type is "unknown", it has a cost lower than
+  // cellular but higher than Wi-Fi/Ethernet. So if an unknown network exists,
+  // cellular networks will not be used to gather candidates and if a Wi-Fi
+  // network is present, "unknown" networks will not be usd to gather
+  // candidates. Doing so ensures that even if a cellular network type was not
+  // detected initially, it would not be used if a Wi-Fi network is present.
+  PORTALLOCATOR_DISABLE_COSTLY_NETWORKS = 0x2000,
 };
 
 const uint32_t kDefaultPortAllocatorFlags = 0;
 
 const uint32_t kDefaultStepDelay = 1000;  // 1 sec step delay.
 // As per RFC 5245 Appendix B.1, STUN transactions need to be paced at certain
 // internal. Less than 20ms is not acceptable. We choose 50ms as our default.
 const uint32_t kMinimumStepDelay = 50;
 
 // CF = CANDIDATE FILTER
@@ skipping 265 matching lines @@
   int target_pooled_session_count_ = 0;
   // This variable represents the total number of pooled sessions
   // both owned by this class and taken by TakePooledSession.
   int allocated_pooled_session_count_ = 0;
   std::deque<std::unique_ptr<PortAllocatorSession>> pooled_sessions_;
 };
 
 }  // namespace cricket
 
 #endif  // WEBRTC_P2P_BASE_PORTALLOCATOR_H_