Relanding: Move "max IPv6 networks" logic to BasicPortAllocator, and fix sorting.

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 85 matching lines @@
   MAX_VALUE
 };
 
 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;
 
+// Turning on IPv6 could make many IPv6 interfaces available for connectivity
+// check and delay the call setup time. kDefaultMaxIPv6Networks is the default
+// upper limit of IPv6 networks but could be changed by
+// set_max_ipv6_networks().
+constexpr int kDefaultMaxIPv6Networks = 5;
+
 // CF = CANDIDATE FILTER
 enum {
   CF_NONE = 0x0,
   CF_HOST = 0x1,
   CF_REFLEXIVE = 0x2,
   CF_RELAY = 0x4,
   CF_ALL = 0x7,
 };
 
 // TLS certificate policy.
@@ skipping 201 matching lines @@
 };
 
 // Every method of PortAllocator (including the destructor) must be called on
 // the same thread, except for the constructor which may be called on any
 // thread.
 //
 // This allows constructing a PortAllocator subclass on one thread and
 // passing it into an object that uses it on a different thread.
 class PortAllocator : public sigslot::has_slots<> {
  public:
-  PortAllocator() :
-      flags_(kDefaultPortAllocatorFlags),
-      min_port_(0),
-      max_port_(0),
-      step_delay_(kDefaultStepDelay),
-      allow_tcp_listen_(true),
-      candidate_filter_(CF_ALL) {
-  }
+  PortAllocator()
+      : flags_(kDefaultPortAllocatorFlags),
+        min_port_(0),
+        max_port_(0),
+        max_ipv6_networks_(kDefaultMaxIPv6Networks),
+        step_delay_(kDefaultStepDelay),
+        allow_tcp_listen_(true),
+        candidate_filter_(CF_ALL) {}
 
   virtual ~PortAllocator() {}
 
   // This should be called on the PortAllocator's thread before the
   // PortAllocator is used. Subclasses may override this if necessary.
   virtual void Initialize() {}
 
   // Set STUN and TURN servers to be used in future sessions, and set
   // candidate pool size, as described in JSEP.
   //
@@ skipping 77 matching lines @@
   bool SetPortRange(int min_port, int max_port) {
     if (min_port > max_port) {
       return false;
     }
 
     min_port_ = min_port;
     max_port_ = max_port;
     return true;
   }
 
+  // Can be used to change the default numer of IPv6 network interfaces used
+  // (5). Can set to INT_MAX to effectively disable the limit.
+  //
+  // TODO(deadbeef): Applications shouldn't have to arbitrarily limit the
+  // number of available IPv6 network interfaces just because they could slow
+  // ICE down. We should work on making our ICE logic smarter (for example,
+  // prioritizing pinging connections that are most likely to work) so that
+  // every network interface can be used without impacting ICE's speed.
+  void set_max_ipv6_networks(int networks) { max_ipv6_networks_ = networks; }
+  int max_ipv6_networks() { return max_ipv6_networks_; }
+
   uint32_t step_delay() const { return step_delay_; }
   void set_step_delay(uint32_t delay) { step_delay_ = delay; }
 
   bool allow_tcp_listen() const { return allow_tcp_listen_; }
   void set_allow_tcp_listen(bool allow_tcp_listen) {
     allow_tcp_listen_ = allow_tcp_listen;
   }
 
   uint32_t candidate_filter() { return candidate_filter_; }
   void set_candidate_filter(uint32_t filter) {
@@ skipping 23 matching lines @@
 
   const std::deque<std::unique_ptr<PortAllocatorSession>>& pooled_sessions() {
     return pooled_sessions_;
   }
 
   uint32_t flags_;
   std::string agent_;
   rtc::ProxyInfo proxy_;
   int min_port_;
   int max_port_;
+  int max_ipv6_networks_;
   uint32_t step_delay_;
   bool allow_tcp_listen_;
   uint32_t candidate_filter_;
   std::string origin_;
 
  private:
   ServerAddresses stun_servers_;
   std::vector<RelayServerConfig> turn_servers_;
   int candidate_pool_size_ = 0;  // Last value passed into SetConfiguration.
   std::deque<std::unique_ptr<PortAllocatorSession>> pooled_sessions_;
   bool candidate_pool_frozen_ = false;
   bool prune_turn_ports_ = false;
 
   webrtc::MetricsObserverInterface* metrics_observer_ = nullptr;
 };
 
 }  // namespace cricket
 
 #endif  // WEBRTC_P2P_BASE_PORTALLOCATOR_H_