Keep on sending stun binding requests on zero-cost networks.

webrtc/p2p/base/stunport.cc

 /*
  *  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.
  */
 
 #include "webrtc/p2p/base/stunport.h"
 
 #include "webrtc/p2p/base/common.h"
 #include "webrtc/p2p/base/portallocator.h"
 #include "webrtc/p2p/base/stun.h"
 #include "webrtc/base/checks.h"
 #include "webrtc/base/common.h"
 #include "webrtc/base/helpers.h"
 #include "webrtc/base/ipaddress.h"
 #include "webrtc/base/logging.h"
 #include "webrtc/base/nethelpers.h"
 
 namespace cricket {
 
 // TODO: Move these to a common place (used in relayport too)
 const int KEEPALIVE_DELAY = 10 * 1000;  // 10 seconds - sort timeouts
 const int RETRY_TIMEOUT = 50 * 1000;    // ICE says 50 secs
-// Stop sending STUN binding requests after this amount of time
-// (in milliseconds) because the connection binding requests should keep
-// the NAT binding alive.
-const int KEEP_ALIVE_TIMEOUT = 2 * 60 * 1000;  // 2 minutes
+const int KEEPALIVE_LIFETIME = 2 * 60 * 1000;  // 2 minutes

[pthatcher1, 2016/02/26 22:33:52]

This could use a comment explaining what it is.

Plus, isn't this now just value for high-cost networks?  So shouldn't it be:

HIGH_COST_STUN_PORT_KEEPALIVE_LIFETIME

?

[honghaiz3, 2016/02/29 19:34:11]

Done.

 
 // Handles a binding request sent to the STUN server.
 class StunBindingRequest : public StunRequest {
  public:
   StunBindingRequest(UDPPort* port,
                      const rtc::SocketAddress& addr,
-                     uint32_t deadline)
-      : port_(port), server_addr_(addr), deadline_(deadline) {
+                     int lifetime)
+      : port_(port), server_addr_(addr), lifetime_(lifetime) {
     start_time_ = rtc::Time();
   }
 
   virtual ~StunBindingRequest() {
   }
 
   const rtc::SocketAddress& server_addr() const { return server_addr_; }
 
   virtual void Prepare(StunMessage* request) override {
     request->SetType(STUN_BINDING_REQUEST);
   }
 
   virtual void OnResponse(StunMessage* response) override {
     const StunAddressAttribute* addr_attr =
         response->GetAddress(STUN_ATTR_MAPPED_ADDRESS);
     if (!addr_attr) {
       LOG(LS_ERROR) << "Binding response missing mapped address.";
     } else if (addr_attr->family() != STUN_ADDRESS_IPV4 &&
                addr_attr->family() != STUN_ADDRESS_IPV6) {
       LOG(LS_ERROR) << "Binding address has bad family";
     } else {
       rtc::SocketAddress addr(addr_attr->ipaddr(), addr_attr->port());
       port_->OnStunBindingRequestSucceeded(server_addr_, addr);
     }
 
     // We will do a keep-alive regardless of whether this request succeeds.
-    // It will be stopped after |deadline_| mostly to conserve the battery life.
-    if (rtc::Time() <= deadline_) {
+    // It will be stopped after its lifetime has passed (note that a negative
+    // lifetime indicates it will be sent indefinitely).
+    if (lifetime_ < 0 || rtc::TimeDiff(rtc::Time(), start_time_) <= lifetime_) {
       port_->requests_.SendDelayed(
-          new StunBindingRequest(port_, server_addr_, deadline_),
+          new StunBindingRequest(port_, server_addr_, lifetime_),
           port_->stun_keepalive_delay());
     }
   }
 
   virtual void OnErrorResponse(StunMessage* response) override {
     const StunErrorCodeAttribute* attr = response->GetErrorCode();
     if (!attr) {
       LOG(LS_ERROR) << "Bad allocate response error code";
     } else {
       LOG(LS_ERROR) << "Binding error response:"
                  << " class=" << attr->eclass()
                  << " number=" << attr->number()
                  << " reason='" << attr->reason() << "'";
     }
 
     port_->OnStunBindingOrResolveRequestFailed(server_addr_);
 
     uint32_t now = rtc::Time();
-    if (now <= deadline_ && rtc::TimeDiff(now, start_time_) <= RETRY_TIMEOUT) {
+    if ((lifetime_ < 0 || rtc::TimeDiff(now, start_time_) <= lifetime_) &&

[pthatcher1, 2016/02/26 22:33:52]

It seems like we could use a helper method of BeyondLifetime(now).

[honghaiz3, 2016/02/29 19:34:11]

Done, although this will lose the benefit of not requiring to evaluate
rtc::Time() if lifetime is infinite. 

+        rtc::TimeDiff(now, start_time_) <= RETRY_TIMEOUT) {
       port_->requests_.SendDelayed(
-          new StunBindingRequest(port_, server_addr_, deadline_),
+          new StunBindingRequest(port_, server_addr_, lifetime_),
           port_->stun_keepalive_delay());
     }
   }
 
   virtual void OnTimeout() override {
     LOG(LS_ERROR) << "Binding request timed out from "
       << port_->GetLocalAddress().ToSensitiveString()
       << " (" << port_->Network()->name() << ")";
 
     port_->OnStunBindingOrResolveRequestFailed(server_addr_);
   }
 
  private:
   UDPPort* port_;
   const rtc::SocketAddress server_addr_;
   uint32_t start_time_;
-  uint32_t deadline_;
+  // The time duration for which this request will be rescheduled.
+  // A negative value means this request will be rescheduled indefinitely.
+  int lifetime_;
 };
 
 UDPPort::AddressResolver::AddressResolver(
     rtc::PacketSocketFactory* factory)
     : socket_factory_(factory) {}
 
 UDPPort::AddressResolver::~AddressResolver() {
   for (ResolverMap::iterator it = resolvers_.begin();
        it != resolvers_.end(); ++it) {
     // TODO(guoweis): Change to asynchronous DNS resolution to prevent the hang
@@ skipping 272 matching lines @@
   }
 }
 
 void UDPPort::SendStunBindingRequest(const rtc::SocketAddress& stun_addr) {
   if (stun_addr.IsUnresolvedIP()) {
     ResolveStunAddress(stun_addr);
 
   } else if (socket_->GetState() == rtc::AsyncPacketSocket::STATE_BOUND) {
     // Check if |server_addr_| is compatible with the port's ip.
     if (IsCompatibleAddress(stun_addr)) {
-      requests_.Send(new StunBindingRequest(this, stun_addr,
-                                            rtc::Time() + KEEP_ALIVE_TIMEOUT));
+      // If this is a zero-cost network, it will keep on sending STUN binding
+      // requests indefinitely to keep the NAT binding alive. Otherwise,
+      // stop sending STUN binding requests after KEEPALIVE_LIFETIME.
+      int keepalive_lifetime = (network_cost() == 0) ? -1 : KEEPALIVE_LIFETIME;

[pthatcher1, 2016/02/26 22:33:52]

I think we should make a constant for UNLIMITED_LIFETIME to make this a bit more
readable.

You could use it above also as "if (lifetime_ <= UNLIMITED_LIFETIME)"

[honghaiz3, 2016/02/29 19:34:11]

Done. Used INIFINTE_LIFETIME. Also the logic changes to if (lifetime_ ==
INFINITE_LIFETIME || ....), which Looks more readable. 

+      requests_.Send(
+          new StunBindingRequest(this, stun_addr, keepalive_lifetime));
     } else {
       // Since we can't send stun messages to the server, we should mark this
       // port ready.
       LOG(LS_WARNING) << "STUN server address is incompatible.";
       OnStunBindingOrResolveRequestFailed(stun_addr);
     }
   }
 }
 
 bool UDPPort::MaybeSetDefaultLocalAddress(rtc::SocketAddress* addr) const {
@@ skipping 93 matching lines @@
   const std::vector<Candidate>& existing_candidates = Candidates();
   std::vector<Candidate>::const_iterator it = existing_candidates.begin();
   for (; it != existing_candidates.end(); ++it) {
     if (it->address() == addr)
       return true;
   }
   return false;
 }
 
 }  // namespace cricket