Handle lifetime short than 2 minutes for TURN allocations

This patch modifies behaviour when TurnPort gets a lifetime
back from server that is shorter than 2 minutes.

Before the patch such lifetime resulted in TurnPort not scheduling any
refresh, leading to timeout on the turn allocation.

After then patch lifetime shorter then 2 minutes leads to refresh
after half stipulated lifetime.

BUG=webrtc:8826

Change-Id: I80561100f2307bd9a6a91af0924bb2814102ddd3
Reviewed-on: https://webrtc-review.googlesource.com/46741
Commit-Queue: Jonas Oreland <jonaso@webrtc.org>
Reviewed-by: Taylor Brandstetter <deadbeef@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#21891}

p2p/base/turnport.cc

@@ -976,15 +976,32 @@ void TurnPort::DispatchPacket(const char* data, size_t size,
   }
 }
 
-bool TurnPort::ScheduleRefresh(int lifetime) {
-  // Lifetime is in seconds; we schedule a refresh for one minute less.
+bool TurnPort::ScheduleRefresh(uint32_t lifetime) {
+  // Lifetime is in seconds, delay is in milliseconds.
+  int delay = 1 * 60 * 1000;
+
+  // Cutoff lifetime bigger than 1h.
+  constexpr uint32_t max_lifetime = 60 * 60;
+
   if (lifetime < 2 * 60) {
-    LOG_J(LS_WARNING, this) << "Received response with lifetime that was "
-                            << "too short, lifetime=" << lifetime;
-    return false;
+    // The RFC does not mention a lower limit on lifetime.
+    // So if server sends a value less than 2 minutes, we schedule a refresh
+    // for half lifetime.
+    LOG_J(LS_WARNING, this) << "Received response with short lifetime="
+                            << lifetime << " seconds.";
+    delay = (lifetime * 1000) / 2;
+  } else if (lifetime > max_lifetime) {
+    // Make 1 hour largest delay, and then sce
+    // we schedule a refresh for one minute less than max lifetime.
+    LOG_J(LS_WARNING, this) << "Received response with long lifetime="
+                            << lifetime << " seconds.";
+    delay = (max_lifetime - 60) * 1000;
+  } else {
+    // Normal case,
+    // we schedule a refresh for one minute less than requested lifetime.
+    delay = (lifetime - 60) * 1000;
   }
 
-  int delay = (lifetime - 60) * 1000;
   SendRequest(new TurnRefreshRequest(this), delay);
   LOG_J(LS_INFO, this) << "Scheduled refresh in " << delay << "ms.";
   return true;

p2p/base/turnport.h

@@ -260,7 +260,7 @@ class TurnPort : public Port {
       const rtc::SocketAddress& remote_addr,
       ProtocolType proto, const rtc::PacketTime& packet_time);
 
-  bool ScheduleRefresh(int lifetime);
+  bool ScheduleRefresh(uint32_t lifetime);
   void SendRequest(StunRequest* request, int delay);
   int Send(const void* data, size_t size,
            const rtc::PacketOptions& options);