Fill the remote pwd in the ice candidates when an ICE credential is received.

Also when a STUN ping arrives from an unknown address, try to find the pwd and generation from the remote ICE parameters.

BUG=

Review URL: https://codereview.webrtc.org/1549633004

Cr-Commit-Position: refs/heads/master@{#11144}

4 files changed, 72 insertions, 24 deletions

diff --git a/webrtc/p2p/base/candidate.h b/webrtc/p2p/base/candidate.h
index 3f0ea43cde..ac7acabf05 100644
--- a/webrtc/p2p/base/candidate.h
+++ b/webrtc/p2p/base/candidate.h
@@ -105,6 +105,7 @@ class Candidate {
         std::min(prio_val, static_cast<uint64_t>(UINT_MAX)));
   }
 
+  // TODO(honghaiz): Change to usernameFragment or ufrag.
   const std::string & username() const { return username_; }
   void set_username(const std::string & username) { username_ = username; }
 
diff --git a/webrtc/p2p/base/p2ptransportchannel.cc b/webrtc/p2p/base/p2ptransportchannel.cc
index 5101bf3411..c58a235f2d 100644
--- a/webrtc/p2p/base/p2ptransportchannel.cc
+++ b/webrtc/p2p/base/p2ptransportchannel.cc
@@ -354,10 +354,15 @@ void P2PTransportChannel::SetRemoteIceCredentials(const std::string& ice_ufrag,
     remote_ice_parameters_.push_back(new_ice);
   }
 
+  // Update the pwd of remote candidate if needed.
+  for (RemoteCandidate& candidate : remote_candidates_) {
+    if (candidate.username() == ice_ufrag && candidate.password().empty()) {
+      candidate.set_password(ice_pwd);
+    }
+  }
   // We need to update the credentials for any peer reflexive candidates.
-  std::vector<Connection*>::iterator it = connections_.begin();
-  for (; it != connections_.end(); ++it) {
-    (*it)->MaybeSetRemoteIceCredentials(ice_ufrag, ice_pwd);
+  for (Connection* conn : connections_) {
+    conn->MaybeSetRemoteIceCredentials(ice_ufrag, ice_pwd);
   }
 }
 
@@ -525,13 +530,16 @@ void P2PTransportChannel::OnUnknownAddress(
     }
   }
 
+  uint32_t remote_generation = 0;
   // The STUN binding request may arrive after setRemoteDescription and before
   // adding remote candidate, so we need to set the password to the shared
   // password if the user name matches.
   if (remote_password.empty()) {
-    IceParameters* current_ice = remote_ice();
-    if (current_ice && remote_username == current_ice->ufrag) {
-      remote_password = current_ice->pwd;
+    const IceParameters* ice_param =
+        FindRemoteIceFromUfrag(remote_username, &remote_generation);
+    // Note: if not found, the remote_generation will still be 0.
+    if (ice_param != nullptr) {
+      remote_password = ice_param->pwd;
     }
   }
 
@@ -564,9 +572,9 @@ void P2PTransportChannel::OnUnknownAddress(
     // If the source transport address of the request does not match any
     // existing remote candidates, it represents a new peer reflexive remote
     // candidate.
-    remote_candidate =
-        Candidate(component(), ProtoToString(proto), address, 0,
-                  remote_username, remote_password, PRFLX_PORT_TYPE, 0U, "");
+    remote_candidate = Candidate(component(), ProtoToString(proto), address, 0,
+                                 remote_username, remote_password,
+                                 PRFLX_PORT_TYPE, remote_generation, "");
 
     // From RFC 5245, section-7.2.1.3:
     // The foundation of the candidate is set to an arbitrary value, different
@@ -626,6 +634,21 @@ void P2PTransportChannel::OnRoleConflict(PortInterface* port) {
                              // from Transport.
 }
 
+const IceParameters* P2PTransportChannel::FindRemoteIceFromUfrag(
+    const std::string& ufrag,
+    uint32_t* generation) {
+  const auto& params = remote_ice_parameters_;
+  auto it = std::find_if(
+      params.rbegin(), params.rend(),
+      [ufrag](const IceParameters& param) { return param.ufrag == ufrag; });
+  if (it == params.rend()) {
+    // Not found.
+    return nullptr;
+  }
+  *generation = params.rend() - it - 1;
+  return &(*it);
+}
+
 void P2PTransportChannel::OnNominated(Connection* conn) {
   ASSERT(worker_thread_ == rtc::Thread::Current());
   ASSERT(ice_role_ == ICEROLE_CONTROLLED);
@@ -788,22 +811,14 @@ bool P2PTransportChannel::FindConnection(
 
 uint32_t P2PTransportChannel::GetRemoteCandidateGeneration(
     const Candidate& candidate) {
-  // We need to keep track of the remote ice restart so newer
-  // connections are prioritized over the older.
-  const auto& params = remote_ice_parameters_;
+  // If the candidate has a ufrag, use it to find the generation.
   if (!candidate.username().empty()) {
-    // If remote side sets the ufrag, we use that to determine the candidate
-    // generation.
-    // Search backward as it is more likely to find it near the end.
-    auto it = std::find_if(params.rbegin(), params.rend(),
-                           [candidate](const IceParameters& param) {
-                             return param.ufrag == candidate.username();
-                           });
-    if (it == params.rend()) {
-      // If not found, assume it is the next (future) generation.
-      return static_cast<uint32_t>(remote_ice_parameters_.size());
+    uint32_t generation = 0;
+    if (!FindRemoteIceFromUfrag(candidate.username(), &generation)) {
+      // If the ufrag is not found, assume the next/future generation.
+      generation = static_cast<uint32_t>(remote_ice_parameters_.size());
     }
-    return params.rend() - it - 1;
+    return generation;
   }
   // If candidate generation is set, use that.
   if (candidate.generation() > 0) {
diff --git a/webrtc/p2p/base/p2ptransportchannel.h b/webrtc/p2p/base/p2ptransportchannel.h
index 92c0534e7c..3927b17659 100644
--- a/webrtc/p2p/base/p2ptransportchannel.h
+++ b/webrtc/p2p/base/p2ptransportchannel.h
@@ -178,6 +178,11 @@ class P2PTransportChannel : public TransportChannelImpl,
     return allocator_sessions_.back();
   }
 
+  // Public for unit tests.
+  const std::vector<RemoteCandidate>& remote_candidates() const {
+    return remote_candidates_;
+  }
+
  private:
   rtc::Thread* thread() { return worker_thread_; }
   bool IsGettingPorts() { return allocator_session()->IsGettingPorts(); }
@@ -247,6 +252,10 @@ class P2PTransportChannel : public TransportChannelImpl,
     return remote_ice_parameters_.empty() ? nullptr
                                           : &remote_ice_parameters_.back();
   }
+  // Returns the remote IceParameters and generation that match |ufrag|
+  // if found, and returns nullptr otherwise.
+  const IceParameters* FindRemoteIceFromUfrag(const std::string& ufrag,
+                                              uint32_t* generation);
   // Returns the index of the latest remote ICE parameters, or 0 if no remote
   // ICE parameters have been received.
   uint32_t remote_ice_generation() {
diff --git a/webrtc/p2p/base/p2ptransportchannel_unittest.cc b/webrtc/p2p/base/p2ptransportchannel_unittest.cc
index 9f40c46fdb..90ddd43714 100644
--- a/webrtc/p2p/base/p2ptransportchannel_unittest.cc
+++ b/webrtc/p2p/base/p2ptransportchannel_unittest.cc
@@ -1901,6 +1901,17 @@ TEST_F(P2PTransportChannelPingTest, TestAddRemoteCandidateWithVariousUfrags) {
   const cricket::Candidate& new_candidate = conn3->remote_candidate();
   EXPECT_EQ(kIcePwd[2], new_candidate.password());
   EXPECT_EQ(1U, new_candidate.generation());
+
+  // Check that the pwd of all remote candidates are properly assigned.
+  for (const cricket::RemoteCandidate& candidate : ch.remote_candidates()) {
+    EXPECT_TRUE(candidate.username() == kIceUfrag[1] ||
+                candidate.username() == kIceUfrag[2]);
+    if (candidate.username() == kIceUfrag[1]) {
+      EXPECT_EQ(kIcePwd[1], candidate.password());
+    } else if (candidate.username() == kIceUfrag[2]) {
+      EXPECT_EQ(kIcePwd[2], candidate.password());
+    }
+  }
 }
 
 TEST_F(P2PTransportChannelPingTest, ConnectionResurrection) {
@@ -2040,7 +2051,7 @@ TEST_F(P2PTransportChannelPingTest, TestSelectConnectionBeforeNomination) {
 // on requests from an unknown address before the controlling side nominates
 // a connection, and will nominate a connection from an unknown address if the
 // request contains the use_candidate attribute. Plus, it will also sends back
-// a ping response.
+// a ping response and set the ICE pwd in the remote candidate appropriately.
 TEST_F(P2PTransportChannelPingTest, TestSelectConnectionFromUnknownAddress) {
   cricket::FakePortAllocator pa(rtc::Thread::Current(), nullptr);
   cricket::P2PTransportChannel ch("receiving state change", 1, nullptr, &pa);
@@ -2105,6 +2116,18 @@ TEST_F(P2PTransportChannelPingTest, TestSelectConnectionFromUnknownAddress) {
   EXPECT_EQ(conn2, ch.best_connection());
   conn4->ReceivedPingResponse();  // Become writable.
   EXPECT_EQ(conn4, ch.best_connection());
+
+  // Test that the request from an unknown address contains a ufrag from an old
+  // generation.
+  port->set_sent_binding_response(false);
+  ch.SetRemoteIceCredentials(kIceUfrag[2], kIcePwd[2]);
+  ch.SetRemoteIceCredentials(kIceUfrag[3], kIcePwd[3]);
+  port->SignalUnknownAddress(port, rtc::SocketAddress("5.5.5.5", 5),
+                             cricket::PROTO_UDP, &request, kIceUfrag[2], false);
+  cricket::Connection* conn5 = WaitForConnectionTo(&ch, "5.5.5.5", 5);
+  ASSERT_TRUE(conn5 != nullptr);
+  EXPECT_TRUE(port->sent_binding_response());
+  EXPECT_EQ(kIcePwd[2], conn5->remote_candidate().password());
 }
 
 // The controlled side will select a connection as the "best connection"