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

webrtc/p2p/base/p2ptransportchannel.cc

Index: webrtc/p2p/base/p2ptransportchannel.cc
diff --git a/webrtc/p2p/base/p2ptransportchannel.cc b/webrtc/p2p/base/p2ptransportchannel.cc
index 5101bf341117c2cebafc14f5734c6f612fd857e8..504affbf2b3a751bdf4997b26ebbcab949cdf334 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()) {

[pthatcher1, 2015/12/28 21:33:59]

Can you put a TODO in candidate.h to change username() to either
usernameFragment() or ufrag()?  And, better yet, make a CL to do so?

[honghaiz3, 2015/12/30 18:59:33]

Added TODO... although I think there is no confusion there. A username/password
is perhaps more readable than ufrag/pwd for general people? 

[pthatcher1, 2015/12/30 19:15:44]

username() is more readable, but it's also wrong.  usernameFragment() is
correct.  I'd be happy with usernameFragment/password.  But on the other hand,
we use "ufrag" and "pwd" in all of the other code, and we should probably be
consistent.

Your TODO is sufficient for this CL.

+      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);
   }
 }
 
@@ -511,6 +516,7 @@ void P2PTransportChannel::OnUnknownAddress(
 
   const Candidate* candidate = NULL;
   std::string remote_password;
+  uint32_t remote_generation = 0;
   for (it = remote_candidates_.begin(); it != remote_candidates_.end(); ++it) {
     if (it->username() == remote_username) {
       remote_password = it->password();
@@ -529,9 +535,10 @@ void P2PTransportChannel::OnUnknownAddress(
   // 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 =
+        FindRemoteIce(remote_username, &remote_generation);
+    if (ice_param != nullptr) {
+      remote_password = ice_param->pwd;

[pthatcher1, 2015/12/28 21:33:59]

If the remote_username is empty (not signalled), do we want to continue to
assume it means the latest ufrag/pwd?  If we don't, this is a behavior changes
which might break things.

[honghaiz3, 2015/12/30 18:59:33]

If the remote_username is not signalled, remote ufrag and pwd will be empty in
both cases, right. The behavior should not matter. 
Plus, in a stun request, the ufrag should never be empty, right?

[pthatcher1, 2015/12/30 19:15:44]

Sorry, when I said "not signalled", I meant "not signalled on the candidate". 
But looking at this more closely, I see that my comment was wrong.  This is
covering the case where we know the remote ufrag from a STUN ping and are
filling in the password.  So, your code looks good here.  Forget my previous
comment.

     }
   }
 
@@ -564,9 +571,9 @@ 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 +633,22 @@ void P2PTransportChannel::OnRoleConflict(PortInterface* port) {
                              // from Transport.
 }
 
+const IceParameters* P2PTransportChannel::FindRemoteIce(
+    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()) {
+    // If not found, assume the next (future) generation.
+    *generation = static_cast<uint32_t>(params.size());

[pthatcher1, 2015/12/28 21:33:59]

I find it a bit confusing that we fill in the generation even when the
generation isn't found.  That's a little too magic/implicit.  Can we instead of
the caller explicitly use remote_ice_parameters_.size() when a generation isn't
found?

[honghaiz3, 2015/12/30 18:59:33]

Done.

+    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 +811,11 @@ 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 contains ufrag, use that to find the generation.

[pthatcher1, 2015/12/28 21:33:59]

contains ufrag => has a ufrag
use that => use it

[honghaiz3, 2015/12/30 18:59:33]

Done.

   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());
-    }
-    return params.rend() - it - 1;
+    uint32_t generation = 0;
+    FindRemoteIce(candidate.username(), &generation);
+    return generation;
   }
   // If candidate generation is set, use that.
   if (candidate.generation() > 0) {