Allow remote fingerprint update during a call

webrtc/p2p/base/dtlstransportchannel.cc

 /*
  *  Copyright 2011 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 181 matching lines @@
 
   return dtls_->GetSslCipherSuite(cipher);
 }
 
 bool DtlsTransportChannelWrapper::SetRemoteFingerprint(
     const std::string& digest_alg,
     const uint8_t* digest,
     size_t digest_len) {
   rtc::Buffer remote_fingerprint_value(digest, digest_len);
 
+  // Once we have the local certificate, the same remote fingerprint can be set
+  // multiple times.
   if (dtls_active_ && remote_fingerprint_value_ == remote_fingerprint_value &&
       !digest_alg.empty()) {
     // This may happen during renegotiation.
     LOG_J(LS_INFO, this) << "Ignoring identical remote DTLS fingerprint";
     return true;
   }
 
-  // Allow SetRemoteFingerprint with a NULL digest even if SetLocalCertificate
-  // hasn't been called.
-  if (dtls_ || (!dtls_active_ && !digest_alg.empty())) {
-    LOG_J(LS_ERROR, this) << "Can't set DTLS remote settings in this state.";
-    return false;
-  }
-
+  // If the other side doesn't support DTLS, turn off |dtls_active_|.
   if (digest_alg.empty()) {
+    RTC_DCHECK(!digest_len);
     LOG_J(LS_INFO, this) << "Other side didn't support DTLS.";
     dtls_active_ = false;
     return true;
   }
 
+  // Otherwise, we must have a local certificate before setting remote
+  // fingerprint.
+  if (!dtls_active_) {
+    LOG_J(LS_ERROR, this) << "Can't set DTLS remote settings in this state.";
+    return false;
+  }
+
   // At this point we know we are doing DTLS
   remote_fingerprint_value_ = remote_fingerprint_value.Pass();
   remote_fingerprint_algorithm_ = digest_alg;
 
+  bool reconnect = dtls_;
+
   if (!SetupDtls()) {
     set_dtls_state(DTLS_TRANSPORT_FAILED);
     return false;
   }
 
+  if (reconnect) {
+    Reconnect();
+  }
+
   return true;
 }
 
 bool DtlsTransportChannelWrapper::GetRemoteSSLCertificate(
     rtc::SSLCertificate** cert) const {
   if (!dtls_) {
     return false;
   }
 
   return dtls_->GetPeerCertificate(cert);
@@ skipping 282 matching lines @@
     if (dtls_->GetState() == rtc::SS_OPEN) {
       // The check for OPEN shouldn't be necessary but let's make
       // sure we don't accidentally frob the state if it's closed.
       set_dtls_state(DTLS_TRANSPORT_CONNECTED);
       set_writable(true);
     }
   }
   if (sig & rtc::SE_READ) {
     char buf[kMaxDtlsPacketLen];
     size_t read;
-    if (dtls_->Read(buf, sizeof(buf), &read, NULL) == rtc::SR_SUCCESS) {
+    rtc::StreamResult result = dtls_->Read(buf, sizeof(buf), &read, NULL);
+    if (result == rtc::SR_SUCCESS) {
       SignalReadPacket(this, buf, read, rtc::CreatePacketTime(0), 0);
+    } else if (result == rtc::SR_EOS) {
+      // If the SSL stream has closed remotely, reset the |sig| to be SE_CLOSE

[juberti, 2015/12/02 00:29:43]

Won't we get a SE_CLOSE anyway after the SE_READ?

[guoweis_webrtc, 2015/12/02 18:44:15]

This crashes randomly after many repeated runs so it seems a timing issue. My
plan was to land this first and then write a test case to prevent the transfer
test cases become flaky. I don't have full investigation why this crashes at
this point.

Let me know if you want me to back this one out though.

[guoweis_webrtc, 2015/12/03 22:59:41]

I'm backing this out. This still crashes but with the change of when we reset
DTLS, it seems less likely now. I'll make the change later with a test case.

+      // so it could be handled below.
+      sig = rtc::SE_CLOSE;
     }
   }
   if (sig & rtc::SE_CLOSE) {
     ASSERT(sig == rtc::SE_CLOSE);  // SE_CLOSE should be by itself.
     set_writable(false);
     if (!err) {
       LOG_J(LS_INFO, this) << "DTLS channel closed";
       set_dtls_state(DTLS_TRANSPORT_CLOSED);
     } else {
       LOG_J(LS_INFO, this) << "DTLS channel error, code=" << err;
@@ skipping 64 matching lines @@
   ASSERT(channel == channel_);
   SignalRouteChange(this, candidate);
 }
 
 void DtlsTransportChannelWrapper::OnConnectionRemoved(
     TransportChannelImpl* channel) {
   ASSERT(channel == channel_);
   SignalConnectionRemoved(this);
 }
 
+void DtlsTransportChannelWrapper::Reconnect() {
+  set_dtls_state(DTLS_TRANSPORT_NEW);
+  set_writable(false);
+  if (channel_->writable()) {
+    OnWritableState(channel_);
+  } else {
+    channel_->Connect();

[juberti, 2015/12/02 00:29:44]

Why do we need to call Connect() here? We didn't do this before.

[guoweis_webrtc, 2015/12/02 18:44:15]

Indeed, the tranfered endpoint has always maintained writable for its
|channel_|. However, I'm wondering if we should also handle the case when it
becomes unwritable? 

[guoweis_webrtc, 2015/12/03 22:59:41]

Right, we don't need this part. Removing it.

+  }
+}
+
 }  // namespace cricket