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 104 matching lines @@
   channel_->SignalConnectionRemoved.connect(this,
       &DtlsTransportChannelWrapper::OnConnectionRemoved);
   channel_->SignalReceivingState.connect(this,
       &DtlsTransportChannelWrapper::OnReceivingState);
 }
 
 DtlsTransportChannelWrapper::~DtlsTransportChannelWrapper() {
 }
 
 void DtlsTransportChannelWrapper::Connect() {
-  // We should only get a single call to Connect.
   ASSERT(dtls_state() == DTLS_TRANSPORT_NEW);
-  channel_->Connect();
+  if (channel_->writable()) {
+    OnWritableState(channel_);
+  } else {
+    channel_->Connect();
+  }

[pthatcher1, 2015/11/18 20:42:43]

I think instead of changing the Connect method, we should make an explicit
Reconnect() method.  That way, it's clear that Connect is called once and
Reconnect() can be called many times.  Or just call channel_->Connect() below
instead of using Connect().

[guoweis_webrtc, 2015/11/25 21:03:13]

Done.

 }
 
 bool DtlsTransportChannelWrapper::SetLocalCertificate(
     const rtc::scoped_refptr<rtc::RTCCertificate>& certificate) {
   if (dtls_active_) {
     if (certificate == local_certificate_) {
       // This may happen during renegotiation.
       LOG_J(LS_INFO, this) << "Ignoring identical DTLS identity";
       return true;
     } else {
@@ skipping 54 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);
 
+  bool reconnect = false;
+
   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())) {
+  if (!dtls_active_ && !digest_alg.empty()) {
     LOG_J(LS_ERROR, this) << "Can't set DTLS remote settings in this state.";
     return false;
   }
 
   if (digest_alg.empty()) {
     LOG_J(LS_INFO, this) << "Other side didn't support DTLS.";
     dtls_active_ = false;
     return true;
   }
 
+  if (dtls_) {
+    RTC_DCHECK(remote_fingerprint_value_ != remote_fingerprint_value);
+    reconnect = true;
+  }

[pthatcher1, 2015/11/18 20:42:43]

I think this would be more readable as something like this:

if (remote_fingerprint_value_ == remote_fingerprint_value &&
    remote_fingerprint_algorithm_ == digest_alg) {
  return; 
}

remote_fingerprint_value_ = remote_fingerprint_value.Pass();
remote_fingerprint_algorithm_ = digest_alg;

if (dtls_) {
  SignalDtlsReset(this);
  set_dtls_state(DTLS_TRANSPORT_NEW);
  set_writable(false);
  Reconnect();
  return true;
}

if (!SetupDtls()) {
  set_dtls_state(DTLS_TRANSPORT_FAILED);
  return false;
}

return true;

[guoweis_webrtc, 2015/11/25 21:03:13]

Reconnect has to be called after SetupDtls

+
   // At this point we know we are doing DTLS
   remote_fingerprint_value_ = remote_fingerprint_value.Pass();
   remote_fingerprint_algorithm_ = digest_alg;
 
   if (!SetupDtls()) {
     set_dtls_state(DTLS_TRANSPORT_FAILED);
     return false;
+  } else {
+    // We get the Dtls newly set up here. Signal the media side to re-setup SRTP
+    // context.
+    SignalDtlsSrtpSetup(this);
+  }
+
+  if (reconnect) {
+    set_dtls_state(DTLS_TRANSPORT_NEW);
+    set_writable(false);
+    Connect();
   }
 
   return true;
 }
 
 bool DtlsTransportChannelWrapper::GetRemoteSSLCertificate(
     rtc::SSLCertificate** cert) const {
   if (!dtls_) {
     return false;
   }
@@ skipping 372 matching lines @@
   SignalRouteChange(this, candidate);
 }
 
 void DtlsTransportChannelWrapper::OnConnectionRemoved(
     TransportChannelImpl* channel) {
   ASSERT(channel == channel_);
   SignalConnectionRemoved(this);
 }
 
 }  // namespace cricket