Only set certificate on DTLS transport if fingerprint is found in SDP.

webrtc/p2p/base/transportdescriptionfactory.cc

 /*
  *  Copyright 2012 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 92 matching lines @@
 
 bool TransportDescriptionFactory::SetSecurityInfo(
     TransportDescription* desc, ConnectionRole role) const {
   if (!certificate_) {
     LOG(LS_ERROR) << "Cannot create identity digest with no certificate";
     return false;
   }
 
   // This digest algorithm is used to produce the a=fingerprint lines in SDP.
   // RFC 4572 Section 5 requires that those lines use the same hash function as
-  // the certificate's signature.
+  // the certificate's signature, which is what CreateFromCertificate does.
+  desc->identity_fingerprint.reset(
+      rtc::SSLFingerprint::CreateFromCertificate(certificate_));
+  if (!desc->identity_fingerprint) {
+    return false;
+  }
   std::string digest_alg;
   if (!certificate_->ssl_certificate().GetSignatureDigestAlgorithm(
           &digest_alg)) {
     LOG(LS_ERROR) << "Failed to retrieve the certificate's digest algorithm";
     return false;
   }
 
   desc->identity_fingerprint.reset(
       rtc::SSLFingerprint::Create(digest_alg, certificate_->identity()));
   if (!desc->identity_fingerprint.get()) {
     LOG(LS_ERROR) << "Failed to create identity fingerprint, alg="
                   << digest_alg;
     return false;
   }
 
   // Assign security role.
   desc->connection_role = role;
   return true;
 }
 
 }  // namespace cricket