Add WARN_UNUSED_RESULT to crypto/hmac.h

remoting/protocol/jingle_session.cc

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "remoting/protocol/jingle_session.h"
 
 #include "base/bind.h"
 #include "base/message_loop.h"
 #include "base/rand_util.h"
 #include "base/stl_util.h"
@@ skipping 53 matching lines @@
 }
 
 // Generates channel key from master key and channel name. Must be
 // used to generate channel key so that we don't use the same key for
 // different channels. The key is calculated as
 //   HMAC_SHA256(master_key, channel_name)
 bool GetChannelKey(const std::string& channel_name,
                    const std::string& master_key,
                    std::string* channel_key) {
   crypto::HMAC hmac(crypto::HMAC::SHA256);
-  hmac.Init(channel_name);
+  if (!hmac.Init(channel_name)) {
+    channel_key->clear();
+    return false;
+  }
   channel_key->resize(kChannelKeyLength);
   if (!hmac.Sign(master_key,
                  reinterpret_cast<unsigned char*>(&(*channel_key)[0]),
                  channel_key->size())) {
-    *channel_key = "";
+    channel_key->clear();
     return false;
   }
   return true;
 }
 
 }  // namespace
 
 // static
 JingleSession* JingleSession::CreateClientSession(
     JingleSessionManager* manager, const std::string& host_public_key) {
@@ skipping 491 matching lines @@
 
     state_ = new_state;
     if (!closed_ && state_change_callback_.get())
       state_change_callback_->Run(new_state);
   }
 }
 
 }  // namespace protocol
 
 }  // namespace remoting