Change WebM parser to treat IVs from encrypted WebM as raw data.

media/webm/webm_cluster_parser.cc

 // Copyright (c) 2012 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 "media/webm/webm_cluster_parser.h"
 
 #include <vector>
 
 #include "base/logging.h"
 #include "base/sys_byteorder.h"
 #include "media/base/data_buffer.h"
 #include "media/base/decrypt_config.h"
 #include "media/webm/webm_constants.h"
 
 namespace media {
 
 // Generates a 16 byte CTR counter block. The CTR counter block format is a
 // CTR IV appended with a CTR block counter. |iv| is an 8 byte CTR IV.
 // Returns a string of kDecryptionKeySize bytes.
-static std::string GenerateCounterBlock(uint64 iv) {
-  std::string counter_block(reinterpret_cast<char*>(&iv), sizeof(iv));
-  counter_block.append(DecryptConfig::kDecryptionKeySize - sizeof(iv), 0);
+static std::string GenerateCounterBlock(const std::string& iv) {
+  std::string counter_block(iv);
+  counter_block.append(DecryptConfig::kDecryptionKeySize - kWebMIvSize, 0);
   return counter_block;
 }
 
 WebMClusterParser::WebMClusterParser(int64 timecode_scale,
                                      int audio_track_num,
                                      int video_track_num,
                                      const std::string& audio_encryption_key_id,
                                      const std::string& video_encryption_key_id)
     : timecode_multiplier_(timecode_scale / 1000.0),
       audio_encryption_key_id_(audio_encryption_key_id),
@@ skipping 197 matching lines @@
   if (!encryption_key_id.empty()) {
     uint8 signal_byte = data[0];
     int data_offset = sizeof(signal_byte);
 
     // Setting the DecryptConfig object of the buffer while leaving the
     // initialization vector empty will tell the decryptor that the frame is
     // unencrypted.
     std::string counter_block;
 
     if (signal_byte & kWebMFlagEncryptedFrame) {
-      uint64 network_iv;
-      memcpy(&network_iv, data + data_offset, sizeof(network_iv));
-      data_offset += sizeof(network_iv);
-      counter_block = GenerateCounterBlock(base::NetToHost64(network_iv));
+      const std::string iv(reinterpret_cast<const char*>(data + data_offset),

[ddorwin, 2012/10/13 00:26:17]

nit: We create a string just to then copy it to another string. If we just
passed the pointer as before, we'd avoid a copy.

[fgalligan1, 2012/10/13 06:20:31]

Done.

+                           kWebMIvSize);
+      data_offset += kWebMIvSize;
+      counter_block = GenerateCounterBlock(iv);
     }
 
     // TODO(fgalligan): Revisit if DecryptConfig needs to be set on unencrypted
     // frames after the CDM API is finalized.
     // Unencrypted frames of potentially encrypted streams currently set
     // DecryptConfig.
     buffer->SetDecryptConfig(scoped_ptr<DecryptConfig>(new DecryptConfig(
         encryption_key_id,
         counter_block,
         data_offset,
@@ skipping 28 matching lines @@
 
   buffers_.push_back(buffer);
   return true;
 }
 
 void WebMClusterParser::Track::Reset() {
   buffers_.clear();
 }
 
 }  // namespace media