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

The encrypted WebM spec RFC changed to treat IVs as raw data.

BUG=155641
TEST=All media_unittests pass.
TBR=sky

Review URL: https://chromiumcodereview.appspot.com/11139008

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@162012 0039d316-1c4b-4281-b951-d872f2087c98

4 files changed, 32 insertions, 28 deletions

diff --git a/media/crypto/aes_decryptor_unittest.cc b/media/crypto/aes_decryptor_unittest.cc
index 1b9d52e..0f3537e 100644
--- a/media/crypto/aes_decryptor_unittest.cc
+++ b/media/crypto/aes_decryptor_unittest.cc
@@ -7,7 +7,6 @@
 
 #include "base/basictypes.h"
 #include "base/bind.h"
-#include "base/sys_byteorder.h"
 #include "media/base/decoder_buffer.h"
 #include "media/base/decrypt_config.h"
 #include "media/base/mock_filters.h"
@@ -92,8 +91,8 @@ const WebmEncryptedData kWebmEncryptedFrames[] = {
       0x39, 0x3a, 0x3b, 0x3c, 0x3d, 0x3e, 0x3f, 0x40
       }, 16,
     // encrypted_data
-    { 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
-      0x01, 0x9c, 0x71, 0x26, 0x57, 0x3e, 0x25, 0x37,
+    { 0x01, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+      0x00, 0x9c, 0x71, 0x26, 0x57, 0x3e, 0x25, 0x37,
       0xf7, 0x31, 0x81, 0x19, 0x64, 0xce, 0xbc
       }, 23
   },
@@ -161,16 +160,16 @@ static const SubsampleEntry kSubsampleEntries[] = {
   { 1, 0 }
 };
 
-// Returns a 16 byte CTR counter block. The CTR counter block format is a
-// CTR IV appended with a CTR block counter. |iv| is a CTR IV. |iv_size| is
-// the size of |iv| in bytes.
+// 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.
+// |iv_size| is the size of |iv| in btyes. Returns a string of
+// kDecryptionKeySize bytes.
 static std::string GenerateCounterBlock(const uint8* iv, int iv_size) {
-  const int kDecryptionKeySize = 16;
   CHECK_GT(iv_size, 0);
-  CHECK_LE(iv_size, kDecryptionKeySize);
+  CHECK_LE(iv_size, DecryptConfig::kDecryptionKeySize);
 
   std::string counter_block(reinterpret_cast<const char*>(iv), iv_size);
-  counter_block.append(kDecryptionKeySize - iv_size, 0);
+  counter_block.append(DecryptConfig::kDecryptionKeySize - iv_size, 0);
   return counter_block;
 }
 
@@ -187,9 +186,10 @@ static scoped_refptr<DecoderBuffer> CreateWebMEncryptedBuffer(
   scoped_refptr<DecoderBuffer> encrypted_buffer = DecoderBuffer::CopyFrom(
       data, data_size);
   CHECK(encrypted_buffer);
+  DCHECK_EQ(kWebMSignalByteSize, 1);
 
   uint8 signal_byte = data[0];
-  int data_offset = sizeof(signal_byte);
+  int data_offset = kWebMSignalByteSize;
 
   // Setting the DecryptConfig object of the buffer while leaving the
   // initialization vector empty will tell the decryptor that the frame is
@@ -197,12 +197,8 @@ static scoped_refptr<DecoderBuffer> CreateWebMEncryptedBuffer(
   std::string counter_block_str;
 
   if (signal_byte & kWebMFlagEncryptedFrame) {
-    uint64 network_iv;
-    memcpy(&network_iv, data + data_offset, sizeof(network_iv));
-    const uint64 iv = base::NetToHost64(network_iv);
-    counter_block_str =
-        GenerateCounterBlock(reinterpret_cast<const uint8*>(&iv), sizeof(iv));
-    data_offset += sizeof(iv);
+    counter_block_str = GenerateCounterBlock(data + data_offset, kWebMIvSize);
+    data_offset += kWebMIvSize;
   }
 
   encrypted_buffer->SetDecryptConfig(
diff --git a/media/filters/pipeline_integration_test.cc b/media/filters/pipeline_integration_test.cc
index 77d3bf3..ffafb0e 100644
--- a/media/filters/pipeline_integration_test.cc
+++ b/media/filters/pipeline_integration_test.cc
@@ -368,9 +368,7 @@ TEST_F(PipelineIntegrationTest, BasicPlayback_16x9AspectRatio) {
   ASSERT_TRUE(WaitUntilOnEnded());
 }
 
-// TODO(fgalligan): Enable after WebM parser has been updated.
-// http://crbug.com/155641
-TEST_F(PipelineIntegrationTest, DISABLED_EncryptedPlayback) {
+TEST_F(PipelineIntegrationTest, EncryptedPlayback) {
   MockMediaSource source("bear-320x240-encrypted.webm", kWebM, 219816);
   FakeDecryptorClient encrypted_media;
   StartPipelineWithEncryptedMedia(&source, &encrypted_media);
diff --git a/media/webm/webm_cluster_parser.cc b/media/webm/webm_cluster_parser.cc
index fb1c69b..477f668 100644
--- a/media/webm/webm_cluster_parser.cc
+++ b/media/webm/webm_cluster_parser.cc
@@ -7,7 +7,6 @@
 #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"
@@ -16,10 +15,11 @@ 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);
+// |iv_size| is the size of |iv| in btyes. Returns a string of
+// kDecryptionKeySize bytes.
+static std::string GenerateCounterBlock(const uint8* iv, int iv_size) {
+  std::string counter_block(reinterpret_cast<const char*>(iv), iv_size);
+  counter_block.append(DecryptConfig::kDecryptionKeySize - iv_size, 0);
   return counter_block;
 }
 
@@ -185,6 +185,7 @@ bool WebMClusterParser::OnBlock(int track_num, int timecode,
                                 int  block_duration,
                                 int flags,
                                 const uint8* data, int size) {
+  DCHECK_GE(size, 0);
   if (cluster_timecode_ == -1) {
     DVLOG(1) << "Got a block before cluster timecode.";
     return false;
@@ -228,6 +229,11 @@ bool WebMClusterParser::OnBlock(int track_num, int timecode,
   // encrypted WebM request for comments specification is here
   // http://wiki.webmproject.org/encryption/webm-encryption-rfc
   if (!encryption_key_id.empty()) {
+    DCHECK_EQ(kWebMSignalByteSize, 1);
+    if (size < kWebMSignalByteSize) {
+      DVLOG(1) << "Got a block from an encrypted stream with no data.";
+      return false;
+    }
     uint8 signal_byte = data[0];
     int data_offset = sizeof(signal_byte);
 
@@ -237,10 +243,12 @@ bool WebMClusterParser::OnBlock(int track_num, int timecode,
     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));
+      if (size < kWebMSignalByteSize + kWebMIvSize) {
+        DVLOG(1) << "Got an encrypted block with not enough data " << size;
+        return false;
+      }
+      counter_block = GenerateCounterBlock(data + data_offset, kWebMIvSize);
+      data_offset += kWebMIvSize;
     }
 
     // TODO(fgalligan): Revisit if DecryptConfig needs to be set on unencrypted
diff --git a/media/webm/webm_constants.h b/media/webm/webm_constants.h
index 463b15a..7e5e3b1 100644
--- a/media/webm/webm_constants.h
+++ b/media/webm/webm_constants.h
@@ -202,6 +202,8 @@ const uint8 kWebMFlagKeyframe = 0x80;
 // Current encrypted WebM request for comments specification is here
 // http://wiki.webmproject.org/encryption/webm-encryption-rfc
 const uint8 kWebMFlagEncryptedFrame = 0x1;
+const int kWebMIvSize = 8;
+const int kWebMSignalByteSize = 1;
 
 }  // namespace media