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// Copyright 2015 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 "components/cdm/browser/widevine_drm_delegate_android.h"
#include "base/logging.h"
#include "base/numerics/safe_conversions.h"
namespace cdm {
namespace {
uint32_t ReadUint32(const uint8_t* data) {
uint32_t value = 0;
for (int i = 0; i < 4; ++i)
value = (value << 8) | data[i];
return value;
}
uint64_t ReadUint64(const uint8_t* data) {
uint64_t value = 0;
for (int i = 0; i < 8; ++i)
value = (value << 8) | data[i];
return value;
}
// The structure of an ISO CENC Protection System Specific Header (PSSH) box is
// as follows. (See ISO/IEC FDIS 23001-7:2011(E).)
// Note: ISO boxes use big-endian values.
//
// PSSH {
// uint32 Size
// uint32 Type
// uint64 LargeSize # Field is only present if value(Size) == 1.
// uint8 Version
// uint24 Flags
// uint8[16] SystemId
// if (version > 0) {
// uint32 KID_count;
// uint8[16][KID_Count] KID;
// }
// uint32 DataSize
// uint8[DataSize] Data
// }
const int kBoxHeaderSize = 8; // Box's header contains Size and Type.
const int kBoxLargeSizeSize = 8;
const int kPsshVersionFlagSize = 4;
const uint32_t k24BitMask = 0x00ffffff;
const int kPsshSystemIdSize = 16;
const int kPsshKidCountSize = 4;
const int kPsshKidSize = 16;
const int kPsshDataSizeSize = 4;
const uint32_t kPsshType = 0x70737368;
const uint8_t kWidevineUuid[16] = {
0xED, 0xEF, 0x8B, 0xA9, 0x79, 0xD6, 0x4A, 0xCE,
0xA3, 0xC8, 0x27, 0xDC, 0xD5, 0x1D, 0x21, 0xED };
// Tries to find a PSSH box with the Widevine UUID, parses the
// "Data" of the box and put it in |pssh_data|. Returns true if such a box is
// found and successfully parsed. Returns false otherwise.
// Notes:
// 1, If multiple PSSH boxes are found,the "Data" of the first matching PSSH box
// will be set in |pssh_data|.
// 2, Only PSSH boxes are allowed in |data|.
bool GetPsshData(const std::vector<uint8_t>& data,
std::vector<uint8_t>* pssh_data) {
int bytes_left = base::checked_cast<int>(data.size());
const uint8_t* cur = &data[0];
const uint8_t* data_end = cur + bytes_left;
while (bytes_left > 0) {
const uint8_t* box_head = cur;
if (bytes_left < kBoxHeaderSize)
return false;
uint64_t box_size = ReadUint32(cur);
uint32_t type = ReadUint32(cur + 4);
cur += kBoxHeaderSize;
bytes_left -= kBoxHeaderSize;
if (box_size == 1) { // LargeSize is present.
if (bytes_left < kBoxLargeSizeSize)
return false;
box_size = ReadUint64(cur);
cur += kBoxLargeSizeSize;
bytes_left -= kBoxLargeSizeSize;
} else if (box_size == 0) {
box_size = bytes_left + kBoxHeaderSize;
}
const uint8_t* box_end = box_head + box_size;
if (data_end < box_end)
return false;
if (type != kPsshType)
return false;
const int kPsshBoxMinimumSize =
kPsshVersionFlagSize + kPsshSystemIdSize + kPsshDataSizeSize;
if (box_end < cur + kPsshBoxMinimumSize)
return false;
uint8_t version = cur[0];
uint32_t flags = ReadUint32(cur) & k24BitMask;
cur += kPsshVersionFlagSize;
bytes_left -= kPsshVersionFlagSize;
if (flags != 0)
return false;
DCHECK_GE(bytes_left, kPsshSystemIdSize);
if (!std::equal(kWidevineUuid,
kWidevineUuid + sizeof(kWidevineUuid), cur)) {
cur = box_end;
bytes_left = data_end - cur;
continue;
}
cur += kPsshSystemIdSize;
bytes_left -= kPsshSystemIdSize;
// If KeyIDs specified, skip them.
if (version > 0) {
DCHECK_GE(bytes_left, kPsshKidCountSize);
uint32_t kid_count = ReadUint32(cur);
cur += kPsshKidCountSize + kid_count * kPsshKidSize;
bytes_left -= kPsshKidCountSize + kid_count * kPsshKidSize;
// Must be bytes left in this box for data_size.
if (box_end < cur + kPsshDataSizeSize)
return false;
}
DCHECK_GE(bytes_left, kPsshDataSizeSize);
uint32_t data_size = ReadUint32(cur);
cur += kPsshDataSizeSize;
bytes_left -= kPsshDataSizeSize;
if (box_end < cur + data_size)
return false;
pssh_data->assign(cur, cur + data_size);
return true;
}
return false;
}
}
WidevineDrmDelegateAndroid::WidevineDrmDelegateAndroid() {
}
WidevineDrmDelegateAndroid::~WidevineDrmDelegateAndroid() {
}
const std::vector<uint8_t> WidevineDrmDelegateAndroid::GetUUID() const {
return std::vector<uint8_t>(kWidevineUuid,
kWidevineUuid + arraysize(kWidevineUuid));
}
bool WidevineDrmDelegateAndroid::OnCreateSession(
const media::EmeInitDataType init_data_type,
const std::vector<uint8_t>& init_data,
std::vector<uint8_t>* init_data_out,
std::vector<std::string>* /* optional_parameters_out */) {
if (init_data_type != media::EmeInitDataType::CENC)
return true;
// Widevine MediaDrm plugin only accepts the "data" part of the PSSH box as
// the init data when using MP4 container.
return GetPsshData(init_data, init_data_out);
}
} // namespace cdm
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