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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 "media/cdm/cenc_utils.h"
#include "base/stl_util.h"
#include "media/formats/mp4/box_definitions.h"
#include "media/formats/mp4/box_reader.h"
namespace media {
// The initialization data for encrypted media files using the ISO Common
// Encryption ('cenc') protection scheme may contain one or more protection
// system specific header ('pssh') boxes.
// ref: https://w3c.github.io/encrypted-media/cenc-format.html
// SystemID for the Common System.
// https://w3c.github.io/encrypted-media/cenc-format.html#common-system
const uint8_t kCommonSystemId[] = { 0x10, 0x77, 0xef, 0xec,
0xc0, 0xb2, 0x4d, 0x02,
0xac, 0xe3, 0x3c, 0x1e,
0x52, 0xe2, 0xfb, 0x4b };
static bool ReadAllPsshBoxes(
const std::vector<uint8_t>& input,
std::vector<mp4::FullProtectionSystemSpecificHeader>* pssh_boxes) {
DCHECK(!input.empty());
// Verify that |input| contains only 'pssh' boxes. ReadAllChildren() is
// templated, so it checks that each box in |input| matches the box type of
// the parameter (in this case mp4::ProtectionSystemSpecificHeader is a
// 'pssh' box). mp4::ProtectionSystemSpecificHeader doesn't validate the
// 'pssh' contents, so this simply verifies that |input| only contains
// 'pssh' boxes and nothing else.
scoped_ptr<mp4::BoxReader> input_reader(
mp4::BoxReader::ReadConcatentatedBoxes(
vector_as_array(&input), input.size()));
std::vector<mp4::ProtectionSystemSpecificHeader> raw_pssh_boxes;
if (!input_reader->ReadAllChildren(&raw_pssh_boxes))
return false;
// Now that we have |input| parsed into |raw_pssh_boxes|, reparse each one
// into a mp4::FullProtectionSystemSpecificHeader, which extracts all the
// relevant fields from the box. Since there may be unparseable 'pssh' boxes
// (due to unsupported version, for example), this is done one by one,
// ignoring any boxes that can't be parsed.
for (const auto& raw_pssh_box : raw_pssh_boxes) {
scoped_ptr<mp4::BoxReader> raw_pssh_reader(
mp4::BoxReader::ReadConcatentatedBoxes(
vector_as_array(&raw_pssh_box.raw_box),
raw_pssh_box.raw_box.size()));
// ReadAllChildren() appends any successfully parsed box onto it's
// parameter, so |pssh_boxes| will contain the collection of successfully
// parsed 'pssh' boxes. If an error occurs, try the next box.
if (!raw_pssh_reader->ReadAllChildren(pssh_boxes))
continue;
}
// Must have successfully parsed at least one 'pssh' box.
return pssh_boxes->size() > 0;
}
bool ValidatePsshInput(const std::vector<uint8_t>& input) {
// No 'pssh' boxes is considered valid.
if (input.empty())
return true;
std::vector<mp4::FullProtectionSystemSpecificHeader> children;
return ReadAllPsshBoxes(input, &children);
}
bool GetKeyIdsForCommonSystemId(const std::vector<uint8_t>& input,
KeyIdList* key_ids) {
KeyIdList result;
std::vector<uint8_t> common_system_id(
kCommonSystemId, kCommonSystemId + arraysize(kCommonSystemId));
if (!input.empty()) {
std::vector<mp4::FullProtectionSystemSpecificHeader> children;
if (!ReadAllPsshBoxes(input, &children))
return false;
// Check all children for an appropriate 'pssh' box, concatenating any
// key IDs found.
for (const auto& child : children) {
if (child.system_id == common_system_id && child.key_ids.size() > 0)
result.insert(result.end(), child.key_ids.begin(), child.key_ids.end());
}
}
key_ids->swap(result);
return key_ids->size() > 0;
}
bool GetPsshData(const std::vector<uint8_t>& input,
const std::vector<uint8_t>& system_id,
std::vector<uint8_t>* pssh_data) {
if (input.empty())
return false;
std::vector<mp4::FullProtectionSystemSpecificHeader> children;
if (!ReadAllPsshBoxes(input, &children))
return false;
// Check all children for an appropriate 'pssh' box, returning |data| from
// the first one found.
for (const auto& child : children) {
if (child.system_id == system_id) {
pssh_data->assign(child.data.begin(), child.data.end());
return true;
}
}
// No matching 'pssh' box found.
return false;
}
} // namespace media
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