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shaka-packager/media/base/widevine_key_source.cc

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// Copyright 2014 Google Inc. All rights reserved.
//
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file or at
// https://developers.google.com/open-source/licenses/bsd
#include "media/base/widevine_key_source.h"
#include "base/base64.h"
#include "base/bind.h"
#include "base/json/json_reader.h"
#include "base/json/json_writer.h"
#include "base/memory/ref_counted.h"
#include "base/stl_util.h"
#include "media/base/http_fetcher.h"
#include "media/base/producer_consumer_queue.h"
#include "media/base/request_signer.h"
#define RCHECK(x) \
do { \
if (!(x)) { \
LOG(ERROR) << "Failure while processing: " << #x; \
return false; \
} \
} while (0)
namespace edash_packager {
namespace {
const bool kEnableKeyRotation = true;
const char kLicenseStatusOK[] = "OK";
// Server may return INTERNAL_ERROR intermittently, which is a transient error
// and the next client request may succeed without problem.
const char kLicenseStatusTransientError[] = "INTERNAL_ERROR";
// Number of times to retry requesting keys in case of a transient error from
// the server.
const int kNumTransientErrorRetries = 5;
const int kFirstRetryDelayMilliseconds = 1000;
// Default crypto period count, which is the number of keys to fetch on every
// key rotation enabled request.
const int kDefaultCryptoPeriodCount = 10;
const int kGetKeyTimeoutInSeconds = 5 * 60; // 5 minutes.
const int kHttpTimeoutInSeconds = 60; // 1 minute.
bool Base64StringToBytes(const std::string& base64_string,
std::vector<uint8_t>* bytes) {
DCHECK(bytes);
std::string str;
if (!base::Base64Decode(base64_string, &str))
return false;
bytes->assign(str.begin(), str.end());
return true;
}
void BytesToBase64String(const std::vector<uint8_t>& bytes,
std::string* base64_string) {
DCHECK(base64_string);
base::Base64Encode(base::StringPiece(reinterpret_cast<const char*>
(bytes.data()), bytes.size()),
base64_string);
}
bool GetKeyFromTrack(const base::DictionaryValue& track_dict,
std::vector<uint8_t>* key) {
DCHECK(key);
std::string key_base64_string;
RCHECK(track_dict.GetString("key", &key_base64_string));
VLOG(2) << "Key:" << key_base64_string;
RCHECK(Base64StringToBytes(key_base64_string, key));
return true;
}
bool GetKeyIdFromTrack(const base::DictionaryValue& track_dict,
std::vector<uint8_t>* key_id) {
DCHECK(key_id);
std::string key_id_base64_string;
RCHECK(track_dict.GetString("key_id", &key_id_base64_string));
VLOG(2) << "Keyid:" << key_id_base64_string;
RCHECK(Base64StringToBytes(key_id_base64_string, key_id));
return true;
}
bool GetPsshDataFromTrack(const base::DictionaryValue& track_dict,
std::vector<uint8_t>* pssh_data) {
DCHECK(pssh_data);
const base::ListValue* pssh_list;
RCHECK(track_dict.GetList("pssh", &pssh_list));
// Invariant check. We don't want to crash in release mode if possible.
// The following code handles it gracefully if GetSize() does not return 1.
DCHECK_EQ(1u, pssh_list->GetSize());
const base::DictionaryValue* pssh_dict;
RCHECK(pssh_list->GetDictionary(0, &pssh_dict));
std::string drm_type;
RCHECK(pssh_dict->GetString("drm_type", &drm_type));
if (drm_type != "WIDEVINE") {
LOG(ERROR) << "Expecting drm_type 'WIDEVINE', get '" << drm_type << "'.";
return false;
}
std::string pssh_data_base64_string;
RCHECK(pssh_dict->GetString("data", &pssh_data_base64_string));
VLOG(2) << "Pssh Data:" << pssh_data_base64_string;
RCHECK(Base64StringToBytes(pssh_data_base64_string, pssh_data));
return true;
}
} // namespace
namespace media {
// A ref counted wrapper for EncryptionKeyMap.
class WidevineKeySource::RefCountedEncryptionKeyMap
: public base::RefCountedThreadSafe<RefCountedEncryptionKeyMap> {
public:
explicit RefCountedEncryptionKeyMap(EncryptionKeyMap* encryption_key_map) {
DCHECK(encryption_key_map);
encryption_key_map_.swap(*encryption_key_map);
}
std::map<KeySource::TrackType, EncryptionKey*>& map() {
return encryption_key_map_;
}
private:
friend class base::RefCountedThreadSafe<RefCountedEncryptionKeyMap>;
~RefCountedEncryptionKeyMap() { STLDeleteValues(&encryption_key_map_); }
EncryptionKeyMap encryption_key_map_;
DISALLOW_COPY_AND_ASSIGN(RefCountedEncryptionKeyMap);
};
WidevineKeySource::WidevineKeySource(
const std::string& server_url,
scoped_ptr<RequestSigner> signer)
: http_fetcher_(new SimpleHttpFetcher(kHttpTimeoutInSeconds)),
server_url_(server_url),
signer_(signer.Pass()),
crypto_period_count_(kDefaultCryptoPeriodCount),
key_production_started_(false),
start_key_production_(false, false),
first_crypto_period_index_(0),
key_production_thread_(
"KeyProductionThread",
base::Bind(&WidevineKeySource::FetchKeysTask,
base::Unretained(this))) {
DCHECK(signer_);
}
WidevineKeySource::~WidevineKeySource() {
if (key_pool_)
key_pool_->Stop();
if (key_production_thread_.HasBeenStarted()) {
// Signal the production thread to start key production if it is not
// signaled yet so the thread can be joined.
start_key_production_.Signal();
key_production_thread_.Join();
}
}
Status WidevineKeySource::FetchKeys(const std::vector<uint8_t>& content_id,
const std::string& policy) {
base::AutoLock scoped_lock(lock_);
request_dict_.Clear();
std::string content_id_base64_string;
BytesToBase64String(content_id, &content_id_base64_string);
request_dict_.SetString("content_id", content_id_base64_string);
request_dict_.SetString("policy", policy);
return FetchKeysCommon(false);
}
Status WidevineKeySource::FetchKeys(const std::vector<uint8_t>& pssh_data) {
base::AutoLock scoped_lock(lock_);
request_dict_.Clear();
std::string pssh_data_base64_string;
BytesToBase64String(pssh_data, &pssh_data_base64_string);
request_dict_.SetString("pssh_data", pssh_data_base64_string);
return FetchKeysCommon(false);
}
Status WidevineKeySource::FetchKeys(uint32_t asset_id) {
base::AutoLock scoped_lock(lock_);
request_dict_.Clear();
request_dict_.SetInteger("asset_id", asset_id);
return FetchKeysCommon(true);
}
Status WidevineKeySource::FetchKeysCommon(bool widevine_classic) {
// TODO(tinskip): Make this method callable multiple times to fetch
// different keys.
DCHECK(!key_production_thread_.HasBeenStarted());
key_production_thread_.Start();
// Perform a fetch request to find out if the key source is healthy.
// It also stores the keys fetched for consumption later.
return FetchKeysInternal(!kEnableKeyRotation, 0, widevine_classic);
}
Status WidevineKeySource::GetKey(TrackType track_type,
EncryptionKey* key) {
DCHECK(key);
if (encryption_key_map_.find(track_type) == encryption_key_map_.end()) {
return Status(error::INTERNAL_ERROR,
"Cannot find key of type " + TrackTypeToString(track_type));
}
*key = *encryption_key_map_[track_type];
return Status::OK;
}
Status WidevineKeySource::GetKey(const std::vector<uint8_t>& key_id,
EncryptionKey* key) {
DCHECK(key);
for (std::map<TrackType, EncryptionKey*>::iterator iter =
encryption_key_map_.begin();
iter != encryption_key_map_.end();
++iter) {
if (iter->second->key_id == key_id) {
*key = *iter->second;
return Status::OK;
}
}
return Status(error::INTERNAL_ERROR,
"Cannot find key with specified key ID");
}
Status WidevineKeySource::GetCryptoPeriodKey(uint32_t crypto_period_index,
TrackType track_type,
EncryptionKey* key) {
DCHECK(key_production_thread_.HasBeenStarted());
// TODO(kqyang): This is not elegant. Consider refactoring later.
{
base::AutoLock scoped_lock(lock_);
if (!key_production_started_) {
// Another client may have a slightly smaller starting crypto period
// index. Set the initial value to account for that.
first_crypto_period_index_ = crypto_period_index ? crypto_period_index - 1 : 0;
DCHECK(!key_pool_);
key_pool_.reset(new EncryptionKeyQueue(crypto_period_count_,
first_crypto_period_index_));
start_key_production_.Signal();
key_production_started_ = true;
}
}
return GetKeyInternal(crypto_period_index, track_type, key);
}
void WidevineKeySource::set_http_fetcher(
scoped_ptr<HttpFetcher> http_fetcher) {
http_fetcher_ = http_fetcher.Pass();
}
Status WidevineKeySource::GetKeyInternal(uint32_t crypto_period_index,
TrackType track_type,
EncryptionKey* key) {
DCHECK(key_pool_);
DCHECK(key);
DCHECK_LE(track_type, NUM_VALID_TRACK_TYPES);
DCHECK_NE(track_type, TRACK_TYPE_UNKNOWN);
scoped_refptr<RefCountedEncryptionKeyMap> ref_counted_encryption_key_map;
Status status =
key_pool_->Peek(crypto_period_index, &ref_counted_encryption_key_map,
kGetKeyTimeoutInSeconds * 1000);
if (!status.ok()) {
if (status.error_code() == error::STOPPED) {
CHECK(!common_encryption_request_status_.ok());
return common_encryption_request_status_;
}
return status;
}
EncryptionKeyMap& encryption_key_map = ref_counted_encryption_key_map->map();
if (encryption_key_map.find(track_type) == encryption_key_map.end()) {
return Status(error::INTERNAL_ERROR,
"Cannot find key of type " + TrackTypeToString(track_type));
}
*key = *encryption_key_map[track_type];
return Status::OK;
}
void WidevineKeySource::FetchKeysTask() {
// Wait until key production is signaled.
start_key_production_.Wait();
if (!key_pool_ || key_pool_->Stopped())
return;
Status status = FetchKeysInternal(kEnableKeyRotation,
first_crypto_period_index_,
false);
while (status.ok()) {
first_crypto_period_index_ += crypto_period_count_;
status = FetchKeysInternal(kEnableKeyRotation,
first_crypto_period_index_,
false);
}
common_encryption_request_status_ = status;
key_pool_->Stop();
}
Status WidevineKeySource::FetchKeysInternal(bool enable_key_rotation,
uint32_t first_crypto_period_index,
bool widevine_classic) {
std::string request;
FillRequest(enable_key_rotation,
first_crypto_period_index,
&request);
std::string message;
Status status = SignRequest(request, &message);
if (!status.ok())
return status;
VLOG(1) << "Message: " << message;
std::string raw_response;
int64_t sleep_duration = kFirstRetryDelayMilliseconds;
// Perform client side retries if seeing server transient error to workaround
// server limitation.
for (int i = 0; i < kNumTransientErrorRetries; ++i) {
status = http_fetcher_->Post(server_url_, message, &raw_response);
if (status.ok()) {
VLOG(1) << "Retry [" << i << "] Response:" << raw_response;
std::string response;
if (!DecodeResponse(raw_response, &response)) {
return Status(error::SERVER_ERROR,
"Failed to decode response '" + raw_response + "'.");
}
bool transient_error = false;
if (ExtractEncryptionKey(enable_key_rotation,
widevine_classic,
response,
&transient_error))
return Status::OK;
if (!transient_error) {
return Status(
error::SERVER_ERROR,
"Failed to extract encryption key from '" + response + "'.");
}
} else if (status.error_code() != error::TIME_OUT) {
return status;
}
// Exponential backoff.
if (i != kNumTransientErrorRetries - 1) {
base::PlatformThread::Sleep(
base::TimeDelta::FromMilliseconds(sleep_duration));
sleep_duration *= 2;
}
}
return Status(error::SERVER_ERROR,
"Failed to recover from server internal error.");
}
void WidevineKeySource::FillRequest(bool enable_key_rotation,
uint32_t first_crypto_period_index,
std::string* request) {
DCHECK(request);
DCHECK(!request_dict_.empty());
// Build tracks.
base::ListValue* tracks = new base::ListValue();
base::DictionaryValue* track_sd = new base::DictionaryValue();
track_sd->SetString("type", "SD");
tracks->Append(track_sd);
base::DictionaryValue* track_hd = new base::DictionaryValue();
track_hd->SetString("type", "HD");
tracks->Append(track_hd);
base::DictionaryValue* track_audio = new base::DictionaryValue();
track_audio->SetString("type", "AUDIO");
tracks->Append(track_audio);
request_dict_.Set("tracks", tracks);
// Build DRM types.
base::ListValue* drm_types = new base::ListValue();
drm_types->AppendString("WIDEVINE");
request_dict_.Set("drm_types", drm_types);
// Build key rotation fields.
if (enable_key_rotation) {
request_dict_.SetInteger("first_crypto_period_index",
first_crypto_period_index);
request_dict_.SetInteger("crypto_period_count", crypto_period_count_);
}
base::JSONWriter::Write(&request_dict_, request);
}
Status WidevineKeySource::SignRequest(const std::string& request,
std::string* signed_request) {
DCHECK(signed_request);
// Sign the request.
std::string signature;
if (!signer_->GenerateSignature(request, &signature))
return Status(error::INTERNAL_ERROR, "Signature generation failed.");
// Encode request and signature using Base64 encoding.
std::string request_base64_string;
base::Base64Encode(request, &request_base64_string);
std::string signature_base64_string;
base::Base64Encode(signature, &signature_base64_string);
base::DictionaryValue signed_request_dict;
signed_request_dict.SetString("request", request_base64_string);
signed_request_dict.SetString("signature", signature_base64_string);
signed_request_dict.SetString("signer", signer_->signer_name());
base::JSONWriter::Write(&signed_request_dict, signed_request);
return Status::OK;
}
bool WidevineKeySource::DecodeResponse(
const std::string& raw_response,
std::string* response) {
DCHECK(response);
// Extract base64 formatted response from JSON formatted raw response.
scoped_ptr<base::Value> root(base::JSONReader::Read(raw_response));
if (!root) {
LOG(ERROR) << "'" << raw_response << "' is not in JSON format.";
return false;
}
const base::DictionaryValue* response_dict = NULL;
RCHECK(root->GetAsDictionary(&response_dict));
std::string response_base64_string;
RCHECK(response_dict->GetString("response", &response_base64_string));
RCHECK(base::Base64Decode(response_base64_string, response));
return true;
}
bool WidevineKeySource::ExtractEncryptionKey(
bool enable_key_rotation,
bool widevine_classic,
const std::string& response,
bool* transient_error) {
DCHECK(transient_error);
*transient_error = false;
scoped_ptr<base::Value> root(base::JSONReader::Read(response));
if (!root) {
LOG(ERROR) << "'" << response << "' is not in JSON format.";
return false;
}
const base::DictionaryValue* license_dict = NULL;
RCHECK(root->GetAsDictionary(&license_dict));
std::string license_status;
RCHECK(license_dict->GetString("status", &license_status));
if (license_status != kLicenseStatusOK) {
LOG(ERROR) << "Received non-OK license response: " << response;
*transient_error = (license_status == kLicenseStatusTransientError);
return false;
}
const base::ListValue* tracks;
RCHECK(license_dict->GetList("tracks", &tracks));
RCHECK(enable_key_rotation
? tracks->GetSize() >= NUM_VALID_TRACK_TYPES * crypto_period_count_
: tracks->GetSize() >= NUM_VALID_TRACK_TYPES);
int current_crypto_period_index = first_crypto_period_index_;
EncryptionKeyMap encryption_key_map;
for (size_t i = 0; i < tracks->GetSize(); ++i) {
const base::DictionaryValue* track_dict;
RCHECK(tracks->GetDictionary(i, &track_dict));
if (enable_key_rotation) {
int crypto_period_index;
RCHECK(
track_dict->GetInteger("crypto_period_index", &crypto_period_index));
if (crypto_period_index != current_crypto_period_index) {
if (crypto_period_index != current_crypto_period_index + 1) {
LOG(ERROR) << "Expecting crypto period index "
<< current_crypto_period_index << " or "
<< current_crypto_period_index + 1 << "; Seen "
<< crypto_period_index << " at track " << i;
return false;
}
if (!PushToKeyPool(&encryption_key_map))
return false;
++current_crypto_period_index;
}
}
std::string track_type_str;
RCHECK(track_dict->GetString("type", &track_type_str));
TrackType track_type = GetTrackTypeFromString(track_type_str);
DCHECK_NE(TRACK_TYPE_UNKNOWN, track_type);
RCHECK(encryption_key_map.find(track_type) == encryption_key_map.end());
scoped_ptr<EncryptionKey> encryption_key(new EncryptionKey());
if (!GetKeyFromTrack(*track_dict, &encryption_key->key))
return false;
// Get key ID and PSSH data for CENC content only.
if (!widevine_classic) {
if (!GetKeyIdFromTrack(*track_dict, &encryption_key->key_id))
return false;
std::vector<uint8_t> pssh_data;
if (!GetPsshDataFromTrack(*track_dict, &pssh_data))
return false;
encryption_key->pssh = PsshBoxFromPsshData(pssh_data);
}
encryption_key_map[track_type] = encryption_key.release();
}
DCHECK(!encryption_key_map.empty());
if (!enable_key_rotation) {
encryption_key_map_ = encryption_key_map;
return true;
}
return PushToKeyPool(&encryption_key_map);
}
bool WidevineKeySource::PushToKeyPool(
EncryptionKeyMap* encryption_key_map) {
DCHECK(key_pool_);
DCHECK(encryption_key_map);
Status status =
key_pool_->Push(scoped_refptr<RefCountedEncryptionKeyMap>(
new RefCountedEncryptionKeyMap(encryption_key_map)),
kInfiniteTimeout);
encryption_key_map->clear();
if (!status.ok()) {
DCHECK_EQ(error::STOPPED, status.error_code());
return false;
}
return true;
}
} // namespace media
} // namespace edash_packager
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