You can not select more than 25 topics Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.

233 lines
6.9 KiB

/*
* Copyright (C) 2017 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
//#define LOG_NDEBUG 0
#define LOG_TAG "JsonAssetLoader"
#include <media/stagefright/foundation/ABuffer.h>
#include <media/stagefright/foundation/AString.h>
#include <media/stagefright/foundation/base64.h>
#include <media/stagefright/MediaErrors.h>
#include <utils/Log.h>
#include "JsonAssetLoader.h"
#include "protos/license_protos.pb.h"
namespace android {
namespace clearkeycas {
const String8 kIdTag("id");
const String8 kNameTag("name");
const String8 kLowerCaseOgranizationNameTag("lowercase_organization_name");
const String8 kEncryptionKeyTag("encryption_key");
const String8 kCasTypeTag("cas_type");
const String8 kBase64Padding("=");
JsonAssetLoader::JsonAssetLoader() {
}
JsonAssetLoader::~JsonAssetLoader() {
}
/*
* Extract a clear key asset from a JSON string.
*
* Returns OK if a clear key asset is extracted successfully,
* or ERROR_CAS_NO_LICENSE if the string doesn't contain a valid
* clear key asset.
*/
status_t JsonAssetLoader::extractAssetFromString(
const String8& jsonAssetString, Asset *asset) {
if (!parseJsonAssetString(jsonAssetString, &mJsonObjects)) {
return ERROR_CAS_NO_LICENSE;
}
if (mJsonObjects.size() < 1) {
return ERROR_CAS_NO_LICENSE;
}
if (!parseJsonObject(mJsonObjects[0], &mTokens))
return ERROR_CAS_NO_LICENSE;
if (!findKey(mJsonObjects[0], asset)) {
return ERROR_CAS_NO_LICENSE;
}
return OK;
}
//static
sp<ABuffer> JsonAssetLoader::decodeBase64String(const String8& encodedText) {
// Since android::decodeBase64() requires padding characters,
// add them so length of encodedText is exactly a multiple of 4.
int remainder = encodedText.length() % 4;
String8 paddedText(encodedText);
if (remainder > 0) {
for (int i = 0; i < 4 - remainder; ++i) {
paddedText.append(kBase64Padding);
}
}
return decodeBase64(AString(paddedText.string()));
}
bool JsonAssetLoader::findKey(const String8& jsonObject, Asset *asset) {
String8 value;
if (jsonObject.find(kIdTag) < 0) {
return false;
}
findValue(kIdTag, &value);
ALOGV("found %s=%s", kIdTag.string(), value.string());
asset->set_id(atoi(value.string()));
if (jsonObject.find(kNameTag) < 0) {
return false;
}
findValue(kNameTag, &value);
ALOGV("found %s=%s", kNameTag.string(), value.string());
asset->set_name(value.string());
if (jsonObject.find(kLowerCaseOgranizationNameTag) < 0) {
return false;
}
findValue(kLowerCaseOgranizationNameTag, &value);
ALOGV("found %s=%s", kLowerCaseOgranizationNameTag.string(), value.string());
asset->set_lowercase_organization_name(value.string());
if (jsonObject.find(kCasTypeTag) < 0) {
return false;
}
findValue(kCasTypeTag, &value);
ALOGV("found %s=%s", kCasTypeTag.string(), value.string());
// Asset_CasType_CLEARKEY_CAS = 1
asset->set_cas_type((Asset_CasType)atoi(value.string()));
return true;
}
void JsonAssetLoader::findValue(const String8 &key, String8* value) {
value->clear();
const char* valueToken;
for (Vector<String8>::const_iterator nextToken = mTokens.begin();
nextToken != mTokens.end(); ++nextToken) {
if (0 == (*nextToken).compare(key)) {
if (nextToken + 1 == mTokens.end())
break;
valueToken = (*(nextToken + 1)).string();
value->setTo(valueToken);
nextToken++;
break;
}
}
}
/*
* Parses a JSON objects string and initializes a vector of tokens.
*
* @return Returns false for errors, true for success.
*/
bool JsonAssetLoader::parseJsonObject(const String8& jsonObject,
Vector<String8>* tokens) {
jsmn_parser parser;
jsmn_init(&parser);
int numTokens = jsmn_parse(&parser,
jsonObject.string(), jsonObject.size(), NULL, 0);
if (numTokens < 0) {
ALOGE("Parser returns error code=%d", numTokens);
return false;
}
unsigned int jsmnTokensSize = numTokens * sizeof(jsmntok_t);
mJsmnTokens.clear();
mJsmnTokens.setCapacity(jsmnTokensSize);
jsmn_init(&parser);
int status = jsmn_parse(&parser, jsonObject.string(),
jsonObject.size(), mJsmnTokens.editArray(), numTokens);
if (status < 0) {
ALOGE("Parser returns error code=%d", status);
return false;
}
tokens->clear();
String8 token;
const char *pjs;
ALOGV("numTokens: %d", numTokens);
for (int j = 0; j < numTokens; ++j) {
pjs = jsonObject.string() + mJsmnTokens[j].start;
if (mJsmnTokens[j].type == JSMN_STRING ||
mJsmnTokens[j].type == JSMN_PRIMITIVE) {
token.setTo(pjs, mJsmnTokens[j].end - mJsmnTokens[j].start);
tokens->add(token);
ALOGV("add token: %s", token.string());
}
}
return true;
}
/*
* Parses JSON asset string and initializes a vector of JSON objects.
*
* @return Returns false for errors, true for success.
*/
bool JsonAssetLoader::parseJsonAssetString(const String8& jsonAsset,
Vector<String8>* jsonObjects) {
if (jsonAsset.isEmpty()) {
ALOGE("Empty JSON Web Key");
return false;
}
// The jsmn parser only supports unicode encoding.
jsmn_parser parser;
// Computes number of tokens. A token marks the type, offset in
// the original string.
jsmn_init(&parser);
int numTokens = jsmn_parse(&parser,
jsonAsset.string(), jsonAsset.size(), NULL, 0);
if (numTokens < 0) {
ALOGE("Parser returns error code=%d", numTokens);
return false;
}
unsigned int jsmnTokensSize = numTokens * sizeof(jsmntok_t);
mJsmnTokens.setCapacity(jsmnTokensSize);
jsmn_init(&parser);
int status = jsmn_parse(&parser, jsonAsset.string(),
jsonAsset.size(), mJsmnTokens.editArray(), numTokens);
if (status < 0) {
ALOGE("Parser returns error code=%d", status);
return false;
}
String8 token;
const char *pjs;
for (int i = 0; i < numTokens; ++i) {
pjs = jsonAsset.string() + mJsmnTokens[i].start;
if (mJsmnTokens[i].type == JSMN_OBJECT) {
token.setTo(pjs, mJsmnTokens[i].end - mJsmnTokens[i].start);
jsonObjects->add(token);
}
}
return true;
}
} // namespace clearkeycas
} // namespace android