1/*
2 * Copyright (C) 2018 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17//#define LOG_NDEBUG 0
18#define LOG_TAG "hidl_InitDataParser"
19
20#include <algorithm>
21#include <utils/Log.h>
22
23#include "InitDataParser.h"
24
25#include "Base64.h"
26
27#include "ClearKeyUUID.h"
28#include "MimeType.h"
29#include "Utils.h"
30
31namespace android {
32namespace hardware {
33namespace drm {
34namespace V1_1 {
35namespace clearkey {
36
37namespace {
38    const size_t kKeyIdSize = 16;
39    const size_t kSystemIdSize = 16;
40}
41
42std::vector<uint8_t> StrToVector(const std::string& str) {
43    std::vector<uint8_t> vec(str.begin(), str.end());
44    return vec;
45}
46
47Status InitDataParser::parse(const std::vector<uint8_t>& initData,
48        const std::string& type,
49        std::vector<uint8_t>* licenseRequest) {
50    // Build a list of the key IDs
51    std::vector<const uint8_t*> keyIds;
52
53    if (type == kIsoBmffVideoMimeType ||
54        type == kIsoBmffAudioMimeType ||
55        type == kCencInitDataFormat) {
56        Status res = parsePssh(initData, &keyIds);
57        if (res != Status::OK) {
58            return res;
59        }
60    } else if (type == kWebmVideoMimeType ||
61        type == kWebmAudioMimeType ||
62        type == kWebmInitDataFormat) {
63        // WebM "init data" is just a single key ID
64        if (initData.size() != kKeyIdSize) {
65            return Status::ERROR_DRM_CANNOT_HANDLE;
66        }
67        keyIds.push_back(initData.data());
68    } else {
69        return Status::ERROR_DRM_CANNOT_HANDLE;
70    }
71
72    // Build the request
73    std::string requestJson = generateRequest(keyIds);
74    std::vector<uint8_t> requestJsonVec = StrToVector(requestJson);
75
76    licenseRequest->clear();
77    licenseRequest->insert(licenseRequest->end(), requestJsonVec.begin(), requestJsonVec.end());
78    return Status::OK;
79}
80
81Status InitDataParser::parsePssh(const std::vector<uint8_t>& initData,
82        std::vector<const uint8_t*>* keyIds) {
83    size_t readPosition = 0;
84
85    // Validate size field
86    uint32_t expectedSize = initData.size();
87    expectedSize = htonl(expectedSize);
88    if (memcmp(&initData[readPosition], &expectedSize,
89               sizeof(expectedSize)) != 0) {
90        return Status::ERROR_DRM_CANNOT_HANDLE;
91    }
92    readPosition += sizeof(expectedSize);
93
94    // Validate PSSH box identifier
95    const char psshIdentifier[4] = {'p', 's', 's', 'h'};
96    if (memcmp(&initData[readPosition], psshIdentifier,
97               sizeof(psshIdentifier)) != 0) {
98        return Status::ERROR_DRM_CANNOT_HANDLE;
99    }
100    readPosition += sizeof(psshIdentifier);
101
102    // Validate EME version number
103    const uint8_t psshVersion1[4] = {1, 0, 0, 0};
104    if (memcmp(&initData[readPosition], psshVersion1,
105               sizeof(psshVersion1)) != 0) {
106        return Status::ERROR_DRM_CANNOT_HANDLE;
107    }
108    readPosition += sizeof(psshVersion1);
109
110    // Validate system ID
111    if (!clearkeydrm::isClearKeyUUID(&initData[readPosition])) {
112        return Status::ERROR_DRM_CANNOT_HANDLE;
113    }
114    readPosition += kSystemIdSize;
115
116    // Read key ID count
117    uint32_t keyIdCount;
118    memcpy(&keyIdCount, &initData[readPosition], sizeof(keyIdCount));
119    keyIdCount = ntohl(keyIdCount);
120    readPosition += sizeof(keyIdCount);
121    if (readPosition + ((uint64_t)keyIdCount * kKeyIdSize) !=
122            initData.size() - sizeof(uint32_t)) {
123        return Status::ERROR_DRM_CANNOT_HANDLE;
124    }
125
126    // Calculate the key ID offsets
127    for (uint32_t i = 0; i < keyIdCount; ++i) {
128        size_t keyIdPosition = readPosition + (i * kKeyIdSize);
129        keyIds->push_back(&initData[keyIdPosition]);
130    }
131    return Status::OK;
132}
133
134std::string InitDataParser::generateRequest(const std::vector<const uint8_t*>& keyIds) {
135    const std::string kRequestPrefix("{\"kids\":[");
136    const std::string kRequestSuffix("],\"type\":\"temporary\"}");
137
138    std::string request(kRequestPrefix);
139    std::string encodedId;
140    for (size_t i = 0; i < keyIds.size(); ++i) {
141        encodedId.clear();
142        encodeBase64Url(keyIds[i], kKeyIdSize, &encodedId);
143        if (i != 0) {
144            request.append(",");
145        }
146        request.push_back('\"');
147        request.append(encodedId);
148        request.push_back('\"');
149    }
150    request.append(kRequestSuffix);
151
152    // Android's Base64 encoder produces padding. EME forbids padding.
153    const char kBase64Padding = '=';
154    request.erase(std::remove(request.begin(), request.end(), kBase64Padding), request.end());
155
156    return request;
157}
158
159} // namespace clearkey
160} // namespace V1_1
161} // namespace drm
162} // namespace hardware
163} // namespace android
164