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
31 namespace android {
32 namespace hardware {
33 namespace drm {
34 namespace V1_1 {
35 namespace clearkey {
36
37 namespace {
38 const size_t kKeyIdSize = 16;
39 const size_t kSystemIdSize = 16;
40 }
41
StrToVector(const std::string & str)42 std::vector<uint8_t> StrToVector(const std::string& str) {
43 std::vector<uint8_t> vec(str.begin(), str.end());
44 return vec;
45 }
46
parse(const std::vector<uint8_t> & initData,const std::string & type,std::vector<uint8_t> * licenseRequest)47 Status 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
parsePssh(const std::vector<uint8_t> & initData,std::vector<const uint8_t * > * keyIds)81 Status 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
generateRequest(const std::vector<const uint8_t * > & keyIds)134 std::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