Use Jsmn to parse json data

[ Merge of http://go/wvgerrit/16628 ]

Jsmn will replace a local method that parsed json init data.
Added a fix to include all key Ids in the WidevineCencHeader rather than
just the first. Also modified the content_id to reflect that it is a
base64 encoded value.

b/20630275

Change-Id: I7080c8cea21be4dea09a4905a96b4cc03e584c1d

libwvdrmengine/Android.mk

@@ -85,6 +85,7 @@ LOCAL_STATIC_LIBRARIES := \
   libcdm \
   libcdm_utils \
   libcrypto_static \
+  libjsmn \
   libwvlevel3 \
   libwvdrmcryptoplugin \
   libwvdrmdrmplugin \

libwvdrmengine/cdm/Android.mk

@@ -12,7 +12,8 @@ LOCAL_C_INCLUDES := \
     vendor/widevine/libwvdrmengine/third_party/stringencoders/src
 
 LOCAL_C_INCLUDES += \
-    external/protobuf/src
+    external/jsmn \
+    external/protobuf/src \
 
 LOCAL_STATIC_LIBRARIES := libcdm_protos libcrypto_static
 

libwvdrmengine/cdm/core/include/initialization_data.h

@@ -47,8 +47,6 @@ class InitializationData {
                                   std::vector<uint8_t>* value);
   static bool ExtractAttribute(const std::string& attribute_list,
                                const std::string& key, std::string* value);
-  static bool ExtractJsonValue(const std::string& json,
-                               const std::string& key, std::string* value);
 
   static std::vector<std::string> ExtractKeyFormatVersions(
       const std::string& key_format_versions);

libwvdrmengine/cdm/core/src/initialization_data.cpp

@@ -5,6 +5,7 @@
 #include <string.h>
 
 #include "buffer_reader.h"
+#include "jsmn.h"
 #include "license_protocol.pb.h"
 #include "log.h"
 #include "properties.h"
@@ -23,6 +24,9 @@ const std::string kBase64String = "base64,";
 const std::string kProvider = "provider";
 const std::string kContentId = "content_id";
 const std::string kKeyIds = "key_ids";
+
+// Being conservative, usually we expect 6 + number of Key Ids
+const int kDefaultNumJsonTokens = 128;
 }  // namespace
 
 namespace wvcdm {
@@ -319,7 +323,7 @@ bool InitializationData::ExtractHlsAttributes(const std::string& attribute_list,
 //
 // {
 //   "provider":"mlbamhbo",
-//   "content_id":"2015_Tears",
+//   "content_id":"MjAxNV9UZWFycw==",
 //   "key_ids":
 //   [
 //     "371e135e1a985d75d198a7f41020dc23"
@@ -352,44 +356,110 @@ bool InitializationData::ConstructWidevineInitData(
   std::string json_string((const char*)(&json_init_data[0]),
                           json_init_data.size());
 
-  // Parse json data
+  // Parse the Json string using jsmn
+  int result = 0;
+  jsmn_parser parser;
+  jsmntok_t tokens[kDefaultNumJsonTokens];
+  jsmn_init(&parser);
+  int num_of_tokens =
+      jsmn_parse(&parser, json_string.c_str(), json_string.size(), tokens,
+                 kDefaultNumJsonTokens);
+
+  if (num_of_tokens <= 0) {
+    LOGV(
+        "InitializationData::ConstructWidevineInitData: Json parsing failed: "
+        "%d",
+        num_of_tokens);
+    return false;
+  }
+
   std::string provider;
-  if (!ExtractJsonValue(json_string, kProvider, &provider)) {
-    LOGV(
-        "InitializationData::ConstructWidevineInitData: Unable to extract "
-        "provider value");
-    return false;
-  }
-
   std::string content_id;
-  if (!ExtractJsonValue(json_string, kContentId, &content_id)) {
-    LOGV(
-        "InitializationData::ConstructWidevineInitData: Unable to extract "
-        "content_id value");
+  std::vector<std::string> key_ids;
+
+  enum JsmnParserState {
+    kParseState,
+    kProviderState,
+    kContentIdState,
+    kKeyIdsState,
+  } state = kParseState;
+
+  int number_of_key_ids = 0;
+
+  // Extract the provider, content_id and key_ids
+  for (int i = 0; i < num_of_tokens; ++i) {
+    if (tokens[i].start < 0 || tokens[i].end < 0) {
+      LOGV(
+          "InitializationData::ConstructWidevineInitData: Invalid start or end "
+          "of token");
+      return false;
+    }
+
+    switch (state) {
+      case kParseState:
+        if (tokens[i].type == JSMN_STRING) {
+          std::string token(json_string, tokens[i].start,
+                            tokens[i].end - tokens[i].start);
+          if (token == kProvider) {
+            state = kProviderState;
+          } else if (token == kContentId) {
+            state = kContentIdState;
+          } else if (token == kKeyIds) {
+            state = kKeyIdsState;
+          }
+        }
+        break;
+      case kProviderState:
+        if (tokens[i].type == JSMN_STRING) {
+          provider.assign(json_string, tokens[i].start,
+                          tokens[i].end - tokens[i].start);
+        }
+        state = kParseState;
+        break;
+      case kContentIdState:
+        if (tokens[i].type == JSMN_STRING) {
+          content_id.assign(json_string, tokens[i].start,
+                            tokens[i].end - tokens[i].start);
+        }
+        state = kParseState;
+        break;
+      case kKeyIdsState:
+        if (tokens[i].type == JSMN_ARRAY) {
+          number_of_key_ids = tokens[i].size;
+        } else if (tokens[i].type == JSMN_STRING) {
+          std::string key_id(a2bs_hex(json_string.substr(
+              tokens[i].start, tokens[i].end - tokens[i].start)));
+          if (key_id.size() == 16) key_ids.push_back(key_id);
+          --number_of_key_ids;
+        } else {
+          state = kParseState;
+        }
+        if (number_of_key_ids <= 0) state = kParseState;
+        break;
+    }
+  }
+
+  if (provider.size() == 0) {
+    LOGV("InitializationData::ConstructWidevineInitData: Invalid provider");
     return false;
   }
 
-  std::string key_id;
-  if (!ExtractJsonValue(json_string, kKeyIds, &key_id)) {
-    LOGV(
-        "InitializationData::ConstructWidevineInitData: Unable to extract "
-        "key_id values");
+  if (content_id.size() == 0) {
+    LOGV("InitializationData::ConstructWidevineInitData: Invalid content_id");
     return false;
   }
 
-  key_id = a2bs_hex(key_id);
-  if (key_id.size() != 16) {
-    LOGV(
-        "InitializationData::ConstructWidevineInitData: Invalid key_id size: "
-        "%ld",
-        key_id.size());
+  if (key_ids.size() == 0) {
+    LOGV("InitializationData::ConstructWidevineInitData: No key_ids present");
     return false;
   }
 
   // Now format as Widevine init data protobuf
   WidevineCencHeader cenc_header;
   cenc_header.set_algorithm(WidevineCencHeader_Algorithm_AESCTR);
-  cenc_header.add_key_id(key_id);
+  for (size_t i = 0; i < key_ids.size(); ++i) {
+    cenc_header.add_key_id(key_ids[i]);
+  }
   cenc_header.set_provider(provider);
   cenc_header.set_content_id(content_id);
   cenc_header.SerializeToString(init_data_proto);
@@ -470,45 +540,6 @@ bool InitializationData::ExtractAttribute(const std::string& attribute_list,
   return true;
 }
 
-bool InitializationData::ExtractJsonValue(const std::string& json,
-                                          const std::string& key,
-                                          std::string* value) {
-  std::string quoted_key = key;
-  quoted_key.insert(0, 1, kDoubleQuote);
-  quoted_key.append(1, kDoubleQuote);
-
-  bool found = false;
-  size_t pos = 0;
-  // Find the key followed by ':'
-  while (!found) {
-    pos = json.find(quoted_key, pos);
-    if (pos == std::string::npos) return false;
-    pos += quoted_key.size();
-    while (pos < json.size() && isspace(json[pos])) ++pos;
-    if (pos >= json.size()) return false;
-    if (json[pos] != kColon) continue;
-    found = true;
-  }
-
-  ++pos;
-  while (pos < json.size() && isspace(json[pos])) ++pos;
-  if (pos >= json.size()) return false;
-
-  if (json[pos] == kLeftBracket) {
-    ++pos;
-    while (pos < json.size() && isspace(json[pos])) ++pos;
-    if (pos >= json.size()) return false;
-  }
-
-  if (json[pos] != kDoubleQuote) return false;
-  ++pos;
-  size_t end_pos = json.find(kDoubleQuote, pos);
-  if (end_pos == std::string::npos) return false;
-  --end_pos;
-  *value = json.substr(pos, end_pos - pos + 1);
-  return true;
-}
-
 // Key format versions are individual values or multiple versions
 // separated by '/'. "1" or "1/2/5"
 std::vector<std::string> InitializationData::ExtractKeyFormatVersions(

libwvdrmengine/cdm/core/test/initialization_data_unittest.cpp

@@ -180,7 +180,7 @@ const std::string kHlsTestInvalidHexValue = kHlsIvHexValue + "g7";
 char kHlsTestKeyFormatVersionsSeparator = '/';
 const std::string kHlsTestUriDataFormat = "data:text/plain;base64,";
 const std::string kHlsTestProvider = "youtube";
-const std::string kHlsTestContentId = "Tears_2015";
+const std::string kHlsTestContentId = "MjAxNV9UZWFycw==";
 const std::string kHlsTestKeyId1 = "371E135E1A985D75D198A7F41020DC23";
 const std::string kHlsTestKeyId2 = "E670D9B60AE61583E01BC9253FA19261";
 const std::string kHlsTestKeyId3 = "78094E72165DF39721B8A354D6A71390";
@@ -594,7 +594,17 @@ TEST_P(HlsConstructionTest, InitData) {
     EXPECT_TRUE(cenc_header.ParseFromString(value));
     EXPECT_EQ(video_widevine_server::sdk::WidevineCencHeader_Algorithm_AESCTR,
               cenc_header.algorithm());
-    EXPECT_EQ(param.key_ids_[0], b2a_hex(cenc_header.key_id(0)));
+    for (size_t i = 0; i < param.key_ids_.size(); ++i) {
+      bool key_id_found = false;
+      if (param.key_ids_[i].size() != 32) continue;
+      for (int j = 0; j < cenc_header.key_id_size(); ++j) {
+        if (param.key_ids_[i] == b2a_hex(cenc_header.key_id(j))) {
+          key_id_found = true;
+          break;
+        }
+      }
+      EXPECT_TRUE(key_id_found);
+    }
     EXPECT_EQ(param.provider_, cenc_header.provider());
     EXPECT_EQ(param.content_id_, cenc_header.content_id());
   } else {
@@ -617,7 +627,7 @@ INSTANTIATE_TEST_CASE_P(
             .AddKeyId(kHlsTestKeyId2)
             .AddKeyId(kHlsTestKeyId3),
         HlsInitDataVariant(kHlsTestProvider, kHlsTestContentId,
-                           kHlsTestInvalidKeyId, false)
+                           kHlsTestInvalidKeyId, true)
             .AddKeyId(kHlsTestKeyId1)));
 
 TEST_F(HlsInitDataConstructionTest, InvalidUriDataFormat) {

libwvdrmengine/cdm/test/unit-test.mk

@@ -34,12 +34,13 @@ LOCAL_C_INCLUDES += external/protobuf/src
 LOCAL_STATIC_LIBRARIES := \
     libcdm \
     libcdm_protos \
+    libcdm_utils \
     libcrypto_static \
-    libwvgmock \
+    libjsmn \
     libgtest \
     libgtest_main \
+    libwvgmock \
     libwvlevel3 \
-    libcdm_utils \
 
 LOCAL_SHARED_LIBRARIES := \
     libcutils \

libwvdrmengine/mediacrypto/test/Android.mk

@@ -19,6 +19,7 @@ LOCAL_STATIC_LIBRARIES := \
   libcdm_protos \
   libcdm_utils \
   libcrypto_static \
+  libjsmn \
   libwvgmock \
   libwvgmock_main \
   libgtest \

libwvdrmengine/mediadrm/test/Android.mk

@@ -21,9 +21,10 @@ LOCAL_STATIC_LIBRARIES := \
   libcdm_protos \
   libcdm_utils \
   libcrypto_static \
+  libjsmn \
+  libgtest \
   libwvgmock \
   libwvgmock_main \
-  libgtest \
   libwvlevel3 \
   libwvdrmdrmplugin \