Merge pull request open-source-parsers#205 from open-source-parsers/reject-dup-keys

[Shekhar (shakers007) wrote](https://sourceforge.net/p/jsoncpp/bugs/22/):

> As per RFC4627 (section 2.2), names within an object should be unique. When using JSONCPP's strict mode, parsing such an object should fail.

Author: cdunn2001

include/json/reader.h

@@ -320,6 +320,8 @@ class JSON_API CharReaderBuilder : public CharReader::Factory {
     - `"failIfExtra": false or true`
       - If true, `parse()` returns false when extra non-whitespace trails
         the JSON value in the input string.
+    - `"rejectDupKeys": false or true`
+      - If true, `parse()` returns false when a key is duplicated within an object.
 
     You can examine 'settings_` yourself
     to see the defaults. You can also write and read them just like any

src/lib_json/json_reader.cpp

@@ -916,6 +916,7 @@ class OurFeatures {
   bool allowNumericKeys_;
   bool allowSingleQuotes_;
   bool failIfExtra_;
+  bool rejectDupKeys_;
   int stackLimit_;
 };  // OurFeatures
 
@@ -1431,6 +1432,11 @@ bool OurReader::readObject(Token& tokenStart) {
           "Missing ':' after object member name", colon, tokenObjectEnd);
     }
     if (name.length() >= (1U<<30)) throw std::runtime_error("keylength >= 2^30");
+    if (features_.rejectDupKeys_ && currentValue().isMember(name)) {
+      std::string msg = "Duplicate key: '" + name + "'";
+      return addErrorAndRecover(
+          msg, tokenName, tokenObjectEnd);
+    }
     Value& value = currentValue()[name];
     nodes_.push(&value);
     bool ok = readValue();
@@ -1896,6 +1902,7 @@ CharReader* CharReaderBuilder::newCharReader() const
   features.allowSingleQuotes_ = settings_["allowSingleQuotes"].asBool();
   features.stackLimit_ = settings_["stackLimit"].asInt();
   features.failIfExtra_ = settings_["failIfExtra"].asBool();
+  features.rejectDupKeys_ = settings_["rejectDupKeys"].asBool();
   return new OurCharReader(collectComments, features);
 }
 static void getValidReaderKeys(std::set<std::string>* valid_keys)
@@ -1909,6 +1916,7 @@ static void getValidReaderKeys(std::set<std::string>* valid_keys)
   valid_keys->insert("allowSingleQuotes");
   valid_keys->insert("stackLimit");
   valid_keys->insert("failIfExtra");
+  valid_keys->insert("rejectDupKeys");
 }
 bool CharReaderBuilder::validate(Json::Value* invalid) const
 {
@@ -1941,6 +1949,7 @@ void CharReaderBuilder::strictMode(Json::Value* settings)
   (*settings)["allowNumericKeys"] = false;
   (*settings)["allowSingleQuotes"] = false;
   (*settings)["failIfExtra"] = true;
+  (*settings)["rejectDupKeys"] = true;
 //! [CharReaderBuilderStrictMode]
 }
 // static
@@ -1955,6 +1964,7 @@ void CharReaderBuilder::setDefaults(Json::Value* settings)
   (*settings)["allowSingleQuotes"] = false;
   (*settings)["stackLimit"] = 1000;
   (*settings)["failIfExtra"] = false;
+  (*settings)["rejectDupKeys"] = false;
 //! [CharReaderBuilderDefaults]
 }
 

src/test_lib_json/main.cpp

@@ -1884,6 +1884,29 @@ JSONTEST_FIXTURE(CharReaderTest, parseWithStackLimit) {
   }
 }
 
+struct CharReaderStrictModeTest : JsonTest::TestCase {};
+
+JSONTEST_FIXTURE(CharReaderStrictModeTest, dupKeys) {
+  Json::CharReaderBuilder b;
+  Json::Value root;
+  char const doc[] =
+      "{ \"property\" : \"value\", \"key\" : \"val1\", \"key\" : \"val2\" }";
+  {
+    b.strictMode(&b.settings_);
+    Json::CharReader* reader(b.newCharReader());
+    std::string errs;
+    bool ok = reader->parse(
+        doc, doc + std::strlen(doc),
+        &root, &errs);
+    JSONTEST_ASSERT(!ok);
+    JSONTEST_ASSERT_STRING_EQUAL(
+        "* Line 1, Column 41\n"
+        "  Duplicate key: 'key'\n",
+        errs);
+    JSONTEST_ASSERT_EQUAL("val1", root["key"]); // so far
+    delete reader;
+  }
+}
 struct CharReaderFailIfExtraTest : JsonTest::TestCase {};
 
 JSONTEST_FIXTURE(CharReaderFailIfExtraTest, issue164) {
@@ -2305,6 +2328,8 @@ int main(int argc, const char* argv[]) {
   JSONTEST_REGISTER_FIXTURE(runner, CharReaderTest, parseWithDetailError);
   JSONTEST_REGISTER_FIXTURE(runner, CharReaderTest, parseWithStackLimit);
 
+  JSONTEST_REGISTER_FIXTURE(runner, CharReaderStrictModeTest, dupKeys);
+
   JSONTEST_REGISTER_FIXTURE(runner, CharReaderFailIfExtraTest, issue164);
   JSONTEST_REGISTER_FIXTURE(runner, CharReaderFailIfExtraTest, issue107);
   JSONTEST_REGISTER_FIXTURE(runner, CharReaderFailIfExtraTest, commentAfterObject);