| /* | |
| * AWS IoT Common V1.0.0 | |
| * Copyright (C) 2018 Amazon.com, Inc. or its affiliates. All Rights Reserved. | |
| * | |
| * Permission is hereby granted, free of charge, to any person obtaining a copy of | |
| * this software and associated documentation files (the "Software"), to deal in | |
| * the Software without restriction, including without limitation the rights to | |
| * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of | |
| * the Software, and to permit persons to whom the Software is furnished to do so, | |
| * subject to the following conditions: | |
| * | |
| * The above copyright notice and this permission notice shall be included in all | |
| * copies or substantial portions of the Software. | |
| * | |
| * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR | |
| * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS | |
| * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR | |
| * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER | |
| * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN | |
| * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. | |
| */ | |
| /** | |
| * @file aws_iot_doc_parser.c | |
| * @brief Implements the functions in aws_iot_doc_parser.h | |
| */ | |
| /* The config header is always included first. */ | |
| #include "iot_config.h" | |
| /* Standard includes. */ | |
| #include <string.h> | |
| /* JSON utilities include. */ | |
| #include "aws_iot_doc_parser.h" | |
| #define IS_QUOTE( str, idx ) \ | |
| ( ( str )[ ( idx ) ] == '"' && ( ( idx ) == 0 || ( str )[ ( idx ) - 1 ] != '\\' ) ) | |
| #define IS_WHITESPACE( str, idx ) \ | |
| ( ( str )[ ( idx ) ] == ' ' || ( str )[ ( idx ) ] == '\n' || ( str )[ ( idx ) ] == '\r' || ( str )[ ( idx ) ] == '\t' ) | |
| /*-----------------------------------------------------------*/ | |
| bool AwsIotDocParser_FindValue( const char * pAwsIotJsonDocument, | |
| size_t awsIotJsonDocumentLength, | |
| const char * pAwsIotJsonKey, | |
| size_t awsIotJsonKeyLength, | |
| const char ** pAwsIotJsonValue, | |
| size_t * pAwsIotJsonValueLength ) | |
| { | |
| size_t i = 0; | |
| size_t jsonValueLength = 0; | |
| char openCharacter = '\0', closeCharacter = '\0'; | |
| int nestingLevel = 0; | |
| bool isWithinQuotes = false; | |
| /* Validate all the arguments.*/ | |
| if( ( pAwsIotJsonDocument == NULL ) || ( pAwsIotJsonKey == NULL ) || | |
| ( awsIotJsonDocumentLength == 0 ) || ( awsIotJsonKeyLength == 0 ) ) | |
| { | |
| return false; | |
| } | |
| /* Ensure the JSON document is long enough to contain the key/value pair. At | |
| * the very least, a JSON key/value pair must contain the key and the 6 | |
| * characters {":""} */ | |
| if( awsIotJsonDocumentLength < awsIotJsonKeyLength + 6 ) | |
| { | |
| return false; | |
| } | |
| /* Search the characters in the JSON document for the key. The end of the JSON | |
| * document does not have to be searched once too few characters remain to hold a | |
| * value. */ | |
| while( i < awsIotJsonDocumentLength - awsIotJsonKeyLength - 3 ) | |
| { | |
| /* If the first character in the key is found and there's an unescaped double | |
| * quote after the key length, do a string compare for the key. */ | |
| if( ( IS_QUOTE( pAwsIotJsonDocument, i ) ) && | |
| ( IS_QUOTE( pAwsIotJsonDocument, i + 1 + awsIotJsonKeyLength ) ) && | |
| ( pAwsIotJsonDocument[ i + 1 ] == pAwsIotJsonKey[ 0 ] ) && | |
| ( strncmp( pAwsIotJsonDocument + i + 1, | |
| pAwsIotJsonKey, | |
| awsIotJsonKeyLength ) == 0 ) ) | |
| { | |
| /* Key found; this is a potential match. */ | |
| /* Skip the characters in the JSON key and closing double quote. */ | |
| /* While loop guarantees that i < awsIotJsonDocumentLength - 1 */ | |
| i += awsIotJsonKeyLength + 2; | |
| /* Skip all whitespace characters between the closing " and the : */ | |
| while( IS_WHITESPACE( pAwsIotJsonDocument, i ) ) | |
| { | |
| i++; | |
| /* If the end of the document is reached, this isn't a match. */ | |
| if( i >= awsIotJsonDocumentLength ) | |
| { | |
| return false; | |
| } | |
| } | |
| /* The character immediately following a key (and any whitespace) must be a : | |
| * If it's another character, then this string is a JSON value; skip it. */ | |
| if( pAwsIotJsonDocument[ i ] != ':' ) | |
| { | |
| continue; | |
| } | |
| else | |
| { | |
| /* Skip the : */ | |
| i++; | |
| } | |
| /* If the end of the document is reached, this isn't a match. */ | |
| if( i >= awsIotJsonDocumentLength ) | |
| { | |
| return false; | |
| } | |
| /* Skip all whitespace characters between : and the first character in the value. */ | |
| while( IS_WHITESPACE( pAwsIotJsonDocument, i ) ) | |
| { | |
| i++; | |
| /* If the end of the document is reached, this isn't a match. */ | |
| if( i >= awsIotJsonDocumentLength ) | |
| { | |
| return false; | |
| } | |
| } | |
| /* Value found. Set the output parameter. */ | |
| if( pAwsIotJsonValue != NULL ) | |
| { | |
| *pAwsIotJsonValue = pAwsIotJsonDocument + i; | |
| } | |
| /* Calculate the value's length. */ | |
| switch( pAwsIotJsonDocument[ i ] ) | |
| { | |
| /* Calculate length of a JSON string. */ | |
| case '\"': | |
| /* Include the length of the opening and closing double quotes. */ | |
| jsonValueLength = 2; | |
| /* Skip the opening double quote. */ | |
| i++; | |
| /* If the end of the document is reached, this isn't a match. */ | |
| if( i >= awsIotJsonDocumentLength ) | |
| { | |
| return false; | |
| } | |
| /* Add the length of all characters in the JSON string. */ | |
| while( pAwsIotJsonDocument[ i ] != '\"' ) | |
| { | |
| /* Ignore escaped double quotes. */ | |
| if( ( pAwsIotJsonDocument[ i ] == '\\' ) && | |
| ( i + 1 < awsIotJsonDocumentLength ) && | |
| ( pAwsIotJsonDocument[ i + 1 ] == '\"' ) ) | |
| { | |
| /* Skip the characters \" */ | |
| i += 2; | |
| jsonValueLength += 2; | |
| } | |
| else | |
| { | |
| /* Add the length of a single character. */ | |
| i++; | |
| jsonValueLength++; | |
| } | |
| /* If the end of the document is reached, this isn't a match. */ | |
| if( i >= awsIotJsonDocumentLength ) | |
| { | |
| return false; | |
| } | |
| } | |
| break; | |
| /* Set the matching opening and closing characters of a JSON object or array. | |
| * The length calculation is performed below. */ | |
| case '{': | |
| openCharacter = '{'; | |
| closeCharacter = '}'; | |
| break; | |
| case '[': | |
| openCharacter = '['; | |
| closeCharacter = ']'; | |
| break; | |
| /* Calculate the length of a JSON primitive. */ | |
| default: | |
| /* Skip the characters in the JSON value. The JSON value ends with a , or } */ | |
| while( pAwsIotJsonDocument[ i ] != ',' && | |
| pAwsIotJsonDocument[ i ] != '}' ) | |
| { | |
| /* Any whitespace before a , or } means the JSON document is invalid. */ | |
| if( IS_WHITESPACE( pAwsIotJsonDocument, i ) ) | |
| { | |
| return false; | |
| } | |
| i++; | |
| jsonValueLength++; | |
| /* If the end of the document is reached, this isn't a match. */ | |
| if( i >= awsIotJsonDocumentLength ) | |
| { | |
| return false; | |
| } | |
| } | |
| break; | |
| } | |
| /* Calculate the length of a JSON object or array. */ | |
| if( ( openCharacter != '\0' ) && ( closeCharacter != '\0' ) ) | |
| { | |
| /* Include the length of the opening and closing characters. */ | |
| jsonValueLength = 2; | |
| /* Skip the opening character. */ | |
| i++; | |
| /* If the end of the document is reached, this isn't a match. */ | |
| if( i >= awsIotJsonDocumentLength ) | |
| { | |
| return false; | |
| } | |
| /* Add the length of all characters in the JSON object or array. This | |
| * includes the length of nested objects. */ | |
| while( pAwsIotJsonDocument[ i ] != closeCharacter || | |
| ( pAwsIotJsonDocument[ i ] == closeCharacter && ( nestingLevel != 0 || isWithinQuotes ) ) ) | |
| { | |
| /* Check if its a quote so as to avoid considering the | |
| * nested levels for opening and closing characters within | |
| * quotes. | |
| */ | |
| if( IS_QUOTE( pAwsIotJsonDocument, i ) ) | |
| { | |
| /*Toggle the flag*/ | |
| isWithinQuotes = !isWithinQuotes; | |
| } | |
| /* Calculate the nesting levels only if not in quotes. */ | |
| if( !isWithinQuotes ) | |
| { | |
| /* An opening character starts a nested object. */ | |
| if( pAwsIotJsonDocument[ i ] == openCharacter ) | |
| { | |
| nestingLevel++; | |
| } | |
| /* A closing character ends a nested object. */ | |
| else if( pAwsIotJsonDocument[ i ] == closeCharacter ) | |
| { | |
| nestingLevel--; | |
| } | |
| } | |
| i++; | |
| jsonValueLength++; | |
| /* If the end of the document is reached, this isn't a match. */ | |
| if( i >= awsIotJsonDocumentLength ) | |
| { | |
| return false; | |
| } | |
| } | |
| } | |
| /* JSON value length calculated; set the output parameter. */ | |
| if( pAwsIotJsonValueLength != NULL ) | |
| { | |
| *pAwsIotJsonValueLength = jsonValueLength; | |
| } | |
| return true; | |
| } | |
| i++; | |
| } | |
| return false; | |
| } | |
| /*-----------------------------------------------------------*/ |