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Implemented Json to Tlv and Tlv to Json Converter in Kotlin
Note that NOT all TLV configurations are supported by the current implementation. Here is the list of limitations: - TLV Lists are not supported - Multi-Dimensional TLV Arrays are not supported - All elements of an array MUST be of the same type - The top level TLV element MUST be a single structure with AnonymousTag - The following tags are supported: - AnonymousTag are used only with TLV Arrays elements or a top-level structure - ContextSpecificTag are used only with TLV Structure elements - CommonProfileTag are used only with TLV Structure elements - Infinity Float/Double values are not supported
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/* | ||
* | ||
* Copyright (c) 2023 Project CHIP Authors | ||
* Copyright (c) 2023 Google LLC. | ||
* | ||
* Licensed under the Apache License, Version 2.0 (the "License"); | ||
* you may not use this file except in compliance with the License. | ||
* You may obtain a copy of the License at | ||
* | ||
* http://www.apache.org/licenses/LICENSE-2.0 | ||
* | ||
* Unless required by applicable law or agreed to in writing, software | ||
* distributed under the License is distributed on an "AS IS" BASIS, | ||
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | ||
* See the License for the specific language governing permissions and | ||
* limitations under the License. | ||
*/ | ||
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package chip.json | ||
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import com.google.gson.JsonArray | ||
import com.google.gson.JsonElement | ||
import com.google.gson.JsonObject | ||
import com.google.gson.JsonParser | ||
import com.google.protobuf.ByteString | ||
import java.util.Base64 | ||
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/** | ||
* Implements Matter JSON to TLV converter. | ||
* | ||
* Note that NOT all TLV configurations are supported by the current implementation. Below is the | ||
* list of limitations: | ||
* - TLV Lists are not supported | ||
* - Multi-Dimensional TLV Arrays are not supported | ||
* - All elements of an array MUST be of the same type | ||
* - The top level TLV element MUST be a single structure with AnonymousTag | ||
* - The following tags are supported: | ||
* - AnonymousTag are used only with TLV Arrays elements or a top-level structure | ||
* - ContextSpecificTag are used only with TLV Structure elements | ||
* - CommonProfileTag are used only with TLV Structure elements | ||
* - Infinity Float/Double values are not supported | ||
* | ||
* @param json string representing Json encoded data to be converted into TLV format | ||
* @throws IllegalArgumentException if the data was invalid | ||
*/ | ||
fun TlvWriter.fromJsonString(json: String): ByteArray { | ||
validateIsJsonObjectAndConvert(JsonParser.parseString(json), AnonymousTag) | ||
return validateTlv().getEncoded() | ||
} | ||
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/** | ||
* Converts Json Object into TLV Structure or TLV top level elements. | ||
* | ||
* @param json object to be converted to TLV. | ||
* @throws IllegalArgumentException if the data was invalid | ||
*/ | ||
private fun TlvWriter.fromJson(json: JsonObject): TlvWriter { | ||
json.keySet().forEach { key -> | ||
val (tag, type, subType) = extractTagAndTypeFromJsonKey(key) | ||
fromJson(json.get(key), tag, type, subType) | ||
} | ||
return this | ||
} | ||
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/** | ||
* Converts Json Array into TLV Array. | ||
* | ||
* @param json object to be converted to TLV. | ||
* @param type Type of array elements. | ||
* @throws IllegalArgumentException if the data was invalid | ||
*/ | ||
private fun TlvWriter.fromJson(json: JsonArray, type: String): TlvWriter { | ||
json.iterator().forEach { element -> fromJson(element, AnonymousTag, type) } | ||
return this | ||
} | ||
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/** | ||
* Converts Json Element into TLV Array. | ||
* | ||
* @param element element to be converted to TLV. | ||
* @param tag element tag. | ||
* @param type element type. | ||
* @param subType array elements type. Only relevant when type is an Array. Should be empty string | ||
* in all other cases. | ||
* @throws IllegalArgumentException if the data was invalid | ||
*/ | ||
private fun TlvWriter.fromJson(element: JsonElement, tag: Tag, type: String, subType: String = "") { | ||
when (type) { | ||
JSON_VALUE_TYPE_INT -> put(tag, validateIsNumber(element).toLong()) | ||
JSON_VALUE_TYPE_UINT -> put(tag, validateIsNumber(element).toLong().toULong()) | ||
JSON_VALUE_TYPE_BOOL -> put(tag, validateIsBoolean(element)) | ||
JSON_VALUE_TYPE_FLOAT -> put(tag, validateIsDouble(element).toFloat()) | ||
JSON_VALUE_TYPE_DOUBLE -> put(tag, validateIsDouble(element)) | ||
JSON_VALUE_TYPE_BYTES -> put(tag, validateIsString(element).base64Encode()) | ||
JSON_VALUE_TYPE_STRING -> put(tag, validateIsString(element)) | ||
JSON_VALUE_TYPE_NULL -> validateIsNullAndPut(element, tag) | ||
JSON_VALUE_TYPE_STRUCT -> validateIsJsonObjectAndConvert(element, tag) | ||
JSON_VALUE_TYPE_ARRAY -> { | ||
if (subType.isEmpty()) { | ||
throw IllegalArgumentException("Multi-Dimensional JSON Array is Invalid") | ||
} else { | ||
require(element.isJsonArray()) { "Expected Array; the actual element is: $element" } | ||
startArray(tag).fromJson(element.getAsJsonArray(), subType).endArray() | ||
} | ||
} | ||
JSON_VALUE_TYPE_EMPTY -> | ||
throw IllegalArgumentException("Empty array was expected but there is value: $element}") | ||
else -> throw IllegalArgumentException("Invalid type was specified: $type") | ||
} | ||
} | ||
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/** | ||
* Extracts tag and type fields from Json key. Valid JSON key SHOULD have 1, 2, or 3 fields | ||
* constracted as [name:][tag:]type[-subtype] | ||
* | ||
* @param key Json element key value. | ||
* @throws IllegalArgumentException if the key format was invalid | ||
*/ | ||
private fun extractTagAndTypeFromJsonKey(key: String): Triple<Tag, String, String> { | ||
val keyFields = key.split(":") | ||
var type = keyFields.last() | ||
val typeFields = type.split("-") | ||
var subType = "" | ||
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val tagNumber = | ||
when (keyFields.size) { | ||
2 -> keyFields.first().toUIntOrNull() | ||
3 -> keyFields[1].toUIntOrNull() | ||
else -> throw IllegalArgumentException("Invalid JSON key value: $key") | ||
} | ||
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val tag = | ||
when { | ||
tagNumber == null -> throw IllegalArgumentException("Invalid JSON key value: $key") | ||
tagNumber <= UByte.MAX_VALUE.toUInt() -> ContextSpecificTag(tagNumber.toInt()) | ||
tagNumber <= UShort.MAX_VALUE.toUInt() -> CommonProfileTag(2, tagNumber) | ||
else -> CommonProfileTag(4, tagNumber) | ||
} | ||
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// Valid type field of the JSON key SHOULD have type and optional subtype component | ||
require(typeFields.size in (1..2)) { "Invalid JSON key value: $key" } | ||
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if (typeFields.size == 2) { | ||
require(typeFields[0] == JSON_VALUE_TYPE_ARRAY) { "Invalid JSON key value: $key" } | ||
type = JSON_VALUE_TYPE_ARRAY | ||
subType = typeFields[1] | ||
} | ||
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return Triple(tag, type, subType) | ||
} | ||
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private fun String.base64Encode(): ByteString { | ||
return ByteString.copyFrom(Base64.getDecoder().decode(this)) | ||
} | ||
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/** Verifies JsonElement is Number. If yes, returns the value. */ | ||
private fun validateIsNumber(element: JsonElement): Number { | ||
require( | ||
element.isJsonPrimitive() && | ||
(element.getAsJsonPrimitive().isNumber() || element.getAsJsonPrimitive().isString()) | ||
) { | ||
"Expected Integer represented as a Number or as a String; the actual element is: $element" | ||
} | ||
return element.getAsJsonPrimitive().getAsNumber() | ||
} | ||
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/** Verifies JsonElement is Boolean. If yes, returns the value. */ | ||
private fun validateIsBoolean(element: JsonElement): Boolean { | ||
require(element.isJsonPrimitive() && element.getAsJsonPrimitive().isBoolean()) { | ||
"Expected Boolean; the actual element is: $element" | ||
} | ||
return element.getAsJsonPrimitive().getAsBoolean() | ||
} | ||
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/** Verifies JsonElement is Double. If yes, returns the value. */ | ||
private fun validateIsDouble(element: JsonElement): Double { | ||
require(element.isJsonPrimitive() && element.getAsJsonPrimitive().isNumber()) { | ||
"Expected Double; the actual element is: $element" | ||
} | ||
return element.getAsJsonPrimitive().getAsDouble() | ||
} | ||
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/** Verifies JsonElement is String. If yes, returns the value. */ | ||
private fun validateIsString(element: JsonElement): String { | ||
require(element.isJsonPrimitive() && element.getAsJsonPrimitive().isString()) { | ||
"Expected String; the actual element is: $element" | ||
} | ||
return element.getAsJsonPrimitive().getAsString() | ||
} | ||
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/** Verifies JsonElement is Null. If yes, puts it into TLV. */ | ||
private fun TlvWriter.validateIsNullAndPut(element: JsonElement, tag: Tag) { | ||
require(element.isJsonNull()) { "Expected Null; the actual element is: $element" } | ||
putNull(tag) | ||
} | ||
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/** Verifies JsonElement is JsonObject. If yes, converts it into TLV Structure. */ | ||
private fun TlvWriter.validateIsJsonObjectAndConvert(element: JsonElement, tag: Tag) { | ||
require(element.isJsonObject()) { "Expected JsonObject; the actual element is: $element" } | ||
startStructure(tag).fromJson(element.getAsJsonObject()).endStructure() | ||
} |
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