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using Newtonsoft.Json.Linq;
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Security.Cryptography;
using System.Text;
namespace com.clusterrr.TuyaNet
{
/// <summary>
/// Class to encode and decode data sent over local network.
/// </summary>
internal static class TuyaParser
{
private static byte[] PROTOCOL_VERSION_BYTES_31 = Encoding.ASCII.GetBytes("3.1");
private static byte[] PROTOCOL_VERSION_BYTES_33 = Encoding.ASCII.GetBytes("3.3");
private static byte[] PROTOCOL_33_HEADER = Enumerable.Concat(PROTOCOL_VERSION_BYTES_33, new byte[] { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 }).ToArray();
private static byte[] PREFIX = new byte[] { 0, 0, 0x55, 0xAA };
private static byte[] SUFFIX = { 0, 0, 0xAA, 0x55 };
private static uint SeqNo = 0;
internal static IEnumerable<byte> BigEndian(IEnumerable<byte> seq) => BitConverter.IsLittleEndian ? seq.Reverse() : seq;
internal static byte[] Encrypt(byte[] data, byte[] key)
{
var aes = new AesManaged()
{
Mode = CipherMode.ECB,
Key = key
};
using (var ms = new MemoryStream())
using (var cs = new CryptoStream(ms, aes.CreateEncryptor(), CryptoStreamMode.Write))
{
cs.Write(data, 0, data.Length);
cs.Close();
data = ms.ToArray(); // encrypt the data
}
return data;
}
internal static byte[] Decrypt(byte[] data, byte[] key)
{
if (data.Length == 0) return data;
var aes = new AesManaged()
{
Mode = CipherMode.ECB,
Key = key
};
using (var ms = new MemoryStream())
using (var cs = new CryptoStream(ms, aes.CreateDecryptor(), CryptoStreamMode.Write))
{
cs.Write(data, 0, data.Length);
cs.Close();
data = ms.ToArray(); // dencrypt the data
}
return data;
}
internal static byte[] EncodeRequest(TuyaCommand command, string json, byte[] key, TuyaProtocolVersion protocolVersion = TuyaProtocolVersion.V33)
{
// Remove spaces and newlines
var root = JObject.Parse(json);
json = root.ToString(Newtonsoft.Json.Formatting.None);
byte[] payload = Encoding.UTF8.GetBytes(json);
if (protocolVersion == TuyaProtocolVersion.V33)
{
// Encrypt
payload = Encrypt(payload, key);
// Add protocol 3.3 header
if ((command != TuyaCommand.DP_QUERY) && (command != TuyaCommand.UPDATE_DPS))
payload = Enumerable.Concat(PROTOCOL_33_HEADER, payload).ToArray();
}
else if (command == TuyaCommand.CONTROL)
{
// Encrypt
payload = Encrypt(payload, key);
// Encode to base64
string data64 = Convert.ToBase64String(payload);
// Make string
payload = Encoding.UTF8.GetBytes($"data={data64}||lpv=3.1||");
using (var md5 = MD5.Create())
using (var ms = new MemoryStream())
{
// Calculate MD5 of data
ms.Write(payload, 0, payload.Length);
// ...and encryption key
ms.Write(key, 0, key.Length);
string md5s =
BitConverter.ToString( // Make string from MD5
md5.ComputeHash(ms.ToArray()) // Calculate MD5
)
.Replace("-", string.Empty) // Remove '-'
.Substring(8, 16) // Get part of it
.ToLower(); // Lowercase
// Data with protocol header, MD5 hash and data
payload = Encoding.UTF8.GetBytes($"3.1{md5s}{data64}");
}
}
using (var ms = new MemoryStream())
{
byte[] seqNo = BitConverter.GetBytes(SeqNo++);
if (BitConverter.IsLittleEndian) Array.Reverse(seqNo); // Make big-endian
byte[] dataLength = BitConverter.GetBytes(payload.Length + 8);
if (BitConverter.IsLittleEndian) Array.Reverse(dataLength); // Make big-endian
ms.Write(PREFIX, 0, 4); // Prefix
ms.Write(seqNo, 0, 4); // Packet number
ms.Write(new byte[] { 0, 0, 0, (byte)command }, 0, 4); // Command number
ms.Write(dataLength, 0, 4); // Length of data + length of suffix
ms.Write(payload, 0, payload.Length); // Data
var crc32 = new Crc32();
var crc = crc32.Get(ms.ToArray());
byte[] crcBin = BitConverter.GetBytes(crc);
if (BitConverter.IsLittleEndian) Array.Reverse(crcBin); // Make big-endian
ms.Write(crcBin, 0, 4); // CRC32 checksum
ms.Write(SUFFIX, 0, 4); // Suffix
payload = ms.ToArray();
}
return payload;
}
internal static TuyaLocalResponse DecodeResponse(byte[] data, byte[] key, TuyaProtocolVersion protocolVersion = TuyaProtocolVersion.V33)
{
// Check length and prefix
if (data.Length < 20 || !data.Take(PREFIX.Length).SequenceEqual(PREFIX))
{
throw new InvalidDataException("Invalid header/prefix");
}
// Check length
int length = BitConverter.ToInt32(BigEndian(data.Skip(12).Take(4)).ToArray(), 0);
if (data.Length != 16 + length)
{
throw new InvalidDataException("Invalid length");
}
// Check suffix
if (!data.Skip(16 + length - SUFFIX.Length).Take(SUFFIX.Length).SequenceEqual(SUFFIX))
{
throw new InvalidDataException("Invalid suffix");
}
// Packet number
// uint seq = BitConverter.ToUInt32(BinEndian(data.Skip(4).Take(4)).ToArray(), 0);
// Command
var command = (TuyaCommand)BitConverter.ToUInt32(BigEndian(data.Skip(8).Take(4)).ToArray(), 0);
// Return code
int returnCode = BitConverter.ToInt32(BigEndian(data.Skip(16).Take(4)).ToArray(), 0);
// Data
data = data.Skip(20).Take(length - 12).ToArray();
var realVersion = protocolVersion;
// Remove version 3.1 header
if (data.Take(PROTOCOL_VERSION_BYTES_31.Length).SequenceEqual(PROTOCOL_VERSION_BYTES_31))
{
data = data.Skip(PROTOCOL_VERSION_BYTES_31.Length).ToArray();
realVersion = TuyaProtocolVersion.V31;
}
// Remove version 3.3 header
if (data.Take(PROTOCOL_VERSION_BYTES_33.Length).SequenceEqual(PROTOCOL_VERSION_BYTES_33))
{
data = data.Skip(PROTOCOL_33_HEADER.Length).ToArray();
realVersion = TuyaProtocolVersion.V33;
}
if (realVersion == TuyaProtocolVersion.V33)
{
data = Decrypt(data, key);
}
if (data.Length == 0)
return new TuyaLocalResponse(command, returnCode, null);
var json = Encoding.UTF8.GetString(data);
if (!json.StartsWith("{") || !json.EndsWith("}"))
throw new InvalidDataException($"Response is not JSON: {json}");
return new TuyaLocalResponse(command, returnCode, json);
}
}
}
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