ZLIB compression in .NET

zlip.cs

public static byte[] ZlibCompress(byte[] data)
{
	using (MemoryStream outStream = new MemoryStream())
	{
		// zlib header
		outStream.WriteByte(0x58);
		outStream.WriteByte(0x85);

		// zlib body
		using (var compressor = new DeflateStream(outStream, CompressionMode.Compress, true))
			compressor.Write(data, 0, data.Length);

		// zlib checksum - a naive implementation of adler-32 checksum
		const uint A32Mod = 65521;
		uint s1 = 1, s2 = 0;
		foreach (byte b in data)
		{
			s1 = (s1 + b) % A32Mod;
			s2 = (s2 + s1) % A32Mod;
		}

		int adler32 = unchecked((int)((s2 << 16) + s1));
		outStream.Write(BitConverter.GetBytes(IPAddress.HostToNetworkOrder(adler32)), 0, sizeof(uint));

		// zlib compatible compressed query
		var bytes = outStream.ToArray();
		outStream.Close();

		return bytes;
	}
}