Potential bug: Decoding partial response may result in corrupt string in case of multi-byte encoding

[Makaopior]

This one is rather theoretical bug (I haven't encounter one) but may emerge someday.
Consider this part of code, which is reading response from the socket:

do
{
    cbRead = s.Read(readBuff, 0, readBuff.Length);
    res.Append(options.Encoding.GetString(readBuff, 0, cbRead));

In case of single-byte ASCII encoding, it does well. But some registries use other encodings. For example, JPNIC uses ISO-2022-JP to encode dual-byte characters. In this case, if response byte chunk ends in the middle of multi-byte codepoint, the result will be corrupted.
This test demonstrates a potential behavior:

[Test]
public void StringWithDualByteChars_BrokenInTheMiddleOfTheChar_DecodingBothPartsDerivesIncorrectResult()
{
#if NETCOREAPP
    Encoding.RegisterProvider(CodePagesEncodingProvider.Instance);
#endif

    var isoEncoding = Encoding.GetEncoding("iso-2022-jp");

    var testBytes = isoEncoding.GetBytes("こちらはテスト文字列である");
    var firstBytes = testBytes.Take(9).ToArray();
    var lastBytes = testBytes.Skip(9).ToArray();

    var finalString = isoEncoding.GetString(firstBytes) + isoEncoding.GetString(lastBytes);

    testBytes.Length.Is(firstBytes.Length + lastBytes.Length);
    finalString.Is("こちらはテスト文字列である"); //fails
}

Result:

Assert.That(actual, Is.EqualTo(expected))
Expected string length 13 but was 23. Strings differ at index 3.
Expected: "こちらはテスト文字列である"
But was:  "こちら$O%F%9%HJ8;zNs$G$"$k"
--------------^

 at NUnit.Framework.Legacy.ClassicAssert.AreEqual(Object expected, Object actual, String message, Object[] args)

The fix would be reading the full response message in something like List<byte> and decoding it afterwards.
I'll create a PR later in order not to mess up with other fixes.

[jsakamoto]

Hi @Makaopior,
Thank you for your contributions.

The fix would be reading the full response message in something like List and decoding it afterwards.

That sounds good for me. Please go ahead and create a pull request. I'd appreciate it if you could.

[Makaopior]

Hi @jsakamoto ,

Here you are.