Is it possible to detect UDP response encoding?

Question:

I query a Quake3 masterserver via UDP, and get the response as below. As you can see, I had trouble figuring out the encoding of what the server sent... Is there any way to detect or set the receive encoding ?

            baBuffer = new byte[1024*100]; // 100 kb should be enough
        int recv = sctServerConnection.ReceiveFrom(baBuffer, ref tmpRemote);

        Console.WriteLine("Message received from {0}:", tmpRemote.ToString());

        System.Text.Encoding encResponseEncoding = System.Text.Encoding.Default; // Wrong...
        //encResponseEncoding = System.Text.Encoding.ASCII;
        //encResponseEncoding = System.Text.Encoding.UTF8;
        //encResponseEncoding = System.Text.Encoding.GetEncoding(437); // ANSI-DOS
        //encResponseEncoding = System.Text.Encoding.GetEncoding(1252);// ANSI-WestEurope
        //encResponseEncoding = System.Text.Encoding.GetEncoding(1250); // Ansi-Centraleuro
        //encResponseEncoding = System.Text.Encoding.GetEncoding("ISO-8859-1");
        //encResponseEncoding = System.Text.Encoding.GetEncoding("ISO-8859开发者_开发技巧-9");
        //encResponseEncoding = System.Text.Encoding.UTF32;
        encResponseEncoding = System.Text.Encoding.UTF7; // Bingo !

The encoding (if it is actually text) is determined by the protocol. If you don't have a protocol spec and you don't have the source code then, yes, you'll have to guess.

There is no way to safely detect encoding, you can just guess it. See also How can I detect the encoding/codepage of a text file.

You can look for the Byte Order Mark (BOM). Here's some VB.Net code that I use:

Private Shared Function GetStringFromBytes(ByVal bytes() As Byte) As String
    Dim ByteLegth = bytes.Count
    If (ByteLegth >= 3) AndAlso (bytes(0) = &HEF) AndAlso (bytes(1) = &HBB) AndAlso (bytes(2) = &HBF) Then
        Return System.Text.Encoding.UTF8.GetString(bytes)
    ElseIf (ByteLegth >= 2) AndAlso (bytes(0) = &HFE) AndAlso (bytes(1) = &HFF) Then
        Return System.Text.Encoding.BigEndianUnicode.GetString(bytes)
    ElseIf (ByteLegth >= 2) AndAlso (bytes(0) = &HFF) AndAlso (bytes(1) = &HFE) Then
        Return System.Text.Encoding.Unicode.GetString(bytes)
    ElseIf (ByteLegth >= 2) AndAlso (bytes(0) = &H0) AndAlso (bytes(1) = &H0) AndAlso (bytes(2) = &HFE) AndAlso (bytes(3) = &HFF) Then
        Return New System.Text.UTF32Encoding(True, True).GetString(bytes)
    ElseIf (ByteLegth >= 2) AndAlso (bytes(0) = &HFF) AndAlso (bytes(1) = &HFE) AndAlso (bytes(2) = &H0) AndAlso (bytes(3) = &H0) Then
        Return System.Text.Encoding.UTF32.GetString(bytes)
    Else
        'No BOM, assume ASCII
        Return System.Text.Encoding.ASCII.GetString(bytes)
    End If
End Function