Question

I understand that the default encoding of an HTTP Request is ISO 8859-1.

Am I able to use Unicode to decode an HTTP request given as a byte array?

If not, how would I decode such a request in C#?

EDIT: I’m developing a server, not a client.

Answer 1

As you said the default encoding of an HTTP POST request is ISO-8859-1. Otherwise you have to look at the Content-Type header that might then look like Content-Type: application/x-www-form-urlencoded; charset=UTF-8.

Once you have read the posted data into a byte array you may decide to convert this buffer to a string (remember all strings in .NET are UTF-16). It is only at that moment that you need to know the encoding.

byte[] buffer = ReadFromRequestStream(...)
string data = Encoding
              .GetEncoding("DETECTED ENCODING OR ISO-8859-1")
              .GetString(buffer);

And to answer your question:

Am I able to use Unicode to decode an
HTTP request given as a byte array?

Yes, if unicode has been used to encode this byte array:

string data = Encoding.UTF8.GetString(buffer);