undocumented - Reading from a socket stream

I noticed an undocumented socket package (SocketLink) in Mathematica (Using version 10, not sure when it was actually added) and wrote a barebones HTTP responder using it:

<host = "localhost";
port = 9999;
eol = "\r\n";
helloHTML = 
  "Hello world!";
response = "HTTP/1.1 200 OK"<>eol<>
    "Content-length: "<>ToString[StringLength[helloHTML<>eol]]<>eol<>eol<>

    helloHTML<>eol;
handler[streams_] := Module[{
        inStream = streams[[1]],
        outStream = streams[[2]],
        req = {},
        reqString
    },
    While[!MatchQ[req, {___, 13, 10, 13, 10}],
        AppendTo[req, BinaryRead[inStream]];
    ];

    Close[inStream];
    reqString = FromCharacterCode[req];
    (* print request *)
    Print[reqString];
    BinaryWrite[outStream, ToCharacterCode[response]];
    Close[outStream];
];

s = CreateServerSocket[port]
ser = CreateAsynchronousServer[s, handler]

The issue is that I have no way of telling when there is no more content in the input stream. This is a problem because if I read once byte beyond this the kernel crashes. I get around it in the above code by reading each character individually and using pattern matching to detect when the request ends (at "\r\n\r\n"):

While[!MatchQ[req, {___, 13, 10, 13, 10}],
    AppendTo[req, BinaryRead[inStream]];
];

This is will work with properly formed requests but if the request is malformed the kernel crash is unavoidable as far as I can see. I realize implementing an HTTP server in Mathematica is a silly endeavour but I would like to know if there is a way of detecting the "end" of a socket stream for other potentially nontrivial uses of SocketLink.