Why does websocket handshake fail?

Question

i have the following code for my python server to create and send back the response to an handshake

    def HandShake(self, request):
    specificationGUID = "258EAFA5-E914-47DA-95CA-C5AB0DC85B11"
    websocketkey = ""
    protocol = ""
    for line in request.split("\n"):
        if "Sec-WebSocket-Key:" in line:
            websocketkey = line.split(" ")[1]
        elif "Sec-WebSocket-Protocol" in line:
            protocol = line.split(":")[1].strip()

    print("websocketkey: " + websocketkey + "\n")
    fullKey = hashlib.sha1(websocketkey.encode("utf-8") + specificationGUID.encode("utf-8")).digest()
    acceptKey = base64.b64encode(fullKey)
    print("acceptKey: " + str(acceptKey, "utf-8") + "\n")
    if protocol != "":
        handshake = "HTTP/1.1 101 Switching Protocols\r\nUpgrade: websocket\r\nConnection: Upgrade\r\nSec-WebSocket-Accept: " + str(acceptKey, "utf-8") + "\r\nSec-WebSocket-Protocol: " + protocol + "\r\n\r\n"
    else:
        handshake = "HTTP/1.1 101 Switching Protocols\r\nUpgrade: websocket\r\nConnection: Upgrade\r\nSec-WebSocket-Accept: " + str(acceptKey, "utf-8") + "\r\n\r\n"
    print(handshake)
    self.request.send(bytes(handshake, "utf-8"))

I have tested my method of calculating the key with the example on wikipedia, so i know that is correct. However everytime when i try to connect to my server i get the following the error:

Error during WebSocket handshake: Sec-WebSocket-Accept mismatch

I dont understand what im doing wrong here. does someone see what is going wrong?

EDIT: an example output from the prints, this prints the original message and the fabricated handshake

server started, waiting for connections...
request:
GET / HTTP/1.1
Upgrade: websocket
Connection: Upgrade
Host: localhost:600
Origin: http://localhost
Pragma: no-cache
Cache-Control: no-cache
Sec-WebSocket-Key: yLffHPqMU4gIW2WnKq+4BQ==
Sec-WebSocket-Version: 13
Sec-WebSocket-Extensions: x-webkit-deflate-frame
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/31.0.1650.63 Safari/537.36


websocketkey: yLffHPqMU4gIW2WnKq+4BQ==

acceptKey: A0eCd19URtkji0OPV162okWsCns=

HTTP/1.1 101 Switching Protocols
Upgrade: websocket
Connection: Upgrade
Sec-WebSocket-Accept: A0eCd19URtkji0OPV162okWsCns=

Post the output of your print() calls in your question.

Joakim Erdfelt
– Joakim Erdfelt

2013-12-22 03:42:22 +00:00
Commented Dec 22, 2013 at 3:42 — Joakim Erdfelt
– Joakim Erdfelt, Commented Dec 22, 2013 at 3:42
i edited the op with the print output

WillieWonka
– WillieWonka

2013-12-22 10:45:29 +00:00
Commented Dec 22, 2013 at 10:45 — WillieWonka
– WillieWonka, Commented Dec 22, 2013 at 10:45

Joakim Erdfelt · Accepted Answer · 2013-12-23 18:23:10Z

2

You have a bug in your code.

for line in request.split("\n"):
    if "Sec-WebSocket-Key:" in line:
        websocketkey = line.split(" ")[1]

That is returning the "\r" in your Sec-WebSocket-Key.

Evidence:

Normal RFC Behavior

Client Key: "yLffHPqMU4gIW2WnKq+4BQ=="
Server Key: YVjKqlMRxlzzM70LScN9VoCsboI=

Bad Behavior

Client Key: "yLffHPqMU4gIW2WnKq+4BQ==\r"
Server Key: A0eCd19URtkji0OPV162okWsCns=

Links to AutobahnPython Sec-WebSocket-Key server side validation, and AutobahnPython hash calculation.

edited Dec 23, 2013 at 18:23

answered Dec 23, 2013 at 18:00

Joakim Erdfelt

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