WsDataUtil (WebSocket Data Util)

The WsDataUtil is a lightweight, highly compatible Python module for processing WebSocket data. The parsing, building and masking of WebSocket frames is implemented in C to increase performance.

The core of the module is the Frame and the StreamReader object as an interface to the C api. Frame serves as the result value from parsing and as the parameter for building a WebSocket frame. A Frame is not checked for plausibility or according to the specification RFC6455. This should be implemented later if required.

For the sake of completeness, the HandshakeRequest object is available.

Installation:

python -m pip install wsdatautil --upgrade

Gallery of WebSocket data

Connection establishment

minimum client request:

GET /<URL> HTTP/1.1
Upgrade: websocket
Connection: Upgrade
Sec-WebSocket-Key: <String-In>
Sec-WebSocket-Version: <Version-in>

minimum server response:

HTTP/1.1 101 Switching Protocols
Upgrade: websocket
Connection: Upgrade
Sec-WebSocket-Accept: <String-Out>
Sec-WebSocket-Version: <Version-out>

The WebSocket Key conversion

• <String-In> can be any base64 string.
• On the server side, the static string 258EAFA5-E914-47DA-95CA-C5AB0DC85B11 is appended to the <String-In>.
• The result is hashed with the SHA-1 function.
• A base64 string is then created from the digest and returned as <String-Out>.

WebSocket-Frame

 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
| | | | |
HEADER +-+-+-+-+-------+-+-------------+-------------------------------+
|F|R|R|R| op- |M| amount_spec | ... amount (extended I) |
|I|S|S|S| code |A| | if amount_spec == (126|127) |
|N|V|V|V| |S| | |
| |1|2|3| (4) |K| (7) | (16|64) |
+-+-+-+-+-------+-+-------------+— — — — — — — — — — — — — — — —+
| ... amount (extended II) if amount_spec == 127 |
+— — — — — — — — — — — — — — — —+-------------------------------+
| | masking_key if MASK == 1 |
+-------------------------------+-------------------------------+
| ... masking_key |
+-------------------------------+
BUFFER +-------------------------------+
| payload |
+-------------------------------+— — — — — — — — — — — — — — — —+
: ... payload :
+— — — — — — — — — — — — — — — —+— — — — — — — — — — — — — — — —+
| ... payload |
+-------------------------------+-------------------------------+

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Tests

python test.py
python test.py -h