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