Class: FTW::WebSocket::Parser

Inherits:

Object

• Object
• FTW::WebSocket::Parser

Defined in:

lib/ftw/websocket/parser.rb

Overview

This class implements a parser for WebSocket messages over a stream.

Protocol diagram copied from RFC6455 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 +-+-+-+-+-------+-+-------------+-------------------------------+ |F|R|R|R| opcode|M| Payload len | Extended payload length | |I|S|S|S| (4) |A| (7) | (16/64) | |N|V|V|V| |S| | (if payload len==126/127) | | |1|2|3| |K| | | +-+-+-+-+-------+-+-------------+ - - - - - - - - - - - - - - - + | Extended payload length continued, if payload len == 127 |

• • • • • • • • • • • • • • • • -------------------------------

| |Masking-key, if MASK set to 1 | +-------------------------------+-------------------------------+ | Masking-key (continued) | Payload Data | +-------------------------------- - - - - - - - - - - - - - - - + : Payload Data continued ... :

+ - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - +
|                     Payload Data continued ...                |
+---------------------------------------------------------------+

Example use:

socket = FTW::Connection.new("example.com:80")
parser = FTW::WebSocket::Parser.new
# ... do HTTP Upgrade request to websockets
loop do
  data = socket.sysread(4096)
  payload = parser.feed(data)
  if payload
    # We got a full websocket frame, print the payload.
    p :payload => payload
  end
end

Constant Summary

STATES =

States are based on the minimal unit of 'byte'

[ :flags_and_opcode, :mask_and_payload_init, :payload_length, :payload ]

Instance Method Summary

• #feed(data) ⇒ String^?

  Feed data to this parser.

Instance Method Details

#feed(data) ⇒ String^?

Feed data to this parser.

Currently, it will return the raw payload of websocket messages. Otherwise, it returns nil if no complete message has yet been consumed.

Parameters:

• the (String) —

  string data to feed into the parser.

Returns:

• (String, nil) —

  the websocket message payload, if any, nil otherwise.

# File 'lib/ftw/websocket/parser.rb', line 77

def feed(data)
  @buffer << data
  while have?(@need)
    value = send(@state)
    # Return if our state yields a value.
    yield value if !value.nil? and block_given?
  end
  return nil
end