class BBS::Telnet::Parser

Telnet commands taken out of a byte stream, one byte at a time: a small state machine, shared by the board’s own line (BBS::Telnet) and both directions of a BBS::Gateway::Link. Data bytes come out, a doubled IAC as one 255; each option command and subnegotiation goes to the block given to ::new.

parser = BBS::Telnet::Parser.new { |command, argument| p [command, argument] }
parser.parse("hi\xFF\xFB\x01".b)   # => "hi", and prints [251, 1]

The block gets (command, option) for WILL, WONT, DO and DONT, and (SB, bytes) for a subnegotiation, bytes an Array of Integer whose first is the option; a subnegotiation keeps at most MAX_SUBNEGOTIATION bytes, the rest is read and dropped. Other commands (NOP, GA …) are dropped.

Constants

OPTION_COMMANDS: The commands followed by one option byte.

Public Class Methods

new (&on_command)

Source

# File lib/bbs/telnet/parser.rb, line 27
def initialize(&on_command)
  @on_command = on_command
  @state      = :data
end

Creates a parser in the data state; on_command is called as described above.

Public Instance Methods

feed (byte)

Source

# File lib/bbs/telnet/parser.rb, line 34
def feed(byte) = send(@state, byte)

Takes the next byte (an Integer) of the stream. Returns it when it is data, nil when it belongs to a command.

parse (bytes)

Source

# File lib/bbs/telnet/parser.rb, line 37
def parse(bytes) = bytes.each_byte.filter_map { |byte| feed(byte) }.pack('C*')

Takes a String of bytes and returns its data bytes, a binary String.