telnet
Telnet
Telnet protocol support for Crystal Lang. Does not implement transport, just the raw protocol.
Usage
There are three processes that need to implemented to talk to a Telnet device or service.
- Incoming data needs to be buffered, this handles protocol specific operations and unescapes incomming messages.
- A callback for sending protocol level responses to the far-end
- Preparing a message for transmission
require "telnet"
telnet = Telnet.new do |cmd_response|
# This is a response to a request from the far end
# it should be transferred to the remote
end
# Buffer incoming data for unescaping and command processing
clear_text = telnet.buffer("a string or slice / Bytes")
# Prepare data for sending to the remote (i.e. the application level protocol)
# The prepare function adds the appropriate line endings, as per the telnet session negotiations
encoded_response = telnet.prepare("hello")
An example with the IO implemented properly
require "telnet"
socket = TCPSocket.new("192.168.0.60", 23)
telnet = Telnet.new do |cmd_response|
# This is a response to a request from the far end
socket.write cmd_response
end
# Buffer incoming data for unescaping and command processing
encoded = socket.gets
clear_text = telnet.buffer(encoded)
# Prepare data for sending to the remote
encoded_response = telnet.prepare("hello")
socket.write encoded_response
If you are sending binary data to the remote you'll want to escape it
data = Bytes[3, 255, 4, 40, 255, 30, 20]
encoded_response = telnet.prepare(data, escape: true)
socket.write encoded_response
encoded_response # => Bytes[3, 255, 255, 4, 40, 255, 255, 30, 20, 13, 10]