https://github.com/spider-gazelle/telnet.cr

Telnet protocol helper for crystal lang
https://github.com/spider-gazelle/telnet.cr

Last synced: 9 days ago
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Telnet protocol helper for crystal lang

• Host: GitHub
• URL: https://github.com/spider-gazelle/telnet.cr
• Owner: spider-gazelle
• License: mit
• Created: 2019-09-27T06:02:05.000Z (about 5 years ago)
• Default Branch: master
• Last Pushed: 2021-05-26T01:34:58.000Z (over 3 years ago)
• Last Synced: 2024-08-01T17:36:19.094Z (3 months ago)
• Language: Crystal
• Size: 6.84 KB
• Stars: 11
• Watchers: 5
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

Awesome Lists containing this project

• awesome-crystal - telnet.cr - Telnet protocol (Network Protocols)
• awesome-crystal - telnet.cr - Telnet protocol (Network Protocols)

README

        
# Telnet

[![CI](https://github.com/spider-gazelle/telnet.cr/actions/workflows/ci.yml/badge.svg)](https://github.com/spider-gazelle/telnet.cr/actions/workflows/ci.yml)

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

```crystal

    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

```crystal

    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

```crystal

    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]

```