Module 0x1 | Basic Ruby Kung Fu

Last updated 11 months ago
Ruby has awesome abilities and tricks for dealing with string and array scenarios. In this chapter we'll present some tricks we may need in our hacking life.
Terminal
Terminal size
Here are some different ways to get terminal size from ruby:
By IO/console standard library
require 'io/console'
rows, columns = $stdin.winsize
# Try this now
print "-" * (columns/2) + "\n" + ("|" + " " * (columns/2 -2) + "|\n")* (rows / 2) + "-" * (columns/2) + "\n"
By readline standard library
require 'readline'
Readline.get_screen_size
By environment like IRB or Pry
[ENV['LINES'].to_i, ENV['COLUMNS'].to_i]
By tput command line 
[`tput cols`.to_i , `tput lines`.to_i]
Console with tab completion
We can't stop being jealous of Metasploit console (msfconsole), where we take a rest from command line switches. Fortunately, here is the main idea of console tab completion in ruby:
Readline 
The Readline module provides an interface for GNU Readline. This module defines a number of methods to facilitate completion and accesses input history from the Ruby interpreter.
console-basic1.rb
#!/usr/bin/env ruby
# KING SABRI | @KINGSABRI
# 
require 'readline'
​
# Prevent Ctrl+C for exiting
trap('INT', 'SIG_IGN')
​
# List of commands
CMDS = [ 'help', 'rubyfu', 'ls', 'pwd', 'exit' ].sort
​
​
completion = proc { |line| CMDS.grep( /^#{Regexp.escape( line )}/ ) }
​
# Console Settings
Readline.completion_proc = completion        # Set completion process
Readline.completion_append_character = ' '   # Make sure to add a space after completion
​
while line = Readline.readline('-> ', true)
  puts line unless line.nil? or line.squeeze.empty?
  break if line =~ /^quit.*/i or line =~ /^exit.*/i
end
Now run it and try out the tab completion!
Well, the main idea for tab completion is to make things easier, not just "press tab". Here is a simple thought...
console-basic2.rb
require 'readline'
​
# Prevent Ctrl+C for exiting
trap('INT', 'SIG_IGN')
​
# List of commands
CMDS = [ 'help', 'rubyfu', 'ls', 'exit' ].sort
​
​
completion = 
    proc do |str|
      case 
      when Readline.line_buffer =~ /help.*/i
    puts "Available commands:\n" + "#{CMDS.join("\t")}"
      when Readline.line_buffer =~ /rubyfu.*/i
    puts "Rubyfu, where Ruby goes evil!"
      when Readline.line_buffer =~ /ls.*/i
    puts `ls`
      when Readline.line_buffer =~ /exit.*/i
    puts 'Exiting..'
    exit 0
      else
    CMDS.grep( /^#{Regexp.escape(str)}/i ) unless str.nil?
      end
    end
​
​
Readline.completion_proc = completion        # Set completion process
Readline.completion_append_character = ' '   # Make sure to add a space after completion
​
while line = Readline.readline('-> ', true)  # Start console with character -> and make add_hist = true
  puts completion.call
  break if line =~ /^quit.*/i or line =~ /^exit.*/i
end
Things can go much farther, like msfconsole, maybe?
​Ruby Readline Documentation and Tutorial​
Required Gems
String