openssh-key-checker.gemspec

Gem::Specification.new do |s|
  s.name        = 'openssh-key-checker'
  s.version     = '0.1.0'
  s.platform    = Gem::Platform::RUBY
  s.author      = 'Jan Bernacki'
  s.email       = '[email protected]'
  s.summary     = 'OpenSSH checker'
  s.description = 'OpenSSH checker with system tools'
 
  s.files         = ['openssh-key-checker.rb']
  s.require_path  = '.'
end

openssh-key-checker.rb

require "securerandom"

class OpenSSHKeyChecker
  def initialize(key)
    @key = key.to_s
  end
  
  def valid?
    tmpfile = TmpFile.new
    tmpfile.write oneliner
    system "ssh-keygen -l -f '#{tmpfile.path}' >/dev/null 2>/dev/null"
  rescue Invalid
    false
  ensure
    tmpfile.unlink
  end
  
  def oneliner
    oneliner? ? @key : to_oneliner
  end
  
  def oneliner?
    @key.lines.size == 1
  end

  def to_oneliner
    tmpfile = TmpFile.new
    tmpfile.write @key
    
    oneliner = `ssh-keygen -i -f '#{tmpfile.path}' 2>/dev/null`
    $?.success? ? oneliner : raise(Invalid.new)
  ensure
    tmpfile.unlink
  end
  
  class Invalid < StandardError
  end
  
  class TmpFile
    attr_reader :path
    def initialize
      @path = "/tmp/openssh-check-#{SecureRandom.hex(8)}"
    end
    
    def write(data)
      File.open(@path, "wb") { |file| file.write data }
    end
    
    def unlink
      File.exists?(@path) and File.unlink(@path)
    end
  end
end