SSL certificate algorithm test

certtest.rb

#!/usr/bin/env ruby
require 'socket'
require 'openssl'

def check_ssl_cert(host, port, ca_file)
  sock = TCPSocket.new(host, port)
  ctx = OpenSSL::SSL::SSLContext.new
  ctx.set_params(:verify_mode => OpenSSL::SSL::VERIFY_PEER,
                 :ca_file => ca_file)

  socket = OpenSSL::SSL::SSLSocket.new(sock, ctx)
  socket.connect

  cert = socket.peer_cert

  return [host, 'OK', cert.not_before.strftime('%F'), cert.signature_algorithm]
end

if ARGV.empty?
  STDERR.puts 'usage: certtest.rb DOMAIN...'
  exit 1
end

def do_check(domain, add_www=true)
  ca_file = '/etc/ssl/certs/ca-certificates.crt'
  begin
    puts check_ssl_cert(domain, '443', ca_file).join("\t")
  rescue OpenSSL::SSL::SSLError, SocketError => err
    STDERR.puts("#{domain}: #{err}")
    puts [domain, 'ERR', '', ''].join("\t")
  end
  $stdout.flush

  if add_www
    do_check('www.' + domain, false)
  end
end

if ARGV.first == '-'
  STDIN.each_line do |line|
    do_check(line.chomp)
  end
else
  ARGV.each do |domain|
    do_check(domain)
  end
end