#!/usr/bin/ruby
# Takes <keygen> input and emails somebody with an inline SPKAC request
#
# Certificates are automatically imported if they are served to clients over http with
# Content-type: application/x-x509-user-cert
# 
# Some Webkit browsers, notably Chrome, don't understand PEM. Use DER.

# Redefine these:

localpart = 'jerks'
hostname = 'example.com'

require 'cgi'

cgi = CGI.new

# Depending on how you access the form variables will depend on the results you get.
# 1. An explicit request in 1.8.x of form cgi['myvar'] returns a string
# 2. pre 1.8.x it returns an array
# 3. If you use the form cgi.params it returns a hash
# 4. If your form happens to include file upload (e.g. contains <input type="file"> and an 'enctype="multipart/form-data"') then
#    * if the file size is > 10240 bytes ALL variables are created as Tempfiles
#    * if < 10240 they are StringIO objects.

# StringIO and Tempfile both support the 'read' method, so all that's left is String...
class String
  def read( )
    self
  end
end

print 'Content-type: text/plain

'

spkac = String.new

['SPKAC', 'C', 'ST', 'L', 'O', 'OU', 'CN', 'emailAddress'].each do |dn|
  if defined?(cgi.params[dn][0].read) && cgi.params[dn][0].read =~ /./
    spkac << "#{dn}=#{cgi.params[dn][0].read.gsub(/\r|\n/, '')}\n"
  else
    print "Warning: Variable #{dn} is invalid or missing. It will not be included in your request. If this is in error, please correct and resubmit.\n"
  end
end

if spkac =~ /^SPKAC/
  IO.popen('/usr/sbin/sendmail -t', mode='w') { |mail|
    mail.write(
"To: #{localpart}@#{hostname}
From: spkac form <root@#{hostname}>
Subject: SPKAC request
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii

#{ENV['REMOTE_ADDR']} #{ENV['HTTP_USER_AGENT']}

#{spkac}
"
    )
  }
  print "\nThe following SPKAC request has been emailed to your friendly neighbourhood admins, who will look it over, possibly sign it and give you a link to a shiny new certificate:\n\n"
  print spkac

else
  print "Error: SPKAC public key is missing. Correct and resubmit."
end