#!/usr/bin/perl
#
# $RCSfile: encmail.txt,v $
# Original Author...: Anthony Awtrey
# Version...........: $Revision: 1.1 $
# Last Modified By..: $Author: aawtrey $
# Last Modified.....: $Date: 2005/04/04 14:44:38 $
#
# Copyright 2005 Anthony L. Awtrey
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
#
# Purpose:
# This script replaces sendmail in CGI forms that send mail. It uses GnuPG
# to encrypt email based on the email address in the To: header. If no key
# is available it passes the mail through to sendmail unencrypted.
#

####################
# Adjust these variables
####################

# The full sendmail commandline. Typically, "/usr/sbin/sendmail -t"
$sendmail = "/usr/sbin/sendmail -t -i";

# The path to the gpg executable
$gnupg    = "/usr/bin/gpg";

# A place the script can write temporary files.
$tmpdir   = "/tmp";

# Location of the keyring files
$homedir  = "/home/dir/.gnupg";

####################
# Start Main Code
####################

####################
# Pull the email from STDIN and break out the components
####################

while (<STDIN>) {

  ####################
  # The headers and the body are seperated by a single newline
  # Test for a newline to mark the start of the email body
  ####################

  if ( /^\n/ && $start_body!=1 ) {

    $start_body = 1;

  ####################
  # If we haven't found the bare newline yet, switch based on the header field
  # name to collect the headers.
  ####################

  } elsif ($start_body!=1) {

    ####################
    # Remove the newline
    ####################
    chop;

    ####################
    # Split the line at the colon ':'
    ####################
    ($field, $data) = split(/:/, $_, 2);

    ####################
    # Set an element in an array if we get a valid header.
    # Valid Headers: To From Subject Fcc Bcc Cc Sender X-sender Date X-Url
    ####################
    SWITCH: for ($field) {

      /^To$/ && do {
        $headers{'To'} = $data;
        $email_address = &get_email($data);
        last;
      };
      /^From$/ && do {
        $headers{'From'} = $data;
        last;
      };
      /^Subject$/ && do {
        $headers{'Subject'} = $data;
        last;
      };
      /^Cc$/ && do {
        $headers{'Cc'} = $data;
        last;
      };
      /^Fcc$/ && do {
        $headers{'Fcc'} = $data;
        last;
      };
      /^Bcc$/ && do {
        $headers{'Bcc'} = $data;
        last;
      };
      /^Sender$/ && do {
        $headers{'Sender'} = $data;
        last;
      };
      /^X-sender$/ && do {
        $headers{'X-sender'} = $data;
        last;
      };
      /^Date$/ && do {
        $headers{'Date'} = $data;
        last;
      };
      /^X-url$/ && do {
        $headers{'X-url'} = $data;
        last;
      };
    }

  ####################
  # If we have found the bare newline then the rest of the message is collected
  # as the body
  ####################

  } else {

    $BODY .= "$_";

  }

}

####################
# End the while loop collecting the data from STDIN
####################

####################
# Collect a key list from gpg
####################

@keys  = `$gnupg --homedir=$homedir --list-keys`;

foreach $key (@keys) {

  ####################
  # Ditch the newline
  ####################
  if ($key =~ /\n$/) { chop($key); }

  ####################
  # Try to find the email address in the key line
  ####################
  $key =~ s/^pub.*\<(.*)\>/$1/;

  ####################
  # Test to see if this line's email address matches the To header
  ####################
  if ($email_address eq $key) {

    ####################
    # If it does, set a variable for later
    ####################
    $enc_email = $key;

  }

}

####################
# End the key list collection
####################

####################
# If the GnuPG email address matches the To address encrypt the message body
####################

if ($enc_email) {

  ####################
  # Generate a tmp file name
  ####################

  srand(time|$$);
  @saltchars = (a..z,A..Z,0..9);
  for ($i=0; $i<8; $i++) {
    $tmpfile .= $saltchars[int(rand($#saltchars+1))];
  }
  $tmpfile = "$tmpdir/$tmpfile";

  ####################
  # Write message body to temp file
  ####################

  open(TMPFILE,">$tmpfile");
    print TMPFILE "$BODY\n";
  close(TMPFILE);

  ####################
  # Encrypt email body from the temp file
  ####################

  $BODY = `$gnupg --no-verbose --no-greeting --no-secmem-warning --homedir=$homedir -ear $enc_email < $tmpfile 2>&1`;

  ####################
  # Delete temp file
  ####################

  unlink($tmpfile);

}
####################
# End email encryption
####################

####################
# Send the mail
####################

open(MAIL,"|$sendmail");

  foreach $key (keys %headers) {
    print MAIL "$key: $headers{$key}\n";
  }
  print MAIL "\n";
  print MAIL "$BODY";
  print MAIL "\n";

close(MAIL);

####################
# End Main Code
####################

####################
# Begin Functions
####################

sub get_email {
  $address = $_[0];

  @parts = split(/ /,$address);
  foreach $part (@parts) {
    if ($part =~ /\<?.*\@.*\>?/) {
      $part =~ s/\<//g;
      $part =~ s/\>//g;
      $email = $part;
    }
  }
  return($email);

}