gpgmlrobot

#!/bin/sh
# gpgmlrobot - GnuPG Mailing List Robot
# Copyright (c) 1999 Werner Koch <wk@gnupg.org>
# This program may be used under the terms of the GNU General Public Licence
# version 2 or later.
#
#
# The format of the dists file is like this:
#-------------------------------------------------------
# CF8BCC4B18DE08FCD8A1615906AD222CADF6A6E1  wk@gnupg.de
# 4444444444444444444444444444444444444444  foo@bar.net
#---------------------------------------------------------
#
# Each mailing list should have its own directory and an 
# entry like this in the .procmailrc:
#-----------------------------------------
# :0
#  * ^To: .*laurin-list@example\.com
#   {
#        :0:
#        * ^X-Loop: failed-laurin-list@example\.com
#        /dev/null
#
#	:0:
#	| $HOME/laurin-list/gpgmlrobot
#   } 
#-------------------------------------		     
#
# You should create one keypair for each mailing list by
# cd-ing to the list directory and doing a:
#  gpg --homedir .  --gen-key
# and give it the email address of the mailing list, it might
# be a couuld idea to have a comment in the user ID to mark this
# as a key for an encrypted mailing list.  Sen this key to all
# subscribers and put there fingerprint 
#  (gpg --fingerprint --with-colons foo@bar.net)
# into the dists file along with their email address.
# 

#-------------------------------------------
#  Configuration section
#-------------------------------------------

ml_address="laurin-list@example.com"
full_ml_address="Laurin List <$ml_address>"
ml_domain="example.com"

myhome=/home/cryptorobot/laurin-list

SENDMAIL="/usr/sbin/sendmail"
distsfile=dists
remove_input=no
ciphertextfile="$1"
passphrasefile=passphrase
plaintextfile="plain.$$"


#-------------------------------------------
#  End configuration section
#-------------------------------------------
#pgmname=`basename $0`
#today=`date -u "+%Y-%m-%d"`

if ! cd $myhome 2>/dev/null ; then
    echo "gpgmlrobot: failed to cd to $myhome" >&2
    exit 1
fi

if [ -z "$ciphertextfile" -o "$ciphertextfile" = "-" ]; then
    ciphertextfile="input.$$"
    cat > $ciphertextfile
    remove_input=yes
fi

if [ ! -f "$ciphertextfile" ]; then
    echo "usage: gpgmlrobot encrypted-mail-file" >&2
    do_exit 1
fi

cleanup () {
  [ -f $plaintextfile ] && rm $plaintextfile
  [ -f $ciphertextfile -a "$remove_input" = "yes" ] && rm $ciphertextfile
}

do_exit () {
    cleanup
    exit $1
}


trap "cleanup " 1 2 13 15

do_send () {
    key="$1"
    recp="$2"
    ( cat <<EOF
Date:$orig_date
From:$orig_from
To: $full_ml_address
Subject:$orig_subject
Message-ID: $orig_msg_id
Mime-Version: 1.0
Content-Type: multipart/encrypted; protocol="application/pgp-encrypted";
	      boundary="x42x42x42x42x42x"
X-GPG-ML-Robot: 0.1
X-Loop: $ml_address
Precedence: list


--x42x42x42x42x42x
Content-Type: application/pgp-encrypted

Version: 1

--x42x42x42x42x42x
Content-Type: application/octet-stream

EOF
   (
  if [ $orig_is_mime = no ]; then
      echo "Content-Type: text/plain; charset=iso-8859-1"
      echo "Content-Transfer-Encoding: 8bit"
      echo " "
  fi
  cat /dev/null $plaintextfile
  echo "-- "
  echo "This message has been processed by the gpg-ml-robot"
  echo "and is made available to all subscribers of this ML:"
  echo $(cut -d ' ' -f 2- $distsfile ) | fold -s -w 70 
  ) | gpg --homedir . --no-secmem-warning --quiet --batch \
				   --always-trust -ea -r $key
echo ""
echo "--x42x42x42x42x42x--"
echo ""
    ) | $SENDMAIL -oi $recp
}


# see whether we have already handled this message
if [ "$(formail -x X-Loop: < $ciphertextfile)" = "failed-$ml_address" ]; then
    exit 0
fi

if [ "$(formail -x X-Loop: < $ciphertextfile)" = "$ml_address" ]; then
    ( formail -t -rI"Precedence: junk" \
		   -i"X-Loop: failed-$ml_address" < $ciphertextfile
      echo "Hi,"
      echo ""
      echo "Your mail has already been processed by this robot"
      echo 'and was hopefully delivered to all subscribers.'
      echo ""
      echo "Hochachtungsvoll,"
      echo ""
      echo "   G. M. Robot"
      echo ""
      echo "-- "
      echo "Powered by the GNU Privacy Guard"
    ) | $SENDMAIL -oi -t
   exit 0
fi

# Decrypt the file and encrypt it to each user in turn.
echo -n "" > $plaintextfile
chmod 600 $plaintextfile

cat $passphrasefile | gpg --homedir . --quiet --no-secmem-warning \
			  --passphrase-fd 0 --decrypt --batch --always-trust \
			 -o - $ciphertextfile >> $plaintextfile
if [ $? != 0 ] ; then
    ( formail -t -i"X-Loop: failed-$ml_address" < $ciphertextfile
      echo "Hi,"
      echo ""
      echo "Your mail could not been processed by this robot"
      echo 'probably because you did not encrypt it to the'
      echo "robot's key"
      echo ""
      echo "Hochachtungsvoll,"
      echo ""
      echo "   G. M. Robot"
      echo ""
      echo "-- "
      echo "Powered by the GNU Privacy Guard"
    ) | $SENDMAIL -oi -t
    exit 0
fi

if head -1 $plaintextfile | grep '^Content-Type: text/plain' >/dev/null; then
    orig_is_mime=yes
else
    orig_is_mime=no
fi

orig_date="$(formail -x Date: < $ciphertextfile)"
orig_subject="$(formail -x Subject: < $ciphertextfile)"
# We munch the message id to hide the posters informations
# This is not really need, because we use the orignal from line,
# but this can be changed when needed.
orig_msg_id="$(formail -x Message-ID < $ciphertextfile|md5sum)"
orig_msg_id="<${orig_msg_id}@${ml_domain}>"
orig_from="$(formail -x From: < $ciphertextfile)"

cat $distsfile | while read  ; do
    set -- $REPLY
    if [ -n "$1" -a -n "$2" ]; then
       do_send $1 $2
    fi
done

cleanup