#!/bin/bash
# A wrapper for SpamAssassin suitable for calling from a dot-qmail file
# Version: 0.1
#
# Usage:
#  |ifspamloop mail-address spam-address virus-address spamc-user
#
# spamc-user is the user ID passed to spamc.  It controls selection of
# the user's black/white lists, bayes rules, etc.  Not used if you
# don't use the -u option to spamc.
#
# mail-address is an address that is sent to THIS mailbox.  Emails that
# are scanned by Spamassassin will be forwarded to this address to be
# reprocessed.
#
# spam-address is an email address that you want all spam forwarded to.
# It may be the same as mail-address.
#
# virus-address is an email address that you want all virus-infected
# emails to be forwarded to.  It may be the same as email-address.
#
# Mail that has already been scanned by Spamasssassin, or is to large 
# for Spamassassin to deal with, will be passed to the rest of the 
# .qmail file for further processing.
# 
# This script is based on James Grinter's ifspamh script.
# www.gbnet.net/~jrg/qmail/ifspamh/
#
# I want to have the scanned and annotated email available to the 
# entire .qmail file.  I also want emails that contan viruses to be
# forwarded to a quarantine box.  In my installation, the non-virus
# spams are left in the box for the MUA to filter.  The scanned
# emails my also be forwarded to other addresses, some of which are
# on my server.  I want an email to be presented to Spamassassin 
# only once, no matter how many boxes it goes to.
#
# A typical .qmail file might look like this:
#    |ifspamloop mark@example.com mark@example.com sharps@example.com example.com
#    ./Maildir/
#    &alterego@example.com
# 
# You should set Spamassassin to insert a custom header to indicate 
# that the email has been scanned by YOUR server.  I use the following 
# in my configuration:
#    add_header all ScannedBy DataHelper, Inc.
#
# For more details on SpamAssassin, how to set preferences, whitelists,
# etc, see 'Mail::SpamAssassin::Conf(3)' - and put the preferences
# in ~/.spamassassin/user_prefs
#
# For more detail on .qmail files, see dot-qmail(5) and qmail-command(8)
# 
# Author of ifspamh: James R Grinter
# jrg (at) watching.org 24/03/2002
# Last Update: 28/02/2003
# URL: http://www.gbnet.net/~jrg/qmail/ifspamh/
#
# Requires: spamc, spamd, qmail and 822field (from DJB's mess822 package)
# to be installed and working.
#
# Also requires your /bin/sh to have a "printf" available
# (most do, if yours doesn't then consider fetching ksh-93
# from http://www.research.att.com/sw/download/, or using bash)
#
# N.B.
# If you are using vpopmail, make sure you are using at least
# version 5.3.6.
#
# If you want to run SpamAssassin globally for every email, see the
# qmail-spamc/qmail-scanner approach in the qmail/ subdirectory of the
# SpamAssassin distribution
#
# Author of ifspamloop: Mark Willcox
# willcox (at) datahelper.com
# Last Update: 02/27/2005
# http://datahelper.com/download/ifspamloop/

######    Change these values!    ######
# The custom header and value that identify your spamassassin
CUSTOMHEAD=ScannedBy
CUSTOMVALUE="Your Message Here"

# spamc - client location - followed by "-u " if you specify a user.
SPAMC="/usr/bin/spamc -u"
# qmail's forward program location
FORWARDBIN=/var/qmail/bin/forward
# mess822 822field location
M822FIELD=/usr/local/bin/822field


#################################################################
# nothing beyond here should require adjustment
#################################################################

LOOPADDR="$1"
SPAMADDR="$2"
VIRUSADDR="$3"
USERID="$4"

if [ -z "$VIRUSADDR" ]; then
  echo "Usage: ifspamloop this-box's-address spam-address virus-address [userID] "
  exit 111
fi

output="`head -c250100`"

# spamc will not process a "large email"
msize=`echo "$output" | wc -c`
# there's also a sizelimit with some shells that triggers around the 512kB mark
# with an external printf and arguments size so we stop at this point
if [ $msize -gt 250000 ]; then
  # probably deemed too large anyway .. let it through
  exit 0
fi

# Have we seen this email before?  Is it already scanned?
flagvalue=`printf "%s\n" "$output" | $M822FIELD X-Spam-$CUSTOMHEAD` 
flgvalue=`echo $flagvalue | grep "$CUSTOMVALUE"`
if [ -n "$flagvalue" ]; then
  # Regardless of this email's spammness or infectedness, let it be processed by the
  # rest of the .qmail file.  If there is an email address to send spam and viruses
  # to, it's already been sent there.
  exit 0
fi

output="`echo "$output" | $SPAMC $USERID`"
exitcode=$?

# We've gotten this far and called spamc.  We will NOT exit with 0 below here.
# We will either forward the email to one of the supplied addresses or exit
# with 111 to try it again.

# Virus found?
flagvalue=`printf "%s\n" "$output" | $M822FIELD X-Spam-Virus | sed -e 's/^ //' -e 's/ .*//'`
echo "$flagvalue" > /tmp/ifspamloop
if [ "$flagvalue" = "Yes" ]; then
  export DTLINE=
  printf "%s\n" "$output" | $FORWARDBIN $VIRUSADDR
  if [ $? -eq 0 ]; then
    # so qmail will not do any further deliveries in .qmail file
    exit 99
  fi
  # problem calling inject - temp failure
  exit 111
fi

# Spam found?
flagvalue=`printf "%s\n" "$output" | $M822FIELD X-Spam-Flag | sed 's/^ //'`
if [ "$flagvalue" = "YES" ]; then
  export DTLINE=
  printf "%s\n" "$output" | $FORWARDBIN $SPAMADDR
  if [ $? -eq 0 ]; then
    # so qmail will not do any further deliveries in .qmail file
    exit 99
  fi
  # problem calling inject - temp failure
  exit 111
fi

# Neither spam nor virus.  Sen it to the address that's supposed to 
# deliver it back here.

export DTLINE=
printf "%s\n" "$output" | $FORWARDBIN $LOOPADDR
if [ $? -eq 0 ]; then
  # so qmail will not do any further deliveries in .qmail file
  exit 99
fi
# problem calling inject - temp failure
exit 111