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#
# reto_procmail.recipe - Check message with crm114
#
# Copyright 2004 Reto Lichtensteiger
# Copyright 2004-2009 William S. Yerazunis.
# This file is under GPLv3, as described in COPYING.
#


# NOTE: This recipe invokes crm114 on a message. It does NOT filter
# the message to a spam folder.  How you choose to manage that task
# up to you.
#

CRM="/usr/local/bin/crm"
CRMDIR="${HOME}/.crm114"
UTRACE=""                       # -t turns on crm script tracing

CRMVERSION="`${CRM} '-{ output /:*:_crm_version:/}' < /dev/null` [stats_only]"

#
# It is possible for crm114 to DoS if it receives a very large message.
# To prevent this, the author has coded an upper bound to the size
# message that mailfilter.crm will accept.
#
# We can prevent messages from hitting that limit by only feeding a
# portion of the message to crm114, but this has a slightly more
# subtle problem in that messages are often fed to crm114 as filters,
# which means procmail expects the message to be modified. Using
# head(1) to limit the message size going into a filter recipe will
# truncate the actual message, not just a copy. "Oops"
#
# This recipe set uses crm114 as a direct "f"ilter if the message is
# smaller than $BIGGEST, otherwise the message is truncated with head
# and crm114 is set (via "--stats_only" switch) to report only. The
# output from crm114 when run in this mode is captured and formail is
# used to put the same headers in place that crm114 would normally
# add.
#

BIGGEST="20000"

:0
* < ${BIGGEST}
{
  :0 fw
  | ${CRM} ${UTRACE} -u ${CRMDIR} mailfilter.crm

  # if crm114 failed, return the mail to the queue where the MTA will
  # retry delivery at a later date.  (EX_TEMPFAIL in /usr/include/sysexits.h)

  :0 e
  { EXITCODE=75 }
}

#
# If the first recipe doesn't match the size test, then the message is
# larger than ${BIGGEST}
#

:0 E
{
  # For programs invoked via backtick operator, procmail puts the mail
  # message on stdin.  The line below feeds the mail message through
  # head to truncate it and then into crm114.

  CRMOUT="`head -c ${BIGGEST} | ${CRM} -u ${CRMDIR} mailfilter.crm --stats_only\`"

  # If CRMOUT is undefined (or empty) then crm114 failed. Set the exit
  # code to 75, so that procmail uses that as an exitcode. THe MTA
  # that invoked procmail will see that as "TEMPFAIL" and requeue the
  # message. THe script then unsets the HOST variable to tell procmail
  # to exit.

  :0
  * CRMOUT ?? ^^^^
  {
    EXITCODE=75
    HOST
  }

  :0
  * CRMOUT ?? ^-
  { VALUE="SPAM" }

  :0 E
  { VALUE="Good" }

  :0 f
  | formail -A "X-CRM114-Version: ${CRMVERSION}" \
            -A "X-CRM114-Status: ${VALUE}  ( pR: ${CRMOUT})"

  CRMOUT
  VALUE
}

:0
* ^X-CRM114-Status: SPAM
{ LOG="SPAM: CRM114 (Sure)${NL}" }

# Unset variables
CRM
CRMDIR
CRMVERSION
UTRACE