#!/bin/bash
##############################################################################
#
# qmail SPP-Plugin "goodmailto.sh"
#     See http://qmail-spp.sourceforge.net
#     Only accept "RCPT TO"-Addresses in "control/goodmailfrom" file
#     Version 1.4, Stefan Onderka, 2016-02-10
#
# Location:
#     /var/qmail/plugins/goodmailto.sh
#
# Activation (in /var/qmail/control/smtpplugins):
#    [rcpt]
#    :plugins/goodmailto.sh
#    # Don't forget the ":" to exec a shell
#
# We have:
#     $SMTPRCPTTO   - "argument of last 'RCPT' command"
#     $SMTPHELOHOST - HELO hostname
#     goodmailto    - file with "user"-parts of existing accounts
#     $NOGOODMAILTO - If set to 1 test is skipped (mail in -> out f.e.)
#                     Else test is performed (mail out -> in f.e.)
#
# We respond:
#    "H<some mail-header>"
#    ... if $SMTPRCPTTO is accepted (existing mail account)
#
#    "H<some mail-header>"
#    "E<smtp error message>"
#    ... if $SMTPRCPTTO is not accepted (non-existing mail account)
#
#    "H<some mail-header>"
#    ... if "goodmailto" is not readable (In dubio pro reo)
#
# Outputs (see http://qmail-spp.sourceforge.net/doc/):
#    "Hmsg" - Sets mail-header msg
#    "Rmsg" - Sends smtp-message xxx and drops connection
#
##############################################################################
#
# SMTP Code 550 (permanent error):
#    Requested action not taken: mailbox unavailable (e.g., mailbox not
#    found, no access, or command rejected for policy reasons)
#
# Variables
##############################################################################
# PID
MY_PID=$$
# Logfile
LOGFILE="/var/log/mail/mail.goodmailto_plugin"
# RCPT TO - address from environment
LOOKUP_ADDR=$SMTPRCPTTO
# Logging prefix
LOG_STRING="plugins/goodmailto [${MY_PID}]"
# goodmailto - file
GOODMT="/var/qmail/control/goodmailto"
# Response: RCPT TO not OK
SMTP_ERROR="550 No mailbox or alias named"
# Response: RCPT TO OK
SMTP_OK="250 ok"
# Our smtp-error as number
SMTP_ERROR_NUMBER="(#5.1.1)"
# Timestamp
TIMESTAMP=`date +"%Y-%m-%d %H:%M:%S"`

# Our mail-header - added to see if a certain msg has been processed by plugin
##############################################################################
CUST_HEADER="X-GoodMailTo:"
CUST_FOUND="Rcpt found"
CUST_NOTFOUND="Rcpt not found"
CUST_SKIPPED="Skipped"
CUST_ERROR="File Error (/var/qmail/control/goodmailto)"

# $NOGOODMAILTO set? (via tcprules): skip check, accept and exit
##############################################################################
if [  -n "${NOGOODMAILTO+x}" ]; then
   echo "H$CUST_HEADER $CUST_SKIPPED"
   echo $SMTP_OK
   echo "${LOG_STRING}: [$SMTPHELOHOST] from: $SMTPMAILFROM to: $SMTPRCPTTO status: $CUST_SKIPPED" >&2
   #echo "$TIMESTAMP ${LOG_STRING}: $SMTPHELOHOST $SMTPMAILFROM to: $SMTPRCPTTO status: $CUST_SKIPPED" >> $LOGFILE
   exit 0
fi

if [ -r $GOODMT ]; then
   # File /var/qmail/control/goodmailto readable
   ###########################################################################
   GOODMAILTO_ALL=`cat $GOODMT`
   # "User"-part only - checking for a valid domain is not our job...
   NAMEPART=`echo $LOOKUP_ADDR | cut -d"@" -f1`

   # Find RegEx - case insensitive, on one line, no more, no less
   ###########################################################################
   if `cat ${GOODMT} | egrep -i "^${NAMEPART}$" 1> /dev/null 2>&1`
   then
      # Found in goodmailto - accept
      echo "H$CUST_HEADER $CUST_FOUND (${NAMEPART})"
      echo $SMTP_OK
      echo "${LOG_STRING}: $SMTPHELOHOST from: $SMTPMAILFROM to: $SMTPRCPTTO status: $CUST_FOUND" >&2
      #echo "$TIMESTAMP ${LOG_STRING}: $SMTPHELOHOST from: $SMTPMAILFROM to: $SMTPRCPTTO status: $CUST_FOUND" >> $LOGFILE
      exit 0
   else
      # Not found in goodmailto - deny
      echo "H$CUST_HEADER $CUST_NOTFOUND (${NAMEPART})"
      echo "E$SMTP_ERROR $NAMEPART $SMTP_ERROR_NUMBER"
      echo "${LOG_STRING}: $SMTPHELOHOST from: $SMTPMAILFROM to: $SMTPRCPTTO status: $CUST_NOTFOUND" >&2
      #echo "$TIMESTAMP ${LOG_STRING}: $SMTPHELOHOST from: $SMTPMAILFROM to: $SMTPRCPTTO status: $CUST_NOTFOUND" >> $LOGFILE
      exit 0
   fi
else
   # File /var/qmail/control/goodmailto not readable
   ###########################################################################
   # Accept
   echo "H$CUST_HEADER $CUST_ERROR"
   echo $SMTP_OK
   echo "${LOG_STRING}: $SMTPHELOHOST from: $SMTPMAILFROM to: $SMTPRCPTTO status: $CUST_ERROR" >&2
   #echo "$TIMESTAMP ${LOG_STRING}: $SMTPHELOHOST from: $SMTPMAILFROM to: $SMTPRCPTTO status: $CUST_ERROR" >> $LOGFILE
fi