#!/bin/bash
#
# Andrew's kick-ass chkrcpt script for qmail+vpopmail
# Author: aschwabe@gmail.com
# 
# This script makes qmail check for the existance of a user before email is accepted.
# Will check vpopmail accounts, and look for .qmail* files to determine real accounts.
# Logs all checks in the /var/log/maillog, and then refers to it to throttle spammers.

set -- $RECIPIENT
set -- $SENDER
MY_TEST=""

#echo `whoami`

if [ "$RECIPIENT" == "" ]; then
  # uncomment these lines and the "echo" lines throughout to test at the command line
  #echo "sender:"
  #read SENDER
  #echo "recipient:"
  #read RECIPIENT
  exit 100
fi

# email sender addresses explicitly allowed:
allowed[1]="soundoff3@iexp.com"
allowed[2]="soundoff3@iexp.net"
for index in 1 2
do
  if [ "$SENDER" == "${allowed[index]}" ]; then
        /usr/bin/logger -p mail.info -t vchkrcpt "mail from <$SENDER> to <$RECIPIENT> : ok (sender explicitly allowed: ${allowed[index]})"
	exit 0
  fi
done

USERPART=`echo "$RECIPIENT" |cut -d@ -f1`
DOMAIN=`echo "$RECIPIENT" |cut -d@ -f2`

# We reject any emails with more than one @ sign
THIRDPART=`echo "$RECIPIENT" |cut -d@ -f3`
if [ "$THIRDPART" != "" ]; then

  #echo "Invalid username - multiple or no @ signs"
  /usr/bin/logger -p mail.info -t vchkrcpt "mail from <$SENDER> to <$RECIPIENT> : illegal username"
  exit 100

fi

# We reject any emails with ! in the name
EXCL_CHECK=`echo $USERPART |grep '!' >/dev/null 2>&1; echo $?|grep "1" > /dev/null 2>&1 ; echo $?`
if [ "$EXCL_CHECK" == "1" ]; then

  #echo "Invalid username"
  /usr/bin/logger -p mail.info -t vchkrcpt "mail from <$SENDER> to <$RECIPIENT> : illegal username"
  exit 100

fi

# We reject any emails with a percent sign in the name
PERCENT_CHECK=`echo $USERPART |grep '%' >/dev/null 2>&1; echo $?|grep "1" > /dev/null 2>&1 ; echo $?`
if [ "$PERCENT_CHECK" == "1" ]; then

  #echo "Invalid username"
  /usr/bin/logger -p mail.info -t vchkrcpt "mail from <$SENDER> to <$RECIPIENT> : illegal username"
  exit 100

fi

# We reject if this sender has had 3 or more bad recipients recently
if [ "$SENDER" != "" ]; then

    SPAMMER_CHECK=`tail -n800 /var/log/maillog|grep vchkrcpt|grep $SENDER |grep 'bounce-no-mailbox'|wc -l`
    #echo 'result of spammer check:'
    #echo $SPAMMER_CHECK

    if [ "$SPAMMER_CHECK" -gt "2" ]; then
        #echo "Too many invalid recipients.  Mail will not be accepted."
  	/usr/bin/logger -p mail.info -t vchkrcpt "mail from <$SENDER> to <$RECIPIENT> : spammer=bounce-no-mailbox"
        exit 100
    fi
fi

# check for valid account
MY_TEST=`/home/vpopmail/bin/vuserinfo -d $RECIPIENT |/usr/bin/head -n1`

if [ "$MY_TEST" == "" ] || [ "${MY_TEST:0:7}" == "no such" ]; then

  # it wasn't a real pop user, so check if its an alias
  MY_TEST=`/home/vpopmail/bin/valias $RECIPIENT|/usr/bin/head -n1`

  # if the address has a dash in it, re-build a default alias address
  USER_ALIAS_CHECK=`echo $USERPART |grep '\-' >/dev/null 2>&1; echo $?|grep "1" > /dev/null 2>&1 ; echo $?`
  if [ "$USER_ALIAS_CHECK" == "1" ]; then
    ALIAS_USERPART=`echo $USERPART | cut -d - -f1`
    ALIAS_USERPART=$ALIAS_USERPART"-default"
    ALIAS_RECIPIENT=$ALIAS_USERPART"@"$DOMAIN
    MY_TEST2=`/home/vpopmail/bin/valias $ALIAS_RECIPIENT|/usr/bin/head -n1`
  else
    MY_TEST2=""
  fi

  if [ "$MY_TEST" != "" ]; then

    # this is a valid alias
    #echo "valid alias"
    /usr/bin/logger -p mail.info -t vchkrcpt "mail from <$SENDER> to <$RECIPIENT> : alias ok"
    exit 0

  elif [ "$MY_TEST2" != "" ]; then

    # this is a valid user alias
    #echo "valid user-alias"
    /usr/bin/logger -p mail.info -t vchkrcpt "mail from <$SENDER> to <$RECIPIENT> : user-alias ok"
    exit 0

  else

    # look for a .qmail-default file, and see it if has a real account in it

    DEFAULT_RECIPIENT="default@"$DOMAIN 
    #echo "default recipient = $DEFAULT_RECIPIENT"

    DEFAULT_BOUNCE=`/home/vpopmail/bin/valias $DEFAULT_RECIPIENT | /usr/bin/head -n1|grep bounce-no-mailbox \
	>/dev/null 2>&1; echo $? |grep "1" > /dev/null 2>&1 ; echo $?`
    #echo "DEFAULT_BOUNCE result = $DEFAULT_BOUNCE"

    if [ "$DEFAULT_BOUNCE" == "1" ]; then
      #echo ".qmail-default = bounce"
      #echo "invalid recipient"
      /usr/bin/logger -p mail.info -t vchkrcpt "mail from <$SENDER> to <$RECIPIENT> : catchall=bounce-no-mailbox"
      exit 100
    fi

    DEFAULT_DELETE=`/home/vpopmail/bin/valias $DEFAULT_RECIPIENT | /usr/bin/head -n1|grep ' delete' \
	>/dev/null 2>&1; echo $? |grep "1" > /dev/null 2>&1 ; echo $?`
    #echo "DEFAULT_DELETE result = $DEFAULT_DELETE"

    if [ "$DEFAULT_DELETE" == "1" ]; then
      #echo ".qmail-default = delete"
      #echo "invalid recipient"
      /usr/bin/logger -p mail.info -t vchkrcpt "mail from <$SENDER> to <$RECIPIENT> : catchall=delete"
      exit 100
    fi

    MY_TEST=`/home/vpopmail/bin/valias $DEFAULT_RECIPIENT | /usr/bin/head -n1`
    #echo "ALIAS DEFAULT result = $MY_TEST"

    if [ "$MY_TEST" == "" ]; then

      #echo "invalid recipient (no default alias)"
      /usr/bin/logger -p mail.info -t vchkrcpt "mail from <$SENDER> to <$RECIPIENT> : catchall=none"
      exit 100

    else

      #echo "valid recipient (.qmail-default)"
      /usr/bin/logger -p mail.info -t vchkrcpt "mail from <$SENDER> to <$RECIPIENT> : catchall=ok"
      exit 0

    fi

  fi

else

  #echo "valid mailbox"
  /usr/bin/logger -p mail.info -t vchkrcpt "mail from <$SENDER> to <$RECIPIENT> : account ok"
  exit 0

fi