#!/bin/bash

SENDMAIL='/var/qmail/bin/sendmail.qmail'
USER=$(id -un)
MIN_CUSTOMER_UID=10003
#BASEDIR=/tmp/mail-abuse
BASEDIR=/var/cache/mail-abuse
HISTORY_DB="${BASEDIR}/sendmail_history.${USER}.sqlite3"
MAX_SEND_MAIL=500
MAX_SEND_MAIL_TRIAL=100
TIME_PERIOD='-60 minutes'
KEEP_HISTORY='-7 days'
TRIAL_DAYS=7
USER_HOME_BASE='/virtual'
TIMESTAMP=$(date --date "${TRIAL_DAYS} days ago" +'%Y%m%d%H%M')
CHECKFILE="${BASEDIR}/trialcheck.${USER}"

# white list ids 202312
WHITELIST_UIDS=(10001 10002 10003) # Example UIDs in whitelist

# Get the hostname
HOSTNAME=$(hostname)

# Adjust MAX_SEND_MAIL based on hostname patterns 202312
if [[ $HOSTNAME == *s*.xrea.com* ]]; then
    MAX_SEND_MAIL=1000
elif [[ $HOSTNAME == *m*.xrea.com* ]]; then
    MAX_SEND_MAIL=100
elif [[ $HOSTNAME == *s*.coreserver.jp* ]]; then
    MAX_SEND_MAIL=2000
elif [[ $HOSTNAME == *m*.coreserver.jp* ]]; then
    MAX_SEND_MAIL=1000
elif [[ $HOSTNAME == *b*.coreserver.jp* ]]; then
    MAX_SEND_MAIL=3000
elif [[ $HOSTNAME == *c*.coreserver.jp* ]]; then
    MAX_SEND_MAIL=10000
elif [[ $HOSTNAME == *s*.valueserver.jp* ]]; then
    MAX_SEND_MAIL=2000
elif [[ $HOSTNAME == *e*.valueserver.jp* ]]; then
    MAX_SEND_MAIL=1000
elif [[ $HOSTNAME == *b*.valueserver.jp* ]]; then
    MAX_SEND_MAIL=5000
fi


init_sqlite3(){
    echo "CREATE TABLE IF NOT EXISTS history (
      id INTEGER PRIMARY KEY AUTOINCREMENT,
      user TEXT,
      pwd TEXT,
      count INTEGER,
      created_at DATETIME
    );" | sqlite3 ${HISTORY_DB}
    chmod 700 ${HISTORY_DB}
}

count_recipients(){
    echo -e "${STDIN}" | while read line
    do
        if [[ $line = '' ]];then
            echo "${RCPT_SUM}"
            break
        fi
        if [[ $line =~ ^[Tt][Oo] ]] || [[ $line =~ ^[Bb]?[Cc][Cc] ]];then
            for rcpt in `echo $line | tr ',' '\n'`
            do
                if [[ ${rcpt} =~ @ ]];then
                    RCPT_SUM=$(( ${RCPT_SUM=} + 1 ))
                fi
            done
        fi
    done
}

add_history(){
    echo "INSERT INTO history (user,pwd,count,created_at) values ('${USER}','$1',$2,datetime('now', 'localtime'));" | sqlite3 ${HISTORY_DB}
}

count_recent(){
    echo "SELECT sum(count) FROM history WHERE user = '${USER}' AND created_at > datetime('now','localtime','${TIME_PERIOD}');" | sqlite3 ${HISTORY_DB}
}

clear_old_history(){
    echo "DELETE FROM history WHERE created_at < datetime('now','localtime','${KEEP_HISTORY}');" | sqlite3 ${HISTORY_DB}
}

is_user_account(){
    ## user account's UID is begin from MIN_CUSTOMER_UID
    if [[ ${UID} -gt ${MIN_CUSTOMER_UID} ]];then
        echo "1"
    fi
}

get_sendlimit(){
    touch -t ${TIMESTAMP} ${CHECKFILE}
    chmod 700 ${CHECKFILE}
    user_home=$(echo $1 | cut -d/ -f1-3)
    if [[ "${user_home}" =~ "${USER_HOME_BASE}" && ${user_home} -nt ${CHECKFILE} ]];then
        echo ${MAX_SEND_MAIL_TRIAL}
    else
        echo ${MAX_SEND_MAIL}
    fi
    rm -f ${CHECKFILE}
}


# Whitelist implementation
if [[ " ${WHITELIST_UIDS[@]} " =~ " ${UID} " ]]; then
    STDIN=$(cat -)
    echo "${STDIN}" | ${SENDMAIL} $*
    exit 0
fi

## log caller information
logger -t "sendmail_wrapper" -p mail.info "PWD=${PWD}"

## check and create working dir
if [[ -f ${BASEDIR} ]];then
    rm -f ${BASEDIR}
fi
if [[ ! -d ${BASEDIR} ]];then
    mkdir ${BASEDIR}
    chmod 1777 ${BASEDIR}
fi

## init sqlite3 db file for history
if [[ ! -f ${HISTORY_DB} ]];then
    init_sqlite3
fi

## exit sendmail if this user sent more than limit
## system account can send mail anyway
IS_USER_ACCOUNT=$( is_user_account )
RECENT=$( count_recent )
SEND_LIMIT=$( get_sendlimit ${PWD} )
if [[ ${IS_USER_ACCOUNT} ]] && [[ ${RECENT} -gt ${SEND_LIMIT} ]];then
    echo "sendmail is not allowed. You sent too many mails"
    exit 1
fi

## run sendmail first.
STDIN=$(cat -)
echo "${STDIN}" | ${SENDMAIL} $*

## if non-user(system) account, don't have to record send history
if [[ ! ${IS_USER_ACCOUNT} ]]; then
    exit 0
fi

## count recipients
RCPTS=$( count_recipients )
if [[ ! -n "${RCPTS}" ]];then
    RCPTS=0
fi

## store to sendmail history
add_history ${PWD} ${RCPTS}

## suppress sqlite database grow too large
clear_old_history