Shell Programming and Scripting

#!/bin/bash

MSMTP="/usr/bin/msmtp"
TMPDIR="/var/tmp/smtpdd"
TMPFILENAME="mailqfile.$RANDOM.`date +%s`.$$"
LOCKFILE="$1/.smtpdd.lck"

EX_TEMPFAIL=75

printUsage()
{
    echo "Usage: `basename $0` queue-directory sender recipient hostname|ip:port:mode [hostname|ip:port:mode ...]"
    echo "     : `basename $0` queue-directory qrun";
    echo "Where mode is q for queuing delivery, d for just drop it or o to just queue the mail - defaults to q"
}

attemptDelivery()
{
    qd=$1
    mail=$2
    host=`basename $1`
    
    from=`cat $mail|cut -f 1 -d " "`
    to=`cat $mail|cut -f 2 -d " "`
    
    hostname=`echo $host|cut -f 1 -d :`
    port=`echo $host|cut -f 2 -d :`
    
    if [ ! -f $mail.body ]
    then
        echo "Cannot delivery mail, mail body is missing"
        exit $EX_TEMPFAIL
    fi
    
    #echo "attmpting delivery of $2 from $1 as $from and $to to host $hostname with port $port"
    $MSMTP --host $hostname --port $port -f $from $to < $mail.body
    if [ $? == 0 ]
    then
        echo "Message delivered, deleting"
        rm -f $mail $mail.body
    else
        echo "Message delivery failed, leaving in place"
    fi
}

queueRun()
{
    for dirs in $1/*
    do
        if [ -d $dirs ]
        then
            old_pwd=$PWD
            cd $dirs
            for mail in *.qf
            do
                if [ -f $mail ]
                then
                    attemptDelivery "$dirs" "$mail"
                fi
            done
            cd $old_pwd
        fi
    done
}

mainRun()
{
    if [ ! -d $TMPDIR ]
    then
        mkdir $TMPDIR
        if [ $? != 0 ]
        then
            echo "Tempdirectory configuration problem with $TMPDIR - cannot create directory"
            logger -p mail.error -t smtpdd "Temp directory configuration problem with $TMPDIR - cannot create directory"
            exit $EX_TEMPFAIL
        fi
    fi
    
    chmod 0700 $TMPDIR
    
    queuedir=$1
    from=$2
    to=$3
    
    # should loop until it finds a unique filename
    while [ -f $TMPDIR/$TMPFILENAME ]
    do
        TMPFILENAME="$TMPFILENAME.$RANDOM"
        # echo "File exists already, generating new one, $TMPFILENAME"
    done
    
    cat > $TMPDIR/$TMPFILENAME
    
    for host in ${@:4}
    do
        #echo "attempting $2 to $3 for $host"
        
        hostname=`echo $host|cut -f 1 -d :`
        port=`echo $host|cut -f 2 -d :`
        mode=`echo $host|cut -f 3 -d :`
        if [ "x$mode" == "x" ]
        then
            mode="q"
        fi

        queueit="no"
        
        logger -p mail.info -t smtpdd "Attempting delivery of mail from $2 to $3 for host $hostname on $port with mode of $mode" 
        
        if [ "$mode" != "o" ]
        then
            # attempt real delivery
            $MSMTP --host $hostname --port $port -f $from $to < $TMPDIR/$TMPFILENAME > /dev/null 2>&1
            RET=$?
            if [ $RET != 0 ]
            then
                if [ $RET != "75" ]
                then
                    logger -p mail.info -t smtpdd "Mail delivery for $3 has failed"
                    echo "Mail delivery for $3 has failed (unknown user?)"
                    exit $RET
                fi
                # we failed to deliver ....
                # in queue mode, we deliver to the queue
                if [ "$mode" == "q" ]
                then
                    #echo "Delivery of mail to $hostname on $port from $from to $to has failed, but will be queued ($RET)" 
                    logger -p mail.warning -t smtpdd "Delivery of mail to $hostname on $port from $from to $to has failed, but will be queued ($RET)"
                    queueit="yes"
                fi
                
                # delete mode
                if [ "$mode" == "d" ]
                then
                    logger -p mail.info -t smtpdd "Delivery of mail to $hostname on $port from $from to $to has failed and will not be re-tried (delete mode)"
                    randomtext="asdf"
                fi
            else
                logger -p mail.info -t smtpdd "Delivery of mail to $hostname on $port from $from to $to has succeeded"
                randomtext="asdf"
            fi
        else
            echo "In queue only mode, will queue"
            logger -p mail.info -t smtpdd "In queue-only mode, will queue mail until a queue run is performed"
            queueit="yes"
        fi
        
        if [ $queueit == "yes" ]
        then
            echo "queueing"
            mkdir -p $queuedir/$hostname:$port
            i=0
            while [ -f $queuedir/$hostname:$port/mailf.$$.$i.qf ]
            do
                i=$(( $i + 1 ))
            done
            cp $TMPDIR/$TMPFILENAME $queuedir/$hostname:$port/mailf.$$.$i.qf.body
            echo $from $to > $queuedir/$hostname:$port/mailf.$$.$i.qf
        fi
    done
    
    rm -f $TMPDIR/$TMPFILENAME
}


if [ "x$1" == "x" ]
then
    printUsage
    exit $EX_TEMPFAIL
fi

if [ ! -d $1 ]
then
    echo "queue-directory specified, $1, must exist"
    exit $EX_TEMPFAIL
fi

if ! touch $1/.fml
then
    echo "queue-directory specified, $1, must exist and be writable"
    exit $EX_TEMPFAIL
else
    rm -f $1/.fml
fi

chmod 0700 $1

exec 8>> $LOCKFILE

if [ "x$2" == "xqrun" ]
then
    if flock -n -e 8
    then
        queueRun "$1"
        exit 0
    else
        logger -p mail.warning -t smtpdd "Queue directory locked, must exit from qrun"
        exit $EX_TEMPFAIL
    fi
fi

if [ "x$4" == "x" ]
then
    printUsage
    exit $EX_TEMPFAIL
fi

if flock -n -s 8
then
    mainRun $@
else
    logger -p mail.warning -t smtpdd "Cannot obtain shared lock - will not deliver right now"
    exit $EX_TEMPFAIL
fi