#!/bin/sh
#
# Configure a machine without exim installed as a mail server receiving
# email using SMTP via Tor.

append_if_missing() {
    file="$1"
    string="$2"
    if [ -f "$file" ] && grep -xq "$string" "$file" ; then
        :
    else
        (
            if [ -f "$file" ] ; then cat "$file" ; fi
            echo "$string"
        ) > "$file.new" && mv "$file.new" "$file"
    fi
}

DEBIAN_FRONTEND=noninteractive apt-get install -y tor xinetd
torhsdir=$(awk '/^HiddenServiceDir (.*) *$/ { print $2 }' /etc/tor/torrc)
if [ -e "$torhsdir/hostname" ] ; then
   torhsname=$(cat "$torhsdir/hostname")
else
    echo "*******************************************************************"
    echo "* Added Tor hidden service for SMTP (port 25)                     *"
    echo "*******************************************************************"
    append_if_missing /etc/tor/torrc \
	"HiddenServiceDir /var/lib/tor/hidden_service/"
    append_if_missing /etc/tor/torrc \
	"HiddenServicePort 25 127.0.0.1:25"
    mkdir -p /var/lib/tor/hidden_service
    chown debian-tor:debian-tor /var/lib/tor/hidden_service
    chmod og-rwx /var/lib/tor/hidden_service
    service tor restart
    if [ -e "$torhsdir/hostname" ] ; then
	torhsname=$(cat "$torhsdir/hostname")
    else
	echo "error: unable to set up Tor hidden service"
	exit 1
    fi
fi

if dpkg -l exim4-config > /dev/null ; then
    echo "******************************************************************"
    echo "* Unable to set up SMTP over Tor, exim4-config already installed *"
    echo "* Purge the package and try again, or                            *"
    echo "* run "dpkg-reconfigure exim4-config" to configure manually.     *"
    echo "******************************************************************"
    echo "* Enable '$torhsname' as mail domain.
    exit 1
fi

cat <<EOF | debconf-set-selections
exim4-config	exim4/dc_eximconfig_configtype	select	internet site; mail is sent and received directly using SMTP
exim4-config	exim4/dc_local_interfaces	string	127.0.0.1 ; ::1
exim4-config	exim4/dc_other_hostnames	string	$torhsname
exim4-config	exim4/use_split_config	boolean	true
EOF

DEBIAN_FRONTEND=noninteractive apt-get install -y exim4