#!/bin/sh
# dyndns via ssh login + tinydns (djbdns/dbndns)
#
# usage:
# $ ssh dyndns@example.org home.example.org
#
# @author Christian Weiske <cweiske@cweiske.de>

if [ -z "$SSH_CONNECTION" ]; then
   echo "no ssh connection" >&2
   exit 1
fi

remoteip=${SSH_CLIENT%% *}
if [ -z "$remoteip" ]; then
   echo "ssh client IP not found" >&2
   exit 2
fi

#TODO: allow removal of domains
#TODO: support multiple domains
if [ -z "$2" ]; then
    echo Missing argument: domain name >&2
    exit 3
fi
domain="$2"

#load config files
if [ -f ~/.config/ssh-dyndns.sh ]; then
    . ~/.config/ssh-dyndns.sh
fi
if [ -f /etc/ssh-dyndns.sh ]; then
    . /etc/ssh-dyndns.sh
fi

if [ -z "$data_dir" ]; then
    echo '$data_dir not set' >&2
    exit 4
fi
if [ ! -d "$data_dir" ]; then
    echo "$data_dir does not exist" >&2
    exit 5
fi
if [ ! -f "$data_dir/Makefile" ]; then
    echo "$data_dir misses Makefile" >&2
    exit 6
fi

if [ ! -z "$domain_patterns" ]; then
    ok=0
    for single_dp in $domain_patterns; do
        case "$domain" in
            ($single_dp) ok=1;;
        esac
    done
    if [ $ok -ne 1 ]; then
        echo "Domain \"$domain\" does not match \$domain_pattern" >&2
        exit 7
    fi
fi


file_pattern="${file_pattern:-data-dyndns-%DOMAIN%}"
timeout=${timeout:-300}

datafile=${data_dir}`echo $file_pattern | sed "s/%DOMAIN%/$domain/"`

if [ `echo "$remoteip"| sed "s/://"` != "$remoteip" ]; then
    echo "IPv6 not supported yet" >&2
    # we need ipv6 address expansion
    exit 8
fi

#=cweiske.de:5.35.241.22
djbdnsline="=${domain}:${remoteip}:${timeout}"

update=1
if [ -f "$datafile" ]; then
    currentdata=`head -n1 "$datafile"|tr -d '\n'`
    if [ "$currentdata" = "$djbdnsline" ]; then
        #no need to update
        update=0
    fi
fi
if [ $update -eq 0 ]; then
    exit
fi

echo $djbdnsline > $datafile

#TXT record with last update
date=`date --rfc-3339=seconds|tr : .|tr -d '\n'`
djbdnsTxtLine="'${domain}:Last update ${date}.:${timeout}"
echo $djbdnsTxtLine >> $datafile

#compile dns data
cd "$data_dir"
sudo make --silent