#!/bin/bash
########################################################################
#  Copyright (C) 2016 Max Mehl <mail [at] mehl [dot] mx>
########################################################################
#  
#  This program is free software: you can redistribute it and/or modify
#  it under the terms of the GNU General Public License as published by
#  the Free Software Foundation, either version 3 of the License, or
#  (at your option) any later version.
#  
#  This program is distributed in the hope that it will be useful,
#  but WITHOUT ANY WARRANTY; without even the implied warranty of
#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#  GNU General Public License for more details.
#  
#  You should have received a copy of the GNU General Public License
#  along with this program.  If not, see <http://www.gnu.org/licenses/>.
#  
########################################################################
#  
#  Client part of the "Snap DynDNS Server", grabbing public IP address 
#  and pushing it to the server handling the more complicated API stuff
#  
########################################################################


cd "$(dirname "$(readlink -f "$0")")"

# Test if config.cfg exists and set needed variables
if [ ! -e config.cfg ]; then echo "Missing config.cfg file. Edit and rename config.cfg.sample"; exit 1; fi
source config.cfg

# Test whether necessary applications are installed
function testinst {
  APP=$1
  if [ $(which $APP | wc -l) != 1 ]; then
    echo "$APP does not seem to be installed. Aborting."
    exit 1
  fi
}
testinst curl
testinst wget

# Does the old.ip file exist? If not, fill it with unrealistic input
if [ ! -e old.ip ]; then
    echo "0.0.0.0" > old.ip
fi

# Read old IP, gather new IP via IP return service
OLDIP=$(cat old.ip)
NEWIP=$(wget -T $TIMEOUT -q -O - $IPSERV)

# Post current timestamp in logfile
echo "[$(date "+%Y-%m-%d %H:%M:%S")]" > update.log

# check whether the IP has changed since the last update
if [ "$OLDIP" == "$NEWIP" ]; then
    echo "IP ($OLDIP) did not change. Aborting." >> update.log
    exit 0
fi

# Check whether IP is on ignore list
if [ $(echo "$IGNOREIP" | grep "$NEWIP") ]; then
    echo "Current IP ($NEWIP) is ignored. Aborting without DNS update." >> update.log
    exit 0
fi

# Check whether user is using a Tor exit node IP
if [ "$CHECKTOR" = true ]; then
  # Only download list of exit nodes if tor-ips.txt file isn't existing yet, or if it is older than 7 days
  if [ ! -e tor-ips.txt ] || [ $[ $(date +%s) - $(stat -L -c %Y tor-ips.txt) ] -gt "604800" ]; then
    # download list, extract plain IPs, move back to file
    echo "download list"
    wget -O tor-ips.txt $EXITNODES
    TORIPS=$(grep "^ExitAddress" tor-ips.txt | cut -d" " -f2)
    echo $TORIPS | sed 's/ /\n/g' > tor-ips.txt
  fi
  # Grep current IP in list of exit node IPs
  if [ $(grep "^$NEWIP$" tor-ips.txt) ]; then
    echo "Current IP ($NEWIP) is ignored because it is a Tor exit IP. Aborting without DNS update." >> update.log
    exit 0
  fi
fi

# Run update if old IP and current IP are not equal
if [ ! "$OLDIP" == "$NEWIP" ]; then
    echo $NEWIP > old.ip
    
    curl -X POST -d "domain=$DOMAIN&user=$USER&pass=$PASS&ip=$NEWIP" "$SERVER" >> update.log
    
    echo "" >> update.log
    echo "Updated IP address from $OLDIP to $NEWIP." >> update.log
fi