snap-dyndns-client/dnsupdate.sh

#!/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")")"

print_usage() {
  echo "dnsupdate.sh [-c configfile]"
}

while getopts c:h OPT; do
  case $OPT in
    c)  CONFIG=$OPTARG;;  # type: normal or docker
    h)  print_usage; exit 0;;
    *)  echo "Unknown option: -$OPTARG"; print_usage; exit 1;;
  esac
done

if [ -z $CONFIG ]; then
  CONFIG="config.cfg"
fi

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

# 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

# Loop over all hosts. $i will be key
for i in "${!USER[@]}"; do
  oldip="old-$i.ip"
  logfile="update-$i.log"

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

  # Read old IP, gather new IP via IP return service
  OLDIP=$(cat "$oldip")
  NEWIP=$(curl -m "$TIMEOUT" -s "$IPSERV")

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

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

  # Check whether IP is on ignore list
  if [ $(echo "$IGNOREIP" | grep "$NEWIP") ]; then
      echo "Current IP ($NEWIP) is ignored. Aborting without DNS update." >> "$logfile"
      continue
  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) - $(stat -L -c %Y tor-ips.txt) ] -gt "604800" ]; then
      # download list, extract plain IPs, move back to file
      echo "download list"
      curl "$EXITNODES" > tor-ips.txt
      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." >> "$logfile"
      continue
    fi
  fi

  # Run update if old IP and current IP are not equal
  if [ ! "$OLDIP" == "$NEWIP" ]; then
      echo $NEWIP > "$oldip"

      curl -X POST -d "domain=${DOMAIN[$i]}&user=${USER[$i]}&pass=${PASS[$i]}&ip=$NEWIP" "$SERVER" >> "$logfile"

      echo "" >> "$logfile"
      echo "Updated IP address from $OLDIP to $NEWIP." >> "$logfile"
  fi
done