spdyn.de update script

spdyn_update

#!/bin/bash

# spdyn.de external ip update script
# usage:
# bash spdyn_update
#   Check external ips and update spdyn host entries only if necessary.
#   Can be run any time, as it does not trigger unnecessary updates.
# bash spdyn_update force
#   Forced update of spdyn host entries. Does not care about unchanged public ips.
#   Keep in mind: Frequent unnecessary updates might get you blocked by spdyn.

# Function url encodes given string
# usage:
#   testvar="2003:45:4320:6705:4a4d:7eff:fedb:7d6c"
#   testresult=`rawurlencode "$testvar"`
#   echo "$testresult"
rawurlencode()
{
  local string="${1}"
  local strlen=${#string}
  local encoded=""
  local pos c o

  for (( pos=0 ; pos<strlen ; pos++ )); do
     c=${string:$pos:1}
     case "$c" in
        [-_.~a-zA-Z0-9] ) o="${c}" ;;
        * )               printf -v o '%%%02x' "'$c"
     esac
     encoded+="${o}"
  done
  echo "${encoded}"
}

# Function updates spdyn host entry. Depends on function rawurlencode.
# usage:
#   dns_host="somehost.spdns.de"
#   dns_token="aaa-bbb-ccc"
#   external_ip="10.10.10.10"
#   response=`update_spdyn "$dns_host" "$dns_token" "$external_ip"`
#   echo "$response"
update_spdyn()
{
  local loc_dns_host="$1"
  local loc_dns_host_urlencoded=`rawurlencode "$loc_dns_host"`
  local loc_dns_token="$2"
  local loc_ext_ip="$3"
  local loc_ext_ip_urlencoded=`rawurlencode "$loc_ext_ip"`
  local loc_spdns_response=`wget --user=$loc_dns_host --password=$loc_dns_token "https://update.spdyn.de/nic/update?hostname=$loc_dns_host_urlencoded&myip=$loc_ext_ip_urlencoded" -O "-" --quiet`
  echo $loc_spdns_response
}

### START: edit host parameters ###

# set host vars to empty string to skip specific check
ipv4_dns_host="somehostforipv4.spdns.de"
ipv4_dns_token="aaaa-bbbb-cccc"
ipv6_dns_host="somehostforipv6.spdns.de"
ipv6_dns_token="dddd-eeee-ffff"

# if IPv6 should be skipped, it would look like this
# ipv4_dns_host="somehostforipv4.spdns.de"
# ipv4_dns_token="aaaa-bbbb-cccc"
# ipv6_dns_host=""
# ipv6_dns_token=""

### END: edit host parameters ###

# define response file (derived from script file)
response_file_v4="$(readlink -f $0)_v4.response"
response_file_v6="$(readlink -f $0)_v6.response"

# get external ips
[[ ! "`/usr/bin/tty`" == "not a tty" ]] && echo -e "\nspdyn.de update: Checking external ips ..."
if [ ! -z "$ipv4_dns_host" ]; then
  external_ip_v4=`wget "http://checkip4.spdyn.de" -O "-" --quiet`
else
  [[ ! "`/usr/bin/tty`" == "not a tty" ]] && echo -e "\nSkipped IPv4 check (no IPv4 host defined)."
fi
if [ ! -z "$ipv6_dns_host" ]; then
  external_ip_v6=`wget "http://checkip6.spdyn.de" -O "-" --quiet`
else
  [[ ! "`/usr/bin/tty`" == "not a tty" ]] && echo -e "\nSkipped IPv6 check (no IPv6 host defined)."
fi

# determine operation mode
force_update="no"
if [ $# -ne 0 ]; then
  if [ $1 == "force" ]; then
    force_update="yes"
    [[ ! "`/usr/bin/tty`" == "not a tty" ]] && echo -e "\nForced spdns update requested ..."
  else
    [[ ! "`/usr/bin/tty`" == "not a tty" ]] && echo -e "\nInvalid parameter! Defaulting to standard mode ..."
  fi
fi

# report and save results
if [ -z "$external_ip_v4" ] && [ -z "$external_ip_v6" ]; then

  # no public ip was obtained

  [[ ! "`/usr/bin/tty`" == "not a tty" ]] && echo -e "\nNo internet connection detected."
  # write failed response files
  # only if checks were not skipped intentionally - otherwise remove existing response files
  if [ ! -z "$ipv4_dns_host" ]; then
    echo "OPERATION FAILED TO FETCH EXTERNAL IP V4" > $response_file_v4
  else
    rm -f "$response_file_v4"
  fi
  if [ ! -z "$ipv6_dns_host" ]; then
    echo "OPERATION FAILED TO FETCH EXTERNAL IP V6" > $response_file_v6
  else
    rm -f "$response_file_v6"
  fi

elif [ -z "$external_ip_v6" ] && [ ! -z "$external_ip_v4" ]; then

  # only ip v4 was obtained

  [[ ! "`/usr/bin/tty`" == "not a tty" ]] && echo -e "\nIPv4 connection detected."
  [[ ! "`/usr/bin/tty`" == "not a tty" ]] && echo -e "Current external ip v4: $external_ip_v4"

  # write failed response file v6
  # only if v6 check was not skipped intentionally - otherwise remove existing response file
  if [ ! -z "$ipv6_dns_host" ]; then
    echo "OPERATION FAILED TO FETCH EXTERNAL IP V6" > $response_file_v6
  else
    rm -f "$response_file_v6"
  fi

elif [ ! -z "$external_ip_v6" ] && [ -z "$external_ip_v4" ]; then

  # only ip v6 was obtained

  [[ ! "`/usr/bin/tty`" == "not a tty" ]] && echo -e "\nIPv6 connection detected."
  [[ ! "`/usr/bin/tty`" == "not a tty" ]] && echo -e "Current external ip v6: $external_ip_v6"

  # write failed response file v4
  # only if v4 check was not skipped intentionally - otherwise remove existing response file
  if [ ! -z "$ipv4_dns_host" ]; then
    echo "OPERATION FAILED TO FETCH EXTERNAL IP V4" > $response_file_v4
  else
    rm -f "$response_file_v4"
  fi

elif [ ! -z "$external_ip_v6" ] && [ ! -z "$external_ip_v4" ]; then
  [[ ! "`/usr/bin/tty`" == "not a tty" ]] && echo -e "\nIPv6 Dual Stack connection detected."
  [[ ! "`/usr/bin/tty`" == "not a tty" ]] && echo -e "Current external ip v6: $external_ip_v6"
  [[ ! "`/usr/bin/tty`" == "not a tty" ]] && echo -e "Current external ip v4: $external_ip_v4"
fi

# update ip v4 host
if [ ! -z "$external_ip_v4" ]; then

  # read ip from last response file
  if [ ! -f "$response_file_v4" ]; then
    last_ip_v4=""
    [[ ! "`/usr/bin/tty`" == "not a tty" ]] && echo -e "\nNo previous response file v4 found ..."
  else
    last_ip_v4=$(head -n 1 "$response_file_v4")
    last_ip_v4=`echo $last_ip_v4 | cut -d \  -f 2`
    [[ ! "`/usr/bin/tty`" == "not a tty" ]] && echo -e "\nPrevious response file v4 reports: $last_ip_v4"
  fi

  # check if ip has changed or forced update was requested
  if [ ! "$external_ip_v4" = "$last_ip_v4" ] || [ "$force_update" = "yes" ]; then

    # send update request
    [[ ! "`/usr/bin/tty`" == "not a tty" ]] && echo -e "Updating IPv4 spdyn host $ipv4_dns_host ..."
    response_v4=`update_spdyn "$ipv4_dns_host" "$ipv4_dns_token" "$external_ip_v4"`
    # save result into file
    echo "$response_v4" > $response_file_v4
    # display result
    [[ ! "`/usr/bin/tty`" == "not a tty" ]] && echo "spdyn response: $response_v4"   

  else
    [[ ! "`/usr/bin/tty`" == "not a tty" ]] && echo "No update required. Public ip is still correct."
  fi

fi

# update ip v6 host
if [ ! -z "$external_ip_v6" ]; then

  # read ip from last response file
  if [ ! -f "$response_file_v6" ]; then
    last_ip_v6=""
    [[ ! "`/usr/bin/tty`" == "not a tty" ]] && echo -e "\nNo previous response file v6 found ..."
  else
    last_ip_v6=$(head -n 1 "$response_file_v6")
    last_ip_v6=`echo $last_ip_v6 | cut -d \  -f 2`
    [[ ! "`/usr/bin/tty`" == "not a tty" ]] && echo -e "\nPrevious response file v6 reports: $last_ip_v6"
  fi

  # check if ip has changed or forced update was requested
  if [ ! "$external_ip_v6" = "$last_ip_v6" ] || [ "$force_update" = "yes" ]; then

    # send update request
    [[ ! "`/usr/bin/tty`" == "not a tty" ]] && echo -e "Updating IPv6 spdyn host $ipv6_dns_host ..."
    response_v6=`update_spdyn "$ipv6_dns_host" "$ipv6_dns_token" "$external_ip_v6"`
    # save result into file
    echo "$response_v6" > $response_file_v6
    # display result
    [[ ! "`/usr/bin/tty`" == "not a tty" ]] && echo "spdyn response: $response_v6"   

  else
    [[ ! "`/usr/bin/tty`" == "not a tty" ]] && echo "No update required. Public ip is still correct."
  fi

fi

[[ ! "`/usr/bin/tty`" == "not a tty" ]] && echo -e "\n"

# done
exit 0