dynamicdns.bash

#!/bin/bash

# This script updates a DNS A record hosted by Dreamhost to your current IP
# address via the Dreamhost API.
#
# =============================================================================
#
# Copyright (c) 2013, Paul Clement
# All rights reserved.
#
# Additional changes and updates as noted via https://github.com/jgabello/dreamhost-dynamic-dns Copyright (c) 2014, Contributing Author
# See LICENSE for more details.

CONFIG="$HOME/.config/dynamicdns"

function usage {
  echo 'usage:  ' `basename $0` '[-Sdv][-k API Key] [-r Record] [-i New IP Address] [-L Logging (true/false)]'
}

function createConfigurationFile {

  if [ ! -d $HOME/.config ]; then
    echo "$HOME/.config/ does not exist, creating directory."
    mkdir $HOME/.config
  fi

  umask 077
echo -n '# Dreamhost Dynamic DNS Updater Configuration file.  This file
# allows you to set the basic parameters to update Dreamhost
# dynamic dns without command line options.
# There are three basic parameters:
#
# KEY
# This parameter is your Dreamhost API Key.  The parameter should
# be specified as a STRING.  Your API KEY must be given the the
# following permissions in the Dreamhost webpanel:
# - dns-list_records
# - dns-remove_record
# - dns-add_record

KEY=

# RECORD
# This parameter specifies which DNS A record you wish to update
# with this script.

RECORD=

# LOGGING
# Logging enables script output to the system log in OSX or Linux
# This parameter accepts a BOOLEAN.  By default this parameter is
# set to "true".
#

LOGGING=true
' > "$CONFIG"

return 0
}

function logStatus {
  local LEVEL=$1
  local MESSAGE=$2
  if [ "$LOGGING" = "true" ]; then
    if [ $LEVEL = "error" ]; then
      logger -p syslog.err -t `basename $0` "$MESSAGE"
    elif [ $LEVEL = "notice" ]; then
      logger -p syslog.notice -t `basename $0` "$MESSAGE"
    elif [ $LEVEL = "alert" ]; then
      logger -p syslog.alert -t `basename $0` "$MESSAGE"
    fi
  fi
  if [ $VERBOSE = "true" ]; then
    echo `basename $0` "$MESSAGE"
  fi
  return 0
}

function saveConfiguration {
  if [ -n "$1" ]; then
    sed -i -e "s/^KEY=.*$/KEY=$1/" "$CONFIG"
    if [ $VERBOSE = "true" ]; then
      echo "Saving KEY to configuration file"
    fi
  fi

  if [ -n "$2" ]; then
    sed -i -e "s/^RECORD=.*$/RECORD=$2/" "$CONFIG"
    if [ $VERBOSE = "true" ]; then
      echo "Saving RECORD to configuration file"
    fi

  fi
  if [ -n "$3" ]; then
    sed -i -e "s/^LOGGING=.*$/LOGGING=$3/" "$CONFIG"
    if [ $VERBOSE = "true" ]; then
      echo "Saving LOGGING to configuration file"
    fi
  fi
  return 0
}

VERBOSE="false"
LISTONLY="false"
#Get Command Line Options
while getopts "L:i:k:r:Sdvl" OPTS
do
  case $OPTS in
    L)
    if ! ([ "$OPTARG" == "true" ] || [ "$OPTARG" == "false" ])  ; then
      echo `basename $0` " Invalid Parameters -- L"
      logStatus "error" "Invalid Parameters -- L"
      usage
      exit 1
    fi

    OPTLOGGING=$OPTARG
    ;;

    v)
    VERBOSE="true"
    ;;

    k)
    OPTKEY=$OPTARG
    ;;

    l)
    LISTONLY="true"
    ;;

    r)
    OPTRECORD=$OPTARG
    ;;

    i)
    if [[ $OPTARG =~ ^[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}$ ]];
    then
      OPTIP=$OPTARG
    else
      echo `basename $0` " Invalid Parameters -- i"
      logStatus "error" "Invalid Parameters -- i"
      usage
      exit 1
    fi
    ;;

    S)
    SAVE="true"
    ;;

    d)
    SAVEONLY="true"
    ;;

    ?)
    usage
    exit 1
    ;;
  esac
done

#Check for Configuration File

if [ ! -f ~/.config/dynamicdns ]; then
  logStatus "notice" "Configuration File Not Found. Creating new configuration file."
  createConfigurationFile
fi

# Load Configuration File

source ~/.config/dynamicdns

# check for dependencies, if wget not available, test for curl, set variable to be used to test this later
if command -v wget >/dev/null 2>&1; then
  POSTPROCESS="wget"

elif command -v curl >/dev/null 2>&1; then
  POSTPROCESS="curl"

else
  echo `basename $0` "ERROR: Missing dependency -- wget or curl"
  logStatus "error" "Missing Dependency -- wget or curl"
  exit 1
fi
if [ $VERBOSE = "true" ]; then
  echo "Post process set to: $POSTPROCESS"
fi

if [ ! -n "$OPTKEY" ]; then
  if [ ! -n "$KEY" ]; then
    echo `basename $0` ": missing parameter -- KEY"
    logStatus "error" "Missing Parameter -- KEY"
    usage
    exit 1
  fi
else KEY="$OPTKEY"
fi

if [ ! -n "$OPTRECORD" ]; then
  if [ ! -n "$RECORD" ]; then
    echo `basename $0` ": missing parameter -- RECORD"
    logStatus "error" "Missing Parameter -- RECORD"
    usage
   exit 1
  fi
else RECORD="$OPTRECORD"
fi

if [ $VERBOSE = "true" ]; then
  echo "Using API Key: $KEY"
  echo "Updating RECORD: $RECORD"
fi

if [ "$SAVE" == "true" ] || [ "$SAVEONLY" == "true" ]; then
  saveConfiguration "$OPTKEY" "$OPTRECORD" "$OPTLOGGING"
fi

if [ "$SAVEONLY" == "true" ]; then
  if [ $VERBOSE = "true" ]; then
    echo "Saving Configuration File and Exiting"
  fi
  exit 0
fi

if [ ! -n "$OPTIP" ]; then
  if [ $VERBOSE = "true" ]; then
    echo "No IP Address provided, obtaining public IP"
  fi
  # Try multiple resolvers (in case they don't respond)
  RESOLVERS='
    o-o.myaddr.l.google.com:ns1.google.com:TXT
    myip.opendns.com:resolver1.opendns.com:A
    whoami.akamai.net:ns1-1.akamaitech.net:A
    o-o.myaddr.l.google.com:ns2.google.com:TXT
    myip.opendns.com:resolver2.opendns.com:A
    o-o.myaddr.l.google.com:ns3.google.com:TXT
    myip.opendns.com:resolver3.opendns.com:A
    o-o.myaddr.l.google.com:ns4.google.com:TXT
    myip.opendns.com:resolver4.opendns.com:A
  '
  for ENTRY in $RESOLVERS; do
    IFS=':' read -r OWN_HOSTNAME RESOLVER DNS_RECORD <<< "$ENTRY"
    IP=$(dig -4 +short $DNS_RECORD $OWN_HOSTNAME @$RESOLVER)
    if [ $? -eq 0 ]; then
      break
    fi
    logStatus "notice" "Failed to obtain current IP address using $RESOLVER"
  done
  IP=${IP//\"/}
  if [[ ! $IP =~ ^([0-9]{1,3}\.){3}[0-9]{1,3}$ ]]; then
    logStatus "error" "Failed to obtain current IP address"
    exit 3
  fi
  if [ $VERBOSE = "true" ]; then
    echo "Found current public IP: $IP"
  fi
else IP="$OPTIP"
fi


function submitApiRequest {
  local KEY=$1
  local CMD=$2
  local ARGS=$3

  # Send request
  if [ $POSTPROCESS = "wget" ]; then
      local RESPONSE=$(wget -O- -q https://api.dreamhost.com/ \
        --post-data key=$KEY\&unique_id=$(uuidgen)\&cmd=$CMD\&$ARGS )
  elif [ $POSTPROCESS = "curl" ]; then
    local RESPONSE=$(curl -s --data "key=$KEY&unique_id=$(uuidgen)&cmd=$CMD&$ARGS" https://api.dreamhost.com/)
  else
    logStatus "error" "Missing Dependency -- wget or curl"
    exit 1
  fi
  local RC=$?

  # Output response
  printf "$RESPONSE"

  if [ $RC -ne 0 ]; then
    logStatus "notice" "API Request Failed"
    return $?
  fi

  # If "success" is not in the response, then the request failed
  printf "$RESPONSE" | grep "^success$" > /dev/null
}

function listRecord {
  local KEY=$1
  local RECORD=$2

  # See whether there is already a record for this domain

  local LIST_RESP=`submitApiRequest $KEY dns-list_records type=A\&editable=1`

  if [ $? -ne 0 ]; then
    logStatus "notice" "Error Listing Records: $LIST_RESP"
    return 1
  fi

  local CLEANED_RECORD=`echo $RECORD | sed "s/[*]/[*]/g ; s/[.]/[.]/g "` 
  local CURRENT_RECORD=`printf "$LIST_RESP" | grep "\s$CLEANED_RECORD\sA\n"`

  if [ $? -ne 0 ]; then
    logStatus "error" "Record not found"
    return 0
  fi

  local OLD_VALUE=`printf "$CURRENT_RECORD" | awk '{print $5 }'`

  echo "Found current record: $OLD_VALUE"

}

function deleteRecord {
  local KEY=$1
  local RECORD=$2
  local NEW_VALUE=$3

  # See whether there is already a record for this domain

  local LIST_RESP=`submitApiRequest $KEY dns-list_records type=A\&editable=1`
  if [ $? -ne 0 ]; then
    logStatus "notice" "Error Listing Records: $LIST_RESP"
    return 1
  fi

  local CLEANED_RECORD=`echo $RECORD | sed "s/[*]/[*]/g ; s/[.]/[.]/g "` 
  local CURRENT_RECORD=`echo $LIST_RESP | egrep -o "\s$CLEANED_RECORD\s+A\s+[0-9]{1,3}.[0-9]{1,3}.[0-9]{1,3}.[0-9]{1,3}"`
  if [ $VERBOSE = "true" ]; then
    echo "Current Record: $CURRENT_RECORD"
  fi
  if [ $? -ne 0 ]; then
    logStatus "error" "Record not found"
    return 0
  fi

  local OLD_VALUE=`echo $CURRENT_RECORD | awk '{print $3 }'`

  if [ "$OLD_VALUE" == "$NEW_VALUE" ]; then
    # The current record is up to date, so we don't need to do anything
    return 255
  fi

  # We need to remove the existing record to continue

  submitApiRequest $KEY \
                   dns-remove_record \
                   record=$RECORD\&type=A\&value=$OLD_VALUE

  if [ $? -ne 0 ]; then
    logStatus "error" "Unable to Remove Existing Record"
    return 2
  else
    return 0
  fi
}

function addRecord {
  local KEY=$1
  local RECORD=$2
  local IP=$3

  submitApiRequest $KEY \
                   dns-add_record \
                   record=$RECORD\&type=A\&value=$IP
}

# -------------------------------
# Main execution

if [ "$LISTONLY" == "true" ]; then

  # We're just getting the current record
  
  listRecord $KEY $RECORD

  if [ $? -ne 0 ]; then
    # Something is wrong
    logStatus "error" "ERROR $?"
    exit $?
  fi

else

  # We're updating the record

  # Delete any existing record for this domain
  deleteRecord $KEY $RECORD $IP

  if [ $? -eq 255 ]; then
    logStatus "notice" "Record up to date"
    exit 0
  fi

  if [ $? -ne 0 ]; then
    # Something is wrong
    logStatus "error" "ERROR $?"
    exit $?
  fi

  # Add the new record

  addRecord $KEY $RECORD $IP
  if [ $? -ne 0 ]; then
    logStatus "alert" "Failed to add new record"
    # In this case, if we have deleted the record, then you will no longer
    # have a DNS record for this domain.
    exit 4
  else
    logStatus "notice" "Record updated succesfully"
  fi

fi

# Woohoo! We're exiting cleanly
exit 0