#!/bin/sh
# /usr/lib/dynamic_dns/dynamic_dns_updater.sh
#
# Written by Eric Paul Bishop, Janary 2008
# Distributed under the terms of the GNU General Public License (GPL) version 2.0
#
# This script is (loosely) based on the one posted by exobyte in the forums here:
# http://forum.openwrt.org/viewtopic.php?id=14040
#

. /usr/lib/ddns/dynamic_dns_functions.sh


service_id=$1
if [ -z "$service_id" ]
then
    echo "ERRROR: You must specify a service id (the section name in the /etc/config/ddns file) to initialize dynamic DNS."
    return 1
fi

#default mode is verbose_mode, but easily turned off with second parameter
verbose_mode="1"
if [ -n "$2" ]
then
    verbose_mode="$2"
fi

###############################################################
# Leave this comment here, to clearly document variable names
# that are expected/possible
#
# Now use load_all_config_options to load config
# options, which is a much more flexible solution.
#
#
#config_load "ddns"
#
#config_get enabled $service_id enabled
#config_get service_name $service_id service_name
#config_get update_url $service_id update_url
#
#
#config_get username $service_id username
#config_get password $service_id password
#config_get domain $service_id domain
#
#
#config_get use_https $service_id use_https
#config_get cacert $service_id cacert
#
#config_get ip_source $service_id ip_source
#config_get ip_interface $service_id ip_interface
#config_get ip_network $service_id ip_network
#config_get ip_url $service_id ip_url
#
#config_get force_interval $service_id force_interval
#config_get force_unit $service_id force_unit
#
#config_get check_interval $service_id check_interval
#config_get check_unit $service_id check_unit
#########################################################
load_all_config_options "ddns" "$service_id"


#some defaults
if [ -z "$check_interval" ]
then
    check_interval=600
fi

if [ -z "$check_unit" ]
then
    check_unit="seconds"
fi


if [ -z "$force_interval" ]
then
    force_interval=72
fi

if [ -z "$force_unit" ]
then
    force_unit="hours"
fi

if [ -z "$use_https" ]
then
    use_https=0
fi



#some constants

if [ "x$use_https" = "x1" ]
then
    retrieve_prog="/usr/bin/curl "
    if [ -f "$cacert" ]
    then
        retrieve_prog="${retrieve_prog}--cacert $cacert "
    elif [ -d "$cacert" ]
    then
        retrieve_prog="${retrieve_prog}--capath $cacert "
    fi
else
    retrieve_prog="/usr/bin/wget -O - ";
fi

service_file="/usr/lib/ddns/services"

ip_regex="[0-9]\{1,3\}\.[0-9]\{1,3\}\.[0-9]\{1,3\}\.[0-9]\{1,3\}"

NEWLINE_IFS='
'


#determine what update url we're using if the service_name is supplied
if [ -n "$service_name" ]
then
    #remove any lines not containing data, and then make sure fields are enclosed in double quotes
    quoted_services=$(cat $service_file |  grep "^[\t ]*[^#]" |  awk ' gsub("\x27", "\"") { if ($1~/^[^\"]*$/) $1="\""$1"\"" }; { if ( $NF~/^[^\"]*$/) $NF="\""$NF"\""  }; { print $0 }' )


    #echo "quoted_services = $quoted_services"
    OLD_IFS=$IFS
    IFS=$NEWLINE_IFS
    for service_line in $quoted_services
    do
        #grep out proper parts of data and use echo to remove quotes
        next_name=$(echo $service_line | grep -o "^[\t ]*\"[^\"]*\"" | xargs -r -n1 echo)
        next_url=$(echo $service_line | grep -o "\"[^\"]*\"[\t ]*$" | xargs -r -n1 echo)

        if [ "$next_name" = "$service_name" ]
        then
            update_url=$next_url
        fi
    done
    IFS=$OLD_IFS
fi

if [ "x$use_https" = x1 ]
then
    update_url=$(echo $update_url | sed -e 's/^http:/https:/')
fi


verbose_echo "update_url=$update_url"



#if this service isn't enabled then quit
if [ "$enabled" != "1" ] 
then
    return 0
fi





#compute update interval in seconds
case "$force_unit" in
    "days" )
        force_interval_seconds=$(($force_interval*60*60*24))
        ;;
    "hours" )
        force_interval_seconds=$(($force_interval*60*60))
        ;;
    "minutes" )
        force_interval_seconds=$(($force_interval*60))
        ;;
    "seconds" )
        force_interval_seconds=$force_interval
        ;;
    * )
        #default is hours
        force_interval_seconds=$(($force_interval*60*60))
        ;;
esac



#compute check interval in seconds
case "$check_unit" in
    "days" )
        check_interval_seconds=$(($check_interval*60*60*24))
        ;;
    "hours" )
        check_interval_seconds=$(($check_interval*60*60))
        ;;
    "minutes" )
        check_interval_seconds=$(($check_interval*60))
        ;;
    "seconds" )
        check_interval_seconds=$check_interval
        ;;
    * )
        #default is seconds
        check_interval_seconds=$check_interval
        ;;
esac



verbose_echo "force seconds = $force_interval_seconds"
verbose_echo "check seconds = $check_interval_seconds"

#kill old process if it exists & set new pid file
if [ -d /var/run/dynamic_dns ]
then
    #if process is already running, stop it
    if [ -e "/var/run/dynamic_dns/$service_id.pid" ]
    then
        old_pid=$(cat /var/run/dynamic_dns/$service_id.pid)
        test_match=$(ps | grep "^[\t ]*$old_pid")
        verbose_echo "old process id (if it exists) = \"$test_match\""
        if [ -n  "$test_match" ]
        then
            kill $old_pid
        fi
    fi

else
    #make dir since it doesn't exist
    mkdir /var/run/dynamic_dns
fi
echo $$ > /var/run/dynamic_dns/$service_id.pid




#determine when the last update was
current_time=$(monotonic_time)
last_update=$(( $current_time - (2*$force_interval_seconds) ))
if [ -e "/var/run/dynamic_dns/$service_id.update" ]
then
    last_update=$(cat /var/run/dynamic_dns/$service_id.update)
fi
time_since_update=$(($current_time - $last_update))


human_time_since_update=$(( $time_since_update / ( 60 * 60 ) ))
verbose_echo "time_since_update = $human_time_since_update hours"




registered_ip=$(echo $(nslookup "$domain" 2>/dev/null) |  grep -o "Name:.*" | grep -o "$ip_regex")


#do update and then loop endlessly, checking ip every check_interval and forcing an updating once every force_interval

while [ true ]
do
    current_ip=$(get_current_ip)


    current_time=$(monotonic_time)
    time_since_update=$(($current_time - $last_update))


    verbose_echo "Running IP check..."
    verbose_echo "current system ip = $current_ip"
    verbose_echo "registered domain ip = $registered_ip"


    if [ "$current_ip" != "$registered_ip" ]  || [ $force_interval_seconds -lt $time_since_update ]
    then
        verbose_echo "update necessary, performing update ..."

        #do replacement
        final_url=$update_url
        for option_var in $ALL_OPTION_VARIABLES
        do
            if [ "$option_var" != "update_url" ]
            then
                replace_name=$(echo "\[$option_var\]" | tr 'a-z' 'A-Z')
                replace_value=$(eval echo "\$$option_var")
                replace_value=$(echo $replace_value | sed -f /usr/lib/ddns/url_escape.sed)
                final_url=$(echo $final_url | sed s^"$replace_name"^"$replace_value"^g )
            fi
        done
        final_url=$(echo $final_url | sed s/"\[HTTPAUTH\]"/"$username${password:+:$password}"/g )
        final_url=$(echo $final_url | sed s/"\[IP\]"/"$current_ip"/g )


        verbose_echo "updating with url=\"$final_url\""

        #here we actually connect, and perform the update
        update_output=$( $retrieve_prog "$final_url" )

        verbose_echo "Update Output:"
        verbose_echo "$update_output"
        verbose_echo ""

        #save the time of the update
        current_time=$(monotonic_time)
        last_update=$current_time
        time_since_update='0'
        registered_ip=$current_ip

        human_time=$(date)
        verbose_echo "update complete, time is: $human_time"

        echo "$last_update" > "/var/run/dynamic_dns/$service_id.update"
    else
        human_time=$(date)
        human_time_since_update=$(( $time_since_update / ( 60 * 60 ) ))
        verbose_echo "update unnecessary"
        verbose_echo "time since last update = $human_time_since_update hours"
        verbose_echo "the time is now $human_time"
    fi

    #sleep for 10 minutes, then re-check ip && time since last update
    sleep $check_interval_seconds
done

#should never get here since we're a daemon, but I'll throw it in anyway
return 0