#!/bin/sh
# Custom DDNS (dynamic DNS) for the no-ip.com or asuswrt service for asuswrt-merlin
# The scripts works in a double NAT setup and single NAT setup, and will automatically detect the current configuration.
# The script does only support single wan configuration, e.g. not dual.

#Path to logfile leave empty if not used
LOGFILE=""

#Use cron to check for new ip every X minute.
#Leave empty if you're using the default from merlin (24 hours).
#Any previous, or if used, setting will be removed if left empty.
CUSTOM_UPDATE_INTERVAL=""
SILENT="false" # "true|false". true only logs ip change

#Select DDNS provider below. Select either and adjust config accordingly
DDNS_PROVIDER="noip" # "noip" or "asuswrt"

###Config for noip
USERNAME=""
PASSWORD=""
HOSTNAME=""
USERAGENT="asuswrt-merlin No-IP Updater/$VERSION"

###Config for asuswrt
MY_DDNS_HOSTNAME="[your-hostname].asuscomm.com"

#Select IP Service Provider below.
IP_PROVIDER="wget -O - --no-check-certificate --quiet https://checkip.amazonaws.com/"
#IP_PROVIDER="curl -s http://icanhazip.com/"
#IP_PROVIDER="curl -s http://ipv4.myip.dk/api/info/IPv4Address | cut -d "\"" -f2"

## CODE BELOW ####
VERSION="3.0"
# Get the the reported wan_ipaddr from nvram. (dual wan uses wan_ipaddr_x, not supported)
ASUSIP="$(nvram get wan0_ipaddr)"

LogMe(){
    if [[ -n "$LOGFILE" ]]; then
        echo "[$(date +'%Y-%m-%d %H:%M:%S')]: $1" >> "$LOGFILE"
    fi
    if [[ "$SILENT" == "true" ]]; then
        if [[ -n "$2" ]]; then
            logger "$1"
        fi
    else
        logger "$1"
    fi
}
UpdateMerlin(){
    /sbin/ddns_custom_updated "$1"
}
UpdateIp(){
    nvram set EXTERNALIP="$NEWIP"
    case "$DDNS_PROVIDER" in
        "noip" )
            # update ip
            URL="https://$USERNAME:$PASSWORD@dynupdate.no-ip.com/nic/update?hostname=$HOSTNAME&myip=$NEWIP"
            RESPONSE=$(curl -s -k --user-agent "$USERAGENT" "$URL")
            RESPONSE_A=$(echo $RESPONSE | awk '{ print $1 }')
            case "$RESPONSE_A" in
                "good")    UpdateMerlin 1; LogMe "CustomUpdateDDNS: (good) DNS hostname successfully updated to $NEWIP." "log"
                ;;
                "nochg") UpdateMerlin 1; LogMe "CustomUpdateDDNS: (nochg) IP address is current: $NEWIP; no update performed."
                ;;
                "nohost") UpdateMerlin 0; LogMe "CustomUpdateDDNS: (nohost) Hostname supplied does not exist under specified account. Revise config file."
                ;;
                "badauth") UpdateMerlin 0; LogMe "CustomUpdateDDNS: (badauth) Invalid username password combination."
                ;;
                "badagent")    UpdateMerlin 0; LogMe "CustomUpdateDDNS: (badagent) Client disabled - No-IP is no longer allowing requests from this update script."
                ;;
                "!donator")    UpdateMerlin 0; LogMe "CustomUpdateDDNS: (!donator) An update request was sent including a feature that is not available."
                ;;
                "abuse") UpdateMerlin 0; LogMe "CustomUpdateDDNS: (abuse) Username is blocked due to abuse."
                ;;
                "911") UpdateMerlin 0; LogMe "CustomUpdateDDNS: (911) A fatal error on our side such as a database outage. Retry the update in no sooner than 30 minutes."
                ;;
                "*") UpdateMerlin 0; LogMe "CustomUpdateDDNS: (error) Could not understand the response from No-IP. The DNS update server may be down."
                ;;
            esac
        ;;
        "asuswrt" )
            RESPONSE=$(nslookup $MY_DDNS_HOSTNAME ns1.asuscomm.com | tail -n1 | sed -e 's/Address 1: //')
            if [[ -n "$RESPONSE" ]]; then
                UPDATE_DDNS="ez-ipupdate -S dyndns -i eth0 -a $NEWIP -h $MY_DDNS_HOSTNAME -A 2 -s nwsrv-ns1.asus.com"
                UpdateMerlin 1
                LogMe "CustomUpdateDDNS: DNS hostname successfully updated to $NEWIP." "log"
            else
                LogMe "CustomUpdateDDNS: Something went wrong????"
            fi
        ;;
    esac
}


CronUpdate(){
    if [[ -n "$CUSTOM_UPDATE_INTERVAL" ]]; then
        if [[ -z "$(cru l | grep "CustomUpdateDDNS")" ]]; then
            /usr/sbin/cru a CustomUpdateDDNS "*/$CUSTOM_UPDATE_INTERVAL * * * * /jffs/scripts/ddns-start"
            LogMe "CustomUpdateDDNS has been added to cron (x $CUSTOM_UPDATE_INTERVAL mins)"
        fi
    else
        if [[ -n "$(cru l | grep "CustomUpdateDDNS")" ]]; then
            /usr/sbin/cru d "CustomUpdateDDNS"
            LogMe "CustomUpdateDDNS has been removed from cron"
        fi
    fi
}

LogMe "CustomUpdateDDNS: Starting custom DDNS updater v$VERSION"

if [[ -z "$ASUSIP" ]]; then
    LogMe "(error) Router has no ip or no network configuration"
    exit 1
fi

CronUpdate

LogMe "CustomUpdateDDNS: Reported asus router ip: $ASUSIP"

if [[ -n "$(echo "$ASUSIP" | grep -E '^(10\.|100\.(6[4-9]|7[0-9]|8[0-9]|9[0-9]|1[0-2][0-9])\.|172\.(1[6789]|2[0-9]|3[01])\.|192\.0\.0\.|192\.168|198\.1[89])')" ]]; then
    # check if we have a local ip. If true, then look up external ip
    LogMe "CustomUpdateDDNS: Local ip detected"
    # look up external ip
    NEWIP=$(eval $IP_PROVIDER)
    if [[ -n "$NEWIP" ]]; then
        LogMe "CustomUpdateDDNS: Found external ip: $NEWIP"
    else
        LogMe "CustomUpdateDDNS: External IP not found"
    fi
else
    NEWIP="$ASUSIP"
    LogMe "CustomUpdateDDNS: External ip detected"
fi

# compare found ip with stored ip. If nothing is stored, assume an update is needed

if [[ "$NEWIP" == "$(nvram get EXTERNALIP)" ]]; then
    # ip has not changed there's no need to hammer the ddns provider, so compare it to the previosuly found ip and save in ram
    LogMe "CustomUpdateDDNS: (nochange) External IP address is current: $NEWIP"
    LogMe "CustomUpdateDDNS: Update not needed"
    /sbin/ddns_custom_updated 1
else
    UpdateIp
fi
LogMe "CustomUpdateDDNS: DDNS update complete"
exit 0