update-record

#!/bin/bash
exec 3>&1

# get int value for given log level debug=>10, info=>20, error=>40
get_log_level_value(){
    level=20
    case $1 in
        debug)
        level=10
    ;;
        info)
        level=20
    ;;
        error)
        level=40
    ;;
    esac
    echo $level
}

# functions used to display logs
log(){
    log_level_value=$(get_log_level_value $1)
    if [ "$log_level_value" -ge "$current_level_value" ]
    then
    echo "{\"date\": \"$(date +"%Y-%m-%dT%H:%M:%SZ")\", \"level\": \"$1\", \"message\": \"$2\"}" 1>&3
    fi
}
debug(){ log debug "$1"; }
info(){ log info "$1"; }
error(){ log error "$1"; }

valid_ipv4() {
    local ip="$1"
    [[ "${ip}" =~ ^([0-9]{1,3}\.){3}[0-9]{1,3}$ ]] || { return 1; }
    for i in ${ip//./ }; do
        [[ "${#i}" -gt 1 && "${i:0:1}" == 0 ]] && { return 1; }
        [[ "${i}" -gt 255 ]] && { return 1; }
    done
    return 0
}

# validate inputs and set defaults

[[ -z "$HOSTNAME" ]] && echo You need to set environment variable HOSTNAME && exit
[[ -z "$IDENTIFIER" ]] && echo You need to set environment variable IDENTIFIER && exit
[[ -z "$PASSWORD" ]] && echo You need to set environment variable PASSWORD && exit
[[ -z "$LOG_LEVEL" ]] && LOG_LEVEL=debug

# set current log level, all logs with a lower level are filtered
current_level_value=$(get_log_level_value "$LOG_LEVEL")

# retrieve last known address and current public address
OLD_IP_ADDRESS=$(dig +short $(echo "$HOSTNAME" | tr ";" "\n" | head -1))
PUBLIC_IP_ADDRESS=$(dig +short myip.opendns.com @resolver4.opendns.com)

if valid_ipv4 "${PUBLIC_IP_ADDRESS}" && valid_ipv4 "${OLD_IP_ADDRESS}" && [[ "${PUBLIC_IP_ADDRESS}" ]]; then
    if [[ "${OLD_IP_ADDRESS}" != "${PUBLIC_IP_ADDRESS}" ]]; then
        info "IP address changed from '${OLD_IP_ADDRESS}' to '${PUBLIC_IP_ADDRESS}'"
        for host in $(echo "$HOSTNAME" | tr ";" "\n");
        do
        # update DynHost record using OVH API
        ovh_response=$(curl -sS "http://www.ovh.com/nic/update?system=dyndns&hostname=${host}&myip=${PUBLIC_IP_ADDRESS}" \
            -H "Authorization: Basic $(echo -n "$IDENTIFIER":"$PASSWORD" | base64)")
        debug "OVH response: ${ovh_response}"
        done
    else
        debug "No changes detected"
    fi
fi