ddns.sh

#!/bin/bash
#===============================================================================
#
#       FILE:  ddns.sh
#
#       USAGE:  ./ddns.sh
#
#       DESCRIPTION: Enables the use of a DreamHost hosted FQDN with dynamic
#                    IP addresses.
#       REQUIRES: API Access and key - https://panel.dreamhost.com/?tree=home.api
#                 Details about the API at http://wiki.dreamhost.com/API
#       AUTHOR:   Eri Ramos Bastos - bastos.eri()gmail.com
#       VERSION:  Wed Oct  6 21:52:09 ADT 2010
#
#
#===============================================================================


# Configuration
hostname="your.fqdn.hostname"
export key="YOURAPIKEY"


#-------------------------------------------------------------------------------
#   Don't change from here to bottom unless you know what you're doing
#-------------------------------------------------------------------------------
fetch_cmd="curl -s"
current_ip_url="http://icanhazip.com"


function die () { echo "$progname: $1"; exit ${2:-1}  ; }

function Verbose ()
{
    # May be useful for troubleshooting
    [ $VERBOSE ] && echo "[MESSAGE] $1"
    return 0
}    # ----------  end of function Verbose  ----------


function RunCmd ()
{
    local cmd="$1"
    local uuid=$(uuidgen)
    local link="https://api.dreamhost.com/?key=$key&unique_id=$uuid&cmd=$cmd"
    local api_response=$($fetch_cmd "$link")
    if ! (echo $api_response | grep -q 'success'); then
        return 1
    fi
    echo "$api_response"
}    # ----------  end of function RunCmd  ----------



#-------------------------------------------------------------------------------
# Runs from here
#-------------------------------------------------------------------------------


# Fetches current DNS entries
cmd=dns-list_records
dreamhost_response=$(RunCmd "$cmd")
[ $? -ne 0 ] && die "Unable to get response from DreamHost"
current_dns_ip=$(echo "$dreamhost_response"|grep "$hostname" |cut -f5)

# Fetches IP address in use
Verbose "Fetching current IP address"
current_ip_response=$($fetch_cmd "$current_ip_url")
[ -z "$current_ip_response" ] && die "Unable to get IP address from $current_ip_url"

# Do magic
Verbose "Comparing IPs"
if [ "$current_dns_ip" = "$current_ip_response" ]
then
    Verbose "IP matches. Nothing else to do..."
else
    Verbose "IP needs update"

    #Remove current DNS entry
    Verbose "Removing current DNS entry $current_dns_ip"
    cmd="dns-remove_record&record=$hostname&type=A&value=$current_dns_ip"
    dreamhost_response=$(RunCmd "$cmd")
    [ $? -ne 0 ] && die "Unable to get response from DreamHost"

    #Creates new DNS entry
    Verbose "Adding new entry $current_ip_response"
    now=$(date +%Y%m%d_%H%M)
    cmd="dns-add_record&record=$hostname&type=A&value=$current_ip_response&comment=$now"
    dreamhost_response=$(RunCmd "$cmd")
    [ $? -ne 0 ] && die "Unable to get response from DreamHost"
fi

exit 0