Secure dynu.com dynamic IP update script using OAuth2 authentication

dynu.sh

#!/bin/bash

# dynu.com dynamic IP update script
# variables can be added in file, in sourced file or as command line arguments

set -e

# https://www.dynu.com/en-US/ControlPanel/APICredentials
# oauth2='{Client-Id}:{Secret}'
oauth2='EOJ2S-Z6OoN_le_KS1d75wsZ6y0SFdVsY9183IvxFyZp:EClusMEUk8e9ihI7ZdVLF5cZ6y0SFdVsY9183IvxFyZp'
ipv4Address='1.2.3.4'
domainid='100119100'        # Use --get-list to obtain domain IDs
name='rover.mydomain.com'
group='rover'
ttl='60'

# Source variables file if it exists,
# so that they can be left out of git repository
if [ -e ./dynu.env ]; then source ./dynu.env; fi

# Check for dependencies
deps=( curl jq )
unset bail
for i in "${deps[@]}"; do command -v "$i" >/dev/null 2>&1 || { bail="$?"; echo "$i" is not available; }; done
if [ "$bail" ]; then exit "$bail"; fi

help() {
    cat << EOF
  Options:
   --help
   --get-list (of domains)
   --check
   --current (updates to current local address)
   -o OAuth2
   -4 IPv4
   -i DomainID
   -n Domain
   -g Group
   -t TTL
EOF
}

exit_error() {
    help
    exit 1
}

getoptions () {
    opts=()
    while getopts ':o:4:i:n:g:t:' arg; do
        case "${arg}" in
            o)  oauth2=${OPTARG};;
            4)  ipv4Address=${OPTARG}
                re_isaipaddress='^[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}$'
                if ! [[ ${ipv4Address} =~ ${re_isaipaddress} ]]; then
                    echo "Error: ${ipv4Address} is not a valid IPv4 address"
                    exit 1
                fi;;
            i)  domainid=${OPTARG};;
            n)  name=${OPTARG};;
            g)  group=${OPTARG};;
            t)  ttl=${OPTARG};;
            :)  echo "Error: -${OPTARG} requires an argument"
                exit_error;;
            *)  exit_error;;
        esac
    done
}

gettoken () {
    if [ -z ${oauth2} ]; then echo "Error: No OAuth2 key supplied" && exit 1; fi
    token=$(curl -sX GET https://api.dynu.com/v2/oauth2/token \
            -H "accept: application/json" \
            -u ${oauth2} | jq -r '.access_token')
}

getdomainlist () {
    curl -sX GET "https://api.dynu.com/v2/dns" \
            -H "accept: application/json" \
            -H "Authorization: Bearer ${token}" | jq -r
}

getaddress() {
    ipv4=$(curl -sX GET "https://api.dynu.com/v2/dns/${domainid}" \
            -H "accept: application/json" \
            -H "Authorization: Bearer ${token}" | jq -r '.ipv4Address')
    echo "Current record address: ${ipv4}"
}

postaddress () {
    curl -sX POST "https://api.dynu.com/v2/dns/${domainid}" \
            -H "accept: application/json" \
            -H "Authorization: Bearer ${token}" \
            -H "Content-Type: application/json" \
            -d "{
                \"name\":\"${name}\",
                \"group\":\"${group}\",
                \"ipv4Address\":\"${ipv4Address}\",
                \"ttl\":${ttl},
                \"ipv4\":true,
                \"ipv6\":false,
                \"ipv4WildcardAlias\":false,
                \"ipv6WildcardAlias\":false,
                \"allowZoneTransfer\":false,
                \"dnssec\":false
            }" | jq -r
}

if [[ "$*" =~ "--help" ]]; then
    help
elif [[ "$*" =~ "--get-list" ]]; then
    gettoken && getdomainlist
elif [[ "$*" =~ "--check" ]]; then
    gettoken && getaddress
elif [[ "$*" =~ "--current" ]]; then
    getoptions && ipv4Address="$(curl -s https://ipv4.icanhazip.com)" && gettoken && postaddress && getaddress
else
    getoptions "$@" && gettoken && postaddress && getaddress
fi

exit 0