DNS-01 challenge hook script of uacme for Cloudflare

uacme-cloudflare-hook.sh

#!/bin/sh
# Copyright (C) 2020 Michel Stam <michel@reverze.net>
# Copyright (C) 2021 Hung-I Wang <whygowe@gmail.com>
# 
# The script is adatped from:
# https://github.com/ndilieto/uacme/blob/5edec0eea1bcf6f454ec1787297c2408c2f2e97a/nsupdate.sh
# 
# Licensed under the the GNU General Public License <http://www.gnu.org/licenses/>.

# The script is meant to be used as a hook script of uacme to update TXT records for acme challenges. 
# Instead of relying on IETF RFC2136, it talks to cfapi-ddns-worker.js which is a wrapper around Cloudflare API:
# https://gist.github.com/Gowee/8c3e65b80767b915e0199908e5d7a916

# API Config
API_ENDPOINT="https://foo.bar.workers.dev/"
API_TOKEN="TOKEN_FOR_THE_DOMAIN_SPECIFIED_IN_THE_WORKER_SCRIPT"

# Arguments
METHOD=$1
TYPE=$2
IDENT=$3
TOKEN=$4
AUTH=$5

ns_ispresent()
{
    local fqhn="$1"
    local expect="$2"
    local resp

    resp=$(curl -fsSH "accept: application/dns-json" "https://cloudflare-dns.com/dns-query?name=${fqhn}&type=TXT")
    if echo "$resp" | grep -q "$expect"; then
        return 0
    else
        return 1
    fi
}

ns_doupdate()
{
    local fqhn="$1"
    local challenge="$2"

    if [ -n "${challenge}" ]; then
        curl -fsS "${API_ENDPOINT}upsert/${API_TOKEN}/${fqhn}/TXT/${challenge}"
        # TODO: --fail-with-body
    else
        curl -fsS "${API_ENDPOINT}delete/${API_TOKEN}/${fqhn}/TXT/${challenge}"
        # TODO: --fail-with-body
    fi
    return $?
}

ns_update()
{
    local fqhn="$1"
    local challenge="$2"
    local count=0
    local res

    res=1
    while [ $res -ne 0 ]; do
        if [ $count -eq 0 ]; then
            ns_doupdate "$fqhn" "$challenge"
            res=$?
            [ $res -eq 0 ] || break
        else
            sleep 1
        fi

        count=$(((count + 1) % 5))
        ns_ispresent "$fqhn" "$challenge"
        res=$?
    done

    return $res
}

ARGS=5
E_BADARGS=85

if [ $# -ne "$ARGS" ]; then
    echo "Usage: $(basename "$0") method type ident token auth" 1>&2
    exit $E_BADARGS
fi

case "$METHOD" in
    "begin")
        case "$TYPE" in
            dns-01)
                ns_update "_acme-challenge.$IDENT" "$AUTH"
                exit $?
                ;;
            *)
                exit 1
                ;;
        esac
        ;;

    "done"|"failed")
        case "$TYPE" in
            dns-01)
                ns_update "_acme-challenge.$IDENT"
                exit $?
                ;;
            *)
                exit 1
                ;;
        esac
        ;;

    *)
        echo "$0: invalid method" 1>&2
        exit 1
esac