Dynamic DNS using the CloudFlare API

addr.json

{}

addr.php

<?php
$API_KEY = "xxxxxxxxxxxxxxxx";
$EMAIL   = "user@example.com";

$BASE_URL  = "https://www.cloudflare.com/api_json.html";
$BASE_URL .= "?tkn=" . $API_KEY . "&email=" . $EMAIL;

function get_json(){
	$raw = file_get_contents('addr.json');
	if($raw === FALSE || strlen($raw) == 0)
		$raw = "{}";
	return json_decode($raw, TRUE);
}

function get_machines(){
	$raw = file_get_contents('machines.json');
	if($raw === FALSE || strlen($raw) == 0)
		$raw = "{}";
	return json_decode($raw, TRUE);
}

if(isset($_GET['set'])){
	$name = $_GET['set'];
	$machines = get_machines();

	if(isset($machines[$name])){
		$machine = $machines[$name];
		if(strlen($machine['hash']) != 0 && (!isset($_GET['key']) || $machine['hash'] != sha1($_GET['key'])))
			exit("Unauthorized!");

		$ip = $_SERVER['REMOTE_ADDR'];
		$json = get_json();

		// Check if the address has changed
		if($json[$name] != $ip){
			$json[$name] = $ip;
			file_put_contents('addr.json', json_encode($json));

			foreach($machine['domains'] as $domain){
				// Get a list of subdomains
				$res = file_get_contents($BASE_URL . "&z=" . $domain['name'] . "&a=rec_load_all");
				$res = json_decode($res, true)['response']['recs']['objs'];
				$ids = array();
				foreach($res as $search_domain)
					$ids[$search_domain['display_name']] = $search_domain['rec_id'];

				// Update the entry
				$url = $BASE_URL . "&z=" . $domain['name'] . "&a=rec_edit&type=A&service_mode=0&ttl=120";
				if(isset($ids[$domain['sub']])){
					$url .= "&name=" . $domain['sub'] . "&id=" . $ids[$domain['sub']] . "&content=" . $ip;
					$res = json_decode(file_get_contents($url), true);
					if(isset($res['result']) && $res['result'] == "success")
						echo "+";
					else
						echo "-";
				}else
					echo "-";
			}

			echo " ";
			$hosts = "";
			foreach($json as $name => $ip)
				$hosts .= $ip . "\t" . $name . "\n";
			file_put_contents("/etc/hosts.d/dynamic", $hosts);
		}else
			echo "0 ";
	}else
		exit("No such domain.");
	exit($ip);
}

// Look up an entry
if(isset($_GET['get'])){
	$search = strtolower($_GET['get']);
	$json = get_json();
	if(isset($json[$search]))
		exit($json[$search]);
	else
		exit("0.0.0.0");
}

http_response_code(400);

machines.json

{
	"box1": {
		"hash": "",
		"domains": [
			{
				"sub": "box1",
				"name": "example.com"
			}
		]
	}, "box2": {
		"hash": "7bb19c41ef70714b4f72004618a0f3b37c1a6ca6",
		"domains": [
			{
				"sub": "box2",
				"name": "example.com"
			}, {
				"sub": "box2.dyndns",
				"name": "example.net"
			}
		]
	}, "box3": {
		"hash": "",
		"domains": [
			{
				"sub": "box3",
				"name": "example.com"
			}, {
				"sub": "box3.dyndns",
				"name": "example.net"
			}
		]
	}
}