Parse Zone File to generate a list of all domains defined within it.

zonefile.js

// Polyfill
// String.prototype.includes
String.prototype.includes = function (string, index) {
	if (typeof string === 'object' && string instanceof RegExp) throw new TypeError("First argument to String.prototype.includes must not be a regular expression");
	return this.indexOf(string, index) !== -1;
};

// Array.prototype.includes
Array.prototype.includes = function includes(searchElement /*, fromIndex*/ ) {'use strict';
	var O = Object(this);
	var len = parseInt(O.length) || 0;
	if (len === 0) {
		return false;
	}
	var n = parseInt(arguments[1]) || 0;
	var k;
	if (n >= 0) {
		k = n;
	} else {
		k = len + n;
		if (k < 0) {k = 0;}
	}
	var currentElement;
	while (k < len) {
		currentElement = O[k];
		if (searchElement === currentElement ||
		   (searchElement !== searchElement && currentElement !== currentElement)) {
			return true;
		}
		k++;
	}
	return false;
};

var split = require('split');

var originRegex = /ORIGIN/;

var records = {};

var currentRecord = false;

process.stdin.pipe(split()).on('data', function(data) {
	var splitData = data.split(/\s+/);
	if (data.includes('$ORIGIN')) {
		// slice to remove trailing '.' character
		currentRecord = splitData[1].slice(0, -1);
		records[currentRecord] = [];
	} else {
		if (splitData.includes("A")  || splitData.includes("CNAME") || splitData.includes("AAAA")) {
			if (splitData[0] === "@") { return; }
			records[currentRecord].push(splitData[0]);
		}
	}
});

process.stdin.on('end', function() {
	Object.keys(records).forEach(function(key) {
		var domain = records[key];
		domain.forEach(function(sub) {
			console.log(sub + "." + key);
		});
	});
});