node-echo-server/server.js at master · jpillora/node-echo-server · GitHub

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var pkg = require("./package.json");
var metrics = require("./metrics");
var http = require("http");
var dns = require("dns");
var port = process.env.PORT || parseInt(process.argv[2], 10) || 4000;
var echoes = [];
var total = 0;
var live = 0;
var up = new Date().toUTCString();
//replay a single echo
var getEcho = function(id, res) {
	res.writeHead(200, {
		'Content-Type': 'application/json'
	});
	res.end(JSON.stringify(echoes[id], null, 2));
};
//get metadata for all echoes
var getEchos = function(res) {
	res.writeHead(200, {
		'Content-Type': 'application/json'
	});
	var ips = {};
	var methods = {};
	var stats = {
		live: live,
		total: total,
		totalLength: 0,
		methods: methods,
		ips: ips
	};
	echoes.forEach(function(echo) {
		var id = echo.domains || echo.ip;
		if (!ips[id]) ips[id] = [];
		ips[id].push(echo.meta.num);
		if (!methods[echo.method]) methods[echo.method] = 0;
		methods[echo.method]++;
		stats.totalLength += parseInt(echo.headers['content-length'], 10) || 0;
	});
	//compress id lists
	for (var id in ips) {
		var range = null;
		ips[id] = ips[id].reduce(function(nums, num, i, arr) {
			var lastIndex = arr.length - 1;
			var hasNext = i + 1 <= lastIndex;
			var increments = hasNext && arr[i + 1] === num + 1;
			if (hasNext && increments) {
				if (!range) range = [num];
				return nums;
			} else if (range) {
				range.push(num);
				nums.push(range);
				range = null;
				return nums;
			}
			nums.push(num);
			return nums;
		}, []);
	}
	res.end(JSON.stringify(stats), null, 2);
};
//special endpoint for xdomain
var getProxy = function(xdomain, res) {
	res.writeHead(200, {
		'Content-Type': 'text/html'
	});
	res.end('<!DOCTYPE HTML>\n' + '<script src="' + (xdomain || '//rawgit.com/jpillora/xdomain/gh-pages/dist/0.6/xdomain.js') + '" master="*"></script>');
};
//create the server!
http.createServer(function(req, res) {
	//special actions
	if (req.url === '/favicon.ico') {
		return res.end();
	} else if (/^\/echo\/(\d+)\/?/.test(req.url)) {
		return getEcho(RegExp.$1, res);
	} else if (/^\/echoes-request/.test(req.url)) {
		return metrics.fetch(req, res);
	} else if (/^\/echoes/.test(req.url)) {
		return getEchos(res);
	} else if (/^\/proxy\.html(\?src=(.+))?$/.test(req.url)) {
		return getProxy(RegExp.$2, res);
	}
	//do echo
	var num = echoes.length;
	var ip = req.headers["x-forwarded-for"] || req.connection.remoteAddress;
	var status = 200;
	if (/\/status\/(\d{3})/.test(req.url)) status = parseInt(RegExp.$1, 10);
	var delay = 0;
	if (/\/delay\/(\d{1,5})/.test(req.url)) delay = parseInt(RegExp.$1, 10);
	var host = 'http://' + req.headers['host'];
	var referer = /^(https?:\/\/[^\/]+)/.test(req.headers['referer']) ? RegExp.$1 : '*';
	var headers = {
		'content-type': 'application/json',
		'echo-server-version': pkg.version,
		'cache-control': 'no-cache'
	};
	//apply cors when needed
	if (host !== referer) {
		headers['access-control-allow-credentials'] = true;
		headers['access-control-allow-origin'] = referer;
		if (req.headers['access-control-request-method']) headers['access-control-allow-methods'] = req.headers['access-control-request-method'];
		if (req.headers['access-control-request-headers']) headers['access-control-allow-headers'] = req.headers['access-control-request-headers'];
		headers['access-control-max-age'] = 0;
	}
	total++;
	live++;
	//wipe heroku headers
	for (var k in req.headers)
		if (/^x-/.test(k)) delete req.headers[k];
	var data = {
		ip: ip,
		domains: null, //unset
		time: Date.now(),
		method: req.method,
		url: req.url,
		body: "",
		headers: req.headers,
		meta: {
			up: up,
			num: num,
			live: live,
			status: status,
			delay: delay
		}
	};
	//echoes fall off the front
	if (echoes.length >= 100) echoes.unshift();
	//push onto the back
	echoes.push(data);
	req.on('data', function(buffer) {
		data.body += buffer.toString();
	});
	var send = function() {
		//send after has domains AND request ended
		if (data.domains === null || !req.ended) return;
		//process (if able)
		metrics.process(data);
		var buff = new Buffer(JSON.stringify(data, null, 2));
		var length = buff.length;
		headers['content-length'] = length;
		//write header
		res.writeHead(status, headers);

		function end(buff) {
			if (buff) res.write(buff);
			res.end();
			live--;
		}
		//write all now
		if (delay === 0) return end(buff);
		//with delay, write out 10 chunks over 10 time intervals
		var d = Math.ceil(delay / 10);
		var l = Math.ceil(length / 10);
		(function sendChunk() {
			var b = buff.slice(0, l);
			if (b.length === 0) return end();
			res.write(b);
			buff = buff.slice(l);
			setTimeout(sendChunk, d);
		}());
	};
	//attempt a reverse lookup on the remote ip
	try {
		dns.reverse(ip, function(err, domains) {
			data.domains = domains ? domains.length === 1 ? domains[0] : domains.length >= 2 ? domains : undefined : undefined;
			send();
		});
	} catch (err) {
		data.domains = undefined;
		send();
	}
	//
	req.on('end', function() {
		req.ended = true;
		send();
	});
}).listen(port, "0.0.0.0", function() {
	console.log("listening on " + port + "...");
});