postmailer/ws.js

HTTP POST -> SMTP proxy, as Express middleware

var crypto = require('crypto');
var WebSocketServer = require('ws').Server;

function parseHeaders(headers) {
	var matches = headers.match(/(^|\n)[a-z\-]+:([^\r\n]|\r?\n[ \t])+/ig);
	if (!matches) return null;
	var result = {};
	matches.forEach(function (match) {
		var key = match.split(':', 1)[0];
		var value = match.substring(key.length + 1).replace(/(^\s+)/, '').replace(/\s+$/, '');
		key = key.toLowerCase().replace('\n', '');
		value = value.replace(/\r?\n[ \t]+/g, ' ');
		result[key] = value;
	});
	return result;
}

function headersToString(headers) {
	var result = '';
	var keys = Object.keys(headers);
	keys.sort();
	keys.forEach(function (key) {
		var value = headers[key].replace(/(^\s+|\s+$)/g, '');
		key = key.replace(/(^|\-)./g, function (s) {
			return s.toUpperCase();
		});
		result += key + ': ' + value + '\r\n';
	});
	return result;
}

function matchRequest(hub, request) {
	// TODO: additionally add 'wss' if it's secure
	var url = 'ws://' + (request.headers['host']) + request.url.replace(/\?.*/, ''); // Reconstruct (without query)
	return hub.match(url);
	return url;
}

function handleChat(hub, options) {
	options = options || {};
	options.verifyClient = function (info) {
		return !!matchRequest(hub, info.req);
	};
	var wsServer = new WebSocketServer(options);

	var connectionIdMap = {};
	hub.handle('chat', function (chat, next) {
		var targetUrls = chat.target.urls;
		var connection = null;
		for (var i = 0; i < targetUrls.length; i++) {
			connection = connectionIdMap[targetUrls[i]];
			if (connection) break;
		}
		if (!connection) return next();

		var headers = headersToString(chat.headers);
		var prefix = '';
		var message = chat.message;
		if (headers && headers !== connection.sentHeaders) {
			connection.sentHeaders = headers;
			prefix = headers + '\r\n';
		} else if (/^([^\r\n]+\r?\n)*\r?\n/.test(message.toString('ascii'))) {
			prefix = '\r\n';
		}
		if (prefix) {
			if (typeof message === 'string') {
				message = prefix + message;
			} else {
				message = Buffer.concat([new Buffer(prefix, 'ascii'), message]);
			}
		}
		connection.socket.send(message);
	});

	wsServer.on('connection', function (ws) {
		// TODO: assemble ws:// URL from host and match on that
		var target = matchRequest(hub, ws.upgradeReq);
		if (!target) return ws.close();

		// Events, and management within the map
		var connectionId = 'chat:' + crypto.randomBytes(24).toString('base64').replace(/\//g, '_').replace(/\+/g, '-');
		connectionIdMap[connectionId] = {
			socket: ws,
			sentHeaders: 'Content-Type: text/plain'
		};
		var source = {
			url: connectionId,
			name: 'WebSocket chat'
		};

		hub.emit('chat-open', {
			source: source,
			target: target
		});
		ws.on('close', function () {
			hub.emit('chat-close', {
				source: source,
				target: target
			});
			delete connectionIdMap[connectionId];
		});
		ws.on('error', function (error) {
			hub.emit('chat-error', {
				source: source,
				target: target,
				error: error
			});
			hub.emit('error', error);
			delete connectionIdMap[connectionId];
		});

		var latestHeaders = parseHeaders('Content-Type: text/plain');

		var messageCounter = 0;
		ws.on('message', function (message) {
			var stringMessage = (typeof message === 'string') ? message : message.toString('ascii');

			var headerMatch = stringMessage.match(/^([^\r\n]+\r?\n)*\r?\n/);
			if (headerMatch) {
				latestHeaders = parseHeaders(headerMatch[0]) || latestHeaders;
				if (typeof message === 'string') {
					message = message.substring(headerMatch[0].length);
				} else {
					message = message.slice(headerMatch[0].length);
				}
			}
			stringMessage = null;

			hub.emit('chat', {
				target: target,
				source: source,
				headers: JSON.parse(JSON.stringify(latestHeaders)),
				message: message
			});
		});
	});
}

module.exports = handleChat;

return;