postmailer/express.js

HTTP POST -> SMTP proxy, as Express middleware

var fs = require('fs');
var stream = require('stream');
var parseHeader = require('parse-http-header');

function htmlEscape(value) {
	return value.replace(/&/g, '&amp;').replace(/</g, '&lt;').replace(/"/g, '&quot;');
}

function enableCors(request, response) {
	response.setHeader("Access-Control-Allow-Origin", "*");
	response.setHeader("Access-Control-Allow-Headers", "Origin, X-Requested-With, Content-Type, Accept, Link, From, Subject, CC");
	if (request.method === 'OPTIONS') {
		var methods = "HEAD,GET,POST,OPTIONS";
		response.setHeader("Access-Control-Allow-Methods", methods);
		response.setHeader("Access-Control-Allow-Headers", request.header("Access-Control-Request-Headers"));
	}
}

function loadHtmlTemplateSync(file, minify) {
	var template = fs.readFileSync(file, {encoding: 'utf-8'});
	if (minify) {
		try {
			template = require('html-minifier').minify(template, {
				collapseWhitespace: true,
				minifyJS: true,
				minifyCSS: true
			});
		} catch (e) {
			console.error(e);
			// Nothing - the HTML minifier module might not be installed
		}
	}
	return function (match, httpUrl, wsUrl) {
		var subs = {
			url: httpUrl,
			name: match.name,
			'ws-url': wsUrl
		}
		return template.replace(/\{\{(.*?)\}\}/g, function (match, key) {
			return htmlEscape((subs[key] || "") + "");
		});
	};
}

// Pipe through to another stream without changes
// - otherwise the "path" property can screw things up
function copyStream(source) {
	var content = new stream.Transform();
	content._transform = function (chunk, encoding, callback) {
		this.push(chunk, encoding);
		callback();
	};
	source.pipe(content);
	return content;
}

function expressHandler(hub, options) {
	options = options || {};

	var htmlTemplate = null;
	var form = options.webForm || options.form;
	if (form !== false) {
		if (typeof form === 'function') {
			htmlTemplate = form;
		} else {
			var templateFile = (typeof form === 'string') ? form : 'rich';
			if (/^[^\/]+$/.test(templateFile) && fs.existsSync(__dirname + '/templates/' + templateFile + '.html')) {
				templateFile = __dirname + '/templates/' + templateFile + '.html';
			}
			htmlTemplate = loadHtmlTemplateSync(templateFile, options.minifyForm);
		}
	}

	return function (request, response, next) {
		// TODO: additionally add 'https' if it's secure
		var url = 'http://' + request.get('host') + request.originalUrl.replace(/\?.*/, ''); // Reconstruct (without query)
		// WebSocket version (used for template only)
		var wsUrl = 'ws://' + request.get('host') + request.originalUrl.replace(/\?.*/, '');
		var match = hub.match(url); // TODO: filter on "acceptPost" flag
		if (!match) return next();

		enableCors(request, response);

		function textResult(code, text) {
			response.setHeader('Content-Type', 'text/plain');
			response.status(code).send(text);
		}

		if (request.method === 'OPTIONS') {
			return textResult(200, 'This endpoint implements the "HTTP POST mail" principle.\r\n\r\nhttps://www.npmjs.com/package/postmailer');
		} else if (request.method === 'GET') {
			if (!htmlTemplate) return next();
			response.setHeader('Content-Type', 'text/html');
			var wsMatch = hub.match(wsUrl);
			response.send(htmlTemplate(match, url, wsMatch && wsUrl));
		} else if (request.method === 'POST') {
			var fromHeader = request.header('from');
			if (!fromHeader) {
				return textResult(400, '"From" header is required');
			} else if (!/@/.test(fromHeader) && !/\:\/\//.test(fromHeader)) {
				return textResult(400, '"From" header must contain URL or email address');
			}

			var filename = null;
			if (request.header('content-disposition')) {
				var parsed = parseHeader(request.header('content-disposition'));
				if (parsed[0] !== 'inline' && parsed.filename) filename = parsed.filename;
			}

			hub.emit('mail', {
				target: match,
				headers: request.headers,
				filename: filename,
				message: copyStream(request),
				length: parseFloat(request.header['content-length']) || null
			});

			var messageHeaders = request.headers;
			return textResult(200, "Message accepted");
		} else {
			return textResult(405, 'Unknown HTTP method: ' + request.method);
		}
	}
}

module.exports = expressHandler;