From fc8b03a9dc12bb52eb3dd46a9acfd6fd03e9a32e Mon Sep 17 00:00:00 2001
From: Girish Ramakrishnan <girish@forwardbias.in>
Date: Wed, 8 Jan 2014 17:51:50 -0800
Subject: [PATCH] Add CORS middleware

---
 middleware/cors.js | 50 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 50 insertions(+)
 create mode 100644 middleware/cors.js

diff --git a/middleware/cors.js b/middleware/cors.js
new file mode 100644
index 000000000..de53ad339
--- /dev/null
+++ b/middleware/cors.js
@@ -0,0 +1,50 @@
+var _ = require('underscore'),
+    url = require('url');
+
+/*
+ * CORS middleware
+ *
+ * options can contains a list of origins
+ */
+module.exports = function cors(options) {
+    options = options || { };
+    var maxAge = options.maxAge || 60 * 60 * 25 * 5; // 5 days
+    var origins = options.origins || [ '*' ];
+    var allowCredentials = options.allowCredentials || false; // cookies
+
+    return function (req, res, next) {
+        var requestOrigin = req.headers.origin;
+        if (!requestOrigin) return next();
+
+        requestOrigin = url.parse(requestOrigin);
+
+        var hostname = requestOrigin.host.split(':')[0]; // remove any port
+        var matchedOrigin = _.find(origins, function (o) { return o === '*' || o === hostname });
+        if (_.isUndefined(matchedOrigin)) { return res.send(405, 'CORS not allowed from this domain'); }
+
+        // respond back with req.headers.origin which might contain the scheme
+        res.header('Access-Control-Allow-Origin', req.headers.origin);
+
+        // handle preflighted requests
+        if (req.method === 'OPTIONS') {
+            if (req.headers['access-control-request-method']) {
+                res.header('Access-Control-Allow-Methods', 'GET, PUT, DELETE, POST, OPTIONS');
+            }
+
+            if (req.headers['access-control-request-headers']) {
+                res.header('Access-Control-Allow-Headers', req.headers['access-control-request-headers']);
+            }
+
+            res.header('Access-Control-Allow-Credentials', allowCredentials);
+            res.header('Access-Control-Max-Age', maxAge);
+
+            return res.send(200);
+        }
+
+        if (req.headers['access-control-request-headers']) {
+            res.header('Access-Control-Allow-Headers', req.headers['access-control-request-headers']);
+        }
+
+        next();
+    }
+};