feat: Add callback for configuring Vary header

lib/index.js

@@ -9,7 +9,8 @@
     origin: '*',
     methods: 'GET,HEAD,PUT,PATCH,POST,DELETE',
     preflightContinue: false,
-    optionsSuccessStatus: 204
+    optionsSuccessStatus: 204,
+    shouldSetVaryHeader: function(req, header) { return true }
   };
 
   function isString(s) {
@@ -50,21 +51,25 @@
         key: 'Access-Control-Allow-Origin',
         value: options.origin
       }]);
-      headers.push([{
-        key: 'Vary',
-        value: 'Origin'
-      }]);
+      if (options.shouldSetVaryHeader(req, 'Origin')) {
+        headers.push([{
+          key: 'Vary',
+          value: 'Origin'
+        }]);
+      }
     } else {
       isAllowed = isOriginAllowed(requestOrigin, options.origin);
       // reflect origin
       headers.push([{
         key: 'Access-Control-Allow-Origin',
         value: isAllowed ? requestOrigin : false
       }]);
-      headers.push([{
-        key: 'Vary',
-        value: 'Origin'
-      }]);
+      if (options.shouldSetVaryHeader(req, 'Origin')) {
+        headers.push([{
+          key: 'Vary',
+          value: 'Origin'
+        }]);
+      }
     }
 
     return headers;
@@ -97,10 +102,12 @@
 
     if (!allowedHeaders) {
       allowedHeaders = req.headers['access-control-request-headers']; // .headers wasn't specified, so reflect the request headers
-      headers.push([{
-        key: 'Vary',
-        value: 'Access-Control-Request-Headers'
-      }]);
+      if (options.shouldSetVaryHeader(req, 'Access-Control-Request-Headers')) {
+        headers.push([{
+          key: 'Vary',
+          value: 'Access-Control-Request-Headers'
+        }]);
+      }
     } else if (allowedHeaders.join) {
       allowedHeaders = allowedHeaders.join(','); // .headers is an array, so turn it into a string
     }

package.json

@@ -1,7 +1,7 @@
 {
   "name": "cors",
   "description": "Node.js CORS middleware",
-  "version": "2.8.5",
+  "version": "2.9.0",
   "author": "Troy Goode <troygoode@gmail.com> (https://github.com/troygoode/)",
   "license": "MIT",
   "keywords": [

test/test.js

@@ -150,6 +150,198 @@ var util = require('util')
       })
     });
 
+    describe('shouldSetVaryHeader', function() {
+      it('Vary: "Access-Control-Request-Headers" header is set by default for pre-flight requests', function (done) {
+        var cb = after(1, done)
+
+        var req = new FakeRequest('OPTIONS')
+        var res = new FakeResponse()
+        req.host = 'http://example.com'
+        req.originalUrl = '/images/asdf.png'
+
+
+        res.on('finish', function () {
+          assert.equal(res.statusCode, 204)
+          assert.equal(res.getHeader('Vary'), 'Access-Control-Request-Headers')
+          cb()
+        })
+
+        cors()(req, res, function (err) {
+          cb(err || new Error('should not be called'))
+        })
+      })
+
+      it('Vary: "Origin, Access-Control-Request-Headers" header is set by default for pre-flight requests with origins', function (done) {
+        var cb = after(1, done)
+
+        var req = new FakeRequest('OPTIONS')
+        var res = new FakeResponse()
+        req.host = 'http://example.com'
+        req.originalUrl = '/images/asdf.png'
+        var options = {
+          origin: 'https://example.com'
+        }
+
+        res.on('finish', function () {
+          assert.equal(res.statusCode, 204)
+          assert.equal(res.getHeader('Vary'), 'Origin, Access-Control-Request-Headers')
+          cb()
+        })
+
+        cors(options)(req, res, function (err) {
+          cb(err || new Error('should not be called'))
+        })
+      })
+
+      it('Vary: "Access-Control-Request-Headers" header is set for pre-flight requests and shouldSetVaryHeader(req, \'Origin\') configured to return false with origins', function (done) {
+        var cb = after(1, done)
+
+        var req = new FakeRequest('OPTIONS')
+        var res = new FakeResponse()
+        req.host = 'http://example.com'
+        req.originalUrl = '/images/asdf.png'
+        var options = {
+          origin: 'https://example.com',
+          shouldSetVaryHeader: function(req, header) {
+            if (header === 'Access-Control-Request-Headers') {
+              return true
+            }
+
+            if (req.originalUrl.indexOf('/images') === 0 && header === 'Origin') {
+              return false
+            } else {
+              return true
+            }
+          }
+        }
+
+        res.on('finish', function () {
+          assert.equal(res.statusCode, 204)
+          assert.equal(res.getHeader('Vary'), 'Access-Control-Request-Headers')
+          cb()
+        })
+
+        cors(options)(req, res, function (err) {
+          cb(err || new Error('should not be called'))
+        })
+      })
+
+      it('Vary: "Access-Control-Request-Headers" header is not set for pre-flight requests when shouldSetVaryHeader(req, \'Access-Control-Request-Headers\') configured to return false', function (done) {
+        var cb = after(1, done)
+
+        var req = new FakeRequest('OPTIONS')
+        var res = new FakeResponse()
+        req.host = 'http://example.com'
+        req.originalUrl = '/images/asdf.png'
+        var options = {
+          origin: 'https://example.com',
+          shouldSetVaryHeader: function(req, header) {
+            if (header === 'Access-Control-Request-Headers') {
+              return false
+            }
+
+            if (req.originalUrl.indexOf('/images') === 0 && header === 'Origin') {
+              return false
+            } else {
+              return true
+            }
+          }
+        }
+
+        res.on('finish', function () {
+          assert.equal(res.statusCode, 204)
+          assert.equal(res.getHeader('Vary'), undefined)
+          cb()
+        })
+
+        cors(options)(req, res, function (err) {
+          cb(err || new Error('should not be called'))
+        })
+      })
+
+      it('Vary: "Origin" header is set by default', function (done) {
+        var req = fakeRequest('GET')
+        var res = fakeResponse()
+        req.host = 'http://example.com'
+        req.originalUrl = '/images/asdf.png'
+        var options = {
+          origin: 'http://example.com'
+        }
+
+        var next = function () {
+          // assert
+          assert.equal(res.statusCode, 200)
+          assert.equal(res.getHeader('Vary'), 'Origin')
+          done();
+        };
+
+        cors(options)(req, res, next)
+      })
+
+      it('Vary: "Origin" header is not set when shouldSetVaryHeader(req, \'Origin\') configured to return false', function (done) {
+        var req = fakeRequest('GET')
+        var res = fakeResponse()
+        req.host = 'http://example.com'
+        req.originalUrl = '/images/asdf.png'
+
+        var options = {
+          origin: ['http://example.com', 'http://foo.com'],
+          shouldSetVaryHeader: function(req, header) {
+            if (header === 'Access-Control-Request-Headers') {
+              return true
+            }
+
+            if (req.originalUrl.indexOf('/images') === 0 && header === 'Origin') {
+              return false
+            } else {
+              return true
+            }
+          }
+        }
+
+        var next = function () {
+          // assert
+          assert.equal(res.statusCode, 200)
+          assert.equal(res.getHeader('Vary'), undefined)
+          done();
+        };
+
+        cors(options)(req, res, next)
+      })
+
+      it('Vary: "Origin" header is set when shouldSetVaryHeader(req, \'Origin\') configured to return true', function (done) {
+        var req = fakeRequest('GET')
+        var res = fakeResponse()
+        req.host = 'http://example.com'
+
+        req.originalUrl = '/some/other/path'
+
+        var options = {
+          origin: ['http://example.com', 'http://foo.com'],
+          shouldSetVaryHeader: function(req, header) {
+            if (header === 'Access-Control-Request-Headers') {
+              return true
+            }
+
+            if (req.originalUrl.indexOf('/images') === 0 && header === 'Origin') {
+              return false
+            } else {
+              return true
+            }
+          }
+        }
+
+        var next = function () {
+          // assert
+          assert.equal(res.statusCode, 200)
+          assert.equal(res.getHeader('Vary'), 'Origin')
+          done();
+        };
+
+        cors(options)(req, res, next)
+      })
+    })
+
     describe('passing static options', function () {
       it('overrides defaults', function (done) {
         var cb = after(1, done)