Enable versioning on demand

README.md

@@ -144,7 +144,9 @@ router.on('GET', '/example', (req, res, params, store) => {
 
 ##### Versioned routes
 
-If needed you can provide a `version` option, which will allow you to declare multiple versions of the same route.
+If needed you can provide a `version` option, which will allow you to declare multiple versions of the same route. If you never configure a versioned route, the `'Accept-Version'` header will be ignored.
+
+Remember to set a [Vary](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Vary) header in your responses with the value you are using for deifning the versioning (e.g.: 'Accept-Version'), to prevent cache poisoning attacks. You can also configure this as part your Proxy/CDN.
 
 ###### default
 <a name="semver"></a>

index.js

@@ -51,7 +51,7 @@ function Router (opts) {
   this.ignoreTrailingSlash = opts.ignoreTrailingSlash || false
   this.maxParamLength = opts.maxParamLength || 100
   this.allowUnsafeRegex = opts.allowUnsafeRegex || false
-  this.versioning = opts.versioning || acceptVersionStrategy
+  this.versioning = opts.versioning || acceptVersionStrategy(false)
   this.trees = {}
   this.routes = []
 }
@@ -111,6 +111,9 @@ Router.prototype._on = function _on (method, path, opts, handler, store) {
   })
 
   const version = opts.version
+  if (version != null && this.versioning.disabled) {
+    this.versioning = acceptVersionStrategy(true)
+  }
 
   for (var i = 0, len = path.length; i < len; i++) {
     // search for parametric or wildcard routes

lib/accept-version.js

@@ -2,9 +2,20 @@
 
 const SemVerStore = require('semver-store')
 
-module.exports = {
-  storage: SemVerStore,
-  deriveVersion: function (req, ctx) {
-    return req.headers['accept-version']
+function build (enabled) {
+  if (enabled) {
+    return {
+      storage: SemVerStore,
+      deriveVersion: function (req, ctx) {
+        return req.headers['accept-version']
+      }
+    }
+  }
+  return {
+    storage: SemVerStore,
+    deriveVersion: function (req, ctx) {},
+    disabled: true
   }
 }
+
+module.exports = build

test/version.default-versioning.test.js

@@ -240,3 +240,28 @@ test('It should throw if you declare multiple times the same route', t => {
     t.is(err.message, 'Method \'GET\' already declared for route \'/\' version \'1.2.3\'')
   }
 })
+
+test('Versioning won\'t work if there are no versioned routes', t => {
+  t.plan(2)
+
+  const findMyWay = FindMyWay({
+    defaultRoute: (req, res) => {
+      t.fail('We should not be here')
+    }
+  })
+
+  findMyWay.on('GET', '/', (req, res) => {
+    t.pass('Yeah!')
+  })
+
+  findMyWay.lookup({
+    method: 'GET',
+    url: '/',
+    headers: { 'accept-version': '2.x' }
+  }, null)
+
+  findMyWay.lookup({
+    method: 'GET',
+    url: '/'
+  }, null)
+})