Don't encode responses with Cache-Control: no-transform

expressjs · Sep 8, 2015 · 70c5f8b · 70c5f8b
1 parent c2af8bd
commit 70c5f8b
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diff --git a/index.js b/index.js
@@ -135,6 +135,14 @@ function compression(options) {
         return
       }
 
+      // Don't compress for Cache-Control: no-transform
+      // https://tools.ietf.org/html/rfc7234#section-5.2.1.6
+      var cacheControl = res.getHeader('Cache-Control') || ''
+      if (cacheControl.match(/\bno-transform\b/)) {
+        nocompress('no-transform')
+        return
+      }
+
       // vary
       vary(res, 'Accept-Encoding')
 

diff --git a/test/compression.js b/test/compression.js
@@ -20,6 +20,20 @@ describe('compression()', function(){
     .expect(200, done)
   })
 
+  it('should skip Cache-Control: no-transform', function(done){
+    var server = createServer({ threshold: 0 }, function (req, res) {
+      res.setHeader('Content-Type', 'text/plain')
+      res.setHeader('Cache-Control', 'no-transform')
+      res.end('hello, world')
+    })
+
+    request(server)
+    .get('/')
+    .set('Accept-Encoding', 'gzip')
+    .expect(shouldNotHaveHeader('Content-Encoding'))
+    .expect(200, done)
+  })
+
   it('should skip unknown accept-encoding', function(done){
     var server = createServer({ threshold: 0 }, function (req, res) {
       res.setHeader('Content-Type', 'text/plain')