Use etag to generate ETag headers

History.md

@@ -5,6 +5,7 @@ unreleased
     - Applies to `res.sendFile`, `res.sendfile`, and `res.download`
     - `err` will be populated with request aborted error
   * Support IP address host in `req.subdomains`
+  * Use `etag` to generate `ETag` headers
   * deps: accepts@~1.1.0
     - update `mime-types`
   * deps: cookie-signature@1.0.5

lib/utils.js

@@ -3,9 +3,8 @@
  */
 
 var mime = require('send').mime;
-var crc32 = require('buffer-crc32');
-var crypto = require('crypto');
 var basename = require('path').basename;
+var etag = require('etag');
 var proxyaddr = require('proxy-addr');
 var qs = require('qs');
 var querystring = require('querystring');
@@ -20,17 +19,12 @@ var typer = require('media-typer');
  * @api private
  */
 
-exports.etag = function etag(body, encoding){
-  if (body.length === 0) {
-    // fast-path empty body
-    return '"1B2M2Y8AsgTpgAmY7PhCfg=="'
-  }
+exports.etag = function (body, encoding) {
+  var buf = !Buffer.isBuffer(body)
+    ? new Buffer(body, encoding)
+    : body
 
-  var hash = crypto
-    .createHash('md5')
-    .update(body, encoding)
-    .digest('base64')
-  return '"' + hash + '"'
+  return etag(buf, {weak: false})
 };
 
 /**
@@ -43,16 +37,11 @@ exports.etag = function etag(body, encoding){
  */
 
 exports.wetag = function wetag(body, encoding){
-  if (body.length === 0) {
-    // fast-path empty body
-    return 'W/"0-0"'
-  }
+  var buf = !Buffer.isBuffer(body)
+    ? new Buffer(body, encoding)
+    : body
 
-  var buf = Buffer.isBuffer(body)
-    ? body
-    : new Buffer(body, encoding)
-  var len = buf.length
-  return 'W/"' + len.toString(16) + '-' + crc32.unsigned(buf) + '"'
+  return etag(buf, {weak: true})
 };
 
 /**

package.json

@@ -33,6 +33,7 @@
     "debug": "~2.0.0",
     "depd": "0.4.4",
     "escape-html": "1.0.1",
+    "etag": "~1.3.0",
     "finalhandler": "0.2.0",
     "fresh": "0.2.4",
     "media-typer": "0.3.0",

test/res.send.js

@@ -118,13 +118,13 @@ describe('res', function(){
       var app = express();
 
       app.use(function(req, res){
-        var str = Array(1024 * 2).join('-');
+        var str = Array(1000).join('-');
         res.send(str);
       });
 
       request(app)
       .get('/')
-      .expect('ETag', 'W/"7ff-2796319984"')
+      .expect('ETag', 'W/"3e7-8084ccd1"')
       .end(done);
     })
 
@@ -132,7 +132,7 @@ describe('res', function(){
       var app = express();
 
       app.use(function(req, res){
-        var str = Array(1024 * 2).join('-');
+        var str = Array(1000).join('-');
         res.send(str);
       });
 
@@ -207,13 +207,13 @@ describe('res', function(){
       var app = express();
 
       app.use(function(req, res){
-        var str = Array(1024 * 2).join('-');
+        var str = Array(1000).join('-');
         res.send(new Buffer(str));
       });
 
       request(app)
       .get('/')
-      .expect('ETag', 'W/"7ff-2796319984"')
+      .expect('ETag', 'W/"3e7-8084ccd1"')
       .end(done);
     })
 
@@ -321,15 +321,17 @@ describe('res', function(){
 
   it('should respond with 304 Not Modified when fresh', function(done){
     var app = express();
+    var etag = '"asdf"';
 
     app.use(function(req, res){
-      var str = Array(1024 * 2).join('-');
+      var str = Array(1000).join('-');
+      res.set('ETag', etag);
       res.send(str);
     });
 
     request(app)
     .get('/')
-    .set('If-None-Match', 'W/"7ff-2796319984"')
+    .set('If-None-Match', etag)
     .expect(304, done);
   })
 
@@ -375,7 +377,7 @@ describe('res', function(){
 
         request(app)
         .get('/')
-        .expect('etag', 'W/"c-1525560792"', done)
+        .expect('etag', 'W/"c-5aee35d8"', done)
       })
 
       it('should send ETag for empty string response', function(done){
@@ -396,7 +398,7 @@ describe('res', function(){
         var app = express();
 
         app.use(function(req, res){
-          var str = Array(1024 * 2).join('-');
+          var str = Array(1000).join('-');
           res.send(str);
         });
 
@@ -404,7 +406,7 @@ describe('res', function(){
 
         request(app)
         .get('/')
-        .expect('etag', 'W/"7ff-2796319984"', done)
+        .expect('etag', 'W/"3e7-8084ccd1"', done)
       });
 
       it('should not override ETag when manually set', function(done){
@@ -445,7 +447,7 @@ describe('res', function(){
         var app = express();
 
         app.use(function(req, res){
-          var str = Array(1024 * 2).join('-');
+          var str = Array(1000).join('-');
           res.send(str);
         });
 
@@ -503,7 +505,7 @@ describe('res', function(){
 
         request(app)
         .get('/')
-        .expect('etag', 'W/"d-1486392595"', done)
+        .expect('etag', 'W/"d-58988d13"', done)
       })
     })
 

test/utils.js

@@ -28,18 +28,18 @@ describe('utils.etag(body, encoding)', function(){
 describe('utils.wetag(body, encoding)', function(){
   it('should support strings', function(){
     utils.wetag('express!')
-    .should.eql('W/"8-3098196679"')
+    .should.eql('W/"8-b8aabac7"')
   })
 
   it('should support utf8 strings', function(){
     utils.wetag('express❤', 'utf8')
-    .should.eql('W/"a-1751845617"')
+    .should.eql('W/"a-686b0af1"')
   })
 
   it('should support buffer', function(){
     var buf = new Buffer('express!')
     utils.wetag(buf)
-    .should.eql('W/"8-3098196679"');
+    .should.eql('W/"8-b8aabac7"');
   })
 
   it('should support empty string', function(){