Work in progress, looks like we are going nowhere

Unless we dont have a mechanism to detect that there is only one chunk that is being sent(for damn sure?), we can't implement this

.eslintrc

@@ -1,35 +1,17 @@
 {
-  "extends": "google",
+  "extends": "r0mflip",
   "env": {
     "node": true
   },
   "parserOptions": {
     "ecmaVersion": 2017
   },
   "rules": {
-    "max-len": [2, 100, {
-      "ignoreComments": true,
+    "max-len": [2, {
+      "code": 100,
+      "tabWidth": 2,
       "ignoreUrls": true,
-      "tabWidth": 2
-    }],
-    "no-implicit-coercion": [2, {
-      "boolean": false,
-      "number": true,
-      "string": true
-    }],
-    "no-unused-expressions": [2, {
-      "allowShortCircuit": true,
-      "allowTernary": false
-    }],
-    "no-unused-vars": [2, {
-      "vars": "all",
-      "args": "after-used",
-      "argsIgnorePattern": "(^reject$|^_$)",
-      "varsIgnorePattern": "(^_$)"
-    }],
-    "quotes": [2, "single"],
-    "require-jsdoc": 0,
-    "valid-jsdoc": 0,
-    "arrow-parens": 0
+      "ignoreComments": true
+    }]
   }
 }

.travis.yml

@@ -1,6 +1,11 @@
 dist: trusty
 language: node_js
+sudo: false
 node_js:
-  - "9"
+  - "8"
+  - "10"
 script:
   - npm run test
+notification:
+  on_success: never
+  on_failure: always

README.md

@@ -1,10 +1,13 @@
 # taggart
 
-[![Greenkeeper badge](https://badges.greenkeeper.io/ramlmn/taggart.svg)](https://greenkeeper.io/)
-
 An ETag header middleware for express like apps. It is a zero dependency
 middleware which generates `ETags` accurately.
 
+**Note:** `express.static` uses `serve-static` which internally uses `send`.
+`send` generates/supports only weak `ETags`. If you want strong etags, then you
+have to write your own cache invalidation in your server, regardless of strong
+or weak.
+
 ## Installation
 
 ``` bash
@@ -27,10 +30,10 @@ app.use(...);
 
 # Working
 
-`taggart` simply overrides the `write`, `end` and `send` methods of the `res`
+`taggart` simply overrides the `write` and `end` methods of the `res`
 (`ServerResponse` object) and tries to gather around the response content
 being sent to the client, at the end, `taggart` adds the `ETag` header to the
-response if it is't buffered or tansfered in chunks.
+response if it is't buffered (or tansfered in chunks).
 
 ## License
 [MIT](LICENSE)

index.js

@@ -2,55 +2,92 @@
 
 const crypto = require('crypto');
 
+const noop = _ => {};
+
 /**
  * An ETag header middleware for express like apps
  *
- * @param {Object} req http IncomingMessage
- * @param {Object} res http ServerReponse
- * @param {Function} next next middleware to call
+ * @param {Object} opts options
+ * @param {Boolean} opts.weak weak tags?
+ * @return {Function}
  */
-const addEtag = (req, res, next = _ => {}) => {
-  const write = res.write;
-  const end = res.end;
-  const send = res.send;
-
-  const onData = (...args) => {
-    if (!res.headersSent
-      && !res.getHeader('Transfer-Encoding')
-      && !res.getHeader('TE')
-      && res.getHeader('Content-Length')) {
-      // we are in luck
-      const body = args[0];
-
-      // @TODO: allow weak etags
-
-      // genarate the etag
-      const etag = crypto.createHash('sha1')
-        .update(body)
-        .digest('hex');
-
-      res.setHeader('ETag', etag);
-    }
-  };
+const addEtag = opts => {
+  const weak = (opts !== undefined) ? !!opts.weak : false;
 
-  // override the default methods and collect response buffer
+  return (req, res, next = noop) => {
+    const write = res.write;
+    const end = res.end;
 
-  res.write = (...args) => {
-    onData(...args);
-    write.apply(res, [...args]);
-  };
+    // sha1 ain't that bad
+    const hash = crypto.createHash('sha1');
 
-  res.end = (...args) => {
-    onData(...args);
-    end.apply(res, [...args]);
-  };
+    // keep track, for content-length
+    let length = 0;
 
-  res.send = (...args) => {
-    onData(...args);
-    send.apply(res, [...args]);
-  };
+    let onData = (chunk, encoding) => {
+      const TE = (res.getHeader('Transfer-Encoding') || res.getHeader('TE') || '').toLowerCase();
+
+      // if (chunk) {
+      //   console.log(Buffer.byteLength(chunk, 'utf8'), res.headersSent, TE);
+      // } else {
+      //   console.log(undefined, res.headersSent, TE);
+      // }
+
+      if (res.headersSent || TE === 'chunked') {
+        // bail
+        onData = noop;
+        return;
+      }
+
+      // convert chunk to buffer
+      chunk = Buffer.isBuffer(chunk) ? chunk : Buffer.from(chunk, encoding);
+
+      hash.update(chunk);
+      length += Buffer.byteLength(chunk, 'utf8');
+    };
+
+    const onEnd = (chunk, encoding) => {
+      onData(chunk, encoding);
 
-  next();
+      // generate tag
+      const l = length.toString(16);
+      const h = hash.digest('hex');
+
+      const tag = weak ? `W/${l}-${h}` : `${l}-${h}`;
+
+      // check if headers can be sent, ignore TE
+      if (!res.headersSent) {
+        res.setHeader('Content-Length', length);
+
+        if (res.getHeader('ETag')) {
+          res.removeHeader('ETag');
+        }
+
+        res.setHeader('ETag', tag);
+      }
+    };
+
+    // override the default methods
+    res.write = (...args) => {
+      onData(...args);
+      write.apply(res, [...args]);
+    };
+
+    res.end = (...args) => {
+      onEnd(...args);
+      end.apply(res, [...args]);
+    };
+
+    // non standard, express like
+    res.send = (...args) => {
+      onEnd(...args);
+      end.apply(res, [...args]);
+    };
+
+    if (typeof next === 'function') {
+      next();
+    }
+  };
 };
 
 

package.json

@@ -1,34 +1,37 @@
 {
   "name": "@ramlmn/taggart",
   "version": "0.1.0",
+  "author": "@r0mflip",
   "description": "An ETag header middleware for express like apps",
   "main": "index.js",
   "scripts": {
     "test": "eslint . && node test/test.js"
   },
+  "engines": {
+    "node": ">=8.0.0"
+  },
+  "homepage": "https://github.com/ramlmn/taggart#readme",
+  "bugs": {
+    "url": "https://github.com/ramlmn/taggart/issues"
+  },
   "repository": {
     "type": "git",
     "url": "git+https://github.com/ramlmn/taggart.git"
   },
+  "license": "MIT",
+  "devDependencies": {
+    "eslint": "^5.6.0",
+    "eslint-config-r0mflip": "^0.1.3",
+    "express": "^4.16.3",
+    "node-fetch": "^2.2.0",
+    "tap-spec": "^5.0.0",
+    "tape": "^4.9.1"
+  },
   "keywords": [
     "ETag",
     "e-tag",
     "headers",
     "express",
     "middleware"
-  ],
-  "author": "@mram",
-  "license": "MIT",
-  "bugs": {
-    "url": "https://github.com/ramlmn/taggart/issues"
-  },
-  "homepage": "https://github.com/ramlmn/taggart#readme",
-  "devDependencies": {
-    "eslint": "^5.2.0",
-    "eslint-config-google": "^0.9.1",
-    "express": "^4.16.3",
-    "node-fetch": "^2.1.2",
-    "tap-spec": "^5.0.0",
-    "tape": "^4.9.0"
-  }
+  ]
 }

test/static/README.md

@@ -0,0 +1,5 @@
+# Attributions
+
+ * [atari-adventure.jpg](atari-adventure.jpg) by Scott Canoni from [WikiMedia Commons](https://commons.wikimedia.org/wiki/File:Atari_Adventure_Easter_Egg_on_Atari_(Jakks_Pacific)_Port.jpg)
+ * Big buck bunny [trailer](trailer_400p.ogg) from [https://peach.blender.org/trailer-page/](https://peach.blender.org/trailer-page/)
+ * Lipsum text from [https://lipsum.com](https://lipsum.com)

test/static/small-text.txt

@@ -0,0 +1 @@
+values of β give rises to dom!

test/test.js

@@ -14,29 +14,44 @@ tape
   .pipe(tapSpec())
   .pipe(process.stdout);
 
-tape('ETag test', async t => {
-  t.plan(2);
+
+tape('ETags test in express', async t => {
+  t.plan(5);
 
   const app = express();
   app.set('etag', false);
-  app.use(taggart);
-  app.use(express.static(path.resolve(__dirname, 'public')));
+  app.use(taggart());
+  app.use(express.static(path.resolve(__dirname, 'static')));
 
   const server = app.listen(0, async _ => {
     const {port} = server.address();
 
     try {
-      const res = await fetch(`http://localhost:${port}/garble.txt`);
+      const res = await fetch(`http://localhost:${port}/large-text.txt`);
+      const resETag = res.headers.get('ETag');
+      const testTag = 'W/"6281-165de617a21"';
+
+      if (resETag && testTag === resETag.toLowerCase()) {
+        t.pass(`Large text - got valid ETag ${resETag}`);
+      } else {
+        t.fail(`Large text - got invalid ETag ${resETag}`);
+      }
+    } catch (e) {
+      t.fail('Large text - Failed: ', e);
+    }
+
+    try {
+      const res = await fetch(`http://localhost:${port}/small-text.txt`);
       const resETag = res.headers.get('ETag');
       const testTag = '691544a391db46480b9a425ae3126fe2a0ec22fa';
 
       if (resETag && testTag === resETag.toLowerCase()) {
-        t.pass(`Test 1: Got valid ETag: ${resETag}`);
+        t.pass(`Small text - got valid ETag ${resETag}`);
       } else {
-        t.fail(`Test 1: Got invalid ETag: ${resETag}`);
+        t.fail(`Small text - got invalid ETag ${resETag}`);
       }
     } catch (e) {
-      t.fail('Test 1: Failed: ', e);
+      t.fail('Small text - Failed: ', e);
     }
 
     try {
@@ -45,12 +60,40 @@ tape('ETag test', async t => {
       const testTag = 'b13764e8ffd613c4734f67fe51e47afd6bd903f2';
 
       if (resETag && testTag === resETag.toLowerCase()) {
-        t.pass(`Test 2: Got valid ETag: ${resETag}`);
+        t.pass(`JSON request - got valid ETag ${resETag}`);
+      } else {
+        t.fail(`JSON request - got invalid ETag ${resETag}`);
+      }
+    } catch (e) {
+      t.fail('JSON request: Failed: ', e);
+    }
+
+    try {
+      const res = await fetch(`http://localhost:${port}/trailer_400p.ogg`);
+      const resETag = res.headers.get('ETag');
+      const testTag = 'b13764e8ffd613c4734f67fe51e47afd6bd903f2';
+
+      if (resETag && testTag === resETag.toLowerCase()) {
+        t.pass(`Video request - got valid ETag ${resETag}`);
+      } else {
+        t.fail(`Video request - got invalid ETag ${resETag}`);
+      }
+    } catch (e) {
+      t.fail('Video request: Failed: ', e);
+    }
+
+    try {
+      const res = await fetch(`http://localhost:${port}/atari-adventure.jpg`);
+      const resETag = res.headers.get('ETag');
+      const testTag = 'b13764e8ffd613c4734f67fe51e47afd6bd903f2';
+
+      if (resETag && testTag === resETag.toLowerCase()) {
+        t.pass(`Video request - got valid ETag ${resETag}`);
       } else {
-        t.fail(`Test 2: Got invalid ETag: ${resETag}`);
+        t.fail(`Video request - got invalid ETag ${resETag}`);
       }
     } catch (e) {
-      t.fail('Test 2: Failed: ', e);
+      t.fail('Video request: Failed: ', e);
     }
 
     server.close();