feat: Adding support for brolti

README.md

@@ -11,6 +11,9 @@ The following compression codings are supported:
 
   - deflate
   - gzip
+  - br (brotli)
+
+**Note** Brotli is supported only since Node.js versions v11.7.0 and v10.16.0.
 
 ## Install
 
@@ -44,7 +47,8 @@ as compressing will transform the body.
 
 `compression()` accepts these properties in the options object. In addition to
 those listed below, [zlib](http://nodejs.org/api/zlib.html) options may be
-passed in to the options object.
+passed in to the options object or
+[brotli](https://nodejs.org/api/zlib.html#zlib_class_brotlioptions) options.
 
 ##### chunkSize
 
@@ -101,6 +105,20 @@ The default value is `zlib.Z_DEFAULT_MEMLEVEL`, or `8`.
 See [Node.js documentation](http://nodejs.org/api/zlib.html#zlib_memory_usage_tuning)
 regarding the usage.
 
+##### params *(brotli only)* - [key-value object containing indexed Brotli parameters](https://nodejs.org/api/zlib.html#zlib_brotli_constants)
+
+  - `zlib.constants.BROTLI_PARAM_MODE`
+    - `zlib.constants.BROTLI_MODE_GENERIC` (default)
+    - `zlib.constants.BROTLI_MODE_TEXT`, adjusted for UTF-8 text
+    - `zlib.constants.BROTLI_MODE_FONT`, adjusted for WOFF 2.0 fonts
+  - `zlib.constants.BROTLI_PARAM_QUALITY`
+    - Ranges from `zlib.constants.BROTLI_MIN_QUALITY` to
+      `zlib.constants.BROTLI_MAX_QUALITY`, with a default of
+      `4` (which is not node's default but the most optimal).
+
+Note that here the default is set to compression level 4. This is a balanced setting with a very good speed and a very good
+compression ratio.
+
 ##### strategy
 
 This is used to tune the compression algorithm. This value only affects the

index.js

@@ -22,6 +22,7 @@ var debug = require('debug')('compression')
 var onHeaders = require('on-headers')
 var vary = require('vary')
 var zlib = require('zlib')
+var objectAssign = require('object-assign')
 
 /**
  * Module exports.
@@ -30,6 +31,12 @@ var zlib = require('zlib')
 module.exports = compression
 module.exports.filter = shouldCompress
 
+/**
+ * @const
+ * whether current node version has brotli support
+ */
+var hasBrotliSupport = 'createBrotliCompress' in zlib
+
 /**
  * Module variables.
  * @private
@@ -48,6 +55,17 @@ var cacheControlNoTransformRegExp = /(?:^|,)\s*?no-transform\s*?(?:,|$)/
 function compression (options) {
   var opts = options || {}
 
+  if (hasBrotliSupport) {
+    // set the default level to a reasonable value with balanced speed/ratio
+    if (opts.params === undefined) {
+      opts.params = {}
+    }
+
+    if (opts.params[zlib.constants.BROTLI_PARAM_QUALITY] === undefined) {
+      opts.params[zlib.constants.BROTLI_PARAM_QUALITY] = 4
+    }
+  }
+
   // options
   var filter = opts.filter || shouldCompress
   var threshold = bytes.parse(opts.threshold)
@@ -173,14 +191,12 @@ function compression (options) {
         return
       }
 
-      // compression method
-      var accept = accepts(req)
-      var method = accept.encoding(['gzip', 'deflate', 'identity'])
+      // force proper priorization
+      var headers = objectAssign({}, req.headers, { 'accept-encoding': prioritize(req.headers['accept-encoding']) })
 
-      // we really don't prefer deflate
-      if (method === 'deflate' && accept.encoding(['gzip'])) {
-        method = accept.encoding(['gzip', 'identity'])
-      }
+      // compression method
+      var accept = accepts(objectAssign({}, res, { headers: headers }))
+      var method = accept.encoding(['br', 'gzip', 'deflate', 'identity'])
 
       // negotiation failed
       if (!method || method === 'identity') {
@@ -192,7 +208,9 @@ function compression (options) {
       debug('%s compression', method)
       stream = method === 'gzip'
         ? zlib.createGzip(opts)
-        : zlib.createDeflate(opts)
+        : method === 'br'
+          ? zlib.createBrotliCompress(opts)
+          : zlib.createDeflate(opts)
 
       // add buffered listeners to stream
       addListeners(stream, stream.on, listeners)
@@ -286,3 +304,47 @@ function toBuffer (chunk, encoding) {
     ? Buffer.from(chunk, encoding)
     : chunk
 }
+
+/**
+ * Most browsers send "br" (brolti) as the last value in
+ * in the 'Accept-Encoding' header which causes it to be
+ * depriorited according to the spec.
+ *
+ * This is typically not what end users actually want so here
+ * we force the "br" (brotli) value to first in the list so that
+ * it will get properly prioritized and used.
+ *
+ * It's worth noting that although this is not "spec compliant",
+ * we belive it follows a well-established convention.
+ *
+ * @private
+ */
+function prioritize (str) {
+  return str && str.split(',')
+    .sort(sortAlgs)
+    .join(',')
+}
+
+/**
+ * Sort compression algs in order of preference:
+ * br > gzip > deflate | identity
+ *
+ * @private
+ */
+function sortAlgs (a, b) {
+  if (a.indexOf('br') >= 0) {
+    return -1
+  }
+  if (a.indexOf('gzip') >= 0) {
+    return b.indexOf('br') >= 0 ? 1 : -1
+  }
+  // we need these inverse rules to fix a stable sort bug
+  // found in node 10.x
+  if (b.indexOf('br') >= 0) {
+    return 1
+  }
+  if (b.indexOf('gzip') >= 0) {
+    return a.indexOf('br') >= 0 ? -1 : 1
+  }
+  return 0
+}

package.json

@@ -13,6 +13,7 @@
     "bytes": "3.0.0",
     "compressible": "~2.0.17",
     "debug": "2.6.9",
+    "object-assign": "^4.1.1",
     "on-headers": "~1.0.2",
     "safe-buffer": "5.2.0",
     "vary": "~1.1.2"

test/compression.js

@@ -9,6 +9,8 @@ var zlib = require('zlib')
 
 var compression = require('..')
 
+var hasBrotliSupport = 'createBrotliCompress' in zlib
+
 describe('compression()', function () {
   it('should skip HEAD', function (done) {
     var server = createServer({ threshold: 0 }, function (req, res) {
@@ -656,6 +658,156 @@ describe('compression()', function () {
         }))
         .end()
     })
+
+    var brotlit = hasBrotliSupport ? it : it.skip
+    brotlit('should flush small chunks for brotli', function (done) {
+      var chunks = 0
+      var next
+      var server = createServer({ threshold: 0 }, function (req, res) {
+        next = writeAndFlush(res, 2, Buffer.from('..'))
+        res.setHeader('Content-Type', 'text/plain')
+        next()
+      })
+
+      function onchunk (chunk) {
+        assert.ok(chunks++ < 20)
+        assert.strictEqual(chunk.toString(), '..')
+        next()
+      }
+
+      request(server)
+        .get('/')
+        .set('Accept-Encoding', 'br')
+        .request()
+        .on('response', unchunk('br', onchunk, function (err) {
+          if (err) return done(err)
+          server.close(done)
+        }))
+        .end()
+    })
+  })
+
+  describe('when "Accept-Encoding: br"', function () {
+    var brotlit = hasBrotliSupport ? it : it.skip
+    brotlit('should respond with br', function (done) {
+      var server = createServer({ threshold: 0 }, function (req, res) {
+        res.setHeader('Content-Type', 'text/plain')
+        res.end('hello, world')
+      })
+
+      request(server)
+        .get('/')
+        .set('Accept-Encoding', 'br')
+        .expect('Content-Encoding', 'br', done)
+    })
+  })
+
+  describe('when "Accept-Encoding: br" and passing compression level', function () {
+    var brotlit = hasBrotliSupport ? it : it.skip
+    brotlit('should respond with br', function (done) {
+      var params = {}
+      params[zlib.constants.BROTLI_PARAM_QUALITY] = 11
+
+      var server = createServer({ threshold: 0, params: params }, function (req, res) {
+        res.setHeader('Content-Type', 'text/plain')
+        res.end('hello, world')
+      })
+
+      request(server)
+        .get('/')
+        .set('Accept-Encoding', 'br')
+        .expect('Content-Encoding', 'br', done)
+    })
+  })
+
+  describe('when "Accept-Encoding: gzip, br"', function () {
+    var brotlit = hasBrotliSupport ? it : it.skip
+    brotlit('should respond with br', function (done) {
+      var server = createServer({ threshold: 0 }, function (req, res) {
+        res.setHeader('Content-Type', 'text/plain')
+        res.end('hello, world')
+      })
+
+      request(server)
+        .get('/')
+        .set('Accept-Encoding', 'gzip, br')
+        .expect('Content-Encoding', 'br', done)
+    })
+  })
+
+  describe('when "Accept-Encoding: deflate, gzip, br"', function () {
+    var brotlit = hasBrotliSupport ? it : it.skip
+    brotlit('should respond with br', function (done) {
+      var server = createServer({ threshold: 0 }, function (req, res) {
+        res.setHeader('Content-Type', 'text/plain')
+        res.end('hello, world')
+      })
+
+      request(server)
+        .get('/')
+        .set('Accept-Encoding', 'deflate, gzip, br')
+        .expect('Content-Encoding', 'br', done)
+    })
+  })
+
+  describe('when "Accept-Encoding: gzip;q=1, br;q=0.3"', function () {
+    var brotlit = hasBrotliSupport ? it : it.skip
+    brotlit('should respond with gzip', function (done) {
+      var server = createServer({ threshold: 0 }, function (req, res) {
+        res.setHeader('Content-Type', 'text/plain')
+        res.end('hello, world')
+      })
+
+      request(server)
+        .get('/')
+        .set('Accept-Encoding', 'gzip;q=1, br;q=0.3')
+        .expect('Content-Encoding', 'gzip', done)
+    })
+  })
+
+  describe('when "Accept-Encoding: gzip, br;q=0.8"', function () {
+    var brotlit = hasBrotliSupport ? it : it.skip
+    brotlit('should respond with gzip', function (done) {
+      var server = createServer({ threshold: 0 }, function (req, res) {
+        res.setHeader('Content-Type', 'text/plain')
+        res.end('hello, world')
+      })
+
+      request(server)
+        .get('/')
+        .set('Accept-Encoding', 'gzip, br;q=0.8')
+        .expect('Content-Encoding', 'gzip', done)
+    })
+  })
+
+  describe('when "Accept-Encoding: gzip;q=0.001"', function () {
+    var brotlit = hasBrotliSupport ? it : it.skip
+    brotlit('should respond with gzip', function (done) {
+      var server = createServer({ threshold: 0 }, function (req, res) {
+        res.setHeader('Content-Type', 'text/plain')
+        res.end('hello, world')
+      })
+
+      request(server)
+        .get('/')
+        .set('Accept-Encoding', 'gzip;q=0.001')
+        .expect('Content-Encoding', 'gzip', done)
+    })
+  })
+
+  describe('when "Accept-Encoding: deflate, br"', function () {
+    var brotlit = hasBrotliSupport ? it : it.skip
+    brotlit('should respond with br', function (done) {
+      var server = createServer({ threshold: 0 }, function (req, res) {
+        res.setHeader('Content-Type', 'text/plain')
+        res.end('hello, world')
+      })
+
+      request(server)
+        .get('/')
+        .set('Accept-Encoding', 'deflate, br')
+        .expect('Content-Encoding', 'br', done)
+    })
   })
 })
 
@@ -710,6 +862,9 @@ function unchunk (encoding, onchunk, onend) {
       case 'gzip':
         stream = res.pipe(zlib.createGunzip())
         break
+      case 'br':
+        stream = res.pipe(zlib.createBrotliDecompress())
+        break
     }
 
     stream.on('data', onchunk)