fix(gateway): streaming compressed payload

This change simplifies code responsible for streaming response
and makes the streaming actually work by telling the payload compression
stream to flush its content on every read().
(previous version was buffering entire thing in Hapi's compressor memory)

We also do content-type detection based on the beginning of the stream
by peeking at first `fileType.minimumBytes` bytes.

License: MIT
Signed-off-by: Marcin Rataj <lidel@lidel.org>

package.json

@@ -88,6 +88,7 @@
     "bl": "^3.0.0",
     "boom": "^7.2.0",
     "bs58": "^4.0.1",
+    "buffer-peek-stream": "^1.0.1",
     "byteman": "^1.3.5",
     "cid-tool": "~0.2.0",
     "cids": "~0.5.8",

src/http/gateway/resources/gateway.js

@@ -3,13 +3,12 @@
 const debug = require('debug')
 const log = debug('ipfs:http-gateway')
 log.error = debug('ipfs:http-gateway:error')
-const pull = require('pull-stream')
-const pushable = require('pull-pushable')
-const toStream = require('pull-stream-to-stream')
+
 const fileType = require('file-type')
 const mime = require('mime-types')
 const { PassThrough } = require('readable-stream')
 const Boom = require('boom')
+const peek = require('buffer-peek-stream')
 
 const { resolver } = require('ipfs-http-response')
 const PathUtils = require('../utils/path')
@@ -30,6 +29,20 @@ function detectContentType (ref, chunk) {
   return mime.contentType(mimeType)
 }
 
+// Enable streaming of compressed payload
+// https://github.com/hapijs/hapi/issues/3599
+class ResponseStream extends PassThrough {
+  _read (size) {
+    super._read(size)
+    if (this._compressor) {
+      this._compressor.flush()
+    }
+  }
+  setCompressor (compressor) {
+    this._compressor = compressor
+  }
+}
+
 module.exports = {
   checkCID (request, h) {
     if (!request.params.cid) {
@@ -85,58 +98,46 @@ module.exports = {
       return h.redirect(PathUtils.removeTrailingSlash(ref)).permanent(true)
     }
 
-    return new Promise((resolve, reject) => {
-      let pusher
-      let started = false
-
-      pull(
-        ipfs.catPullStream(data.cid),
-        pull.drain(
-          chunk => {
-            if (!started) {
-              started = true
-              pusher = pushable()
-              const res = h.response(toStream.source(pusher).pipe(new PassThrough()))
-
-              // Etag maps directly to an identifier for a specific version of a resource
-              res.header('Etag', `"${data.cid}"`)
+    const rawStream = ipfs.catReadableStream(data.cid)
+    const responseStream = new ResponseStream()
+
+    // Pass-through Content-Type sniffing over initial bytes
+    const contentType = await new Promise((resolve, reject) => {
+      try {
+        const peekBytes = fileType.minimumBytes
+        peek(rawStream, peekBytes, (err, streamHead, outputStream) => {
+          if (err) {
+            log.error(err)
+            return reject(err)
+          }
+          outputStream.pipe(responseStream)
+          resolve(detectContentType(ref, streamHead))
+        })
+      } catch (err) {
+        log.error(err)
+        reject(err)
+      }
+    })
 
-              // Set headers specific to the immutable namespace
-              if (ref.startsWith('/ipfs/')) {
-                res.header('Cache-Control', 'public, max-age=29030400, immutable')
-              }
+    const res = h.response(responseStream)
 
-              const contentType = detectContentType(ref, chunk)
+    // Etag maps directly to an identifier for a specific version of a resource
+    res.header('Etag', `"${data.cid}"`)
 
-              log('ref ', ref)
-              log('mime-type ', contentType)
+    // Set headers specific to the immutable namespace
+    if (ref.startsWith('/ipfs/')) {
+      res.header('Cache-Control', 'public, max-age=29030400, immutable')
+    }
 
-              if (contentType) {
-                log('writing content-type header')
-                res.header('Content-Type', contentType)
-              }
+    log('ref ', ref)
+    log('content-type ', contentType)
 
-              resolve(res)
-            }
-            pusher.push(chunk)
-          },
-          err => {
-            if (err) {
-              log.error(err)
-
-              // We already started flowing, abort the stream
-              if (started) {
-                return pusher.end(err)
-              }
-
-              return reject(err)
-            }
+    if (contentType) {
+      log('writing content-type header')
+      res.header('Content-Type', contentType)
+    }
 
-            pusher.end()
-          }
-        )
-      )
-    })
+    return res
   },
 
   afterHandler (request, h) {

test/gateway/index.js

@@ -156,10 +156,15 @@ describe('HTTP Gateway', function () {
 
     expect(res.statusCode).to.equal(200)
     expect(res.rawPayload).to.eql(bigFile)
+    expect(res.headers['x-ipfs-path']).to.equal(`/ipfs/${bigFileHash}`)
+    expect(res.headers['etag']).to.equal(`"${bigFileHash}"`)
+    expect(res.headers['cache-control']).to.equal('public, max-age=29030400, immutable')
+    expect(res.headers['content-type']).to.equal('application/octet-stream')
   })
 
   it('load a jpg file', async () => {
     const kitty = 'QmW2WQi7j6c7UgJTarActp7tDNikE4B2qXtFCfLPdsgaTQ/cat.jpg'
+    const kittyDirectCid = 'Qmd286K6pohQcTKYqnS1YhWrCiS4gz7Xi34sdwMe9USZ7u'
 
     const res = await gateway.inject({
       method: 'GET',
@@ -169,6 +174,7 @@ describe('HTTP Gateway', function () {
     expect(res.statusCode).to.equal(200)
     expect(res.headers['content-type']).to.equal('image/jpeg')
     expect(res.headers['x-ipfs-path']).to.equal('/ipfs/' + kitty)
+    expect(res.headers['etag']).to.equal(`"${kittyDirectCid}"`)
     expect(res.headers['cache-control']).to.equal('public, max-age=29030400, immutable')
     expect(res.headers.etag).to.equal('"Qmd286K6pohQcTKYqnS1YhWrCiS4gz7Xi34sdwMe9USZ7u"')
     expect(res.headers.suborigin).to.equal('ipfs000bafybeidsg6t7ici2osxjkukisd5inixiunqdpq2q5jy4a2ruzdf6ewsqk4')