feat: add service worker server as an alternative to renderMedia (#2098)

* feat: add service worker server as an alternative to renderMedia

* code QL

* thanks gh auto merge

Co-authored-by: Diego Rodríguez Baquero <github@diegorbaquero.com>

1 files changed, 76 insertions, 0 deletions

diff --git a/lib/file.js b/lib/file.js
index fd9ac7c..f3de744 100644
--- a/lib/file.js
+++ b/lib/file.js
@@ -7,6 +7,9 @@ const streamToBlobURL = require('stream-to-blob-url')
 const streamToBuffer = require('stream-with-known-length-to-buffer')
 const FileStream = require('./file-stream')
 const queueMicrotask = require('queue-microtask')
+const rangeParser = require('range-parser')
+const mime = require('mime')
+const eos = require('end-of-stream')
 
 class File extends EventEmitter {
   constructor (torrent, file) {
@@ -33,6 +36,8 @@ class File extends EventEmitter {
       this.done = true
       this.emit('done')
     }
+
+    this._serviceWorker = torrent.client.serviceWorker
   }
 
   get downloaded () {
@@ -144,6 +149,77 @@ class File extends EventEmitter {
     render.render(this, elem, opts, cb)
   }
 
+  _serve (req) {
+    const res = {
+      status: 200,
+      headers: {
+        // Support range-requests
+        'Accept-Ranges': 'bytes',
+        'Content-Type': mime.getType(this.name),
+        'Cache-Control': 'no-cache, no-store, must-revalidate, max-age=0',
+        Expires: '0'
+      },
+      body: req.method === 'HEAD' ? '' : 'STREAM'
+    }
+    // force the browser to download the file if if it's opened in a new tab
+    if (req.destination === 'document') {
+      res.headers['Content-Type'] = 'application/octet-stream'
+      res.headers['Content-Disposition'] = 'attachment'
+      res.body = 'DOWNLOAD'
+    }
+
+    // `rangeParser` returns an array of ranges, or an error code (number) if
+    // there was an error parsing the range.
+    let range = rangeParser(this.length, req.headers.range || '')
+
+    if (range.constructor === Array) {
+      res.status = 206 // indicates that range-request was understood
+
+      // no support for multi-range request, just use the first range
+      range = range[0]
+
+      res.headers['Content-Range'] = `bytes ${range.start}-${range.end}/${this.length}`
+      res.headers['Content-Length'] = `${range.end - range.start + 1}`
+    } else {
+      res.headers['Content-Length'] = this.length
+    }
+
+    const stream = req.method === 'GET' && this.createReadStream(range)
+
+    let pipe = null
+    if (stream) {
+      this.emit('stream', { stream, req, file: this }, piped => {
+        pipe = piped
+
+        // piped stream might not close the original filestream on close/error, this is agressive but necessary
+        eos(piped, () => {
+          if (piped) piped.destroy()
+          stream.destroy()
+        })
+      })
+    }
+
+    return [res, pipe || stream, pipe && stream]
+  }
+
+  getStreamURL (cb = () => {}) {
+    if (typeof window === 'undefined') throw new Error('browser-only method')
+    if (!this._serviceWorker) throw new Error('No worker registered')
+    if (this._serviceWorker.state !== 'activated') throw new Error('Worker isn\'t activated')
+    const workerPath = this._serviceWorker.scriptURL.substr(0, this._serviceWorker.scriptURL.lastIndexOf('/') + 1).slice(window.location.origin.length)
+    const url = `${workerPath}webtorrent/${this._torrent.infoHash}/${encodeURI(this.path)}`
+    cb(null, url)
+  }
+
+  streamTo (elem, cb = () => {}) {
+    if (typeof window === 'undefined') throw new Error('browser-only method')
+    if (!this._serviceWorker) throw new Error('No worker registered')
+    if (this._serviceWorker.state !== 'activated') throw new Error('Worker isn\'t activated')
+    const workerPath = this._serviceWorker.scriptURL.substr(0, this._serviceWorker.scriptURL.lastIndexOf('/') + 1).slice(window.location.origin.length)
+    elem.src = `${workerPath}webtorrent/${this._torrent.infoHash}/${encodeURI(this.path)}`
+    cb(null, elem)
+  }
+
   _getMimeType () {
     return render.mime[path.extname(this.name).toLowerCase()]
   }