Extend request methods for Download button #356 (#429)

package.json

@@ -53,6 +53,7 @@
     "remove-markdown": "^0.5.0",
     "stac-layer": "^0.15.0",
     "stac-node-validator": "^2.0.0-beta.7",
+    "streamsaver-js": "^2.0.7",
     "urijs": "^1.19.11",
     "v-clipboard": "^3.0.0-next.1",
     "vue": "^2.6.12",

public/mitm.html

@@ -0,0 +1,168 @@
+<!--
+	mitm.html is the lite "man in the middle"
+
+	This is only meant to signal the opener's messageChannel to
+	the service worker - when that is done this mitm can be closed
+    but it's better to keep it alive since this also stops the sw
+    from restarting
+
+	The service worker is capable of intercepting all request and fork their
+	own "fake" response - wish we are going to craft
+	when the worker then receives a stream then the worker will tell the opener
+	to open up a link that will start the download
+-->
+<script>
+  // This will prevent the sw from restarting
+  let keepAlive = () => {
+    keepAlive = () => {}
+    var ping = location.href.substr(0, location.href.lastIndexOf('/')) + '/ping'
+    var interval = setInterval(() => {
+      if (sw) {
+        sw.postMessage('ping')
+      } else {
+        fetch(ping).then(res => res.text(!res.ok && clearInterval(interval)))
+      }
+    }, 10000)
+  }
+
+  // message event is the first thing we need to setup a listner for
+  // don't want the opener to do a random timeout - instead they can listen for
+  // the ready event
+  // but since we need to wait for the Service Worker registration, we store the
+  // message for later
+  let messages = []
+  window.onmessage = evt => messages.push(evt)
+
+  let sw = null
+  let scope = ''
+
+  function registerWorker() {
+    return navigator.serviceWorker.getRegistration('./').then(swReg => {
+      return swReg || navigator.serviceWorker.register('sw.js', { scope: './' })
+    }).then(swReg => {
+      const swRegTmp = swReg.installing || swReg.waiting
+
+      scope = swReg.scope
+
+      return (sw = swReg.active) || new Promise(resolve => {
+        swRegTmp.addEventListener('statechange', fn = () => {
+          if (swRegTmp.state === 'activated') {
+            swRegTmp.removeEventListener('statechange', fn)
+            sw = swReg.active
+            resolve()
+          }
+        })
+      })
+    })
+  }
+
+  // Now that we have the Service Worker registered we can process messages
+  function onMessage (event) {
+    let { data, ports, origin } = event
+
+    // It's important to have a messageChannel, don't want to interfere
+    // with other simultaneous downloads
+    if (!ports || !ports.length) {
+      throw new TypeError("[StreamSaver] You didn't send a messageChannel")
+    }
+
+    if (typeof data !== 'object') {
+      throw new TypeError("[StreamSaver] You didn't send a object")
+    }
+
+    // the default public service worker for StreamSaver is shared among others.
+    // so all download links needs to be prefixed to avoid any other conflict
+    data.origin = origin
+
+    // if we ever (in some feature versoin of streamsaver) would like to
+    // redirect back to the page of who initiated a http request
+    data.referrer = data.referrer || document.referrer || origin
+
+    // pass along version for possible backwards compatibility in sw.js
+    data.streamSaverVersion = new URLSearchParams(location.search).get('version')
+
+    if (data.streamSaverVersion === '1.2.0') {
+      console.warn('[StreamSaver] please update streamsaver')
+    }
+
+    /** @since v2.0.0 */
+    if (!data.headers) {
+      console.warn("[StreamSaver] pass `data.headers` that you would like to pass along to the service worker\nit should be a 2D array or a key/val object that fetch's Headers api accepts")
+    } else {
+      // test if it's correct
+      // should thorw a typeError if not
+      new Headers(data.headers)
+    }
+
+    /** @since v2.0.0 */
+    if (typeof data.filename === 'string') {
+      console.warn("[StreamSaver] You shouldn't send `data.filename` anymore. It should be included in the Content-Disposition header option")
+      // Do what File constructor do with fileNames
+      data.filename = data.filename.replace(/\//g, ':')
+    }
+
+    /** @since v2.0.0 */
+    if (data.size) {
+      console.warn("[StreamSaver] You shouldn't send `data.size` anymore. It should be included in the content-length header option")
+    }
+
+    /** @since v2.0.0 */
+    if (data.readableStream) {
+      console.warn("[StreamSaver] You should send the readableStream in the messageChannel, not throught mitm")
+    }
+
+    /** @since v2.0.0 */
+    if (!data.pathname) {
+      console.warn("[StreamSaver] Please send `data.pathname` (eg: /pictures/summer.jpg)")
+      data.pathname = Math.random().toString().slice(-6) + '/' + data.filename
+    }
+
+    // remove all leading slashes
+    data.pathname = data.pathname.replace(/^\/+/g, '')
+
+    // remove protocol
+    let org = origin.replace(/(^\w+:|^)\/\//, '')
+
+    // set the absolute pathname to the download url.
+    data.url = new URL(`${scope + org}/${data.pathname}`).toString()
+
+    if (!data.url.startsWith(`${scope + org}/`)) {
+      throw new TypeError('[StreamSaver] bad `data.pathname`')
+    }
+
+    // This sends the message data as well as transferring
+    // messageChannel.port2 to the service worker. The service worker can
+    // then use the transferred port to reply via postMessage(), which
+    // will in turn trigger the onmessage handler on messageChannel.port1.
+
+    const transferable = data.readableStream
+      ? [ ports[0], data.readableStream ]
+      : [ ports[0] ]
+
+    if (!(data.readableStream || data.transferringReadable)) {
+      keepAlive()
+    }
+
+    return sw.postMessage(data, transferable)
+  }
+
+  if (window.opener) {
+    // The opener can't listen to onload event, so we need to help em out!
+    // (telling them that we are ready to accept postMessage's)
+    window.opener.postMessage('StreamSaver::loadedPopup', '*')
+  }
+
+  if (navigator.serviceWorker) {
+    registerWorker().then(() => {
+      window.onmessage = onMessage
+      messages.forEach(window.onmessage)
+    })
+  }
+
+  // FF v102 just started to supports transferable streams, but still needs to ping sw.js
+  // even tough the service worker dose not have to do any kind of work and listen to any
+  // messages... #305
+  keepAlive()
+
+  </script>
+

public/sw.js

@@ -0,0 +1,130 @@
+self.addEventListener('install', () => {
+  self.skipWaiting();
+});
+
+self.addEventListener('activate', event => {
+  event.waitUntil(self.clients.claim());
+});
+
+const map = new Map();
+
+// This should be called once per download
+// Each event has a dataChannel that the data will be piped through
+self.onmessage = event => {
+  // We send a heartbeat every x second to keep the
+  // service worker alive if a transferable stream is not sent
+  if (event.data === 'ping') {
+    return;
+  }
+
+  const data = event.data;
+  const downloadUrl = data.url || self.registration.scope + Math.random() + '/' + (typeof data === 'string' ? data : data.filename);
+  const port = event.ports[0];
+  const metadata = new Array(3); // [stream, data, port]
+
+  metadata[1] = data;
+  metadata[2] = port;
+
+  // Note to self:
+  // old streamsaver v1.2.0 might still use `readableStream`...
+  // but v2.0.0 will always transfer the stream through MessageChannel #94
+  if (event.data.readableStream) {
+    metadata[0] = event.data.readableStream;
+  } else if (event.data.transferringReadable) {
+    port.onmessage = evt => {
+      port.onmessage = null;
+      metadata[0] = evt.data.readableStream;
+    };
+  } else {
+    metadata[0] = createStream(port);
+  }
+
+  map.set(downloadUrl, metadata);
+  port.postMessage({ download: downloadUrl });
+};
+
+function createStream(port) {
+  // ReadableStream is only supported by chrome 52
+  return new ReadableStream({
+    start(controller) {
+      // When we receive data on the messageChannel, we write
+      port.onmessage = ({ data }) => {
+        if (data === 'end') {
+          return controller.close();
+        }
+
+        if (data === 'abort') {
+          controller.error('Aborted the download');
+          return;
+        }
+
+        controller.enqueue(data);
+      };
+    },
+    cancel(reason) {
+      console.log('user aborted', reason);
+      port.postMessage({ abort: true });
+    }
+  });
+}
+
+self.onfetch = event => {
+  const url = event.request.url;
+
+  // this only works for Firefox
+  if (url.endsWith('/ping')) {
+    return event.respondWith(new Response('pong'));
+  }
+
+  const hijacke = map.get(url);
+
+  if (!hijacke) {
+    return null;
+  }
+
+  const [stream, data, port] = hijacke;
+
+  map.delete(url);
+
+  // Not comfortable letting any user control all headers
+  // so we only copy over the length & disposition
+  const responseHeaders = new Headers({
+    'Content-Type': 'application/octet-stream; charset=utf-8',
+
+    // To be on the safe side, The link can be opened in a iframe.
+    // but octet-stream should stop it.
+    'Content-Security-Policy': "default-src 'none'",
+    'X-Content-Security-Policy': "default-src 'none'",
+    'X-WebKit-CSP': "default-src 'none'",
+    'X-XSS-Protection': '1; mode=block',
+    'Cross-Origin-Embedder-Policy': 'require-corp'
+  });
+
+  let headers = new Headers(data.headers || {});
+
+  if (headers.has('Content-Length')) {
+    responseHeaders.set('Content-Length', headers.get('Content-Length'));
+  }
+
+  if (headers.has('Content-Disposition')) {
+    responseHeaders.set('Content-Disposition', headers.get('Content-Disposition'));
+  }
+
+  // data, data.filename and size should not be used anymore
+  if (data.size) {
+    console.warn('Depricated');
+    responseHeaders.set('Content-Length', data.size);
+  }
+
+  let fileName = typeof data === 'string' ? data : data.filename;
+  if (fileName) {
+    console.warn('Depricated');
+    // Make filename RFC5987 compatible
+    fileName = encodeURIComponent(fileName).replace(/['()]/g, escape).replace(/\*/g, '%2A');
+    responseHeaders.set('Content-Disposition', "attachment; filename*=UTF-8''" + fileName);
+  }
+
+  event.respondWith(new Response(stream, { headers: responseHeaders }));
+
+  port.postMessage({ debug: 'Download started' });
+};