fixes #1005

The upstream gcp aggressively closes the connection once it has
received Content-Length bytes. However the @google-cloud/storage
module doesn't handle this well and emits no event in this case.
We were setting Content-Length because it's slightly more
efficient and was important for our download progress
bar (not anymore). The download should function fine without
setting the Content-Length, and allows the storage stream to finish
before closing the upstream socket.

app/api.js

@@ -162,8 +162,8 @@ function download(id, keychain, onprogress, canceller) {
     });
 
     xhr.addEventListener('progress', function(event) {
-      if (event.lengthComputable && event.target.status === 200) {
+      if (event.target.status === 200) {
-        onprogress([event.loaded, event.total]);
+        onprogress(event.loaded);
       }
     });
     const auth = await keychain.authHeader();
@@ -171,7 +171,7 @@ function download(id, keychain, onprogress, canceller) {
     xhr.setRequestHeader('Authorization', auth);
     xhr.responseType = 'blob';
     xhr.send();
-    onprogress([0, 1]);
+    onprogress(0);
   });
 }
 

app/fileReceiver.js

@@ -47,7 +47,7 @@ export default class FileReceiver extends Nanobus {
     this.fileInfo.name = meta.name;
     this.fileInfo.type = meta.type;
     this.fileInfo.iv = meta.iv;
-    this.fileInfo.size = meta.size;
+    this.fileInfo.size = +meta.size;
     this.state = 'ready';
   }
 
@@ -57,7 +57,7 @@ export default class FileReceiver extends Nanobus {
       this.fileInfo.id,
       this.keychain,
       p => {
-        this.progress = p;
+        this.progress = [p, this.fileInfo.size];
         this.emit('progress');
       }
     );

server/routes/download.js

@@ -6,13 +6,6 @@ module.exports = async function(req, res) {
   const id = req.params.id;
   try {
     const meta = req.meta;
-    const contentLength = await storage.length(id);
-    res.writeHead(200, {
-      'Content-Disposition': 'attachment',
-      'Content-Type': 'application/octet-stream',
-      'Content-Length': contentLength,
-      'WWW-Authenticate': `send-v1 ${req.nonce}`
-    });
     const file_stream = storage.get(id);
     let cancelled = false;
 
@@ -21,7 +14,7 @@ module.exports = async function(req, res) {
       file_stream.destroy();
     });
 
-    file_stream.on('end', async () => {
+    file_stream.pipe(res).on('finish', async () => {
       if (cancelled) {
         return;
       }
@@ -38,8 +31,6 @@ module.exports = async function(req, res) {
         log.info('StorageError:', id);
       }
     });
-
-    file_stream.pipe(res);
   } catch (e) {
     res.sendStatus(404);
   }

server/storage/gcs.js

@@ -13,7 +13,7 @@ class GCSStorage {
   }
 
   getStream(id) {
-    return this.bucket.file(id).createReadStream();
+    return this.bucket.file(id).createReadStream({ validation: false });
   }
 
   set(id, file) {