1193128 - data URIs are not handled correctly by fetch()

Status: RESOLVED FIXED

(Core :: DOM: Service Workers, defect)

Description

[Seth Fowler [:seth] [:s2h]]

There appears to be a bug in the implementation of fetch for data URIs. I discovered it when trying to fix a bug in test_fetch_event.html. If I replace the code for "nonexistent_image.gif" with this:

> else if (ev.request.url.includes("nonexistent_image.gif")) {
>   ev.respondWith(
>     fetch(new Request("data:image/gif;base64,R0lGODlhAQABAPAAAP8AAAAAACH5BAAAAAAALAAAAAABAAEAAAICRAEAOw%3D%3D")));
> }

Then the test fails. Logging the response body from ImageLib, I see that we're just getting "R0lGODlhAQABAP..." as the response body - in other words, the data URI's data is not being properly decoded.

It looks to me like the problem lies here:

https://dxr.mozilla.org/mozilla-central/source/dom/fetch/FetchDriver.cpp#284

I think this code is assuming that nsDataHandler::ParseURI decoded |dataBuffer|, but it looks like ParseURI doesn't do that - it just splits the data URI into parts. We probably need to apply base64 decoding (and possibly URI decoding) manually.

Comment 1

[Ben Kelly [:bkelly, not reviewing]]

We shipped fetch in 39, so this is probably an issue as far back as that.

Comment 2

[Nikhil Marathe [:nsm] (No longer reading bugmail, please needinfo?)]

Attachment: MozReview Request: Bug 1193128 - Fix base64 decoding when fetching data URIs. r?baku

Bug 1193128 - Fix base64 decoding when fetching data URIs. r?baku

Comment 3

[Andrea Marchesini [:baku]]

Comment on attachment 8647703 [details]
MozReview Request: Bug 1193128 - Fix base64 decoding when fetching data URIs. r?baku

https://reviewboard.mozilla.org/r/16035/#review15113

Ship It!

::: dom/fetch/FetchDriver.cpp:284
(Diff revision 1)
> +      if (NS_SUCCEEDED(channel->GetContentType(contentType))) {

would be nice to have a:

NS_WARN_IF_NOT(...)

Comment 4

[Nikhil Marathe [:nsm] (No longer reading bugmail, please needinfo?)]

url:        https://hg.mozilla.org/integration/mozilla-inbound/rev/4d96f2d4807728039747d701d766b67108d96968
changeset:  4d96f2d4807728039747d701d766b67108d96968
user:       Nikhil Marathe <[e-mail]>
date:       Thu Aug 13 13:08:43 2015 -0700
description:
Bug 1193128 - Fix base64 decoding when fetching data URIs. r=baku

Comment 5

[Nikhil Marathe [:nsm] (No longer reading bugmail, please needinfo?)]

https://treeherder.mozilla.org/#/jobs?repo=try&revision=e8c021affdcc

Comment 6

[Nikhil Marathe [:nsm] (No longer reading bugmail, please needinfo?)]

url:        https://hg.mozilla.org/integration/mozilla-inbound/rev/af97951b7f1d68fd60255dc5211206b66a3d0676
changeset:  af97951b7f1d68fd60255dc5211206b66a3d0676
user:       Nikhil Marathe <[e-mail]>
date:       Thu Aug 13 13:08:43 2015 -0700
description:
Bug 1193128 - Fix base64 decoding when fetching data URIs. r=baku

Comment 7

[Ryan VanderMeulen [:RyanVM]]

https://hg.mozilla.org/mozilla-central/rev/af97951b7f1d