1579331 - URL constructor fails when input is a data URL without a comma

Status: RESOLVED FIXED

(Core :: DOM: Core & HTML, defect, P2)

Description

[Kagami Rosylight [:saschanaz] (they/them) (inactive until 2025-11-14)]

new URL("data:foo");

All Chrome, Edge, and Safari successfully can create a URL instance but Firefox fails to do so.

I suspect this should be a duplicate but couldn't find any existing relevant bug.

Comment 1

[Marcos Caceres [:marcosc]]

Anne, Baku, wdyt?

Comment 2

[Andrea Marchesini [:baku]]

In URL API, we call NS_NewURI() and this returns an error when parsing data:foo.
See: https://searchfox.org/mozilla-central/rev/2c0a60b5b065ae0fdfcfae168141e82b834fb2d4/dom/url/URL.cpp#68

Because the URL doesn't contain a comma, we return NS_ERROR_MALFORMED_URI:
https://searchfox.org/mozilla-central/rev/2c0a60b5b065ae0fdfcfae168141e82b834fb2d4/netwerk/protocol/data/nsDataHandler.cpp#159

Valentin is on PTO. Dragana, who can take a look whether this is a bug in our data: URL parser?

Comment 3

[Robert Longson [:longsonr]]

Doesn't seem like the comma is optional according to https://tools.ietf.org/html/rfc2397, which says it's

data:[<mediatype>][;base64],<data>

and wikipedia says

The comma is required in a data URI, even when the data part has zero length.

Comment 4

[Kagami Rosylight [:saschanaz] (they/them) (inactive until 2025-11-14)]

The URL standard doesn't seem to reference RFC 2397 nor require a valid data URI.

Edit: There are several relevant WPT test failures https://searchfox.org/mozilla-central/rev/2c0a60b5b065ae0fdfcfae168141e82b834fb2d4/testing/web-platform/meta/url/url-constructor.html.ini

Comment 5

[Anne (:annevk)]

Yeah, this is a bug in Firefox not using a compliant URL parser (one that covers all schemes and does not dispatch on a per-scheme basis).

Comment 6

[Andrea Marchesini [:baku]]

Valentin, do you have time to take a look?

Comment 7

[Valentin Gosu [:valentin] (he/him)]

The fix seems simple enough.

Comment 8

[Valentin Gosu [:valentin] (he/him)]

Attachment: Bug 1579331 - URL constructor fails when input is a data URL without a comma r=baku

Comment 9

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/d0fb6559c22e
URL constructor fails when input is a data URL without a comma r=baku

Comment 10

[Noemi Erli[:noemi_erli]]

Backed out changeset d0fb6559c22e (Bug 1579331) for failing in browser_contextmenu.js CLOSED TREE

Push with failure: https://treeherder.mozilla.org/#/jobs?repo=autoland&selectedJob=266141844&resultStatus=testfailed%2Cbusted%2Cexception&revision=d0fb6559c22ec8cbe5f4eeb15ebbaa549fb3e106

Failure log: https://treeherder.mozilla.org/logviewer.html#/jobs?job_id=266141844&repo=autoland&lineNumber=2882

Backout: https://hg.mozilla.org/integration/autoland/rev/5b2288a607cb020a24ccc3f8be0469b2007dd742

Comment 11

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/db3536d46c35
URL constructor fails when input is a data URL without a comma r=baku

Comment 12

[Natalia Csoregi [:nataliaCs]]

https://hg.mozilla.org/mozilla-central/rev/db3536d46c35