1187300 - Verify if interception occurs for channels created by Downloads.jsm when possible

Status: NEW

(Core :: DOM: Service Workers, task, P3)

Description

[José Antonio Olivera Ortega [:jaoo]]

See bug 1182095 comment 6.

Comment 1

[Andrew Overholt [:overholt]]

Let's not block v1 on this but fix it.

Comment 2

[Jens Stutte [:jstutte]]

:annevk, is there an (actionable) gap to the spec here?

Comment 3

[Anne (:annevk)]

Having read through the bug this blocks, it sounds like user-initiated downloads are not intercepted by the service worker. Such downloads can also be paused and resumed at a later time (is that through range requests?).

Downloads are not well-defined by specifications and there's a couple of variants. I'm pretty sure at least some can be intercepted (as they are navigations that turn into downloads) and I think it would be bad if those did not work in Firefox, but Josh's comment seems to suggest they do work.

Non-navigations and resumption seem trickier however:

1. In general range requests are underspecified and have a number of thorny issues that haven't been fully sorted.
2. Executing script in a service worker when no document is open and no permission is given feels wrong. Five years ago this was perhaps more reasonable, but I think our model now ought to be that we do not execute script unless the user is visiting the site (with a notable exception for push notifications, which do require a permission, mind).

Questions:

1. This blocks ServiceWorkers-compat, what sites are breaking and how?
2. What do Chrome and Safari do for downloads? (As per above there's multiple paths to downloads, right click "Save Image As", download="", Content-Disposition, ?; and we should test all.)