1673229 - When network.ftp.enabled is disabled, FF still tries to open FTP links resulting in indefinite number of tabs

Status: RESOLVED DUPLICATE of bug 1667468

(Core Graveyard :: Networking: FTP, defect)

Description

[FirstAirBender]

User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/85.0.4183.83 Safari/537.36/8mqQhSuL-09

Steps to reproduce:

FF Nightly: 84.0a1 (2020-10-22) (64-bit)
OS: Linux ArcoB 5.8.14-arch1-1 #1 SMP PREEMPT Wed, 07 Oct 2020 23:59:46 +0000 x86_64 GNU/Linux

Open about:config and set network.ftp.enabled to false
In preferences, set FF as default program for FTP links
Restart browser
Try opening an FTP link. For example: ftp://ftp.gnu.org/old-gnu/Manuals/glibc-2.2.3/html_chapter/libc_24.html

Actual results:

Firefox starts opening tabs at a rate of 10 tabs per second: Very quick!
Even after closing the browser, it still respawns and keeps opening tabs until I guess a timeout or something makes it stop. All the tabs opened are empty, but it just keeps opening the tabs.

Expected results:

It should either say that FTP is not supported, or disable the option to use FF as the default program for FTP.
Given the fact that we set network.ftp.enabled to false, nothing should have even happened to begin with.

Comment 1

[FirstAirBender]

The behavior is similar to what is reported by https://bugzilla.mozilla.org/show_bug.cgi?id=1667468

---

So (un)suprisingly, after setting network.ftp.enabled to true, and restarting FF, clicking an FTP link actually opens the link inside FF.
What a mess!

Comment 2

[Masatoshi Kimura [:emk]]

I guess Firefox registers itself as the default ftp:// protocol handler somehow. So Firefox tries to open the ftp:// link with an external app, which ends up with launching itself.

If Firefox receives another unknown protocol, it will search the URL with the default search engine instead. I think ftp:// should behave similarly when network.ftp.enabled is false.

Comment 3

[Masatoshi Kimura [:emk]]

Maybe here: https://searchfox.org/mozilla-central/rev/a147181ece866c1ecd176ac49f112785f960aac0/docshell/base/URIFixup.jsm#323-336

~~~We should remove "ftp" from COMMON_PROTOCOLS if network.ftp.enabled is false.~~~

EDIT: it did not work because `externalProtocolService.externalProtocolHandlerExists("ftp")` will return true.

Comment 4

[Masatoshi Kimura [:emk]]

If the URI comes from command line, we should not try to launch an external app to prevent infinite loop.