1664059 - Custom user-agent prevents signing in to your Firefox Account

Status: RESOLVED DUPLICATE of bug 1469653

(Cloud Services :: Server: Firefox Accounts, task)

Description

[Mark Hammond [:markh] [:mhammond]]

via bug 1663097, STR:

• Set general.useragent.override to (almost) anything
• Attempt to log in to your account - the login page will "hang"

We were given enough clues by the user in that bug to discover that Firefox Accounts was sending an object over the webchannel rather than a string, which Firefox rejected, preventing the login. Ryan found this code which is probably too lax in deciding when to use a string vs when to use an object - all modern Firefoxes want strings, and this code is only relevant for Firefoxes. I don't think there's any legacy stuff we care about that would want objects, but if there is, that code should be inverted to default to using a string and only use objects for the specific legacy agents that need it.

Note that addons allow user-agent switching, so this isn't purely theoretical.

Comment 1

[Wil Clouser [:clouserw]]

I think this is a duplicate of bug 1469653 so I'll mark it as such. Let me know if I'm wrong please.