So... I have some (very limited) progress in getting WISPr authentication working against a BTWiFi hotspot. My first forays with the simple client scripts resulted in some not-very-helpful errors, and it was only when I tried a third perl client that it became clear that I was going to need quite a handful of perl modules to get past detecting the WISPr redirect and actually submit credentials over HTTPS.

After some messing about with CPAN to install XML::Simple and Crypt::SSLeay plus dependencies (libssl-dev needed before you start, plus some familiarity with CPAN advised) I was able to get the client to make an HTTP request, intercept the WISPr redirect, submit my login credentials... and receive "Login failed (Access REJECT)" for pretty much anything I tried.

Documentation on WISPr is pretty scant, but from reading the sources of other clients I suspected that I would need to prefix or suffix my login credentials with a string to indicate that I'm a FON customer as opposed to BTOpenzone or whatever. I'd tried prefixing with FON/ and suffixing with @fon, both without success, when I found (from the source code of the Android WISPr client) that the network prefix seems to be BTFON, so BTFON/user@email.tld as username.

And, lo and behold, it worked! Login succeeded (Access ACCEPT), plus a LogoffURL to call when we want to close the connection. And I can ping Google, so we're online.

So, if nothing else, this confirms that a WISPr login using FON credentials on a BTWiFi hotspot is possible; it should be pretty simple to make this fire automatically from DBUS although I need to figure out exactly which SSIDs it works with, and possibly how to supply credentials to/from other service providers.

There's a glaring vacancy for a WISPr client application for the N900, whether it's based on that bit of perl or not. Android has it, iPhone has it, BTWiFi supports it, I'm surprised that I could find no standard Linux clients for it and no adaptations for the N900. Hopefully, the more networks and the more sets of login credentials this works with, the more reason there is for someone to throw together an implementation of some kind.

More to follow, if I make any further headway with it...