[maemo-developers] [maemo-developers] "Smartest" way to start network connection "before" socket connection is attempted to be made

[From: Kalle Valo]

"Tomi Ollila" <tomi.ollila at guru.guru-group.fi> writes:

> In a program I need to know the IP of the interface before doing
> any network connections. 
>
> So far the program has complained 'Please start network connection first'
>
>
> But I'd like to have smarter solution, like do the automatic network
> connection that LD_PRELOAD -trick does but not to connect anywhere.
>
> Does anyone know a good way to achieve this, so that the network connection
> stays alive and closes on request, or when the program exits (unless there
> is someone else using the connection...).

What do you exactly want to do? I didn't get it from your description,
sorry. You want to start the network connection but not connect
anywhere. What do you mean by that?

To answer your question in subject ("Smartest" way to start network
connection "before" socket connection is attempted to be made), I
would say use the IC API. That they you don't have to deal with
sockets at all during the connection establishment.

>From Tomi's second mail:

> Here it is interesting that socket() is wrapped, I would have quessed
> that connect()/sendto() were wrapped; If I'm connecting to 127.0.0.1 why
> open network connection... Or is there some deeper "trickery" involved
> (I sure hope not, as that would make it too unpredictable for application
> programmers).

I don't know the reasons why socket() was chosen. But the connectivity
preload library is just to ease porting of applications to 770,
nothing else. If you are putting more effort on porting than just to
recompile the application, it would be best to use the IC API and not
use the preload library at all.

>From Tomi's third mail:

> Or I just try with osso_socket()... Does osso_close() wrap anything
> or could i just use close() (I will use osso_close, I'm just asking).

One should use osso_close(). osso_socket()/osso_close() do some
bookkeeping and it will get out of sync if osso_close() isn't used.

> btw:s are the strncpy():s in osso-iap-connect.c safe? those doesn't
> ensure that the copied string is null-terminated. Maybe that is not
> needed or the source is always short enough...that kind of usage
> is just always suspicious...

Good catch, it's not safe. I'll fix that. Thanks.

-- 
Kalle Valo