FreeLists / openbeosnetteam / [openbeosnetteam] Information about routes and interfaces for protocols

[Oliver Tappe <openbeos@xxxxxxxxxxxxxxx>]

Hi there,

now that a first version of UDP is at least basically working, I'd like to 
continue with filling in some holes in the stack:

UDP needs to know the IP of the outgoing interface when sending data. 
Normally, only IP would determine this (as a result of the routing decision), 
but since UDP requires it, too, I have implemented a workaround that grabs 
the domain (via get_domain()) and then fetches the route for the given 
destination address. Now that UDP knows the route, it can copy over the 
source address from the route. 
This works, but having to fetch the domain and the route from UDP (jumping 
from the transport layer directly into the datalink layer) isn't really nice, 
or am I just being too pedantic, here?
I suspect that BONE is solving this with the get_route() function that is 
missing in our net_protocol_module_info. Axel, given the fact that you left 
that function out, I'm pretty sure there's a good reason for doing so, still 
I wonder if it wouldn't be better to add get_route() to a protocol's module?

Along the same lines: there are instances when IPv4 needs to know the IP 
addresses of the local interfaces, in order to determine whether or not a 
given source/destination IP is indeed of this host. The current 
implementation takes a shortcut (marked as such) and iterates over 
net_domain.interfaces  without locking. I remember Axel mentioning that 
locking isn't thought through yet, so I guess, that's just one incarnation of 
this fact >;o)

In order to fix the problem, we could:
1) Add is_local_address() to net_protocol_module_info and 
   net_datalink_module_info. IPv4 would just delegate the request to the
   datalink module, which could lock the interfaces in it's implementation
   (as it can access the private parts of net_domain).
2) Export locking functions for net_domain (rather ugly)

Any preferences (or other, better ideas) on this?

cheers,
        Oliver