dhcpcd-discuss

Hello, Gentlemen.

(Slackware distro of Linux 3.14.x w/grsecurity patches on x86_64 assumed 
for the purposes of this discussion.)

I've been using multi-homed uplink connections at home for many years, 
but up to this point, they've involved statically configured routes that 
are easily managed.

I lost one of those and am trying on "Time Warner Business Cable", for 
better or for worse, but they only seem to offer DHCP.  I didn't think 
too much about it until I went to adapt my scripts, which consist of 
some shell scripts string and duct tape to obtain interface information 
and then configuring the kernel routing and packet marking rules 
according via iproute2.

It worked very well, and allowed me to do some things that seem well out 
of reach of most home users (load balancing to use different uplinks on 
a socket-by-socket basis, auto-failover, binding certain services to use 
a preferred uplink if it's available, etc).

One of the vital bits of information my scripts need is a given link's 
gateway to provide to iproute2's route.  When I use DHCP, it seems 
there's no way I can obtain that information when an already-existing 
default gateway is configured outside of dhcpcd.

I've dumped the lease file and enabled DEBUG logging, to no avail.  All 
I see is a "dummy" localhost gateway and the assigned host IP#.

Is it possible to obtain the details of the offered gateway from the 
exchange, or do I need to look into a patch to provide this?  I'm happy 
to write it, but initial efforts by hammering on nc_route() in ipv4.c 
proved unfruitful. I suspect there's some "editing" of the obtained 
routes in get_routes() in ipv4.c.  I'll look into that logic next, but 
it looks a bit messy and that part of the kernel's structures are 
unfamiliar to me, so it's slower-going than usual.

Thanks,
Malcolm