[Dnsmasq-discuss] send_ra never sending Router Advertisements

[Simon Kelley]

On 24/09/12 15:47, Kaspar Schleiser wrote:
> Hi,
> 
> Current dnsmasq (tried from 2.62 onwards) doesn't reply to router
> solicits. I think I found the problem.
> 
> This is from radv.c from HEAD (commit 35239a30):
> 
> -------
> 205   parm.other = 0;
> 206   parm.found_context = 0;
> 
> parm.found_context gets initialized here.
> 
> 207   parm.if_name = iface_name;
> 208   parm.first = 1;
> 209
> 210   /* set tag with name == interface */
> 211   iface_id.net = iface_name;
> 212   iface_id.next = NULL;
> 213   parm.tags = &iface_id;
> 214
> 215   for (context = daemon->ra_contexts; context; context = context->next)
> 216     {
> 217       context->flags &= ~CONTEXT_RA_DONE;
> 218       context->netid.next = &context->netid;
> 219     }
> 220
> 221   if (!iface_enumerate(AF_INET6, &parm, add_prefixes) ||
> 222       !parm.found_context)
> 223     return;
> ----
> 
> If parm.found_context is zero, the function just returns.
> iface_enumerate is the only function called, and it doesn't touch
> param.found_context. So send_ra always returns.
> 
> Removing the "!parm.found_context" from that if-statement in line 222
> makes dnsmasq answer to RS again.
> 
> Am I missing something?

Yes. Line 221 passed a pointer to the function add_prefixes() to
iface_enumerate, and iface_enumerate() will call that add_prefixes for
every address of every interface on the system

add_prefixes() does, amongst other things

if (interface_index == param_index)
  for (.... all contexts ....)
   if (<address in on same subnet as context>)
     parm.found_context = 1;



Checking though todays logs on the dogfood test machine, I can see a
DHCPSOLICIT and the corresponding reply.

I'm not saying there isn't a problem, but if there is, it's  More
Complicated Than That.

Cheers,

Simon.