On 2011/04/24 10:42, Claudio Jeker wrote:
> On Sat, Apr 23, 2011 at 08:58:12PM +0000, Stuart Henderson wrote:
> > On 2011-04-23, Henning Brauer <lists-openbsdpo...@bsws.de> wrote:
> > > * Stuart Henderson <s...@spacehopper.org> [2011-04-23 14:41]:
> > >> Should we do this or should we rethink allowing sockets to be
> > >> bound to broadcast IP addresses?
> > >
> > > i have no idea. and that seems to be common for all of us. i really
> > > dunno. anybody?
> > >
> >
> > Unless there are objections I'll commit my samba diff tomorrow,
> > it can always come out again if anything else changes.
>
> What is this socket used for? You can not send a packet out of that
> socket. I guess it is a UDP socket that should pickup the broadcast hellos
> that flood windows infested networks.
Yes, exactly.
> Our network stack will deliver broadcast datagram to all IP RAW and all
> UDP dgram sockets that match and are bound to 0.0.0.0 or ::.
>
> /*
> * Deliver a multicast or broadcast datagram to *all* sockets
> * for which the local and remote addresses and ports match
> * those of the incoming datagram. This allows more than
> * one process to receive multi/broadcasts on the same port.
>
> Now there is this bit of code in the loop as well:
> if (inp->inp_laddr.s_addr != INADDR_ANY) {
> if (inp->inp_laddr.s_addr != ip->ip_dst.s_addr)
> continue;
> }
>
> So it may make sense to bind to a specific broadcast addr for SOCK_DGRAM
> and SOCK_RAW AF_INET socks. In that case you only receive packets that are
> sent to the network specific broadcast (this does not work for
> packets sent to 255.255.255.255 on that LAN segment)
That would look something like this horror..
Index: in_pcb.c
===================================================================
RCS file: /cvs/src/sys/netinet/in_pcb.c,v
retrieving revision 1.116
diff -u -p -r1.116 in_pcb.c
--- in_pcb.c 19 Apr 2011 03:47:29 -0000 1.116
+++ in_pcb.c 24 Apr 2011 11:31:56 -0000
@@ -276,8 +276,12 @@ in_pcbbind(v, nam, p)
} else if (sin->sin_addr.s_addr != INADDR_ANY) {
sin->sin_port = 0; /* yech... */
if (!(so->so_options & SO_BINDANY) &&
- in_iawithaddr(sin->sin_addr,
- inp->inp_rtableid) == NULL)
+ (ifa_ifwithaddr(sintosa(&sin),
+ inp->inp_rtableid) == NULL) &&
+ (so->so_type != SOCK_DGRAM) &&
+ (so->so_type != SOCK_RAW) &&
+ (in_iawithaddr(sin->sin_addr,
+ inp->inp_rtableid) == NULL))
return (EADDRNOTAVAIL);
}
if (lport) {
