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Substitute on-link routes' gateways with an all-zero address.

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On OS X, the code in route_loop in route-bsd.c can get a gateway
sockaddr_dl that looks like this:

$1 = {
  sdl_len = 20 '\024',
  sdl_family = 18 '\022',
  sdl_index = 4,
  sdl_type = 6 '\006',
  sdl_nlen = 0 '\0',
  sdl_alen = 0 '\0',
  sdl_slen = 0 '\0',
  sdl_data = '\0' <repeats 11 times>
}

route_loop would throw these out because there's no hardward address
there. This is a routing table entry that indicates that there is no
gateway, and that packets for this particular destination need to go on
interface #4. It corresponds to this type of line from netstat output:

Destination        Gateway            Flags        Refs      Use   Netif Expire
192.168.0          link#4             UCS             2        0     en0

I've changed it so that instead of throwing out the entry, it creates an
all-zero address of the same type as the destination address, which is a
convention used (by Nmap at least) to indicate an on-link route.
This commit is contained in:
david
2012-03-26 22:24:55 +00:00
parent d7af8ff3d0
commit b5c1e83471
1 changed files with 28 additions and 1 deletions
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29
libdnet-stripped/src/route-bsd.c
View File

@@ -217,6 +217,33 @@ route_get(route_t *r, struct route_entry *entry)
}
#if defined(HAVE_SYS_SYSCTL_H) || defined(HAVE_STREAMS_ROUTE) || defined(HAVE_GETKERNINFO)
/* This wrapper around addr_ston, on failure, checks for a gateway address
* family of AF_LINK, and if it finds one, stores an all-zero address of the
* same type as dst. The all-zero address is a convention for same-subnet
* routing table entries. */
static int
addr_ston_gateway(const struct addr *dst,
const struct sockaddr *sa, struct addr *a)
{
int rc;
rc = addr_ston(sa, a);
if (rc == 0)
return rc;
#ifdef HAVE_NET_IF_DL_H
# ifdef AF_LINK
if (sa->sa_family == AF_LINK) {
memset(a, 0, sizeof(*a));
a->addr_type = dst->addr_type;
return (0);
}
# endif
#endif
return (-1);
}
int
route_loop(route_t *r, route_handler callback, void *arg)
{
@@ -301,7 +328,7 @@ route_loop(route_t *r, route_handler callback, void *arg)
/* Need a gateway. */
continue;
sa = NEXTSA(sa);
if (addr_ston(sa, &entry.route_gw) < 0)
if (addr_ston_gateway(&entry.route_dst, sa, &entry.route_gw) < 0)
continue;
if (entry.route_dst.addr_type != entry.route_gw.addr_type ||