diff options
author | julian <julian@FreeBSD.org> | 1997-08-22 22:47:27 +0000 |
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committer | julian <julian@FreeBSD.org> | 1997-08-22 22:47:27 +0000 |
commit | 7364436505167cd5254f4433235274a7fab84988 (patch) | |
tree | 4bf71211101f803d948f0a62f0c2192398a38bfa /sys | |
parent | 7623afeb407513ee6db66b683e27014043ee3715 (diff) | |
download | FreeBSD-src-7364436505167cd5254f4433235274a7fab84988.zip FreeBSD-src-7364436505167cd5254f4433235274a7fab84988.tar.gz |
add some comments while trying to understand why appletalk
gets some things wrong.
(part of my continuing "comment it as you understand it" effort :)
Diffstat (limited to 'sys')
-rw-r--r-- | sys/net/if.c | 40 |
1 files changed, 36 insertions, 4 deletions
diff --git a/sys/net/if.c b/sys/net/if.c index f6a99c0..1e40ae9 100644 --- a/sys/net/if.c +++ b/sys/net/if.c @@ -31,7 +31,7 @@ * SUCH DAMAGE. * * @(#)if.c 8.3 (Berkeley) 1/4/94 - * $Id: if.c,v 1.48 1997/05/03 21:07:13 peter Exp $ + * $Id: if.c,v 1.49 1997/07/07 17:36:06 julian Exp $ */ #include <sys/param.h> @@ -235,32 +235,64 @@ ifa_ifwithnet(addr) u_int af = addr->sa_family; char *addr_data = addr->sa_data, *cplim; + /* + * AF_LINK addresses can be looked up directly by their index number, + * so do that if we can. + */ if (af == AF_LINK) { register struct sockaddr_dl *sdl = (struct sockaddr_dl *)addr; if (sdl->sdl_index && sdl->sdl_index <= if_index) return (ifnet_addrs[sdl->sdl_index - 1]); } + + /* + * Scan though each interface, looking for ones that have + * addresses in this address family. + */ for (ifp = ifnet.tqh_first; ifp; ifp = ifp->if_link.tqe_next) { for (ifa = ifp->if_addrhead.tqh_first; ifa; ifa = ifa->ifa_link.tqe_next) { register char *cp, *cp2, *cp3; if (ifa->ifa_addr->sa_family != af) - next: continue; +next: continue; if (ifp->if_flags & IFF_POINTOPOINT) { + /* + * This is a bit broken as it doesn't + * take into account that the remote end may + * be a single node in the network we are + * looking for. + * The trouble is that we don't know the + * netmask for the remote end. + */ if (ifa->ifa_dstaddr != 0 && equal(addr, ifa->ifa_dstaddr)) return (ifa); } else { + /* + * Scan all the bits in the ifa's address. + * If a bit dissagrees with what we are + * looking for, mask it with the netmask + * to see if it really matters. + * (A byte at a time) + */ if (ifa->ifa_netmask == 0) continue; cp = addr_data; cp2 = ifa->ifa_addr->sa_data; cp3 = ifa->ifa_netmask->sa_data; - cplim = ifa->ifa_netmask->sa_len + (char *)ifa->ifa_netmask; + cplim = ifa->ifa_netmask->sa_len + + (char *)ifa->ifa_netmask; while (cp3 < cplim) if ((*cp++ ^ *cp2++) & *cp3++) - goto next; + goto next; /* next address! */ + /* + * If the netmask of what we just found + * is more specific than what we had before + * (if we had one) then remember the new one + * before continuing to search + * for an even better one. + */ if (ifa_maybe == 0 || rn_refines((caddr_t)ifa->ifa_netmask, (caddr_t)ifa_maybe->ifa_netmask)) |