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Pick source address for ICMP errors a bit more intelligently when

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there are multiple addresses on the interface.

From Marc Horowitz <marc@netbsd.org>, who left this sitting for too long.
This commit is contained in:
sommerfeld 2000-01-25 17:07:56 +00:00
parent 3d9809edd8
commit 62224d5f23
1 changed files with 71 additions and 14 deletions
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85
sys/netinet/ip_icmp.c
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@ -1,4 +1,4 @@
/* $NetBSD: ip_icmp.c,v 1.38 1999/07/09 22:57:18 thorpej Exp $ */
/* $NetBSD: ip_icmp.c,v 1.39 2000/01/25 17:07:56 sommerfeld Exp $ */
/*
* Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
@ -125,6 +125,7 @@
#include <netinet/ip.h>
#include <netinet/ip_icmp.h>
#include <netinet/ip_var.h>
#include <netinet/in_pcb.h>
#include <netinet/icmp_var.h>
#ifdef IPSEC
@ -535,6 +536,7 @@ icmp_reflect(m)
register struct ip *ip = mtod(m, struct ip *);
register struct in_ifaddr *ia;
register struct ifaddr *ifa;
struct sockaddr_in *sin = 0;
struct in_addr t;
struct mbuf *opts = 0;
int optlen = (ip->ip_hl << 2) - sizeof(struct ip);
@ -548,51 +550,106 @@ icmp_reflect(m)
t = ip->ip_dst;
ip->ip_dst = ip->ip_src;
/*
* If the incoming packet was addressed directly to us,
* use dst as the src for the reply. Otherwise (broadcast
* or anonymous), use the address which corresponds
* to the incoming interface.
* If the incoming packet was addressed directly to us, use
* dst as the src for the reply. Otherwise (broadcast or
* anonymous), use an address which corresponds to the
* incoming interface, with a preference for the address which
* corresponds to the route to the destination of the ICMP.
*/
/* Look for packet addressed to us */
INADDR_TO_IA(t, ia);
/* look for packet sent to broadcast address */
if (ia == NULL && (m->m_pkthdr.rcvif->if_flags & IFF_BROADCAST)) {
for (ifa = m->m_pkthdr.rcvif->if_addrlist.tqh_first;
ifa != NULL; ifa = ifa->ifa_list.tqe_next) {
if (ifa->ifa_addr->sa_family != AF_INET)
continue;
ia = ifatoia(ifa);
if (in_hosteq(t, ia->ia_broadaddr.sin_addr))
if (in_hosteq(t,ifatoia(ifa)->ia_broadaddr.sin_addr)) {
ia = ifatoia(ifa);
break;
}
}
}
if (ia)
sin = &ia->ia_addr;
icmpdst.sin_addr = t;
if (ia == (struct in_ifaddr *)0)
ia = ifatoia(ifaof_ifpforaddr(sintosa(&icmpdst),
m->m_pkthdr.rcvif));
/* if the packet is addressed somewhere else, compute the
source address for packets routed back to the source, and
use that, if it's an address on the interface which
received the packet */
if (sin == (struct sockaddr_in *)0) {
struct sockaddr_in sin_dst;
struct route icmproute;
int errornum;
sin_dst.sin_family = AF_INET;
sin_dst.sin_len = sizeof(struct sockaddr_in);
sin_dst.sin_addr = ip->ip_dst;
bzero(&icmproute, sizeof(icmproute));
errornum = 0;
sin = in_selectsrc(&sin_dst, &icmproute, 0, NULL, &errornum);
/* errornum is never used */
if (icmproute.ro_rt)
RTFREE(icmproute.ro_rt);
/* check to make sure sin is a source address on rcvif */
if (sin) {
t = sin->sin_addr;
sin = (struct sockaddr_in *)0;
INADDR_TO_IA(t, ia);
while (ia) {
if (ia->ia_ifp == m->m_pkthdr.rcvif) {
sin = &ia->ia_addr;
break;
}
NEXT_IA_WITH_SAME_ADDR(ia);
}
}
}
/* if it was not addressed to us, but the route doesn't go out
the source interface, pick an address on the source
interface. This can happen when routing is asymmetric, or
when the incoming packet was encapsulated */
if (sin == (struct sockaddr_in *)0) {
for (ifa = m->m_pkthdr.rcvif->if_addrlist.tqh_first;
ifa != NULL; ifa = ifa->ifa_list.tqe_next) {
if (ifa->ifa_addr->sa_family != AF_INET)
continue;
sin = &(ifatoia(ifa)->ia_addr);
break;
}
}
/*
* The following happens if the packet was not addressed to us,
* and was received on an interface with no IP address:
* We find the first AF_INET address on the first non-loopback
* interface.
*/
if (ia == (struct in_ifaddr *)0)
if (sin == (struct sockaddr_in *)0)
for (ia = in_ifaddr.tqh_first; ia != NULL;
ia = ia->ia_list.tqe_next) {
if (ia->ia_ifp->if_flags & IFF_LOOPBACK)
continue;
sin = &ia->ia_addr;
break;
}
/*
* If we still didn't find an address, punt. We could have an
* interface up (and receiving packets) with no address.
*/
if (ia == (struct in_ifaddr *)0) {
if (sin == (struct sockaddr_in *)0) {
m_freem(m);
goto done;
}
t = ia->ia_addr.sin_addr;
ip->ip_src = t;
ip->ip_src = sin->sin_addr;
ip->ip_ttl = MAXTTL;
if (optlen > 0) {