Module Name: src
Committed By: roy
Date: Thu Jan 23 17:27:35 UTC 2020
Modified Files:
src/sys/netinet: if_arp.c
Log Message:
arp: find source address then target address when processing input
This fixes the case where another host having a duplicate ip address
starts using it right away without probing for it's availability.
While here, prefer ifatoia over a strict cast.
To generate a diff of this commit:
cvs rdiff -u -r1.291 -r1.292 src/sys/netinet/if_arp.c
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/sys/netinet/if_arp.c
diff -u src/sys/netinet/if_arp.c:1.291 src/sys/netinet/if_arp.c:1.292
--- src/sys/netinet/if_arp.c:1.291 Mon Jan 20 18:38:22 2020
+++ src/sys/netinet/if_arp.c Thu Jan 23 17:27:35 2020
@@ -1,4 +1,4 @@
-/* $NetBSD: if_arp.c,v 1.291 2020/01/20 18:38:22 thorpej Exp $ */
+/* $NetBSD: if_arp.c,v 1.292 2020/01/23 17:27:35 roy Exp $ */
/*
* Copyright (c) 1998, 2000, 2008 The NetBSD Foundation, Inc.
@@ -68,7 +68,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: if_arp.c,v 1.291 2020/01/20 18:38:22 thorpej Exp $");
+__KERNEL_RCSID(0, "$NetBSD: if_arp.c,v 1.292 2020/01/23 17:27:35 roy Exp $");
#ifdef _KERNEL_OPT
#include "opt_ddb.h"
@@ -988,7 +988,7 @@ in_arpinput(struct mbuf *m)
struct psref psref, psref_ia;
int s;
char ipbuf[INET_ADDRSTRLEN];
- bool do_dad;
+ bool find_source, do_dad;
if (__predict_false(m_makewritable(&m, 0, m->m_pkthdr.len, M_DONTWAIT)))
goto out;
@@ -1023,11 +1023,20 @@ in_arpinput(struct mbuf *m)
* or any address on the interface to use
* as a dummy address in the rest of this function.
*
- * If the target IP address is zero then try and find
- * the sender address for DAD.
+ * First try and find the source address for early
+ * duplicate address detection.
*/
- myaddr = in_nullhost(itaddr) ? isaddr : itaddr;
+ if (in_nullhost(isaddr)) {
+ if (in_nullhost(itaddr)) /* very bogus ARP */
+ goto out;
+ find_source = false;
+ myaddr = itaddr;
+ } else {
+ find_source = true;
+ myaddr = isaddr;
+ }
s = pserialize_read_enter();
+again:
IN_ADDRHASH_READER_FOREACH(ia, myaddr.s_addr) {
if (!in_hosteq(ia->ia_addr.sin_addr, myaddr))
continue;
@@ -1069,6 +1078,15 @@ in_arpinput(struct mbuf *m)
ifp = bridge_ia->ia_ifp;
}
#endif
+
+ /* If we failed to find the source address then find
+ * the target address. */
+ if (ia == NULL && find_source && !in_nullhost(itaddr)) {
+ find_source = false;
+ myaddr = itaddr;
+ goto again;
+ }
+
if (ia != NULL)
ia4_acquire(ia, &psref_ia);
pserialize_read_exit(s);
@@ -1722,7 +1740,7 @@ done:
static void
arp_dad_duplicated(struct ifaddr *ifa, const struct sockaddr_dl *from)
{
- struct in_ifaddr *ia = (struct in_ifaddr *)ifa;
+ struct in_ifaddr *ia = ifatoia(ifa);
struct ifnet *ifp = ifa->ifa_ifp;
char ipbuf[INET_ADDRSTRLEN], llabuf[LLA_ADDRSTRLEN];
const char *iastr, *llastr;
