Don't rely on SA_LEN to check whether it's passed a null pointer (it

might be supplied by the OS, and the OS might supply a version that
doesn't check); instead, check for null pointers before doing anything
with the address at all.  This also means we don't supply a netmask if
the address is null; that makes sense, as a netmask makes no sense
without an address.

1 files changed, 34 insertions, 13 deletions

diff --git a/fad-getad.c b/fad-getad.c
index 9c41217..3bbf54a 100644
--- a/fad-getad.c
+++ b/fad-getad.c
@@ -34,7 +34,7 @@
 
 #ifndef lint
 static const char rcsid[] _U_ =
-    "@(#) $Header: /tcpdump/master/libpcap/fad-getad.c,v 1.8 2003-11-15 23:23:58 guy Exp $ (LBL)";
+    "@(#) $Header: /tcpdump/master/libpcap/fad-getad.c,v 1.9 2004-03-11 23:04:24 guy Exp $ (LBL)";
 #endif
 
 #ifdef HAVE_CONFIG_H
@@ -83,14 +83,12 @@ static const char rcsid[] _U_ =
  */
 #ifndef SA_LEN
 #ifdef HAVE_SOCKADDR_SA_LEN
-#define SA_LEN(addr)	(addr ? (addr)->sa_len : 0)
+#define SA_LEN(addr)	((addr)->sa_len)
 #else /* HAVE_SOCKADDR_SA_LEN */
 #ifdef HAVE_SOCKADDR_STORAGE
 static size_t
 get_sa_len(struct sockaddr *addr)
 {
-	if (!addr)
-		return (0);
 	switch (addr->sa_family) {
 
 #ifdef AF_INET
@@ -127,8 +125,8 @@ pcap_findalldevs(pcap_if_t **alldevsp, char *errbuf)
 {
 	pcap_if_t *devlist = NULL;
 	struct ifaddrs *ifap, *ifa;
-	struct sockaddr *broadaddr, *dstaddr;
-	size_t broadaddr_size, dstaddr_size;
+	struct sockaddr *addr, *netmask, *broadaddr, *dstaddr;
+	size_t addr_size, broadaddr_size, dstaddr_size;
 	int ret = 0;
 
 	/*
@@ -162,20 +160,44 @@ pcap_findalldevs(pcap_if_t **alldevsp, char *errbuf)
 		}
 
 		/*
+		 * "ifa_addr" was apparently null on at least one
+		 * interface on some system.
+		 *
 		 * "ifa_broadaddr" may be non-null even on
-		 * non-broadcast interfaces; "ifa_dstaddr"
-		 * was, on at least one FreeBSD 4.1 system,
-		 * non-null on a non-point-to-point
+		 * non-broadcast interfaces, and was null on
+		 * at least one OpenBSD 3.4 system on at least
+		 * one interface with IFF_BROADCAST set.
+		 *
+		 * "ifa_dstaddr" was, on at least one FreeBSD 4.1
+		 * system, non-null on a non-point-to-point
 		 * interface.
+		 *
+		 * Therefore, we supply the address and netmask only
+		 * if "ifa_addr" is non-null (if there's no address,
+		 * there's obviously no netmask), and supply the
+		 * broadcast and destination addresses if the appropriate
+		 * flag is set *and* the appropriate "ifa_" entry doesn't
+		 * evaluate to a null pointer.
 		 */
-		if (ifa->ifa_flags & IFF_BROADCAST) {
+		if (ifa->ifa_addr != NULL) {
+			addr = ifa->ifa_addr;
+			addr_size = SA_LEN(addr);
+			netmask = ifa->ifa_netmask;
+		} else {
+			addr = NULL;
+			addr_size = 0;
+			netmask = NULL;
+		}
+		if (ifa->ifa_flags & IFF_BROADCAST &&
+		    ifa->ifa_broadaddr != NULL) {
 			broadaddr = ifa->ifa_broadaddr;
 			broadaddr_size = SA_LEN(broadaddr);
 		} else {
 			broadaddr = NULL;
 			broadaddr_size = 0;
 		}
-		if (ifa->ifa_flags & IFF_POINTOPOINT) {
+		if (ifa->ifa_flags & IFF_POINTOPOINT &&
+		    ifa->ifa_dstaddr != NULL) {
 			dstaddr = ifa->ifa_dstaddr;
 			dstaddr_size = SA_LEN(ifa->ifa_dstaddr);
 		} else {
@@ -187,8 +209,7 @@ pcap_findalldevs(pcap_if_t **alldevsp, char *errbuf)
 		 * Add information for this address to the list.
 		 */
 		if (add_addr_to_iflist(&devlist, ifa->ifa_name,
-		    ifa->ifa_flags, ifa->ifa_addr, SA_LEN(ifa->ifa_addr),
-		    ifa->ifa_netmask, SA_LEN(ifa->ifa_addr),
+		    ifa->ifa_flags, addr, addr_size, netmask, addr_size,
 		    broadaddr, broadaddr_size, dstaddr, dstaddr_size,
 		    errbuf) < 0) {
 			ret = -1;