Index: src/sbin/ifconfig/ifconfig.c
===================================================================
RCS file: /home/ncvs/src/sbin/ifconfig/ifconfig.c,v
retrieving revision 1.104
diff -u -r1.104 ifconfig.c
--- src/sbin/ifconfig/ifconfig.c	30 Apr 2004 22:34:12 -0000	1.104
+++ src/sbin/ifconfig/ifconfig.c	20 May 2004 16:02:44 -0000
@@ -145,6 +145,9 @@
 void	usage(void);
 void	ifmaybeload(char *name);
 
+static char	*findifname(const char *);
+static void	 parseaddr(const char *, struct sockaddr_dl *);
+
 #ifdef INET6
 void	in6_fillscopeid(struct sockaddr_in6 *sin6);
 int	prefix(void *, int);
@@ -509,6 +512,14 @@
 		if (argc < 1)
 			usage();
 
+		if (!strncmp(*argv, "hw-", 3)) {
+			char *tmp;
+			
+			tmp = findifname(*argv + 3);
+			if (tmp == NULL)
+				errx(1, "no interface with address %s", *argv);
+			*argv = tmp;
+		}
 		strncpy(name, *argv, sizeof(name));
 		argc--, argv++;
 
@@ -1947,3 +1958,57 @@
 	 */
 	printname = 0;
 }
+
+/*
+ * Return the name of the interface with this link-level address, or NULL
+ */
+char *
+findifname(const char *addr)
+{
+	struct ifaddrs *l, *c;
+	struct sockaddr_dl *sdl, templ;
+	char *name;
+	
+	parseaddr(addr, &templ);
+
+	if (getifaddrs(&l) == -1)
+		err(1, "getifaddrs");
+	name = NULL;
+	for (c = l; c != NULL; c = c->ifa_next) {
+		if (c->ifa_addr == NULL || c->ifa_addr->sa_family != AF_LINK)
+			continue;
+		sdl = (struct sockaddr_dl *)c->ifa_addr;
+		if (sdl->sdl_alen == templ.sdl_alen &&
+		    memcmp(sdl->sdl_data + sdl->sdl_nlen,
+		    templ.sdl_data + templ.sdl_nlen,
+		    sdl->sdl_alen) == 0) {
+			name = strdup(c->ifa_name);
+			break;
+		}
+	}
+	freeifaddrs(l);
+	return (name);
+}
+
+/*
+ * Parse the interface address into a sockaddr_dl structure
+ */
+static void
+parseaddr(const char *addr, struct sockaddr_dl *dst)
+{
+	struct sockaddr_dl sdl;
+	struct ether_addr *e;
+
+	/* Init the sockaddr_dl structure */
+	memset(&sdl, 0, sizeof(sdl));
+	sdl.sdl_len = sizeof(sdl);
+	sdl.sdl_family = AF_LINK;
+	sdl.sdl_nlen = 0;
+	e = ether_aton(addr);
+	if (e == NULL)
+		errx(1, "Invalid link-level address format: %s", addr);
+	memcpy(sdl.sdl_data, e, sizeof(*e));
+	sdl.sdl_alen = 6;
+	sdl.sdl_slen = 0;
+	memcpy(dst, &sdl, sizeof(*dst));
+}