add -F to force replacement of entries with -s and -f

inspired by a diff from Mike Belopuhov <mkb@cvs.hnet.spb.ru>,
these semantics with theo, manpage jaredy jmc and bob, ok bob

2 files changed, 41 insertions, 13 deletions

diff --git a/usr.sbin/arp/arp.8 b/usr.sbin/arp/arp.8
index 128b2be5084..d3b05762689 100644
--- a/usr.sbin/arp/arp.8
+++ b/usr.sbin/arp/arp.8
@@ -1,4 +1,4 @@
-.\"	$OpenBSD: arp.8,v 1.14 2004/07/09 19:54:41 jaredy Exp $
+.\"	$OpenBSD: arp.8,v 1.15 2005/03/29 21:59:59 henning Exp $
 .\"	$NetBSD: arp.8,v 1.7 1995/03/01 11:50:59 chopps Exp $
 .\"
 .\" Copyright (c) 1985, 1991, 1993
@@ -48,10 +48,12 @@
 .Nm arp
 .Fl d a
 .Nm arp
+.Op Fl F
 .Fl s Ar hostname ether_addr
 .Op Cm temp | permanent
 .Op Cm pub
 .Nm arp
+.Op Fl F
 .Fl f Ar filename
 .Sh DESCRIPTION
 The
@@ -85,15 +87,25 @@ flag may be combined with the
 flag to delete all entries, with hostname lookups automatically
 disabled.
 Only the superuser may delete entries.
-.It Fl f Ar filename
+.It Fl F
+Force existing entries for the given host to be overwritten
+(only relevant to the
+.Fl f
+and
+.Fl s
+options).
+.It Fl f
 Process entries from
 .Ar filename
 to be set in the
 .Tn ARP
 tables.
+Any entries in the file that already exist for a given host
+will not be overwritten unless
+.Fl F
+is given.
 Entries in the file should be of the form:
-.Pp
-.Bd -filled -offset indent -compact
+.Bd -filled -offset indent
 .Ar hostname ether_addr
 .Op Cm temp | permanent
 .Op Cm pub
@@ -124,7 +136,11 @@ This behavior has traditionally been called
 Show network addresses as numbers (normally
 .Nm
 attempts to display addresses symbolically).
-.It Fl s Ar hostname ether_addr
+.It Xo
+.Fl s Ar hostname ether_addr
+.Op Cm temp | permanent
+.Op Cm pub
+.Xc
 Create an
 .Tn ARP
 entry for the host called
@@ -139,6 +155,11 @@ The
 or
 .Cm temp
 modifiers may be specified with meanings as given above.
+.Pp
+If the entry already exists for the given host, it will not
+be replaced unless
+.Fl F
+is given.
 .El
 .Sh EXAMPLES
 To view the current
@@ -157,8 +178,7 @@ To create
 .Em proxy ARP
 entries on an interface, fxp0,
 for the IP addresses 204.1.2.3 and 204.1.2.4:
-.Pp
-.Bd -unfilled -offset indent -compact
+.Bd -literal -offset indent
 # arp -s 204.1.2.3 00:90:27:bb:cc:dd pub
 # arp -s 204.1.2.4 00:90:27:bb:cc:dd pub
 .Ed
diff --git a/usr.sbin/arp/arp.c b/usr.sbin/arp/arp.c
index b9218195a85..6686268395e 100644
--- a/usr.sbin/arp/arp.c
+++ b/usr.sbin/arp/arp.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: arp.c,v 1.31 2005/01/04 10:57:23 pascoe Exp $ */
+/*	$OpenBSD: arp.c,v 1.32 2005/03/29 21:59:59 henning Exp $ */
 /*	$NetBSD: arp.c,v 1.12 1995/04/24 13:25:18 cgd Exp $ */
 
 /*
@@ -41,7 +41,7 @@ static char copyright[] =
 
 #ifndef lint
 /*static char sccsid[] = "from: @(#)arp.c	8.2 (Berkeley) 1/2/94";*/
-static char *rcsid = "$OpenBSD: arp.c,v 1.31 2005/01/04 10:57:23 pascoe Exp $";
+static char *rcsid = "$OpenBSD: arp.c,v 1.32 2005/03/29 21:59:59 henning Exp $";
 #endif /* not lint */
 
 /*
@@ -88,6 +88,7 @@ int set(int, char **);
 void usage(void);
 
 static pid_t pid;
+static int replace;	/* replace entries when adding */
 static int nflag;	/* no reverse dns lookups */
 static int aflag;	/* do it for all entries */
 static int s = -1;
@@ -113,7 +114,7 @@ main(int argc, char *argv[])
 	opterr = 0;
 	func = 0;
 
-	while ((ch = getopt(argc, argv, "andsf")) != -1) {
+	while ((ch = getopt(argc, argv, "andSsFf")) != -1) {
 		switch ((char)ch) {
 		case 'a':
 			aflag = 1;
@@ -131,6 +132,9 @@ main(int argc, char *argv[])
 				usage();
 			func = F_SET;
 			break;
+		case 'F':
+			replace = 1;
+			break;
 		case 'f':
 			if (func)
 				usage();
@@ -160,6 +164,8 @@ main(int argc, char *argv[])
 	case F_SET:
 		if (argc < 2 || argc > 5)
 			usage();
+		if (replace)
+			(void)delete(argv[0], NULL);
 		rtn = set(argc, argv) ? 1 : 0;
 		break;
 	case F_DELETE:
@@ -205,6 +211,8 @@ file(char *name)
 			retval = 1;
 			continue;
 		}
+		if (replace)
+			(void)delete(arg[0], NULL);
 		if (set(i, args))
 			retval = 1;
 	}
@@ -459,7 +467,7 @@ print_entry(struct sockaddr_dl *sdl, struct sockaddr_inarp *sin,
 {
 	char *host;
 	struct hostent *hp;
-	char ifname[IF_NAMESIZE];
+	char ifname[IFNAMSIZ];
 
 	if (nflag == 0)
 		hp = gethostbyaddr((caddr_t)&(sin->sin_addr),
@@ -527,8 +535,8 @@ usage(void)
 	(void)fprintf(stderr, "usage: arp -d hostname\n");
 	(void)fprintf(stderr, "usage: arp -d -a\n");
 	(void)fprintf(stderr,
-	    "usage: arp -s hostname ether_addr [temp | permanent] [pub]\n");
-	(void)fprintf(stderr, "usage: arp -f filename\n");
+	    "usage: arp [-F] -s hostname ether_addr [temp | permanent] [pub]\n");
+	(void)fprintf(stderr, "usage: arp [-F] -f filename\n");
 	exit(1);
 }