From 3cea04d068901c206119ae4debc3f48aa119c6ee Mon Sep 17 00:00:00 2001
From: deraadt <deraadt@openbsd.org>
Date: Fri, 15 Dec 1995 08:08:16 +0000
Subject: [PATCH] from gwr: Check return value from sendrecv so that ARP
 timeout does not cause garbage to be entered into the ARP table.  Also fix
 ARP_DEBUG code.

---
 sys/lib/libsa/arp.c | 46 +++++++++++++++++++++++++--------------------
 1 file changed, 26 insertions(+), 20 deletions(-)

diff --git a/sys/lib/libsa/arp.c b/sys/lib/libsa/arp.c
index de09484106b..f9c5c95e7be 100644
--- a/sys/lib/libsa/arp.c
+++ b/sys/lib/libsa/arp.c
@@ -1,4 +1,4 @@
-/*	$NetBSD: arp.c,v 1.12 1995/09/27 23:14:57 pk Exp $	*/
+/*	$NetBSD: arp.c,v 1.13 1995/12/08 04:12:53 gwr Exp $	*/
 
 /*
  * Copyright (c) 1992 Regents of the University of California.
@@ -55,14 +55,14 @@
 /* Cache stuff */
 #define ARP_NUM 8			/* need at most 3 arp entries */
 
-static struct arp_list {
+struct arp_list {
 	struct in_addr	addr;
 	u_char		ea[6];
 } arp_list[ARP_NUM] = {
 	/* XXX - net order `INADDR_BROADCAST' must be a constant */
 	{ {0xffffffff}, BA }
 };
-static	int arp_num = 1;
+int arp_num = 1;
 
 /* Local forwards */
 static	ssize_t arpsend __P((struct iodesc *, void *, size_t));
@@ -78,36 +78,34 @@ arpwhohas(d, addr)
 	register struct ether_arp *ah;
 	register struct arp_list *al;
 	struct {
-		u_char header[ETHER_SIZE];
+		struct ether_header eh;
 		struct {
 			struct ether_arp arp;
-			u_char pad[18]; 	/* 60 - sizeof(arp) */
+			u_char pad[18]; 	/* 60 - sizeof(...) */
 		} data;
 	} wbuf;
 	struct {
-		u_char header[ETHER_SIZE];
+		struct ether_header eh;
 		struct {
 			struct ether_arp arp;
 			u_char pad[24]; 	/* extra space */
 		} data;
 	} rbuf;
 
-#ifdef ARP_DEBUG
- 	if (debug)
- 	    printf("arpwhohas: called for %s\n", inet_ntoa(addr));
-#endif
 	/* Try for cached answer first */
 	for (i = 0, al = arp_list; i < arp_num; ++i, ++al)
 		if (addr.s_addr == al->addr.s_addr)
 			return (al->ea);
 
 	/* Don't overflow cache */
-	if (arp_num > ARP_NUM - 1)
-		panic("arpwhohas: overflowed arp_list!");
+	if (arp_num > ARP_NUM - 1) {
+		arp_num = 1;	/* recycle */
+		printf("arpwhohas: overflowed arp_list!\n");
+	}
 
 #ifdef ARP_DEBUG
  	if (debug)
-		printf("arpwhohas: not cached\n");
+ 	    printf("arpwhohas: send request for %s\n", inet_ntoa(addr));
 #endif
 
 	bzero((char*)&wbuf.data, sizeof(wbuf.data));
@@ -119,22 +117,30 @@ arpwhohas(d, addr)
 	ah->arp_op = htons(ARPOP_REQUEST);
 	MACPY(d->myea, ah->arp_sha);
 	bcopy(&d->myip, ah->arp_spa, sizeof(ah->arp_spa));
+	/* Leave zeros in arp_tha */
 	bcopy(&addr, ah->arp_tpa, sizeof(ah->arp_tpa));
 
-	/* Store ip address in cache */
+	/* Store ip address in cache (incomplete entry). */
 	al->addr = addr;
 
-	(void)sendrecv(d,
+	i = sendrecv(d,
 	    arpsend, &wbuf.data, sizeof(wbuf.data),
 	    arprecv, &rbuf.data, sizeof(rbuf.data));
+	if (i == -1) {
+		panic("arp: no response for %s\n",
+			  inet_ntoa(addr));
+	}
 
 	/* Store ethernet address in cache */
 	ah = &rbuf.data.arp;
 #ifdef ARP_DEBUG
- 	if (debug)
+ 	if (debug) {
+		printf("arp: response from %s\n",
+			   ether_sprintf(rbuf.eh.ether_shost));
 		printf("arp: cacheing %s --> %s\n",
-			   intoa(ah->arp_spa),
+			   inet_ntoa(addr),
 			   ether_sprintf(ah->arp_sha));
+	}
 #endif
 	MACPY(ah->arp_sha, al->ea);
 	++arp_num;
@@ -205,7 +211,7 @@ arprecv(d, pkt, len, tleft)
 	{
 #ifdef ARP_DEBUG
 		if (debug)
-			printf("bad hrd/pro/hln/pln\n")
+			printf("bad hrd/pro/hln/pln\n");
 #endif
 		return (-1);
 	}
@@ -213,7 +219,7 @@ arprecv(d, pkt, len, tleft)
 	if (ah->arp_op == htons(ARPOP_REQUEST)) {
 #ifdef ARP_DEBUG
 		if (debug)
-			printf("is request\n")
+			printf("is request\n");
 #endif
 		arp_reply(d, ah);
 		return (-1);
@@ -265,7 +271,7 @@ arp_reply(d, pkt)
 	{
 #ifdef ARP_DEBUG
 		if (debug)
-			printf("arp_reply: bad hrd/pro/hln/pln\n")
+			printf("arp_reply: bad hrd/pro/hln/pln\n");
 #endif
 		return;
 	}
-- 
2.20.1