From: Ted Lemon <source@isc.org>
Date: Mon, 12 Jan 1998 01:00:42 +0000 (+0000)
Subject: Handle ICMP packets with IP header options correctly.
X-Git-Tag: carrel-2~202
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=0a8ee595f1df3ae2c43c74f5988f12251561cfa7;p=thirdparty%2Fdhcp.git

Handle ICMP packets with IP header options correctly.
---

diff --git a/common/icmp.c b/common/icmp.c
index 590828426..c3c357c04 100644
--- a/common/icmp.c
+++ b/common/icmp.c
@@ -43,7 +43,7 @@
 
 #ifndef lint
 static char copyright[] =
-"$Id: icmp.c,v 1.7 1997/06/04 20:59:40 mellon Exp $ Copyright (c) 1997 The Internet Software Consortium.  All rights reserved.\n";
+"$Id: icmp.c,v 1.8 1998/01/12 01:00:42 mellon Exp $ Copyright (c) 1997 The Internet Software Consortium.  All rights reserved.\n";
 #endif /* not lint */
 
 #include "dhcpd.h"
@@ -135,10 +135,11 @@ void icmp_echoreply (protocol)
 	struct protocol *protocol;
 {
 	struct icmp *icfrom;
+	struct ip *ip;
 	struct sockaddr_in from;
 	unsigned char icbuf [1500];
 	int status;
-	int len;
+	int len, hlen;
 	struct iaddr ia;
 	void (*handler) PROTO ((struct iaddr, u_int8_t *, int));
 
@@ -150,13 +151,17 @@ void icmp_echoreply (protocol)
 		return;
 	}
 
-	/* Probably not for us. */
-	if (status < (sizeof (struct ip)) + (sizeof *icfrom)) {
+	/* Find the IP header length... */
+	ip = (struct ip *)icbuf;
+	hlen = ip -> ip_hl << 2;
+
+	/* Short packet? */
+	if (status < hlen + (sizeof *icfrom)) {
 		return;
 	}
 
-	len = status - sizeof (struct ip);
-	icfrom = (struct icmp *)(icbuf + sizeof (struct ip));
+	len = status - hlen;
+	icfrom = (struct icmp *)(icbuf + hlen);
 
 	/* Silently discard ICMP packets that aren't echoreplies. */
 	if (icfrom -> icmp_type != ICMP_ECHOREPLY) {