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From: karels%okeeffe@UCBVAX.BERKELEY.EDU (Mike Karels)
Newsgroups: comp.protocols.tcp-ip
Subject: Re: IP options
Message-ID: <8709092006.AA09597@okeeffe.Berkeley.EDU>
Date: Wed, 9-Sep-87 16:06:30 EDT
Article-I.D.: okeeffe.8709092006.AA09597
Posted: Wed Sep  9 16:06:30 1987
Date-Received: Fri, 11-Sep-87 05:31:56 EDT
References: <423@root44.co.uk>
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The ARPA Internet
Lines: 144

As a matter of fact, there are a few oddities in the IP options code
in 4.3.  Of the two you mentioned, one is a bug (record route used
a garbage address which coincidentally works on machines with default
routes).  You appear to have misunderstood the code for source route,
though; look for the call to ip_rtaddr, which locates the outgoing
interface address.  The other bug of any interest was in IP timestamp
handling.  Here is a set of diffs to fix the record route bug and
several other minor things.

		Mike

*** /nbsd/usr/src/sys/netinet/ip_input.c	Thu Jun  5 00:28:15 1986
--- ./ip_input.c	Wed Sep  9 11:33:47 1987
***************
*** 5,7 ****
   *
!  *	@(#)ip_input.c	7.1 (Berkeley) 6/5/86
   */
--- 5,7 ----
   *
!  *	@(#)ip_input.c	7.6.1.1 (Berkeley) 9/9/87
   */
***************
*** 302,304 ****
  	if (fp == 0) {
! 		if ((t = m_get(M_WAIT, MT_FTABLE)) == NULL)
  			goto dropfrag;
--- 302,304 ----
  	if (fp == 0) {
! 		if ((t = m_get(M_DONTWAIT, MT_FTABLE)) == NULL)
  			goto dropfrag;
***************
*** 490,491 ****
--- 490,492 ----
  
+ extern struct in_ifaddr *ifptoia();
  struct in_ifaddr *ip_rtaddr();
***************
*** 595,597 ****
  				break;
! 			bcopy((caddr_t)(cp + off), (caddr_t)&ipaddr.sin_addr,
  			    sizeof(ipaddr.sin_addr));
--- 596,598 ----
  				break;
! 			bcopy((caddr_t)(&ip->ip_dst), (caddr_t)&ipaddr.sin_addr,
  			    sizeof(ipaddr.sin_addr));
***************
*** 602,604 ****
  				type = ICMP_UNREACH;
! 				code = ICMP_UNREACH_SRCFAIL;
  				goto bad;
--- 603,605 ----
  				type = ICMP_UNREACH;
! 				code = ICMP_UNREACH_HOST;
  				goto bad;
***************
*** 620,622 ****
  			}
! 			sin = (struct in_addr *)(cp+cp[IPOPT_OFFSET]-1);
  			switch (ipt->ipt_flg) {
--- 621,623 ----
  			}
! 			sin = (struct in_addr *)(cp + ipt->ipt_ptr - 1);
  			switch (ipt->ipt_flg) {
***************
*** 630,636 ****
  					goto bad;
! 				if (in_ifaddr == 0)
! 					goto bad;	/* ??? */
! 				bcopy((caddr_t)&IA_SIN(in_ifaddr)->sin_addr,
  				    (caddr_t)sin, sizeof(struct in_addr));
! 				sin++;
  				break;
--- 631,636 ----
  					goto bad;
! 				ia = ifptoia(ifp);
! 				bcopy((caddr_t)&IA_SIN(ia)->sin_addr,
  				    (caddr_t)sin, sizeof(struct in_addr));
! 				ipt->ipt_ptr += sizeof(struct in_addr);
  				break;
***************
*** 638,639 ****
--- 638,642 ----
  			case IPOPT_TS_PRESPEC:
+ 				if (ipt->ipt_ptr + sizeof(n_time) +
+ 				    sizeof(struct in_addr) > ipt->ipt_len)
+ 					goto bad;
  				bcopy((caddr_t)sin, (caddr_t)&ipaddr.sin_addr,
***************
*** 642,646 ****
  					continue;
- 				if (ipt->ipt_ptr + sizeof(n_time) +
- 				    sizeof(struct in_addr) > ipt->ipt_len)
- 					goto bad;
  				ipt->ipt_ptr += sizeof(struct in_addr);
--- 645,646 ----
***************
*** 652,654 ****
  			ntime = iptime();
! 			bcopy((caddr_t)&ntime, (caddr_t)sin, sizeof(n_time));
  			ipt->ipt_ptr += sizeof(n_time);
--- 652,655 ----
  			ntime = iptime();
! 			bcopy((caddr_t)&ntime, (caddr_t)cp + ipt->ipt_ptr - 1,
! 			    sizeof(n_time));
  			ipt->ipt_ptr += sizeof(n_time);
***************
*** 731,733 ****
  		return ((struct mbuf *)0);
! 	m = m_get(M_WAIT, MT_SOOPTS);
  	m->m_len = ip_nhops * sizeof(struct in_addr) + IPOPT_OFFSET + 1 + 1;
--- 732,736 ----
  		return ((struct mbuf *)0);
! 	m = m_get(M_DONTWAIT, MT_SOOPTS);
! 	if (m == 0)
! 		return ((struct mbuf *)0);
  	m->m_len = ip_nhops * sizeof(struct in_addr) + IPOPT_OFFSET + 1 + 1;
***************
*** 841,843 ****
  	}
! 	if (ip->ip_ttl < IPTTLDEC) {
  		type = ICMP_TIMXCEED, code = ICMP_TIMXCEED_INTRANS;
--- 844,846 ----
  	}
! 	if (ip->ip_ttl <= IPTTLDEC) {
  		type = ICMP_TIMXCEED, code = ICMP_TIMXCEED_INTRANS;
***************
*** 870,873 ****
--- 873,881 ----
  	 * and if packet was not source routed (or has any options).
+ 	 * Also, don't send redirect if forwarding using a default route
+ 	 * or a route modfied by a redirect.
  	 */
+ #define	satosin(sa)	((struct sockaddr_in *)(sa))
  	if (ipforward_rt.ro_rt && ipforward_rt.ro_rt->rt_ifp == ifp &&
+ 	    (ipforward_rt.ro_rt->rt_flags & (RTF_DYNAMIC|RTF_MODIFIED)) == 0 &&
+ 	    satosin(&ipforward_rt.ro_rt->rt_dst)->sin_addr.s_addr != 0 &&
  	    ipsendredirects && ip->ip_hl == (sizeof(struct ip) >> 2)) {
***************
*** 874,876 ****
  		struct in_ifaddr *ia;
- 		extern struct in_ifaddr *ifptoia();
  		u_long src = ntohl(ip->ip_src.s_addr);
--- 882,883 ----