text: #include <machine/rtems-bsd-kernel-space.h>
  
  /*
   * Copyright (c) 1982, 1986, 1988, 1993
   *	The Regents of the University of California.  All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in the
   *    documentation and/or other materials provided with the distribution.
   * 4. Neither the name of the University nor the names of its contributors
   *    may be used to endorse or promote products derived from this software
   *    without specific prior written permission.
   *
   * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   * SUCH DAMAGE.
   *
   *	@(#)ip_input.c	8.2 (Berkeley) 1/4/94
   *	$ANA: ip_input.c,v 1.5 1996/09/18 14:34:59 wollman Exp $
   */
  
  #ifdef HAVE_CONFIG_H
  #include "config.h"
  #endif
  
  #define	_IP_VHL
  
  #include "opt_ipfw.h"
  
  #include <stddef.h>
  #include <inttypes.h>
  
  #include <sys/param.h>
  #include <sys/systm.h>
  #include <sys/mbuf.h>
  #include <sys/malloc.h>
  #include <sys/domain.h>
  #include <sys/protosw.h>
  #include <sys/socket.h>
  #include <errno.h>
  #include <sys/time.h>
  #include <sys/kernel.h>
  #include <sys/syslog.h>
  #include <sys/sysctl.h>
  
  #include <net/if.h>
  #include <net/if_dl.h>
  #include <net/route.h>
  #include <net/netisr.h>
  
  #include <netinet/in.h>
  #include <rtems/rtems_netinet_in.h>
  #include <netinet/in_systm.h>
  #include <netinet/in_var.h>
  #include <netinet/ip.h>
  #include <netinet/in_pcb.h>
  #include <netinet/ip_var.h>
  #include <netinet/ip_icmp.h>
  #include <machine/in_cksum.h>
  
  #include <sys/socketvar.h>
  
  #ifdef IPFIREWALL
  #include <netinet/ip_fw.h>
  #endif
  
  int rsvp_on = 0;
  static int ip_rsvp_on;
  struct socket *ip_rsvpd;
  
  int	ipforwarding = 0;
  SYSCTL_INT(_net_inet_ip, IPCTL_FORWARDING, forwarding, CTLFLAG_RW,
      &ipforwarding, 0, "Enable IP forwarding between interfaces");
  
  static int	ipsendredirects = 1; /* XXX */
  SYSCTL_INT(_net_inet_ip, IPCTL_SENDREDIRECTS, redirect, CTLFLAG_RW,
      &ipsendredirects, 0, "Enable sending IP redirects");
  
  int	ip_defttl = IPDEFTTL;
  SYSCTL_INT(_net_inet_ip, IPCTL_DEFTTL, ttl, CTLFLAG_RW,
      &ip_defttl, 0, "Maximum TTL on IP packets");
  
  static int	ip_dosourceroute = 0;
  SYSCTL_INT(_net_inet_ip, IPCTL_SOURCEROUTE, sourceroute, CTLFLAG_RW,
  	&ip_dosourceroute, 0, "");
  
  static int	ip_acceptsourceroute = 0;
  SYSCTL_INT(_net_inet_ip, IPCTL_ACCEPTSOURCEROUTE, accept_sourceroute,
  	CTLFLAG_RW, &ip_acceptsourceroute, 0, "");
  #ifdef DIAGNOSTIC
  static int	ipprintfs = 0;
  #endif
  
  extern	struct domain inetdomain;
  extern	struct protosw inetsw[];
  u_char	ip_protox[IPPROTO_MAX];
  static int	ipqmaxlen = IFQ_MAXLEN;
  struct	in_ifaddr *in_ifaddr;			/* first inet address */
  struct	ifqueue ipintrq;
  SYSCTL_INT(_net_inet_ip, IPCTL_INTRQMAXLEN, intr_queue_maxlen, CTLFLAG_RD,
  	&ipintrq.ifq_maxlen, 0, "");
  SYSCTL_INT(_net_inet_ip, IPCTL_INTRQDROPS, intr_queue_drops, CTLFLAG_RD,
      &ipintrq.ifq_drops, 0,
      "Number of packets dropped from the IP input queue");
  
  struct ipstat ipstat;
  
  /* Packet reassembly stuff */
  #define IPREASS_NHASH_LOG2      6
  #define IPREASS_NHASH           (1 << IPREASS_NHASH_LOG2)
  #define IPREASS_HMASK           (IPREASS_NHASH - 1)
  #define IPREASS_HASH(x,y) \
  	(((((x) & 0xF) | ((((x) >> 8) & 0xF) << 4)) ^ (y)) & IPREASS_HMASK)
  
  static struct ipq ipq[IPREASS_NHASH];
  static int    nipq = 0;         /* total # of reass queues */
  static int    maxnipq;
  
  #ifdef IPCTL_DEFMTU
  SYSCTL_INT(_net_inet_ip, IPCTL_DEFMTU, mtu, CTLFLAG_RW,
      &ip_mtu, 0, "Default MTU");
  #endif
  
  #if !defined(COMPAT_IPFW) || COMPAT_IPFW == 1
  #undef COMPAT_IPFW
  #define COMPAT_IPFW 1
  #else
  #undef COMPAT_IPFW
  #endif
  
  #ifdef COMPAT_IPFW
  /* Firewall hooks */
  ip_fw_chk_t *ip_fw_chk_ptr;
  ip_fw_ctl_t *ip_fw_ctl_ptr;
  
  /* IP Network Address Translation (NAT) hooks */ 
  ip_nat_t *ip_nat_ptr;
  ip_nat_ctl_t *ip_nat_ctl_ptr;
  #endif
  
  /*
   * We need to save the IP options in case a protocol wants to respond
   * to an incoming packet over the same route if the packet got here
   * using IP source routing.  This allows connection establishment and
   * maintenance when the remote end is on a network that is not known
   * to us.
   */
  static int	ip_nhops = 0;
  static	struct ip_srcrt {
  	struct	in_addr dst;			/* final destination */
  	char	nop;				/* one NOP to align */
  	char	srcopt[IPOPT_OFFSET + 1];	/* OPTVAL, OLEN and OFFSET */
  	struct	in_addr route[MAX_IPOPTLEN/sizeof(struct in_addr)];
  } ip_srcrt;
  
  #ifdef IPDIVERT
  /*
   * Shared variable between ip_input() and ip_reass() to communicate
   * about which packets, once assembled from fragments, get diverted,
   * and to which port.
   */
  static u_short	frag_divert_port;
  #endif
  
  static void save_rte(u_char *, struct in_addr);
  static void	 ip_deq(struct ipasfrag *);
  static int	 ip_dooptions(struct mbuf *);
  static void	 ip_enq(struct ipasfrag *, struct ipasfrag *);
  static void	 ip_forward(struct mbuf *, int);
  static void	 ip_freef(struct ipq *);
  static struct ip *
  	 ip_reass(struct ipasfrag *, struct ipq *, struct ipq *);
  static struct in_ifaddr *
  	 ip_rtaddr(struct in_addr);
  void	ipintr(void);
  /*
   * IP initialization: fill in IP protocol switch table.
   * All protocols not implemented in kernel go to raw IP protocol handler.
   */
  void
  ip_init(void)
  {
  	register struct protosw *pr;
  	register int i;
  
  	pr = pffindproto(PF_INET, IPPROTO_RAW, SOCK_RAW);
  	if (pr == NULL)
  		panic("ip_init: PF_INET not found");
  
  	/* Initialize the entire ip_protox[] array to IPPROTO_RAW. */
  	for (i = 0; i < IPPROTO_MAX; i++)
  		ip_protox[i] = pr - inetsw;
  	/*
  	 * Cycle through IP protocols and put them into the appropriate place
  	 * in ip_protox[].
  	 */
  	for (pr = inetdomain.dom_protosw;
  	    pr < inetdomain.dom_protoswNPROTOSW; pr++)
  		if (pr->pr_domain->dom_family == PF_INET &&
  		    pr->pr_protocol && pr->pr_protocol != IPPROTO_RAW) {
  			ip_protox[pr->pr_protocol] = pr - inetsw;
  		}
  
  	for (i = 0; i < IPREASS_NHASH; i++)
  	    ipq[i].next = ipq[i].prev = &ipq[i];
  
  	maxnipq = nmbclusters/4;
  
  	/* Initialize various other remaining things. */
  	ip_id = rtems_bsdnet_seconds_since_boot() & 0xffff;
  	ipintrq.ifq_maxlen = ipqmaxlen;
  #ifdef IPFIREWALL
  	ip_fw_init();
  #endif
  #ifdef IPNAT
          ip_nat_init(); 
  #endif
  
  }
  
  static struct	sockaddr_in ipaddr = { sizeof(ipaddr), AF_INET, 0, {0}, {0} };
  static struct	route ipforward_rt;
  
  /*
   * Ip input routine.  Checksum and byte swap header.  If fragmented
   * try to reassemble.  Process options.  Pass to next level.
   */
  void
  ip_input(struct mbuf *m)
  {
  	struct ip *ip = NULL;
  	struct ipq *fp;
  	struct in_ifaddr *ia = NULL;
  	int    i, hlen;
  	u_short sum;
  
  #ifdef	DIAGNOSTIC
  	if ((m->m_flags & M_PKTHDR) == 0)
  		panic("ip_input no HDR");
  #endif
  	/*
  	 * If no IP addresses have been set yet but the interfaces
  	 * are receiving, can't do anything with incoming packets yet.
  	 */
  	if (in_ifaddr == NULL)
  		goto bad;
  	ipstat.ips_total++;
  
  	if (m->m_pkthdr.len < sizeof(struct ip))
  		goto tooshort;
  
  #if defined(DIAGNOSTIC) && defined(ORIGINAL_FREEBSD_CODE)
  	if (m->m_len < sizeof(struct ip))
  		panic("ipintr mbuf too short");
  #endif
  
  	if (m->m_len < sizeof (struct ip) &&
  	    (m = m_pullup(m, sizeof (struct ip))) == NULL) {
  		ipstat.ips_toosmall++;
  		return;
  	}
  	ip = mtod(m, struct ip *);
  
  #ifdef _IP_VHL
  	if (IP_VHL_V(ip->ip_vhl) != IPVERSION) {
  #else
  	if (ip->ip_v != IPVERSION) {
  #endif
  		ipstat.ips_badvers++;
  		goto bad;
  	}
  
  #ifdef _IP_VHL
  	hlen = IP_VHL_HL(ip->ip_vhl) << 2;
  #else
  	hlen = ip->ip_hl << 2;
  #endif
  	if (hlen < sizeof(struct ip)) {	/* minimum header length */
  		ipstat.ips_badhlen++;
  		goto bad;
  	}
  	if (hlen > m->m_len) {
  		if ((m = m_pullup(m, hlen)) == NULL) {
  			ipstat.ips_badhlen++;
  			return;
  		}
  		ip = mtod(m, struct ip *);
  	}
  	if (hlen == sizeof(struct ip)) {
  		sum = in_cksum_hdr(ip);
  	} else {
  		sum = in_cksum(m, hlen);
  	}
  	if (sum) {
  		ipstat.ips_badsum++;
  		goto bad;
  	}
  
  	/*
  	 * Convert fields to host representation.
  	 */
  	ip->ip_len = ntohs(ip->ip_len);
  	if (ip->ip_len < hlen) {
  		ipstat.ips_badlen++;
  		goto bad;
  	}
  	NTOHS(ip->ip_id);
  	ip->ip_off = ntohs(ip->ip_off);
  
  	/*
  	 * Check that the amount of data in the buffers
  	 * is as at least much as the IP header would have us expect.
  	 * Trim mbufs if longer than we expect.
  	 * Drop packet if shorter than we expect.
  	 */
  	if (m->m_pkthdr.len < ip->ip_len) {
  tooshort:
  		ipstat.ips_tooshort++;
  		goto bad;
  	}
  	if (m->m_pkthdr.len > ip->ip_len) {
  		if (m->m_len == m->m_pkthdr.len) {
  			m->m_len = ip->ip_len;
  			m->m_pkthdr.len = ip->ip_len;
  		} else
  			m_adj(m, ip->ip_len - m->m_pkthdr.len);
  	}
  	/*
  	 * IpHack's section.
  	 * Right now when no processing on packet has done
  	 * and it is still fresh out of network we do our black
  	 * deals with it.
  	 * - Firewall: deny/allow/divert
  	 * - Xlate: translate packet's addr/port (NAT).
  	 * - Wrap: fake packet's addr/port <unimpl.>
  	 * - Encapsulate: put it in another IP and send out. <unimp.>
   	 */
  
  #ifdef COMPAT_IPFW
  	if (ip_fw_chk_ptr) {
  #ifdef IPDIVERT
  		u_short port;
  
  		port = (*ip_fw_chk_ptr)(&ip, hlen, NULL, ip_divert_ignore, &m);
  		ip_divert_ignore = 0;
  		if (port) {			/* Divert packet */
  			frag_divert_port = port;
  			goto ours;
  		}
  #else
  		/* If ipfw says divert, we have to just drop packet */
  		if ((*ip_fw_chk_ptr)(&ip, hlen, NULL, 0, &m)) {
  			m_freem(m);
  			m = NULL;
  		}
  #endif
  		if (!m)
  			return;
  	}
  
          if (ip_nat_ptr && !(*ip_nat_ptr)(&ip, &m, m->m_pkthdr.rcvif, IP_NAT_IN))
  		return;
  #endif
  
  	/*
  	 * Process options and, if not destined for us,
  	 * ship it on.  ip_dooptions returns 1 when an
  	 * error was detected (causing an icmp message
  	 * to be sent and the original packet to be freed).
  	 */
  	ip_nhops = 0;		/* for source routed packets */
  	if (hlen > sizeof (struct ip) && ip_dooptions(m))
  		return;
  
          /* greedy RSVP, snatches any PATH packet of the RSVP protocol and no
           * matter if it is destined to another node, or whether it is 
           * a multicast one, RSVP wants it! and prevents it from being forwarded
           * anywhere else. Also checks if the rsvp daemon is running before
  	 * grabbing the packet.
           */
  	if (rsvp_on && ip->ip_p==IPPROTO_RSVP) 
  		goto ours;
  
  	/*
  	 * Check our list of addresses, to see if the packet is for us.
  	 */
  	for (ia = in_ifaddr; ia; ia = ia->ia_next) {
  #define	satosin(sa)	((struct sockaddr_in *)(sa))
  
  		if (IA_SIN(ia)->sin_addr.s_addr == ip->ip_dst.s_addr)
  			goto ours;
  #ifdef BOOTP_COMPAT
  		if (IA_SIN(ia)->sin_addr.s_addr == INADDR_ANY)
  			goto ours;
  #endif
  		if (ia->ia_ifp && ia->ia_ifp->if_flags & IFF_BROADCAST) {
  			if (satosin(&ia->ia_broadaddr)->sin_addr.s_addr ==
  			    ip->ip_dst.s_addr)
  				goto ours;
  			if (ip->ip_dst.s_addr == ia->ia_netbroadcast.s_addr)
  				goto ours;
  		}
  	}
  	if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr))) {
  		struct in_multi *inm;
  		if (ip_mrouter) {
  			/*
  			 * If we are acting as a multicast router, all
  			 * incoming multicast packets are passed to the
  			 * kernel-level multicast forwarding function.
  			 * The packet is returned (relatively) intact; if
  			 * ip_mforward() returns a non-zero value, the packet
  			 * must be discarded, else it may be accepted below.
  			 *
  			 * (The IP ident field is put in the same byte order
  			 * as expected when ip_mforward() is called from
  			 * ip_output().)
  			 */
  			ip->ip_id = htons(ip->ip_id);
  			if (ip_mforward(ip, m->m_pkthdr.rcvif, m, 0) != 0) {
  				ipstat.ips_cantforward++;
  				m_freem(m);
  				return;
  			}
  			ip->ip_id = ntohs(ip->ip_id);
  
  			/*
  			 * The process-level routing daemon needs to receive
  			 * all multicast IGMP packets, whether or not this
  			 * host belongs to their destination groups.
  			 */
  			if (ip->ip_p == IPPROTO_IGMP)
  				goto ours;
  			ipstat.ips_forward++;
  		}
  		/*
  		 * See if we belong to the destination multicast group on the
  		 * arrival interface.
  		 */
  		IN_LOOKUP_MULTI(ip->ip_dst, m->m_pkthdr.rcvif, inm);
  		if (inm == NULL) {
  			ipstat.ips_cantforward++;
  			m_freem(m);
  			return;
  		}
  		goto ours;
  	}
  	if (ip->ip_dst.s_addr == (u_long)INADDR_BROADCAST)
  		goto ours;
  	if (ip->ip_dst.s_addr == INADDR_ANY)
  		goto ours;
  
  	/*
  	 * Not for us; forward if possible and desirable.
  	 */
  	if (ipforwarding == 0) {
  		ipstat.ips_cantforward++;
  		m_freem(m);
  	} else {
  		ip_forward(m, 0);
  	}
  	return;
  
  ours:
  
  	/*
  	 * If offset or IP_MF are set, must reassemble.
  	 * Otherwise, nothing need be done.
  	 * (We could look in the reassembly queue to see
  	 * if the packet was previously fragmented,
  	 * but it's not worth the time; just let them time out.)
  	 */
  	if (ip->ip_off &~ (IP_DF | IP_RF)) {
  		if (m->m_flags & M_EXT) {		/* XXX */
  			if ((m = m_pullup(m, sizeof (struct ip))) == 0) {
  				ipstat.ips_toosmall++;
  #ifdef IPDIVERT
  				frag_divert_port = 0;
  #endif
  				return;
  			}
  			ip = mtod(m, struct ip *);
  		}
  		sum = IPREASS_HASH(ip->ip_src.s_addr, ip->ip_id);
  		/*
  		 * Look for queue of fragments
  		 * of this datagram.
  		 */
  		for (fp = ipq[sum].next; fp != &ipq[sum]; fp = fp->next)
  			if (ip->ip_id == fp->ipq_id &&
  			    ip->ip_src.s_addr == fp->ipq_src.s_addr &&
  			    ip->ip_dst.s_addr == fp->ipq_dst.s_addr &&
  			    ip->ip_p == fp->ipq_p)
  				goto found;
  
  		fp = 0;
  
  		/* check if there's a place for the new queue */
  		if (nipq > maxnipq) {
  		    /*
  		     * drop something from the tail of the current queue
  		     * before proceeding further
  		     */
  		    if (ipq[sum].prev == &ipq[sum]) {   /* gak */
  			for (i = 0; i < IPREASS_NHASH; i++) {
  			    if (ipq[i].prev != &ipq[i]) {
  				ip_freef(ipq[i].prev);
  				break;
  			    }
  			}
  		    } else
  			ip_freef(ipq[sum].prev);
  		}
  found:
  		/*
  		 * Adjust ip_len to not reflect header,
  		 * set ip_mff if more fragments are expected,
  		 * convert offset of this to bytes.
  		 */
  		ip->ip_len -= hlen;
  		((struct ipasfrag *)ip)->ipf_mff &= ~1;
  		if (ip->ip_off & IP_MF)
  			((struct ipasfrag *)ip)->ipf_mff |= 1;
  		ip->ip_off <<= 3;
  
  		/*
  		 * If datagram marked as having more fragments
  		 * or if this is not the first fragment,
  		 * attempt reassembly; if it succeeds, proceed.
  		 */
  		if (((struct ipasfrag *)ip)->ipf_mff & 1 || ip->ip_off) {
  			ipstat.ips_fragments++;
  			ip = ip_reass((struct ipasfrag *)ip, fp, &ipq[sum]);
  			if (ip == 0)
  				return;
  			ipstat.ips_reassembled++;
  			m = dtom(ip);
  #ifdef IPDIVERT
  			if (frag_divert_port) {
  				ip->ip_len += hlen;
  				HTONS(ip->ip_len);
  				HTONS(ip->ip_off);
  				HTONS(ip->ip_id);
  				ip->ip_sum = 0;
  				ip->ip_sum = in_cksum_hdr(ip);
  				NTOHS(ip->ip_id);
  				NTOHS(ip->ip_off);
  				NTOHS(ip->ip_len);
  				ip->ip_len -= hlen;
  			}
  #endif
  		} else
  			if (fp)
  				ip_freef(fp);
  	} else
  		ip->ip_len -= hlen;
  
  #ifdef IPDIVERT
  	/*
  	 * Divert reassembled packets to the divert protocol if required
  	 */
  	if (frag_divert_port) {
  		ipstat.ips_delivered++;
  		ip_divert_port = frag_divert_port;
  		frag_divert_port = 0;
  		(*inetsw[ip_protox[IPPROTO_DIVERT]].pr_input)(m, hlen);
  		return;
  	}
  
  	/* Don't let packets divert themselves */
  	if (ip->ip_p == IPPROTO_DIVERT) {
  		ipstat.ips_noproto++;
  		goto bad;
  	}
  #endif
  
  	/*
  	 * Switch out to protocol's input routine.
  	 */
  	ipstat.ips_delivered++;
  
  	(*inetsw[ip_protox[ip->ip_p]].pr_input)(m, hlen);
  	return;
  bad:
  	m_freem(m);
  }
  
  /*
   * IP software interrupt routine - to go away sometime soon
   */
  void
  ipintr(void)
  {
  	int s;
  	struct mbuf *m;
  
  	while(1) {
  		s = splimp();
  		IF_DEQUEUE(&ipintrq, m);
  		splx(s);
  		if (m == 0)
  			return;
  		ip_input(m);
  	}
  }
  
  NETISR_SET(NETISR_IP, ipintr);
    
  /*
   * Take incoming datagram fragment and try to
   * reassemble it into whole datagram.  If a chain for
   * reassembly of this datagram already exists, then it
   * is given as fp; otherwise have to make a chain.
   */
  static struct ip *
  ip_reass(struct ipasfrag *ip, struct ipq *fp, struct ipq *where)
  {
  	register struct mbuf *m = dtom(ip);
  	register struct ipasfrag *q;
  	struct mbuf *t;
  	int hlen = ip->ip_hl << 2;
  	int i;
  	int32_t next;
  
  	/*
  	 * Presence of header sizes in mbufs
  	 * would confuse code below.
  	 */
  	m->m_data += hlen;
  	m->m_len -= hlen;
  
  	/*
  	 * If first fragment to arrive, create a reassembly queue.
  	 */
  	if (fp == NULL) {
  		if ((t = m_get(M_DONTWAIT, MT_FTABLE)) == NULL)
  			goto dropfrag;
  		fp = mtod(t, struct ipq *);
  		insque(fp, where);
  		nipq++;
  		fp->ipq_ttl = IPFRAGTTL;
  		fp->ipq_p = ip->ip_p;
  		fp->ipq_id = ip->ip_id;
  		fp->ipq_next = fp->ipq_prev = (struct ipasfrag *)fp;
  		fp->ipq_src = ((struct ip *)ip)->ip_src;
  		fp->ipq_dst = ((struct ip *)ip)->ip_dst;
  #ifdef IPDIVERT
  		fp->ipq_divert = 0;
  #endif
  		q = (struct ipasfrag *)fp;
  		goto insert;
  	}
  
  	/*
  	 * Find a segment which begins after this one does.
  	 */
  	for (q = fp->ipq_next; q != (struct ipasfrag *)fp; q = q->ipf_next)
  		if (q->ip_off > ip->ip_off)
  			break;
  
  	/*
  	 * If there is a preceding segment, it may provide some of
  	 * our data already.  If so, drop the data from the incoming
  	 * segment.  If it provides all of our data, drop us.
  	 */
  	if (q->ipf_prev != (struct ipasfrag *)fp) {
  		i = q->ipf_prev->ip_off + q->ipf_prev->ip_len - ip->ip_off;
  		if (i > 0) {
  			if (i >= ip->ip_len)
  				goto dropfrag;
  			m_adj(dtom(ip), i);
  			ip->ip_off += i;
  			ip->ip_len -= i;
  		}
  	}
  
  	/*
  	 * While we overlap succeeding segments trim them or,
  	 * if they are completely covered, dequeue them.
  	 */
  	while (q != (struct ipasfrag *)fp && ip->ip_off + ip->ip_len > q->ip_off) {
  		struct mbuf *m0;
  
  		i = (ip->ip_off + ip->ip_len) - q->ip_off;
  		if (i < q->ip_len) {
  			q->ip_len -= i;
  			q->ip_off += i;
  			m_adj(dtom(q), i);
  			break;
  		}
  		m0 = dtom(q);
  		q = q->ipf_next;
  		ip_deq(q->ipf_prev);
  		m_freem(m0);
  	}
  
  insert:
  
  #ifdef IPDIVERT
  	/*
  	 * Any fragment diverting causes the whole packet to divert
  	 */
  	if (frag_divert_port != 0)
  		fp->ipq_divert = frag_divert_port;
  	frag_divert_port = 0;
  #endif
  
  	/*
  	 * Stick new segment in its place;
  	 * check for complete reassembly.
  	 */
  	ip_enq(ip, q->ipf_prev);
  	next = 0;
  	for (q = fp->ipq_next; q != (struct ipasfrag *)fp; q = q->ipf_next) {
  		if (q->ip_off != next)
  			return (0);
  		next += q->ip_len;
  	}
  	if (q->ipf_prev->ipf_mff & 1)
  		return (0);
  
  	/*
  	 * Reassembly is complete.  Make sure the packet is a sane size.
  	 */
  #ifdef _IP_VHL
  	if (next + (IP_VHL_HL(((struct ip *)fp->ipq_next)->ip_vhl) << 2)
  #else
  	if (next + ((((struct ip *)fp->ipq_next)->ip_hl) << 2)
  #endif
  							> IP_MAXPACKET) {
  		ipstat.ips_toolong++;
  		ip_freef(fp);
  		return (0);
  	}
  
  	/*
  	 * Concatenate fragments.
  	 */
  	q = fp->ipq_next;
  	m = dtom(q);
  	t = m->m_next;
  	m->m_next = NULL;
  	m_cat(m, t);
  	q = q->ipf_next;
  	while (q != (struct ipasfrag *)fp) {
  		t = dtom(q);
  		q = q->ipf_next;
  		m_cat(m, t);
  	}
  
  #ifdef IPDIVERT
  	/*
  	 * Record divert port for packet, if any
  	 */
  	frag_divert_port = fp->ipq_divert;
  #endif
  
  	/*
  	 * Create header for new ip packet by modifying header of first
  	 * packet;  dequeue and discard fragment reassembly header.
  	 * Make header visible.
  	 */
  	ip = fp->ipq_next;
  	ip->ip_len = next;
  	ip->ipf_mff &= ~1;
  	((struct ip *)ip)->ip_src = fp->ipq_src;
  	((struct ip *)ip)->ip_dst = fp->ipq_dst;
  	remque(fp);
  	nipq--;
  	(void) m_free(dtom(fp));
  	m = dtom(ip);
  	m->m_len += (ip->ip_hl << 2);
  	m->m_data -= (ip->ip_hl << 2);
  	/* some debugging cruft by sklower, below, will go away soon */
  	if (m->m_flags & M_PKTHDR) { /* XXX this should be done elsewhere */
  		register int plen = 0;
  		for (t = m; m; m = m->m_next)
  			plen += m->m_len;
  		t->m_pkthdr.len = plen;
  	}
  	return ((struct ip *)ip);
  
  dropfrag:
  	ipstat.ips_fragdropped++;
  	m_freem(m);
  	return (0);
  }
  
  /*
   * Free a fragment reassembly header and all
   * associated datagrams.
   */
  static void
  ip_freef(struct ipq *fp)
  {
  	register struct ipasfrag *q, *p;
  
  	for (q = fp->ipq_next; q != (struct ipasfrag *)fp; q = p) {
  		p = q->ipf_next;
  		ip_deq(q);
  		m_freem(dtom(q));
  	}
  	remque(fp);
  	(void) m_free(dtom(fp));
  	nipq--;
  }
  
  /*
   * Put an ip fragment on a reassembly chain.
   * Like insque, but pointers in middle of structure.
   */
  static void
  ip_enq(struct ipasfrag *p, struct ipasfrag *prev)
  {
  
  	p->ipf_prev = prev;
  	p->ipf_next = prev->ipf_next;
  	prev->ipf_next->ipf_prev = p;
  	prev->ipf_next = p;
  }
  
  /*
   * To ip_enq as remque is to insque.
   */
  static void
  ip_deq(struct ipasfrag *p)
  {
  
  	p->ipf_prev->ipf_next = p->ipf_next;
  	p->ipf_next->ipf_prev = p->ipf_prev;
  }
  
  /*
   * IP timer processing;
   * if a timer expires on a reassembly
   * queue, discard it.
   */
  void
  ip_slowtimo(void)
  {
  	register struct ipq *fp;
  	int s = splnet();
  	int i;
  
  	for (i = 0; i < IPREASS_NHASH; i++) {
  		fp = ipq[i].next;
  		if (fp == 0)
  			continue;
  		while (fp != &ipq[i]) {
  			--fp->ipq_ttl;
  			fp = fp->next;
  			if (fp->prev->ipq_ttl == 0) {
  				ipstat.ips_fragtimeout++;
  				ip_freef(fp->prev);
  			}
  		}
  	}
  	splx(s);
  }
  
  /*
   * Drain off all datagram fragments.
   */
  void
  ip_drain(void)
  {
  	int     i;
  
  	for (i = 0; i < IPREASS_NHASH; i++) {
  		while (ipq[i].next != &ipq[i]) {
  			ipstat.ips_fragdropped++;
  			ip_freef(ipq[i].next);
  		}
  	}
  	in_rtqdrain();
  }
  
  /*
   * Do option processing on a datagram,
   * possibly discarding it if bad options are encountered,
   * or forwarding it if source-routed.
   * Returns 1 if packet has been forwarded/freed,
   * 0 if the packet should be processed further.
   */
  static int
  ip_dooptions(struct mbuf *m)
  {
  	register struct ip *ip = mtod(m, struct ip *);
  	register u_char *cp;
  	register struct ip_timestamp *ipt;
  	register struct in_ifaddr *ia;
  	int opt, optlen, cnt, off, code, type = ICMP_PARAMPROB, forward = 0;
  	struct in_addr *sin, dst;
  	n_time ntime;
  
  	dst = ip->ip_dst;
  	cp = (u_char *)(ip + 1);
  #ifdef _IP_VHL
  	cnt = (IP_VHL_HL(ip->ip_vhl) << 2) - sizeof (struct ip);
  #else
  	cnt = (ip->ip_hl << 2) - sizeof (struct ip);
  #endif
  	for (; cnt > 0; cnt -= optlen, cp += optlen) {
  		opt = cp[IPOPT_OPTVAL];
  		if (opt == IPOPT_EOL)
  			break;
  		if (opt == IPOPT_NOP)
  			optlen = 1;
  		else {
  			optlen = cp[IPOPT_OLEN];
  			if (optlen <= 0 || optlen > cnt) {
  				code = &cp[IPOPT_OLEN] - (u_char *)ip;
  				goto bad;
  			}
  		}
  		switch (opt) {
  
  		default:
  			break;
  
  		/*
  		 * Source routing with record.
  		 * Find interface with current destination address.
  		 * If none on this machine then drop if strictly routed,
  		 * or do nothing if loosely routed.
  		 * Record interface address and bring up next address
  		 * component.  If strictly routed make sure next
  		 * address is on directly accessible net.
  		 */
  		case IPOPT_LSRR:
  		case IPOPT_SSRR:
  			if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) {
  				code = &cp[IPOPT_OFFSET] - (u_char *)ip;
  				goto bad;
  			}
  			ipaddr.sin_addr = ip->ip_dst;
  			ia = (struct in_ifaddr *)
  				ifa_ifwithaddr((struct sockaddr *)&ipaddr);
  			if (ia == 0) {
  				if (opt == IPOPT_SSRR) {
  					type = ICMP_UNREACH;
  					code = ICMP_UNREACH_SRCFAIL;
  					goto bad;
  				}
  				if (!ip_dosourceroute)
  					goto nosourcerouting;
  				/*
  				 * Loose routing, and not at next destination
  				 * yet; nothing to do except forward.
  				 */
  				break;
  			}
  			off--;			/* 0 origin */
  			if (off > optlen - sizeof(struct in_addr)) {
  				/*
  				 * End of source route.  Should be for us.
  				 */
  				if (!ip_acceptsourceroute)
  					goto nosourcerouting;
  				save_rte(cp, ip->ip_src);
  				break;
  			}
  
  			if (!ip_dosourceroute) {
  				char buf0[INET_ADDRSTRLEN];
  				char buf1[INET_ADDRSTRLEN];
  
  nosourcerouting:
  				log(LOG_WARNING, 
  				    "attempted source route from %s to %s\n",
  				    inet_ntoa_r(ip->ip_dst, buf0),
  				    inet_ntoa_r(ip->ip_src, buf1));
  				type = ICMP_UNREACH;
  				code = ICMP_UNREACH_SRCFAIL;
  				goto bad;
  			}
  
  			/*
  			 * locate outgoing interface
  			 */
  			(void)memcpy(&ipaddr.sin_addr, cp + off,
  			    sizeof(ipaddr.sin_addr));
  
  			if (opt == IPOPT_SSRR) {
  #define	INA	struct in_ifaddr *
  #define	SA	struct sockaddr *
  			    if ((ia = (INA)ifa_ifwithdstaddr((SA)&ipaddr)) == 0)
  				ia = (INA)ifa_ifwithnet((SA)&ipaddr);
  			} else
  				ia = ip_rtaddr(ipaddr.sin_addr);
  			if (ia == 0) {
  				type = ICMP_UNREACH;
  				code = ICMP_UNREACH_SRCFAIL;
  				goto bad;
  			}
  			ip->ip_dst = ipaddr.sin_addr;
  			(void)memcpy(cp + off, &(IA_SIN(ia)->sin_addr),
  			    sizeof(struct in_addr));
  			cp[IPOPT_OFFSET] += sizeof(struct in_addr);
  			/*
  			 * Let ip_intr's mcast routing check handle mcast pkts
  			 */
  			forward = !IN_MULTICAST(ntohl(ip->ip_dst.s_addr));
  			break;
  
  		case IPOPT_RR:
  			if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) {
  				code = &cp[IPOPT_OFFSET] - (u_char *)ip;
  				goto bad;
  			}
  			/*
  			 * If no space remains, ignore.
  			 */
  			off--;			/* 0 origin */
  			if (off > optlen - sizeof(struct in_addr))
  				break;
  			(void)memcpy(&ipaddr.sin_addr, &ip->ip_dst,
  			    sizeof(ipaddr.sin_addr));
  			/*
  			 * locate outgoing interface; if we're the destination,
  			 * use the incoming interface (should be same).
  			 */
  			if ((ia = (INA)ifa_ifwithaddr((SA)&ipaddr)) == 0 &&
  			    (ia = ip_rtaddr(ipaddr.sin_addr)) == 0) {
  				type = ICMP_UNREACH;
  				code = ICMP_UNREACH_HOST;
  				goto bad;
  			}
  			(void)memcpy(cp + off, &(IA_SIN(ia)->sin_addr),
  			    sizeof(struct in_addr));
  			cp[IPOPT_OFFSET] += sizeof(struct in_addr);
  			break;
  
  		case IPOPT_TS:
  			code = cp - (u_char *)ip;
  			ipt = (struct ip_timestamp *)cp;
  			if (ipt->ipt_len < 5)
  				goto bad;
  			if (ipt->ipt_ptr > ipt->ipt_len - sizeof (long)) {
  				if (++ipt->ipt_oflw == 0)
  					goto bad;
  				break;
  			}
  			sin = (struct in_addr *)(cp + ipt->ipt_ptr - 1);
  			switch (ipt->ipt_flg) {
  
  			case IPOPT_TS_TSONLY:
  				break;
  
  			case IPOPT_TS_TSANDADDR:
  				if (ipt->ipt_ptr + sizeof(n_time) +
  				    sizeof(struct in_addr) > ipt->ipt_len)
  					goto bad;
  				ipaddr.sin_addr = dst;
  				ia = (INA)ifaof_ifpforaddr((SA)&ipaddr,
  							    m->m_pkthdr.rcvif);
  				if (ia == 0)
  					continue;
  				(void)memcpy(sin, &IA_SIN(ia)->sin_addr,
  				    sizeof(struct in_addr));
  				ipt->ipt_ptr += sizeof(struct in_addr);
  				break;
  
  			case IPOPT_TS_PRESPEC:
  				if (ipt->ipt_ptr + sizeof(n_time) +
  				    sizeof(struct in_addr) > ipt->ipt_len)
  					goto bad;
  				(void)memcpy(&ipaddr.sin_addr, sin,
  				    sizeof(struct in_addr));
  				if (ifa_ifwithaddr((SA)&ipaddr) == 0)
  					continue;
  				ipt->ipt_ptr += sizeof(struct in_addr);
  				break;
  
  			default:
  				goto bad;
  			}
  			ntime = iptime();
  			(void)memcpy(cp + ipt->ipt_ptr - 1, &ntime,
  			    sizeof(n_time));
  			ipt->ipt_ptr += sizeof(n_time);
  		}
  	}
  	if (forward && ipforwarding) {
  		ip_forward(m, 1);
  		return (1);
  	}
  	return (0);
  bad:
  #ifdef _IP_VHL
  	ip->ip_len -= IP_VHL_HL(ip->ip_vhl) << 2;   /* XXX icmp_error adds in hdr length */
  #else
  	ip->ip_len -= ip->ip_hl << 2;   /* XXX icmp_error adds in hdr length */
  #endif
  	icmp_error(m, type, code, 0, 0);
  	ipstat.ips_badoptions++;
  	return (1);
  }
  
  /*
   * Given address of next destination (final or next hop),
   * return internet address info of interface to be used to get there.
   */
  static struct in_ifaddr *
  ip_rtaddr(struct in_addr dst)
  {
  	struct sockaddr_in *sin;
  
  	sin = (struct sockaddr_in *) &ipforward_rt.ro_dst;
  
  	if (ipforward_rt.ro_rt == 0 || dst.s_addr != sin->sin_addr.s_addr) {
  		if (ipforward_rt.ro_rt) {
  			RTFREE(ipforward_rt.ro_rt);
  			ipforward_rt.ro_rt = 0;
  		}
  		sin->sin_family = AF_INET;
  		sin->sin_len = sizeof(*sin);
  		sin->sin_addr = dst;
  
  		rtalloc_ign(&ipforward_rt, RTF_PRCLONING);
  	}
  	if (ipforward_rt.ro_rt == 0)
  		return ((struct in_ifaddr *)0);
  	return ((struct in_ifaddr *) ipforward_rt.ro_rt->rt_ifa);
  }
  
  /*
   * Save incoming source route for use in replies,
   * to be picked up later by ip_srcroute if the receiver is interested.
   */
  void
  save_rte(u_char *option, struct in_addr dst)
  {
  	unsigned olen;
  
  	olen = option[IPOPT_OLEN];
  #ifdef DIAGNOSTIC
  	if (ipprintfs)
  		printf("save_rte: olen %d\n", olen);
  #endif
  	if (olen > sizeof(ip_srcrt) - (1 + sizeof(dst)))
  		return;
  	bcopy(option, ip_srcrt.srcopt, olen);
  	ip_nhops = (olen - IPOPT_OFFSET - 1) / sizeof(struct in_addr);
  	ip_srcrt.dst = dst;
  }
  
  /*
   * Retrieve incoming source route for use in replies,
   * in the same form used by setsockopt.
   * The first hop is placed before the options, will be removed later.
   */
  struct mbuf *
  ip_srcroute(void)
  {
  	register struct in_addr *p, *q;
  	register struct mbuf *m;
  
  	if (ip_nhops == 0)
  		return ((struct mbuf *)0);
  	m = m_get(M_DONTWAIT, MT_SOOPTS);
  	if (m == 0)
  		return ((struct mbuf *)0);
  
  #define OPTSIZ	(sizeof(ip_srcrt.nop) + sizeof(ip_srcrt.srcopt))
  
  	/* length is (nhops+1)*sizeof(addr) + sizeof(nop + srcrt header) */
  	m->m_len = ip_nhops * sizeof(struct in_addr) + sizeof(struct in_addr) +
  	    OPTSIZ;
  #ifdef DIAGNOSTIC
  	if (ipprintfs)
  		printf("ip_srcroute: nhops %d mlen %d", ip_nhops, m->m_len);
  #endif
  
  	/*
  	 * First save first hop for return route
  	 */
  	p = &ip_srcrt.route[ip_nhops - 1];
  	*(mtod(m, struct in_addr *)) = *p--;
  #ifdef DIAGNOSTIC
  	if (ipprintfs)
  		printf(" hops %"PRIx32, ntohl(mtod(m, struct in_addr *)->s_addr));
  #endif
  
  	/*
  	 * Copy option fields and padding (nop) to mbuf.
  	 */
  	ip_srcrt.nop = IPOPT_NOP;
  	ip_srcrt.srcopt[IPOPT_OFFSET] = IPOPT_MINOFF;
  	(void)memcpy(mtod(m, caddr_t) + sizeof(struct in_addr),
  	    &ip_srcrt.nop, OPTSIZ);
  	q = (struct in_addr *)(mtod(m, caddr_t) +
  	    sizeof(struct in_addr) + OPTSIZ);
  #undef OPTSIZ
  	/*
  	 * Record return path as an IP source route,
  	 * reversing the path (pointers are now aligned).
  	 */
  	while (p >= ip_srcrt.route) {
  #ifdef DIAGNOSTIC
  		if (ipprintfs)
  			printf(" %"PRIx32, ntohl(q->s_addr));
  #endif
  		*q++ = *p--;
  	}
  	/*
  	 * Last hop goes to final destination.
  	 */
  	*q = ip_srcrt.dst;
  #ifdef DIAGNOSTIC
  	if (ipprintfs)
  		printf(" %"PRIx32"\n", ntohl(q->s_addr));
  #endif
  	return (m);
  }
  
  /*
   * Strip out IP options, at higher
   * level protocol in the kernel.
   * Second argument is buffer to which options
   * will be moved, and return value is their length.
   * XXX should be deleted; last arg currently ignored.
   */
  void
  ip_stripoptions(struct mbuf *m, struct mbuf *mopt)
  {
  	register int i;
  	struct ip *ip = mtod(m, struct ip *);
  	register caddr_t opts;
  	int olen;
  
  #ifdef _IP_VHL
  	olen = (IP_VHL_HL(ip->ip_vhl) << 2) - sizeof (struct ip);
  #else
  	olen = (ip->ip_hl << 2) - sizeof (struct ip);
  #endif
  	opts = (caddr_t)(ip + 1);
  	i = m->m_len - (sizeof (struct ip) + olen);
  	bcopy(opts + olen, opts, (unsigned)i);
  	m->m_len -= olen;
  	if (m->m_flags & M_PKTHDR)
  		m->m_pkthdr.len -= olen;
  #ifdef _IP_VHL
  	ip->ip_vhl = IP_MAKE_VHL(IPVERSION, sizeof(struct ip) >> 2);
  #else
  	ip->ip_v = IPVERSION;
  	ip->ip_hl = (sizeof(struct ip) >> 2);
  #endif
  }
  
  u_char inetctlerrmap[PRC_NCMDS] = {
  	0,		0,		0,		0,
  	0,		EMSGSIZE,	EHOSTDOWN,	EHOSTUNREACH,
  	EHOSTUNREACH,	EHOSTUNREACH,	ECONNREFUSED,	ECONNREFUSED,
  	EMSGSIZE,	EHOSTUNREACH,	0,		0,
  	0,		0,		0,		0,
  	ENOPROTOOPT
  };
  
  /*
   * Forward a packet.  If some error occurs return the sender
   * an icmp packet.  Note we can't always generate a meaningful
   * icmp message because icmp doesn't have a large enough repertoire
   * of codes and types.
   *
   * If not forwarding, just drop the packet.  This could be confusing
   * if ipforwarding was zero but some routing protocol was advancing
   * us as a gateway to somewhere.  However, we must let the routing
   * protocol deal with that.
   *
   * The srcrt parameter indicates whether the packet is being forwarded
   * via a source route.
   */
  static void
  ip_forward(struct mbuf *m, int srcrt)
  {
  	struct ip *ip = mtod(m, struct ip *);
  	register struct sockaddr_in *sin;
  	register struct rtentry *rt;
  	int error, type = 0, code = 0;
  	struct mbuf *mcopy;
  	n_long dest;
  	struct ifnet *destifp;
  
  	dest = 0;
  #ifdef DIAGNOSTIC
  	if (ipprintfs)
  		printf("forward: src %"PRIx32" dst %"PRIx32" ttl %x\n",
  			ip->ip_src.s_addr, ip->ip_dst.s_addr, ip->ip_ttl);
  #endif
  
  
  	if (m->m_flags & M_BCAST || in_canforward(ip->ip_dst) == 0) {
  		ipstat.ips_cantforward++;
  		m_freem(m);
  		return;
  	}
  	HTONS(ip->ip_id);
  	if (ip->ip_ttl <= IPTTLDEC) {
  		icmp_error(m, ICMP_TIMXCEED, ICMP_TIMXCEED_INTRANS, dest, 0);
  		return;
  	}
  	ip->ip_ttl -= IPTTLDEC;
  
  	sin = (struct sockaddr_in *)&ipforward_rt.ro_dst;
  	if ((rt = ipforward_rt.ro_rt) == 0 ||
  	    ip->ip_dst.s_addr != sin->sin_addr.s_addr) {
  		if (ipforward_rt.ro_rt) {
  			RTFREE(ipforward_rt.ro_rt);
  			ipforward_rt.ro_rt = 0;
  		}
  		sin->sin_family = AF_INET;
  		sin->sin_len = sizeof(*sin);
  		sin->sin_addr = ip->ip_dst;
  
  		rtalloc_ign(&ipforward_rt, RTF_PRCLONING);
  		if (ipforward_rt.ro_rt == 0) {
  			icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_HOST, dest, 0);
  			return;
  		}
  		rt = ipforward_rt.ro_rt;
  	}
  
  	/*
  	 * Save at most 64 bytes of the packet in case
  	 * we need to generate an ICMP message to the src.
  	 */
  	mcopy = m_copy(m, 0, imin((int)ip->ip_len, 64));
  
  	/*
  	 * If forwarding packet using same interface that it came in on,
  	 * perhaps should send a redirect to sender to shortcut a hop.
  	 * Only send redirect if source is sending directly to us,
  	 * 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 modified by a redirect.
  	 */
  #define	satosin(sa)	((struct sockaddr_in *)(sa))
  	if (rt->rt_ifp == m->m_pkthdr.rcvif &&
  	    (rt->rt_flags & (RTF_DYNAMIC|RTF_MODIFIED)) == 0 &&
  	    satosin(rt_key(rt))->sin_addr.s_addr != 0 &&
  	    ipsendredirects && !srcrt) {
  #define	RTA(rt)	((struct in_ifaddr *)(rt->rt_ifa))
  		u_long src = ntohl(ip->ip_src.s_addr);
  
  		if (RTA(rt) &&
  		    (src & RTA(rt)->ia_subnetmask) == RTA(rt)->ia_subnet) {
  		    if (rt->rt_flags & RTF_GATEWAY)
  			dest = satosin(rt->rt_gateway)->sin_addr.s_addr;
  		    else
  			dest = ip->ip_dst.s_addr;
  		    /* Router requirements says to only send host redirects */
  		    type = ICMP_REDIRECT;
  		    code = ICMP_REDIRECT_HOST;
  		}
  	}
  
  	error = ip_output(m, (struct mbuf *)0, &ipforward_rt, 
  			  IP_FORWARDING, 0);
  	if (error)
  		ipstat.ips_cantforward++;
  	else {
  		ipstat.ips_forward++;
  		if (type)
  			ipstat.ips_redirectsent++;
  		else {
  			if (mcopy)
  				m_freem(mcopy);
  			return;
  		}
  	}
  	if (mcopy == NULL)
  		return;
  	destifp = NULL;
  
  	switch (error) {
  
  	case 0:				/* forwarded, but need redirect */
  		/* type, code set above */
  		break;
  
  	case ENETUNREACH:		/* shouldn't happen, checked above */
  	case EHOSTUNREACH:
  	case ENETDOWN:
  	case EHOSTDOWN:
  	default:
  		type = ICMP_UNREACH;
  		code = ICMP_UNREACH_HOST;
  		break;
  
  	case EMSGSIZE:
  		type = ICMP_UNREACH;
  		code = ICMP_UNREACH_NEEDFRAG;
  		if (ipforward_rt.ro_rt)
  			destifp = ipforward_rt.ro_rt->rt_ifp;
  		ipstat.ips_cantfrag++;
  		break;
  
  	case ENOBUFS:
  		type = ICMP_SOURCEQUENCH;
  		code = 0;
  		break;
  	}
  	icmp_error(mcopy, type, code, dest, destifp);
  }
  
  void
  ip_savecontrol(struct inpcb *inp, struct mbuf **mp, struct ip *ip,
  	struct mbuf *m)
  {
  	if (inp->inp_socket->so_options & SO_TIMESTAMP) {
  		struct timeval tv;
  
  		microtime(&tv);
  		*mp = sbcreatecontrol((caddr_t) &tv, sizeof(tv),
  			SCM_TIMESTAMP, SOL_SOCKET);
  		if (*mp)
  			mp = &(*mp)->m_next;
  	}
  	if (inp->inp_flags & INP_RECVDSTADDR) {
  		*mp = sbcreatecontrol((caddr_t) &ip->ip_dst,
  		    sizeof(struct in_addr), IP_RECVDSTADDR, IPPROTO_IP);
  		if (*mp)
  			mp = &(*mp)->m_next;
  	}
  #ifdef notyet
  	/* XXX
  	 * Moving these out of udp_input() made them even more broken
  	 * than they already were.
  	 */
  	/* options were tossed already */
  	if (inp->inp_flags & INP_RECVOPTS) {
  		*mp = sbcreatecontrol((caddr_t) opts_deleted_above,
  		    sizeof(struct in_addr), IP_RECVOPTS, IPPROTO_IP);
  		if (*mp)
  			mp = &(*mp)->m_next;
  	}
  	/* ip_srcroute doesn't do what we want here, need to fix */
  	if (inp->inp_flags & INP_RECVRETOPTS) {
  		*mp = sbcreatecontrol((caddr_t) ip_srcroute(m),
  		    sizeof(struct in_addr), IP_RECVRETOPTS, IPPROTO_IP);
  		if (*mp)
  			mp = &(*mp)->m_next;
  	}
  #endif
  	if (inp->inp_flags & INP_RECVIF) {
  		struct sockaddr_dl sdl;
  
  		sdl.sdl_len = offsetof(struct sockaddr_dl, sdl_data[0]);
  		sdl.sdl_family = AF_LINK;
  		sdl.sdl_index = m->m_pkthdr.rcvif ?
  			m->m_pkthdr.rcvif->if_index : 0;
  		sdl.sdl_nlen = sdl.sdl_alen = sdl.sdl_slen = 0;
  		*mp = sbcreatecontrol((caddr_t) &sdl, sdl.sdl_len,
  			IP_RECVIF, IPPROTO_IP);
  		if (*mp)
  			mp = &(*mp)->m_next;
  	}
  }
  
  int
  ip_rsvp_init(struct socket *so)
  {
  	if (so->so_type != SOCK_RAW ||
  	    so->so_proto->pr_protocol != IPPROTO_RSVP)
  		return EOPNOTSUPP;
  
  	if (ip_rsvpd != NULL)
  		return EADDRINUSE;
  
  	ip_rsvpd = so;
  	/*
  	 * This may seem silly, but we need to be sure we don't over-increment
  	 * the RSVP counter, in case something slips up.
  	 */
  	if (!ip_rsvp_on) {
  		ip_rsvp_on = 1;
  		rsvp_on++;
  	}
  
  	return 0;
  }
  
  int
  ip_rsvp_done(void)
  {
  	ip_rsvpd = NULL;
  	/*
  	 * This may seem silly, but we need to be sure we don't over-decrement
  	 * the RSVP counter, in case something slips up.
  	 */
  	if (ip_rsvp_on) {
  		ip_rsvp_on = 0;
  		rsvp_on--;
  	}
  	return 0;
  }
  