/*	$OpenBSD: ip_output.c,v 1.152 2003/03/14 18:28:12 jason Exp $	*/
/*	$NetBSD: ip_output.c,v 1.28 1996/02/13 23:43:07 christos Exp $	*/

/*
 * Copyright (c) 1982, 1986, 1988, 1990, 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.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 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_output.c	8.3 (Berkeley) 1/21/94
 */

#include "pf.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/mbuf.h>
#include <sys/protosw.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <sys/proc.h>
#include <sys/kernel.h>

#include <net/if.h>
#include <net/route.h>

#include <netinet/in.h>
#include <netinet/in_systm.h>
#include <netinet/ip.h>
#include <netinet/in_pcb.h>
#include <netinet/in_var.h>
#include <netinet/ip_var.h>
#include <netinet/ip_icmp.h>
#include <netinet/tcp.h>
#include <netinet/udp.h>
#include <netinet/tcp_timer.h>
#include <netinet/tcp_var.h>
#include <netinet/udp_var.h>

#if NPF > 0
#include <net/pfvar.h>
#endif

int
ip_fragment(struct mbuf *m, struct ifnet *ifp, u_long mtu)
{
	struct ip *ip, *mhip;
	struct mbuf *m0;
	int len, hlen, off;
	int mhlen, firstlen;
	struct mbuf **mnext;

	ip = mtod(m, struct ip *);
	hlen = ip->ip_hl << 2;

	len = (mtu - hlen) &~ 7;
	if (len < 8)
		return (EMSGSIZE);

	/*
	 * If we are doing fragmentation, we can't defer TCP/UDP
	 * checksumming; compute the checksum and clear the flag.
	 */
	if (m->m_pkthdr.csum_flags & (M_CSUM_TCPv4 | M_CSUM_UDPv4)) {
		in_delayed_cksum(m);
		m->m_pkthdr.csum_flags &= ~(M_CSUM_TCPv4 | M_CSUM_UDPv4);
	}

	firstlen = len;
	mnext = &m->m_nextpkt;

	/*
	 * Loop through length of segment after first fragment,
	 * make new header and copy data of each part and link onto chain.
	 */
	m0 = m;
	mhlen = sizeof (struct ip);
	for (off = hlen + len; off < (u_int16_t)ip->ip_len; off += len) {
		MGETHDR(m, M_DONTWAIT, MT_HEADER);
		if (m == 0) {
			ipstat.ips_odropped++;
			return (ENOBUFS);
		}
		*mnext = m;
		mnext = &m->m_nextpkt;
		m->m_data += max_linkhdr;
		mhip = mtod(m, struct ip *);
		*mhip = *ip;
		/* we must inherit MCAST and BCAST flags */
		m->m_flags |= m0->m_flags & (M_MCAST|M_BCAST);
		if (hlen > sizeof (struct ip)) {
			mhlen = ip_optcopy(ip, mhip) + sizeof (struct ip);
			mhip->ip_hl = mhlen >> 2;
		}
		m->m_len = mhlen;
		mhip->ip_off = ((off - hlen) >> 3) + (ip->ip_off & ~IP_MF);
		if (ip->ip_off & IP_MF)
			mhip->ip_off |= IP_MF;
		if (off + len >= (u_int16_t)ip->ip_len)
			len = (u_int16_t)ip->ip_len - off;
		else
			mhip->ip_off |= IP_MF;
		mhip->ip_len = htons((u_int16_t)(len + mhlen));
		m->m_next = m_copy(m0, off, len);
		if (m->m_next == 0) {
			ipstat.ips_odropped++;
			return (ENOBUFS);	/* ??? */
		}
		m->m_pkthdr.len = mhlen + len;
		m->m_pkthdr.rcvif = (struct ifnet *)0;
		mhip->ip_off = htons((u_int16_t)mhip->ip_off);
		if ((ifp->if_capabilities & IFCAP_CSUM_IPv4) &&
		    ifp->if_bridge == NULL) {
			m->m_pkthdr.csum_flags |= M_CSUM_IPv4;
		} else {
			mhip->ip_sum = 0;
			mhip->ip_sum = in_cksum(m, mhlen);
		}
		ipstat.ips_ofragments++;
	}
	/*
	 * Update first fragment by trimming what's been copied out
	 * and updating header, then send each fragment (in order).
	 */
	m = m0;
	m_adj(m, hlen + firstlen - (u_int16_t)ip->ip_len);
	m->m_pkthdr.len = hlen + firstlen;
	ip->ip_len = htons((u_int16_t)m->m_pkthdr.len);
	ip->ip_off = htons((u_int16_t)(ip->ip_off | IP_MF));
	if ((ifp->if_capabilities & IFCAP_CSUM_IPv4) &&
	    ifp->if_bridge == NULL) {
		m->m_pkthdr.csum_flags |= M_CSUM_IPv4;
	} else {
		ip->ip_sum = 0;
		ip->ip_sum = in_cksum(m, hlen);
	}

	return (0);
}