/*

 * 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.

 * 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_input.c	8.2 (Berkeley) 1/4/94

 * ip_input.c,v 1.11 1994/11/16 10:17:08 jkh Exp

 */

/*

 * Changes and additions relating to SLiRP are

 * Copyright (c) 1995 Danny Gasparovski.

 *

 * Please read the file COPYRIGHT for the

 * terms and conditions of the copyright.

 */

#include <slirp.h>

#include "ip_icmp.h"

#ifdef LOG_ENABLED

struct ipstat ipstat;

#endif

struct ipq ipq;

static struct ip *ip_reass(register struct ipasfrag *ip,

                           register struct ipq *fp);

static void ip_freef(struct ipq *fp);

static void ip_enq(register struct ipasfrag *p,

                   register struct ipasfrag *prev);

static void ip_deq(register struct ipasfrag *p);

/*

 * IP initialization: fill in IP protocol switch table.

 * All protocols not implemented in kernel go to raw IP protocol handler.

 */

void

ip_init()

{

	ipq.next = ipq.prev = (ipqp_32)&ipq;

	ip_id = tt.tv_sec & 0xffff;

	udp_init();

	tcp_init();

}

/*

 * Ip input routine.  Checksum and byte swap header.  If fragmented

 * try to reassemble.  Process options.  Pass to next level.

 */

void

ip_input(m)

	struct mbuf *m;

{

	register struct ip *ip;

	int hlen;

	DEBUG_CALL("ip_input");

	DEBUG_ARG("m = %lx", (long)m);

	DEBUG_ARG("m_len = %d", m->m_len);

	STAT(ipstat.ips_total++);

	if (m->m_len < sizeof (struct ip)) {

		STAT(ipstat.ips_toosmall++);

		return;

	}

	ip = mtod(m, struct ip *);

	if (ip->ip_v != IPVERSION) {

		STAT(ipstat.ips_badvers++);

		goto bad;

	}

	hlen = ip->ip_hl << 2;

	if (hlen<sizeof(struct ip ) || hlen>m->m_len) {/* min header length */

	  STAT(ipstat.ips_badhlen++);                     /* or packet too short */

	  goto bad;

	}

        /* keep ip header intact for ICMP reply

	 * ip->ip_sum = cksum(m, hlen);

	 * if (ip->ip_sum) {

	 */

	if(cksum(m,hlen)) {

	  STAT(ipstat.ips_badsum++);

	  goto bad;

	}

	/*

	 * Convert fields to host representation.

	 */

	NTOHS(ip->ip_len);

	if (ip->ip_len < hlen) {

		STAT(ipstat.ips_badlen++);

		goto bad;

	}

	NTOHS(ip->ip_id);

	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_len < ip->ip_len) {

		STAT(ipstat.ips_tooshort++);

		goto bad;

	}

	/* Should drop packet if mbuf too long? hmmm... */

	if (m->m_len > ip->ip_len)

	   m_adj(m, ip->ip_len - m->m_len);

	/* check ip_ttl for a correct ICMP reply */

	if(ip->ip_ttl==0 || ip->ip_ttl==1) {

	  icmp_error(m, ICMP_TIMXCEED,ICMP_TIMXCEED_INTRANS, 0,"ttl");

	  goto bad;

	}

	/*

	 * 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).

	 */

/* We do no IP options */

/*	if (hlen > sizeof (struct ip) && ip_dooptions(m))

 *		goto next;

 */

	/*

	 * 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.)

	 *

	 * XXX This should fail, don't fragment yet

	 */

	if (ip->ip_off &~ IP_DF) {

	  register struct ipq *fp;

		/*

		 * Look for queue of fragments

		 * of this datagram.

		 */

		for (fp = (struct ipq *) ipq.next; fp != &ipq;

		     fp = (struct ipq *) 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;

	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;

		if (ip->ip_off & IP_MF)

		  ((struct ipasfrag *)ip)->ipf_mff |= 1;

		else

		  ((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) {

			STAT(ipstat.ips_fragments++);

			ip = ip_reass((struct ipasfrag *)ip, fp);

			if (ip == 0)

				return;

			STAT(ipstat.ips_reassembled++);

			m = dtom(ip);

		} else

			if (fp)

		   	   ip_freef(fp);

	} else

		ip->ip_len -= hlen;

	/*

	 * Switch out to protocol's input routine.

	 */

	STAT(ipstat.ips_delivered++);

	switch (ip->ip_p) {

	 case IPPROTO_TCP:

		tcp_input(m, hlen, (struct socket *)NULL);

		break;

	 case IPPROTO_UDP:

		udp_input(m, hlen);

		break;

	 case IPPROTO_ICMP:

		icmp_input(m, hlen);

		break;

	 default:

		STAT(ipstat.ips_noproto++);

		m_free(m);

	}

	return;

bad:

	m_freem(m);

	return;

}

/*

 * 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(register struct ipasfrag *ip, register struct ipq *fp)

{

	register struct mbuf *m = dtom(ip);

	register struct ipasfrag *q;

	int hlen = ip->ip_hl << 2;

	int i, next;

	DEBUG_CALL("ip_reass");

	DEBUG_ARG("ip = %lx", (long)ip);

	DEBUG_ARG("fp = %lx", (long)fp);

	DEBUG_ARG("m = %lx", (long)m);

	/*

	 * Presence of header sizes in mbufs

	 * would confuse code below.

         * Fragment m_data is concatenated.

	 */

	m->m_data += hlen;

	m->m_len -= hlen;

	/*

	 * If first fragment to arrive, create a reassembly queue.

	 */

	if (fp == 0) {

	  struct mbuf *t;

	  if ((t = m_get()) == NULL) goto dropfrag;

	  fp = mtod(t, struct ipq *);

	  insque_32(fp, &ipq);

	  fp->ipq_ttl = IPFRAGTTL;

	  fp->ipq_p = ip->ip_p;

	  fp->ipq_id = ip->ip_id;

	  fp->ipq_next = fp->ipq_prev = (ipasfragp_32)fp;

	  fp->ipq_src = ((struct ip *)ip)->ip_src;

	  fp->ipq_dst = ((struct ip *)ip)->ip_dst;

	  q = (struct ipasfrag *)fp;

	  goto insert;

	}

	/*

	 * Find a segment which begins after this one does.

	 */

	for (q = (struct ipasfrag *)fp->ipq_next; q != (struct ipasfrag *)fp;

	    q = (struct ipasfrag *)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 != (ipasfragp_32)fp) {

		i = ((struct ipasfrag *)(q->ipf_prev))->ip_off +

		  ((struct ipasfrag *)(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) {

		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;

		}

		q = (struct ipasfrag *) q->ipf_next;

		m_freem(dtom((struct ipasfrag *) q->ipf_prev));

		ip_deq((struct ipasfrag *) q->ipf_prev);

	}

insert:

	/*

	 * Stick new segment in its place;

	 * check for complete reassembly.

	 */

	ip_enq(ip, (struct ipasfrag *) q->ipf_prev);

	next = 0;

	for (q = (struct ipasfrag *) fp->ipq_next; q != (struct ipasfrag *)fp;

	     q = (struct ipasfrag *) q->ipf_next) {

		if (q->ip_off != next)

			return (0);

		next += q->ip_len;

	}

	if (((struct ipasfrag *)(q->ipf_prev))->ipf_mff & 1)

		return (0);

	/*

	 * Reassembly is complete; concatenate fragments.

	 */

	q = (struct ipasfrag *) fp->ipq_next;

	m = dtom(q);

	q = (struct ipasfrag *) q->ipf_next;

	while (q != (struct ipasfrag *)fp) {

	  struct mbuf *t;

	  t = dtom(q);

	  q = (struct ipasfrag *) q->ipf_next;

	  m_cat(m, t);

	}

	/*

	 * Create header for new ip packet by

	 * modifying header of first packet;

	 * dequeue and discard fragment reassembly header.

	 * Make header visible.

	 */

	ip = (struct ipasfrag *) fp->ipq_next;

	/*

	 * If the fragments concatenated to an mbuf that's

	 * bigger than the total size of the fragment, then and

	 * m_ext buffer was alloced. But fp->ipq_next points to

	 * the old buffer (in the mbuf), so we must point ip

	 * into the new buffer.

	 */

	if (m->m_flags & M_EXT) {

	  int delta;

	  delta = (char *)ip - m->m_dat;

	  ip = (struct ipasfrag *)(m->m_ext + delta);

	}

	/* DEBUG_ARG("ip = %lx", (long)ip);

	 * ip=(struct ipasfrag *)m->m_data; */

	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_32(fp);

	(void) m_free(dtom(fp));

	m = dtom(ip);

	m->m_len += (ip->ip_hl << 2);

	m->m_data -= (ip->ip_hl << 2);

	return ((struct ip *)ip);

dropfrag:

	STAT(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 = (struct ipasfrag *) fp->ipq_next; q != (struct ipasfrag *)fp;

	    q = p) {

		p = (struct ipasfrag *) q->ipf_next;

		ip_deq(q);

		m_freem(dtom(q));

	}

	remque_32(fp);

	(void) m_free(dtom(fp));

}

/*

 * Put an ip fragment on a reassembly chain.

 * Like insque, but pointers in middle of structure.

 */

static void

ip_enq(register struct ipasfrag *p, register struct ipasfrag *prev)

{

	DEBUG_CALL("ip_enq");

	DEBUG_ARG("prev = %lx", (long)prev);

	p->ipf_prev = (ipasfragp_32) prev;

	p->ipf_next = prev->ipf_next;

	((struct ipasfrag *)(prev->ipf_next))->ipf_prev = (ipasfragp_32) p;

	prev->ipf_next = (ipasfragp_32) p;

}

/*

 * To ip_enq as remque is to insque.

 */

static void

ip_deq(register struct ipasfrag *p)

{

	((struct ipasfrag *)(p->ipf_prev))->ipf_next = p->ipf_next;

	((struct ipasfrag *)(p->ipf_next))->ipf_prev = p->ipf_prev;

}

/*

 * IP timer processing;

 * if a timer expires on a reassembly

 * queue, discard it.

 */

void

ip_slowtimo()

{

	register struct ipq *fp;

	DEBUG_CALL("ip_slowtimo");

	fp = (struct ipq *) ipq.next;

	if (fp == 0)

	   return;

	while (fp != &ipq) {

		--fp->ipq_ttl;

		fp = (struct ipq *) fp->next;

		if (((struct ipq *)(fp->prev))->ipq_ttl == 0) {

			STAT(ipstat.ips_fragtimeout++);

			ip_freef((struct ipq *) fp->prev);

		}

	}

}

/*

 * 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.

 */

#ifdef notdef

int

ip_dooptions(m)

	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; */

	int opt, optlen, cnt, off, code, type, forward = 0;

	struct in_addr *sin, dst;

typedef u_int32_t n_time;

	n_time ntime;

	dst = ip->ip_dst;

	cp = (u_char *)(ip + 1);

	cnt = (ip->ip_hl << 2) - sizeof (struct ip);

	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;