src/slirp/ip_input.c

/*
 * 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"

int ip_defttl;
struct ipstat ipstat;
struct ipq ipq;

/*
 * 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_defttl = IPDEFTTL;
}

/*
 * 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);

        ipstat.ips_total++;
        
        if (m->m_len < sizeof (struct ip)) {
                ipstat.ips_toosmall++;
                return;
        }
        
        ip = mtod(m, struct ip *);
        
        if (ip->ip_v != IPVERSION) {
                ipstat.ips_badvers++;
                goto bad;
        }

        hlen = ip->ip_hl << 2;
        if (hlen<sizeof(struct ip ) || hlen>m->m_len) {/* min header length */
          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)) {
          ipstat.ips_badsum++;
          goto bad;
        }

        /*
         * Convert fields to host representation.
         */
        NTOHS(ip->ip_len);
        if (ip->ip_len < hlen) {
                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) {
                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) {
                        ipstat.ips_fragments++;
                        ip = ip_reass((struct ipasfrag *)ip, fp);
                        if (ip == 0)
                                return;
                        ipstat.ips_reassembled++;
                        m = dtom(ip);
                } else
                        if (fp)
                           ip_freef(fp);

        } else
                ip->ip_len -= hlen;

        /*
         * Switch out to protocol's input routine.
         */
        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:
                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.
 */
struct ip *
ip_reass(ip, fp)
        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);
          m_cat(m, t);
          q = (struct ipasfrag *) q->ipf_next;
        }

        /*
         * 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:
        ipstat.ips_fragdropped++;
        m_freem(m);
        return (0);
}

/*
 * Free a fragment reassembly header and all
 * associated datagrams.
 */
void
ip_freef(fp)
        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.
 */
void
ip_enq(p, prev)
        register struct ipasfrag *p, *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.
 */
void
ip_deq(p)
        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) {
                        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;
                        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;
                                }
                                /*
                                 * 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.
                                 */
                                save_rte(cp, ip->ip_src);
                                break;
                        }
                        /*
                         * locate outgoing interface
                         */
                        bcopy((caddr_t)(cp + off), (caddr_t)&ipaddr.sin_addr,
                            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;
                        bcopy((caddr_t)&(IA_SIN(ia)->sin_addr),
                            (caddr_t)(cp + off), 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;
                        bcopy((caddr_t)(&ip->ip_dst), (caddr_t)&ipaddr.sin_addr,
                            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;
                        }
                        bcopy((caddr_t)&(IA_SIN(ia)->sin_addr),
                            (caddr_t)(cp + off), 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 (int32_t)) {
                                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_ i f p foraddr((SA)&ipaddr,
                                                            m->m_pkthdr.rcvif);
                                if (ia == 0)
                                        continue;
                                bcopy((caddr_t)&IA_SIN(ia)->sin_addr,
                                    (caddr_t)sin, 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;
                                bcopy((caddr_t)sin, (caddr_t)&ipaddr.sin_addr,
                                    sizeof(struct in_addr));
                                if (ifa_ifwithaddr((SA)&ipaddr) == 0)
                                        continue;
                                ipt->ipt_ptr += sizeof(struct in_addr);
                                break;

                        default:
                                goto bad;
                        }
                        ntime = iptime();
                        bcopy((caddr_t)&ntime, (caddr_t)cp + ipt->ipt_ptr - 1,
                            sizeof(n_time));
                        ipt->ipt_ptr += sizeof(n_time);
                }
        }
        if (forward) {
                ip_forward(m, 1);
                return (1);
        }
                }
        }
        return (0);
bad:
        /* ip->ip_len -= ip->ip_hl << 2;   XXX icmp_error adds in hdr length */

/* Not yet */
        icmp_error(m, type, code, 0, 0);

        ipstat.ips_badoptions++;
        return (1);
}

#endif /* notdef */

/*
 * 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(m, mopt)
        register struct mbuf *m;
        struct mbuf *mopt;
{
        register int i;
        struct ip *ip = mtod(m, struct ip *);
        register caddr_t opts;
        int olen;

        olen = (ip->ip_hl<<2) - sizeof (struct ip);
        opts = (caddr_t)(ip + 1);
        i = m->m_len - (sizeof (struct ip) + olen);
        memcpy(opts, opts  + olen, (unsigned)i);
        m->m_len -= olen;
        
        ip->ip_hl = sizeof(struct ip) >> 2;
}
Revision:	1.1
Committed:	2005-05-13T09:00:59Z (19 years ago) by gbeauche
Content type:	text/plain
Branch:	MAIN
CVS Tags:	nigel-build-17
Log Message:	slirp user mode network emulation code from qemu
#	User	Rev	Content
1	gbeauche	1.1	/*
2			* Copyright (c) 1982, 1986, 1988, 1993
3			* The Regents of the University of California. All rights reserved.
4			*
5			* Redistribution and use in source and binary forms, with or without
6			* modification, are permitted provided that the following conditions
7			* are met:
8			* 1. Redistributions of source code must retain the above copyright
9			* notice, this list of conditions and the following disclaimer.
10			* 2. Redistributions in binary form must reproduce the above copyright
11			* notice, this list of conditions and the following disclaimer in the
12			* documentation and/or other materials provided with the distribution.
13			* 3. All advertising materials mentioning features or use of this software
14			* must display the following acknowledgement:
15			* This product includes software developed by the University of
16			* California, Berkeley and its contributors.
17			* 4. Neither the name of the University nor the names of its contributors
18			* may be used to endorse or promote products derived from this software
19			* without specific prior written permission.
20			*
21			* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22			* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23			* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24			* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25			* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26			* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27			* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28			* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29			* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30			* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31			* SUCH DAMAGE.
32			*
33			* @(#)ip_input.c 8.2 (Berkeley) 1/4/94
34			* ip_input.c,v 1.11 1994/11/16 10:17:08 jkh Exp
35			*/
36
37			/*
38			* Changes and additions relating to SLiRP are
39			* Copyright (c) 1995 Danny Gasparovski.
40			*
41			* Please read the file COPYRIGHT for the
42			* terms and conditions of the copyright.
43			*/
44
45			#include <slirp.h>
46			#include "ip_icmp.h"
47
48			int ip_defttl;
49			struct ipstat ipstat;
50			struct ipq ipq;
51
52			/*
53			* IP initialization: fill in IP protocol switch table.
54			* All protocols not implemented in kernel go to raw IP protocol handler.
55			*/
56			void
57			ip_init()
58			{
59			ipq.next = ipq.prev = (ipqp_32)&ipq;
60			ip_id = tt.tv_sec & 0xffff;
61			udp_init();
62			tcp_init();
63			ip_defttl = IPDEFTTL;
64			}
65
66			/*
67			* Ip input routine. Checksum and byte swap header. If fragmented
68			* try to reassemble. Process options. Pass to next level.
69			*/
70			void
71			ip_input(m)
72			struct mbuf *m;
73			{
74			register struct ip *ip;
75			int hlen;
76
77			DEBUG_CALL("ip_input");
78			DEBUG_ARG("m = %lx", (long)m);
79			DEBUG_ARG("m_len = %d", m->m_len);
80
81			ipstat.ips_total++;
82
83			if (m->m_len < sizeof (struct ip)) {
84			ipstat.ips_toosmall++;
85			return;
86			}
87
88			ip = mtod(m, struct ip *);
89
90			if (ip->ip_v != IPVERSION) {
91			ipstat.ips_badvers++;
92			goto bad;
93			}
94
95			hlen = ip->ip_hl << 2;
96			if (hlen<sizeof(struct ip ) \|\| hlen>m->m_len) {/* min header length */
97			ipstat.ips_badhlen++; /* or packet too short */
98			goto bad;
99			}
100
101			/* keep ip header intact for ICMP reply
102			* ip->ip_sum = cksum(m, hlen);
103			* if (ip->ip_sum) {
104			*/
105			if(cksum(m,hlen)) {
106			ipstat.ips_badsum++;
107			goto bad;
108			}
109
110			/*
111			* Convert fields to host representation.
112			*/
113			NTOHS(ip->ip_len);
114			if (ip->ip_len < hlen) {
115			ipstat.ips_badlen++;
116			goto bad;
117			}
118			NTOHS(ip->ip_id);
119			NTOHS(ip->ip_off);
120
121			/*
122			* Check that the amount of data in the buffers
123			* is as at least much as the IP header would have us expect.
124			* Trim mbufs if longer than we expect.
125			* Drop packet if shorter than we expect.
126			*/
127			if (m->m_len < ip->ip_len) {
128			ipstat.ips_tooshort++;
129			goto bad;
130			}
131			/* Should drop packet if mbuf too long? hmmm... */
132			if (m->m_len > ip->ip_len)
133			m_adj(m, ip->ip_len - m->m_len);
134
135			/* check ip_ttl for a correct ICMP reply */
136			if(ip->ip_ttl==0 \|\| ip->ip_ttl==1) {
137			icmp_error(m, ICMP_TIMXCEED,ICMP_TIMXCEED_INTRANS, 0,"ttl");
138			goto bad;
139			}
140
141			/*
142			* Process options and, if not destined for us,
143			* ship it on. ip_dooptions returns 1 when an
144			* error was detected (causing an icmp message
145			* to be sent and the original packet to be freed).
146			*/
147			/* We do no IP options */
148			/* if (hlen > sizeof (struct ip) && ip_dooptions(m))
149			* goto next;
150			*/
151			/*
152			* If offset or IP_MF are set, must reassemble.
153			* Otherwise, nothing need be done.
154			* (We could look in the reassembly queue to see
155			* if the packet was previously fragmented,
156			* but it's not worth the time; just let them time out.)
157			*
158			* XXX This should fail, don't fragment yet
159			*/
160			if (ip->ip_off &~ IP_DF) {
161			register struct ipq *fp;
162			/*
163			* Look for queue of fragments
164			* of this datagram.
165			*/
166			for (fp = (struct ipq *) ipq.next; fp != &ipq;
167			fp = (struct ipq *) fp->next)
168			if (ip->ip_id == fp->ipq_id &&
169			ip->ip_src.s_addr == fp->ipq_src.s_addr &&
170			ip->ip_dst.s_addr == fp->ipq_dst.s_addr &&
171			ip->ip_p == fp->ipq_p)
172			goto found;
173			fp = 0;
174			found:
175
176			/*
177			* Adjust ip_len to not reflect header,
178			* set ip_mff if more fragments are expected,
179			* convert offset of this to bytes.
180			*/
181			ip->ip_len -= hlen;
182			if (ip->ip_off & IP_MF)
183			((struct ipasfrag *)ip)->ipf_mff \|= 1;
184			else
185			((struct ipasfrag *)ip)->ipf_mff &= ~1;
186
187			ip->ip_off <<= 3;
188
189			/*
190			* If datagram marked as having more fragments
191			* or if this is not the first fragment,
192			* attempt reassembly; if it succeeds, proceed.
193			*/
194			if (((struct ipasfrag *)ip)->ipf_mff & 1 \|\| ip->ip_off) {
195			ipstat.ips_fragments++;
196			ip = ip_reass((struct ipasfrag *)ip, fp);
197			if (ip == 0)
198			return;
199			ipstat.ips_reassembled++;
200			m = dtom(ip);
201			} else
202			if (fp)
203			ip_freef(fp);
204
205			} else
206			ip->ip_len -= hlen;
207
208			/*
209			* Switch out to protocol's input routine.
210			*/
211			ipstat.ips_delivered++;
212			switch (ip->ip_p) {
213			case IPPROTO_TCP:
214			tcp_input(m, hlen, (struct socket *)NULL);
215			break;
216			case IPPROTO_UDP:
217			udp_input(m, hlen);
218			break;
219			case IPPROTO_ICMP:
220			icmp_input(m, hlen);
221			break;
222			default:
223			ipstat.ips_noproto++;
224			m_free(m);
225			}
226			return;
227			bad:
228			m_freem(m);
229			return;
230			}
231
232			/*
233			* Take incoming datagram fragment and try to
234			* reassemble it into whole datagram. If a chain for
235			* reassembly of this datagram already exists, then it
236			* is given as fp; otherwise have to make a chain.
237			*/
238			struct ip *
239			ip_reass(ip, fp)
240			register struct ipasfrag *ip;
241			register struct ipq *fp;
242			{
243			register struct mbuf *m = dtom(ip);
244			register struct ipasfrag *q;
245			int hlen = ip->ip_hl << 2;
246			int i, next;
247
248			DEBUG_CALL("ip_reass");
249			DEBUG_ARG("ip = %lx", (long)ip);
250			DEBUG_ARG("fp = %lx", (long)fp);
251			DEBUG_ARG("m = %lx", (long)m);
252
253			/*
254			* Presence of header sizes in mbufs
255			* would confuse code below.
256			* Fragment m_data is concatenated.
257			*/
258			m->m_data += hlen;
259			m->m_len -= hlen;
260
261			/*
262			* If first fragment to arrive, create a reassembly queue.
263			*/
264			if (fp == 0) {
265			struct mbuf *t;
266			if ((t = m_get()) == NULL) goto dropfrag;
267			fp = mtod(t, struct ipq *);
268			insque_32(fp, &ipq);
269			fp->ipq_ttl = IPFRAGTTL;
270			fp->ipq_p = ip->ip_p;
271			fp->ipq_id = ip->ip_id;
272			fp->ipq_next = fp->ipq_prev = (ipasfragp_32)fp;
273			fp->ipq_src = ((struct ip *)ip)->ip_src;
274			fp->ipq_dst = ((struct ip *)ip)->ip_dst;
275			q = (struct ipasfrag *)fp;
276			goto insert;
277			}
278
279			/*
280			* Find a segment which begins after this one does.
281			*/
282			for (q = (struct ipasfrag )fp->ipq_next; q != (struct ipasfrag )fp;
283			q = (struct ipasfrag *)q->ipf_next)
284			if (q->ip_off > ip->ip_off)
285			break;
286
287			/*
288			* If there is a preceding segment, it may provide some of
289			* our data already. If so, drop the data from the incoming
290			* segment. If it provides all of our data, drop us.
291			*/
292			if (q->ipf_prev != (ipasfragp_32)fp) {
293			i = ((struct ipasfrag *)(q->ipf_prev))->ip_off +
294			((struct ipasfrag *)(q->ipf_prev))->ip_len - ip->ip_off;
295			if (i > 0) {
296			if (i >= ip->ip_len)
297			goto dropfrag;
298			m_adj(dtom(ip), i);
299			ip->ip_off += i;
300			ip->ip_len -= i;
301			}
302			}
303
304			/*
305			* While we overlap succeeding segments trim them or,
306			* if they are completely covered, dequeue them.
307			*/
308			while (q != (struct ipasfrag *)fp && ip->ip_off + ip->ip_len > q->ip_off) {
309			i = (ip->ip_off + ip->ip_len) - q->ip_off;
310			if (i < q->ip_len) {
311			q->ip_len -= i;
312			q->ip_off += i;
313			m_adj(dtom(q), i);
314			break;
315			}
316			q = (struct ipasfrag *) q->ipf_next;
317			m_freem(dtom((struct ipasfrag *) q->ipf_prev));
318			ip_deq((struct ipasfrag *) q->ipf_prev);
319			}
320
321			insert:
322			/*
323			* Stick new segment in its place;
324			* check for complete reassembly.
325			*/
326			ip_enq(ip, (struct ipasfrag *) q->ipf_prev);
327			next = 0;
328			for (q = (struct ipasfrag ) fp->ipq_next; q != (struct ipasfrag )fp;
329			q = (struct ipasfrag *) q->ipf_next) {
330			if (q->ip_off != next)
331			return (0);
332			next += q->ip_len;
333			}
334			if (((struct ipasfrag *)(q->ipf_prev))->ipf_mff & 1)
335			return (0);
336
337			/*
338			* Reassembly is complete; concatenate fragments.
339			*/
340			q = (struct ipasfrag *) fp->ipq_next;
341			m = dtom(q);
342
343			q = (struct ipasfrag *) q->ipf_next;
344			while (q != (struct ipasfrag *)fp) {
345			struct mbuf *t;
346			t = dtom(q);
347			m_cat(m, t);
348			q = (struct ipasfrag *) q->ipf_next;
349			}
350
351			/*
352			* Create header for new ip packet by
353			* modifying header of first packet;
354			* dequeue and discard fragment reassembly header.
355			* Make header visible.
356			*/
357			ip = (struct ipasfrag *) fp->ipq_next;
358
359			/*
360			* If the fragments concatenated to an mbuf that's
361			* bigger than the total size of the fragment, then and
362			* m_ext buffer was alloced. But fp->ipq_next points to
363			* the old buffer (in the mbuf), so we must point ip
364			* into the new buffer.
365			*/
366			if (m->m_flags & M_EXT) {
367			int delta;
368			delta = (char *)ip - m->m_dat;
369			ip = (struct ipasfrag *)(m->m_ext + delta);
370			}
371
372			/* DEBUG_ARG("ip = %lx", (long)ip);
373			* ip=(struct ipasfrag )m->m_data; /
374
375			ip->ip_len = next;
376			ip->ipf_mff &= ~1;
377			((struct ip *)ip)->ip_src = fp->ipq_src;
378			((struct ip *)ip)->ip_dst = fp->ipq_dst;
379			remque_32(fp);
380			(void) m_free(dtom(fp));
381			m = dtom(ip);
382			m->m_len += (ip->ip_hl << 2);
383			m->m_data -= (ip->ip_hl << 2);
384
385			return ((struct ip *)ip);
386
387			dropfrag:
388			ipstat.ips_fragdropped++;
389			m_freem(m);
390			return (0);
391			}
392
393			/*
394			* Free a fragment reassembly header and all
395			* associated datagrams.
396			*/
397			void
398			ip_freef(fp)
399			struct ipq *fp;
400			{
401			register struct ipasfrag q, p;
402
403			for (q = (struct ipasfrag ) fp->ipq_next; q != (struct ipasfrag )fp;
404			q = p) {
405			p = (struct ipasfrag *) q->ipf_next;
406			ip_deq(q);
407			m_freem(dtom(q));
408			}
409			remque_32(fp);
410			(void) m_free(dtom(fp));
411			}
412
413			/*
414			* Put an ip fragment on a reassembly chain.
415			* Like insque, but pointers in middle of structure.
416			*/
417			void
418			ip_enq(p, prev)
419			register struct ipasfrag p, prev;
420			{
421			DEBUG_CALL("ip_enq");
422			DEBUG_ARG("prev = %lx", (long)prev);
423			p->ipf_prev = (ipasfragp_32) prev;
424			p->ipf_next = prev->ipf_next;
425			((struct ipasfrag *)(prev->ipf_next))->ipf_prev = (ipasfragp_32) p;
426			prev->ipf_next = (ipasfragp_32) p;
427			}
428
429			/*
430			* To ip_enq as remque is to insque.
431			*/
432			void
433			ip_deq(p)
434			register struct ipasfrag *p;
435			{
436			((struct ipasfrag *)(p->ipf_prev))->ipf_next = p->ipf_next;
437			((struct ipasfrag *)(p->ipf_next))->ipf_prev = p->ipf_prev;
438			}
439
440			/*
441			* IP timer processing;
442			* if a timer expires on a reassembly
443			* queue, discard it.
444			*/
445			void
446			ip_slowtimo()
447			{
448			register struct ipq *fp;
449
450			DEBUG_CALL("ip_slowtimo");
451
452			fp = (struct ipq *) ipq.next;
453			if (fp == 0)
454			return;
455
456			while (fp != &ipq) {
457			--fp->ipq_ttl;
458			fp = (struct ipq *) fp->next;
459			if (((struct ipq *)(fp->prev))->ipq_ttl == 0) {
460			ipstat.ips_fragtimeout++;
461			ip_freef((struct ipq *) fp->prev);
462			}
463			}
464			}
465
466			/*
467			* Do option processing on a datagram,
468			* possibly discarding it if bad options are encountered,
469			* or forwarding it if source-routed.
470			* Returns 1 if packet has been forwarded/freed,
471			* 0 if the packet should be processed further.
472			*/
473
474			#ifdef notdef
475
476			int
477			ip_dooptions(m)
478			struct mbuf *m;
479			{
480			register struct ip ip = mtod(m, struct ip );
481			register u_char *cp;
482			register struct ip_timestamp *ipt;
483			register struct in_ifaddr *ia;
484			/* int opt, optlen, cnt, off, code, type = ICMP_PARAMPROB, forward = 0; */
485			int opt, optlen, cnt, off, code, type, forward = 0;
486			struct in_addr *sin, dst;
487			typedef u_int32_t n_time;
488			n_time ntime;
489
490			dst = ip->ip_dst;
491			cp = (u_char *)(ip + 1);
492			cnt = (ip->ip_hl << 2) - sizeof (struct ip);
493			for (; cnt > 0; cnt -= optlen, cp += optlen) {
494			opt = cp[IPOPT_OPTVAL];
495			if (opt == IPOPT_EOL)
496			break;
497			if (opt == IPOPT_NOP)
498			optlen = 1;
499			else {
500			optlen = cp[IPOPT_OLEN];
501			if (optlen <= 0 \|\| optlen > cnt) {
502			code = &cp[IPOPT_OLEN] - (u_char *)ip;
503			goto bad;
504			}
505			}
506			switch (opt) {
507
508			default:
509			break;
510
511			/*
512			* Source routing with record.
513			* Find interface with current destination address.
514			* If none on this machine then drop if strictly routed,
515			* or do nothing if loosely routed.
516			* Record interface address and bring up next address
517			* component. If strictly routed make sure next
518			* address is on directly accessible net.
519			*/
520			case IPOPT_LSRR:
521			case IPOPT_SSRR:
522			if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) {
523			code = &cp[IPOPT_OFFSET] - (u_char *)ip;
524			goto bad;
525			}
526			ipaddr.sin_addr = ip->ip_dst;
527			ia = (struct in_ifaddr *)
528			ifa_ifwithaddr((struct sockaddr *)&ipaddr);
529			if (ia == 0) {
530			if (opt == IPOPT_SSRR) {
531			type = ICMP_UNREACH;
532			code = ICMP_UNREACH_SRCFAIL;
533			goto bad;
534			}
535			/*
536			* Loose routing, and not at next destination
537			* yet; nothing to do except forward.
538			*/
539			break;
540			}
541			off--; / * 0 origin * /
542			if (off > optlen - sizeof(struct in_addr)) {
543			/*
544			* End of source route. Should be for us.
545			*/
546			save_rte(cp, ip->ip_src);
547			break;
548			}
549			/*
550			* locate outgoing interface
551			*/
552			bcopy((caddr_t)(cp + off), (caddr_t)&ipaddr.sin_addr,
553			sizeof(ipaddr.sin_addr));
554			if (opt == IPOPT_SSRR) {
555			#define INA struct in_ifaddr *
556			#define SA struct sockaddr *
557			if ((ia = (INA)ifa_ifwithdstaddr((SA)&ipaddr)) == 0)
558			ia = (INA)ifa_ifwithnet((SA)&ipaddr);
559			} else
560			ia = ip_rtaddr(ipaddr.sin_addr);
561			if (ia == 0) {
562			type = ICMP_UNREACH;
563			code = ICMP_UNREACH_SRCFAIL;
564			goto bad;
565			}
566			ip->ip_dst = ipaddr.sin_addr;
567			bcopy((caddr_t)&(IA_SIN(ia)->sin_addr),
568			(caddr_t)(cp + off), sizeof(struct in_addr));
569			cp[IPOPT_OFFSET] += sizeof(struct in_addr);
570			/*
571			* Let ip_intr's mcast routing check handle mcast pkts
572			*/
573			forward = !IN_MULTICAST(ntohl(ip->ip_dst.s_addr));
574			break;
575
576			case IPOPT_RR:
577			if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) {
578			code = &cp[IPOPT_OFFSET] - (u_char *)ip;
579			goto bad;
580			}
581			/*
582			* If no space remains, ignore.
583			*/
584			off--; * 0 origin *
585			if (off > optlen - sizeof(struct in_addr))
586			break;
587			bcopy((caddr_t)(&ip->ip_dst), (caddr_t)&ipaddr.sin_addr,
588			sizeof(ipaddr.sin_addr));
589			/*
590			* locate outgoing interface; if we're the destination,
591			* use the incoming interface (should be same).
592			*/
593			if ((ia = (INA)ifa_ifwithaddr((SA)&ipaddr)) == 0 &&
594			(ia = ip_rtaddr(ipaddr.sin_addr)) == 0) {
595			type = ICMP_UNREACH;
596			code = ICMP_UNREACH_HOST;
597			goto bad;
598			}
599			bcopy((caddr_t)&(IA_SIN(ia)->sin_addr),
600			(caddr_t)(cp + off), sizeof(struct in_addr));
601			cp[IPOPT_OFFSET] += sizeof(struct in_addr);
602			break;
603
604			case IPOPT_TS:
605			code = cp - (u_char *)ip;
606			ipt = (struct ip_timestamp *)cp;
607			if (ipt->ipt_len < 5)
608			goto bad;
609			if (ipt->ipt_ptr > ipt->ipt_len - sizeof (int32_t)) {
610			if (++ipt->ipt_oflw == 0)
611			goto bad;
612			break;
613			}
614			sin = (struct in_addr *)(cp + ipt->ipt_ptr - 1);
615			switch (ipt->ipt_flg) {
616
617			case IPOPT_TS_TSONLY:
618			break;
619
620			case IPOPT_TS_TSANDADDR:
621			if (ipt->ipt_ptr + sizeof(n_time) +
622			sizeof(struct in_addr) > ipt->ipt_len)
623			goto bad;
624			ipaddr.sin_addr = dst;
625			ia = (INA)ifaof_ i f p foraddr((SA)&ipaddr,
626			m->m_pkthdr.rcvif);
627			if (ia == 0)
628			continue;
629			bcopy((caddr_t)&IA_SIN(ia)->sin_addr,
630			(caddr_t)sin, sizeof(struct in_addr));
631			ipt->ipt_ptr += sizeof(struct in_addr);
632			break;
633
634			case IPOPT_TS_PRESPEC:
635			if (ipt->ipt_ptr + sizeof(n_time) +
636			sizeof(struct in_addr) > ipt->ipt_len)
637			goto bad;
638			bcopy((caddr_t)sin, (caddr_t)&ipaddr.sin_addr,
639			sizeof(struct in_addr));
640			if (ifa_ifwithaddr((SA)&ipaddr) == 0)
641			continue;
642			ipt->ipt_ptr += sizeof(struct in_addr);
643			break;
644
645			default:
646			goto bad;
647			}
648			ntime = iptime();
649			bcopy((caddr_t)&ntime, (caddr_t)cp + ipt->ipt_ptr - 1,
650			sizeof(n_time));
651			ipt->ipt_ptr += sizeof(n_time);
652			}
653			}
654			if (forward) {
655			ip_forward(m, 1);
656			return (1);
657			}
658			}
659			}
660			return (0);
661			bad:
662			/* ip->ip_len -= ip->ip_hl << 2; XXX icmp_error adds in hdr length */
663
664			/* Not yet */
665			icmp_error(m, type, code, 0, 0);
666
667			ipstat.ips_badoptions++;
668			return (1);
669			}
670
671			#endif /* notdef */
672
673			/*
674			* Strip out IP options, at higher
675			* level protocol in the kernel.
676			* Second argument is buffer to which options
677			* will be moved, and return value is their length.
678			* (XXX) should be deleted; last arg currently ignored.
679			*/
680			void
681			ip_stripoptions(m, mopt)
682			register struct mbuf *m;
683			struct mbuf *mopt;
684			{
685			register int i;
686			struct ip ip = mtod(m, struct ip );
687			register caddr_t opts;
688			int olen;
689
690			olen = (ip->ip_hl<<2) - sizeof (struct ip);
691			opts = (caddr_t)(ip + 1);
692			i = m->m_len - (sizeof (struct ip) + olen);
693			memcpy(opts, opts + olen, (unsigned)i);
694			m->m_len -= olen;
695
696			ip->ip_hl = sizeof(struct ip) >> 2;
697			}