ip_input.c revision 3d061451ecc0fa7baa94211f5038ee56a60ebc0f
/*
* 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"
/*
* IP initialization: fill in IP protocol switch table.
* All protocols not implemented in kernel go to raw IP protocol handler.
*/
void
ip_init(PNATState pData)
{
int i = 0;
for (i = 0; i < IPREASS_NHASH; ++i)
TAILQ_INIT(&ipq[i]);
maxnipq = 100; /* ??? */
maxfragsperpacket = 16;
nipq = 0;
ip_currid = tt.tv_sec & 0xffff;
udp_init(pData);
tcp_init(pData);
}
/*
* Ip input routine. Checksum and byte swap header. If fragmented
* try to reassemble. Process options. Pass to next level.
*/
void
ip_input(PNATState pData, 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(pData, m, ICMP_TIMXCEED,ICMP_TIMXCEED_INTRANS, 0,"ttl");
goto bad;
}
ip->ip_ttl--;
/*
* 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_MF | IP_OFFMASK))
{
m = ip_reass(pData, m);
if (m == NULL)
return;
ip = mtod(m, struct ip *);
hlen = ip->ip_len;
}
else
ip->ip_len -= hlen;
/*
* Switch out to protocol's input routine.
*/
ipstat.ips_delivered++;
switch (ip->ip_p)
{
case IPPROTO_TCP:
tcp_input(pData, m, hlen, (struct socket *)NULL);
break;
case IPPROTO_UDP:
udp_input(pData, m, hlen);
break;
case IPPROTO_ICMP:
icmp_input(pData, m, hlen);
break;
default:
ipstat.ips_noproto++;
m_free(pData, m);
}
return;
bad:
m_freem(pData, m);
return;
}
struct mbuf *
ip_reass(PNATState pData, struct mbuf* m)
{
struct ip *ip;
struct mbuf *p, *q, *nq;
struct ipq_t *fp = NULL;
struct ipqhead *head;
int i, hlen, next;
u_short hash;
/* If maxnipq or maxfragsperpacket are 0, never accept fragments. */
if ( maxnipq == 0
|| maxfragsperpacket == 0)
{
ipstat.ips_fragments++;
ipstat.ips_fragdropped++;
m_freem(pData, m);
return (NULL);
}
ip = mtod(m, struct ip *);
hlen = ip->ip_hl << 2;
hash = IPREASS_HASH(ip->ip_src.s_addr, ip->ip_id);
head = &ipq[hash];
/*
* Look for queue of fragments
* of this datagram.
*/
TAILQ_FOREACH(fp, head, ipq_list)
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 = NULL;
/*
* Attempt to trim the number of allocated fragment queues if it
* exceeds the administrative limit.
*/
if ((nipq > maxnipq) && (maxnipq > 0))
{
/*
* drop something from the tail of the current queue
* before proceeding further
*/
struct ipq_t *q = TAILQ_LAST(head, ipqhead);
if (q == NULL)
{
/* gak */
for (i = 0; i < IPREASS_NHASH; i++)
{
struct ipq_t *r = TAILQ_LAST(&ipq[i], ipqhead);
if (r)
{
ipstat.ips_fragtimeout += r->ipq_nfrags;
ip_freef(pData, &ipq[i], r);
break;
}
}
}
else
{
ipstat.ips_fragtimeout += q->ipq_nfrags;
ip_freef(pData, head, q);
}
}
found:
/*
* Adjust ip_len to not reflect header,
* convert offset of this to bytes.
*/
ip->ip_len -= hlen;
if (ip->ip_off & IP_MF)
{
/*
* Make sure that fragments have a data length
* that's a non-zero multiple of 8 bytes.
*/
if (ip->ip_len == 0 || (ip->ip_len & 0x7) != 0)
{
ipstat.ips_toosmall++; /* XXX */
goto dropfrag;
}
m->m_flags |= M_FRAG;
}
else
m->m_flags &= ~M_FRAG;
ip->ip_off <<= 3;
/*
* Attempt reassembly; if it succeeds, proceed.
* ip_reass() will return a different mbuf.
*/
ipstat.ips_fragments++;
m->m_hdr.header = ip;
/* Previous ip_reass() started here. */
/*
* 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)
{
fp = RTMemAlloc(sizeof(struct ipq_t));
if (fp == NULL)
goto dropfrag;
TAILQ_INSERT_HEAD(head, fp, ipq_list);
nipq++;
fp->ipq_nfrags = 1;
fp->ipq_ttl = IPFRAGTTL;
fp->ipq_p = ip->ip_p;
fp->ipq_id = ip->ip_id;
fp->ipq_src = ip->ip_src;
fp->ipq_dst = ip->ip_dst;
fp->ipq_frags = m;
m->m_nextpkt = NULL;
goto done;
}
else
{
fp->ipq_nfrags++;
}
#define GETIP(m) ((struct ip*)((m)->m_hdr.header))
/*
* Find a segment which begins after this one does.
*/
for (p = NULL, q = fp->ipq_frags; q; p = q, q = q->m_nextpkt)
if (GETIP(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, otherwise
* stick new segment in the proper place.
*
* If some of the data is dropped from the the preceding
* segment, then it's checksum is invalidated.
*/
if (p)
{
i = GETIP(p)->ip_off + GETIP(p)->ip_len - ip->ip_off;
if (i > 0)
{
if (i >= ip->ip_len)
goto dropfrag;
m_adj(m, i);
ip->ip_off += i;
ip->ip_len -= i;
}
m->m_nextpkt = p->m_nextpkt;
p->m_nextpkt = m;
}
else
{
m->m_nextpkt = fp->ipq_frags;
fp->ipq_frags = m;
}
/*
* While we overlap succeeding segments trim them or,
* if they are completely covered, dequeue them.
*/
for (; q != NULL && ip->ip_off + ip->ip_len > GETIP(q)->ip_off;
q = nq)
{
i = (ip->ip_off + ip->ip_len) - GETIP(q)->ip_off;
if (i < GETIP(q)->ip_len)
{
GETIP(q)->ip_len -= i;
GETIP(q)->ip_off += i;
m_adj(q, i);
break;
}
nq = q->m_nextpkt;
m->m_nextpkt = nq;
ipstat.ips_fragdropped++;
fp->ipq_nfrags--;
m_freem(pData, q);
}
/*
* Check for complete reassembly and perform frag per packet
* limiting.
*
* Frag limiting is performed here so that the nth frag has
* a chance to complete the packet before we drop the packet.
* As a result, n+1 frags are actually allowed per packet, but
* only n will ever be stored. (n = maxfragsperpacket.)
*
*/
next = 0;
for (p = NULL, q = fp->ipq_frags; q; p = q, q = q->m_nextpkt)
{
if (GETIP(q)->ip_off != next)
{
if (fp->ipq_nfrags > maxfragsperpacket)
{
ipstat.ips_fragdropped += fp->ipq_nfrags;
ip_freef(pData, head, fp);
}
goto done;
}
next += GETIP(q)->ip_len;
}
/* Make sure the last packet didn't have the IP_MF flag */
if (p->m_flags & M_FRAG)
{
if (fp->ipq_nfrags > maxfragsperpacket)
{
ipstat.ips_fragdropped += fp->ipq_nfrags;
ip_freef(pData, head, fp);
}
goto done;
}
/*
* Reassembly is complete. Make sure the packet is a sane size.
*/
q = fp->ipq_frags;
ip = GETIP(q);
if (next + (ip->ip_hl << 2) > IP_MAXPACKET)
{
ipstat.ips_fragdropped += fp->ipq_nfrags;
ip_freef(pData, head, fp);
goto done;
}
/*
* Concatenate fragments.
*/
m = q;
nq = q->m_nextpkt;
q->m_nextpkt = NULL;
for (q = nq; q != NULL; q = nq)
{
nq = q->m_nextpkt;
q->m_nextpkt = NULL;
m_cat(pData, m, q);
}
/*
* Create header for new ip packet by modifying header of first
* packet; dequeue and discard fragment reassembly header.
* Make header visible.
*/
#if 0
ip->ip_len = (ip->ip_hl << 2) + next;
#else
ip->ip_len = next;
#endif
ip->ip_src = fp->ipq_src;
ip->ip_dst = fp->ipq_dst;
TAILQ_REMOVE(head, fp, ipq_list);
nipq--;
RTMemFree(fp);
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 0
if (m->m_flags & M_PKTHDR) /* XXX this should be done elsewhere */
m_fixhdr(m);
#endif
ipstat.ips_reassembled++;
return (m);
dropfrag:
ipstat.ips_fragdropped++;
if (fp != NULL)
fp->ipq_nfrags--;
m_freem(pData, m);
done:
return NULL;
#undef GETIP
}
void
ip_freef(PNATState pData, struct ipqhead *fhp, struct ipq_t *fp)
{
struct mbuf *q;
while (fp->ipq_frags)
{
q = fp->ipq_frags;
fp->ipq_frags = q->m_nextpkt;
m_freem(pData, q);
}
TAILQ_REMOVE(fhp, fp, ipq_list);
RTMemFree(fp);
nipq--;
}
/*
* IP timer processing;
* if a timer expires on a reassembly
* queue, discard it.
*/
void
ip_slowtimo(PNATState pData)
{
register struct ipq_t *fp;
/* XXX: the fragment expiration is the same but requier
* additional loop see (see ip_input.c in FreeBSD tree)
*/
int i;
DEBUG_CALL("ip_slowtimo");
for (i = 0; i < IPREASS_NHASH; i++)
{
for(fp = TAILQ_FIRST(&ipq[i]); fp;)
{
struct ipq_t *fpp;
fpp = fp;
fp = TAILQ_NEXT(fp, ipq_list);
if(--fpp->ipq_ttl == 0) {
ipstat.ips_fragtimeout += fpp->ipq_nfrags;
ip_freef(pData, &ipq[i], fpp);
}
}
}
/*
* If we are over the maximum number of fragments
* (due to the limit being lowered), drain off
* enough to get down to the new limit.
*/
if (maxnipq >= 0 && nipq > maxnipq)
{
for (i = 0; i < IPREASS_NHASH; i++)
{
while (nipq > maxnipq && !TAILQ_EMPTY(&ipq[i]))
{
ipstat.ips_fragdropped += TAILQ_FIRST(&ipq[i])->ipq_nfrags;
ip_freef(pData, &ipq[i], TAILQ_FIRST(&ipq[i]));
}
}
}
}
/*
* 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;
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;
}