ip_input.c revision bcacc87b5019dd907592a9025de8c1750269fdb0
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * Copyright (c) 1982, 1986, 1988, 1993
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * The Regents of the University of California. All rights reserved.
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * Redistribution and use in source and binary forms, with or without
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * modification, are permitted provided that the following conditions
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * are met:
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * 1. Redistributions of source code must retain the above copyright
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * notice, this list of conditions and the following disclaimer.
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * 2. Redistributions in binary form must reproduce the above copyright
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * notice, this list of conditions and the following disclaimer in the
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * documentation and/or other materials provided with the distribution.
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * 3. All advertising materials mentioning features or use of this software
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * must display the following acknowledgement:
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * This product includes software developed by the University of
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * California, Berkeley and its contributors.
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * 4. Neither the name of the University nor the names of its contributors
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * may be used to endorse or promote products derived from this software
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * without specific prior written permission.
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
f317a3a3712d9b82387b437ac621db3733d8c804krishna * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * SUCH DAMAGE.
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * @(#)ip_input.c 8.2 (Berkeley) 1/4/94
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * ip_input.c,v 1.11 1994/11/16 10:17:08 jkh Exp
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * Changes and additions relating to SLiRP are
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * Copyright (c) 1995 Danny Gasparovski.
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * Please read the file COPYRIGHT for the
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * terms and conditions of the copyright.
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * IP initialization: fill in IP protocol switch table.
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * All protocols not implemented in kernel go to raw IP protocol handler.
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm int i = 0;
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm for (i = 0; i < IPREASS_NHASH; ++i)
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * Ip input routine. Checksum and byte swap header. If fragmented
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * try to reassemble. Process options. Pass to next level.
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm /* min header length */
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm /* keep ip header intact for ICMP reply
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * ip->ip_sum = cksum(m, hlen);
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * if (ip->ip_sum) {
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * Convert fields to host representation.
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * Check that the amount of data in the buffers
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * is as at least much as the IP header would have us expect.
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * Trim mbufs if longer than we expect.
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * Drop packet if shorter than we expect.
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm /* Should drop packet if mbuf too long? hmmm... */
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm /* check ip_ttl for a correct ICMP reply */
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm icmp_error(pData, m, ICMP_TIMXCEED, ICMP_TIMXCEED_INTRANS, 0, "ttl");
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * If offset or IP_MF are set, must reassemble.
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * Otherwise, nothing need be done.
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * (We could look in the reassembly queue to see
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * if the packet was previously fragmented,
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * but it's not worth the time; just let them time out.)
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * XXX This should fail, don't fragment yet
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * Switch out to protocol's input routine.
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm /* If maxnipq or maxfragsperpacket are 0, never accept fragments. */
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * Look for queue of fragments
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * of this datagram.
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * Attempt to trim the number of allocated fragment queues if it
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * exceeds the administrative limit.
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * drop something from the tail of the current queue
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * before proceeding further
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm for (i = 0; i < IPREASS_NHASH; i++)
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * Adjust ip_len to not reflect header,
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * convert offset of this to bytes.
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * Make sure that fragments have a data length
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * that's a non-zero multiple of 8 bytes.
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * Attempt reassembly; if it succeeds, proceed.
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * ip_reass() will return a different mbuf.
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm /* Previous ip_reass() started here. */
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * Presence of header sizes in mbufs
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * would confuse code below.
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * If first fragment to arrive, create a reassembly queue.
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * Find a segment which begins after this one does.
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm for (p = NULL, q = fp->ipq_frags; q; p = q, q = q->m_nextpkt)
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * If there is a preceding segment, it may provide some of
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * our data already. If so, drop the data from the incoming
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * segment. If it provides all of our data, drop us, otherwise
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * stick new segment in the proper place.
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * If some of the data is dropped from the the preceding
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * segment, then it's checksum is invalidated.
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm if (i > 0)
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * While we overlap succeeding segments trim them or,
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * if they are completely covered, dequeue them.
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm for (; q != NULL && ip->ip_off + ip->ip_len > GETIP(q)->ip_off;
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * Check for complete reassembly and perform frag per packet
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * limiting.
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * Frag limiting is performed here so that the nth frag has
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * a chance to complete the packet before we drop the packet.
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * As a result, n+1 frags are actually allowed per packet, but
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * only n will ever be stored. (n = maxfragsperpacket.)
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm for (p = NULL, q = fp->ipq_frags; q; p = q, q = q->m_nextpkt)
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm /* Make sure the last packet didn't have the IP_MF flag */
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * Reassembly is complete. Make sure the packet is a sane size.
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * Concatenate fragments.
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * Create header for new ip packet by modifying header of first
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * packet; dequeue and discard fragment reassembly header.
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * Make header visible.
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm /* some debugging cruft by sklower, below, will go away soon */
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm if (m->m_flags & M_PKTHDR) /* XXX this should be done elsewhere */
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm return (m);
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gmip_freef(PNATState pData, struct ipqhead *fhp, struct ipq_t *fp)
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm struct mbuf *q;
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * IP timer processing;
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * if a timer expires on a reassembly
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * queue, discard it.
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm /* XXX: the fragment expiration is the same but requier
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * additional loop see (see ip_input.c in FreeBSD tree)
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm for (i = 0; i < IPREASS_NHASH; i++)
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * If we are over the maximum number of fragments
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * (due to the limit being lowered), drain off
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * enough to get down to the new limit.
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm for (i = 0; i < IPREASS_NHASH; i++)
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm ipstat.ips_fragdropped += TAILQ_FIRST(&ipq[i])->ipq_nfrags;
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * Strip out IP options, at higher
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * level protocol in the kernel.
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * Second argument is buffer to which options
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * will be moved, and return value is their length.
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm * (XXX) should be deleted; last arg currently ignored.
88f8b78a88cbdc6d8c1af5c3e54bc49d25095c98gm register int i;