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/* SPDX-License-Identifier: BSD-3-Clause */
/*
* 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. 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.
*/
#include "slirp.h"
#include "ip_icmp.h"
static struct ip *ip_reass(Slirp *slirp, struct ip *ip, struct ipq *fp);
static void ip_freef(Slirp *slirp, 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(Slirp *slirp)
{
slirp->ipq.ip_link.next = slirp->ipq.ip_link.prev = &slirp->ipq.ip_link;
udp_init(slirp);
tcp_init(slirp);
icmp_init(slirp);
}
void ip_cleanup(Slirp *slirp)
{
udp_cleanup(slirp);
tcp_cleanup(slirp);
icmp_cleanup(slirp);
}
/*
* Ip input routine. Checksum and byte swap header. If fragmented
* try to reassemble. Process options. Pass to next level.
*/
void ip_input(struct mbuf *m)
{
Slirp *slirp = m->slirp;
M_DUP_DEBUG(slirp, m, 0, TCPIPHDR_DELTA);
register struct ip *ip;
int hlen;
if (!slirp->in_enabled) {
goto bad;
}
DEBUG_CALL("ip_input");
DEBUG_ARG("m = %p", m);
DEBUG_ARG("m_len = %d", m->m_len);
if (m->m_len < sizeof(struct ip)) {
goto bad;
}
ip = mtod(m, struct ip *);
if (ip->ip_v != IPVERSION) {
goto bad;
}
hlen = ip->ip_hl << 2;
if (hlen < sizeof(struct ip) || hlen > m->m_len) { /* min header length */
goto bad; /* or packet too short */
}
/* keep ip header intact for ICMP reply
* ip->ip_sum = cksum(m, hlen);
* if (ip->ip_sum) {
*/
if (cksum(m, hlen)) {
goto bad;
}
/*
* Convert fields to host representation.
*/
NTOHS(ip->ip_len);
if (ip->ip_len < hlen) {
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) {
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) {
icmp_send_error(m, ICMP_TIMXCEED, ICMP_TIMXCEED_INTRANS, 0, "ttl");
goto bad;
}
/*
* 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;
struct qlink *l;
/*
* Look for queue of fragments
* of this datagram.
*/
for (l = slirp->ipq.ip_link.next; l != &slirp->ipq.ip_link;
l = l->next) {
fp = container_of(l, struct ipq, ip_link);
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;
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)
ip->ip_tos |= 1;
else
ip->ip_tos &= ~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 (ip->ip_tos & 1 || ip->ip_off) {
ip = ip_reass(slirp, ip, fp);
if (ip == NULL)
return;
m = dtom(slirp, ip);
} else if (fp)
ip_freef(slirp, fp);
} else
ip->ip_len -= hlen;
/*
* Switch out to protocol's input routine.
*/
switch (ip->ip_p) {
case IPPROTO_TCP:
tcp_input(m, hlen, (struct socket *)NULL, AF_INET);
break;
case IPPROTO_UDP:
udp_input(m, hlen);
break;
case IPPROTO_ICMP:
icmp_input(m, hlen);
break;
default:
m_free(m);
}
return;
bad:
m_free(m);
}
#define iptofrag(P) ((struct ipasfrag *)(((char *)(P)) - sizeof(struct qlink)))
#define fragtoip(P) ((struct ip *)(((char *)(P)) + sizeof(struct qlink)))
/*
* 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(Slirp *slirp, struct ip *ip, struct ipq *fp)
{
register struct mbuf *m = dtom(slirp, ip);
register struct ipasfrag *q;
int hlen = ip->ip_hl << 2;
int i, next;
DEBUG_CALL("ip_reass");
DEBUG_ARG("ip = %p", ip);
DEBUG_ARG("fp = %p", fp);
DEBUG_ARG("m = %p", 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 == NULL) {
struct mbuf *t = m_get(slirp);
if (t == NULL) {
goto dropfrag;
}
fp = mtod(t, struct ipq *);
insque(&fp->ip_link, &slirp->ipq.ip_link);
fp->ipq_ttl = IPFRAGTTL;
fp->ipq_p = ip->ip_p;
fp->ipq_id = ip->ip_id;
fp->frag_link.next = fp->frag_link.prev = &fp->frag_link;
fp->ipq_src = ip->ip_src;
fp->ipq_dst = ip->ip_dst;
q = (struct ipasfrag *)fp;
goto insert;
}
/*
* Find a segment which begins after this one does.
*/
for (q = fp->frag_link.next; q != (struct ipasfrag *)&fp->frag_link;
q = q->ipf_next)
if (q->ipf_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 != &fp->frag_link) {
struct ipasfrag *pq = q->ipf_prev;
i = pq->ipf_off + pq->ipf_len - ip->ip_off;
if (i > 0) {
if (i >= ip->ip_len)
goto dropfrag;
m_adj(dtom(slirp, 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->frag_link &&
ip->ip_off + ip->ip_len > q->ipf_off) {
struct ipasfrag *prev;
i = (ip->ip_off + ip->ip_len) - q->ipf_off;
if (i < q->ipf_len) {
q->ipf_len -= i;
q->ipf_off += i;
m_adj(dtom(slirp, q), i);
break;
}
prev = q;
q = q->ipf_next;
ip_deq(prev);
m_free(dtom(slirp, prev));
}
insert:
/*
* Stick new segment in its place;
* check for complete reassembly.
*/
ip_enq(iptofrag(ip), q->ipf_prev);
next = 0;
for (q = fp->frag_link.next; q != (struct ipasfrag *)&fp->frag_link;
q = q->ipf_next) {
if (q->ipf_off != next)
return NULL;
next += q->ipf_len;
}
if (((struct ipasfrag *)(q->ipf_prev))->ipf_tos & 1)
return NULL;
/*
* Reassembly is complete; concatenate fragments.
*/
q = fp->frag_link.next;
m = dtom(slirp, q);
int delta = (char *)q - (m->m_flags & M_EXT ? m->m_ext : m->m_dat);
q = (struct ipasfrag *)q->ipf_next;
while (q != (struct ipasfrag *)&fp->frag_link) {
struct mbuf *t = dtom(slirp, 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.
*/
q = fp->frag_link.next;
/*
* If the fragments concatenated to an mbuf that's bigger than the total
* size of the fragment and the mbuf was not already using an m_ext buffer,
* then an m_ext buffer was allocated. 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) {
q = (struct ipasfrag *)(m->m_ext + delta);
}
ip = fragtoip(q);
ip->ip_len = next;
ip->ip_tos &= ~1;
ip->ip_src = fp->ipq_src;
ip->ip_dst = fp->ipq_dst;
remque(&fp->ip_link);
m_free(dtom(slirp, fp));
m->m_len += (ip->ip_hl << 2);
m->m_data -= (ip->ip_hl << 2);
return ip;
dropfrag:
m_free(m);
return NULL;
}
/*
* Free a fragment reassembly header and all
* associated datagrams.
*/
static void ip_freef(Slirp *slirp, struct ipq *fp)
{
register struct ipasfrag *q, *p;
for (q = fp->frag_link.next; q != (struct ipasfrag *)&fp->frag_link;
q = p) {
p = q->ipf_next;
ip_deq(q);
m_free(dtom(slirp, q));
}
remque(&fp->ip_link);
m_free(dtom(slirp, 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 = %p", prev);
p->ipf_prev = prev;
p->ipf_next = prev->ipf_next;
((struct ipasfrag *)(prev->ipf_next))->ipf_prev = p;
prev->ipf_next = 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(Slirp *slirp)
{
struct qlink *l;
DEBUG_CALL("ip_slowtimo");
l = slirp->ipq.ip_link.next;
if (l == NULL)
return;
while (l != &slirp->ipq.ip_link) {
struct ipq *fp = container_of(l, struct ipq, ip_link);
l = l->next;
if (--fp->ipq_ttl == 0) {
ip_freef(slirp, fp);
}
}
}
/*
* 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(register struct mbuf *m, struct mbuf *mopt)
{
register int i;
struct ip *ip = mtod(m, struct ip *);
register char *opts;
int olen;
olen = (ip->ip_hl << 2) - sizeof(struct ip);
opts = (char *)(ip + 1);
i = m->m_len - (sizeof(struct ip) + olen);
memmove(opts, opts + olen, (unsigned)i);
m->m_len -= olen;
ip->ip_hl = sizeof(struct ip) >> 2;
}