/*
* 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.
*
* Please read the file COPYRIGHT for the
* terms and conditions of the copyright.
*/
#include <slirp.h>
#include <osdep.h>
#include "ip_icmp.h"
#ifdef LOG_ENABLED
struct ipstat ipstat;
#endif
struct ipq ipq;
static struct ip *ip_reass(register struct ip *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(void)
{
ipq.ip_link.next = ipq.ip_link.prev = &ipq.ip_link;
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(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;
}
if (slirp_restrict) {
if (ip_geth(ip->ip_dst) != special_addr_ip) {
if (ip_getn(ip->ip_dst) == 0xffffffffu && ip->ip_p != IPPROTO_UDP)
goto bad;
} else {
int host = ip_geth(ip->ip_dst) & 0xff;
struct ex_list *ex_ptr;
if (host == 0xff)
goto bad;
for (ex_ptr = exec_list; ex_ptr; ex_ptr = ex_ptr->ex_next)
if (ex_ptr->ex_addr == host)
break;
if (!ex_ptr)
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;
struct qlink *l;
/*
* Look for queue of fragments
* of this datagram.
*/
for (l = ipq.ip_link.next; l != &ipq.ip_link; l = l->next) {
fp = container_of(l, struct ipq, ip_link);
if (ip->ip_id == fp->ipq_id &&
ip_equal(ip->ip_src, fp->ipq_src) &&
ip_equal(ip->ip_dst, fp->ipq_dst) &&
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) {
STAT(ipstat.ips_fragments++);
ip = ip_reass(ip, fp);
if (ip == NULL)
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;
}
#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(register struct ip *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 == NULL) {
struct mbuf *t;
if ((t = m_get()) == NULL) goto dropfrag;
fp = mtod(t, struct ipq *);
insque(&fp->ip_link, &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(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) {
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(q), i);
break;
}
q = q->ipf_next;
m_freem(dtom(q->ipf_prev));
ip_deq(q->ipf_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(q);
q = (struct ipasfrag *) q->ipf_next;
while (q != (struct ipasfrag*)&fp->frag_link) {
struct mbuf *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.
*/
q = fp->frag_link.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 = (char *)q - m->m_dat;
q = (struct ipasfrag *)(m->m_ext + delta);
}
/* DEBUG_ARG("ip = %lx", (long)ip);
* ip=(struct ipasfrag *)m->m_data; */
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);
(void) m_free(dtom(fp));
m->m_len += (ip->ip_hl << 2);
m->m_data -= (ip->ip_hl << 2);
return ip;
dropfrag:
STAT(ipstat.ips_fragdropped++);
m_freem(m);
return NULL;
}
/*
* Free a fragment reassembly header and all
* associated datagrams.
*/
static void
ip_freef(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_freem(dtom(q));
}
remque(&fp->ip_link);
(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 = 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(void)
{
struct qlink *l;
DEBUG_CALL("ip_slowtimo");
l = ipq.ip_link.next;
if (l == NULL)
return;
while (l != &ipq.ip_link) {
struct ipq *fp = container_of(l, struct ipq, ip_link);
l = l->next;
if (--fp->ipq_ttl == 0) {
STAT(ipstat.ips_fragtimeout++);
ip_freef(fp);
}
}
}
/*
* 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;
ipaddr_t *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);
STAT(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(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;
}