2 * Copyright (c) 1982, 1986, 1988, 1993
3 * The Regents of the University of California. All rights reserved.
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
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. Neither the name of the University nor the names of its contributors
14 * may be used to endorse or promote products derived from this software
15 * without specific prior written permission.
17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * @(#)ip_input.c 8.2 (Berkeley) 1/4/94
30 * ip_input.c,v 1.11 1994/11/16 10:17:08 jkh Exp
34 * Changes and additions relating to SLiRP are
35 * Copyright (c) 1995 Danny Gasparovski.
37 * Please read the file COPYRIGHT for the
38 * terms and conditions of the copyright.
51 static struct ip
*ip_reass(register struct ip
*ip
,
52 register struct ipq
*fp
);
53 static void ip_freef(struct ipq
*fp
);
54 static void ip_enq(register struct ipasfrag
*p
,
55 register struct ipasfrag
*prev
);
56 static void ip_deq(register struct ipasfrag
*p
);
59 * IP initialization: fill in IP protocol switch table.
60 * All protocols not implemented in kernel go to raw IP protocol handler.
65 ipq
.ip_link
.next
= ipq
.ip_link
.prev
= &ipq
.ip_link
;
66 ip_id
= tt
.tv_sec
& 0xffff;
72 * Ip input routine. Checksum and byte swap header. If fragmented
73 * try to reassemble. Process options. Pass to next level.
76 ip_input(struct mbuf
*m
)
78 register struct ip
*ip
;
81 DEBUG_CALL("ip_input");
82 DEBUG_ARG("m = %lx", (long)m
);
83 DEBUG_ARG("m_len = %d", m
->m_len
);
85 STAT(ipstat
.ips_total
++);
87 if (m
->m_len
< sizeof (struct ip
)) {
88 STAT(ipstat
.ips_toosmall
++);
92 ip
= mtod(m
, struct ip
*);
94 if (ip
->ip_v
!= IPVERSION
) {
95 STAT(ipstat
.ips_badvers
++);
99 hlen
= ip
->ip_hl
<< 2;
100 if (hlen
<sizeof(struct ip
) || hlen
>m
->m_len
) {/* min header length */
101 STAT(ipstat
.ips_badhlen
++); /* or packet too short */
105 /* keep ip header intact for ICMP reply
106 * ip->ip_sum = cksum(m, hlen);
110 STAT(ipstat
.ips_badsum
++);
115 * Convert fields to host representation.
118 if (ip
->ip_len
< hlen
) {
119 STAT(ipstat
.ips_badlen
++);
126 * Check that the amount of data in the buffers
127 * is as at least much as the IP header would have us expect.
128 * Trim mbufs if longer than we expect.
129 * Drop packet if shorter than we expect.
131 if (m
->m_len
< ip
->ip_len
) {
132 STAT(ipstat
.ips_tooshort
++);
136 if (slirp_restrict
) {
137 if (memcmp(&ip
->ip_dst
.s_addr
, &special_addr
, 3)) {
138 if (ip
->ip_dst
.s_addr
== 0xffffffff && ip
->ip_p
!= IPPROTO_UDP
)
141 int host
= ntohl(ip
->ip_dst
.s_addr
) & 0xff;
142 struct ex_list
*ex_ptr
;
147 for (ex_ptr
= exec_list
; ex_ptr
; ex_ptr
= ex_ptr
->ex_next
)
148 if (ex_ptr
->ex_addr
== host
)
156 /* Should drop packet if mbuf too long? hmmm... */
157 if (m
->m_len
> ip
->ip_len
)
158 m_adj(m
, ip
->ip_len
- m
->m_len
);
160 /* check ip_ttl for a correct ICMP reply */
161 if(ip
->ip_ttl
==0 || ip
->ip_ttl
==1) {
162 icmp_error(m
, ICMP_TIMXCEED
,ICMP_TIMXCEED_INTRANS
, 0,"ttl");
167 * Process options and, if not destined for us,
168 * ship it on. ip_dooptions returns 1 when an
169 * error was detected (causing an icmp message
170 * to be sent and the original packet to be freed).
172 /* We do no IP options */
173 /* if (hlen > sizeof (struct ip) && ip_dooptions(m))
177 * If offset or IP_MF are set, must reassemble.
178 * Otherwise, nothing need be done.
179 * (We could look in the reassembly queue to see
180 * if the packet was previously fragmented,
181 * but it's not worth the time; just let them time out.)
183 * XXX This should fail, don't fragment yet
185 if (ip
->ip_off
&~ IP_DF
) {
186 register struct ipq
*fp
;
189 * Look for queue of fragments
192 for (l
= ipq
.ip_link
.next
; l
!= &ipq
.ip_link
; l
= l
->next
) {
193 fp
= container_of(l
, struct ipq
, ip_link
);
194 if (ip
->ip_id
== fp
->ipq_id
&&
195 ip
->ip_src
.s_addr
== fp
->ipq_src
.s_addr
&&
196 ip
->ip_dst
.s_addr
== fp
->ipq_dst
.s_addr
&&
197 ip
->ip_p
== fp
->ipq_p
)
204 * Adjust ip_len to not reflect header,
205 * set ip_mff if more fragments are expected,
206 * convert offset of this to bytes.
209 if (ip
->ip_off
& IP_MF
)
217 * If datagram marked as having more fragments
218 * or if this is not the first fragment,
219 * attempt reassembly; if it succeeds, proceed.
221 if (ip
->ip_tos
& 1 || ip
->ip_off
) {
222 STAT(ipstat
.ips_fragments
++);
223 ip
= ip_reass(ip
, fp
);
226 STAT(ipstat
.ips_reassembled
++);
236 * Switch out to protocol's input routine.
238 STAT(ipstat
.ips_delivered
++);
241 tcp_input(m
, hlen
, (struct socket
*)NULL
);
250 STAT(ipstat
.ips_noproto
++);
259 #define iptofrag(P) ((struct ipasfrag *)(((char*)(P)) - sizeof(struct qlink)))
260 #define fragtoip(P) ((struct ip*)(((char*)(P)) + sizeof(struct qlink)))
262 * Take incoming datagram fragment and try to
263 * reassemble it into whole datagram. If a chain for
264 * reassembly of this datagram already exists, then it
265 * is given as fp; otherwise have to make a chain.
268 ip_reass(register struct ip
*ip
, register struct ipq
*fp
)
270 register struct mbuf
*m
= dtom(ip
);
271 register struct ipasfrag
*q
;
272 int hlen
= ip
->ip_hl
<< 2;
275 DEBUG_CALL("ip_reass");
276 DEBUG_ARG("ip = %lx", (long)ip
);
277 DEBUG_ARG("fp = %lx", (long)fp
);
278 DEBUG_ARG("m = %lx", (long)m
);
281 * Presence of header sizes in mbufs
282 * would confuse code below.
283 * Fragment m_data is concatenated.
289 * If first fragment to arrive, create a reassembly queue.
293 if ((t
= m_get()) == NULL
) goto dropfrag
;
294 fp
= mtod(t
, struct ipq
*);
295 insque(&fp
->ip_link
, &ipq
.ip_link
);
296 fp
->ipq_ttl
= IPFRAGTTL
;
297 fp
->ipq_p
= ip
->ip_p
;
298 fp
->ipq_id
= ip
->ip_id
;
299 fp
->frag_link
.next
= fp
->frag_link
.prev
= &fp
->frag_link
;
300 fp
->ipq_src
= ip
->ip_src
;
301 fp
->ipq_dst
= ip
->ip_dst
;
302 q
= (struct ipasfrag
*)fp
;
307 * Find a segment which begins after this one does.
309 for (q
= fp
->frag_link
.next
; q
!= (struct ipasfrag
*)&fp
->frag_link
;
311 if (q
->ipf_off
> ip
->ip_off
)
315 * If there is a preceding segment, it may provide some of
316 * our data already. If so, drop the data from the incoming
317 * segment. If it provides all of our data, drop us.
319 if (q
->ipf_prev
!= &fp
->frag_link
) {
320 struct ipasfrag
*pq
= q
->ipf_prev
;
321 i
= pq
->ipf_off
+ pq
->ipf_len
- ip
->ip_off
;
332 * While we overlap succeeding segments trim them or,
333 * if they are completely covered, dequeue them.
335 while (q
!= (struct ipasfrag
*)&fp
->frag_link
&&
336 ip
->ip_off
+ ip
->ip_len
> q
->ipf_off
) {
337 i
= (ip
->ip_off
+ ip
->ip_len
) - q
->ipf_off
;
338 if (i
< q
->ipf_len
) {
345 m_freem(dtom(q
->ipf_prev
));
351 * Stick new segment in its place;
352 * check for complete reassembly.
354 ip_enq(iptofrag(ip
), q
->ipf_prev
);
356 for (q
= fp
->frag_link
.next
; q
!= (struct ipasfrag
*)&fp
->frag_link
;
358 if (q
->ipf_off
!= next
)
362 if (((struct ipasfrag
*)(q
->ipf_prev
))->ipf_tos
& 1)
366 * Reassembly is complete; concatenate fragments.
368 q
= fp
->frag_link
.next
;
371 q
= (struct ipasfrag
*) q
->ipf_next
;
372 while (q
!= (struct ipasfrag
*)&fp
->frag_link
) {
373 struct mbuf
*t
= dtom(q
);
374 q
= (struct ipasfrag
*) q
->ipf_next
;
379 * Create header for new ip packet by
380 * modifying header of first packet;
381 * dequeue and discard fragment reassembly header.
382 * Make header visible.
384 q
= fp
->frag_link
.next
;
387 * If the fragments concatenated to an mbuf that's
388 * bigger than the total size of the fragment, then and
389 * m_ext buffer was alloced. But fp->ipq_next points to
390 * the old buffer (in the mbuf), so we must point ip
391 * into the new buffer.
393 if (m
->m_flags
& M_EXT
) {
394 int delta
= (char *)q
- m
->m_dat
;
395 q
= (struct ipasfrag
*)(m
->m_ext
+ delta
);
398 /* DEBUG_ARG("ip = %lx", (long)ip);
399 * ip=(struct ipasfrag *)m->m_data; */
404 ip
->ip_src
= fp
->ipq_src
;
405 ip
->ip_dst
= fp
->ipq_dst
;
406 remque(&fp
->ip_link
);
407 (void) m_free(dtom(fp
));
408 m
->m_len
+= (ip
->ip_hl
<< 2);
409 m
->m_data
-= (ip
->ip_hl
<< 2);
414 STAT(ipstat
.ips_fragdropped
++);
420 * Free a fragment reassembly header and all
421 * associated datagrams.
424 ip_freef(struct ipq
*fp
)
426 register struct ipasfrag
*q
, *p
;
428 for (q
= fp
->frag_link
.next
; q
!= (struct ipasfrag
*)&fp
->frag_link
; q
= p
) {
433 remque(&fp
->ip_link
);
434 (void) m_free(dtom(fp
));
438 * Put an ip fragment on a reassembly chain.
439 * Like insque, but pointers in middle of structure.
442 ip_enq(register struct ipasfrag
*p
, register struct ipasfrag
*prev
)
444 DEBUG_CALL("ip_enq");
445 DEBUG_ARG("prev = %lx", (long)prev
);
447 p
->ipf_next
= prev
->ipf_next
;
448 ((struct ipasfrag
*)(prev
->ipf_next
))->ipf_prev
= p
;
453 * To ip_enq as remque is to insque.
456 ip_deq(register struct ipasfrag
*p
)
458 ((struct ipasfrag
*)(p
->ipf_prev
))->ipf_next
= p
->ipf_next
;
459 ((struct ipasfrag
*)(p
->ipf_next
))->ipf_prev
= p
->ipf_prev
;
463 * IP timer processing;
464 * if a timer expires on a reassembly
472 DEBUG_CALL("ip_slowtimo");
474 l
= ipq
.ip_link
.next
;
479 while (l
!= &ipq
.ip_link
) {
480 struct ipq
*fp
= container_of(l
, struct ipq
, ip_link
);
482 if (--fp
->ipq_ttl
== 0) {
483 STAT(ipstat
.ips_fragtimeout
++);
490 * Do option processing on a datagram,
491 * possibly discarding it if bad options are encountered,
492 * or forwarding it if source-routed.
493 * Returns 1 if packet has been forwarded/freed,
494 * 0 if the packet should be processed further.
503 register struct ip
*ip
= mtod(m
, struct ip
*);
505 register struct ip_timestamp
*ipt
;
506 register struct in_ifaddr
*ia
;
507 /* int opt, optlen, cnt, off, code, type = ICMP_PARAMPROB, forward = 0; */
508 int opt
, optlen
, cnt
, off
, code
, type
, forward
= 0;
509 struct in_addr
*sin
, dst
;
510 typedef u_int32_t n_time
;
514 cp
= (u_char
*)(ip
+ 1);
515 cnt
= (ip
->ip_hl
<< 2) - sizeof (struct ip
);
516 for (; cnt
> 0; cnt
-= optlen
, cp
+= optlen
) {
517 opt
= cp
[IPOPT_OPTVAL
];
518 if (opt
== IPOPT_EOL
)
520 if (opt
== IPOPT_NOP
)
523 optlen
= cp
[IPOPT_OLEN
];
524 if (optlen
<= 0 || optlen
> cnt
) {
525 code
= &cp
[IPOPT_OLEN
] - (u_char
*)ip
;
535 * Source routing with record.
536 * Find interface with current destination address.
537 * If none on this machine then drop if strictly routed,
538 * or do nothing if loosely routed.
539 * Record interface address and bring up next address
540 * component. If strictly routed make sure next
541 * address is on directly accessible net.
545 if ((off
= cp
[IPOPT_OFFSET
]) < IPOPT_MINOFF
) {
546 code
= &cp
[IPOPT_OFFSET
] - (u_char
*)ip
;
549 ipaddr
.sin_addr
= ip
->ip_dst
;
550 ia
= (struct in_ifaddr
*)
551 ifa_ifwithaddr((struct sockaddr
*)&ipaddr
);
553 if (opt
== IPOPT_SSRR
) {
555 code
= ICMP_UNREACH_SRCFAIL
;
559 * Loose routing, and not at next destination
560 * yet; nothing to do except forward.
564 off
--; / * 0 origin
* /
565 if (off
> optlen
- sizeof(struct in_addr
)) {
567 * End of source route. Should be for us.
569 save_rte(cp
, ip
->ip_src
);
573 * locate outgoing interface
575 bcopy((caddr_t
)(cp
+ off
), (caddr_t
)&ipaddr
.sin_addr
,
576 sizeof(ipaddr
.sin_addr
));
577 if (opt
== IPOPT_SSRR
) {
578 #define INA struct in_ifaddr *
579 #define SA struct sockaddr *
580 if ((ia
= (INA
)ifa_ifwithdstaddr((SA
)&ipaddr
)) == 0)
581 ia
= (INA
)ifa_ifwithnet((SA
)&ipaddr
);
583 ia
= ip_rtaddr(ipaddr
.sin_addr
);
586 code
= ICMP_UNREACH_SRCFAIL
;
589 ip
->ip_dst
= ipaddr
.sin_addr
;
590 bcopy((caddr_t
)&(IA_SIN(ia
)->sin_addr
),
591 (caddr_t
)(cp
+ off
), sizeof(struct in_addr
));
592 cp
[IPOPT_OFFSET
] += sizeof(struct in_addr
);
594 * Let ip_intr's mcast routing check handle mcast pkts
596 forward
= !IN_MULTICAST(ntohl(ip
->ip_dst
.s_addr
));
600 if ((off
= cp
[IPOPT_OFFSET
]) < IPOPT_MINOFF
) {
601 code
= &cp
[IPOPT_OFFSET
] - (u_char
*)ip
;
605 * If no space remains, ignore.
608 if (off
> optlen
- sizeof(struct in_addr
))
610 bcopy((caddr_t
)(&ip
->ip_dst
), (caddr_t
)&ipaddr
.sin_addr
,
611 sizeof(ipaddr
.sin_addr
));
613 * locate outgoing interface; if we're the destination,
614 * use the incoming interface (should be same).
616 if ((ia
= (INA
)ifa_ifwithaddr((SA
)&ipaddr
)) == 0 &&
617 (ia
= ip_rtaddr(ipaddr
.sin_addr
)) == 0) {
619 code
= ICMP_UNREACH_HOST
;
622 bcopy((caddr_t
)&(IA_SIN(ia
)->sin_addr
),
623 (caddr_t
)(cp
+ off
), sizeof(struct in_addr
));
624 cp
[IPOPT_OFFSET
] += sizeof(struct in_addr
);
628 code
= cp
- (u_char
*)ip
;
629 ipt
= (struct ip_timestamp
*)cp
;
630 if (ipt
->ipt_len
< 5)
632 if (ipt
->ipt_ptr
> ipt
->ipt_len
- sizeof (int32_t)) {
633 if (++ipt
->ipt_oflw
== 0)
637 sin
= (struct in_addr
*)(cp
+ ipt
->ipt_ptr
- 1);
638 switch (ipt
->ipt_flg
) {
640 case IPOPT_TS_TSONLY
:
643 case IPOPT_TS_TSANDADDR
:
644 if (ipt
->ipt_ptr
+ sizeof(n_time
) +
645 sizeof(struct in_addr
) > ipt
->ipt_len
)
647 ipaddr
.sin_addr
= dst
;
648 ia
= (INA
)ifaof_ i f p
foraddr((SA
)&ipaddr
,
652 bcopy((caddr_t
)&IA_SIN(ia
)->sin_addr
,
653 (caddr_t
)sin
, sizeof(struct in_addr
));
654 ipt
->ipt_ptr
+= sizeof(struct in_addr
);
657 case IPOPT_TS_PRESPEC
:
658 if (ipt
->ipt_ptr
+ sizeof(n_time
) +
659 sizeof(struct in_addr
) > ipt
->ipt_len
)
661 bcopy((caddr_t
)sin
, (caddr_t
)&ipaddr
.sin_addr
,
662 sizeof(struct in_addr
));
663 if (ifa_ifwithaddr((SA
)&ipaddr
) == 0)
665 ipt
->ipt_ptr
+= sizeof(struct in_addr
);
672 bcopy((caddr_t
)&ntime
, (caddr_t
)cp
+ ipt
->ipt_ptr
- 1,
674 ipt
->ipt_ptr
+= sizeof(n_time
);
685 /* ip->ip_len -= ip->ip_hl << 2; XXX icmp_error adds in hdr length */
688 icmp_error(m
, type
, code
, 0, 0);
690 STAT(ipstat
.ips_badoptions
++);
697 * Strip out IP options, at higher
698 * level protocol in the kernel.
699 * Second argument is buffer to which options
700 * will be moved, and return value is their length.
701 * (XXX) should be deleted; last arg currently ignored.
704 ip_stripoptions(register struct mbuf
*m
, struct mbuf
*mopt
)
707 struct ip
*ip
= mtod(m
, struct ip
*);
708 register caddr_t opts
;
711 olen
= (ip
->ip_hl
<<2) - sizeof (struct ip
);
712 opts
= (caddr_t
)(ip
+ 1);
713 i
= m
->m_len
- (sizeof (struct ip
) + olen
);
714 memcpy(opts
, opts
+ olen
, (unsigned)i
);
717 ip
->ip_hl
= sizeof(struct ip
) >> 2;