ip_icmp.c@ 56292

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1	/* $Id: ip_icmp.c 56292 2015-06-09 14:20:46Z vboxsync $ */
2	/** @file
3	* NAT - IP/ICMP handling.
4	*/
5
6	/*
7	* Copyright (C) 2006-2015 Oracle Corporation
8	*
9	* This file is part of VirtualBox Open Source Edition (OSE), as
10	* available from http://www.215389.xyz. This file is free software;
11	* you can redistribute it and/or modify it under the terms of the GNU
12	* General Public License (GPL) as published by the Free Software
13	* Foundation, in version 2 as it comes in the "COPYING" file of the
14	* VirtualBox OSE distribution. VirtualBox OSE is distributed in the
15	* hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
16	*/
17
18	/*
19	* This code is based on:
20	*
21	* Copyright (c) 1982, 1986, 1988, 1993
22	* The Regents of the University of California. All rights reserved.
23	*
24	* Redistribution and use in source and binary forms, with or without
25	* modification, are permitted provided that the following conditions
26	* are met:
27	* 1. Redistributions of source code must retain the above copyright
28	* notice, this list of conditions and the following disclaimer.
29	* 2. Redistributions in binary form must reproduce the above copyright
30	* notice, this list of conditions and the following disclaimer in the
31	* documentation and/or other materials provided with the distribution.
32	* 3. All advertising materials mentioning features or use of this software
33	* must display the following acknowledgement:
34	* This product includes software developed by the University of
35	* California, Berkeley and its contributors.
36	* 4. Neither the name of the University nor the names of its contributors
37	* may be used to endorse or promote products derived from this software
38	* without specific prior written permission.
39	*
40	* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
41	* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
42	* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
43	* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
44	* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
45	* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
46	* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
47	* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
48	* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
49	* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
50	* SUCH DAMAGE.
51	*
52	* @(#)ip_icmp.c 8.2 (Berkeley) 1/4/94
53	* ip_icmp.c,v 1.7 1995/05/30 08:09:42 rgrimes Exp
54	*/
55
56	#include "slirp.h"
57	#include "ip_icmp.h"
58
59	#ifdef VBOX_RAWSOCK_DEBUG_HELPER
60	int getrawsock(int type);
61	#endif
62
63
64	/* The message sent when emulating PING */
65	/* Be nice and tell them it's just a psuedo-ping packet */
66	static const char icmp_ping_msg[] = "This is a psuedo-PING packet used by Slirp to emulate ICMP ECHO-REQUEST packets.\n";
67
68	/* list of actions for icmp_error() on RX of an icmp message */
69	static const int icmp_flush[19] =
70	{
71	/* ECHO REPLY (0) */ 0,
72	1,
73	1,
74	/* DEST UNREACH (3) */ 1,
75	/* SOURCE QUENCH (4)*/ 1,
76	/* REDIRECT (5) */ 1,
77	1,
78	1,
79	/* ECHO (8) */ 0,
80	/* ROUTERADVERT (9) */ 1,
81	/* ROUTERSOLICIT (10) */ 1,
82	/* TIME EXCEEDED (11) */ 1,
83	/* PARAMETER PROBLEM (12) */ 1,
84	/* TIMESTAMP (13) */ 0,
85	/* TIMESTAMP REPLY (14) */ 0,
86	/* INFO (15) */ 0,
87	/* INFO REPLY (16) */ 0,
88	/* ADDR MASK (17) */ 0,
89	/* ADDR MASK REPLY (18) */ 0
90	};
91
92
93	int
94	icmp_init(PNATState pData, int iIcmpCacheLimit)
95	{
96	pData->icmp_socket.so_type = IPPROTO_ICMP;
97	pData->icmp_socket.so_state = SS_ISFCONNECTED;
98
99	#ifndef RT_OS_WINDOWS
100	TAILQ_INIT(&pData->icmp_msg_head);
101
102	if (iIcmpCacheLimit < 0)
103	{
104	LogRel(("NAT: iIcmpCacheLimit is invalid %d, will be alter to default value 100\n", iIcmpCacheLimit));
105	iIcmpCacheLimit = 100;
106	}
107	pData->iIcmpCacheLimit = iIcmpCacheLimit;
108	# ifndef RT_OS_DARWIN
109	pData->icmp_socket.s = socket(PF_INET, SOCK_RAW, IPPROTO_ICMP);
110	# else /* !RT_OS_DARWIN */
111	pData->icmp_socket.s = socket(AF_INET, SOCK_DGRAM, IPPROTO_ICMP);
112	# endif /* RT_OS_DARWIN */
113	if (pData->icmp_socket.s == -1)
114	{
115	int rc = RTErrConvertFromErrno(errno);
116	# if defined(RT_OS_DARWIN) \|\| !defined(VBOX_RAWSOCK_DEBUG_HELPER)
117	LogRel(("NAT: ICMP/ping not available (could not open ICMP socket, error %Rrc)\n", rc));
118	return 1;
119	# else
120	/* try to get it from privileged helper */
121	LogRel(("NAT: ICMP/ping raw socket error %Rrc, asking helper...\n", rc));
122	pData->icmp_socket.s = getrawsock(AF_INET);
123	if (pData->icmp_socket.s == -1)
124	{
125	LogRel(("NAT: ICMP/ping not available\n"));
126	return 1;
127	}
128	# endif /* !RT_OS_DARWIN && VBOX_RAWSOCK_DEBUG_HELPER */
129	}
130	fd_nonblock(pData->icmp_socket.s);
131	NSOCK_INC();
132	#else /* RT_OS_WINDOWS */
133	if (icmpwin_init(pData) != 0)
134	return 1;
135	#endif /* RT_OS_WINDOWS */
136
137	return 0;
138	}
139
140	/**
141	* Cleans ICMP cache.
142	*/
143	void
144	icmp_finit(PNATState pData)
145	{
146	#ifdef RT_OS_WINDOWS
147	icmpwin_finit(pData);
148	#else
149	while (!TAILQ_EMPTY(&pData->icmp_msg_head))
150	{
151	struct icmp_msg *icm = TAILQ_FIRST(&pData->icmp_msg_head);
152	icmp_msg_delete(pData, icm);
153	}
154	closesocket(pData->icmp_socket.s);
155	#endif
156	}
157
158
159	#if !defined(RT_OS_WINDOWS)
160	static struct icmp_msg *
161	icmp_msg_alloc(PNATState pData)
162	{
163	struct icmp_msg *icm;
164
165	#ifdef DEBUG
166	{
167	int iTally = 0;
168	TAILQ_FOREACH(icm, &pData->icmp_msg_head, im_queue)
169	++iTally;
170	Assert(pData->cIcmpCacheSize == iTally);
171	}
172	#endif
173
174	if (pData->cIcmpCacheSize >= pData->iIcmpCacheLimit)
175	{
176	int cTargetCacheSize = pData->iIcmpCacheLimit/2;
177
178	while (pData->cIcmpCacheSize > cTargetCacheSize)
179	{
180	icm = TAILQ_FIRST(&pData->icmp_msg_head);
181	icmp_msg_delete(pData, icm);
182	}
183	}
184
185	icm = RTMemAlloc(sizeof(struct icmp_msg));
186	if (RT_UNLIKELY(icm == NULL))
187	return NULL;
188
189	TAILQ_INSERT_TAIL(&pData->icmp_msg_head, icm, im_queue);
190	pData->cIcmpCacheSize++;
191
192	return icm;
193	}
194
195
196	static void
197	icmp_attach(PNATState pData, struct mbuf *m)
198	{
199	struct icmp_msg *icm;
200
201	#ifdef DEBUG
202	{
203	/* only used for ping */
204	struct ip ip = mtod(m, struct ip );
205	Assert(ip->ip_p == IPPROTO_ICMP);
206	}
207	#endif
208
209	icm = icmp_msg_alloc(pData);
210	if (RT_UNLIKELY(icm == NULL))
211	return;
212
213	icm->im_so = &pData->icmp_socket;
214	icm->im_m = m;
215	}
216
217
218	void
219	icmp_msg_delete(PNATState pData, struct icmp_msg *icm)
220	{
221	if (RT_UNLIKELY(icm == NULL))
222	return;
223
224	#ifdef DEBUG
225	{
226	struct icmp_msg *existing;
227	int iTally = 0;
228
229	TAILQ_FOREACH(existing, &pData->icmp_msg_head, im_queue)
230	++iTally;
231	Assert(pData->cIcmpCacheSize == iTally);
232
233	Assert(pData->cIcmpCacheSize > 0);
234	TAILQ_FOREACH(existing, &pData->icmp_msg_head, im_queue)
235	{
236	if (existing == icm)
237	break;
238	}
239	Assert(existing != NULL);
240	}
241	#endif
242
243	TAILQ_REMOVE(&pData->icmp_msg_head, icm, im_queue);
244	pData->cIcmpCacheSize--;
245
246	icm->im_so->so_m = NULL;
247	if (icm->im_m != NULL)
248	m_freem(pData, icm->im_m);
249
250	RTMemFree(icm);
251	}
252
253
254	/*
255	* ip here is ip header + 64bytes readed from ICMP packet
256	*/
257	struct icmp_msg *
258	icmp_find_original_mbuf(PNATState pData, struct ip *ip)
259	{
260	struct mbuf *m0;
261	struct ip *ip0;
262	struct icmp icp, icp0;
263	struct icmp_msg *icm = NULL;
264	int found = 0;
265	struct udphdr *udp;
266	struct tcphdr *tcp;
267	struct socket *head_socket = NULL;
268	struct socket *last_socket = NULL;
269	struct socket *so = NULL;
270	struct in_addr faddr;
271	u_short lport, fport;
272
273	faddr.s_addr = ~0;
274
275	lport = ~0;
276	fport = ~0;
277
278
279	LogFlowFunc(("ENTER: ip->ip_p:%d\n", ip->ip_p));
280	switch (ip->ip_p)
281	{
282	case IPPROTO_ICMP:
283	icp = (struct icmp )((char )ip + (ip->ip_hl << 2));
284	TAILQ_FOREACH(icm, &pData->icmp_msg_head, im_queue)
285	{
286	m0 = icm->im_m;
287	ip0 = mtod(m0, struct ip *);
288	if (ip0->ip_p != IPPROTO_ICMP)
289	{
290	/* try next item */
291	continue;
292	}
293	icp0 = (struct icmp )((char )ip0 + (ip0->ip_hl << 2));
294	/*
295	* IP could pointer to ICMP_REPLY datagram (1)
296	* or pointer IP header in ICMP payload in case of
297	* ICMP_TIMXCEED or ICMP_UNREACH (2)
298	*
299	* if (1) and then ICMP (type should be ICMP_ECHOREPLY) and we need check that
300	* IP.IP_SRC == IP0.IP_DST received datagramm comes from destination.
301	*
302	* if (2) then check that payload ICMP has got type ICMP_ECHO and
303	* IP.IP_DST == IP0.IP_DST destination of returned datagram is the same as
304	* one was sent.
305	*/
306	if ( ( (icp->icmp_type != ICMP_ECHO && ip->ip_src.s_addr == ip0->ip_dst.s_addr)
307	\|\| (icp->icmp_type == ICMP_ECHO && ip->ip_dst.s_addr == ip0->ip_dst.s_addr))
308	&& icp->icmp_id == icp0->icmp_id
309	&& icp->icmp_seq == icp0->icmp_seq)
310	{
311	found = 1;
312	Log(("Have found %R[natsock]\n", icm->im_so));
313	break;
314	}
315	Log(("Have found nothing\n"));
316	}
317	break;
318
319	/*
320	* for TCP and UDP logic little bit reverted, we try to find the HOST socket
321	* from which the IP package has been sent.
322	*/
323	case IPPROTO_UDP:
324	head_socket = &udb;
325	udp = (struct udphdr )((char )ip + (ip->ip_hl << 2));
326	faddr.s_addr = ip->ip_dst.s_addr;
327	fport = udp->uh_dport;
328	lport = udp->uh_sport;
329	last_socket = udp_last_so;
330	/* fall through */
331
332	case IPPROTO_TCP:
333	if (head_socket == NULL)
334	{
335	tcp = (struct tcphdr )((char )ip + (ip->ip_hl << 2));
336	head_socket = &tcb; /* head_socket could be initialized with udb*/
337	faddr.s_addr = ip->ip_dst.s_addr;
338	fport = tcp->th_dport;
339	lport = tcp->th_sport;
340	last_socket = tcp_last_so;
341	}
342	/* check last socket first */
343	if ( last_socket->so_faddr.s_addr == faddr.s_addr
344	&& last_socket->so_fport == fport
345	&& last_socket->so_hlport == lport)
346	{
347	found = 1;
348	so = last_socket;
349	break;
350	}
351	for (so = head_socket->so_prev; so != head_socket; so = so->so_prev)
352	{
353	/* Should be reaplaced by hash here */
354	Log(("trying:%R[natsock] against %RTnaipv4:%d lport=%d hlport=%d\n", so, &faddr, fport, lport, so->so_hlport));
355	if ( so->so_faddr.s_addr == faddr.s_addr
356	&& so->so_fport == fport
357	&& so->so_hlport == lport)
358	{
359	found = 1;
360	break;
361	}
362	}
363	break;
364
365	default:
366	Log(("NAT:ICMP: unsupported protocol(%d)\n", ip->ip_p));
367	}
368
369	#ifdef DEBUG
370	if (found)
371	Assert((icm != NULL) ^ (so != NULL));
372	#endif
373
374	if (found && icm == NULL)
375	{
376	/*
377	* XXX: Implies this is not a pong, found socket. This is, of
378	* course, wasteful since the caller will delete icmp_msg
379	* immediately after processing, so there's not much reason to
380	* clutter up the queue with it.
381	*/
382	AssertReturn(so != NULL, NULL);
383
384	/*
385	* XXX: FIXME: If the very first send(2) fails, the socket is
386	* still in SS_NOFDREF and so we will not report this too.
387	*/
388	if (so->so_state == SS_NOFDREF)
389	{
390	/* socket is shutting down we've already sent ICMP on it. */
391	Log(("NAT:ICMP: disconnected %R[natsock]\n", so));
392	LogFlowFunc(("LEAVE: icm:NULL\n"));
393	return NULL;
394	}
395
396	if (so->so_m == NULL)
397	{
398	Log(("NAT:ICMP: no saved mbuf for %R[natsock]\n", so));
399	LogFlowFunc(("LEAVE: icm:NULL\n"));
400	return NULL;
401	}
402
403	icm = icmp_msg_alloc(pData);
404	if (RT_UNLIKELY(icm == NULL))
405	{
406	LogFlowFunc(("LEAVE: icm:NULL\n"));
407	return NULL;
408	}
409
410	Log(("NAT:ICMP: for %R[natsock]\n", so));
411	icm->im_so = so;
412	icm->im_m = so->so_m;
413	}
414	LogFlowFunc(("LEAVE: icm:%p\n", icm));
415	return icm;
416	}
417	#endif /* !RT_OS_WINDOWS */
418
419
420	/*
421	* Process a received ICMP message.
422	*/
423	void
424	icmp_input(PNATState pData, struct mbuf *m, int hlen)
425	{
426	register struct ip ip = mtod(m, struct ip );
427	int icmplen = ip->ip_len;
428	uint8_t icmp_type;
429	void *icp_buf = NULL;
430	uint32_t dst;
431
432	/* int code; */
433
434	LogFlowFunc(("ENTER: m = %lx, m_len = %d\n", (long)m, m ? m->m_len : 0));
435
436	icmpstat.icps_received++;
437
438	/*
439	* Locate icmp structure in mbuf, and check
440	* that its not corrupted and of at least minimum length.
441	*/
442	if (icmplen < ICMP_MINLEN)
443	{
444	/* min 8 bytes payload */
445	icmpstat.icps_tooshort++;
446	goto end_error_free_m;
447	}
448
449	m->m_len -= hlen;
450	m->m_data += hlen;
451
452	if (cksum(m, icmplen))
453	{
454	icmpstat.icps_checksum++;
455	goto end_error_free_m;
456	}
457
458	/* are we guaranteed to have ICMP header in first mbuf? be safe. */
459	m_copydata(m, 0, sizeof(icmp_type), (caddr_t)&icmp_type);
460
461	m->m_len += hlen;
462	m->m_data -= hlen;
463
464	/* icmpstat.icps_inhist[icp->icmp_type]++; */
465	/* code = icp->icmp_code; */
466
467	LogFlow(("icmp_type = %d\n", icmp_type));
468	switch (icmp_type)
469	{
470	case ICMP_ECHO:
471	ip->ip_len += hlen; /* since ip_input subtracts this */
472	dst = ip->ip_dst.s_addr;
473	if ( CTL_CHECK(dst, CTL_ALIAS)
474	\|\| CTL_CHECK(dst, CTL_DNS)
475	\|\| CTL_CHECK(dst, CTL_TFTP))
476	{
477	uint8_t echo_reply = ICMP_ECHOREPLY;
478	m_copyback(pData, m, hlen + RT_OFFSETOF(struct icmp, icmp_type),
479	sizeof(echo_reply), (caddr_t)&echo_reply);
480	ip->ip_dst.s_addr = ip->ip_src.s_addr;
481	ip->ip_src.s_addr = dst;
482	icmp_reflect(pData, m);
483	goto done;
484	}
485
486	#ifdef RT_OS_WINDOWS
487	{
488	icmpwin_ping(pData, m, hlen);
489	break; /* free mbuf */
490	}
491	#else
492	{
493	struct icmp *icp;
494	struct sockaddr_in addr;
495
496	/* XXX: FIXME: this is bogus, see CTL_CHECKs above */
497	addr.sin_family = AF_INET;
498	if ((ip->ip_dst.s_addr & RT_H2N_U32(pData->netmask)) == pData->special_addr.s_addr)
499	{
500	/* It's an alias */
501	switch (RT_N2H_U32(ip->ip_dst.s_addr) & ~pData->netmask)
502	{
503	case CTL_DNS:
504	case CTL_ALIAS:
505	default:
506	addr.sin_addr = loopback_addr;
507	break;
508	}
509	}
510	else
511	addr.sin_addr.s_addr = ip->ip_dst.s_addr;
512
513	if (m->m_next)
514	{
515	icp_buf = RTMemAlloc(icmplen);
516	if (!icp_buf)
517	{
518	Log(("NAT: not enought memory to allocate the buffer\n"));
519	goto end_error_free_m;
520	}
521	m_copydata(m, hlen, icmplen, icp_buf);
522	icp = (struct icmp *)icp_buf;
523	}
524	else
525	icp = (struct icmp )(mtod(m, char ) + hlen);
526
527	if (pData->icmp_socket.s != -1)
528	{
529	static bool fIcmpSocketErrorReported;
530	int ttl;
531	int status;
532	ssize_t rc;
533
534	ttl = ip->ip_ttl;
535	Log(("NAT/ICMP: try to set TTL(%d)\n", ttl));
536	status = setsockopt(pData->icmp_socket.s, IPPROTO_IP, IP_TTL,
537	(void *)&ttl, sizeof(ttl));
538	if (status < 0)
539	Log(("NAT: Error (%s) occurred while setting TTL attribute of IP packet\n",
540	strerror(errno)));
541	rc = sendto(pData->icmp_socket.s, icp, icmplen, 0,
542	(struct sockaddr *)&addr, sizeof(addr));
543	if (rc >= 0)
544	{
545	icmp_attach(pData, m);
546	/* don't let m_freem at the end free atached buffer */
547	goto done;
548	}
549
550
551	if (!fIcmpSocketErrorReported)
552	{
553	LogRel(("icmp_input udp sendto tx errno = %d (%s)\n",
554	errno, strerror(errno)));
555	fIcmpSocketErrorReported = true;
556	}
557	icmp_error(pData, m, ICMP_UNREACH, ICMP_UNREACH_NET, 0, strerror(errno));
558	}
559	}
560	#endif /* !RT_OS_WINDOWS */
561	break;
562	case ICMP_UNREACH:
563	case ICMP_TIMXCEED:
564	/* @todo(vvl): both up cases comes from guest,
565	* indeed right solution would be find the socket
566	* corresponding to ICMP data and close it.
567	*/
568	case ICMP_PARAMPROB:
569	case ICMP_SOURCEQUENCH:
570	case ICMP_TSTAMP:
571	case ICMP_MASKREQ:
572	case ICMP_REDIRECT:
573	icmpstat.icps_notsupp++;
574	break;
575
576	default:
577	icmpstat.icps_badtype++;
578	} /* switch */
579
580	end_error_free_m:
581	m_freem(pData, m);
582
583	done:
584	if (icp_buf)
585	RTMemFree(icp_buf);
586	}
587
588
589	/**
590	* Send an ICMP message in response to a situation
591	*
592	* RFC 1122: 3.2.2 MUST send at least the IP header and 8 bytes of header. MAY send more (we do).
593	* MUST NOT change this header information.
594	* MUST NOT reply to a multicast/broadcast IP address.
595	* MUST NOT reply to a multicast/broadcast MAC address.
596	* MUST reply to only the first fragment.
597	*
598	* Send ICMP_UNREACH back to the source regarding msrc.
599	* It is reported as the bad ip packet. The header should
600	* be fully correct and in host byte order.
601	* ICMP fragmentation is illegal.
602	*
603	* @note: implementation note: MSIZE is 256 bytes (minimal buffer).
604	* We always truncate original payload to 8 bytes required by the RFC,
605	* so the largest possible datagram is 14 (ethernet) + 20 (ip) +
606	* 8 (icmp) + 60 (max original ip with options) + 8 (original payload)
607	* = 110 bytes which fits into sinlge mbuf.
608	*
609	* @note This function will free msrc!
610	*/
611
612	void icmp_error(PNATState pData, struct mbuf msrc, u_char type, u_char code, int minsize, const char message)
613	{
614	unsigned ohlen, olen;
615	struct mbuf *m;
616	struct ip oip, ip;
617	struct icmp *icp;
618	void *payload;
619
620	LogFlow(("icmp_error: msrc = %p, msrc_len = %d\n",
621	(void *)msrc, msrc ? msrc->m_len : 0));
622
623	if (RT_UNLIKELY(msrc == NULL))
624	goto end_error;
625
626	M_ASSERTPKTHDR(msrc);
627
628	if ( type != ICMP_UNREACH
629	&& type != ICMP_TIMXCEED
630	&& type != ICMP_SOURCEQUENCH)
631	goto end_error;
632
633	oip = mtod(msrc, struct ip *);
634	LogFunc(("msrc: %RTnaipv4 -> %RTnaipv4\n", oip->ip_src, oip->ip_dst));
635
636	if (oip->ip_src.s_addr == INADDR_ANY)
637	goto end_error;
638
639	if (oip->ip_off & IP_OFFMASK)
640	goto end_error; /* Only reply to fragment 0 */
641
642	ohlen = oip->ip_hl * 4;
643	AssertStmt(ohlen >= sizeof(struct ip), goto end_error);
644
645	olen = oip->ip_len;
646	AssertStmt(olen >= ohlen, goto end_error);
647
648	if (oip->ip_p == IPPROTO_ICMP)
649	{
650	struct icmp oicp = (struct icmp )((char *)oip + ohlen);
651	/*
652	* Assume any unknown ICMP type is an error. This isn't
653	* specified by the RFC, but think about it..
654	*/
655	if (oicp->icmp_type > ICMP_MAXTYPE \|\| icmp_flush[oicp->icmp_type])
656	goto end_error;
657	}
658
659	/* undo byte order conversions done in ip_input() */
660	HTONS(oip->ip_len);
661	HTONS(oip->ip_id);
662	HTONS(oip->ip_off);
663
664	m = m_gethdr(pData, M_NOWAIT, MT_HEADER);
665	if (RT_UNLIKELY(m == NULL))
666	goto end_error;
667
668	m->m_flags \|= M_SKIP_FIREWALL;
669	m->m_data += if_maxlinkhdr;
670
671	ip = mtod(m, struct ip *);
672	m->m_pkthdr.header = (void *)ip;
673
674	/* fill in ip (ip_output0() does the boilerplate for us) */
675	ip->ip_tos = ((oip->ip_tos & 0x1E) \| 0xC0); /* high priority for errors */
676	/* ip->ip_len will be set later */
677	ip->ip_off = 0;
678	ip->ip_ttl = MAXTTL;
679	ip->ip_p = IPPROTO_ICMP;
680	ip->ip_src = alias_addr;
681	ip->ip_dst = oip->ip_src;
682
683	/* fill in icmp */
684	icp = (struct icmp )((char )ip + sizeof(*ip));
685	icp->icmp_type = type;
686	icp->icmp_code = code;
687	icp->icmp_id = 0;
688	icp->icmp_seq = 0;
689
690	/* fill in icmp payload: original ip header plus 8 bytes of its payload */
691	if (olen > ohlen + 8)
692	olen = ohlen + 8;
693	payload = (void )((char )icp + ICMP_MINLEN);
694	memcpy(payload, oip, olen);
695
696	/*
697	* Original code appended this message after the payload. This
698	* might have been a good idea for real slirp, as it provided a
699	* communication channel with the remote host. But 90s are over.
700	*/
701	NOREF(message);
702
703	/* hide ip header for icmp checksum calculation */
704	m->m_data += sizeof(struct ip);
705	m->m_len = ICMP_MINLEN + /* truncated */ olen;
706
707	icp->icmp_cksum = 0;
708	icp->icmp_cksum = cksum(m, m->m_len);
709
710	/* reveal ip header */
711	m->m_data -= sizeof(struct ip);
712	m->m_len += sizeof(struct ip);
713	ip->ip_len = m->m_len;
714
715	(void) ip_output0(pData, (struct socket *)NULL, m, 1);
716
717	icmpstat.icps_reflect++;
718
719	/* clear source datagramm in positive branch */
720	m_freem(pData, msrc);
721	LogFlowFuncLeave();
722	return;
723
724	end_error:
725
726	/*
727	* clear source datagramm in case if some of requirement haven't been met.
728	*/
729	if (msrc)
730	m_freem(pData, msrc);
731
732	{
733	static bool fIcmpErrorReported;
734	if (!fIcmpErrorReported)
735	{
736	LogRel(("NAT: error occurred while sending ICMP error message\n"));
737	fIcmpErrorReported = true;
738	}
739	}
740	LogFlowFuncLeave();
741	}
742
743	/*
744	* Reflect the ip packet back to the source
745	* Note: m isn't duplicated by this method and more delivered to ip_output then.
746	*/
747	void
748	icmp_reflect(PNATState pData, struct mbuf *m)
749	{
750	register struct ip ip = mtod(m, struct ip );
751	int hlen = ip->ip_hl << 2;
752	register struct icmp *icp;
753	LogFlowFunc(("ENTER: m:%p\n", m));
754
755	/*
756	* Send an icmp packet back to the ip level,
757	* after supplying a checksum.
758	*/
759	m->m_data += hlen;
760	m->m_len -= hlen;
761	icp = mtod(m, struct icmp *);
762
763	icp->icmp_cksum = 0;
764	icp->icmp_cksum = cksum(m, ip->ip_len - hlen);
765
766	m->m_data -= hlen;
767	m->m_len += hlen;
768
769	(void) ip_output(pData, (struct socket *)NULL, m);
770
771	icmpstat.icps_reflect++;
772	LogFlowFuncLeave();
773	}

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source: vbox/trunk/src/VBox/Devices/Network/slirp/ip_icmp.c@ 56292

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