ip_icmp.c@ 53776

Last change on this file since 53776 was 53776, checked in by vboxsync, 10 years ago
NAT: Make it possible to use privileged helper to obtain raw ICMP socket when debugging unprivileged. Conditional on VBOX_RAWSOCK_DEBUG_HELPER that is added to the makefile but is commented out.
Property svn:eol-style set to `native` Property svn:keywords set to `Author Date Id Revision`
File size: 22.2 KB

Line
1	/* $Id: ip_icmp.c 53776 2015-01-12 16:38:11Z vboxsync $ */
2	/** @file
3	* NAT - IP/ICMP handling.
4	*/
5
6	/*
7	* Copyright (C) 2006-2012 Oracle Corporation
8	*
9	* This file is part of VirtualBox Open Source Edition (OSE), as
10	* available from http://www.virtualbox.org. 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	static void icmp_cache_clean(PNATState pData, int iEntries);
93
94	int
95	icmp_init(PNATState pData, int iIcmpCacheLimit)
96	{
97	pData->icmp_socket.so_type = IPPROTO_ICMP;
98	pData->icmp_socket.so_state = SS_ISFCONNECTED;
99
100	#ifndef RT_OS_WINDOWS
101	if (iIcmpCacheLimit < 0)
102	{
103	LogRel(("NAT: iIcmpCacheLimit is invalid %d, will be alter to default value 100\n", iIcmpCacheLimit));
104	iIcmpCacheLimit = 100;
105	}
106	pData->iIcmpCacheLimit = iIcmpCacheLimit;
107	# ifndef RT_OS_DARWIN
108	pData->icmp_socket.s = socket(PF_INET, SOCK_RAW, IPPROTO_ICMP);
109	# else /* !RT_OS_DARWIN */
110	pData->icmp_socket.s = socket(AF_INET, SOCK_DGRAM, IPPROTO_ICMP);
111	# endif /* RT_OS_DARWIN */
112	if (pData->icmp_socket.s == -1)
113	{
114	int rc = RTErrConvertFromErrno(errno);
115	# if defined(RT_OS_DARWIN) \|\| !defined(VBOX_RAWSOCK_DEBUG_HELPER)
116	LogRel(("NAT: ICMP/ping not available (could not open ICMP socket, error %Rrc)\n", rc));
117	return 1;
118	# else
119	/* try to get it from privileged helper */
120	LogRel(("NAT: ICMP/ping raw socket error %Rrc, asking helper...\n", rc));
121	pData->icmp_socket.s = getrawsock(AF_INET);
122	if (pData->icmp_socket.s == -1)
123	{
124	LogRel(("NAT: ICMP/ping not available\n"));
125	return 1;
126	}
127	# endif /* !RT_OS_DARWIN && VBOX_RAWSOCK_DEBUG_HELPER */
128	}
129	fd_nonblock(pData->icmp_socket.s);
130	NSOCK_INC();
131
132	LIST_INIT(&pData->icmp_msg_head);
133
134	#else /* RT_OS_WINDOWS */
135	if (icmpwin_init(pData) != 0)
136	return 1;
137	#endif /* RT_OS_WINDOWS */
138
139	return 0;
140	}
141
142	/**
143	* Cleans ICMP cache.
144	*/
145	void
146	icmp_finit(PNATState pData)
147	{
148	#ifdef RT_OS_WINDOWS
149	icmpwin_finit(pData);
150	#else
151	icmp_cache_clean(pData, -1);
152	closesocket(pData->icmp_socket.s);
153	#endif
154	}
155
156	#if !defined(RT_OS_WINDOWS)
157	/*
158	* ip here is ip header + 64bytes readed from ICMP packet
159	*/
160	struct icmp_msg *
161	icmp_find_original_mbuf(PNATState pData, struct ip *ip)
162	{
163	struct mbuf *m0;
164	struct ip *ip0;
165	struct icmp icp, icp0;
166	struct icmp_msg *icm = NULL;
167	int found = 0;
168	struct udphdr *udp;
169	struct tcphdr *tcp;
170	struct socket *head_socket = NULL;
171	struct socket *last_socket = NULL;
172	struct socket *so = NULL;
173	struct in_addr faddr;
174	u_short lport, fport;
175
176	faddr.s_addr = ~0;
177
178	lport = ~0;
179	fport = ~0;
180
181
182	LogFlowFunc(("ENTER: ip->ip_p:%d\n", ip->ip_p));
183	switch (ip->ip_p)
184	{
185	case IPPROTO_ICMP:
186	icp = (struct icmp )((char )ip + (ip->ip_hl << 2));
187	LIST_FOREACH(icm, &pData->icmp_msg_head, im_list)
188	{
189	m0 = icm->im_m;
190	ip0 = mtod(m0, struct ip *);
191	if (ip0->ip_p != IPPROTO_ICMP)
192	{
193	/* try next item */
194	continue;
195	}
196	icp0 = (struct icmp )((char )ip0 + (ip0->ip_hl << 2));
197	/*
198	* IP could pointer to ICMP_REPLY datagram (1)
199	* or pointer IP header in ICMP payload in case of
200	* ICMP_TIMXCEED or ICMP_UNREACH (2)
201	*
202	* if (1) and then ICMP (type should be ICMP_ECHOREPLY) and we need check that
203	* IP.IP_SRC == IP0.IP_DST received datagramm comes from destination.
204	*
205	* if (2) then check that payload ICMP has got type ICMP_ECHO and
206	* IP.IP_DST == IP0.IP_DST destination of returned datagram is the same as
207	* one was sent.
208	*/
209	if ( ( (icp->icmp_type != ICMP_ECHO && ip->ip_src.s_addr == ip0->ip_dst.s_addr)
210	\|\| (icp->icmp_type == ICMP_ECHO && ip->ip_dst.s_addr == ip0->ip_dst.s_addr))
211	&& icp->icmp_id == icp0->icmp_id
212	&& icp->icmp_seq == icp0->icmp_seq)
213	{
214	found = 1;
215	Log(("Have found %R[natsock]\n", icm->im_so));
216	break;
217	}
218	Log(("Have found nothing\n"));
219	}
220	break;
221
222	/*
223	* for TCP and UDP logic little bit reverted, we try to find the HOST socket
224	* from which the IP package has been sent.
225	*/
226	case IPPROTO_UDP:
227	head_socket = &udb;
228	udp = (struct udphdr )((char )ip + (ip->ip_hl << 2));
229	faddr.s_addr = ip->ip_dst.s_addr;
230	fport = udp->uh_dport;
231	lport = udp->uh_sport;
232	last_socket = udp_last_so;
233	/* fall through */
234
235	case IPPROTO_TCP:
236	if (head_socket == NULL)
237	{
238	tcp = (struct tcphdr )((char )ip + (ip->ip_hl << 2));
239	head_socket = &tcb; /* head_socket could be initialized with udb*/
240	faddr.s_addr = ip->ip_dst.s_addr;
241	fport = tcp->th_dport;
242	lport = tcp->th_sport;
243	last_socket = tcp_last_so;
244	}
245	/* check last socket first */
246	if ( last_socket->so_faddr.s_addr == faddr.s_addr
247	&& last_socket->so_fport == fport
248	&& last_socket->so_hlport == lport)
249	{
250	found = 1;
251	so = last_socket;
252	goto sofound;
253	}
254	for (so = head_socket->so_prev; so != head_socket; so = so->so_prev)
255	{
256	/* Should be reaplaced by hash here */
257	Log(("trying:%R[natsock] against %RTnaipv4:%d lport=%d hlport=%d\n", so, &faddr, fport, lport, so->so_hlport));
258	if ( so->so_faddr.s_addr == faddr.s_addr
259	&& so->so_fport == fport
260	&& so->so_hlport == lport)
261	{
262	found = 1;
263	break;
264	}
265	}
266	break;
267
268	default:
269	Log(("NAT:ICMP: unsupported protocol(%d)\n", ip->ip_p));
270	}
271	sofound:
272	if (found == 1 && icm == NULL)
273	{
274	if (so->so_state == SS_NOFDREF)
275	{
276	/* socket is shutdowning we've already sent ICMP on it.*/
277	Log(("NAT: Received icmp on shutdowning socket (probably corresponding ICMP socket has been already sent)\n"));
278	return NULL;
279	}
280	icm = RTMemAlloc(sizeof(struct icmp_msg));
281	icm->im_m = so->so_m;
282	icm->im_so = so;
283	found = 1;
284	Log(("hit:%R[natsock]\n", so));
285	/*XXX: this storage not very long,
286	* better add flag if it should removed from lis
287	*/
288	LIST_INSERT_HEAD(&pData->icmp_msg_head, icm, im_list);
289	pData->cIcmpCacheSize++;
290	if (pData->cIcmpCacheSize > pData->iIcmpCacheLimit)
291	icmp_cache_clean(pData, pData->iIcmpCacheLimit/2);
292	LogFlowFunc(("LEAVE: icm:%p\n", icm));
293	return (icm);
294	}
295	if (found == 1)
296	{
297	LogFlowFunc(("LEAVE: icm:%p\n", icm));
298	return icm;
299	}
300
301	LogFlowFunc(("LEAVE: NULL\n"));
302	return NULL;
303	}
304
305	/**
306	* iEntries how many entries to leave, if iEntries < 0, clean all
307	*/
308	static void icmp_cache_clean(PNATState pData, int iEntries)
309	{
310	int iIcmpCount = 0;
311	struct icmp_msg *icm = NULL;
312	LogFlowFunc(("iEntries:%d\n", iEntries));
313	if (iEntries > pData->cIcmpCacheSize)
314	{
315	LogFlowFuncLeave();
316	return;
317	}
318	while(!LIST_EMPTY(&pData->icmp_msg_head))
319	{
320	icm = LIST_FIRST(&pData->icmp_msg_head);
321	if ( iEntries > 0
322	&& iIcmpCount < iEntries)
323	{
324	iIcmpCount++;
325	continue;
326	}
327
328	LIST_REMOVE(icm, im_list);
329	if (icm->im_m)
330	{
331	pData->cIcmpCacheSize--;
332	m_freem(pData, icm->im_m);
333	}
334	RTMemFree(icm);
335	}
336	LogFlowFuncLeave();
337	}
338
339	static int
340	icmp_attach(PNATState pData, struct mbuf *m)
341	{
342	struct icmp_msg *icm;
343	struct ip *ip;
344	ip = mtod(m, struct ip *);
345	Assert(ip->ip_p == IPPROTO_ICMP);
346	icm = RTMemAlloc(sizeof(struct icmp_msg));
347	icm->im_m = m;
348	icm->im_so = m->m_so;
349	LIST_INSERT_HEAD(&pData->icmp_msg_head, icm, im_list);
350	pData->cIcmpCacheSize++;
351	if (pData->cIcmpCacheSize > pData->iIcmpCacheLimit)
352	icmp_cache_clean(pData, pData->iIcmpCacheLimit/2);
353	return 0;
354	}
355	#endif /* !RT_OS_WINDOWS */
356
357	/*
358	* Process a received ICMP message.
359	*/
360	void
361	icmp_input(PNATState pData, struct mbuf *m, int hlen)
362	{
363	register struct ip ip = mtod(m, struct ip );
364	int icmplen = ip->ip_len;
365	uint8_t icmp_type;
366	void *icp_buf = NULL;
367	uint32_t dst;
368
369	/* int code; */
370
371	LogFlowFunc(("ENTER: m = %lx, m_len = %d\n", (long)m, m ? m->m_len : 0));
372
373	icmpstat.icps_received++;
374
375	/*
376	* Locate icmp structure in mbuf, and check
377	* that its not corrupted and of at least minimum length.
378	*/
379	if (icmplen < ICMP_MINLEN)
380	{
381	/* min 8 bytes payload */
382	icmpstat.icps_tooshort++;
383	goto end_error_free_m;
384	}
385
386	m->m_len -= hlen;
387	m->m_data += hlen;
388
389	if (cksum(m, icmplen))
390	{
391	icmpstat.icps_checksum++;
392	goto end_error_free_m;
393	}
394
395	/* are we guaranteed to have ICMP header in first mbuf? be safe. */
396	m_copydata(m, 0, sizeof(icmp_type), (caddr_t)&icmp_type);
397
398	m->m_len += hlen;
399	m->m_data -= hlen;
400
401	/* icmpstat.icps_inhist[icp->icmp_type]++; */
402	/* code = icp->icmp_code; */
403
404	LogFlow(("icmp_type = %d\n", icmp_type));
405	switch (icmp_type)
406	{
407	case ICMP_ECHO:
408	ip->ip_len += hlen; /* since ip_input subtracts this */
409	dst = ip->ip_dst.s_addr;
410	if ( CTL_CHECK(dst, CTL_ALIAS)
411	\|\| CTL_CHECK(dst, CTL_DNS)
412	\|\| CTL_CHECK(dst, CTL_TFTP))
413	{
414	uint8_t echo_reply = ICMP_ECHOREPLY;
415	m_copyback(pData, m, hlen + RT_OFFSETOF(struct icmp, icmp_type),
416	sizeof(echo_reply), (caddr_t)&echo_reply);
417	ip->ip_dst.s_addr = ip->ip_src.s_addr;
418	ip->ip_src.s_addr = dst;
419	icmp_reflect(pData, m);
420	goto done;
421	}
422
423	#ifdef RT_OS_WINDOWS
424	{
425	icmpwin_ping(pData, m, hlen);
426	break; /* free mbuf */
427	}
428	#else
429	{
430	struct icmp *icp;
431	struct sockaddr_in addr;
432
433	/* XXX: FIXME: this is bogus, see CTL_CHECKs above */
434	addr.sin_family = AF_INET;
435	if ((ip->ip_dst.s_addr & RT_H2N_U32(pData->netmask)) == pData->special_addr.s_addr)
436	{
437	/* It's an alias */
438	switch (RT_N2H_U32(ip->ip_dst.s_addr) & ~pData->netmask)
439	{
440	case CTL_DNS:
441	case CTL_ALIAS:
442	default:
443	addr.sin_addr = loopback_addr;
444	break;
445	}
446	}
447	else
448	addr.sin_addr.s_addr = ip->ip_dst.s_addr;
449
450	if (m->m_next)
451	{
452	icp_buf = RTMemAlloc(icmplen);
453	if (!icp_buf)
454	{
455	Log(("NAT: not enought memory to allocate the buffer\n"));
456	goto end_error_free_m;
457	}
458	m_copydata(m, hlen, icmplen, icp_buf);
459	icp = (struct icmp *)icp_buf;
460	}
461	else
462	icp = (struct icmp )(mtod(m, char ) + hlen);
463
464	if (pData->icmp_socket.s != -1)
465	{
466	static bool fIcmpSocketErrorReported;
467	int ttl;
468	int status;
469	ssize_t rc;
470
471	ttl = ip->ip_ttl;
472	Log(("NAT/ICMP: try to set TTL(%d)\n", ttl));
473	status = setsockopt(pData->icmp_socket.s, IPPROTO_IP, IP_TTL,
474	(void *)&ttl, sizeof(ttl));
475	if (status < 0)
476	Log(("NAT: Error (%s) occurred while setting TTL attribute of IP packet\n",
477	strerror(errno)));
478	rc = sendto(pData->icmp_socket.s, icp, icmplen, 0,
479	(struct sockaddr *)&addr, sizeof(addr));
480	if (rc >= 0)
481	{
482	m->m_so = &pData->icmp_socket;
483	icmp_attach(pData, m);
484	/* don't let m_freem at the end free atached buffer */
485	goto done;
486	}
487
488
489	if (!fIcmpSocketErrorReported)
490	{
491	LogRel(("icmp_input udp sendto tx errno = %d (%s)\n",
492	errno, strerror(errno)));
493	fIcmpSocketErrorReported = true;
494	}
495	icmp_error(pData, m, ICMP_UNREACH, ICMP_UNREACH_NET, 0, strerror(errno));
496	}
497	}
498	#endif /* !RT_OS_WINDOWS */
499	break;
500	case ICMP_UNREACH:
501	case ICMP_TIMXCEED:
502	/* @todo(vvl): both up cases comes from guest,
503	* indeed right solution would be find the socket
504	* corresponding to ICMP data and close it.
505	*/
506	case ICMP_PARAMPROB:
507	case ICMP_SOURCEQUENCH:
508	case ICMP_TSTAMP:
509	case ICMP_MASKREQ:
510	case ICMP_REDIRECT:
511	icmpstat.icps_notsupp++;
512	break;
513
514	default:
515	icmpstat.icps_badtype++;
516	} /* switch */
517
518	end_error_free_m:
519	m_freem(pData, m);
520
521	done:
522	if (icp_buf)
523	RTMemFree(icp_buf);
524	}
525
526
527	/**
528	* Send an ICMP message in response to a situation
529	*
530	* RFC 1122: 3.2.2 MUST send at least the IP header and 8 bytes of header. MAY send more (we do).
531	* MUST NOT change this header information.
532	* MUST NOT reply to a multicast/broadcast IP address.
533	* MUST NOT reply to a multicast/broadcast MAC address.
534	* MUST reply to only the first fragment.
535	*
536	* Send ICMP_UNREACH back to the source regarding msrc.
537	* It is reported as the bad ip packet. The header should
538	* be fully correct and in host byte order.
539	* ICMP fragmentation is illegal.
540	*
541	* @note: implementation note: MSIZE is 256 bytes (minimal buffer).
542	* We always truncate original payload to 8 bytes required by the RFC,
543	* so the largest possible datagram is 14 (ethernet) + 20 (ip) +
544	* 8 (icmp) + 60 (max original ip with options) + 8 (original payload)
545	* = 110 bytes which fits into sinlge mbuf.
546	*
547	* @note This function will free msrc!
548	*/
549
550	void icmp_error(PNATState pData, struct mbuf msrc, u_char type, u_char code, int minsize, const char message)
551	{
552	unsigned ohlen, olen;
553	struct mbuf *m;
554	struct ip oip, ip;
555	struct icmp *icp;
556	void *payload;
557
558	LogFlow(("icmp_error: msrc = %p, msrc_len = %d\n",
559	(void *)msrc, msrc ? msrc->m_len : 0));
560
561	if (RT_UNLIKELY(msrc == NULL))
562	goto end_error;
563
564	M_ASSERTPKTHDR(msrc);
565
566	if ( type != ICMP_UNREACH
567	&& type != ICMP_TIMXCEED
568	&& type != ICMP_SOURCEQUENCH)
569	goto end_error;
570
571	oip = mtod(msrc, struct ip *);
572	LogFunc(("msrc: %RTnaipv4 -> %RTnaipv4\n", oip->ip_src, oip->ip_dst));
573
574	if (oip->ip_src.s_addr == INADDR_ANY)
575	goto end_error;
576
577	if (oip->ip_off & IP_OFFMASK)
578	goto end_error; /* Only reply to fragment 0 */
579
580	ohlen = oip->ip_hl * 4;
581	AssertStmt(ohlen >= sizeof(struct ip), goto end_error);
582
583	olen = oip->ip_len;
584	AssertStmt(olen >= ohlen, goto end_error);
585
586	if (oip->ip_p == IPPROTO_ICMP)
587	{
588	struct icmp oicp = (struct icmp )((char *)oip + ohlen);
589	/*
590	* Assume any unknown ICMP type is an error. This isn't
591	* specified by the RFC, but think about it..
592	*/
593	if (oicp->icmp_type > ICMP_MAXTYPE \|\| icmp_flush[oicp->icmp_type])
594	goto end_error;
595	}
596
597	/* undo byte order conversions done in ip_input() */
598	HTONS(oip->ip_len);
599	HTONS(oip->ip_id);
600	HTONS(oip->ip_off);
601
602	m = m_gethdr(pData, M_NOWAIT, MT_HEADER);
603	if (RT_UNLIKELY(m == NULL))
604	goto end_error;
605
606	m->m_flags \|= M_SKIP_FIREWALL;
607	m->m_data += if_maxlinkhdr;
608
609	ip = mtod(m, struct ip *);
610	m->m_pkthdr.header = (void *)ip;
611
612	/* fill in ip (ip_output0() does the boilerplate for us) */
613	ip->ip_tos = ((oip->ip_tos & 0x1E) \| 0xC0); /* high priority for errors */
614	/* ip->ip_len will be set later */
615	ip->ip_off = 0;
616	ip->ip_ttl = MAXTTL;
617	ip->ip_p = IPPROTO_ICMP;
618	ip->ip_src = alias_addr;
619	ip->ip_dst = oip->ip_src;
620
621	/* fill in icmp */
622	icp = (struct icmp )((char )ip + sizeof(*ip));
623	icp->icmp_type = type;
624	icp->icmp_code = code;
625	icp->icmp_id = 0;
626	icp->icmp_seq = 0;
627
628	/* fill in icmp payload: original ip header plus 8 bytes of its payload */
629	if (olen > ohlen + 8)
630	olen = ohlen + 8;
631	payload = (void )((char )icp + ICMP_MINLEN);
632	memcpy(payload, oip, olen);
633
634	/*
635	* Original code appended this message after the payload. This
636	* might have been a good idea for real slirp, as it provided a
637	* communication channel with the remote host. But 90s are over.
638	*/
639	NOREF(message);
640
641	/* hide ip header for icmp checksum calculation */
642	m->m_data += sizeof(struct ip);
643	m->m_len = ICMP_MINLEN + /* truncated */ olen;
644
645	icp->icmp_cksum = 0;
646	icp->icmp_cksum = cksum(m, m->m_len);
647
648	/* reveal ip header */
649	m->m_data -= sizeof(struct ip);
650	m->m_len += sizeof(struct ip);
651	ip->ip_len = m->m_len;
652
653	(void) ip_output0(pData, (struct socket *)NULL, m, 1);
654
655	icmpstat.icps_reflect++;
656
657	/* clear source datagramm in positive branch */
658	m_freem(pData, msrc);
659	LogFlowFuncLeave();
660	return;
661
662	end_error:
663
664	/*
665	* clear source datagramm in case if some of requirement haven't been met.
666	*/
667	if (msrc)
668	m_freem(pData, msrc);
669
670	{
671	static bool fIcmpErrorReported;
672	if (!fIcmpErrorReported)
673	{
674	LogRel(("NAT: error occurred while sending ICMP error message\n"));
675	fIcmpErrorReported = true;
676	}
677	}
678	LogFlowFuncLeave();
679	}
680
681	/*
682	* Reflect the ip packet back to the source
683	* Note: m isn't duplicated by this method and more delivered to ip_output then.
684	*/
685	void
686	icmp_reflect(PNATState pData, struct mbuf *m)
687	{
688	register struct ip ip = mtod(m, struct ip );
689	int hlen = ip->ip_hl << 2;
690	register struct icmp *icp;
691	LogFlowFunc(("ENTER: m:%p\n", m));
692
693	/*
694	* Send an icmp packet back to the ip level,
695	* after supplying a checksum.
696	*/
697	m->m_data += hlen;
698	m->m_len -= hlen;
699	icp = mtod(m, struct icmp *);
700
701	icp->icmp_cksum = 0;
702	icp->icmp_cksum = cksum(m, ip->ip_len - hlen);
703
704	m->m_data -= hlen;
705	m->m_len += hlen;
706
707	(void) ip_output(pData, (struct socket *)NULL, m);
708
709	icmpstat.icps_reflect++;
710	LogFlowFuncLeave();
711	}

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source: vbox/trunk/src/VBox/Devices/Network/slirp/ip_icmp.c@ 53776

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