ip_icmp.c@ 52343

Last change on this file since 52343 was 50986, checked in by vboxsync, 11 years ago
NAT: Update function comment for icmp_error to reflect r93155 (it was already out of sync with the code after r91460).
Property svn:eol-style set to `native` Property svn:keywords set to `Author Date Id Revision`
File size: 25.3 KB

Line
1	/* $Id: ip_icmp.c 50986 2014-04-07 16:12:55Z 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	#ifdef RT_OS_WINDOWS
59	# include <Icmpapi.h>
60	# include <Iphlpapi.h>
61	# include <iprt/ldr.h>
62	#endif
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	if (iIcmpCacheLimit < 0)
100	{
101	LogRel(("NAT: iIcmpCacheLimit is invalid %d, will be alter to default value 100\n", iIcmpCacheLimit));
102	iIcmpCacheLimit = 100;
103	}
104	pData->iIcmpCacheLimit = iIcmpCacheLimit;
105	#ifndef RT_OS_WINDOWS
106	# ifndef RT_OS_DARWIN
107	pData->icmp_socket.s = socket(PF_INET, SOCK_RAW, IPPROTO_ICMP);
108	# else /* !RT_OS_DARWIN */
109	pData->icmp_socket.s = socket(AF_INET, SOCK_DGRAM, IPPROTO_ICMP);
110	# endif /* RT_OS_DARWIN */
111	if (pData->icmp_socket.s == -1)
112	{
113	int rc = RTErrConvertFromErrno(errno);
114	LogRel(("NAT: ICMP/ping not available (could not open ICMP socket, error %Rrc)\n", rc));
115	return 1;
116	}
117	fd_nonblock(pData->icmp_socket.s);
118	NSOCK_INC();
119
120	#else /* RT_OS_WINDOWS */
121	/* Resolve symbols we need. */
122	{
123	RTLDRMOD hLdrMod;
124	int rc = RTLdrLoadSystem("Iphlpapi.dll", true /fNoUnload/, &hLdrMod);
125	if (RT_SUCCESS(rc))
126	{
127	pData->pfIcmpParseReplies = (long (WINAPI )(void , long))RTLdrGetFunction(hLdrMod, "IcmpParseReplies");
128	pData->pfIcmpCloseHandle = (BOOL (WINAPI *)(HANDLE))RTLdrGetFunction(hLdrMod, "IcmpCloseHandle");
129	rc = RTLdrGetSymbol(hLdrMod, "GetAdaptersAddresses", (void **)&pData->pfGetAdaptersAddresses);
130	if (RT_FAILURE(rc))
131	LogRel(("NAT: Can't find GetAdapterAddresses in Iphlpapi.dll\n"));
132	RTLdrClose(hLdrMod);
133	}
134
135	if (pData->pfIcmpParseReplies == NULL)
136	{
137	int rc = RTLdrLoadSystem("Icmp.dll", true /fNoUnload/, &hLdrMod);
138	if (RT_FAILURE(rc))
139	{
140	LogRel(("NAT: Icmp.dll could not be loaded: %Rrc\n", rc));
141	return 1;
142	}
143	pData->pfIcmpParseReplies = (long (WINAPI )(void , long))RTLdrGetFunction(hLdrMod, "IcmpParseReplies");
144	pData->pfIcmpCloseHandle = (BOOL (WINAPI *)(HANDLE))RTLdrGetFunction(hLdrMod, "IcmpCloseHandle");
145	RTLdrClose(hLdrMod);
146	}
147	}
148	if (pData->pfIcmpParseReplies == NULL)
149	{
150	LogRel(("NAT: Can't find IcmpParseReplies symbol\n"));
151	return 1;
152	}
153	if (pData->pfIcmpCloseHandle == NULL)
154	{
155	LogRel(("NAT: Can't find IcmpCloseHandle symbol\n"));
156	return 1;
157	}
158
159	pData->icmp_socket.sh = IcmpCreateFile();
160	pData->phEvents[VBOX_ICMP_EVENT_INDEX] = CreateEvent(NULL, FALSE, FALSE, NULL);
161	pData->cbIcmpBuffer = sizeof(ICMP_ECHO_REPLY) * 10;
162	pData->pvIcmpBuffer = RTMemAlloc(pData->cbIcmpBuffer);
163	#endif /* RT_OS_WINDOWS */
164
165	LIST_INIT(&pData->icmp_msg_head);
166	return 0;
167	}
168
169	/**
170	* Cleans ICMP cache.
171	*/
172	void
173	icmp_finit(PNATState pData)
174	{
175	icmp_cache_clean(pData, -1);
176	#ifdef RT_OS_WINDOWS
177	pData->pfIcmpCloseHandle(pData->icmp_socket.sh);
178	RTMemFree(pData->pvIcmpBuffer);
179	#else
180	closesocket(pData->icmp_socket.s);
181	#endif
182	}
183
184	/*
185	* ip here is ip header + 64bytes readed from ICMP packet
186	*/
187	struct icmp_msg *
188	icmp_find_original_mbuf(PNATState pData, struct ip *ip)
189	{
190	struct mbuf *m0;
191	struct ip *ip0;
192	struct icmp icp, icp0;
193	struct icmp_msg *icm = NULL;
194	int found = 0;
195	struct udphdr *udp;
196	struct tcphdr *tcp;
197	struct socket *head_socket = NULL;
198	struct socket *last_socket = NULL;
199	struct socket *so = NULL;
200	struct in_addr faddr;
201	u_short lport, fport;
202
203	faddr.s_addr = ~0;
204
205	lport = ~0;
206	fport = ~0;
207
208
209	LogFlowFunc(("ENTER: ip->ip_p:%d\n", ip->ip_p));
210	switch (ip->ip_p)
211	{
212	case IPPROTO_ICMP:
213	icp = (struct icmp )((char )ip + (ip->ip_hl << 2));
214	LIST_FOREACH(icm, &pData->icmp_msg_head, im_list)
215	{
216	m0 = icm->im_m;
217	ip0 = mtod(m0, struct ip *);
218	if (ip0->ip_p != IPPROTO_ICMP)
219	{
220	/* try next item */
221	continue;
222	}
223	icp0 = (struct icmp )((char )ip0 + (ip0->ip_hl << 2));
224	/*
225	* IP could pointer to ICMP_REPLY datagram (1)
226	* or pointer IP header in ICMP payload in case of
227	* ICMP_TIMXCEED or ICMP_UNREACH (2)
228	*
229	* if (1) and then ICMP (type should be ICMP_ECHOREPLY) and we need check that
230	* IP.IP_SRC == IP0.IP_DST received datagramm comes from destination.
231	*
232	* if (2) then check that payload ICMP has got type ICMP_ECHO and
233	* IP.IP_DST == IP0.IP_DST destination of returned datagram is the same as
234	* one was sent.
235	*/
236	if ( ( (icp->icmp_type != ICMP_ECHO && ip->ip_src.s_addr == ip0->ip_dst.s_addr)
237	\|\| (icp->icmp_type == ICMP_ECHO && ip->ip_dst.s_addr == ip0->ip_dst.s_addr))
238	&& icp->icmp_id == icp0->icmp_id
239	&& icp->icmp_seq == icp0->icmp_seq)
240	{
241	found = 1;
242	Log(("Have found %R[natsock]\n", icm->im_so));
243	break;
244	}
245	Log(("Have found nothing\n"));
246	}
247	break;
248
249	/*
250	* for TCP and UDP logic little bit reverted, we try to find the HOST socket
251	* from which the IP package has been sent.
252	*/
253	case IPPROTO_UDP:
254	head_socket = &udb;
255	udp = (struct udphdr )((char )ip + (ip->ip_hl << 2));
256	faddr.s_addr = ip->ip_dst.s_addr;
257	fport = udp->uh_dport;
258	lport = udp->uh_sport;
259	last_socket = udp_last_so;
260	/* fall through */
261
262	case IPPROTO_TCP:
263	if (head_socket == NULL)
264	{
265	tcp = (struct tcphdr )((char )ip + (ip->ip_hl << 2));
266	head_socket = &tcb; /* head_socket could be initialized with udb*/
267	faddr.s_addr = ip->ip_dst.s_addr;
268	fport = tcp->th_dport;
269	lport = tcp->th_sport;
270	last_socket = tcp_last_so;
271	}
272	/* check last socket first */
273	if ( last_socket->so_faddr.s_addr == faddr.s_addr
274	&& last_socket->so_fport == fport
275	&& last_socket->so_hlport == lport)
276	{
277	found = 1;
278	so = last_socket;
279	goto sofound;
280	}
281	for (so = head_socket->so_prev; so != head_socket; so = so->so_prev)
282	{
283	/* Should be reaplaced by hash here */
284	Log(("trying:%R[natsock] against %RTnaipv4:%d lport=%d hlport=%d\n", so, &faddr, fport, lport, so->so_hlport));
285	if ( so->so_faddr.s_addr == faddr.s_addr
286	&& so->so_fport == fport
287	&& so->so_hlport == lport)
288	{
289	found = 1;
290	break;
291	}
292	}
293	break;
294
295	default:
296	Log(("NAT:ICMP: unsupported protocol(%d)\n", ip->ip_p));
297	}
298	sofound:
299	if (found == 1 && icm == NULL)
300	{
301	if (so->so_state == SS_NOFDREF)
302	{
303	/* socket is shutdowning we've already sent ICMP on it.*/
304	Log(("NAT: Received icmp on shutdowning socket (probably corresponding ICMP socket has been already sent)\n"));
305	return NULL;
306	}
307	icm = RTMemAlloc(sizeof(struct icmp_msg));
308	icm->im_m = so->so_m;
309	icm->im_so = so;
310	found = 1;
311	Log(("hit:%R[natsock]\n", so));
312	/*XXX: this storage not very long,
313	* better add flag if it should removed from lis
314	*/
315	LIST_INSERT_HEAD(&pData->icmp_msg_head, icm, im_list);
316	pData->cIcmpCacheSize++;
317	if (pData->cIcmpCacheSize > pData->iIcmpCacheLimit)
318	icmp_cache_clean(pData, pData->iIcmpCacheLimit/2);
319	LogFlowFunc(("LEAVE: icm:%p\n", icm));
320	return (icm);
321	}
322	if (found == 1)
323	{
324	LogFlowFunc(("LEAVE: icm:%p\n", icm));
325	return icm;
326	}
327
328	LogFlowFunc(("LEAVE: NULL\n"));
329	return NULL;
330	}
331
332	/**
333	* iEntries how many entries to leave, if iEntries < 0, clean all
334	*/
335	static void icmp_cache_clean(PNATState pData, int iEntries)
336	{
337	int iIcmpCount = 0;
338	struct icmp_msg *icm = NULL;
339	LogFlowFunc(("iEntries:%d\n", iEntries));
340	if (iEntries > pData->cIcmpCacheSize)
341	{
342	LogFlowFuncLeave();
343	return;
344	}
345	while(!LIST_EMPTY(&pData->icmp_msg_head))
346	{
347	icm = LIST_FIRST(&pData->icmp_msg_head);
348	if ( iEntries > 0
349	&& iIcmpCount < iEntries)
350	{
351	iIcmpCount++;
352	continue;
353	}
354
355	LIST_REMOVE(icm, im_list);
356	if (icm->im_m)
357	{
358	pData->cIcmpCacheSize--;
359	m_freem(pData, icm->im_m);
360	}
361	RTMemFree(icm);
362	}
363	LogFlowFuncLeave();
364	}
365
366	static int
367	icmp_attach(PNATState pData, struct mbuf *m)
368	{
369	struct icmp_msg *icm;
370	struct ip *ip;
371	ip = mtod(m, struct ip *);
372	Assert(ip->ip_p == IPPROTO_ICMP);
373	icm = RTMemAlloc(sizeof(struct icmp_msg));
374	icm->im_m = m;
375	icm->im_so = m->m_so;
376	LIST_INSERT_HEAD(&pData->icmp_msg_head, icm, im_list);
377	pData->cIcmpCacheSize++;
378	if (pData->cIcmpCacheSize > pData->iIcmpCacheLimit)
379	icmp_cache_clean(pData, pData->iIcmpCacheLimit/2);
380	return 0;
381	}
382
383	/*
384	* Process a received ICMP message.
385	*/
386	void
387	icmp_input(PNATState pData, struct mbuf *m, int hlen)
388	{
389	register struct icmp *icp;
390	void *icp_buf = NULL;
391	register struct ip ip = mtod(m, struct ip );
392	int icmplen = ip->ip_len;
393	int status;
394	uint32_t dst;
395	#if !defined(RT_OS_WINDOWS)
396	int ttl;
397	#endif
398
399	/* int code; */
400
401	LogFlowFunc(("ENTER: m = %lx, m_len = %d\n", (long)m, m ? m->m_len : 0));
402
403	icmpstat.icps_received++;
404
405	/*
406	* Locate icmp structure in mbuf, and check
407	* that its not corrupted and of at least minimum length.
408	*/
409	if (icmplen < ICMP_MINLEN)
410	{
411	/* min 8 bytes payload */
412	icmpstat.icps_tooshort++;
413	goto end_error_free_m;
414	}
415
416	m->m_len -= hlen;
417	m->m_data += hlen;
418
419	if (cksum(m, icmplen))
420	{
421	icmpstat.icps_checksum++;
422	goto end_error_free_m;
423	}
424
425	if (m->m_next)
426	{
427	icp_buf = RTMemAlloc(icmplen);
428	if (!icp_buf)
429	{
430	Log(("NAT: not enought memory to allocate the buffer\n"));
431	goto end_error_free_m;
432	}
433	m_copydata(m, 0, icmplen, icp_buf);
434	icp = (struct icmp *)icp_buf;
435	}
436	else
437	icp = mtod(m, struct icmp *);
438
439	m->m_len += hlen;
440	m->m_data -= hlen;
441
442	/* icmpstat.icps_inhist[icp->icmp_type]++; */
443	/* code = icp->icmp_code; */
444
445	LogFlow(("icmp_type = %d\n", icp->icmp_type));
446	switch (icp->icmp_type)
447	{
448	case ICMP_ECHO:
449	ip->ip_len += hlen; /* since ip_input subtracts this */
450	dst = ip->ip_dst.s_addr;
451	if ( CTL_CHECK(dst, CTL_ALIAS)
452	\|\| CTL_CHECK(dst, CTL_DNS)
453	\|\| CTL_CHECK(dst, CTL_TFTP))
454	{
455	icp->icmp_type = ICMP_ECHOREPLY;
456	ip->ip_dst.s_addr = ip->ip_src.s_addr;
457	ip->ip_src.s_addr = dst;
458	icmp_reflect(pData, m);
459	goto done;
460	}
461	else
462	{
463	struct sockaddr_in addr;
464	#ifdef RT_OS_WINDOWS
465	IP_OPTION_INFORMATION ipopt;
466	int error;
467	#endif
468	addr.sin_family = AF_INET;
469	if ((ip->ip_dst.s_addr & RT_H2N_U32(pData->netmask)) == pData->special_addr.s_addr)
470	{
471	/* It's an alias */
472	switch (RT_N2H_U32(ip->ip_dst.s_addr) & ~pData->netmask)
473	{
474	case CTL_DNS:
475	case CTL_ALIAS:
476	default:
477	addr.sin_addr = loopback_addr;
478	break;
479	}
480	}
481	else
482	addr.sin_addr.s_addr = ip->ip_dst.s_addr;
483	#ifndef RT_OS_WINDOWS
484	if (pData->icmp_socket.s != -1)
485	{
486	ssize_t rc;
487	static bool fIcmpSocketErrorReported;
488	ttl = ip->ip_ttl;
489	Log(("NAT/ICMP: try to set TTL(%d)\n", ttl));
490	status = setsockopt(pData->icmp_socket.s, IPPROTO_IP, IP_TTL,
491	(void *)&ttl, sizeof(ttl));
492	if (status < 0)
493	Log(("NAT: Error (%s) occurred while setting TTL attribute of IP packet\n",
494	strerror(errno)));
495	rc = sendto(pData->icmp_socket.s, icp, icmplen, 0,
496	(struct sockaddr *)&addr, sizeof(addr));
497	if (rc >= 0)
498	{
499	m->m_so = &pData->icmp_socket;
500	icmp_attach(pData, m);
501	/* don't let m_freem at the end free atached buffer */
502	goto done;
503	}
504
505
506	if (!fIcmpSocketErrorReported)
507	{
508	LogRel(("icmp_input udp sendto tx errno = %d (%s)\n",
509	errno, strerror(errno)));
510	fIcmpSocketErrorReported = true;
511	}
512	icmp_error(pData, m, ICMP_UNREACH, ICMP_UNREACH_NET, 0, strerror(errno));
513	}
514	#else /* RT_OS_WINDOWS */
515	pData->icmp_socket.so_laddr.s_addr = ip->ip_src.s_addr; /* XXX: hack*/
516	pData->icmp_socket.so_icmp_id = icp->icmp_id;
517	pData->icmp_socket.so_icmp_seq = icp->icmp_seq;
518	memset(&ipopt, 0, sizeof(IP_OPTION_INFORMATION));
519	ipopt.Ttl = ip->ip_ttl;
520	status = IcmpSendEcho2(pData->icmp_socket.sh /=handle/,
521	pData->phEvents[VBOX_ICMP_EVENT_INDEX] /=Event/,
522	NULL /=ApcRoutine/,
523	NULL /=ApcContext/,
524	addr.sin_addr.s_addr /=DestinationAddress/,
525	icp->icmp_data /=RequestData/,
526	icmplen - ICMP_MINLEN /=RequestSize/,
527	&ipopt /=RequestOptions/,
528	pData->pvIcmpBuffer /=ReplyBuffer/,
529	pData->cbIcmpBuffer /=ReplySize/,
530	1 /=Timeout in ms/);
531	error = GetLastError();
532	if ( status != 0
533	\|\| error == ERROR_IO_PENDING)
534	{
535	/* no error! */
536	m->m_so = &pData->icmp_socket;
537	icmp_attach(pData, m);
538	/* don't let m_freem at the end free atached buffer */
539	goto done;
540	}
541	Log(("NAT: Error (%d) occurred while sending ICMP (", error));
542	switch (error)
543	{
544	case ERROR_INVALID_PARAMETER:
545	Log(("icmp_socket:%lx is invalid)\n", pData->icmp_socket.s));
546	break;
547	case ERROR_NOT_SUPPORTED:
548	Log(("operation is unsupported)\n"));
549	break;
550	case ERROR_NOT_ENOUGH_MEMORY:
551	Log(("OOM!!!)\n"));
552	break;
553	case IP_BUF_TOO_SMALL:
554	Log(("Buffer too small)\n"));
555	break;
556	default:
557	Log(("Other error!!!)\n"));
558	break;
559	}
560	#endif /* RT_OS_WINDOWS */
561	} /* if ip->ip_dst.s_addr == alias_addr.s_addr */
562	break;
563	case ICMP_UNREACH:
564	case ICMP_TIMXCEED:
565	/* @todo(vvl): both up cases comes from guest,
566	* indeed right solution would be find the socket
567	* corresponding to ICMP data and close it.
568	*/
569	case ICMP_PARAMPROB:
570	case ICMP_SOURCEQUENCH:
571	case ICMP_TSTAMP:
572	case ICMP_MASKREQ:
573	case ICMP_REDIRECT:
574	icmpstat.icps_notsupp++;
575	break;
576
577	default:
578	icmpstat.icps_badtype++;
579	} /* switch */
580
581	end_error_free_m:
582	m_freem(pData, m);
583
584	done:
585	if (icp_buf)
586	RTMemFree(icp_buf);
587	}
588
589
590	/**
591	* Send an ICMP message in response to a situation
592	*
593	* RFC 1122: 3.2.2 MUST send at least the IP header and 8 bytes of header. MAY send more (we do).
594	* MUST NOT change this header information.
595	* MUST NOT reply to a multicast/broadcast IP address.
596	* MUST NOT reply to a multicast/broadcast MAC address.
597	* MUST reply to only the first fragment.
598	*
599	* Send ICMP_UNREACH back to the source regarding msrc.
600	* It is reported as the bad ip packet. The header should
601	* be fully correct and in host byte order.
602	* ICMP fragmentation is illegal.
603	*
604	* @note: implementation note: MSIZE is 256 bytes (minimal buffer).
605	* We always truncate original payload to 8 bytes required by the RFC,
606	* so the largest possible datagram is 14 (ethernet) + 20 (ip) +
607	* 8 (icmp) + 60 (max original ip with options) + 8 (original payload)
608	* = 110 bytes which fits into sinlge mbuf.
609	*
610	* @note This function will free msrc!
611	*/
612
613	void icmp_error(PNATState pData, struct mbuf msrc, u_char type, u_char code, int minsize, const char message)
614	{
615	unsigned ohlen, olen;
616	struct mbuf *m;
617	struct ip oip, ip;
618	struct icmp *icp;
619	void *payload;
620
621	LogFlow(("icmp_error: msrc = %p, msrc_len = %d\n",
622	(void *)msrc, msrc ? msrc->m_len : 0));
623
624	if (RT_UNLIKELY(msrc == NULL))
625	goto end_error;
626
627	M_ASSERTPKTHDR(msrc);
628
629	if ( type != ICMP_UNREACH
630	&& type != ICMP_TIMXCEED
631	&& type != ICMP_SOURCEQUENCH)
632	goto end_error;
633
634	oip = mtod(msrc, struct ip *);
635	LogFunc(("msrc: %RTnaipv4 -> %RTnaipv4\n", oip->ip_src, oip->ip_dst));
636
637	if (oip->ip_src.s_addr == INADDR_ANY)
638	goto end_error;
639
640	if (oip->ip_off & IP_OFFMASK)
641	goto end_error; /* Only reply to fragment 0 */
642
643	ohlen = oip->ip_hl * 4;
644	AssertStmt(ohlen >= sizeof(struct ip), goto end_error);
645
646	olen = oip->ip_len;
647	AssertStmt(olen >= ohlen, goto end_error);
648
649	if (oip->ip_p == IPPROTO_ICMP)
650	{
651	struct icmp oicp = (struct icmp )((char *)oip + ohlen);
652	/*
653	* Assume any unknown ICMP type is an error. This isn't
654	* specified by the RFC, but think about it..
655	*/
656	if (oicp->icmp_type > ICMP_MAXTYPE \|\| icmp_flush[oicp->icmp_type])
657	goto end_error;
658	}
659
660	/* undo byte order conversions done in ip_input() */
661	HTONS(oip->ip_len);
662	HTONS(oip->ip_id);
663	HTONS(oip->ip_off);
664
665	m = m_gethdr(pData, M_NOWAIT, MT_HEADER);
666	if (RT_UNLIKELY(m == NULL))
667	goto end_error;
668
669	m->m_flags \|= M_SKIP_FIREWALL;
670	m->m_data += if_maxlinkhdr;
671
672	ip = mtod(m, struct ip *);
673	m->m_pkthdr.header = (void *)ip;
674
675	/* fill in ip (ip_output0() does the boilerplate for us) */
676	ip->ip_tos = ((oip->ip_tos & 0x1E) \| 0xC0); /* high priority for errors */
677	/* ip->ip_len will be set later */
678	ip->ip_off = 0;
679	ip->ip_ttl = MAXTTL;
680	ip->ip_p = IPPROTO_ICMP;
681	ip->ip_src = alias_addr;
682	ip->ip_dst = oip->ip_src;
683
684	/* fill in icmp */
685	icp = (struct icmp )((char )ip + sizeof(*ip));
686	icp->icmp_type = type;
687	icp->icmp_code = code;
688	icp->icmp_id = 0;
689	icp->icmp_seq = 0;
690
691	/* fill in icmp payload: original ip header plus 8 bytes of its payload */
692	if (olen > ohlen + 8)
693	olen = ohlen + 8;
694	payload = (void )((char )icp + ICMP_MINLEN);
695	memcpy(payload, oip, olen);
696
697	/*
698	* Original code appended this message after the payload. This
699	* might have been a good idea for real slirp, as it provided a
700	* communication channel with the remote host. But 90s are over.
701	*/
702	NOREF(message);
703
704	/* hide ip header for icmp checksum calculation */
705	m->m_data += sizeof(struct ip);
706	m->m_len = ICMP_MINLEN + /* truncated */ olen;
707
708	icp->icmp_cksum = 0;
709	icp->icmp_cksum = cksum(m, m->m_len);
710
711	/* reveal ip header */
712	m->m_data -= sizeof(struct ip);
713	m->m_len += sizeof(struct ip);
714	ip->ip_len = m->m_len;
715
716	(void) ip_output0(pData, (struct socket *)NULL, m, 1);
717
718	icmpstat.icps_reflect++;
719
720	/* clear source datagramm in positive branch */
721	m_freem(pData, msrc);
722	LogFlowFuncLeave();
723	return;
724
725	end_error:
726
727	/*
728	* clear source datagramm in case if some of requirement haven't been met.
729	*/
730	if (msrc)
731	m_freem(pData, msrc);
732
733	{
734	static bool fIcmpErrorReported;
735	if (!fIcmpErrorReported)
736	{
737	LogRel(("NAT: error occurred while sending ICMP error message\n"));
738	fIcmpErrorReported = true;
739	}
740	}
741	LogFlowFuncLeave();
742	}
743
744	/*
745	* Reflect the ip packet back to the source
746	* Note: m isn't duplicated by this method and more delivered to ip_output then.
747	*/
748	void
749	icmp_reflect(PNATState pData, struct mbuf *m)
750	{
751	register struct ip ip = mtod(m, struct ip );
752	int hlen = ip->ip_hl << 2;
753	register struct icmp *icp;
754	LogFlowFunc(("ENTER: m:%p\n", m));
755
756	/*
757	* Send an icmp packet back to the ip level,
758	* after supplying a checksum.
759	*/
760	m->m_data += hlen;
761	m->m_len -= hlen;
762	icp = mtod(m, struct icmp *);
763
764	icp->icmp_cksum = 0;
765	icp->icmp_cksum = cksum(m, ip->ip_len - hlen);
766
767	m->m_data -= hlen;
768	m->m_len += hlen;
769
770	(void) ip_output(pData, (struct socket *)NULL, m);
771
772	icmpstat.icps_reflect++;
773	LogFlowFuncLeave();
774	}

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source: vbox/trunk/src/VBox/Devices/Network/slirp/ip_icmp.c@ 52343

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