slirp: fix pinging the virtual ipv4 DNS server
[qemu.git] / slirp / ip_icmp.c
1 /*
2 * Copyright (c) 1982, 1986, 1988, 1993
3 * The Regents of the University of California. All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
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.
16 *
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
27 * SUCH DAMAGE.
28 *
29 * @(#)ip_icmp.c 8.2 (Berkeley) 1/4/94
30 * ip_icmp.c,v 1.7 1995/05/30 08:09:42 rgrimes Exp
31 */
32
33 #include "qemu/osdep.h"
34 #include "slirp.h"
35 #include "ip_icmp.h"
36
37 /* The message sent when emulating PING */
38 /* Be nice and tell them it's just a pseudo-ping packet */
39 static const char icmp_ping_msg[] = "This is a pseudo-PING packet used by Slirp to emulate ICMP ECHO-REQUEST packets.\n";
40
41 /* list of actions for icmp_send_error() on RX of an icmp message */
42 static const int icmp_flush[19] = {
43 /* ECHO REPLY (0) */ 0,
44 1,
45 1,
46 /* DEST UNREACH (3) */ 1,
47 /* SOURCE QUENCH (4)*/ 1,
48 /* REDIRECT (5) */ 1,
49 1,
50 1,
51 /* ECHO (8) */ 0,
52 /* ROUTERADVERT (9) */ 1,
53 /* ROUTERSOLICIT (10) */ 1,
54 /* TIME EXCEEDED (11) */ 1,
55 /* PARAMETER PROBLEM (12) */ 1,
56 /* TIMESTAMP (13) */ 0,
57 /* TIMESTAMP REPLY (14) */ 0,
58 /* INFO (15) */ 0,
59 /* INFO REPLY (16) */ 0,
60 /* ADDR MASK (17) */ 0,
61 /* ADDR MASK REPLY (18) */ 0
62 };
63
64 void icmp_init(Slirp *slirp)
65 {
66 slirp->icmp.so_next = slirp->icmp.so_prev = &slirp->icmp;
67 slirp->icmp_last_so = &slirp->icmp;
68 }
69
70 void icmp_cleanup(Slirp *slirp)
71 {
72 while (slirp->icmp.so_next != &slirp->icmp) {
73 icmp_detach(slirp->icmp.so_next);
74 }
75 }
76
77 static int icmp_send(struct socket *so, struct mbuf *m, int hlen)
78 {
79 struct ip *ip = mtod(m, struct ip *);
80 struct sockaddr_in addr;
81
82 so->s = qemu_socket(AF_INET, SOCK_DGRAM, IPPROTO_ICMP);
83 if (so->s == -1) {
84 return -1;
85 }
86
87 so->so_m = m;
88 so->so_faddr = ip->ip_dst;
89 so->so_laddr = ip->ip_src;
90 so->so_iptos = ip->ip_tos;
91 so->so_type = IPPROTO_ICMP;
92 so->so_state = SS_ISFCONNECTED;
93 so->so_expire = curtime + SO_EXPIRE;
94
95 addr.sin_family = AF_INET;
96 addr.sin_addr = so->so_faddr;
97
98 insque(so, &so->slirp->icmp);
99
100 if (sendto(so->s, m->m_data + hlen, m->m_len - hlen, 0,
101 (struct sockaddr *)&addr, sizeof(addr)) == -1) {
102 DEBUG_MISC((dfd, "icmp_input icmp sendto tx errno = %d-%s\n",
103 errno, strerror(errno)));
104 icmp_send_error(m, ICMP_UNREACH, ICMP_UNREACH_NET, 0, strerror(errno));
105 icmp_detach(so);
106 }
107
108 return 0;
109 }
110
111 void icmp_detach(struct socket *so)
112 {
113 closesocket(so->s);
114 sofree(so);
115 }
116
117 /*
118 * Process a received ICMP message.
119 */
120 void
121 icmp_input(struct mbuf *m, int hlen)
122 {
123 register struct icmp *icp;
124 register struct ip *ip=mtod(m, struct ip *);
125 int icmplen=ip->ip_len;
126 Slirp *slirp = m->slirp;
127
128 DEBUG_CALL("icmp_input");
129 DEBUG_ARG("m = %p", m);
130 DEBUG_ARG("m_len = %d", m->m_len);
131
132 /*
133 * Locate icmp structure in mbuf, and check
134 * that its not corrupted and of at least minimum length.
135 */
136 if (icmplen < ICMP_MINLEN) { /* min 8 bytes payload */
137 freeit:
138 m_free(m);
139 goto end_error;
140 }
141
142 m->m_len -= hlen;
143 m->m_data += hlen;
144 icp = mtod(m, struct icmp *);
145 if (cksum(m, icmplen)) {
146 goto freeit;
147 }
148 m->m_len += hlen;
149 m->m_data -= hlen;
150
151 DEBUG_ARG("icmp_type = %d", icp->icmp_type);
152 switch (icp->icmp_type) {
153 case ICMP_ECHO:
154 ip->ip_len += hlen; /* since ip_input subtracts this */
155 if (ip->ip_dst.s_addr == slirp->vhost_addr.s_addr ||
156 ip->ip_dst.s_addr == slirp->vnameserver_addr.s_addr) {
157 icmp_reflect(m);
158 } else if (slirp->restricted) {
159 goto freeit;
160 } else {
161 struct socket *so;
162 struct sockaddr_storage addr;
163 if ((so = socreate(slirp)) == NULL) goto freeit;
164 if (icmp_send(so, m, hlen) == 0) {
165 return;
166 }
167 if (udp_attach(so, AF_INET) == -1) {
168 DEBUG_MISC((dfd,"icmp_input udp_attach errno = %d-%s\n",
169 errno,strerror(errno)));
170 sofree(so);
171 m_free(m);
172 goto end_error;
173 }
174 so->so_m = m;
175 so->so_ffamily = AF_INET;
176 so->so_faddr = ip->ip_dst;
177 so->so_fport = htons(7);
178 so->so_lfamily = AF_INET;
179 so->so_laddr = ip->ip_src;
180 so->so_lport = htons(9);
181 so->so_iptos = ip->ip_tos;
182 so->so_type = IPPROTO_ICMP;
183 so->so_state = SS_ISFCONNECTED;
184
185 /* Send the packet */
186 addr = so->fhost.ss;
187 sotranslate_out(so, &addr);
188
189 if(sendto(so->s, icmp_ping_msg, strlen(icmp_ping_msg), 0,
190 (struct sockaddr *)&addr, sockaddr_size(&addr)) == -1) {
191 DEBUG_MISC((dfd,"icmp_input udp sendto tx errno = %d-%s\n",
192 errno,strerror(errno)));
193 icmp_send_error(m, ICMP_UNREACH, ICMP_UNREACH_NET, 0, strerror(errno));
194 udp_detach(so);
195 }
196 } /* if ip->ip_dst.s_addr == alias_addr.s_addr */
197 break;
198 case ICMP_UNREACH:
199 /* XXX? report error? close socket? */
200 case ICMP_TIMXCEED:
201 case ICMP_PARAMPROB:
202 case ICMP_SOURCEQUENCH:
203 case ICMP_TSTAMP:
204 case ICMP_MASKREQ:
205 case ICMP_REDIRECT:
206 m_free(m);
207 break;
208
209 default:
210 m_free(m);
211 } /* swith */
212
213 end_error:
214 /* m is m_free()'d xor put in a socket xor or given to ip_send */
215 return;
216 }
217
218
219 /*
220 * Send an ICMP message in response to a situation
221 *
222 * RFC 1122: 3.2.2 MUST send at least the IP header and 8 bytes of header. MAY send more (we do).
223 * MUST NOT change this header information.
224 * MUST NOT reply to a multicast/broadcast IP address.
225 * MUST NOT reply to a multicast/broadcast MAC address.
226 * MUST reply to only the first fragment.
227 */
228 /*
229 * Send ICMP_UNREACH back to the source regarding msrc.
230 * mbuf *msrc is used as a template, but is NOT m_free()'d.
231 * It is reported as the bad ip packet. The header should
232 * be fully correct and in host byte order.
233 * ICMP fragmentation is illegal. All machines must accept 576 bytes in one
234 * packet. The maximum payload is 576-20(ip hdr)-8(icmp hdr)=548
235 */
236
237 #define ICMP_MAXDATALEN (IP_MSS-28)
238 void
239 icmp_send_error(struct mbuf *msrc, u_char type, u_char code, int minsize,
240 const char *message)
241 {
242 unsigned hlen, shlen, s_ip_len;
243 register struct ip *ip;
244 register struct icmp *icp;
245 register struct mbuf *m;
246
247 DEBUG_CALL("icmp_send_error");
248 DEBUG_ARG("msrc = %p", msrc);
249 DEBUG_ARG("msrc_len = %d", msrc->m_len);
250
251 if(type!=ICMP_UNREACH && type!=ICMP_TIMXCEED) goto end_error;
252
253 /* check msrc */
254 if(!msrc) goto end_error;
255 ip = mtod(msrc, struct ip *);
256 #ifdef DEBUG
257 { char bufa[20], bufb[20];
258 strcpy(bufa, inet_ntoa(ip->ip_src));
259 strcpy(bufb, inet_ntoa(ip->ip_dst));
260 DEBUG_MISC((dfd, " %.16s to %.16s\n", bufa, bufb));
261 }
262 #endif
263 if(ip->ip_off & IP_OFFMASK) goto end_error; /* Only reply to fragment 0 */
264
265 /* Do not reply to source-only IPs */
266 if ((ip->ip_src.s_addr & htonl(~(0xf << 28))) == 0) {
267 goto end_error;
268 }
269
270 shlen=ip->ip_hl << 2;
271 s_ip_len=ip->ip_len;
272 if(ip->ip_p == IPPROTO_ICMP) {
273 icp = (struct icmp *)((char *)ip + shlen);
274 /*
275 * Assume any unknown ICMP type is an error. This isn't
276 * specified by the RFC, but think about it..
277 */
278 if(icp->icmp_type>18 || icmp_flush[icp->icmp_type]) goto end_error;
279 }
280
281 /* make a copy */
282 m = m_get(msrc->slirp);
283 if (!m) {
284 goto end_error;
285 }
286
287 { int new_m_size;
288 new_m_size=sizeof(struct ip )+ICMP_MINLEN+msrc->m_len+ICMP_MAXDATALEN;
289 if(new_m_size>m->m_size) m_inc(m, new_m_size);
290 }
291 memcpy(m->m_data, msrc->m_data, msrc->m_len);
292 m->m_len = msrc->m_len; /* copy msrc to m */
293
294 /* make the header of the reply packet */
295 ip = mtod(m, struct ip *);
296 hlen= sizeof(struct ip ); /* no options in reply */
297
298 /* fill in icmp */
299 m->m_data += hlen;
300 m->m_len -= hlen;
301
302 icp = mtod(m, struct icmp *);
303
304 if(minsize) s_ip_len=shlen+ICMP_MINLEN; /* return header+8b only */
305 else if(s_ip_len>ICMP_MAXDATALEN) /* maximum size */
306 s_ip_len=ICMP_MAXDATALEN;
307
308 m->m_len=ICMP_MINLEN+s_ip_len; /* 8 bytes ICMP header */
309
310 /* min. size = 8+sizeof(struct ip)+8 */
311
312 icp->icmp_type = type;
313 icp->icmp_code = code;
314 icp->icmp_id = 0;
315 icp->icmp_seq = 0;
316
317 memcpy(&icp->icmp_ip, msrc->m_data, s_ip_len); /* report the ip packet */
318 HTONS(icp->icmp_ip.ip_len);
319 HTONS(icp->icmp_ip.ip_id);
320 HTONS(icp->icmp_ip.ip_off);
321
322 #ifdef DEBUG
323 if(message) { /* DEBUG : append message to ICMP packet */
324 int message_len;
325 char *cpnt;
326 message_len=strlen(message);
327 if(message_len>ICMP_MAXDATALEN) message_len=ICMP_MAXDATALEN;
328 cpnt=(char *)m->m_data+m->m_len;
329 memcpy(cpnt, message, message_len);
330 m->m_len+=message_len;
331 }
332 #endif
333
334 icp->icmp_cksum = 0;
335 icp->icmp_cksum = cksum(m, m->m_len);
336
337 m->m_data -= hlen;
338 m->m_len += hlen;
339
340 /* fill in ip */
341 ip->ip_hl = hlen >> 2;
342 ip->ip_len = m->m_len;
343
344 ip->ip_tos=((ip->ip_tos & 0x1E) | 0xC0); /* high priority for errors */
345
346 ip->ip_ttl = MAXTTL;
347 ip->ip_p = IPPROTO_ICMP;
348 ip->ip_dst = ip->ip_src; /* ip addresses */
349 ip->ip_src = m->slirp->vhost_addr;
350
351 (void ) ip_output((struct socket *)NULL, m);
352
353 end_error:
354 return;
355 }
356 #undef ICMP_MAXDATALEN
357
358 /*
359 * Reflect the ip packet back to the source
360 */
361 void
362 icmp_reflect(struct mbuf *m)
363 {
364 register struct ip *ip = mtod(m, struct ip *);
365 int hlen = ip->ip_hl << 2;
366 int optlen = hlen - sizeof(struct ip );
367 register struct icmp *icp;
368
369 /*
370 * Send an icmp packet back to the ip level,
371 * after supplying a checksum.
372 */
373 m->m_data += hlen;
374 m->m_len -= hlen;
375 icp = mtod(m, struct icmp *);
376
377 icp->icmp_type = ICMP_ECHOREPLY;
378 icp->icmp_cksum = 0;
379 icp->icmp_cksum = cksum(m, ip->ip_len - hlen);
380
381 m->m_data -= hlen;
382 m->m_len += hlen;
383
384 /* fill in ip */
385 if (optlen > 0) {
386 /*
387 * Strip out original options by copying rest of first
388 * mbuf's data back, and adjust the IP length.
389 */
390 memmove((caddr_t)(ip + 1), (caddr_t)ip + hlen,
391 (unsigned )(m->m_len - hlen));
392 hlen -= optlen;
393 ip->ip_hl = hlen >> 2;
394 ip->ip_len -= optlen;
395 m->m_len -= optlen;
396 }
397
398 ip->ip_ttl = MAXTTL;
399 { /* swap */
400 struct in_addr icmp_dst;
401 icmp_dst = ip->ip_dst;
402 ip->ip_dst = ip->ip_src;
403 ip->ip_src = icmp_dst;
404 }
405
406 (void ) ip_output((struct socket *)NULL, m);
407 }
408
409 void icmp_receive(struct socket *so)
410 {
411 struct mbuf *m = so->so_m;
412 struct ip *ip = mtod(m, struct ip *);
413 int hlen = ip->ip_hl << 2;
414 u_char error_code;
415 struct icmp *icp;
416 int id, len;
417
418 m->m_data += hlen;
419 m->m_len -= hlen;
420 icp = mtod(m, struct icmp *);
421
422 id = icp->icmp_id;
423 len = qemu_recv(so->s, icp, m->m_len, 0);
424 icp->icmp_id = id;
425
426 m->m_data -= hlen;
427 m->m_len += hlen;
428
429 if (len == -1 || len == 0) {
430 if (errno == ENETUNREACH) {
431 error_code = ICMP_UNREACH_NET;
432 } else {
433 error_code = ICMP_UNREACH_HOST;
434 }
435 DEBUG_MISC((dfd, " udp icmp rx errno = %d-%s\n", errno,
436 strerror(errno)));
437 icmp_send_error(so->so_m, ICMP_UNREACH, error_code, 0, strerror(errno));
438 } else {
439 icmp_reflect(so->so_m);
440 so->so_m = NULL; /* Don't m_free() it again! */
441 }
442 icmp_detach(so);
443 }