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. All advertising materials mentioning features or use of this software
14 * must display the following acknowledgement:
15 * This product includes software developed by the University of
16 * California, Berkeley and its contributors.
17 * 4. Neither the name of the University nor the names of its contributors
18 * may be used to endorse or promote products derived from this software
19 * without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 *
33 * @(#)ip_icmp.c 8.2 (Berkeley) 1/4/94
34 * ip_icmp.c,v 1.7 1995/05/30 08:09:42 rgrimes Exp
35 */
36
37 #include "slirp.h"
38 #include "ip_icmp.h"
39 #include "sockets.h"
40
41 struct icmpstat icmpstat;
42
43 /* The message sent when emulating PING */
44 /* Be nice and tell them it's just a psuedo-ping packet */
45 char icmp_ping_msg[] = "This is a psuedo-PING packet used by Slirp to emulate ICMP ECHO-REQUEST packets.\n";
46
47 /* list of actions for icmp_error() on RX of an icmp message */
48 static int icmp_flush[19] = {
49 /* ECHO REPLY (0) */ 0,
50 1,
51 1,
52 /* DEST UNREACH (3) */ 1,
53 /* SOURCE QUENCH (4)*/ 1,
54 /* REDIRECT (5) */ 1,
55 1,
56 1,
57 /* ECHO (8) */ 0,
58 /* ROUTERADVERT (9) */ 1,
59 /* ROUTERSOLICIT (10) */ 1,
60 /* TIME EXCEEDED (11) */ 1,
61 /* PARAMETER PROBLEM (12) */ 1,
62 /* TIMESTAMP (13) */ 0,
63 /* TIMESTAMP REPLY (14) */ 0,
64 /* INFO (15) */ 0,
65 /* INFO REPLY (16) */ 0,
66 /* ADDR MASK (17) */ 0,
67 /* ADDR MASK REPLY (18) */ 0
68 };
69
70 /*
71 * Process a received ICMP message.
72 */
73 void
icmp_input(m,hlen)74 icmp_input(m, hlen)
75 MBuf m;
76 int hlen;
77 {
78 register struct icmp *icp;
79 register struct ip *ip=MBUF_TO(m, struct ip *);
80 int icmplen=ip->ip_len;
81 /* int code; */
82
83 DEBUG_CALL("icmp_input");
84 DEBUG_ARG("m = %lx", (long )m);
85 DEBUG_ARG("m_len = %d", m->m_len);
86
87 icmpstat.icps_received++;
88
89 /*
90 * Locate icmp structure in mbuf, and check
91 * that its not corrupted and of at least minimum length.
92 */
93 if (icmplen < ICMP_MINLEN) { /* min 8 bytes payload */
94 icmpstat.icps_tooshort++;
95 freeit:
96 mbuf_free(m);
97 goto end_error;
98 }
99
100 m->m_len -= hlen;
101 m->m_data += hlen;
102 icp = MBUF_TO(m, struct icmp *);
103 if (cksum(m, icmplen)) {
104 icmpstat.icps_checksum++;
105 goto freeit;
106 }
107 m->m_len += hlen;
108 m->m_data -= hlen;
109
110 /* icmpstat.icps_inhist[icp->icmp_type]++; */
111 /* code = icp->icmp_code; */
112
113 DEBUG_ARG("icmp_type = %d", icp->icmp_type);
114 switch (icp->icmp_type) {
115 case ICMP_ECHO:
116 icp->icmp_type = ICMP_ECHOREPLY;
117 ip->ip_len += hlen; /* since ip_input subtracts this */
118 if (ip_geth(ip->ip_dst) == alias_addr_ip) {
119 icmp_reflect(m);
120 } else {
121 struct socket *so;
122 SockAddress addr;
123 uint32_t addr_ip;
124 uint16_t addr_port;
125
126 if ((so = socreate()) == NULL) goto freeit;
127 if(udp_attach(so) == -1) {
128 DEBUG_MISC((dfd,"icmp_input udp_attach errno = %d-%s\n",
129 errno,errno_str));
130 sofree(so);
131 mbuf_free(m);
132 goto end_error;
133 }
134 so->so_m = m;
135 so->so_faddr_ip = ip_geth(ip->ip_dst);
136 so->so_faddr_port = 7;
137 so->so_laddr_ip = ip_geth(ip->ip_src);
138 so->so_laddr_port = 9;
139 so->so_iptos = ip->ip_tos;
140 so->so_type = IPPROTO_ICMP;
141 so->so_state = SS_ISFCONNECTED;
142
143 /* Send the packet */
144 if ((so->so_faddr_ip & 0xffffff00) == special_addr_ip) {
145 /* It's an alias */
146 int low = so->so_faddr_ip & 0xff;
147
148 if (low >= CTL_DNS && low < CTL_DNS + dns_addr_count)
149 addr_ip = dns_addr[low - CTL_DNS];
150 else
151 addr_ip = loopback_addr_ip;
152 } else {
153 addr_ip = so->so_faddr_ip;
154 }
155 addr_port = so->so_faddr_port;
156
157 sock_address_init_inet( &addr, addr_ip, addr_port );
158
159 if(socket_sendto(so->s, icmp_ping_msg, strlen(icmp_ping_msg), &addr) < 0) {
160 DEBUG_MISC((dfd,"icmp_input udp sendto tx errno = %d-%s\n",
161 errno,errno_str));
162 icmp_error(m, ICMP_UNREACH,ICMP_UNREACH_NET, 0,errno_str);
163 udp_detach(so);
164 }
165 } /* if ip->ip_dst.s_addr == alias_addr.s_addr */
166 break;
167 case ICMP_UNREACH:
168 /* XXX? report error? close socket? */
169 case ICMP_TIMXCEED:
170 case ICMP_PARAMPROB:
171 case ICMP_SOURCEQUENCH:
172 case ICMP_TSTAMP:
173 case ICMP_MASKREQ:
174 case ICMP_REDIRECT:
175 icmpstat.icps_notsupp++;
176 mbuf_free(m);
177 break;
178
179 default:
180 icmpstat.icps_badtype++;
181 mbuf_free(m);
182 } /* swith */
183
184 end_error:
185 /* m is mbuf_free()'d xor put in a socket xor or given to ip_send */
186 return;
187 }
188
189
190 /*
191 * Send an ICMP message in response to a situation
192 *
193 * RFC 1122: 3.2.2 MUST send at least the IP header and 8 bytes of header. MAY send more (we do).
194 * MUST NOT change this header information.
195 * MUST NOT reply to a multicast/broadcast IP address.
196 * MUST NOT reply to a multicast/broadcast MAC address.
197 * MUST reply to only the first fragment.
198 */
199 /*
200 * Send ICMP_UNREACH back to the source regarding msrc.
201 * mbuf *msrc is used as a template, but is NOT mbuf_free()'d.
202 * It is reported as the bad ip packet. The header should
203 * be fully correct and in host byte order.
204 * ICMP fragmentation is illegal. All machines must accept 576 bytes in one
205 * packet. The maximum payload is 576-20(ip hdr)-8(icmp hdr)=548
206 */
207
208 #define ICMP_MAXDATALEN (IP_MSS-28)
209 void
icmp_error(msrc,type,code,minsize,message)210 icmp_error(msrc, type, code, minsize, message)
211 MBuf msrc;
212 u_char type;
213 u_char code;
214 int minsize;
215 const char *message;
216 {
217 unsigned hlen, shlen, s_ip_len;
218 register struct ip *ip;
219 register struct icmp *icp;
220 register MBuf m;
221
222 DEBUG_CALL("icmp_error");
223 DEBUG_ARG("msrc = %lx", (long )msrc);
224 DEBUG_ARG("msrc_len = %d", msrc->m_len);
225
226 if(type!=ICMP_UNREACH && type!=ICMP_TIMXCEED) goto end_error;
227
228 /* check msrc */
229 if(!msrc) goto end_error;
230 ip = MBUF_TO(msrc, struct ip *);
231 #if DEBUG
232 { char bufa[20], bufb[20];
233 strcpy(bufa, inet_iptostr(ip_geth(ip->ip_src)));
234 strcpy(bufb, inet_iptostr(ip_geth(ip->ip_dst)));
235 DEBUG_MISC((dfd, " %.16s to %.16s\n", bufa, bufb));
236 }
237 #endif
238 if(ip->ip_off & IP_OFFMASK) goto end_error; /* Only reply to fragment 0 */
239
240 shlen=ip->ip_hl << 2;
241 s_ip_len=ip->ip_len;
242 if(ip->ip_p == IPPROTO_ICMP) {
243 icp = (struct icmp *)((char *)ip + shlen);
244 /*
245 * Assume any unknown ICMP type is an error. This isn't
246 * specified by the RFC, but think about it..
247 */
248 if(icp->icmp_type>18 || icmp_flush[icp->icmp_type]) goto end_error;
249 }
250
251 /* make a copy */
252 if(!(m=mbuf_alloc())) goto end_error; /* get mbuf */
253 { int new_m_size;
254 new_m_size=sizeof(struct ip )+ICMP_MINLEN+msrc->m_len+ICMP_MAXDATALEN;
255 if(new_m_size>m->m_size) mbuf_ensure(m, new_m_size);
256 }
257 memcpy(m->m_data, msrc->m_data, msrc->m_len);
258 m->m_len = msrc->m_len; /* copy msrc to m */
259
260 /* make the header of the reply packet */
261 ip = MBUF_TO(m, struct ip *);
262 hlen= sizeof(struct ip ); /* no options in reply */
263
264 /* fill in icmp */
265 m->m_data += hlen;
266 m->m_len -= hlen;
267
268 icp = MBUF_TO(m, struct icmp *);
269
270 if(minsize) s_ip_len=shlen+ICMP_MINLEN; /* return header+8b only */
271 else if(s_ip_len>ICMP_MAXDATALEN) /* maximum size */
272 s_ip_len=ICMP_MAXDATALEN;
273
274 m->m_len=ICMP_MINLEN+s_ip_len; /* 8 bytes ICMP header */
275
276 /* min. size = 8+sizeof(struct ip)+8 */
277
278 icp->icmp_type = type;
279 icp->icmp_code = code;
280 icp->icmp_id = 0;
281 icp->icmp_seq = 0;
282
283 memcpy(&icp->icmp_ip, msrc->m_data, s_ip_len); /* report the ip packet */
284 HTONS(icp->icmp_ip.ip_len);
285 HTONS(icp->icmp_ip.ip_id);
286 HTONS(icp->icmp_ip.ip_off);
287
288 #if DEBUG
289 if(message) { /* DEBUG : append message to ICMP packet */
290 int message_len;
291 char *cpnt;
292 message_len=strlen(message);
293 if(message_len>ICMP_MAXDATALEN) message_len=ICMP_MAXDATALEN;
294 cpnt=(char *)m->m_data+m->m_len;
295 memcpy(cpnt, message, message_len);
296 m->m_len+=message_len;
297 }
298 #endif
299
300 icp->icmp_cksum = 0;
301 icp->icmp_cksum = cksum(m, m->m_len);
302
303 m->m_data -= hlen;
304 m->m_len += hlen;
305
306 /* fill in ip */
307 ip->ip_hl = hlen >> 2;
308 ip->ip_len = m->m_len;
309
310 ip->ip_tos=((ip->ip_tos & 0x1E) | 0xC0); /* high priority for errors */
311
312 ip->ip_ttl = MAXTTL;
313 ip->ip_p = IPPROTO_ICMP;
314 ip->ip_dst = ip->ip_src; /* ip adresses */
315 ip->ip_src = ip_setn(alias_addr_ip);
316
317 (void ) ip_output((struct socket *)NULL, m);
318
319 icmpstat.icps_reflect++;
320
321 end_error:
322 return;
323 }
324 #undef ICMP_MAXDATALEN
325
326 /*
327 * Reflect the ip packet back to the source
328 */
329 void
icmp_reflect(m)330 icmp_reflect(m)
331 MBuf m;
332 {
333 register struct ip *ip = MBUF_TO(m, struct ip *);
334 int hlen = ip->ip_hl << 2;
335 int optlen = hlen - sizeof(struct ip );
336 register struct icmp *icp;
337
338 /*
339 * Send an icmp packet back to the ip level,
340 * after supplying a checksum.
341 */
342 m->m_data += hlen;
343 m->m_len -= hlen;
344 icp = MBUF_TO(m, struct icmp *);
345
346 icp->icmp_cksum = 0;
347 icp->icmp_cksum = cksum(m, ip->ip_len - hlen);
348
349 m->m_data -= hlen;
350 m->m_len += hlen;
351
352 /* fill in ip */
353 if (optlen > 0) {
354 /*
355 * Strip out original options by copying rest of first
356 * mbuf's data back, and adjust the IP length.
357 */
358 memmove((caddr_t)(ip + 1), (caddr_t)ip + hlen,
359 (unsigned )(m->m_len - hlen));
360 hlen -= optlen;
361 ip->ip_hl = hlen >> 2;
362 ip->ip_len -= optlen;
363 m->m_len -= optlen;
364 }
365
366 ip->ip_ttl = MAXTTL;
367 { /* swap */
368 ipaddr_t icmp_dst;
369 icmp_dst = ip->ip_dst;
370 ip->ip_dst = ip->ip_src;
371 ip->ip_src = icmp_dst;
372 }
373
374 (void ) ip_output((struct socket *)NULL, m);
375
376 icmpstat.icps_reflect++;
377 }
378