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
40 struct icmpstat icmpstat;
41
42 /* The message sent when emulating PING */
43 /* Be nice and tell them it's just a psuedo-ping packet */
44 char icmp_ping_msg[] = "This is a psuedo-PING packet used by Slirp to emulate ICMP ECHO-REQUEST packets.\n";
45
46 /* list of actions for icmp_error() on RX of an icmp message */
47 static int icmp_flush[19] = {
48 /* ECHO REPLY (0) */ 0,
49 1,
50 1,
51 /* DEST UNREACH (3) */ 1,
52 /* SOURCE QUENCH (4)*/ 1,
53 /* REDIRECT (5) */ 1,
54 1,
55 1,
56 /* ECHO (8) */ 0,
57 /* ROUTERADVERT (9) */ 1,
58 /* ROUTERSOLICIT (10) */ 1,
59 /* TIME EXCEEDED (11) */ 1,
60 /* PARAMETER PROBLEM (12) */ 1,
61 /* TIMESTAMP (13) */ 0,
62 /* TIMESTAMP REPLY (14) */ 0,
63 /* INFO (15) */ 0,
64 /* INFO REPLY (16) */ 0,
65 /* ADDR MASK (17) */ 0,
66 /* ADDR MASK REPLY (18) */ 0
67 };
68
69 /*
70 * Process a received ICMP message.
71 */
72 void
icmp_input(m,hlen)73 icmp_input(m, hlen)
74 struct mbuf *m;
75 int hlen;
76 {
77 register struct icmp *icp;
78 register struct ip *ip=mtod(m, struct ip *);
79 int icmplen=ip->ip_len;
80 /* int code; */
81
82 DEBUG_CALL("icmp_input");
83 DEBUG_ARG("m = %lx", (long )m);
84 DEBUG_ARG("m_len = %d", m->m_len);
85
86 icmpstat.icps_received++;
87
88 /*
89 * Locate icmp structure in mbuf, and check
90 * that its not corrupted and of at least minimum length.
91 */
92 if (icmplen < ICMP_MINLEN) { /* min 8 bytes payload */
93 icmpstat.icps_tooshort++;
94 freeit:
95 m_freem(m);
96 goto end_error;
97 }
98
99 m->m_len -= hlen;
100 m->m_data += hlen;
101 icp = mtod(m, struct icmp *);
102 if (cksum(m, icmplen)) {
103 icmpstat.icps_checksum++;
104 goto freeit;
105 }
106 m->m_len += hlen;
107 m->m_data -= hlen;
108
109 /* icmpstat.icps_inhist[icp->icmp_type]++; */
110 /* code = icp->icmp_code; */
111
112 DEBUG_ARG("icmp_type = %d", icp->icmp_type);
113 switch (icp->icmp_type) {
114 case ICMP_ECHO:
115 icp->icmp_type = ICMP_ECHOREPLY;
116 ip->ip_len += hlen; /* since ip_input subtracts this */
117 if (ip->ip_dst.s_addr == our_addr.s_addr ||
118 (ip->ip_dst.s_addr == (special_addr.s_addr|htonl(CTL_ALIAS))) ) {
119 icmp_reflect(m);
120 } else {
121 struct socket *so;
122 struct sockaddr_in addr;
123 if ((so = socreate()) == NULL) goto freeit;
124 if(udp_attach(so) == -1) {
125 DEBUG_MISC((dfd,"icmp_input udp_attach errno = %d-%s\n",
126 errno,strerror(errno)));
127 sofree(so);
128 m_free(m);
129 goto end_error;
130 }
131 so->so_m = m;
132 so->so_faddr = ip->ip_dst;
133 so->so_fport = htons(7);
134 so->so_laddr = ip->ip_src;
135 so->so_lport = htons(9);
136 so->so_iptos = ip->ip_tos;
137 so->so_type = IPPROTO_ICMP;
138 so->so_state = SS_ISFCONNECTED;
139
140 /* Send the packet */
141 addr.sin_family = AF_INET;
142 if ((so->so_faddr.s_addr & htonl(0xffffff00)) == special_addr.s_addr) {
143 /* It's an alias */
144 switch(ntohl(so->so_faddr.s_addr) & 0xff) {
145 case CTL_DNS:
146 addr.sin_addr = dns_addr;
147 break;
148 case CTL_ALIAS:
149 default:
150 addr.sin_addr = loopback_addr;
151 break;
152 }
153 } else {
154 addr.sin_addr = so->so_faddr;
155 }
156 addr.sin_port = so->so_fport;
157 if(sendto(so->s, icmp_ping_msg, strlen(icmp_ping_msg), 0,
158 (struct sockaddr *)&addr, sizeof(addr)) == -1) {
159 DEBUG_MISC((dfd,"icmp_input udp sendto tx errno = %d-%s\n",
160 errno,strerror(errno)));
161 icmp_error(m, ICMP_UNREACH,ICMP_UNREACH_NET, 0,strerror(errno));
162 udp_detach(so);
163 }
164 } /* if ip->ip_dst.s_addr == our_addr.s_addr */
165 break;
166 case ICMP_UNREACH:
167 /* XXX? report error? close socket? */
168 case ICMP_TIMXCEED:
169 case ICMP_PARAMPROB:
170 case ICMP_SOURCEQUENCH:
171 case ICMP_TSTAMP:
172 case ICMP_MASKREQ:
173 case ICMP_REDIRECT:
174 icmpstat.icps_notsupp++;
175 m_freem(m);
176 break;
177
178 default:
179 icmpstat.icps_badtype++;
180 m_freem(m);
181 } /* swith */
182
183 end_error:
184 /* m is m_free()'d xor put in a socket xor or given to ip_send */
185 return;
186 }
187
188
189 /*
190 * Send an ICMP message in response to a situation
191 *
192 * RFC 1122: 3.2.2 MUST send at least the IP header and 8 bytes of header. MAY send more (we do).
193 * MUST NOT change this header information.
194 * MUST NOT reply to a multicast/broadcast IP address.
195 * MUST NOT reply to a multicast/broadcast MAC address.
196 * MUST reply to only the first fragment.
197 */
198 /*
199 * Send ICMP_UNREACH back to the source regarding msrc.
200 * mbuf *msrc is used as a template, but is NOT m_free()'d.
201 * It is reported as the bad ip packet. The header should
202 * be fully correct and in host byte order.
203 * ICMP fragmentation is illegal. All machines must accept 576 bytes in one
204 * packet. The maximum payload is 576-20(ip hdr)-8(icmp hdr)=548
205 */
206
207 #define ICMP_MAXDATALEN (IP_MSS-28)
208 void
icmp_error(msrc,type,code,minsize,message)209 icmp_error(msrc, type, code, minsize, message)
210 struct mbuf *msrc;
211 u_char type;
212 u_char code;
213 int minsize;
214 char *message;
215 {
216 unsigned hlen, shlen, s_ip_len;
217 register struct ip *ip;
218 register struct icmp *icp;
219 register struct mbuf *m;
220
221 DEBUG_CALL("icmp_error");
222 DEBUG_ARG("msrc = %lx", (long )msrc);
223 DEBUG_ARG("msrc_len = %d", msrc->m_len);
224
225 if(type!=ICMP_UNREACH && type!=ICMP_TIMXCEED) goto end_error;
226
227 /* check msrc */
228 if(!msrc) goto end_error;
229 ip = mtod(msrc, struct ip *);
230 #if DEBUG
231 { char bufa[20], bufb[20];
232 strcpy(bufa, inet_ntoa(ip->ip_src));
233 strcpy(bufb, inet_ntoa(ip->ip_dst));
234 DEBUG_MISC((dfd, " %.16s to %.16s\n", bufa, bufb));
235 }
236 #endif
237 if(ip->ip_off & IP_OFFMASK) goto end_error; /* Only reply to fragment 0 */
238
239 shlen=ip->ip_hl << 2;
240 s_ip_len=ip->ip_len;
241 if(ip->ip_p == IPPROTO_ICMP) {
242 icp = (struct icmp *)((char *)ip + shlen);
243 /*
244 * Assume any unknown ICMP type is an error. This isn't
245 * specified by the RFC, but think about it..
246 */
247 if(icp->icmp_type>18 || icmp_flush[icp->icmp_type]) goto end_error;
248 }
249
250 /* make a copy */
251 if(!(m=m_get())) goto end_error; /* get mbuf */
252 { int new_m_size;
253 new_m_size=sizeof(struct ip )+ICMP_MINLEN+msrc->m_len+ICMP_MAXDATALEN;
254 if(new_m_size>m->m_size) m_inc(m, new_m_size);
255 }
256 memcpy(m->m_data, msrc->m_data, msrc->m_len);
257 m->m_len = msrc->m_len; /* copy msrc to m */
258
259 /* make the header of the reply packet */
260 ip = mtod(m, struct ip *);
261 hlen= sizeof(struct ip ); /* no options in reply */
262
263 /* fill in icmp */
264 m->m_data += hlen;
265 m->m_len -= hlen;
266
267 icp = mtod(m, struct icmp *);
268
269 if(minsize) s_ip_len=shlen+ICMP_MINLEN; /* return header+8b only */
270 else if(s_ip_len>ICMP_MAXDATALEN) /* maximum size */
271 s_ip_len=ICMP_MAXDATALEN;
272
273 m->m_len=ICMP_MINLEN+s_ip_len; /* 8 bytes ICMP header */
274
275 /* min. size = 8+sizeof(struct ip)+8 */
276
277 icp->icmp_type = type;
278 icp->icmp_code = code;
279 icp->icmp_id = 0;
280 icp->icmp_seq = 0;
281
282 memcpy(&icp->icmp_ip, msrc->m_data, s_ip_len); /* report the ip packet */
283 HTONS(icp->icmp_ip.ip_len);
284 HTONS(icp->icmp_ip.ip_id);
285 HTONS(icp->icmp_ip.ip_off);
286
287 #if DEBUG
288 if(message) { /* DEBUG : append message to ICMP packet */
289 int message_len;
290 char *cpnt;
291 message_len=strlen(message);
292 if(message_len>ICMP_MAXDATALEN) message_len=ICMP_MAXDATALEN;
293 cpnt=(char *)m->m_data+m->m_len;
294 memcpy(cpnt, message, message_len);
295 m->m_len+=message_len;
296 }
297 #endif
298
299 icp->icmp_cksum = 0;
300 icp->icmp_cksum = cksum(m, m->m_len);
301
302 m->m_data -= hlen;
303 m->m_len += hlen;
304
305 /* fill in ip */
306 ip->ip_hl = hlen >> 2;
307 ip->ip_len = m->m_len;
308
309 ip->ip_tos=((ip->ip_tos & 0x1E) | 0xC0); /* high priority for errors */
310
311 ip->ip_ttl = MAXTTL;
312 ip->ip_p = IPPROTO_ICMP;
313 ip->ip_dst = ip->ip_src; /* ip adresses */
314 ip->ip_src = our_addr;
315
316 (void ) ip_output((struct socket *)NULL, m);
317
318 icmpstat.icps_reflect++;
319
320 end_error:
321 return;
322 }
323 #undef ICMP_MAXDATALEN
324
325 /*
326 * Reflect the ip packet back to the source
327 */
328 void
icmp_reflect(m)329 icmp_reflect(m)
330 struct mbuf *m;
331 {
332 register struct ip *ip = mtod(m, struct ip *);
333 int hlen = ip->ip_hl << 2;
334 int optlen = hlen - sizeof(struct ip );
335 register struct icmp *icp;
336
337 /*
338 * Send an icmp packet back to the ip level,
339 * after supplying a checksum.
340 */
341 m->m_data += hlen;
342 m->m_len -= hlen;
343 icp = mtod(m, struct icmp *);
344
345 icp->icmp_cksum = 0;
346 icp->icmp_cksum = cksum(m, ip->ip_len - hlen);
347
348 m->m_data -= hlen;
349 m->m_len += hlen;
350
351 /* fill in ip */
352 if (optlen > 0) {
353 /*
354 * Strip out original options by copying rest of first
355 * mbuf's data back, and adjust the IP length.
356 */
357 memmove((caddr_t)(ip + 1), (caddr_t)ip + hlen,
358 (unsigned )(m->m_len - hlen));
359 hlen -= optlen;
360 ip->ip_hl = hlen >> 2;
361 ip->ip_len -= optlen;
362 m->m_len -= optlen;
363 }
364
365 ip->ip_ttl = MAXTTL;
366 { /* swap */
367 struct in_addr icmp_dst;
368 icmp_dst = ip->ip_dst;
369 ip->ip_dst = ip->ip_src;
370 ip->ip_src = icmp_dst;
371 }
372
373 (void ) ip_output((struct socket *)NULL, m);
374
375 icmpstat.icps_reflect++;
376 }
377