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 "slirp.h"
34 #include "ip_icmp.h"
35 #include "sockets.h"
36
37 #ifdef LOG_ENABLED
38 struct icmpstat icmpstat;
39 #endif
40
41 /* The message sent when emulating PING */
42 /* Be nice and tell them it's just a pseudo-ping packet */
43 static const char icmp_ping_msg[] = "This is a pseudo-PING packet used by Slirp to emulate ICMP ECHO-REQUEST packets.\n";
44
45 /* list of actions for icmp_error() on RX of an icmp message */
46 static const int icmp_flush[19] = {
47 /* ECHO REPLY (0) */ 0,
48 1,
49 1,
50 /* DEST UNREACH (3) */ 1,
51 /* SOURCE QUENCH (4)*/ 1,
52 /* REDIRECT (5) */ 1,
53 1,
54 1,
55 /* ECHO (8) */ 0,
56 /* ROUTERADVERT (9) */ 1,
57 /* ROUTERSOLICIT (10) */ 1,
58 /* TIME EXCEEDED (11) */ 1,
59 /* PARAMETER PROBLEM (12) */ 1,
60 /* TIMESTAMP (13) */ 0,
61 /* TIMESTAMP REPLY (14) */ 0,
62 /* INFO (15) */ 0,
63 /* INFO REPLY (16) */ 0,
64 /* ADDR MASK (17) */ 0,
65 /* ADDR MASK REPLY (18) */ 0
66 };
67
68 /*
69 * Process a received ICMP message.
70 */
71 void
icmp_input(struct mbuf * m,int hlen)72 icmp_input(struct mbuf *m, int hlen)
73 {
74 register struct icmp *icp;
75 register struct ip *ip=mtod(m, struct ip *);
76 int icmplen=ip->ip_len;
77 /* int code; */
78
79 DEBUG_CALL("icmp_input");
80 DEBUG_ARG("m = %lx", (long )m);
81 DEBUG_ARG("m_len = %d", m->m_len);
82
83 STAT(icmpstat.icps_received++);
84
85 /*
86 * Locate icmp structure in mbuf, and check
87 * that its not corrupted and of at least minimum length.
88 */
89 if (icmplen < ICMP_MINLEN) { /* min 8 bytes payload */
90 STAT(icmpstat.icps_tooshort++);
91 freeit:
92 m_freem(m);
93 goto end_error;
94 }
95
96 m->m_len -= hlen;
97 m->m_data += hlen;
98 icp = mtod(m, struct icmp *);
99 if (cksum(m, icmplen)) {
100 STAT(icmpstat.icps_checksum++);
101 goto freeit;
102 }
103 m->m_len += hlen;
104 m->m_data -= hlen;
105
106 /* icmpstat.icps_inhist[icp->icmp_type]++; */
107 /* code = icp->icmp_code; */
108
109 DEBUG_ARG("icmp_type = %d", icp->icmp_type);
110 switch (icp->icmp_type) {
111 case ICMP_ECHO:
112 icp->icmp_type = ICMP_ECHOREPLY;
113 ip->ip_len += hlen; /* since ip_input subtracts this */
114 if (ip_geth(ip->ip_dst) == alias_addr_ip) {
115 icmp_reflect(m);
116 } else {
117 struct socket *so;
118 SockAddress addr;
119 uint32_t addr_ip;
120 uint16_t addr_port;
121
122 if ((so = socreate()) == NULL) goto freeit;
123 if(udp_attach(so) == -1) {
124 DEBUG_MISC((dfd,"icmp_input udp_attach errno = %d-%s\n",
125 errno,errno_str));
126 sofree(so);
127 m_free(m);
128 goto end_error;
129 }
130 so->so_m = m;
131 so->so_faddr_ip = ip_geth(ip->ip_dst);
132 so->so_faddr_port = 7;
133 so->so_laddr_ip = ip_geth(ip->ip_src);
134 so->so_laddr_port = 9;
135 so->so_iptos = ip->ip_tos;
136 so->so_type = IPPROTO_ICMP;
137 so->so_state = SS_ISFCONNECTED;
138
139 /* Send the packet */
140 if ((so->so_faddr_ip & 0xffffff00) == special_addr_ip) {
141 /* It's an alias */
142 int low = so->so_faddr_ip & 0xff;
143
144 if (low >= CTL_DNS && low < CTL_DNS + dns_addr_count)
145 addr_ip = dns_addr[low - CTL_DNS];
146 else
147 addr_ip = loopback_addr_ip;
148 } else {
149 addr_ip = so->so_faddr_ip;
150 }
151 addr_port = so->so_faddr_port;
152
153 sock_address_init_inet( &addr, addr_ip, addr_port );
154
155 if(socket_sendto(so->s, icmp_ping_msg, strlen(icmp_ping_msg), &addr) < 0) {
156 DEBUG_MISC((dfd,"icmp_input udp sendto tx errno = %d-%s\n",
157 errno,errno_str));
158 icmp_error(m, ICMP_UNREACH,ICMP_UNREACH_NET, 0,errno_str);
159 udp_detach(so);
160 }
161 } /* if ip->ip_dst.s_addr == alias_addr.s_addr */
162 break;
163 case ICMP_UNREACH:
164 /* XXX? report error? close socket? */
165 case ICMP_TIMXCEED:
166 case ICMP_PARAMPROB:
167 case ICMP_SOURCEQUENCH:
168 case ICMP_TSTAMP:
169 case ICMP_MASKREQ:
170 case ICMP_REDIRECT:
171 STAT(icmpstat.icps_notsupp++);
172 m_freem(m);
173 break;
174
175 default:
176 STAT(icmpstat.icps_badtype++);
177 m_freem(m);
178 } /* swith */
179
180 end_error:
181 /* m is m_free()'d xor put in a socket xor or given to ip_send */
182 return;
183 }
184
185
186 /*
187 * Send an ICMP message in response to a situation
188 *
189 * RFC 1122: 3.2.2 MUST send at least the IP header and 8 bytes of header. MAY send more (we do).
190 * MUST NOT change this header information.
191 * MUST NOT reply to a multicast/broadcast IP address.
192 * MUST NOT reply to a multicast/broadcast MAC address.
193 * MUST reply to only the first fragment.
194 */
195 /*
196 * Send ICMP_UNREACH back to the source regarding msrc.
197 * mbuf *msrc is used as a template, but is NOT m_free()'d.
198 * It is reported as the bad ip packet. The header should
199 * be fully correct and in host byte order.
200 * ICMP fragmentation is illegal. All machines must accept 576 bytes in one
201 * packet. The maximum payload is 576-20(ip hdr)-8(icmp hdr)=548
202 */
203
204 #define ICMP_MAXDATALEN (IP_MSS-28)
205 void
icmp_error(struct mbuf * msrc,u_char type,u_char code,int minsize,const char * message)206 icmp_error(struct mbuf *msrc, u_char type, u_char code, int minsize,
207 const char *message)
208 {
209 unsigned hlen, shlen, s_ip_len;
210 register struct ip *ip;
211 register struct icmp *icp;
212 register struct mbuf *m;
213
214 DEBUG_CALL("icmp_error");
215 DEBUG_ARG("msrc = %lx", (long )msrc);
216 DEBUG_ARG("msrc_len = %d", msrc->m_len);
217
218 if(type!=ICMP_UNREACH && type!=ICMP_TIMXCEED) goto end_error;
219
220 /* check msrc */
221 if(!msrc) goto end_error;
222 ip = mtod(msrc, struct ip *);
223 #ifdef DEBUG
224 { char bufa[20], bufb[20];
225 strcpy(bufa, inet_iptostr(ip_geth(ip->ip_src)));
226 strcpy(bufb, inet_iptostr(ip_geth(ip->ip_dst)));
227 DEBUG_MISC((dfd, " %.16s to %.16s\n", bufa, bufb));
228 }
229 #endif
230 if(ip->ip_off & IP_OFFMASK) goto end_error; /* Only reply to fragment 0 */
231
232 shlen=ip->ip_hl << 2;
233 s_ip_len=ip->ip_len;
234 if(ip->ip_p == IPPROTO_ICMP) {
235 icp = (struct icmp *)((char *)ip + shlen);
236 /*
237 * Assume any unknown ICMP type is an error. This isn't
238 * specified by the RFC, but think about it..
239 */
240 if(icp->icmp_type>18 || icmp_flush[icp->icmp_type]) goto end_error;
241 }
242
243 /* make a copy */
244 if(!(m=m_get())) goto end_error; /* get mbuf */
245 { int new_m_size;
246 new_m_size=sizeof(struct ip )+ICMP_MINLEN+msrc->m_len+ICMP_MAXDATALEN;
247 if(new_m_size>m->m_size) m_inc(m, new_m_size);
248 }
249 memcpy(m->m_data, msrc->m_data, msrc->m_len);
250 m->m_len = msrc->m_len; /* copy msrc to m */
251
252 /* make the header of the reply packet */
253 ip = mtod(m, struct ip *);
254 hlen= sizeof(struct ip ); /* no options in reply */
255
256 /* fill in icmp */
257 m->m_data += hlen;
258 m->m_len -= hlen;
259
260 icp = mtod(m, struct icmp *);
261
262 if(minsize) s_ip_len=shlen+ICMP_MINLEN; /* return header+8b only */
263 else if(s_ip_len>ICMP_MAXDATALEN) /* maximum size */
264 s_ip_len=ICMP_MAXDATALEN;
265
266 m->m_len=ICMP_MINLEN+s_ip_len; /* 8 bytes ICMP header */
267
268 /* min. size = 8+sizeof(struct ip)+8 */
269
270 icp->icmp_type = type;
271 icp->icmp_code = code;
272 icp->icmp_id = 0;
273 icp->icmp_seq = 0;
274
275 memcpy(&icp->icmp_ip, msrc->m_data, s_ip_len); /* report the ip packet */
276 HTONS(icp->icmp_ip.ip_len);
277 HTONS(icp->icmp_ip.ip_id);
278 HTONS(icp->icmp_ip.ip_off);
279
280 #ifdef DEBUG
281 if(message) { /* DEBUG : append message to ICMP packet */
282 int message_len;
283 char *cpnt;
284 message_len=strlen(message);
285 if(message_len>ICMP_MAXDATALEN) message_len=ICMP_MAXDATALEN;
286 cpnt=(char *)m->m_data+m->m_len;
287 memcpy(cpnt, message, message_len);
288 m->m_len+=message_len;
289 }
290 #endif
291
292 icp->icmp_cksum = 0;
293 icp->icmp_cksum = cksum(m, m->m_len);
294
295 m->m_data -= hlen;
296 m->m_len += hlen;
297
298 /* fill in ip */
299 ip->ip_hl = hlen >> 2;
300 ip->ip_len = m->m_len;
301
302 ip->ip_tos=((ip->ip_tos & 0x1E) | 0xC0); /* high priority for errors */
303
304 ip->ip_ttl = MAXTTL;
305 ip->ip_p = IPPROTO_ICMP;
306 ip->ip_dst = ip->ip_src; /* ip adresses */
307 ip->ip_src = ip_setn(alias_addr_ip);
308
309 (void ) ip_output((struct socket *)NULL, m);
310
311 STAT(icmpstat.icps_reflect++);
312
313 end_error:
314 return;
315 }
316 #undef ICMP_MAXDATALEN
317
318 /*
319 * Reflect the ip packet back to the source
320 */
321 void
icmp_reflect(struct mbuf * m)322 icmp_reflect(struct mbuf *m)
323 {
324 register struct ip *ip = mtod(m, struct ip *);
325 int hlen = ip->ip_hl << 2;
326 int optlen = hlen - sizeof(struct ip );
327 register struct icmp *icp;
328
329 /*
330 * Send an icmp packet back to the ip level,
331 * after supplying a checksum.
332 */
333 m->m_data += hlen;
334 m->m_len -= hlen;
335 icp = mtod(m, struct icmp *);
336
337 icp->icmp_cksum = 0;
338 icp->icmp_cksum = cksum(m, ip->ip_len - hlen);
339
340 m->m_data -= hlen;
341 m->m_len += hlen;
342
343 /* fill in ip */
344 if (optlen > 0) {
345 /*
346 * Strip out original options by copying rest of first
347 * mbuf's data back, and adjust the IP length.
348 */
349 memmove((caddr_t)(ip + 1), (caddr_t)ip + hlen,
350 (unsigned )(m->m_len - hlen));
351 hlen -= optlen;
352 ip->ip_hl = hlen >> 2;
353 ip->ip_len -= optlen;
354 m->m_len -= optlen;
355 }
356
357 ip->ip_ttl = MAXTTL;
358 { /* swap */
359 ipaddr_t icmp_dst;
360 icmp_dst = ip->ip_dst;
361 ip->ip_dst = ip->ip_src;
362 ip->ip_src = icmp_dst;
363 }
364
365 (void ) ip_output((struct socket *)NULL, m);
366
367 STAT(icmpstat.icps_reflect++);
368 }
369