summaryrefslogtreecommitdiff
path: root/slirp/ip_icmp.c
blob: ae5a3211852ff64e9c9c51e98e3b10a72e68db58 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
/*
 * Copyright (c) 1982, 1986, 1988, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *	@(#)ip_icmp.c	8.2 (Berkeley) 1/4/94
 * ip_icmp.c,v 1.7 1995/05/30 08:09:42 rgrimes Exp
 */

#include "slirp.h"
#include "ip_icmp.h"

struct icmpstat icmpstat;

/* The message sent when emulating PING */
/* Be nice and tell them it's just a psuedo-ping packet */
char icmp_ping_msg[] = "This is a psuedo-PING packet used by Slirp to emulate ICMP ECHO-REQUEST packets.\n";

/* list of actions for icmp_error() on RX of an icmp message */
static int icmp_flush[19] = {
/*  ECHO REPLY (0)  */   0,
		         1,
		         1,
/* DEST UNREACH (3) */   1,
/* SOURCE QUENCH (4)*/   1,
/* REDIRECT (5) */       1,
		         1,
		         1,
/* ECHO (8) */           0,
/* ROUTERADVERT (9) */   1,
/* ROUTERSOLICIT (10) */ 1,
/* TIME EXCEEDED (11) */ 1,
/* PARAMETER PROBLEM (12) */ 1,
/* TIMESTAMP (13) */     0,
/* TIMESTAMP REPLY (14) */ 0,
/* INFO (15) */          0,
/* INFO REPLY (16) */    0,
/* ADDR MASK (17) */     0,
/* ADDR MASK REPLY (18) */ 0
};

/*
 * Process a received ICMP message.
 */
void
icmp_input(m, hlen)
     struct mbuf *m;
     int hlen;
{
  register struct icmp *icp;
  register struct ip *ip=mtod(m, struct ip *);
  int icmplen=ip->ip_len;
  /* int code; */

  DEBUG_CALL("icmp_input");
  DEBUG_ARG("m = %lx", (long )m);
  DEBUG_ARG("m_len = %d", m->m_len);

  icmpstat.icps_received++;

  /*
   * Locate icmp structure in mbuf, and check
   * that its not corrupted and of at least minimum length.
   */
  if (icmplen < ICMP_MINLEN) {          /* min 8 bytes payload */
    icmpstat.icps_tooshort++;
  freeit:
    m_freem(m);
    goto end_error;
  }

  m->m_len -= hlen;
  m->m_data += hlen;
  icp = mtod(m, struct icmp *);
  if (cksum(m, icmplen)) {
    icmpstat.icps_checksum++;
    goto freeit;
  }
  m->m_len += hlen;
  m->m_data -= hlen;

  /*	icmpstat.icps_inhist[icp->icmp_type]++; */
  /* code = icp->icmp_code; */

  DEBUG_ARG("icmp_type = %d", icp->icmp_type);
  switch (icp->icmp_type) {
  case ICMP_ECHO:
    icp->icmp_type = ICMP_ECHOREPLY;
    ip->ip_len += hlen;	             /* since ip_input subtracts this */
    if (ip->ip_dst.s_addr == alias_addr.s_addr) {
      icmp_reflect(m);
    } else {
      struct socket *so;
      struct sockaddr_in addr;
      if ((so = socreate()) == NULL) goto freeit;
      if(udp_attach(so) == -1) {
	DEBUG_MISC((dfd,"icmp_input udp_attach errno = %d-%s\n",
		    errno,strerror(errno)));
	sofree(so);
	m_free(m);
	goto end_error;
      }
      so->so_m = m;
      so->so_faddr = ip->ip_dst;
      so->so_fport = htons(7);
      so->so_laddr = ip->ip_src;
      so->so_lport = htons(9);
      so->so_iptos = ip->ip_tos;
      so->so_type = IPPROTO_ICMP;
      so->so_state = SS_ISFCONNECTED;

      /* Send the packet */
      addr.sin_family = AF_INET;
      if ((so->so_faddr.s_addr & htonl(0xffffff00)) == special_addr.s_addr) {
	/* It's an alias */
	switch(ntohl(so->so_faddr.s_addr) & 0xff) {
	case CTL_DNS:
	  addr.sin_addr = dns_addr;
	  break;
	case CTL_ALIAS:
	default:
	  addr.sin_addr = loopback_addr;
	  break;
	}
      } else {
	addr.sin_addr = so->so_faddr;
      }
      addr.sin_port = so->so_fport;
      if(sendto(so->s, icmp_ping_msg, strlen(icmp_ping_msg), 0,
		(struct sockaddr *)&addr, sizeof(addr)) == -1) {
	DEBUG_MISC((dfd,"icmp_input udp sendto tx errno = %d-%s\n",
		    errno,strerror(errno)));
	icmp_error(m, ICMP_UNREACH,ICMP_UNREACH_NET, 0,strerror(errno));
	udp_detach(so);
      }
    } /* if ip->ip_dst.s_addr == alias_addr.s_addr */
    break;
  case ICMP_UNREACH:
    /* XXX? report error? close socket? */
  case ICMP_TIMXCEED:
  case ICMP_PARAMPROB:
  case ICMP_SOURCEQUENCH:
  case ICMP_TSTAMP:
  case ICMP_MASKREQ:
  case ICMP_REDIRECT:
    icmpstat.icps_notsupp++;
    m_freem(m);
    break;

  default:
    icmpstat.icps_badtype++;
    m_freem(m);
  } /* swith */

end_error:
  /* m is m_free()'d xor put in a socket xor or given to ip_send */
  return;
}


/*
 *	Send an ICMP message in response to a situation
 *
 *	RFC 1122: 3.2.2	MUST send at least the IP header and 8 bytes of header. MAY send more (we do).
 *			MUST NOT change this header information.
 *			MUST NOT reply to a multicast/broadcast IP address.
 *			MUST NOT reply to a multicast/broadcast MAC address.
 *			MUST reply to only the first fragment.
 */
/*
 * Send ICMP_UNREACH back to the source regarding msrc.
 * mbuf *msrc is used as a template, but is NOT m_free()'d.
 * It is reported as the bad ip packet.  The header should
 * be fully correct and in host byte order.
 * ICMP fragmentation is illegal.  All machines must accept 576 bytes in one
 * packet.  The maximum payload is 576-20(ip hdr)-8(icmp hdr)=548
 */

#define ICMP_MAXDATALEN (IP_MSS-28)
void
icmp_error(msrc, type, code, minsize, message)
     struct mbuf *msrc;
     u_char type;
     u_char code;
     int minsize;
     char *message;
{
  unsigned hlen, shlen, s_ip_len;
  register struct ip *ip;
  register struct icmp *icp;
  register struct mbuf *m;

  DEBUG_CALL("icmp_error");
  DEBUG_ARG("msrc = %lx", (long )msrc);
  DEBUG_ARG("msrc_len = %d", msrc->m_len);

  if(type!=ICMP_UNREACH && type!=ICMP_TIMXCEED) goto end_error;

  /* check msrc */
  if(!msrc) goto end_error;
  ip = mtod(msrc, struct ip *);
#if DEBUG
  { char bufa[20], bufb[20];
    strcpy(bufa, inet_ntoa(ip->ip_src));
    strcpy(bufb, inet_ntoa(ip->ip_dst));
    DEBUG_MISC((dfd, " %.16s to %.16s\n", bufa, bufb));
  }
#endif
  if(ip->ip_off & IP_OFFMASK) goto end_error;    /* Only reply to fragment 0 */

  shlen=ip->ip_hl << 2;
  s_ip_len=ip->ip_len;
  if(ip->ip_p == IPPROTO_ICMP) {
    icp = (struct icmp *)((char *)ip + shlen);
    /*
     *	Assume any unknown ICMP type is an error. This isn't
     *	specified by the RFC, but think about it..
     */
    if(icp->icmp_type>18 || icmp_flush[icp->icmp_type]) goto end_error;
  }

  /* make a copy */
  if(!(m=m_get())) goto end_error;               /* get mbuf */
  { int new_m_size;
    new_m_size=sizeof(struct ip )+ICMP_MINLEN+msrc->m_len+ICMP_MAXDATALEN;
    if(new_m_size>m->m_size) m_inc(m, new_m_size);
  }
  memcpy(m->m_data, msrc->m_data, msrc->m_len);
  m->m_len = msrc->m_len;                        /* copy msrc to m */

  /* make the header of the reply packet */
  ip  = mtod(m, struct ip *);
  hlen= sizeof(struct ip );     /* no options in reply */

  /* fill in icmp */
  m->m_data += hlen;
  m->m_len -= hlen;

  icp = mtod(m, struct icmp *);

  if(minsize) s_ip_len=shlen+ICMP_MINLEN;   /* return header+8b only */
  else if(s_ip_len>ICMP_MAXDATALEN)         /* maximum size */
    s_ip_len=ICMP_MAXDATALEN;

  m->m_len=ICMP_MINLEN+s_ip_len;        /* 8 bytes ICMP header */

  /* min. size = 8+sizeof(struct ip)+8 */

  icp->icmp_type = type;
  icp->icmp_code = code;
  icp->icmp_id = 0;
  icp->icmp_seq = 0;

  memcpy(&icp->icmp_ip, msrc->m_data, s_ip_len);   /* report the ip packet */
  HTONS(icp->icmp_ip.ip_len);
  HTONS(icp->icmp_ip.ip_id);
  HTONS(icp->icmp_ip.ip_off);

#if DEBUG
  if(message) {           /* DEBUG : append message to ICMP packet */
    int message_len;
    char *cpnt;
    message_len=strlen(message);
    if(message_len>ICMP_MAXDATALEN) message_len=ICMP_MAXDATALEN;
    cpnt=(char *)m->m_data+m->m_len;
    memcpy(cpnt, message, message_len);
    m->m_len+=message_len;
  }
#endif

  icp->icmp_cksum = 0;
  icp->icmp_cksum = cksum(m, m->m_len);

  m->m_data -= hlen;
  m->m_len += hlen;

  /* fill in ip */
  ip->ip_hl = hlen >> 2;
  ip->ip_len = m->m_len;

  ip->ip_tos=((ip->ip_tos & 0x1E) | 0xC0);  /* high priority for errors */

  ip->ip_ttl = MAXTTL;
  ip->ip_p = IPPROTO_ICMP;
  ip->ip_dst = ip->ip_src;    /* ip adresses */
  ip->ip_src = alias_addr;

  (void ) ip_output((struct socket *)NULL, m);

  icmpstat.icps_reflect++;

end_error:
  return;
}
#undef ICMP_MAXDATALEN

/*
 * Reflect the ip packet back to the source
 */
void
icmp_reflect(m)
     struct mbuf *m;
{
  register struct ip *ip = mtod(m, struct ip *);
  int hlen = ip->ip_hl << 2;
  int optlen = hlen - sizeof(struct ip );
  register struct icmp *icp;

  /*
   * Send an icmp packet back to the ip level,
   * after supplying a checksum.
   */
  m->m_data += hlen;
  m->m_len -= hlen;
  icp = mtod(m, struct icmp *);

  icp->icmp_cksum = 0;
  icp->icmp_cksum = cksum(m, ip->ip_len - hlen);

  m->m_data -= hlen;
  m->m_len += hlen;

  /* fill in ip */
  if (optlen > 0) {
    /*
     * Strip out original options by copying rest of first
     * mbuf's data back, and adjust the IP length.
     */
    memmove((caddr_t)(ip + 1), (caddr_t)ip + hlen,
	    (unsigned )(m->m_len - hlen));
    hlen -= optlen;
    ip->ip_hl = hlen >> 2;
    ip->ip_len -= optlen;
    m->m_len -= optlen;
  }

  ip->ip_ttl = MAXTTL;
  { /* swap */
    struct in_addr icmp_dst;
    icmp_dst = ip->ip_dst;
    ip->ip_dst = ip->ip_src;
    ip->ip_src = icmp_dst;
  }

  (void ) ip_output((struct socket *)NULL, m);

  icmpstat.icps_reflect++;
}