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1.1 root 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:
1.1.1.3 ! root 40: #ifdef LOG_ENABLED
1.1 root 41: struct icmpstat icmpstat;
1.1.1.3 ! root 42: #endif
1.1 root 43:
44: /* The message sent when emulating PING */
1.1.1.3 ! root 45: /* Be nice and tell them it's just a pseudo-ping packet */
! 46: const char icmp_ping_msg[] = "This is a pseudo-PING packet used by Slirp to emulate ICMP ECHO-REQUEST packets.\n";
1.1 root 47:
48: /* list of actions for icmp_error() on RX of an icmp message */
1.1.1.3 ! root 49: static const int icmp_flush[19] = {
1.1 root 50: /* ECHO REPLY (0) */ 0,
51: 1,
52: 1,
53: /* DEST UNREACH (3) */ 1,
54: /* SOURCE QUENCH (4)*/ 1,
55: /* REDIRECT (5) */ 1,
56: 1,
57: 1,
58: /* ECHO (8) */ 0,
59: /* ROUTERADVERT (9) */ 1,
60: /* ROUTERSOLICIT (10) */ 1,
61: /* TIME EXCEEDED (11) */ 1,
62: /* PARAMETER PROBLEM (12) */ 1,
63: /* TIMESTAMP (13) */ 0,
64: /* TIMESTAMP REPLY (14) */ 0,
65: /* INFO (15) */ 0,
66: /* INFO REPLY (16) */ 0,
67: /* ADDR MASK (17) */ 0,
1.1.1.3 ! root 68: /* ADDR MASK REPLY (18) */ 0
1.1 root 69: };
70:
71: /*
72: * Process a received ICMP message.
73: */
74: void
75: icmp_input(m, hlen)
76: struct mbuf *m;
77: int hlen;
78: {
79: register struct icmp *icp;
80: register struct ip *ip=mtod(m, struct ip *);
81: int icmplen=ip->ip_len;
82: /* int code; */
1.1.1.3 ! root 83:
1.1 root 84: DEBUG_CALL("icmp_input");
85: DEBUG_ARG("m = %lx", (long )m);
86: DEBUG_ARG("m_len = %d", m->m_len);
87:
1.1.1.3 ! root 88: STAT(icmpstat.icps_received++);
! 89:
1.1 root 90: /*
91: * Locate icmp structure in mbuf, and check
92: * that its not corrupted and of at least minimum length.
93: */
94: if (icmplen < ICMP_MINLEN) { /* min 8 bytes payload */
1.1.1.3 ! root 95: STAT(icmpstat.icps_tooshort++);
1.1 root 96: freeit:
97: m_freem(m);
98: goto end_error;
99: }
100:
101: m->m_len -= hlen;
102: m->m_data += hlen;
103: icp = mtod(m, struct icmp *);
104: if (cksum(m, icmplen)) {
1.1.1.3 ! root 105: STAT(icmpstat.icps_checksum++);
1.1 root 106: goto freeit;
107: }
108: m->m_len += hlen;
109: m->m_data -= hlen;
1.1.1.3 ! root 110:
1.1 root 111: /* icmpstat.icps_inhist[icp->icmp_type]++; */
112: /* code = icp->icmp_code; */
113:
114: DEBUG_ARG("icmp_type = %d", icp->icmp_type);
115: switch (icp->icmp_type) {
116: case ICMP_ECHO:
117: icp->icmp_type = ICMP_ECHOREPLY;
118: ip->ip_len += hlen; /* since ip_input subtracts this */
1.1.1.2 root 119: if (ip->ip_dst.s_addr == alias_addr.s_addr) {
1.1 root 120: icmp_reflect(m);
121: } else {
122: struct socket *so;
123: struct sockaddr_in addr;
124: if ((so = socreate()) == NULL) goto freeit;
125: if(udp_attach(so) == -1) {
1.1.1.3 ! root 126: DEBUG_MISC((dfd,"icmp_input udp_attach errno = %d-%s\n",
1.1 root 127: errno,strerror(errno)));
128: sofree(so);
129: m_free(m);
130: goto end_error;
131: }
132: so->so_m = m;
133: so->so_faddr = ip->ip_dst;
134: so->so_fport = htons(7);
135: so->so_laddr = ip->ip_src;
136: so->so_lport = htons(9);
137: so->so_iptos = ip->ip_tos;
138: so->so_type = IPPROTO_ICMP;
139: so->so_state = SS_ISFCONNECTED;
1.1.1.3 ! root 140:
1.1 root 141: /* Send the packet */
142: addr.sin_family = AF_INET;
143: if ((so->so_faddr.s_addr & htonl(0xffffff00)) == special_addr.s_addr) {
144: /* It's an alias */
145: switch(ntohl(so->so_faddr.s_addr) & 0xff) {
146: case CTL_DNS:
147: addr.sin_addr = dns_addr;
148: break;
149: case CTL_ALIAS:
150: default:
151: addr.sin_addr = loopback_addr;
152: break;
153: }
154: } else {
155: addr.sin_addr = so->so_faddr;
156: }
157: addr.sin_port = so->so_fport;
158: if(sendto(so->s, icmp_ping_msg, strlen(icmp_ping_msg), 0,
159: (struct sockaddr *)&addr, sizeof(addr)) == -1) {
160: DEBUG_MISC((dfd,"icmp_input udp sendto tx errno = %d-%s\n",
161: errno,strerror(errno)));
1.1.1.3 ! root 162: icmp_error(m, ICMP_UNREACH,ICMP_UNREACH_NET, 0,strerror(errno));
1.1 root 163: udp_detach(so);
164: }
1.1.1.2 root 165: } /* if ip->ip_dst.s_addr == alias_addr.s_addr */
1.1 root 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:
1.1.1.3 ! root 175: STAT(icmpstat.icps_notsupp++);
1.1 root 176: m_freem(m);
177: break;
1.1.1.3 ! root 178:
1.1 root 179: default:
1.1.1.3 ! root 180: STAT(icmpstat.icps_badtype++);
1.1 root 181: m_freem(m);
182: } /* swith */
183:
184: end_error:
185: /* m is m_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 m_free()'d.
202: * It is reported as the bad ip packet. The header should
203: * be fully correct and in host byte order.
1.1.1.3 ! root 204: * ICMP fragmentation is illegal. All machines must accept 576 bytes in one
1.1 root 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
210: icmp_error(msrc, type, code, minsize, message)
211: struct mbuf *msrc;
212: u_char type;
213: u_char code;
214: int minsize;
215: char *message;
216: {
217: unsigned hlen, shlen, s_ip_len;
218: register struct ip *ip;
219: register struct icmp *icp;
220: register struct 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 = mtod(msrc, struct ip *);
1.1.1.3 ! root 231: #if DEBUG
1.1 root 232: { char bufa[20], bufb[20];
233: strcpy(bufa, inet_ntoa(ip->ip_src));
234: strcpy(bufb, inet_ntoa(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=m_get())) 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) m_inc(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 = mtod(m, struct ip *);
262: hlen= sizeof(struct ip ); /* no options in reply */
1.1.1.3 ! root 263:
1.1 root 264: /* fill in icmp */
1.1.1.3 ! root 265: m->m_data += hlen;
1.1 root 266: m->m_len -= hlen;
267:
268: icp = mtod(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:
1.1.1.3 ! root 274: m->m_len=ICMP_MINLEN+s_ip_len; /* 8 bytes ICMP header */
1.1 root 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;
1.1.1.3 ! root 309:
1.1 root 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 */
1.1.1.2 root 315: ip->ip_src = alias_addr;
1.1 root 316:
317: (void ) ip_output((struct socket *)NULL, m);
1.1.1.3 ! root 318:
! 319: STAT(icmpstat.icps_reflect++);
1.1 root 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
330: icmp_reflect(m)
331: struct mbuf *m;
332: {
333: register struct ip *ip = mtod(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 = mtod(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: struct in_addr 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:
1.1.1.3 ! root 376: STAT(icmpstat.icps_reflect++);
1.1 root 377: }
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