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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.
1.1.1.4 ! root 13: * 3. Neither the name of the University nor the names of its contributors
1.1 root 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:
1.1.1.3 root 36: #ifdef LOG_ENABLED
1.1 root 37: struct icmpstat icmpstat;
1.1.1.3 root 38: #endif
1.1 root 39:
40: /* The message sent when emulating PING */
1.1.1.3 root 41: /* Be nice and tell them it's just a pseudo-ping packet */
1.1.1.4 ! root 42: static const char icmp_ping_msg[] = "This is a pseudo-PING packet used by Slirp to emulate ICMP ECHO-REQUEST packets.\n";
1.1 root 43:
44: /* list of actions for icmp_error() on RX of an icmp message */
1.1.1.3 root 45: static const int icmp_flush[19] = {
1.1 root 46: /* ECHO REPLY (0) */ 0,
47: 1,
48: 1,
49: /* DEST UNREACH (3) */ 1,
50: /* SOURCE QUENCH (4)*/ 1,
51: /* REDIRECT (5) */ 1,
52: 1,
53: 1,
54: /* ECHO (8) */ 0,
55: /* ROUTERADVERT (9) */ 1,
56: /* ROUTERSOLICIT (10) */ 1,
57: /* TIME EXCEEDED (11) */ 1,
58: /* PARAMETER PROBLEM (12) */ 1,
59: /* TIMESTAMP (13) */ 0,
60: /* TIMESTAMP REPLY (14) */ 0,
61: /* INFO (15) */ 0,
62: /* INFO REPLY (16) */ 0,
63: /* ADDR MASK (17) */ 0,
1.1.1.3 root 64: /* ADDR MASK REPLY (18) */ 0
1.1 root 65: };
66:
67: /*
68: * Process a received ICMP message.
69: */
70: void
71: icmp_input(m, hlen)
72: struct mbuf *m;
73: int hlen;
74: {
75: register struct icmp *icp;
76: register struct ip *ip=mtod(m, struct ip *);
77: int icmplen=ip->ip_len;
78: /* int code; */
1.1.1.3 root 79:
1.1 root 80: DEBUG_CALL("icmp_input");
81: DEBUG_ARG("m = %lx", (long )m);
82: DEBUG_ARG("m_len = %d", m->m_len);
83:
1.1.1.3 root 84: STAT(icmpstat.icps_received++);
85:
1.1 root 86: /*
87: * Locate icmp structure in mbuf, and check
88: * that its not corrupted and of at least minimum length.
89: */
90: if (icmplen < ICMP_MINLEN) { /* min 8 bytes payload */
1.1.1.3 root 91: STAT(icmpstat.icps_tooshort++);
1.1 root 92: freeit:
93: m_freem(m);
94: goto end_error;
95: }
96:
97: m->m_len -= hlen;
98: m->m_data += hlen;
99: icp = mtod(m, struct icmp *);
100: if (cksum(m, icmplen)) {
1.1.1.3 root 101: STAT(icmpstat.icps_checksum++);
1.1 root 102: goto freeit;
103: }
104: m->m_len += hlen;
105: m->m_data -= hlen;
1.1.1.3 root 106:
1.1 root 107: /* icmpstat.icps_inhist[icp->icmp_type]++; */
108: /* code = icp->icmp_code; */
109:
110: DEBUG_ARG("icmp_type = %d", icp->icmp_type);
111: switch (icp->icmp_type) {
112: case ICMP_ECHO:
113: icp->icmp_type = ICMP_ECHOREPLY;
114: ip->ip_len += hlen; /* since ip_input subtracts this */
1.1.1.2 root 115: if (ip->ip_dst.s_addr == alias_addr.s_addr) {
1.1 root 116: icmp_reflect(m);
117: } else {
118: struct socket *so;
119: struct sockaddr_in addr;
120: if ((so = socreate()) == NULL) goto freeit;
121: if(udp_attach(so) == -1) {
1.1.1.3 root 122: DEBUG_MISC((dfd,"icmp_input udp_attach errno = %d-%s\n",
1.1 root 123: errno,strerror(errno)));
124: sofree(so);
125: m_free(m);
126: goto end_error;
127: }
128: so->so_m = m;
129: so->so_faddr = ip->ip_dst;
130: so->so_fport = htons(7);
131: so->so_laddr = ip->ip_src;
132: so->so_lport = htons(9);
133: so->so_iptos = ip->ip_tos;
134: so->so_type = IPPROTO_ICMP;
135: so->so_state = SS_ISFCONNECTED;
1.1.1.3 root 136:
1.1 root 137: /* Send the packet */
138: addr.sin_family = AF_INET;
139: if ((so->so_faddr.s_addr & htonl(0xffffff00)) == special_addr.s_addr) {
140: /* It's an alias */
141: switch(ntohl(so->so_faddr.s_addr) & 0xff) {
142: case CTL_DNS:
143: addr.sin_addr = dns_addr;
144: break;
145: case CTL_ALIAS:
146: default:
147: addr.sin_addr = loopback_addr;
148: break;
149: }
150: } else {
151: addr.sin_addr = so->so_faddr;
152: }
153: addr.sin_port = so->so_fport;
154: if(sendto(so->s, icmp_ping_msg, strlen(icmp_ping_msg), 0,
155: (struct sockaddr *)&addr, sizeof(addr)) == -1) {
156: DEBUG_MISC((dfd,"icmp_input udp sendto tx errno = %d-%s\n",
157: errno,strerror(errno)));
1.1.1.3 root 158: icmp_error(m, ICMP_UNREACH,ICMP_UNREACH_NET, 0,strerror(errno));
1.1 root 159: udp_detach(so);
160: }
1.1.1.2 root 161: } /* if ip->ip_dst.s_addr == alias_addr.s_addr */
1.1 root 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:
1.1.1.3 root 171: STAT(icmpstat.icps_notsupp++);
1.1 root 172: m_freem(m);
173: break;
1.1.1.3 root 174:
1.1 root 175: default:
1.1.1.3 root 176: STAT(icmpstat.icps_badtype++);
1.1 root 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.
1.1.1.3 root 200: * ICMP fragmentation is illegal. All machines must accept 576 bytes in one
1.1 root 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
1.1.1.4 ! root 206: icmp_error(struct mbuf *msrc, u_char type, u_char code, int minsize,
! 207: const char *message)
1.1 root 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 *);
1.1.1.4 ! root 223: #ifdef DEBUG
1.1 root 224: { char bufa[20], bufb[20];
225: strcpy(bufa, inet_ntoa(ip->ip_src));
226: strcpy(bufb, inet_ntoa(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 */
1.1.1.3 root 255:
1.1 root 256: /* fill in icmp */
1.1.1.3 root 257: m->m_data += hlen;
1.1 root 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:
1.1.1.3 root 266: m->m_len=ICMP_MINLEN+s_ip_len; /* 8 bytes ICMP header */
1.1 root 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:
1.1.1.4 ! root 280: #ifdef DEBUG
1.1 root 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;
1.1.1.3 root 301:
1.1 root 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 */
1.1.1.2 root 307: ip->ip_src = alias_addr;
1.1 root 308:
309: (void ) ip_output((struct socket *)NULL, m);
1.1.1.3 root 310:
311: STAT(icmpstat.icps_reflect++);
1.1 root 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
322: icmp_reflect(m)
323: struct mbuf *m;
324: {
325: register struct ip *ip = mtod(m, struct ip *);
326: int hlen = ip->ip_hl << 2;
327: int optlen = hlen - sizeof(struct ip );
328: register struct icmp *icp;
329:
330: /*
331: * Send an icmp packet back to the ip level,
332: * after supplying a checksum.
333: */
334: m->m_data += hlen;
335: m->m_len -= hlen;
336: icp = mtod(m, struct icmp *);
337:
338: icp->icmp_cksum = 0;
339: icp->icmp_cksum = cksum(m, ip->ip_len - hlen);
340:
341: m->m_data -= hlen;
342: m->m_len += hlen;
343:
344: /* fill in ip */
345: if (optlen > 0) {
346: /*
347: * Strip out original options by copying rest of first
348: * mbuf's data back, and adjust the IP length.
349: */
350: memmove((caddr_t)(ip + 1), (caddr_t)ip + hlen,
351: (unsigned )(m->m_len - hlen));
352: hlen -= optlen;
353: ip->ip_hl = hlen >> 2;
354: ip->ip_len -= optlen;
355: m->m_len -= optlen;
356: }
357:
358: ip->ip_ttl = MAXTTL;
359: { /* swap */
360: struct in_addr icmp_dst;
361: icmp_dst = ip->ip_dst;
362: ip->ip_dst = ip->ip_src;
363: ip->ip_src = icmp_dst;
364: }
365:
366: (void ) ip_output((struct socket *)NULL, m);
367:
1.1.1.3 root 368: STAT(icmpstat.icps_reflect++);
1.1 root 369: }
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