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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:
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
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 */
1.1.1.2 ! root 117: if (ip->ip_dst.s_addr == alias_addr.s_addr) {
1.1 root 118: icmp_reflect(m);
119: } else {
120: struct socket *so;
121: struct sockaddr_in addr;
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,strerror(errno)));
126: sofree(so);
127: m_free(m);
128: goto end_error;
129: }
130: so->so_m = m;
131: so->so_faddr = ip->ip_dst;
132: so->so_fport = htons(7);
133: so->so_laddr = ip->ip_src;
134: so->so_lport = htons(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: addr.sin_family = AF_INET;
141: if ((so->so_faddr.s_addr & htonl(0xffffff00)) == special_addr.s_addr) {
142: /* It's an alias */
143: switch(ntohl(so->so_faddr.s_addr) & 0xff) {
144: case CTL_DNS:
145: addr.sin_addr = dns_addr;
146: break;
147: case CTL_ALIAS:
148: default:
149: addr.sin_addr = loopback_addr;
150: break;
151: }
152: } else {
153: addr.sin_addr = so->so_faddr;
154: }
155: addr.sin_port = so->so_fport;
156: if(sendto(so->s, icmp_ping_msg, strlen(icmp_ping_msg), 0,
157: (struct sockaddr *)&addr, sizeof(addr)) == -1) {
158: DEBUG_MISC((dfd,"icmp_input udp sendto tx errno = %d-%s\n",
159: errno,strerror(errno)));
160: icmp_error(m, ICMP_UNREACH,ICMP_UNREACH_NET, 0,strerror(errno));
161: udp_detach(so);
162: }
1.1.1.2 ! root 163: } /* if ip->ip_dst.s_addr == alias_addr.s_addr */
1.1 root 164: break;
165: case ICMP_UNREACH:
166: /* XXX? report error? close socket? */
167: case ICMP_TIMXCEED:
168: case ICMP_PARAMPROB:
169: case ICMP_SOURCEQUENCH:
170: case ICMP_TSTAMP:
171: case ICMP_MASKREQ:
172: case ICMP_REDIRECT:
173: icmpstat.icps_notsupp++;
174: m_freem(m);
175: break;
176:
177: default:
178: icmpstat.icps_badtype++;
179: m_freem(m);
180: } /* swith */
181:
182: end_error:
183: /* m is m_free()'d xor put in a socket xor or given to ip_send */
184: return;
185: }
186:
187:
188: /*
189: * Send an ICMP message in response to a situation
190: *
191: * RFC 1122: 3.2.2 MUST send at least the IP header and 8 bytes of header. MAY send more (we do).
192: * MUST NOT change this header information.
193: * MUST NOT reply to a multicast/broadcast IP address.
194: * MUST NOT reply to a multicast/broadcast MAC address.
195: * MUST reply to only the first fragment.
196: */
197: /*
198: * Send ICMP_UNREACH back to the source regarding msrc.
199: * mbuf *msrc is used as a template, but is NOT m_free()'d.
200: * It is reported as the bad ip packet. The header should
201: * be fully correct and in host byte order.
202: * ICMP fragmentation is illegal. All machines must accept 576 bytes in one
203: * packet. The maximum payload is 576-20(ip hdr)-8(icmp hdr)=548
204: */
205:
206: #define ICMP_MAXDATALEN (IP_MSS-28)
207: void
208: icmp_error(msrc, type, code, minsize, message)
209: struct mbuf *msrc;
210: u_char type;
211: u_char code;
212: int minsize;
213: char *message;
214: {
215: unsigned hlen, shlen, s_ip_len;
216: register struct ip *ip;
217: register struct icmp *icp;
218: register struct mbuf *m;
219:
220: DEBUG_CALL("icmp_error");
221: DEBUG_ARG("msrc = %lx", (long )msrc);
222: DEBUG_ARG("msrc_len = %d", msrc->m_len);
223:
224: if(type!=ICMP_UNREACH && type!=ICMP_TIMXCEED) goto end_error;
225:
226: /* check msrc */
227: if(!msrc) goto end_error;
228: ip = mtod(msrc, struct ip *);
229: #if DEBUG
230: { char bufa[20], bufb[20];
231: strcpy(bufa, inet_ntoa(ip->ip_src));
232: strcpy(bufb, inet_ntoa(ip->ip_dst));
233: DEBUG_MISC((dfd, " %.16s to %.16s\n", bufa, bufb));
234: }
235: #endif
236: if(ip->ip_off & IP_OFFMASK) goto end_error; /* Only reply to fragment 0 */
237:
238: shlen=ip->ip_hl << 2;
239: s_ip_len=ip->ip_len;
240: if(ip->ip_p == IPPROTO_ICMP) {
241: icp = (struct icmp *)((char *)ip + shlen);
242: /*
243: * Assume any unknown ICMP type is an error. This isn't
244: * specified by the RFC, but think about it..
245: */
246: if(icp->icmp_type>18 || icmp_flush[icp->icmp_type]) goto end_error;
247: }
248:
249: /* make a copy */
250: if(!(m=m_get())) goto end_error; /* get mbuf */
251: { int new_m_size;
252: new_m_size=sizeof(struct ip )+ICMP_MINLEN+msrc->m_len+ICMP_MAXDATALEN;
253: if(new_m_size>m->m_size) m_inc(m, new_m_size);
254: }
255: memcpy(m->m_data, msrc->m_data, msrc->m_len);
256: m->m_len = msrc->m_len; /* copy msrc to m */
257:
258: /* make the header of the reply packet */
259: ip = mtod(m, struct ip *);
260: hlen= sizeof(struct ip ); /* no options in reply */
261:
262: /* fill in icmp */
263: m->m_data += hlen;
264: m->m_len -= hlen;
265:
266: icp = mtod(m, struct icmp *);
267:
268: if(minsize) s_ip_len=shlen+ICMP_MINLEN; /* return header+8b only */
269: else if(s_ip_len>ICMP_MAXDATALEN) /* maximum size */
270: s_ip_len=ICMP_MAXDATALEN;
271:
272: m->m_len=ICMP_MINLEN+s_ip_len; /* 8 bytes ICMP header */
273:
274: /* min. size = 8+sizeof(struct ip)+8 */
275:
276: icp->icmp_type = type;
277: icp->icmp_code = code;
278: icp->icmp_id = 0;
279: icp->icmp_seq = 0;
280:
281: memcpy(&icp->icmp_ip, msrc->m_data, s_ip_len); /* report the ip packet */
282: HTONS(icp->icmp_ip.ip_len);
283: HTONS(icp->icmp_ip.ip_id);
284: HTONS(icp->icmp_ip.ip_off);
285:
286: #if DEBUG
287: if(message) { /* DEBUG : append message to ICMP packet */
288: int message_len;
289: char *cpnt;
290: message_len=strlen(message);
291: if(message_len>ICMP_MAXDATALEN) message_len=ICMP_MAXDATALEN;
292: cpnt=(char *)m->m_data+m->m_len;
293: memcpy(cpnt, message, message_len);
294: m->m_len+=message_len;
295: }
296: #endif
297:
298: icp->icmp_cksum = 0;
299: icp->icmp_cksum = cksum(m, m->m_len);
300:
301: m->m_data -= hlen;
302: m->m_len += hlen;
303:
304: /* fill in ip */
305: ip->ip_hl = hlen >> 2;
306: ip->ip_len = m->m_len;
307:
308: ip->ip_tos=((ip->ip_tos & 0x1E) | 0xC0); /* high priority for errors */
309:
310: ip->ip_ttl = MAXTTL;
311: ip->ip_p = IPPROTO_ICMP;
312: ip->ip_dst = ip->ip_src; /* ip adresses */
1.1.1.2 ! root 313: ip->ip_src = alias_addr;
1.1 root 314:
315: (void ) ip_output((struct socket *)NULL, m);
316:
317: icmpstat.icps_reflect++;
318:
319: end_error:
320: return;
321: }
322: #undef ICMP_MAXDATALEN
323:
324: /*
325: * Reflect the ip packet back to the source
326: */
327: void
328: icmp_reflect(m)
329: struct mbuf *m;
330: {
331: register struct ip *ip = mtod(m, struct ip *);
332: int hlen = ip->ip_hl << 2;
333: int optlen = hlen - sizeof(struct ip );
334: register struct icmp *icp;
335:
336: /*
337: * Send an icmp packet back to the ip level,
338: * after supplying a checksum.
339: */
340: m->m_data += hlen;
341: m->m_len -= hlen;
342: icp = mtod(m, struct icmp *);
343:
344: icp->icmp_cksum = 0;
345: icp->icmp_cksum = cksum(m, ip->ip_len - hlen);
346:
347: m->m_data -= hlen;
348: m->m_len += hlen;
349:
350: /* fill in ip */
351: if (optlen > 0) {
352: /*
353: * Strip out original options by copying rest of first
354: * mbuf's data back, and adjust the IP length.
355: */
356: memmove((caddr_t)(ip + 1), (caddr_t)ip + hlen,
357: (unsigned )(m->m_len - hlen));
358: hlen -= optlen;
359: ip->ip_hl = hlen >> 2;
360: ip->ip_len -= optlen;
361: m->m_len -= optlen;
362: }
363:
364: ip->ip_ttl = MAXTTL;
365: { /* swap */
366: struct in_addr icmp_dst;
367: icmp_dst = ip->ip_dst;
368: ip->ip_dst = ip->ip_src;
369: ip->ip_src = icmp_dst;
370: }
371:
372: (void ) ip_output((struct socket *)NULL, m);
373:
374: icmpstat.icps_reflect++;
375: }
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