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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
36 /* The message sent when emulating PING */
37 /* Be nice and tell them it's just a pseudo-ping packet */
38 static const char icmp_ping_msg[] = "This is a pseudo-PING packet used by Slirp to emulate ICMP ECHO-REQUEST packets.\n";
40 /* list of actions for icmp_error() on RX of an icmp message */
41 static const int icmp_flush[19] = {
42 /* ECHO REPLY (0) */ 0,
45 /* DEST UNREACH (3) */ 1,
46 /* SOURCE QUENCH (4)*/ 1,
51 /* ROUTERADVERT (9) */ 1,
52 /* ROUTERSOLICIT (10) */ 1,
53 /* TIME EXCEEDED (11) */ 1,
54 /* PARAMETER PROBLEM (12) */ 1,
55 /* TIMESTAMP (13) */ 0,
56 /* TIMESTAMP REPLY (14) */ 0,
58 /* INFO REPLY (16) */ 0,
59 /* ADDR MASK (17) */ 0,
60 /* ADDR MASK REPLY (18) */ 0
63 int icmp_attach(struct socket *so);
64 void icmp_detach(struct socket *so);
65 int icmp_cksum(u_short *p, int n);
68 icmp_attach(struct socket *so)
70 /* same as udp_attach except socket creation */
71 if((so->s = qemu_socket(AF_INET,SOCK_RAW,IPPROTO_ICMP)) != -1) {
72 so->so_expire = curtime + SO_EXPIRE;
73 insque(so, &so->slirp->udb);
79 icmp_detach(struct socket *so)
81 /* same as udp_detach */
87 icmp_cksum(u_short *p, int n)
89 register u_short answer;
90 register long sum = 0;
101 /* mop up an odd byte, if necessary */
104 *( u_char* )( &odd_byte ) = *( u_char* )p;
109 sum = ( sum >> 16 ) + ( sum & 0xffff ); /* add hi 16 to low 16 */
110 sum += ( sum >> 16 ); /* add carry */
111 answer = ~sum; /* ones-complement, truncate*/
118 * Process a received ICMP message.
121 icmp_input(struct mbuf *m, int hlen)
123 register struct icmp *icp;
124 register struct ip *ip=mtod(m, struct ip *);
125 int icmplen=ip->ip_len;
126 Slirp *slirp = m->slirp;
128 DEBUG_CALL("icmp_input");
129 DEBUG_ARG("m = %lx", (long )m);
130 DEBUG_ARG("m_len = %d", m->m_len);
133 * Locate icmp structure in mbuf, and check
134 * that its not corrupted and of at least minimum length.
136 if (icmplen < ICMP_MINLEN) { /* min 8 bytes payload */
144 icp = mtod(m, struct icmp *);
145 if (cksum(m, icmplen)) {
151 DEBUG_ARG("icmp_type = %d", icp->icmp_type);
152 switch (icp->icmp_type) {
154 icp->icmp_type = ICMP_ECHOREPLY;
155 ip->ip_len += hlen; /* since ip_input subtracts this */
156 if (ip->ip_dst.s_addr == slirp->vhost_addr.s_addr) {
159 } else if( getuid() != 0 ) {
163 sprintf( commands, "ping -c 1 %s", inet_ntoa(ip->ip_dst) );
164 code = system( commands );
166 if( WIFEXITED(code) && WEXITSTATUS(code) == 0 )
169 icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_NET, 0, "ping failed");
173 struct icmp *picmp = (struct icmp *)icmp_buf;
175 struct sockaddr_in addr;
176 if ((so = socreate(slirp)) == NULL) goto freeit;
177 if(icmp_attach(so) == -1) {
178 DEBUG_MISC((dfd,"icmp_input udp_attach errno = %d-%s\n",
179 errno,strerror(errno)));
185 so->so_faddr = ip->ip_dst;
186 so->so_fport = htons(7);
187 so->so_laddr = ip->ip_src;
188 so->so_lport = htons(9);
189 so->so_iptos = ip->ip_tos;
190 so->so_type = IPPROTO_ICMP;
191 so->so_state = SS_ISFCONNECTED;
193 /* Send the packet */
194 addr.sin_family = AF_INET;
195 if ((so->so_faddr.s_addr & slirp->vnetwork_mask.s_addr) ==
196 slirp->vnetwork_addr.s_addr) {
198 if (so->so_faddr.s_addr == slirp->vnameserver_addr.s_addr) {
199 if (get_dns_addr(&addr.sin_addr) < 0)
200 addr.sin_addr = loopback_addr;
202 addr.sin_addr = loopback_addr;
205 addr.sin_addr = so->so_faddr;
207 addr.sin_port = so->so_fport;
209 picmp->icmp_type = ICMP_ECHO;
210 picmp->icmp_code = 0;
211 picmp->icmp_cksum = 0;
212 picmp->icmp_id = icp->icmp_id;
213 picmp->icmp_seq = icp->icmp_seq;
214 strcpy(icmp_buf+8, icmp_ping_msg);
215 picmp->icmp_cksum = icmp_cksum((u_short *)picmp, sizeof(icmp_ping_msg)+8);
217 if(sendto(so->s, picmp, sizeof(icmp_ping_msg)+8, 0,
218 (struct sockaddr *)&addr, sizeof(addr)) == -1) {
219 DEBUG_MISC((dfd,"icmp_input udp sendto tx errno = %d-%s\n",
220 errno,strerror(errno)));
221 icmp_error(m, ICMP_UNREACH,ICMP_UNREACH_NET, 0,strerror(errno));
224 } /* if ip->ip_dst.s_addr == alias_addr.s_addr */
227 /* XXX? report error? close socket? */
230 case ICMP_SOURCEQUENCH:
242 /* m is m_free()'d xor put in a socket xor or given to ip_send */
248 * Send an ICMP message in response to a situation
250 * RFC 1122: 3.2.2 MUST send at least the IP header and 8 bytes of header. MAY send more (we do).
251 * MUST NOT change this header information.
252 * MUST NOT reply to a multicast/broadcast IP address.
253 * MUST NOT reply to a multicast/broadcast MAC address.
254 * MUST reply to only the first fragment.
257 * Send ICMP_UNREACH back to the source regarding msrc.
258 * mbuf *msrc is used as a template, but is NOT m_free()'d.
259 * It is reported as the bad ip packet. The header should
260 * be fully correct and in host byte order.
261 * ICMP fragmentation is illegal. All machines must accept 576 bytes in one
262 * packet. The maximum payload is 576-20(ip hdr)-8(icmp hdr)=548
265 #define ICMP_MAXDATALEN (IP_MSS-28)
267 icmp_error(struct mbuf *msrc, u_char type, u_char code, int minsize,
270 unsigned hlen, shlen, s_ip_len;
271 register struct ip *ip;
272 register struct icmp *icp;
273 register struct mbuf *m;
275 DEBUG_CALL("icmp_error");
276 DEBUG_ARG("msrc = %lx", (long )msrc);
277 DEBUG_ARG("msrc_len = %d", msrc->m_len);
279 if(type!=ICMP_UNREACH && type!=ICMP_TIMXCEED) goto end_error;
282 if(!msrc) goto end_error;
283 ip = mtod(msrc, struct ip *);
285 { char bufa[20], bufb[20];
286 strcpy(bufa, inet_ntoa(ip->ip_src));
287 strcpy(bufb, inet_ntoa(ip->ip_dst));
288 DEBUG_MISC((dfd, " %.16s to %.16s\n", bufa, bufb));
291 if(ip->ip_off & IP_OFFMASK) goto end_error; /* Only reply to fragment 0 */
293 shlen=ip->ip_hl << 2;
295 if(ip->ip_p == IPPROTO_ICMP) {
296 icp = (struct icmp *)((char *)ip + shlen);
298 * Assume any unknown ICMP type is an error. This isn't
299 * specified by the RFC, but think about it..
301 if(icp->icmp_type>18 || icmp_flush[icp->icmp_type]) goto end_error;
305 m = m_get(msrc->slirp);
311 new_m_size=sizeof(struct ip )+ICMP_MINLEN+msrc->m_len+ICMP_MAXDATALEN;
312 if(new_m_size>m->m_size) m_inc(m, new_m_size);
314 memcpy(m->m_data, msrc->m_data, msrc->m_len);
315 m->m_len = msrc->m_len; /* copy msrc to m */
317 /* make the header of the reply packet */
318 ip = mtod(m, struct ip *);
319 hlen= sizeof(struct ip ); /* no options in reply */
325 icp = mtod(m, struct icmp *);
327 if(minsize) s_ip_len=shlen+ICMP_MINLEN; /* return header+8b only */
328 else if(s_ip_len>ICMP_MAXDATALEN) /* maximum size */
329 s_ip_len=ICMP_MAXDATALEN;
331 m->m_len=ICMP_MINLEN+s_ip_len; /* 8 bytes ICMP header */
333 /* min. size = 8+sizeof(struct ip)+8 */
335 icp->icmp_type = type;
336 icp->icmp_code = code;
340 memcpy(&icp->icmp_ip, msrc->m_data, s_ip_len); /* report the ip packet */
341 HTONS(icp->icmp_ip.ip_len);
342 HTONS(icp->icmp_ip.ip_id);
343 HTONS(icp->icmp_ip.ip_off);
346 if(message) { /* DEBUG : append message to ICMP packet */
349 message_len=strlen(message);
350 if(message_len>ICMP_MAXDATALEN) message_len=ICMP_MAXDATALEN;
351 cpnt=(char *)m->m_data+m->m_len;
352 memcpy(cpnt, message, message_len);
353 m->m_len+=message_len;
358 icp->icmp_cksum = cksum(m, m->m_len);
364 ip->ip_hl = hlen >> 2;
365 ip->ip_len = m->m_len;
367 ip->ip_tos=((ip->ip_tos & 0x1E) | 0xC0); /* high priority for errors */
370 ip->ip_p = IPPROTO_ICMP;
371 ip->ip_dst = ip->ip_src; /* ip adresses */
372 ip->ip_src = m->slirp->vhost_addr;
374 (void ) ip_output((struct socket *)NULL, m);
379 #undef ICMP_MAXDATALEN
382 * Reflect the ip packet back to the source
385 icmp_reflect(struct mbuf *m)
387 register struct ip *ip = mtod(m, struct ip *);
388 int hlen = ip->ip_hl << 2;
389 int optlen = hlen - sizeof(struct ip );
390 register struct icmp *icp;
393 * Send an icmp packet back to the ip level,
394 * after supplying a checksum.
398 icp = mtod(m, struct icmp *);
401 icp->icmp_cksum = cksum(m, ip->ip_len - hlen);
409 * Strip out original options by copying rest of first
410 * mbuf's data back, and adjust the IP length.
412 memmove((caddr_t)(ip + 1), (caddr_t)ip + hlen,
413 (unsigned )(m->m_len - hlen));
415 ip->ip_hl = hlen >> 2;
416 ip->ip_len -= optlen;
422 struct in_addr icmp_dst;
423 icmp_dst = ip->ip_dst;
424 ip->ip_dst = ip->ip_src;
425 ip->ip_src = icmp_dst;
428 (void ) ip_output((struct socket *)NULL, m);