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2 * Copyright (c) 1982, 1986, 1988, 1993
3 * The Regents of the University of California. All rights reserved.
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
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. Neither the name of the University nor the names of its contributors
14 * may be used to endorse or promote products derived from this software
15 * without specific prior written permission.
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
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
64 * Process a received ICMP message.
67 icmp_input(struct mbuf
*m
, int hlen
)
69 register struct icmp
*icp
;
70 register struct ip
*ip
=mtod(m
, struct ip
*);
71 int icmplen
=ip
->ip_len
;
73 DEBUG_CALL("icmp_input");
74 DEBUG_ARG("m = %lx", (long )m
);
75 DEBUG_ARG("m_len = %d", m
->m_len
);
78 * Locate icmp structure in mbuf, and check
79 * that its not corrupted and of at least minimum length.
81 if (icmplen
< ICMP_MINLEN
) { /* min 8 bytes payload */
89 icp
= mtod(m
, struct icmp
*);
90 if (cksum(m
, icmplen
)) {
96 DEBUG_ARG("icmp_type = %d", icp
->icmp_type
);
97 switch (icp
->icmp_type
) {
99 icp
->icmp_type
= ICMP_ECHOREPLY
;
100 ip
->ip_len
+= hlen
; /* since ip_input subtracts this */
101 if (ip
->ip_dst
.s_addr
== vhost_addr
.s_addr
) {
105 struct sockaddr_in addr
;
106 if ((so
= socreate()) == NULL
) goto freeit
;
107 if(udp_attach(so
) == -1) {
108 DEBUG_MISC((dfd
,"icmp_input udp_attach errno = %d-%s\n",
109 errno
,strerror(errno
)));
115 so
->so_faddr
= ip
->ip_dst
;
116 so
->so_fport
= htons(7);
117 so
->so_laddr
= ip
->ip_src
;
118 so
->so_lport
= htons(9);
119 so
->so_iptos
= ip
->ip_tos
;
120 so
->so_type
= IPPROTO_ICMP
;
121 so
->so_state
= SS_ISFCONNECTED
;
123 /* Send the packet */
124 addr
.sin_family
= AF_INET
;
125 if ((so
->so_faddr
.s_addr
& vnetwork_mask
.s_addr
) ==
126 vnetwork_addr
.s_addr
) {
128 if (so
->so_faddr
.s_addr
== vnameserver_addr
.s_addr
) {
129 addr
.sin_addr
= dns_addr
;
131 addr
.sin_addr
= loopback_addr
;
134 addr
.sin_addr
= so
->so_faddr
;
136 addr
.sin_port
= so
->so_fport
;
137 if(sendto(so
->s
, icmp_ping_msg
, strlen(icmp_ping_msg
), 0,
138 (struct sockaddr
*)&addr
, sizeof(addr
)) == -1) {
139 DEBUG_MISC((dfd
,"icmp_input udp sendto tx errno = %d-%s\n",
140 errno
,strerror(errno
)));
141 icmp_error(m
, ICMP_UNREACH
,ICMP_UNREACH_NET
, 0,strerror(errno
));
144 } /* if ip->ip_dst.s_addr == alias_addr.s_addr */
147 /* XXX? report error? close socket? */
150 case ICMP_SOURCEQUENCH
:
162 /* m is m_free()'d xor put in a socket xor or given to ip_send */
168 * Send an ICMP message in response to a situation
170 * RFC 1122: 3.2.2 MUST send at least the IP header and 8 bytes of header. MAY send more (we do).
171 * MUST NOT change this header information.
172 * MUST NOT reply to a multicast/broadcast IP address.
173 * MUST NOT reply to a multicast/broadcast MAC address.
174 * MUST reply to only the first fragment.
177 * Send ICMP_UNREACH back to the source regarding msrc.
178 * mbuf *msrc is used as a template, but is NOT m_free()'d.
179 * It is reported as the bad ip packet. The header should
180 * be fully correct and in host byte order.
181 * ICMP fragmentation is illegal. All machines must accept 576 bytes in one
182 * packet. The maximum payload is 576-20(ip hdr)-8(icmp hdr)=548
185 #define ICMP_MAXDATALEN (IP_MSS-28)
187 icmp_error(struct mbuf
*msrc
, u_char type
, u_char code
, int minsize
,
190 unsigned hlen
, shlen
, s_ip_len
;
191 register struct ip
*ip
;
192 register struct icmp
*icp
;
193 register struct mbuf
*m
;
195 DEBUG_CALL("icmp_error");
196 DEBUG_ARG("msrc = %lx", (long )msrc
);
197 DEBUG_ARG("msrc_len = %d", msrc
->m_len
);
199 if(type
!=ICMP_UNREACH
&& type
!=ICMP_TIMXCEED
) goto end_error
;
202 if(!msrc
) goto end_error
;
203 ip
= mtod(msrc
, struct ip
*);
205 { char bufa
[20], bufb
[20];
206 strcpy(bufa
, inet_ntoa(ip
->ip_src
));
207 strcpy(bufb
, inet_ntoa(ip
->ip_dst
));
208 DEBUG_MISC((dfd
, " %.16s to %.16s\n", bufa
, bufb
));
211 if(ip
->ip_off
& IP_OFFMASK
) goto end_error
; /* Only reply to fragment 0 */
213 shlen
=ip
->ip_hl
<< 2;
215 if(ip
->ip_p
== IPPROTO_ICMP
) {
216 icp
= (struct icmp
*)((char *)ip
+ shlen
);
218 * Assume any unknown ICMP type is an error. This isn't
219 * specified by the RFC, but think about it..
221 if(icp
->icmp_type
>18 || icmp_flush
[icp
->icmp_type
]) goto end_error
;
225 if(!(m
=m_get())) goto end_error
; /* get mbuf */
227 new_m_size
=sizeof(struct ip
)+ICMP_MINLEN
+msrc
->m_len
+ICMP_MAXDATALEN
;
228 if(new_m_size
>m
->m_size
) m_inc(m
, new_m_size
);
230 memcpy(m
->m_data
, msrc
->m_data
, msrc
->m_len
);
231 m
->m_len
= msrc
->m_len
; /* copy msrc to m */
233 /* make the header of the reply packet */
234 ip
= mtod(m
, struct ip
*);
235 hlen
= sizeof(struct ip
); /* no options in reply */
241 icp
= mtod(m
, struct icmp
*);
243 if(minsize
) s_ip_len
=shlen
+ICMP_MINLEN
; /* return header+8b only */
244 else if(s_ip_len
>ICMP_MAXDATALEN
) /* maximum size */
245 s_ip_len
=ICMP_MAXDATALEN
;
247 m
->m_len
=ICMP_MINLEN
+s_ip_len
; /* 8 bytes ICMP header */
249 /* min. size = 8+sizeof(struct ip)+8 */
251 icp
->icmp_type
= type
;
252 icp
->icmp_code
= code
;
256 memcpy(&icp
->icmp_ip
, msrc
->m_data
, s_ip_len
); /* report the ip packet */
257 HTONS(icp
->icmp_ip
.ip_len
);
258 HTONS(icp
->icmp_ip
.ip_id
);
259 HTONS(icp
->icmp_ip
.ip_off
);
262 if(message
) { /* DEBUG : append message to ICMP packet */
265 message_len
=strlen(message
);
266 if(message_len
>ICMP_MAXDATALEN
) message_len
=ICMP_MAXDATALEN
;
267 cpnt
=(char *)m
->m_data
+m
->m_len
;
268 memcpy(cpnt
, message
, message_len
);
269 m
->m_len
+=message_len
;
274 icp
->icmp_cksum
= cksum(m
, m
->m_len
);
280 ip
->ip_hl
= hlen
>> 2;
281 ip
->ip_len
= m
->m_len
;
283 ip
->ip_tos
=((ip
->ip_tos
& 0x1E) | 0xC0); /* high priority for errors */
286 ip
->ip_p
= IPPROTO_ICMP
;
287 ip
->ip_dst
= ip
->ip_src
; /* ip adresses */
288 ip
->ip_src
= vhost_addr
;
290 (void ) ip_output((struct socket
*)NULL
, m
);
295 #undef ICMP_MAXDATALEN
298 * Reflect the ip packet back to the source
301 icmp_reflect(struct mbuf
*m
)
303 register struct ip
*ip
= mtod(m
, struct ip
*);
304 int hlen
= ip
->ip_hl
<< 2;
305 int optlen
= hlen
- sizeof(struct ip
);
306 register struct icmp
*icp
;
309 * Send an icmp packet back to the ip level,
310 * after supplying a checksum.
314 icp
= mtod(m
, struct icmp
*);
317 icp
->icmp_cksum
= cksum(m
, ip
->ip_len
- hlen
);
325 * Strip out original options by copying rest of first
326 * mbuf's data back, and adjust the IP length.
328 memmove((caddr_t
)(ip
+ 1), (caddr_t
)ip
+ hlen
,
329 (unsigned )(m
->m_len
- hlen
));
331 ip
->ip_hl
= hlen
>> 2;
332 ip
->ip_len
-= optlen
;
338 struct in_addr icmp_dst
;
339 icmp_dst
= ip
->ip_dst
;
340 ip
->ip_dst
= ip
->ip_src
;
341 ip
->ip_src
= icmp_dst
;
344 (void ) ip_output((struct socket
*)NULL
, m
);