xref: /openbsd-src/usr.sbin/dhcpd/icmp.c (revision 91f110e064cd7c194e59e019b83bb7496c1c84d4)
1 /*	$OpenBSD: icmp.c,v 1.10 2008/09/15 20:38:17 claudio Exp $ */
2 
3 /*
4  * Copyright (c) 1997, 1998 The Internet Software Consortium.
5  * All rights reserved.
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  *
11  * 1. Redistributions of source code must retain the above copyright
12  *    notice, this list of conditions and the following disclaimer.
13  * 2. Redistributions in binary form must reproduce the above copyright
14  *    notice, this list of conditions and the following disclaimer in the
15  *    documentation and/or other materials provided with the distribution.
16  * 3. Neither the name of The Internet Software Consortium nor the names
17  *    of its contributors may be used to endorse or promote products derived
18  *    from this software without specific prior written permission.
19  *
20  * THIS SOFTWARE IS PROVIDED BY THE INTERNET SOFTWARE CONSORTIUM AND
21  * CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
22  * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
23  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
24  * DISCLAIMED.  IN NO EVENT SHALL THE INTERNET SOFTWARE CONSORTIUM OR
25  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
26  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
27  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
28  * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
29  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
30  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
31  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32  * SUCH DAMAGE.
33  *
34  * This software has been written for the Internet Software Consortium
35  * by Ted Lemon <mellon@fugue.com> in cooperation with Vixie
36  * Enterprises.  To learn more about the Internet Software Consortium,
37  * see ``http://www.vix.com/isc''.  To learn more about Vixie
38  * Enterprises, see ``http://www.vix.com''.
39  */
40 
41 #include "dhcpd.h"
42 #include <netinet/in_systm.h>
43 #include <netinet/ip.h>
44 #include <netinet/ip_icmp.h>
45 
46 static int icmp_protocol_initialized;
47 static int icmp_protocol_fd;
48 
49 /* Initialize the ICMP protocol. */
50 
51 void
52 icmp_startup(int routep, void (*handler)(struct iaddr, u_int8_t *, int))
53 {
54 	struct protoent *proto;
55 	int protocol = 1, state;
56 
57 	/* Only initialize icmp once. */
58 	if (icmp_protocol_initialized)
59 		error("attempted to reinitialize icmp protocol");
60 	icmp_protocol_initialized = 1;
61 
62 	/* Get the protocol number (should be 1). */
63 	if ((proto = getprotobyname("icmp")) != NULL)
64 		protocol = proto->p_proto;
65 
66 	/* Get a raw socket for the ICMP protocol. */
67 	if ((icmp_protocol_fd = socket(AF_INET, SOCK_RAW, protocol)) == -1)
68 		error("unable to create icmp socket: %m");
69 
70 	/* Make sure it does routing... */
71 	state = 0;
72 	if (setsockopt(icmp_protocol_fd, SOL_SOCKET, SO_DONTROUTE,
73 	    &state, sizeof(state)) == -1)
74 		error("Unable to disable SO_DONTROUTE on ICMP socket: %m");
75 
76 	add_protocol("icmp", icmp_protocol_fd, icmp_echoreply, (void *)handler);
77 }
78 
79 int
80 icmp_echorequest(struct iaddr *addr)
81 {
82 	struct sockaddr_in to;
83 	struct icmp icmp;
84 	int status;
85 
86 	if (!icmp_protocol_initialized)
87 		error("attempt to use ICMP protocol before initialization.");
88 
89 	bzero(&to, sizeof(to));
90 	to.sin_len = sizeof to;
91 	to.sin_family = AF_INET;
92 	memcpy(&to.sin_addr, addr->iabuf, sizeof to.sin_addr);	/* XXX */
93 
94 	icmp.icmp_type = ICMP_ECHO;
95 	icmp.icmp_code = 0;
96 	icmp.icmp_cksum = 0;
97 	icmp.icmp_seq = 0;
98 	icmp.icmp_id = getpid() & 0xffff;
99 
100 	icmp.icmp_cksum = wrapsum(checksum((unsigned char *)&icmp,
101 	    sizeof(icmp), 0));
102 
103 	/* Send the ICMP packet... */
104 	status = sendto(icmp_protocol_fd, &icmp, sizeof(icmp), 0,
105 	    (struct sockaddr *)&to, sizeof(to));
106 	if (status == -1)
107 		warning("icmp_echorequest %s: %m", inet_ntoa(to.sin_addr));
108 
109 	if (status != sizeof icmp)
110 		return 0;
111 	return 1;
112 }
113 
114 void
115 icmp_echoreply(struct protocol *protocol)
116 {
117 	void (*handler)(struct iaddr, u_int8_t *, int);
118 	struct sockaddr_in from;
119 	u_int8_t icbuf[1500];
120 	struct icmp *icfrom;
121 	int status, len;
122 	socklen_t salen;
123 	struct iaddr ia;
124 
125 	salen = sizeof from;
126 	status = recvfrom(protocol->fd, icbuf, sizeof(icbuf), 0,
127 	    (struct sockaddr *)&from, &salen);
128 	if (status == -1) {
129 		warning("icmp_echoreply: %m");
130 		return;
131 	}
132 
133 	/* Probably not for us. */
134 	if (status < (sizeof(struct ip)) + (sizeof *icfrom))
135 		return;
136 
137 	len = status - sizeof(struct ip);
138 	icfrom = (struct icmp *)(icbuf + sizeof(struct ip));
139 
140 	/* Silently discard ICMP packets that aren't echoreplies. */
141 	if (icfrom->icmp_type != ICMP_ECHOREPLY)
142 		return;
143 
144 	/* If we were given a second-stage handler, call it. */
145 	if (protocol->local) {
146 		handler = ((void (*)(struct iaddr, u_int8_t *, int))
147 		    protocol->local);
148 		memcpy(ia.iabuf, &from.sin_addr, sizeof from.sin_addr);
149 		ia.len = sizeof from.sin_addr;
150 		(*handler)(ia, icbuf, len);
151 	}
152 }
153