1/*	$OpenBSD: icmp.c,v 1.19 2019/10/03 13:36:15 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 <sys/types.h>
42#include <sys/socket.h>
43
44#include <arpa/inet.h>
45
46#include <net/if.h>
47
48#include <netinet/ip.h>
49#include <netinet/ip_icmp.h>
50
51#include <netdb.h>
52#include <stdio.h>
53#include <string.h>
54#include <unistd.h>
55
56#include "dhcp.h"
57#include "tree.h"
58#include "dhcpd.h"
59#include "log.h"
60
61static int icmp_protocol_initialized;
62static int icmp_protocol_fd;
63
64/* Initialize the ICMP protocol. */
65
66void
67icmp_startup(int routep, void (*handler)(struct iaddr, u_int8_t *, int))
68{
69	struct protoent *proto;
70	int protocol = 1, state;
71
72	/* Only initialize icmp once. */
73	if (icmp_protocol_initialized)
74		fatalx("attempted to reinitialize icmp protocol");
75	icmp_protocol_initialized = 1;
76
77	/* Get the protocol number (should be 1). */
78	if ((proto = getprotobyname("icmp")) != NULL)
79		protocol = proto->p_proto;
80
81	/* Get a raw socket for the ICMP protocol. */
82	if ((icmp_protocol_fd = socket(AF_INET, SOCK_RAW, protocol)) == -1)
83		fatal("unable to create icmp socket");
84
85	/* Make sure it does routing... */
86	state = 0;
87	if (setsockopt(icmp_protocol_fd, SOL_SOCKET, SO_DONTROUTE,
88	    &state, sizeof(state)) == -1)
89		fatal("Unable to disable SO_DONTROUTE on ICMP socket");
90
91	add_protocol("icmp", icmp_protocol_fd, icmp_echoreply,
92	    (void *)handler);
93}
94
95int
96icmp_echorequest(struct iaddr *addr)
97{
98	struct sockaddr_in to;
99	struct icmp icmp;
100	int status;
101
102	if (!icmp_protocol_initialized)
103		fatalx("attempt to use ICMP protocol before initialization.");
104
105	memset(&to, 0, sizeof(to));
106	to.sin_len = sizeof to;
107	to.sin_family = AF_INET;
108	memcpy(&to.sin_addr, addr->iabuf, sizeof to.sin_addr);	/* XXX */
109
110	memset(&icmp, 0, sizeof(icmp));
111	icmp.icmp_type = ICMP_ECHO;
112	icmp.icmp_id = getpid() & 0xffff;
113
114	icmp.icmp_cksum = wrapsum(checksum((unsigned char *)&icmp,
115	    sizeof(icmp), 0));
116
117	/* Send the ICMP packet... */
118	status = sendto(icmp_protocol_fd, &icmp, sizeof(icmp), 0,
119	    (struct sockaddr *)&to, sizeof(to));
120	if (status == -1)
121		log_warn("icmp_echorequest %s", inet_ntoa(to.sin_addr));
122
123	if (status != sizeof icmp)
124		return 0;
125	return 1;
126}
127
128void
129icmp_echoreply(struct protocol *protocol)
130{
131	void (*handler)(struct iaddr, u_int8_t *, int);
132	struct sockaddr_in from;
133	u_int8_t icbuf[1500];
134	struct icmp *icfrom;
135	int status, len;
136	socklen_t salen;
137	struct iaddr ia;
138
139	salen = sizeof from;
140	status = recvfrom(protocol->fd, icbuf, sizeof(icbuf), 0,
141	    (struct sockaddr *)&from, &salen);
142	if (status == -1) {
143		log_warn("icmp_echoreply");
144		return;
145	}
146
147	/* Probably not for us. */
148	if (status < (sizeof(struct ip)) + (sizeof *icfrom))
149		return;
150
151	len = status - sizeof(struct ip);
152	icfrom = (struct icmp *)(icbuf + sizeof(struct ip));
153
154	/* Silently discard ICMP packets that aren't echoreplies. */
155	if (icfrom->icmp_type != ICMP_ECHOREPLY)
156		return;
157
158	/* If we were given a second-stage handler, call it. */
159	if (protocol->local) {
160		handler = ((void (*)(struct iaddr, u_int8_t *, int))
161		    protocol->local);
162		memcpy(ia.iabuf, &from.sin_addr, sizeof from.sin_addr);
163		ia.len = sizeof from.sin_addr;
164		(*handler)(ia, icbuf, len);
165	}
166}
167