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/* $OpenBSD: dhcpd.c,v 1.22 2004/10/31 10:43:38 canacar Exp $ */
/*
* Copyright (c) 2004 Henning Brauer <henning@cvs.openbsd.org>
* Copyright (c) 1995, 1996, 1997, 1998, 1999
* The Internet Software Consortium. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of The Internet Software Consortium nor the names
* of its contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE INTERNET SOFTWARE CONSORTIUM AND
* CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE INTERNET SOFTWARE CONSORTIUM OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* This software has been written for the Internet Software Consortium
* by Ted Lemon <mellon@fugue.com> in cooperation with Vixie
* Enterprises. To learn more about the Internet Software Consortium,
* see ``http://www.vix.com/isc''. To learn more about Vixie
* Enterprises, see ``http://www.vix.com''.
*/
#include "dhcpd.h"
#include "pwd.h"
void usage(void);
time_t cur_time;
struct group root_group;
u_int16_t server_port;
u_int16_t client_port;
int log_priority;
int log_perror = 0;
char *path_dhcpd_conf = _PATH_DHCPD_CONF;
char *path_dhcpd_db = _PATH_DHCPD_DB;
int
main(int argc, char *argv[])
{
int ch, cftest = 0, daemonize = 1;
struct passwd *pw;
extern char *__progname;
/* Initially, log errors to stderr as well as to syslogd. */
openlog(__progname, LOG_NDELAY, DHCPD_LOG_FACILITY);
setlogmask(LOG_UPTO(LOG_INFO));
while ((ch = getopt(argc, argv, "c:dfl:nq")) != -1)
switch (ch) {
case 'c':
path_dhcpd_conf = optarg;
break;
case 'd':
daemonize = 0;
log_perror = -1;
break;
case 'f':
daemonize = 0;
break;
case 'l':
path_dhcpd_db = optarg;
break;
case 'n':
daemonize = 0;
cftest = 1;
log_perror = -1;
break;
case 'q':
break;
default:
usage();
}
argc -= optind;
argv += optind;
while (argc > 0) {
struct interface_info *tmp = calloc(1, sizeof(*tmp));
if (!tmp)
error("calloc");
strlcpy(tmp->name, argv[0], sizeof(tmp->name));
tmp->next = interfaces;
tmp->flags = INTERFACE_REQUESTED;
interfaces = tmp;
argc--;
argv++;
}
/* Default DHCP/BOOTP ports. */
server_port = htons(SERVER_PORT);
client_port = htons(CLIENT_PORT);
tzset();
time(&cur_time);
if (!readconf())
error("Configuration file errors encountered");
if (cftest)
exit(0);
db_startup();
discover_interfaces(DISCOVER_SERVER);
icmp_startup(1, lease_pinged);
if ((pw = getpwnam("_dhcp")) == NULL)
error("user \"_dhcp\" not found");
if (daemonize)
daemon(0, 0);
if (chroot(_PATH_VAREMPTY) == -1)
error("chroot %s: %m", _PATH_VAREMPTY);
if (chdir("/") == -1)
error("chdir(\"/\"): %m");
if (setgroups(1, &pw->pw_gid) ||
setegid(pw->pw_gid) || setgid(pw->pw_gid) ||
seteuid(pw->pw_uid) || setuid(pw->pw_uid))
error("can't drop privileges: %m");
endpwent();
bootp_packet_handler = do_packet;
dispatch();
/* not reached */
exit(0);
}
void
usage(void)
{
extern char *__progname;
fprintf(stderr, "usage: %s [-dfn] [-c config-file] [-l lease-file]",
__progname);
fprintf(stderr, " [if0 [...ifN]]\n");
exit(1);
}
void
lease_pinged(struct iaddr from, u_int8_t *packet, int length)
{
struct lease *lp;
/*
* Don't try to look up a pinged lease if we aren't trying to
* ping one - otherwise somebody could easily make us churn by
* just forging repeated ICMP EchoReply packets for us to look
* up.
*/
if (!outstanding_pings)
return;
lp = find_lease_by_ip_addr(from);
if (!lp) {
note("unexpected ICMP Echo Reply from %s", piaddr(from));
return;
}
if (!lp->state && !lp->releasing) {
warning("ICMP Echo Reply for %s arrived late or is spurious.",
piaddr(from));
return;
}
/* At this point it looks like we pinged a lease and got a
* response, which shouldn't have happened.
* if it did it's either one of two two cases:
* 1 - we pinged this lease before offering it and
* something answered, so we abandon it.
* 2 - we pinged this lease before releasing it
* and something answered, so we don't release it.
*/
if (lp->releasing) {
warning("IP address %s answers a ping after sending a release",
piaddr(lp->ip_addr));
warning("Possible release spoof - Not releasing address %s",
piaddr(lp->ip_addr));
lp->releasing = 0;
} else {
free_lease_state(lp->state, "lease_pinged");
lp->state = NULL;
abandon_lease(lp, "pinged before offer");
}
cancel_timeout(lease_ping_timeout, lp);
--outstanding_pings;
}
void
lease_ping_timeout(void *vlp)
{
struct lease *lp = vlp;
--outstanding_pings;
if (lp->releasing) {
lp->releasing = 0;
release_lease(lp);
} else
dhcp_reply(lp);
}
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