OpenBSD-4.6/usr.sbin/dhcpd/dhcpd.c
/* $OpenBSD: dhcpd.c,v 1.38 2008/05/29 19:02:47 deraadt 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 "sync.h"
#include <err.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;
struct passwd *pw;
int log_priority;
int log_perror = 0;
int pfpipe[2];
int gotpipe = 0;
int syncrecv;
int syncsend;
pid_t pfproc_pid = -1;
char *path_dhcpd_conf = _PATH_DHCPD_CONF;
char *path_dhcpd_db = _PATH_DHCPD_DB;
char *abandoned_tab = NULL;
char *changedmac_tab = NULL;
char *leased_tab = NULL;
struct syslog_data sdata = SYSLOG_DATA_INIT;
int
main(int argc, char *argv[])
{
int ch, cftest = 0, daemonize = 1;
extern char *__progname;
char *sync_iface = NULL;
char *sync_baddr = NULL;
u_short sync_port = 0;
struct servent *ent;
/* Initially, log errors to stderr as well as to syslogd. */
openlog_r(__progname, LOG_PID | LOG_NDELAY, DHCPD_LOG_FACILITY, &sdata);
opterr = 0;
while ((ch = getopt(argc, argv, "Y:y:")) != -1)
switch (ch) {
case 'Y':
syncsend = 1;
break;
case 'y':
syncrecv = 1;
break;
}
if (syncsend || syncrecv) {
if ((ent = getservbyname("dhcpd-sync", "udp")) == NULL)
errx(1, "Can't find service \"dhcpd-sync\" in "
"/etc/services");
sync_port = ntohs(ent->s_port);
}
optreset = optind = opterr = 1;
while ((ch = getopt(argc, argv, "A:C:L:c:dfl:nY:y:")) != -1)
switch (ch) {
case 'A':
abandoned_tab = optarg;
break;
case 'C':
changedmac_tab = optarg;
break;
case 'L':
leased_tab = optarg;
break;
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 'Y':
if (sync_addhost(optarg, sync_port) != 0)
sync_iface = optarg;
syncsend = 1;
break;
case 'y':
sync_baddr = optarg;
syncrecv = 1;
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;
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);
if (syncsend || syncrecv) {
syncfd = sync_init(sync_iface, sync_baddr, sync_port);
if (syncfd == -1)
err(1, "sync init");
}
db_startup();
discover_interfaces();
icmp_startup(1, lease_pinged);
if ((pw = getpwnam("_dhcp")) == NULL)
error("user \"_dhcp\" not found");
if (daemonize)
daemon(0, 0);
/* don't go near /dev/pf unless we actually intend to use it */
if ((abandoned_tab != NULL) ||
(changedmac_tab != NULL) ||
(leased_tab != NULL)){
if (pipe(pfpipe) == -1)
error("pipe (%m)");
switch (pfproc_pid = fork()){
case -1:
error("fork (%m)");
/* NOTREACHED */
exit(1);
case 0:
/* child process. start up table engine */
pftable_handler();
/* NOTREACHED */
exit(1);
default:
gotpipe = 1;
break;
}
}
if (chroot(_PATH_VAREMPTY) == -1)
error("chroot %s: %m", _PATH_VAREMPTY);
if (chdir("/") == -1)
error("chdir(\"/\"): %m");
if (setgroups(1, &pw->pw_gid) ||
setresgid(pw->pw_gid, pw->pw_gid, pw->pw_gid) ||
setresuid(pw->pw_uid, pw->pw_uid, pw->pw_uid))
error("can't drop privileges: %m");
bootp_packet_handler = do_packet;
add_timeout(cur_time + 5, periodic_scan, NULL);
dispatch();
/* not reached */
exit(0);
}
void
usage(void)
{
extern char *__progname;
fprintf(stderr, "usage: %s [-dfn] [-A abandoned_ip_table]", __progname);
fprintf(stderr, " [-C changed_ip_table]\n");
fprintf(stderr, "\t[-c config-file] [-L leased_ip_table]");
fprintf(stderr, " [-l lease-file] [-Y synctarget] [-y synclisten]\n");
fprintf(stderr, "\t[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);
}
/* from memory.c - needed to be able to walk the lease table */
extern struct subnet *subnets;
void
periodic_scan(void *p)
{
time_t x, y;
struct subnet *n;
struct group *g;
struct shared_network *s;
struct lease *l;
/* find the shortest lease this server gives out */
x = MIN(root_group.default_lease_time, root_group.max_lease_time);
for (n = subnets; n; n = n->next_subnet)
for (g = n->group; g; g = g->next)
x = MIN(x, g->default_lease_time);
/* use half of the shortest lease as the scan interval */
y = x / 2;
if (y < 1)
y = 1;
/* walk across all leases to find the exired ones */
for (n = subnets; n; n = n->next_subnet)
for (g = n->group; g; g = g->next)
for (s = g->shared_network; s; s = s->next)
for (l = s->leases; l && l->ends; l = l->next)
if (cur_time >= l->ends){
release_lease(l);
pfmsg('R', l);
}
add_timeout(cur_time + y, periodic_scan, NULL);
}