OpenBSD-4.6/usr.sbin/dhcrelay/dhcrelay.c
/* $OpenBSD: dhcrelay.c,v 1.31 2008/07/09 20:08:13 sobrado Exp $ */
/*
* Copyright (c) 2004 Henning Brauer <henning@cvs.openbsd.org>
* Copyright (c) 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"
void usage(void);
void relay(struct interface_info *, struct dhcp_packet *, int,
unsigned int, struct iaddr, struct hardware *);
char *print_hw_addr(int, int, unsigned char *);
void got_response(struct protocol *);
time_t cur_time;
int log_perror = 1;
u_int16_t server_port;
u_int16_t client_port;
int log_priority;
struct interface_info *interfaces = NULL;
struct server_list {
struct server_list *next;
struct sockaddr_in to;
int fd;
} *servers;
int
main(int argc, char *argv[])
{
int ch, no_daemon = 0, opt;
extern char *__progname;
struct server_list *sp = NULL;
struct passwd *pw;
struct sockaddr_in laddr;
/* 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, "di:")) != -1) {
switch (ch) {
case 'd':
no_daemon = 1;
break;
case 'i':
if (interfaces != NULL)
usage();
if ((interfaces = calloc(1,
sizeof(struct interface_info))) == NULL)
error("calloc");
strlcpy(interfaces->name, optarg,
sizeof(interfaces->name));
break;
default:
usage();
/* not reached */
}
}
argc -= optind;
argv += optind;
if (argc < 1)
usage();
while (argc > 0) {
struct hostent *he;
struct in_addr ia, *iap = NULL;
if (inet_aton(argv[0], &ia))
iap = &ia;
else {
he = gethostbyname(argv[0]);
if (!he)
warning("%s: host unknown", argv[0]);
else
iap = ((struct in_addr *)he->h_addr_list[0]);
}
if (iap) {
if ((sp = calloc(1, sizeof *sp)) == NULL)
error("calloc");
sp->next = servers;
servers = sp;
memcpy(&sp->to.sin_addr, iap, sizeof *iap);
}
argc--;
argv++;
}
log_perror = 0;
if (interfaces == NULL)
error("no interface given");
/* Default DHCP/BOOTP ports. */
server_port = htons(SERVER_PORT);
client_port = htons(CLIENT_PORT);
/* We need at least one server. */
if (!sp)
usage();
discover_interfaces(interfaces);
bzero(&laddr, sizeof laddr);
laddr.sin_len = sizeof laddr;
laddr.sin_family = AF_INET;
laddr.sin_port = server_port;
laddr.sin_addr.s_addr = interfaces->primary_address.s_addr;
/* Set up the server sockaddrs. */
for (sp = servers; sp; sp = sp->next) {
sp->to.sin_port = server_port;
sp->to.sin_family = AF_INET;
sp->to.sin_len = sizeof sp->to;
sp->fd = socket(AF_INET, SOCK_DGRAM, 0);
if (sp->fd == -1)
error("socket: %m");
opt = 1;
if (setsockopt(sp->fd, SOL_SOCKET, SO_REUSEPORT,
&opt, sizeof(opt)) == -1)
error("setsockopt: %m");
if (bind(sp->fd, (struct sockaddr *)&laddr, sizeof laddr) == -1)
error("bind: %m");
if (connect(sp->fd, (struct sockaddr *)&sp->to,
sizeof sp->to) == -1)
error("connect: %m");
add_protocol("server", sp->fd, got_response, sp);
}
tzset();
time(&cur_time);
bootp_packet_handler = relay;
if (!no_daemon)
daemon(0, 0);
if ((pw = getpwnam("_dhcp")) == NULL)
error("user \"_dhcp\" not found");
if (chroot(_PATH_VAREMPTY) == -1)
error("chroot: %m");
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");
dispatch();
/* not reached */
exit(0);
}
void
relay(struct interface_info *ip, struct dhcp_packet *packet, int length,
unsigned int from_port, struct iaddr from, struct hardware *hfrom)
{
struct server_list *sp;
struct sockaddr_in to;
struct hardware hto;
if (packet->hlen > sizeof packet->chaddr) {
note("Discarding packet with invalid hlen.");
return;
}
/* If it's a bootreply, forward it to the client. */
if (packet->op == BOOTREPLY) {
bzero(&to, sizeof(to));
if (!(packet->flags & htons(BOOTP_BROADCAST))) {
to.sin_addr = packet->yiaddr;
to.sin_port = client_port;
} else {
to.sin_addr.s_addr = htonl(INADDR_BROADCAST);
to.sin_port = client_port;
}
to.sin_family = AF_INET;
to.sin_len = sizeof to;
/* Set up the hardware destination address. */
hto.hlen = packet->hlen;
if (hto.hlen > sizeof hto.haddr)
hto.hlen = sizeof hto.haddr;
memcpy(hto.haddr, packet->chaddr, hto.hlen);
hto.htype = packet->htype;
if (send_packet(interfaces, packet, length,
interfaces->primary_address, &to, &hto) != -1)
debug("forwarded BOOTREPLY for %s to %s",
print_hw_addr(packet->htype, packet->hlen,
packet->chaddr), inet_ntoa(to.sin_addr));
return;
}
if (ip == NULL) {
note("ignoring non BOOTREPLY from server");
return;
}
/* If giaddr is set on a BOOTREQUEST, ignore it - it's already
been gatewayed. */
if (packet->giaddr.s_addr) {
note("ignoring BOOTREQUEST with giaddr of %s",
inet_ntoa(packet->giaddr));
return;
}
/* Set the giaddr so the server can figure out what net it's
from and so that we can later forward the response to the
correct net. */
packet->giaddr = ip->primary_address;
/* Otherwise, it's a BOOTREQUEST, so forward it to all the
servers. */
for (sp = servers; sp; sp = sp->next) {
if (send(sp->fd, packet, length, 0) != -1) {
debug("forwarded BOOTREQUEST for %s to %s",
print_hw_addr(packet->htype, packet->hlen,
packet->chaddr), inet_ntoa(sp->to.sin_addr));
}
}
}
void
usage(void)
{
extern char *__progname;
fprintf(stderr, "usage: %s [-d] -i interface server1 [... serverN]\n",
__progname);
exit(1);
}
char *
print_hw_addr(int htype, int hlen, unsigned char *data)
{
static char habuf[49];
char *s = habuf;
int i, j, slen = sizeof(habuf);
if (htype == 0 || hlen == 0) {
bad:
strlcpy(habuf, "<null>", sizeof habuf);
return habuf;
}
for (i = 0; i < hlen; i++) {
j = snprintf(s, slen, "%02x", data[i]);
if (j <= 0 || j >= slen)
goto bad;
j = strlen (s);
s += j;
slen -= (j + 1);
*s++ = ':';
}
*--s = '\0';
return habuf;
}
void
got_response(struct protocol *l)
{
ssize_t result;
struct iaddr ifrom;
union {
/*
* Packet input buffer. Must be as large as largest
* possible MTU.
*/
unsigned char packbuf[4095];
struct dhcp_packet packet;
} u;
struct server_list *sp = l->local;
if ((result = recv(l->fd, u.packbuf, sizeof(u), 0)) == -1 &&
errno != ECONNREFUSED) {
/*
* Ignore ECONNREFUSED as to many dhcp server send a bogus
* icmp unreach for every request.
*/
warning("recv failed for %s: %m",
inet_ntoa(sp->to.sin_addr));
return;
}
if (result == -1 && errno == ECONNREFUSED)
return;
if (result == 0)
return;
if (result < BOOTP_MIN_LEN) {
note("Discarding packet with invalid size.");
return;
}
if (bootp_packet_handler) {
ifrom.len = 4;
memcpy(ifrom.iabuf, &sp->to.sin_addr, ifrom.len);
(*bootp_packet_handler)(NULL, &u.packet, result,
sp->to.sin_port, ifrom, NULL);
}
}