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/* vi: set sw=4 ts=4: */
/* dhcpd.c
*
* udhcp Server
* Copyright (C) 1999 Matthew Ramsay <matthewr@moreton.com.au>
* Chris Trew <ctrew@moreton.com.au>
*
* Rewrite by Russ Dill <Russ.Dill@asu.edu> July 2001
*
* Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
*/
#include <syslog.h>
#include "common.h"
#include "dhcpd.h"
#include "options.h"
/* globals */
struct dhcpOfferedAddr *leases;
struct server_config_t server_config;
int udhcpd_main(int argc, char **argv);
int udhcpd_main(int argc, char **argv)
{
fd_set rfds;
struct timeval tv;
int server_socket = -1, bytes, retval, max_sock;
struct dhcpMessage packet;
uint8_t *state, *server_id, *requested;
uint32_t server_id_align, requested_align, static_lease_ip;
unsigned timeout_end;
unsigned num_ips;
struct option_set *option;
struct dhcpOfferedAddr *lease, static_lease;
//Huh, dhcpd don't have --foreground, --syslog options?? TODO
if (!ENABLE_FEATURE_UDHCP_DEBUG) {
bb_daemonize_or_rexec(0, argv);
logmode &= ~LOGMODE_STDIO;
}
if (ENABLE_FEATURE_UDHCP_SYSLOG) {
openlog(applet_name, LOG_PID, LOG_LOCAL0);
logmode |= LOGMODE_SYSLOG;
}
/* Would rather not do read_config before daemonization -
* otherwise NOMMU machines will parse config twice */
read_config(argv[1] ? argv[1] : DHCPD_CONF_FILE);
udhcp_make_pidfile(server_config.pidfile);
option = find_option(server_config.options, DHCP_LEASE_TIME);
server_config.lease = LEASE_TIME;
if (option) {
memcpy(&server_config.lease, option->data + 2, 4);
server_config.lease = ntohl(server_config.lease);
}
/* Sanity check */
num_ips = server_config.end_ip - server_config.start_ip + 1;
if (server_config.max_leases > num_ips) {
bb_error_msg("max_leases=%u is too big, setting to %u",
(unsigned)server_config.max_leases, num_ips);
server_config.max_leases = num_ips;
}
leases = xzalloc(server_config.max_leases * sizeof(*leases));
read_leases(server_config.lease_file);
if (read_interface(server_config.interface, &server_config.ifindex,
&server_config.server, server_config.arp) < 0) {
retval = 1;
goto ret;
}
/* Setup the signal pipe */
udhcp_sp_setup();
timeout_end = monotonic_sec() + server_config.auto_time;
while (1) { /* loop until universe collapses */
if (server_socket < 0) {
server_socket = listen_socket(INADDR_ANY, SERVER_PORT,
server_config.interface);
}
max_sock = udhcp_sp_fd_set(&rfds, server_socket);
if (server_config.auto_time) {
tv.tv_sec = timeout_end - monotonic_sec();
tv.tv_usec = 0;
}
retval = 0;
if (!server_config.auto_time || tv.tv_sec > 0) {
retval = select(max_sock + 1, &rfds, NULL, NULL,
server_config.auto_time ? &tv : NULL);
}
if (retval == 0) {
write_leases();
timeout_end = monotonic_sec() + server_config.auto_time;
continue;
}
if (retval < 0 && errno != EINTR) {
DEBUG("error on select");
continue;
}
switch (udhcp_sp_read(&rfds)) {
case SIGUSR1:
bb_info_msg("Received a SIGUSR1");
write_leases();
/* why not just reset the timeout, eh */
timeout_end = monotonic_sec() + server_config.auto_time;
continue;
case SIGTERM:
bb_info_msg("Received a SIGTERM");
goto ret0;
case 0: break; /* no signal */
default: continue; /* signal or error (probably EINTR) */
}
bytes = udhcp_get_packet(&packet, server_socket); /* this waits for a packet - idle */
if (bytes < 0) {
if (bytes == -1 && errno != EINTR) {
DEBUG("error on read, %s, reopening socket", strerror(errno));
close(server_socket);
server_socket = -1;
}
continue;
}
state = get_option(&packet, DHCP_MESSAGE_TYPE);
if (state == NULL) {
bb_error_msg("cannot get option from packet, ignoring");
continue;
}
/* Look for a static lease */
static_lease_ip = getIpByMac(server_config.static_leases, &packet.chaddr);
if (static_lease_ip) {
bb_info_msg("Found static lease: %x", static_lease_ip);
memcpy(&static_lease.chaddr, &packet.chaddr, 16);
static_lease.yiaddr = static_lease_ip;
static_lease.expires = 0;
lease = &static_lease;
} else {
lease = find_lease_by_chaddr(packet.chaddr);
}
switch (state[0]) {
case DHCPDISCOVER:
DEBUG("Received DISCOVER");
if (sendOffer(&packet) < 0) {
bb_error_msg("send OFFER failed");
}
break;
case DHCPREQUEST:
DEBUG("received REQUEST");
requested = get_option(&packet, DHCP_REQUESTED_IP);
server_id = get_option(&packet, DHCP_SERVER_ID);
if (requested) memcpy(&requested_align, requested, 4);
if (server_id) memcpy(&server_id_align, server_id, 4);
if (lease) {
if (server_id) {
/* SELECTING State */
DEBUG("server_id = %08x", ntohl(server_id_align));
if (server_id_align == server_config.server && requested
&& requested_align == lease->yiaddr
) {
sendACK(&packet, lease->yiaddr);
}
} else if (requested) {
/* INIT-REBOOT State */
if (lease->yiaddr == requested_align)
sendACK(&packet, lease->yiaddr);
else
sendNAK(&packet);
} else if (lease->yiaddr == packet.ciaddr) {
/* RENEWING or REBINDING State */
sendACK(&packet, lease->yiaddr);
} else {
/* don't know what to do!!!! */
sendNAK(&packet);
}
/* what to do if we have no record of the client */
} else if (server_id) {
/* SELECTING State */
} else if (requested) {
/* INIT-REBOOT State */
lease = find_lease_by_yiaddr(requested_align);
if (lease) {
if (lease_expired(lease)) {
/* probably best if we drop this lease */
memset(lease->chaddr, 0, 16);
/* make some contention for this address */
} else
sendNAK(&packet);
} else {
uint32_t r = ntohl(requested_align);
if (r < server_config.start_ip
|| r > server_config.end_ip
) {
sendNAK(&packet);
}
/* else remain silent */
}
} else {
/* RENEWING or REBINDING State */
}
break;
case DHCPDECLINE:
DEBUG("Received DECLINE");
if (lease) {
memset(lease->chaddr, 0, 16);
lease->expires = time(0) + server_config.decline_time;
}
break;
case DHCPRELEASE:
DEBUG("Received RELEASE");
if (lease)
lease->expires = time(0);
break;
case DHCPINFORM:
DEBUG("Received INFORM");
send_inform(&packet);
break;
default:
bb_info_msg("Unsupported DHCP message (%02x) - ignoring", state[0]);
}
}
ret0:
retval = 0;
ret:
/*if (server_config.pidfile) - server_config.pidfile is never NULL */
remove_pidfile(server_config.pidfile);
return retval;
}
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