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busybox/networking/udhcp/dhcpc.c

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/* dhcpc.c
*
* udhcp DHCP client
*
* Russ Dill <Russ.Dill@asu.edu> July 2001
*
* Licensed under the GPL v2 or later, see the file LICENSE in this tarball.
*/
#include <sys/time.h>
#include <sys/file.h>
#include <unistd.h>
#include <getopt.h>
#include <stdlib.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <signal.h>
#include <time.h>
#include <string.h>
#include <sys/ioctl.h>
#include <net/if.h>
#include <errno.h>
#include "common.h"
#include "dhcpd.h"
#include "dhcpc.h"
#include "options.h"
#include "clientpacket.h"
#include "clientsocket.h"
#include "script.h"
#include "socket.h"
#include "signalpipe.h"
static int state;
static unsigned long requested_ip; /* = 0 */
static unsigned long server_addr;
static unsigned long timeout;
static int packet_num; /* = 0 */
static int fd = -1;
#define LISTEN_NONE 0
#define LISTEN_KERNEL 1
#define LISTEN_RAW 2
static int listen_mode;
struct client_config_t client_config = {
/* Default options. */
.abort_if_no_lease = 0,
.foreground = 0,
.quit_after_lease = 0,
.background_if_no_lease = 0,
.interface = "eth0",
.pidfile = NULL,
.script = DEFAULT_SCRIPT,
.clientid = NULL,
.vendorclass = NULL,
.hostname = NULL,
.fqdn = NULL,
.ifindex = 0,
.retries = 3,
.arp = "\0\0\0\0\0\0", /* appease gcc-3.0 */
};
#ifndef IN_BUSYBOX
static void ATTRIBUTE_NORETURN show_usage(void)
{
printf(
"Usage: udhcpc [OPTIONS]\n\n"
" -c, --clientid=CLIENTID Set client identifier - type is first char\n"
" -C, --clientid-none Suppress default client identifier\n"
" -V, --vendorclass=CLASSID Set vendor class identifier\n"
" -H, --hostname=HOSTNAME Client hostname\n"
" -h Alias for -H\n"
" -F, --fqdn=FQDN Client fully qualified domain name\n"
" -f, --foreground Do not fork after getting lease\n"
" -b, --background Fork to background if lease cannot be\n"
" immediately negotiated.\n"
" -i, --interface=INTERFACE Interface to use (default: eth0)\n"
" -n, --now Exit with failure if lease cannot be\n"
" immediately negotiated.\n"
" -p, --pidfile=file Store process ID of daemon in file\n"
" -q, --quit Quit after obtaining lease\n"
" -r, --request=IP IP address to request (default: none)\n"
" -s, --script=file Run file at dhcp events (default:\n"
" " DEFAULT_SCRIPT ")\n"
" -v, --version Display version\n"
);
exit(0);
}
#else
#define show_usage bb_show_usage
extern void show_usage(void) ATTRIBUTE_NORETURN;
#endif
/* just a little helper */
static void change_mode(int new_mode)
{
DEBUG(LOG_INFO, "entering %s listen mode",
new_mode ? (new_mode == 1 ? "kernel" : "raw") : "none");
if (fd >= 0) close(fd);
fd = -1;
listen_mode = new_mode;
}
/* perform a renew */
static void perform_renew(void)
{
LOG(LOG_INFO, "Performing a DHCP renew");
switch (state) {
case BOUND:
change_mode(LISTEN_KERNEL);
case RENEWING:
case REBINDING:
state = RENEW_REQUESTED;
break;
case RENEW_REQUESTED: /* impatient are we? fine, square 1 */
run_script(NULL, "deconfig");
case REQUESTING:
case RELEASED:
change_mode(LISTEN_RAW);
state = INIT_SELECTING;
break;
case INIT_SELECTING:
break;
}
/* start things over */
packet_num = 0;
/* Kill any timeouts because the user wants this to hurry along */
timeout = 0;
}
/* perform a release */
static void perform_release(void)
{
char buffer[16];
struct in_addr temp_addr;
/* send release packet */
if (state == BOUND || state == RENEWING || state == REBINDING) {
temp_addr.s_addr = server_addr;
sprintf(buffer, "%s", inet_ntoa(temp_addr));
temp_addr.s_addr = requested_ip;
LOG(LOG_INFO, "Unicasting a release of %s to %s",
inet_ntoa(temp_addr), buffer);
send_release(server_addr, requested_ip); /* unicast */
run_script(NULL, "deconfig");
}
LOG(LOG_INFO, "Entering released state");
change_mode(LISTEN_NONE);
state = RELEASED;
timeout = 0x7fffffff;
}
static void client_background(void)
{
background(client_config.pidfile);
client_config.foreground = 1; /* Do not fork again. */
client_config.background_if_no_lease = 0;
}
#ifdef COMBINED_BINARY
int udhcpc_main(int argc, char *argv[])
#else
int main(int argc, char *argv[])
#endif
{
uint8_t *temp, *message;
unsigned long t1 = 0, t2 = 0, xid = 0;
unsigned long start = 0, lease;
fd_set rfds;
int retval;
struct timeval tv;
int c, len;
struct dhcpMessage packet;
struct in_addr temp_addr;
long now;
int max_fd;
int sig;
int no_clientid = 0;
static const struct option arg_options[] = {
{"clientid", required_argument, 0, 'c'},
{"clientid-none", no_argument, 0, 'C'},
{"vendorclass", required_argument, 0, 'V'},
{"foreground", no_argument, 0, 'f'},
{"background", no_argument, 0, 'b'},
{"hostname", required_argument, 0, 'H'},
{"hostname", required_argument, 0, 'h'},
{"fqdn", required_argument, 0, 'F'},
{"interface", required_argument, 0, 'i'},
{"now", no_argument, 0, 'n'},
{"pidfile", required_argument, 0, 'p'},
{"quit", no_argument, 0, 'q'},
{"request", required_argument, 0, 'r'},
{"script", required_argument, 0, 's'},
{"version", no_argument, 0, 'v'},
{"retries", required_argument, 0, 't'},
{0, 0, 0, 0}
};
/* get options */
while (1) {
int option_index = 0;
c = getopt_long(argc, argv, "c:CV:fbH:h:F:i:np:qr:s:t:v", arg_options, &option_index);
if (c == -1) break;
switch (c) {
case 'c':
if (no_clientid) show_usage();
len = strlen(optarg) > 255 ? 255 : strlen(optarg);
if (client_config.clientid) free(client_config.clientid);
client_config.clientid = xmalloc(len + 2);
client_config.clientid[OPT_CODE] = DHCP_CLIENT_ID;
client_config.clientid[OPT_LEN] = len;
client_config.clientid[OPT_DATA] = '\0';
strncpy((char*)client_config.clientid + OPT_DATA, optarg, len);
break;
case 'C':
if (client_config.clientid) show_usage();
no_clientid = 1;
break;
case 'V':
len = strlen(optarg) > 255 ? 255 : strlen(optarg);
if (client_config.vendorclass) free(client_config.vendorclass);
client_config.vendorclass = xmalloc(len + 2);
client_config.vendorclass[OPT_CODE] = DHCP_VENDOR;
client_config.vendorclass[OPT_LEN] = len;
strncpy((char*)client_config.vendorclass + OPT_DATA, optarg, len);
break;
case 'f':
client_config.foreground = 1;
break;
case 'b':
client_config.background_if_no_lease = 1;
break;
case 'h':
case 'H':
len = strlen(optarg) > 255 ? 255 : strlen(optarg);
if (client_config.hostname) free(client_config.hostname);
client_config.hostname = xmalloc(len + 2);
client_config.hostname[OPT_CODE] = DHCP_HOST_NAME;
client_config.hostname[OPT_LEN] = len;
strncpy((char*)client_config.hostname + 2, optarg, len);
break;
case 'F':
len = strlen(optarg) > 255 ? 255 : strlen(optarg);
if (client_config.fqdn) free(client_config.fqdn);
client_config.fqdn = xmalloc(len + 5);
client_config.fqdn[OPT_CODE] = DHCP_FQDN;
client_config.fqdn[OPT_LEN] = len + 3;
/* Flags: 0000NEOS
S: 1 => Client requests Server to update A RR in DNS as well as PTR
O: 1 => Server indicates to client that DNS has been updated regardless
E: 1 => Name data is DNS format, i.e. <4>host<6>domain<4>com<0> not "host.domain.com"
N: 1 => Client requests Server to not update DNS
*/
client_config.fqdn[OPT_LEN + 1] = 0x1;
client_config.fqdn[OPT_LEN + 2] = 0;
client_config.fqdn[OPT_LEN + 3] = 0;
strncpy((char*)client_config.fqdn + 5, optarg, len);
break;
case 'i':
client_config.interface = optarg;
break;
case 'n':
client_config.abort_if_no_lease = 1;
break;
case 'p':
client_config.pidfile = optarg;
break;
case 'q':
client_config.quit_after_lease = 1;
break;
case 'r':
requested_ip = inet_addr(optarg);
break;
case 's':
client_config.script = optarg;
break;
case 't':
client_config.retries = atoi(optarg);
break;
case 'v':
printf("udhcpcd, version %s\n\n", VERSION);
return 0;
break;
default:
show_usage();
}
}
/* Start the log, sanitize fd's, and write a pid file */
start_log_and_pid("udhcpc", client_config.pidfile);
if (read_interface(client_config.interface, &client_config.ifindex,
NULL, client_config.arp) < 0)
return 1;
/* if not set, and not suppressed, setup the default client ID */
if (!client_config.clientid && !no_clientid) {
client_config.clientid = xmalloc(6 + 3);
client_config.clientid[OPT_CODE] = DHCP_CLIENT_ID;
client_config.clientid[OPT_LEN] = 7;
client_config.clientid[OPT_DATA] = 1;
memcpy(client_config.clientid + 3, client_config.arp, 6);
}
if (!client_config.vendorclass) {
client_config.vendorclass = xmalloc(sizeof("udhcp "VERSION) + 2);
client_config.vendorclass[OPT_CODE] = DHCP_VENDOR;
client_config.vendorclass[OPT_LEN] = sizeof("udhcp "VERSION) - 1;
client_config.vendorclass[OPT_DATA] = 1;
memcpy(&client_config.vendorclass[OPT_DATA],
"udhcp "VERSION, sizeof("udhcp "VERSION) - 1);
}
/* setup the signal pipe */
udhcp_sp_setup();
state = INIT_SELECTING;
run_script(NULL, "deconfig");
change_mode(LISTEN_RAW);
for (;;) {
tv.tv_sec = timeout - uptime();
tv.tv_usec = 0;
if (listen_mode != LISTEN_NONE && fd < 0) {
if (listen_mode == LISTEN_KERNEL)
fd = listen_socket(INADDR_ANY, CLIENT_PORT, client_config.interface);
else
fd = raw_socket(client_config.ifindex);
if (fd < 0) {
LOG(LOG_ERR, "FATAL: couldn't listen on socket, %m");
return 0;
}
}
max_fd = udhcp_sp_fd_set(&rfds, fd);
if (tv.tv_sec > 0) {
DEBUG(LOG_INFO, "Waiting on select...");
retval = select(max_fd + 1, &rfds, NULL, NULL, &tv);
} else retval = 0; /* If we already timed out, fall through */
now = uptime();
if (retval == 0) {
/* timeout dropped to zero */
switch (state) {
case INIT_SELECTING:
if (packet_num < client_config.retries) {
if (packet_num == 0)
xid = random_xid();
/* send discover packet */
send_discover(xid, requested_ip); /* broadcast */
timeout = now + ((packet_num == 2) ? 4 : 2);
packet_num++;
} else {
run_script(NULL, "leasefail");
if (client_config.background_if_no_lease) {
LOG(LOG_INFO, "No lease, forking to background.");
client_background();
} else if (client_config.abort_if_no_lease) {
LOG(LOG_INFO, "No lease, failing.");
return 1;
}
/* wait to try again */
packet_num = 0;
timeout = now + 60;
}
break;
case RENEW_REQUESTED:
case REQUESTING:
if (packet_num < client_config.retries) {
/* send request packet */
if (state == RENEW_REQUESTED)
send_renew(xid, server_addr, requested_ip); /* unicast */
else send_selecting(xid, server_addr, requested_ip); /* broadcast */
timeout = now + ((packet_num == 2) ? 10 : 2);
packet_num++;
} else {
/* timed out, go back to init state */
if (state == RENEW_REQUESTED) run_script(NULL, "deconfig");
state = INIT_SELECTING;
timeout = now;
packet_num = 0;
change_mode(LISTEN_RAW);
}
break;
case BOUND:
/* Lease is starting to run out, time to enter renewing state */
state = RENEWING;
change_mode(LISTEN_KERNEL);
DEBUG(LOG_INFO, "Entering renew state");
/* fall right through */
case RENEWING:
/* Either set a new T1, or enter REBINDING state */
if ((t2 - t1) <= (lease / 14400 + 1)) {
/* timed out, enter rebinding state */
state = REBINDING;
timeout = now + (t2 - t1);
DEBUG(LOG_INFO, "Entering rebinding state");
} else {
/* send a request packet */
send_renew(xid, server_addr, requested_ip); /* unicast */
t1 = (t2 - t1) / 2 + t1;
timeout = t1 + start;
}
break;
case REBINDING:
/* Either set a new T2, or enter INIT state */
if ((lease - t2) <= (lease / 14400 + 1)) {
/* timed out, enter init state */
state = INIT_SELECTING;
LOG(LOG_INFO, "Lease lost, entering init state");
run_script(NULL, "deconfig");
timeout = now;
packet_num = 0;
change_mode(LISTEN_RAW);
} else {
/* send a request packet */
send_renew(xid, 0, requested_ip); /* broadcast */
t2 = (lease - t2) / 2 + t2;
timeout = t2 + start;
}
break;
case RELEASED:
/* yah, I know, *you* say it would never happen */
timeout = 0x7fffffff;
break;
}
} else if (retval > 0 && listen_mode != LISTEN_NONE && FD_ISSET(fd, &rfds)) {
/* a packet is ready, read it */
if (listen_mode == LISTEN_KERNEL)
len = get_packet(&packet, fd);
else len = get_raw_packet(&packet, fd);
if (len == -1 && errno != EINTR) {
DEBUG(LOG_INFO, "error on read, %m, reopening socket");
change_mode(listen_mode); /* just close and reopen */
}
if (len < 0) continue;
if (packet.xid != xid) {
DEBUG(LOG_INFO, "Ignoring XID %lx (our xid is %lx)",
(unsigned long) packet.xid, xid);
continue;
}
/* Ignore packets that aren't for us */
if (memcmp(packet.chaddr, client_config.arp, 6)) {
DEBUG(LOG_INFO, "packet does not have our chaddr -- ignoring");
continue;
}
if ((message = get_option(&packet, DHCP_MESSAGE_TYPE)) == NULL) {
DEBUG(LOG_ERR, "couldnt get option from packet -- ignoring");
continue;
}
switch (state) {
case INIT_SELECTING:
/* Must be a DHCPOFFER to one of our xid's */
if (*message == DHCPOFFER) {
if ((temp = get_option(&packet, DHCP_SERVER_ID))) {
memcpy(&server_addr, temp, 4);
xid = packet.xid;
requested_ip = packet.yiaddr;
/* enter requesting state */
state = REQUESTING;
timeout = now;
packet_num = 0;
} else {
DEBUG(LOG_ERR, "No server ID in message");
}
}
break;
case RENEW_REQUESTED:
case REQUESTING:
case RENEWING:
case REBINDING:
if (*message == DHCPACK) {
if (!(temp = get_option(&packet, DHCP_LEASE_TIME))) {
LOG(LOG_ERR, "No lease time with ACK, using 1 hour lease");
lease = 60 * 60;
} else {
memcpy(&lease, temp, 4);
lease = ntohl(lease);
}
/* enter bound state */
t1 = lease / 2;
/* little fixed point for n * .875 */
t2 = (lease * 0x7) >> 3;
temp_addr.s_addr = packet.yiaddr;
LOG(LOG_INFO, "Lease of %s obtained, lease time %ld",
inet_ntoa(temp_addr), lease);
start = now;
timeout = t1 + start;
requested_ip = packet.yiaddr;
run_script(&packet,
((state == RENEWING || state == REBINDING) ? "renew" : "bound"));
state = BOUND;
change_mode(LISTEN_NONE);
if (client_config.quit_after_lease)
return 0;
if (!client_config.foreground)
client_background();
} else if (*message == DHCPNAK) {
/* return to init state */
LOG(LOG_INFO, "Received DHCP NAK");
run_script(&packet, "nak");
if (state != REQUESTING)
run_script(NULL, "deconfig");
state = INIT_SELECTING;
timeout = now;
requested_ip = 0;
packet_num = 0;
change_mode(LISTEN_RAW);
sleep(3); /* avoid excessive network traffic */
}
break;
/* case BOUND, RELEASED: - ignore all packets */
}
} else if (retval > 0 && (sig = udhcp_sp_read(&rfds))) {
switch (sig) {
case SIGUSR1:
perform_renew();
break;
case SIGUSR2:
perform_release();
break;
case SIGTERM:
LOG(LOG_INFO, "Received SIGTERM");
return 0;
}
} else if (retval == -1 && errno == EINTR) {
/* a signal was caught */
} else {
/* An error occured */
DEBUG(LOG_ERR, "Error on select");
}
}
return 0;
}
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