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busybox/networking/udhcp/dhcpc.c

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/* vi: set sw=4 ts=4: */
/* 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 <getopt.h>
#include <syslog.h>
/* Override ENABLE_FEATURE_PIDFILE - ifupdown needs our pidfile to always exist */
#define WANT_PIDFILE 1
#include "common.h"
#include "dhcpd.h"
#include "dhcpc.h"
#include "options.h"
static int timeout; /* = 0. Must be signed */
static uint32_t requested_ip; /* = 0 */
static uint32_t server_addr;
static int sockfd = -1;
#define LISTEN_NONE 0
#define LISTEN_KERNEL 1
#define LISTEN_RAW 2
static smallint listen_mode;
static smallint state;
/* struct client_config_t client_config is in bb_common_bufsiz1 */
/* just a little helper */
static void change_listen_mode(int new_mode)
{
DEBUG("entering %s listen mode",
new_mode ? (new_mode == 1 ? "kernel" : "raw") : "none");
if (sockfd >= 0) {
close(sockfd);
sockfd = -1;
}
listen_mode = new_mode;
}
/* perform a renew */
static void perform_renew(void)
{
bb_info_msg("Performing a DHCP renew");
switch (state) {
case BOUND:
change_listen_mode(LISTEN_KERNEL);
case RENEWING:
case REBINDING:
state = RENEW_REQUESTED;
break;
case RENEW_REQUESTED: /* impatient are we? fine, square 1 */
udhcp_run_script(NULL, "deconfig");
case REQUESTING:
case RELEASED:
change_listen_mode(LISTEN_RAW);
state = INIT_SELECTING;
break;
case INIT_SELECTING:
break;
}
}
/* perform a release */
static void perform_release(void)
{
char buffer[sizeof("255.255.255.255")];
struct in_addr temp_addr;
/* send release packet */
if (state == BOUND || state == RENEWING || state == REBINDING) {
temp_addr.s_addr = server_addr;
strcpy(buffer, inet_ntoa(temp_addr));
temp_addr.s_addr = requested_ip;
bb_info_msg("Unicasting a release of %s to %s",
inet_ntoa(temp_addr), buffer);
send_release(server_addr, requested_ip); /* unicast */
udhcp_run_script(NULL, "deconfig");
}
bb_info_msg("Entering released state");
change_listen_mode(LISTEN_NONE);
state = RELEASED;
timeout = INT_MAX;
}
static void client_background(void)
{
#if !BB_MMU
bb_error_msg("cannot background in uclinux (yet)");
/* ... mainly because udhcpc calls client_background()
* in _the _middle _of _udhcpc _run_, not at the start!
* If that will be properly disabled for NOMMU, client_background()
* will work on NOMMU too */
#else
bb_daemonize(0);
logmode &= ~LOGMODE_STDIO;
/* rewrite pidfile, as our pid is different now */
write_pidfile(client_config.pidfile);
#endif
/* Do not fork again. */
client_config.foreground = 1;
client_config.background_if_no_lease = 0;
}
static uint8_t* alloc_dhcp_option(int code, const char *str, int extra)
{
uint8_t *storage;
int len = strlen(str);
if (len > 255) len = 255;
storage = xzalloc(len + extra + OPT_DATA);
storage[OPT_CODE] = code;
storage[OPT_LEN] = len + extra;
memcpy(storage + extra + OPT_DATA, str, len);
return storage;
}
int udhcpc_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int udhcpc_main(int argc, char **argv)
{
uint8_t *temp, *message;
char *str_c, *str_V, *str_h, *str_F, *str_r, *str_T, *str_A, *str_t;
USE_FEATURE_UDHCP_PORT(char *str_P;)
llist_t *list_O = NULL;
#if ENABLE_FEATURE_UDHCPC_ARPING
char *str_W;
#endif
int tryagain_timeout = 20;
int discover_timeout = 3;
int discover_retries = 3;
uint32_t xid = 0;
uint32_t lease_seconds = 0; /* can be given as 32-bit quantity */
int packet_num;
/* t1, t2... what a wonderful names... */
unsigned t1 = t1; /* for gcc */
unsigned t2 = t2;
unsigned timestamp_got_lease = timestamp_got_lease;
unsigned opt;
int max_fd;
int retval;
int len;
struct timeval tv;
struct in_addr temp_addr;
struct dhcpMessage packet;
fd_set rfds;
enum {
OPT_c = 1 << 0,
OPT_C = 1 << 1,
OPT_V = 1 << 2,
OPT_f = 1 << 3,
OPT_b = 1 << 4,
OPT_H = 1 << 5,
OPT_h = 1 << 6,
OPT_F = 1 << 7,
OPT_i = 1 << 8,
OPT_n = 1 << 9,
OPT_p = 1 << 10,
OPT_q = 1 << 11,
OPT_R = 1 << 12,
OPT_r = 1 << 13,
OPT_s = 1 << 14,
OPT_T = 1 << 15,
OPT_t = 1 << 16,
OPT_v = 1 << 17,
OPT_S = 1 << 18,
OPT_A = 1 << 19,
#if ENABLE_FEATURE_UDHCPC_ARPING
OPT_a = 1 << 20,
OPT_W = 1 << 21,
#endif
OPT_P = 1 << 22,
};
#if ENABLE_GETOPT_LONG
static const char udhcpc_longopts[] ALIGN1 =
"clientid\0" Required_argument "c"
"clientid-none\0" No_argument "C"
"vendorclass\0" Required_argument "V"
"foreground\0" No_argument "f"
"background\0" No_argument "b"
"hostname\0" Required_argument "H"
"fqdn\0" Required_argument "F"
"interface\0" Required_argument "i"
"now\0" No_argument "n"
"pidfile\0" Required_argument "p"
"quit\0" No_argument "q"
"release\0" No_argument "R"
"request\0" Required_argument "r"
"script\0" Required_argument "s"
"timeout\0" Required_argument "T"
"version\0" No_argument "v"
"retries\0" Required_argument "t"
"tryagain\0" Required_argument "A"
"syslog\0" No_argument "S"
#if ENABLE_FEATURE_UDHCPC_ARPING
"arping\0" No_argument "a"
#endif
"request-option\0" Required_argument "O"
#if ENABLE_FEATURE_UDHCP_PORT
"client-port\0" Required_argument "P"
#endif
;
#endif
/* Default options. */
#if ENABLE_FEATURE_UDHCP_PORT
SERVER_PORT = 67;
CLIENT_PORT = 68;
#endif
client_config.interface = "eth0";
client_config.script = DEFAULT_SCRIPT;
/* Parse command line */
opt_complementary = "c--C:C--c:O::"; // Cc: mutually exclusive; O: list
#if ENABLE_GETOPT_LONG
applet_long_options = udhcpc_longopts;
#endif
opt = getopt32(argv, "c:CV:fbH:h:F:i:np:qRr:s:T:t:vSA:"
USE_FEATURE_UDHCPC_ARPING("aW:")
USE_FEATURE_UDHCP_PORT("P:")
"O:"
, &str_c, &str_V, &str_h, &str_h, &str_F
, &client_config.interface, &client_config.pidfile, &str_r
, &client_config.script, &str_T, &str_t, &str_A
USE_FEATURE_UDHCPC_ARPING(, &str_W)
USE_FEATURE_UDHCP_PORT(, &str_P)
, &list_O
);
if (opt & OPT_c)
client_config.clientid = alloc_dhcp_option(DHCP_CLIENT_ID, str_c, 0);
//if (opt & OPT_C)
if (opt & OPT_V)
client_config.vendorclass = alloc_dhcp_option(DHCP_VENDOR, str_V, 0);
if (opt & OPT_f)
client_config.foreground = 1;
if (opt & OPT_b)
client_config.background_if_no_lease = 1;
if (opt & (OPT_h|OPT_H))
client_config.hostname = alloc_dhcp_option(DHCP_HOST_NAME, str_h, 0);
if (opt & OPT_F) {
client_config.fqdn = alloc_dhcp_option(DHCP_FQDN, str_F, 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_DATA + 0] = 0x1;
/* client_config.fqdn[OPT_DATA + 1] = 0; - redundant */
/* client_config.fqdn[OPT_DATA + 2] = 0; - redundant */
}
// if (opt & OPT_i) client_config.interface = ...
if (opt & OPT_n)
client_config.abort_if_no_lease = 1;
// if (opt & OPT_p) client_config.pidfile = ...
if (opt & OPT_q)
client_config.quit_after_lease = 1;
if (opt & OPT_R)
client_config.release_on_quit = 1;
if (opt & OPT_r)
requested_ip = inet_addr(str_r);
// if (opt & OPT_s) client_config.script = ...
if (opt & OPT_T)
discover_timeout = xatoi_u(str_T);
if (opt & OPT_t)
discover_retries = xatoi_u(str_t);
if (opt & OPT_A)
tryagain_timeout = xatoi_u(str_A);
if (opt & OPT_v) {
puts("version "BB_VER);
return 0;
}
if (opt & OPT_S) {
openlog(applet_name, LOG_PID, LOG_LOCAL0);
logmode |= LOGMODE_SYSLOG;
}
#if ENABLE_FEATURE_UDHCP_PORT
if (opt & OPT_P) {
CLIENT_PORT = xatou16(str_P);
SERVER_PORT = CLIENT_PORT - 1;
}
#endif
while (list_O) {
int n = index_in_strings(dhcp_option_strings, list_O->data);
if (n < 0)
bb_error_msg_and_die("unknown option '%s'", list_O->data);
n = dhcp_options[n].code;
client_config.opt_mask[n >> 3] |= 1 << (n & 7);
list_O = list_O->link;
}
if (read_interface(client_config.interface, &client_config.ifindex,
NULL, client_config.arp))
return 1;
/* Make sure fd 0,1,2 are open */
bb_sanitize_stdio();
/* Equivalent of doing a fflush after every \n */
setlinebuf(stdout);
/* Create pidfile */
write_pidfile(client_config.pidfile);
/* if (!..) bb_perror_msg("cannot create pidfile %s", pidfile); */
/* Goes to stdout and possibly syslog */
bb_info_msg("%s (v"BB_VER") started", applet_name);
/* if not set, and not suppressed, setup the default client ID */
if (!client_config.clientid && !(opt & OPT_C)) {
client_config.clientid = alloc_dhcp_option(DHCP_CLIENT_ID, "", 7);
client_config.clientid[OPT_DATA] = 1;
memcpy(client_config.clientid + OPT_DATA+1, client_config.arp, 6);
}
if (!client_config.vendorclass)
client_config.vendorclass = alloc_dhcp_option(DHCP_VENDOR, "udhcp "BB_VER, 0);
/* setup the signal pipe */
udhcp_sp_setup();
state = INIT_SELECTING;
udhcp_run_script(NULL, "deconfig");
change_listen_mode(LISTEN_RAW);
packet_num = 0;
/* Main event loop. select() waits on signal pipe and possibly
* on sockfd.
* "continue" statements in code below jump to the top of the loop.
*/
for (;;) {
tv.tv_sec = timeout;
tv.tv_usec = 0;
if (listen_mode != LISTEN_NONE && sockfd < 0) {
if (listen_mode == LISTEN_KERNEL)
sockfd = listen_socket(/*INADDR_ANY,*/ CLIENT_PORT, client_config.interface);
else
sockfd = raw_socket(client_config.ifindex);
}
max_fd = udhcp_sp_fd_set(&rfds, sockfd);
retval = 0; /* If we already timed out, fall through, else... */
if (tv.tv_sec > 0) {
DEBUG("Waiting on select...");
retval = select(max_fd + 1, &rfds, NULL, NULL, &tv);
}
if (retval < 0) {
/* EINTR? signal was caught, don't panic */
if (errno != EINTR) {
/* Else: an error occured, panic! */
bb_perror_msg_and_die("select");
}
continue;
}
/* If timeout dropped to zero, time to become active:
* resend discover/renew/whatever
*/
if (retval == 0) {
switch (state) {
case INIT_SELECTING:
if (packet_num < discover_retries) {
if (packet_num == 0)
xid = random_xid();
/* send discover packet */
send_discover(xid, requested_ip); /* broadcast */
timeout = discover_timeout;
packet_num++;
continue;
}
udhcp_run_script(NULL, "leasefail");
if (client_config.background_if_no_lease) {
bb_info_msg("No lease, forking to background");
client_background();
} else if (client_config.abort_if_no_lease) {
bb_info_msg("No lease, failing");
retval = 1;
goto ret;
}
/* wait to try again */
timeout = tryagain_timeout;
packet_num = 0;
continue;
case RENEW_REQUESTED:
case REQUESTING:
if (packet_num < discover_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 = ((packet_num == 2) ? 10 : 2);
packet_num++;
continue;
}
/* timed out, go back to init state */
if (state == RENEW_REQUESTED)
udhcp_run_script(NULL, "deconfig");
change_listen_mode(LISTEN_RAW);
state = INIT_SELECTING;
timeout = 0;
packet_num = 0;
continue;
case BOUND:
/* Lease is starting to run out, time to enter renewing state */
change_listen_mode(LISTEN_KERNEL);
DEBUG("Entering renew state");
state = RENEWING;
/* fall right through */
case RENEWING:
/* Either set a new T1, or enter REBINDING state */
if ((t2 - t1) > (lease_seconds / (4*60*60) + 1)) {
/* send a request packet */
send_renew(xid, server_addr, requested_ip); /* unicast */
t1 += (t2 - t1) / 2;
timeout = t1 - ((int)monotonic_sec() - timestamp_got_lease);
continue;
}
/* Timed out, enter rebinding state */
DEBUG("Entering rebinding state");
state = REBINDING;
timeout = (t2 - t1);
continue;
case REBINDING:
/* Lease is *really* about to run out,
* try to find DHCP server using broadcast */
if ((lease_seconds - t2) > (lease_seconds / (4*60*60) + 1)) {
/* send a request packet */
send_renew(xid, 0, requested_ip); /* broadcast */
t2 += (lease_seconds - t2) / 2;
timeout = t2 - ((int)monotonic_sec() - timestamp_got_lease);
continue;
}
/* Timed out, enter init state */
bb_info_msg("Lease lost, entering init state");
udhcp_run_script(NULL, "deconfig");
change_listen_mode(LISTEN_RAW);
state = INIT_SELECTING;
timeout = 0;
packet_num = 0;
continue;
/* case RELEASED: */
}
/* yah, I know, *you* say it would never happen */
timeout = INT_MAX;
continue; /* back to main loop */
}
/* select() didn't timeout, something did happen. */
/* Is is a packet? */
if (listen_mode != LISTEN_NONE && FD_ISSET(sockfd, &rfds)) {
/* A packet is ready, read it */
if (listen_mode == LISTEN_KERNEL)
len = udhcp_recv_packet(&packet, sockfd);
else
len = get_raw_packet(&packet, sockfd);
if (len == -1) { /* error is severe, reopen socket */
DEBUG("error on read, %s, reopening socket", strerror(errno));
change_listen_mode(listen_mode); /* just close and reopen */
}
if (len < 0) continue;
if (packet.xid != xid) {
DEBUG("Ignoring XID %x (our xid is %x)",
(unsigned)packet.xid, (unsigned)xid);
continue;
}
/* Ignore packets that aren't for us */
if (memcmp(packet.chaddr, client_config.arp, 6)) {
DEBUG("Packet does not have our chaddr - ignoring");
continue;
}
message = get_option(&packet, DHCP_MESSAGE_TYPE);
if (message == NULL) {
bb_error_msg("cannot get message type from packet - ignoring");
continue;
}
switch (state) {
case INIT_SELECTING:
/* Must be a DHCPOFFER to one of our xid's */
if (*message == DHCPOFFER) {
/* TODO: why we don't just fetch server's IP from IP header? */
temp = get_option(&packet, DHCP_SERVER_ID);
if (!temp) {
bb_error_msg("no server ID in message");
continue;
/* still selecting - this server looks bad */
}
/* can be misaligned, thus memcpy */
memcpy(&server_addr, temp, 4);
xid = packet.xid;
requested_ip = packet.yiaddr;
/* enter requesting state */
state = REQUESTING;
timeout = 0;
packet_num = 0;
}
continue;
case RENEW_REQUESTED:
case REQUESTING:
case RENEWING:
case REBINDING:
if (*message == DHCPACK) {
temp = get_option(&packet, DHCP_LEASE_TIME);
if (!temp) {
bb_error_msg("no lease time with ACK, using 1 hour lease");
lease_seconds = 60 * 60;
} else {
/* can be misaligned, thus memcpy */
memcpy(&lease_seconds, temp, 4);
lease_seconds = ntohl(lease_seconds);
}
#if ENABLE_FEATURE_UDHCPC_ARPING
if (opt & OPT_a) {
if (!arpping(packet.yiaddr,
(uint32_t) 0,
client_config.arp,
client_config.interface)
) {
bb_info_msg("offered address is in use "
"(got ARP reply), declining");
send_decline(xid, server_addr, packet.yiaddr);
if (state != REQUESTING)
udhcp_run_script(NULL, "deconfig");
change_listen_mode(LISTEN_RAW);
state = INIT_SELECTING;
requested_ip = 0;
timeout = tryagain_timeout;
packet_num = 0;
continue; /* back to main loop */
}
}
#endif
/* enter bound state */
t1 = lease_seconds / 2;
/* little fixed point for n * .875 */
t2 = (lease_seconds * 7) >> 3;
temp_addr.s_addr = packet.yiaddr;
bb_info_msg("Lease of %s obtained, lease time %u",
inet_ntoa(temp_addr), (unsigned)lease_seconds);
timestamp_got_lease = monotonic_sec();
timeout = t1;
requested_ip = packet.yiaddr;
udhcp_run_script(&packet,
((state == RENEWING || state == REBINDING) ? "renew" : "bound"));
state = BOUND;
change_listen_mode(LISTEN_NONE);
if (client_config.quit_after_lease) {
if (client_config.release_on_quit)
perform_release();
goto ret0;
}
if (!client_config.foreground)
client_background();
continue; /* back to main loop */
}
if (*message == DHCPNAK) {
/* return to init state */
bb_info_msg("Received DHCP NAK");
udhcp_run_script(&packet, "nak");
if (state != REQUESTING)
udhcp_run_script(NULL, "deconfig");
change_listen_mode(LISTEN_RAW);
sleep(3); /* avoid excessive network traffic */
state = INIT_SELECTING;
requested_ip = 0;
timeout = 0;
packet_num = 0;
}
continue;
/* case BOUND, RELEASED: - ignore all packets */
}
continue; /* back to main loop */
}
/* select() didn't timeout, something did happen.
* But it wasn't a packet. It's a signal pipe then. */
{
int signo = udhcp_sp_read(&rfds);
switch (signo) {
case SIGUSR1:
perform_renew();
/* start things over */
packet_num = 0;
/* Kill any timeouts because the user wants this to hurry along */
timeout = 0;
break;
case SIGUSR2:
perform_release();
break;
case SIGTERM:
bb_info_msg("Received SIGTERM");
if (client_config.release_on_quit)
perform_release();
goto ret0;
}
}
} /* for (;;) - main loop ends */
ret0:
retval = 0;
ret:
/*if (client_config.pidfile) - remove_pidfile has it's own check */
remove_pidfile(client_config.pidfile);
return retval;
}
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