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busybox/networking/udhcp/dhcpc.c
Denis Vlasenko f1980f67d3 dhcp: add FAST_FUNC as appropriate. -160 bytes.
2008-09-26 09:34:59 +00:00

636 lines
18 KiB
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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 <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 sockfd = -1;
#define LISTEN_NONE 0
#define LISTEN_KERNEL 1
#define LISTEN_RAW 2
static smallint listen_mode;
#define INIT_SELECTING 0
#define REQUESTING 1
#define BOUND 2
#define RENEWING 3
#define REBINDING 4
#define INIT_REBOOT 5
#define RENEW_REQUESTED 6
#define RELEASED 7
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(uint32_t requested_ip, uint32_t server_addr)
{
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;
}
#if BB_MMU
static void client_background(void)
{
bb_daemonize(0);
logmode &= ~LOGMODE_STDIO;
/* rewrite pidfile, as our pid is different now */
write_pidfile(client_config.pidfile);
}
#endif
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 UNUSED_PARAM, char **argv)
{
uint8_t *temp, *message;
char *str_c, *str_V, *str_h, *str_F, *str_r;
USE_FEATURE_UDHCP_PORT(char *str_P;)
llist_t *list_O = NULL;
int tryagain_timeout = 20;
int discover_timeout = 3;
int discover_retries = 3;
uint32_t server_addr = server_addr; /* for compiler */
uint32_t requested_ip = 0;
uint32_t xid = 0;
uint32_t lease_seconds = 0; /* can be given as 32-bit quantity */
int packet_num;
int timeout; /* must be signed */
unsigned already_waited_sec;
unsigned opt;
int max_fd;
int retval;
struct timeval tv;
struct dhcpMessage packet;
fd_set rfds;
#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"
"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"
"request-option\0" Required_argument "O"
"no-default-options\0" No_argument "o"
"foreground\0" No_argument "f"
"background\0" No_argument "b"
USE_FEATURE_UDHCPC_ARPING("arping\0" No_argument "a")
USE_FEATURE_UDHCP_PORT("client-port\0" Required_argument "P")
;
#endif
enum {
OPT_c = 1 << 0,
OPT_C = 1 << 1,
OPT_V = 1 << 2,
OPT_H = 1 << 3,
OPT_h = 1 << 4,
OPT_F = 1 << 5,
OPT_i = 1 << 6,
OPT_n = 1 << 7,
OPT_p = 1 << 8,
OPT_q = 1 << 9,
OPT_R = 1 << 10,
OPT_r = 1 << 11,
OPT_s = 1 << 12,
OPT_T = 1 << 13,
OPT_t = 1 << 14,
OPT_v = 1 << 15,
OPT_S = 1 << 16,
OPT_A = 1 << 17,
OPT_O = 1 << 18,
OPT_o = 1 << 19,
OPT_f = 1 << 20,
/* The rest has variable bit positions, need to be clever */
OPTBIT_f = 20,
USE_FOR_MMU( OPTBIT_b,)
USE_FEATURE_UDHCPC_ARPING(OPTBIT_a,)
USE_FEATURE_UDHCP_PORT( OPTBIT_P,)
USE_FOR_MMU( OPT_b = 1 << OPTBIT_b,)
USE_FEATURE_UDHCPC_ARPING(OPT_a = 1 << OPTBIT_a,)
USE_FEATURE_UDHCP_PORT( OPT_P = 1 << OPTBIT_P,)
};
/* Default options. */
USE_FEATURE_UDHCP_PORT(SERVER_PORT = 67;)
USE_FEATURE_UDHCP_PORT(CLIENT_PORT = 68;)
client_config.interface = "eth0";
client_config.script = DEFAULT_SCRIPT;
/* Parse command line */
/* Cc: mutually exclusive; O: list; -T,-t,-A take numeric param */
opt_complementary = "c--C:C--c:O::T+:t+:A+";
USE_GETOPT_LONG(applet_long_options = udhcpc_longopts;)
opt = getopt32(argv, "c:CV:H:h:F:i:np:qRr:s:T:t:vSA:O:of"
USE_FOR_MMU("b")
USE_FEATURE_UDHCPC_ARPING("a")
USE_FEATURE_UDHCP_PORT("P:")
, &str_c, &str_V, &str_h, &str_h, &str_F
, &client_config.interface, &client_config.pidfile, &str_r /* i,p */
, &client_config.script /* s */
, &discover_timeout, &discover_retries, &tryagain_timeout /* T,t,A */
, &list_O
USE_FEATURE_UDHCP_PORT(, &str_P)
);
if (opt & OPT_c)
client_config.clientid = alloc_dhcp_option(DHCP_CLIENT_ID, str_c, 0);
if (opt & OPT_V)
client_config.vendorclass = alloc_dhcp_option(DHCP_VENDOR, str_V, 0);
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<3>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_r)
requested_ip = inet_addr(str_r);
if (opt & OPT_v) {
puts("version "BB_VER);
return 0;
}
#if ENABLE_FEATURE_UDHCP_PORT
if (opt & OPT_P) {
CLIENT_PORT = xatou16(str_P);
SERVER_PORT = CLIENT_PORT - 1;
}
#endif
if (opt & OPT_o)
client_config.no_default_options = 1;
while (list_O) {
char *optstr = llist_pop(&list_O);
int n = index_in_strings(dhcp_option_strings, optstr);
if (n < 0)
bb_error_msg_and_die("unknown option '%s'", optstr);
n = dhcp_options[n].code;
client_config.opt_mask[n >> 3] |= 1 << (n & 7);
}
if (udhcp_read_interface(client_config.interface, &client_config.ifindex,
NULL, client_config.arp))
return 1;
#if !BB_MMU
/* on NOMMU reexec (i.e., background) early */
if (!(opt & OPT_f)) {
bb_daemonize_or_rexec(0 /* flags */, argv);
logmode = 0;
}
#endif
if (opt & OPT_S) {
openlog(applet_name, LOG_PID, LOG_LOCAL0);
logmode |= LOGMODE_SYSLOG;
}
/* 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);
/* Goes to stdout (unless NOMMU) 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;
timeout = 0;
already_waited_sec = 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 (;;) {
unsigned timestamp_before_wait;
if (listen_mode != LISTEN_NONE && sockfd < 0) {
if (listen_mode == LISTEN_KERNEL)
sockfd = udhcp_listen_socket(/*INADDR_ANY,*/ CLIENT_PORT, client_config.interface);
else
sockfd = udhcp_raw_socket(client_config.ifindex);
}
max_fd = udhcp_sp_fd_set(&rfds, sockfd);
tv.tv_sec = timeout - already_waited_sec;
tv.tv_usec = 0;
retval = 0; /* If we already timed out, fall through, else... */
if (tv.tv_sec > 0) {
timestamp_before_wait = (unsigned)monotonic_sec();
DEBUG("Waiting on select...");
retval = select(max_fd + 1, &rfds, NULL, NULL, &tv);
if (retval < 0) {
/* EINTR? A signal was caught, don't panic */
if (errno == EINTR)
continue;
/* Else: an error occured, panic! */
bb_perror_msg_and_die("select");
}
}
/* If timeout dropped to zero, time to become active:
* resend discover/renew/whatever
*/
if (retval == 0) {
/* We will restart the wait in any case */
already_waited_sec = 0;
switch (state) {
case INIT_SELECTING:
if (packet_num < discover_retries) {
if (packet_num == 0)
xid = random_xid();
send_discover(xid, requested_ip); /* broadcast */
timeout = discover_timeout;
packet_num++;
continue;
}
leasefail:
udhcp_run_script(NULL, "leasefail");
#if BB_MMU /* -b is not supported on NOMMU */
if (opt & OPT_b) { /* background if no lease */
bb_info_msg("No lease, forking to background");
client_background();
/* do not background again! */
opt = ((opt & ~OPT_b) | OPT_f);
} else
#endif
if (opt & OPT_n) { /* abort if no lease */
bb_info_msg("No lease, failing");
retval = 1;
goto ret;
}
/* wait before trying 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) /* unicast */
send_renew(xid, server_addr, requested_ip);
else /* broadcast */
send_selecting(xid, server_addr, requested_ip);
timeout = discover_timeout;
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;
/* "discover...select...discover..." loops
* were seen in the wild. Treat then similarly
* to "no response to discover" case */
if (state == REQUESTING)
goto leasefail;
timeout = 0;
packet_num = 0;
continue;
case BOUND:
/* Half of the lease passed, time to enter renewing state */
change_listen_mode(LISTEN_KERNEL);
DEBUG("Entering renew state");
state = RENEWING;
/* fall right through */
case RENEWING:
if (timeout > 60) {
/* send a request packet */
send_renew(xid, server_addr, requested_ip); /* unicast */
timeout >>= 1;
continue;
}
/* Timed out, enter rebinding state */
DEBUG("Entering rebinding state");
state = REBINDING;
/* fall right through */
case REBINDING:
/* Lease is *really* about to run out,
* try to find DHCP server using broadcast */
if (timeout > 0) {
/* send a request packet */
send_renew(xid, 0, requested_ip); /* broadcast */
timeout >>= 1;
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; - already is */
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)) {
int len;
/* A packet is ready, read it */
if (listen_mode == LISTEN_KERNEL)
len = udhcp_recv_kernel_packet(&packet, sockfd);
else
len = udhcp_recv_raw_packet(&packet, sockfd);
if (len == -1) { /* error is severe, reopen socket */
DEBUG("error on read, %s, reopening socket", strerror(errno));
sleep(discover_timeout); /* 3 seconds by default */
change_listen_mode(listen_mode); /* just close and reopen */
}
/* If this packet will turn out to be unrelated/bogus,
* we will go back and wait for next one.
* Be sure timeout is properly decreased. */
already_waited_sec += (unsigned)monotonic_sec() - timestamp_before_wait;
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 */
}
/* it IS unaligned sometimes, don't "optimize" */
server_addr = get_unaligned_u32p((uint32_t*)temp);
xid = packet.xid;
requested_ip = packet.yiaddr;
/* enter requesting state */
state = REQUESTING;
timeout = 0;
packet_num = 0;
already_waited_sec = 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);
lease_seconds &= 0x0fffffff; /* paranoia: must not be prone to overflows */
if (lease_seconds < 10) /* and not too small */
lease_seconds = 10;
}
#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;
already_waited_sec = 0;
continue; /* back to main loop */
}
}
#endif
/* enter bound state */
timeout = lease_seconds / 2;
{
struct in_addr temp_addr;
temp_addr.s_addr = packet.yiaddr;
bb_info_msg("Lease of %s obtained, lease time %u",
inet_ntoa(temp_addr), (unsigned)lease_seconds);
}
requested_ip = packet.yiaddr;
udhcp_run_script(&packet,
((state == RENEWING || state == REBINDING) ? "renew" : "bound"));
state = BOUND;
change_listen_mode(LISTEN_NONE);
if (opt & OPT_q) { /* quit after lease */
if (opt & OPT_R) /* release on quit */
perform_release(requested_ip, server_addr);
goto ret0;
}
#if BB_MMU /* NOMMU case backgrounded earlier */
if (!(opt & OPT_f)) {
client_background();
/* do not background again! */
opt = ((opt & ~OPT_b) | OPT_f);
}
#endif
already_waited_sec = 0;
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;
already_waited_sec = 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(requested_ip, server_addr);
timeout = INT_MAX;
break;
case SIGTERM:
bb_info_msg("Received SIGTERM");
if (opt & OPT_R) /* release on quit */
perform_release(requested_ip, server_addr);
goto ret0;
}
}
} /* for (;;) - main loop ends */
ret0:
retval = 0;
ret:
/*if (client_config.pidfile) - remove_pidfile has its own check */
remove_pidfile(client_config.pidfile);
return retval;
}
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