emo/busybox
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

dhcpc: cleanup and comments; fix buggy timeout handling in corner cases.

Browse Source 
-25 bytes.
This commit is contained in:
Denis Vlasenko 2007-11-22 01:00:00 +00:00
parent 223bc97f61
commit 9cdfd14223
1 changed files with 127 additions and 109 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

236
networking/udhcp/dhcpc.c
View File

@ -24,7 +24,7 @@
* in the code. Manpage says that struct in_addr has a member of type long (!) * in the code. Manpage says that struct in_addr has a member of type long (!)
* which holds IPv4 address, and the struct is passed by value (!!) * which holds IPv4 address, and the struct is passed by value (!!)
*/ */
static unsigned timeout; static int timeout; /* = 0. Must be signed */
static uint32_t requested_ip; /* = 0 */ static uint32_t requested_ip; /* = 0 */
static uint32_t server_addr; static uint32_t server_addr;
static int packet_num; /* = 0 */ static int packet_num; /* = 0 */
@ -41,7 +41,7 @@ static smallint state;
/* just a little helper */ /* just a little helper */
static void change_mode(int new_mode) static void change_listen_mode(int new_mode)
{ {
DEBUG("entering %s listen mode", DEBUG("entering %s listen mode",
new_mode ? (new_mode == 1 ? "kernel" : "raw") : "none"); new_mode ? (new_mode == 1 ? "kernel" : "raw") : "none");
@ -59,7 +59,7 @@ static void perform_renew(void)
bb_info_msg("Performing a DHCP renew"); bb_info_msg("Performing a DHCP renew");
switch (state) { switch (state) {
case BOUND: case BOUND:
change_mode(LISTEN_KERNEL); change_listen_mode(LISTEN_KERNEL);
case RENEWING: case RENEWING:
case REBINDING: case REBINDING:
state = RENEW_REQUESTED; state = RENEW_REQUESTED;
@ -68,7 +68,7 @@ static void perform_renew(void)
udhcp_run_script(NULL, "deconfig"); udhcp_run_script(NULL, "deconfig");
case REQUESTING: case REQUESTING:
case RELEASED: case RELEASED:
change_mode(LISTEN_RAW); change_listen_mode(LISTEN_RAW);
state = INIT_SELECTING; state = INIT_SELECTING;
break; break;
case INIT_SELECTING: case INIT_SELECTING:
@ -101,7 +101,7 @@ static void perform_release(void)
} }
bb_info_msg("Entering released state"); bb_info_msg("Entering released state");
change_mode(LISTEN_NONE); change_listen_mode(LISTEN_NONE);
state = RELEASED; state = RELEASED;
timeout = INT_MAX; timeout = INT_MAX;
} }
@ -153,10 +153,9 @@ int udhcpc_main(int argc, char **argv)
char *str_W; char *str_W;
#endif #endif
uint32_t xid = 0; uint32_t xid = 0;
uint32_t lease = 0; /* can be given as 32-bit quantity */ uint32_t lease_seconds = 0; /* can be given as 32-bit quantity */
unsigned t1 = 0, t2 = 0; /* what a wonderful names */ unsigned t1 = 0, t2 = 0; /* what a wonderful names */
unsigned start = 0; unsigned timestamp_got_lease = 0; /* for gcc */
unsigned now;
unsigned opt; unsigned opt;
int max_fd; int max_fd;
int retval; int retval;
@ -324,13 +323,14 @@ int udhcpc_main(int argc, char **argv)
state = INIT_SELECTING; state = INIT_SELECTING;
udhcp_run_script(NULL, "deconfig"); udhcp_run_script(NULL, "deconfig");
change_mode(LISTEN_RAW); change_listen_mode(LISTEN_RAW);
tv.tv_sec = 0;
goto jump_in;
/* 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 (;;) { for (;;) {
tv.tv_sec = timeout - monotonic_sec(); tv.tv_sec = timeout;
jump_in:
tv.tv_usec = 0; tv.tv_usec = 0;
if (listen_mode != LISTEN_NONE && sockfd < 0) { if (listen_mode != LISTEN_NONE && sockfd < 0) {
@ -347,15 +347,19 @@ int udhcpc_main(int argc, char **argv)
retval = select(max_fd + 1, &rfds, NULL, NULL, &tv); retval = select(max_fd + 1, &rfds, NULL, NULL, &tv);
} }
now = monotonic_sec();
if (retval < 0) { if (retval < 0) {
/* EINTR? signal was caught, don't panic */ /* EINTR? signal was caught, don't panic */
if (errno != EINTR) { if (errno != EINTR) {
/* Else: an error occured, panic! */ /* Else: an error occured, panic! */
bb_perror_msg_and_die("select"); bb_perror_msg_and_die("select");
} }
} else if (retval == 0) { continue;
/* timeout dropped to zero */ }
/* If timeout dropped to zero, time to become active:
* resend discover/renew/whatever
*/
if (retval == 0) {
switch (state) { switch (state) {
case INIT_SELECTING: case INIT_SELECTING:
if (packet_num < discover_retries) { if (packet_num < discover_retries) {
@ -365,23 +369,23 @@ int udhcpc_main(int argc, char **argv)
/* send discover packet */ /* send discover packet */
send_discover(xid, requested_ip); /* broadcast */ send_discover(xid, requested_ip); /* broadcast */
timeout = now + discover_timeout; timeout = discover_timeout;
packet_num++; packet_num++;
} else { 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 */
packet_num = 0;
timeout = now + tryagain_timeout;
} }
break; 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 RENEW_REQUESTED:
case REQUESTING: case REQUESTING:
if (packet_num < discover_retries) { if (packet_num < discover_retries) {
@ -390,62 +394,67 @@ int udhcpc_main(int argc, char **argv)
send_renew(xid, server_addr, requested_ip); /* unicast */ send_renew(xid, server_addr, requested_ip); /* unicast */
else send_selecting(xid, server_addr, requested_ip); /* broadcast */ else send_selecting(xid, server_addr, requested_ip); /* broadcast */
timeout = now + ((packet_num == 2) ? 10 : 2); timeout = ((packet_num == 2) ? 10 : 2);
packet_num++; packet_num++;
} else { continue;
/* timed out, go back to init state */
if (state == RENEW_REQUESTED)
udhcp_run_script(NULL, "deconfig");
state = INIT_SELECTING;
timeout = now;
packet_num = 0;
change_mode(LISTEN_RAW);
} }
break; /* 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: case BOUND:
/* Lease is starting to run out, time to enter renewing state */ /* Lease is starting to run out, time to enter renewing state */
state = RENEWING; change_listen_mode(LISTEN_KERNEL);
change_mode(LISTEN_KERNEL);
DEBUG("Entering renew state"); DEBUG("Entering renew state");
state = RENEWING;
/* fall right through */ /* fall right through */
case RENEWING: case RENEWING:
/* Either set a new T1, or enter REBINDING state */ /* Either set a new T1, or enter REBINDING state */
if ((t2 - t1) <= (lease / 14400 + 1)) { if ((t2 - t1) > (lease_seconds / (4*60*60) + 1)) {
/* timed out, enter rebinding state */
state = REBINDING;
timeout = now + (t2 - t1);
DEBUG("Entering rebinding state");
} else {
/* send a request packet */ /* send a request packet */
send_renew(xid, server_addr, requested_ip); /* unicast */ send_renew(xid, server_addr, requested_ip); /* unicast */
t1 = (t2 - t1) / 2 + t1; t1 += (t2 - t1) / 2;
timeout = start + t1; timeout = t1 - ((int)monotonic_sec() - timestamp_got_lease);
continue;
} }
break; /* Timed out, enter rebinding state */
DEBUG("Entering rebinding state");
state = REBINDING;
timeout = (t2 - t1);
continue;
case REBINDING: case REBINDING:
/* Either set a new T2, or enter INIT state */ /* Lease is *really* about to run out,
if ((lease - t2) <= (lease / 14400 + 1)) { * try to find DHCP server using broadcast */
/* timed out, enter init state */ if ((lease_seconds - t2) > (lease_seconds / (4*60*60) + 1)) {
state = INIT_SELECTING;
bb_info_msg("Lease lost, entering init state");
udhcp_run_script(NULL, "deconfig");
timeout = now;
packet_num = 0;
change_mode(LISTEN_RAW);
} else {
/* send a request packet */ /* send a request packet */
send_renew(xid, 0, requested_ip); /* broadcast */ send_renew(xid, 0, requested_ip); /* broadcast */
t2 = (lease - t2) / 2 + t2; t2 += (lease_seconds - t2) / 2;
timeout = start + t2; timeout = t2 - ((int)monotonic_sec() - timestamp_got_lease);
continue;
} }
break; /* Timed out, enter init state */
case RELEASED: bb_info_msg("Lease lost, entering init state");
/* yah, I know, *you* say it would never happen */ udhcp_run_script(NULL, "deconfig");
timeout = INT_MAX; change_listen_mode(LISTEN_RAW);
break; state = INIT_SELECTING;
timeout = 0;
packet_num = 0;
continue;
/* case RELEASED: */
} }
} else if (listen_mode != LISTEN_NONE && FD_ISSET(sockfd, &rfds)) { /* yah, I know, *you* say it would never happen */
/* a packet is ready, read it */ 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) if (listen_mode == LISTEN_KERNEL)
len = udhcp_get_packet(&packet, sockfd); len = udhcp_get_packet(&packet, sockfd);
@ -453,7 +462,7 @@ int udhcpc_main(int argc, char **argv)
if (len == -1 && errno != EINTR) { if (len == -1 && errno != EINTR) {
DEBUG("error on read, %s, reopening socket", strerror(errno)); DEBUG("error on read, %s, reopening socket", strerror(errno));
change_mode(listen_mode); /* just close and reopen */ change_listen_mode(listen_mode); /* just close and reopen */
} }
if (len < 0) continue; if (len < 0) continue;
@ -471,7 +480,7 @@ int udhcpc_main(int argc, char **argv)
message = get_option(&packet, DHCP_MESSAGE_TYPE); message = get_option(&packet, DHCP_MESSAGE_TYPE);
if (message == NULL) { if (message == NULL) {
bb_error_msg("cannot get option from packet - ignoring"); bb_error_msg("cannot get message type from packet - ignoring");
continue; continue;
} }
@ -479,22 +488,24 @@ int udhcpc_main(int argc, char **argv)
case INIT_SELECTING: case INIT_SELECTING:
/* Must be a DHCPOFFER to one of our xid's */ /* Must be a DHCPOFFER to one of our xid's */
if (*message == DHCPOFFER) { if (*message == DHCPOFFER) {
/* TODO: why we don't just fetch server's IP from IP header? */
temp = get_option(&packet, DHCP_SERVER_ID); temp = get_option(&packet, DHCP_SERVER_ID);
if (temp) { if (!temp) {
/* can be misaligned, thus memcpy */
memcpy(&server_addr, temp, 4);
xid = packet.xid;
requested_ip = packet.yiaddr;
/* enter requesting state */
state = REQUESTING;
timeout = now;
packet_num = 0;
} else {
bb_error_msg("no server ID in message"); 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;
} }
break; continue;
case RENEW_REQUESTED: case RENEW_REQUESTED:
case REQUESTING: case REQUESTING:
case RENEWING: case RENEWING:
@ -503,13 +514,12 @@ int udhcpc_main(int argc, char **argv)
temp = get_option(&packet, DHCP_LEASE_TIME); temp = get_option(&packet, DHCP_LEASE_TIME);
if (!temp) { if (!temp) {
bb_error_msg("no lease time with ACK, using 1 hour lease"); bb_error_msg("no lease time with ACK, using 1 hour lease");
lease = 60 * 60; lease_seconds = 60 * 60;
} else { } else {
/* can be misaligned, thus memcpy */ /* can be misaligned, thus memcpy */
memcpy(&lease, temp, 4); memcpy(&lease_seconds, temp, 4);
lease = ntohl(lease); lease_seconds = ntohl(lease_seconds);
} }
#if ENABLE_FEATURE_UDHCPC_ARPING #if ENABLE_FEATURE_UDHCPC_ARPING
if (opt & OPT_a) { if (opt & OPT_a) {
if (!arpping(packet.yiaddr, if (!arpping(packet.yiaddr,
@ -517,37 +527,37 @@ int udhcpc_main(int argc, char **argv)
client_config.arp, client_config.arp,
client_config.interface) client_config.interface)
) { ) {
bb_info_msg("offered address is in use," bb_info_msg("offered address is in use "
" declining"); "(got ARP reply), declining");
send_decline(xid, server_addr); send_decline(xid, server_addr);
if (state != REQUESTING) if (state != REQUESTING)
udhcp_run_script(NULL, "deconfig"); udhcp_run_script(NULL, "deconfig");
change_listen_mode(LISTEN_RAW);
state = INIT_SELECTING; state = INIT_SELECTING;
requested_ip = 0; requested_ip = 0;
timeout = decline_wait;
packet_num = 0; packet_num = 0;
change_mode(LISTEN_RAW); continue; /* back to main loop */
timeout = now + decline_wait;
break;
} }
} }
#endif #endif
/* enter bound state */ /* enter bound state */
t1 = lease / 2; t1 = lease_seconds / 2;
/* little fixed point for n * .875 */ /* little fixed point for n * .875 */
t2 = (lease * 7) >> 3; t2 = (lease_seconds * 7) >> 3;
temp_addr.s_addr = packet.yiaddr; temp_addr.s_addr = packet.yiaddr;
bb_info_msg("Lease of %s obtained, lease time %u", bb_info_msg("Lease of %s obtained, lease time %u",
inet_ntoa(temp_addr), (unsigned)lease); inet_ntoa(temp_addr), (unsigned)lease_seconds);
start = now; timestamp_got_lease = monotonic_sec();
timeout = start + t1; timeout = t1;
requested_ip = packet.yiaddr; requested_ip = packet.yiaddr;
udhcp_run_script(&packet, udhcp_run_script(&packet,
((state == RENEWING || state == REBINDING) ? "renew" : "bound")); ((state == RENEWING || state == REBINDING) ? "renew" : "bound"));
state = BOUND; state = BOUND;
change_mode(LISTEN_NONE); change_listen_mode(LISTEN_NONE);
if (client_config.quit_after_lease) { if (client_config.quit_after_lease) {
if (client_config.release_on_quit) if (client_config.release_on_quit)
perform_release(); perform_release();
@ -556,23 +566,30 @@ int udhcpc_main(int argc, char **argv)
if (!client_config.foreground) if (!client_config.foreground)
client_background(); client_background();
} else if (*message == DHCPNAK) { continue; /* back to main loop */
}
if (*message == DHCPNAK) {
/* return to init state */ /* return to init state */
bb_info_msg("Received DHCP NAK"); bb_info_msg("Received DHCP NAK");
udhcp_run_script(&packet, "nak"); udhcp_run_script(&packet, "nak");
if (state != REQUESTING) if (state != REQUESTING)
udhcp_run_script(NULL, "deconfig"); udhcp_run_script(NULL, "deconfig");
state = INIT_SELECTING; change_listen_mode(LISTEN_RAW);
timeout = now;
requested_ip = 0;
packet_num = 0;
change_mode(LISTEN_RAW);
sleep(3); /* avoid excessive network traffic */ sleep(3); /* avoid excessive network traffic */
state = INIT_SELECTING;
requested_ip = 0;
timeout = 0;
packet_num = 0;
} }
break; continue;
/* case BOUND, RELEASED: - ignore all packets */ /* case BOUND, RELEASED: - ignore all packets */
} }
} else { 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); int signo = udhcp_sp_read(&rfds);
switch (signo) { switch (signo) {
case SIGUSR1: case SIGUSR1:
@ -588,7 +605,8 @@ int udhcpc_main(int argc, char **argv)
goto ret0; goto ret0;
} }
} }
} /* for (;;) */ } /* for (;;) - main loop ends */
ret0: ret0:
retval = 0; retval = 0;
ret: ret: