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9cdfd1422

Denis Vlasenko
Denis Vlasenko
2007-11-22
FAILED Duration: 19s

Subject

dhcpc: cleanup and comments; fix buggy timeout handling in corner cases. -25 bytes.

Binary

No binary (build failed)

Architecture & Compiler Flags

Architecture: x86_64-linux-gnu Compiler: gcc (Ubuntu 11.4.0-1ubuntu1~22.04.3) 11.4.0

—

Build Log

(log yok)

Commit Diff GitHub →

networking/udhcp/dhcpc.c +125 -107
networking/udhcp/dhcpc.c+125 -107
@@ -24,7 +24,7 @@
* 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 (!!)
*/
-static unsigned timeout;
+static int timeout; /* = 0. Must be signed */
static uint32_t requested_ip; /* = 0 */
static uint32_t server_addr;
static int packet_num; /* = 0 */
@@ -41,7 +41,7 @@ static smallint state;
/* just a little helper */
-static void change_mode(int new_mode)
+static void change_listen_mode(int new_mode)
{
DEBUG("entering %s listen mode",
new_mode ? (new_mode == 1 ? "kernel" : "raw") : "none");
@@ -59,7 +59,7 @@ static void perform_renew(void)
bb_info_msg("Performing a DHCP renew");
switch (state) {
case BOUND:
- change_mode(LISTEN_KERNEL);
+ change_listen_mode(LISTEN_KERNEL);
case RENEWING:
case REBINDING:
state = RENEW_REQUESTED;
@@ -68,7 +68,7 @@ static void perform_renew(void)
udhcp_run_script(NULL, "deconfig");
case REQUESTING:
case RELEASED:
- change_mode(LISTEN_RAW);
+ change_listen_mode(LISTEN_RAW);
state = INIT_SELECTING;
break;
case INIT_SELECTING:
@@ -101,7 +101,7 @@ static void perform_release(void)
}
bb_info_msg("Entering released state");
- change_mode(LISTEN_NONE);
+ change_listen_mode(LISTEN_NONE);
state = RELEASED;
timeout = INT_MAX;
}
@@ -153,10 +153,9 @@ int udhcpc_main(int argc, char **argv)
char *str_W;
#endif
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 start = 0;
- unsigned now;
+ unsigned timestamp_got_lease = 0; /* for gcc */
unsigned opt;
int max_fd;
int retval;
@@ -324,13 +323,14 @@ int udhcpc_main(int argc, char **argv)
state = INIT_SELECTING;
udhcp_run_script(NULL, "deconfig");
- change_mode(LISTEN_RAW);
- tv.tv_sec = 0;
- goto jump_in;
+ change_listen_mode(LISTEN_RAW);
+ /* 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 - monotonic_sec();
- jump_in:
+ tv.tv_sec = timeout;
tv.tv_usec = 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);
}
- now = monotonic_sec();
if (retval < 0) {
/* EINTR? signal was caught, don't panic */
if (errno != EINTR) {
/* Else: an error occured, panic! */
bb_perror_msg_and_die("select");
}
- } else if (retval == 0) {
- /* timeout dropped to zero */
+ 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) {
@@ -365,23 +369,23 @@ int udhcpc_main(int argc, char **argv)
/* send discover packet */
send_discover(xid, requested_ip); /* broadcast */
- timeout = now + discover_timeout;
+ timeout = discover_timeout;
packet_num++;
- } else {
- 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;
+ continue;
}
- 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 REQUESTING:
if (packet_num < discover_retries) {
@@ -390,62 +394,67 @@ int udhcpc_main(int argc, char **argv)
send_renew(xid, server_addr, requested_ip); /* unicast */
else send_selecting(xid, server_addr, requested_ip); /* broadcast */
- timeout = now + ((packet_num == 2) ? 10 : 2);
+ timeout = ((packet_num == 2) ? 10 : 2);
packet_num++;
- } else {
- /* 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);
+ continue;
}
- 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:
/* Lease is starting to run out, time to enter renewing state */
- state = RENEWING;
- change_mode(LISTEN_KERNEL);
+ 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 / 14400 + 1)) {
- /* timed out, enter rebinding state */
- state = REBINDING;
- timeout = now + (t2 - t1);
- DEBUG("Entering rebinding state");
- } else {
+ 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 + t1;
- timeout = start + t1;
+ t1 += (t2 - t1) / 2;
+ 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:
- /* Either set a new T2, or enter INIT state */
- if ((lease - t2) <= (lease / 14400 + 1)) {
- /* timed out, enter init state */
- 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 {
+ /* 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 - t2) / 2 + t2;
- timeout = start + t2;
+ t2 += (lease_seconds - t2) / 2;
+ timeout = t2 - ((int)monotonic_sec() - timestamp_got_lease);
+ continue;
}
- break;
- case RELEASED:
- /* yah, I know, *you* say it would never happen */
- timeout = INT_MAX;
- break;
+ /* 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: */
}
- } else if (listen_mode != LISTEN_NONE && FD_ISSET(sockfd, &rfds)) {
- /* a packet is ready, read it */
+ /* 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_get_packet(&packet, sockfd);
@@ -453,7 +462,7 @@ int udhcpc_main(int argc, char **argv)
if (len == -1 && errno != EINTR) {
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;
@@ -471,7 +480,7 @@ int udhcpc_main(int argc, char **argv)
message = get_option(&packet, DHCP_MESSAGE_TYPE);
if (message == NULL) {
- bb_error_msg("cannot get option from packet - ignoring");
+ bb_error_msg("cannot get message type from packet - ignoring");
continue;
}
@@ -479,22 +488,24 @@ int udhcpc_main(int argc, char **argv)
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) {
- /* 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 {
+ 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;
}
- break;
+ continue;
case RENEW_REQUESTED:
case REQUESTING:
case RENEWING:
@@ -503,13 +514,12 @@ int udhcpc_main(int argc, char **argv)
temp = get_option(&packet, DHCP_LEASE_TIME);
if (!temp) {
bb_error_msg("no lease time with ACK, using 1 hour lease");
- lease = 60 * 60;
+ lease_seconds = 60 * 60;
} else {
/* can be misaligned, thus memcpy */
- memcpy(&lease, temp, 4);
- lease = ntohl(lease);
+ memcpy(&lease_seconds, temp, 4);
+ lease_seconds = ntohl(lease_seconds);
}
-
#if ENABLE_FEATURE_UDHCPC_ARPING
if (opt & OPT_a) {
if (!arpping(packet.yiaddr,
@@ -517,37 +527,37 @@ int udhcpc_main(int argc, char **argv)
client_config.arp,
client_config.interface)
) {
- bb_info_msg("offered address is in use,"
- " declining");
+ bb_info_msg("offered address is in use "
+ "(got ARP reply), declining");
send_decline(xid, server_addr);
if (state != REQUESTING)
udhcp_run_script(NULL, "deconfig");
+ change_listen_mode(LISTEN_RAW);
state = INIT_SELECTING;
requested_ip = 0;
+ timeout = decline_wait;
packet_num = 0;
- change_mode(LISTEN_RAW);
- timeout = now + decline_wait;
- break;
+ continue; /* back to main loop */
}
}
#endif
/* enter bound state */
- t1 = lease / 2;
+ t1 = lease_seconds / 2;
/* little fixed point for n * .875 */
- t2 = (lease * 7) >> 3;
+ 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);
- start = now;
- timeout = start + t1;
+ 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_mode(LISTEN_NONE);
+ change_listen_mode(LISTEN_NONE);
if (client_config.quit_after_lease) {
if (client_config.release_on_quit)
perform_release();
@@ -556,23 +566,30 @@ int udhcpc_main(int argc, char **argv)
if (!client_config.foreground)
client_background();
- } else if (*message == DHCPNAK) {
+ 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;
- timeout = now;
requested_ip = 0;
+ timeout = 0;
packet_num = 0;
- change_mode(LISTEN_RAW);
- sleep(3); /* avoid excessive network traffic */
}
- break;
+ continue;
/* 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);
switch (signo) {
case SIGUSR1:
@@ -588,7 +605,8 @@ int udhcpc_main(int argc, char **argv)
goto ret0;
}
}
- } /* for (;;) */
+ } /* for (;;) - main loop ends */
+
ret0:
retval = 0;
ret: