dhcpc: cleanup and comments; fix buggy timeout handling in corner cases.
-25 bytes.
This commit is contained in:
Denis Vlasenko
parent
223bc97f61
commit
9cdfd14223
@ -24,7 +24,7 @@
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* in the code. Manpage says that struct in_addr has a member of type long (!)
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* which holds IPv4 address, and the struct is passed by value (!!)
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*/
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static unsigned timeout;
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static int timeout; /* = 0. Must be signed */
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static uint32_t requested_ip; /* = 0 */
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static uint32_t server_addr;
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static int packet_num; /* = 0 */
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@ -41,7 +41,7 @@ static smallint state;
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/* just a little helper */
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static void change_mode(int new_mode)
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static void change_listen_mode(int new_mode)
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{
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DEBUG("entering %s listen mode",
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new_mode ? (new_mode == 1 ? "kernel" : "raw") : "none");
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@ -59,7 +59,7 @@ static void perform_renew(void)
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bb_info_msg("Performing a DHCP renew");
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switch (state) {
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case BOUND:
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change_mode(LISTEN_KERNEL);
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change_listen_mode(LISTEN_KERNEL);
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case RENEWING:
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case REBINDING:
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state = RENEW_REQUESTED;
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@ -68,7 +68,7 @@ static void perform_renew(void)
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udhcp_run_script(NULL, "deconfig");
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case REQUESTING:
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case RELEASED:
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change_mode(LISTEN_RAW);
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change_listen_mode(LISTEN_RAW);
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state = INIT_SELECTING;
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break;
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case INIT_SELECTING:
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@ -101,7 +101,7 @@ static void perform_release(void)
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}
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bb_info_msg("Entering released state");
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change_mode(LISTEN_NONE);
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change_listen_mode(LISTEN_NONE);
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state = RELEASED;
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timeout = INT_MAX;
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}
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@ -153,10 +153,9 @@ int udhcpc_main(int argc, char **argv)
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char *str_W;
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#endif
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uint32_t xid = 0;
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uint32_t lease = 0; /* can be given as 32-bit quantity */
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uint32_t lease_seconds = 0; /* can be given as 32-bit quantity */
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unsigned t1 = 0, t2 = 0; /* what a wonderful names */
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unsigned start = 0;
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unsigned now;
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unsigned timestamp_got_lease = 0; /* for gcc */
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unsigned opt;
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int max_fd;
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int retval;
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@ -324,13 +323,14 @@ int udhcpc_main(int argc, char **argv)
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state = INIT_SELECTING;
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udhcp_run_script(NULL, "deconfig");
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change_mode(LISTEN_RAW);
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tv.tv_sec = 0;
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goto jump_in;
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change_listen_mode(LISTEN_RAW);
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/* Main event loop. select() waits on signal pipe and possibly
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* on sockfd.
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* "continue" statements in code below jump to the top of the loop.
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*/
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for (;;) {
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tv.tv_sec = timeout - monotonic_sec();
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jump_in:
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tv.tv_sec = timeout;
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tv.tv_usec = 0;
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if (listen_mode != LISTEN_NONE && sockfd < 0) {
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@ -347,15 +347,19 @@ int udhcpc_main(int argc, char **argv)
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retval = select(max_fd + 1, &rfds, NULL, NULL, &tv);
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}
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now = monotonic_sec();
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if (retval < 0) {
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/* EINTR? signal was caught, don't panic */
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if (errno != EINTR) {
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/* Else: an error occured, panic! */
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bb_perror_msg_and_die("select");
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}
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} else if (retval == 0) {
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/* timeout dropped to zero */
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continue;
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}
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/* If timeout dropped to zero, time to become active:
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* resend discover/renew/whatever
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*/
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if (retval == 0) {
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switch (state) {
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case INIT_SELECTING:
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if (packet_num < discover_retries) {
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@ -365,23 +369,23 @@ int udhcpc_main(int argc, char **argv)
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/* send discover packet */
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send_discover(xid, requested_ip); /* broadcast */
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timeout = now + discover_timeout;
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timeout = discover_timeout;
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packet_num++;
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} else {
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udhcp_run_script(NULL, "leasefail");
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if (client_config.background_if_no_lease) {
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bb_info_msg("No lease, forking to background");
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client_background();
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} else if (client_config.abort_if_no_lease) {
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bb_info_msg("No lease, failing");
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retval = 1;
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goto ret;
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}
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/* wait to try again */
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packet_num = 0;
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timeout = now + tryagain_timeout;
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continue;
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}
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break;
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udhcp_run_script(NULL, "leasefail");
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if (client_config.background_if_no_lease) {
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bb_info_msg("No lease, forking to background");
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client_background();
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} else if (client_config.abort_if_no_lease) {
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bb_info_msg("No lease, failing");
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retval = 1;
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goto ret;
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}
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/* wait to try again */
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timeout = tryagain_timeout;
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packet_num = 0;
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continue;
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case RENEW_REQUESTED:
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case REQUESTING:
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if (packet_num < discover_retries) {
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@ -390,62 +394,67 @@ int udhcpc_main(int argc, char **argv)
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send_renew(xid, server_addr, requested_ip); /* unicast */
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else send_selecting(xid, server_addr, requested_ip); /* broadcast */
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timeout = now + ((packet_num == 2) ? 10 : 2);
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timeout = ((packet_num == 2) ? 10 : 2);
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packet_num++;
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} else {
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/* timed out, go back to init state */
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if (state == RENEW_REQUESTED)
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udhcp_run_script(NULL, "deconfig");
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state = INIT_SELECTING;
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timeout = now;
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packet_num = 0;
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change_mode(LISTEN_RAW);
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continue;
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}
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break;
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/* timed out, go back to init state */
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if (state == RENEW_REQUESTED)
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udhcp_run_script(NULL, "deconfig");
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change_listen_mode(LISTEN_RAW);
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state = INIT_SELECTING;
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timeout = 0;
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packet_num = 0;
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continue;
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case BOUND:
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/* Lease is starting to run out, time to enter renewing state */
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state = RENEWING;
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change_mode(LISTEN_KERNEL);
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change_listen_mode(LISTEN_KERNEL);
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DEBUG("Entering renew state");
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state = RENEWING;
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/* fall right through */
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case RENEWING:
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/* Either set a new T1, or enter REBINDING state */
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if ((t2 - t1) <= (lease / 14400 + 1)) {
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/* timed out, enter rebinding state */
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state = REBINDING;
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timeout = now + (t2 - t1);
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DEBUG("Entering rebinding state");
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} else {
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if ((t2 - t1) > (lease_seconds / (4*60*60) + 1)) {
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/* send a request packet */
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send_renew(xid, server_addr, requested_ip); /* unicast */
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t1 = (t2 - t1) / 2 + t1;
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timeout = start + t1;
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t1 += (t2 - t1) / 2;
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timeout = t1 - ((int)monotonic_sec() - timestamp_got_lease);
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continue;
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}
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break;
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/* Timed out, enter rebinding state */
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DEBUG("Entering rebinding state");
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state = REBINDING;
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timeout = (t2 - t1);
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continue;
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case REBINDING:
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/* Either set a new T2, or enter INIT state */
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if ((lease - t2) <= (lease / 14400 + 1)) {
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/* timed out, enter init state */
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state = INIT_SELECTING;
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bb_info_msg("Lease lost, entering init state");
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udhcp_run_script(NULL, "deconfig");
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timeout = now;
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packet_num = 0;
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change_mode(LISTEN_RAW);
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} else {
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/* Lease is *really* about to run out,
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* try to find DHCP server using broadcast */
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if ((lease_seconds - t2) > (lease_seconds / (4*60*60) + 1)) {
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/* send a request packet */
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send_renew(xid, 0, requested_ip); /* broadcast */
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t2 = (lease - t2) / 2 + t2;
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timeout = start + t2;
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t2 += (lease_seconds - t2) / 2;
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timeout = t2 - ((int)monotonic_sec() - timestamp_got_lease);
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continue;
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}
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break;
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case RELEASED:
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/* yah, I know, *you* say it would never happen */
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timeout = INT_MAX;
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break;
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/* Timed out, enter init state */
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bb_info_msg("Lease lost, entering init state");
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udhcp_run_script(NULL, "deconfig");
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change_listen_mode(LISTEN_RAW);
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state = INIT_SELECTING;
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timeout = 0;
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packet_num = 0;
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continue;
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/* case RELEASED: */
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}
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} else if (listen_mode != LISTEN_NONE && FD_ISSET(sockfd, &rfds)) {
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/* a packet is ready, read it */
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/* yah, I know, *you* say it would never happen */
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timeout = INT_MAX;
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continue; /* back to main loop */
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}
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/* select() didn't timeout, something did happen. */
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/* Is is a packet? */
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if (listen_mode != LISTEN_NONE && FD_ISSET(sockfd, &rfds)) {
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/* A packet is ready, read it */
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if (listen_mode == LISTEN_KERNEL)
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len = udhcp_get_packet(&packet, sockfd);
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@ -453,7 +462,7 @@ int udhcpc_main(int argc, char **argv)
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if (len == -1 && errno != EINTR) {
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DEBUG("error on read, %s, reopening socket", strerror(errno));
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change_mode(listen_mode); /* just close and reopen */
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change_listen_mode(listen_mode); /* just close and reopen */
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}
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if (len < 0) continue;
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@ -471,7 +480,7 @@ int udhcpc_main(int argc, char **argv)
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message = get_option(&packet, DHCP_MESSAGE_TYPE);
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if (message == NULL) {
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bb_error_msg("cannot get option from packet - ignoring");
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bb_error_msg("cannot get message type from packet - ignoring");
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continue;
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}
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@ -479,22 +488,24 @@ int udhcpc_main(int argc, char **argv)
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case INIT_SELECTING:
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/* Must be a DHCPOFFER to one of our xid's */
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if (*message == DHCPOFFER) {
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/* TODO: why we don't just fetch server's IP from IP header? */
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temp = get_option(&packet, DHCP_SERVER_ID);
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if (temp) {
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/* can be misaligned, thus memcpy */
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memcpy(&server_addr, temp, 4);
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xid = packet.xid;
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requested_ip = packet.yiaddr;
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/* enter requesting state */
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state = REQUESTING;
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timeout = now;
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packet_num = 0;
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} else {
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if (!temp) {
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bb_error_msg("no server ID in message");
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continue;
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/* still selecting - this server looks bad */
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}
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/* can be misaligned, thus memcpy */
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memcpy(&server_addr, temp, 4);
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xid = packet.xid;
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requested_ip = packet.yiaddr;
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/* enter requesting state */
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state = REQUESTING;
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timeout = 0;
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packet_num = 0;
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}
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break;
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continue;
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case RENEW_REQUESTED:
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case REQUESTING:
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case RENEWING:
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@ -503,13 +514,12 @@ int udhcpc_main(int argc, char **argv)
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temp = get_option(&packet, DHCP_LEASE_TIME);
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if (!temp) {
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bb_error_msg("no lease time with ACK, using 1 hour lease");
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lease = 60 * 60;
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lease_seconds = 60 * 60;
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} else {
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/* can be misaligned, thus memcpy */
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memcpy(&lease, temp, 4);
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lease = ntohl(lease);
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memcpy(&lease_seconds, temp, 4);
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lease_seconds = ntohl(lease_seconds);
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}
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#if ENABLE_FEATURE_UDHCPC_ARPING
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if (opt & OPT_a) {
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if (!arpping(packet.yiaddr,
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@ -517,37 +527,37 @@ int udhcpc_main(int argc, char **argv)
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client_config.arp,
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client_config.interface)
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) {
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bb_info_msg("offered address is in use,"
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" declining");
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bb_info_msg("offered address is in use "
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"(got ARP reply), declining");
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send_decline(xid, server_addr);
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if (state != REQUESTING)
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udhcp_run_script(NULL, "deconfig");
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change_listen_mode(LISTEN_RAW);
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state = INIT_SELECTING;
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requested_ip = 0;
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timeout = decline_wait;
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packet_num = 0;
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change_mode(LISTEN_RAW);
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timeout = now + decline_wait;
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break;
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continue; /* back to main loop */
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}
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}
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#endif
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/* enter bound state */
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t1 = lease / 2;
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t1 = lease_seconds / 2;
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/* little fixed point for n * .875 */
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t2 = (lease * 7) >> 3;
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t2 = (lease_seconds * 7) >> 3;
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temp_addr.s_addr = packet.yiaddr;
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bb_info_msg("Lease of %s obtained, lease time %u",
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inet_ntoa(temp_addr), (unsigned)lease);
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start = now;
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timeout = start + t1;
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inet_ntoa(temp_addr), (unsigned)lease_seconds);
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timestamp_got_lease = monotonic_sec();
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timeout = t1;
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requested_ip = packet.yiaddr;
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udhcp_run_script(&packet,
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((state == RENEWING || state == REBINDING) ? "renew" : "bound"));
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state = BOUND;
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change_mode(LISTEN_NONE);
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change_listen_mode(LISTEN_NONE);
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if (client_config.quit_after_lease) {
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if (client_config.release_on_quit)
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perform_release();
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@ -556,23 +566,30 @@ int udhcpc_main(int argc, char **argv)
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if (!client_config.foreground)
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client_background();
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} else if (*message == DHCPNAK) {
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continue; /* back to main loop */
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}
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if (*message == DHCPNAK) {
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/* return to init state */
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bb_info_msg("Received DHCP NAK");
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udhcp_run_script(&packet, "nak");
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if (state != REQUESTING)
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udhcp_run_script(NULL, "deconfig");
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state = INIT_SELECTING;
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timeout = now;
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requested_ip = 0;
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packet_num = 0;
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change_mode(LISTEN_RAW);
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change_listen_mode(LISTEN_RAW);
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sleep(3); /* avoid excessive network traffic */
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state = INIT_SELECTING;
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requested_ip = 0;
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timeout = 0;
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packet_num = 0;
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}
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break;
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continue;
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/* case BOUND, RELEASED: - ignore all packets */
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}
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} else {
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continue; /* back to main loop */
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}
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/* select() didn't timeout, something did happen.
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* But it wasn't a packet. It's a signal pipe then. */
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{
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int signo = udhcp_sp_read(&rfds);
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switch (signo) {
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case SIGUSR1:
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@ -588,7 +605,8 @@ int udhcpc_main(int argc, char **argv)
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goto ret0;
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}
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}
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} /* for (;;) */
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} /* for (;;) - main loop ends */
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ret0:
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retval = 0;
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ret:
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