diff options
| -rw-r--r-- | networking/udhcp/dhcpc.c | 232 |
1 files changed, 125 insertions, 107 deletions
diff --git a/networking/udhcp/dhcpc.c b/networking/udhcp/dhcpc.c index b3b8945..234ecfd 100644 --- a/networking/udhcp/dhcpc.c +++ b/networking/udhcp/dhcpc.c @@ -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: |