/* vi: set sw=4 ts=4: */ /* dhcpc.c * * udhcp DHCP client * * Russ Dill July 2001 * * Licensed under the GPL v2 or later, see the file LICENSE in this tarball. */ #include #include /* 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" /* Something is definitely wrong here. IPv4 addresses * in variables of type long?? BTW, we use inet_ntoa() * 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 uint32_t requested_ip; /* = 0 */ static uint32_t server_addr; static int packet_num; /* = 0 */ static int sockfd = -1; #define LISTEN_NONE 0 #define LISTEN_KERNEL 1 #define LISTEN_RAW 2 static smallint listen_mode; static smallint state; struct client_config_t client_config; /* just a little helper */ static void change_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_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_mode(LISTEN_RAW); state = INIT_SELECTING; break; case INIT_SELECTING: break; } /* start things over */ packet_num = 0; /* Kill any timeouts because the user wants this to hurry along */ timeout = 0; } /* perform a release */ static void perform_release(void) { 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_mode(LISTEN_NONE); state = RELEASED; timeout = INT_MAX; } static void client_background(void) { #ifdef __uClinux__ bb_error_msg("cannot background in uclinux (yet)"); /* ... mainly because udhcpc calls client_background() * in _the _middle _of _udhcpc _run_, not at the start! * If that will be properly disabled for NOMMU, client_background() * will work on NOMMU too */ #else bb_daemonize(0); logmode &= ~LOGMODE_STDIO; /* rewrite pidfile, as our pid is different now */ if (client_config.pidfile) write_pidfile(client_config.pidfile); #endif /* Do not fork again. */ client_config.foreground = 1; client_config.background_if_no_lease = 0; } 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); int udhcpc_main(int argc, char **argv) { uint8_t *temp, *message; char *str_c, *str_V, *str_h, *str_F, *str_r, *str_T, *str_t; uint32_t xid = 0; uint32_t lease = 0; /* can be given as 32-bit quantity */ unsigned t1 = 0, t2 = 0; unsigned start = 0; unsigned now; unsigned opt; int max_fd; int sig; int retval; int len; int no_clientid = 0; fd_set rfds; struct timeval tv; struct dhcpMessage packet; struct in_addr temp_addr; enum { OPT_c = 1 << 0, OPT_C = 1 << 1, OPT_V = 1 << 2, OPT_f = 1 << 3, OPT_b = 1 << 4, OPT_H = 1 << 5, OPT_h = 1 << 6, OPT_F = 1 << 7, OPT_i = 1 << 8, OPT_n = 1 << 9, OPT_p = 1 << 10, OPT_q = 1 << 11, OPT_R = 1 << 12, OPT_r = 1 << 13, OPT_s = 1 << 14, OPT_T = 1 << 15, OPT_t = 1 << 16, OPT_v = 1 << 17, }; #if ENABLE_GETOPT_LONG static const char udhcpc_longopts[] = "clientid\0" Required_argument "c" "clientid-none\0" No_argument "C" "vendorclass\0" Required_argument "V" "foreground\0" No_argument "f" "background\0" No_argument "b" "hostname\0" Required_argument "H" "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" ; #endif /* Default options. */ client_config.interface = "eth0"; client_config.script = DEFAULT_SCRIPT; client_config.retries = 3; client_config.timeout = 3; /* Parse command line */ opt_complementary = "c--C:C--c" // mutually exclusive ":hH:Hh"; // -h and -H are the same #if ENABLE_GETOPT_LONG applet_long_options = udhcpc_longopts; #endif opt = getopt32(argc, argv, "c:CV:fbH:h:F:i:np:qRr:s:T:t:v", &str_c, &str_V, &str_h, &str_h, &str_F, &client_config.interface, &client_config.pidfile, &str_r, &client_config.script, &str_T, &str_t ); if (opt & OPT_c) client_config.clientid = alloc_dhcp_option(DHCP_CLIENT_ID, str_c, 0); if (opt & OPT_C) no_clientid = 1; if (opt & OPT_V) client_config.vendorclass = alloc_dhcp_option(DHCP_VENDOR, str_V, 0); if (opt & OPT_f) client_config.foreground = 1; if (opt & OPT_b) client_config.background_if_no_lease = 1; if (opt & 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<4>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_i) client_config.interface = ... if (opt & OPT_n) client_config.abort_if_no_lease = 1; // if (opt & OPT_p) client_config.pidfile = ... if (opt & OPT_q) client_config.quit_after_lease = 1; if (opt & OPT_R) client_config.release_on_quit = 1; if (opt & OPT_r) requested_ip = inet_addr(str_r); // if (opt & OPT_s) client_config.script = ... if (opt & OPT_T) client_config.timeout = xatoi_u(str_T); if (opt & OPT_t) client_config.retries = xatoi_u(str_t); if (opt & OPT_v) { printf("version %s\n\n", BB_VER); return 0; } if (ENABLE_FEATURE_UDHCP_SYSLOG) { openlog(applet_name, LOG_PID, LOG_LOCAL0); logmode |= LOGMODE_SYSLOG; } if (read_interface(client_config.interface, &client_config.ifindex, NULL, client_config.arp) < 0) return 1; /* Sanitize fd's and write pidfile */ udhcp_make_pidfile(client_config.pidfile); /* if not set, and not suppressed, setup the default client ID */ if (!client_config.clientid && !no_clientid) { 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_mode(LISTEN_RAW); for (;;) { tv.tv_sec = timeout - monotonic_sec(); tv.tv_usec = 0; if (listen_mode != LISTEN_NONE && sockfd < 0) { if (listen_mode == LISTEN_KERNEL) sockfd = listen_socket(INADDR_ANY, CLIENT_PORT, client_config.interface); else sockfd = raw_socket(client_config.ifindex); } max_fd = udhcp_sp_fd_set(&rfds, sockfd); if (tv.tv_sec > 0) { DEBUG("Waiting on select..."); retval = select(max_fd + 1, &rfds, NULL, NULL, &tv); } else retval = 0; /* If we already timed out, fall through */ now = monotonic_sec(); if (retval == 0) { /* timeout dropped to zero */ switch (state) { case INIT_SELECTING: if (packet_num < client_config.retries) { if (packet_num == 0) xid = random_xid(); /* send discover packet */ send_discover(xid, requested_ip); /* broadcast */ timeout = now + client_config.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 + 60; } break; case RENEW_REQUESTED: case REQUESTING: if (packet_num < client_config.retries) { /* send request packet */ if (state == RENEW_REQUESTED) send_renew(xid, server_addr, requested_ip); /* unicast */ else send_selecting(xid, server_addr, requested_ip); /* broadcast */ timeout = now + ((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); } break; case BOUND: /* Lease is starting to run out, time to enter renewing state */ state = RENEWING; change_mode(LISTEN_KERNEL); DEBUG("Entering renew state"); /* 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 { /* send a request packet */ send_renew(xid, server_addr, requested_ip); /* unicast */ t1 = (t2 - t1) / 2 + t1; timeout = t1 + start; } break; 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 { /* send a request packet */ send_renew(xid, 0, requested_ip); /* broadcast */ t2 = (lease - t2) / 2 + t2; timeout = t2 + start; } break; case RELEASED: /* yah, I know, *you* say it would never happen */ timeout = INT_MAX; break; } } else if (retval > 0 && 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); else len = get_raw_packet(&packet, sockfd); if (len == -1 && errno != EINTR) { DEBUG("error on read, %s, reopening socket", strerror(errno)); change_mode(listen_mode); /* just close and reopen */ } 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 option from packet - ignoring"); continue; } switch (state) { case INIT_SELECTING: /* Must be a DHCPOFFER to one of our xid's */ if (*message == DHCPOFFER) { 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 { bb_error_msg("no server ID in message"); } } break; 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 = 60 * 60; } else { /* can be misaligned, thus memcpy */ memcpy(&lease, temp, 4); lease = ntohl(lease); } /* enter bound state */ t1 = lease / 2; /* little fixed point for n * .875 */ t2 = (lease * 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 = t1 + start; requested_ip = packet.yiaddr; udhcp_run_script(&packet, ((state == RENEWING || state == REBINDING) ? "renew" : "bound")); state = BOUND; change_mode(LISTEN_NONE); if (client_config.quit_after_lease) { if (client_config.release_on_quit) perform_release(); goto ret0; } if (!client_config.foreground) client_background(); } else 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"); state = INIT_SELECTING; timeout = now; requested_ip = 0; packet_num = 0; change_mode(LISTEN_RAW); sleep(3); /* avoid excessive network traffic */ } break; /* case BOUND, RELEASED: - ignore all packets */ } } else if (retval > 0 && (sig = udhcp_sp_read(&rfds))) { switch (sig) { case SIGUSR1: perform_renew(); break; case SIGUSR2: perform_release(); break; case SIGTERM: bb_info_msg("Received SIGTERM"); if (client_config.release_on_quit) perform_release(); goto ret0; } } else if (retval == -1 && errno == EINTR) { /* a signal was caught */ } else { /* An error occured */ bb_perror_msg("select"); } } /* for (;;) */ ret0: retval = 0; ret: if (client_config.pidfile) remove_pidfile(client_config.pidfile); return retval; }