diff options
Diffstat (limited to 'networking/udhcp/dhcpc.c')
-rw-r--r-- | networking/udhcp/dhcpc.c | 646 |
1 files changed, 646 insertions, 0 deletions
diff --git a/networking/udhcp/dhcpc.c b/networking/udhcp/dhcpc.c new file mode 100644 index 0000000..2d48980 --- /dev/null +++ b/networking/udhcp/dhcpc.c @@ -0,0 +1,646 @@ +/* vi: set sw=4 ts=4: */ +/* dhcpc.c + * + * udhcp DHCP client + * + * Russ Dill <Russ.Dill@asu.edu> July 2001 + * + * Licensed under the GPL v2 or later, see the file LICENSE in this tarball. + */ + +#include <syslog.h> + +/* 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" + + +static int sockfd = -1; + +#define LISTEN_NONE 0 +#define LISTEN_KERNEL 1 +#define LISTEN_RAW 2 +static smallint listen_mode; + +#define INIT_SELECTING 0 +#define REQUESTING 1 +#define BOUND 2 +#define RENEWING 3 +#define REBINDING 4 +#define INIT_REBOOT 5 +#define RENEW_REQUESTED 6 +#define RELEASED 7 +static smallint state; + +/* struct client_config_t client_config is in bb_common_bufsiz1 */ + + +/* just a little helper */ +static void change_listen_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_listen_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_listen_mode(LISTEN_RAW); + state = INIT_SELECTING; + break; + case INIT_SELECTING: + break; + } +} + + +/* perform a release */ +static void perform_release(uint32_t requested_ip, uint32_t server_addr) +{ + 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_listen_mode(LISTEN_NONE); + state = RELEASED; +} + + +#if BB_MMU +static void client_background(void) +{ + bb_daemonize(0); + logmode &= ~LOGMODE_STDIO; + /* rewrite pidfile, as our pid is different now */ + write_pidfile(client_config.pidfile); +} +#endif + + +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) MAIN_EXTERNALLY_VISIBLE; +int udhcpc_main(int argc UNUSED_PARAM, char **argv) +{ + uint8_t *temp, *message; + char *str_c, *str_V, *str_h, *str_F, *str_r; + USE_FEATURE_UDHCP_PORT(char *str_P;) + llist_t *list_O = NULL; + int tryagain_timeout = 20; + int discover_timeout = 3; + int discover_retries = 3; + uint32_t server_addr = server_addr; /* for compiler */ + uint32_t requested_ip = 0; + uint32_t xid = 0; + uint32_t lease_seconds = 0; /* can be given as 32-bit quantity */ + int packet_num; + int timeout; /* must be signed */ + unsigned already_waited_sec; + unsigned opt; + int max_fd; + int retval; + struct timeval tv; + struct dhcpMessage packet; + fd_set rfds; + +#if ENABLE_GETOPT_LONG + static const char udhcpc_longopts[] ALIGN1 = + "clientid\0" Required_argument "c" + "clientid-none\0" No_argument "C" + "vendorclass\0" Required_argument "V" + "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" + "tryagain\0" Required_argument "A" + "syslog\0" No_argument "S" + "request-option\0" Required_argument "O" + "no-default-options\0" No_argument "o" + "foreground\0" No_argument "f" + "background\0" No_argument "b" + USE_FEATURE_UDHCPC_ARPING("arping\0" No_argument "a") + USE_FEATURE_UDHCP_PORT("client-port\0" Required_argument "P") + ; +#endif + enum { + OPT_c = 1 << 0, + OPT_C = 1 << 1, + OPT_V = 1 << 2, + OPT_H = 1 << 3, + OPT_h = 1 << 4, + OPT_F = 1 << 5, + OPT_i = 1 << 6, + OPT_n = 1 << 7, + OPT_p = 1 << 8, + OPT_q = 1 << 9, + OPT_R = 1 << 10, + OPT_r = 1 << 11, + OPT_s = 1 << 12, + OPT_T = 1 << 13, + OPT_t = 1 << 14, + OPT_v = 1 << 15, + OPT_S = 1 << 16, + OPT_A = 1 << 17, + OPT_O = 1 << 18, + OPT_o = 1 << 19, + OPT_f = 1 << 20, +/* The rest has variable bit positions, need to be clever */ + OPTBIT_f = 20, + USE_FOR_MMU( OPTBIT_b,) + USE_FEATURE_UDHCPC_ARPING(OPTBIT_a,) + USE_FEATURE_UDHCP_PORT( OPTBIT_P,) + USE_FOR_MMU( OPT_b = 1 << OPTBIT_b,) + USE_FEATURE_UDHCPC_ARPING(OPT_a = 1 << OPTBIT_a,) + USE_FEATURE_UDHCP_PORT( OPT_P = 1 << OPTBIT_P,) + }; + + /* Default options. */ + USE_FEATURE_UDHCP_PORT(SERVER_PORT = 67;) + USE_FEATURE_UDHCP_PORT(CLIENT_PORT = 68;) + client_config.interface = "eth0"; + client_config.script = DEFAULT_SCRIPT; + + /* Parse command line */ + /* Cc: mutually exclusive; O: list; -T,-t,-A take numeric param */ + opt_complementary = "c--C:C--c:O::T+:t+:A+"; + USE_GETOPT_LONG(applet_long_options = udhcpc_longopts;) + opt = getopt32(argv, "c:CV:H:h:F:i:np:qRr:s:T:t:vSA:O:of" + USE_FOR_MMU("b") + USE_FEATURE_UDHCPC_ARPING("a") + USE_FEATURE_UDHCP_PORT("P:") + , &str_c, &str_V, &str_h, &str_h, &str_F + , &client_config.interface, &client_config.pidfile, &str_r /* i,p */ + , &client_config.script /* s */ + , &discover_timeout, &discover_retries, &tryagain_timeout /* T,t,A */ + , &list_O + USE_FEATURE_UDHCP_PORT(, &str_P) + ); + if (opt & OPT_c) + client_config.clientid = alloc_dhcp_option(DHCP_CLIENT_ID, str_c, 0); + if (opt & OPT_V) + client_config.vendorclass = alloc_dhcp_option(DHCP_VENDOR, str_V, 0); + if (opt & (OPT_h|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<3>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_r) + requested_ip = inet_addr(str_r); + if (opt & OPT_v) { + puts("version "BB_VER); + return 0; + } +#if ENABLE_FEATURE_UDHCP_PORT + if (opt & OPT_P) { + CLIENT_PORT = xatou16(str_P); + SERVER_PORT = CLIENT_PORT - 1; + } +#endif + if (opt & OPT_o) + client_config.no_default_options = 1; + while (list_O) { + char *optstr = llist_pop(&list_O); + int n = index_in_strings(dhcp_option_strings, optstr); + if (n < 0) + bb_error_msg_and_die("unknown option '%s'", optstr); + n = dhcp_options[n].code; + client_config.opt_mask[n >> 3] |= 1 << (n & 7); + } + + if (udhcp_read_interface(client_config.interface, &client_config.ifindex, + NULL, client_config.arp)) + return 1; +#if !BB_MMU + /* on NOMMU reexec (i.e., background) early */ + if (!(opt & OPT_f)) { + bb_daemonize_or_rexec(0 /* flags */, argv); + logmode = 0; + } +#endif + if (opt & OPT_S) { + openlog(applet_name, LOG_PID, LOG_LOCAL0); + logmode |= LOGMODE_SYSLOG; + } + + /* Make sure fd 0,1,2 are open */ + bb_sanitize_stdio(); + /* Equivalent of doing a fflush after every \n */ + setlinebuf(stdout); + + /* Create pidfile */ + write_pidfile(client_config.pidfile); + + /* Goes to stdout (unless NOMMU) and possibly syslog */ + bb_info_msg("%s (v"BB_VER") started", applet_name); + + /* if not set, and not suppressed, setup the default client ID */ + if (!client_config.clientid && !(opt & OPT_C)) { + 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_listen_mode(LISTEN_RAW); + packet_num = 0; + timeout = 0; + already_waited_sec = 0; + + /* 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 (;;) { + unsigned timestamp_before_wait; + + if (listen_mode != LISTEN_NONE && sockfd < 0) { + if (listen_mode == LISTEN_KERNEL) + sockfd = udhcp_listen_socket(/*INADDR_ANY,*/ CLIENT_PORT, client_config.interface); + else + sockfd = udhcp_raw_socket(client_config.ifindex); + } + max_fd = udhcp_sp_fd_set(&rfds, sockfd); + + tv.tv_sec = timeout - already_waited_sec; + tv.tv_usec = 0; + retval = 0; /* If we already timed out, fall through, else... */ + if (tv.tv_sec > 0) { + timestamp_before_wait = (unsigned)monotonic_sec(); + DEBUG("Waiting on select..."); + retval = select(max_fd + 1, &rfds, NULL, NULL, &tv); + if (retval < 0) { + /* EINTR? A signal was caught, don't panic */ + if (errno == EINTR) + continue; + /* Else: an error occured, panic! */ + bb_perror_msg_and_die("select"); + } + } + + /* If timeout dropped to zero, time to become active: + * resend discover/renew/whatever + */ + if (retval == 0) { + /* We will restart the wait in any case */ + already_waited_sec = 0; + + switch (state) { + case INIT_SELECTING: + if (packet_num < discover_retries) { + if (packet_num == 0) + xid = random_xid(); + + send_discover(xid, requested_ip); /* broadcast */ + + timeout = discover_timeout; + packet_num++; + continue; + } + leasefail: + udhcp_run_script(NULL, "leasefail"); +#if BB_MMU /* -b is not supported on NOMMU */ + if (opt & OPT_b) { /* background if no lease */ + bb_info_msg("No lease, forking to background"); + client_background(); + /* do not background again! */ + opt = ((opt & ~OPT_b) | OPT_f); + } else +#endif + if (opt & OPT_n) { /* abort if no lease */ + bb_info_msg("No lease, failing"); + retval = 1; + goto ret; + } + /* wait before trying again */ + timeout = tryagain_timeout; + packet_num = 0; + continue; + case RENEW_REQUESTED: + case REQUESTING: + if (packet_num < discover_retries) { + /* send request packet */ + if (state == RENEW_REQUESTED) /* unicast */ + send_renew(xid, server_addr, requested_ip); + else /* broadcast */ + send_select(xid, server_addr, requested_ip); + + timeout = discover_timeout; + packet_num++; + continue; + } + /* timed out, go back to init state */ + if (state == RENEW_REQUESTED) + udhcp_run_script(NULL, "deconfig"); + change_listen_mode(LISTEN_RAW); + /* "discover...select...discover..." loops + * were seen in the wild. Treat them similarly + * to "no response to discover" case */ + if (state == REQUESTING) { + state = INIT_SELECTING; + goto leasefail; + } + state = INIT_SELECTING; + timeout = 0; + packet_num = 0; + continue; + case BOUND: + /* Half of the lease passed, time to enter renewing state */ + change_listen_mode(LISTEN_KERNEL); + DEBUG("Entering renew state"); + state = RENEWING; + /* fall right through */ + case RENEWING: + if (timeout > 60) { + /* send a request packet */ + send_renew(xid, server_addr, requested_ip); /* unicast */ + timeout >>= 1; + continue; + } + /* Timed out, enter rebinding state */ + DEBUG("Entering rebinding state"); + state = REBINDING; + /* fall right through */ + case REBINDING: + /* Lease is *really* about to run out, + * try to find DHCP server using broadcast */ + if (timeout > 0) { + /* send a request packet */ + send_renew(xid, 0 /* INADDR_ANY*/, requested_ip); /* broadcast */ + timeout >>= 1; + continue; + } + /* 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; - already is */ + packet_num = 0; + continue; + /* case RELEASED: */ + } + /* 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 it a packet? */ + if (listen_mode != LISTEN_NONE && FD_ISSET(sockfd, &rfds)) { + int len; + /* A packet is ready, read it */ + + if (listen_mode == LISTEN_KERNEL) + len = udhcp_recv_kernel_packet(&packet, sockfd); + else + len = udhcp_recv_raw_packet(&packet, sockfd); + if (len == -1) { /* error is severe, reopen socket */ + DEBUG("error on read, %s, reopening socket", strerror(errno)); + sleep(discover_timeout); /* 3 seconds by default */ + change_listen_mode(listen_mode); /* just close and reopen */ + } + /* If this packet will turn out to be unrelated/bogus, + * we will go back and wait for next one. + * Be sure timeout is properly decreased. */ + already_waited_sec += (unsigned)monotonic_sec() - timestamp_before_wait; + 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 message type from packet - ignoring"); + continue; + } + + switch (state) { + 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) { + bb_error_msg("no server ID in message"); + continue; + /* still selecting - this server looks bad */ + } + /* it IS unaligned sometimes, don't "optimize" */ + server_addr = get_unaligned_u32p((uint32_t*)temp); + xid = packet.xid; + requested_ip = packet.yiaddr; + + /* enter requesting state */ + state = REQUESTING; + timeout = 0; + packet_num = 0; + already_waited_sec = 0; + } + continue; + 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_seconds = 60 * 60; + } else { + /* it IS unaligned sometimes, don't "optimize" */ + lease_seconds = get_unaligned_u32p((uint32_t*)temp); + lease_seconds = ntohl(lease_seconds); + lease_seconds &= 0x0fffffff; /* paranoia: must not be prone to overflows */ + if (lease_seconds < 10) /* and not too small */ + lease_seconds = 10; + } +#if ENABLE_FEATURE_UDHCPC_ARPING + if (opt & OPT_a) { +/* RFC 2131 3.1 paragraph 5: + * "The client receives the DHCPACK message with configuration + * parameters. The client SHOULD perform a final check on the + * parameters (e.g., ARP for allocated network address), and notes + * the duration of the lease specified in the DHCPACK message. At this + * point, the client is configured. If the client detects that the + * address is already in use (e.g., through the use of ARP), + * the client MUST send a DHCPDECLINE message to the server and restarts + * the configuration process..." */ + if (!arpping(packet.yiaddr, + (uint32_t) 0, + client_config.arp, + client_config.interface) + ) { + bb_info_msg("offered address is in use " + "(got ARP reply), declining"); + send_decline(xid, server_addr, packet.yiaddr); + + if (state != REQUESTING) + udhcp_run_script(NULL, "deconfig"); + change_listen_mode(LISTEN_RAW); + state = INIT_SELECTING; + requested_ip = 0; + timeout = tryagain_timeout; + packet_num = 0; + already_waited_sec = 0; + continue; /* back to main loop */ + } + } +#endif + /* enter bound state */ + timeout = lease_seconds / 2; + { + struct in_addr temp_addr; + temp_addr.s_addr = packet.yiaddr; + bb_info_msg("Lease of %s obtained, lease time %u", + inet_ntoa(temp_addr), (unsigned)lease_seconds); + } + requested_ip = packet.yiaddr; + udhcp_run_script(&packet, + ((state == RENEWING || state == REBINDING) ? "renew" : "bound")); + + state = BOUND; + change_listen_mode(LISTEN_NONE); + if (opt & OPT_q) { /* quit after lease */ + if (opt & OPT_R) /* release on quit */ + perform_release(requested_ip, server_addr); + goto ret0; + } +#if BB_MMU /* NOMMU case backgrounded earlier */ + if (!(opt & OPT_f)) { + client_background(); + /* do not background again! */ + opt = ((opt & ~OPT_b) | OPT_f); + } +#endif + already_waited_sec = 0; + 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; + requested_ip = 0; + timeout = 0; + packet_num = 0; + already_waited_sec = 0; + } + continue; + /* case BOUND, RELEASED: - ignore all packets */ + } + 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: + perform_renew(); + /* start things over */ + packet_num = 0; + /* Kill any timeouts because the user wants this to hurry along */ + timeout = 0; + break; + case SIGUSR2: + perform_release(requested_ip, server_addr); + timeout = INT_MAX; + break; + case SIGTERM: + bb_info_msg("Received SIGTERM"); + if (opt & OPT_R) /* release on quit */ + perform_release(requested_ip, server_addr); + goto ret0; + } + } + } /* for (;;) - main loop ends */ + + ret0: + retval = 0; + ret: + /*if (client_config.pidfile) - remove_pidfile has its own check */ + remove_pidfile(client_config.pidfile); + return retval; +} |