source: MondoRescue/branches/stable/mindi-busybox/networking/udhcp/dhcpc.c@ 1770

/* 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 <getopt.h>
#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"


/* 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)
{
#if !BB_MMU
    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 */
    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; /* what a wonderful names */
    unsigned start = 0;
    unsigned now;
    unsigned opt;
    int max_fd;
    int retval;
    int len;
    struct timeval tv;
    struct in_addr temp_addr;
    struct dhcpMessage packet;
    fd_set rfds;

    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,
        OPT_S = 1 << 18,
    };
#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"
        "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"
        "syslog\0"        No_argument       "S"
        ;
#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(argv, "c:CV:fbH:h:F:i:np:qRr:s:T:t:vS",
        &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)
    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", BB_VER);
        return 0;
    }

    if (opt & OPT_S) {
        openlog(applet_name, LOG_PID, LOG_LOCAL0);
        logmode |= LOGMODE_SYSLOG;
    }

    if (read_interface(client_config.interface, &client_config.ifindex,
               NULL, client_config.arp))
        return 1;

    /* 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);
    /* if (!..) bb_perror_msg("cannot create pidfile %s", pidfile); */

    /* Goes to stdout and possibly syslog */
    bb_info_msg("%s (v%s) started", applet_name, BB_VER);

    /* 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_mode(LISTEN_RAW);
    tv.tv_sec = 0;
    goto jump_in;

    for (;;) {
        tv.tv_sec = timeout - monotonic_sec();
 jump_in:
        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);

        retval = 0; /* If we already timed out, fall through, else... */
        if (tv.tv_sec > 0) {
            DEBUG("Waiting on select...");
            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 */
            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 = start + t1;
                }
                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 = start + t2;
                }
                break;
            case RELEASED:
                /* yah, I know, *you* say it would never happen */
                timeout = INT_MAX;
                break;
            }
        } else 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);
            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 = start + t1;
                    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 {
            int signo = udhcp_sp_read(&rfds);
            switch (signo) {
            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;
            }
        }
    } /* for (;;) */
 ret0:
    retval = 0;
 ret:
    /*if (client_config.pidfile) - remove_pidfile has it's own check */
        remove_pidfile(client_config.pidfile);
    return retval;
}