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

/* vi: set sw=4 ts=4: */
/* dhcpd.c
 *
 * udhcp Server
 * Copyright (C) 1999 Matthew Ramsay <matthewr@moreton.com.au>
 *          Chris Trew <ctrew@moreton.com.au>
 *
 * Rewrite by Russ Dill <Russ.Dill@asu.edu> July 2001
 *
 * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
 */

#include <syslog.h>
#include "common.h"
#include "dhcpd.h"
#include "options.h"


/* globals */
struct dhcpOfferedAddr *leases;
struct server_config_t server_config;


int udhcpd_main(int argc, char **argv);
int udhcpd_main(int argc, char **argv)
{
    fd_set rfds;
    struct timeval tv;
    int server_socket = -1, bytes, retval, max_sock;
    struct dhcpMessage packet;
    uint8_t *state, *server_id, *requested;
    uint32_t server_id_align, requested_align, static_lease_ip;
    unsigned timeout_end;
    unsigned num_ips;
    unsigned opt;
    struct option_set *option;
    struct dhcpOfferedAddr *lease, static_lease;

    opt = getopt32(argv, "fS");
    argv += optind;

    if (!(opt & 1)) { /* no -f */
        bb_daemonize_or_rexec(0, argv);
        logmode &= ~LOGMODE_STDIO;
    }

    if (opt & 2) { /* -S */
        openlog(applet_name, LOG_PID, LOG_LOCAL0);
        logmode |= LOGMODE_SYSLOG;
    }

    /* Would rather not do read_config before daemonization -
     * otherwise NOMMU machines will parse config twice */
    read_config(argv[0] ? argv[0] : DHCPD_CONF_FILE);

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

    bb_info_msg("%s (v%s) started", applet_name, BB_VER);

    option = find_option(server_config.options, DHCP_LEASE_TIME);
    server_config.lease = LEASE_TIME;
    if (option) {
        memcpy(&server_config.lease, option->data + 2, 4);
        server_config.lease = ntohl(server_config.lease);
    }

    /* Sanity check */
    num_ips = server_config.end_ip - server_config.start_ip + 1;
    if (server_config.max_leases > num_ips) {
        bb_error_msg("max_leases=%u is too big, setting to %u",
            (unsigned)server_config.max_leases, num_ips);
        server_config.max_leases = num_ips;
    }

    leases = xzalloc(server_config.max_leases * sizeof(*leases));
    read_leases(server_config.lease_file);

    if (read_interface(server_config.interface, &server_config.ifindex,
               &server_config.server, server_config.arp)) {
        retval = 1;
        goto ret;
    }

    /* Setup the signal pipe */
    udhcp_sp_setup();

    timeout_end = monotonic_sec() + server_config.auto_time;
    while (1) { /* loop until universe collapses */

        if (server_socket < 0) {
            server_socket = listen_socket(/*INADDR_ANY,*/ SERVER_PORT,
                    server_config.interface);
        }

        max_sock = udhcp_sp_fd_set(&rfds, server_socket);
        if (server_config.auto_time) {
            tv.tv_sec = timeout_end - monotonic_sec();
            tv.tv_usec = 0;
        }
        retval = 0;
        if (!server_config.auto_time || tv.tv_sec > 0) {
            retval = select(max_sock + 1, &rfds, NULL, NULL,
                    server_config.auto_time ? &tv : NULL);
        }
        if (retval == 0) {
            write_leases();
            timeout_end = monotonic_sec() + server_config.auto_time;
            continue;
        }
        if (retval < 0 && errno != EINTR) {
            DEBUG("error on select");
            continue;
        }

        switch (udhcp_sp_read(&rfds)) {
        case SIGUSR1:
            bb_info_msg("Received a SIGUSR1");
            write_leases();
            /* why not just reset the timeout, eh */
            timeout_end = monotonic_sec() + server_config.auto_time;
            continue;
        case SIGTERM:
            bb_info_msg("Received a SIGTERM");
            goto ret0;
        case 0: break;      /* no signal */
        default: continue;  /* signal or error (probably EINTR) */
        }

        bytes = udhcp_get_packet(&packet, server_socket); /* this waits for a packet - idle */
        if (bytes < 0) {
            if (bytes == -1 && errno != EINTR) {
                DEBUG("error on read, %s, reopening socket", strerror(errno));
                close(server_socket);
                server_socket = -1;
            }
            continue;
        }

        state = get_option(&packet, DHCP_MESSAGE_TYPE);
        if (state == NULL) {
            bb_error_msg("cannot get option from packet, ignoring");
            continue;
        }

        /* Look for a static lease */
        static_lease_ip = getIpByMac(server_config.static_leases, &packet.chaddr);

        if (static_lease_ip) {
            bb_info_msg("Found static lease: %x", static_lease_ip);

            memcpy(&static_lease.chaddr, &packet.chaddr, 16);
            static_lease.yiaddr = static_lease_ip;
            static_lease.expires = 0;

            lease = &static_lease;
        } else {
            lease = find_lease_by_chaddr(packet.chaddr);
        }

        switch (state[0]) {
        case DHCPDISCOVER:
            DEBUG("Received DISCOVER");

            if (sendOffer(&packet) < 0) {
                bb_error_msg("send OFFER failed");
            }
            break;
        case DHCPREQUEST:
            DEBUG("received REQUEST");

            requested = get_option(&packet, DHCP_REQUESTED_IP);
            server_id = get_option(&packet, DHCP_SERVER_ID);

            if (requested) memcpy(&requested_align, requested, 4);
            if (server_id) memcpy(&server_id_align, server_id, 4);

            if (lease) {
                if (server_id) {
                    /* SELECTING State */
                    DEBUG("server_id = %08x", ntohl(server_id_align));
                    if (server_id_align == server_config.server && requested
                     && requested_align == lease->yiaddr
                    ) {
                        sendACK(&packet, lease->yiaddr);
                    }
                } else if (requested) {
                    /* INIT-REBOOT State */
                    if (lease->yiaddr == requested_align)
                        sendACK(&packet, lease->yiaddr);
                    else
                        sendNAK(&packet);
                } else if (lease->yiaddr == packet.ciaddr) {
                    /* RENEWING or REBINDING State */
                    sendACK(&packet, lease->yiaddr);
                } else {
                    /* don't know what to do!!!! */
                    sendNAK(&packet);
                }

            /* what to do if we have no record of the client */
            } else if (server_id) {
                /* SELECTING State */

            } else if (requested) {
                /* INIT-REBOOT State */
                lease = find_lease_by_yiaddr(requested_align);
                if (lease) {
                    if (lease_expired(lease)) {
                        /* probably best if we drop this lease */
                        memset(lease->chaddr, 0, 16);
                    /* make some contention for this address */
                    } else
                        sendNAK(&packet);
                } else {
                    uint32_t r = ntohl(requested_align);
                    if (r < server_config.start_ip
                         || r > server_config.end_ip
                    ) {
                        sendNAK(&packet);
                    }
                    /* else remain silent */
                }

            } else {
                /* RENEWING or REBINDING State */
            }
            break;
        case DHCPDECLINE:
            DEBUG("Received DECLINE");
            if (lease) {
                memset(lease->chaddr, 0, 16);
                lease->expires = time(0) + server_config.decline_time;
            }
            break;
        case DHCPRELEASE:
            DEBUG("Received RELEASE");
            if (lease)
                lease->expires = time(0);
            break;
        case DHCPINFORM:
            DEBUG("Received INFORM");
            send_inform(&packet);
            break;
        default:
            bb_info_msg("Unsupported DHCP message (%02x) - ignoring", state[0]);
        }
    }
 ret0:
    retval = 0;
 ret:
    /*if (server_config.pidfile) - server_config.pidfile is never NULL */
        remove_pidfile(server_config.pidfile);
    return retval;
}