source: MondoRescue/branches/3.3/mindi-busybox/networking/udhcp/files.c@ 3621

/* vi: set sw=4 ts=4: */
/*
 * DHCP server config and lease file manipulation
 *
 * Rewrite by Russ Dill <Russ.Dill@asu.edu> July 2001
 *
 * Licensed under GPLv2, see file LICENSE in this source tree.
 */
#include <netinet/ether.h>

#include "common.h"
#include "dhcpd.h"

/* on these functions, make sure your datatype matches */
static int FAST_FUNC read_str(const char *line, void *arg)
{
    char **dest = arg;

    free(*dest);
    *dest = xstrdup(line);
    return 1;
}

static int FAST_FUNC read_u32(const char *line, void *arg)
{
    *(uint32_t*)arg = bb_strtou32(line, NULL, 10);
    return errno == 0;
}

static int FAST_FUNC read_staticlease(const char *const_line, void *arg)
{
    char *line;
    char *mac_string;
    char *ip_string;
    struct ether_addr mac_bytes; /* it's "struct { uint8_t mac[6]; }" */
    uint32_t nip;

    /* Read mac */
    line = (char *) const_line;
    mac_string = strtok_r(line, " \t", &line);
    if (!mac_string || !ether_aton_r(mac_string, &mac_bytes))
        return 0;

    /* Read ip */
    ip_string = strtok_r(NULL, " \t", &line);
    if (!ip_string || !udhcp_str2nip(ip_string, &nip))
        return 0;

    add_static_lease(arg, (uint8_t*) &mac_bytes, nip);

    log_static_leases(arg);

    return 1;
}


struct config_keyword {
    const char *keyword;
    int (*handler)(const char *line, void *var) FAST_FUNC;
    unsigned ofs;
    const char *def;
};

#define OFS(field) offsetof(struct server_config_t, field)

static const struct config_keyword keywords[] = {
    /* keyword        handler           variable address               default */
    {"start"        , udhcp_str2nip   , OFS(start_ip     ), "192.168.0.20"},
    {"end"          , udhcp_str2nip   , OFS(end_ip       ), "192.168.0.254"},
    {"interface"    , read_str        , OFS(interface    ), "eth0"},
    /* Avoid "max_leases value not sane" warning by setting default
     * to default_end_ip - default_start_ip + 1: */
    {"max_leases"   , read_u32        , OFS(max_leases   ), "235"},
    {"auto_time"    , read_u32        , OFS(auto_time    ), "7200"},
    {"decline_time" , read_u32        , OFS(decline_time ), "3600"},
    {"conflict_time", read_u32        , OFS(conflict_time), "3600"},
    {"offer_time"   , read_u32        , OFS(offer_time   ), "60"},
    {"min_lease"    , read_u32        , OFS(min_lease_sec), "60"},
    {"lease_file"   , read_str        , OFS(lease_file   ), LEASES_FILE},
    {"pidfile"      , read_str        , OFS(pidfile      ), "/var/run/udhcpd.pid"},
    {"siaddr"       , udhcp_str2nip   , OFS(siaddr_nip   ), "0.0.0.0"},
    /* keywords with no defaults must be last! */
    {"option"       , udhcp_str2optset, OFS(options      ), ""},
    {"opt"          , udhcp_str2optset, OFS(options      ), ""},
    {"notify_file"  , read_str        , OFS(notify_file  ), NULL},
    {"sname"        , read_str        , OFS(sname        ), NULL},
    {"boot_file"    , read_str        , OFS(boot_file    ), NULL},
    {"static_lease" , read_staticlease, OFS(static_leases), ""},
};
enum { KWS_WITH_DEFAULTS = ARRAY_SIZE(keywords) - 6 };

void FAST_FUNC read_config(const char *file)
{
    parser_t *parser;
    const struct config_keyword *k;
    unsigned i;
    char *token[2];

    for (i = 0; i < KWS_WITH_DEFAULTS; i++)
        keywords[i].handler(keywords[i].def, (char*)&server_config + keywords[i].ofs);

    parser = config_open(file);
    while (config_read(parser, token, 2, 2, "# \t", PARSE_NORMAL)) {
        for (k = keywords, i = 0; i < ARRAY_SIZE(keywords); k++, i++) {
            if (strcasecmp(token[0], k->keyword) == 0) {
                if (!k->handler(token[1], (char*)&server_config + k->ofs)) {
                    bb_error_msg("can't parse line %u in %s",
                            parser->lineno, file);
                    /* reset back to the default value */
                    k->handler(k->def, (char*)&server_config + k->ofs);
                }
                break;
            }
        }
    }
    config_close(parser);

    server_config.start_ip = ntohl(server_config.start_ip);
    server_config.end_ip = ntohl(server_config.end_ip);
}

void FAST_FUNC write_leases(void)
{
    int fd;
    unsigned i;
    leasetime_t curr;
    int64_t written_at;

    fd = open_or_warn(server_config.lease_file, O_WRONLY|O_CREAT|O_TRUNC);
    if (fd < 0)
        return;

    curr = written_at = time(NULL);

    written_at = SWAP_BE64(written_at);
    full_write(fd, &written_at, sizeof(written_at));

    for (i = 0; i < server_config.max_leases; i++) {
        leasetime_t tmp_time;

        if (g_leases[i].lease_nip == 0)
            continue;

        /* Screw with the time in the struct, for easier writing */
        tmp_time = g_leases[i].expires;

        g_leases[i].expires -= curr;
        if ((signed_leasetime_t) g_leases[i].expires < 0)
            g_leases[i].expires = 0;
        g_leases[i].expires = htonl(g_leases[i].expires);

        /* No error check. If the file gets truncated,
         * we lose some leases on restart. Oh well. */
        full_write(fd, &g_leases[i], sizeof(g_leases[i]));

        /* Then restore it when done */
        g_leases[i].expires = tmp_time;
    }
    close(fd);

    if (server_config.notify_file) {
        char *argv[3];
        argv[0] = server_config.notify_file;
        argv[1] = server_config.lease_file;
        argv[2] = NULL;
        spawn_and_wait(argv);
    }
}

void FAST_FUNC read_leases(const char *file)
{
    struct dyn_lease lease;
    int64_t written_at, time_passed;
    int fd;
#if defined CONFIG_UDHCP_DEBUG && CONFIG_UDHCP_DEBUG >= 1
    unsigned i = 0;
#endif

    fd = open_or_warn(file, O_RDONLY);
    if (fd < 0)
        return;

    if (full_read(fd, &written_at, sizeof(written_at)) != sizeof(written_at))
        goto ret;
    written_at = SWAP_BE64(written_at);

    time_passed = time(NULL) - written_at;
    /* Strange written_at, or lease file from old version of udhcpd
     * which had no "written_at" field? */
    if ((uint64_t)time_passed > 12 * 60 * 60)
        goto ret;

    while (full_read(fd, &lease, sizeof(lease)) == sizeof(lease)) {
        uint32_t y = ntohl(lease.lease_nip);
        if (y >= server_config.start_ip && y <= server_config.end_ip) {
            signed_leasetime_t expires = ntohl(lease.expires) - (signed_leasetime_t)time_passed;
            uint32_t static_nip;

            if (expires <= 0)
                /* We keep expired leases: add_lease() will add
                 * a lease with 0 seconds remaining.
                 * Fewer IP address changes this way for mass reboot scenario.
                 */
                expires = 0;

            /* Check if there is a different static lease for this IP or MAC */
            static_nip = get_static_nip_by_mac(server_config.static_leases, lease.lease_mac);
            if (static_nip) {
                /* NB: we do not add lease even if static_nip == lease.lease_nip.
                 */
                continue;
            }
            if (is_nip_reserved(server_config.static_leases, lease.lease_nip))
                continue;

            /* NB: add_lease takes "relative time", IOW,
             * lease duration, not lease deadline. */
            if (add_lease(lease.lease_mac, lease.lease_nip,
                    expires,
                    lease.hostname, sizeof(lease.hostname)
                ) == 0
            ) {
                bb_error_msg("too many leases while loading %s", file);
                break;
            }
#if defined CONFIG_UDHCP_DEBUG && CONFIG_UDHCP_DEBUG >= 1
            i++;
#endif
        }
    }
    log1("read %d leases", i);
 ret:
    close(fd);
}