/* 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;
        void *var;
        const char *def;
};

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

        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], k->var)) {
                                        bb_error_msg("can't parse line %u in %s",
                                                        parser->lineno, file);
                                        /* reset back to the default value */
                                        k->handler(k->def, k->var);
                                }
                                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)) {
//FIXME: what if it matches some static 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;
                        if (expires <= 0)
                                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);
}