/*
 * Copyright (c) 1997-2005 Kungliga Tekniska Högskolan
 * (Royal Institute of Technology, Stockholm, Sweden).
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * 3. Neither the name of the Institute nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include "kdc_locl.h"

/* Should we enable the HTTP hack? */
int enable_http = -1;

/* Log over requests to the KDC */
const char *request_log;

/* A string describing on what ports to listen */
const char *port_str;

krb5_addresses explicit_addresses;

size_t max_request_udp;
size_t max_request_tcp;

/*
 * a tuple describing on what to listen
 */

struct port_desc{
    int family;
    int type;
    int port;
};

/* the current ones */

static struct port_desc *ports;
static size_t num_ports;

/*
 * add `family, port, protocol' to the list with duplicate suppresion.
 */

static void
add_port(krb5_context context,
         int family, int port, const char *protocol)
{
    int type;
    size_t i;

    if(strcmp(protocol, "udp") == 0)
        type = SOCK_DGRAM;
    else if(strcmp(protocol, "tcp") == 0)
        type = SOCK_STREAM;
    else
        return;
    for(i = 0; i < num_ports; i++){
        if(ports[i].type == type
           && ports[i].port == port
           && ports[i].family == family)
            return;
    }
    ports = realloc(ports, (num_ports + 1) * sizeof(*ports));
    if (ports == NULL)
        krb5_err (context, 1, errno, "realloc");
    ports[num_ports].family = family;
    ports[num_ports].type   = type;
    ports[num_ports].port   = port;
    num_ports++;
}

/*
 * add a triple but with service -> port lookup
 * (this prints warnings for stuff that does not exist)
 */

static void
add_port_service(krb5_context context,
                 int family, const char *service, int port,
                 const char *protocol)
{
    port = krb5_getportbyname (context, service, protocol, port);
    add_port (context, family, port, protocol);
}

/*
 * add the port with service -> port lookup or string -> number
 * (no warning is printed)
 */

static void
add_port_string (krb5_context context,
                 int family, const char *str, const char *protocol)
{
    struct servent *sp;
    int port;

    sp = roken_getservbyname (str, protocol);
    if (sp != NULL) {
        port = sp->s_port;
    } else {
        char *end;

        port = htons(strtol(str, &end, 0));
        if (end == str)
            return;
    }
    add_port (context, family, port, protocol);
}

/*
 * add the standard collection of ports for `family'
 */

static void
add_standard_ports (krb5_context context,
                    krb5_kdc_configuration *config,
                    int family)
{
    add_port_service(context, family, "kerberos", 88, "udp");
    add_port_service(context, family, "kerberos", 88, "tcp");
    add_port_service(context, family, "kerberos-sec", 88, "udp");
    add_port_service(context, family, "kerberos-sec", 88, "tcp");
    if(enable_http)
        add_port_service(context, family, "http", 80, "tcp");
    if(config->enable_kx509) {
        add_port_service(context, family, "kca_service", 9878, "udp");
        add_port_service(context, family, "kca_service", 9878, "tcp");
    }

}

/*
 * parse the set of space-delimited ports in `str' and add them.
 * "+" => all the standard ones
 * otherwise it's port|service[/protocol]
 */

static void
parse_ports(krb5_context context,
            krb5_kdc_configuration *config,
            const char *str)
{
    char *pos = NULL;
    char *p;
    char *str_copy = strdup (str);

    p = strtok_r(str_copy, " \t", &pos);
    while(p != NULL) {
        if(strcmp(p, "+") == 0) {
#ifdef HAVE_IPV6
            add_standard_ports(context, config, AF_INET6);
#endif
            add_standard_ports(context, config, AF_INET);
        } else {
            char *q = strchr(p, '/');
            if(q){
                *q++ = 0;
#ifdef HAVE_IPV6
                add_port_string(context, AF_INET6, p, q);
#endif
                add_port_string(context, AF_INET, p, q);
            }else {
#ifdef HAVE_IPV6
                add_port_string(context, AF_INET6, p, "udp");
                add_port_string(context, AF_INET6, p, "tcp");
#endif
                add_port_string(context, AF_INET, p, "udp");
                add_port_string(context, AF_INET, p, "tcp");
            }
        }

        p = strtok_r(NULL, " \t", &pos);
    }
    free (str_copy);
}

/*
 * every socket we listen on
 */

struct descr {
    krb5_socket_t s;
    int type;
    int port;
    unsigned char *buf;
    size_t size;
    size_t len;
    time_t timeout;
    struct sockaddr_storage __ss;
    struct sockaddr *sa;
    socklen_t sock_len;
    char addr_string[128];
};

static void
init_descr(struct descr *d)
{
    memset(d, 0, sizeof(*d));
    d->sa = (struct sockaddr *)&d->__ss;
    d->s = rk_INVALID_SOCKET;
}

/*
 * re-initialize all `n' ->sa in `d'.
 */

static void
reinit_descrs (struct descr *d, int n)
{
    int i;

    for (i = 0; i < n; ++i)
        d[i].sa = (struct sockaddr *)&d[i].__ss;
}

/*
 * Create the socket (family, type, port) in `d'
 */

static void
init_socket(krb5_context context,
            krb5_kdc_configuration *config,
            struct descr *d, krb5_address *a, int family, int type, int port)
{
    krb5_error_code ret;
    struct sockaddr_storage __ss;
    struct sockaddr *sa = (struct sockaddr *)&__ss;
    krb5_socklen_t sa_size = sizeof(__ss);

    init_descr (d);

    ret = krb5_addr2sockaddr (context, a, sa, &sa_size, port);
    if (ret) {
        krb5_warn(context, ret, "krb5_addr2sockaddr");
        rk_closesocket(d->s);
        d->s = rk_INVALID_SOCKET;
        return;
    }

    if (sa->sa_family != family)
        return;

    d->s = socket(family, type, 0);
    if(rk_IS_BAD_SOCKET(d->s)){
        krb5_warn(context, errno, "socket(%d, %d, 0)", family, type);
        d->s = rk_INVALID_SOCKET;
        return;
    }
#if defined(HAVE_SETSOCKOPT) && defined(SOL_SOCKET) && defined(SO_REUSEADDR)
    {
        int one = 1;
        setsockopt(d->s, SOL_SOCKET, SO_REUSEADDR, (void *)&one, sizeof(one));
    }
#endif
    d->type = type;
    d->port = port;

    if(rk_IS_SOCKET_ERROR(bind(d->s, sa, sa_size))){
        char a_str[256];
        size_t len;

        krb5_print_address (a, a_str, sizeof(a_str), &len);
        krb5_warn(context, errno, "bind %s/%d", a_str, ntohs(port));
        rk_closesocket(d->s);
        d->s = rk_INVALID_SOCKET;
        return;
    }
    if(type == SOCK_STREAM && rk_IS_SOCKET_ERROR(listen(d->s, SOMAXCONN))){
        char a_str[256];
        size_t len;

        krb5_print_address (a, a_str, sizeof(a_str), &len);
        krb5_warn(context, errno, "listen %s/%d", a_str, ntohs(port));
        rk_closesocket(d->s);
        d->s = rk_INVALID_SOCKET;
        return;
    }
}

/*
 * Allocate descriptors for all the sockets that we should listen on
 * and return the number of them.
 */

static int
init_sockets(krb5_context context,
             krb5_kdc_configuration *config,
             struct descr **desc)
{
    krb5_error_code ret;
    size_t i, j;
    struct descr *d;
    int num = 0;
    krb5_addresses addresses;

    if (explicit_addresses.len) {
        addresses = explicit_addresses;
    } else {
        ret = krb5_get_all_server_addrs (context, &addresses);
        if (ret)
            krb5_err (context, 1, ret, "krb5_get_all_server_addrs");
    }
    parse_ports(context, config, port_str);
    d = malloc(addresses.len * num_ports * sizeof(*d));
    if (d == NULL)
        krb5_errx(context, 1, "malloc(%lu) failed",
                  (unsigned long)num_ports * sizeof(*d));

    for (i = 0; i < num_ports; i++){
        for (j = 0; j < addresses.len; ++j) {
            init_socket(context, config, &d[num], &addresses.val[j],
                        ports[i].family, ports[i].type, ports[i].port);
            if(d[num].s != rk_INVALID_SOCKET){
                char a_str[80];
                size_t len;

                krb5_print_address (&addresses.val[j], a_str,
                                    sizeof(a_str), &len);

                kdc_log(context, config, 5, "listening on %s port %u/%s",
                        a_str,
                        ntohs(ports[i].port),
                        (ports[i].type == SOCK_STREAM) ? "tcp" : "udp");
                /* XXX */
                num++;
            }
        }
    }
    krb5_free_addresses (context, &addresses);
    d = realloc(d, num * sizeof(*d));
    if (d == NULL && num != 0)
        krb5_errx(context, 1, "realloc(%lu) failed",
                  (unsigned long)num * sizeof(*d));
    reinit_descrs (d, num);
    *desc = d;
    return num;
}

/*
 *
 */

static const char *
descr_type(struct descr *d)
{
    if (d->type == SOCK_DGRAM)
        return "udp";
    else if (d->type == SOCK_STREAM)
        return "tcp";
    return "unknown";
}

static void
addr_to_string(krb5_context context,
               struct sockaddr *addr, size_t addr_len, char *str, size_t len)
{
    krb5_address a;
    if(krb5_sockaddr2address(context, addr, &a) == 0) {
        if(krb5_print_address(&a, str, len, &len) == 0) {
            krb5_free_address(context, &a);
            return;
        }
        krb5_free_address(context, &a);
    }
    snprintf(str, len, "<family=%d>", addr->sa_family);
}

/*
 *
 */

static void
send_reply(krb5_context context,
           krb5_kdc_configuration *config,
           krb5_boolean prependlength,
           struct descr *d,
           krb5_data *reply)
{
    kdc_log(context, config, 5,
            "sending %lu bytes to %s", (unsigned long)reply->length,
            d->addr_string);
    if(prependlength){
        unsigned char l[4];
        l[0] = (reply->length >> 24) & 0xff;
        l[1] = (reply->length >> 16) & 0xff;
        l[2] = (reply->length >> 8) & 0xff;
        l[3] = reply->length & 0xff;
        if(rk_IS_SOCKET_ERROR(sendto(d->s, l, sizeof(l), 0, d->sa, d->sock_len))) {
            kdc_log (context, config,
                     0, "sendto(%s): %s", d->addr_string,
                     strerror(rk_SOCK_ERRNO));
            return;
        }
    }
    if(rk_IS_SOCKET_ERROR(sendto(d->s, reply->data, reply->length, 0, d->sa, d->sock_len))) {
        kdc_log (context, config, 0, "sendto(%s): %s", d->addr_string,
                 strerror(rk_SOCK_ERRNO));
        return;
    }
}

/*
 * Handle the request in `buf, len' to socket `d'
 */

static void
do_request(krb5_context context,
           krb5_kdc_configuration *config,
           void *buf, size_t len, krb5_boolean prependlength,
           struct descr *d)
{
    krb5_error_code ret;
    krb5_data reply;
    int datagram_reply = (d->type == SOCK_DGRAM);

    krb5_kdc_update_time(NULL);

    krb5_data_zero(&reply);
    ret = krb5_kdc_process_request(context, config,
                                   buf, len, &reply, &prependlength,
                                   d->addr_string, d->sa,
                                   datagram_reply);
    if(request_log)
        krb5_kdc_save_request(context, request_log, buf, len, &reply, d->sa);
    if(reply.length){
        send_reply(context, config, prependlength, d, &reply);
        krb5_data_free(&reply);
    }
    if(ret)
        kdc_log(context, config, 0,
                "Failed processing %lu byte request from %s",
                (unsigned long)len, d->addr_string);
}

/*
 * Handle incoming data to the UDP socket in `d'
 */

static void
handle_udp(krb5_context context,
           krb5_kdc_configuration *config,
           struct descr *d)
{
    unsigned char *buf;
    ssize_t n;

    buf = malloc(max_request_udp);
    if(buf == NULL){
        kdc_log(context, config, 0, "Failed to allocate %lu bytes", (unsigned long)max_request_udp);
        return;
    }

    d->sock_len = sizeof(d->__ss);
    n = recvfrom(d->s, buf, max_request_udp, 0, d->sa, &d->sock_len);
    if(rk_IS_SOCKET_ERROR(n))
        krb5_warn(context, rk_SOCK_ERRNO, "recvfrom");
    else {
        addr_to_string (context, d->sa, d->sock_len,
                        d->addr_string, sizeof(d->addr_string));
        if ((size_t)n == max_request_udp) {
            krb5_data data;
            krb5_warn(context, errno,
                      "recvfrom: truncated packet from %s, asking for TCP",
                      d->addr_string);
            krb5_mk_error(context,
                          KRB5KRB_ERR_RESPONSE_TOO_BIG,
                          NULL,
                          NULL,
                          NULL,
                          NULL,
                          NULL,
                          NULL,
                          &data);
            send_reply(context, config, FALSE, d, &data);
            krb5_data_free(&data);
        } else {
            do_request(context, config, buf, n, FALSE, d);
        }
    }
    free (buf);
}

static void
clear_descr(struct descr *d)
{
    if(d->buf)
        memset(d->buf, 0, d->size);
    d->len = 0;
    if(d->s != rk_INVALID_SOCKET)
        rk_closesocket(d->s);
    d->s = rk_INVALID_SOCKET;
}


/* remove HTTP %-quoting from buf */
static int
de_http(char *buf)
{
    unsigned char *p, *q;
    for(p = q = (unsigned char *)buf; *p; p++, q++) {
        if(*p == '%' && isxdigit(p[1]) && isxdigit(p[2])) {
            unsigned int x;
            if(sscanf((char *)p + 1, "%2x", &x) != 1)
                return -1;
            *q = x;
            p += 2;
        } else
            *q = *p;
    }
    *q = '\0';
    return 0;
}

#define TCP_TIMEOUT 4

/*
 * accept a new TCP connection on `d[parent]' and store it in `d[child]'
 */

static void
add_new_tcp (krb5_context context,
             krb5_kdc_configuration *config,
             struct descr *d, int parent, int child)
{
    krb5_socket_t s;

    if (child == -1)
        return;

    d[child].sock_len = sizeof(d[child].__ss);
    s = accept(d[parent].s, d[child].sa, &d[child].sock_len);
    if(rk_IS_BAD_SOCKET(s)) {
        krb5_warn(context, rk_SOCK_ERRNO, "accept");
        return;
    }

#ifdef FD_SETSIZE
    if (s >= FD_SETSIZE) {
        krb5_warnx(context, "socket FD too large");
        rk_closesocket (s);
        return;
    }
#endif

    d[child].s = s;
    d[child].timeout = time(NULL) + TCP_TIMEOUT;
    d[child].type = SOCK_STREAM;
    addr_to_string (context,
                    d[child].sa, d[child].sock_len,
                    d[child].addr_string, sizeof(d[child].addr_string));
}

/*
 * Grow `d' to handle at least `n'.
 * Return != 0 if fails
 */

static int
grow_descr (krb5_context context,
            krb5_kdc_configuration *config,
            struct descr *d, size_t n)
{
    if (d->size - d->len < n) {
        unsigned char *tmp;
        size_t grow;

        grow = max(1024, d->len + n);
        if (d->size + grow > max_request_tcp) {
            kdc_log(context, config, 0, "Request exceeds max request size (%lu bytes).",
                    (unsigned long)d->size + grow);
            clear_descr(d);
            return -1;
        }
        tmp = realloc (d->buf, d->size + grow);
        if (tmp == NULL) {
            kdc_log(context, config, 0, "Failed to re-allocate %lu bytes.",
                    (unsigned long)d->size + grow);
            clear_descr(d);
            return -1;
        }
        d->size += grow;
        d->buf = tmp;
    }
    return 0;
}

/*
 * Try to handle the TCP data at `d->buf, d->len'.
 * Return -1 if failed, 0 if succesful, and 1 if data is complete.
 */

static int
handle_vanilla_tcp (krb5_context context,
                    krb5_kdc_configuration *config,
                    struct descr *d)
{
    krb5_storage *sp;
    uint32_t len;

    sp = krb5_storage_from_mem(d->buf, d->len);
    if (sp == NULL) {
        kdc_log (context, config, 0, "krb5_storage_from_mem failed");
        return -1;
    }
    krb5_ret_uint32(sp, &len);
    krb5_storage_free(sp);
    if(d->len - 4 >= len) {
        memmove(d->buf, d->buf + 4, d->len - 4);
        d->len -= 4;
        return 1;
    }
    return 0;
}

/*
 * Try to handle the TCP/HTTP data at `d->buf, d->len'.
 * Return -1 if failed, 0 if succesful, and 1 if data is complete.
 */

static int
handle_http_tcp (krb5_context context,
                 krb5_kdc_configuration *config,
                 struct descr *d)
{
    char *s, *p, *t;
    void *data;
    char *proto;
    int len;

    s = (char *)d->buf;

    /* If its a multi line query, truncate off the first line */
    p = strstr(s, "\r\n");
    if (p)
        *p = 0;

    p = NULL;
    t = strtok_r(s, " \t", &p);
    if (t == NULL) {
        kdc_log(context, config, 0,
                "Missing HTTP operand (GET) request from %s", d->addr_string);
        return -1;
    }

    t = strtok_r(NULL, " \t", &p);
    if(t == NULL) {
        kdc_log(context, config, 0,
                "Missing HTTP GET data in request from %s", d->addr_string);
        return -1;
    }

    data = malloc(strlen(t));
    if (data == NULL) {
        kdc_log(context, config, 0, "Failed to allocate %lu bytes",
                (unsigned long)strlen(t));
        return -1;
    }
    if(*t == '/')
        t++;
    if(de_http(t) != 0) {
        kdc_log(context, config, 0, "Malformed HTTP request from %s", d->addr_string);
        kdc_log(context, config, 5, "HTTP request: %s", t);
        free(data);
        return -1;
    }
    proto = strtok_r(NULL, " \t", &p);
    if (proto == NULL) {
        kdc_log(context, config, 0, "Malformed HTTP request from %s", d->addr_string);
        free(data);
        return -1;
    }
    len = base64_decode(t, data);
    if(len <= 0){
        const char *msg =
            " 404 Not found\r\n"
            "Server: Heimdal/" VERSION "\r\n"
            "Cache-Control: no-cache\r\n"
            "Pragma: no-cache\r\n"
            "Content-type: text/html\r\n"
            "Content-transfer-encoding: 8bit\r\n\r\n"
            "<TITLE>404 Not found</TITLE>\r\n"
            "<H1>404 Not found</H1>\r\n"
            "That page doesn't exist, maybe you are looking for "
            "<A HREF=\"http://www.h5l.org/\">Heimdal</A>?\r\n";
        kdc_log(context, config, 0, "HTTP request from %s is non KDC request", d->addr_string);
        kdc_log(context, config, 5, "HTTP request: %s", t);
        free(data);
        if (rk_IS_SOCKET_ERROR(send(d->s, proto, strlen(proto), 0))) {
            kdc_log(context, config, 0, "HTTP write failed: %s: %s",
                    d->addr_string, strerror(rk_SOCK_ERRNO));
            return -1;
        }
        if (rk_IS_SOCKET_ERROR(send(d->s, msg, strlen(msg), 0))) {
            kdc_log(context, config, 0, "HTTP write failed: %s: %s",
                    d->addr_string, strerror(rk_SOCK_ERRNO));
            return -1;
        }
        return -1;
    }
    {
        const char *msg =
            " 200 OK\r\n"
            "Server: Heimdal/" VERSION "\r\n"
            "Cache-Control: no-cache\r\n"
            "Pragma: no-cache\r\n"
            "Content-type: application/octet-stream\r\n"
            "Content-transfer-encoding: binary\r\n\r\n";
        if (rk_IS_SOCKET_ERROR(send(d->s, proto, strlen(proto), 0))) {
            free(data);
            kdc_log(context, config, 0, "HTTP write failed: %s: %s",
                    d->addr_string, strerror(rk_SOCK_ERRNO));
            return -1;
        }
        if (rk_IS_SOCKET_ERROR(send(d->s, msg, strlen(msg), 0))) {
            free(data);
            kdc_log(context, config, 0, "HTTP write failed: %s: %s",
                    d->addr_string, strerror(rk_SOCK_ERRNO));
            return -1;
        }
    }
    if ((size_t)len > d->len)
        len = d->len;
    memcpy(d->buf, data, len);
    d->len = len;
    free(data);
    return 1;
}

/*
 * Handle incoming data to the TCP socket in `d[index]'
 */

static void
handle_tcp(krb5_context context,
           krb5_kdc_configuration *config,
           struct descr *d, int idx, int min_free)
{
    unsigned char buf[1024];
    int n;
    int ret = 0;

    if (d[idx].timeout == 0) {
        add_new_tcp (context, config, d, idx, min_free);
        return;
    }

    n = recvfrom(d[idx].s, buf, sizeof(buf), 0, NULL, NULL);
    if(rk_IS_SOCKET_ERROR(n)){
        krb5_warn(context, rk_SOCK_ERRNO, "recvfrom failed from %s to %s/%d",
                  d[idx].addr_string, descr_type(d + idx),
                  ntohs(d[idx].port));
        return;
    } else if (n == 0) {
        krb5_warnx(context, "connection closed before end of data after %lu "
                   "bytes from %s to %s/%d", (unsigned long)d[idx].len,
                   d[idx].addr_string, descr_type(d + idx),
                   ntohs(d[idx].port));
        clear_descr (d + idx);
        return;
    }
    if (grow_descr (context, config, &d[idx], n))
        return;
    memcpy(d[idx].buf + d[idx].len, buf, n);
    d[idx].len += n;
    if(d[idx].len > 4 && d[idx].buf[0] == 0) {
        ret = handle_vanilla_tcp (context, config, &d[idx]);
    } else if(enable_http &&
              d[idx].len >= 4 &&
              strncmp((char *)d[idx].buf, "GET ", 4) == 0 &&
              strncmp((char *)d[idx].buf + d[idx].len - 4,
                      "\r\n\r\n", 4) == 0) {

        /* remove the trailing \r\n\r\n so the string is NUL terminated */
        d[idx].buf[d[idx].len - 4] = '\0';

        ret = handle_http_tcp (context, config, &d[idx]);
        if (ret < 0)
            clear_descr (d + idx);
    } else if (d[idx].len > 4) {
        kdc_log (context, config,
                 0, "TCP data of strange type from %s to %s/%d",
                 d[idx].addr_string, descr_type(d + idx),
                 ntohs(d[idx].port));
        if (d[idx].buf[0] & 0x80) {
            krb5_data reply;

            kdc_log (context, config, 0, "TCP extension not supported");

            ret = krb5_mk_error(context,
                                KRB5KRB_ERR_FIELD_TOOLONG,
                                NULL,
                                NULL,
                                NULL,
                                NULL,
                                NULL,
                                NULL,
                                &reply);
            if (ret == 0) {
                send_reply(context, config, TRUE, d + idx, &reply);
                krb5_data_free(&reply);
            }
        }
        clear_descr(d + idx);
        return;
    }
    if (ret < 0)
        return;
    else if (ret == 1) {
        do_request(context, config,
                   d[idx].buf, d[idx].len, TRUE, &d[idx]);
        clear_descr(d + idx);
    }
}

void
loop(krb5_context context,
     krb5_kdc_configuration *config)
{
    struct descr *d;
    unsigned int ndescr;

    ndescr = init_sockets(context, config, &d);
    if(ndescr <= 0)
        krb5_errx(context, 1, "No sockets!");
    kdc_log(context, config, 0, "KDC started");
    while(exit_flag == 0){
        struct timeval tmout;
        fd_set fds;
        int min_free = -1;
        int max_fd = 0;
        size_t i;

        FD_ZERO(&fds);
        for(i = 0; i < ndescr; i++) {
            if(!rk_IS_BAD_SOCKET(d[i].s)){
                if(d[i].type == SOCK_STREAM &&
                   d[i].timeout && d[i].timeout < time(NULL)) {
                    kdc_log(context, config, 1,
                            "TCP-connection from %s expired after %lu bytes",
                            d[i].addr_string, (unsigned long)d[i].len);
                    clear_descr(&d[i]);
                    continue;
                }
#ifndef NO_LIMIT_FD_SETSIZE
                if(max_fd < d[i].s)
                    max_fd = d[i].s;
#ifdef FD_SETSIZE
                if (max_fd >= FD_SETSIZE)
                    krb5_errx(context, 1, "fd too large");
#endif
#endif
                FD_SET(d[i].s, &fds);
            } else if(min_free < 0 || i < (size_t)min_free)
                min_free = i;
        }
        if(min_free == -1){
            struct descr *tmp;
            tmp = realloc(d, (ndescr + 4) * sizeof(*d));
            if(tmp == NULL)
                krb5_warnx(context, "No memory");
            else {
                d = tmp;
                reinit_descrs (d, ndescr);
                memset(d + ndescr, 0, 4 * sizeof(*d));
                for(i = ndescr; i < ndescr + 4; i++)
                    init_descr (&d[i]);
                min_free = ndescr;
                ndescr += 4;
            }
        }

        tmout.tv_sec = TCP_TIMEOUT;
        tmout.tv_usec = 0;
        switch(select(max_fd + 1, &fds, 0, 0, &tmout)){
        case 0:
            break;
        case -1:
            if (errno != EINTR)
                krb5_warn(context, rk_SOCK_ERRNO, "select");
            break;
        default:
            for(i = 0; i < ndescr; i++)
                if(!rk_IS_BAD_SOCKET(d[i].s) && FD_ISSET(d[i].s, &fds)) {
                    if(d[i].type == SOCK_DGRAM)
                        handle_udp(context, config, &d[i]);
                    else if(d[i].type == SOCK_STREAM)
                        handle_tcp(context, config, d, i, min_free);
                }
        }
    }
    if (0);
#ifdef SIGXCPU
    else if(exit_flag == SIGXCPU)
        kdc_log(context, config, 0, "CPU time limit exceeded");
#endif
    else if(exit_flag == SIGINT || exit_flag == SIGTERM)
        kdc_log(context, config, 0, "Terminated");
    else
        kdc_log(context, config, 0, "Unexpected exit reason: %d", exit_flag);
    free (d);
}