/*
 * 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 "krb5_locl.h"

#undef __attribute__
#define __attribute__(X)


static void
str2data (krb5_data *d,
          const char *fmt,
          ...) __attribute__ ((format (printf, 2, 3)));

static void
str2data (krb5_data *d,
          const char *fmt,
          ...)
{
    va_list args;
    char *str;

    va_start(args, fmt);
    d->length = vasprintf (&str, fmt, args);
    va_end(args);
    d->data = str;
}

/*
 * Change password protocol defined by
 * draft-ietf-cat-kerb-chg-password-02.txt
 *
 * Share the response part of the protocol with MS set password
 * (RFC3244)
 */

static krb5_error_code
chgpw_send_request (krb5_context context,
                    krb5_auth_context *auth_context,
                    krb5_creds *creds,
                    krb5_principal targprinc,
                    int is_stream,
                    rk_socket_t sock,
                    const char *passwd,
                    const char *host)
{
    krb5_error_code ret;
    krb5_data ap_req_data;
    krb5_data krb_priv_data;
    krb5_data passwd_data;
    size_t len;
    u_char header[6];
    struct iovec iov[3];
    struct msghdr msghdr;

    if (is_stream)
        return KRB5_KPASSWD_MALFORMED;

    if (targprinc &&
        krb5_principal_compare(context, creds->client, targprinc) != TRUE)
        return KRB5_KPASSWD_MALFORMED;

    krb5_data_zero (&ap_req_data);

    ret = krb5_mk_req_extended (context,
                                auth_context,
                                AP_OPTS_MUTUAL_REQUIRED | AP_OPTS_USE_SUBKEY,
                                NULL, /* in_data */
                                creds,
                                &ap_req_data);
    if (ret)
        return ret;

    passwd_data.data   = rk_UNCONST(passwd);
    passwd_data.length = strlen(passwd);

    krb5_data_zero (&krb_priv_data);

    ret = krb5_mk_priv (context,
                        *auth_context,
                        &passwd_data,
                        &krb_priv_data,
                        NULL);
    if (ret)
        goto out2;

    len = 6 + ap_req_data.length + krb_priv_data.length;
    header[0] = (len >> 8) & 0xFF;
    header[1] = (len >> 0) & 0xFF;
    header[2] = 0;
    header[3] = 1;
    header[4] = (ap_req_data.length >> 8) & 0xFF;
    header[5] = (ap_req_data.length >> 0) & 0xFF;

    memset(&msghdr, 0, sizeof(msghdr));
    msghdr.msg_name       = NULL;
    msghdr.msg_namelen    = 0;
    msghdr.msg_iov        = iov;
    msghdr.msg_iovlen     = sizeof(iov)/sizeof(*iov);
#if 0
    msghdr.msg_control    = NULL;
    msghdr.msg_controllen = 0;
#endif

    iov[0].iov_base    = (void*)header;
    iov[0].iov_len     = 6;
    iov[1].iov_base    = ap_req_data.data;
    iov[1].iov_len     = ap_req_data.length;
    iov[2].iov_base    = krb_priv_data.data;
    iov[2].iov_len     = krb_priv_data.length;

    if (rk_IS_SOCKET_ERROR( sendmsg (sock, &msghdr, 0) )) {
        ret = rk_SOCK_ERRNO;
        krb5_set_error_message(context, ret, "sendmsg %s: %s",
                               host, strerror(ret));
    }

    krb5_data_free (&krb_priv_data);
out2:
    krb5_data_free (&ap_req_data);
    return ret;
}

/*
 * Set password protocol as defined by RFC3244 --
 * Microsoft Windows 2000 Kerberos Change Password and Set Password Protocols
 */

static krb5_error_code
setpw_send_request (krb5_context context,
                    krb5_auth_context *auth_context,
                    krb5_creds *creds,
                    krb5_principal targprinc,
                    int is_stream,
                    rk_socket_t sock,
                    const char *passwd,
                    const char *host)
{
    krb5_error_code ret;
    krb5_data ap_req_data;
    krb5_data krb_priv_data;
    krb5_data pwd_data;
    ChangePasswdDataMS chpw;
    size_t len = 0;
    u_char header[4 + 6];
    u_char *p;
    struct iovec iov[3];
    struct msghdr msghdr;

    krb5_data_zero (&ap_req_data);

    ret = krb5_mk_req_extended (context,
                                auth_context,
                                AP_OPTS_MUTUAL_REQUIRED | AP_OPTS_USE_SUBKEY,
                                NULL, /* in_data */
                                creds,
                                &ap_req_data);
    if (ret)
        return ret;

    chpw.newpasswd.length = strlen(passwd);
    chpw.newpasswd.data = rk_UNCONST(passwd);
    if (targprinc) {
        chpw.targname = &targprinc->name;
        chpw.targrealm = &targprinc->realm;
    } else {
        chpw.targname = NULL;
        chpw.targrealm = NULL;
    }

    ASN1_MALLOC_ENCODE(ChangePasswdDataMS, pwd_data.data, pwd_data.length,
                       &chpw, &len, ret);
    if (ret) {
        krb5_data_free (&ap_req_data);
        return ret;
    }

    if(pwd_data.length != len)
        krb5_abortx(context, "internal error in ASN.1 encoder");

    ret = krb5_mk_priv (context,
                        *auth_context,
                        &pwd_data,
                        &krb_priv_data,
                        NULL);
    if (ret)
        goto out2;

    len = 6 + ap_req_data.length + krb_priv_data.length;
    p = header;
    if (is_stream) {
        _krb5_put_int(p, len, 4);
        p += 4;
    }
    *p++ = (len >> 8) & 0xFF;
    *p++ = (len >> 0) & 0xFF;
    *p++ = 0xff;
    *p++ = 0x80;
    *p++ = (ap_req_data.length >> 8) & 0xFF;
    *p   = (ap_req_data.length >> 0) & 0xFF;

    memset(&msghdr, 0, sizeof(msghdr));
    msghdr.msg_name       = NULL;
    msghdr.msg_namelen    = 0;
    msghdr.msg_iov        = iov;
    msghdr.msg_iovlen     = sizeof(iov)/sizeof(*iov);
#if 0
    msghdr.msg_control    = NULL;
    msghdr.msg_controllen = 0;
#endif

    iov[0].iov_base    = (void*)header;
    if (is_stream)
        iov[0].iov_len     = 10;
    else
        iov[0].iov_len     = 6;
    iov[1].iov_base    = ap_req_data.data;
    iov[1].iov_len     = ap_req_data.length;
    iov[2].iov_base    = krb_priv_data.data;
    iov[2].iov_len     = krb_priv_data.length;

    if (rk_IS_SOCKET_ERROR( sendmsg (sock, &msghdr, 0) )) {
        ret = rk_SOCK_ERRNO;
        krb5_set_error_message(context, ret, "sendmsg %s: %s",
                               host, strerror(ret));
    }

    krb5_data_free (&krb_priv_data);
out2:
    krb5_data_free (&ap_req_data);
    krb5_data_free (&pwd_data);
    return ret;
}

static krb5_error_code
process_reply (krb5_context context,
               krb5_auth_context auth_context,
               int is_stream,
               rk_socket_t sock,
               int *result_code,
               krb5_data *result_code_string,
               krb5_data *result_string,
               const char *host)
{
    krb5_error_code ret;
    u_char reply[1024 * 3];
    size_t len;
    uint16_t pkt_len, pkt_ver;
    krb5_data ap_rep_data;
    int save_errno;

    len = 0;
    if (is_stream) {
        while (len < sizeof(reply)) {
            unsigned long size;

            ret = recvfrom (sock, reply + len, sizeof(reply) - len,
                            0, NULL, NULL);
            if (rk_IS_SOCKET_ERROR(ret)) {
                save_errno = rk_SOCK_ERRNO;
                krb5_set_error_message(context, save_errno,
                                       "recvfrom %s: %s",
                                       host, strerror(save_errno));
                return save_errno;
            } else if (ret == 0) {
                krb5_set_error_message(context, 1,"recvfrom timeout %s", host);
                return 1;
            }
            len += ret;
            if (len < 4)
                continue;
            _krb5_get_int(reply, &size, 4);
            if (size + 4 < len)
                continue;
            memmove(reply, reply + 4, size);
            len = size;
            break;
        }
        if (len == sizeof(reply)) {
            krb5_set_error_message(context, ENOMEM,
                                   N_("Message too large from %s", "host"),
                                   host);
            return ENOMEM;
        }
    } else {
        ret = recvfrom (sock, reply, sizeof(reply), 0, NULL, NULL);
        if (rk_IS_SOCKET_ERROR(ret)) {
            save_errno = rk_SOCK_ERRNO;
            krb5_set_error_message(context, save_errno,
                                   "recvfrom %s: %s",
                                   host, strerror(save_errno));
            return save_errno;
        }
        len = ret;
    }

    if (len < 6) {
        str2data (result_string, "server %s sent to too short message "
                  "(%zu bytes)", host, len);
        *result_code = KRB5_KPASSWD_MALFORMED;
        return 0;
    }

    pkt_len = (reply[0] << 8) | (reply[1]);
    pkt_ver = (reply[2] << 8) | (reply[3]);

    if ((pkt_len != len) || (reply[1] == 0x7e || reply[1] == 0x5e)) {
        KRB_ERROR error;
        size_t size;
        u_char *p;

        memset(&error, 0, sizeof(error));

        ret = decode_KRB_ERROR(reply, len, &error, &size);
        if (ret)
            return ret;

        if (error.e_data->length < 2) {
            str2data(result_string, "server %s sent too short "
                     "e_data to print anything usable", host);
            free_KRB_ERROR(&error);
            *result_code = KRB5_KPASSWD_MALFORMED;
            return 0;
        }

        p = error.e_data->data;
        *result_code = (p[0] << 8) | p[1];
        if (error.e_data->length == 2)
            str2data(result_string, "server only sent error code");
        else
            krb5_data_copy (result_string,
                            p + 2,
                            error.e_data->length - 2);
        free_KRB_ERROR(&error);
        return 0;
    }

    if (pkt_len != len) {
        str2data (result_string, "client: wrong len in reply");
        *result_code = KRB5_KPASSWD_MALFORMED;
        return 0;
    }
    if (pkt_ver != KRB5_KPASSWD_VERS_CHANGEPW) {
        str2data (result_string,
                  "client: wrong version number (%d)", pkt_ver);
        *result_code = KRB5_KPASSWD_MALFORMED;
        return 0;
    }

    ap_rep_data.data = reply + 6;
    ap_rep_data.length  = (reply[4] << 8) | (reply[5]);

    if (reply + len < (u_char *)ap_rep_data.data + ap_rep_data.length) {
        str2data (result_string, "client: wrong AP len in reply");
        *result_code = KRB5_KPASSWD_MALFORMED;
        return 0;
    }

    if (ap_rep_data.length) {
        krb5_ap_rep_enc_part *ap_rep;
        krb5_data priv_data;
        u_char *p;

        priv_data.data   = (u_char*)ap_rep_data.data + ap_rep_data.length;
        priv_data.length = len - ap_rep_data.length - 6;

        ret = krb5_rd_rep (context,
                           auth_context,
                           &ap_rep_data,
                           &ap_rep);
        if (ret)
            return ret;

        krb5_free_ap_rep_enc_part (context, ap_rep);

        ret = krb5_rd_priv (context,
                            auth_context,
                            &priv_data,
                            result_code_string,
                            NULL);
        if (ret) {
            krb5_data_free (result_code_string);
            return ret;
        }

        if (result_code_string->length < 2) {
            *result_code = KRB5_KPASSWD_MALFORMED;
            str2data (result_string,
                      "client: bad length in result");
            return 0;
        }

        p = result_code_string->data;

        *result_code = (p[0] << 8) | p[1];
        krb5_data_copy (result_string,
                        (unsigned char*)result_code_string->data + 2,
                        result_code_string->length - 2);
        return 0;
    } else {
        KRB_ERROR error;
        size_t size;
        u_char *p;

        ret = decode_KRB_ERROR(reply + 6, len - 6, &error, &size);
        if (ret) {
            return ret;
        }
        if (error.e_data->length < 2) {
            krb5_warnx (context, "too short e_data to print anything usable");
            return 1;           /* XXX */
        }

        p = error.e_data->data;
        *result_code = (p[0] << 8) | p[1];
        krb5_data_copy (result_string,
                        p + 2,
                        error.e_data->length - 2);
        return 0;
    }
}


/*
 * change the password using the credentials in `creds' (for the
 * principal indicated in them) to `newpw', storing the result of
 * the operation in `result_*' and an error code or 0.
 */

typedef krb5_error_code (*kpwd_send_request) (krb5_context,
                                              krb5_auth_context *,
                                              krb5_creds *,
                                              krb5_principal,
                                              int,
                                              rk_socket_t,
                                              const char *,
                                              const char *);
typedef krb5_error_code (*kpwd_process_reply) (krb5_context,
                                               krb5_auth_context,
                                               int,
                                               rk_socket_t,
                                               int *,
                                               krb5_data *,
                                               krb5_data *,
                                               const char *);

static struct kpwd_proc {
    const char *name;
    int flags;
#define SUPPORT_TCP     1
#define SUPPORT_UDP     2
    kpwd_send_request send_req;
    kpwd_process_reply process_rep;
} procs[] = {
    {
        "MS set password",
        SUPPORT_TCP|SUPPORT_UDP,
        setpw_send_request,
        process_reply
    },
    {
        "change password",
        SUPPORT_UDP,
        chgpw_send_request,
        process_reply
    },
    { NULL, 0, NULL, NULL }
};

/*
 *
 */

static krb5_error_code
change_password_loop (krb5_context      context,
                      krb5_creds        *creds,
                      krb5_principal    targprinc,
                      const char        *newpw,
                      int               *result_code,
                      krb5_data         *result_code_string,
                      krb5_data         *result_string,
                      struct kpwd_proc  *proc)
{
    krb5_error_code ret;
    krb5_auth_context auth_context = NULL;
    krb5_krbhst_handle handle = NULL;
    krb5_krbhst_info *hi;
    rk_socket_t sock;
    unsigned int i;
    int done = 0;
    krb5_realm realm;

    if (targprinc)
        realm = targprinc->realm;
    else
        realm = creds->client->realm;

    ret = krb5_auth_con_init (context, &auth_context);
    if (ret)
        return ret;

    krb5_auth_con_setflags (context, auth_context,
                            KRB5_AUTH_CONTEXT_DO_SEQUENCE);

    ret = krb5_krbhst_init (context, realm, KRB5_KRBHST_CHANGEPW, &handle);
    if (ret)
        goto out;

    while (!done && (ret = krb5_krbhst_next(context, handle, &hi)) == 0) {
        struct addrinfo *ai, *a;
        int is_stream;

        switch (hi->proto) {
        case KRB5_KRBHST_UDP:
            if ((proc->flags & SUPPORT_UDP) == 0)
                continue;
            is_stream = 0;
            break;
        case KRB5_KRBHST_TCP:
            if ((proc->flags & SUPPORT_TCP) == 0)
                continue;
            is_stream = 1;
            break;
        default:
            continue;
        }

        ret = krb5_krbhst_get_addrinfo(context, hi, &ai);
        if (ret)
            continue;

        for (a = ai; !done && a != NULL; a = a->ai_next) {
            int replied = 0;

            sock = socket (a->ai_family, a->ai_socktype | SOCK_CLOEXEC, a->ai_protocol);
            if (rk_IS_BAD_SOCKET(sock))
                continue;
            rk_cloexec(sock);

            ret = connect(sock, a->ai_addr, a->ai_addrlen);
            if (rk_IS_SOCKET_ERROR(ret)) {
                rk_closesocket (sock);
                goto out;
            }

            ret = krb5_auth_con_genaddrs (context, auth_context, sock,
                                          KRB5_AUTH_CONTEXT_GENERATE_LOCAL_ADDR);
            if (ret) {
                rk_closesocket (sock);
                goto out;
            }

            for (i = 0; !done && i < 5; ++i) {
                fd_set fdset;
                struct timeval tv;

                if (!replied) {
                    replied = 0;

                    ret = (*proc->send_req) (context,
                                             &auth_context,
                                             creds,
                                             targprinc,
                                             is_stream,
                                             sock,
                                             newpw,
                                             hi->hostname);
                    if (ret) {
                        rk_closesocket(sock);
                        goto out;
                    }
                }

#ifndef NO_LIMIT_FD_SETSIZE
                if (sock >= FD_SETSIZE) {
                    ret = ERANGE;
                    krb5_set_error_message(context, ret,
                                           "fd %d too large", sock);
                    rk_closesocket (sock);
                    goto out;
                }
#endif

                FD_ZERO(&fdset);
                FD_SET(sock, &fdset);
                tv.tv_usec = 0;
                tv.tv_sec  = 1 + (1 << i);

                ret = select (sock + 1, &fdset, NULL, NULL, &tv);
                if (rk_IS_SOCKET_ERROR(ret) && rk_SOCK_ERRNO != EINTR) {
                    rk_closesocket(sock);
                    goto out;
                }
                if (ret == 1) {
                    ret = (*proc->process_rep) (context,
                                                auth_context,
                                                is_stream,
                                                sock,
                                                result_code,
                                                result_code_string,
                                                result_string,
                                                hi->hostname);
                    if (ret == 0)
                        done = 1;
                    else if (i > 0 && ret == KRB5KRB_AP_ERR_MUT_FAIL)
                        replied = 1;
                } else {
                    ret = KRB5_KDC_UNREACH;
                }
            }
            rk_closesocket (sock);
        }
    }

 out:
    krb5_krbhst_free (context, handle);
    krb5_auth_con_free (context, auth_context);

    if (ret == KRB5_KDC_UNREACH) {
        krb5_set_error_message(context,
                               ret,
                               N_("Unable to reach any changepw server "
                                 " in realm %s", "realm"), realm);
        *result_code = KRB5_KPASSWD_HARDERROR;
    }
    return ret;
}

#ifndef HEIMDAL_SMALLER

static struct kpwd_proc *
find_chpw_proto(const char *name)
{
    struct kpwd_proc *p;
    for (p = procs; p->name != NULL; p++) {
        if (strcmp(p->name, name) == 0)
            return p;
    }
    return NULL;
}

/**
 * Deprecated: krb5_change_password() is deprecated, use krb5_set_password().
 *
 * @param context a Keberos context
 * @param creds
 * @param newpw
 * @param result_code
 * @param result_code_string
 * @param result_string
 *
 * @return On sucess password is changed.

 * @ingroup @krb5_deprecated
 */

KRB5_LIB_FUNCTION krb5_error_code KRB5_LIB_CALL
krb5_change_password (krb5_context      context,
                      krb5_creds        *creds,
                      const char        *newpw,
                      int               *result_code,
                      krb5_data         *result_code_string,
                      krb5_data         *result_string)
    KRB5_DEPRECATED_FUNCTION("Use X instead")
{
    struct kpwd_proc *p = find_chpw_proto("change password");

    *result_code = KRB5_KPASSWD_MALFORMED;
    result_code_string->data = result_string->data = NULL;
    result_code_string->length = result_string->length = 0;

    if (p == NULL)
        return KRB5_KPASSWD_MALFORMED;

    return change_password_loop(context, creds, NULL, newpw,
                                result_code, result_code_string,
                                result_string, p);
}
#endif /* HEIMDAL_SMALLER */

/**
 * Change password using creds.
 *
 * @param context a Keberos context
 * @param creds The initial kadmin/passwd for the principal or an admin principal
 * @param newpw The new password to set
 * @param targprinc if unset, the default principal is used.
 * @param result_code Result code, KRB5_KPASSWD_SUCCESS is when password is changed.
 * @param result_code_string binary message from the server, contains
 * at least the result_code.
 * @param result_string A message from the kpasswd service or the
 * library in human printable form. The string is NUL terminated.
 *
 * @return On sucess and *result_code is KRB5_KPASSWD_SUCCESS, the password is changed.

 * @ingroup @krb5
 */

KRB5_LIB_FUNCTION krb5_error_code KRB5_LIB_CALL
krb5_set_password(krb5_context context,
                  krb5_creds *creds,
                  const char *newpw,
                  krb5_principal targprinc,
                  int *result_code,
                  krb5_data *result_code_string,
                  krb5_data *result_string)
{
    krb5_principal principal = NULL;
    krb5_error_code ret = 0;
    int i;

    *result_code = KRB5_KPASSWD_MALFORMED;
    krb5_data_zero(result_code_string);
    krb5_data_zero(result_string);

    if (targprinc == NULL) {
        ret = krb5_get_default_principal(context, &principal);
        if (ret)
            return ret;
    } else
        principal = targprinc;

    for (i = 0; procs[i].name != NULL; i++) {
        *result_code = 0;
        ret = change_password_loop(context, creds, principal, newpw,
                                   result_code, result_code_string,
                                   result_string,
                                   &procs[i]);
        if (ret == 0 && *result_code == 0)
            break;
    }

    if (targprinc == NULL)
        krb5_free_principal(context, principal);
    return ret;
}

/*
 *
 */

KRB5_LIB_FUNCTION krb5_error_code KRB5_LIB_CALL
krb5_set_password_using_ccache(krb5_context context,
                               krb5_ccache ccache,
                               const char *newpw,
                               krb5_principal targprinc,
                               int *result_code,
                               krb5_data *result_code_string,
                               krb5_data *result_string)
{
    krb5_creds creds, *credsp;
    krb5_error_code ret;
    krb5_principal principal = NULL;

    *result_code = KRB5_KPASSWD_MALFORMED;
    result_code_string->data = result_string->data = NULL;
    result_code_string->length = result_string->length = 0;

    memset(&creds, 0, sizeof(creds));

    if (targprinc == NULL) {
        ret = krb5_cc_get_principal(context, ccache, &principal);
        if (ret)
            return ret;
    } else
        principal = targprinc;

    ret = krb5_make_principal(context, &creds.server,
                              krb5_principal_get_realm(context, principal),
                              "kadmin", "changepw", NULL);
    if (ret)
        goto out;

    ret = krb5_cc_get_principal(context, ccache, &creds.client);
    if (ret) {
        krb5_free_principal(context, creds.server);
        goto out;
    }

    ret = krb5_get_credentials(context, 0, ccache, &creds, &credsp);
    krb5_free_principal(context, creds.server);
    krb5_free_principal(context, creds.client);
    if (ret)
        goto out;

    ret = krb5_set_password(context,
                            credsp,
                            newpw,
                            principal,
                            result_code,
                            result_code_string,
                            result_string);

    krb5_free_creds(context, credsp);

    return ret;
 out:
    if (targprinc == NULL)
        krb5_free_principal(context, principal);
    return ret;
}

/*
 *
 */

KRB5_LIB_FUNCTION const char* KRB5_LIB_CALL
krb5_passwd_result_to_string (krb5_context context,
                              int result)
{
    static const char *strings[] = {
        "Success",
        "Malformed",
        "Hard error",
        "Auth error",
        "Soft error" ,
        "Access denied",
        "Bad version",
        "Initial flag needed"
    };

    if (result < 0 || result > KRB5_KPASSWD_INITIAL_FLAG_NEEDED)
        return "unknown result code";
    else
        return strings[result];
}