/*
 * Copyright (c) 1997 - 2001 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"

/*
 * Try to find out what's a reasonable default principal.
 */

static const char*
get_env_user(void)
{
    const char *user = getenv("USER");
    if(user == NULL)
        user = getenv("LOGNAME");
    if(user == NULL)
        user = getenv("USERNAME");
    return user;
}

#ifndef _WIN32

/*
 * Will only use operating-system dependant operation to get the
 * default principal, for use of functions that in ccache layer to
 * avoid recursive calls.
 */

krb5_error_code
_krb5_get_default_principal_local (krb5_context context,
                                   krb5_principal *princ)
{
    krb5_error_code ret;
    const char *user;
    uid_t uid;

    *princ = NULL;

    uid = getuid();
    if(uid == 0) {
        user = getlogin();
        if(user == NULL)
            user = get_env_user();
        if(user != NULL && strcmp(user, "root") != 0)
            ret = krb5_make_principal(context, princ, NULL, user, "root", NULL);
        else
            ret = krb5_make_principal(context, princ, NULL, "root", NULL);
    } else {
        struct passwd *pw = getpwuid(uid);
        if(pw != NULL)
            user = pw->pw_name;
        else {
            user = get_env_user();
            if(user == NULL)
                user = getlogin();
        }
        if(user == NULL) {
            krb5_set_error_message(context, ENOTTY,
                                   N_("unable to figure out current "
                                      "principal", ""));
            return ENOTTY; /* XXX */
        }
        ret = krb5_make_principal(context, princ, NULL, user, NULL);
    }
    return ret;
}

#else  /* _WIN32 */

#define SECURITY_WIN32
#include <security.h>

krb5_error_code
_krb5_get_default_principal_local(krb5_context context,
                                  krb5_principal *princ)
{
    /* See if we can get the principal first.  We only expect this to
       work if logged into a domain. */
    {
        char username[1024];
        ULONG sz = sizeof(username);

        if (GetUserNameEx(NameUserPrincipal, username, &sz)) {
            return krb5_parse_name_flags(context, username,
                                         KRB5_PRINCIPAL_PARSE_ENTERPRISE,
                                         princ);
        }
    }

    /* Just get the Windows username.  This should pretty much always
       work. */
    {
        char username[1024];
        DWORD dsz = sizeof(username);

        if (GetUserName(username, &dsz)) {
            return krb5_make_principal(context, princ, NULL, username, NULL);
        }
    }

    /* Failing that, we look at the environment */
    {
        const char * username = get_env_user();

        if (username == NULL) {
            krb5_set_error_string(context,
                                  "unable to figure out current principal");
            return ENOTTY;      /* Really? */
        }

        return krb5_make_principal(context, princ, NULL, username, NULL);
    }
}

#endif

KRB5_LIB_FUNCTION krb5_error_code KRB5_LIB_CALL
krb5_get_default_principal (krb5_context context,
                            krb5_principal *princ)
{
    krb5_error_code ret;
    krb5_ccache id;

    *princ = NULL;

    ret = krb5_cc_default (context, &id);
    if (ret == 0) {
        ret = krb5_cc_get_principal (context, id, princ);
        krb5_cc_close (context, id);
        if (ret == 0)
            return 0;
    }

    return _krb5_get_default_principal_local(context, princ);
}