/* -*- mode: c; c-basic-offset: 4; indent-tabs-mode: nil -*- */
/* lib/krb5/os/sn2princ.c */
/*
 * Copyright 1991,2002 by the Massachusetts Institute of Technology.
 * All Rights Reserved.
 *
 * Export of this software from the United States of America may
 *   require a specific license from the United States Government.
 *   It is the responsibility of any person or organization contemplating
 *   export to obtain such a license before exporting.
 *
 * WITHIN THAT CONSTRAINT, permission to use, copy, modify, and
 * distribute this software and its documentation for any purpose and
 * without fee is hereby granted, provided that the above copyright
 * notice appear in all copies and that both that copyright notice and
 * this permission notice appear in supporting documentation, and that
 * the name of M.I.T. not be used in advertising or publicity pertaining
 * to distribution of the software without specific, written prior
 * permission.  Furthermore if you modify this software you must label
 * your software as modified software and not distribute it in such a
 * fashion that it might be confused with the original M.I.T. software.
 * M.I.T. makes no representations about the suitability of
 * this software for any purpose.  It is provided "as is" without express
 * or implied warranty.
 */

/* Convert a hostname and service name to a principal in the "standard"
 * form. */

#include "k5-int.h"
#include "os-proto.h"
#include "fake-addrinfo.h"
#include <ctype.h>
#ifdef HAVE_SYS_PARAM_H
#include <sys/param.h>
#endif

#if !defined(DEFAULT_RDNS_LOOKUP)
#define DEFAULT_RDNS_LOOKUP 1
#endif

static int
maybe_use_reverse_dns (krb5_context context, int defalt)
{
    krb5_error_code code;
    char * value = NULL;
    int use_rdns = 0;

    code = profile_get_string(context->profile, KRB5_CONF_LIBDEFAULTS,
                              KRB5_CONF_RDNS, 0, 0, &value);
    if (code)
        return defalt;

    if (value == 0)
        return defalt;

    use_rdns = _krb5_conf_boolean(value);
    profile_release_string(value);
    return use_rdns;
}


krb5_error_code KRB5_CALLCONV
krb5_sname_to_principal(krb5_context context, const char *hostname, const char *sname, krb5_int32 type, krb5_principal *ret_princ)
{
    char **hrealms, *realm, *remote_host;
    krb5_error_code retval;
    register char *cp;
    char localname[MAXHOSTNAMELEN];

#ifdef DEBUG_REFERRALS
    printf("krb5_sname_to_principal(host=%s, sname=%s, type=%d)\n",hostname,sname,type);
    printf("      name types: 0=unknown, 3=srv_host\n");
#endif

    if ((type == KRB5_NT_UNKNOWN) ||
        (type == KRB5_NT_SRV_HST)) {

        /* if hostname is NULL, use local hostname */
        if (! hostname) {
            if (gethostname(localname, MAXHOSTNAMELEN))
                return SOCKET_ERRNO;
            hostname = localname;
        }

        /* if sname is NULL, use "host" */
        if (! sname)
            sname = "host";

        /* copy the hostname into non-volatile storage */

        if (type == KRB5_NT_SRV_HST) {
            struct addrinfo *ai = NULL, hints;
            int err;
            char hnamebuf[NI_MAXHOST];

            /* Note that the old code would accept numeric addresses,
               and if the gethostbyaddr step could convert them to
               real hostnames, you could actually get reasonable
               results.  If the mapping failed, you'd get dotted
               triples as realm names.  *sigh*

               The latter has been fixed in hst_realm.c, but we should
               keep supporting numeric addresses if they do have
               hostnames associated.  */

            memset(&hints, 0, sizeof(hints));
            hints.ai_flags = AI_CANONNAME;
            err = getaddrinfo(hostname, 0, &hints, &ai);
            if (err) {
#ifdef DEBUG_REFERRALS
                printf("sname_to_princ: failed to canonicalize %s; using as-is", hostname);
#endif
            }
            remote_host = strdup((ai && ai->ai_canonname) ? ai->ai_canonname : hostname);
            if (!remote_host) {
                if(ai)
                    freeaddrinfo(ai);
                return ENOMEM;
            }

            if ((!err) && maybe_use_reverse_dns(context, DEFAULT_RDNS_LOOKUP)) {
                /*
                 * Do a reverse resolution to get the full name, just in
                 * case there's some funny business going on.  If there
                 * isn't an in-addr record, give up.
                 */
                /* XXX: This is *so* bogus.  There are several cases where
                   this won't get us the canonical name of the host, but
                   this is what we've trained people to expect.  We'll
                   probably fix it at some point, but let's try to
                   preserve the current behavior and only shake things up
                   once when it comes time to fix this lossage.  */
                err = getnameinfo(ai->ai_addr, ai->ai_addrlen,
                                  hnamebuf, sizeof(hnamebuf), 0, 0, NI_NAMEREQD);
                freeaddrinfo(ai);
                if (err == 0) {
                    free(remote_host);
                    remote_host = strdup(hnamebuf);
                    if (!remote_host)
                        return ENOMEM;
                }
            } else
                freeaddrinfo(ai);
        } else /* type == KRB5_NT_UNKNOWN */ {
            remote_host = strdup(hostname);
        }
        if (!remote_host)
            return ENOMEM;
#ifdef DEBUG_REFERRALS
        printf("sname_to_princ: hostname <%s> after rdns processing\n",remote_host);
#endif

        if (type == KRB5_NT_SRV_HST)
            for (cp = remote_host; *cp; cp++)
                if (isupper((unsigned char) (*cp)))
                    *cp = tolower((unsigned char) (*cp));

        /*
         * Windows NT5's broken resolver gratuitously tacks on a
         * trailing period to the hostname (at least it does in
         * Beta2).  Find and remove it.
         */
        if (remote_host[0]) {
            cp = remote_host + strlen(remote_host)-1;
            if (*cp == '.')
                *cp = 0;
        }


        if ((retval = krb5_get_host_realm(context, remote_host, &hrealms))) {
            free(remote_host);
            return retval;
        }

#ifdef DEBUG_REFERRALS
        printf("sname_to_princ:  realm <%s> after krb5_get_host_realm\n",hrealms[0]);
#endif

        if (!hrealms[0]) {
            free(remote_host);
            free(hrealms);
            return KRB5_ERR_HOST_REALM_UNKNOWN;
        }
        realm = hrealms[0];

        retval = krb5_build_principal(context, ret_princ, strlen(realm),
                                      realm, sname, remote_host,
                                      (char *)0);
        if (retval == 0)
            krb5_princ_type(context, *ret_princ) = type;

#ifdef DEBUG_REFERRALS
        printf("krb5_sname_to_principal returning\n");
        printf("realm: <%s>, sname: <%s>, remote_host: <%s>\n",
               realm,sname,remote_host);
        krb5int_dbgref_dump_principal("krb5_sname_to_principal",*ret_princ);
#endif

        free(remote_host);

        krb5_free_host_realm(context, hrealms);
        return retval;
    } else {
        return KRB5_SNAME_UNSUPP_NAMETYPE;
    }
}
