NULL_RETURNS paranoid check [CID-66]

[heimdal.git] / lib / krb5 / principal.c

/*
 * Copyright (c) 1997-2007 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.
 */

/**
 * @page krb5_principal_intro The principal handing functions.
 *
 * A Kerberos principal is a email address looking string that
 * contains to parts separeted by a @.  The later part is the kerbero
 * realm the principal belongs to and the former is a list of 0 or
 * more components. For example
 * @verbatim
lha@SU.SE
host/hummel.it.su.se@SU.SE
host/admin@H5L.ORG
@endverbatim
 *
 * See the library functions here: @ref krb5_principal
 */

#include "krb5_locl.h"
#ifdef HAVE_RES_SEARCH
#define USE_RESOLVER
#endif
#ifdef HAVE_ARPA_NAMESER_H
#include <arpa/nameser.h>
#endif
#include <fnmatch.h>
#include "resolve.h"

#define princ_num_comp(P) ((P)->name.name_string.len)
#define princ_type(P) ((P)->name.name_type)
#define princ_comp(P) ((P)->name.name_string.val)
#define princ_ncomp(P, N) ((P)->name.name_string.val[(N)])
#define princ_realm(P) ((P)->realm)

/**
 * Frees a Kerberos principal allocated by the library with
 * krb5_parse_name(), krb5_make_principal() or any other related
 * principal functions.
 *
 * @param context A Kerberos context.
 * @param p a principal to free.
 *
 * @return An krb5 error code, see krb5_get_error_message().
 *
 * @ingroup krb5_principal
 */

void KRB5_LIB_FUNCTION
krb5_free_principal(krb5_context context,
                    krb5_principal p)
{
    if(p){
        free_Principal(p);
        free(p);
    }
}

/**
 * Set the type of the principal
 *
 * @param context A Kerberos context.
 * @param principal principal to set the type for
 * @param type the new type
 *
 * @return An krb5 error code, see krb5_get_error_message().
 *
 * @ingroup krb5_principal
 */

void KRB5_LIB_FUNCTION
krb5_principal_set_type(krb5_context context,
                        krb5_principal principal,
                        int type)
{
    princ_type(principal) = type;
}

int KRB5_LIB_FUNCTION
krb5_principal_get_type(krb5_context context,
                        krb5_const_principal principal)
{
    return princ_type(principal);
}

const char* KRB5_LIB_FUNCTION
krb5_principal_get_realm(krb5_context context,
                         krb5_const_principal principal)
{
    return princ_realm(principal);
}                       

const char* KRB5_LIB_FUNCTION
krb5_principal_get_comp_string(krb5_context context,
                               krb5_const_principal principal,
                               unsigned int component)
{
    if(component >= princ_num_comp(principal))
       return NULL;
    return princ_ncomp(principal, component);
}

/**
 * Get number of component is principal.
 *
 * @param context Kerberos 5 context
 * @param principal principal to query
 *
 * @return number of components in string
 *
 * @ingroup krb5_principal
 */

unsigned int KRB5_LIB_FUNCTION
krb5_principal_get_num_comp(krb5_context context,
                            krb5_const_principal principal)
{
    return princ_num_comp(principal);
}

krb5_error_code KRB5_LIB_FUNCTION
krb5_parse_name_flags(krb5_context context,
                      const char *name,
                      int flags,
                      krb5_principal *principal)
{
    krb5_error_code ret;
    heim_general_string *comp;
    heim_general_string realm = NULL;
    int ncomp;

    const char *p;
    char *q;
    char *s;
    char *start;

    int n;
    char c;
    int got_realm = 0;
    int first_at = 1;
    int enterprise = (flags & KRB5_PRINCIPAL_PARSE_ENTERPRISE);

    *principal = NULL;

#define RFLAGS (KRB5_PRINCIPAL_PARSE_NO_REALM|KRB5_PRINCIPAL_PARSE_REQUIRE_REALM)

    if ((flags & RFLAGS) == RFLAGS) {
        krb5_set_error_message(context, KRB5_ERR_NO_SERVICE,
                               N_("Can't require both realm and "
                                  "no realm at the same time", ""));
        return KRB5_ERR_NO_SERVICE;
    }
#undef RFLAGS

    /* count number of component,
     * enterprise names only have one component
     */
    ncomp = 1;
    if (!enterprise) {
        for(p = name; *p; p++){
            if(*p=='\\'){
                if(!p[1]) {
                    krb5_set_error_message(context, KRB5_PARSE_MALFORMED,
                                           N_("trailing \\ in principal name", ""));
                    return KRB5_PARSE_MALFORMED;
                }
                p++;
            } else if(*p == '/')
                ncomp++;
            else if(*p == '@')
                break;
        }
    }
    comp = calloc(ncomp, sizeof(*comp));
    if (comp == NULL) {
        krb5_set_error_message(context, ENOMEM,
                               N_("malloc: out of memory", ""));
        return ENOMEM;
    }

    n = 0;
    p = start = q = s = strdup(name);
    if (start == NULL) {
        free (comp);
        krb5_set_error_message(context, ENOMEM,
                               N_("malloc: out of memory", ""));
        return ENOMEM;
    }
    while(*p){
        c = *p++;
        if(c == '\\'){
            c = *p++;
            if(c == 'n')
                c = '\n';
            else if(c == 't')
                c = '\t';
            else if(c == 'b')
                c = '\b';
            else if(c == '0')
                c = '\0';
            else if(c == '\0') {
                ret = KRB5_PARSE_MALFORMED;
                krb5_set_error_message(context, ret,
                                       N_("trailing \\ in principal name", ""));
                goto exit;
            }
        }else if(enterprise && first_at) {
            if (c == '@')
                first_at = 0;
        }else if((c == '/' && !enterprise) || c == '@'){
            if(got_realm){
                ret = KRB5_PARSE_MALFORMED;
                krb5_set_error_message(context, ret,
                                       N_("part after realm in principal name", ""));
                goto exit;
            }else{
                comp[n] = malloc(q - start + 1);
                if (comp[n] == NULL) {
                    ret = ENOMEM;
                    krb5_set_error_message(context, ret,
                                           N_("malloc: out of memory", ""));
                    goto exit;
                }
                memcpy(comp[n], start, q - start);
                comp[n][q - start] = 0;
                n++;
            }
            if(c == '@')
                got_realm = 1;
            start = q;
            continue;
        }
        if(got_realm && (c == '/' || c == '\0')) {
            ret = KRB5_PARSE_MALFORMED;
            krb5_set_error_message(context, ret,
                                   N_("part after realm in principal name", ""));
            goto exit;
        }
        *q++ = c;
    }
    if(got_realm){
        if (flags & KRB5_PRINCIPAL_PARSE_NO_REALM) {
            ret = KRB5_PARSE_MALFORMED;
            krb5_set_error_message(context, ret,
                                   N_("realm found in 'short' principal "
                                      "expected to be without one", ""));
            goto exit;
        }
        realm = malloc(q - start + 1);
        if (realm == NULL) {
            ret = ENOMEM;
            krb5_set_error_message(context, ret,
                                   N_("malloc: out of memory", ""));
            goto exit;
        }
        memcpy(realm, start, q - start);
        realm[q - start] = 0;
    }else{
        if (flags & KRB5_PRINCIPAL_PARSE_REQUIRE_REALM) {
            ret = KRB5_PARSE_MALFORMED;
            krb5_set_error_message(context, ret,
                                   N_("realm NOT found in principal "
                                      "expected to be with one", ""));
            goto exit;
        } else if (flags & KRB5_PRINCIPAL_PARSE_NO_REALM) {
            realm = NULL;
        } else {
            ret = krb5_get_default_realm (context, &realm);
            if (ret)
                goto exit;
        }

        comp[n] = malloc(q - start + 1);
        if (comp[n] == NULL) {
            ret = ENOMEM;
            krb5_set_error_message(context, ret,
                                   N_("malloc: out of memory", ""));
            goto exit;
        }
        memcpy(comp[n], start, q - start);
        comp[n][q - start] = 0;
        n++;
    }
    *principal = malloc(sizeof(**principal));
    if (*principal == NULL) {
        ret = ENOMEM;
        krb5_set_error_message(context, ret,
                               N_("malloc: out of memory", ""));
        goto exit;
    }
    if (enterprise)
        (*principal)->name.name_type = KRB5_NT_ENTERPRISE_PRINCIPAL;
    else
        (*principal)->name.name_type = KRB5_NT_PRINCIPAL;
    (*principal)->name.name_string.val = comp;
    princ_num_comp(*principal) = n;
    (*principal)->realm = realm;
    free(s);
    return 0;
exit:
    while(n>0){
        free(comp[--n]);
    }
    free(comp);
    free(realm);
    free(s);
    return ret;
}

krb5_error_code KRB5_LIB_FUNCTION
krb5_parse_name(krb5_context context,
                const char *name,
                krb5_principal *principal)
{
    return krb5_parse_name_flags(context, name, 0, principal);
}

static const char quotable_chars[] = " \n\t\b\\/@";
static const char replace_chars[] = " ntb\\/@";
static const char nq_chars[] = "    \\/@";

#define add_char(BASE, INDEX, LEN, C) do { if((INDEX) < (LEN)) (BASE)[(INDEX)++] = (C); }while(0);

static size_t
quote_string(const char *s, char *out, size_t idx, size_t len, int display)
{
    const char *p, *q;
    for(p = s; *p && idx < len; p++){
        q = strchr(quotable_chars, *p);
        if (q && display) {
            add_char(out, idx, len, replace_chars[q - quotable_chars]);
        } else if (q) {
            add_char(out, idx, len, '\\');
            add_char(out, idx, len, replace_chars[q - quotable_chars]);
        }else
            add_char(out, idx, len, *p);
    }
    if(idx < len)
        out[idx] = '\0';
    return idx;
}


static krb5_error_code
unparse_name_fixed(krb5_context context,
                   krb5_const_principal principal,
                   char *name,
                   size_t len,
                   int flags)
{
    size_t idx = 0;
    int i;
    int short_form = (flags & KRB5_PRINCIPAL_UNPARSE_SHORT) != 0;
    int no_realm = (flags & KRB5_PRINCIPAL_UNPARSE_NO_REALM) != 0;
    int display = (flags & KRB5_PRINCIPAL_UNPARSE_DISPLAY) != 0;

    if (!no_realm && princ_realm(principal) == NULL) {
        krb5_set_error_message(context, ERANGE,
                               N_("Realm missing from principal, "
                                  "can't unparse", ""));
        return ERANGE;
    }

    for(i = 0; i < princ_num_comp(principal); i++){
        if(i)
            add_char(name, idx, len, '/');
        idx = quote_string(princ_ncomp(principal, i), name, idx, len, display);
        if(idx == len) {
            krb5_set_error_message(context, ERANGE,
                                   N_("Out of space printing principal", ""));
            return ERANGE;
        }
    }
    /* add realm if different from default realm */
    if(short_form && !no_realm) {
        krb5_realm r;
        krb5_error_code ret;
        ret = krb5_get_default_realm(context, &r);
        if(ret)
            return ret;
        if(strcmp(princ_realm(principal), r) != 0)
            short_form = 0;
        free(r);
    }
    if(!short_form && !no_realm) {
        add_char(name, idx, len, '@');
        idx = quote_string(princ_realm(principal), name, idx, len, display);
        if(idx == len) {
            krb5_set_error_message(context, ERANGE,
                                   N_("Out of space printing "
                                      "realm of principal", ""));
            return ERANGE;
        }
    }
    return 0;
}

krb5_error_code KRB5_LIB_FUNCTION
krb5_unparse_name_fixed(krb5_context context,
                        krb5_const_principal principal,
                        char *name,
                        size_t len)
{
    return unparse_name_fixed(context, principal, name, len, 0);
}

krb5_error_code KRB5_LIB_FUNCTION
krb5_unparse_name_fixed_short(krb5_context context,
                              krb5_const_principal principal,
                              char *name,
                              size_t len)
{
    return unparse_name_fixed(context, principal, name, len,
                              KRB5_PRINCIPAL_UNPARSE_SHORT);
}

krb5_error_code KRB5_LIB_FUNCTION
krb5_unparse_name_fixed_flags(krb5_context context,
                              krb5_const_principal principal,
                              int flags,
                              char *name,
                              size_t len)
{
    return unparse_name_fixed(context, principal, name, len, flags);
}

static krb5_error_code
unparse_name(krb5_context context,
             krb5_const_principal principal,
             char **name,
             int flags)
{
    size_t len = 0, plen;
    int i;
    krb5_error_code ret;
    /* count length */
    if (princ_realm(principal)) {
        plen = strlen(princ_realm(principal));

        if(strcspn(princ_realm(principal), quotable_chars) == plen)
            len += plen;
        else
            len += 2*plen;
        len++; /* '@' */
    }
    for(i = 0; i < princ_num_comp(principal); i++){
        plen = strlen(princ_ncomp(principal, i));
        if(strcspn(princ_ncomp(principal, i), quotable_chars) == plen)
            len += plen;
        else
            len += 2*plen;
        len++;
    }
    len++; /* '\0' */
    *name = malloc(len);
    if(*name == NULL) {
        krb5_set_error_message(context, ENOMEM,
                               N_("malloc: out of memory", ""));
        return ENOMEM;
    }
    ret = unparse_name_fixed(context, principal, *name, len, flags);
    if(ret) {
        free(*name);
        *name = NULL;
    }
    return ret;
}

krb5_error_code KRB5_LIB_FUNCTION
krb5_unparse_name(krb5_context context,
                  krb5_const_principal principal,
                  char **name)
{
    return unparse_name(context, principal, name, 0);
}

krb5_error_code KRB5_LIB_FUNCTION
krb5_unparse_name_flags(krb5_context context,
                        krb5_const_principal principal,
                        int flags,
                        char **name)
{
    return unparse_name(context, principal, name, flags);
}

krb5_error_code KRB5_LIB_FUNCTION
krb5_unparse_name_short(krb5_context context,
                        krb5_const_principal principal,
                        char **name)
{
    return unparse_name(context, principal, name, KRB5_PRINCIPAL_UNPARSE_SHORT);
}

#if 0 /* not implemented */

krb5_error_code KRB5_LIB_FUNCTION
krb5_unparse_name_ext(krb5_context context,
                      krb5_const_principal principal,
                      char **name,
                      size_t *size)
{
    krb5_abortx(context, "unimplemented krb5_unparse_name_ext called");
}

#endif

krb5_error_code KRB5_LIB_FUNCTION
krb5_principal_set_realm(krb5_context context,
                         krb5_principal principal,
                         krb5_const_realm realm)
{
    if (princ_realm(principal))
        free(princ_realm(principal));

    princ_realm(principal) = strdup(realm);
    if (princ_realm(principal) == NULL) {
        krb5_set_error_message(context, ENOMEM,
                               N_("malloc: out of memory", ""));
        return ENOMEM;
    }
    return 0;
}


krb5_error_code KRB5_LIB_FUNCTION
krb5_build_principal(krb5_context context,
                     krb5_principal *principal,
                     int rlen,
                     krb5_const_realm realm,
                     ...)
{
    krb5_error_code ret;
    va_list ap;
    va_start(ap, realm);
    ret = krb5_build_principal_va(context, principal, rlen, realm, ap);
    va_end(ap);
    return ret;
}

static krb5_error_code
append_component(krb5_context context, krb5_principal p,
                 const char *comp,
                 size_t comp_len)
{
    heim_general_string *tmp;
    size_t len = princ_num_comp(p);

    tmp = realloc(princ_comp(p), (len + 1) * sizeof(*tmp));
    if(tmp == NULL) {
        krb5_set_error_message(context, ENOMEM,
                               N_("malloc: out of memory", ""));
        return ENOMEM;
    }
    princ_comp(p) = tmp;
    princ_ncomp(p, len) = malloc(comp_len + 1);
    if (princ_ncomp(p, len) == NULL) {
        krb5_set_error_message(context, ENOMEM,
                               N_("malloc: out of memory", ""));
        return ENOMEM;
    }
    memcpy (princ_ncomp(p, len), comp, comp_len);
    princ_ncomp(p, len)[comp_len] = '\0';
    princ_num_comp(p)++;
    return 0;
}

static void
va_ext_princ(krb5_context context, krb5_principal p, va_list ap)
{
    while(1){
        const char *s;
        int len;
        len = va_arg(ap, int);
        if(len == 0)
            break;
        s = va_arg(ap, const char*);
        append_component(context, p, s, len);
    }
}

static void
va_princ(krb5_context context, krb5_principal p, va_list ap)
{
    while(1){
        const char *s;
        s = va_arg(ap, const char*);
        if(s == NULL)
            break;
        append_component(context, p, s, strlen(s));
    }
}


static krb5_error_code
build_principal(krb5_context context,
                krb5_principal *principal,
                int rlen,
                krb5_const_realm realm,
                void (*func)(krb5_context, krb5_principal, va_list),
                va_list ap)
{
    krb5_principal p;

    p = calloc(1, sizeof(*p));
    if (p == NULL) {
        krb5_set_error_message(context, ENOMEM,
                               N_("malloc: out of memory", ""));
        return ENOMEM;
    }
    princ_type(p) = KRB5_NT_PRINCIPAL;

    princ_realm(p) = strdup(realm);
    if(p->realm == NULL){
        free(p);
        krb5_set_error_message(context, ENOMEM,
                               N_("malloc: out of memory", ""));
        return ENOMEM;
    }

    (*func)(context, p, ap);
    *principal = p;
    return 0;
}

krb5_error_code KRB5_LIB_FUNCTION
krb5_make_principal(krb5_context context,
                    krb5_principal *principal,
                    krb5_const_realm realm,
                    ...)
{
    krb5_error_code ret;
    krb5_realm r = NULL;
    va_list ap;
    if(realm == NULL) {
        ret = krb5_get_default_realm(context, &r);
        if(ret)
            return ret;
        realm = r;
    }
    va_start(ap, realm);
    ret = krb5_build_principal_va(context, principal, strlen(realm), realm, ap);
    va_end(ap);
    if(r)
        free(r);
    return ret;
}

krb5_error_code KRB5_LIB_FUNCTION
krb5_build_principal_va(krb5_context context,
                        krb5_principal *principal,
                        int rlen,
                        krb5_const_realm realm,
                        va_list ap)
{
    return build_principal(context, principal, rlen, realm, va_princ, ap);
}

krb5_error_code KRB5_LIB_FUNCTION
krb5_build_principal_va_ext(krb5_context context,
                            krb5_principal *principal,
                            int rlen,
                            krb5_const_realm realm,
                            va_list ap)
{
    return build_principal(context, principal, rlen, realm, va_ext_princ, ap);
}


krb5_error_code KRB5_LIB_FUNCTION
krb5_build_principal_ext(krb5_context context,
                         krb5_principal *principal,
                         int rlen,
                         krb5_const_realm realm,
                         ...)
{
    krb5_error_code ret;
    va_list ap;
    va_start(ap, realm);
    ret = krb5_build_principal_va_ext(context, principal, rlen, realm, ap);
    va_end(ap);
    return ret;
}


krb5_error_code KRB5_LIB_FUNCTION
krb5_copy_principal(krb5_context context,
                    krb5_const_principal inprinc,
                    krb5_principal *outprinc)
{
    krb5_principal p = malloc(sizeof(*p));
    if (p == NULL) {
        krb5_set_error_message(context, ENOMEM,
                               N_("malloc: out of memory", ""));
        return ENOMEM;
    }
    if(copy_Principal(inprinc, p)) {
        free(p);
        krb5_set_error_message(context, ENOMEM,
                               N_("malloc: out of memory", ""));
        return ENOMEM;
    }
    *outprinc = p;
    return 0;
}

/*
 * return TRUE iff princ1 == princ2 (without considering the realm)
 */

krb5_boolean KRB5_LIB_FUNCTION
krb5_principal_compare_any_realm(krb5_context context,
                                 krb5_const_principal princ1,
                                 krb5_const_principal princ2)
{
    int i;
    if(princ_num_comp(princ1) != princ_num_comp(princ2))
        return FALSE;
    for(i = 0; i < princ_num_comp(princ1); i++){
        if(strcmp(princ_ncomp(princ1, i), princ_ncomp(princ2, i)) != 0)
            return FALSE;
    }
    return TRUE;
}

krb5_boolean KRB5_LIB_FUNCTION
_krb5_principal_compare_PrincipalName(krb5_context context,
                                      krb5_const_principal princ1,
                                      PrincipalName *princ2)
{
    int i;
    if (princ_num_comp(princ1) != princ2->name_string.len)
        return FALSE;
    for(i = 0; i < princ_num_comp(princ1); i++){
        if(strcmp(princ_ncomp(princ1, i), princ2->name_string.val[i]) != 0)
            return FALSE;
    }
    return TRUE;
}


/*
 * return TRUE iff princ1 == princ2
 */

krb5_boolean KRB5_LIB_FUNCTION
krb5_principal_compare(krb5_context context,
                       krb5_const_principal princ1,
                       krb5_const_principal princ2)
{
    if(!krb5_realm_compare(context, princ1, princ2))
        return FALSE;
    return krb5_principal_compare_any_realm(context, princ1, princ2);
}

/*
 * return TRUE iff realm(princ1) == realm(princ2)
 */

krb5_boolean KRB5_LIB_FUNCTION
krb5_realm_compare(krb5_context context,
                   krb5_const_principal princ1,
                   krb5_const_principal princ2)
{
    return strcmp(princ_realm(princ1), princ_realm(princ2)) == 0;
}

/*
 * return TRUE iff princ matches pattern
 */

krb5_boolean KRB5_LIB_FUNCTION
krb5_principal_match(krb5_context context,
                     krb5_const_principal princ,
                     krb5_const_principal pattern)
{
    int i;
    if(princ_num_comp(princ) != princ_num_comp(pattern))
        return FALSE;
    if(fnmatch(princ_realm(pattern), princ_realm(princ), 0) != 0)
        return FALSE;
    for(i = 0; i < princ_num_comp(princ); i++){
        if(fnmatch(princ_ncomp(pattern, i), princ_ncomp(princ, i), 0) != 0)
            return FALSE;
    }
    return TRUE;
}

#if defined(KRB4) || !defined(HEIMDAL_SMALLER)

static struct v4_name_convert {
    const char *from;
    const char *to;
} default_v4_name_convert[] = {
    { "ftp",    "ftp" },
    { "hprop",  "hprop" },
    { "pop",    "pop" },
    { "imap",   "imap" },
    { "rcmd",   "host" },
    { "smtp",   "smtp" },
    { NULL, NULL }
};

#endif

#ifdef KRB4

/*
 * return the converted instance name of `name' in `realm'.
 * look in the configuration file and then in the default set above.
 * return NULL if no conversion is appropriate.
 */

static const char*
get_name_conversion(krb5_context context, const char *realm, const char *name)
{
    struct v4_name_convert *q;
    const char *p;

    p = krb5_config_get_string(context, NULL, "realms", realm,
                               "v4_name_convert", "host", name, NULL);
    if(p == NULL)
        p = krb5_config_get_string(context, NULL, "libdefaults",
                                   "v4_name_convert", "host", name, NULL);
    if(p)
        return p;

    /* XXX should be possible to override default list */
    p = krb5_config_get_string(context, NULL,
                               "realms",
                               realm,
                               "v4_name_convert",
                               "plain",
                               name,
                               NULL);
    if(p)
        return NULL;
    p = krb5_config_get_string(context, NULL,
                               "libdefaults",
                               "v4_name_convert",
                               "plain",
                               name,
                               NULL);
    if(p)
        return NULL;
    for(q = default_v4_name_convert; q->from; q++)
        if(strcmp(q->from, name) == 0)
            return q->to;
    return NULL;
}

/*
 * convert the v4 principal `name.instance@realm' to a v5 principal in `princ'.
 * if `resolve', use DNS.
 * if `func', use that function for validating the conversion
 */

krb5_error_code KRB5_LIB_FUNCTION
krb5_425_conv_principal_ext2(krb5_context context,
                             const char *name,
                             const char *instance,
                             const char *realm,
                             krb5_boolean (*func)(krb5_context,
                                                  void *, krb5_principal),
                             void *funcctx,
                             krb5_boolean resolve,
                             krb5_principal *princ)
{
    const char *p;
    krb5_error_code ret;
    krb5_principal pr;
    char host[MAXHOSTNAMELEN];
    char local_hostname[MAXHOSTNAMELEN];

    /* do the following: if the name is found in the
       `v4_name_convert:host' part, is assumed to be a `host' type
       principal, and the instance is looked up in the
       `v4_instance_convert' part. if not found there the name is
       (optionally) looked up as a hostname, and if that doesn't yield
       anything, the `default_domain' is appended to the instance
       */

    if(instance == NULL)
        goto no_host;
    if(instance[0] == 0){
        instance = NULL;
        goto no_host;
    }
    p = get_name_conversion(context, realm, name);
    if(p == NULL)
        goto no_host;
    name = p;
    p = krb5_config_get_string(context, NULL, "realms", realm,
                               "v4_instance_convert", instance, NULL);
    if(p){
        instance = p;
        ret = krb5_make_principal(context, &pr, realm, name, instance, NULL);
        if (ret)
            return ret;
        if(func == NULL || (*func)(context, funcctx, pr)){
            *princ = pr;
            return 0;
        }
        krb5_free_principal(context, pr);
        *princ = NULL;
        krb5_clear_error_message (context);
        return HEIM_ERR_V4_PRINC_NO_CONV;
    }
    if(resolve){
        krb5_boolean passed = FALSE;
        char *inst = NULL;
#ifdef USE_RESOLVER
        struct rk_dns_reply *r;

        r = rk_dns_lookup(instance, "aaaa");
        if (r) {
            if (r->head && r->head->type == rk_ns_t_aaaa) {
                inst = strdup(r->head->domain);
                passed = TRUE;
            }
            rk_dns_free_data(r);
        } else {
            r = rk_dns_lookup(instance, "a");
            if (r) {
                if(r->head && r->head->type == rk_ns_t_a) {
                    inst = strdup(r->head->domain);
                    passed = TRUE;
                }
                rk_dns_free_data(r);
            }
        }
#else
        struct addrinfo hints, *ai;
        
        memset (&hints, 0, sizeof(hints));
        hints.ai_flags = AI_CANONNAME;
        ret = getaddrinfo(instance, NULL, &hints, &ai);
        if (ret == 0) {
            const struct addrinfo *a;
            for (a = ai; a != NULL; a = a->ai_next) {
                if (a->ai_canonname != NULL) {
                    inst = strdup (a->ai_canonname);
                    passed = TRUE;
                    break;
                }
            }
            freeaddrinfo (ai);
        }
#endif
        if (passed) {
            if (inst == NULL) {
                krb5_set_error_message(context, ENOMEM,
                                       N_("malloc: out of memory", ""));
                return ENOMEM;
            }
            strlwr(inst);
            ret = krb5_make_principal(context, &pr, realm, name, inst,
                                      NULL);
            free (inst);
            if(ret == 0) {
                if(func == NULL || (*func)(context, funcctx, pr)){
                    *princ = pr;
                    return 0;
                }
                krb5_free_principal(context, pr);
            }
        }
    }
    if(func != NULL) {
        snprintf(host, sizeof(host), "%s.%s", instance, realm);
        strlwr(host);
        ret = krb5_make_principal(context, &pr, realm, name, host, NULL);
        if (ret)
            return ret;
        if((*func)(context, funcctx, pr)){
            *princ = pr;
            return 0;
        }
        krb5_free_principal(context, pr);
    }

    /*
     * if the instance is the first component of the local hostname,
     * the converted host should be the long hostname.
     */

    if (func == NULL &&
        gethostname (local_hostname, sizeof(local_hostname)) == 0 &&
        strncmp(instance, local_hostname, strlen(instance)) == 0 &&
        local_hostname[strlen(instance)] == '.') {
        strlcpy(host, local_hostname, sizeof(host));
        goto local_host;
    }

    {
        char **domains, **d;
        domains = krb5_config_get_strings(context, NULL, "realms", realm,
                                          "v4_domains", NULL);
        for(d = domains; d && *d; d++){
            snprintf(host, sizeof(host), "%s.%s", instance, *d);
            ret = krb5_make_principal(context, &pr, realm, name, host, NULL);
            if (ret) {
                krb5_config_free_strings(domains);
                return ret;
            }
            if(func == NULL || (*func)(context, funcctx, pr)){
                *princ = pr;
                krb5_config_free_strings(domains);
                return 0;
            }
            krb5_free_principal(context, pr);
        }
        krb5_config_free_strings(domains);
    }


    p = krb5_config_get_string(context, NULL, "realms", realm,
                               "default_domain", NULL);
    if(p == NULL){
        /* this should be an error, just faking a name is not good */
        krb5_clear_error_message (context);
        return HEIM_ERR_V4_PRINC_NO_CONV;
    }
        
    if (*p == '.')
        ++p;
    snprintf(host, sizeof(host), "%s.%s", instance, p);
local_host:
    ret = krb5_make_principal(context, &pr, realm, name, host, NULL);
    if (ret)
        return ret;
    if(func == NULL || (*func)(context, funcctx, pr)){
        *princ = pr;
        return 0;
    }
    krb5_free_principal(context, pr);
    krb5_clear_error_message (context);
    return HEIM_ERR_V4_PRINC_NO_CONV;
no_host:
    p = krb5_config_get_string(context, NULL,
                               "realms",
                               realm,
                               "v4_name_convert",
                               "plain",
                               name,
                               NULL);
    if(p == NULL)
        p = krb5_config_get_string(context, NULL,
                                   "libdefaults",
                                   "v4_name_convert",
                                   "plain",
                                   name,
                                   NULL);
    if(p)
        name = p;

    ret = krb5_make_principal(context, &pr, realm, name, instance, NULL);
    if (ret)
        return ret;
    if(func == NULL || (*func)(context, funcctx, pr)){
        *princ = pr;
        return 0;
    }
    krb5_free_principal(context, pr);
    krb5_clear_error_message (context);
    return HEIM_ERR_V4_PRINC_NO_CONV;
}

#endif /* KRB4 */

#ifndef HEIMDAL_SMALLER

static int
check_list(const krb5_config_binding *l, const char *name, const char **out)
{
    while(l){
        if (l->type != krb5_config_string)
            continue;
        if(strcmp(name, l->u.string) == 0) {
            *out = l->name;
            return 1;
        }
        l = l->next;
    }
    return 0;
}

static int
name_convert(krb5_context context, const char *name, const char *realm,
             const char **out)
{
    const krb5_config_binding *l;
    l = krb5_config_get_list (context,
                              NULL,
                              "realms",
                              realm,
                              "v4_name_convert",
                              "host",
                              NULL);
    if(l && check_list(l, name, out))
        return KRB5_NT_SRV_HST;
    l = krb5_config_get_list (context,
                              NULL,
                              "libdefaults",
                              "v4_name_convert",
                              "host",
                              NULL);
    if(l && check_list(l, name, out))
        return KRB5_NT_SRV_HST;
    l = krb5_config_get_list (context,
                              NULL,
                              "realms",
                              realm,
                              "v4_name_convert",
                              "plain",
                              NULL);
    if(l && check_list(l, name, out))
        return KRB5_NT_UNKNOWN;
    l = krb5_config_get_list (context,
                              NULL,
                              "libdefaults",
                              "v4_name_convert",
                              "host",
                              NULL);
    if(l && check_list(l, name, out))
        return KRB5_NT_UNKNOWN;

    /* didn't find it in config file, try built-in list */
    {
        struct v4_name_convert *q;
        for(q = default_v4_name_convert; q->from; q++) {
            if(strcmp(name, q->to) == 0) {
                *out = q->from;
                return KRB5_NT_SRV_HST;
            }
        }
    }
    return -1;
}

/*
 * convert the v5 principal in `principal' into a v4 corresponding one
 * in `name, instance, realm'
 * this is limited interface since there's no length given for these
 * three parameters.  They have to be 40 bytes each (ANAME_SZ).
 */

krb5_error_code KRB5_LIB_FUNCTION
krb5_524_conv_principal(krb5_context context,
                        const krb5_principal principal,
                        char *name,
                        char *instance,
                        char *realm)
{
    const char *n, *i, *r;
    char tmpinst[40];
    int type = princ_type(principal);
    const int aname_sz = 40;

    r = principal->realm;

    switch(principal->name.name_string.len){
    case 1:
        n = principal->name.name_string.val[0];
        i = "";
        break;
    case 2:
        n = principal->name.name_string.val[0];
        i = principal->name.name_string.val[1];
        break;
    default:
        krb5_set_error_message(context, KRB5_PARSE_MALFORMED,
                               N_("cannot convert a %d "
                                  "component principal", ""),
                               principal->name.name_string.len);
        return KRB5_PARSE_MALFORMED;
    }

    {
        const char *tmp;
        int t = name_convert(context, n, r, &tmp);
        if(t >= 0) {
            type = t;
            n = tmp;
        }
    }

    if(type == KRB5_NT_SRV_HST){
        char *p;

        strlcpy (tmpinst, i, sizeof(tmpinst));
        p = strchr(tmpinst, '.');
        if(p)
            *p = 0;
        i = tmpinst;
    }

    if (strlcpy (name, n, aname_sz) >= aname_sz) {
        krb5_set_error_message(context, KRB5_PARSE_MALFORMED,
                               N_("too long name component to convert", ""));
        return KRB5_PARSE_MALFORMED;
    }
    if (strlcpy (instance, i, aname_sz) >= aname_sz) {
        krb5_set_error_message(context, KRB5_PARSE_MALFORMED,
                               N_("too long instance component to convert", ""));
        return KRB5_PARSE_MALFORMED;
    }
    if (strlcpy (realm, r, aname_sz) >= aname_sz) {
        krb5_set_error_message(context, KRB5_PARSE_MALFORMED,
                               N_("too long realm component to convert", ""));
        return KRB5_PARSE_MALFORMED;
    }
    return 0;
}

#endif /* !HEIMDAL_SMALLER */

/**
 * Create a principal for the service running on hostname. If
 * KRB5_NT_SRV_HST is used, the hostname is canonization using DNS (or
 * some other service), this is potentially insecure.
 *
 * @param context A Kerberos context.
 * @param hostname hostname to use
 * @param sname Service name to use
 * @param type name type of pricipal, use KRB5_NT_SRV_HST or KRB5_NT_UNKNOWN.
 * @param ret_princ return principal, free with krb5_free_principal().
 *
 * @return An krb5 error code, see krb5_get_error_message().
 *
 * @ingroup krb5_principal
 */
                        
krb5_error_code KRB5_LIB_FUNCTION
krb5_sname_to_principal (krb5_context context,
                         const char *hostname,
                         const char *sname,
                         int32_t type,
                         krb5_principal *ret_princ)
{
    krb5_error_code ret;
    char localhost[MAXHOSTNAMELEN];
    char **realms, *host = NULL;
        
    if(type != KRB5_NT_SRV_HST && type != KRB5_NT_UNKNOWN) {
        krb5_set_error_message(context, KRB5_SNAME_UNSUPP_NAMETYPE,
                               N_("unsupported name type %d", ""),
                               (int)type);
        return KRB5_SNAME_UNSUPP_NAMETYPE;
    }
    if(hostname == NULL) {
        ret = gethostname(localhost, sizeof(localhost) - 1);
        if (ret != 0) {
            ret = errno;
            krb5_set_error_message(context, ret,
                                   N_("Failed to get local hostname", ""));
            return ret;
        }       
        localhost[sizeof(localhost) - 1] = '\0';
        hostname = localhost;
    }
    if(sname == NULL)
        sname = "host";
    if(type == KRB5_NT_SRV_HST) {
        ret = krb5_expand_hostname_realms (context, hostname,
                                           &host, &realms);
        if (ret)
            return ret;
        strlwr(host);
        hostname = host;
    } else {
        ret = krb5_get_host_realm(context, hostname, &realms);
        if(ret)
            return ret;
    }

    ret = krb5_make_principal(context, ret_princ, realms[0], sname,
                              hostname, NULL);
    if(host)
        free(host);
    krb5_free_host_realm(context, realms);
    return ret;
}

static const struct {
    const char *type;
    int32_t value;
} nametypes[] = {
    { "UNKNOWN", KRB5_NT_UNKNOWN },
    { "PRINCIPAL", KRB5_NT_PRINCIPAL },
    { "SRV_INST", KRB5_NT_SRV_INST },
    { "SRV_HST", KRB5_NT_SRV_HST },
    { "SRV_XHST", KRB5_NT_SRV_XHST },
    { "UID", KRB5_NT_UID },
    { "X500_PRINCIPAL", KRB5_NT_X500_PRINCIPAL },
    { "SMTP_NAME", KRB5_NT_SMTP_NAME },
    { "ENTERPRISE_PRINCIPAL", KRB5_NT_ENTERPRISE_PRINCIPAL },
    { "ENT_PRINCIPAL_AND_ID", KRB5_NT_ENT_PRINCIPAL_AND_ID },
    { "MS_PRINCIPAL", KRB5_NT_MS_PRINCIPAL },
    { "MS_PRINCIPAL_AND_ID", KRB5_NT_MS_PRINCIPAL_AND_ID },
    { NULL }
};

krb5_error_code
krb5_parse_nametype(krb5_context context, const char *str, int32_t *nametype)
{
    size_t i;

    for(i = 0; nametypes[i].type; i++) {
        if (strcasecmp(nametypes[i].type, str) == 0) {
            *nametype = nametypes[i].value;
            return 0;
        }
    }
    krb5_set_error_message(context, KRB5_PARSE_MALFORMED,
                           N_("Failed to find name type %s", ""), str);
    return KRB5_PARSE_MALFORMED;
}