/*

 * Copyright (C) 2015 Red Hat, Inc.

 *

 * Author: Nikos Mavrogiannopoulos

 *

 * This file is part of GnuTLS.

 *

 * The GnuTLS is free software; you can redistribute it and/or

 * modify it under the terms of the GNU Lesser General Public License

 * as published by the Free Software Foundation; either version 2.1 of

 * the License, or (at your option) any later version.

 *

 * This library is distributed in the hope that it will be useful, but

 * WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

 * Lesser General Public License for more details.

 *

 * You should have received a copy of the GNU Lesser General Public License

 * along with this program.  If not, see <https://www.gnu.org/licenses/>

 *

 */

#include "config.h"

#include <gnutls/gnutls.h>

#include <libtasn1.h>

#include <string.h>

#include <stdint.h>

#include <stdlib.h>

#include "errors.h"

#include "krb5.h"

#include "common.h"

#define _gnutls_asn2err(x) GNUTLS_E_ASN1_DER_ERROR

#define MAX_COMPONENTS 6

typedef struct krb5_principal_data {

  char *realm;

  char *data[MAX_COMPONENTS];

  uint32_t length;

  int8_t type;

} krb5_principal_data;

extern const asn1_static_node krb5_asn1_tab[];

static void cleanup_principal(krb5_principal_data *princ)

{

  unsigned i;

  if (princ) {

    gnutls_free(princ->realm);

    for (i = 0; i < princ->length; i++)

      gnutls_free(princ->data[i]);

    memset(princ, 0, sizeof(*princ));

    gnutls_free(princ);

  }

}

static krb5_principal_data *name_to_principal(const char *_name)

{

  krb5_principal_data *princ;

  char *p, *p2, *sp;

  unsigned pos = 0;

  char *name = NULL;

  princ = gnutls_calloc(1, sizeof(struct krb5_principal_data));

  if (princ == NULL)

    return NULL;

  name = gnutls_strdup(_name);

  if (name == NULL) {

    gnutls_assert();

    goto fail;

  }

  p = strrchr(name, '@');

  p2 = strchr(name, '@');

  if (p == NULL) {

    /* unknown name type */

    gnutls_assert();

    goto fail;

  }

  princ->realm = gnutls_strdup(p + 1);

  if (princ->realm == NULL) {

    gnutls_assert();

    goto fail;

  }

  *p = 0;

  if (p == p2) {

    p = strtok_r(name, "/", &sp);

    while (p) {

      if (pos == MAX_COMPONENTS) {

        _gnutls_debug_log(

          "%s: Cannot parse names with more than %d components\n",

          __func__, MAX_COMPONENTS);

        goto fail;

      }

      princ->data[pos] = gnutls_strdup(p);

      if (princ->data[pos] == NULL) {

        gnutls_assert();

        goto fail;

      }

      princ->length++;

      pos++;

      p = strtok_r(NULL, "/", &sp);

    }

    if ((princ->length == 2) &&

        (strcmp(princ->data[0], "krbtgt") == 0)) {

      princ->type = 2; /* KRB_NT_SRV_INST */

    } else {

      princ->type = 1; /* KRB_NT_PRINCIPAL */

    }

  } else { /* enterprise */

    princ->data[0] = gnutls_strdup(name);

    if (princ->data[0] == NULL) {

      gnutls_assert();

      goto fail;

    }

    princ->length++;

    princ->type = 10; /* KRB_NT_ENTERPRISE */

  }

  goto cleanup;

fail:

  cleanup_principal(princ);

  princ = NULL;

cleanup:

  gnutls_free(name);

  return princ;

}

int _gnutls_krb5_principal_to_der(const char *name, gnutls_datum_t *der)

{

  int ret, result;

  asn1_node c2 = NULL;

  krb5_principal_data *princ;

  unsigned i;

  princ = name_to_principal(name);

  if (princ == NULL) {

    gnutls_assert();

    ret = GNUTLS_E_PARSING_ERROR;

    goto cleanup;

  }

  result = asn1_create_element(_gnutls_get_gnutls_asn(),

             "GNUTLS.KRB5PrincipalName", &c2);

  if (result != ASN1_SUCCESS) {

    gnutls_assert();

    ret = _gnutls_asn2err(result);

    goto cleanup;

  }

  result = asn1_write_value(c2, "realm", princ->realm,

          strlen(princ->realm));

  if (result != ASN1_SUCCESS) {

    gnutls_assert();

    ret = _gnutls_asn2err(result);

    goto cleanup;

  }

  result = asn1_write_value(c2, "principalName.name-type", &princ->type,

          1);

  if (result != ASN1_SUCCESS) {

    gnutls_assert();

    ret = _gnutls_asn2err(result);

    goto cleanup;

  }

  for (i = 0; i < princ->length; i++) {

    result = asn1_write_value(c2, "principalName.name-string",

            "NEW", 1);

    if (result != ASN1_SUCCESS) {

      gnutls_assert();

      ret = _gnutls_asn2err(result);

      goto cleanup;

    }

    result = asn1_write_value(c2, "principalName.name-string.?LAST",

            princ->data[i],

            strlen(princ->data[i]));

    if (result != ASN1_SUCCESS) {

      gnutls_assert();

      ret = _gnutls_asn2err(result);

      goto cleanup;

    }

  }

  ret = _gnutls_x509_der_encode(c2, "", der, 0);

  if (ret < 0) {

    gnutls_assert();

    goto cleanup;

  }

  ret = 0;

cleanup:

  cleanup_principal(princ);

  asn1_delete_structure(&c2);

  return ret;

}

static int principal_to_str(asn1_node c2, gnutls_buffer_st *str)

{

  gnutls_datum_t realm = { NULL, 0 };

  gnutls_datum_t component = { NULL, 0 };

  unsigned char name_type[2];

  int ret, result, len;

  unsigned i;

  char val[128];

  ret = _gnutls_x509_read_value(c2, "realm", &realm);

  if (ret < 0) {

    gnutls_assert();

    return ret;

  }

  len = sizeof(name_type);

  result =

    asn1_read_value(c2, "principalName.name-type", name_type, &len);

  if (result != ASN1_SUCCESS) {

    gnutls_assert();

    ret = _gnutls_asn2err(result);

    goto cleanup;

  }

  if (len != 1 ||

      (name_type[0] != 1 && name_type[0] != 2 && name_type[0] != 10)) {

    ret = GNUTLS_E_INVALID_REQUEST;

    goto cleanup;

  }

  for (i = 0;; i++) {

    snprintf(val, sizeof(val), "principalName.name-string.?%u",

       i + 1);

    ret = _gnutls_x509_read_value(c2, val, &component);

    if (ret == GNUTLS_E_ASN1_VALUE_NOT_FOUND ||

        ret == GNUTLS_E_ASN1_ELEMENT_NOT_FOUND)

      break;

    if (ret < 0) {

      gnutls_assert();

      goto cleanup;

    }

    if (i > 0) {

      ret = _gnutls_buffer_append_data(str, "/", 1);

      if (ret < 0) {

        gnutls_assert();

        goto cleanup;

      }

    }

    ret = _gnutls_buffer_append_data(str, component.data,

             component.size);

    if (ret < 0) {

      gnutls_assert();

      goto cleanup;

    }

    _gnutls_free_datum(&component);

  }

  ret = _gnutls_buffer_append_data(str, "@", 1);

  if (ret < 0) {

    gnutls_assert();

    goto cleanup;

  }

  ret = _gnutls_buffer_append_data(str, realm.data, realm.size);

  if (ret < 0) {

    gnutls_assert();

    goto cleanup;

  }

  ret = 0;

cleanup:

  _gnutls_free_datum(&component);

  gnutls_free(realm.data);

  return ret;

}

int _gnutls_krb5_der_to_principal(const gnutls_datum_t *der,

          gnutls_datum_t *name)

{

  int ret, result;

  asn1_node c2 = NULL;

  gnutls_buffer_st str;

  _gnutls_buffer_init(&str);

  result = asn1_create_element(_gnutls_get_gnutls_asn(),

             "GNUTLS.KRB5PrincipalName", &c2);

  if (result != ASN1_SUCCESS) {

    gnutls_assert();

    ret = _gnutls_asn2err(result);

    goto cleanup;

  }

  result = asn1_der_decoding(&c2, der->data, der->size, NULL);

  if (result != ASN1_SUCCESS) {

    gnutls_assert();

    ret = _gnutls_asn2err(result);

    goto cleanup;

  }

  ret = principal_to_str(c2, &str);

  if (ret < 0) {

    /* for some reason we cannot convert to a human readable string

     * the principal. Then we use the #HEX format.

     */

    _gnutls_buffer_reset(&str);

    ret = _gnutls_buffer_append_data(&str, "#", 1);

    if (ret < 0) {

      gnutls_assert();

      goto cleanup;

    }

    _gnutls_buffer_hexprint(&str, der->data, der->size);

  }

  asn1_delete_structure(&c2);

  return _gnutls_buffer_to_datum(&str, name, 1);

cleanup:

  _gnutls_buffer_clear(&str);

  asn1_delete_structure(&c2);

  return ret;

}