// Copyright 1999-2016 The OpenSSL Project Authors. All Rights Reserved.

//

// Licensed under the Apache License, Version 2.0 (the "License");

// you may not use this file except in compliance with the License.

// You may obtain a copy of the License at

//

//     https://www.apache.org/licenses/LICENSE-2.0

//

// Unless required by applicable law or agreed to in writing, software

// distributed under the License is distributed on an "AS IS" BASIS,

// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

// See the License for the specific language governing permissions and

// limitations under the License.

// extension creation utilities

#include <ctype.h>

#include <limits.h>

#include <stdio.h>

#include <string.h>

#include <openssl/conf.h>

#include <openssl/err.h>

#include <openssl/mem.h>

#include <openssl/obj.h>

#include <openssl/x509.h>

#include "../internal.h"

#include "internal.h"

static int v3_check_critical(const char **value);

static int v3_check_generic(const char **value);

static X509_EXTENSION *do_ext_nconf(const CONF *conf, const X509V3_CTX *ctx,

                                    int ext_nid, int crit, const char *value);

static X509_EXTENSION *v3_generic_extension(const char *ext, const char *value,

                                            int crit, int type,

                                            const X509V3_CTX *ctx);

static X509_EXTENSION *do_ext_i2d(const X509V3_EXT_METHOD *method, int ext_nid,

                                  int crit, void *ext_struc);

static unsigned char *generic_asn1(const char *value, const X509V3_CTX *ctx,

                                   size_t *ext_len);

X509_EXTENSION *X509V3_EXT_nconf(const CONF *conf, const X509V3_CTX *ctx,

                                 const char *name, const char *value) {

  // If omitted, fill in an empty |X509V3_CTX|.

  X509V3_CTX ctx_tmp;

  if (ctx == nullptr) {

    X509V3_set_ctx(&ctx_tmp, nullptr, nullptr, nullptr, nullptr, 0);

    X509V3_set_nconf(&ctx_tmp, conf);

    ctx = &ctx_tmp;

  }

  int crit = v3_check_critical(&value);

  int ext_type = v3_check_generic(&value);

  if (ext_type != 0) {

    return v3_generic_extension(name, value, crit, ext_type, ctx);

  }

  X509_EXTENSION *ret = do_ext_nconf(conf, ctx, OBJ_sn2nid(name), crit, value);

  if (!ret) {

    OPENSSL_PUT_ERROR(X509V3, X509V3_R_ERROR_IN_EXTENSION);

    ERR_add_error_data(4, "name=", name, ", value=", value);

  }

  return ret;

}

X509_EXTENSION *X509V3_EXT_nconf_nid(const CONF *conf, const X509V3_CTX *ctx,

                                     int ext_nid, const char *value) {

  // If omitted, fill in an empty |X509V3_CTX|.

  X509V3_CTX ctx_tmp;

  if (ctx == nullptr) {

    X509V3_set_ctx(&ctx_tmp, nullptr, nullptr, nullptr, nullptr, 0);

    X509V3_set_nconf(&ctx_tmp, conf);

    ctx = &ctx_tmp;

  }

  int crit = v3_check_critical(&value);

  int ext_type = v3_check_generic(&value);

  if (ext_type != 0) {

    return v3_generic_extension(OBJ_nid2sn(ext_nid), value, crit, ext_type,

                                ctx);

  }

  return do_ext_nconf(conf, ctx, ext_nid, crit, value);

}

// CONF *conf:  Config file

// char *value:  Value

static X509_EXTENSION *do_ext_nconf(const CONF *conf, const X509V3_CTX *ctx,

                                    int ext_nid, int crit, const char *value) {

  const X509V3_EXT_METHOD *method;

  X509_EXTENSION *ext;

  const STACK_OF(CONF_VALUE) *nval;

  STACK_OF(CONF_VALUE) *nval_owned = nullptr;

  void *ext_struc;

  if (ext_nid == NID_undef) {

    OPENSSL_PUT_ERROR(X509V3, X509V3_R_UNKNOWN_EXTENSION_NAME);

    return nullptr;

  }

  if (!(method = X509V3_EXT_get_nid(ext_nid))) {

    OPENSSL_PUT_ERROR(X509V3, X509V3_R_UNKNOWN_EXTENSION);

    return nullptr;

  }

  // Now get internal extension representation based on type

  if (method->v2i) {

    if (*value == '@') {

      // TODO(davidben): This is the only place where |X509V3_EXT_nconf|'s

      // |conf| parameter is used. All other codepaths use the copy inside

      // |ctx|. Should this be switched and then the parameter ignored?

      if (conf == nullptr) {

        OPENSSL_PUT_ERROR(X509V3, X509V3_R_NO_CONFIG_DATABASE);

        return nullptr;

      }

      nval = NCONF_get_section(conf, value + 1);

    } else {

      nval_owned = X509V3_parse_list(value);

      nval = nval_owned;

    }

    if (nval == nullptr || sk_CONF_VALUE_num(nval) <= 0) {

      OPENSSL_PUT_ERROR(X509V3, X509V3_R_INVALID_EXTENSION_STRING);

      ERR_add_error_data(4, "name=", OBJ_nid2sn(ext_nid), ",section=", value);

      sk_CONF_VALUE_pop_free(nval_owned, X509V3_conf_free);

      return nullptr;

    }

    ext_struc = method->v2i(method, ctx, nval);

    sk_CONF_VALUE_pop_free(nval_owned, X509V3_conf_free);

    if (!ext_struc) {

      return nullptr;

    }

  } else if (method->s2i) {

    if (!(ext_struc = method->s2i(method, ctx, value))) {

      return nullptr;

    }

  } else if (method->r2i) {

    // TODO(davidben): Should this check be removed? This matches OpenSSL, but

    // r2i-based extensions do not necessarily require a config database. The

    // two built-in extensions only use it some of the time, and already handle

    // |X509V3_get_section| returning NULL.

    if (!ctx->db) {

      OPENSSL_PUT_ERROR(X509V3, X509V3_R_NO_CONFIG_DATABASE);

      return nullptr;

    }

    if (!(ext_struc = method->r2i(method, ctx, value))) {

      return nullptr;

    }

  } else {

    OPENSSL_PUT_ERROR(X509V3, X509V3_R_EXTENSION_SETTING_NOT_SUPPORTED);

    ERR_add_error_data(2, "name=", OBJ_nid2sn(ext_nid));

    return nullptr;

  }

  ext = do_ext_i2d(method, ext_nid, crit, ext_struc);

  ASN1_item_free(reinterpret_cast<ASN1_VALUE *>(ext_struc),

                 ASN1_ITEM_ptr(method->it));

  return ext;

}

static X509_EXTENSION *do_ext_i2d(const X509V3_EXT_METHOD *method, int ext_nid,

                                  int crit, void *ext_struc) {

  // Convert the extension's internal representation to DER.

  unsigned char *ext_der = nullptr;

  int ext_len = ASN1_item_i2d(reinterpret_cast<ASN1_VALUE *>(ext_struc),

                              &ext_der, ASN1_ITEM_ptr(method->it));

  if (ext_len < 0) {

    return nullptr;

  }

  ASN1_OCTET_STRING *ext_oct = ASN1_OCTET_STRING_new();

  if (ext_oct == nullptr) {

    OPENSSL_free(ext_der);

    return nullptr;

  }

  ASN1_STRING_set0(ext_oct, ext_der, ext_len);

  X509_EXTENSION *ext =

      X509_EXTENSION_create_by_NID(nullptr, ext_nid, crit, ext_oct);

  ASN1_OCTET_STRING_free(ext_oct);

  return ext;

}

// Given an internal structure, nid and critical flag create an extension

X509_EXTENSION *X509V3_EXT_i2d(int ext_nid, int crit, void *ext_struc) {

  const X509V3_EXT_METHOD *method;

  if (!(method = X509V3_EXT_get_nid(ext_nid))) {

    OPENSSL_PUT_ERROR(X509V3, X509V3_R_UNKNOWN_EXTENSION);

    return nullptr;

  }

  return do_ext_i2d(method, ext_nid, crit, ext_struc);

}

// Check the extension string for critical flag

static int v3_check_critical(const char **value) {

  const char *p = *value;

  if ((strlen(p) < 9) || strncmp(p, "critical,", 9)) {

    return 0;

  }

  p += 9;

  while (OPENSSL_isspace((unsigned char)*p)) {

    p++;

  }

  *value = p;

  return 1;

}

// Check extension string for generic extension and return the type

static int v3_check_generic(const char **value) {

  int gen_type = 0;

  const char *p = *value;

  if ((strlen(p) >= 4) && !strncmp(p, "DER:", 4)) {

    p += 4;

    gen_type = 1;

  } else if ((strlen(p) >= 5) && !strncmp(p, "ASN1:", 5)) {

    p += 5;

    gen_type = 2;

  } else {

    return 0;

  }

  while (OPENSSL_isspace((unsigned char)*p)) {

    p++;

  }

  *value = p;

  return gen_type;

}

// Create a generic extension: for now just handle DER type

static X509_EXTENSION *v3_generic_extension(const char *ext, const char *value,

                                            int crit, int gen_type,

                                            const X509V3_CTX *ctx) {

  bssl::UniquePtr<ASN1_OBJECT> obj(OBJ_txt2obj(ext, 0));

  if (obj == nullptr) {

    OPENSSL_PUT_ERROR(X509V3, X509V3_R_EXTENSION_NAME_ERROR);

    ERR_add_error_data(2, "name=", ext);

    return nullptr;

  }

  bssl::UniquePtr<unsigned char> ext_der;

  size_t ext_len = 0;

  if (gen_type == 1) {

    ext_der.reset(x509v3_hex_to_bytes(value, &ext_len));

  } else if (gen_type == 2) {

    ext_der.reset(generic_asn1(value, ctx, &ext_len));

  }

  if (ext_der == nullptr) {

    OPENSSL_PUT_ERROR(X509V3, X509V3_R_EXTENSION_VALUE_ERROR);

    ERR_add_error_data(2, "value=", value);

    return nullptr;

  }

  if (ext_len > INT_MAX) {

    OPENSSL_PUT_ERROR(X509V3, ERR_R_OVERFLOW);

    return nullptr;

  }

  bssl::UniquePtr<ASN1_OCTET_STRING> oct(ASN1_OCTET_STRING_new());

  if (oct == nullptr) {

    return nullptr;

  }

  ASN1_STRING_set0(oct.get(), ext_der.get(), (int)ext_len);

  ext_der.release();  // ASN1_STRING_set0 took ownership.

  return X509_EXTENSION_create_by_OBJ(nullptr, obj.get(), crit, oct.get());

}

static unsigned char *generic_asn1(const char *value, const X509V3_CTX *ctx,

                                   size_t *ext_len) {

  ASN1_TYPE *typ = ASN1_generate_v3(value, ctx);

  if (typ == nullptr) {

    return nullptr;

  }

  unsigned char *ext_der = nullptr;

  int len = i2d_ASN1_TYPE(typ, &ext_der);

  ASN1_TYPE_free(typ);

  if (len < 0) {

    return nullptr;

  }

  *ext_len = len;

  return ext_der;

}

// This is the main function: add a bunch of extensions based on a config

// file section to an extension STACK.

int X509V3_EXT_add_nconf_sk(const CONF *conf, const X509V3_CTX *ctx,

                            const char *section,

                            STACK_OF(X509_EXTENSION) **sk) {

  const STACK_OF(CONF_VALUE) *nval = NCONF_get_section(conf, section);

  if (nval == nullptr) {

    return 0;

  }

  for (size_t i = 0; i < sk_CONF_VALUE_num(nval); i++) {

    const CONF_VALUE *val = sk_CONF_VALUE_value(nval, i);

    X509_EXTENSION *ext = X509V3_EXT_nconf(conf, ctx, val->name, val->value);

    int ok = ext != nullptr &&  //

             (sk == nullptr || X509v3_add_ext(sk, ext, -1) != nullptr);

    X509_EXTENSION_free(ext);

    if (!ok) {

      return 0;

    }

  }

  return 1;

}

// Convenience functions to add extensions to a certificate, CRL and request

int X509V3_EXT_add_nconf(const CONF *conf, const X509V3_CTX *ctx,

                         const char *section, X509 *cert) {

  STACK_OF(X509_EXTENSION) **sk = nullptr;

  if (cert) {

    sk = &cert->extensions;

  }

  return X509V3_EXT_add_nconf_sk(conf, ctx, section, sk);

}

// Same as above but for a CRL

int X509V3_EXT_CRL_add_nconf(const CONF *conf, const X509V3_CTX *ctx,

                             const char *section, X509_CRL *crl) {

  STACK_OF(X509_EXTENSION) **sk = nullptr;

  if (crl) {

    sk = &crl->crl->extensions;

  }

  return X509V3_EXT_add_nconf_sk(conf, ctx, section, sk);

}

// Add extensions to certificate request

int X509V3_EXT_REQ_add_nconf(const CONF *conf, const X509V3_CTX *ctx,

                             const char *section, X509_REQ *req) {

  STACK_OF(X509_EXTENSION) *extlist = nullptr, **sk = nullptr;

  int i;

  if (req) {

    sk = &extlist;

  }

  i = X509V3_EXT_add_nconf_sk(conf, ctx, section, sk);

  if (!i || !sk) {

    return i;

  }

  i = X509_REQ_add_extensions(req, extlist);

  sk_X509_EXTENSION_pop_free(extlist, X509_EXTENSION_free);

  return i;

}

// Config database functions

const STACK_OF(CONF_VALUE) *X509V3_get_section(const X509V3_CTX *ctx,

                                               const char *section) {

  if (ctx->db == nullptr) {

    OPENSSL_PUT_ERROR(X509V3, X509V3_R_OPERATION_NOT_DEFINED);

    return nullptr;

  }

  return NCONF_get_section(ctx->db, section);

}

void X509V3_set_nconf(X509V3_CTX *ctx, const CONF *conf) { ctx->db = conf; }

void X509V3_set_ctx(X509V3_CTX *ctx, const X509 *issuer, const X509 *subj,

                    const X509_REQ *req, const X509_CRL *crl, int flags) {

  OPENSSL_memset(ctx, 0, sizeof(*ctx));

  ctx->issuer_cert = issuer;

  ctx->subject_cert = subj;

  ctx->crl = crl;

  ctx->subject_req = req;

  ctx->flags = flags;

}