X509_get_version, X509_set_version, X509_REQ_get_version, X509_REQ_set_version,
  X509_CRL_get_version, X509_CRL_set_version - get or set certificate,
  certificate request or CRL version
 #include <openssl/x509.h>
 long X509_get_version(const X509 *x);
 int X509_set_version(X509 *x, long version);
 long X509_REQ_get_version(const X509_REQ *req);
 int X509_REQ_set_version(X509_REQ *x, long version);
 long X509_CRL_get_version(const X509_CRL *crl);
 int X509_CRL_set_version(X509_CRL *x, long version);
X509_get_version() returns the numerical value of the version field of
  certificate x. These correspond to the constants X509_VERSION_1,
  X509_VERSION_2, and X509_VERSION_3. Note: the values of these
  constants are defined by standards (X.509 et al) to be one less than the
  certificate version. So X509_VERSION_3 has value 2 and
  X509_VERSION_1 has value 0.
X509_set_version() sets the numerical value of the version
    field of certificate x to version.
Similarly X509_REQ_get_version(),
    X509_REQ_set_version(), X509_CRL_get_version() and
    X509_CRL_set_version() get and set the version number of certificate
    requests and CRLs. They use constants X509_REQ_VERSION_1,
    X509_CRL_VERSION_1, and X509_CRL_VERSION_2.
The version field of certificates, certificate requests and CRLs has a DEFAULT
  value of v1(0) meaning the field should be omitted for
  version 1. This is handled transparently by these functions.
X509_get_version(), X509_REQ_get_version() and
  X509_CRL_get_version() return the numerical value of the version field.
X509_set_version(), X509_REQ_set_version() and
    X509_CRL_set_version() return 1 for success and 0 for failure.
d2i_X509(3), ERR_get_error(3), X509_CRL_get0_by_serial(3),
  X509_get0_signature(3), X509_get_ext_d2i(3),
  X509_get_extension_flags(3), X509_get_pubkey(3),
  X509_get_subject_name(3), X509_NAME_add_entry_by_txt(3),
  X509_NAME_ENTRY_get_object(3), X509_NAME_get_index_by_NID(3),
  X509_NAME_print_ex(3), X509_new(3), X509_sign(3),
  X509V3_get_d2i(3), X509_verify_cert(3)
X509_get_version(), X509_REQ_get_version() and
  X509_CRL_get_version() are functions in OpenSSL 1.1.0, in previous
  versions they were macros.
Copyright 2015-2021 The OpenSSL Project Authors. All Rights Reserved.
Licensed under the Apache License 2.0 (the "License").
    You may not use this file except in compliance with the License. You can
    obtain a copy in the file LICENSE in the source distribution or at
    <https://www.openssl.org/source/license.html>.