1=pod 2 3=head1 NAME 4 5X509_cmp, X509_NAME_cmp, 6X509_issuer_and_serial_cmp, X509_issuer_name_cmp, X509_subject_name_cmp, 7X509_CRL_cmp, X509_CRL_match 8- compare X509 certificates and related values 9 10=head1 SYNOPSIS 11 12 #include <openssl/x509.h> 13 14 int X509_cmp(const X509 *a, const X509 *b); 15 int X509_NAME_cmp(const X509_NAME *a, const X509_NAME *b); 16 int X509_issuer_and_serial_cmp(const X509 *a, const X509 *b); 17 int X509_issuer_name_cmp(const X509 *a, const X509 *b); 18 int X509_subject_name_cmp(const X509 *a, const X509 *b); 19 int X509_CRL_cmp(const X509_CRL *a, const X509_CRL *b); 20 int X509_CRL_match(const X509_CRL *a, const X509_CRL *b); 21 22=head1 DESCRIPTION 23 24This set of functions are used to compare X509 objects, including X509 25certificates, X509 CRL objects and various values in an X509 certificate. 26 27The X509_cmp() function compares two B<X509> objects indicated by parameters 28I<a> and I<b>. The comparison is based on the B<memcmp> result of the hash 29values of two B<X509> objects and the canonical (DER) encoding values. 30 31The X509_NAME_cmp() function compares two B<X509_NAME> objects indicated by 32parameters I<a> and I<b>. The comparison is based on the B<memcmp> result of the 33canonical (DER) encoding values of the two objects using L<i2d_X509_NAME(3)>. 34This procedure adheres to the matching rules for Distinguished Names (DN) 35given in RFC 4517 section 4.2.15 and RFC 5280 section 7.1. 36In particular, the order of Relative Distinguished Names (RDNs) is relevant. 37On the other hand, if an RDN is multi-valued, i.e., it contains a set of 38AttributeValueAssertions (AVAs), its members are effectively not ordered. 39 40The X509_issuer_and_serial_cmp() function compares the serial number and issuer 41values in the given B<X509> objects I<a> and I<b>. 42 43The X509_issuer_name_cmp(), X509_subject_name_cmp() and X509_CRL_cmp() functions 44are effectively wrappers of the X509_NAME_cmp() function. These functions compare 45issuer names and subject names of the X<509> objects, or issuers of B<X509_CRL> 46objects, respectively. 47 48The X509_CRL_match() function compares two B<X509_CRL> objects. Unlike the 49X509_CRL_cmp() function, this function compares the whole CRL content instead 50of just the issuer name. 51 52=head1 RETURN VALUES 53 54The B<X509> comparison functions return B<-1>, B<0>, or B<1> if object I<a> is 55found to be less than, to match, or be greater than object I<b>, respectively. 56 57X509_NAME_cmp(), X509_issuer_and_serial_cmp(), X509_issuer_name_cmp(), 58X509_subject_name_cmp(), X509_CRL_cmp(), and X509_CRL_match() 59may return B<-2> to indicate an error. 60 61=head1 NOTES 62 63These functions in fact utilize the underlying B<memcmp> of the C library to do 64the comparison job. Data to be compared varies from DER encoding data, hash 65value or B<ASN1_STRING>. The sign of the comparison can be used to order the 66objects but it does not have a special meaning in some cases. 67 68X509_NAME_cmp() and wrappers utilize the value B<-2> to indicate errors in some 69circumstances, which could cause confusion for the applications. 70 71=head1 SEE ALSO 72 73L<i2d_X509_NAME(3)>, L<i2d_X509(3)> 74 75=head1 COPYRIGHT 76 77Copyright 2019-2021 The OpenSSL Project Authors. All Rights Reserved. 78 79Licensed under the Apache License 2.0 (the "License"). You may not use 80this file except in compliance with the License. You can obtain a copy 81in the file LICENSE in the source distribution or at 82L<https://www.openssl.org/source/license.html>. 83 84=cut 85