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 28B<a> and B<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 B<a> and B<b>. The comparison is based on the B<memcmp> result of 33the canonical (DER) encoding values of the two objects. L<i2d_X509_NAME(3)> 34has a more detailed description of the DER encoding of the B<X509_NAME> structure. 35 36The X509_issuer_and_serial_cmp() function compares the serial number and issuer 37values in the given B<X509> objects B<a> and B<b>. 38 39The X509_issuer_name_cmp(), X509_subject_name_cmp() and X509_CRL_cmp() functions 40are effectively wrappers of the X509_NAME_cmp() function. These functions compare 41issuer names and subject names of the X<509> objects, or issuers of B<X509_CRL> 42objects, respectively. 43 44The X509_CRL_match() function compares two B<X509_CRL> objects. Unlike the 45X509_CRL_cmp() function, this function compares the whole CRL content instead 46of just the issuer name. 47 48=head1 RETURN VALUES 49 50Like common memory comparison functions, the B<X509> comparison functions return 51an integer less than, equal to, or greater than zero if object B<a> is found to 52be less than, to match, or be greater than object B<b>, respectively. 53 54X509_NAME_cmp(), X509_issuer_and_serial_cmp(), X509_issuer_name_cmp(), 55X509_subject_name_cmp() and X509_CRL_cmp() may return B<-2> to indicate an error. 56 57=head1 NOTES 58 59These functions in fact utilize the underlying B<memcmp> of the C library to do 60the comparison job. Data to be compared varies from DER encoding data, hash 61value or B<ASN1_STRING>. The sign of the comparison can be used to order the 62objects but it does not have a special meaning in some cases. 63 64X509_NAME_cmp() and wrappers utilize the value B<-2> to indicate errors in some 65circumstances, which could cause confusion for the applications. 66 67=head1 SEE ALSO 68 69L<i2d_X509_NAME(3)>, L<i2d_X509(3)> 70 71=head1 COPYRIGHT 72 73Copyright 2019 The OpenSSL Project Authors. All Rights Reserved. 74 75Licensed under the Apache License 2.0 (the "License"). You may not use 76this file except in compliance with the License. You can obtain a copy 77in the file LICENSE in the source distribution or at 78L<https://www.openssl.org/source/license.html>. 79 80=cut 81