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=head1 NAME

X509_NAME_get_index_by_NID, X509_NAME_get_index_by_OBJ, X509_NAME_get_entry,

X509_NAME_entry_count, X509_NAME_get_text_by_NID, X509_NAME_get_text_by_OBJ -

X509_NAME lookup and enumeration functions

=head1 SYNOPSIS

 #include <openssl/x509.h>

 int X509_NAME_get_index_by_NID(X509_NAME *name, int nid, int lastpos);

 int X509_NAME_get_index_by_OBJ(X509_NAME *name, const ASN1_OBJECT *obj, int lastpos);

 int X509_NAME_entry_count(const X509_NAME *name);

 X509_NAME_ENTRY *X509_NAME_get_entry(const X509_NAME *name, int loc);

 int X509_NAME_get_text_by_NID(X509_NAME *name, int nid, char *buf, int len);

 int X509_NAME_get_text_by_OBJ(X509_NAME *name, const ASN1_OBJECT *obj, char *buf, int len);

=head1 DESCRIPTION

These functions allow an B<X509_NAME> structure to be examined. The

B<X509_NAME> structure is the same as the B<Name> type defined in

RFC2459 (and elsewhere) and used for example in certificate subject

and issuer names.

X509_NAME_get_index_by_NID() and X509_NAME_get_index_by_OBJ() retrieve

the next index matching B<nid> or B<obj> after B<lastpos>. B<lastpos>

should initially be set to -1. If there are no more entries -1 is returned.

If B<nid> is invalid (doesn't correspond to a valid OID) then -2 is returned.

X509_NAME_entry_count() returns the total number of entries in B<name>.

X509_NAME_get_entry() retrieves the B<X509_NAME_ENTRY> from B<name>

corresponding to index B<loc>. Acceptable values for B<loc> run from

0 to (X509_NAME_entry_count(name) - 1). The value returned is an

internal pointer which must not be freed.

X509_NAME_get_text_by_NID(), X509_NAME_get_text_by_OBJ() retrieve

the "text" from the first entry in B<name> which matches B<nid> or

B<obj>, if no such entry exists -1 is returned. At most B<len> bytes

will be written and the text written to B<buf> will be null

terminated. The length of the output string written is returned

excluding the terminating null. If B<buf> is <NULL> then the amount

of space needed in B<buf> (excluding the final null) is returned.

=head1 NOTES

X509_NAME_get_text_by_NID() and X509_NAME_get_text_by_OBJ() should be

considered deprecated because they

have various limitations which make them

of minimal use in practice. They can only find the first matching

entry and will copy the contents of the field verbatim: this can

be highly confusing if the target is a multicharacter string type

like a BMPString or a UTF8String.

For a more general solution X509_NAME_get_index_by_NID() or

X509_NAME_get_index_by_OBJ() should be used followed by

X509_NAME_get_entry() on any matching indices and then the

various B<X509_NAME_ENTRY> utility functions on the result.

The list of all relevant B<NID_*> and B<OBJ_* codes> can be found in

the source code header files E<lt>openssl/obj_mac.hE<gt> and/or

E<lt>openssl/objects.hE<gt>.

Applications which could pass invalid NIDs to X509_NAME_get_index_by_NID()

should check for the return value of -2. Alternatively the NID validity

can be determined first by checking OBJ_nid2obj(nid) is not NULL.

=head1 RETURN VALUES

X509_NAME_get_index_by_NID() and X509_NAME_get_index_by_OBJ()

return the index of the next matching entry or -1 if not found.

X509_NAME_get_index_by_NID() can also return -2 if the supplied

NID is invalid.

X509_NAME_entry_count() returns the total number of entries.

X509_NAME_get_entry() returns an B<X509_NAME> pointer to the

requested entry or B<NULL> if the index is invalid.

=head1 EXAMPLES

Process all entries:

 int i;

 X509_NAME_ENTRY *e;

 for (i = 0; i < X509_NAME_entry_count(nm); i++) {

     e = X509_NAME_get_entry(nm, i);

     /* Do something with e */

 }

Process all commonName entries:

 int lastpos = -1;

 X509_NAME_ENTRY *e;

 for (;;) {

     lastpos = X509_NAME_get_index_by_NID(nm, NID_commonName, lastpos);

     if (lastpos == -1)

         break;

     e = X509_NAME_get_entry(nm, lastpos);

     /* Do something with e */

 }

=head1 SEE ALSO

L<ERR_get_error(3)>, L<d2i_X509_NAME(3)>

=head1 COPYRIGHT

Copyright 2002-2019 The OpenSSL Project Authors. All Rights Reserved.

Licensed under the OpenSSL license (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

L<https://www.openssl.org/source/license.html>.

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