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

SYNOPSIS

        #include <openssl/x509.h>

        int X509_NAME_get_index_by_NID(const X509_NAME *name, int nid, int lastpos);
        int X509_NAME_get_index_by_OBJ(const 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(const X509_NAME *name, int nid,
                                      char *buf, int len);
        int X509_NAME_get_text_by_OBJ(const X509_NAME *name, const ASN1_OBJECT *obj,
                                      char *buf, int len);

DESCRIPTION

       These functions allow an X509_NAME structure to be examined. The X509_NAME structure is
       the same as the 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 nid or obj after lastpos. lastpos should initially be set to -1. If there are no
       more entries -1 is returned.  If 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 name.

       X509_NAME_get_entry() retrieves the X509_NAME_ENTRY from name corresponding to index loc.
       Acceptable values for 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 name which matches nid or obj, if no such entry exists -1 is returned. At
       most len bytes will be written and the text written to buf will be null terminated. The
       length of the output string written is returned excluding the terminating null. If buf is
       <NULL> then the amount of space needed in buf (excluding the final null) is returned.

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 X509_NAME_ENTRY utility functions on the result.

       The list of all relevant NID_* and OBJ_* codes can be found in the source code header
       files <openssl/obj_mac.h> and/or <openssl/objects.h>.

       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.

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, and 0 for failure.

       X509_NAME_get_entry() returns an X509_NAME pointer to the requested entry or NULL if the
       index is invalid.

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 */
        }

SEE ALSO

       ERR_get_error(3), d2i_X509_NAME(3)

COPYRIGHT

       Copyright 2002-2021 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>.