BIO_find_type.3ssl man page

BIO_find_type, BIO_next, BIO_method_type — BIO chain traversal


#include <openssl/bio.h>
BIO *BIO_find_type(BIO *b, int bio_type);
BIO *BIO_next(BIO *b);
int BIO_method_type(const BIO *b);


The BIO_find_type() searches for a BIO of a given type in a chain, starting at BIO b. If type is a specific type (such as BIO_TYPE_MEM) then a search is made for a BIO of that type. If type is a general type (such as BIO_TYPE_SOURCE_SINK) then the next matching BIO of the given general type is searched for. BIO_find_type() returns the next matching BIO or NULL if none is found.

The following general types are defined: BIO_TYPE_DESCRIPTOR, BIO_TYPE_FILTER, and BIO_TYPE_SOURCE_SINK.

For a list of the specific types, see the openssl/bio.h header file.

BIO_next() returns the next BIO in a chain. It can be used to traverse all BIOs in a chain or used in conjunction with BIO_find_type() to find all BIOs of a certain type.

BIO_method_type() returns the type of a BIO.

Return Values

BIO_find_type() returns a matching BIO or NULL for no match.

BIO_next() returns the next BIO in a chain.

BIO_method_type() returns the type of the BIO b.


Traverse a chain looking for digest BIOs:

BIO *btmp;
btmp = in_bio; /* in_bio is chain to search through */

do {
       btmp = BIO_find_type(btmp, BIO_TYPE_MD);
       if (btmp == NULL) break; /* Not found */
       /* btmp is a digest BIO, do something with it ...*/

       btmp = BIO_next(btmp);
} while (btmp);