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NAME

       BIO_find_type, BIO_next, BIO_method_type - BIO chain traversal

SYNOPSIS

        #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);

DESCRIPTION

       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.

EXAMPLES

       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);

COPYRIGHT

       Copyright 2000-2019 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>.