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BIO_FIND_TYPE(3) Library Functions Manual BIO_FIND_TYPE(3)

BIO_find_type, BIO_next, BIO_method_type, BIO_method_nameBIO chain traversal

#include <openssl/bio.h>

BIO *
BIO_find_type(BIO *bio, int type);

BIO *
BIO_next(BIO *bio);

int
BIO_method_type(const BIO *bio);

const char *
BIO_method_name(const BIO *bio);

#define BIO_TYPE_NONE 0
#define BIO_TYPE_MEM (1|0x0400)
#define BIO_TYPE_FILE (2|0x0400)
#define BIO_TYPE_FD (4|0x0400|0x0100)
#define BIO_TYPE_SOCKET (5|0x0400|0x0100)
#define BIO_TYPE_NULL (6|0x0400)
#define BIO_TYPE_SSL (7|0x0200)
#define BIO_TYPE_MD (8|0x0200)
#define BIO_TYPE_BUFFER (9|0x0200)
#define BIO_TYPE_CIPHER (10|0x0200)
#define BIO_TYPE_BASE64 (11|0x0200)
#define BIO_TYPE_CONNECT (12|0x0400|0x0100)
#define BIO_TYPE_ACCEPT (13|0x0400|0x0100)
#define BIO_TYPE_PROXY_CLIENT (14|0x0200)
#define BIO_TYPE_PROXY_SERVER (15|0x0200)
#define BIO_TYPE_NBIO_TEST (16|0x0200)
#define BIO_TYPE_NULL_FILTER (17|0x0200)
#define BIO_TYPE_BER (18|0x0200)
#define BIO_TYPE_BIO (19|0x0400)
#define BIO_TYPE_LINEBUFFER (20|0x0200)
#define BIO_TYPE_DGRAM (21|0x0400|0x0100)
#define BIO_TYPE_ASN1 (22|0x0200)
#define BIO_TYPE_COMP (23|0x0200)
#define BIO_TYPE_DESCRIPTOR 0x0100
#define BIO_TYPE_FILTER 0x0200
#define BIO_TYPE_SOURCE_SINK 0x0400
#define BIO_TYPE_START 128

() searches for a BIO matching the given type in the chain starting at bio. If the least significant byte of the type argument is non-zero, only exact matches of the type are accepted. Otherwise, a match only requires that any of the bits set in the type argument is also set in the candidate BIO.

Not all the BIO_TYPE_* types shown above have corresponding BIO implementations.

Types with a least significant byte in the range from 0 to BIO_TYPE_START, inclusive, are reserved for BIO types built into the library. Types with a least significant byte greater than BIO_TYPE_START are available for user-defined BIO types; see BIO_get_new_index(3) for details.

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

() returns the type of the given bio.

() returns an ASCII string representing the type of the bio.

BIO_find_type() returns the next matching BIO or NULL if bio is a NULL pointer or if no matching BIO is found.

BIO_next() returns the next BIO or NULL if bio is a NULL pointer or points to the last BIO in a chain.

BIO_method_type() returns one of the BIO_TYPE_* constants.

BIO_method_name() returns an internal pointer to a string.

Traverse a chain looking for digest BIOs:

BIO *btmp;

btmp = in_bio;	/* in_bio is the chain to search through */
while (btmp != NULL) {
	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);
}

BIO_meth_new(3), BIO_new(3)

BIO_method_type() and BIO_method_name() first appeared in SSLeay 0.6.0. BIO_find_type() first appeared in SSLeay 0.6.6. These functions have been available since OpenBSD 2.4.

BIO_next() first appeared in OpenSSL 0.9.6 and has been available since OpenBSD 2.9.

November 25, 2021 OpenBSD-current