BIO_FIND_TYPE(3) Library Functions Manual BIO_FIND_TYPE(3)
NAME
BIO_find_type, BIO_next, BIO_method_type, BIO_method_name — BIO chain traversal
SYNOPSIS
#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 |
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#define BIO_TYPE_START |
128 |
DESCRIPTION
BIO_find_type() 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.
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.
BIO_next() 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.
BIO_method_type() returns the type of the given bio.
BIO_method_name() returns an ASCII string representing the type of the bio.
The following are the built-in source/sink BIO types that operate on file descriptors. They all have both of the bits BIO_TYPE_SOURCE_SINK and BIO_TYPE_DESCRIPTOR but not the bit BIO_TYPE_FILTER set in their type constant.
type constant | |
name string | |
BIO_METHOD | |
BIO_TYPE_ACCEPT | |
socket accept | |
BIO_s_accept(3) | |
BIO_TYPE_CONNECT | |
socket connect | |
BIO_s_connect(3) | |
BIO_TYPE_DGRAM | |
datagram socket | |
BIO_s_datagram(3) | |
BIO_TYPE_FD | |
file descriptor | |
BIO_s_fd(3) | |
BIO_TYPE_SOCKET | |
socket | |
BIO_s_socket(3) |
The following are the built-in source/sink BIO types that do not directly operate on file descriptors. They all have the bit BIO_TYPE_SOURCE_SINK but not the bits BIO_TYPE_DESCRIPTOR and BIO_TYPE_FILTER set in their type constant.
type constant | |
name string | |
BIO_METHOD | |
BIO_TYPE_BIO | |
BIO pair | |
BIO_s_bio(3) | |
BIO_TYPE_FILE | |
FILE pointer | |
BIO_s_file(3) | |
BIO_TYPE_MEM | |
memory buffer | |
BIO_s_mem(3) | |
BIO_TYPE_NULL | |
NULL | |
BIO_s_null(3) |
The following are the built-in filter BIO types. They all have the bit BIO_TYPE_FILTER but not the bits BIO_TYPE_SOURCE_SINK and BIO_TYPE_DESCRIPTOR set in their type constant.
type constant | |
name string | |
BIO_METHOD | |
BIO_TYPE_BASE64 | |
base64 encoding | |
BIO_f_base64(3) | |
BIO_TYPE_BUFFER | |
buffer | |
BIO_f_buffer(3) | |
BIO_TYPE_CIPHER | |
cipher | |
BIO_f_cipher(3) | |
BIO_TYPE_MD | |
message digest | |
BIO_f_md(3) | |
BIO_TYPE_NULL_FILTER | |
NULL filter | |
BIO_f_null(3) | |
BIO_TYPE_SSL | |
ssl | |
BIO_f_ssl(3) |
The constants BIO_TYPE_BER, BIO_TYPE_PROXY_CLIENT, and BIO_TYPE_PROXY_SERVER do not correspond to any BIO types implemented by the library and are not intended to be used for application-defined types, either. The constants BIO_TYPE_COMP, BIO_TYPE_LINEBUFFER, and BIO_TYPE_NBIO_TEST corresponds to a deprecated BIO types that are intentionally undocumented.
If a variable in an application program is intended to store a BIO type but temporarily does not refer to any BIO or refers to a BIO of an unknown type, setting the variable to BIO_TYPE_NONE is recommended.
RETURN VALUES
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.
EXAMPLES
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); |
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if (btmp == NULL) |
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break; |
/* Not found */ |
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/* btmp is a digest BIO, do something with it ... */ |
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... |
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btmp = BIO_next(btmp); |
}
SEE ALSO
BIO_meth_new(3), BIO_new(3)
HISTORY
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. GNU July 26, 2023 BIO_FIND_TYPE(3)