DragonFly On-Line Manual Pages
BIO(3) DragonFly Library Functions Manual BIO(3)
NAME
BIO -- I/O abstraction
SYNOPSIS
#include <openssl/bio.h>
DESCRIPTION
A BIO is an I/O abstraction, it hides many of the underlying I/O details
from an application. If an application uses a BIO for its I/O, it can
transparently handle SSL connections, unencrypted network connections and
file I/O.
There are two types of BIO, a source/sink BIO and a filter BIO.
As its name implies, a source/sink BIO is a source and/or sink of data,
examples include a socket BIO and a file BIO.
A filter BIO takes data from one BIO and passes it through to another, or
to the application. The data may be left unmodified (for example a mes-
sage digest BIO) or translated (for example an encryption BIO). The
effect of a filter BIO may change according to the I/O operation it is
performing: for example an encryption BIO will encrypt data if it is
being written to and decrypt data if it is being read from.
BIOs can be joined together to form a chain (a single BIO is a chain with
one component). A chain normally consist of one source/sink BIO and one
or more filter BIOs. Data read from or written to the first BIO then
traverses the chain to the end (normally a source/sink BIO).
SEE ALSO
BIO_ctrl(3), BIO_f_base64(3), BIO_f_buffer(3), BIO_f_cipher(3),
BIO_f_md(3), BIO_f_null(3), BIO_f_ssl(3), BIO_find_type(3), BIO_new(3),
BIO_new_bio_pair(3), BIO_push(3), BIO_read(3), BIO_s_accept(3),
BIO_s_bio(3), BIO_s_connect(3), BIO_s_fd(3), BIO_s_file(3), BIO_s_mem(3),
BIO_s_null(3), BIO_s_socket(3), BIO_set_callback(3), BIO_should_retry(3)
DragonFly 4.7 July 17, 2014 DragonFly 4.7
BIO_METH_NEW(3) OpenSSL BIO_METH_NEW(3)
NAME
BIO_get_new_index, BIO_meth_new, BIO_meth_free, BIO_meth_get_read_ex,
BIO_meth_set_read_ex, BIO_meth_get_write_ex, BIO_meth_set_write_ex,
BIO_meth_get_write, BIO_meth_set_write, BIO_meth_get_read,
BIO_meth_set_read, BIO_meth_get_puts, BIO_meth_set_puts,
BIO_meth_get_gets, BIO_meth_set_gets, BIO_meth_get_ctrl,
BIO_meth_set_ctrl, BIO_meth_get_create, BIO_meth_set_create,
BIO_meth_get_destroy, BIO_meth_set_destroy, BIO_meth_get_callback_ctrl,
BIO_meth_set_callback_ctrl - Routines to build up BIO methods
SYNOPSIS
#include <openssl/bio.h>
int BIO_get_new_index(void);
BIO_METHOD *BIO_meth_new(int type, const char *name);
void BIO_meth_free(BIO_METHOD *biom);
int (*BIO_meth_get_write_ex(const BIO_METHOD *biom))(BIO *, const char *, size_t,
size_t *);
int (*BIO_meth_get_write(const BIO_METHOD *biom))(BIO *, const char *, int);
int BIO_meth_set_write_ex(BIO_METHOD *biom,
int (*bwrite)(BIO *, const char *, size_t, size_t *));
int BIO_meth_set_write(BIO_METHOD *biom,
int (*write)(BIO *, const char *, int));
int (*BIO_meth_get_read_ex(const BIO_METHOD *biom))(BIO *, char *, size_t, size_t *);
int (*BIO_meth_get_read(const BIO_METHOD *biom))(BIO *, char *, int);
int BIO_meth_set_read_ex(BIO_METHOD *biom,
int (*bread)(BIO *, char *, size_t, size_t *));
int BIO_meth_set_read(BIO_METHOD *biom, int (*read)(BIO *, char *, int));
int (*BIO_meth_get_puts(const BIO_METHOD *biom))(BIO *, const char *);
int BIO_meth_set_puts(BIO_METHOD *biom, int (*puts)(BIO *, const char *));
int (*BIO_meth_get_gets(const BIO_METHOD *biom))(BIO *, char *, int);
int BIO_meth_set_gets(BIO_METHOD *biom,
int (*gets)(BIO *, char *, int));
long (*BIO_meth_get_ctrl(const BIO_METHOD *biom))(BIO *, int, long, void *);
int BIO_meth_set_ctrl(BIO_METHOD *biom,
long (*ctrl)(BIO *, int, long, void *));
int (*BIO_meth_get_create(const BIO_METHOD *bion))(BIO *);
int BIO_meth_set_create(BIO_METHOD *biom, int (*create)(BIO *));
int (*BIO_meth_get_destroy(const BIO_METHOD *biom))(BIO *);
int BIO_meth_set_destroy(BIO_METHOD *biom, int (*destroy)(BIO *));
long (*BIO_meth_get_callback_ctrl(const BIO_METHOD *biom))(BIO *, int, BIO_info_cb *);
int BIO_meth_set_callback_ctrl(BIO_METHOD *biom,
long (*callback_ctrl)(BIO *, int, BIO_info_cb *));
DESCRIPTION
The BIO_METHOD type is a structure used for the implementation of new
BIO types. It provides a set of functions used by OpenSSL for the
implementation of the various BIO capabilities. See the bio page for
more information.
BIO_meth_new() creates a new BIO_METHOD structure. It should be given a
unique integer type and a string that represents its name. Use
BIO_get_new_index() to get the value for type.
The set of standard OpenSSL provided BIO types is provided in bio.h.
Some examples include BIO_TYPE_BUFFER and BIO_TYPE_CIPHER. Filter BIOs
should have a type which have the "filter" bit set (BIO_TYPE_FILTER).
Source/sink BIOs should have the "source/sink" bit set
(BIO_TYPE_SOURCE_SINK). File descriptor based BIOs (e.g. socket, fd,
connect, accept etc) should additionally have the "descriptor" bit set
(BIO_TYPE_DESCRIPTOR). See the BIO_find_type page for more information.
BIO_meth_free() destroys a BIO_METHOD structure and frees up any memory
associated with it.
BIO_meth_get_write_ex() and BIO_meth_set_write_ex() get and set the
function used for writing arbitrary length data to the BIO
respectively. This function will be called in response to the
application calling BIO_write_ex() or BIO_write(). The parameters for
the function have the same meaning as for BIO_write_ex(). Older code
may call BIO_meth_get_write() and BIO_meth_set_write() instead.
Applications should not call both BIO_meth_set_write_ex() and
BIO_meth_set_write() or call BIO_meth_get_write() when the function was
set with BIO_meth_set_write_ex().
BIO_meth_get_read_ex() and BIO_meth_set_read_ex() get and set the
function used for reading arbitrary length data from the BIO
respectively. This function will be called in response to the
application calling BIO_read_ex() or BIO_read(). The parameters for
the function have the same meaning as for BIO_read_ex(). Older code
may call BIO_meth_get_read() and BIO_meth_set_read() instead.
Applications should not call both BIO_meth_set_read_ex() and
BIO_meth_set_read() or call BIO_meth_get_read() when the function was
set with BIO_meth_set_read_ex().
BIO_meth_get_puts() and BIO_meth_set_puts() get and set the function
used for writing a NULL terminated string to the BIO respectively. This
function will be called in response to the application calling
BIO_puts(). The parameters for the function have the same meaning as
for BIO_puts().
BIO_meth_get_gets() and BIO_meth_set_gets() get and set the function
typically used for reading a line of data from the BIO respectively
(see the BIO_gets(3) page for more information). This function will be
called in response to the application calling BIO_gets(). The
parameters for the function have the same meaning as for BIO_gets().
BIO_meth_get_ctrl() and BIO_meth_set_ctrl() get and set the function
used for processing ctrl messages in the BIO respectively. See the
BIO_ctrl page for more information. This function will be called in
response to the application calling BIO_ctrl(). The parameters for the
function have the same meaning as for BIO_ctrl().
BIO_meth_get_create() and BIO_meth_set_create() get and set the
function used for creating a new instance of the BIO respectively. This
function will be called in response to the application calling
BIO_new() and passing in a pointer to the current BIO_METHOD. The
BIO_new() function will allocate the memory for the new BIO, and a
pointer to this newly allocated structure will be passed as a parameter
to the function.
BIO_meth_get_destroy() and BIO_meth_set_destroy() get and set the
function used for destroying an instance of a BIO respectively. This
function will be called in response to the application calling
BIO_free(). A pointer to the BIO to be destroyed is passed as a
parameter. The destroy function should be used for BIO specific clean
up. The memory for the BIO itself should not be freed by this function.
BIO_meth_get_callback_ctrl() and BIO_meth_set_callback_ctrl() get and
set the function used for processing callback ctrl messages in the BIO
respectively. See the BIO_callback_ctrl(3) page for more information.
This function will be called in response to the application calling
BIO_callback_ctrl(). The parameters for the function have the same
meaning as for BIO_callback_ctrl().
RETURN VALUES
BIO_get_new_index() returns the new BIO type value or -1 if an error
occurred.
BIO_meth_new(int type, const char *name) returns a valid BIO_METHOD or
NULL if an error occurred.
The BIO_meth_set functions return 1 on success or 0 on error.
The BIO_meth_get functions return the corresponding function pointers.
SEE ALSO
bio, BIO_find_type, BIO_ctrl, BIO_read_ex, BIO_new
HISTORY
The functions described here were added in OpenSSL 1.1.0.
COPYRIGHT
Copyright 2016-2018 The OpenSSL Project Authors. All Rights Reserved.
Licensed under the OpenSSL license (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>.
1.1.1v 2023-08-01 BIO_METH_NEW(3)