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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_GET_DATA(3)       DragonFly Library Functions Manual       BIO_GET_DATA(3)


NAME

     BIO_set_data, BIO_get_data, BIO_set_init, BIO_set_shutdown,
     BIO_get_shutdown -- manage BIO state information


SYNOPSIS

     #include <openssl/bio.h>

     void
     BIO_set_data(BIO *a, void *ptr);

     void *
     BIO_get_data(BIO *a);

     void
     BIO_set_init(BIO *a, int init);

     void
     BIO_set_shutdown(BIO *a, int shutdown);

     int
     BIO_get_shutdown(BIO *a);


DESCRIPTION

     These functions are mainly useful when implementing a custom BIO.

     The BIO_set_data() function associates the custom data pointed to by ptr
     with the BIO a.  This data can subsequently be retrieved via a call to
     BIO_get_data().  This can be used by custom BIOs for storing implementa-
     tion specific information.

     The BIO_set_init() function sets the init flag in a to the specified
     value.  A non-zero value indicates that initialisation is complete,
     whilst zero indicates that it is not.  Often initialisation will complete
     during initial construction of the BIO.  For some BIOs however, initiali-
     sation may not be complete until additional steps have been taken, for
     example through calling custom ctrls.

     The BIO_set_shutdown() and BIO_get_shutdown() functions are low-level
     interfaces to forcefully set and get the shutdown flag of a, circumvent-
     ing type-dependent sanity checks, exclusively intended for implementing a
     new BIO type.  The shutdown argument must be either BIO_CLOSE or
     BIO_NOCLOSE.  When merely using a BIO object, call BIO_set_close(3) and
     BIO_get_close(3) instead.


RETURN VALUES

     BIO_get_data() returns a pointer to the implementation specific custom
     data associated with a, or NULL if none is set.

     BIO_get_shutdown() returns the value previously set with
     BIO_set_shutdown() or with BIO_set_close(3).


SEE ALSO

     BIO_meth_new(3), BIO_new(3), BIO_set_close(3)


HISTORY

     These functions first appeared in OpenSSL 1.1.0 and have been available
     since OpenBSD 6.3.

DragonFly 5.5			March 23, 2018			 DragonFly 5.5

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