bio - I/O abstraction
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 type 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 the application. The data may be left unmodified (for example a message 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).
BIO_ctrl(), BIO_f_base64(), BIO_f_buffer(), BIO_f_cipher(), BIO_f_md(), BIO_f_null(), BIO_f_ssl(), BIO_find_type(), BIO_new(), BIO_new_bio_pair(), BIO_push(), BIO_read(), BIO_s_accept(), BIO_s_bio(), BIO_s_connect(), BIO_s_fd(), BIO_s_file(), BIO_s_mem(), BIO_s_null(), BIO_s_socket(), BIO_set_callback(), BIO_should_retry()