bio (3)
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NAME
bio - I/O abstractionSYNOPSIS
#include <openssl/bio.h>
TBA
DESCRIPTION
ABIO
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
).