1*2175Sjp161948=pod 2*2175Sjp161948 3*2175Sjp161948=head1 NAME 4*2175Sjp161948 5*2175Sjp161948bio - I/O abstraction 6*2175Sjp161948 7*2175Sjp161948=head1 SYNOPSIS 8*2175Sjp161948 9*2175Sjp161948 #include <openssl/bio.h> 10*2175Sjp161948 11*2175Sjp161948TBA 12*2175Sjp161948 13*2175Sjp161948 14*2175Sjp161948=head1 DESCRIPTION 15*2175Sjp161948 16*2175Sjp161948A BIO is an I/O abstraction, it hides many of the underlying I/O 17*2175Sjp161948details from an application. If an application uses a BIO for its 18*2175Sjp161948I/O it can transparently handle SSL connections, unencrypted network 19*2175Sjp161948connections and file I/O. 20*2175Sjp161948 21*2175Sjp161948There are two type of BIO, a source/sink BIO and a filter BIO. 22*2175Sjp161948 23*2175Sjp161948As its name implies a source/sink BIO is a source and/or sink of data, 24*2175Sjp161948examples include a socket BIO and a file BIO. 25*2175Sjp161948 26*2175Sjp161948A filter BIO takes data from one BIO and passes it through to 27*2175Sjp161948another, or the application. The data may be left unmodified (for 28*2175Sjp161948example a message digest BIO) or translated (for example an 29*2175Sjp161948encryption BIO). The effect of a filter BIO may change according 30*2175Sjp161948to the I/O operation it is performing: for example an encryption 31*2175Sjp161948BIO will encrypt data if it is being written to and decrypt data 32*2175Sjp161948if it is being read from. 33*2175Sjp161948 34*2175Sjp161948BIOs can be joined together to form a chain (a single BIO is a chain 35*2175Sjp161948with one component). A chain normally consist of one source/sink 36*2175Sjp161948BIO and one or more filter BIOs. Data read from or written to the 37*2175Sjp161948first BIO then traverses the chain to the end (normally a source/sink 38*2175Sjp161948BIO). 39*2175Sjp161948 40*2175Sjp161948=head1 SEE ALSO 41*2175Sjp161948 42*2175Sjp161948L<BIO_ctrl(3)|BIO_ctrl(3)>, 43*2175Sjp161948L<BIO_f_base64(3)|BIO_f_base64(3)>, L<BIO_f_buffer(3)|BIO_f_buffer(3)>, 44*2175Sjp161948L<BIO_f_cipher(3)|BIO_f_cipher(3)>, L<BIO_f_md(3)|BIO_f_md(3)>, 45*2175Sjp161948L<BIO_f_null(3)|BIO_f_null(3)>, L<BIO_f_ssl(3)|BIO_f_ssl(3)>, 46*2175Sjp161948L<BIO_find_type(3)|BIO_find_type(3)>, L<BIO_new(3)|BIO_new(3)>, 47*2175Sjp161948L<BIO_new_bio_pair(3)|BIO_new_bio_pair(3)>, 48*2175Sjp161948L<BIO_push(3)|BIO_push(3)>, L<BIO_read(3)|BIO_read(3)>, 49*2175Sjp161948L<BIO_s_accept(3)|BIO_s_accept(3)>, L<BIO_s_bio(3)|BIO_s_bio(3)>, 50*2175Sjp161948L<BIO_s_connect(3)|BIO_s_connect(3)>, L<BIO_s_fd(3)|BIO_s_fd(3)>, 51*2175Sjp161948L<BIO_s_file(3)|BIO_s_file(3)>, L<BIO_s_mem(3)|BIO_s_mem(3)>, 52*2175Sjp161948L<BIO_s_null(3)|BIO_s_null(3)>, L<BIO_s_socket(3)|BIO_s_socket(3)>, 53*2175Sjp161948L<BIO_set_callback(3)|BIO_set_callback(3)>, 54*2175Sjp161948L<BIO_should_retry(3)|BIO_should_retry(3)> 55