+++ /dev/null
-=pod
-
-=head1 NAME
-
-BIO_s_bio, BIO_make_bio_pair, BIO_destroy_bio_pair, BIO_shutdown_wr,
-BIO_set_write_buf_size, BIO_get_write_buf_size, BIO_new_bio_pair,
-BIO_get_write_guarantee, BIO_ctrl_get_write_guarantee, BIO_get_read_request,
-BIO_ctrl_get_read_request, BIO_ctrl_reset_read_request - BIO pair BIO
-
-=head1 SYNOPSIS
-
- #include <openssl/bio.h>
-
- const BIO_METHOD *BIO_s_bio(void);
-
- int BIO_make_bio_pair(BIO *b1, BIO *b2);
- int BIO_destroy_bio_pair(BIO *b);
- int BIO_shutdown_wr(BIO *b);
-
-
- int BIO_set_write_buf_size(BIO *b, long size);
- size_t BIO_get_write_buf_size(BIO *b, long size);
-
- int BIO_new_bio_pair(BIO **bio1, size_t writebuf1, BIO **bio2, size_t writebuf2);
-
- int BIO_get_write_guarantee(BIO *b);
- size_t BIO_ctrl_get_write_guarantee(BIO *b);
- int BIO_get_read_request(BIO *b);
- size_t BIO_ctrl_get_read_request(BIO *b);
- int BIO_ctrl_reset_read_request(BIO *b);
-
-=head1 DESCRIPTION
-
-BIO_s_bio() returns the method for a BIO pair. A BIO pair is a pair of source/sink
-BIOs where data written to either half of the pair is buffered and can be read from
-the other half. Both halves must usually by handled by the same application thread
-since no locking is done on the internal data structures.
-
-Since BIO chains typically end in a source/sink BIO it is possible to make this
-one half of a BIO pair and have all the data processed by the chain under application
-control.
-
-One typical use of BIO pairs is to place TLS/SSL I/O under application control, this
-can be used when the application wishes to use a non standard transport for
-TLS/SSL or the normal socket routines are inappropriate.
-
-Calls to BIO_read() will read data from the buffer or request a retry if no
-data is available.
-
-Calls to BIO_write() will place data in the buffer or request a retry if the
-buffer is full.
-
-The standard calls BIO_ctrl_pending() and BIO_ctrl_wpending() can be used to
-determine the amount of pending data in the read or write buffer.
-
-BIO_reset() clears any data in the write buffer.
-
-BIO_make_bio_pair() joins two separate BIOs into a connected pair.
-
-BIO_destroy_pair() destroys the association between two connected BIOs. Freeing
-up any half of the pair will automatically destroy the association.
-
-BIO_shutdown_wr() is used to close down a BIO B<b>. After this call no further
-writes on BIO B<b> are allowed (they will return an error). Reads on the other
-half of the pair will return any pending data or EOF when all pending data has
-been read.
-
-BIO_set_write_buf_size() sets the write buffer size of BIO B<b> to B<size>.
-If the size is not initialized a default value is used. This is currently
-17K, sufficient for a maximum size TLS record.
-
-BIO_get_write_buf_size() returns the size of the write buffer.
-
-BIO_new_bio_pair() combines the calls to BIO_new(), BIO_make_bio_pair() and
-BIO_set_write_buf_size() to create a connected pair of BIOs B<bio1>, B<bio2>
-with write buffer sizes B<writebuf1> and B<writebuf2>. If either size is
-zero then the default size is used. BIO_new_bio_pair() does not check whether
-B<bio1> or B<bio2> do point to some other BIO, the values are overwritten,
-BIO_free() is not called.
-
-BIO_get_write_guarantee() and BIO_ctrl_get_write_guarantee() return the maximum
-length of data that can be currently written to the BIO. Writes larger than this
-value will return a value from BIO_write() less than the amount requested or if the
-buffer is full request a retry. BIO_ctrl_get_write_guarantee() is a function
-whereas BIO_get_write_guarantee() is a macro.
-
-BIO_get_read_request() and BIO_ctrl_get_read_request() return the
-amount of data requested, or the buffer size if it is less, if the
-last read attempt at the other half of the BIO pair failed due to an
-empty buffer. This can be used to determine how much data should be
-written to the BIO so the next read will succeed: this is most useful
-in TLS/SSL applications where the amount of data read is usually
-meaningful rather than just a buffer size. After a successful read
-this call will return zero. It also will return zero once new data
-has been written satisfying the read request or part of it.
-Note that BIO_get_read_request() never returns an amount larger
-than that returned by BIO_get_write_guarantee().
-
-BIO_ctrl_reset_read_request() can also be used to reset the value returned by
-BIO_get_read_request() to zero.
-
-=head1 NOTES
-
-Both halves of a BIO pair should be freed. That is even if one half is implicit
-freed due to a BIO_free_all() or SSL_free() call the other half needs to be freed.
-
-When used in bidirectional applications (such as TLS/SSL) care should be taken to
-flush any data in the write buffer. This can be done by calling BIO_pending()
-on the other half of the pair and, if any data is pending, reading it and sending
-it to the underlying transport. This must be done before any normal processing
-(such as calling select() ) due to a request and BIO_should_read() being true.
-
-To see why this is important consider a case where a request is sent using
-BIO_write() and a response read with BIO_read(), this can occur during an
-TLS/SSL handshake for example. BIO_write() will succeed and place data in the write
-buffer. BIO_read() will initially fail and BIO_should_read() will be true. If
-the application then waits for data to be available on the underlying transport
-before flushing the write buffer it will never succeed because the request was
-never sent!
-
-BIO_eof() is true if no data is in the peer BIO and the peer BIO has been
-shutdown.
-
-BIO_make_bio_pair(), BIO_destroy_bio_pair(), BIO_shutdown_wr(),
-BIO_set_write_buf_size(), BIO_get_write_buf_size(),
-BIO_get_write_guarantee(), and BIO_get_read_request() are implemented
-as macros.
-
-=head1 RETURN VALUES
-
-BIO_new_bio_pair() returns 1 on success, with the new BIOs available in
-B<bio1> and B<bio2>, or 0 on failure, with NULL pointers stored into the
-locations for B<bio1> and B<bio2>. Check the error stack for more information.
-
-[XXXXX: More return values need to be added here]
-
-=head1 EXAMPLE
-
-The BIO pair can be used to have full control over the network access of an
-application. The application can call select() on the socket as required
-without having to go through the SSL-interface.
-
- BIO *internal_bio, *network_bio;
- ...
- BIO_new_bio_pair(&internal_bio, 0, &network_bio, 0);
- SSL_set_bio(ssl, internal_bio, internal_bio);
- SSL_operations(); //e.g SSL_read and SSL_write
- ...
-
- application | TLS-engine
- | |
- +----------> SSL_operations()
- | /\ ||
- | || \/
- | BIO-pair (internal_bio)
- | BIO-pair (network_bio)
- | || /\
- | \/ ||
- +-----------< BIO_operations()
- | |
- | |
- socket
-
- ...
- SSL_free(ssl); /* implicitly frees internal_bio */
- BIO_free(network_bio);
- ...
-
-As the BIO pair will only buffer the data and never directly access the
-connection, it behaves non-blocking and will return as soon as the write
-buffer is full or the read buffer is drained. Then the application has to
-flush the write buffer and/or fill the read buffer.
-
-Use the BIO_ctrl_pending(), to find out whether data is buffered in the BIO
-and must be transferred to the network. Use BIO_ctrl_get_read_request() to
-find out, how many bytes must be written into the buffer before the
-SSL_operation() can successfully be continued.
-
-=head1 WARNING
-
-As the data is buffered, SSL_operation() may return with an ERROR_SSL_WANT_READ
-condition, but there is still data in the write buffer. An application must
-not rely on the error value of SSL_operation() but must assure that the
-write buffer is always flushed first. Otherwise a deadlock may occur as
-the peer might be waiting for the data before being able to continue.
-
-=head1 SEE ALSO
-
-L<SSL_set_bio(3)>, L<ssl(3)>, L<bio(3)>,
-L<BIO_should_retry(3)>, L<BIO_read(3)>
-
-=head1 COPYRIGHT
-
-Copyright 2000-2016 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
-L<https://www.openssl.org/source/license.html>.
-
-=cut
projects / openssl.git / blobdiff