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Diffstat (limited to 'crypto/openssl/doc/crypto/BIO_s_bio.pod')
| -rw-r--r-- | crypto/openssl/doc/crypto/BIO_s_bio.pod | 182 |
1 files changed, 0 insertions, 182 deletions
diff --git a/crypto/openssl/doc/crypto/BIO_s_bio.pod b/crypto/openssl/doc/crypto/BIO_s_bio.pod deleted file mode 100644 index 8d0a55a025c7..000000000000 --- a/crypto/openssl/doc/crypto/BIO_s_bio.pod +++ /dev/null @@ -1,182 +0,0 @@ -=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> - - BIO_METHOD *BIO_s_bio(void); - - #define BIO_make_bio_pair(b1,b2) (int)BIO_ctrl(b1,BIO_C_MAKE_BIO_PAIR,0,b2) - #define BIO_destroy_bio_pair(b) (int)BIO_ctrl(b,BIO_C_DESTROY_BIO_PAIR,0,NULL) - - #define BIO_shutdown_wr(b) (int)BIO_ctrl(b, BIO_C_SHUTDOWN_WR, 0, NULL) - - #define BIO_set_write_buf_size(b,size) (int)BIO_ctrl(b,BIO_C_SET_WRITE_BUF_SIZE,size,NULL) - #define BIO_get_write_buf_size(b,size) (size_t)BIO_ctrl(b,BIO_C_GET_WRITE_BUF_SIZE,size,NULL) - - int BIO_new_bio_pair(BIO **bio1, size_t writebuf1, BIO **bio2, size_t writebuf2); - - #define BIO_get_write_guarantee(b) (int)BIO_ctrl(b,BIO_C_GET_WRITE_GUARANTEE,0,NULL) - size_t BIO_ctrl_get_write_guarantee(BIO *b); - - #define BIO_get_read_request(b) (int)BIO_ctrl(b,BIO_C_GET_READ_REQUEST,0,NULL) - 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! - -=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(); - ... - - application | TLS-engine - | | - +----------> SSL_operations() - | /\ || - | || \/ - | BIO-pair (internal_bio) - +----------< BIO-pair (network_bio) - | | - 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 transfered 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 a 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)|SSL_set_bio(3)>, L<ssl(3)|ssl(3)>, L<bio(3)|bio(3)>, -L<BIO_should_retry(3)|BIO_should_retry(3)>, L<BIO_read(3)|BIO_read(3)> - -=cut |