BIO_get_write_guarantee man page on IRIX

Man page or keyword search:  
man Server   31559 pages
apropos Keyword Search (all sections)
Output format
IRIX logo
[printable version]

     /xlv3/openssl/0.9.7e-sgipl1/work/0.9.7e-sgipl1/openssl-
     0.9.7e/doc/crypto

     Page 1					    (printed 10/20/05)

     BIO_s_bio(3)	   12/Dec/2002 (0.9.7e)		  BIO_s_bio(3)

     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

     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);

     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.

     Page 1					    (printed 10/20/05)

     BIO_s_bio(3)	   12/Dec/2002 (0.9.7e)		  BIO_s_bio(3)

	  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. After this
	  call no further writes on BIO 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
	  to 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 bio1, bio2 with write buffer sizes
	  writebuf1 and writebuf2. If either size is zero then the
	  default size is used.	 BIO_new_bio_pair() does not check
	  whether bio1 or 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

     Page 2					    (printed 10/20/05)

     BIO_s_bio(3)	   12/Dec/2002 (0.9.7e)		  BIO_s_bio(3)

	  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.

     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!

     RETURN VALUES
	  BIO_new_bio_pair() returns 1 on success, with the new BIOs
	  available in bio1 and bio2, or 0 on failure, with NULL
	  pointers stored into the locations for bio1 and bio2. Check
	  the error stack for more information.

	  [XXXXX: More return values need to be added here]

     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.

     Page 3					    (printed 10/20/05)

     BIO_s_bio(3)	   12/Dec/2002 (0.9.7e)		  BIO_s_bio(3)

	   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.

     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.

     SEE ALSO
	  SSL_set_bio(3), ssl(3), bio(3), BIO_should_retry(3),
	  BIO_read(3)

     Page 4					    (printed 10/20/05)

     BIO_s_bio(3)	   12/Dec/2002 (0.9.7e)		  BIO_s_bio(3)

     Page 5					    (printed 10/20/05)

[top]

List of man pages available for IRIX

Copyright (c) for man pages and the logo by the respective OS vendor.

For those who want to learn more, the polarhome community provides shell access and support.

[legal] [privacy] [GNU] [policy] [cookies] [netiquette] [sponsors] [FAQ]
Tweet
Polarhome, production since 1999.
Member of Polarhome portal.
Based on Fawad Halim's script.
....................................................................
Vote for polarhome
Free Shell Accounts :: the biggest list on the net