doc/man3/BIO_ctrl.pod - third_party/openssl - Git at Google

 =pod

 =head1 NAME

 BIO_ctrl, BIO_callback_ctrl, BIO_ptr_ctrl, BIO_int_ctrl, BIO_reset,
 BIO_seek, BIO_tell, BIO_flush, BIO_eof, BIO_set_close, BIO_get_close,
 BIO_pending, BIO_wpending, BIO_ctrl_pending, BIO_ctrl_wpending,
 BIO_get_info_callback, BIO_set_info_callback, BIO_info_cb, BIO_get_ktls_send,
 BIO_get_ktls_recv, BIO_set_conn_mode, BIO_get_conn_mode, BIO_set_tfo
 - BIO control operations

 =head1 SYNOPSIS

  #include <openssl/bio.h>

  typedef int BIO_info_cb(BIO *b, int state, int res);

  long BIO_ctrl(BIO *bp, int cmd, long larg, void *parg);
  long BIO_callback_ctrl(BIO *b, int cmd, BIO_info_cb *cb);
  void *BIO_ptr_ctrl(BIO *bp, int cmd, long larg);
  long BIO_int_ctrl(BIO *bp, int cmd, long larg, int iarg);

  int BIO_reset(BIO *b);
  int BIO_seek(BIO *b, int ofs);
  int BIO_tell(BIO *b);
  int BIO_flush(BIO *b);
  int BIO_eof(BIO *b);
  int BIO_set_close(BIO *b, long flag);
  int BIO_get_close(BIO *b);
  int BIO_pending(BIO *b);
  int BIO_wpending(BIO *b);
  size_t BIO_ctrl_pending(BIO *b);
  size_t BIO_ctrl_wpending(BIO *b);

  int BIO_get_info_callback(BIO *b, BIO_info_cb **cbp);
  int BIO_set_info_callback(BIO *b, BIO_info_cb *cb);

  int BIO_get_ktls_send(BIO *b);
  int BIO_get_ktls_recv(BIO *b);

  int BIO_set_conn_mode(BIO *b, int mode);
  int BIO_get_conn_mode(BIO *b);

  int BIO_set_tfo(BIO *b, int onoff);

 =head1 DESCRIPTION

 BIO_ctrl(), BIO_callback_ctrl(), BIO_ptr_ctrl() and BIO_int_ctrl()
 are BIO "control" operations taking arguments of various types.
 These functions are not normally called directly, various macros
 are used instead. The standard macros are described below, macros
 specific to a particular type of BIO are described in the specific
 BIOs manual page as well as any special features of the standard
 calls.

 BIO_reset() typically resets a BIO to some initial state, in the case
 of file related BIOs for example it rewinds the file pointer to the
 start of the file.

 BIO_seek() resets a file related BIO's (that is file descriptor and
 FILE BIOs) file position pointer to B<ofs> bytes from start of file.

 BIO_tell() returns the current file position of a file related BIO.

 BIO_flush() normally writes out any internally buffered data, in some
 cases it is used to signal EOF and that no more data will be written.

 BIO_eof() returns 1 if the BIO has read EOF, the precise meaning of
 "EOF" varies according to the BIO type.

 BIO_set_close() sets the BIO B<b> close flag to B<flag>. B<flag> can
 take the value BIO_CLOSE or BIO_NOCLOSE. Typically BIO_CLOSE is used
 in a source/sink BIO to indicate that the underlying I/O stream should
 be closed when the BIO is freed.

 BIO_get_close() returns the BIOs close flag.

 BIO_pending(), BIO_ctrl_pending(), BIO_wpending() and BIO_ctrl_wpending()
 return the number of pending characters in the BIOs read and write buffers.
 Not all BIOs support these calls. BIO_ctrl_pending() and BIO_ctrl_wpending()
 return a size_t type and are functions, BIO_pending() and BIO_wpending() are
 macros which call BIO_ctrl().

 BIO_get_ktls_send() returns 1 if the BIO is using the Kernel TLS data-path for
 sending. Otherwise, it returns zero. It also returns negative values for failure.
 BIO_get_ktls_recv() returns 1 if the BIO is using the Kernel TLS data-path for
 receiving. Otherwise, it returns zero. It also returns negative values for failure.

 BIO_get_conn_mode() returns the BIO connection mode. BIO_set_conn_mode() sets
 the BIO connection mode.

 BIO_set_tfo() disables TCP Fast Open when B<onoff> is 0, and enables TCP Fast
 Open when B<onoff> is nonzero. Setting the value to 1 is equivalent to setting
 B<BIO_SOCK_TFO> in BIO_set_conn_mode().

 =head1 RETURN VALUES

 BIO_reset() normally returns 1 for success and <=0 for failure. File
 BIOs are an exception, they return 0 for success and -1 for failure.

 BIO_seek() and BIO_tell() both return the current file position on success
 and -1 for failure, except file BIOs which for BIO_seek() always return 0
 for success and -1 for failure.

 BIO_flush() returns 1 for success and <=0 for failure.

 BIO_eof() returns 1 if EOF has been reached, 0 if not, or negative values for failure.

 BIO_set_close() returns 1 on success or <=0 for failure.

 BIO_get_close() returns the close flag value: BIO_CLOSE or BIO_NOCLOSE. It also
 returns other negative values if an error occurs.

 BIO_pending(), BIO_ctrl_pending(), BIO_wpending() and BIO_ctrl_wpending()
 return the amount of pending data.

 BIO_get_ktls_send() returns 1 if the BIO is using the Kernel TLS data-path for
 sending. Otherwise, it returns zero.
 BIO_get_ktls_recv() returns 1 if the BIO is using the Kernel TLS data-path for
 receiving. Otherwise, it returns zero.

 BIO_set_conn_mode() returns 1 for success and 0 for failure. BIO_get_conn_mode()
 returns the current connection mode. Which may contain the bitwise-or of the
 following flags:

  BIO_SOCK_REUSEADDR
  BIO_SOCK_V6_ONLY
  BIO_SOCK_KEEPALIVE
  BIO_SOCK_NONBLOCK
  BIO_SOCK_NODELAY
  BIO_SOCK_TFO

 BIO_set_tfo() returns 1 for success, and 0 for failure.

 =head1 NOTES

 BIO_flush(), because it can write data may return 0 or -1 indicating
 that the call should be retried later in a similar manner to BIO_write_ex().
 The BIO_should_retry() call should be used and appropriate action taken
 is the call fails.

 The return values of BIO_pending() and BIO_wpending() may not reliably
 determine the amount of pending data in all cases. For example in the
 case of a file BIO some data may be available in the FILE structures
 internal buffers but it is not possible to determine this in a
 portably way. For other types of BIO they may not be supported.

 Filter BIOs if they do not internally handle a particular BIO_ctrl()
 operation usually pass the operation to the next BIO in the chain.
 This often means there is no need to locate the required BIO for
 a particular operation, it can be called on a chain and it will
 be automatically passed to the relevant BIO. However, this can cause
 unexpected results: for example no current filter BIOs implement
 BIO_seek(), but this may still succeed if the chain ends in a FILE
 or file descriptor BIO.

 Source/sink BIOs return an 0 if they do not recognize the BIO_ctrl()
 operation.

 =head1 BUGS

 Some of the return values are ambiguous and care should be taken. In
 particular a return value of 0 can be returned if an operation is not
 supported, if an error occurred, if EOF has not been reached and in
 the case of BIO_seek() on a file BIO for a successful operation.

 =head1 HISTORY

 The BIO_get_ktls_send() and BIO_get_ktls_recv() functions were added in
 OpenSSL 3.0.

 The BIO_get_conn_mode(), BIO_set_conn_mode() and BIO_set_tfo() functions
 were added in OpenSSL 3.1.

 =head1 COPYRIGHT

 Copyright 2000-2022 The OpenSSL Project Authors. All Rights Reserved.

 Licensed under the Apache License 2.0 (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
	=pod

	=head1 NAME

	BIO_ctrl, BIO_callback_ctrl, BIO_ptr_ctrl, BIO_int_ctrl, BIO_reset,
	BIO_seek, BIO_tell, BIO_flush, BIO_eof, BIO_set_close, BIO_get_close,
	BIO_pending, BIO_wpending, BIO_ctrl_pending, BIO_ctrl_wpending,
	BIO_get_info_callback, BIO_set_info_callback, BIO_info_cb, BIO_get_ktls_send,
	BIO_get_ktls_recv, BIO_set_conn_mode, BIO_get_conn_mode, BIO_set_tfo
	- BIO control operations

	=head1 SYNOPSIS

	#include <openssl/bio.h>

	typedef int BIO_info_cb(BIO *b, int state, int res);

	long BIO_ctrl(BIO bp, int cmd, long larg, void parg);
	long BIO_callback_ctrl(BIO b, int cmd, BIO_info_cb cb);
	void BIO_ptr_ctrl(BIO bp, int cmd, long larg);
	long BIO_int_ctrl(BIO *bp, int cmd, long larg, int iarg);

	int BIO_reset(BIO *b);
	int BIO_seek(BIO *b, int ofs);
	int BIO_tell(BIO *b);
	int BIO_flush(BIO *b);
	int BIO_eof(BIO *b);
	int BIO_set_close(BIO *b, long flag);
	int BIO_get_close(BIO *b);
	int BIO_pending(BIO *b);
	int BIO_wpending(BIO *b);
	size_t BIO_ctrl_pending(BIO *b);
	size_t BIO_ctrl_wpending(BIO *b);

	int BIO_get_info_callback(BIO b, BIO_info_cb *cbp);
	int BIO_set_info_callback(BIO b, BIO_info_cb cb);

	int BIO_get_ktls_send(BIO *b);
	int BIO_get_ktls_recv(BIO *b);

	int BIO_set_conn_mode(BIO *b, int mode);
	int BIO_get_conn_mode(BIO *b);

	int BIO_set_tfo(BIO *b, int onoff);

	=head1 DESCRIPTION

	BIO_ctrl(), BIO_callback_ctrl(), BIO_ptr_ctrl() and BIO_int_ctrl()
	are BIO "control" operations taking arguments of various types.
	These functions are not normally called directly, various macros
	are used instead. The standard macros are described below, macros
	specific to a particular type of BIO are described in the specific
	BIOs manual page as well as any special features of the standard
	calls.

	BIO_reset() typically resets a BIO to some initial state, in the case
	of file related BIOs for example it rewinds the file pointer to the
	start of the file.

	BIO_seek() resets a file related BIO's (that is file descriptor and
	FILE BIOs) file position pointer to B<ofs> bytes from start of file.

	BIO_tell() returns the current file position of a file related BIO.

	BIO_flush() normally writes out any internally buffered data, in some
	cases it is used to signal EOF and that no more data will be written.

	BIO_eof() returns 1 if the BIO has read EOF, the precise meaning of
	"EOF" varies according to the BIO type.

	BIO_set_close() sets the BIO B<b> close flag to B<flag>. B<flag> can
	take the value BIO_CLOSE or BIO_NOCLOSE. Typically BIO_CLOSE is used
	in a source/sink BIO to indicate that the underlying I/O stream should
	be closed when the BIO is freed.

	BIO_get_close() returns the BIOs close flag.

	BIO_pending(), BIO_ctrl_pending(), BIO_wpending() and BIO_ctrl_wpending()
	return the number of pending characters in the BIOs read and write buffers.
	Not all BIOs support these calls. BIO_ctrl_pending() and BIO_ctrl_wpending()
	return a size_t type and are functions, BIO_pending() and BIO_wpending() are
	macros which call BIO_ctrl().

	BIO_get_ktls_send() returns 1 if the BIO is using the Kernel TLS data-path for
	sending. Otherwise, it returns zero. It also returns negative values for failure.
	BIO_get_ktls_recv() returns 1 if the BIO is using the Kernel TLS data-path for
	receiving. Otherwise, it returns zero. It also returns negative values for failure.

	BIO_get_conn_mode() returns the BIO connection mode. BIO_set_conn_mode() sets
	the BIO connection mode.

	BIO_set_tfo() disables TCP Fast Open when B<onoff> is 0, and enables TCP Fast
	Open when B<onoff> is nonzero. Setting the value to 1 is equivalent to setting
	B<BIO_SOCK_TFO> in BIO_set_conn_mode().

	=head1 RETURN VALUES

	BIO_reset() normally returns 1 for success and <=0 for failure. File
	BIOs are an exception, they return 0 for success and -1 for failure.

	BIO_seek() and BIO_tell() both return the current file position on success
	and -1 for failure, except file BIOs which for BIO_seek() always return 0
	for success and -1 for failure.

	BIO_flush() returns 1 for success and <=0 for failure.

	BIO_eof() returns 1 if EOF has been reached, 0 if not, or negative values for failure.

	BIO_set_close() returns 1 on success or <=0 for failure.

	BIO_get_close() returns the close flag value: BIO_CLOSE or BIO_NOCLOSE. It also
	returns other negative values if an error occurs.

	BIO_pending(), BIO_ctrl_pending(), BIO_wpending() and BIO_ctrl_wpending()
	return the amount of pending data.

	BIO_get_ktls_send() returns 1 if the BIO is using the Kernel TLS data-path for
	sending. Otherwise, it returns zero.
	BIO_get_ktls_recv() returns 1 if the BIO is using the Kernel TLS data-path for
	receiving. Otherwise, it returns zero.

	BIO_set_conn_mode() returns 1 for success and 0 for failure. BIO_get_conn_mode()
	returns the current connection mode. Which may contain the bitwise-or of the
	following flags:

	BIO_SOCK_REUSEADDR
	BIO_SOCK_V6_ONLY
	BIO_SOCK_KEEPALIVE
	BIO_SOCK_NONBLOCK
	BIO_SOCK_NODELAY
	BIO_SOCK_TFO

	BIO_set_tfo() returns 1 for success, and 0 for failure.

	=head1 NOTES

	BIO_flush(), because it can write data may return 0 or -1 indicating
	that the call should be retried later in a similar manner to BIO_write_ex().
	The BIO_should_retry() call should be used and appropriate action taken
	is the call fails.

	The return values of BIO_pending() and BIO_wpending() may not reliably
	determine the amount of pending data in all cases. For example in the
	case of a file BIO some data may be available in the FILE structures
	internal buffers but it is not possible to determine this in a
	portably way. For other types of BIO they may not be supported.

	Filter BIOs if they do not internally handle a particular BIO_ctrl()
	operation usually pass the operation to the next BIO in the chain.
	This often means there is no need to locate the required BIO for
	a particular operation, it can be called on a chain and it will
	be automatically passed to the relevant BIO. However, this can cause
	unexpected results: for example no current filter BIOs implement
	BIO_seek(), but this may still succeed if the chain ends in a FILE
	or file descriptor BIO.

	Source/sink BIOs return an 0 if they do not recognize the BIO_ctrl()
	operation.

	=head1 BUGS

	Some of the return values are ambiguous and care should be taken. In
	particular a return value of 0 can be returned if an operation is not
	supported, if an error occurred, if EOF has not been reached and in
	the case of BIO_seek() on a file BIO for a successful operation.

	=head1 HISTORY

	The BIO_get_ktls_send() and BIO_get_ktls_recv() functions were added in
	OpenSSL 3.0.

	The BIO_get_conn_mode(), BIO_set_conn_mode() and BIO_set_tfo() functions
	were added in OpenSSL 3.1.

	=head1 COPYRIGHT

	Copyright 2000-2022 The OpenSSL Project Authors. All Rights Reserved.

	Licensed under the Apache License 2.0 (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