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       SSL_waiting_for_async, SSL_get_all_async_fds, SSL_get_changed_async_fds
       - manage	asynchronous operations

	#include <openssl/async.h>
	#include <openssl/ssl.h>

	int SSL_waiting_for_async(SSL *s);
	int SSL_get_all_async_fds(SSL *s, OSSL_ASYNC_FD	*fd, size_t *numfds);
	int SSL_get_changed_async_fds(SSL *s, OSSL_ASYNC_FD *addfd, size_t *numaddfds,
				      OSSL_ASYNC_FD *delfd, size_t *numdelfds);

       SSL_waiting_for_async() determines whether an SSL connection is
       currently waiting for asynchronous operations to	complete (see the
       SSL_MODE_ASYNC mode in SSL_CTX_set_mode(3)).

       SSL_get_all_async_fds() returns a list of file descriptor which can be
       used in a call to select() or poll() to determine whether the current
       asynchronous operation has completed or not. A completed	operation will
       result in data appearing	as "read ready"	on the file descriptor (no
       actual data should be read from the file	descriptor). This function
       should only be called if	the SSL	object is currently waiting for
       asynchronous work to complete (i.e.  SSL_ERROR_WANT_ASYNC has been
       received	- see SSL_get_error(3)). Typically the list will only contain
       one file	descriptor. However, if	multiple asynchronous capable engines
       are in use then more than one is	possible. The number of	file
       descriptors returned is stored in *numfds and the file descriptors
       themselves are in *fds. The fds parameter may be	NULL in	which case no
       file descriptors	are returned but *numfds is still populated. It	is the
       callers responsibility to ensure	sufficient memory is allocated at *fds
       so typically this function is called twice (once	with a NULL fds
       parameter and once without).

       SSL_get_changed_async_fds() returns a list of the asynchronous file
       descriptors that	have been added	and a list that	have been deleted
       since the last SSL_ERROR_WANT_ASYNC was received	(or since the SSL
       object was created if no	SSL_ERROR_WANT_ASYNC has been received).
       Similar to SSL_get_all_async_fds() it is	the callers responsibility to
       ensure that *addfd and *delfd have sufficient memory allocated,
       although	they may be NULL. The number of	added fds and the number of
       deleted fds are stored in *numaddfds and	*numdelfds respectively.

       SSL_waiting_for_async() will return 1 if	the current SSL	operation is
       waiting for an async operation to complete and 0	otherwise.

       SSL_get_all_async_fds() and SSL_get_changed_async_fds() return 1	on
       success or 0 on error.

       On Windows platforms the	openssl/async.h	header is dependent on some of
       the types customarily made available by including windows.h. The
       application developer is	likely to require control over when the	latter
       is included, commonly as	one of the first included headers. Therefore,
       it is defined as	an application developer's responsibility to include
       windows.h prior to async.h.

       SSL_get_error(3), SSL_CTX_set_mode(3)

       The SSL_waiting_for_async(), SSL_get_all_async_fds() and
       SSL_get_changed_async_fds() functions were added	in OpenSSL 1.1.0.

       Copyright 2016-2020 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

1.1.1k				  2021-03-25	      SSL_GET_ALL_ASYNC_FDS(3)


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