=pod

=head1 NAME

SSL_waiting_for_async,

SSL_get_all_async_fds,

SSL_get_changed_async_fds

- manage asynchronous operations

=head1 SYNOPSIS

=for comment multiple includes

 #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);

=head1 DESCRIPTION

SSL_waiting_for_async() determines whether an SSL connection is currently

waiting for asynchronous operations to complete (see the SSL_MODE_ASYNC mode in

L<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 L<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 B<*numfds> and the file descriptors themselves

are in B<*fds>. The B<fds> parameter may be NULL in which case no file

descriptors are returned but B<*numfds> is still populated. It is the callers

responsibility to ensure sufficient memory is allocated at B<*fds> so typically

this function is called twice (once with a NULL B<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 B<*addfd> and B<*delfd> have

sufficient memory allocated, although they may be NULL. The number of added fds

and the number of deleted fds are stored in B<*numaddfds> and B<*numdelfds>

respectively.

=head1 RETURN VALUES

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.

=head1 NOTES

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.

=head1 SEE ALSO

L<SSL_get_error(3)>, L<SSL_CTX_set_mode(3)>

=head1 HISTORY

The SSL_waiting_for_async(), SSL_get_all_async_fds()

and SSL_get_changed_async_fds() functions were added in OpenSSL 1.1.0.

=head1 COPYRIGHT

Copyright 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