NAME

       SSL_waiting_for_async, SSL_get_all_async_fds, SSL_get_changed_async_fds - manage asynchronous operations

SYNOPSIS

        #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);

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 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.

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.

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 <openssl/async.h>.

SEE ALSO

       ssl(7), SSL_get_error(3), SSL_CTX_set_mode(3)

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.

COPYRIGHT

       Copyright 2016-2021 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
       <https://www.openssl.org/source/license.html>.

3.4.1                                              2025-04-03                        SSL_GET_ALL_ASYNC_FDS(3SSL)