mirror of
https://github.com/openssl/openssl.git
synced 2024-12-15 06:01:37 +08:00
99d63d4662
Move manpages to manX directories Add Windows/VMS install fix from Richard Levitte Update README Fix typo's Remove some duplicates Reviewed-by: Richard Levitte <levitte@openssl.org>
145 lines
7.2 KiB
Plaintext
145 lines
7.2 KiB
Plaintext
=pod
|
|
|
|
=head1 NAME
|
|
|
|
ASYNC_WAIT_CTX_new, ASYNC_WAIT_CTX_free, ASYNC_WAIT_CTX_set_wait_fd,
|
|
ASYNC_WAIT_CTX_get_fd, ASYNC_WAIT_CTX_get_all_fds,
|
|
ASYNC_WAIT_CTX_get_changed_fds, ASYNC_WAIT_CTX_clear_fd - functions to manage
|
|
waiting for asynchronous jobs to complete
|
|
|
|
=head1 SYNOPSIS
|
|
|
|
#include <openssl/async.h>
|
|
|
|
ASYNC_WAIT_CTX *ASYNC_WAIT_CTX_new(void);
|
|
void ASYNC_WAIT_CTX_free(ASYNC_WAIT_CTX *ctx);
|
|
int ASYNC_WAIT_CTX_set_wait_fd(ASYNC_WAIT_CTX *ctx, const void *key,
|
|
OSSL_ASYNC_FD fd,
|
|
void *custom_data,
|
|
void (*cleanup)(ASYNC_WAIT_CTX *, const void *,
|
|
OSSL_ASYNC_FD, void *));
|
|
int ASYNC_WAIT_CTX_get_fd(ASYNC_WAIT_CTX *ctx, const void *key,
|
|
OSSL_ASYNC_FD *fd, void **custom_data);
|
|
int ASYNC_WAIT_CTX_get_all_fds(ASYNC_WAIT_CTX *ctx, OSSL_ASYNC_FD *fd,
|
|
size_t *numfds);
|
|
int ASYNC_WAIT_CTX_get_changed_fds(ASYNC_WAIT_CTX *ctx, OSSL_ASYNC_FD *addfd,
|
|
size_t *numaddfds, OSSL_ASYNC_FD *delfd,
|
|
size_t *numdelfds);
|
|
int ASYNC_WAIT_CTX_clear_fd(ASYNC_WAIT_CTX *ctx, const void *key);
|
|
|
|
|
|
=head1 DESCRIPTION
|
|
|
|
For an overview of how asynchronous operations are implemented in OpenSSL see
|
|
L<ASYNC_start_job(3)>. An ASYNC_WAIT_CTX object represents an asynchronous
|
|
"session", i.e. a related set of crypto operations. For example in SSL terms
|
|
this would have a one-to-one correspondence with an SSL connection.
|
|
|
|
Application code must create an ASYNC_WAIT_CTX using the ASYNC_WAIT_CTX_new()
|
|
function prior to calling ASYNC_start_job() (see L<ASYNC_start_job(3)>). When
|
|
the job is started it is associated with the ASYNC_WAIT_CTX for the duration of
|
|
that job. An ASYNC_WAIT_CTX should only be used for one ASYNC_JOB at any one
|
|
time, but can be reused after an ASYNC_JOB has finished for a subsequent
|
|
ASYNC_JOB. When the session is complete (e.g. the SSL connection is closed),
|
|
application code cleans up with ASYNC_WAIT_CTX_free().
|
|
|
|
ASYNC_WAIT_CTXs can have "wait" file descriptors associated with them. Calling
|
|
ASYNC_WAIT_CTX_get_all_fds() and passing in a pointer to an ASYNC_WAIT_CTX in
|
|
the B<ctx> parameter will return the wait file descriptors associated with that
|
|
job in B<*fd>. The number of file descriptors returned will be stored in
|
|
B<*numfds>. It is the caller's responsibility to ensure that sufficient memory
|
|
has been allocated in B<*fd> to receive all the file descriptors. Calling
|
|
ASYNC_WAIT_CTX_get_all_fds() with a NULL B<fd> value will return no file
|
|
descriptors but will still populate B<*numfds>. Therefore application code is
|
|
typically expected to call this function twice: once to get the number of fds,
|
|
and then again when sufficient memory has been allocated. If only one
|
|
asynchronous engine is being used then normally this call will only ever return
|
|
one fd. If multiple asynchronous engines are being used then more could be
|
|
returned.
|
|
|
|
The function ASYNC_WAIT_CTX_fds_have_changed() can be used to detect if any fds
|
|
have changed since the last call time ASYNC_start_job() returned an ASYNC_PAUSE
|
|
result (or since the ASYNC_WAIT_CTX was created if no ASYNC_PAUSE result has
|
|
been received). The B<numaddfds> and B<numdelfds> parameters will be populated
|
|
with the number of fds added or deleted respectively. B<*addfd> and B<*delfd>
|
|
will be populated with the list of added and deleted fds respectively. Similarly
|
|
to ASYNC_WAIT_CTX_get_all_fds() either of these can be NULL, but if they are not
|
|
NULL then the caller is responsible for ensuring sufficient memory is allocated.
|
|
|
|
Implementors of async aware code (e.g. engines) are encouraged to return a
|
|
stable fd for the lifetime of the ASYNC_WAIT_CTX in order to reduce the "churn"
|
|
of regularly changing fds - although no guarantees of this are provided to
|
|
applications.
|
|
|
|
Applications can wait for the file descriptor to be ready for "read" using a
|
|
system function call such as select or poll (being ready for "read" indicates
|
|
that the job should be resumed). If no file descriptor is made available then an
|
|
application will have to periodically "poll" the job by attempting to restart it
|
|
to see if it is ready to continue.
|
|
|
|
Async aware code (e.g. engines) can get the current ASYNC_WAIT_CTX from the job
|
|
via L<ASYNC_get_wait_ctx(3)> and provide a file descriptor to use for waiting
|
|
on by calling ASYNC_WAIT_CTX_set_wait_fd(). Typically this would be done by an
|
|
engine immediately prior to calling ASYNC_pause_job() and not by end user code.
|
|
An existing association with a file descriptor can be obtained using
|
|
ASYNC_WAIT_CTX_get_fd() and cleared using ASYNC_WAIT_CTX_clear_fd(). Both of
|
|
these functions requires a B<key> value which is unique to the async aware
|
|
code. This could be any unique value but a good candidate might be the
|
|
B<ENGINE *> for the engine. The B<custom_data> parameter can be any value, and
|
|
will be returned in a subsequent call to ASYNC_WAIT_CTX_get_fd(). The
|
|
ASYNC_WAIT_CTX_set_wait_fd() function also expects a pointer to a "cleanup"
|
|
routine. This can be NULL but if provided will automatically get called when
|
|
the ASYNC_WAIT_CTX is freed, and gives the engine the opportunity to close the
|
|
fd or any other resources. Note: The "cleanup" routine does not get called if
|
|
the fd is cleared directly via a call to ASYNC_WAIT_CTX_clear_fd().
|
|
|
|
An example of typical usage might be an async capable engine. User code would
|
|
initiate cryptographic operations. The engine would initiate those operations
|
|
asynchronously and then call ASYNC_WAIT_CTX_set_wait_fd() followed by
|
|
ASYNC_pause_job() to return control to the user code. The user code can then
|
|
perform other tasks or wait for the job to be ready by calling "select" or other
|
|
similar function on the wait file descriptor. The engine can signal to the user
|
|
code that the job should be resumed by making the wait file descriptor
|
|
"readable". Once resumed the engine should clear the wake signal on the wait
|
|
file descriptor.
|
|
|
|
=head1 RETURN VALUES
|
|
|
|
ASYNC_WAIT_CTX_new() returns a pointer to the newly allocated ASYNC_WAIT_CTX or
|
|
NULL on error.
|
|
|
|
ASYNC_WAIT_CTX_set_wait_fd, ASYNC_WAIT_CTX_get_fd, ASYNC_WAIT_CTX_get_all_fds,
|
|
ASYNC_WAIT_CTX_get_changed_fds and ASYNC_WAIT_CTX_clear_fd all 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<crypto(3)>, L<ASYNC_start_job(3)>
|
|
|
|
=head1 HISTORY
|
|
|
|
ASYNC_WAIT_CTX_new, ASYNC_WAIT_CTX_free, ASYNC_WAIT_CTX_set_wait_fd,
|
|
ASYNC_WAIT_CTX_get_fd, ASYNC_WAIT_CTX_get_all_fds,
|
|
ASYNC_WAIT_CTX_get_changed_fds, ASYNC_WAIT_CTX_clear_fd were first added to
|
|
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
|