Commit 9f5a87fd authored by Ping Yu's avatar Ping Yu Committed by Matt Caswell
Browse files

add an additional async notification communication method based on callback 



Reviewed-by: default avatarMatt Caswell <matt@openssl.org>
Reviewed-by: default avatarPaul Yang <yang.yang@baishancloud.com>
Signed-off-by: default avatarPing Yu <ping.yu@intel.com>
Signed-off-by: default avatarSteven Linsell <stevenx.linsell@intel.com>

(Merged from https://github.com/openssl/openssl/pull/7573)
parent 61e03330

crypto/async/async_locl.h

+3 −0
Original line number Diff line number Diff line
@@ -59,6 +59,9 @@ struct async_wait_ctx_st { 
    struct fd_lookup_st *fds;

    size_t numadd;

    size_t numdel;

    ASYNC_callback_fn callback;

    void *callback_arg;

    int status;

};



DEFINE_STACK_OF(ASYNC_JOB)

crypto/async/async_wait.c

+35 −0
Original line number Diff line number Diff line
@@ -182,6 +182,41 @@ int ASYNC_WAIT_CTX_clear_fd(ASYNC_WAIT_CTX *ctx, const void *key) 
    return 0;

}



int ASYNC_WAIT_CTX_set_callback(ASYNC_WAIT_CTX *ctx,

                                ASYNC_callback_fn callback,

                                void *callback_arg)

{

      if (ctx == NULL)

          return 0;



      ctx->callback = callback;

      ctx->callback_arg = callback_arg;

      return 1;

}



int ASYNC_WAIT_CTX_get_callback(ASYNC_WAIT_CTX *ctx,

                                ASYNC_callback_fn *callback,

                                void **callback_arg)

{

      if (ctx->callback == NULL)

          return 0;



      *callback = ctx->callback;

      *callback_arg = ctx->callback_arg;

      return 1;

}



int ASYNC_WAIT_CTX_set_status(ASYNC_WAIT_CTX *ctx, int status)

{

      ctx->status = status;

      return 1;

}



int ASYNC_WAIT_CTX_get_status(ASYNC_WAIT_CTX *ctx)

{

      return ctx->status;

}



void async_wait_ctx_reset_counts(ASYNC_WAIT_CTX *ctx)

{

    struct fd_lookup_st *curr, *prev = NULL;

doc/man3/ASYNC_WAIT_CTX_new.pod

+69 −4
Original line number Diff line number Diff line
@@ -4,13 +4,22 @@ 


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

ASYNC_WAIT_CTX_get_changed_fds, ASYNC_WAIT_CTX_clear_fd,

ASYNC_WAIT_CTX_set_callback, ASYNC_WAIT_CTX_get_callback,

ASYNC_WAIT_CTX_set_status, ASYNC_WAIT_CTX_get_status, ASYNC_callback_fn,

ASYNC_STATUS_UNSUPPORTED, ASYNC_STATUS_ERR, ASYNC_STATUS_OK,

ASYNC_STATUS_EAGAIN

- functions to manage waiting for asynchronous jobs to complete



=head1 SYNOPSIS



 #include <openssl/async.h>



 #define ASYNC_STATUS_UNSUPPORTED    0

 #define ASYNC_STATUS_ERR            1

 #define ASYNC_STATUS_OK             2

 #define ASYNC_STATUS_EAGAIN         3

 typedef int (*ASYNC_callback_fn)(void *arg);

 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,
@@ -26,6 +35,14 @@ waiting for asynchronous jobs to complete 
                                    size_t *numaddfds, OSSL_ASYNC_FD *delfd,

                                    size_t *numdelfds);

 int ASYNC_WAIT_CTX_clear_fd(ASYNC_WAIT_CTX *ctx, const void *key);

 int ASYNC_WAIT_CTX_set_callback(ASYNC_WAIT_CTX *ctx,

                                 ASYNC_callback_fn callback,

                                 void *callback_arg);

 int ASYNC_WAIT_CTX_get_callback(ASYNC_WAIT_CTX *ctx,

                                 ASYNC_callback_fn *callback,

                                 void **callback_arg);

 int ASYNC_WAIT_CTX_set_status(ASYNC_WAIT_CTX *ctx, int status);

 int ASYNC_WAIT_CTX_get_status(ASYNC_WAIT_CTX *ctx);





=head1 DESCRIPTION
@@ -103,14 +120,58 @@ 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.



As well as a file descriptor, user code may also be notified via a callback. The

callback and data pointers are stored within the ASYNC_WAIT_CTX along with an

additional status field that can be used for the notification of retries from an

engine. This additional method can be used when the user thinks that a file

descriptor is too costly in terms of CPU cycles or in some context where a file

descriptor is not appropriate.



ASYNC_WAIT_CTX_set_callback() sets the callback and the callback argument. The

callback will be called to notify user code when an engine completes a

cryptography operation. It is a requirement that the callback function is small

and non-blocking as it will be run in the context of a polling mechanism or an

interrupt.



ASYNC_WAIT_CTX_get_callback() returns the callback set in the ASYNC_WAIT_CTX

structure.



ASYNC_WAIT_CTX_set_status() allows an engine to set the current engine status.

The possible status values are the following:

ASYNC_STATUS_UNSUPPORTED: The engine does not support the callback mechanism.

This is the default value. The engine must call ASYNC_WAIT_CTX_set_status() to

set the status to some value other than ASYNC_STATUS_UNSUPPORTED if it intends

to enable the callback mechanism.

ASYNC_STATUS_ERR: The engine has a fatal problem with this request. The user

code should clean up this session.

ASYNC_STATUS_OK: The request has been successfully submitted.

ASYNC_STATUS_EAGAIN: The engine has some problem which will be recovered soon,

such as a buffer is full, so user code should resume the job.



ASYNC_WAIT_CTX_get_status() allows user code to obtain the current status value.

If the status is any value other than ASYNC_STATUS_OK then the user code should

not expect to receive a callback from the engine even if one has been set.



An example of the usage of the callback method might be the following. User

code would initiate cryptographic operations, and the engine code would dispatch

this operation to hardware, and if the dispatch is successful, then the engine

code would call ASYNC_pause_job() to return control to the user code. After

that, user code can perform other tasks. When the hardware completes the

operation, normally it is detected by a polling function or an interrupt, as the

user code set a callback by calling ASYNC_WAIT_CTX_set_callback() previously,

then the registered callback will be called.



=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.

ASYNC_WAIT_CTX_get_changed_fds, ASYNC_WAIT_CTX_clear_fd,

ASYNC_WAIT_CTX_set_callback, ASYNC_WAIT_CTX_get_callback and

ASYNC_WAIT_CTX_set_status all return 1 on success or 0 on error.

ASYNC_WAIT_CTX_get_status() returs the engine status.





=head1 NOTES
@@ -132,6 +193,10 @@ ASYNC_WAIT_CTX_get_fd(), ASYNC_WAIT_CTX_get_all_fds(), 
ASYNC_WAIT_CTX_get_changed_fds() and ASYNC_WAIT_CTX_clear_fd()

were added in OpenSSL 1.1.0.



ASYNC_WAIT_CTX_set_callback(), ASYNC_WAIT_CTX_get_callback(),

ASYNC_WAIT_CTX_set_status(), and ASYNC_WAIT_CTX_get_status()

were added in OpenSSL 3.0.0.



=head1 COPYRIGHT



Copyright 2016 The OpenSSL Project Authors. All Rights Reserved.

doc/man3/ASYNC_start_job.pod

+20 −16
Original line number Diff line number Diff line
@@ -107,22 +107,26 @@ ASYNC_pause_job() is called whilst not within the context of a job then no 
action is taken and ASYNC_pause_job() returns immediately.



ASYNC_get_wait_ctx() can be used to get a pointer to the ASYNC_WAIT_CTX

for the B<job>. ASYNC_WAIT_CTXs can have a "wait" file descriptor associated

with them. 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.



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 L<ASYNC_WAIT_CTX_set_wait_fd(3)> 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.

for the B<job>. ASYNC_WAIT_CTXs contain two different ways to notify

applications that a job is ready to be resumed. One is a "wait" file

descriptor, and the other is a "callback" mechanism.



The "wait" file descriptor associated with ASYNC_WAIT_CTX is used for

applications to 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_WAIT_CTXs also have a "callback" mechanism to notify applications. The

callback is set by an application, and it will be automatically called when an

engine completes a cryptography operation, so that the application can resume

the paused work flow without polling. An engine could be written to look whether

the callback has been set. If it has then it would use the callback mechanism

in preference to the file descriptor notifications. If a callback is not set

then the engine may use file descriptor based notifications. Please note that

not all engines may support the callback mechanism, so the callback may not be

used even if it has been set. See ASYNC_WAIT_CTX_new() for more details.



The ASYNC_block_pause() function will prevent the currently active job from

pausing. The block will remain in place until a subsequent call to

doc/man3/SSL_set_async_callback.pod

0 → 100644
+96 −0
Original line number Diff line number Diff line 
=pod



=head1 NAME



SSL_CTX_set_async_callback,

SSL_CTX_set_async_callback_arg,

SSL_set_async_callback,

SSL_set_async_callback_arg,

SSL_get_async_status,

SSL_async_callback_fn

- manage asynchronous operations



=head1 SYNOPSIS



=for comment multiple includes



 #include <openssl/ssl.h>



 typedef int (*SSL_async_callback_fn)(SSL *s, void *arg);

 int SSL_CTX_set_async_callback(SSL_CTX *ctx, SSL_async_callback_fn callback);

 int SSL_CTX_set_async_callback_arg(SSL_CTX *ctx, void *arg);

 int SSL_set_async_callback(SSL *s, SSL_async_callback_fn callback);

 int SSL_set_async_callback_arg(SSL *s, void *arg);

 int SSL_get_async_status(SSL *s, int *status);



=head1 DESCRIPTION



SSL_CTX_set_async_callback() sets an asynchronous callback function. All SSL

objects generated based on this SSL_CTX will get this callback. If an engine

supports the callback mechanism, it will be automatically called if

SSL_MODE_ASYNC has been set and an asynchronous capable engine completes a

cryptography operation to notify the application to resume the paused work flow.



SSL_CTX_set_async_callback_arg() sets the callback argument.



SSL_set_async_callback() allows an application to set a callback in an

asynchronous SSL object, so that when an engine completes a cryptography

operation, the callback will be called to notify the application to resume the

paused work flow.



SSL_set_async_callback_arg() sets an argument for the SSL object when the above

callback is called.



SSL_get_async_status() returns the engine status. This function facilitates the

communication from the engine to the application. During an SSL session,

cryptographic operations are dispatched to an engine. The engine status is very

useful for an application to know if the operation has been successfully

dispatched. If the engine does not support this additional callback method,

"ASYNC_STATUS_UNSUPPORTED" will be returned. See ASYNC_WAIT_CTX_set_status() for

a description of all of the status values.



An example of the above functions would be the following.

1. Application sets the async callback and callback data on an SSL connection

by calling SSL_set_async_callback().

2. Application sets SSL_MODE_ASYNC and makes an asynchronous SSL call

3. OpenSSL submits the asynchronous request to the engine. If a retry occurs at

this point then the status within the ASYNC_WAIT_CTX would be set and the async

callback function would be called (goto Step 7).

4. The OpenSSL engine pauses the current job and returns, so that the

application can continue processing other connections.

5. At a future point in time (probably via a polling mechanism or via an

interrupt) the engine will become aware that the asynchronous request has

finished processing.

6. The engine will call the application's callback passing the callback data as

a parameter.

7. The callback function should then run. Note: it is a requirement that the

callback function is small and non-blocking as it will be run in the context of

a polling mechanism or an interrupt.

8. It is the application's responsibility via the callback function to schedule

recalling the OpenSSL asynchronous function and to continue processing.

9. The callback function has the option to check the status returned via

SSL_get_async_status() to determine whether a retry happened instead of the

request being submitted, allowing different processing if required.



=head1 RETURN VALUES



SSL_CTX_set_async_callback(), SSL_set_async_callback(),

SSL_CTX_set_async_callback_arg(), SSL_CTX_set_async_callback_arg() and

SSL_get_async_status() return 1 on success or 0 on error.



=head1 HISTORY



SSL_CTX_set_async_callback(), SSL_CTX_set_async_callback_arg(),

SSL_set_async_callback(), SSL_set_async_callback_arg() and

SSL_get_async_status() were first added to OpenSSL 3.0.0.



=head1 COPYRIGHT



Copyright 2019 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