103 lines
3.9 KiB
C
103 lines
3.9 KiB
C
/*
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* Copyright 2023 The OpenSSL Project Authors. All Rights Reserved.
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*
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* Licensed under the Apache License 2.0 (the "License"). You may not use
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* this file except in compliance with the License. You can obtain a copy
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* in the file LICENSE in the source distribution or at
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* https://www.openssl.org/source/license.html
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*/
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#ifndef OSSL_QUIC_THREAD_ASSIST_H
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# define OSSL_QUIC_THREAD_ASSIST_H
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# include <openssl/ssl.h>
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# include "internal/thread.h"
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# include "internal/time.h"
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# if defined(OPENSSL_NO_QUIC) || defined(OPENSSL_NO_THREAD_POOL)
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# define OPENSSL_NO_QUIC_THREAD_ASSIST
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# endif
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# ifndef OPENSSL_NO_QUIC_THREAD_ASSIST
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/*
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* QUIC Thread Assisted Functionality
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* ==================================
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*
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* Where OS threading support is available, QUIC can optionally support a thread
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* assisted mode of operation. The purpose of this mode of operation is to
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* ensure that assorted timeout events which QUIC expects to be handled in a
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* timely manner can be handled without the application needing to ensure that
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* SSL_tick() is called on time. This is not needed if the application always
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* has a call blocking to SSL_read() or SSL_write() (or another I/O function) on
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* a QUIC SSL object, but if the application goes for long periods of time
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* without making any such call to a QUIC SSL object, libssl cannot ordinarily
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* guarantee that QUIC timeout events will be serviced in a timely fashion.
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* Thread assisted mode is therefore of use to applications which do not always
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* have an ongoing call to an I/O function on a QUIC SSL object but also do not
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* want to have to arrange periodic ticking.
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*
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* A consequence of this is that the intrusiveness of thread assisted mode upon
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* the general architecture of our QUIC engine is actually fairly limited and
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* amounts to an automatic ticking of the QUIC engine when timeouts expire,
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* synchronised correctly with an application's own threads using locking.
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*/
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typedef struct quic_thread_assist_st {
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QUIC_CHANNEL *ch;
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CRYPTO_CONDVAR *cv;
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CRYPTO_THREAD *t;
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int teardown, joined;
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OSSL_TIME (*now_cb)(void *arg);
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void *now_cb_arg;
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} QUIC_THREAD_ASSIST;
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/*
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* Initialise the thread assist object. The channel must have a valid mutex
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* configured on it which will be retrieved automatically. It is assumed that
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* the mutex is currently held when this function is called. This function does
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* not affect the state of the mutex.
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*/
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int ossl_quic_thread_assist_init_start(QUIC_THREAD_ASSIST *qta,
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QUIC_CHANNEL *ch,
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OSSL_TIME (*now_cb)(void *arg),
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void *now_cb_arg);
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/*
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* Request the thread assist helper to begin stopping the assist thread. This
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* returns before the teardown is complete. Idempotent; multiple calls to this
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* function are inconsequential.
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*
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* Precondition: channel mutex must be held (unchecked)
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*/
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int ossl_quic_thread_assist_stop_async(QUIC_THREAD_ASSIST *qta);
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/*
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* Wait until the thread assist helper is torn down. This automatically implies
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* the effects of ossl_quic_thread_assist_stop_async(). Returns immediately
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* if the teardown has already completed.
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*
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* Precondition: channel mutex must be held (unchecked)
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*/
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int ossl_quic_thread_assist_wait_stopped(QUIC_THREAD_ASSIST *qta);
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/*
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* Deallocates state associated with the thread assist helper.
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* ossl_quic_thread_assist_wait_stopped() must have returned successfully before
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* calling this. It does not matter whether the channel mutex is held or not.
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*
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* Precondition: ossl_quic_thread_assist_wait_stopped() has returned 1
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* (asserted)
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*/
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int ossl_quic_thread_assist_cleanup(QUIC_THREAD_ASSIST *qta);
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/*
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* Must be called to notify the assist thread if the channel deadline changes.
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*
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* Precondition: channel mutex must be held (unchecked)
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*/
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int ossl_quic_thread_assist_notify_deadline_changed(QUIC_THREAD_ASSIST *qta);
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# endif
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#endif
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