ssl: implement an event queue

Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/18345)

1 files changed, 194 insertions, 0 deletions

diff --git a/ssl/event_queue.c b/ssl/event_queue.c
new file mode 100644
index 0000000000..f828d5280f
--- /dev/null
+++ b/ssl/event_queue.c
@@ -0,0 +1,194 @@
+/*
+ * Copyright 2022 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
+ */
+
+#include <stdlib.h>
+#include "internal/event_queue.h"
+#include "crypto/sparse_array.h"
+#include "ssl_local.h"
+
+struct ossl_event_queue_st {
+    PRIORITY_QUEUE_OF(OSSL_EVENT) *timed_events;
+    PRIORITY_QUEUE_OF(OSSL_EVENT) *now_events;
+};
+
+static int event_compare_times(const OSSL_EVENT *a, const OSSL_EVENT *b)
+{
+    return ossl_time_compare(a->when, b->when);
+}
+
+static int event_compare_priority(const OSSL_EVENT *a, const OSSL_EVENT *b)
+{
+    if (a->priority > b->priority)
+        return -1;
+    if (a->priority < b->priority)
+        return 1;
+    return 0;
+}
+
+OSSL_EVENT_QUEUE *ossl_event_queue_new(void)
+{
+    OSSL_EVENT_QUEUE *r = OPENSSL_malloc(sizeof(*r));
+
+    if (r != NULL) {
+        r->timed_events = ossl_pqueue_OSSL_EVENT_new(&event_compare_times);
+        r->now_events = ossl_pqueue_OSSL_EVENT_new(&event_compare_priority);
+        if (r->timed_events == NULL || r->now_events == NULL) {
+            ossl_event_queue_free(r);
+            return NULL;
+        }
+    }
+    return r;
+}
+
+void ossl_event_free(OSSL_EVENT *event)
+{
+    if (event != NULL) {
+        if (event->flag_dynamic)
+            OPENSSL_free(event);
+        else
+            event->queue = NULL;
+    }
+}
+
+static void event_queue_free(PRIORITY_QUEUE_OF(OSSL_EVENT) *queue)
+{
+    OSSL_EVENT *e;
+
+    if (queue != NULL) {
+        while ((e = ossl_pqueue_OSSL_EVENT_pop(queue)) != NULL)
+            ossl_event_free(e);
+        ossl_pqueue_OSSL_EVENT_free(queue);
+    }
+}
+
+void ossl_event_queue_free(OSSL_EVENT_QUEUE *queue)
+{
+    if (queue != NULL) {
+        event_queue_free(queue->now_events);
+        event_queue_free(queue->timed_events);
+        OPENSSL_free(queue);
+    }
+}
+
+static ossl_inline
+int event_queue_add(OSSL_EVENT_QUEUE *queue, OSSL_EVENT *event)
+{
+    PRIORITY_QUEUE_OF(OSSL_EVENT) *pq =
+            ossl_time_compare(event->when, ossl_time_now()) <= 0
+            ? queue->now_events
+            : queue->timed_events;
+
+    if (ossl_pqueue_OSSL_EVENT_push(pq, event, &event->ref)) {
+        event->queue = pq;
+        return 1;
+    }
+    return 0;
+}
+
+static ossl_inline
+void ossl_event_set(OSSL_EVENT *event, uint32_t type, uint32_t priority,
+                    OSSL_TIME when, void *ctx,
+                    void *payload, size_t payload_size)
+{
+    event->type = type;
+    event->priority = priority;
+    event->when = when;
+    event->ctx = ctx;
+    event->payload = payload;
+    event->payload_size = payload_size;
+}
+
+OSSL_EVENT *ossl_event_queue_add_new(OSSL_EVENT_QUEUE *queue, 
+                                     uint32_t type, uint32_t priority,
+                                     OSSL_TIME when, void *ctx,
+                                     void *payload, size_t payload_size)
+{
+    OSSL_EVENT *e = OPENSSL_malloc(sizeof(*e));
+
+    if (e == NULL || queue == NULL)
+        return NULL;
+    ossl_event_set(e, type, priority, when, ctx, payload, payload_size);
+    e->flag_dynamic = 1;
+    if (event_queue_add(queue, e))
+        return e;
+    OPENSSL_free(e);
+    return NULL;
+}
+
+int ossl_event_queue_add(OSSL_EVENT_QUEUE *queue, OSSL_EVENT *event,
+                         uint32_t type, uint32_t priority,
+                         OSSL_TIME when, void *ctx,
+                         void *payload, size_t payload_size)
+{
+    if (event == NULL || queue == NULL)
+        return 0;
+    ossl_event_set(event, type, priority, when, ctx, payload, payload_size);
+    event->flag_dynamic = 0;
+    return event_queue_add(queue, event);
+}
+
+int ossl_event_queue_remove(OSSL_EVENT_QUEUE *queue, OSSL_EVENT *event)
+{
+    if (event != NULL && event->queue != NULL) {
+        ossl_pqueue_OSSL_EVENT_remove(event->queue, event->ref);
+        event->queue = NULL;
+    }
+    return 1;
+}
+
+OSSL_TIME ossl_event_time_until(const OSSL_EVENT *event)
+{
+    if (event == NULL)
+        return OSSL_TIME_INFINITY;
+    return ossl_time_subtract(event->when, ossl_time_now());
+}
+
+OSSL_TIME ossl_event_queue_time_until_next(const OSSL_EVENT_QUEUE *queue)
+{
+    if (queue == NULL)
+        return OSSL_TIME_INFINITY;
+    if (ossl_pqueue_OSSL_EVENT_num(queue->now_events) > 0)
+        return OSSL_TIME_IMMEDIATE;
+    return ossl_event_time_until(ossl_pqueue_OSSL_EVENT_peek(queue->timed_events));
+}
+
+int ossl_event_queue_postpone_until(OSSL_EVENT_QUEUE *queue,
+                                    OSSL_EVENT *event,
+                                    OSSL_TIME when)
+{
+    if (ossl_event_queue_remove(queue, event)) {
+        event->when = when;
+        return event_queue_add(queue, event);
+    }
+    return 0;
+}
+
+int ossl_event_queue_get1_next_event(OSSL_EVENT_QUEUE *queue,
+                                     OSSL_EVENT **event)
+{
+    OSSL_TIME now = ossl_time_now();
+    OSSL_EVENT *e;
+
+    /* Check for expired timer based events and convert them to now events */
+    while ((e = ossl_pqueue_OSSL_EVENT_peek(queue->timed_events)) != NULL
+           && ossl_time_compare(e->when, now) <= 0) {
+        e = ossl_pqueue_OSSL_EVENT_pop(queue->timed_events);
+        if (!ossl_pqueue_OSSL_EVENT_push(queue->now_events, e, &e->ref)) {
+            e->queue = NULL;
+            return 0;
+        }
+    }
+
+    /*
+     * Get next event from the now queue.
+     * The pop returns NULL when there is none.
+     */
+    *event = ossl_pqueue_OSSL_EVENT_pop(queue->now_events);
+    return 1;
+}