new file mode 100644
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+/* Minimized/hacked up from openvswitch lib/conntrack.c, which had this license
+ header: */
+/*
+ * Copyright (c) 2015-2019 Nicira, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+typedef __SIZE_TYPE__ size_t;
+#define NULL ((void *)0)
+#define false 0
+
+#define OBJECT_OFFSETOF(OBJECT, MEMBER)\
+ __builtin_offsetof(typeof(*(OBJECT)), MEMBER)
+
+#define OBJECT_CONTAINING(POINTER, OBJECT, MEMBER) \
+ ((typeof(OBJECT)) (void *) \
+ ((char *) (POINTER) - OBJECT_OFFSETOF(OBJECT, MEMBER)))
+
+#define ASSIGN_CONTAINER(OBJECT, POINTER, MEMBER) \
+ ((OBJECT) = OBJECT_CONTAINING(POINTER, OBJECT, MEMBER), (void) 0)
+
+#define INIT_CONTAINER(OBJECT, POINTER, MEMBER) \
+ ((OBJECT) = NULL, ASSIGN_CONTAINER(OBJECT, POINTER, MEMBER))
+
+#define HMAP_FOR_EACH_POP(NODE, MEMBER, HMAP) \
+ for (size_t bucket__ = 0; \
+ INIT_CONTAINER(NODE, hmap_pop_helper__(HMAP, &bucket__), MEMBER), \
+ (NODE != OBJECT_CONTAINING(NULL, NODE, MEMBER)) \
+ || ((NODE = NULL), false);)
+
+struct hmap {
+ struct hmap_node **buckets;
+ struct hmap_node *one;
+ size_t mask;
+ size_t n;
+};
+
+struct hmap_node {
+ size_t hash;
+ struct hmap_node *next;
+};
+
+static inline void hmap_remove(struct hmap *, struct hmap_node *);
+
+struct hmap_node *
+hmap_pop_helper__(struct hmap *hmap, size_t *bucket) {
+
+ for (; *bucket <= hmap->mask; (*bucket)++) {
+ struct hmap_node *node = hmap->buckets[*bucket];
+
+ if (node) {
+ hmap_remove(hmap, node);
+ return node;
+ }
+ }
+
+ return NULL;
+}
+
+static inline void
+hmap_remove(struct hmap *hmap, struct hmap_node *node)
+{
+ struct hmap_node **bucket = &hmap->buckets[node->hash & hmap->mask];
+ while (*bucket != node) {
+ bucket = &(*bucket)->next;
+ }
+ *bucket = node->next;
+ hmap->n--;
+}
+
+struct conntrack {
+ struct hmap zone_limits;
+};
+
+struct zone_limit {
+ struct hmap_node node;
+};
+
+void
+conntrack_destroy(struct conntrack *ct)
+{
+ struct zone_limit *zl;
+ HMAP_FOR_EACH_POP (zl, node, &ct->zone_limits) {
+ __builtin_free(zl);
+ }
+}