lib, ipcpd: Add hashtable and PDU Forwarding Function

This adds a hash table that takes 64-bit integers as key and uses
separate chaining on collision. It also adds the PDU Forwarding
Function, which the Flow Manager can use to lookup the fd towards the
next hop. Routing policies will add/update/remove entries in the PFF.

1 files changed, 188 insertions, 0 deletions

diff --git a/src/lib/hashtable.c b/src/lib/hashtable.c
new file mode 100644
index 00000000..cc73d6a0
--- /dev/null
+++ b/src/lib/hashtable.c
@@ -0,0 +1,188 @@
+/*
+ * Ouroboros - Copyright (C) 2016
+ *
+ * Hash table with separate chaining on collisions
+ *
+ *    Sander Vrijders <sander.vrijders@intec.ugent.be>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#include <ouroboros/config.h>
+#include <ouroboros/hashtable.h>
+#include <ouroboros/list.h>
+#include <ouroboros/errno.h>
+
+#include <assert.h>
+
+struct htable_entry {
+        struct list_head next;
+        uint64_t         key;
+        void *           val;
+};
+
+struct htable {
+        struct list_head * buckets;
+        bool               hash_key;
+        uint64_t           buckets_size;
+};
+
+struct htable * htable_create(uint64_t buckets, bool hash_key)
+{
+        struct htable * tmp;
+        unsigned int i;
+
+        if (buckets == 0)
+                return NULL;
+
+        buckets--;
+        buckets |= buckets >> 1;
+        buckets |= buckets >> 2;
+        buckets |= buckets >> 4;
+        buckets |= buckets >> 8;
+        buckets |= buckets >> 16;
+        buckets |= buckets >> 32;
+        buckets++;
+
+        tmp = malloc(sizeof(*tmp));
+        if (tmp == NULL)
+                return NULL;
+
+        tmp->hash_key = hash_key;
+        tmp->buckets_size = buckets;
+
+        tmp->buckets = malloc(buckets * sizeof(*tmp->buckets));
+        if (tmp->buckets == NULL) {
+                free(tmp);
+                return NULL;
+        }
+
+        for (i = 0; i < buckets; i++)
+                INIT_LIST_HEAD(&(tmp->buckets[i]));
+
+        return tmp;
+}
+
+int htable_destroy(struct htable * table)
+{
+        unsigned int          i;
+        struct list_head *    pos = NULL;
+        struct list_head *    n = NULL;
+        struct htable_entry * entry;
+
+        assert(table);
+
+        for (i = 0; i < table->buckets_size; i++) {
+                list_for_each_safe(pos, n, &(table->buckets[i])) {
+                        entry = list_entry(pos, struct htable_entry, next);
+                        free(entry->val);
+                        free(entry);
+                }
+        }
+
+        free(table->buckets);
+        free(table);
+
+        return 0;
+}
+
+static uint64_t hash(uint64_t x)
+{
+        x = (x ^ (x >> 30)) * UINT64_C(0xbf58476d1ce4e5b9);
+        x = (x ^ (x >> 27)) * UINT64_C(0x94d049bb133111eb);
+        x = x ^ (x >> 31);
+
+        return x;
+}
+
+static uint64_t calc_key(struct htable * table, uint64_t key)
+{
+        if (table->hash_key == true)
+                key = hash(key);
+
+        return (key & (table->buckets_size - 1));
+}
+
+int htable_insert(struct htable * table, uint64_t key, void * val)
+{
+        struct htable_entry * entry;
+        uint64_t              lookup_key;
+        struct list_head *    pos = NULL;
+
+        assert(table);
+
+        lookup_key = calc_key(table, key);
+
+        list_for_each(pos, &(table->buckets[lookup_key])) {
+                entry = list_entry(pos, struct htable_entry, next);
+                if (entry->key == key)
+                        return -1;
+        }
+
+        entry = malloc(sizeof(*entry));
+        if (entry == NULL)
+                return -ENOMEM;
+
+        entry->key = key;
+        entry->val = val;
+        INIT_LIST_HEAD(&entry->next);
+
+        list_add(&entry->next, &(table->buckets[lookup_key]));
+
+        return 0;
+}
+
+void * htable_lookup(struct htable * table, uint64_t key)
+{
+        struct htable_entry * entry;
+        struct list_head *    pos = NULL;
+        uint64_t              lookup_key;
+
+        assert(table);
+
+        lookup_key = calc_key(table, key);
+
+        list_for_each(pos, &(table->buckets[lookup_key])) {
+                entry = list_entry(pos, struct htable_entry, next);
+                if (entry->key == key)
+                        return entry->val;
+        }
+
+        return NULL;
+}
+
+int htable_delete(struct htable * table, uint64_t key)
+{
+        struct htable_entry * entry;
+        uint64_t              lookup_key;
+        struct list_head *    pos = NULL;
+        struct list_head *    n = NULL;
+
+        assert(table);
+
+        lookup_key = calc_key(table, key);
+
+        list_for_each_safe(pos, n, &(table->buckets[lookup_key])) {
+                entry = list_entry(pos, struct htable_entry, next);
+                if (entry->key == key) {
+                        list_del(&entry->next);
+                        free(entry->val);
+                        free(entry);
+                        return 0;
+                }
+        }
+
+        return -1;
+}