lib: Move hashtable from lib to unicast

The hashtable is only used for forwarding tables in the unicast
IPCP. This moves the generic hashtable out of the library into the
unicast IPCP to prepare a more tailored implementation specific to
routing tables containing address lists.

Signed-off-by: Dimitri Staessens <dimitri@ouroboros.rocks>
Signed-off-by: Sander Vrijders <sander@ouroboros.rocks>

1 files changed, 222 insertions, 0 deletions

diff --git a/src/ipcpd/unicast/pol/hashtable.c b/src/ipcpd/unicast/pol/hashtable.c
new file mode 100644
index 00000000..596219f3
--- /dev/null
+++ b/src/ipcpd/unicast/pol/hashtable.c
@@ -0,0 +1,222 @@
+/*
+ * Ouroboros - Copyright (C) 2016 - 2020
+ *
+ * Hash table with integer keys with separate chaining on collisions
+ *
+ *    Dimitri Staessens <dimitri.staessens@ugent.be>
+ *    Sander Vrijders   <sander.vrijders@ugent.be>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * 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., http://www.fsf.org/about/contact/.
+ */
+
+#if defined(__linux__) || defined(__CYGWIN__)
+#define _DEFAULT_SOURCE
+#endif
+
+#include <ouroboros/list.h>
+#include <ouroboros/errno.h>
+#include <ouroboros/hash.h>
+
+#include "hashtable.h"
+
+#include <assert.h>
+#include <string.h>
+
+struct htable_entry {
+        struct list_head next;
+        uint64_t         key;
+        void *           val;
+        size_t           len;
+};
+
+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++)
+                list_head_init(&(tmp->buckets[i]));
+
+        return tmp;
+}
+
+void htable_destroy(struct htable * table)
+{
+        assert(table);
+        assert(table->buckets);
+
+        htable_flush(table);
+        free(table->buckets);
+        free(table);
+}
+
+void htable_flush(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);
+                        list_del(&entry->next);
+                        free(entry->val);
+                        free(entry);
+                }
+        }
+}
+
+static uint64_t hash(uint64_t key)
+{
+        void *   res;
+        uint64_t ret;
+        uint8_t  keys[4];
+
+        memcpy(keys, &key, 4);
+
+        mem_hash(HASH_MD5, &res, keys, 4);
+
+        ret = (* (uint64_t *) res);
+
+        free(res);
+
+        return ret;
+}
+
+static uint64_t calc_key(struct htable * table,
+                         uint64_t        key)
+{
+        if (table->hash_key)
+                key = hash(key);
+
+        return (key & (table->buckets_size - 1));
+}
+
+int htable_insert(struct htable * table,
+                  uint64_t        key,
+                  void *          val,
+                  size_t          len)
+{
+        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;
+        entry->len = len;
+        list_head_init(&entry->next);
+
+        list_add(&entry->next, &(table->buckets[lookup_key]));
+
+        return 0;
+}
+
+int htable_lookup(struct htable * table,
+                  uint64_t        key,
+                  void **         val,
+                  size_t *        len)
+{
+        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) {
+                        *val = entry->val;
+                        *len = entry->len;
+                        return 0;
+                }
+        }
+
+        return -1;
+}
+
+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;
+}