source: mainline/uspace/lib/nic/src/nic_addr_db.c

/*
 * Copyright (c) 2011 Radim Vansa
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 * - The name of the author may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/**
 * @addtogroup libnic
 * @{
 */
/**
 * @file
 * @brief Generic hash-set based database of addresses
 */

#include "nic_addr_db.h"
#include <assert.h>
#include <stdlib.h>
#include <stdbool.h>
#include <errno.h>
#include <mem.h>
#include <member.h>
#include <adt/hash_table.h>
#include <macros.h>
#include <stdint.h>

/**
 * Helper structure for keeping the address in the hash set.
 */
typedef struct nic_addr_entry {
        ht_link_t link;
        size_t hash;
        uint8_t len;
        uint8_t addr[];
} nic_addr_entry_t;

/*
 * Hash table helper functions
 */
typedef struct {
        size_t hash;
        size_t len;
        const uint8_t *addr;
} addr_key_t;

static bool nic_addr_key_equal(const void *key_arg, size_t hash, const ht_link_t *item)
{
        const addr_key_t *key = key_arg;
        nic_addr_entry_t *entry = member_to_inst(item, nic_addr_entry_t, link);
        return entry->hash == hash && memcmp(entry->addr, key->addr, entry->len) == 0;
}

static size_t addr_hash(size_t len, const uint8_t *addr)
{
        size_t hash = 0;

        for (size_t i = 0; i < len; ++i) {
                hash = (hash << 5) ^ addr[i];
        }

        return hash;
}

static size_t nic_addr_key_hash(const void *k)
{
        const addr_key_t *key = k;
        return key->hash ? key->hash : addr_hash(key->len, key->addr);
}

static size_t nic_addr_hash(const ht_link_t *item)
{
        nic_addr_entry_t *entry = member_to_inst(item, nic_addr_entry_t, link);
        return entry->hash;
}

static void nic_addr_removed(ht_link_t *item)
{
        nic_addr_entry_t *entry = member_to_inst(item, nic_addr_entry_t, link);
        free(entry);
}

static const hash_table_ops_t set_ops = {
        .hash = nic_addr_hash,
        .key_hash = nic_addr_key_hash,
        .key_equal = nic_addr_key_equal,
        .equal = NULL,
        .remove_callback = nic_addr_removed
};

/**
 * Initialize the database
 *
 * @param[in,out]       db                      Uninitialized storage
 * @param[in]           addr_len        Size of addresses in the db
 *
 * @return EOK          If successfully initialized
 * @return EINVAL       If the address length is too big
 * @return ENOMEM       If there was not enough memory to initialize the storage
 */
errno_t nic_addr_db_init(nic_addr_db_t *db, size_t addr_len)
{
        assert(db);

        if (addr_len > UCHAR_MAX)
                return EINVAL;

        if (!hash_table_create(&db->set, 0, 0, &set_ops))
                return ENOMEM;

        db->addr_len = addr_len;
        return EOK;
}

/**
 * Remove all records from the DB
 *
 * @param db
 */
void nic_addr_db_clear(nic_addr_db_t *db)
{
        assert(db);
        hash_table_clear(&db->set);
}

/**
 * Free the memory used by db, including all records...
 *
 * @param       db
 */
void nic_addr_db_destroy(nic_addr_db_t *db)
{
        assert(db);
        hash_table_destroy(&db->set);
}

/**
 * Insert an address to the db
 *
 * @param       db
 * @param       addr    Inserted address. Length is implicitly concluded from the
 *                                      db's address length.
 *
 * @return EOK          If the address was inserted
 * @return ENOMEM       If there was not enough memory
 * @return EEXIST       If this address already is in the db
 */
errno_t nic_addr_db_insert(nic_addr_db_t *db, const uint8_t *addr)
{
        assert(db && addr);

        addr_key_t key = {
                .len = db->addr_len,
                .addr = addr,
                .hash = addr_hash(db->addr_len, addr),
        };

        if (hash_table_find(&db->set, &key))
                return EEXIST;

        nic_addr_entry_t *entry = malloc(offsetof(nic_addr_entry_t, addr) + db->addr_len);
        if (entry == NULL)
                return ENOMEM;

        entry->len = (uint8_t) db->addr_len;
        memcpy(entry->addr, addr, db->addr_len);
        entry->hash = key.hash;

        hash_table_insert(&db->set, &entry->link);
        return EOK;
}

/**
 * Remove the address from the db
 *
 * @param       db
 * @param       addr    Removed address.
 *
 * @return EOK          If the address was removed
 * @return ENOENT       If there is no address
 */
errno_t nic_addr_db_remove(nic_addr_db_t *db, const uint8_t *addr)
{
        assert(db && addr);

        addr_key_t key = {
                .len = db->addr_len,
                .addr = addr
        };

        if (hash_table_remove(&db->set, &key))
                return EOK;
        else
                return ENOENT;
}

/**
 * Test if the address is contained in the db
 *
 * @param       db
 * @param       addr    Tested addresss
 *
 * @return true if the address is in the db, false otherwise
 */
bool nic_addr_db_contains(const nic_addr_db_t *db, const uint8_t *addr)
{
        assert(db && addr);

        addr_key_t key = {
                .len = db->addr_len,
                .addr = addr
        };

        return 0 != hash_table_find(&db->set, &key);
}

/**
 * Helper structure for nic_addr_db_foreach
 */
typedef struct {
        void (*func)(const uint8_t *, void *);
        void *arg;
} nic_addr_db_fe_arg_t;

/**
 * Helper function for nic_addr_db_foreach
 */
static bool nic_addr_db_fe_helper(ht_link_t *item, void *arg)
{
        nic_addr_db_fe_arg_t *hs = (nic_addr_db_fe_arg_t *) arg;
        nic_addr_entry_t *entry = member_to_inst(item, nic_addr_entry_t, link);
        hs->func(entry->addr, hs->arg);
        return true;
}

/**
 * Executes a user-defined function on all addresses in the DB. The function
 * must not change the addresses.
 *
 * @param       db
 * @param       func    User-defined function
 * @param       arg             Custom argument passed to the function
 */
void nic_addr_db_foreach(const nic_addr_db_t *db,
    void (*func)(const uint8_t *, void *), void *arg)
{
        nic_addr_db_fe_arg_t hs = { .func = func, .arg = arg };
        hash_table_apply((hash_table_t *)&db->set, nic_addr_db_fe_helper, &hs);
}

/** @}
 */