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/* wmem_map.h
* Definitions for the Wireshark Memory Manager Hash Map
* Copyright 2014, Evan Huus <eapache@gmail.com>
*
* Wireshark - Network traffic analyzer
* By Gerald Combs <gerald@wireshark.org>
* Copyright 1998 Gerald Combs
*
* 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.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#ifndef __WMEM_MAP_H__
#define __WMEM_MAP_H__
#include <glib.h>
#include "wmem_core.h"
#ifdef __cplusplus
extern "C" {
#endif /* __cplusplus */
/** @addtogroup wmem
* @{
* @defgroup wmem-map Hash Map
*
* A hash map implementation on top of wmem. Provides insertion, deletion and
* lookup in expected amortized constant time. Uses universal hashing to map
* keys into buckets, and provides a generic strong hash function that makes
* it secure against algorithmic complexity attacks, and suitable for use
* even with untrusted data.
*
* @{
*/
struct _wmem_map_t;
typedef struct _wmem_map_t wmem_map_t;
/** Creates a map with the given allocator scope. When the scope is emptied,
* the map is fully destroyed. Items stored in it will not be freed unless they
* were allocated from the same scope. For details on the GHashFunc and
* GEqualFunc parameters, see the glib documentation at:
* https://developer.gnome.org/glib/unstable/glib-Hash-Tables.html
*
* If the keys are coming from untrusted data, do *not* use glib's default hash
* functions for strings, int64s or doubles. Wmem provides stronger equivalents
* below. Feel free to use the g_direct_hash, g_int_hash, and any of the
* g_*_equal functions though, as they should be safe.
*
* @param allocator The allocator scope with which to create the map.
* @param hash_func The hash function used to place inserted keys.
* @param eql_func The equality function used to compare inserted keys.
* @return The newly-allocated map.
*/
WS_DLL_PUBLIC
wmem_map_t *
wmem_map_new(wmem_allocator_t *allocator,
GHashFunc hash_func, GEqualFunc eql_func)
G_GNUC_MALLOC;
/** Inserts a value into the map.
*
* @param map The map to insert into.
* @param key The key to insert by.
* @param value The value to insert.
* @return The previous value stored at this key if any, or NULL.
*/
WS_DLL_PUBLIC
void *
wmem_map_insert(wmem_map_t *map, const void *key, void *value);
/** Lookup a value in the map.
*
* @param map The map to search in.
* @param key The key to lookup.
* @return The value stored at the key if any, or NULL.
*/
WS_DLL_PUBLIC
void *
wmem_map_lookup(wmem_map_t *map, const void *key);
/** Remove a value from the map. If no value is stored at that key, nothing
* happens.
*
* @param map The map to remove from.
* @param key The key of the value to remove.
* @return The (removed) value stored at the key if any, or NULL.
*/
WS_DLL_PUBLIC
void *
wmem_map_remove(wmem_map_t *map, const void *key);
/** Compute a strong hash value for an arbitrary sequence of bytes. Use of this
* hash value should be secure against algorithmic complexity attacks, even for
* short keys. The computation uses a random seed which is generated on wmem
* initialization, so the same key will hash to different values on different
* runs of the application.
*
* @param buf The buffer of bytes (does not have to be aligned).
* @param len The length of buf to use for the hash computation.
* @return The hash value.
*/
WS_DLL_PUBLIC
guint32
wmem_strong_hash(const guint8 *buf, const size_t len);
/** An implementation of GHashFunc using wmem_strong_hash. Prefer this over
* g_str_hash when the data comes from an untrusted source.
*/
WS_DLL_PUBLIC
guint
wmem_str_hash(gconstpointer key);
/** An implementation of GHashFunc using wmem_strong_hash. Prefer this over
* g_int64_hash when the data comes from an untrusted source.
*/
WS_DLL_PUBLIC
guint
wmem_int64_hash(gconstpointer key);
/** An implementation of GHashFunc using wmem_strong_hash. Prefer this over
* g_double_hash when the data comes from an untrusted source.
*/
WS_DLL_PUBLIC
guint
wmem_double_hash(gconstpointer key);
/** @}
* @} */
#ifdef __cplusplus
}
#endif /* __cplusplus */
#endif /* __WMEM_MAP_H__ */
/*
* Editor modelines - http://www.wireshark.org/tools/modelines.html
*
* Local variables:
* c-basic-offset: 4
* tab-width: 8
* indent-tabs-mode: nil
* End:
*
* vi: set shiftwidth=4 tabstop=8 expandtab:
* :indentSize=4:tabSize=8:noTabs=true:
*/
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