Add a simple hash table implementation.

src/Makefile.am

@@ -5,7 +5,7 @@ sbin_PROGRAMS = tincd tincctl sptps_test
 EXTRA_DIST = linux bsd solaris cygwin mingw openssl gcrypt
 
 tincd_SOURCES = \
-	utils.c getopt.c getopt1.c list.c splay_tree.c dropin.c fake-getaddrinfo.c fake-getnameinfo.c \
+	utils.c getopt.c getopt1.c list.c splay_tree.c dropin.c fake-getaddrinfo.c fake-getnameinfo.c hash.c \
 	buffer.c conf.c connection.c control.c edge.c graph.c logger.c meta.c net.c net_packet.c net_setup.c \
 	net_socket.c netutl.c node.c process.c protocol.c protocol_auth.c protocol_edge.c protocol_misc.c \
 	protocol_key.c protocol_subnet.c route.c sptps.c subnet.c subnet_parse.c tincd.c \
@@ -46,7 +46,7 @@ INCLUDES = @INCLUDES@ -I$(top_builddir)
 noinst_HEADERS = \
 	xalloc.h utils.h getopt.h list.h splay_tree.h dropin.h fake-getaddrinfo.h fake-getnameinfo.h fake-gai-errnos.h ipv6.h ipv4.h ethernet.h \
 	buffer.h conf.h connection.h control.h control_common.h device.h edge.h graph.h info.h logger.h meta.h net.h netutl.h node.h process.h \
-	protocol.h route.h subnet.h sptps.h tincctl.h top.h bsd/tunemu.h
+	protocol.h route.h subnet.h sptps.h tincctl.h top.h bsd/tunemu.h hash.h
 
 nodist_noinst_HEADERS = \
 	cipher.h crypto.h ecdh.h ecdsa.h digest.h prf.h rsa.h ecdsagen.h rsagen.h

src/hash.c

@@ -0,0 +1,103 @@
+/*
+    hash.c -- hash table management
+    Copyright (C) 2012 Guus Sliepen <guus@tinc-vpn.org>
+
+    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.
+*/
+
+#include "system.h"
+
+#include "hash.h"
+#include "xalloc.h"
+
+/* Generic hash function */
+
+static uint32_t hash_function(const void *p, size_t len) {
+	const uint8_t *q = p;
+	uint32_t hash = 0;
+	while(len > 0) {
+		for(int i = len > 4 ? 4 : len; --i;)
+			hash += q[i] << (8 * i);
+		hash *= 0x9e370001UL; // Golden ratio prime.
+		len -= 4;
+	}
+	return hash;
+}
+
+/* Map 32 bits int onto 0..n-1, without throwing away too many bits if n is 2^8 or 2^16 */
+
+static uint32_t modulo(uint32_t hash, size_t n) {
+	if(n == 0x100)
+		return (hash >> 24) ^ ((hash >> 16) & 0xff) ^ ((hash >> 8) & 0xff) ^ (hash & 0xff);
+	else if(n == 0x10000)
+		return (hash >> 16) ^ (hash & 0xffff);
+	else
+		return hash % n;
+}
+
+/* (De)allocation */
+
+hash_t *hash_alloc(size_t n, size_t size) {
+	hash_t *hash = xmalloc_and_zero(sizeof *hash);
+	hash->n = n;
+	hash->size = size;
+	hash->keys = xmalloc(hash->n * hash->size);
+	hash->values = xmalloc_and_zero(hash->n * sizeof *hash->values);
+	return hash;
+}
+
+void hash_free(hash_t *hash) {
+	free(hash->keys);
+	free(hash->values);
+	free(hash);
+}
+
+/* Searching and inserting */
+
+void hash_insert(hash_t *hash, const void *key, const void *value) {
+	uint32_t i = modulo(hash_function(key, hash->size), hash->n);
+	memcpy(hash->keys + i * hash->size, key, hash->size);
+	hash->values[i] = value;
+}
+
+void *hash_search(const hash_t *hash, const void *key) {
+	uint32_t i = modulo(hash_function(key, hash->size), hash->n);
+	if(hash->values[i] && !memcmp(key, hash->keys + i * hash->size, hash->size)) {
+		return (void *)hash->values[i];
+	}
+	return NULL;
+}
+
+void *hash_search_or_insert(hash_t *hash, const void *key, const void *value) {
+	uint32_t i = modulo(hash_function(key, hash->size), hash->n);
+	if(hash->values[i] && !memcmp(key, hash->keys + i * hash->size, hash->size))
+		return (void *)hash->values[i];
+	memcpy(hash->keys + i * hash->size, key, hash->size);
+	hash->values[i] = value;
+	return NULL;
+}
+
+/* Utility functions */
+
+void hash_clear(hash_t *hash) {
+	memset(hash->values, 0, hash->n * sizeof *hash->values);
+}
+
+void hash_resize(hash_t *hash, size_t n) {
+	hash->keys = xrealloc(hash->keys, n * hash->size);
+	hash->values = xrealloc(hash->values, n * sizeof *hash->values);
+	if(n > hash->n)
+		memset(hash->values + hash->n, 0, (n - hash->n) * sizeof *hash->values);
+}

src/hash.h

@@ -0,0 +1,41 @@
+/*
+    hash.h -- header file for hash.c
+    Copyright (C) 2012 Guus Sliepen <guus@tinc-vpn.org>
+
+    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 __TINC_HASH_H__
+#define __TINC_HASH_H__
+
+typedef struct hash_t {
+	size_t n;
+	size_t size;
+	char *keys;
+	const void **values;
+} hash_t;
+
+extern hash_t *hash_alloc(size_t n, size_t size) __attribute__ ((__malloc__));
+extern void hash_free(hash_t *);
+
+extern void hash_insert(hash_t *, const void *key, const void *value);
+
+extern void *hash_search(const hash_t *, const void *key);
+extern void *hash_search_or_insert(hash_t *, const void *key, const void *value);
+
+extern void hash_clear(hash_t *);
+extern void hash_resize(hash_t *, size_t n);
+
+#endif							/* __TINC_HASH_H__ */