Implementation of Radix tree for NAT

src/radixtree.c

@@ -0,0 +1,198 @@
+/*
+ *  WrapSix
+ *  Copyright (C) 2008-2010  Michal Zima <xhire@mujmalysvet.cz>
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU Affero General Public License as
+ *  published by the Free Software Foundation, either version 3 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 Affero General Public License for more details.
+ *
+ *  You should have received a copy of the GNU Affero General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+radixtree_t *radixtree_create()
+{
+	radixtree_t *radixtree;
+
+	if ((radixtree = (radixtree_t *) malloc(sizeof(radixtree_t))) == NULL) {
+		fprintf(stderr, "[Error] Lack of free memory\n");
+		return NULL;
+	}
+	memset(radixtree, 0, sizeof(radixtree_t));
+	radixtree->count = 0;
+
+	return radixtree;
+}
+
+void radixtree_destroy(radixtree_t *t, unsigned char depth)
+{
+	unsigned char i;
+
+	for (i = 0; i < ARRAY_SIZE; i++) {
+		if (depth != 1 && t->array[i] != NULL) {
+			radixtree_destroy(t->array[i], depth - 1);
+		} else if (depth == 1) {
+			free(t->array[i]);
+		}
+	}
+
+	free(t);
+}
+
+void radixtree_insert(radixtree_t *root,
+		      unsigned char *(chunker)(void *data, unsigned char *count),
+		      void *search_data, void *data)
+{
+	radixtree_t *tmp;
+	unsigned char i, chunk_count;
+	unsigned char *chunks;
+
+	chunks = chunker(search_data, &chunk_count);
+
+	tmp = root;
+	tmp->count++;
+
+	for (i = 0; i < chunk_count; i++) {
+		unsigned char id;
+
+		id = chunk[i];
+
+		if (i == chunk_count - 1) {
+			tmp->array[id] = data;
+			return;
+		}
+
+		if (tmp->array[id] == NULL) {
+			tmp->array[id] = radixtree_create();
+		}
+
+		tmp = tmp->array[id];
+		tmp->count++;
+	}
+}
+
+void radixtree_delete(radixtree_t *root,
+		      unsigned char *(chunker)(void *data, unsigned char *count),
+		      void *data)
+{
+	radixtree_t *tmp,
+		    *next;
+	unsigned char i, chunk_count;
+	unsigned char *chunks;
+
+	chunks = chunker(data, &chunk_count);
+
+	tmp = root;
+	tmp->count--;
+
+	for (i = 0; i < chunk_count; i++) {
+		unsigned char id;
+
+		id = chunk[i];
+
+		/* already deleted? may cause data inconsistency! */
+		if (tmp->array[id] == NULL) {
+			return;
+		}
+
+		if (i == chunk_count - 1) {
+			if (tmp->count == 0) {
+				free(tmp);
+			} else {
+				tmp->array[id] = NULL;
+			}
+
+			/**
+			 * now you *have to* call free on data too
+			 * but probably not here...
+			 **/
+
+			return;
+		}
+
+		next = tmp->array[id];
+
+		/* if it is the last entry in this tree branch */
+		if (next->count == 1) {
+			tmp->array[id] = NULL;
+		}
+
+		if (i != 0 && tmp->count == 0) {
+			free(tmp);
+		}
+
+		tmp = next;
+		tmp->count--;
+	}
+}
+
+radixtree_t *radixtree_lookup(radixtree_t *root,
+			      unsigned char *(chunker)(void *data, unsigned char *count),
+			      void *data)
+{
+	radixtree_t *tmp;
+	unsigned char i, chunk_count;
+	unsigned char *chunks;
+
+	chunks = chunker(data, &chunk_count);
+
+	tmp = root;
+
+	for (i = 0; i < chunk_count; i++) {
+		unsigned char id;
+
+		id = chunk[i];
+
+		if (i == chunk_count - 1) {
+			return tmp->array[id];
+		}
+
+		if (tmp->array[id] == NULL) {
+			return NULL;
+		}
+
+		tmp = tmp->array[id];
+	}
+}
+
+unsigned char *radixtree_outgoing_chunker(void *data, unsigned char *count)
+{
+	short i;
+	unsigned char counter;
+
+	counter = 198 / 6;
+	memcpy(count, &counter, sizeof(unsigned char));
+
+	unsigned char chunks[counter];
+
+	/* 128 + 16 + 32 + 16 - 6 = 192 */
+	for (i = 192, counter = 0; i >= 0; i -= 6, counter++) {
+		chunks[counter] = (*data >> i) & 63;	/* 63 == 0011 1111 */
+	}
+
+	return chunks;
+}
+
+unsigned char *radixtree_incoming_chunker(void *data, unsigned char *count)
+{
+	short i;
+	unsigned char counter;
+
+	counter = 72 / 6;
+	memcpy(count, &counter, sizeof(unsigned char));
+
+	unsigned char chunks[counter];
+
+	/* 32 + 16 + 16 + 8 - 6 = 66 */
+	for (i = 66, counter = 0; i >= 0; i -= 6, counter++) {
+		chunks[counter] = (*data >> i) & 63;	/* 63 == 0011 1111 */
+	}
+
+	return chunks;
+}

src/radixtree.h

@@ -0,0 +1,39 @@
+/*
+ *  WrapSix
+ *  Copyright (C) 2008-2010  Michal Zima <xhire@mujmalysvet.cz>
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU Affero General Public License as
+ *  published by the Free Software Foundation, either version 3 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 Affero General Public License for more details.
+ *
+ *  You should have received a copy of the GNU Affero General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#define CHUNK_SIZE	6
+#define ARRAY_SIZE	64	/* 2 ^ CHUNK_SIZE */
+
+typedef struct radixtree {
+	void *array[ARRAY_SIZE];
+	unsigned int count;
+} radixtree_t;
+
+radixtree_t *radixtree_create();
+void radixtree_destroy(radixtree_t *t, unsigned char depth);
+void radixtree_insert(radixtree_t *root,
+		      unsigned char *(chunker)(void *data, unsigned char *count),
+		      void *search_data, void *data);
+void radixtree_delete(radixtree_t *root,
+		      unsigned char *(chunker)(void *data, unsigned char *count),
+		      void *data);
+radixtree_t *radixtree_lookup(radixtree_t *root,
+		      unsigned char *(chunker)(void *data, unsigned char *count),
+		      void *data);
+unsigned char *radixtree_outgoing_chunker(void *data, unsigned char *count);
+unsigned char *radixtree_incoming_chunker(void *data, unsigned char *count);