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/*
* This file is part of RTRlib.
*
* This file is subject to the terms and conditions of the MIT license.
* See the file LICENSE in the top level directory for more details.
*
* Website: http://rtrlib.realmv6.org/
*/
#include "trie_private.h"
#include "rtrlib/lib/alloc_utils_private.h"
#include "rtrlib/lib/ip_private.h"
#include <assert.h>
#include <stdlib.h>
static void swap_nodes(struct trie_node *a, struct trie_node *b)
{
struct trie_node tmp;
tmp.prefix = a->prefix;
tmp.len = a->len;
tmp.data = a->data;
a->prefix = b->prefix;
a->len = b->len;
a->data = b->data;
b->prefix = tmp.prefix;
b->len = tmp.len;
b->data = tmp.data;
}
enum child_node_rel { LEFT, RIGHT };
static void add_child_node(struct trie_node *parent, struct trie_node *child, enum child_node_rel rel)
{
assert(rel == LEFT || rel == RIGHT);
if (rel == LEFT)
parent->lchild = child;
else
parent->rchild = child;
child->parent = parent;
}
static inline bool is_left_child(const struct lrtr_ip_addr *addr, unsigned int lvl)
{
/* A node must be inserted as left child if bit <lvl> of the IP address
* is 0 otherwise as right child
*/
return lrtr_ip_addr_is_zero(lrtr_ip_addr_get_bits(addr, lvl, 1));
}
void trie_insert(struct trie_node *root, struct trie_node *new, const unsigned int lvl)
{
if (new->len < root->len)
swap_nodes(root, new);
if (is_left_child(&new->prefix, lvl)) {
if (!root->lchild)
return add_child_node(root, new, LEFT);
return trie_insert(root->lchild, new, lvl + 1);
}
if (!root->rchild)
return add_child_node(root, new, RIGHT);
trie_insert(root->rchild, new, lvl + 1);
}
struct trie_node *trie_lookup(const struct trie_node *root, const struct lrtr_ip_addr *prefix, const uint8_t mask_len,
unsigned int *lvl)
{
while (root) {
if (root->len <= mask_len && lrtr_ip_addr_equal(lrtr_ip_addr_get_bits(&root->prefix, 0, root->len),
lrtr_ip_addr_get_bits(prefix, 0, root->len)))
return (struct trie_node *)root;
if (is_left_child(prefix, *lvl))
root = root->lchild;
else
root = root->rchild;
(*lvl)++;
}
return NULL;
}
struct trie_node *trie_lookup_exact(struct trie_node *root_node, const struct lrtr_ip_addr *prefix,
const uint8_t mask_len, unsigned int *lvl, bool *found)
{
*found = false;
while (root_node) {
if (*lvl > 0 && root_node->len > mask_len) {
(*lvl)--;
return root_node->parent;
}
if (root_node->len == mask_len && lrtr_ip_addr_equal(root_node->prefix, *prefix)) {
*found = true;
return root_node;
}
if (is_left_child(prefix, *lvl)) {
if (!root_node->lchild)
return root_node;
root_node = root_node->lchild;
} else {
if (!root_node->rchild)
return root_node;
root_node = root_node->rchild;
}
(*lvl)++;
}
return NULL;
}
static void deref_node(struct trie_node *n)
{
if (!n->parent)
return;
if (n->parent->lchild == n) {
n->parent->lchild = NULL;
return;
}
n->parent->rchild = NULL;
}
static inline bool prefix_is_same(const struct trie_node *n, const struct lrtr_ip_addr *p, uint8_t mask_len)
{
return n->len == mask_len && lrtr_ip_addr_equal(n->prefix, *p);
}
static void replace_node_data(struct trie_node *a, struct trie_node *b)
{
a->prefix = b->prefix;
a->len = b->len;
a->data = b->data;
}
struct trie_node *trie_remove(struct trie_node *root, const struct lrtr_ip_addr *prefix, const uint8_t mask_len,
const unsigned int lvl)
{
/* If the node has no children we can simply remove it
* If the node has children, we swap the node with the child that
* has the smaller prefix length and drop the child.
*/
if (prefix_is_same(root, prefix, mask_len)) {
void *tmp;
if (trie_is_leaf(root)) {
deref_node(root);
return root;
}
/* swap with the left child and drop the child */
if (root->lchild && (!root->rchild || root->lchild->len < root->rchild->len)) {
tmp = root->data;
replace_node_data(root, root->lchild);
root->lchild->data = tmp;
return trie_remove(root->lchild, &root->lchild->prefix, root->lchild->len, lvl + 1);
}
/* swap with the right child and drop the child */
tmp = root->data;
replace_node_data(root, root->rchild);
root->rchild->data = tmp;
return trie_remove(root->rchild, &root->rchild->prefix, root->rchild->len, lvl + 1);
}
if (is_left_child(prefix, lvl)) {
if (!root->lchild)
return NULL;
return trie_remove(root->lchild, prefix, mask_len, lvl + 1);
}
if (!root->rchild)
return NULL;
return trie_remove(root->rchild, prefix, mask_len, lvl + 1);
}
static int append_node_to_array(struct trie_node ***ary, unsigned int *len, struct trie_node *n)
{
struct trie_node **new;
new = lrtr_realloc(*ary, *len * sizeof(n));
if (!new)
return -1;
*ary = new;
(*ary)[*len - 1] = n;
return 0;
}
int trie_get_children(const struct trie_node *root_node, struct trie_node ***array, unsigned int *len)
{
if (root_node->lchild) {
*len += 1;
if (append_node_to_array(array, len, root_node->lchild))
goto err;
if (trie_get_children(root_node->lchild, array, len) == -1)
goto err;
}
if (root_node->rchild) {
*len += 1;
if (append_node_to_array(array, len, root_node->rchild))
goto err;
if (trie_get_children(root_node->rchild, array, len) == -1)
goto err;
}
return 0;
err:
lrtr_free(*array);
return -1;
}
inline bool trie_is_leaf(const struct trie_node *node)
{
return !node->lchild && !node->rchild;
}
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