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shadowsocks-libev/libipset/bdd/basics.c

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/* -*- coding: utf-8 -*-
* ----------------------------------------------------------------------
* Copyright © 2010-2013, RedJack, LLC.
* All rights reserved.
*
* Please see the LICENSE.txt file in this distribution for license
* details.
* ----------------------------------------------------------------------
*/
#include <stdio.h>
#include <string.h>
#include <libcork/core.h>
#include "ipset/bdd/nodes.h"
#include "ipset/bits.h"
#include "ipset/logging.h"
void
ipset_node_fprint(FILE *stream, struct ipset_node *node)
{
fprintf(stream,
"nonterminal(x%u? " IPSET_NODE_ID_FORMAT
": " IPSET_NODE_ID_FORMAT ")",
node->variable,
IPSET_NODE_ID_VALUES(node->high),
IPSET_NODE_ID_VALUES(node->low));
}
static cork_hash
ipset_node_hash(void *user_data, const void *key)
{
const struct ipset_node *node = key;
/* Hash of "ipset_node" */
cork_hash hash = 0xf3b7dc44;
hash = cork_hash_variable(hash, node->variable);
hash = cork_hash_variable(hash, node->low);
hash = cork_hash_variable(hash, node->high);
return hash;
}
static bool
ipset_node_equals(void *user_data, const void *key1, const void *key2)
{
const struct ipset_node *node1 = key1;
const struct ipset_node *node2 = key2;
if (node1 == node2) {
return true;
}
return
(node1->variable == node2->variable) &&
(node1->low == node2->low) &&
(node1->high == node2->high);
}
/* The free list in an ipset_node_cache is represented by a
* singly-linked list of indices into the chunk array. Since the
* ipset_node instance is unused for nodes in the free list, we reuse
* the refcount field to store the "next" index. */
#define IPSET_NULL_INDEX ((ipset_variable) -1)
struct ipset_node_cache *
ipset_node_cache_new()
{
struct ipset_node_cache *cache = cork_new(struct ipset_node_cache);
cork_array_init(&cache->chunks);
cache->largest_index = 0;
cache->free_list = IPSET_NULL_INDEX;
cache->node_cache = cork_hash_table_new(0, 0);
cork_hash_table_set_hash
(cache->node_cache, (cork_hash_f) ipset_node_hash);
cork_hash_table_set_equals
(cache->node_cache, (cork_equals_f) ipset_node_equals);
return cache;
}
void
ipset_node_cache_free(struct ipset_node_cache *cache)
{
size_t i;
for (i = 0; i < cork_array_size(&cache->chunks); i++) {
free(cork_array_at(&cache->chunks, i));
}
cork_array_done(&cache->chunks);
cork_hash_table_free(cache->node_cache);
free(cache);
}
/**
* Returns the index of a new ipset_node instance.
*/
static ipset_value
ipset_node_cache_alloc_node(struct ipset_node_cache *cache)
{
if (cache->free_list == IPSET_NULL_INDEX) {
/* Nothing in the free list; need to allocate a new node. */
ipset_value next_index = cache->largest_index++;
ipset_value chunk_index = next_index >> IPSET_BDD_NODE_CACHE_BIT_SIZE;
if (chunk_index >= cork_array_size(&cache->chunks)) {
/* We've filled up all of the existing chunks, and need to
* create a new one. */
DEBUG(" (allocating chunk %zu)",
cork_array_size(&cache->chunks));
struct ipset_node *new_chunk = cork_calloc
(IPSET_BDD_NODE_CACHE_SIZE, sizeof(struct ipset_node));
cork_array_append(&cache->chunks, new_chunk);
}
return next_index;
} else {
/* Reuse a recently freed node. */
ipset_value next_index = cache->free_list;
struct ipset_node *node =
ipset_node_cache_get_nonterminal_by_index(cache, next_index);
cache->free_list = node->refcount;
return next_index;
}
}
ipset_node_id
ipset_node_incref(struct ipset_node_cache *cache, ipset_node_id node_id)
{
if (ipset_node_get_type(node_id) == IPSET_NONTERMINAL_NODE) {
struct ipset_node *node =
ipset_node_cache_get_nonterminal(cache, node_id);
DEBUG(" [incref " IPSET_NODE_ID_FORMAT "]",
IPSET_NODE_ID_VALUES(node_id));
node->refcount++;
}
return node_id;
}
void
ipset_node_decref(struct ipset_node_cache *cache, ipset_node_id node_id)
{
if (ipset_node_get_type(node_id) == IPSET_NONTERMINAL_NODE) {
struct ipset_node *node =
ipset_node_cache_get_nonterminal(cache, node_id);
DEBUG(" [decref " IPSET_NODE_ID_FORMAT "]",
IPSET_NODE_ID_VALUES(node_id));
if (--node->refcount == 0) {
DEBUG(" [free " IPSET_NODE_ID_FORMAT "]",
IPSET_NODE_ID_VALUES(node_id));
ipset_node_decref(cache, node->low);
ipset_node_decref(cache, node->high);
cork_hash_table_delete(cache->node_cache, node, NULL, NULL);
/* Add the node to the free list */
node->refcount = cache->free_list;
cache->free_list = ipset_nonterminal_value(node_id);
}
}
}
bool
ipset_node_cache_nodes_equal(const struct ipset_node_cache *cache1,
ipset_node_id node_id1,
const struct ipset_node_cache *cache2,
ipset_node_id node_id2)
{
struct ipset_node *node1;
struct ipset_node *node2;
if (ipset_node_get_type(node_id1) != ipset_node_get_type(node_id2)) {
return false;
}
if (ipset_node_get_type(node_id1) == IPSET_TERMINAL_NODE) {
return node_id1 == node_id2;
}
node1 = ipset_node_cache_get_nonterminal(cache1, node_id1);
node2 = ipset_node_cache_get_nonterminal(cache2, node_id2);
return
(node1->variable == node2->variable) &&
ipset_node_cache_nodes_equal(cache1, node1->low, cache2, node2->low) &&
ipset_node_cache_nodes_equal(cache1, node1->high, cache2, node2->high);
}
ipset_node_id
ipset_node_cache_nonterminal(struct ipset_node_cache *cache,
ipset_variable variable,
ipset_node_id low, ipset_node_id high)
{
/* Don't allow any nonterminals whose low and high subtrees are the
* same, since the nonterminal would be redundant. */
if (CORK_UNLIKELY(low == high)) {
DEBUG(" [ SKIP nonterminal(x%u? "
IPSET_NODE_ID_FORMAT ": " IPSET_NODE_ID_FORMAT ")]",
variable, IPSET_NODE_ID_VALUES(high), IPSET_NODE_ID_VALUES(low));
ipset_node_decref(cache, high);
return low;
}
/* Check to see if there's already a nonterminal with these contents
* in the cache. */
DEBUG(" [search nonterminal(x%u? "
IPSET_NODE_ID_FORMAT ": " IPSET_NODE_ID_FORMAT ")]",
variable, IPSET_NODE_ID_VALUES(high), IPSET_NODE_ID_VALUES(low));
struct ipset_node search_node;
search_node.variable = variable;
search_node.low = low;
search_node.high = high;
bool is_new;
struct cork_hash_table_entry *entry =
cork_hash_table_get_or_create
(cache->node_cache, &search_node, &is_new);
if (!is_new) {
/* There's already a node with these contents, so return its ID. */
ipset_node_id node_id = (uintptr_t) entry->value;
DEBUG(" [reuse " IPSET_NODE_ID_FORMAT "]",
IPSET_NODE_ID_VALUES(node_id));
ipset_node_incref(cache, node_id);
ipset_node_decref(cache, low);
ipset_node_decref(cache, high);
return node_id;
} else {
/* This node doesn't exist yet. Allocate a permanent copy of
* the node, add it to the cache, and then return its ID. */
ipset_value new_index = ipset_node_cache_alloc_node(cache);
ipset_node_id new_node_id = ipset_nonterminal_node_id(new_index);
struct ipset_node *real_node =
ipset_node_cache_get_nonterminal_by_index(cache, new_index);
real_node->refcount = 1;
real_node->variable = variable;
real_node->low = low;
real_node->high = high;
entry->key = real_node;
entry->value = (void *) (uintptr_t) new_node_id;
DEBUG(" [new " IPSET_NODE_ID_FORMAT "]",
IPSET_NODE_ID_VALUES(new_node_id));
return new_node_id;
}
}
bool
ipset_bool_array_assignment(const void *user_data, ipset_variable variable)
{
const bool *bool_array = (const bool *) user_data;
return bool_array[variable];
}
bool
ipset_bit_array_assignment(const void *user_data, ipset_variable variable)
{
return IPSET_BIT_GET(user_data, variable);
}
ipset_value
ipset_node_evaluate(const struct ipset_node_cache *cache, ipset_node_id node_id,
ipset_assignment_func assignment, const void *user_data)
{
ipset_node_id curr_node_id = node_id;
DEBUG("Evaluating BDD node " IPSET_NODE_ID_FORMAT,
IPSET_NODE_ID_VALUES(node_id));
/* As long as the current node is a nonterminal, we have to check
* the value of the current variable. */
while (ipset_node_get_type(curr_node_id) == IPSET_NONTERMINAL_NODE) {
/* We have to look up this variable in the assignment. */
struct ipset_node *node =
ipset_node_cache_get_nonterminal(cache, curr_node_id);
bool this_value = assignment(user_data, node->variable);
DEBUG("[%3u] Nonterminal " IPSET_NODE_ID_FORMAT,
node->variable, IPSET_NODE_ID_VALUES(curr_node_id));
DEBUG("[%3u] x%u = %s",
node->variable, node->variable, this_value? "TRUE": "FALSE");
if (this_value) {
/* This node's variable is true in the assignment vector, so
* trace down the high subtree. */
curr_node_id = node->high;
} else {
/* This node's variable is false in the assignment vector,
* so trace down the low subtree. */
curr_node_id = node->low;
}
}
/* Once we find a terminal node, we've got the final result. */
DEBUG("Evaluated result is %u", ipset_terminal_value(curr_node_id));
return ipset_terminal_value(curr_node_id);
}
/* A “fake” BDD node given by an assignment. */
struct ipset_fake_node {
ipset_variable current_var;
ipset_variable var_count;
ipset_assignment_func assignment;
const void *user_data;
ipset_value value;
};
/* A fake BDD node representing the terminal 0 value. */
static struct ipset_fake_node fake_terminal_0 = { 0, 0, NULL, 0, 0 };
/* We set elements in a map using the if-then-else (ITE) operator:
*
* new_set = new_element? new_value: old_set
*
* The below is a straight copy of the standard trinary APPLY from the BDD
* literature, but without the caching of the results. And also with the
* wrinkle that the F argument to ITE (i.e., new_element) is given by an
* assignment, and not by a BDD node. (This lets us skip constructing the BDD
* for the assignment, saving us a few cycles.)
*/
static ipset_node_id
ipset_apply_ite(struct ipset_node_cache *cache, struct ipset_fake_node *f,
ipset_value g, ipset_node_id h)
{
ipset_node_id h_low;
ipset_node_id h_high;
ipset_node_id result_low;
ipset_node_id result_high;
/* If F is a terminal, then we're in one of the following two
* cases:
*
* 1? G: H == G
* 0? G: H == H
*/
if (f->current_var == f->var_count) {
ipset_node_id result;
DEBUG("[%3u] F is terminal (value %u)", f->current_var, f->value);
if (f->value == 0) {
DEBUG("[%3u] 0? " IPSET_NODE_ID_FORMAT ": " IPSET_NODE_ID_FORMAT
" = " IPSET_NODE_ID_FORMAT,
f->current_var,
IPSET_NODE_ID_VALUES(ipset_terminal_node_id(g)),
IPSET_NODE_ID_VALUES(h), IPSET_NODE_ID_VALUES(h));
result = ipset_node_incref(cache, h);
} else {
result = ipset_terminal_node_id(g);
DEBUG("[%3u] 1? " IPSET_NODE_ID_FORMAT ": " IPSET_NODE_ID_FORMAT
" = " IPSET_NODE_ID_FORMAT,
f->current_var, IPSET_NODE_ID_VALUES(result),
IPSET_NODE_ID_VALUES(h), IPSET_NODE_ID_VALUES(result));
}
return result;
}
/* F? G: G == G */
if (h == ipset_terminal_node_id(g)) {
DEBUG("[%3u] F? " IPSET_NODE_ID_FORMAT ": " IPSET_NODE_ID_FORMAT
" = " IPSET_NODE_ID_FORMAT,
f->current_var, IPSET_NODE_ID_VALUES(h),
IPSET_NODE_ID_VALUES(h), IPSET_NODE_ID_VALUES(h));
return h;
}
/* From here to the end of the function, we know that F is a
* nonterminal. */
DEBUG("[%3u] F is nonterminal", f->current_var);
/* We're going to do two recursive calls, a “low” one and a “high” one. For
* each nonterminal that has the minimum variable number, we use its low and
* high pointers in the respective recursive call. For all other
* nonterminals, and for all terminals, we use the operand itself. */
if (ipset_node_get_type(h) == IPSET_NONTERMINAL_NODE) {
struct ipset_node *h_node =
ipset_node_cache_get_nonterminal(cache, h);
DEBUG("[%3u] H is nonterminal (variable %u)",
f->current_var, h_node->variable);
if (h_node->variable < f->current_var) {
/* var(F) > var(H), so we only recurse down the H branches. */
DEBUG("[%3u] Recursing only down H", f->current_var);
DEBUG("[%3u] Recursing high", f->current_var);
result_high = ipset_apply_ite(cache, f, g, h_node->high);
DEBUG("[%3u] Back from high recursion", f->current_var);
DEBUG("[%3u] Recursing low", f->current_var);
result_low = ipset_apply_ite(cache, f, g, h_node->low);
DEBUG("[%3u] Back from low recursion", f->current_var);
return ipset_node_cache_nonterminal
(cache, h_node->variable, result_low, result_high);
} else if (h_node->variable == f->current_var) {
/* var(F) == var(H), so we recurse down both branches. */
DEBUG("[%3u] Recursing down both F and H", f->current_var);
h_low = h_node->low;
h_high = h_node->high;
} else {
/* var(F) < var(H), so we only recurse down the F branches. */
DEBUG("[%3u] Recursing only down F", f->current_var);
h_low = h;
h_high = h;
}
} else {
/* H in nonterminal, so we only recurse down the F branches. */
DEBUG("[%3u] H is terminal (value %u)",
f->current_var, ipset_terminal_value(h));
DEBUG("[%3u] Recursing only down F", f->current_var);
h_low = h;
h_high = h;
}
/* F is a “fake” nonterminal node, since it comes from our assignment. One
* of its branches will be the 0 terminal, and the other will be the fake
* nonterminal for the next variable in the assignment. (Which one is low
* and which one is high depends on the value of the current variable in the
* assignment.) */
if (f->assignment(f->user_data, f->current_var)) {
/* The current variable is set in F. The low branch is terminal 0; the
* high branch is the next variable in F. */
DEBUG("[%3u] x[%u] is set", f->current_var, f->current_var);
DEBUG("[%3u] Recursing high", f->current_var);
f->current_var++;
result_high = ipset_apply_ite(cache, f, g, h_high);
f->current_var--;
DEBUG("[%3u] Back from high recursion: " IPSET_NODE_ID_FORMAT,
f->current_var, IPSET_NODE_ID_VALUES(result_high));
DEBUG("[%3u] Recursing low", f->current_var);
fake_terminal_0.current_var = f->var_count;
fake_terminal_0.var_count = f->var_count;
result_low = ipset_apply_ite(cache, &fake_terminal_0, g, h_low);
DEBUG("[%3u] Back from low recursion: " IPSET_NODE_ID_FORMAT,
f->current_var, IPSET_NODE_ID_VALUES(result_low));
} else {
/* The current variable is NOT set in F. The high branch is terminal 0;
* the low branch is the next variable in F. */
DEBUG("[%3u] x[%u] is NOT set", f->current_var, f->current_var);
DEBUG("[%3u] Recursing high", f->current_var);
fake_terminal_0.current_var = f->var_count;
fake_terminal_0.var_count = f->var_count;
result_high = ipset_apply_ite(cache, &fake_terminal_0, g, h_high);
DEBUG("[%3u] Back from high recursion: " IPSET_NODE_ID_FORMAT,
f->current_var, IPSET_NODE_ID_VALUES(result_high));
DEBUG("[%3u] Recursing low", f->current_var);
f->current_var++;
result_low = ipset_apply_ite(cache, f, g, h_low);
f->current_var--;
DEBUG("[%3u] Back from low recursion: " IPSET_NODE_ID_FORMAT,
f->current_var, IPSET_NODE_ID_VALUES(result_low));
}
return ipset_node_cache_nonterminal
(cache, f->current_var, result_low, result_high);
}
ipset_node_id
ipset_node_insert(struct ipset_node_cache *cache, ipset_node_id node,
ipset_assignment_func assignment, const void *user_data,
ipset_variable var_count, ipset_value value)
{
struct ipset_fake_node f = { 0, var_count, assignment, user_data, 1 };
DEBUG("Inserting new element");
return ipset_apply_ite(cache, &f, value, node);
}