mirror of
https://gitlab.nic.cz/labs/bird.git
synced 2024-11-13 22:58:42 +00:00
126 lines
2.5 KiB
C
126 lines
2.5 KiB
C
/*
|
|
* Filters: utility functions
|
|
*
|
|
* Copyright 1998 Pavel Machek <pavel@ucw.cz>
|
|
*
|
|
* Can be freely distributed and used under the terms of the GNU GPL.
|
|
*/
|
|
|
|
#include <stdio.h>
|
|
#include <fcntl.h>
|
|
#include <unistd.h>
|
|
#include <sys/signal.h>
|
|
#include <setjmp.h>
|
|
|
|
#include "nest/bird.h"
|
|
#include "lib/lists.h"
|
|
#include "lib/resource.h"
|
|
#include "lib/socket.h"
|
|
#include "nest/route.h"
|
|
#include "nest/protocol.h"
|
|
#include "nest/iface.h"
|
|
#include "conf/conf.h"
|
|
#include "filter/filter.h"
|
|
|
|
/* Finds n-th item in list linked by right. Trashes pointers in right. */
|
|
static struct f_tree *
|
|
find_nth(struct f_tree *from, int nth)
|
|
{
|
|
struct f_tree *pivot;
|
|
int lcount = 0, rcount = 0;
|
|
struct f_tree *left, *right, *next;
|
|
|
|
pivot = from;
|
|
|
|
left = right = NULL;
|
|
next = from->right;
|
|
while (from = next) {
|
|
next = from->right;
|
|
if (val_compare(pivot->from, from->from)==1) {
|
|
from->right = left;
|
|
left = from;
|
|
lcount++;
|
|
} else {
|
|
from->right = right;
|
|
right = from;
|
|
rcount++;
|
|
}
|
|
}
|
|
if (lcount == nth)
|
|
return pivot;
|
|
if (lcount < nth)
|
|
return find_nth(right, nth-lcount-1);
|
|
return find_nth(left, nth);
|
|
}
|
|
|
|
/* Gets list linked by left, finds its median, trashes pointers in right */
|
|
static struct f_tree *
|
|
find_median(struct f_tree *from)
|
|
{
|
|
struct f_tree *t = from;
|
|
int cnt = 0;
|
|
|
|
if (!from)
|
|
return NULL;
|
|
do {
|
|
t->right = t->left;
|
|
cnt++;
|
|
} while (t = t->left);
|
|
return find_nth(from, cnt/2);
|
|
}
|
|
|
|
struct f_tree *
|
|
find_tree(struct f_tree *t, struct f_val val)
|
|
{
|
|
if (!t)
|
|
return 0;
|
|
if ((val_compare(t->from, val) != 1) &&
|
|
(val_compare(t->to, val) != -1))
|
|
return t;
|
|
if (val_compare(t->from, val) == -1)
|
|
return find_tree(t->right, val);
|
|
else
|
|
return find_tree(t->left, val);
|
|
}
|
|
|
|
/* Gets list linked by left */
|
|
struct f_tree *
|
|
build_tree(struct f_tree *from)
|
|
{
|
|
struct f_tree *median, *t = from, *next, *left = NULL, *right = NULL;
|
|
|
|
median = find_median(from);
|
|
if (!median)
|
|
return NULL;
|
|
|
|
do {
|
|
next = t->left;
|
|
if (t == median)
|
|
continue;
|
|
|
|
if (val_compare(median->from, t->from)==1) {
|
|
t->left = left;
|
|
left = t;
|
|
} else {
|
|
t->left = right;
|
|
right = t;
|
|
}
|
|
} while(t = next);
|
|
|
|
median->left = build_tree(left);
|
|
median->right = build_tree(right);
|
|
return median;
|
|
}
|
|
|
|
struct f_tree *
|
|
f_new_tree(void)
|
|
{
|
|
struct f_tree * ret;
|
|
ret = cfg_alloc(sizeof(struct f_tree));
|
|
ret->left = ret->right = NULL;
|
|
ret->from.type = ret->to.type = T_VOID;
|
|
ret->from.val.i = ret->to.val.i = 0;
|
|
ret->data = NULL;
|
|
return ret;
|
|
}
|