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/*
* Elastic Binary Trees - example of application to network list reduction
* (C) 2010 - Willy Tarreau <w@1wt.eu>
*
* 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 St, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/time.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <ebmbtree.h>
struct one_net {
struct ebmb_node eb_node;
struct in_addr addr; /* keep it after eb_node */
/* any other information related to this network could be stored here */
};
struct eb_root tree = EB_ROOT; /* EB_ROOT || EB_ROOT_UNIQUE */
/* Insert an address into the tree, after checking that it does not match
* another one. If it does, then only one is kept or they are merged in a
* larger network and the function recurses over itself. The address is in
* network byte order.
*/
void insert_net(unsigned addr, unsigned cidr)
{
unsigned mask;
struct ebmb_node *node;
struct one_net *net;
/* clear unexpected bits */
mask = cidr ? ((signed)-0x80000000) >> (cidr - 1) : 0;
mask = htonl(mask);
addr &= mask;
/* 1) check if the entry already exists or matches an existing one. If we
* get a match, we have to compare prefixes and keep the widest one.
*/
if ((node = ebmb_lookup_longest(&tree, &addr)) != NULL) {
if (node->node.pfx <= cidr)
return;
ebmb_delete(node);
free(node);
}
/* 2) check if we can merge this network with the one just below or above */
if (cidr) {
unsigned mask2, addr2;
mask2 = cidr ? ((unsigned)0x80000000U) >> (cidr - 1) : 0;
mask2 = htonl(mask2);
/* invert the bit corresponding to the mask */
addr2 = addr ^ mask2;
node = ebmb_lookup_prefix(&tree, &addr2, cidr);
if (node) {
/* we can merge both entries at cidr - 1 */
ebmb_delete(node);
free(ebmb_entry(node, struct one_net, eb_node));
addr &= addr2; /* clear varying bit */
cidr--;
/* recursively do the same above */
insert_net(addr, cidr);
return;
}
}
net = (struct one_net *)calloc(1, sizeof(*net));
net->addr.s_addr = addr;
net->eb_node.node.pfx = cidr;
ebmb_insert_prefix(&tree, &net->eb_node, sizeof(net->addr.s_addr));
/* 3) it is possible that this node covers other ones. All other ones
* will always be located just after this one, so let's walk right as
* long as we find some matches and kill them.
*/
node = ebmb_next(&net->eb_node);
while (node) {
net = ebmb_entry(node, struct one_net, eb_node);
if ((addr & mask) != (net->addr.s_addr & mask))
break;
node = ebmb_next(&net->eb_node);
ebmb_delete(&net->eb_node);
}
}
void read_nets_from_stdin()
{
struct in_addr addr;
char str[256];
char *slash;
int bits;
while (fgets(str, sizeof(str), stdin) != NULL) {
bits = 32;
slash = strchr(str, '/');
if (slash) {
*(slash++) = 0;
if (strchr(slash, '.') == NULL) {
bits = atoi(slash);
} else {
inet_aton(slash, &addr);
bits = htonl(addr.s_addr);
if (bits)
bits = 32 - flsnz(~bits);
}
}
inet_aton(str, &addr);
insert_net(addr.s_addr, bits);
}
}
void dump_nets()
{
struct ebmb_node *node = ebmb_first(&tree);
while (node) {
printf("%d.%d.%d.%d/%d\n",
node->key[0], node->key[1], node->key[2], node->key[3], node->node.pfx);
node = ebmb_next(node);
if (!node)
break;
}
}
int main(int argc, char **argv)
{
if (argc > 1) {
fprintf(stderr,
"Enter networks one per line in the form <net>[/<mask>]\n"
"The output will contain the smallest reduction of these nets.\n"
);
exit(1);
}
read_nets_from_stdin();
dump_nets();
return 0;
}
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