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Quite good implementation of NAT

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This commit is contained in:
Michal Zima 2010-02-22 14:55:18 +01:00
parent 3d8d8ace2a
commit f9f2bd501b
2 changed files with 184 additions and 0 deletions
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135
src/nat.c Normal file
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/*
* 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/>.
*/
#include <stdio.h>
#include <stdlib.h> /* malloc */
#include <time.h> /* time */
#include "radixtree.h"
struct s_radixtree_nat6 {
struct s_ipv6_addr ipv6;
struct s_ipv4_addr ipv4;
unsigned short port_src;
unsigned short port_dst;
} __attribute__ ((__packed__));
struct s_radixtree_nat4 {
struct s_ipv4_addr addr;
unsigned short port_src;
unsigned short port_dst;
unsigned char zeros; /* unused space */
} __attribute__ ((__packed__));
radixtree_t *nat6_tcp, *nat6_udp, *nat6_icmp,
*nat4_tcp, *nat4_udp, *nat4_icmp;
void nat_init()
{
nat6_tcp = radixtree_create();
nat6_udp = radixtree_create();
nat6_icmp = radixtree_create();
nat4_tcp = radixtree_create();
nat4_udp = radixtree_create();
nat4_icmp = radixtree_create();
}
void nat_quit()
{
/* 128 + 16 + 32 + 16 = 198 / 6 = 33 */
radixtree_destroy(&nat6_tcp, 33);
radixtree_destroy(&nat6_udp, 33);
radixtree_destroy(&nat6_icmp, 33);
/* 32 + 16 + 16 + 8 = 72 / 6 = 12 */
radixtree_destroy(&nat4_tcp, 12);
radixtree_destroy(&nat4_udp, 12);
radixtree_destroy(&nat4_icmp, 12);
}
struct s_nat *nat_out(radixtree_t *nat_proto6, radixtree_t *nat_proto4,
struct s_ipv6_addr ipv6_src, struct s_ipv6_addr ipv6_dst,
unsigned short port_src, unsigned short port_dst)
{
radixtree_t *result, *connection;
/* create structure to search in the tree */
struct s_radixtree_nat6 radixsearch6;
radixsearch6.ipv6 = ipv6_src;
radixsearch6.ipv4 = ipv6_to_ipv4(&ipv6_dst);
radixsearch6.port_src = port_src;
radixsearch6.port_dst = port_dst;
if ((result = radixtree_lookup(nat_proto6, radixtree_outgoing_chunker, &radixsearch6)) == NULL) {
if ((connection = (struct s_nat *) malloc(sizeof(struct s_nat))) == NULL) {
fprintf(stderr, "[Error] Lack of free memory\n");
return NULL;
}
connection->ipv6 = ipv6_src;
connection->ipv4 = radixsearch6.ipv4;
connection->ipv6_port_src = port_src;
connection->ipv4_port_dst = port_dst;
result->last_packet = time(NULL);
/* generate some outgoing port */
srand((unsigned int) time(NULL));
do {
/* return port from range 1024 - 65535 */
connection->ipv4_port_src = (rand() % 64511) + 1024;
result = radixtree_lookup(nat_proto6, radixtree_outgoing_chunker, &radixsearch6);
} while (result != NULL);
/* save this connection to the NAT table (to *both* of them) */
struct s_radixtree_nat4 radixsearch4;
radixsearch4.addr = radixsearch6.ipv4;
radixsearch4.port_src = port_dst;
radixsearch4.port_dst = connection->ipv4_port_src;
radixsearch4.zeros = 0x0;
radixtree_insert(nat_proto6, radixtree_outgoing_chunker, &radixsearch6, connection);
radixtree_insert(nat_proto4, radixtree_incoming_chunker, &radixsearch4, connection);
return connection;
} else {
result->last_packet = time(NULL);
return result;
}
}
struct s_nat *nat_in(radixtree_t *nat_proto, struct s_ipv4_addr ipv4_src,
unsigned short port_src, unsigned short port_dst)
{
radixtree_t *result;
/* create structure to search in the tree */
struct s_radixtree_nat4 radixsearch;
radixsearch.addr = ipv4_src;
radixsearch.port_src = port_src;
radixsearch.port_dst = port_dst;
radixsearch.zeros = 0x0;
if ((result = radixtree_lookup(nat_proto, radixtree_outgoing_chunker, &radixsearch)) == NULL) {
return NULL;
} else {
result->last_packet = time(NULL);
return result;
}
}

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/*
* 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/>.
*/
#ifndef NAT_H
#define NAT_H
#include <time.h> /* time_t */
#include "ipv4.h" /* s_ipv4_addr */
#include "ipv6.h" /* s_ipv6_addr */
#include "radixtree.h" /* radixtree_t */
struct s_nat {
struct s_ipv6_addr ipv6;
struct s_ipv4_addr ipv4;
unsigned short ipv6_port_src;
unsigned short ipv4_port_src;
unsigned short ipv4_port_dst;
time_t last_packet; /* time of processing last packet of the connection */
};
extern radixtree_t *nat6_tcp, *nat6_udp, *nat6_icmp,
*nat4_tcp, *nat4_udp, *nat4_icmp;
void nat_init();
void nat_quit();
struct s_nat *nat_out(radixtree_t *nat_proto6, radixtree_t *nat_proto4,
struct s_ipv6_addr ipv6_src, struct s_ipv6_addr ipv6_dst,
unsigned short port_src, unsigned short port_dst);
struct s_nat *nat_in(radixtree_t *nat_proto, struct s_ipv4_addr ipv4_src,
unsigned short port_src, unsigned short port_dst);
#endif /* NAT_H */