introduce MAC address table support (selective bridging)

master
Harald Welte 8 months ago
parent 0e59b4607b
commit 995ac55d0e
  1. 2
      Makefile
  2. 78
      mac_table.c
  3. 21
      mac_table.h
  4. 35
      tr-bridge.c
  5. 13
      utils.c
  6. 2
      utils.h

@ -1,7 +1,7 @@
CFLAGS = -Wall -g
tr-bridge: tr-bridge.c utils.c
tr-bridge: tr-bridge.c utils.c mac_table.c
$(CC) $(CFLAGS) -o $@ $^
clean:

@ -0,0 +1,78 @@
#include <string.h>
#include <errno.h>
#include <stdio.h>
#include <errno.h>
#include "mac_table.h"
#include "utils.h"
bool mac_table_contains(struct mac_table *tbl, const uint8_t *addr)
{
unsigned int i;
for (i = 0; i < tbl->num_entries; i++) {
if (!memcmp(tbl->addr[i], addr, 6))
return true;
}
return false;
}
int mac_table_add(struct mac_table *tbl, const uint8_t *addr)
{
if (tbl->num_entries == MAC_TABLE_SIZE-1)
return -ENOSPC;
memcpy(tbl->addr[tbl->num_entries++], addr, 6);
return 0;
}
void mac_table_init(struct mac_table *tbl, const char *name)
{
memset(tbl, 0, sizeof(*tbl));
tbl->name = name;
}
int mac_table_read(struct mac_table *tbl, const char *fname)
{
FILE *f = fopen(fname, "r");
unsigned int num = 0;
char line[256];
if (!f) {
fprintf(stderr, "Cannot open mac table %s: %s\n", fname, strerror(errno));
return -errno;
}
printf("Reading MAC table %s from file %s...\n", tbl->name, fname);
while (fgets(line, sizeof(line), f)) {
uint8_t addr[6];
int rc;
if (line[strlen(line)-1] == '\n')
line[strlen(line)-1] = 0;
if (strlen(line) < 1)
continue;
/* skip comments */
if (line[0] == ';' || line[9] == '#')
continue;
rc = sscanf(line, "%02hhx:%02hhx:%02hhx:%02hhx:%02hhx:%02hhx",
&addr[0], &addr[1], &addr[2], &addr[3], &addr[4], &addr[5]);
if (rc != 6) {
fprintf(stderr, "%s: Cannot parse line '%s'\n", tbl->name, line);
continue;
}
printf("%s: Read MAC address %s\n", tbl->name, mac2str(addr));
mac_table_add(tbl, addr);
num++;
}
fclose(f);
return num;
}

@ -0,0 +1,21 @@
#pragma once
#include <stdint.h>
#include <stdbool.h>
#define MAC_TABLE_SIZE 64
struct mac_table {
const char *name;
uint8_t addr[MAC_TABLE_SIZE][6];
unsigned int num_entries;
};
static inline bool mac_table_empty(const struct mac_table *tbl)
{
return tbl->num_entries == 0;
}
void mac_table_init(struct mac_table *tbl, const char *name);
int mac_table_add(struct mac_table *tbl, const uint8_t *addr);
bool mac_table_contains(struct mac_table *tbl, const uint8_t *addr);
int mac_table_read(struct mac_table *tbl, const char *fname);

@ -8,6 +8,16 @@
* You need to call this program with two arguments:
* - first: the token ring device (e.g. 'tr0')
* - second: the ethernet device (e.g. 'eth0')
*
* Optionally, you may psecify with two additional arguments:
* - third: A file containing MAC addresses on TR side
* - fourth: A file containing MAC addresses on ETH side
*
* The file syntax is one MAC address per line in 01:02:03:04:05:06 format.
*
* If MAC address files are specified, the bridge will only pass frames for those
* addresses and drop all other frames. Please note that you need to specify the
* bit ordering _native_ to the respective side. So Eth order for Eth; TR order for TR.
*/
#include <stdint.h>
@ -29,6 +39,7 @@
#include <net/ethernet.h>
#include "utils.h"
#include "mac_table.h"
#define TR_ALEN 6
@ -46,9 +57,11 @@ struct tr_hdr {
struct bridge_state {
struct {
int socket;
struct mac_table mac_tbl;
} tr;
struct {
int socket;
struct mac_table mac_tbl;
} eth;
};
@ -188,7 +201,12 @@ static int eth2tr(struct bridge_state *bst)
memcpy(&trh.saddr, ethh->h_source, sizeof(trh.saddr));
osmo_revbytebits_buf(trh.saddr, TR_ALEN);
return write_tr(bst->tr.socket, &trh, buf + sizeof(*ethh), ethlen - sizeof(*ethh));
if (mac_table_empty(&bst->tr.mac_tbl) || mac_table_contains(&bst->tr.mac_tbl, trh.daddr))
return write_tr(bst->tr.socket, &trh, buf + sizeof(*ethh), ethlen - sizeof(*ethh));
else {
printf("TR<-ETH: Ignoring frame to unknown MAC %s\n", mac2str(trh.daddr));
return 0;
}
}
@ -237,7 +255,12 @@ static int tr2eth(struct bridge_state *bst)
osmo_revbytebits_buf(ethh.h_source, TR_ALEN);
ethh.h_proto = htons(ETH_P_802_2);
return write_eth(bst->eth.socket, &ethh, buf + sizeof(*trh), trlen - sizeof(*trh));
if (mac_table_empty(&bst->eth.mac_tbl) || mac_table_contains(&bst->eth.mac_tbl, ethh.h_dest))
return write_eth(bst->eth.socket, &ethh, buf + sizeof(*trh), trlen - sizeof(*trh));
else {
printf("TR->ETH: Ignoring frame to unknown MAC %s\n", mac2str(ethh.h_dest));
return 0;
}
}
@ -280,6 +303,9 @@ int main(int argc, char **argv)
struct bridge_state bst;
const char *tr_name, *eth_name;
mac_table_init(&bst.tr.mac_tbl, "TR");
mac_table_init(&bst.eth.mac_tbl, "ETH");
if (argc < 3) {
fprintf(stderr, "You must specify both TR and ETH device\n");
exit(2);
@ -288,6 +314,11 @@ int main(int argc, char **argv)
tr_name = argv[1];
eth_name = argv[2];
if (argc >= 5) {
mac_table_read(&bst.tr.mac_tbl, argv[3]);
mac_table_read(&bst.eth.mac_tbl, argv[4]);
}
bst.tr.socket = open_packet_socket_for_netdev(tr_name, htons(ETH_P_ALL));
if (bst.tr.socket < 0) {
fprintf(stderr, "Error opening TR\n");

@ -1,4 +1,7 @@
#include <stdint.h>
#include <stdio.h>
#include "utils.h"
/* Copied from libosmocore.git src/bits.c */
@ -38,3 +41,13 @@ void osmo_revbytebits_buf(uint8_t *buf, int len)
for (i = 0; i < len; i++)
buf[i] = flip_table[buf[i]];
}
const char *mac2str(const uint8_t *addr)
{
static char buf[32];
snprintf(buf, sizeof(buf), "%02x:%02x:%02x:%02x:%02x:%02x",
addr[0], addr[1], addr[2], addr[3], addr[4], addr[5]);
return buf;
}

@ -1,3 +1,5 @@
#pragma once
void osmo_revbytebits_buf(uint8_t *buf, int len);
const char *mac2str(const uint8_t *addr);

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