t_bridge.c

#include <err.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>

#include <net/ethernet.h>
#include <net/if.h>
#if defined(__DragonFly__)
#include <net/bridge/if_bridgevar.h>
#elif defined(__FreeBSD__)
#include <net/if_bridgevar.h>
#endif
#include <sys/ioctl.h>
#include <sys/socket.h>
#include <sys/types.h>

int
create_socket(int domain)
{
	int s;

	if ((s = socket(domain, SOCK_DGRAM, 0)) == -1)
		err(1, "socket");

	return s;
}


char *
create_if(int s, const char *type)
{
	struct ifreq ifr;

	/* For the bridge creation request */
	memset(&ifr, 0, sizeof(ifr));
	snprintf(ifr.ifr_name, IF_NAMESIZE, "%s", type);

	if (ioctl(s, SIOCIFCREATE2, &ifr) < 0) {
		perror("SIOCIFCREATE2");
		return NULL;
	}

	printf("if=%s created\n", ifr.ifr_name);
	return strndup(ifr.ifr_name, IF_NAMESIZE);
}

int
destroy_if(int s, const char *ifname)
{
	struct ifreq ifr;

	memset(&ifr, 0, sizeof(ifr));
	snprintf(ifr.ifr_name, IF_NAMESIZE, "%s", ifname);

	if (ioctl(s, SIOCIFDESTROY, &ifr) < 0) {
		perror("SIOCIFDESTROY");
		return -1;
	}
	printf("if=%s destroyed\n", ifr.ifr_name);

	return 0;
}

int
add2bridge(int s, const char *bifname, const char *ifname)
{
	struct ifreq ifr;
	struct ifbreq ifbr;
	struct ifdrv ifd;
	int flags;

	memset(&ifbr, 0, sizeof(ifbr));
	memset(&ifr, 0, sizeof(ifr));
	memset(&ifd, 0, sizeof(ifd));

	snprintf(ifbr.ifbr_ifsname, IF_NAMESIZE, "%s", ifname);
	snprintf(ifr.ifr_name, IF_NAMESIZE, "%s", ifname);

	/* Set the interface UP */
	flags = IFF_UP;
	ifr.ifr_flags |= flags & 0xFFFF;
	ifr.ifr_flagshigh |= flags >> 16;
	if (ioctl(s, SIOCSIFFLAGS, &ifr) < 0) {
		perror("SIOCSIFFLAGS");
		return -1;
	}

#if 0
	/* Get bridge priority */
	snprintf(ifd.ifd_name, IF_NAMESIZE, "%s", bifname);
	ifd.ifd_cmd = BRDGGPRI;
	ifd.ifd_len = sizeof(ifbr);
	ifd.ifd_data = &ifbr;

	if (ioctl(s, SIOCGDRVSPEC, &ifd) < 0) {
		if (errno != EEXIST) {
			perror("SIOCGDRVSPEC");
			return -1;
		}
	}
#endif
	/* Add the tap to the bridge */
	memset(&ifd, 0, sizeof(ifd));
	snprintf(ifd.ifd_name, IF_NAMESIZE, "%s", bifname);
	ifd.ifd_cmd = BRDGADD;
	ifd.ifd_len = sizeof(ifbr);
	ifd.ifd_data = &ifbr;

	if (ioctl(s, SIOCSDRVSPEC, &ifd) < 0) {
		if (errno != EEXIST) {
			perror("SIOCSDRVSPEC");
			return -1;
		}
	}
	printf("Added %s to %s\n", ifname, bifname);
	return 0;
}

void
test(int domain)
{
	char *bif_name, *tif_name;
	char *dom_name;

	int s;

	bif_name = tif_name = NULL;

	switch(domain) {
	case PF_LOCAL:
		dom_name = strndup("PF_LOCAL", 12);
		break;
	case PF_INET:
		dom_name = strndup("PF_INET", 12);
		break;
	default:
		return;
	}

	printf("------ Trying with domain=%s\n", dom_name);
	s = create_socket(domain);
	free(dom_name);

	if ((bif_name = create_if(s, "bridge")) == NULL)
		errx(1, "Failed to create bridge interface");
	if ((tif_name = create_if(s, "tap")) == NULL) {
		destroy_if(s, tif_name);
		errx(1, "Failed to create tap interface");
	}

	/* Add to the bridge */
	if (add2bridge(s, bif_name, tif_name) == -1)
		goto cleanup;

cleanup:
	/* Cleanup the interfaces created */
	destroy_if(s, bif_name);
	destroy_if(s, tif_name);

	if (bif_name)
		free(bif_name);
	if (tif_name)
		free(tif_name);
	close(s);

}
int
main(int argc, char *argv[])
{
	test(PF_LOCAL);
	test(PF_INET);

	return 0;
}