bridge.c

/*
 * (C) 2011-2014 Luigi Rizzo, Matteo Landi
 *
 * BSD license
 *
 * A netmap client to bridge two network interfaces
 * (or one interface and the host stack).
 *
 * $FreeBSD$
 */

#include <stdio.h>
#define NETMAP_WITH_LIBS
#include <net/netmap_user.h>
#include <sys/poll.h>

int verbose = 0;

static int do_abort = 0;
static int zerocopy = 1; /* enable zerocopy if possible */
static void *pkt;

static void
sigint_h(int sig)
{
	(void)sig;	/* UNUSED */
	do_abort = 1;
	signal(SIGINT, SIG_DFL);
}

static void
hexdump(char *desc, void *buf, int len) {
	int i;
	unsigned char buff[17];
	unsigned char *pc = (unsigned char *) buf;

	if (desc != NULL) {
		printf("%s:\n", desc);
	}

	for (i = 0; i < len; i++) {
		if ((i % 16) == 0) {
			if (i != 0) {
				printf("  %s\n", buff);
			}

			printf("  %04x ", i);;
		}	

		printf(" %02x", pc[i]);

		if ((pc[i] < 0x20) || (pc[i] > 0x7e)) {
			buff[i % 16] = '.';
		} else {
			buff[i % 16] = pc[i];
		}

		buff[(i % 16) + 1] = '\0';
	}

	while ((i % 16) != 0) {
		printf("   ");
		i++;
	}

	printf("  %s\n", buff);
}

static void
print_packet(char *buf, int len, int tx) {
	bzero(pkt, sizeof(pkt));
	memcpy(pkt, (void*)buf, len);
	if (tx) {
		printf("------TX(copied)------\n");
	} else {
		printf("------RX------\n");
	}
	hexdump(NULL, pkt, len);
}

/*
 * how many packets on this set of queues ?
 */
int
pkt_queued(struct nm_desc *d, int tx)
{
	u_int i, tot = 0;

	if (tx) {
		for (i = d->first_tx_ring; i <= d->last_tx_ring; i++) {
			tot += nm_ring_space(NETMAP_TXRING(d->nifp, i));
		}
	} else {
		for (i = d->first_rx_ring; i <= d->last_rx_ring; i++) {
			tot += nm_ring_space(NETMAP_RXRING(d->nifp, i));
		}
	}
	return tot;
}

#define BUF_OFFSET(buf, x, t) (*((t *) (buf + x)))

static int
filter(char* buf, int len) {
	//ICMP
	if (len >= 34 
		&& (BUF_OFFSET(buf, 12, uint16_t) == 0x0008)
		&& (BUF_OFFSET(buf, 23, uint8_t) == 0x1)
	) { 
		int request = BUF_OFFSET(buf, 34, uint8_t);
		
		printf("ICMP %s \n", request ? "request" : "reply" );
		return 1;
	}


	// ARP
	if (len >= 14 &&
		BUF_OFFSET(buf, 12, uint16_t) == 0x0608) {
		
		char *request = (BUF_OFFSET(buf, 21, uint8_t) == 0x1 ? "request" : "reply");
		printf("ARP %s \n", request);
		return 1;
	
	}

	printf("Unknown protocol\n");
	return 0;
}


/*
 * move up to 'limit' pkts from rxring to txring swapping buffers.
 */
static int
process_rings(struct netmap_ring *rxring, struct netmap_ring *txring,
	      u_int limit, const char *msg, const char *if_src, const char *if_dst)
{
	u_int j, k, m = 0;

	/* print a warning if any of the ring flags is set (e.g. NM_REINIT) */
	if (rxring->flags || txring->flags)
		D("%s rxflags %x txflags %x",
			msg, rxring->flags, txring->flags);
	j = rxring->cur; /* RX */
	k = txring->cur; /* TX */
	m = nm_ring_space(rxring);
	if (m < limit)
		limit = m;
	m = nm_ring_space(txring);
	if (m < limit)
		limit = m;
	m = limit;
	while (limit-- > 0) {
		struct netmap_slot *rs = &rxring->slot[j];
		struct netmap_slot *ts = &txring->slot[k];

		/* swap packets */
		if (ts->buf_idx < 2 || rs->buf_idx < 2) {
			RD(5, "wrong index rx[%d] = %d  -> tx[%d] = %d",
				j, rs->buf_idx, k, ts->buf_idx);
			sleep(2);
		}
		/* copy the packet length. */
		if (rs->len > rxring->nr_buf_size) {
			RD(5, "wrong len %d rx[%d] -> tx[%d]", rs->len, j, k);
			rs->len = 0;
		} else if (verbose > 1) {
			D("%s send len %d rx[%d] -> tx[%d]", msg, rs->len, j, k);
		}
		ts->len = rs->len;
		if (zerocopy) {
			uint32_t pkt = ts->buf_idx;
			ts->buf_idx = rs->buf_idx;
			rs->buf_idx = pkt;
			/* report the buffer change. */
			ts->flags |= NS_BUF_CHANGED;
			rs->flags |= NS_BUF_CHANGED;
			/* copy the NS_MOREFRAG */
			rs->flags = (rs->flags & ~NS_MOREFRAG) | (ts->flags & NS_MOREFRAG);
			printf("%s -> %s -- ", if_src, if_dst);
			char *txbuf = NETMAP_BUF(txring, ts->buf_idx);
			filter(txbuf, ts->len);
			if (verbose > 0) {
				print_packet(txbuf, ts->len, 1);
			}
		} else {
			printf("%s -> %s -- ", if_src, if_dst);
			char *rxbuf = NETMAP_BUF(rxring, rs->buf_idx);
			filter(rxbuf, rs->len);
			if (verbose > 0)
				print_packet(rxbuf, rs->len, 0);
			char *txbuf = NETMAP_BUF(txring, ts->buf_idx);
			nm_pkt_copy(rxbuf, txbuf, ts->len);
			if (verbose > 0) 
				print_packet(txbuf, ts->len, 1);
		}
		j = nm_ring_next(rxring, j);
		k = nm_ring_next(txring, k);
	}
	rxring->head = rxring->cur = j;
	txring->head = txring->cur = k;
	if (verbose && m > 0)
		D("%s sent %d packets to %p", msg, m, txring);

	return (m);
}

/* move packts from src to destination */
static int
move(struct nm_desc *src, struct nm_desc *dst, u_int limit, const char *if_src, const char* if_dst)
{
	struct netmap_ring *txring, *rxring;
	u_int m = 0, si = src->first_rx_ring, di = dst->first_tx_ring;
	const char *msg = (src->req.nr_flags == NR_REG_SW) ?
		"host->net" : "net->host";
	while (si <= src->last_rx_ring && di <= dst->last_tx_ring) {
		rxring = NETMAP_RXRING(src->nifp, si);
		txring = NETMAP_TXRING(dst->nifp, di);
		ND("txring %p rxring %p", txring, rxring);
		if (nm_ring_empty(rxring)) {
			si++;
			continue;
		}
		if (nm_ring_empty(txring)) {
			di++;
			continue;
		}
		m += process_rings(rxring, txring, limit, msg, if_src, if_dst);
	}

	return (m);
}


static void
usage(void)
{
	fprintf(stderr,
		"netmap bridge program: forward packets between two "
			"network interfaces\n"
		"    usage(1): bridge [-v] [-i ifa] [-i ifb] [-b burst] "
			"[-w wait_time] [-L]\n"
		"    usage(2): bridge [-v] [-w wait_time] [-L] "
			"[ifa [ifb [burst]]]\n"
		"\n"
		"    ifa and ifb are specified using the nm_open() syntax.\n"
		"    When ifb is missing (or is equal to ifa), bridge will\n"
		"    forward between between ifa and the host stack if -L\n"
		"    is not specified, otherwise loopback traffic on ifa.\n"
		"\n"
		"    example: bridge -w 10 -i netmap:eth3 -i netmap:eth1\n"
		);
	exit(1);
}

/*
 * bridge [-v] if1 [if2]
 *
 * If only one name, or the two interfaces are the same,
 * bridges userland and the adapter. Otherwise bridge
 * two intefaces.
 */
int
main(int argc, char **argv)
{
	struct pollfd pollfd[2];
	int ch;
	u_int burst = 1024, wait_link = 4;
	struct nm_desc *pa = NULL, *pb = NULL;
	char *ifa = NULL, *ifb = NULL;
	char ifabuf[64] = { 0 };
	int loopback = 0;

	fprintf(stderr, "%s built %s %s\n\n", argv[0], __DATE__, __TIME__);

	while ((ch = getopt(argc, argv, "hb:ci:vw:L")) != -1) {
		switch (ch) {
		default:
			D("bad option %c %s", ch, optarg);
			/* fallthrough */
		case 'h':
			usage();
			break;
		case 'b':	/* burst */
			burst = atoi(optarg);
			break;
		case 'i':	/* interface */
			if (ifa == NULL)
				ifa = optarg;
			else if (ifb == NULL)
				ifb = optarg;
			else
				D("%s ignored, already have 2 interfaces",
					optarg);
			break;
		case 'c':
			zerocopy = 0; /* do not zerocopy */
			break;
		case 'v':
			verbose++;
			break;
		case 'w':
			wait_link = atoi(optarg);
			break;
		case 'L':
			loopback = 1;
			break;
		}

	}

	argc -= optind;
	argv += optind;

	if (argc > 0)
		ifa = argv[0];
	if (argc > 1)
		ifb = argv[1];
	if (argc > 2)
		burst = atoi(argv[2]);
	if (!ifb)
		ifb = ifa;
	if (!ifa) {
		D("missing interface");
		usage();
	}
	if (burst < 1 || burst > 8192) {
		D("invalid burst %d, set to 1024", burst);
		burst = 1024;
	}
	if (wait_link > 100) {
		D("invalid wait_link %d, set to 4", wait_link);
		wait_link = 4;
	}
	if (!strcmp(ifa, ifb)) {
		if (!loopback) {
			D("same interface, endpoint 0 goes to host");
			snprintf(ifabuf, sizeof(ifabuf) - 1, "%s^", ifa);
			ifa = ifabuf;
		} else {
			D("same interface, loopbacking traffic");
		}
	} else {
		/* two different interfaces. Take all rings on if1 */
	}
	pa = nm_open(ifa, NULL, 0, NULL);
	if (pa == NULL) {
		D("cannot open %s", ifa);
		return (1);
	}
	/* try to reuse the mmap() of the first interface, if possible */
	pb = nm_open(ifb, NULL, NM_OPEN_NO_MMAP, pa);
	if (pb == NULL) {
		D("cannot open %s", ifb);
		nm_close(pa);
		return (1);
	}
	zerocopy = zerocopy && (pa->mem == pb->mem);
	D("------- zerocopy %ssupported", zerocopy ? "" : "NOT ");

	pkt = malloc(1500);

	/* setup poll(2) array */
	memset(pollfd, 0, sizeof(pollfd));
	pollfd[0].fd = pa->fd;
	pollfd[1].fd = pb->fd;

	D("Wait %d secs for link to come up...", wait_link);
	sleep(wait_link);
	D("Ready to go, %s 0x%x/%d <-> %s 0x%x/%d.",
		pa->req.nr_name, pa->first_rx_ring, pa->req.nr_rx_rings,
		pb->req.nr_name, pb->first_rx_ring, pb->req.nr_rx_rings);

	/* main loop */
	signal(SIGINT, sigint_h);
	while (!do_abort) {
		int n0, n1, ret;
		pollfd[0].events = pollfd[1].events = 0;
		pollfd[0].revents = pollfd[1].revents = 0;
		n0 = pkt_queued(pa, 0);
		n1 = pkt_queued(pb, 0);
#if defined(_WIN32) || defined(BUSYWAIT)
		if (n0) {
			ioctl(pollfd[1].fd, NIOCTXSYNC, NULL);
			pollfd[1].revents = POLLOUT;
		} else {
			ioctl(pollfd[0].fd, NIOCRXSYNC, NULL);
		}
		if (n1) {
			ioctl(pollfd[0].fd, NIOCTXSYNC, NULL);
			pollfd[0].revents = POLLOUT;
		} else {
			ioctl(pollfd[1].fd, NIOCRXSYNC, NULL);
		}
		ret = 1;
#else
		if (n0)
			pollfd[1].events |= POLLOUT;
		else
			pollfd[0].events |= POLLIN;
		if (n1)
			pollfd[0].events |= POLLOUT;
		else
			pollfd[1].events |= POLLIN;

		/* poll() also cause kernel to txsync/rxsync the NICs */
		ret = poll(pollfd, 2, 2500);
#endif /* defined(_WIN32) || defined(BUSYWAIT) */
		if (ret <= 0 || verbose)
		    D("poll %s [0(%s)] ev %x %x rx %d@%d tx %d,"
			     " [1(%s)] ev %x %x rx %d@%d tx %d",
				ret <= 0 ? "timeout" : "ok",
				ifa,
				pollfd[0].events,
				pollfd[0].revents,
				pkt_queued(pa, 0),
				NETMAP_RXRING(pa->nifp, pa->cur_rx_ring)->cur,
				pkt_queued(pa, 1),
				ifb,
				pollfd[1].events,
				pollfd[1].revents,
				pkt_queued(pb, 0),
				NETMAP_RXRING(pb->nifp, pb->cur_rx_ring)->cur,
				pkt_queued(pb, 1)
			);
		if (ret < 0)
			continue;
		if (pollfd[0].revents & POLLERR) {
			struct netmap_ring *rx = NETMAP_RXRING(pa->nifp, pa->cur_rx_ring);
			D("error on fd0, rx [%d,%d,%d)",
				rx->head, rx->cur, rx->tail);
		}
		if (pollfd[1].revents & POLLERR) {
			struct netmap_ring *rx = NETMAP_RXRING(pb->nifp, pb->cur_rx_ring);
			D("error on fd1, rx [%d,%d,%d)",
				rx->head, rx->cur, rx->tail);
		}
		if (pollfd[0].revents & POLLOUT)
			move(pb, pa, burst, ifb, ifa); /* move from b to a */

		if (pollfd[1].revents & POLLOUT)
			move(pa, pb, burst, ifa, ifb); /* move from a to b */

		/* We don't need ioctl(NIOCTXSYNC) on the two file descriptors here,
		 * kernel will txsync on next poll(). */
	}
	nm_close(pb);
	nm_close(pa);

	return (0);
}