1 /* Copyright (c) 2008 The Board of Trustees of The Leland Stanford
4 * We are making the OpenFlow specification and associated documentation
5 * (Software) available for public use and benefit with the expectation
6 * that others will use, modify and enhance the Software and contribute
7 * those enhancements back to the community. However, since we would
8 * like to make the Software available for broadest use, with as few
9 * restrictions as possible permission is hereby granted, free of
10 * charge, to any person obtaining a copy of this Software to deal in
11 * the Software under the copyrights without restriction, including
12 * without limitation the rights to use, copy, modify, merge, publish,
13 * distribute, sublicense, and/or sell copies of the Software, and to
14 * permit persons to whom the Software is furnished to do so, subject to
15 * the following conditions:
17 * The above copyright notice and this permission notice shall be
18 * included in all copies or substantial portions of the Software.
20 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
21 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
22 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
23 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
24 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
25 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
26 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
29 * The name and trademarks of copyright holder(s) may NOT be used in
30 * advertising or publicity pertaining to the Software or any
31 * derivatives without specific, written prior permission.
39 #include <arpa/inet.h>
41 #include <linux/types.h>
42 #include <linux/ethtool.h>
43 #include <linux/sockios.h>
44 #include <sys/types.h>
45 #include <sys/ioctl.h>
46 #include <sys/socket.h>
47 #include <netpacket/packet.h>
48 #include <net/ethernet.h>
50 #include <net/if_arp.h>
51 #include <net/if_packet.h>
52 #include <net/route.h>
53 #include <netinet/in.h>
59 #include "fatal-signal.h"
63 #include "poll-loop.h"
64 #include "socket-util.h"
66 #define THIS_MODULE VLM_netdev
74 uint8_t etheraddr[ETH_ADDR_LEN];
79 int save_flags; /* Initial device flags. */
80 int changed_flags; /* Flags that we changed. */
83 static struct list netdev_list = LIST_INITIALIZER(&netdev_list);
85 /* An AF_INET socket (used for ioctl operations). */
86 static int af_inet_sock = -1;
88 static void init_netdev(void);
89 static int restore_flags(struct netdev *netdev);
90 static int get_flags(const struct netdev *, int *flagsp);
91 static int set_flags(struct netdev *, int flags);
93 /* Obtains the IPv6 address for 'name' into 'in6'. */
95 get_ipv6_address(const char *name, struct in6_addr *in6)
100 file = fopen("/proc/net/if_inet6", "r");
102 /* This most likely indicates that the host doesn't have IPv6 support,
103 * so it's not really a failure condition.*/
108 while (fgets(line, sizeof line, file)) {
109 uint8_t *s6 = in6->s6_addr;
113 if (sscanf(line, " "X8 X8 X8 X8 X8 X8 X8 X8 X8 X8 X8 X8 X8 X8 X8 X8
114 "%*x %*x %*x %*x %16s\n",
115 &s6[0], &s6[1], &s6[2], &s6[3],
116 &s6[4], &s6[5], &s6[6], &s6[7],
117 &s6[8], &s6[9], &s6[10], &s6[11],
118 &s6[12], &s6[13], &s6[14], &s6[15],
120 && !strcmp(name, ifname))
131 do_ethtool(struct netdev *netdev)
134 struct ethtool_cmd ecmd;
137 netdev->features = 0;
139 memset(&ifr, 0, sizeof ifr);
140 strncpy(ifr.ifr_name, netdev->name, sizeof ifr.ifr_name);
141 ifr.ifr_data = (caddr_t) &ecmd;
143 memset(&ecmd, 0, sizeof ecmd);
144 ecmd.cmd = ETHTOOL_GSET;
145 if (ioctl(netdev->fd, SIOCETHTOOL, &ifr) == 0) {
146 if (ecmd.supported & SUPPORTED_10baseT_Half) {
147 netdev->features |= OFPPF_10MB_HD;
149 if (ecmd.supported & SUPPORTED_10baseT_Full) {
150 netdev->features |= OFPPF_10MB_FD;
152 if (ecmd.supported & SUPPORTED_100baseT_Half) {
153 netdev->features |= OFPPF_100MB_HD;
155 if (ecmd.supported & SUPPORTED_100baseT_Full) {
156 netdev->features |= OFPPF_100MB_FD;
158 if (ecmd.supported & SUPPORTED_1000baseT_Half) {
159 netdev->features |= OFPPF_1GB_HD;
161 if (ecmd.supported & SUPPORTED_1000baseT_Full) {
162 netdev->features |= OFPPF_1GB_FD;
164 /* 10Gbps half-duplex doesn't exist... */
165 if (ecmd.supported & SUPPORTED_10000baseT_Full) {
166 netdev->features |= OFPPF_10GB_FD;
169 switch (ecmd.speed) {
179 netdev->speed = 1000;
183 netdev->speed = 2500;
187 netdev->speed = 10000;
191 VLOG_DBG("ioctl(SIOCETHTOOL) failed: %s", strerror(errno));
195 /* Opens the network device named 'name' (e.g. "eth0") and returns zero if
196 * successful, otherwise a positive errno value. On success, sets '*netdev'
197 * to the new network device, otherwise to null.
199 * 'ethertype' may be a 16-bit Ethernet protocol value in host byte order to
200 * capture frames of that type received on the device. It may also be one of
201 * the 'enum netdev_pseudo_ethertype' values to receive frames in one of those
204 netdev_open(const char *name, int ethertype, struct netdev **netdev_)
207 struct sockaddr_ll sll;
209 unsigned int ifindex;
210 uint8_t etheraddr[ETH_ADDR_LEN];
214 struct netdev *netdev;
219 /* Create raw socket. */
220 fd = socket(PF_PACKET, SOCK_RAW,
221 htons(ethertype == NETDEV_ETH_TYPE_NONE ? 0
222 : ethertype == NETDEV_ETH_TYPE_ANY ? ETH_P_ALL
223 : ethertype == NETDEV_ETH_TYPE_802_2 ? ETH_P_802_2
229 /* Get ethernet device index. */
230 strncpy(ifr.ifr_name, name, sizeof ifr.ifr_name);
231 if (ioctl(fd, SIOCGIFINDEX, &ifr) < 0) {
232 VLOG_ERR("ioctl(SIOCGIFINDEX) on %s device failed: %s",
233 name, strerror(errno));
236 ifindex = ifr.ifr_ifindex;
238 /* Bind to specific ethernet device. */
239 memset(&sll, 0, sizeof sll);
240 sll.sll_family = AF_PACKET;
241 sll.sll_ifindex = ifindex;
242 if (bind(fd, (struct sockaddr *) &sll, sizeof sll) < 0) {
243 VLOG_ERR("bind to %s failed: %s", name, strerror(errno));
247 if (ethertype != NETDEV_ETH_TYPE_NONE) {
248 /* Between the socket() and bind() calls above, the socket receives all
249 * packets of the requested type on all system interfaces. We do not
250 * want to receive that data, but there is no way to avoid it. So we
251 * must now drain out the receive queue. */
252 error = drain_rcvbuf(fd);
258 /* Get MAC address. */
259 if (ioctl(fd, SIOCGIFHWADDR, &ifr) < 0) {
260 VLOG_ERR("ioctl(SIOCGIFHWADDR) on %s device failed: %s",
261 name, strerror(errno));
264 if (ifr.ifr_hwaddr.sa_family != AF_UNSPEC
265 && ifr.ifr_hwaddr.sa_family != ARPHRD_ETHER) {
266 VLOG_WARN("%s device has unknown hardware address family %d",
267 name, (int) ifr.ifr_hwaddr.sa_family);
269 memcpy(etheraddr, ifr.ifr_hwaddr.sa_data, sizeof etheraddr);
272 if (ioctl(fd, SIOCGIFMTU, &ifr) < 0) {
273 VLOG_ERR("ioctl(SIOCGIFMTU) on %s device failed: %s",
274 name, strerror(errno));
279 get_ipv6_address(name, &in6);
281 /* Allocate network device. */
282 netdev = xmalloc(sizeof *netdev);
283 netdev->name = xstrdup(name);
284 netdev->ifindex = ifindex;
286 memcpy(netdev->etheraddr, etheraddr, sizeof etheraddr);
290 /* Get speed, features. */
293 /* Save flags to restore at close or exit. */
294 error = get_flags(netdev, &netdev->save_flags);
298 netdev->changed_flags = 0;
299 fatal_signal_block();
300 list_push_back(&netdev_list, &netdev->node);
301 fatal_signal_unblock();
314 /* Closes and destroys 'netdev'. */
316 netdev_close(struct netdev *netdev)
319 /* Bring down interface and drop promiscuous mode, if we brought up
320 * the interface or enabled promiscuous mode. */
322 fatal_signal_block();
323 error = restore_flags(netdev);
324 list_remove(&netdev->node);
325 fatal_signal_unblock();
327 VLOG_WARN("failed to restore network device flags on %s: %s",
328 netdev->name, strerror(error));
338 /* Pads 'buffer' out with zero-bytes to the minimum valid length of an
339 * Ethernet packet, if necessary. */
341 pad_to_minimum_length(struct buffer *buffer)
343 if (buffer->size < ETH_TOTAL_MIN) {
344 size_t shortage = ETH_TOTAL_MIN - buffer->size;
345 memset(buffer_put_uninit(buffer, shortage), 0, shortage);
349 /* Attempts to receive a packet from 'netdev' into 'buffer', which the caller
350 * must have initialized with sufficient room for the packet. The space
351 * required to receive any packet is ETH_HEADER_LEN bytes, plus VLAN_HEADER_LEN
352 * bytes, plus the device's MTU (which may be retrieved via netdev_get_mtu()).
353 * (Some devices do not allow for a VLAN header, in which case VLAN_HEADER_LEN
354 * need not be included.)
356 * If a packet is successfully retrieved, returns 0. In this case 'buffer' is
357 * guaranteed to contain at least ETH_TOTAL_MIN bytes. Otherwise, returns a
358 * positive errno value. Returns EAGAIN immediately if no packet is ready to
362 netdev_recv(struct netdev *netdev, struct buffer *buffer)
366 assert(buffer->size == 0);
367 assert(buffer_tailroom(buffer) >= ETH_TOTAL_MIN);
369 n_bytes = recv(netdev->fd,
370 buffer_tail(buffer), buffer_tailroom(buffer),
372 } while (n_bytes < 0 && errno == EINTR);
374 if (errno != EAGAIN) {
375 VLOG_WARN("error receiving Ethernet packet on %s: %s",
376 strerror(errno), netdev->name);
380 buffer->size += n_bytes;
382 /* When the kernel internally sends out an Ethernet frame on an
383 * interface, it gives us a copy *before* padding the frame to the
384 * minimum length. Thus, when it sends out something like an ARP
385 * request, we see a too-short frame. So pad it out to the minimum
387 pad_to_minimum_length(buffer);
392 /* Registers with the poll loop to wake up from the next call to poll_block()
393 * when a packet is ready to be received with netdev_recv() on 'netdev'. */
395 netdev_recv_wait(struct netdev *netdev)
397 poll_fd_wait(netdev->fd, POLLIN);
400 /* Discards all packets waiting to be received from 'netdev'. */
402 netdev_drain(struct netdev *netdev)
404 drain_rcvbuf(netdev->fd);
407 /* Sends 'buffer' on 'netdev'. Returns 0 if successful, otherwise a positive
408 * errno value. Returns EAGAIN without blocking if the packet cannot be queued
409 * immediately. Returns EMSGSIZE if a partial packet was transmitted or if
410 * the packet is too big or too small to transmit on the device.
412 * The caller retains ownership of 'buffer' in all cases.
414 * The kernel maintains a packet transmission queue, so the caller is not
415 * expected to do additional queuing of packets. */
417 netdev_send(struct netdev *netdev, const struct buffer *buffer)
420 const struct eth_header *eh;
422 /* Pull out the Ethernet header. */
423 if (buffer->size < ETH_HEADER_LEN) {
424 VLOG_WARN("cannot send %zu-byte frame on %s",
425 buffer->size, netdev->name);
428 eh = buffer_at_assert(buffer, 0, sizeof *eh);
431 n_bytes = sendto(netdev->fd, buffer->data, buffer->size, 0, NULL, 0);
432 } while (n_bytes < 0 && errno == EINTR);
435 /* The Linux AF_PACKET implementation never blocks waiting for room
436 * for packets, instead returning ENOBUFS. Translate this into EAGAIN
438 if (errno == ENOBUFS) {
440 } else if (errno != EAGAIN) {
441 VLOG_WARN("error sending Ethernet packet on %s: %s",
442 netdev->name, strerror(errno));
445 } else if (n_bytes != buffer->size) {
446 VLOG_WARN("send partial Ethernet packet (%d bytes of %zu) on %s",
447 (int) n_bytes, buffer->size, netdev->name);
454 /* Registers with the poll loop to wake up from the next call to poll_block()
455 * when the packet transmission queue has sufficient room to transmit a packet
456 * with netdev_send().
458 * The kernel maintains a packet transmission queue, so the client is not
459 * expected to do additional queuing of packets. Thus, this function is
460 * unlikely to ever be used. It is included for completeness. */
462 netdev_send_wait(struct netdev *netdev)
464 poll_fd_wait(netdev->fd, POLLOUT);
467 /* Returns a pointer to 'netdev''s MAC address. The caller must not modify or
468 * free the returned buffer. */
470 netdev_get_etheraddr(const struct netdev *netdev)
472 return netdev->etheraddr;
475 /* Returns the name of the network device that 'netdev' represents,
476 * e.g. "eth0". The caller must not modify or free the returned string. */
478 netdev_get_name(const struct netdev *netdev)
483 /* Returns the maximum size of transmitted (and received) packets on 'netdev',
484 * in bytes, not including the hardware header; thus, this is typically 1500
485 * bytes for Ethernet devices. */
487 netdev_get_mtu(const struct netdev *netdev)
492 /* Returns the current speed of the network device that 'netdev' represents, in
493 * megabits per second, or 0 if the speed is unknown. */
495 netdev_get_speed(const struct netdev *netdev)
497 return netdev->speed;
500 /* Checks the link status. Returns 1 or 0 to indicate the link is active
501 * or not, respectively. Any other return value indicates an error. */
503 netdev_get_link_status(const struct netdev *netdev)
506 struct ethtool_value edata;
508 memset(&ifr, 0, sizeof ifr);
509 strncpy(ifr.ifr_name, netdev->name, sizeof ifr.ifr_name);
510 ifr.ifr_data = (caddr_t) &edata;
512 memset(&edata, 0, sizeof edata);
513 edata.cmd = ETHTOOL_GLINK;
514 if (ioctl(netdev->fd, SIOCETHTOOL, &ifr) == 0) {
525 /* Returns the features supported by 'netdev', as a bitmap of bits from enum
526 * ofp_phy_port, in host byte order. */
528 netdev_get_features(const struct netdev *netdev)
530 return netdev->features;
533 /* If 'netdev' has an assigned IPv4 address, sets '*in4' to that address (if
534 * 'in4' is non-null) and returns true. Otherwise, returns false. */
536 netdev_get_in4(const struct netdev *netdev, struct in_addr *in4)
539 struct in_addr ip = { INADDR_ANY };
541 strncpy(ifr.ifr_name, netdev->name, sizeof ifr.ifr_name);
542 ifr.ifr_addr.sa_family = AF_INET;
543 if (ioctl(af_inet_sock, SIOCGIFADDR, &ifr) == 0) {
544 struct sockaddr_in *sin = (struct sockaddr_in *) &ifr.ifr_addr;
547 VLOG_DBG("%s: ioctl(SIOCGIFADDR) failed: %s",
548 netdev->name, strerror(errno));
553 return ip.s_addr != INADDR_ANY;
557 make_in4_sockaddr(struct sockaddr *sa, struct in_addr addr)
559 struct sockaddr_in sin;
560 memset(&sin, 0, sizeof sin);
561 sin.sin_family = AF_INET;
565 memset(sa, 0, sizeof *sa);
566 memcpy(sa, &sin, sizeof sin);
570 do_set_addr(struct netdev *netdev, int sock,
571 int ioctl_nr, const char *ioctl_name, struct in_addr addr)
576 strncpy(ifr.ifr_name, netdev->name, sizeof ifr.ifr_name);
577 make_in4_sockaddr(&ifr.ifr_addr, addr);
578 error = ioctl(sock, ioctl_nr, &ifr) < 0 ? errno : 0;
580 VLOG_WARN("ioctl(%s): %s", ioctl_name, strerror(error));
585 /* Assigns 'addr' as 'netdev''s IPv4 address and 'mask' as its netmask. If
586 * 'addr' is INADDR_ANY, 'netdev''s IPv4 address is cleared. Returns a
587 * positive errno value. */
589 netdev_set_in4(struct netdev *netdev, struct in_addr addr, struct in_addr mask)
593 error = do_set_addr(netdev, af_inet_sock,
594 SIOCSIFADDR, "SIOCSIFADDR", addr);
595 if (!error && addr.s_addr != INADDR_ANY) {
596 error = do_set_addr(netdev, af_inet_sock,
597 SIOCSIFNETMASK, "SIOCSIFNETMASK", mask);
602 /* Adds 'router' as a default gateway for 'netdev''s IP address. */
604 netdev_add_router(struct netdev *netdev, struct in_addr router)
606 struct in_addr any = { INADDR_ANY };
610 memset(&rt, 0, sizeof rt);
611 make_in4_sockaddr(&rt.rt_dst, any);
612 make_in4_sockaddr(&rt.rt_gateway, router);
613 make_in4_sockaddr(&rt.rt_genmask, any);
614 rt.rt_flags = RTF_UP | RTF_GATEWAY;
615 error = ioctl(af_inet_sock, SIOCADDRT, &rt) < 0 ? errno : 0;
617 VLOG_WARN("ioctl(SIOCADDRT): %s", strerror(error));
622 /* If 'netdev' has an assigned IPv6 address, sets '*in6' to that address (if
623 * 'in6' is non-null) and returns true. Otherwise, returns false. */
625 netdev_get_in6(const struct netdev *netdev, struct in6_addr *in6)
630 return memcmp(&netdev->in6, &in6addr_any, sizeof netdev->in6) != 0;
633 /* Obtains the current flags for 'netdev' and stores them into '*flagsp'.
634 * Returns 0 if successful, otherwise a positive errno value. */
636 netdev_get_flags(const struct netdev *netdev, enum netdev_flags *flagsp)
640 error = get_flags(netdev, &flags);
646 if (flags & IFF_UP) {
647 *flagsp |= NETDEV_UP;
649 if (flags & IFF_PROMISC) {
650 *flagsp |= NETDEV_PROMISC;
656 nd_to_iff_flags(enum netdev_flags nd)
659 if (nd & NETDEV_UP) {
662 if (nd & NETDEV_PROMISC) {
668 /* On 'netdev', turns off the flags in 'off' and then turns on the flags in
669 * 'on'. If 'permanent' is true, the changes will persist; otherwise, they
670 * will be reverted when 'netdev' is closed or the program exits. Returns 0 if
671 * successful, otherwise a positive errno value. */
673 do_update_flags(struct netdev *netdev, enum netdev_flags off,
674 enum netdev_flags on, bool permanent)
676 int old_flags, new_flags;
679 error = get_flags(netdev, &old_flags);
684 new_flags = (old_flags & ~nd_to_iff_flags(off)) | nd_to_iff_flags(on);
686 netdev->changed_flags |= new_flags ^ old_flags;
688 if (new_flags != old_flags) {
689 error = set_flags(netdev, new_flags);
694 /* Sets the flags for 'netdev' to 'flags'.
695 * If 'permanent' is true, the changes will persist; otherwise, they
696 * will be reverted when 'netdev' is closed or the program exits.
697 * Returns 0 if successful, otherwise a positive errno value. */
699 netdev_set_flags(struct netdev *netdev, enum netdev_flags flags,
702 return do_update_flags(netdev, -1, flags, permanent);
705 /* Turns on the specified 'flags' on 'netdev'.
706 * If 'permanent' is true, the changes will persist; otherwise, they
707 * will be reverted when 'netdev' is closed or the program exits.
708 * Returns 0 if successful, otherwise a positive errno value. */
710 netdev_turn_flags_on(struct netdev *netdev, enum netdev_flags flags,
713 return do_update_flags(netdev, 0, flags, permanent);
716 /* Turns off the specified 'flags' on 'netdev'.
717 * If 'permanent' is true, the changes will persist; otherwise, they
718 * will be reverted when 'netdev' is closed or the program exits.
719 * Returns 0 if successful, otherwise a positive errno value. */
721 netdev_turn_flags_off(struct netdev *netdev, enum netdev_flags flags,
724 return do_update_flags(netdev, flags, 0, permanent);
727 /* Looks up the ARP table entry for 'ip' on 'netdev'. If one exists and can be
728 * successfully retrieved, it stores the corresponding MAC address in 'mac' and
729 * returns 0. Otherwise, it returns a positive errno value; in particular,
730 * ENXIO indicates that there is not ARP table entry for 'ip' on 'netdev'. */
732 netdev_arp_lookup(const struct netdev *netdev,
733 uint32_t ip, uint8_t mac[ETH_ADDR_LEN])
736 struct sockaddr_in *pa;
739 memset(&r, 0, sizeof r);
740 pa = (struct sockaddr_in *) &r.arp_pa;
741 pa->sin_family = AF_INET;
742 pa->sin_addr.s_addr = ip;
744 r.arp_ha.sa_family = ARPHRD_ETHER;
746 strncpy(r.arp_dev, netdev->name, sizeof r.arp_dev);
747 retval = ioctl(af_inet_sock, SIOCGARP, &r) < 0 ? errno : 0;
749 memcpy(mac, r.arp_ha.sa_data, ETH_ADDR_LEN);
750 } else if (retval != ENXIO) {
751 VLOG_WARN("%s: could not look up ARP entry for "IP_FMT": %s",
752 netdev->name, IP_ARGS(&ip), strerror(retval));
757 static void restore_all_flags(void *aux);
759 /* Set up a signal hook to restore network device flags on program
767 fatal_signal_add_hook(restore_all_flags, NULL);
768 af_inet_sock = socket(AF_INET, SOCK_DGRAM, 0);
769 if (af_inet_sock < 0) {
770 fatal(errno, "socket(AF_INET)");
775 /* Restore the network device flags on 'netdev' to those that were active
776 * before we changed them. Returns 0 if successful, otherwise a positive
779 * To avoid reentry, the caller must ensure that fatal signals are blocked. */
781 restore_flags(struct netdev *netdev)
786 /* Get current flags. */
787 strncpy(ifr.ifr_name, netdev->name, sizeof ifr.ifr_name);
788 if (ioctl(netdev->fd, SIOCGIFFLAGS, &ifr) < 0) {
792 /* Restore flags that we might have changed, if necessary. */
793 restore_flags = netdev->changed_flags & (IFF_PROMISC | IFF_UP);
794 if ((ifr.ifr_flags ^ netdev->save_flags) & restore_flags) {
795 ifr.ifr_flags &= ~restore_flags;
796 ifr.ifr_flags |= netdev->save_flags & restore_flags;
797 if (ioctl(netdev->fd, SIOCSIFFLAGS, &ifr) < 0) {
805 /* Retores all the flags on all network devices that we modified. Called from
806 * a signal handler, so it does not attempt to report error conditions. */
808 restore_all_flags(void *aux UNUSED)
810 struct netdev *netdev;
811 LIST_FOR_EACH (netdev, struct netdev, node, &netdev_list) {
812 restore_flags(netdev);
817 get_flags(const struct netdev *netdev, int *flags)
820 strncpy(ifr.ifr_name, netdev->name, sizeof ifr.ifr_name);
821 if (ioctl(netdev->fd, SIOCGIFFLAGS, &ifr) < 0) {
822 VLOG_ERR("ioctl(SIOCGIFFLAGS) on %s device failed: %s",
823 netdev->name, strerror(errno));
826 *flags = ifr.ifr_flags;
831 set_flags(struct netdev *netdev, int flags)
834 strncpy(ifr.ifr_name, netdev->name, sizeof ifr.ifr_name);
835 ifr.ifr_flags = flags;
836 if (ioctl(netdev->fd, SIOCSIFFLAGS, &ifr) < 0) {
837 VLOG_ERR("ioctl(SIOCSIFFLAGS) on %s device failed: %s",
838 netdev->name, strerror(errno));