2 * Copyright (c) 2009, 2010, 2011, 2012, 2013 Nicira, Inc.
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at:
8 * http://www.apache.org/licenses/LICENSE-2.0
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
17 #ifndef NETDEV_PROVIDER_H
18 #define NETDEV_PROVIDER_H 1
20 /* Generic interface to network devices. */
31 /* A network device (e.g. an Ethernet device).
33 * Network device implementations may read these members but should not modify
36 char *name; /* Name of network device. */
37 const struct netdev_class *netdev_class; /* Functions to control
39 int ref_cnt; /* Times this devices was opened. */
40 struct shash_node *node; /* Pointer to element in global map. */
41 struct list saved_flags_list; /* Contains "struct netdev_saved_flags". */
44 const char *netdev_get_type(const struct netdev *);
45 const struct netdev_class *netdev_get_class(const struct netdev *);
46 const char *netdev_get_name(const struct netdev *);
47 struct netdev *netdev_from_name(const char *name);
48 void netdev_get_devices(const struct netdev_class *,
49 struct shash *device_list);
51 /* A data structure for capturing packets received by a network device.
53 * Network device implementations may read these members but should not modify
56 * None of these members change during the lifetime of a struct netdev_rx. */
58 struct netdev *netdev; /* Owns a reference to the netdev. */
61 struct netdev *netdev_rx_get_netdev(const struct netdev_rx *);
63 /* Network device class structure, to be defined by each implementation of a
66 * These functions return 0 if successful or a positive errno value on failure,
67 * except where otherwise noted.
73 * These functions work primarily with two different kinds of data structures:
75 * - "struct netdev", which represents a network device.
77 * - "struct netdev_rx", which represents a handle for capturing packets
78 * received on a network device
80 * Each of these data structures contains all of the implementation-independent
81 * generic state for the respective concept, called the "base" state. None of
82 * them contains any extra space for implementations to use. Instead, each
83 * implementation is expected to declare its own data structure that contains
84 * an instance of the generic data structure plus additional
85 * implementation-specific members, called the "derived" state. The
86 * implementation can use casts or (preferably) the CONTAINER_OF macro to
87 * obtain access to derived state given only a pointer to the embedded generic
94 * Four stylized functions accompany each of these data structures:
96 * "alloc" "construct" "destruct" "dealloc"
97 * ------------ ---------------- --------------- --------------
98 * netdev ->alloc ->construct ->destruct ->dealloc
99 * netdev_rx ->rx_alloc ->rx_construct ->rx_destruct ->rx_dealloc
101 * Any instance of a given data structure goes through the following life
104 * 1. The client calls the "alloc" function to obtain raw memory. If "alloc"
105 * fails, skip all the other steps.
107 * 2. The client initializes all of the data structure's base state. If this
108 * fails, skip to step 7.
110 * 3. The client calls the "construct" function. The implementation
111 * initializes derived state. It may refer to the already-initialized
112 * base state. If "construct" fails, skip to step 6.
114 * 4. The data structure is now initialized and in use.
116 * 5. When the data structure is no longer needed, the client calls the
117 * "destruct" function. The implementation uninitializes derived state.
118 * The base state has not been uninitialized yet, so the implementation
119 * may still refer to it.
121 * 6. The client uninitializes all of the data structure's base state.
123 * 7. The client calls the "dealloc" to free the raw memory. The
124 * implementation must not refer to base or derived state in the data
125 * structure, because it has already been uninitialized.
127 * Each "alloc" function allocates and returns a new instance of the respective
128 * data structure. The "alloc" function is not given any information about the
129 * use of the new data structure, so it cannot perform much initialization.
130 * Its purpose is just to ensure that the new data structure has enough room
131 * for base and derived state. It may return a null pointer if memory is not
132 * available, in which case none of the other functions is called.
134 * Each "construct" function initializes derived state in its respective data
135 * structure. When "construct" is called, all of the base state has already
136 * been initialized, so the "construct" function may refer to it. The
137 * "construct" function is allowed to fail, in which case the client calls the
138 * "dealloc" function (but not the "destruct" function).
140 * Each "destruct" function uninitializes and frees derived state in its
141 * respective data structure. When "destruct" is called, the base state has
142 * not yet been uninitialized, so the "destruct" function may refer to it. The
143 * "destruct" function is not allowed to fail.
145 * Each "dealloc" function frees raw memory that was allocated by the the
146 * "alloc" function. The memory's base and derived members might not have ever
147 * been initialized (but if "construct" returned successfully, then it has been
148 * "destruct"ed already). The "dealloc" function is not allowed to fail. */
149 struct netdev_class {
150 /* Type of netdevs in this class, e.g. "system", "tap", "gre", etc.
152 * One of the providers should supply a "system" type, since this is
153 * the type assumed if no type is specified when opening a netdev.
154 * The "system" type corresponds to an existing network device on
158 /* ## ------------------- ## */
159 /* ## Top-Level Functions ## */
160 /* ## ------------------- ## */
162 /* Called when the netdev provider is registered, typically at program
163 * startup. Returning an error from this function will prevent any network
164 * device in this class from being opened.
166 * This function may be set to null if a network device class needs no
167 * initialization at registration time. */
170 /* Performs periodic work needed by netdevs of this class. May be null if
171 * no periodic work is necessary. */
174 /* Arranges for poll_block() to wake up if the "run" member function needs
175 * to be called. Implementations are additionally required to wake
176 * whenever something changes in any of its netdevs which would cause their
177 * ->change_seq() function to change its result. May be null if nothing is
181 /* ## ---------------- ## */
182 /* ## netdev Functions ## */
183 /* ## ---------------- ## */
185 /* Life-cycle functions for a netdev. See the large comment above on
186 * struct netdev_class. */
187 struct netdev *(*alloc)(void);
188 int (*construct)(struct netdev *);
189 void (*destruct)(struct netdev *);
190 void (*dealloc)(struct netdev *);
192 /* Fetches the device 'netdev''s configuration, storing it in 'args'.
193 * The caller owns 'args' and pre-initializes it to an empty smap.
195 * If this netdev class does not have any configuration options, this may
196 * be a null pointer. */
197 int (*get_config)(const struct netdev *netdev, struct smap *args);
199 /* Changes the device 'netdev''s configuration to 'args'.
201 * If this netdev class does not support configuration, this may be a null
203 int (*set_config)(struct netdev *netdev, const struct smap *args);
205 /* Returns the tunnel configuration of 'netdev'. If 'netdev' is
206 * not a tunnel, returns null.
208 * If this function would always return null, it may be null instead. */
209 const struct netdev_tunnel_config *
210 (*get_tunnel_config)(const struct netdev *netdev);
212 /* Sends the 'size'-byte packet in 'buffer' on 'netdev'. Returns 0 if
213 * successful, otherwise a positive errno value. Returns EAGAIN without
214 * blocking if the packet cannot be queued immediately. Returns EMSGSIZE
215 * if a partial packet was transmitted or if the packet is too big or too
216 * small to transmit on the device.
218 * The caller retains ownership of 'buffer' in all cases.
220 * The network device is expected to maintain a packet transmission queue,
221 * so that the caller does not ordinarily have to do additional queuing of
224 * May return EOPNOTSUPP if a network device does not implement packet
225 * transmission through this interface. This function may be set to null
226 * if it would always return EOPNOTSUPP anyhow. (This will prevent the
227 * network device from being usefully used by the netdev-based "userspace
228 * datapath". It will also prevent the OVS implementation of bonding from
229 * working properly over 'netdev'.) */
230 int (*send)(struct netdev *netdev, const void *buffer, size_t size);
232 /* Registers with the poll loop to wake up from the next call to
233 * poll_block() when the packet transmission queue for 'netdev' has
234 * sufficient room to transmit a packet with netdev_send().
236 * The network device is expected to maintain a packet transmission queue,
237 * so that the caller does not ordinarily have to do additional queuing of
238 * packets. Thus, this function is unlikely to ever be useful.
240 * May be null if not needed, such as for a network device that does not
241 * implement packet transmission through the 'send' member function. */
242 void (*send_wait)(struct netdev *netdev);
244 /* Sets 'netdev''s Ethernet address to 'mac' */
245 int (*set_etheraddr)(struct netdev *netdev, const uint8_t mac[6]);
247 /* Retrieves 'netdev''s Ethernet address into 'mac'.
249 * This address will be advertised as 'netdev''s MAC address through the
250 * OpenFlow protocol, among other uses. */
251 int (*get_etheraddr)(const struct netdev *netdev, uint8_t mac[6]);
253 /* Retrieves 'netdev''s MTU into '*mtup'.
255 * The MTU is the maximum size of transmitted (and received) packets, in
256 * bytes, not including the hardware header; thus, this is typically 1500
257 * bytes for Ethernet devices.
259 * If 'netdev' does not have an MTU (e.g. as some tunnels do not), then
260 * this function should return EOPNOTSUPP. This function may be set to
261 * null if it would always return EOPNOTSUPP. */
262 int (*get_mtu)(const struct netdev *netdev, int *mtup);
264 /* Sets 'netdev''s MTU to 'mtu'.
266 * If 'netdev' does not have an MTU (e.g. as some tunnels do not), then
267 * this function should return EOPNOTSUPP. This function may be set to
268 * null if it would always return EOPNOTSUPP. */
269 int (*set_mtu)(const struct netdev *netdev, int mtu);
271 /* Returns the ifindex of 'netdev', if successful, as a positive number.
272 * On failure, returns a negative errno value.
274 * The desired semantics of the ifindex value are a combination of those
275 * specified by POSIX for if_nametoindex() and by SNMP for ifIndex. An
276 * ifindex value should be unique within a host and remain stable at least
277 * until reboot. SNMP says an ifindex "ranges between 1 and the value of
278 * ifNumber" but many systems do not follow this rule anyhow.
280 * This function may be set to null if it would always return -EOPNOTSUPP.
282 int (*get_ifindex)(const struct netdev *netdev);
284 /* Sets 'carrier' to true if carrier is active (link light is on) on
287 * May be null if device does not provide carrier status (will be always
288 * up as long as device is up).
290 int (*get_carrier)(const struct netdev *netdev, bool *carrier);
292 /* Returns the number of times 'netdev''s carrier has changed since being
295 * If null, callers will assume the number of carrier resets is zero. */
296 long long int (*get_carrier_resets)(const struct netdev *netdev);
298 /* Forces ->get_carrier() to poll 'netdev''s MII registers for link status
299 * instead of checking 'netdev''s carrier. 'netdev''s MII registers will
300 * be polled once ever 'interval' milliseconds. If 'netdev' does not
301 * support MII, another method may be used as a fallback. If 'interval' is
302 * less than or equal to zero, reverts ->get_carrier() to its normal
305 * Most network devices won't support this feature and will set this
306 * function pointer to NULL, which is equivalent to returning EOPNOTSUPP.
308 int (*set_miimon_interval)(struct netdev *netdev, long long int interval);
310 /* Retrieves current device stats for 'netdev' into 'stats'.
312 * A network device that supports some statistics but not others, it should
313 * set the values of the unsupported statistics to all-1-bits
315 int (*get_stats)(const struct netdev *netdev, struct netdev_stats *);
317 /* Sets the device stats for 'netdev' to 'stats'.
319 * Most network devices won't support this feature and will set this
320 * function pointer to NULL, which is equivalent to returning EOPNOTSUPP.
322 * Some network devices might only allow setting their stats to 0. */
323 int (*set_stats)(struct netdev *netdev, const struct netdev_stats *);
325 /* Stores the features supported by 'netdev' into each of '*current',
326 * '*advertised', '*supported', and '*peer'. Each value is a bitmap of
329 * This function may be set to null if it would always return EOPNOTSUPP.
331 int (*get_features)(const struct netdev *netdev,
332 enum netdev_features *current,
333 enum netdev_features *advertised,
334 enum netdev_features *supported,
335 enum netdev_features *peer);
337 /* Set the features advertised by 'netdev' to 'advertise', which is a
338 * set of NETDEV_F_* bits.
340 * This function may be set to null for a network device that does not
341 * support configuring advertisements. */
342 int (*set_advertisements)(struct netdev *netdev,
343 enum netdev_features advertise);
345 /* Attempts to set input rate limiting (policing) policy, such that up to
346 * 'kbits_rate' kbps of traffic is accepted, with a maximum accumulative
347 * burst size of 'kbits' kb.
349 * This function may be set to null if policing is not supported. */
350 int (*set_policing)(struct netdev *netdev, unsigned int kbits_rate,
351 unsigned int kbits_burst);
353 /* Adds to 'types' all of the forms of QoS supported by 'netdev', or leaves
354 * it empty if 'netdev' does not support QoS. Any names added to 'types'
355 * should be documented as valid for the "type" column in the "QoS" table
356 * in vswitchd/vswitch.xml (which is built as ovs-vswitchd.conf.db(8)).
358 * Every network device must support disabling QoS with a type of "", but
359 * this function must not add "" to 'types'.
361 * The caller is responsible for initializing 'types' (e.g. with
362 * sset_init()) before calling this function. The caller retains ownership
365 * May be NULL if 'netdev' does not support QoS at all. */
366 int (*get_qos_types)(const struct netdev *netdev, struct sset *types);
368 /* Queries 'netdev' for its capabilities regarding the specified 'type' of
369 * QoS. On success, initializes 'caps' with the QoS capabilities.
371 * Should return EOPNOTSUPP if 'netdev' does not support 'type'. May be
372 * NULL if 'netdev' does not support QoS at all. */
373 int (*get_qos_capabilities)(const struct netdev *netdev,
375 struct netdev_qos_capabilities *caps);
377 /* Queries 'netdev' about its currently configured form of QoS. If
378 * successful, stores the name of the current form of QoS into '*typep'
379 * and any details of configuration as string key-value pairs in
382 * A '*typep' of "" indicates that QoS is currently disabled on 'netdev'.
384 * The caller initializes 'details' before calling this function. The
385 * caller takes ownership of the string key-values pairs added to
388 * The netdev retains ownership of '*typep'.
390 * '*typep' will be one of the types returned by netdev_get_qos_types() for
391 * 'netdev'. The contents of 'details' should be documented as valid for
392 * '*typep' in the "other_config" column in the "QoS" table in
393 * vswitchd/vswitch.xml (which is built as ovs-vswitchd.conf.db(8)).
395 * May be NULL if 'netdev' does not support QoS at all. */
396 int (*get_qos)(const struct netdev *netdev,
397 const char **typep, struct smap *details);
399 /* Attempts to reconfigure QoS on 'netdev', changing the form of QoS to
400 * 'type' with details of configuration from 'details'.
402 * On error, the previous QoS configuration is retained.
404 * When this function changes the type of QoS (not just 'details'), this
405 * also resets all queue configuration for 'netdev' to their defaults
406 * (which depend on the specific type of QoS). Otherwise, the queue
407 * configuration for 'netdev' is unchanged.
409 * 'type' should be "" (to disable QoS) or one of the types returned by
410 * netdev_get_qos_types() for 'netdev'. The contents of 'details' should
411 * be documented as valid for the given 'type' in the "other_config" column
412 * in the "QoS" table in vswitchd/vswitch.xml (which is built as
413 * ovs-vswitchd.conf.db(8)).
415 * May be NULL if 'netdev' does not support QoS at all. */
416 int (*set_qos)(struct netdev *netdev,
417 const char *type, const struct smap *details);
419 /* Queries 'netdev' for information about the queue numbered 'queue_id'.
420 * If successful, adds that information as string key-value pairs to
421 * 'details'. Returns 0 if successful, otherwise a positive errno value.
423 * Should return EINVAL if 'queue_id' is greater than or equal to the
424 * number of supported queues (as reported in the 'n_queues' member of
425 * struct netdev_qos_capabilities by 'get_qos_capabilities').
427 * The caller initializes 'details' before calling this function. The
428 * caller takes ownership of the string key-values pairs added to
431 * The returned contents of 'details' should be documented as valid for the
432 * given 'type' in the "other_config" column in the "Queue" table in
433 * vswitchd/vswitch.xml (which is built as ovs-vswitchd.conf.db(8)).
435 int (*get_queue)(const struct netdev *netdev,
436 unsigned int queue_id, struct smap *details);
438 /* Configures the queue numbered 'queue_id' on 'netdev' with the key-value
439 * string pairs in 'details'. The contents of 'details' should be
440 * documented as valid for the given 'type' in the "other_config" column in
441 * the "Queue" table in vswitchd/vswitch.xml (which is built as
442 * ovs-vswitchd.conf.db(8)). Returns 0 if successful, otherwise a positive
443 * errno value. On failure, the given queue's configuration should be
446 * Should return EINVAL if 'queue_id' is greater than or equal to the
447 * number of supported queues (as reported in the 'n_queues' member of
448 * struct netdev_qos_capabilities by 'get_qos_capabilities'), or if
449 * 'details' is invalid for the type of queue.
451 * This function does not modify 'details', and the caller retains
454 * May be NULL if 'netdev' does not support QoS at all. */
455 int (*set_queue)(struct netdev *netdev,
456 unsigned int queue_id, const struct smap *details);
458 /* Attempts to delete the queue numbered 'queue_id' from 'netdev'.
460 * Should return EINVAL if 'queue_id' is greater than or equal to the
461 * number of supported queues (as reported in the 'n_queues' member of
462 * struct netdev_qos_capabilities by 'get_qos_capabilities'). Should
463 * return EOPNOTSUPP if 'queue_id' is valid but may not be deleted (e.g. if
464 * 'netdev' has a fixed set of queues with the current QoS mode).
466 * May be NULL if 'netdev' does not support QoS at all, or if all of its
467 * QoS modes have fixed sets of queues. */
468 int (*delete_queue)(struct netdev *netdev, unsigned int queue_id);
470 /* Obtains statistics about 'queue_id' on 'netdev'. Fills 'stats' with the
471 * queue's statistics. May set individual members of 'stats' to all-1-bits
472 * if the statistic is unavailable.
474 * May be NULL if 'netdev' does not support QoS at all. */
475 int (*get_queue_stats)(const struct netdev *netdev, unsigned int queue_id,
476 struct netdev_queue_stats *stats);
478 /* Iterates over all of 'netdev''s queues, calling 'cb' with the queue's
479 * ID, its configuration, and the 'aux' specified by the caller. The order
480 * of iteration is unspecified, but (when successful) each queue is visited
483 * 'cb' will not modify or free the 'details' argument passed in. It may
484 * delete or modify the queue passed in as its 'queue_id' argument. It may
485 * modify but will not delete any other queue within 'netdev'. If 'cb'
486 * adds new queues, then ->dump_queues is allowed to visit some queues
487 * twice or not at all.
489 int (*dump_queues)(const struct netdev *netdev,
490 void (*cb)(unsigned int queue_id,
491 const struct smap *details,
495 /* Iterates over all of 'netdev''s queues, calling 'cb' with the queue's
496 * ID, its statistics, and the 'aux' specified by the caller. The order of
497 * iteration is unspecified, but (when successful) each queue must be
498 * visited exactly once.
500 * 'cb' will not modify or free the statistics passed in. */
501 int (*dump_queue_stats)(const struct netdev *netdev,
502 void (*cb)(unsigned int queue_id,
503 struct netdev_queue_stats *,
507 /* If 'netdev' has an assigned IPv4 address, sets '*address' to that
508 * address and '*netmask' to the associated netmask.
510 * The following error values have well-defined meanings:
512 * - EADDRNOTAVAIL: 'netdev' has no assigned IPv4 address.
514 * - EOPNOTSUPP: No IPv4 network stack attached to 'netdev'.
516 * This function may be set to null if it would always return EOPNOTSUPP
518 int (*get_in4)(const struct netdev *netdev, struct in_addr *address,
519 struct in_addr *netmask);
521 /* Assigns 'addr' as 'netdev''s IPv4 address and 'mask' as its netmask. If
522 * 'addr' is INADDR_ANY, 'netdev''s IPv4 address is cleared.
524 * This function may be set to null if it would always return EOPNOTSUPP
526 int (*set_in4)(struct netdev *netdev, struct in_addr addr,
527 struct in_addr mask);
529 /* If 'netdev' has an assigned IPv6 address, sets '*in6' to that address.
531 * The following error values have well-defined meanings:
533 * - EADDRNOTAVAIL: 'netdev' has no assigned IPv6 address.
535 * - EOPNOTSUPP: No IPv6 network stack attached to 'netdev'.
537 * This function may be set to null if it would always return EOPNOTSUPP
539 int (*get_in6)(const struct netdev *netdev, struct in6_addr *in6);
541 /* Adds 'router' as a default IP gateway for the TCP/IP stack that
542 * corresponds to 'netdev'.
544 * This function may be set to null if it would always return EOPNOTSUPP
546 int (*add_router)(struct netdev *netdev, struct in_addr router);
548 /* Looks up the next hop for 'host'. If successful, stores the next hop
549 * gateway's address (0 if 'host' is on a directly connected network) in
550 * '*next_hop' and a copy of the name of the device to reach 'host' in
551 * '*netdev_name', and returns 0. The caller is responsible for freeing
552 * '*netdev_name' (by calling free()).
554 * This function may be set to null if it would always return EOPNOTSUPP
556 int (*get_next_hop)(const struct in_addr *host, struct in_addr *next_hop,
559 /* Retrieves driver information of the device.
561 * Populates 'smap' with key-value pairs representing the status of the
562 * device. 'smap' is a set of key-value string pairs representing netdev
563 * type specific information. For more information see
564 * ovs-vswitchd.conf.db(5).
566 * The caller is responsible for destroying 'smap' and its data.
568 * This function may be set to null if it would always return EOPNOTSUPP
570 int (*get_status)(const struct netdev *netdev, struct smap *smap);
572 /* Looks up the ARP table entry for 'ip' on 'netdev' and stores the
573 * corresponding MAC address in 'mac'. A return value of ENXIO, in
574 * particular, indicates that there is no ARP table entry for 'ip' on
577 * This function may be set to null if it would always return EOPNOTSUPP
579 int (*arp_lookup)(const struct netdev *netdev, ovs_be32 ip,
582 /* Retrieves the current set of flags on 'netdev' into '*old_flags'. Then,
583 * turns off the flags that are set to 1 in 'off' and turns on the flags
584 * that are set to 1 in 'on'. (No bit will be set to 1 in both 'off' and
585 * 'on'; that is, off & on == 0.)
587 * This function may be invoked from a signal handler. Therefore, it
588 * should not do anything that is not signal-safe (such as logging). */
589 int (*update_flags)(struct netdev *netdev, enum netdev_flags off,
590 enum netdev_flags on, enum netdev_flags *old_flags);
592 /* Returns a sequence number which indicates changes in one of 'netdev''s
593 * properties. The returned sequence number must be nonzero so that
594 * callers have a value which they may use as a reset when tracking
597 * Minimally, the returned sequence number is required to change whenever
598 * 'netdev''s flags, features, ethernet address, or carrier changes. The
599 * returned sequence number is allowed to change even when 'netdev' doesn't
600 * change, although implementations should try to avoid this. */
601 unsigned int (*change_seq)(const struct netdev *netdev);
603 /* ## ------------------- ## */
604 /* ## netdev_rx Functions ## */
605 /* ## ------------------- ## */
607 /* If a particular netdev class does not support receiving packets, all these
608 * function pointers must be NULL. */
610 /* Life-cycle functions for a netdev_rx. See the large comment above on
611 * struct netdev_class. */
612 struct netdev_rx *(*rx_alloc)(void);
613 int (*rx_construct)(struct netdev_rx *);
614 void (*rx_destruct)(struct netdev_rx *);
615 void (*rx_dealloc)(struct netdev_rx *);
617 /* Attempts to receive a packet from 'rx' into the 'size' bytes in
618 * 'buffer'. If successful, returns the number of bytes in the received
619 * packet, otherwise a negative errno value. Returns -EAGAIN immediately
620 * if no packet is ready to be received.
622 * Must return -EMSGSIZE, and discard the packet, if the received packet
623 * is longer than 'size' bytes.
625 * Specify NULL if this */
626 int (*rx_recv)(struct netdev_rx *rx, void *buffer, size_t size);
628 /* Registers with the poll loop to wake up from the next call to
629 * poll_block() when a packet is ready to be received with netdev_rx_recv()
631 void (*rx_wait)(struct netdev_rx *rx);
633 /* Discards all packets waiting to be received from 'rx'. */
634 int (*rx_drain)(struct netdev_rx *rx);
637 int netdev_register_provider(const struct netdev_class *);
638 int netdev_unregister_provider(const char *type);
639 const struct netdev_class *netdev_lookup_provider(const char *type);
641 extern const struct netdev_class netdev_linux_class;
642 extern const struct netdev_class netdev_internal_class;
643 extern const struct netdev_class netdev_tap_class;
644 #if defined(__FreeBSD__) || defined(__NetBSD__)
645 extern const struct netdev_class netdev_bsd_class;
652 #endif /* netdev.h */