lib/netdev-provider.h

   1 /*
   2  * Copyright (c) 2009, 2010 Nicira Networks.
   3  *
   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:
   7  *
   8  *     http://www.apache.org/licenses/LICENSE-2.0
   9  *
  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.
  15  */
  16
  17 #ifndef NETDEV_PROVIDER_H
  18 #define NETDEV_PROVIDER_H 1
  19
  20 /* Generic interface to network devices. */
  21
  22 #include <assert.h>
  23
  24 #include "netdev.h"
  25 #include "list.h"
  26 #include "shash.h"
  27
  28 #ifdef  __cplusplus
  29 extern "C" {
  30 #endif
  31
  32 /* A network device (e.g. an Ethernet device).
  33  *
  34  * This structure should be treated as opaque by network device
  35  * implementations. */
  36 struct netdev_dev {
  37     char *name;                         /* Name of network device. */
  38     const struct netdev_class *netdev_class; /* Functions to control
  39                                                 this device. */
  40     int ref_cnt;                        /* Times this devices was opened. */
  41     struct shash_node *node;            /* Pointer to element in global map. */
  42     struct shash args;                  /* Argument list from last config. */
  43 };
  44
  45 void netdev_dev_init(struct netdev_dev *, const char *name,
  46                      const struct shash *args,
  47                      const struct netdev_class *);
  48 void netdev_dev_uninit(struct netdev_dev *, bool destroy);
  49 const char *netdev_dev_get_type(const struct netdev_dev *);
  50 const struct netdev_class *netdev_dev_get_class(const struct netdev_dev *);
  51 const char *netdev_dev_get_name(const struct netdev_dev *);
  52 struct netdev_dev *netdev_dev_from_name(const char *name);
  53 void netdev_dev_get_devices(const struct netdev_class *,
  54                             struct shash *device_list);
  55
  56 static inline void netdev_dev_assert_class(const struct netdev_dev *netdev_dev,
  57                                            const struct netdev_class *class_)
  58 {
  59     assert(netdev_dev->netdev_class == class_);
  60 }
  61
  62 /* A instance of an open network device.
  63  *
  64  * This structure should be treated as opaque by network device
  65  * implementations. */
  66 struct netdev {
  67     struct netdev_dev *netdev_dev;   /* Parent netdev_dev. */
  68     struct list node;                /* Element in global list. */
  69
  70     enum netdev_flags save_flags;    /* Initial device flags. */
  71     enum netdev_flags changed_flags; /* Flags that we changed. */
  72 };
  73
  74 void netdev_init(struct netdev *, struct netdev_dev *);
  75 void netdev_uninit(struct netdev *, bool close);
  76 struct netdev_dev *netdev_get_dev(const struct netdev *);
  77
  78 static inline void netdev_assert_class(const struct netdev *netdev,
  79                                        const struct netdev_class *netdev_class)
  80 {
  81     netdev_dev_assert_class(netdev_get_dev(netdev), netdev_class);
  82 }
  83
  84 /* A network device notifier.
  85  *
  86  * Network device implementations should use netdev_notifier_init() to
  87  * initialize this structure, but they may freely read its members after
  88  * initialization. */
  89 struct netdev_notifier {
  90     struct netdev *netdev;
  91     void (*cb)(struct netdev_notifier *);
  92     void *aux;
  93 };
  94 void netdev_notifier_init(struct netdev_notifier *, struct netdev *,
  95                           void (*cb)(struct netdev_notifier *), void *aux);
  96
  97 /* Network device class structure, to be defined by each implementation of a
  98  * network device.
  99  *
 100  * These functions return 0 if successful or a positive errno value on failure,
 101  * except where otherwise noted. */
 102 struct netdev_class {
 103     /* Type of netdevs in this class, e.g. "system", "tap", "gre", etc.
 104      *
 105      * One of the providers should supply a "system" type, since this is
 106      * the type assumed if no type is specified when opening a netdev.
 107      * The "system" type corresponds to an existing network device on
 108      * the system. */
 109     const char *type;
 110
 111     /* Called when the netdev provider is registered, typically at program
 112      * startup.  Returning an error from this function will prevent any network
 113      * device in this class from being opened.
 114      *
 115      * This function may be set to null if a network device class needs no
 116      * initialization at registration time. */
 117     int (*init)(void);
 118
 119     /* Performs periodic work needed by netdevs of this class.  May be null if
 120      * no periodic work is necessary. */
 121     void (*run)(void);
 122
 123     /* Arranges for poll_block() to wake up if the "run" member function needs
 124      * to be called.  May be null if nothing is needed here. */
 125     void (*wait)(void);
 126
 127     /* Attempts to create a network device named 'name' with initial 'args' in
 128      * 'netdev_class'.  On success sets 'netdev_devp' to the newly created
 129      * device. */
 130     int (*create)(const struct netdev_class *netdev_class, const char *name,
 131                   const struct shash *args, struct netdev_dev **netdev_devp);
 132
 133     /* Destroys 'netdev_dev'.
 134      *
 135      * Netdev devices maintain a reference count that is incremented on
 136      * netdev_open() and decremented on netdev_close().  If 'netdev_dev'
 137      * has a non-zero reference count, then this function will not be
 138      * called. */
 139     void (*destroy)(struct netdev_dev *netdev_dev);
 140
 141     /* Changes the device 'netdev_dev''s configuration to 'args'.
 142      *
 143      * If this netdev class does not support reconfiguring a netdev
 144      * device, this may be a null pointer.
 145      */
 146     int (*set_config)(struct netdev_dev *netdev_dev, const struct shash *args);
 147
 148     /* Attempts to open a network device.  On success, sets 'netdevp'
 149      * to the new network device.
 150      *
 151      * 'ethertype' may be a 16-bit Ethernet protocol value in host byte order
 152      * to capture frames of that type received on the device.  It may also be
 153      * one of the 'enum netdev_pseudo_ethertype' values to receive frames in
 154      * one of those categories. */
 155     int (*open)(struct netdev_dev *netdev_dev, int ethertype,
 156                 struct netdev **netdevp);
 157
 158     /* Closes 'netdev'. */
 159     void (*close)(struct netdev *netdev);
 160
 161     /* Enumerates the names of all network devices of this class.
 162      *
 163      * The caller has already initialized 'all_names' and might already have
 164      * added some names to it.  This function should not disturb any existing
 165      * names in 'all_names'.
 166      *
 167      * If this netdev class does not support enumeration, this may be a null
 168      * pointer. */
 169     int (*enumerate)(struct svec *all_names);
 170
 171     /* Attempts to receive a packet from 'netdev' into the 'size' bytes in
 172      * 'buffer'.  If successful, returns the number of bytes in the received
 173      * packet, otherwise a negative errno value.  Returns -EAGAIN immediately
 174      * if no packet is ready to be received.
 175      *
 176      * May return -EOPNOTSUPP if a network device does not implement packet
 177      * reception through this interface.  This function may be set to null if
 178      * it would always return -EOPNOTSUPP anyhow.  (This will disable the OVS
 179      * integrated DHCP client and OpenFlow controller discovery, and prevent
 180      * the network device from being usefully used by the netdev-based
 181      * "userspace datapath".) */
 182     int (*recv)(struct netdev *netdev, void *buffer, size_t size);
 183
 184     /* Registers with the poll loop to wake up from the next call to
 185      * poll_block() when a packet is ready to be received with netdev_recv() on
 186      * 'netdev'.
 187      *
 188      * May be null if not needed, such as for a network device that does not
 189      * implement packet reception through the 'recv' member function. */
 190     void (*recv_wait)(struct netdev *netdev);
 191
 192     /* Discards all packets waiting to be received from 'netdev'.
 193      *
 194      * May be null if not needed, such as for a network device that does not
 195      * implement packet reception through the 'recv' member function. */
 196     int (*drain)(struct netdev *netdev);
 197
 198     /* Sends the 'size'-byte packet in 'buffer' on 'netdev'.  Returns 0 if
 199      * successful, otherwise a positive errno value.  Returns EAGAIN without
 200      * blocking if the packet cannot be queued immediately.  Returns EMSGSIZE
 201      * if a partial packet was transmitted or if the packet is too big or too
 202      * small to transmit on the device.
 203      *
 204      * The caller retains ownership of 'buffer' in all cases.
 205      *
 206      * The network device is expected to maintain a packet transmission queue,
 207      * so that the caller does not ordinarily have to do additional queuing of
 208      * packets.
 209      *
 210      * May return EOPNOTSUPP if a network device does not implement packet
 211      * transmission through this interface.  This function may be set to null
 212      * if it would always return EOPNOTSUPP anyhow.  (This will disable the OVS
 213      * integrated DHCP client and OpenFlow controller discovery, and prevent
 214      * the network device from being usefully used by the netdev-based
 215      * "userspace datapath".) */
 216     int (*send)(struct netdev *netdev, const void *buffer, size_t size);
 217
 218     /* Registers with the poll loop to wake up from the next call to
 219      * poll_block() when the packet transmission queue for 'netdev' has
 220      * sufficient room to transmit a packet with netdev_send().
 221      *
 222      * The network device is expected to maintain a packet transmission queue,
 223      * so that the caller does not ordinarily have to do additional queuing of
 224      * packets.  Thus, this function is unlikely to ever be useful.
 225      *
 226      * May be null if not needed, such as for a network device that does not
 227      * implement packet transmission through the 'send' member function. */
 228     void (*send_wait)(struct netdev *netdev);
 229
 230     /* Sets 'netdev''s Ethernet address to 'mac' */
 231     int (*set_etheraddr)(struct netdev *netdev, const uint8_t mac[6]);
 232
 233     /* Retrieves 'netdev''s Ethernet address into 'mac'. */
 234     int (*get_etheraddr)(const struct netdev *netdev, uint8_t mac[6]);
 235
 236     /* Retrieves 'netdev''s MTU into '*mtup'.
 237      *
 238      * The MTU is the maximum size of transmitted (and received) packets, in
 239      * bytes, not including the hardware header; thus, this is typically 1500
 240      * bytes for Ethernet devices.*/
 241     int (*get_mtu)(const struct netdev *netdev, int *mtup);
 242
 243     /* Returns the ifindex of 'netdev', if successful, as a positive number.
 244      * On failure, returns a negative errno value.
 245      *
 246      * The desired semantics of the ifindex value are a combination of those
 247      * specified by POSIX for if_nametoindex() and by SNMP for ifIndex.  An
 248      * ifindex value should be unique within a host and remain stable at least
 249      * until reboot.  SNMP says an ifindex "ranges between 1 and the value of
 250      * ifNumber" but many systems do not follow this rule anyhow.
 251      *
 252      * This function may be set to null if it would always return -EOPNOTSUPP.
 253      */
 254     int (*get_ifindex)(const struct netdev *netdev);
 255
 256     /* Sets 'carrier' to true if carrier is active (link light is on) on
 257      * 'netdev'.
 258      *
 259      * May be null if device does not provide carrier status (will be always
 260      * up as long as device is up).
 261      */
 262     int (*get_carrier)(const struct netdev *netdev, bool *carrier);
 263
 264     /* Sets 'miimon' to true if 'netdev' is up according to its MII.  If
 265      * 'netdev' does not support MII, may fall back to another method or return
 266      * EOPNOTSUPP.
 267      *
 268      * This function may be set to null if it would always return EOPNOTSUPP.
 269      */
 270     int (*get_miimon)(const struct netdev *netdev, bool *miimon);
 271
 272     /* Retrieves current device stats for 'netdev' into 'stats'.
 273      *
 274      * A network device that supports some statistics but not others, it should
 275      * set the values of the unsupported statistics to all-1-bits
 276      * (UINT64_MAX). */
 277     int (*get_stats)(const struct netdev *netdev, struct netdev_stats *);
 278
 279     /* Sets the device stats for 'netdev' to 'stats'.
 280      *
 281      * Most network devices won't support this feature and will set this
 282      * function pointer to NULL, which is equivalent to returning EOPNOTSUPP.
 283      *
 284      * Some network devices might only allow setting their stats to 0. */
 285     int (*set_stats)(struct netdev *netdev, const struct netdev_stats *);
 286
 287     /* Stores the features supported by 'netdev' into each of '*current',
 288      * '*advertised', '*supported', and '*peer'.  Each value is a bitmap of
 289      * "enum ofp_port_features" bits, in host byte order.
 290      *
 291      * This function may be set to null if it would always return EOPNOTSUPP.
 292      */
 293     int (*get_features)(const struct netdev *netdev,
 294                         uint32_t *current, uint32_t *advertised,
 295                         uint32_t *supported, uint32_t *peer);
 296
 297     /* Set the features advertised by 'netdev' to 'advertise', which is a
 298      * bitmap of "enum ofp_port_features" bits, in host byte order.
 299      *
 300      * This function may be set to null for a network device that does not
 301      * support configuring advertisements. */
 302     int (*set_advertisements)(struct netdev *netdev, uint32_t advertise);
 303
 304     /* If 'netdev' is a VLAN network device (e.g. one created with vconfig(8)),
 305      * sets '*vlan_vid' to the VLAN VID associated with that device and returns
 306      * 0.
 307      *
 308      * Returns ENOENT if 'netdev' is a network device that is not a
 309      * VLAN device.
 310      *
 311      * This function should be set to null if it doesn't make any sense for
 312      * your network device (it probably doesn't). */
 313     int (*get_vlan_vid)(const struct netdev *netdev, int *vlan_vid);
 314
 315     /* Attempts to set input rate limiting (policing) policy, such that up to
 316      * 'kbits_rate' kbps of traffic is accepted, with a maximum accumulative
 317      * burst size of 'kbits' kb.
 318      *
 319      * This function may be set to null if policing is not supported. */
 320     int (*set_policing)(struct netdev *netdev, unsigned int kbits_rate,
 321                         unsigned int kbits_burst);
 322
 323     /* Adds to 'types' all of the forms of QoS supported by 'netdev', or leaves
 324      * it empty if 'netdev' does not support QoS.  Any names added to 'types'
 325      * should be documented as valid for the "type" column in the "QoS" table
 326      * in vswitchd/vswitch.xml (which is built as ovs-vswitchd.conf.db(8)).
 327      *
 328      * Every network device must support disabling QoS with a type of "", but
 329      * this function must not add "" to 'types'.
 330      *
 331      * The caller is responsible for initializing 'types' (e.g. with
 332      * svec_init()) before calling this function.  The caller takes ownership
 333      * of the strings added to 'types'.
 334      *
 335      * May be NULL if 'netdev' does not support QoS at all. */
 336     int (*get_qos_types)(const struct netdev *netdev, struct svec *types);
 337
 338     /* Queries 'netdev' for its capabilities regarding the specified 'type' of
 339      * QoS.  On success, initializes 'caps' with the QoS capabilities.
 340      *
 341      * Should return EOPNOTSUPP if 'netdev' does not support 'type'.  May be
 342      * NULL if 'netdev' does not support QoS at all. */
 343     int (*get_qos_capabilities)(const struct netdev *netdev,
 344                                 const char *type,
 345                                 struct netdev_qos_capabilities *caps);
 346
 347     /* Queries 'netdev' about its currently configured form of QoS.  If
 348      * successful, stores the name of the current form of QoS into '*typep'
 349      * and any details of configuration as string key-value pairs in
 350      * 'details'.
 351      *
 352      * A '*typep' of "" indicates that QoS is currently disabled on 'netdev'.
 353      *
 354      * The caller initializes 'details' before calling this function.  The
 355      * caller takes ownership of the string key-values pairs added to
 356      * 'details'.
 357      *
 358      * The netdev retains ownership of '*typep'.
 359      *
 360      * '*typep' will be one of the types returned by netdev_get_qos_types() for
 361      * 'netdev'.  The contents of 'details' should be documented as valid for
 362      * '*typep' in the "other_config" column in the "QoS" table in
 363      * vswitchd/vswitch.xml (which is built as ovs-vswitchd.conf.db(8)).
 364      *
 365      * May be NULL if 'netdev' does not support QoS at all. */
 366     int (*get_qos)(const struct netdev *netdev,
 367                    const char **typep, struct shash *details);
 368
 369     /* Attempts to reconfigure QoS on 'netdev', changing the form of QoS to
 370      * 'type' with details of configuration from 'details'.
 371      *
 372      * On error, the previous QoS configuration is retained.
 373      *
 374      * When this function changes the type of QoS (not just 'details'), this
 375      * also resets all queue configuration for 'netdev' to their defaults
 376      * (which depend on the specific type of QoS).  Otherwise, the queue
 377      * configuration for 'netdev' is unchanged.
 378      *
 379      * 'type' should be "" (to disable QoS) or one of the types returned by
 380      * netdev_get_qos_types() for 'netdev'.  The contents of 'details' should
 381      * be documented as valid for the given 'type' in the "other_config" column
 382      * in the "QoS" table in vswitchd/vswitch.xml (which is built as
 383      * ovs-vswitchd.conf.db(8)).
 384      *
 385      * May be NULL if 'netdev' does not support QoS at all. */
 386     int (*set_qos)(struct netdev *netdev,
 387                    const char *type, const struct shash *details);
 388
 389     /* Queries 'netdev' for information about the queue numbered 'queue_id'.
 390      * If successful, adds that information as string key-value pairs to
 391      * 'details'.  Returns 0 if successful, otherwise a positive errno value.
 392      *
 393      * Should return EINVAL if 'queue_id' is greater than or equal to the
 394      * number of supported queues (as reported in the 'n_queues' member of
 395      * struct netdev_qos_capabilities by 'get_qos_capabilities').
 396      *
 397      * The caller initializes 'details' before calling this function.  The
 398      * caller takes ownership of the string key-values pairs added to
 399      * 'details'.
 400      *
 401      * The returned contents of 'details' should be documented as valid for the
 402      * given 'type' in the "other_config" column in the "Queue" table in
 403      * vswitchd/vswitch.xml (which is built as ovs-vswitchd.conf.db(8)).
 404      */
 405     int (*get_queue)(const struct netdev *netdev,
 406                      unsigned int queue_id, struct shash *details);
 407
 408     /* Configures the queue numbered 'queue_id' on 'netdev' with the key-value
 409      * string pairs in 'details'.  The contents of 'details' should be
 410      * documented as valid for the given 'type' in the "other_config" column in
 411      * the "Queue" table in vswitchd/vswitch.xml (which is built as
 412      * ovs-vswitchd.conf.db(8)).  Returns 0 if successful, otherwise a positive
 413      * errno value.  On failure, the given queue's configuration should be
 414      * unmodified.
 415      *
 416      * Should return EINVAL if 'queue_id' is greater than or equal to the
 417      * number of supported queues (as reported in the 'n_queues' member of
 418      * struct netdev_qos_capabilities by 'get_qos_capabilities'), or if
 419      * 'details' is invalid for the type of queue.
 420      *
 421      * This function does not modify 'details', and the caller retains
 422      * ownership of it.
 423      *
 424      * May be NULL if 'netdev' does not support QoS at all. */
 425     int (*set_queue)(struct netdev *netdev,
 426                      unsigned int queue_id, const struct shash *details);
 427
 428     /* Attempts to delete the queue numbered 'queue_id' from 'netdev'.
 429      *
 430      * Should return EINVAL if 'queue_id' is greater than or equal to the
 431      * number of supported queues (as reported in the 'n_queues' member of
 432      * struct netdev_qos_capabilities by 'get_qos_capabilities').  Should
 433      * return EOPNOTSUPP if 'queue_id' is valid but may not be deleted (e.g. if
 434      * 'netdev' has a fixed set of queues with the current QoS mode).
 435      *
 436      * May be NULL if 'netdev' does not support QoS at all, or if all of its
 437      * QoS modes have fixed sets of queues. */
 438     int (*delete_queue)(struct netdev *netdev, unsigned int queue_id);
 439
 440     /* Obtains statistics about 'queue_id' on 'netdev'.  Fills 'stats' with the
 441      * queue's statistics.  May set individual members of 'stats' to all-1-bits
 442      * if the statistic is unavailable.
 443      *
 444      * May be NULL if 'netdev' does not support QoS at all. */
 445     int (*get_queue_stats)(const struct netdev *netdev, unsigned int queue_id,
 446                            struct netdev_queue_stats *stats);
 447
 448     /* Iterates over all of 'netdev''s queues, calling 'cb' with the queue's
 449      * ID, its configuration, and the 'aux' specified by the caller.  The order
 450      * of iteration is unspecified, but (when successful) each queue is visited
 451      * exactly once.
 452      *
 453      * 'cb' will not modify or free the 'details' argument passed in. */
 454     int (*dump_queues)(const struct netdev *netdev,
 455                        void (*cb)(unsigned int queue_id,
 456                                   const struct shash *details,
 457                                   void *aux),
 458                        void *aux);
 459
 460     /* Iterates over all of 'netdev''s queues, calling 'cb' with the queue's
 461      * ID, its statistics, and the 'aux' specified by the caller.  The order of
 462      * iteration is unspecified, but (when successful) each queue must be
 463      * visited exactly once.
 464      *
 465      * 'cb' will not modify or free the statistics passed in. */
 466     int (*dump_queue_stats)(const struct netdev *netdev,
 467                             void (*cb)(unsigned int queue_id,
 468                                        struct netdev_queue_stats *,
 469                                        void *aux),
 470                             void *aux);
 471
 472     /* If 'netdev' has an assigned IPv4 address, sets '*address' to that
 473      * address and '*netmask' to the associated netmask.
 474      *
 475      * The following error values have well-defined meanings:
 476      *
 477      *   - EADDRNOTAVAIL: 'netdev' has no assigned IPv4 address.
 478      *
 479      *   - EOPNOTSUPP: No IPv4 network stack attached to 'netdev'.
 480      *
 481      * This function may be set to null if it would always return EOPNOTSUPP
 482      * anyhow. */
 483     int (*get_in4)(const struct netdev *netdev, struct in_addr *address,
 484                    struct in_addr *netmask);
 485
 486     /* Assigns 'addr' as 'netdev''s IPv4 address and 'mask' as its netmask.  If
 487      * 'addr' is INADDR_ANY, 'netdev''s IPv4 address is cleared.
 488      *
 489      * This function may be set to null if it would always return EOPNOTSUPP
 490      * anyhow. */
 491     int (*set_in4)(struct netdev *netdev, struct in_addr addr,
 492                    struct in_addr mask);
 493
 494     /* If 'netdev' has an assigned IPv6 address, sets '*in6' to that address.
 495      *
 496      * The following error values have well-defined meanings:
 497      *
 498      *   - EADDRNOTAVAIL: 'netdev' has no assigned IPv6 address.
 499      *
 500      *   - EOPNOTSUPP: No IPv6 network stack attached to 'netdev'.
 501      *
 502      * This function may be set to null if it would always return EOPNOTSUPP
 503      * anyhow. */
 504     int (*get_in6)(const struct netdev *netdev, struct in6_addr *in6);
 505
 506     /* Adds 'router' as a default IP gateway for the TCP/IP stack that
 507      * corresponds to 'netdev'.
 508      *
 509      * This function may be set to null if it would always return EOPNOTSUPP
 510      * anyhow. */
 511     int (*add_router)(struct netdev *netdev, struct in_addr router);
 512
 513     /* Looks up the next hop for 'host'.  If succesful, stores the next hop
 514      * gateway's address (0 if 'host' is on a directly connected network) in
 515      * '*next_hop' and a copy of the name of the device to reach 'host' in
 516      * '*netdev_name', and returns 0.  The caller is responsible for freeing
 517      * '*netdev_name' (by calling free()).
 518      *
 519      * This function may be set to null if it would always return EOPNOTSUPP
 520      * anyhow. */
 521     int (*get_next_hop)(const struct in_addr *host, struct in_addr *next_hop,
 522                         char **netdev_name);
 523
 524     /* Retrieves the status of the device.
 525      *
 526      * Populates 'sh' with key-value pairs representing the status of the
 527      * device.  A device's status is a set of key-value string pairs
 528      * representing netdev type specific information.  For more information see
 529      * ovs-vswitchd.conf.db(5).
 530      *
 531      * The data of 'sh' are heap allocated strings which the caller is
 532      * responsible for deallocating.
 533      *
 534      * This function may be set to null if it would always return EOPNOTSUPP
 535      * anyhow. */
 536     int (*get_status)(const struct netdev *netdev, struct shash *sh);
 537
 538     /* Looks up the ARP table entry for 'ip' on 'netdev' and stores the
 539      * corresponding MAC address in 'mac'.  A return value of ENXIO, in
 540      * particular, indicates that there is no ARP table entry for 'ip' on
 541      * 'netdev'.
 542      *
 543      * This function may be set to null if it would always return EOPNOTSUPP
 544      * anyhow. */
 545     int (*arp_lookup)(const struct netdev *netdev, uint32_t ip, uint8_t mac[6]);
 546
 547     /* Retrieves the current set of flags on 'netdev' into '*old_flags'.
 548      * Then, turns off the flags that are set to 1 in 'off' and turns on the
 549      * flags that are set to 1 in 'on'.  (No bit will be set to 1 in both 'off'
 550      * and 'on'; that is, off & on == 0.)
 551      *
 552      * This function may be invoked from a signal handler.  Therefore, it
 553      * should not do anything that is not signal-safe (such as logging). */
 554     int (*update_flags)(struct netdev *netdev, enum netdev_flags off,
 555                         enum netdev_flags on, enum netdev_flags *old_flags);
 556
 557     /* Arranges for 'cb' to be called whenever one of the attributes of
 558      * 'netdev' changes and sets '*notifierp' to a newly created
 559      * netdev_notifier that represents this arrangement.  The created notifier
 560      * will have its 'netdev', 'cb', and 'aux' members set to the values of the
 561      * corresponding parameters. */
 562     int (*poll_add)(struct netdev *netdev,
 563                     void (*cb)(struct netdev_notifier *notifier), void *aux,
 564                     struct netdev_notifier **notifierp);
 565
 566     /* Cancels poll notification for 'notifier'. */
 567     void (*poll_remove)(struct netdev_notifier *notifier);
 568 };
 569
 570 int netdev_register_provider(const struct netdev_class *);
 571 int netdev_unregister_provider(const char *type);
 572 const struct netdev_class *netdev_lookup_provider(const char *type);
 573
 574 extern const struct netdev_class netdev_linux_class;
 575 extern const struct netdev_class netdev_internal_class;
 576 extern const struct netdev_class netdev_tap_class;
 577
 578 #ifdef  __cplusplus
 579 }
 580 #endif
 581
 582 #endif /* netdev.h */