lib/netdev-provider.h

   1 /*
   2  * Copyright (c) 2009, 2010, 2011 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 prevent the
 179      * network device from being usefully used by the netdev-based "userspace
 180      * datapath".) */
 181     int (*recv)(struct netdev *netdev, void *buffer, size_t size);
 182
 183     /* Registers with the poll loop to wake up from the next call to
 184      * poll_block() when a packet is ready to be received with netdev_recv() on
 185      * 'netdev'.
 186      *
 187      * May be null if not needed, such as for a network device that does not
 188      * implement packet reception through the 'recv' member function. */
 189     void (*recv_wait)(struct netdev *netdev);
 190
 191     /* Discards all packets waiting to be received from 'netdev'.
 192      *
 193      * May be null if not needed, such as for a network device that does not
 194      * implement packet reception through the 'recv' member function. */
 195     int (*drain)(struct netdev *netdev);
 196
 197     /* Sends the 'size'-byte packet in 'buffer' on 'netdev'.  Returns 0 if
 198      * successful, otherwise a positive errno value.  Returns EAGAIN without
 199      * blocking if the packet cannot be queued immediately.  Returns EMSGSIZE
 200      * if a partial packet was transmitted or if the packet is too big or too
 201      * small to transmit on the device.
 202      *
 203      * The caller retains ownership of 'buffer' in all cases.
 204      *
 205      * The network device is expected to maintain a packet transmission queue,
 206      * so that the caller does not ordinarily have to do additional queuing of
 207      * packets.
 208      *
 209      * May return EOPNOTSUPP if a network device does not implement packet
 210      * transmission through this interface.  This function may be set to null
 211      * if it would always return EOPNOTSUPP anyhow.  (This will prevent the
 212      * network device from being usefully used by the netdev-based "userspace
 213      * datapath".) */
 214     int (*send)(struct netdev *netdev, const void *buffer, size_t size);
 215
 216     /* Registers with the poll loop to wake up from the next call to
 217      * poll_block() when the packet transmission queue for 'netdev' has
 218      * sufficient room to transmit a packet with netdev_send().
 219      *
 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
 222      * packets.  Thus, this function is unlikely to ever be useful.
 223      *
 224      * May be null if not needed, such as for a network device that does not
 225      * implement packet transmission through the 'send' member function. */
 226     void (*send_wait)(struct netdev *netdev);
 227
 228     /* Sets 'netdev''s Ethernet address to 'mac' */
 229     int (*set_etheraddr)(struct netdev *netdev, const uint8_t mac[6]);
 230
 231     /* Retrieves 'netdev''s Ethernet address into 'mac'. */
 232     int (*get_etheraddr)(const struct netdev *netdev, uint8_t mac[6]);
 233
 234     /* Retrieves 'netdev''s MTU into '*mtup'.
 235      *
 236      * The MTU is the maximum size of transmitted (and received) packets, in
 237      * bytes, not including the hardware header; thus, this is typically 1500
 238      * bytes for Ethernet devices.
 239      *
 240      * If 'netdev' does not have an MTU (e.g. as some tunnels do not), then
 241      * this function should set '*mtup' to INT_MAX. */
 242     int (*get_mtu)(const struct netdev *netdev, int *mtup);
 243
 244     /* Returns the ifindex of 'netdev', if successful, as a positive number.
 245      * On failure, returns a negative errno value.
 246      *
 247      * The desired semantics of the ifindex value are a combination of those
 248      * specified by POSIX for if_nametoindex() and by SNMP for ifIndex.  An
 249      * ifindex value should be unique within a host and remain stable at least
 250      * until reboot.  SNMP says an ifindex "ranges between 1 and the value of
 251      * ifNumber" but many systems do not follow this rule anyhow.
 252      *
 253      * This function may be set to null if it would always return -EOPNOTSUPP.
 254      */
 255     int (*get_ifindex)(const struct netdev *netdev);
 256
 257     /* Sets 'carrier' to true if carrier is active (link light is on) on
 258      * 'netdev'.
 259      *
 260      * May be null if device does not provide carrier status (will be always
 261      * up as long as device is up).
 262      */
 263     int (*get_carrier)(const struct netdev *netdev, bool *carrier);
 264
 265     /* Sets 'miimon' to true if 'netdev' is up according to its MII.  If
 266      * 'netdev' does not support MII, may fall back to another method or return
 267      * EOPNOTSUPP.
 268      *
 269      * This function may be set to null if it would always return EOPNOTSUPP.
 270      */
 271     int (*get_miimon)(const struct netdev *netdev, bool *miimon);
 272
 273     /* Retrieves current device stats for 'netdev' into 'stats'.
 274      *
 275      * A network device that supports some statistics but not others, it should
 276      * set the values of the unsupported statistics to all-1-bits
 277      * (UINT64_MAX). */
 278     int (*get_stats)(const struct netdev *netdev, struct netdev_stats *);
 279
 280     /* Sets the device stats for 'netdev' to 'stats'.
 281      *
 282      * Most network devices won't support this feature and will set this
 283      * function pointer to NULL, which is equivalent to returning EOPNOTSUPP.
 284      *
 285      * Some network devices might only allow setting their stats to 0. */
 286     int (*set_stats)(struct netdev *netdev, const struct netdev_stats *);
 287
 288     /* Stores the features supported by 'netdev' into each of '*current',
 289      * '*advertised', '*supported', and '*peer'.  Each value is a bitmap of
 290      * "enum ofp_port_features" bits, in host byte order.
 291      *
 292      * This function may be set to null if it would always return EOPNOTSUPP.
 293      */
 294     int (*get_features)(const struct netdev *netdev,
 295                         uint32_t *current, uint32_t *advertised,
 296                         uint32_t *supported, uint32_t *peer);
 297
 298     /* Set the features advertised by 'netdev' to 'advertise', which is a
 299      * bitmap of "enum ofp_port_features" bits, in host byte order.
 300      *
 301      * This function may be set to null for a network device that does not
 302      * support configuring advertisements. */
 303     int (*set_advertisements)(struct netdev *netdev, uint32_t advertise);
 304
 305     /* If 'netdev' is a VLAN network device (e.g. one created with vconfig(8)),
 306      * sets '*vlan_vid' to the VLAN VID associated with that device and returns
 307      * 0.
 308      *
 309      * Returns ENOENT if 'netdev' is a network device that is not a
 310      * VLAN device.
 311      *
 312      * This function should be set to null if it doesn't make any sense for
 313      * your network device (it probably doesn't). */
 314     int (*get_vlan_vid)(const struct netdev *netdev, int *vlan_vid);
 315
 316     /* Attempts to set input rate limiting (policing) policy, such that up to
 317      * 'kbits_rate' kbps of traffic is accepted, with a maximum accumulative
 318      * burst size of 'kbits' kb.
 319      *
 320      * This function may be set to null if policing is not supported. */
 321     int (*set_policing)(struct netdev *netdev, unsigned int kbits_rate,
 322                         unsigned int kbits_burst);
 323
 324     /* Adds to 'types' all of the forms of QoS supported by 'netdev', or leaves
 325      * it empty if 'netdev' does not support QoS.  Any names added to 'types'
 326      * should be documented as valid for the "type" column in the "QoS" table
 327      * in vswitchd/vswitch.xml (which is built as ovs-vswitchd.conf.db(8)).
 328      *
 329      * Every network device must support disabling QoS with a type of "", but
 330      * this function must not add "" to 'types'.
 331      *
 332      * The caller is responsible for initializing 'types' (e.g. with
 333      * svec_init()) before calling this function.  The caller takes ownership
 334      * of the strings added to 'types'.
 335      *
 336      * May be NULL if 'netdev' does not support QoS at all. */
 337     int (*get_qos_types)(const struct netdev *netdev, struct svec *types);
 338
 339     /* Queries 'netdev' for its capabilities regarding the specified 'type' of
 340      * QoS.  On success, initializes 'caps' with the QoS capabilities.
 341      *
 342      * Should return EOPNOTSUPP if 'netdev' does not support 'type'.  May be
 343      * NULL if 'netdev' does not support QoS at all. */
 344     int (*get_qos_capabilities)(const struct netdev *netdev,
 345                                 const char *type,
 346                                 struct netdev_qos_capabilities *caps);
 347
 348     /* Queries 'netdev' about its currently configured form of QoS.  If
 349      * successful, stores the name of the current form of QoS into '*typep'
 350      * and any details of configuration as string key-value pairs in
 351      * 'details'.
 352      *
 353      * A '*typep' of "" indicates that QoS is currently disabled on 'netdev'.
 354      *
 355      * The caller initializes 'details' before calling this function.  The
 356      * caller takes ownership of the string key-values pairs added to
 357      * 'details'.
 358      *
 359      * The netdev retains ownership of '*typep'.
 360      *
 361      * '*typep' will be one of the types returned by netdev_get_qos_types() for
 362      * 'netdev'.  The contents of 'details' should be documented as valid for
 363      * '*typep' in the "other_config" column in the "QoS" table in
 364      * vswitchd/vswitch.xml (which is built as ovs-vswitchd.conf.db(8)).
 365      *
 366      * May be NULL if 'netdev' does not support QoS at all. */
 367     int (*get_qos)(const struct netdev *netdev,
 368                    const char **typep, struct shash *details);
 369
 370     /* Attempts to reconfigure QoS on 'netdev', changing the form of QoS to
 371      * 'type' with details of configuration from 'details'.
 372      *
 373      * On error, the previous QoS configuration is retained.
 374      *
 375      * When this function changes the type of QoS (not just 'details'), this
 376      * also resets all queue configuration for 'netdev' to their defaults
 377      * (which depend on the specific type of QoS).  Otherwise, the queue
 378      * configuration for 'netdev' is unchanged.
 379      *
 380      * 'type' should be "" (to disable QoS) or one of the types returned by
 381      * netdev_get_qos_types() for 'netdev'.  The contents of 'details' should
 382      * be documented as valid for the given 'type' in the "other_config" column
 383      * in the "QoS" table in vswitchd/vswitch.xml (which is built as
 384      * ovs-vswitchd.conf.db(8)).
 385      *
 386      * May be NULL if 'netdev' does not support QoS at all. */
 387     int (*set_qos)(struct netdev *netdev,
 388                    const char *type, const struct shash *details);
 389
 390     /* Queries 'netdev' for information about the queue numbered 'queue_id'.
 391      * If successful, adds that information as string key-value pairs to
 392      * 'details'.  Returns 0 if successful, otherwise a positive errno value.
 393      *
 394      * Should return EINVAL if 'queue_id' is greater than or equal to the
 395      * number of supported queues (as reported in the 'n_queues' member of
 396      * struct netdev_qos_capabilities by 'get_qos_capabilities').
 397      *
 398      * The caller initializes 'details' before calling this function.  The
 399      * caller takes ownership of the string key-values pairs added to
 400      * 'details'.
 401      *
 402      * The returned contents of 'details' should be documented as valid for the
 403      * given 'type' in the "other_config" column in the "Queue" table in
 404      * vswitchd/vswitch.xml (which is built as ovs-vswitchd.conf.db(8)).
 405      */
 406     int (*get_queue)(const struct netdev *netdev,
 407                      unsigned int queue_id, struct shash *details);
 408
 409     /* Configures the queue numbered 'queue_id' on 'netdev' with the key-value
 410      * string pairs in 'details'.  The contents of 'details' should be
 411      * documented as valid for the given 'type' in the "other_config" column in
 412      * the "Queue" table in vswitchd/vswitch.xml (which is built as
 413      * ovs-vswitchd.conf.db(8)).  Returns 0 if successful, otherwise a positive
 414      * errno value.  On failure, the given queue's configuration should be
 415      * unmodified.
 416      *
 417      * Should return EINVAL if 'queue_id' is greater than or equal to the
 418      * number of supported queues (as reported in the 'n_queues' member of
 419      * struct netdev_qos_capabilities by 'get_qos_capabilities'), or if
 420      * 'details' is invalid for the type of queue.
 421      *
 422      * This function does not modify 'details', and the caller retains
 423      * ownership of it.
 424      *
 425      * May be NULL if 'netdev' does not support QoS at all. */
 426     int (*set_queue)(struct netdev *netdev,
 427                      unsigned int queue_id, const struct shash *details);
 428
 429     /* Attempts to delete the queue numbered 'queue_id' from 'netdev'.
 430      *
 431      * Should return EINVAL if 'queue_id' is greater than or equal to the
 432      * number of supported queues (as reported in the 'n_queues' member of
 433      * struct netdev_qos_capabilities by 'get_qos_capabilities').  Should
 434      * return EOPNOTSUPP if 'queue_id' is valid but may not be deleted (e.g. if
 435      * 'netdev' has a fixed set of queues with the current QoS mode).
 436      *
 437      * May be NULL if 'netdev' does not support QoS at all, or if all of its
 438      * QoS modes have fixed sets of queues. */
 439     int (*delete_queue)(struct netdev *netdev, unsigned int queue_id);
 440
 441     /* Obtains statistics about 'queue_id' on 'netdev'.  Fills 'stats' with the
 442      * queue's statistics.  May set individual members of 'stats' to all-1-bits
 443      * if the statistic is unavailable.
 444      *
 445      * May be NULL if 'netdev' does not support QoS at all. */
 446     int (*get_queue_stats)(const struct netdev *netdev, unsigned int queue_id,
 447                            struct netdev_queue_stats *stats);
 448
 449     /* Iterates over all of 'netdev''s queues, calling 'cb' with the queue's
 450      * ID, its configuration, and the 'aux' specified by the caller.  The order
 451      * of iteration is unspecified, but (when successful) each queue is visited
 452      * exactly once.
 453      *
 454      * 'cb' will not modify or free the 'details' argument passed in. */
 455     int (*dump_queues)(const struct netdev *netdev,
 456                        void (*cb)(unsigned int queue_id,
 457                                   const struct shash *details,
 458                                   void *aux),
 459                        void *aux);
 460
 461     /* Iterates over all of 'netdev''s queues, calling 'cb' with the queue's
 462      * ID, its statistics, and the 'aux' specified by the caller.  The order of
 463      * iteration is unspecified, but (when successful) each queue must be
 464      * visited exactly once.
 465      *
 466      * 'cb' will not modify or free the statistics passed in. */
 467     int (*dump_queue_stats)(const struct netdev *netdev,
 468                             void (*cb)(unsigned int queue_id,
 469                                        struct netdev_queue_stats *,
 470                                        void *aux),
 471                             void *aux);
 472
 473     /* If 'netdev' has an assigned IPv4 address, sets '*address' to that
 474      * address and '*netmask' to the associated netmask.
 475      *
 476      * The following error values have well-defined meanings:
 477      *
 478      *   - EADDRNOTAVAIL: 'netdev' has no assigned IPv4 address.
 479      *
 480      *   - EOPNOTSUPP: No IPv4 network stack attached to 'netdev'.
 481      *
 482      * This function may be set to null if it would always return EOPNOTSUPP
 483      * anyhow. */
 484     int (*get_in4)(const struct netdev *netdev, struct in_addr *address,
 485                    struct in_addr *netmask);
 486
 487     /* Assigns 'addr' as 'netdev''s IPv4 address and 'mask' as its netmask.  If
 488      * 'addr' is INADDR_ANY, 'netdev''s IPv4 address is cleared.
 489      *
 490      * This function may be set to null if it would always return EOPNOTSUPP
 491      * anyhow. */
 492     int (*set_in4)(struct netdev *netdev, struct in_addr addr,
 493                    struct in_addr mask);
 494
 495     /* If 'netdev' has an assigned IPv6 address, sets '*in6' to that address.
 496      *
 497      * The following error values have well-defined meanings:
 498      *
 499      *   - EADDRNOTAVAIL: 'netdev' has no assigned IPv6 address.
 500      *
 501      *   - EOPNOTSUPP: No IPv6 network stack attached to 'netdev'.
 502      *
 503      * This function may be set to null if it would always return EOPNOTSUPP
 504      * anyhow. */
 505     int (*get_in6)(const struct netdev *netdev, struct in6_addr *in6);
 506
 507     /* Adds 'router' as a default IP gateway for the TCP/IP stack that
 508      * corresponds to 'netdev'.
 509      *
 510      * This function may be set to null if it would always return EOPNOTSUPP
 511      * anyhow. */
 512     int (*add_router)(struct netdev *netdev, struct in_addr router);
 513
 514     /* Looks up the next hop for 'host'.  If succesful, stores the next hop
 515      * gateway's address (0 if 'host' is on a directly connected network) in
 516      * '*next_hop' and a copy of the name of the device to reach 'host' in
 517      * '*netdev_name', and returns 0.  The caller is responsible for freeing
 518      * '*netdev_name' (by calling free()).
 519      *
 520      * This function may be set to null if it would always return EOPNOTSUPP
 521      * anyhow. */
 522     int (*get_next_hop)(const struct in_addr *host, struct in_addr *next_hop,
 523                         char **netdev_name);
 524
 525     /* Retrieves the status of the device.
 526      *
 527      * Populates 'sh' with key-value pairs representing the status of the
 528      * device.  A device's status is a set of key-value string pairs
 529      * representing netdev type specific information.  For more information see
 530      * ovs-vswitchd.conf.db(5).
 531      *
 532      * The data of 'sh' are heap allocated strings which the caller is
 533      * responsible for deallocating.
 534      *
 535      * This function may be set to null if it would always return EOPNOTSUPP
 536      * anyhow. */
 537     int (*get_status)(const struct netdev *netdev, struct shash *sh);
 538
 539     /* Looks up the ARP table entry for 'ip' on 'netdev' and stores the
 540      * corresponding MAC address in 'mac'.  A return value of ENXIO, in
 541      * particular, indicates that there is no ARP table entry for 'ip' on
 542      * 'netdev'.
 543      *
 544      * This function may be set to null if it would always return EOPNOTSUPP
 545      * anyhow. */
 546     int (*arp_lookup)(const struct netdev *netdev, uint32_t ip, uint8_t mac[6]);
 547
 548     /* Retrieves the current set of flags on 'netdev' into '*old_flags'.
 549      * Then, turns off the flags that are set to 1 in 'off' and turns on the
 550      * flags that are set to 1 in 'on'.  (No bit will be set to 1 in both 'off'
 551      * and 'on'; that is, off & on == 0.)
 552      *
 553      * This function may be invoked from a signal handler.  Therefore, it
 554      * should not do anything that is not signal-safe (such as logging). */
 555     int (*update_flags)(struct netdev *netdev, enum netdev_flags off,
 556                         enum netdev_flags on, enum netdev_flags *old_flags);
 557
 558     /* Arranges for 'cb' to be called whenever one of the attributes of
 559      * 'netdev' changes and sets '*notifierp' to a newly created
 560      * netdev_notifier that represents this arrangement.  The created notifier
 561      * will have its 'netdev', 'cb', and 'aux' members set to the values of the
 562      * corresponding parameters. */
 563     int (*poll_add)(struct netdev *netdev,
 564                     void (*cb)(struct netdev_notifier *notifier), void *aux,
 565                     struct netdev_notifier **notifierp);
 566
 567     /* Cancels poll notification for 'notifier'. */
 568     void (*poll_remove)(struct netdev_notifier *notifier);
 569 };
 570
 571 int netdev_register_provider(const struct netdev_class *);
 572 int netdev_unregister_provider(const char *type);
 573 const struct netdev_class *netdev_lookup_provider(const char *type);
 574
 575 extern const struct netdev_class netdev_linux_class;
 576 extern const struct netdev_class netdev_internal_class;
 577 extern const struct netdev_class netdev_tap_class;
 578
 579 #ifdef  __cplusplus
 580 }
 581 #endif
 582
 583 #endif /* netdev.h */