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 };
  43
  44 void netdev_dev_init(struct netdev_dev *, const char *name,
  45                      const struct netdev_class *);
  46 void netdev_dev_uninit(struct netdev_dev *, bool destroy);
  47 const char *netdev_dev_get_type(const struct netdev_dev *);
  48 const struct netdev_class *netdev_dev_get_class(const struct netdev_dev *);
  49 const char *netdev_dev_get_name(const struct netdev_dev *);
  50 struct netdev_dev *netdev_dev_from_name(const char *name);
  51 void netdev_dev_get_devices(const struct netdev_class *,
  52                             struct shash *device_list);
  53
  54 static inline void netdev_dev_assert_class(const struct netdev_dev *netdev_dev,
  55                                            const struct netdev_class *class_)
  56 {
  57     assert(netdev_dev->netdev_class == class_);
  58 }
  59
  60 /* A instance of an open network device.
  61  *
  62  * This structure should be treated as opaque by network device
  63  * implementations. */
  64 struct netdev {
  65     struct netdev_dev *netdev_dev;   /* Parent netdev_dev. */
  66     struct list node;                /* Element in global list. */
  67
  68     enum netdev_flags save_flags;    /* Initial device flags. */
  69     enum netdev_flags changed_flags; /* Flags that we changed. */
  70 };
  71
  72 void netdev_init(struct netdev *, struct netdev_dev *);
  73 void netdev_uninit(struct netdev *, bool close);
  74 struct netdev_dev *netdev_get_dev(const struct netdev *);
  75
  76 static inline void netdev_assert_class(const struct netdev *netdev,
  77                                        const struct netdev_class *netdev_class)
  78 {
  79     netdev_dev_assert_class(netdev_get_dev(netdev), netdev_class);
  80 }
  81
  82 /* Network device class structure, to be defined by each implementation of a
  83  * network device.
  84  *
  85  * These functions return 0 if successful or a positive errno value on failure,
  86  * except where otherwise noted. */
  87 struct netdev_class {
  88     /* Type of netdevs in this class, e.g. "system", "tap", "gre", etc.
  89      *
  90      * One of the providers should supply a "system" type, since this is
  91      * the type assumed if no type is specified when opening a netdev.
  92      * The "system" type corresponds to an existing network device on
  93      * the system. */
  94     const char *type;
  95
  96     /* Called when the netdev provider is registered, typically at program
  97      * startup.  Returning an error from this function will prevent any network
  98      * device in this class from being opened.
  99      *
 100      * This function may be set to null if a network device class needs no
 101      * initialization at registration time. */
 102     int (*init)(void);
 103
 104     /* Performs periodic work needed by netdevs of this class.  May be null if
 105      * no periodic work is necessary. */
 106     void (*run)(void);
 107
 108     /* Arranges for poll_block() to wake up if the "run" member function needs
 109      * to be called.  Implementations are additionally required to wake
 110      * whenever something changes in any of its netdevs which would cause their
 111      * ->change_seq() function to change its result.  May be null if nothing is
 112      * needed here. */
 113     void (*wait)(void);
 114
 115     /* Attempts to create a network device named 'name' in 'netdev_class'.  On
 116      * success sets 'netdev_devp' to the newly created device. */
 117     int (*create)(const struct netdev_class *netdev_class, const char *name,
 118                   struct netdev_dev **netdev_devp);
 119
 120     /* Destroys 'netdev_dev'.
 121      *
 122      * Netdev devices maintain a reference count that is incremented on
 123      * netdev_open() and decremented on netdev_close().  If 'netdev_dev'
 124      * has a non-zero reference count, then this function will not be
 125      * called. */
 126     void (*destroy)(struct netdev_dev *netdev_dev);
 127
 128     /* Fetches the device 'netdev_dev''s configuration, storing it in 'args'.
 129      * The caller owns 'args' and pre-initializes it to an empty shash.
 130      *
 131      * If this netdev class does not have any configuration options, this may
 132      * be a null pointer. */
 133     int (*get_config)(struct netdev_dev *netdev_dev, struct shash *args);
 134
 135     /* Changes the device 'netdev_dev''s configuration to 'args'.
 136      *
 137      * If this netdev class does not support configuration, this may be a null
 138      * pointer. */
 139     int (*set_config)(struct netdev_dev *netdev_dev, const struct shash *args);
 140
 141     /* Attempts to open a network device.  On success, sets 'netdevp'
 142      * to the new network device. */
 143     int (*open)(struct netdev_dev *netdev_dev, struct netdev **netdevp);
 144
 145     /* Closes 'netdev'. */
 146     void (*close)(struct netdev *netdev);
 147 \f
 148 /* ## ----------------- ## */
 149 /* ## Receiving Packets ## */
 150 /* ## ----------------- ## */
 151
 152 /* The network provider interface is mostly used for inspecting and configuring
 153  * device "metadata", not for sending and receiving packets directly.  It may
 154  * be impractical to implement these functions on some operating systems and
 155  * hardware.  These functions may all be NULL in such cases.
 156  *
 157  * (However, the "dpif-netdev" implementation, which is the easiest way to
 158  * integrate Open vSwitch with a new operating system or hardware, does require
 159  * the ability to receive packets.) */
 160
 161     /* Attempts to set up 'netdev' for receiving packets with ->recv().
 162      * Returns 0 if successful, otherwise a positive errno value.  Return
 163      * EOPNOTSUPP to indicate that the network device does not implement packet
 164      * reception through this interface.  This function may be set to null if
 165      * it would always return EOPNOTSUPP anyhow.  (This will prevent the
 166      * network device from being usefully used by the netdev-based "userspace
 167      * datapath".)*/
 168     int (*listen)(struct netdev *netdev);
 169
 170     /* Attempts to receive a packet from 'netdev' into the 'size' bytes in
 171      * 'buffer'.  If successful, returns the number of bytes in the received
 172      * packet, otherwise a negative errno value.  Returns -EAGAIN immediately
 173      * if no packet is ready to be received.
 174      *
 175      * Returns -EMSGSIZE, and discards the packet, if the received packet is
 176      * longer than 'size' bytes.
 177      *
 178      * This function can only be expected to return a packet if ->listen() has
 179      * been called successfully.
 180      *
 181      * May be null if not needed, such as for a network device that does not
 182      * implement packet reception through the 'recv' member function. */
 183     int (*recv)(struct netdev *netdev, void *buffer, size_t size);
 184
 185     /* Registers with the poll loop to wake up from the next call to
 186      * poll_block() when a packet is ready to be received with netdev_recv() on
 187      * 'netdev'.
 188      *
 189      * May be null if not needed, such as for a network device that does not
 190      * implement packet reception through the 'recv' member function. */
 191     void (*recv_wait)(struct netdev *netdev);
 192
 193     /* Discards all packets waiting to be received from 'netdev'.
 194      *
 195      * May be null if not needed, such as for a network device that does not
 196      * implement packet reception through the 'recv' member function. */
 197     int (*drain)(struct netdev *netdev);
 198 \f
 199     /* Sends the 'size'-byte packet in 'buffer' on 'netdev'.  Returns 0 if
 200      * successful, otherwise a positive errno value.  Returns EAGAIN without
 201      * blocking if the packet cannot be queued immediately.  Returns EMSGSIZE
 202      * if a partial packet was transmitted or if the packet is too big or too
 203      * small to transmit on the device.
 204      *
 205      * The caller retains ownership of 'buffer' in all cases.
 206      *
 207      * The network device is expected to maintain a packet transmission queue,
 208      * so that the caller does not ordinarily have to do additional queuing of
 209      * packets.
 210      *
 211      * May return EOPNOTSUPP if a network device does not implement packet
 212      * transmission through this interface.  This function may be set to null
 213      * if it would always return EOPNOTSUPP anyhow.  (This will prevent the
 214      * network device from being usefully used by the netdev-based "userspace
 215      * datapath".  It will also prevent the OVS implementation of bonding from
 216      * working properly over 'netdev'.) */
 217     int (*send)(struct netdev *netdev, const void *buffer, size_t size);
 218
 219     /* Registers with the poll loop to wake up from the next call to
 220      * poll_block() when the packet transmission queue for 'netdev' has
 221      * sufficient room to transmit a packet with netdev_send().
 222      *
 223      * The network device is expected to maintain a packet transmission queue,
 224      * so that the caller does not ordinarily have to do additional queuing of
 225      * packets.  Thus, this function is unlikely to ever be useful.
 226      *
 227      * May be null if not needed, such as for a network device that does not
 228      * implement packet transmission through the 'send' member function. */
 229     void (*send_wait)(struct netdev *netdev);
 230
 231     /* Sets 'netdev''s Ethernet address to 'mac' */
 232     int (*set_etheraddr)(struct netdev *netdev, const uint8_t mac[6]);
 233
 234     /* Retrieves 'netdev''s Ethernet address into 'mac'. */
 235     int (*get_etheraddr)(const struct netdev *netdev, uint8_t mac[6]);
 236
 237     /* Retrieves 'netdev''s MTU into '*mtup'.
 238      *
 239      * The MTU is the maximum size of transmitted (and received) packets, in
 240      * bytes, not including the hardware header; thus, this is typically 1500
 241      * bytes for Ethernet devices.
 242      *
 243      * If 'netdev' does not have an MTU (e.g. as some tunnels do not), then
 244      * this function should return EOPNOTSUPP.  This function may be set to
 245      * null if it would always return EOPNOTSUPP. */
 246     int (*get_mtu)(const struct netdev *netdev, int *mtup);
 247
 248     /* Sets 'netdev''s MTU to 'mtu'.
 249      *
 250      * If 'netdev' does not have an MTU (e.g. as some tunnels do not), then
 251      * this function should return EOPNOTSUPP.  This function may be set to
 252      * null if it would always return EOPNOTSUPP. */
 253     int (*set_mtu)(const struct netdev *netdev, int mtu);
 254
 255     /* Returns the ifindex of 'netdev', if successful, as a positive number.
 256      * On failure, returns a negative errno value.
 257      *
 258      * The desired semantics of the ifindex value are a combination of those
 259      * specified by POSIX for if_nametoindex() and by SNMP for ifIndex.  An
 260      * ifindex value should be unique within a host and remain stable at least
 261      * until reboot.  SNMP says an ifindex "ranges between 1 and the value of
 262      * ifNumber" but many systems do not follow this rule anyhow.
 263      *
 264      * This function may be set to null if it would always return -EOPNOTSUPP.
 265      */
 266     int (*get_ifindex)(const struct netdev *netdev);
 267
 268     /* Sets 'carrier' to true if carrier is active (link light is on) on
 269      * 'netdev'.
 270      *
 271      * May be null if device does not provide carrier status (will be always
 272      * up as long as device is up).
 273      */
 274     int (*get_carrier)(const struct netdev *netdev, bool *carrier);
 275
 276     /* Returns the number of times 'netdev''s carrier has changed since being
 277      * initialized.
 278      *
 279      * If null, callers will assume the number of carrier resets is zero. */
 280     long long int (*get_carrier_resets)(const struct netdev *netdev);
 281
 282     /* Forces ->get_carrier() to poll 'netdev''s MII registers for link status
 283      * instead of checking 'netdev''s carrier.  'netdev''s MII registers will
 284      * be polled once ever 'interval' milliseconds.  If 'netdev' does not
 285      * support MII, another method may be used as a fallback.  If 'interval' is
 286      * less than or equal to zero, reverts ->get_carrier() to its normal
 287      * behavior.
 288      *
 289      * Most network devices won't support this feature and will set this
 290      * function pointer to NULL, which is equivalent to returning EOPNOTSUPP.
 291      */
 292     int (*set_miimon_interval)(struct netdev *netdev, long long int interval);
 293
 294     /* Retrieves current device stats for 'netdev' into 'stats'.
 295      *
 296      * A network device that supports some statistics but not others, it should
 297      * set the values of the unsupported statistics to all-1-bits
 298      * (UINT64_MAX). */
 299     int (*get_stats)(const struct netdev *netdev, struct netdev_stats *);
 300
 301     /* Sets the device stats for 'netdev' to 'stats'.
 302      *
 303      * Most network devices won't support this feature and will set this
 304      * function pointer to NULL, which is equivalent to returning EOPNOTSUPP.
 305      *
 306      * Some network devices might only allow setting their stats to 0. */
 307     int (*set_stats)(struct netdev *netdev, const struct netdev_stats *);
 308
 309     /* Stores the features supported by 'netdev' into each of '*current',
 310      * '*advertised', '*supported', and '*peer'.  Each value is a bitmap of
 311      * NETDEV_F_* bits.
 312      *
 313      * This function may be set to null if it would always return EOPNOTSUPP.
 314      */
 315     int (*get_features)(const struct netdev *netdev,
 316                         enum netdev_features *current,
 317                         enum netdev_features *advertised,
 318                         enum netdev_features *supported,
 319                         enum netdev_features *peer);
 320
 321     /* Set the features advertised by 'netdev' to 'advertise', which is a
 322      * set of NETDEV_F_* bits.
 323      *
 324      * This function may be set to null for a network device that does not
 325      * support configuring advertisements. */
 326     int (*set_advertisements)(struct netdev *netdev,
 327                               enum netdev_features advertise);
 328
 329     /* Attempts to set input rate limiting (policing) policy, such that up to
 330      * 'kbits_rate' kbps of traffic is accepted, with a maximum accumulative
 331      * burst size of 'kbits' kb.
 332      *
 333      * This function may be set to null if policing is not supported. */
 334     int (*set_policing)(struct netdev *netdev, unsigned int kbits_rate,
 335                         unsigned int kbits_burst);
 336
 337     /* Adds to 'types' all of the forms of QoS supported by 'netdev', or leaves
 338      * it empty if 'netdev' does not support QoS.  Any names added to 'types'
 339      * should be documented as valid for the "type" column in the "QoS" table
 340      * in vswitchd/vswitch.xml (which is built as ovs-vswitchd.conf.db(8)).
 341      *
 342      * Every network device must support disabling QoS with a type of "", but
 343      * this function must not add "" to 'types'.
 344      *
 345      * The caller is responsible for initializing 'types' (e.g. with
 346      * sset_init()) before calling this function.  The caller retains ownership
 347      * of 'types'.
 348      *
 349      * May be NULL if 'netdev' does not support QoS at all. */
 350     int (*get_qos_types)(const struct netdev *netdev, struct sset *types);
 351
 352     /* Queries 'netdev' for its capabilities regarding the specified 'type' of
 353      * QoS.  On success, initializes 'caps' with the QoS capabilities.
 354      *
 355      * Should return EOPNOTSUPP if 'netdev' does not support 'type'.  May be
 356      * NULL if 'netdev' does not support QoS at all. */
 357     int (*get_qos_capabilities)(const struct netdev *netdev,
 358                                 const char *type,
 359                                 struct netdev_qos_capabilities *caps);
 360
 361     /* Queries 'netdev' about its currently configured form of QoS.  If
 362      * successful, stores the name of the current form of QoS into '*typep'
 363      * and any details of configuration as string key-value pairs in
 364      * 'details'.
 365      *
 366      * A '*typep' of "" indicates that QoS is currently disabled on 'netdev'.
 367      *
 368      * The caller initializes 'details' before calling this function.  The
 369      * caller takes ownership of the string key-values pairs added to
 370      * 'details'.
 371      *
 372      * The netdev retains ownership of '*typep'.
 373      *
 374      * '*typep' will be one of the types returned by netdev_get_qos_types() for
 375      * 'netdev'.  The contents of 'details' should be documented as valid for
 376      * '*typep' in the "other_config" column in the "QoS" table in
 377      * vswitchd/vswitch.xml (which is built as ovs-vswitchd.conf.db(8)).
 378      *
 379      * May be NULL if 'netdev' does not support QoS at all. */
 380     int (*get_qos)(const struct netdev *netdev,
 381                    const char **typep, struct shash *details);
 382
 383     /* Attempts to reconfigure QoS on 'netdev', changing the form of QoS to
 384      * 'type' with details of configuration from 'details'.
 385      *
 386      * On error, the previous QoS configuration is retained.
 387      *
 388      * When this function changes the type of QoS (not just 'details'), this
 389      * also resets all queue configuration for 'netdev' to their defaults
 390      * (which depend on the specific type of QoS).  Otherwise, the queue
 391      * configuration for 'netdev' is unchanged.
 392      *
 393      * 'type' should be "" (to disable QoS) or one of the types returned by
 394      * netdev_get_qos_types() for 'netdev'.  The contents of 'details' should
 395      * be documented as valid for the given 'type' in the "other_config" column
 396      * in the "QoS" table in vswitchd/vswitch.xml (which is built as
 397      * ovs-vswitchd.conf.db(8)).
 398      *
 399      * May be NULL if 'netdev' does not support QoS at all. */
 400     int (*set_qos)(struct netdev *netdev,
 401                    const char *type, const struct shash *details);
 402
 403     /* Queries 'netdev' for information about the queue numbered 'queue_id'.
 404      * If successful, adds that information as string key-value pairs to
 405      * 'details'.  Returns 0 if successful, otherwise a positive errno value.
 406      *
 407      * Should return EINVAL if 'queue_id' is greater than or equal to the
 408      * number of supported queues (as reported in the 'n_queues' member of
 409      * struct netdev_qos_capabilities by 'get_qos_capabilities').
 410      *
 411      * The caller initializes 'details' before calling this function.  The
 412      * caller takes ownership of the string key-values pairs added to
 413      * 'details'.
 414      *
 415      * The returned contents of 'details' should be documented as valid for the
 416      * given 'type' in the "other_config" column in the "Queue" table in
 417      * vswitchd/vswitch.xml (which is built as ovs-vswitchd.conf.db(8)).
 418      */
 419     int (*get_queue)(const struct netdev *netdev,
 420                      unsigned int queue_id, struct shash *details);
 421
 422     /* Configures the queue numbered 'queue_id' on 'netdev' with the key-value
 423      * string pairs in 'details'.  The contents of 'details' should be
 424      * documented as valid for the given 'type' in the "other_config" column in
 425      * the "Queue" table in vswitchd/vswitch.xml (which is built as
 426      * ovs-vswitchd.conf.db(8)).  Returns 0 if successful, otherwise a positive
 427      * errno value.  On failure, the given queue's configuration should be
 428      * unmodified.
 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'), or if
 433      * 'details' is invalid for the type of queue.
 434      *
 435      * This function does not modify 'details', and the caller retains
 436      * ownership of it.
 437      *
 438      * May be NULL if 'netdev' does not support QoS at all. */
 439     int (*set_queue)(struct netdev *netdev,
 440                      unsigned int queue_id, const struct shash *details);
 441
 442     /* Attempts to delete the queue numbered 'queue_id' from 'netdev'.
 443      *
 444      * Should return EINVAL if 'queue_id' is greater than or equal to the
 445      * number of supported queues (as reported in the 'n_queues' member of
 446      * struct netdev_qos_capabilities by 'get_qos_capabilities').  Should
 447      * return EOPNOTSUPP if 'queue_id' is valid but may not be deleted (e.g. if
 448      * 'netdev' has a fixed set of queues with the current QoS mode).
 449      *
 450      * May be NULL if 'netdev' does not support QoS at all, or if all of its
 451      * QoS modes have fixed sets of queues. */
 452     int (*delete_queue)(struct netdev *netdev, unsigned int queue_id);
 453
 454     /* Obtains statistics about 'queue_id' on 'netdev'.  Fills 'stats' with the
 455      * queue's statistics.  May set individual members of 'stats' to all-1-bits
 456      * if the statistic is unavailable.
 457      *
 458      * May be NULL if 'netdev' does not support QoS at all. */
 459     int (*get_queue_stats)(const struct netdev *netdev, unsigned int queue_id,
 460                            struct netdev_queue_stats *stats);
 461
 462     /* Iterates over all of 'netdev''s queues, calling 'cb' with the queue's
 463      * ID, its configuration, and the 'aux' specified by the caller.  The order
 464      * of iteration is unspecified, but (when successful) each queue is visited
 465      * exactly once.
 466      *
 467      * 'cb' will not modify or free the 'details' argument passed in. */
 468     int (*dump_queues)(const struct netdev *netdev,
 469                        void (*cb)(unsigned int queue_id,
 470                                   const struct shash *details,
 471                                   void *aux),
 472                        void *aux);
 473
 474     /* Iterates over all of 'netdev''s queues, calling 'cb' with the queue's
 475      * ID, its statistics, and the 'aux' specified by the caller.  The order of
 476      * iteration is unspecified, but (when successful) each queue must be
 477      * visited exactly once.
 478      *
 479      * 'cb' will not modify or free the statistics passed in. */
 480     int (*dump_queue_stats)(const struct netdev *netdev,
 481                             void (*cb)(unsigned int queue_id,
 482                                        struct netdev_queue_stats *,
 483                                        void *aux),
 484                             void *aux);
 485
 486     /* If 'netdev' has an assigned IPv4 address, sets '*address' to that
 487      * address and '*netmask' to the associated netmask.
 488      *
 489      * The following error values have well-defined meanings:
 490      *
 491      *   - EADDRNOTAVAIL: 'netdev' has no assigned IPv4 address.
 492      *
 493      *   - EOPNOTSUPP: No IPv4 network stack attached to 'netdev'.
 494      *
 495      * This function may be set to null if it would always return EOPNOTSUPP
 496      * anyhow. */
 497     int (*get_in4)(const struct netdev *netdev, struct in_addr *address,
 498                    struct in_addr *netmask);
 499
 500     /* Assigns 'addr' as 'netdev''s IPv4 address and 'mask' as its netmask.  If
 501      * 'addr' is INADDR_ANY, 'netdev''s IPv4 address is cleared.
 502      *
 503      * This function may be set to null if it would always return EOPNOTSUPP
 504      * anyhow. */
 505     int (*set_in4)(struct netdev *netdev, struct in_addr addr,
 506                    struct in_addr mask);
 507
 508     /* If 'netdev' has an assigned IPv6 address, sets '*in6' to that address.
 509      *
 510      * The following error values have well-defined meanings:
 511      *
 512      *   - EADDRNOTAVAIL: 'netdev' has no assigned IPv6 address.
 513      *
 514      *   - EOPNOTSUPP: No IPv6 network stack attached to 'netdev'.
 515      *
 516      * This function may be set to null if it would always return EOPNOTSUPP
 517      * anyhow. */
 518     int (*get_in6)(const struct netdev *netdev, struct in6_addr *in6);
 519
 520     /* Adds 'router' as a default IP gateway for the TCP/IP stack that
 521      * corresponds to 'netdev'.
 522      *
 523      * This function may be set to null if it would always return EOPNOTSUPP
 524      * anyhow. */
 525     int (*add_router)(struct netdev *netdev, struct in_addr router);
 526
 527     /* Looks up the next hop for 'host'.  If succesful, stores the next hop
 528      * gateway's address (0 if 'host' is on a directly connected network) in
 529      * '*next_hop' and a copy of the name of the device to reach 'host' in
 530      * '*netdev_name', and returns 0.  The caller is responsible for freeing
 531      * '*netdev_name' (by calling free()).
 532      *
 533      * This function may be set to null if it would always return EOPNOTSUPP
 534      * anyhow. */
 535     int (*get_next_hop)(const struct in_addr *host, struct in_addr *next_hop,
 536                         char **netdev_name);
 537
 538     /* Retrieves the status of the device.
 539      *
 540      * Populates 'sh' with key-value pairs representing the status of the
 541      * device.  A device's status is a set of key-value string pairs
 542      * representing netdev type specific information.  For more information see
 543      * ovs-vswitchd.conf.db(5).
 544      *
 545      * The data of 'sh' are heap allocated strings which the caller is
 546      * responsible for deallocating.
 547      *
 548      * This function may be set to null if it would always return EOPNOTSUPP
 549      * anyhow. */
 550     int (*get_status)(const struct netdev *netdev, struct shash *sh);
 551
 552     /* Looks up the ARP table entry for 'ip' on 'netdev' and stores the
 553      * corresponding MAC address in 'mac'.  A return value of ENXIO, in
 554      * particular, indicates that there is no ARP table entry for 'ip' on
 555      * 'netdev'.
 556      *
 557      * This function may be set to null if it would always return EOPNOTSUPP
 558      * anyhow. */
 559     int (*arp_lookup)(const struct netdev *netdev, ovs_be32 ip,
 560                       uint8_t mac[6]);
 561
 562     /* Retrieves the current set of flags on 'netdev' into '*old_flags'.
 563      * Then, turns off the flags that are set to 1 in 'off' and turns on the
 564      * flags that are set to 1 in 'on'.  (No bit will be set to 1 in both 'off'
 565      * and 'on'; that is, off & on == 0.)
 566      *
 567      * This function may be invoked from a signal handler.  Therefore, it
 568      * should not do anything that is not signal-safe (such as logging). */
 569     int (*update_flags)(struct netdev *netdev, enum netdev_flags off,
 570                         enum netdev_flags on, enum netdev_flags *old_flags);
 571
 572     /* Returns a sequence number which indicates changes in one of 'netdev''s
 573      * properties.  The returned sequence number must be nonzero so that
 574      * callers have a value which they may use as a reset when tracking
 575      * 'netdev'.
 576      *
 577      * Minimally, the returned sequence number is required to change whenever
 578      * 'netdev''s flags, features, ethernet address, or carrier changes.  The
 579      * returned sequence number is allowed to change even when 'netdev' doesn't
 580      * change, although implementations should try to avoid this. */
 581     unsigned int (*change_seq)(const struct netdev *netdev);
 582 };
 583
 584 int netdev_register_provider(const struct netdev_class *);
 585 int netdev_unregister_provider(const char *type);
 586 const struct netdev_class *netdev_lookup_provider(const char *type);
 587
 588 extern const struct netdev_class netdev_linux_class;
 589 extern const struct netdev_class netdev_internal_class;
 590 extern const struct netdev_class netdev_tap_class;
 591
 592 #ifdef  __cplusplus
 593 }
 594 #endif
 595
 596 #endif /* netdev.h */