lib/netdev-provider.h

   1 /*
   2  * Copyright (c) 2009, 2010, 2011, 2012 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      *
 236      * This address will be advertised as 'netdev''s MAC address through the
 237      * OpenFlow protocol, among other uses. */
 238     int (*get_etheraddr)(const struct netdev *netdev, uint8_t mac[6]);
 239
 240     /* Retrieves 'netdev''s MTU into '*mtup'.
 241      *
 242      * The MTU is the maximum size of transmitted (and received) packets, in
 243      * bytes, not including the hardware header; thus, this is typically 1500
 244      * bytes for Ethernet devices.
 245      *
 246      * If 'netdev' does not have an MTU (e.g. as some tunnels do not), then
 247      * this function should return EOPNOTSUPP.  This function may be set to
 248      * null if it would always return EOPNOTSUPP. */
 249     int (*get_mtu)(const struct netdev *netdev, int *mtup);
 250
 251     /* Sets 'netdev''s MTU to 'mtu'.
 252      *
 253      * If 'netdev' does not have an MTU (e.g. as some tunnels do not), then
 254      * this function should return EOPNOTSUPP.  This function may be set to
 255      * null if it would always return EOPNOTSUPP. */
 256     int (*set_mtu)(const struct netdev *netdev, int mtu);
 257
 258     /* Returns the ifindex of 'netdev', if successful, as a positive number.
 259      * On failure, returns a negative errno value.
 260      *
 261      * The desired semantics of the ifindex value are a combination of those
 262      * specified by POSIX for if_nametoindex() and by SNMP for ifIndex.  An
 263      * ifindex value should be unique within a host and remain stable at least
 264      * until reboot.  SNMP says an ifindex "ranges between 1 and the value of
 265      * ifNumber" but many systems do not follow this rule anyhow.
 266      *
 267      * This function may be set to null if it would always return -EOPNOTSUPP.
 268      */
 269     int (*get_ifindex)(const struct netdev *netdev);
 270
 271     /* Sets 'carrier' to true if carrier is active (link light is on) on
 272      * 'netdev'.
 273      *
 274      * May be null if device does not provide carrier status (will be always
 275      * up as long as device is up).
 276      */
 277     int (*get_carrier)(const struct netdev *netdev, bool *carrier);
 278
 279     /* Returns the number of times 'netdev''s carrier has changed since being
 280      * initialized.
 281      *
 282      * If null, callers will assume the number of carrier resets is zero. */
 283     long long int (*get_carrier_resets)(const struct netdev *netdev);
 284
 285     /* Forces ->get_carrier() to poll 'netdev''s MII registers for link status
 286      * instead of checking 'netdev''s carrier.  'netdev''s MII registers will
 287      * be polled once ever 'interval' milliseconds.  If 'netdev' does not
 288      * support MII, another method may be used as a fallback.  If 'interval' is
 289      * less than or equal to zero, reverts ->get_carrier() to its normal
 290      * behavior.
 291      *
 292      * Most network devices won't support this feature and will set this
 293      * function pointer to NULL, which is equivalent to returning EOPNOTSUPP.
 294      */
 295     int (*set_miimon_interval)(struct netdev *netdev, long long int interval);
 296
 297     /* Retrieves current device stats for 'netdev' into 'stats'.
 298      *
 299      * A network device that supports some statistics but not others, it should
 300      * set the values of the unsupported statistics to all-1-bits
 301      * (UINT64_MAX). */
 302     int (*get_stats)(const struct netdev *netdev, struct netdev_stats *);
 303
 304     /* Sets the device stats for 'netdev' to 'stats'.
 305      *
 306      * Most network devices won't support this feature and will set this
 307      * function pointer to NULL, which is equivalent to returning EOPNOTSUPP.
 308      *
 309      * Some network devices might only allow setting their stats to 0. */
 310     int (*set_stats)(struct netdev *netdev, const struct netdev_stats *);
 311
 312     /* Stores the features supported by 'netdev' into each of '*current',
 313      * '*advertised', '*supported', and '*peer'.  Each value is a bitmap of
 314      * NETDEV_F_* bits.
 315      *
 316      * This function may be set to null if it would always return EOPNOTSUPP.
 317      */
 318     int (*get_features)(const struct netdev *netdev,
 319                         enum netdev_features *current,
 320                         enum netdev_features *advertised,
 321                         enum netdev_features *supported,
 322                         enum netdev_features *peer);
 323
 324     /* Set the features advertised by 'netdev' to 'advertise', which is a
 325      * set of NETDEV_F_* bits.
 326      *
 327      * This function may be set to null for a network device that does not
 328      * support configuring advertisements. */
 329     int (*set_advertisements)(struct netdev *netdev,
 330                               enum netdev_features advertise);
 331
 332     /* Attempts to set input rate limiting (policing) policy, such that up to
 333      * 'kbits_rate' kbps of traffic is accepted, with a maximum accumulative
 334      * burst size of 'kbits' kb.
 335      *
 336      * This function may be set to null if policing is not supported. */
 337     int (*set_policing)(struct netdev *netdev, unsigned int kbits_rate,
 338                         unsigned int kbits_burst);
 339
 340     /* Adds to 'types' all of the forms of QoS supported by 'netdev', or leaves
 341      * it empty if 'netdev' does not support QoS.  Any names added to 'types'
 342      * should be documented as valid for the "type" column in the "QoS" table
 343      * in vswitchd/vswitch.xml (which is built as ovs-vswitchd.conf.db(8)).
 344      *
 345      * Every network device must support disabling QoS with a type of "", but
 346      * this function must not add "" to 'types'.
 347      *
 348      * The caller is responsible for initializing 'types' (e.g. with
 349      * sset_init()) before calling this function.  The caller retains ownership
 350      * of 'types'.
 351      *
 352      * May be NULL if 'netdev' does not support QoS at all. */
 353     int (*get_qos_types)(const struct netdev *netdev, struct sset *types);
 354
 355     /* Queries 'netdev' for its capabilities regarding the specified 'type' of
 356      * QoS.  On success, initializes 'caps' with the QoS capabilities.
 357      *
 358      * Should return EOPNOTSUPP if 'netdev' does not support 'type'.  May be
 359      * NULL if 'netdev' does not support QoS at all. */
 360     int (*get_qos_capabilities)(const struct netdev *netdev,
 361                                 const char *type,
 362                                 struct netdev_qos_capabilities *caps);
 363
 364     /* Queries 'netdev' about its currently configured form of QoS.  If
 365      * successful, stores the name of the current form of QoS into '*typep'
 366      * and any details of configuration as string key-value pairs in
 367      * 'details'.
 368      *
 369      * A '*typep' of "" indicates that QoS is currently disabled on 'netdev'.
 370      *
 371      * The caller initializes 'details' before calling this function.  The
 372      * caller takes ownership of the string key-values pairs added to
 373      * 'details'.
 374      *
 375      * The netdev retains ownership of '*typep'.
 376      *
 377      * '*typep' will be one of the types returned by netdev_get_qos_types() for
 378      * 'netdev'.  The contents of 'details' should be documented as valid for
 379      * '*typep' in the "other_config" column in the "QoS" table in
 380      * vswitchd/vswitch.xml (which is built as ovs-vswitchd.conf.db(8)).
 381      *
 382      * May be NULL if 'netdev' does not support QoS at all. */
 383     int (*get_qos)(const struct netdev *netdev,
 384                    const char **typep, struct shash *details);
 385
 386     /* Attempts to reconfigure QoS on 'netdev', changing the form of QoS to
 387      * 'type' with details of configuration from 'details'.
 388      *
 389      * On error, the previous QoS configuration is retained.
 390      *
 391      * When this function changes the type of QoS (not just 'details'), this
 392      * also resets all queue configuration for 'netdev' to their defaults
 393      * (which depend on the specific type of QoS).  Otherwise, the queue
 394      * configuration for 'netdev' is unchanged.
 395      *
 396      * 'type' should be "" (to disable QoS) or one of the types returned by
 397      * netdev_get_qos_types() for 'netdev'.  The contents of 'details' should
 398      * be documented as valid for the given 'type' in the "other_config" column
 399      * in the "QoS" table in vswitchd/vswitch.xml (which is built as
 400      * ovs-vswitchd.conf.db(8)).
 401      *
 402      * May be NULL if 'netdev' does not support QoS at all. */
 403     int (*set_qos)(struct netdev *netdev,
 404                    const char *type, const struct shash *details);
 405
 406     /* Queries 'netdev' for information about the queue numbered 'queue_id'.
 407      * If successful, adds that information as string key-value pairs to
 408      * 'details'.  Returns 0 if successful, otherwise a positive errno value.
 409      *
 410      * Should return EINVAL if 'queue_id' is greater than or equal to the
 411      * number of supported queues (as reported in the 'n_queues' member of
 412      * struct netdev_qos_capabilities by 'get_qos_capabilities').
 413      *
 414      * The caller initializes 'details' before calling this function.  The
 415      * caller takes ownership of the string key-values pairs added to
 416      * 'details'.
 417      *
 418      * The returned contents of 'details' should be documented as valid for the
 419      * given 'type' in the "other_config" column in the "Queue" table in
 420      * vswitchd/vswitch.xml (which is built as ovs-vswitchd.conf.db(8)).
 421      */
 422     int (*get_queue)(const struct netdev *netdev,
 423                      unsigned int queue_id, struct shash *details);
 424
 425     /* Configures the queue numbered 'queue_id' on 'netdev' with the key-value
 426      * string pairs in 'details'.  The contents of 'details' should be
 427      * documented as valid for the given 'type' in the "other_config" column in
 428      * the "Queue" table in vswitchd/vswitch.xml (which is built as
 429      * ovs-vswitchd.conf.db(8)).  Returns 0 if successful, otherwise a positive
 430      * errno value.  On failure, the given queue's configuration should be
 431      * unmodified.
 432      *
 433      * Should return EINVAL if 'queue_id' is greater than or equal to the
 434      * number of supported queues (as reported in the 'n_queues' member of
 435      * struct netdev_qos_capabilities by 'get_qos_capabilities'), or if
 436      * 'details' is invalid for the type of queue.
 437      *
 438      * This function does not modify 'details', and the caller retains
 439      * ownership of it.
 440      *
 441      * May be NULL if 'netdev' does not support QoS at all. */
 442     int (*set_queue)(struct netdev *netdev,
 443                      unsigned int queue_id, const struct shash *details);
 444
 445     /* Attempts to delete the queue numbered 'queue_id' from 'netdev'.
 446      *
 447      * Should return EINVAL if 'queue_id' is greater than or equal to the
 448      * number of supported queues (as reported in the 'n_queues' member of
 449      * struct netdev_qos_capabilities by 'get_qos_capabilities').  Should
 450      * return EOPNOTSUPP if 'queue_id' is valid but may not be deleted (e.g. if
 451      * 'netdev' has a fixed set of queues with the current QoS mode).
 452      *
 453      * May be NULL if 'netdev' does not support QoS at all, or if all of its
 454      * QoS modes have fixed sets of queues. */
 455     int (*delete_queue)(struct netdev *netdev, unsigned int queue_id);
 456
 457     /* Obtains statistics about 'queue_id' on 'netdev'.  Fills 'stats' with the
 458      * queue's statistics.  May set individual members of 'stats' to all-1-bits
 459      * if the statistic is unavailable.
 460      *
 461      * May be NULL if 'netdev' does not support QoS at all. */
 462     int (*get_queue_stats)(const struct netdev *netdev, unsigned int queue_id,
 463                            struct netdev_queue_stats *stats);
 464
 465     /* Iterates over all of 'netdev''s queues, calling 'cb' with the queue's
 466      * ID, its configuration, and the 'aux' specified by the caller.  The order
 467      * of iteration is unspecified, but (when successful) each queue is visited
 468      * exactly once.
 469      *
 470      * 'cb' will not modify or free the 'details' argument passed in.  It may
 471      * delete or modify the queue passed in as its 'queue_id' argument.  It may
 472      * modify but will not delete any other queue within 'netdev'.  If 'cb'
 473      * adds new queues, then ->dump_queues is allowed to visit some queues
 474      * twice or not at all.
 475      */
 476     int (*dump_queues)(const struct netdev *netdev,
 477                        void (*cb)(unsigned int queue_id,
 478                                   const struct shash *details,
 479                                   void *aux),
 480                        void *aux);
 481
 482     /* Iterates over all of 'netdev''s queues, calling 'cb' with the queue's
 483      * ID, its statistics, and the 'aux' specified by the caller.  The order of
 484      * iteration is unspecified, but (when successful) each queue must be
 485      * visited exactly once.
 486      *
 487      * 'cb' will not modify or free the statistics passed in. */
 488     int (*dump_queue_stats)(const struct netdev *netdev,
 489                             void (*cb)(unsigned int queue_id,
 490                                        struct netdev_queue_stats *,
 491                                        void *aux),
 492                             void *aux);
 493
 494     /* If 'netdev' has an assigned IPv4 address, sets '*address' to that
 495      * address and '*netmask' to the associated netmask.
 496      *
 497      * The following error values have well-defined meanings:
 498      *
 499      *   - EADDRNOTAVAIL: 'netdev' has no assigned IPv4 address.
 500      *
 501      *   - EOPNOTSUPP: No IPv4 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_in4)(const struct netdev *netdev, struct in_addr *address,
 506                    struct in_addr *netmask);
 507
 508     /* Assigns 'addr' as 'netdev''s IPv4 address and 'mask' as its netmask.  If
 509      * 'addr' is INADDR_ANY, 'netdev''s IPv4 address is cleared.
 510      *
 511      * This function may be set to null if it would always return EOPNOTSUPP
 512      * anyhow. */
 513     int (*set_in4)(struct netdev *netdev, struct in_addr addr,
 514                    struct in_addr mask);
 515
 516     /* If 'netdev' has an assigned IPv6 address, sets '*in6' to that address.
 517      *
 518      * The following error values have well-defined meanings:
 519      *
 520      *   - EADDRNOTAVAIL: 'netdev' has no assigned IPv6 address.
 521      *
 522      *   - EOPNOTSUPP: No IPv6 network stack attached to 'netdev'.
 523      *
 524      * This function may be set to null if it would always return EOPNOTSUPP
 525      * anyhow. */
 526     int (*get_in6)(const struct netdev *netdev, struct in6_addr *in6);
 527
 528     /* Adds 'router' as a default IP gateway for the TCP/IP stack that
 529      * corresponds to 'netdev'.
 530      *
 531      * This function may be set to null if it would always return EOPNOTSUPP
 532      * anyhow. */
 533     int (*add_router)(struct netdev *netdev, struct in_addr router);
 534
 535     /* Looks up the next hop for 'host'.  If succesful, stores the next hop
 536      * gateway's address (0 if 'host' is on a directly connected network) in
 537      * '*next_hop' and a copy of the name of the device to reach 'host' in
 538      * '*netdev_name', and returns 0.  The caller is responsible for freeing
 539      * '*netdev_name' (by calling free()).
 540      *
 541      * This function may be set to null if it would always return EOPNOTSUPP
 542      * anyhow. */
 543     int (*get_next_hop)(const struct in_addr *host, struct in_addr *next_hop,
 544                         char **netdev_name);
 545
 546     /* Retrieves driver information of the device.
 547      *
 548      * Populates 'sh' with key-value pairs representing the status of the
 549      * device.  Driver info is a set of key-value string pairs
 550      * representing netdev type specific information.  For more information see
 551      * ovs-vswitchd.conf.db(5).
 552      *
 553      * The data of 'sh' are heap allocated strings which the caller is
 554      * responsible for deallocating.
 555      *
 556      * This function may be set to null if it would always return EOPNOTSUPP
 557      * anyhow. */
 558     int (*get_drv_info)(const struct netdev *netdev, struct shash *sh);
 559
 560     /* Looks up the ARP table entry for 'ip' on 'netdev' and stores the
 561      * corresponding MAC address in 'mac'.  A return value of ENXIO, in
 562      * particular, indicates that there is no ARP table entry for 'ip' on
 563      * 'netdev'.
 564      *
 565      * This function may be set to null if it would always return EOPNOTSUPP
 566      * anyhow. */
 567     int (*arp_lookup)(const struct netdev *netdev, ovs_be32 ip,
 568                       uint8_t mac[6]);
 569
 570     /* Retrieves the current set of flags on 'netdev' into '*old_flags'.
 571      * Then, turns off the flags that are set to 1 in 'off' and turns on the
 572      * flags that are set to 1 in 'on'.  (No bit will be set to 1 in both 'off'
 573      * and 'on'; that is, off & on == 0.)
 574      *
 575      * This function may be invoked from a signal handler.  Therefore, it
 576      * should not do anything that is not signal-safe (such as logging). */
 577     int (*update_flags)(struct netdev *netdev, enum netdev_flags off,
 578                         enum netdev_flags on, enum netdev_flags *old_flags);
 579
 580     /* Returns a sequence number which indicates changes in one of 'netdev''s
 581      * properties.  The returned sequence number must be nonzero so that
 582      * callers have a value which they may use as a reset when tracking
 583      * 'netdev'.
 584      *
 585      * Minimally, the returned sequence number is required to change whenever
 586      * 'netdev''s flags, features, ethernet address, or carrier changes.  The
 587      * returned sequence number is allowed to change even when 'netdev' doesn't
 588      * change, although implementations should try to avoid this. */
 589     unsigned int (*change_seq)(const struct netdev *netdev);
 590 };
 591
 592 int netdev_register_provider(const struct netdev_class *);
 593 int netdev_unregister_provider(const char *type);
 594 const struct netdev_class *netdev_lookup_provider(const char *type);
 595
 596 extern const struct netdev_class netdev_linux_class;
 597 extern const struct netdev_class netdev_internal_class;
 598 extern const struct netdev_class netdev_tap_class;
 599
 600 #ifdef  __cplusplus
 601 }
 602 #endif
 603
 604 #endif /* netdev.h */