lib/netdev-provider.h

   1 /*
   2  * Copyright (c) 2009, 2010, 2011, 2012, 2013 Nicira, Inc.
   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 "netdev.h"
  23 #include "list.h"
  24 #include "shash.h"
  25 #include "smap.h"
  26
  27 #ifdef  __cplusplus
  28 extern "C" {
  29 #endif
  30
  31 /* A network device (e.g. an Ethernet device).
  32  *
  33  * This structure should be treated as opaque by network device
  34  * implementations. */
  35 struct netdev_dev {
  36     char *name;                         /* Name of network device. */
  37     const struct netdev_class *netdev_class; /* Functions to control
  38                                                 this device. */
  39     int ref_cnt;                        /* Times this devices was opened. */
  40     struct shash_node *node;            /* Pointer to element in global map. */
  41     struct list saved_flags_list; /* Contains "struct netdev_saved_flags". */
  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     ovs_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
  69 void netdev_init(struct netdev *, struct netdev_dev *);
  70 void netdev_uninit(struct netdev *, bool close);
  71 struct netdev_dev *netdev_get_dev(const struct netdev *);
  72
  73 static inline void netdev_assert_class(const struct netdev *netdev,
  74                                        const struct netdev_class *netdev_class)
  75 {
  76     netdev_dev_assert_class(netdev_get_dev(netdev), netdev_class);
  77 }
  78
  79 /* Network device class structure, to be defined by each implementation of a
  80  * network device.
  81  *
  82  * These functions return 0 if successful or a positive errno value on failure,
  83  * except where otherwise noted. */
  84 struct netdev_class {
  85     /* Type of netdevs in this class, e.g. "system", "tap", "gre", etc.
  86      *
  87      * One of the providers should supply a "system" type, since this is
  88      * the type assumed if no type is specified when opening a netdev.
  89      * The "system" type corresponds to an existing network device on
  90      * the system. */
  91     const char *type;
  92
  93     /* Called when the netdev provider is registered, typically at program
  94      * startup.  Returning an error from this function will prevent any network
  95      * device in this class from being opened.
  96      *
  97      * This function may be set to null if a network device class needs no
  98      * initialization at registration time. */
  99     int (*init)(void);
 100
 101     /* Performs periodic work needed by netdevs of this class.  May be null if
 102      * no periodic work is necessary. */
 103     void (*run)(void);
 104
 105     /* Arranges for poll_block() to wake up if the "run" member function needs
 106      * to be called.  Implementations are additionally required to wake
 107      * whenever something changes in any of its netdevs which would cause their
 108      * ->change_seq() function to change its result.  May be null if nothing is
 109      * needed here. */
 110     void (*wait)(void);
 111
 112     /* Attempts to create a network device named 'name' in 'netdev_class'.  On
 113      * success sets 'netdev_devp' to the newly created device. */
 114     int (*create)(const struct netdev_class *netdev_class, const char *name,
 115                   struct netdev_dev **netdev_devp);
 116
 117     /* Destroys 'netdev_dev'.
 118      *
 119      * Netdev devices maintain a reference count that is incremented on
 120      * netdev_open() and decremented on netdev_close().  If 'netdev_dev'
 121      * has a non-zero reference count, then this function will not be
 122      * called. */
 123     void (*destroy)(struct netdev_dev *netdev_dev);
 124
 125     /* Fetches the device 'netdev_dev''s configuration, storing it in 'args'.
 126      * The caller owns 'args' and pre-initializes it to an empty smap.
 127      *
 128      * If this netdev class does not have any configuration options, this may
 129      * be a null pointer. */
 130     int (*get_config)(struct netdev_dev *netdev_dev, struct smap *args);
 131
 132     /* Changes the device 'netdev_dev''s configuration to 'args'.
 133      *
 134      * If this netdev class does not support configuration, this may be a null
 135      * pointer. */
 136     int (*set_config)(struct netdev_dev *netdev_dev, const struct smap *args);
 137
 138     /* Returns the tunnel configuration of 'netdev_dev'.  If 'netdev_dev' is
 139      * not a tunnel, returns null.
 140      *
 141      * If this function would always return null, it may be null instead. */
 142     const struct netdev_tunnel_config *
 143         (*get_tunnel_config)(const struct netdev_dev *netdev_dev);
 144
 145     /* Attempts to open a network device.  On success, sets 'netdevp'
 146      * to the new network device. */
 147     int (*open)(struct netdev_dev *netdev_dev, struct netdev **netdevp);
 148
 149     /* Closes 'netdev'. */
 150     void (*close)(struct netdev *netdev);
 151
 152     /* Attempts to open a netdev_rx for receiving packets from 'netdev'.
 153      * Returns 0 if successful, otherwise a positive errno value.  Returns
 154      * EOPNOTSUPP to indicate that the network device does not implement packet
 155      * reception through this interface.  This function may be set to null if
 156      * it would always return EOPNOTSUPP anyhow.  (This will prevent the
 157      * network device from being usefully used by the netdev-based "userspace
 158      * datapath".)
 159      *
 160      * On success, the implementation must set '*rxp' to a 'netdev_rx' for
 161      * 'netdev' that it has already initialized (with netdev_rx_init()). */
 162     int (*rx_open)(struct netdev *netdev, struct netdev_rx **rxp);
 163
 164     /* Sends the 'size'-byte packet in 'buffer' on 'netdev'.  Returns 0 if
 165      * successful, otherwise a positive errno value.  Returns EAGAIN without
 166      * blocking if the packet cannot be queued immediately.  Returns EMSGSIZE
 167      * if a partial packet was transmitted or if the packet is too big or too
 168      * small to transmit on the device.
 169      *
 170      * The caller retains ownership of 'buffer' in all cases.
 171      *
 172      * The network device is expected to maintain a packet transmission queue,
 173      * so that the caller does not ordinarily have to do additional queuing of
 174      * packets.
 175      *
 176      * May return EOPNOTSUPP if a network device does not implement packet
 177      * transmission through this interface.  This function may be set to null
 178      * if it would always return EOPNOTSUPP anyhow.  (This will prevent the
 179      * network device from being usefully used by the netdev-based "userspace
 180      * datapath".  It will also prevent the OVS implementation of bonding from
 181      * working properly over 'netdev'.) */
 182     int (*send)(struct netdev *netdev, const void *buffer, size_t size);
 183
 184     /* Registers with the poll loop to wake up from the next call to
 185      * poll_block() when the packet transmission queue for 'netdev' has
 186      * sufficient room to transmit a packet with netdev_send().
 187      *
 188      * The network device is expected to maintain a packet transmission queue,
 189      * so that the caller does not ordinarily have to do additional queuing of
 190      * packets.  Thus, this function is unlikely to ever be useful.
 191      *
 192      * May be null if not needed, such as for a network device that does not
 193      * implement packet transmission through the 'send' member function. */
 194     void (*send_wait)(struct netdev *netdev);
 195
 196     /* Sets 'netdev''s Ethernet address to 'mac' */
 197     int (*set_etheraddr)(struct netdev *netdev, const uint8_t mac[6]);
 198
 199     /* Retrieves 'netdev''s Ethernet address into 'mac'.
 200      *
 201      * This address will be advertised as 'netdev''s MAC address through the
 202      * OpenFlow protocol, among other uses. */
 203     int (*get_etheraddr)(const struct netdev *netdev, uint8_t mac[6]);
 204
 205     /* Retrieves 'netdev''s MTU into '*mtup'.
 206      *
 207      * The MTU is the maximum size of transmitted (and received) packets, in
 208      * bytes, not including the hardware header; thus, this is typically 1500
 209      * bytes for Ethernet devices.
 210      *
 211      * If 'netdev' does not have an MTU (e.g. as some tunnels do not), then
 212      * this function should return EOPNOTSUPP.  This function may be set to
 213      * null if it would always return EOPNOTSUPP. */
 214     int (*get_mtu)(const struct netdev *netdev, int *mtup);
 215
 216     /* Sets 'netdev''s MTU to 'mtu'.
 217      *
 218      * If 'netdev' does not have an MTU (e.g. as some tunnels do not), then
 219      * this function should return EOPNOTSUPP.  This function may be set to
 220      * null if it would always return EOPNOTSUPP. */
 221     int (*set_mtu)(const struct netdev *netdev, int mtu);
 222
 223     /* Returns the ifindex of 'netdev', if successful, as a positive number.
 224      * On failure, returns a negative errno value.
 225      *
 226      * The desired semantics of the ifindex value are a combination of those
 227      * specified by POSIX for if_nametoindex() and by SNMP for ifIndex.  An
 228      * ifindex value should be unique within a host and remain stable at least
 229      * until reboot.  SNMP says an ifindex "ranges between 1 and the value of
 230      * ifNumber" but many systems do not follow this rule anyhow.
 231      *
 232      * This function may be set to null if it would always return -EOPNOTSUPP.
 233      */
 234     int (*get_ifindex)(const struct netdev *netdev);
 235
 236     /* Sets 'carrier' to true if carrier is active (link light is on) on
 237      * 'netdev'.
 238      *
 239      * May be null if device does not provide carrier status (will be always
 240      * up as long as device is up).
 241      */
 242     int (*get_carrier)(const struct netdev *netdev, bool *carrier);
 243
 244     /* Returns the number of times 'netdev''s carrier has changed since being
 245      * initialized.
 246      *
 247      * If null, callers will assume the number of carrier resets is zero. */
 248     long long int (*get_carrier_resets)(const struct netdev *netdev);
 249
 250     /* Forces ->get_carrier() to poll 'netdev''s MII registers for link status
 251      * instead of checking 'netdev''s carrier.  'netdev''s MII registers will
 252      * be polled once ever 'interval' milliseconds.  If 'netdev' does not
 253      * support MII, another method may be used as a fallback.  If 'interval' is
 254      * less than or equal to zero, reverts ->get_carrier() to its normal
 255      * behavior.
 256      *
 257      * Most network devices won't support this feature and will set this
 258      * function pointer to NULL, which is equivalent to returning EOPNOTSUPP.
 259      */
 260     int (*set_miimon_interval)(struct netdev *netdev, long long int interval);
 261
 262     /* Retrieves current device stats for 'netdev' into 'stats'.
 263      *
 264      * A network device that supports some statistics but not others, it should
 265      * set the values of the unsupported statistics to all-1-bits
 266      * (UINT64_MAX). */
 267     int (*get_stats)(const struct netdev *netdev, struct netdev_stats *);
 268
 269     /* Sets the device stats for 'netdev' to 'stats'.
 270      *
 271      * Most network devices won't support this feature and will set this
 272      * function pointer to NULL, which is equivalent to returning EOPNOTSUPP.
 273      *
 274      * Some network devices might only allow setting their stats to 0. */
 275     int (*set_stats)(struct netdev *netdev, const struct netdev_stats *);
 276
 277     /* Stores the features supported by 'netdev' into each of '*current',
 278      * '*advertised', '*supported', and '*peer'.  Each value is a bitmap of
 279      * NETDEV_F_* bits.
 280      *
 281      * This function may be set to null if it would always return EOPNOTSUPP.
 282      */
 283     int (*get_features)(const struct netdev *netdev,
 284                         enum netdev_features *current,
 285                         enum netdev_features *advertised,
 286                         enum netdev_features *supported,
 287                         enum netdev_features *peer);
 288
 289     /* Set the features advertised by 'netdev' to 'advertise', which is a
 290      * set of NETDEV_F_* bits.
 291      *
 292      * This function may be set to null for a network device that does not
 293      * support configuring advertisements. */
 294     int (*set_advertisements)(struct netdev *netdev,
 295                               enum netdev_features advertise);
 296
 297     /* Attempts to set input rate limiting (policing) policy, such that up to
 298      * 'kbits_rate' kbps of traffic is accepted, with a maximum accumulative
 299      * burst size of 'kbits' kb.
 300      *
 301      * This function may be set to null if policing is not supported. */
 302     int (*set_policing)(struct netdev *netdev, unsigned int kbits_rate,
 303                         unsigned int kbits_burst);
 304
 305     /* Adds to 'types' all of the forms of QoS supported by 'netdev', or leaves
 306      * it empty if 'netdev' does not support QoS.  Any names added to 'types'
 307      * should be documented as valid for the "type" column in the "QoS" table
 308      * in vswitchd/vswitch.xml (which is built as ovs-vswitchd.conf.db(8)).
 309      *
 310      * Every network device must support disabling QoS with a type of "", but
 311      * this function must not add "" to 'types'.
 312      *
 313      * The caller is responsible for initializing 'types' (e.g. with
 314      * sset_init()) before calling this function.  The caller retains ownership
 315      * of 'types'.
 316      *
 317      * May be NULL if 'netdev' does not support QoS at all. */
 318     int (*get_qos_types)(const struct netdev *netdev, struct sset *types);
 319
 320     /* Queries 'netdev' for its capabilities regarding the specified 'type' of
 321      * QoS.  On success, initializes 'caps' with the QoS capabilities.
 322      *
 323      * Should return EOPNOTSUPP if 'netdev' does not support 'type'.  May be
 324      * NULL if 'netdev' does not support QoS at all. */
 325     int (*get_qos_capabilities)(const struct netdev *netdev,
 326                                 const char *type,
 327                                 struct netdev_qos_capabilities *caps);
 328
 329     /* Queries 'netdev' about its currently configured form of QoS.  If
 330      * successful, stores the name of the current form of QoS into '*typep'
 331      * and any details of configuration as string key-value pairs in
 332      * 'details'.
 333      *
 334      * A '*typep' of "" indicates that QoS is currently disabled on 'netdev'.
 335      *
 336      * The caller initializes 'details' before calling this function.  The
 337      * caller takes ownership of the string key-values pairs added to
 338      * 'details'.
 339      *
 340      * The netdev retains ownership of '*typep'.
 341      *
 342      * '*typep' will be one of the types returned by netdev_get_qos_types() for
 343      * 'netdev'.  The contents of 'details' should be documented as valid for
 344      * '*typep' in the "other_config" column in the "QoS" table in
 345      * vswitchd/vswitch.xml (which is built as ovs-vswitchd.conf.db(8)).
 346      *
 347      * May be NULL if 'netdev' does not support QoS at all. */
 348     int (*get_qos)(const struct netdev *netdev,
 349                    const char **typep, struct smap *details);
 350
 351     /* Attempts to reconfigure QoS on 'netdev', changing the form of QoS to
 352      * 'type' with details of configuration from 'details'.
 353      *
 354      * On error, the previous QoS configuration is retained.
 355      *
 356      * When this function changes the type of QoS (not just 'details'), this
 357      * also resets all queue configuration for 'netdev' to their defaults
 358      * (which depend on the specific type of QoS).  Otherwise, the queue
 359      * configuration for 'netdev' is unchanged.
 360      *
 361      * 'type' should be "" (to disable QoS) or one of the types returned by
 362      * netdev_get_qos_types() for 'netdev'.  The contents of 'details' should
 363      * be documented as valid for the given 'type' in the "other_config" column
 364      * in the "QoS" table in vswitchd/vswitch.xml (which is built as
 365      * ovs-vswitchd.conf.db(8)).
 366      *
 367      * May be NULL if 'netdev' does not support QoS at all. */
 368     int (*set_qos)(struct netdev *netdev,
 369                    const char *type, const struct smap *details);
 370
 371     /* Queries 'netdev' for information about the queue numbered 'queue_id'.
 372      * If successful, adds that information as string key-value pairs to
 373      * 'details'.  Returns 0 if successful, otherwise a positive errno value.
 374      *
 375      * Should return EINVAL if 'queue_id' is greater than or equal to the
 376      * number of supported queues (as reported in the 'n_queues' member of
 377      * struct netdev_qos_capabilities by 'get_qos_capabilities').
 378      *
 379      * The caller initializes 'details' before calling this function.  The
 380      * caller takes ownership of the string key-values pairs added to
 381      * 'details'.
 382      *
 383      * The returned contents of 'details' should be documented as valid for the
 384      * given 'type' in the "other_config" column in the "Queue" table in
 385      * vswitchd/vswitch.xml (which is built as ovs-vswitchd.conf.db(8)).
 386      */
 387     int (*get_queue)(const struct netdev *netdev,
 388                      unsigned int queue_id, struct smap *details);
 389
 390     /* Configures the queue numbered 'queue_id' on 'netdev' with the key-value
 391      * string pairs in 'details'.  The contents of 'details' should be
 392      * documented as valid for the given 'type' in the "other_config" column in
 393      * the "Queue" table in vswitchd/vswitch.xml (which is built as
 394      * ovs-vswitchd.conf.db(8)).  Returns 0 if successful, otherwise a positive
 395      * errno value.  On failure, the given queue's configuration should be
 396      * unmodified.
 397      *
 398      * Should return EINVAL if 'queue_id' is greater than or equal to the
 399      * number of supported queues (as reported in the 'n_queues' member of
 400      * struct netdev_qos_capabilities by 'get_qos_capabilities'), or if
 401      * 'details' is invalid for the type of queue.
 402      *
 403      * This function does not modify 'details', and the caller retains
 404      * ownership of it.
 405      *
 406      * May be NULL if 'netdev' does not support QoS at all. */
 407     int (*set_queue)(struct netdev *netdev,
 408                      unsigned int queue_id, const struct smap *details);
 409
 410     /* Attempts to delete the queue numbered 'queue_id' from 'netdev'.
 411      *
 412      * Should return EINVAL if 'queue_id' is greater than or equal to the
 413      * number of supported queues (as reported in the 'n_queues' member of
 414      * struct netdev_qos_capabilities by 'get_qos_capabilities').  Should
 415      * return EOPNOTSUPP if 'queue_id' is valid but may not be deleted (e.g. if
 416      * 'netdev' has a fixed set of queues with the current QoS mode).
 417      *
 418      * May be NULL if 'netdev' does not support QoS at all, or if all of its
 419      * QoS modes have fixed sets of queues. */
 420     int (*delete_queue)(struct netdev *netdev, unsigned int queue_id);
 421
 422     /* Obtains statistics about 'queue_id' on 'netdev'.  Fills 'stats' with the
 423      * queue's statistics.  May set individual members of 'stats' to all-1-bits
 424      * if the statistic is unavailable.
 425      *
 426      * May be NULL if 'netdev' does not support QoS at all. */
 427     int (*get_queue_stats)(const struct netdev *netdev, unsigned int queue_id,
 428                            struct netdev_queue_stats *stats);
 429
 430     /* Iterates over all of 'netdev''s queues, calling 'cb' with the queue's
 431      * ID, its configuration, and the 'aux' specified by the caller.  The order
 432      * of iteration is unspecified, but (when successful) each queue is visited
 433      * exactly once.
 434      *
 435      * 'cb' will not modify or free the 'details' argument passed in.  It may
 436      * delete or modify the queue passed in as its 'queue_id' argument.  It may
 437      * modify but will not delete any other queue within 'netdev'.  If 'cb'
 438      * adds new queues, then ->dump_queues is allowed to visit some queues
 439      * twice or not at all.
 440      */
 441     int (*dump_queues)(const struct netdev *netdev,
 442                        void (*cb)(unsigned int queue_id,
 443                                   const struct smap *details,
 444                                   void *aux),
 445                        void *aux);
 446
 447     /* Iterates over all of 'netdev''s queues, calling 'cb' with the queue's
 448      * ID, its statistics, and the 'aux' specified by the caller.  The order of
 449      * iteration is unspecified, but (when successful) each queue must be
 450      * visited exactly once.
 451      *
 452      * 'cb' will not modify or free the statistics passed in. */
 453     int (*dump_queue_stats)(const struct netdev *netdev,
 454                             void (*cb)(unsigned int queue_id,
 455                                        struct netdev_queue_stats *,
 456                                        void *aux),
 457                             void *aux);
 458
 459     /* If 'netdev' has an assigned IPv4 address, sets '*address' to that
 460      * address and '*netmask' to the associated netmask.
 461      *
 462      * The following error values have well-defined meanings:
 463      *
 464      *   - EADDRNOTAVAIL: 'netdev' has no assigned IPv4 address.
 465      *
 466      *   - EOPNOTSUPP: No IPv4 network stack attached to 'netdev'.
 467      *
 468      * This function may be set to null if it would always return EOPNOTSUPP
 469      * anyhow. */
 470     int (*get_in4)(const struct netdev *netdev, struct in_addr *address,
 471                    struct in_addr *netmask);
 472
 473     /* Assigns 'addr' as 'netdev''s IPv4 address and 'mask' as its netmask.  If
 474      * 'addr' is INADDR_ANY, 'netdev''s IPv4 address is cleared.
 475      *
 476      * This function may be set to null if it would always return EOPNOTSUPP
 477      * anyhow. */
 478     int (*set_in4)(struct netdev *netdev, struct in_addr addr,
 479                    struct in_addr mask);
 480
 481     /* If 'netdev' has an assigned IPv6 address, sets '*in6' to that address.
 482      *
 483      * The following error values have well-defined meanings:
 484      *
 485      *   - EADDRNOTAVAIL: 'netdev' has no assigned IPv6 address.
 486      *
 487      *   - EOPNOTSUPP: No IPv6 network stack attached to 'netdev'.
 488      *
 489      * This function may be set to null if it would always return EOPNOTSUPP
 490      * anyhow. */
 491     int (*get_in6)(const struct netdev *netdev, struct in6_addr *in6);
 492
 493     /* Adds 'router' as a default IP gateway for the TCP/IP stack that
 494      * corresponds to 'netdev'.
 495      *
 496      * This function may be set to null if it would always return EOPNOTSUPP
 497      * anyhow. */
 498     int (*add_router)(struct netdev *netdev, struct in_addr router);
 499
 500     /* Looks up the next hop for 'host'.  If succesful, stores the next hop
 501      * gateway's address (0 if 'host' is on a directly connected network) in
 502      * '*next_hop' and a copy of the name of the device to reach 'host' in
 503      * '*netdev_name', and returns 0.  The caller is responsible for freeing
 504      * '*netdev_name' (by calling free()).
 505      *
 506      * This function may be set to null if it would always return EOPNOTSUPP
 507      * anyhow. */
 508     int (*get_next_hop)(const struct in_addr *host, struct in_addr *next_hop,
 509                         char **netdev_name);
 510
 511     /* Retrieves driver information of the device.
 512      *
 513      * Populates 'smap' with key-value pairs representing the status of the
 514      * device.  'smap' is a set of key-value string pairs representing netdev
 515      * type specific information.  For more information see
 516      * ovs-vswitchd.conf.db(5).
 517      *
 518      * The caller is responsible for destroying 'smap' and its data.
 519      *
 520      * This function may be set to null if it would always return EOPNOTSUPP
 521      * anyhow. */
 522     int (*get_status)(const struct netdev *netdev, struct smap *smap);
 523
 524     /* Looks up the ARP table entry for 'ip' on 'netdev' and stores the
 525      * corresponding MAC address in 'mac'.  A return value of ENXIO, in
 526      * particular, indicates that there is no ARP table entry for 'ip' on
 527      * 'netdev'.
 528      *
 529      * This function may be set to null if it would always return EOPNOTSUPP
 530      * anyhow. */
 531     int (*arp_lookup)(const struct netdev *netdev, ovs_be32 ip,
 532                       uint8_t mac[6]);
 533
 534     /* Retrieves the current set of flags on 'dev' into '*old_flags'.  Then,
 535      * turns off the flags that are set to 1 in 'off' and turns on the flags
 536      * that are set to 1 in 'on'.  (No bit will be set to 1 in both 'off' and
 537      * 'on'; that is, off & on == 0.)
 538      *
 539      * This function may be invoked from a signal handler.  Therefore, it
 540      * should not do anything that is not signal-safe (such as logging). */
 541     int (*update_flags)(struct netdev_dev *dev, enum netdev_flags off,
 542                         enum netdev_flags on, enum netdev_flags *old_flags);
 543
 544     /* Returns a sequence number which indicates changes in one of 'netdev''s
 545      * properties.  The returned sequence number must be nonzero so that
 546      * callers have a value which they may use as a reset when tracking
 547      * 'netdev'.
 548      *
 549      * Minimally, the returned sequence number is required to change whenever
 550      * 'netdev''s flags, features, ethernet address, or carrier changes.  The
 551      * returned sequence number is allowed to change even when 'netdev' doesn't
 552      * change, although implementations should try to avoid this. */
 553     unsigned int (*change_seq)(const struct netdev *netdev);
 554 };
 555 \f
 556 /* A data structure for capturing packets received by a network device.
 557  *
 558  * This structure should be treated as opaque by network device
 559  * implementations. */
 560 struct netdev_rx {
 561     const struct netdev_rx_class *rx_class;
 562     struct netdev_dev *netdev_dev;
 563 };
 564
 565 void netdev_rx_init(struct netdev_rx *, struct netdev_dev *,
 566                     const struct netdev_rx_class *);
 567 void netdev_rx_uninit(struct netdev_rx *);
 568 struct netdev_dev *netdev_rx_get_dev(const struct netdev_rx *);
 569
 570 struct netdev_rx_class {
 571     /* Destroys 'rx'. */
 572     void (*destroy)(struct netdev_rx *rx);
 573
 574     /* Attempts to receive a packet from 'rx' into the 'size' bytes in
 575      * 'buffer'.  If successful, returns the number of bytes in the received
 576      * packet, otherwise a negative errno value.  Returns -EAGAIN immediately
 577      * if no packet is ready to be received.
 578      *
 579      * Must return -EMSGSIZE, and discard the packet, if the received packet
 580      * is longer than 'size' bytes. */
 581     int (*recv)(struct netdev_rx *rx, void *buffer, size_t size);
 582
 583     /* Registers with the poll loop to wake up from the next call to
 584      * poll_block() when a packet is ready to be received with netdev_rx_recv()
 585      * on 'rx'. */
 586     void (*wait)(struct netdev_rx *rx);
 587
 588     /* Discards all packets waiting to be received from 'rx'. */
 589     int (*drain)(struct netdev_rx *rx);
 590 };
 591
 592 static inline void netdev_rx_assert_class(const struct netdev_rx *rx,
 593                                           const struct netdev_rx_class *class_)
 594 {
 595     ovs_assert(rx->rx_class == class_);
 596 }
 597
 598 int netdev_register_provider(const struct netdev_class *);
 599 int netdev_unregister_provider(const char *type);
 600 const struct netdev_class *netdev_lookup_provider(const char *type);
 601
 602 extern const struct netdev_class netdev_linux_class;
 603 extern const struct netdev_class netdev_internal_class;
 604 extern const struct netdev_class netdev_tap_class;
 605 #ifdef __FreeBSD__
 606 extern const struct netdev_class netdev_bsd_class;
 607 #endif
 608
 609 #ifdef  __cplusplus
 610 }
 611 #endif
 612
 613 #endif /* netdev.h */