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  * Network device implementations should treat this structure as opaque. */
  34 struct netdev {
  35     char *name;                         /* Name of network device. */
  36     const struct netdev_class *netdev_class; /* Functions to control
  37                                                 this device. */
  38     int ref_cnt;                        /* Times this devices was opened. */
  39     struct shash_node *node;            /* Pointer to element in global map. */
  40     struct list saved_flags_list; /* Contains "struct netdev_saved_flags". */
  41 };
  42
  43 void netdev_init(struct netdev *, const char *name,
  44                  const struct netdev_class *);
  45 void netdev_uninit(struct netdev *, bool destroy);
  46 const char *netdev_get_type(const struct netdev *);
  47 const struct netdev_class *netdev_get_class(const struct netdev *);
  48 const char *netdev_get_name(const struct netdev *);
  49 struct netdev *netdev_from_name(const char *name);
  50 void netdev_get_devices(const struct netdev_class *,
  51                         struct shash *device_list);
  52
  53 static inline void netdev_assert_class(const struct netdev *netdev,
  54                                            const struct netdev_class *class_)
  55 {
  56     ovs_assert(netdev->netdev_class == class_);
  57 }
  58
  59 /* Network device class structure, to be defined by each implementation of a
  60  * network device.
  61  *
  62  * These functions return 0 if successful or a positive errno value on failure,
  63  * except where otherwise noted. */
  64 struct netdev_class {
  65     /* Type of netdevs in this class, e.g. "system", "tap", "gre", etc.
  66      *
  67      * One of the providers should supply a "system" type, since this is
  68      * the type assumed if no type is specified when opening a netdev.
  69      * The "system" type corresponds to an existing network device on
  70      * the system. */
  71     const char *type;
  72
  73     /* Called when the netdev provider is registered, typically at program
  74      * startup.  Returning an error from this function will prevent any network
  75      * device in this class from being opened.
  76      *
  77      * This function may be set to null if a network device class needs no
  78      * initialization at registration time. */
  79     int (*init)(void);
  80
  81     /* Performs periodic work needed by netdevs of this class.  May be null if
  82      * no periodic work is necessary. */
  83     void (*run)(void);
  84
  85     /* Arranges for poll_block() to wake up if the "run" member function needs
  86      * to be called.  Implementations are additionally required to wake
  87      * whenever something changes in any of its netdevs which would cause their
  88      * ->change_seq() function to change its result.  May be null if nothing is
  89      * needed here. */
  90     void (*wait)(void);
  91
  92     /* Attempts to create a network device named 'name' in 'netdev_class'.  On
  93      * success sets 'netdevp' to the newly created device. */
  94     int (*create)(const struct netdev_class *netdev_class, const char *name,
  95                   struct netdev **netdevp);
  96
  97     /* Destroys 'netdev'.
  98      *
  99      * Netdev devices maintain a reference count that is incremented on
 100      * netdev_open() and decremented on netdev_close().  If 'netdev'
 101      * has a non-zero reference count, then this function will not be
 102      * called. */
 103     void (*destroy)(struct netdev *netdev);
 104
 105     /* Fetches the device 'netdev''s configuration, storing it in 'args'.
 106      * The caller owns 'args' and pre-initializes it to an empty smap.
 107      *
 108      * If this netdev class does not have any configuration options, this may
 109      * be a null pointer. */
 110     int (*get_config)(const struct netdev *netdev, struct smap *args);
 111
 112     /* Changes the device 'netdev''s configuration to 'args'.
 113      *
 114      * If this netdev class does not support configuration, this may be a null
 115      * pointer. */
 116     int (*set_config)(struct netdev *netdev, const struct smap *args);
 117
 118     /* Returns the tunnel configuration of 'netdev'.  If 'netdev' is
 119      * not a tunnel, returns null.
 120      *
 121      * If this function would always return null, it may be null instead. */
 122     const struct netdev_tunnel_config *
 123         (*get_tunnel_config)(const struct netdev *netdev);
 124
 125     /* Attempts to open a netdev_rx for receiving packets from 'netdev'.
 126      * Returns 0 if successful, otherwise a positive errno value.  Returns
 127      * EOPNOTSUPP to indicate that the network device does not implement packet
 128      * reception through this interface.  This function may be set to null if
 129      * it would always return EOPNOTSUPP anyhow.  (This will prevent the
 130      * network device from being usefully used by the netdev-based "userspace
 131      * datapath".)
 132      *
 133      * On success, the implementation must set '*rxp' to a 'netdev_rx' for
 134      * 'netdev' that it has already initialized (with netdev_rx_init()). */
 135     int (*rx_open)(struct netdev *netdev, struct netdev_rx **rxp);
 136
 137     /* Sends the 'size'-byte packet in 'buffer' on 'netdev'.  Returns 0 if
 138      * successful, otherwise a positive errno value.  Returns EAGAIN without
 139      * blocking if the packet cannot be queued immediately.  Returns EMSGSIZE
 140      * if a partial packet was transmitted or if the packet is too big or too
 141      * small to transmit on the device.
 142      *
 143      * The caller retains ownership of 'buffer' in all cases.
 144      *
 145      * The network device is expected to maintain a packet transmission queue,
 146      * so that the caller does not ordinarily have to do additional queuing of
 147      * packets.
 148      *
 149      * May return EOPNOTSUPP if a network device does not implement packet
 150      * transmission through this interface.  This function may be set to null
 151      * if it would always return EOPNOTSUPP anyhow.  (This will prevent the
 152      * network device from being usefully used by the netdev-based "userspace
 153      * datapath".  It will also prevent the OVS implementation of bonding from
 154      * working properly over 'netdev'.) */
 155     int (*send)(struct netdev *netdev, const void *buffer, size_t size);
 156
 157     /* Registers with the poll loop to wake up from the next call to
 158      * poll_block() when the packet transmission queue for 'netdev' has
 159      * sufficient room to transmit a packet with netdev_send().
 160      *
 161      * The network device is expected to maintain a packet transmission queue,
 162      * so that the caller does not ordinarily have to do additional queuing of
 163      * packets.  Thus, this function is unlikely to ever be useful.
 164      *
 165      * May be null if not needed, such as for a network device that does not
 166      * implement packet transmission through the 'send' member function. */
 167     void (*send_wait)(struct netdev *netdev);
 168
 169     /* Sets 'netdev''s Ethernet address to 'mac' */
 170     int (*set_etheraddr)(struct netdev *netdev, const uint8_t mac[6]);
 171
 172     /* Retrieves 'netdev''s Ethernet address into 'mac'.
 173      *
 174      * This address will be advertised as 'netdev''s MAC address through the
 175      * OpenFlow protocol, among other uses. */
 176     int (*get_etheraddr)(const struct netdev *netdev, uint8_t mac[6]);
 177
 178     /* Retrieves 'netdev''s MTU into '*mtup'.
 179      *
 180      * The MTU is the maximum size of transmitted (and received) packets, in
 181      * bytes, not including the hardware header; thus, this is typically 1500
 182      * bytes for Ethernet devices.
 183      *
 184      * If 'netdev' does not have an MTU (e.g. as some tunnels do not), then
 185      * this function should return EOPNOTSUPP.  This function may be set to
 186      * null if it would always return EOPNOTSUPP. */
 187     int (*get_mtu)(const struct netdev *netdev, int *mtup);
 188
 189     /* Sets 'netdev''s MTU to 'mtu'.
 190      *
 191      * If 'netdev' does not have an MTU (e.g. as some tunnels do not), then
 192      * this function should return EOPNOTSUPP.  This function may be set to
 193      * null if it would always return EOPNOTSUPP. */
 194     int (*set_mtu)(const struct netdev *netdev, int mtu);
 195
 196     /* Returns the ifindex of 'netdev', if successful, as a positive number.
 197      * On failure, returns a negative errno value.
 198      *
 199      * The desired semantics of the ifindex value are a combination of those
 200      * specified by POSIX for if_nametoindex() and by SNMP for ifIndex.  An
 201      * ifindex value should be unique within a host and remain stable at least
 202      * until reboot.  SNMP says an ifindex "ranges between 1 and the value of
 203      * ifNumber" but many systems do not follow this rule anyhow.
 204      *
 205      * This function may be set to null if it would always return -EOPNOTSUPP.
 206      */
 207     int (*get_ifindex)(const struct netdev *netdev);
 208
 209     /* Sets 'carrier' to true if carrier is active (link light is on) on
 210      * 'netdev'.
 211      *
 212      * May be null if device does not provide carrier status (will be always
 213      * up as long as device is up).
 214      */
 215     int (*get_carrier)(const struct netdev *netdev, bool *carrier);
 216
 217     /* Returns the number of times 'netdev''s carrier has changed since being
 218      * initialized.
 219      *
 220      * If null, callers will assume the number of carrier resets is zero. */
 221     long long int (*get_carrier_resets)(const struct netdev *netdev);
 222
 223     /* Forces ->get_carrier() to poll 'netdev''s MII registers for link status
 224      * instead of checking 'netdev''s carrier.  'netdev''s MII registers will
 225      * be polled once ever 'interval' milliseconds.  If 'netdev' does not
 226      * support MII, another method may be used as a fallback.  If 'interval' is
 227      * less than or equal to zero, reverts ->get_carrier() to its normal
 228      * behavior.
 229      *
 230      * Most network devices won't support this feature and will set this
 231      * function pointer to NULL, which is equivalent to returning EOPNOTSUPP.
 232      */
 233     int (*set_miimon_interval)(struct netdev *netdev, long long int interval);
 234
 235     /* Retrieves current device stats for 'netdev' into 'stats'.
 236      *
 237      * A network device that supports some statistics but not others, it should
 238      * set the values of the unsupported statistics to all-1-bits
 239      * (UINT64_MAX). */
 240     int (*get_stats)(const struct netdev *netdev, struct netdev_stats *);
 241
 242     /* Sets the device stats for 'netdev' to 'stats'.
 243      *
 244      * Most network devices won't support this feature and will set this
 245      * function pointer to NULL, which is equivalent to returning EOPNOTSUPP.
 246      *
 247      * Some network devices might only allow setting their stats to 0. */
 248     int (*set_stats)(struct netdev *netdev, const struct netdev_stats *);
 249
 250     /* Stores the features supported by 'netdev' into each of '*current',
 251      * '*advertised', '*supported', and '*peer'.  Each value is a bitmap of
 252      * NETDEV_F_* bits.
 253      *
 254      * This function may be set to null if it would always return EOPNOTSUPP.
 255      */
 256     int (*get_features)(const struct netdev *netdev,
 257                         enum netdev_features *current,
 258                         enum netdev_features *advertised,
 259                         enum netdev_features *supported,
 260                         enum netdev_features *peer);
 261
 262     /* Set the features advertised by 'netdev' to 'advertise', which is a
 263      * set of NETDEV_F_* bits.
 264      *
 265      * This function may be set to null for a network device that does not
 266      * support configuring advertisements. */
 267     int (*set_advertisements)(struct netdev *netdev,
 268                               enum netdev_features advertise);
 269
 270     /* Attempts to set input rate limiting (policing) policy, such that up to
 271      * 'kbits_rate' kbps of traffic is accepted, with a maximum accumulative
 272      * burst size of 'kbits' kb.
 273      *
 274      * This function may be set to null if policing is not supported. */
 275     int (*set_policing)(struct netdev *netdev, unsigned int kbits_rate,
 276                         unsigned int kbits_burst);
 277
 278     /* Adds to 'types' all of the forms of QoS supported by 'netdev', or leaves
 279      * it empty if 'netdev' does not support QoS.  Any names added to 'types'
 280      * should be documented as valid for the "type" column in the "QoS" table
 281      * in vswitchd/vswitch.xml (which is built as ovs-vswitchd.conf.db(8)).
 282      *
 283      * Every network device must support disabling QoS with a type of "", but
 284      * this function must not add "" to 'types'.
 285      *
 286      * The caller is responsible for initializing 'types' (e.g. with
 287      * sset_init()) before calling this function.  The caller retains ownership
 288      * of 'types'.
 289      *
 290      * May be NULL if 'netdev' does not support QoS at all. */
 291     int (*get_qos_types)(const struct netdev *netdev, struct sset *types);
 292
 293     /* Queries 'netdev' for its capabilities regarding the specified 'type' of
 294      * QoS.  On success, initializes 'caps' with the QoS capabilities.
 295      *
 296      * Should return EOPNOTSUPP if 'netdev' does not support 'type'.  May be
 297      * NULL if 'netdev' does not support QoS at all. */
 298     int (*get_qos_capabilities)(const struct netdev *netdev,
 299                                 const char *type,
 300                                 struct netdev_qos_capabilities *caps);
 301
 302     /* Queries 'netdev' about its currently configured form of QoS.  If
 303      * successful, stores the name of the current form of QoS into '*typep'
 304      * and any details of configuration as string key-value pairs in
 305      * 'details'.
 306      *
 307      * A '*typep' of "" indicates that QoS is currently disabled on 'netdev'.
 308      *
 309      * The caller initializes 'details' before calling this function.  The
 310      * caller takes ownership of the string key-values pairs added to
 311      * 'details'.
 312      *
 313      * The netdev retains ownership of '*typep'.
 314      *
 315      * '*typep' will be one of the types returned by netdev_get_qos_types() for
 316      * 'netdev'.  The contents of 'details' should be documented as valid for
 317      * '*typep' in the "other_config" column in the "QoS" table in
 318      * vswitchd/vswitch.xml (which is built as ovs-vswitchd.conf.db(8)).
 319      *
 320      * May be NULL if 'netdev' does not support QoS at all. */
 321     int (*get_qos)(const struct netdev *netdev,
 322                    const char **typep, struct smap *details);
 323
 324     /* Attempts to reconfigure QoS on 'netdev', changing the form of QoS to
 325      * 'type' with details of configuration from 'details'.
 326      *
 327      * On error, the previous QoS configuration is retained.
 328      *
 329      * When this function changes the type of QoS (not just 'details'), this
 330      * also resets all queue configuration for 'netdev' to their defaults
 331      * (which depend on the specific type of QoS).  Otherwise, the queue
 332      * configuration for 'netdev' is unchanged.
 333      *
 334      * 'type' should be "" (to disable QoS) or one of the types returned by
 335      * netdev_get_qos_types() for 'netdev'.  The contents of 'details' should
 336      * be documented as valid for the given 'type' in the "other_config" column
 337      * in the "QoS" table in vswitchd/vswitch.xml (which is built as
 338      * ovs-vswitchd.conf.db(8)).
 339      *
 340      * May be NULL if 'netdev' does not support QoS at all. */
 341     int (*set_qos)(struct netdev *netdev,
 342                    const char *type, const struct smap *details);
 343
 344     /* Queries 'netdev' for information about the queue numbered 'queue_id'.
 345      * If successful, adds that information as string key-value pairs to
 346      * 'details'.  Returns 0 if successful, otherwise a positive errno value.
 347      *
 348      * Should return EINVAL if 'queue_id' is greater than or equal to the
 349      * number of supported queues (as reported in the 'n_queues' member of
 350      * struct netdev_qos_capabilities by 'get_qos_capabilities').
 351      *
 352      * The caller initializes 'details' before calling this function.  The
 353      * caller takes ownership of the string key-values pairs added to
 354      * 'details'.
 355      *
 356      * The returned contents of 'details' should be documented as valid for the
 357      * given 'type' in the "other_config" column in the "Queue" table in
 358      * vswitchd/vswitch.xml (which is built as ovs-vswitchd.conf.db(8)).
 359      */
 360     int (*get_queue)(const struct netdev *netdev,
 361                      unsigned int queue_id, struct smap *details);
 362
 363     /* Configures the queue numbered 'queue_id' on 'netdev' with the key-value
 364      * string pairs in 'details'.  The contents of 'details' should be
 365      * documented as valid for the given 'type' in the "other_config" column in
 366      * the "Queue" table in vswitchd/vswitch.xml (which is built as
 367      * ovs-vswitchd.conf.db(8)).  Returns 0 if successful, otherwise a positive
 368      * errno value.  On failure, the given queue's configuration should be
 369      * unmodified.
 370      *
 371      * Should return EINVAL if 'queue_id' is greater than or equal to the
 372      * number of supported queues (as reported in the 'n_queues' member of
 373      * struct netdev_qos_capabilities by 'get_qos_capabilities'), or if
 374      * 'details' is invalid for the type of queue.
 375      *
 376      * This function does not modify 'details', and the caller retains
 377      * ownership of it.
 378      *
 379      * May be NULL if 'netdev' does not support QoS at all. */
 380     int (*set_queue)(struct netdev *netdev,
 381                      unsigned int queue_id, const struct smap *details);
 382
 383     /* Attempts to delete the queue numbered 'queue_id' from 'netdev'.
 384      *
 385      * Should return EINVAL if 'queue_id' is greater than or equal to the
 386      * number of supported queues (as reported in the 'n_queues' member of
 387      * struct netdev_qos_capabilities by 'get_qos_capabilities').  Should
 388      * return EOPNOTSUPP if 'queue_id' is valid but may not be deleted (e.g. if
 389      * 'netdev' has a fixed set of queues with the current QoS mode).
 390      *
 391      * May be NULL if 'netdev' does not support QoS at all, or if all of its
 392      * QoS modes have fixed sets of queues. */
 393     int (*delete_queue)(struct netdev *netdev, unsigned int queue_id);
 394
 395     /* Obtains statistics about 'queue_id' on 'netdev'.  Fills 'stats' with the
 396      * queue's statistics.  May set individual members of 'stats' to all-1-bits
 397      * if the statistic is unavailable.
 398      *
 399      * May be NULL if 'netdev' does not support QoS at all. */
 400     int (*get_queue_stats)(const struct netdev *netdev, unsigned int queue_id,
 401                            struct netdev_queue_stats *stats);
 402
 403     /* Iterates over all of 'netdev''s queues, calling 'cb' with the queue's
 404      * ID, its configuration, and the 'aux' specified by the caller.  The order
 405      * of iteration is unspecified, but (when successful) each queue is visited
 406      * exactly once.
 407      *
 408      * 'cb' will not modify or free the 'details' argument passed in.  It may
 409      * delete or modify the queue passed in as its 'queue_id' argument.  It may
 410      * modify but will not delete any other queue within 'netdev'.  If 'cb'
 411      * adds new queues, then ->dump_queues is allowed to visit some queues
 412      * twice or not at all.
 413      */
 414     int (*dump_queues)(const struct netdev *netdev,
 415                        void (*cb)(unsigned int queue_id,
 416                                   const struct smap *details,
 417                                   void *aux),
 418                        void *aux);
 419
 420     /* Iterates over all of 'netdev''s queues, calling 'cb' with the queue's
 421      * ID, its statistics, and the 'aux' specified by the caller.  The order of
 422      * iteration is unspecified, but (when successful) each queue must be
 423      * visited exactly once.
 424      *
 425      * 'cb' will not modify or free the statistics passed in. */
 426     int (*dump_queue_stats)(const struct netdev *netdev,
 427                             void (*cb)(unsigned int queue_id,
 428                                        struct netdev_queue_stats *,
 429                                        void *aux),
 430                             void *aux);
 431
 432     /* If 'netdev' has an assigned IPv4 address, sets '*address' to that
 433      * address and '*netmask' to the associated netmask.
 434      *
 435      * The following error values have well-defined meanings:
 436      *
 437      *   - EADDRNOTAVAIL: 'netdev' has no assigned IPv4 address.
 438      *
 439      *   - EOPNOTSUPP: No IPv4 network stack attached to 'netdev'.
 440      *
 441      * This function may be set to null if it would always return EOPNOTSUPP
 442      * anyhow. */
 443     int (*get_in4)(const struct netdev *netdev, struct in_addr *address,
 444                    struct in_addr *netmask);
 445
 446     /* Assigns 'addr' as 'netdev''s IPv4 address and 'mask' as its netmask.  If
 447      * 'addr' is INADDR_ANY, 'netdev''s IPv4 address is cleared.
 448      *
 449      * This function may be set to null if it would always return EOPNOTSUPP
 450      * anyhow. */
 451     int (*set_in4)(struct netdev *netdev, struct in_addr addr,
 452                    struct in_addr mask);
 453
 454     /* If 'netdev' has an assigned IPv6 address, sets '*in6' to that address.
 455      *
 456      * The following error values have well-defined meanings:
 457      *
 458      *   - EADDRNOTAVAIL: 'netdev' has no assigned IPv6 address.
 459      *
 460      *   - EOPNOTSUPP: No IPv6 network stack attached to 'netdev'.
 461      *
 462      * This function may be set to null if it would always return EOPNOTSUPP
 463      * anyhow. */
 464     int (*get_in6)(const struct netdev *netdev, struct in6_addr *in6);
 465
 466     /* Adds 'router' as a default IP gateway for the TCP/IP stack that
 467      * corresponds to 'netdev'.
 468      *
 469      * This function may be set to null if it would always return EOPNOTSUPP
 470      * anyhow. */
 471     int (*add_router)(struct netdev *netdev, struct in_addr router);
 472
 473     /* Looks up the next hop for 'host'.  If succesful, stores the next hop
 474      * gateway's address (0 if 'host' is on a directly connected network) in
 475      * '*next_hop' and a copy of the name of the device to reach 'host' in
 476      * '*netdev_name', and returns 0.  The caller is responsible for freeing
 477      * '*netdev_name' (by calling free()).
 478      *
 479      * This function may be set to null if it would always return EOPNOTSUPP
 480      * anyhow. */
 481     int (*get_next_hop)(const struct in_addr *host, struct in_addr *next_hop,
 482                         char **netdev_name);
 483
 484     /* Retrieves driver information of the device.
 485      *
 486      * Populates 'smap' with key-value pairs representing the status of the
 487      * device.  'smap' is a set of key-value string pairs representing netdev
 488      * type specific information.  For more information see
 489      * ovs-vswitchd.conf.db(5).
 490      *
 491      * The caller is responsible for destroying 'smap' and its data.
 492      *
 493      * This function may be set to null if it would always return EOPNOTSUPP
 494      * anyhow. */
 495     int (*get_status)(const struct netdev *netdev, struct smap *smap);
 496
 497     /* Looks up the ARP table entry for 'ip' on 'netdev' and stores the
 498      * corresponding MAC address in 'mac'.  A return value of ENXIO, in
 499      * particular, indicates that there is no ARP table entry for 'ip' on
 500      * 'netdev'.
 501      *
 502      * This function may be set to null if it would always return EOPNOTSUPP
 503      * anyhow. */
 504     int (*arp_lookup)(const struct netdev *netdev, ovs_be32 ip,
 505                       uint8_t mac[6]);
 506
 507     /* Retrieves the current set of flags on 'netdev' into '*old_flags'.  Then,
 508      * turns off the flags that are set to 1 in 'off' and turns on the flags
 509      * that are set to 1 in 'on'.  (No bit will be set to 1 in both 'off' and
 510      * 'on'; that is, off & on == 0.)
 511      *
 512      * This function may be invoked from a signal handler.  Therefore, it
 513      * should not do anything that is not signal-safe (such as logging). */
 514     int (*update_flags)(struct netdev *netdev, enum netdev_flags off,
 515                         enum netdev_flags on, enum netdev_flags *old_flags);
 516
 517     /* Returns a sequence number which indicates changes in one of 'netdev''s
 518      * properties.  The returned sequence number must be nonzero so that
 519      * callers have a value which they may use as a reset when tracking
 520      * 'netdev'.
 521      *
 522      * Minimally, the returned sequence number is required to change whenever
 523      * 'netdev''s flags, features, ethernet address, or carrier changes.  The
 524      * returned sequence number is allowed to change even when 'netdev' doesn't
 525      * change, although implementations should try to avoid this. */
 526     unsigned int (*change_seq)(const struct netdev *netdev);
 527 };
 528 \f
 529 /* A data structure for capturing packets received by a network device.
 530  *
 531  * This structure should be treated as opaque by network device
 532  * implementations. */
 533 struct netdev_rx {
 534     const struct netdev_rx_class *rx_class;
 535     struct netdev *netdev;
 536 };
 537
 538 void netdev_rx_init(struct netdev_rx *, struct netdev *,
 539                     const struct netdev_rx_class *);
 540 void netdev_rx_uninit(struct netdev_rx *);
 541 struct netdev *netdev_rx_get_netdev(const struct netdev_rx *);
 542
 543 struct netdev_rx_class {
 544     /* Destroys 'rx'. */
 545     void (*destroy)(struct netdev_rx *rx);
 546
 547     /* Attempts to receive a packet from 'rx' into the 'size' bytes in
 548      * 'buffer'.  If successful, returns the number of bytes in the received
 549      * packet, otherwise a negative errno value.  Returns -EAGAIN immediately
 550      * if no packet is ready to be received.
 551      *
 552      * Must return -EMSGSIZE, and discard the packet, if the received packet
 553      * is longer than 'size' bytes. */
 554     int (*recv)(struct netdev_rx *rx, void *buffer, size_t size);
 555
 556     /* Registers with the poll loop to wake up from the next call to
 557      * poll_block() when a packet is ready to be received with netdev_rx_recv()
 558      * on 'rx'. */
 559     void (*wait)(struct netdev_rx *rx);
 560
 561     /* Discards all packets waiting to be received from 'rx'. */
 562     int (*drain)(struct netdev_rx *rx);
 563 };
 564
 565 static inline void netdev_rx_assert_class(const struct netdev_rx *rx,
 566                                           const struct netdev_rx_class *class_)
 567 {
 568     ovs_assert(rx->rx_class == class_);
 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 #if defined(__FreeBSD__) || defined(__NetBSD__)
 579 extern const struct netdev_class netdev_bsd_class;
 580 #endif
 581
 582 #ifdef  __cplusplus
 583 }
 584 #endif
 585
 586 #endif /* netdev.h */