text: /*
   * Copyright (c) 2008-2015, 2017 Nicira, Inc.
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at:
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  #include <config.h>
  
  #include "dpif-netlink.h"
  
  #include <ctype.h>
  #include <errno.h>
  #include <fcntl.h>
  #include <inttypes.h>
  #include <net/if.h>
  #include <linux/types.h>
  #include <linux/pkt_sched.h>
  #include <poll.h>
  #include <stdlib.h>
  #include <strings.h>
  #include <sys/epoll.h>
  #include <sys/stat.h>
  #include <unistd.h>
  
  #include "bitmap.h"
  #include "dpif-provider.h"
  #include "dynamic-string.h"
  #include "flow.h"
  #include "fat-rwlock.h"
  #include "netdev.h"
  #include "netdev-linux.h"
  #include "netdev-vport.h"
  #include "netlink-conntrack.h"
  #include "netlink-notifier.h"
  #include "netlink-socket.h"
  #include "netlink.h"
  #include "odp-util.h"
  #include "ofpbuf.h"
  #include "packets.h"
  #include "poll-loop.h"
  #include "random.h"
  #include "shash.h"
  #include "sset.h"
  #include "timeval.h"
  #include "unaligned.h"
  #include "util.h"
  #include "openvswitch/vlog.h"
  
  VLOG_DEFINE_THIS_MODULE(dpif_netlink);
  #ifdef _WIN32
  enum { WINDOWS = 1 };
  #else
  enum { WINDOWS = 0 };
  #endif
  enum { MAX_PORTS = USHRT_MAX };
  
  /* This ethtool flag was introduced in Linux 2.6.24, so it might be
   * missing if we have old headers. */
  #define ETH_FLAG_LRO      (1 << 15)    /* LRO is enabled */
  
  struct dpif_netlink_dp {
      /* Generic Netlink header. */
      uint8_t cmd;
  
      /* struct ovs_header. */
      int dp_ifindex;
  
      /* Attributes. */
      const char *name;                  /* OVS_DP_ATTR_NAME. */
      const uint32_t *upcall_pid;        /* OVS_DP_ATTR_UPCALL_PID. */
      uint32_t user_features;            /* OVS_DP_ATTR_USER_FEATURES */
      const struct ovs_dp_stats *stats;  /* OVS_DP_ATTR_STATS. */
      const struct ovs_dp_megaflow_stats *megaflow_stats;
                                         /* OVS_DP_ATTR_MEGAFLOW_STATS.*/
  };
  
  static void dpif_netlink_dp_init(struct dpif_netlink_dp *);
  static int dpif_netlink_dp_from_ofpbuf(struct dpif_netlink_dp *,
                                         const struct ofpbuf *);
  static void dpif_netlink_dp_dump_start(struct nl_dump *);
  static int dpif_netlink_dp_transact(const struct dpif_netlink_dp *request,
                                      struct dpif_netlink_dp *reply,
                                      struct ofpbuf **bufp);
  static int dpif_netlink_dp_get(const struct dpif *,
                                 struct dpif_netlink_dp *reply,
                                 struct ofpbuf **bufp);
  
  struct dpif_netlink_flow {
      /* Generic Netlink header. */
      uint8_t cmd;
  
      /* struct ovs_header. */
      unsigned int nlmsg_flags;
      int dp_ifindex;
  
      /* Attributes.
       *
       * The 'stats' member points to 64-bit data that might only be aligned on
       * 32-bit boundaries, so get_unaligned_u64() should be used to access its
       * values.
       *
       * If 'actions' is nonnull then OVS_FLOW_ATTR_ACTIONS will be included in
       * the Netlink version of the command, even if actions_len is zero. */
      const struct nlattr *key;           /* OVS_FLOW_ATTR_KEY. */
      size_t key_len;
      const struct nlattr *mask;          /* OVS_FLOW_ATTR_MASK. */
      size_t mask_len;
      const struct nlattr *actions;       /* OVS_FLOW_ATTR_ACTIONS. */
      size_t actions_len;
      ovs_u128 ufid;                      /* OVS_FLOW_ATTR_FLOW_ID. */
      bool ufid_present;                  /* Is there a UFID? */
      bool ufid_terse;                    /* Skip serializing key/mask/acts? */
      const struct ovs_flow_stats *stats; /* OVS_FLOW_ATTR_STATS. */
      const uint8_t *tcp_flags;           /* OVS_FLOW_ATTR_TCP_FLAGS. */
      const ovs_32aligned_u64 *used;      /* OVS_FLOW_ATTR_USED. */
      bool clear;                         /* OVS_FLOW_ATTR_CLEAR. */
      bool probe;                         /* OVS_FLOW_ATTR_PROBE. */
  };
  
  static void dpif_netlink_flow_init(struct dpif_netlink_flow *);
  static int dpif_netlink_flow_from_ofpbuf(struct dpif_netlink_flow *,
                                           const struct ofpbuf *);
  static void dpif_netlink_flow_to_ofpbuf(const struct dpif_netlink_flow *,
                                          struct ofpbuf *);
  static int dpif_netlink_flow_transact(struct dpif_netlink_flow *request,
                                        struct dpif_netlink_flow *reply,
                                        struct ofpbuf **bufp);
  static void dpif_netlink_flow_get_stats(const struct dpif_netlink_flow *,
                                          struct dpif_flow_stats *);
  static void dpif_netlink_flow_to_dpif_flow(struct dpif *, struct dpif_flow *,
                                             const struct dpif_netlink_flow *);
  
  /* One of the dpif channels between the kernel and userspace. */
  struct dpif_channel {
      struct nl_sock *sock;       /* Netlink socket. */
      long long int last_poll;    /* Last time this channel was polled. */
  };
  
  #ifdef _WIN32
  #define VPORT_SOCK_POOL_SIZE 1
  /* On Windows, there is no native support for epoll.  There are equivalent
   * interfaces though, that are not used currently.  For simpicity, a pool of
   * netlink sockets is used.  Each socket is represented by 'struct
   * dpif_windows_vport_sock'.  Since it is a pool, multiple OVS ports may be
   * sharing the same socket.  In the future, we can add a reference count and
   * such fields. */
  struct dpif_windows_vport_sock {
      struct nl_sock *nl_sock;    /* netlink socket. */
  };
  #endif
  
  struct dpif_handler {
      struct dpif_channel *channels;/* Array of channels for each handler. */
      struct epoll_event *epoll_events;
      int epoll_fd;                 /* epoll fd that includes channel socks. */
      int n_events;                 /* Num events returned by epoll_wait(). */
      int event_offset;             /* Offset into 'epoll_events'. */
  
  #ifdef _WIN32
      /* Pool of sockets. */
      struct dpif_windows_vport_sock *vport_sock_pool;
      size_t last_used_pool_idx; /* Index to aid in allocating a
                                    socket in the pool to a port. */
  #endif
  };
  
  /* Datapath interface for the openvswitch Linux kernel module. */
  struct dpif_netlink {
      struct dpif dpif;
      int dp_ifindex;
  
      /* Upcall messages. */
      struct fat_rwlock upcall_lock;
      struct dpif_handler *handlers;
      uint32_t n_handlers;           /* Num of upcall handlers. */
      int uc_array_size;             /* Size of 'handler->channels' and */
                                     /* 'handler->epoll_events'. */
  
      /* Change notification. */
      struct nl_sock *port_notifier; /* vport multicast group subscriber. */
      bool refresh_channels;
  };
  
  static void report_loss(struct dpif_netlink *, struct dpif_channel *,
                          uint32_t ch_idx, uint32_t handler_id);
  
  static struct vlog_rate_limit error_rl = VLOG_RATE_LIMIT_INIT(9999, 5);
  
  /* Generic Netlink family numbers for OVS.
   *
   * Initialized by dpif_netlink_init(). */
  static int ovs_datapath_family;
  static int ovs_vport_family;
  static int ovs_flow_family;
  static int ovs_packet_family;
  
  /* Generic Netlink multicast groups for OVS.
   *
   * Initialized by dpif_netlink_init(). */
  static unsigned int ovs_vport_mcgroup;
  
  static int dpif_netlink_init(void);
  static int open_dpif(const struct dpif_netlink_dp *, struct dpif **);
  static uint32_t dpif_netlink_port_get_pid(const struct dpif *,
                                            odp_port_t port_no, uint32_t hash);
  static void dpif_netlink_handler_uninit(struct dpif_handler *handler);
  static int dpif_netlink_refresh_channels(struct dpif_netlink *,
                                           uint32_t n_handlers);
  static void dpif_netlink_vport_to_ofpbuf(const struct dpif_netlink_vport *,
                                           struct ofpbuf *);
  static int dpif_netlink_vport_from_ofpbuf(struct dpif_netlink_vport *,
                                            const struct ofpbuf *);
  
  static struct dpif_netlink *
  dpif_netlink_cast(const struct dpif *dpif)
  {
      dpif_assert_class(dpif, &dpif_netlink_class);
      return CONTAINER_OF(dpif, struct dpif_netlink, dpif);
  }
  
  static int
  dpif_netlink_enumerate(struct sset *all_dps,
                         const struct dpif_class *dpif_class OVS_UNUSED)
  {
      struct nl_dump dump;
      uint64_t reply_stub[NL_DUMP_BUFSIZE / 8];
      struct ofpbuf msg, buf;
      int error;
  
      error = dpif_netlink_init();
      if (error) {
          return error;
      }
  
      ofpbuf_use_stub(&buf, reply_stub, sizeof reply_stub);
      dpif_netlink_dp_dump_start(&dump);
      while (nl_dump_next(&dump, &msg, &buf)) {
          struct dpif_netlink_dp dp;
  
          if (!dpif_netlink_dp_from_ofpbuf(&dp, &msg)) {
              sset_add(all_dps, dp.name);
          }
      }
      ofpbuf_uninit(&buf);
      return nl_dump_done(&dump);
  }
  
  static int
  dpif_netlink_open(const struct dpif_class *class OVS_UNUSED, const char *name,
                    bool create, struct dpif **dpifp)
  {
      struct dpif_netlink_dp dp_request, dp;
      struct ofpbuf *buf;
      uint32_t upcall_pid;
      int error;
  
      error = dpif_netlink_init();
      if (error) {
          return error;
      }
  
      /* Create or look up datapath. */
      dpif_netlink_dp_init(&dp_request);
      if (create) {
          dp_request.cmd = OVS_DP_CMD_NEW;
          upcall_pid = 0;
          dp_request.upcall_pid = &upcall_pid;
      } else {
          /* Use OVS_DP_CMD_SET to report user features */
          dp_request.cmd = OVS_DP_CMD_SET;
      }
      dp_request.name = name;
      dp_request.user_features |= OVS_DP_F_UNALIGNED;
      dp_request.user_features |= OVS_DP_F_VPORT_PIDS;
      error = dpif_netlink_dp_transact(&dp_request, &dp, &buf);
      if (error) {
          return error;
      }
  
      error = open_dpif(&dp, dpifp);
      ofpbuf_delete(buf);
      return error;
  }
  
  static int
  open_dpif(const struct dpif_netlink_dp *dp, struct dpif **dpifp)
  {
      struct dpif_netlink *dpif;
  
      dpif = xzalloc(sizeof *dpif);
      dpif->port_notifier = NULL;
      fat_rwlock_init(&dpif->upcall_lock);
  
      dpif_init(&dpif->dpif, &dpif_netlink_class, dp->name,
                dp->dp_ifindex, dp->dp_ifindex);
  
      dpif->dp_ifindex = dp->dp_ifindex;
      *dpifp = &dpif->dpif;
  
      return 0;
  }
  
  /* Destroys the netlink sockets pointed by the elements in 'socksp'
   * and frees the 'socksp'.  */
  static void
  vport_del_socksp__(struct nl_sock **socksp, uint32_t n_socks)
  {
      size_t i;
  
      for (i = 0; i < n_socks; i++) {
          nl_sock_destroy(socksp[i]);
      }
  
      free(socksp);
  }
  
  /* Creates an array of netlink sockets.  Returns an array of the
   * corresponding pointers.  Records the error in 'error'. */
  static struct nl_sock **
  vport_create_socksp__(uint32_t n_socks, int *error)
  {
      struct nl_sock **socksp = xzalloc(n_socks * sizeof *socksp);
      size_t i;
  
      for (i = 0; i < n_socks; i++) {
          *error = nl_sock_create(NETLINK_GENERIC, &socksp[i]);
          if (*error) {
              goto error;
          }
      }
  
      return socksp;
  
  error:
      vport_del_socksp__(socksp, n_socks);
  
      return NULL;
  }
  
  #ifdef _WIN32
  static void
  vport_delete_sock_pool(struct dpif_handler *handler)
      OVS_REQ_WRLOCK(dpif->upcall_lock)
  {
      if (handler->vport_sock_pool) {
          uint32_t i;
          struct dpif_windows_vport_sock *sock_pool =
              handler->vport_sock_pool;
  
          for (i = 0; i < VPORT_SOCK_POOL_SIZE; i++) {
              if (sock_pool[i].nl_sock) {
                  nl_sock_unsubscribe_packets(sock_pool[i].nl_sock);
                  nl_sock_destroy(sock_pool[i].nl_sock);
                  sock_pool[i].nl_sock = NULL;
              }
          }
  
          free(handler->vport_sock_pool);
          handler->vport_sock_pool = NULL;
      }
  }
  
  static int
  vport_create_sock_pool(struct dpif_handler *handler)
      OVS_REQ_WRLOCK(dpif->upcall_lock)
  {
      struct dpif_windows_vport_sock *sock_pool;
      size_t i;
      int error = 0;
  
      sock_pool = xzalloc(VPORT_SOCK_POOL_SIZE * sizeof *sock_pool);
      for (i = 0; i < VPORT_SOCK_POOL_SIZE; i++) {
          error = nl_sock_create(NETLINK_GENERIC, &sock_pool[i].nl_sock);
          if (error) {
              goto error;
          }
  
          /* Enable the netlink socket to receive packets.  This is equivalent to
           * calling nl_sock_join_mcgroup() to receive events. */
          error = nl_sock_subscribe_packets(sock_pool[i].nl_sock);
          if (error) {
             goto error;
          }
      }
  
      handler->vport_sock_pool = sock_pool;
      handler->last_used_pool_idx = 0;
      return 0;
  
  error:
      vport_delete_sock_pool(handler);
      return error;
  }
  
  /* Returns an array pointers to netlink sockets.  The sockets are picked from a
   * pool. Records the error in 'error'. */
  static struct nl_sock **
  vport_create_socksp_windows(struct dpif_netlink *dpif, int *error)
      OVS_REQ_WRLOCK(dpif->upcall_lock)
  {
      uint32_t n_socks = dpif->n_handlers;
      struct nl_sock **socksp;
      size_t i;
  
      ovs_assert(n_socks <= 1);
      socksp = xzalloc(n_socks * sizeof *socksp);
  
      /* Pick netlink sockets to use in a round-robin fashion from each
       * handler's pool of sockets. */
      for (i = 0; i < n_socks; i++) {
          struct dpif_handler *handler = &dpif->handlers[i];
          struct dpif_windows_vport_sock *sock_pool = handler->vport_sock_pool;
          size_t index = handler->last_used_pool_idx;
  
          /* A pool of sockets is allocated when the handler is initialized. */
          if (sock_pool == NULL) {
              free(socksp);
              *error = EINVAL;
              return NULL;
          }
  
          ovs_assert(index < VPORT_SOCK_POOL_SIZE);
          socksp[i] = sock_pool[index].nl_sock;
          socksp[i] = sock_pool[index].nl_sock;
          ovs_assert(socksp[i]);
          index = (index == VPORT_SOCK_POOL_SIZE - 1) ? 0 : index + 1;
          handler->last_used_pool_idx = index;
      }
  
      return socksp;
  }
  
  static void
  vport_del_socksp_windows(struct dpif_netlink *dpif, struct nl_sock **socksp)
  {
      free(socksp);
  }
  #endif /* _WIN32 */
  
  static struct nl_sock **
  vport_create_socksp(struct dpif_netlink *dpif, int *error)
  {
  #ifdef _WIN32
      return vport_create_socksp_windows(dpif, error);
  #else
      return vport_create_socksp__(dpif->n_handlers, error);
  #endif
  }
  
  static void
  vport_del_socksp(struct dpif_netlink *dpif, struct nl_sock **socksp)
  {
  #ifdef _WIN32
      vport_del_socksp_windows(dpif, socksp);
  #else
      vport_del_socksp__(socksp, dpif->n_handlers);
  #endif
  }
  
  /* Given the array of pointers to netlink sockets 'socksp', returns
   * the array of corresponding pids. If the 'socksp' is NULL, returns
   * a single-element array of value 0. */
  static uint32_t *
  vport_socksp_to_pids(struct nl_sock **socksp, uint32_t n_socks)
  {
      uint32_t *pids;
  
      if (!socksp) {
          pids = xzalloc(sizeof *pids);
      } else {
          size_t i;
  
          pids = xzalloc(n_socks * sizeof *pids);
          for (i = 0; i < n_socks; i++) {
              pids[i] = nl_sock_pid(socksp[i]);
          }
      }
  
      return pids;
  }
  
  /* Given the port number 'port_idx', extracts the pids of netlink sockets
   * associated to the port and assigns it to 'upcall_pids'. */
  static bool
  vport_get_pids(struct dpif_netlink *dpif, uint32_t port_idx,
                 uint32_t **upcall_pids)
  {
      uint32_t *pids;
      size_t i;
  
      /* Since the nl_sock can only be assigned in either all
       * or none "dpif->handlers" channels, the following check
       * would suffice. */
      if (!dpif->handlers[0].channels[port_idx].sock) {
          return false;
      }
      ovs_assert(!WINDOWS || dpif->n_handlers <= 1);
  
      pids = xzalloc(dpif->n_handlers * sizeof *pids);
  
      for (i = 0; i < dpif->n_handlers; i++) {
          pids[i] = nl_sock_pid(dpif->handlers[i].channels[port_idx].sock);
      }
  
      *upcall_pids = pids;
  
      return true;
  }
  
  static int
  vport_add_channels(struct dpif_netlink *dpif, odp_port_t port_no,
                     struct nl_sock **socksp)
  {
      struct epoll_event event;
      uint32_t port_idx = odp_to_u32(port_no);
      size_t i, j;
      int error;
  
      if (dpif->handlers == NULL) {
          return 0;
      }
  
      /* We assume that the datapath densely chooses port numbers, which can
       * therefore be used as an index into 'channels' and 'epoll_events' of
       * 'dpif->handler'. */
      if (port_idx >= dpif->uc_array_size) {
          uint32_t new_size = port_idx + 1;
  
          if (new_size > MAX_PORTS) {
              VLOG_WARN_RL(&error_rl, "%s: datapath port %"PRIu32" too big",
                           dpif_name(&dpif->dpif), port_no);
              return EFBIG;
          }
  
          for (i = 0; i < dpif->n_handlers; i++) {
              struct dpif_handler *handler = &dpif->handlers[i];
  
              handler->channels = xrealloc(handler->channels,
                                           new_size * sizeof *handler->channels);
  
              for (j = dpif->uc_array_size; j < new_size; j++) {
                  handler->channels[j].sock = NULL;
              }
  
              handler->epoll_events = xrealloc(handler->epoll_events,
                  new_size * sizeof *handler->epoll_events);
  
          }
          dpif->uc_array_size = new_size;
      }
  
      memset(&event, 0, sizeof event);
      event.events = EPOLLIN;
      event.data.u32 = port_idx;
  
      for (i = 0; i < dpif->n_handlers; i++) {
          struct dpif_handler *handler = &dpif->handlers[i];
  
  #ifndef _WIN32
          if (epoll_ctl(handler->epoll_fd, EPOLL_CTL_ADD, nl_sock_fd(socksp[i]),
                        &event) < 0) {
              error = errno;
              goto error;
          }
  #endif
          dpif->handlers[i].channels[port_idx].sock = socksp[i];
          dpif->handlers[i].channels[port_idx].last_poll = LLONG_MIN;
      }
  
      return 0;
  
  error:
      for (j = 0; j < i; j++) {
  #ifndef _WIN32
          epoll_ctl(dpif->handlers[j].epoll_fd, EPOLL_CTL_DEL,
                    nl_sock_fd(socksp[j]), NULL);
  #endif
          dpif->handlers[j].channels[port_idx].sock = NULL;
      }
  
      return error;
  }
  
  static void
  vport_del_channels(struct dpif_netlink *dpif, odp_port_t port_no)
  {
      uint32_t port_idx = odp_to_u32(port_no);
      size_t i;
  
      if (!dpif->handlers || port_idx >= dpif->uc_array_size) {
          return;
      }
  
      /* Since the sock can only be assigned in either all or none
       * of "dpif->handlers" channels, the following check would
       * suffice. */
      if (!dpif->handlers[0].channels[port_idx].sock) {
          return;
      }
  
      for (i = 0; i < dpif->n_handlers; i++) {
          struct dpif_handler *handler = &dpif->handlers[i];
  #ifndef _WIN32
          epoll_ctl(handler->epoll_fd, EPOLL_CTL_DEL,
                    nl_sock_fd(handler->channels[port_idx].sock), NULL);
          nl_sock_destroy(handler->channels[port_idx].sock);
  #endif
          handler->channels[port_idx].sock = NULL;
          handler->event_offset = handler->n_events = 0;
      }
  }
  
  static void
  destroy_all_channels(struct dpif_netlink *dpif)
      OVS_REQ_WRLOCK(dpif->upcall_lock)
  {
      unsigned int i;
  
      if (!dpif->handlers) {
          return;
      }
  
      for (i = 0; i < dpif->uc_array_size; i++ ) {
          struct dpif_netlink_vport vport_request;
          uint32_t upcall_pids = 0;
  
          /* Since the sock can only be assigned in either all or none
           * of "dpif->handlers" channels, the following check would
           * suffice. */
          if (!dpif->handlers[0].channels[i].sock) {
              continue;
          }
  
          /* Turn off upcalls. */
          dpif_netlink_vport_init(&vport_request);
          vport_request.cmd = OVS_VPORT_CMD_SET;
          vport_request.dp_ifindex = dpif->dp_ifindex;
          vport_request.port_no = u32_to_odp(i);
          vport_request.n_upcall_pids = 1;
          vport_request.upcall_pids = &upcall_pids;
          dpif_netlink_vport_transact(&vport_request, NULL, NULL);
  
          vport_del_channels(dpif, u32_to_odp(i));
      }
  
      for (i = 0; i < dpif->n_handlers; i++) {
          struct dpif_handler *handler = &dpif->handlers[i];
  
          dpif_netlink_handler_uninit(handler);
          free(handler->epoll_events);
          free(handler->channels);
      }
  
      free(dpif->handlers);
      dpif->handlers = NULL;
      dpif->n_handlers = 0;
      dpif->uc_array_size = 0;
  }
  
  static void
  dpif_netlink_close(struct dpif *dpif_)
  {
      struct dpif_netlink *dpif = dpif_netlink_cast(dpif_);
  
      nl_sock_destroy(dpif->port_notifier);
  
      fat_rwlock_wrlock(&dpif->upcall_lock);
      destroy_all_channels(dpif);
      fat_rwlock_unlock(&dpif->upcall_lock);
  
      fat_rwlock_destroy(&dpif->upcall_lock);
      free(dpif);
  }
  
  static int
  dpif_netlink_destroy(struct dpif *dpif_)
  {
      struct dpif_netlink *dpif = dpif_netlink_cast(dpif_);
      struct dpif_netlink_dp dp;
  
      dpif_netlink_dp_init(&dp);
      dp.cmd = OVS_DP_CMD_DEL;
      dp.dp_ifindex = dpif->dp_ifindex;
      return dpif_netlink_dp_transact(&dp, NULL, NULL);
  }
  
  static bool
  dpif_netlink_run(struct dpif *dpif_)
  {
      struct dpif_netlink *dpif = dpif_netlink_cast(dpif_);
  
      if (dpif->refresh_channels) {
          dpif->refresh_channels = false;
          fat_rwlock_wrlock(&dpif->upcall_lock);
          dpif_netlink_refresh_channels(dpif, dpif->n_handlers);
          fat_rwlock_unlock(&dpif->upcall_lock);
      }
      return false;
  }
  
  static int
  dpif_netlink_get_stats(const struct dpif *dpif_, struct dpif_dp_stats *stats)
  {
      struct dpif_netlink_dp dp;
      struct ofpbuf *buf;
      int error;
  
      error = dpif_netlink_dp_get(dpif_, &dp, &buf);
      if (!error) {
          memset(stats, 0, sizeof *stats);
  
          if (dp.stats) {
              stats->n_hit    = get_32aligned_u64(&dp.stats->n_hit);
              stats->n_missed = get_32aligned_u64(&dp.stats->n_missed);
              stats->n_lost   = get_32aligned_u64(&dp.stats->n_lost);
              stats->n_flows  = get_32aligned_u64(&dp.stats->n_flows);
          }
  
          if (dp.megaflow_stats) {
              stats->n_masks = dp.megaflow_stats->n_masks;
              stats->n_mask_hit = get_32aligned_u64(
                  &dp.megaflow_stats->n_mask_hit);
          } else {
              stats->n_masks = UINT32_MAX;
              stats->n_mask_hit = UINT64_MAX;
          }
          ofpbuf_delete(buf);
      }
      return error;
  }
  
  static const char *
  get_vport_type(const struct dpif_netlink_vport *vport)
  {
      static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(5, 20);
  
      switch (vport->type) {
      case OVS_VPORT_TYPE_NETDEV: {
          const char *type = netdev_get_type_from_name(vport->name);
  
          return type ? type : "system";
      }
  
      case OVS_VPORT_TYPE_INTERNAL:
          return "internal";
  
      case OVS_VPORT_TYPE_GENEVE:
          return "geneve";
  
      case OVS_VPORT_TYPE_GRE:
          return "gre";
  
      case OVS_VPORT_TYPE_VXLAN:
          return "vxlan";
  
      case OVS_VPORT_TYPE_LISP:
          return "lisp";
  
      case OVS_VPORT_TYPE_STT:
          return "stt";
  
      case OVS_VPORT_TYPE_UNSPEC:
      case __OVS_VPORT_TYPE_MAX:
          break;
      }
  
      VLOG_WARN_RL(&rl, "dp%d: port `%s' has unsupported type %u",
                   vport->dp_ifindex, vport->name, (unsigned int) vport->type);
      return "unknown";
  }
  
  static enum ovs_vport_type
  netdev_to_ovs_vport_type(const struct netdev *netdev)
  {
      const char *type = netdev_get_type(netdev);
  
      if (!strcmp(type, "tap") || !strcmp(type, "system")) {
          return OVS_VPORT_TYPE_NETDEV;
      } else if (!strcmp(type, "internal")) {
          return OVS_VPORT_TYPE_INTERNAL;
      } else if (strstr(type, "stt")) {
          return OVS_VPORT_TYPE_STT;
      } else if (!strcmp(type, "geneve")) {
          return OVS_VPORT_TYPE_GENEVE;
      } else if (strstr(type, "gre")) {
          return OVS_VPORT_TYPE_GRE;
      } else if (!strcmp(type, "vxlan")) {
          return OVS_VPORT_TYPE_VXLAN;
      } else if (!strcmp(type, "lisp")) {
          return OVS_VPORT_TYPE_LISP;
      } else {
          return OVS_VPORT_TYPE_UNSPEC;
      }
  }
  
  static int
  dpif_netlink_port_add__(struct dpif_netlink *dpif, struct netdev *netdev,
                          odp_port_t *port_nop)
      OVS_REQ_WRLOCK(dpif->upcall_lock)
  {
      const struct netdev_tunnel_config *tnl_cfg;
      char namebuf[NETDEV_VPORT_NAME_BUFSIZE];
      const char *name = netdev_vport_get_dpif_port(netdev,
                                                    namebuf, sizeof namebuf);
      const char *type = netdev_get_type(netdev);
      struct dpif_netlink_vport request, reply;
      struct ofpbuf *buf;
      uint64_t options_stub[64 / 8];
      struct ofpbuf options;
      struct nl_sock **socksp = NULL;
      uint32_t *upcall_pids;
      int error = 0;
  
      if (dpif->handlers) {
          socksp = vport_create_socksp(dpif, &error);
          if (!socksp) {
              return error;
          }
      }
  
      dpif_netlink_vport_init(&request);
      request.cmd = OVS_VPORT_CMD_NEW;
      request.dp_ifindex = dpif->dp_ifindex;
      request.type = netdev_to_ovs_vport_type(netdev);
      if (request.type == OVS_VPORT_TYPE_UNSPEC) {
          VLOG_WARN_RL(&error_rl, "%s: cannot create port `%s' because it has "
                       "unsupported type `%s'",
                       dpif_name(&dpif->dpif), name, type);
          vport_del_socksp(dpif, socksp);
          return EINVAL;
      }
      request.name = name;
  
      if (request.type == OVS_VPORT_TYPE_NETDEV) {
  #ifdef _WIN32
          /* XXX : Map appropiate Windows handle */
  #else
          netdev_linux_ethtool_set_flag(netdev, ETH_FLAG_LRO, "LRO", false);
  #endif
      }
  
      tnl_cfg = netdev_get_tunnel_config(netdev);
      if (tnl_cfg && (tnl_cfg->dst_port != 0 || tnl_cfg->exts)) {
          ofpbuf_use_stack(&options, options_stub, sizeof options_stub);
          if (tnl_cfg->dst_port) {
              nl_msg_put_u16(&options, OVS_TUNNEL_ATTR_DST_PORT,
                             ntohs(tnl_cfg->dst_port));
          }
          if (tnl_cfg->exts) {
              size_t ext_ofs;
              int i;
  
              ext_ofs = nl_msg_start_nested(&options, OVS_TUNNEL_ATTR_EXTENSION);
              for (i = 0; i < 32; i++) {
                  if (tnl_cfg->exts & (1 << i)) {
                      nl_msg_put_flag(&options, i);
                  }
              }
              nl_msg_end_nested(&options, ext_ofs);
          }
          request.options = options.data;
          request.options_len = options.size;
      }
  
      request.port_no = *port_nop;
      upcall_pids = vport_socksp_to_pids(socksp, dpif->n_handlers);
      request.n_upcall_pids = socksp ? dpif->n_handlers : 1;
      request.upcall_pids = upcall_pids;
  
      error = dpif_netlink_vport_transact(&request, &reply, &buf);
      if (!error) {
          *port_nop = reply.port_no;
      } else {
          if (error == EBUSY && *port_nop != ODPP_NONE) {
              VLOG_INFO("%s: requested port %"PRIu32" is in use",
                        dpif_name(&dpif->dpif), *port_nop);
          }
  
          vport_del_socksp(dpif, socksp);
          goto exit;
      }
  
      if (socksp) {
          error = vport_add_channels(dpif, *port_nop, socksp);
          if (error) {
              VLOG_INFO("%s: could not add channel for port %s",
                        dpif_name(&dpif->dpif), name);
  
              /* Delete the port. */
              dpif_netlink_vport_init(&request);
              request.cmd = OVS_VPORT_CMD_DEL;
              request.dp_ifindex = dpif->dp_ifindex;
              request.port_no = *port_nop;
              dpif_netlink_vport_transact(&request, NULL, NULL);
              vport_del_socksp(dpif, socksp);
              goto exit;
          }
      }
      free(socksp);
  
  exit:
      ofpbuf_delete(buf);
      free(upcall_pids);
  
      return error;
  }
  
  static int
  dpif_netlink_port_add(struct dpif *dpif_, struct netdev *netdev,
                        odp_port_t *port_nop)
  {
      struct dpif_netlink *dpif = dpif_netlink_cast(dpif_);
      int error;
  
      fat_rwlock_wrlock(&dpif->upcall_lock);
      error = dpif_netlink_port_add__(dpif, netdev, port_nop);
      fat_rwlock_unlock(&dpif->upcall_lock);
  
      return error;
  }
  
  static int
  dpif_netlink_port_del__(struct dpif_netlink *dpif, odp_port_t port_no)
      OVS_REQ_WRLOCK(dpif->upcall_lock)
  {
      struct dpif_netlink_vport vport;
      int error;
  
      dpif_netlink_vport_init(&vport);
      vport.cmd = OVS_VPORT_CMD_DEL;
      vport.dp_ifindex = dpif->dp_ifindex;
      vport.port_no = port_no;
      error = dpif_netlink_vport_transact(&vport, NULL, NULL);
  
      vport_del_channels(dpif, port_no);
  
      return error;
  }
  
  static int
  dpif_netlink_port_del(struct dpif *dpif_, odp_port_t port_no)
  {
      struct dpif_netlink *dpif = dpif_netlink_cast(dpif_);
      int error;
  
      fat_rwlock_wrlock(&dpif->upcall_lock);
      error = dpif_netlink_port_del__(dpif, port_no);
      fat_rwlock_unlock(&dpif->upcall_lock);
  
      return error;
  }
  
  static int
  dpif_netlink_port_query__(const struct dpif_netlink *dpif, odp_port_t port_no,
                            const char *port_name, struct dpif_port *dpif_port)
  {
      struct dpif_netlink_vport request;
      struct dpif_netlink_vport reply;
      struct ofpbuf *buf;
      int error;
  
      dpif_netlink_vport_init(&request);
      request.cmd = OVS_VPORT_CMD_GET;
      request.dp_ifindex = dpif->dp_ifindex;
      request.port_no = port_no;
      request.name = port_name;
  
      error = dpif_netlink_vport_transact(&request, &reply, &buf);
      if (!error) {
          if (reply.dp_ifindex != request.dp_ifindex) {
              /* A query by name reported that 'port_name' is in some datapath
               * other than 'dpif', but the caller wants to know about 'dpif'. */
              error = ENODEV;
          } else if (dpif_port) {
              dpif_port->name = xstrdup(reply.name);
              dpif_port->type = xstrdup(get_vport_type(&reply));
              dpif_port->port_no = reply.port_no;
          }
          ofpbuf_delete(buf);
      }
      return error;
  }
  
  static int
  dpif_netlink_port_query_by_number(const struct dpif *dpif_, odp_port_t port_no,
                                    struct dpif_port *dpif_port)
  {
      struct dpif_netlink *dpif = dpif_netlink_cast(dpif_);
  
      return dpif_netlink_port_query__(dpif, port_no, NULL, dpif_port);
  }
  
  static int
  dpif_netlink_port_query_by_name(const struct dpif *dpif_, const char *devname,
                                struct dpif_port *dpif_port)
  {
      struct dpif_netlink *dpif = dpif_netlink_cast(dpif_);
  
      return dpif_netlink_port_query__(dpif, 0, devname, dpif_port);
  }
  
  static uint32_t
  dpif_netlink_port_get_pid__(const struct dpif_netlink *dpif,
                              odp_port_t port_no, uint32_t hash)
      OVS_REQ_RDLOCK(dpif->upcall_lock)
  {
      uint32_t port_idx = odp_to_u32(port_no);
      uint32_t pid = 0;
  
      if (dpif->handlers && dpif->uc_array_size > 0) {
          /* The ODPP_NONE "reserved" port number uses the "ovs-system"'s
           * channel, since it is not heavily loaded. */
          uint32_t idx = port_idx >= dpif->uc_array_size ? 0 : port_idx;
          struct dpif_handler *h = &dpif->handlers[hash % dpif->n_handlers];
  
          /* Needs to check in case the socket pointer is changed in between
           * the holding of upcall_lock.  A known case happens when the main
           * thread deletes the vport while the handler thread is handling
           * the upcall from that port. */
          if (h->channels[idx].sock) {
              pid = nl_sock_pid(h->channels[idx].sock);
          }
      }
  
      return pid;
  }
  
  static uint32_t
  dpif_netlink_port_get_pid(const struct dpif *dpif_, odp_port_t port_no,
                            uint32_t hash)
  {
      const struct dpif_netlink *dpif = dpif_netlink_cast(dpif_);
      uint32_t ret;
  
      fat_rwlock_rdlock(&dpif->upcall_lock);
      ret = dpif_netlink_port_get_pid__(dpif, port_no, hash);
      fat_rwlock_unlock(&dpif->upcall_lock);
  
      return ret;
  }
  
  static int
  dpif_netlink_flow_flush(struct dpif *dpif_)
  {
      const struct dpif_netlink *dpif = dpif_netlink_cast(dpif_);
      struct dpif_netlink_flow flow;
  
      dpif_netlink_flow_init(&flow);
      flow.cmd = OVS_FLOW_CMD_DEL;
      flow.dp_ifindex = dpif->dp_ifindex;
      return dpif_netlink_flow_transact(&flow, NULL, NULL);
  }
  
  struct dpif_netlink_port_state {
      struct nl_dump dump;
      struct ofpbuf buf;
  };
  
  static void
  dpif_netlink_port_dump_start__(const struct dpif_netlink *dpif,
                                 struct nl_dump *dump)
  {
      struct dpif_netlink_vport request;
      struct ofpbuf *buf;
  
      dpif_netlink_vport_init(&request);
      request.cmd = OVS_VPORT_CMD_GET;
      request.dp_ifindex = dpif->dp_ifindex;
  
      buf = ofpbuf_new(1024);
      dpif_netlink_vport_to_ofpbuf(&request, buf);
      nl_dump_start(dump, NETLINK_GENERIC, buf);
      ofpbuf_delete(buf);
  }
  
  static int
  dpif_netlink_port_dump_start(const struct dpif *dpif_, void **statep)
  {
      struct dpif_netlink *dpif = dpif_netlink_cast(dpif_);
      struct dpif_netlink_port_state *state;
  
      *statep = state = xmalloc(sizeof *state);
      dpif_netlink_port_dump_start__(dpif, &state->dump);
  
      ofpbuf_init(&state->buf, NL_DUMP_BUFSIZE);
      return 0;
  }
  
  static int
  dpif_netlink_port_dump_next__(const struct dpif_netlink *dpif,
                                struct nl_dump *dump,
                                struct dpif_netlink_vport *vport,
                                struct ofpbuf *buffer)
  {
      struct ofpbuf buf;
      int error;
  
      if (!nl_dump_next(dump, &buf, buffer)) {
          return EOF;
      }
  
      error = dpif_netlink_vport_from_ofpbuf(vport, &buf);
      if (error) {
          VLOG_WARN_RL(&error_rl, "%s: failed to parse vport record (%s)",
                       dpif_name(&dpif->dpif), ovs_strerror(error));
      }
      return error;
  }
  
  static int
  dpif_netlink_port_dump_next(const struct dpif *dpif_, void *state_,
                              struct dpif_port *dpif_port)
  {
      struct dpif_netlink *dpif = dpif_netlink_cast(dpif_);
      struct dpif_netlink_port_state *state = state_;
      struct dpif_netlink_vport vport;
      int error;
  
      error = dpif_netlink_port_dump_next__(dpif, &state->dump, &vport,
                                            &state->buf);
      if (error) {
          return error;
      }
      dpif_port->name = CONST_CAST(char *, vport.name);
      dpif_port->type = CONST_CAST(char *, get_vport_type(&vport));
      dpif_port->port_no = vport.port_no;
      return 0;
  }
  
  static int
  dpif_netlink_port_dump_done(const struct dpif *dpif_ OVS_UNUSED, void *state_)
  {
      struct dpif_netlink_port_state *state = state_;
      int error = nl_dump_done(&state->dump);
  
      ofpbuf_uninit(&state->buf);
      free(state);
      return error;
  }
  
  static int
  dpif_netlink_port_poll(const struct dpif *dpif_, char **devnamep)
  {
      struct dpif_netlink *dpif = dpif_netlink_cast(dpif_);
  
      /* Lazily create the Netlink socket to listen for notifications. */
      if (!dpif->port_notifier) {
          struct nl_sock *sock;
          int error;
  
          error = nl_sock_create(NETLINK_GENERIC, &sock);
          if (error) {
              return error;
          }
  
          error = nl_sock_join_mcgroup(sock, ovs_vport_mcgroup);
          if (error) {
              nl_sock_destroy(sock);
              return error;
          }
          dpif->port_notifier = sock;
  
          /* We have no idea of the current state so report that everything
           * changed. */
          return ENOBUFS;
      }
  
      for (;;) {
          static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(1, 5);
          uint64_t buf_stub[4096 / 8];
          struct ofpbuf buf;
          int error;
  
          ofpbuf_use_stub(&buf, buf_stub, sizeof buf_stub);
          error = nl_sock_recv(dpif->port_notifier, &buf, false);
          if (!error) {
              struct dpif_netlink_vport vport;
  
              error = dpif_netlink_vport_from_ofpbuf(&vport, &buf);
              if (!error) {
                  if (vport.dp_ifindex == dpif->dp_ifindex
                      && (vport.cmd == OVS_VPORT_CMD_NEW
                          || vport.cmd == OVS_VPORT_CMD_DEL
                          || vport.cmd == OVS_VPORT_CMD_SET)) {
                      VLOG_DBG("port_changed: dpif:%s vport:%s cmd:%"PRIu8,
                               dpif->dpif.full_name, vport.name, vport.cmd);
                      if (vport.cmd == OVS_VPORT_CMD_DEL && dpif->handlers) {
                          dpif->refresh_channels = true;
                      }
                      *devnamep = xstrdup(vport.name);
                      ofpbuf_uninit(&buf);
                      return 0;
                  }
              }
          } else if (error != EAGAIN) {
              VLOG_WARN_RL(&rl, "error reading or parsing netlink (%s)",
                           ovs_strerror(error));
              nl_sock_drain(dpif->port_notifier);
              error = ENOBUFS;
          }
  
          ofpbuf_uninit(&buf);
          if (error) {
              return error;
          }
      }
  }
  
  static void
  dpif_netlink_port_poll_wait(const struct dpif *dpif_)
  {
      const struct dpif_netlink *dpif = dpif_netlink_cast(dpif_);
  
      if (dpif->port_notifier) {
          nl_sock_wait(dpif->port_notifier, POLLIN);
      } else {
          poll_immediate_wake();
      }
  }
  
  static void
  dpif_netlink_flow_init_ufid(struct dpif_netlink_flow *request,
                              const ovs_u128 *ufid, bool terse)
  {
      if (ufid) {
          request->ufid = *ufid;
          request->ufid_present = true;
      } else {
          request->ufid_present = false;
      }
      request->ufid_terse = terse;
  }
  
  static void
  dpif_netlink_init_flow_get__(const struct dpif_netlink *dpif,
                               const struct nlattr *key, size_t key_len,
                               const ovs_u128 *ufid, bool terse,
                               struct dpif_netlink_flow *request)
  {
      dpif_netlink_flow_init(request);
      request->cmd = OVS_FLOW_CMD_GET;
      request->dp_ifindex = dpif->dp_ifindex;
      request->key = key;
      request->key_len = key_len;
      dpif_netlink_flow_init_ufid(request, ufid, terse);
  }
  
  static void
  dpif_netlink_init_flow_get(const struct dpif_netlink *dpif,
                             const struct dpif_flow_get *get,
                             struct dpif_netlink_flow *request)
  {
      dpif_netlink_init_flow_get__(dpif, get->key, get->key_len, get->ufid,
                                   false, request);
  }
  
  static int
  dpif_netlink_flow_get__(const struct dpif_netlink *dpif,
                          const struct nlattr *key, size_t key_len,
                          const ovs_u128 *ufid, bool terse,
                          struct dpif_netlink_flow *reply, struct ofpbuf **bufp)
  {
      struct dpif_netlink_flow request;
  
      dpif_netlink_init_flow_get__(dpif, key, key_len, ufid, terse, &request);
      return dpif_netlink_flow_transact(&request, reply, bufp);
  }
  
  static int
  dpif_netlink_flow_get(const struct dpif_netlink *dpif,
                        const struct dpif_netlink_flow *flow,
                        struct dpif_netlink_flow *reply, struct ofpbuf **bufp)
  {
      return dpif_netlink_flow_get__(dpif, flow->key, flow->key_len,
                                     flow->ufid_present ? &flow->ufid : NULL,
                                     false, reply, bufp);
  }
  
  static void
  dpif_netlink_init_flow_put(struct dpif_netlink *dpif,
                             const struct dpif_flow_put *put,
                             struct dpif_netlink_flow *request)
  {
      static const struct nlattr dummy_action;
  
      dpif_netlink_flow_init(request);
      request->cmd = (put->flags & DPIF_FP_CREATE
                      ? OVS_FLOW_CMD_NEW : OVS_FLOW_CMD_SET);
      request->dp_ifindex = dpif->dp_ifindex;
      request->key = put->key;
      request->key_len = put->key_len;
      request->mask = put->mask;
      request->mask_len = put->mask_len;
      dpif_netlink_flow_init_ufid(request, put->ufid, false);
  
      /* Ensure that OVS_FLOW_ATTR_ACTIONS will always be included. */
      request->actions = (put->actions
                          ? put->actions
                          : CONST_CAST(struct nlattr *, &dummy_action));
      request->actions_len = put->actions_len;
      if (put->flags & DPIF_FP_ZERO_STATS) {
          request->clear = true;
      }
      if (put->flags & DPIF_FP_PROBE) {
          request->probe = true;
      }
      request->nlmsg_flags = put->flags & DPIF_FP_MODIFY ? 0 : NLM_F_CREATE;
  }
  
  static void
  dpif_netlink_init_flow_del__(struct dpif_netlink *dpif,
                               const struct nlattr *key, size_t key_len,
                               const ovs_u128 *ufid, bool terse,
                               struct dpif_netlink_flow *request)
  {
      dpif_netlink_flow_init(request);
      request->cmd = OVS_FLOW_CMD_DEL;
      request->dp_ifindex = dpif->dp_ifindex;
      request->key = key;
      request->key_len = key_len;
      dpif_netlink_flow_init_ufid(request, ufid, terse);
  }
  
  static void
  dpif_netlink_init_flow_del(struct dpif_netlink *dpif,
                             const struct dpif_flow_del *del,
                             struct dpif_netlink_flow *request)
  {
      dpif_netlink_init_flow_del__(dpif, del->key, del->key_len,
                                   del->ufid, del->terse, request);
  }
  
  struct dpif_netlink_flow_dump {
      struct dpif_flow_dump up;
      struct nl_dump nl_dump;
      atomic_int status;
  };
  
  static struct dpif_netlink_flow_dump *
  dpif_netlink_flow_dump_cast(struct dpif_flow_dump *dump)
  {
      return CONTAINER_OF(dump, struct dpif_netlink_flow_dump, up);
  }
  
  static struct dpif_flow_dump *
  dpif_netlink_flow_dump_create(const struct dpif *dpif_, bool terse)
  {
      const struct dpif_netlink *dpif = dpif_netlink_cast(dpif_);
      struct dpif_netlink_flow_dump *dump;
      struct dpif_netlink_flow request;
      struct ofpbuf *buf;
  
      dump = xmalloc(sizeof *dump);
      dpif_flow_dump_init(&dump->up, dpif_);
  
      dpif_netlink_flow_init(&request);
      request.cmd = OVS_FLOW_CMD_GET;
      request.dp_ifindex = dpif->dp_ifindex;
      request.ufid_present = false;
      request.ufid_terse = terse;
  
      buf = ofpbuf_new(1024);
      dpif_netlink_flow_to_ofpbuf(&request, buf);
      nl_dump_start(&dump->nl_dump, NETLINK_GENERIC, buf);
      ofpbuf_delete(buf);
      atomic_init(&dump->status, 0);
      dump->up.terse = terse;
  
      return &dump->up;
  }
  
  static int
  dpif_netlink_flow_dump_destroy(struct dpif_flow_dump *dump_)
  {
      struct dpif_netlink_flow_dump *dump = dpif_netlink_flow_dump_cast(dump_);
      unsigned int nl_status = nl_dump_done(&dump->nl_dump);
      int dump_status;
  
      /* No other thread has access to 'dump' at this point. */
      atomic_read_relaxed(&dump->status, &dump_status);
      free(dump);
      return dump_status ? dump_status : nl_status;
  }
  
  struct dpif_netlink_flow_dump_thread {
      struct dpif_flow_dump_thread up;
      struct dpif_netlink_flow_dump *dump;
      struct dpif_netlink_flow flow;
      struct dpif_flow_stats stats;
      struct ofpbuf nl_flows;     /* Always used to store flows. */
      struct ofpbuf *nl_actions;  /* Used if kernel does not supply actions. */
  };
  
  static struct dpif_netlink_flow_dump_thread *
  dpif_netlink_flow_dump_thread_cast(struct dpif_flow_dump_thread *thread)
  {
      return CONTAINER_OF(thread, struct dpif_netlink_flow_dump_thread, up);
  }
  
  static struct dpif_flow_dump_thread *
  dpif_netlink_flow_dump_thread_create(struct dpif_flow_dump *dump_)
  {
      struct dpif_netlink_flow_dump *dump = dpif_netlink_flow_dump_cast(dump_);
      struct dpif_netlink_flow_dump_thread *thread;
  
      thread = xmalloc(sizeof *thread);
      dpif_flow_dump_thread_init(&thread->up, &dump->up);
      thread->dump = dump;
      ofpbuf_init(&thread->nl_flows, NL_DUMP_BUFSIZE);
      thread->nl_actions = NULL;
  
      return &thread->up;
  }
  
  static void
  dpif_netlink_flow_dump_thread_destroy(struct dpif_flow_dump_thread *thread_)
  {
      struct dpif_netlink_flow_dump_thread *thread
          = dpif_netlink_flow_dump_thread_cast(thread_);
  
      ofpbuf_uninit(&thread->nl_flows);
      ofpbuf_delete(thread->nl_actions);
      free(thread);
  }
  
  static void
  dpif_netlink_flow_to_dpif_flow(struct dpif *dpif, struct dpif_flow *dpif_flow,
                                 const struct dpif_netlink_flow *datapath_flow)
  {
      dpif_flow->key = datapath_flow->key;
      dpif_flow->key_len = datapath_flow->key_len;
      dpif_flow->mask = datapath_flow->mask;
      dpif_flow->mask_len = datapath_flow->mask_len;
      dpif_flow->actions = datapath_flow->actions;
      dpif_flow->actions_len = datapath_flow->actions_len;
      dpif_flow->ufid_present = datapath_flow->ufid_present;
      dpif_flow->pmd_id = PMD_ID_NULL;
      if (datapath_flow->ufid_present) {
          dpif_flow->ufid = datapath_flow->ufid;
      } else {
          ovs_assert(datapath_flow->key && datapath_flow->key_len);
          dpif_flow_hash(dpif, datapath_flow->key, datapath_flow->key_len,
                         &dpif_flow->ufid);
      }
      dpif_netlink_flow_get_stats(datapath_flow, &dpif_flow->stats);
  }
  
  static int
  dpif_netlink_flow_dump_next(struct dpif_flow_dump_thread *thread_,
                              struct dpif_flow *flows, int max_flows)
  {
      struct dpif_netlink_flow_dump_thread *thread
          = dpif_netlink_flow_dump_thread_cast(thread_);
      struct dpif_netlink_flow_dump *dump = thread->dump;
      struct dpif_netlink *dpif = dpif_netlink_cast(thread->up.dpif);
      int n_flows;
  
      ofpbuf_delete(thread->nl_actions);
      thread->nl_actions = NULL;
  
      n_flows = 0;
      while (!n_flows
             || (n_flows < max_flows && thread->nl_flows.size)) {
          struct dpif_netlink_flow datapath_flow;
          struct ofpbuf nl_flow;
          int error;
  
          /* Try to grab another flow. */
          if (!nl_dump_next(&dump->nl_dump, &nl_flow, &thread->nl_flows)) {
              break;
          }
  
          /* Convert the flow to our output format. */
          error = dpif_netlink_flow_from_ofpbuf(&datapath_flow, &nl_flow);
          if (error) {
              atomic_store_relaxed(&dump->status, error);
              break;
          }
  
          if (dump->up.terse || datapath_flow.actions) {
              /* Common case: we don't want actions, or the flow includes
               * actions. */
              dpif_netlink_flow_to_dpif_flow(&dpif->dpif, &flows[n_flows++],
                                             &datapath_flow);
          } else {
              /* Rare case: the flow does not include actions.  Retrieve this
               * individual flow again to get the actions. */
              error = dpif_netlink_flow_get(dpif, &datapath_flow,
                                            &datapath_flow, &thread->nl_actions);
              if (error == ENOENT) {
                  VLOG_DBG("dumped flow disappeared on get");
                  continue;
              } else if (error) {
                  VLOG_WARN("error fetching dumped flow: %s",
                            ovs_strerror(error));
                  atomic_store_relaxed(&dump->status, error);
                  break;
              }
  
              /* Save this flow.  Then exit, because we only have one buffer to
               * handle this case. */
              dpif_netlink_flow_to_dpif_flow(&dpif->dpif, &flows[n_flows++],
                                             &datapath_flow);
              break;
          }
      }
      return n_flows;
  }
  
  static void
  dpif_netlink_encode_execute(int dp_ifindex, const struct dpif_execute *d_exec,
                              struct ofpbuf *buf)
  {
      struct ovs_header *k_exec;
      size_t key_ofs;
  
      ofpbuf_prealloc_tailroom(buf, (64
                                     + dp_packet_size(d_exec->packet)
                                     + ODP_KEY_METADATA_SIZE
                                     + d_exec->actions_len));
  
      nl_msg_put_genlmsghdr(buf, 0, ovs_packet_family, NLM_F_REQUEST,
                            OVS_PACKET_CMD_EXECUTE, OVS_PACKET_VERSION);
  
      k_exec = ofpbuf_put_uninit(buf, sizeof *k_exec);
      k_exec->dp_ifindex = dp_ifindex;
  
      nl_msg_put_unspec(buf, OVS_PACKET_ATTR_PACKET,
                        dp_packet_data(d_exec->packet),
                        dp_packet_size(d_exec->packet));
  
      key_ofs = nl_msg_start_nested(buf, OVS_PACKET_ATTR_KEY);
      odp_key_from_pkt_metadata(buf, &d_exec->packet->md);
      nl_msg_end_nested(buf, key_ofs);
  
      nl_msg_put_unspec(buf, OVS_PACKET_ATTR_ACTIONS,
                        d_exec->actions, d_exec->actions_len);
      if (d_exec->probe) {
          nl_msg_put_flag(buf, OVS_PACKET_ATTR_PROBE);
      }
      if (d_exec->mtu) {
          nl_msg_put_u16(buf, OVS_PACKET_ATTR_MRU, d_exec->mtu);
      }
  }
  
  /* Executes, against 'dpif', up to the first 'n_ops' operations in 'ops'.
   * Returns the number actually executed (at least 1, if 'n_ops' is
   * positive). */
  static size_t
  dpif_netlink_operate__(struct dpif_netlink *dpif,
                         struct dpif_op **ops, size_t n_ops)
  {
      enum { MAX_OPS = 50 };
  
      struct op_auxdata {
          struct nl_transaction txn;
  
          struct ofpbuf request;
          uint64_t request_stub[1024 / 8];
  
          struct ofpbuf reply;
          uint64_t reply_stub[1024 / 8];
      } auxes[MAX_OPS];
  
      struct nl_transaction *txnsp[MAX_OPS];
      size_t i;
  
      n_ops = MIN(n_ops, MAX_OPS);
      for (i = 0; i < n_ops; i++) {
          struct op_auxdata *aux = &auxes[i];
          struct dpif_op *op = ops[i];
          struct dpif_flow_put *put;
          struct dpif_flow_del *del;
          struct dpif_flow_get *get;
          struct dpif_netlink_flow flow;
  
          ofpbuf_use_stub(&aux->request,
                          aux->request_stub, sizeof aux->request_stub);
          aux->txn.request = &aux->request;
  
          ofpbuf_use_stub(&aux->reply, aux->reply_stub, sizeof aux->reply_stub);
          aux->txn.reply = NULL;
  
          switch (op->type) {
          case DPIF_OP_FLOW_PUT:
              put = &op->u.flow_put;
              dpif_netlink_init_flow_put(dpif, put, &flow);
              if (put->stats) {
                  flow.nlmsg_flags |= NLM_F_ECHO;
                  aux->txn.reply = &aux->reply;
              }
              dpif_netlink_flow_to_ofpbuf(&flow, &aux->request);
              break;
  
          case DPIF_OP_FLOW_DEL:
              del = &op->u.flow_del;
              dpif_netlink_init_flow_del(dpif, del, &flow);
              if (del->stats) {
                  flow.nlmsg_flags |= NLM_F_ECHO;
                  aux->txn.reply = &aux->reply;
              }
              dpif_netlink_flow_to_ofpbuf(&flow, &aux->request);
              break;
  
          case DPIF_OP_EXECUTE:
              /* Can't execute a packet that won't fit in a Netlink attribute. */
              if (OVS_UNLIKELY(nl_attr_oversized(
                                   dp_packet_size(op->u.execute.packet)))) {
                  /* Report an error immediately if this is the first operation.
                   * Otherwise the easiest thing to do is to postpone to the next
                   * call (when this will be the first operation). */
                  if (i == 0) {
                      VLOG_ERR_RL(&error_rl,
                                  "dropping oversized %"PRIu32"-byte packet",
                                  dp_packet_size(op->u.execute.packet));
                      op->error = ENOBUFS;
                      return 1;
                  }
                  n_ops = i;
              } else {
                  dpif_netlink_encode_execute(dpif->dp_ifindex, &op->u.execute,
                                              &aux->request);
              }
              break;
  
          case DPIF_OP_FLOW_GET:
              get = &op->u.flow_get;
              dpif_netlink_init_flow_get(dpif, get, &flow);
              aux->txn.reply = get->buffer;
              dpif_netlink_flow_to_ofpbuf(&flow, &aux->request);
              break;
  
          default:
              OVS_NOT_REACHED();
          }
      }
  
      for (i = 0; i < n_ops; i++) {
          txnsp[i] = &auxes[i].txn;
      }
      nl_transact_multiple(NETLINK_GENERIC, txnsp, n_ops);
  
      for (i = 0; i < n_ops; i++) {
          struct op_auxdata *aux = &auxes[i];
          struct nl_transaction *txn = &auxes[i].txn;
          struct dpif_op *op = ops[i];
          struct dpif_flow_put *put;
          struct dpif_flow_del *del;
          struct dpif_flow_get *get;
  
          op->error = txn->error;
  
          switch (op->type) {
          case DPIF_OP_FLOW_PUT:
              put = &op->u.flow_put;
              if (put->stats) {
                  if (!op->error) {
                      struct dpif_netlink_flow reply;
  
                      op->error = dpif_netlink_flow_from_ofpbuf(&reply,
                                                                txn->reply);
                      if (!op->error) {
                          dpif_netlink_flow_get_stats(&reply, put->stats);
                      }
                  }
              }
              break;
  
          case DPIF_OP_FLOW_DEL:
              del = &op->u.flow_del;
              if (del->stats) {
                  if (!op->error) {
                      struct dpif_netlink_flow reply;
  
                      op->error = dpif_netlink_flow_from_ofpbuf(&reply,
                                                                txn->reply);
                      if (!op->error) {
                          dpif_netlink_flow_get_stats(&reply, del->stats);
                      }
                  }
              }
              break;
  
          case DPIF_OP_EXECUTE:
              break;
  
          case DPIF_OP_FLOW_GET:
              get = &op->u.flow_get;
              if (!op->error) {
                  struct dpif_netlink_flow reply;
  
                  op->error = dpif_netlink_flow_from_ofpbuf(&reply, txn->reply);
                  if (!op->error) {
                      dpif_netlink_flow_to_dpif_flow(&dpif->dpif, get->flow,
                                                     &reply);
                  }
              }
              break;
  
          default:
              OVS_NOT_REACHED();
          }
  
          ofpbuf_uninit(&aux->request);
          ofpbuf_uninit(&aux->reply);
      }
  
      return n_ops;
  }
  
  static void
  dpif_netlink_operate(struct dpif *dpif_, struct dpif_op **ops, size_t n_ops)
  {
      struct dpif_netlink *dpif = dpif_netlink_cast(dpif_);
  
      while (n_ops > 0) {
          size_t chunk = dpif_netlink_operate__(dpif, ops, n_ops);
          ops += chunk;
          n_ops -= chunk;
      }
  }
  
  #if _WIN32
  static void
  dpif_netlink_handler_uninit(struct dpif_handler *handler)
  {
      vport_delete_sock_pool(handler);
  }
  
  static int
  dpif_netlink_handler_init(struct dpif_handler *handler)
  {
      return vport_create_sock_pool(handler);
  }
  #else
  
  static int
  dpif_netlink_handler_init(struct dpif_handler *handler)
  {
      handler->epoll_fd = epoll_create(10);
      return handler->epoll_fd < 0 ? errno : 0;
  }
  
  static void
  dpif_netlink_handler_uninit(struct dpif_handler *handler)
  {
      close(handler->epoll_fd);
  }
  #endif
  
  /* Synchronizes 'channels' in 'dpif->handlers'  with the set of vports
   * currently in 'dpif' in the kernel, by adding a new set of channels for
   * any kernel vport that lacks one and deleting any channels that have no
   * backing kernel vports. */
  static int
  dpif_netlink_refresh_channels(struct dpif_netlink *dpif, uint32_t n_handlers)
      OVS_REQ_WRLOCK(dpif->upcall_lock)
  {
      unsigned long int *keep_channels;
      struct dpif_netlink_vport vport;
      size_t keep_channels_nbits;
      struct nl_dump dump;
      uint64_t reply_stub[NL_DUMP_BUFSIZE / 8];
      struct ofpbuf buf;
      int retval = 0;
      size_t i;
  
      ovs_assert(!WINDOWS || n_handlers <= 1);
      ovs_assert(!WINDOWS || dpif->n_handlers <= 1);
  
      if (dpif->n_handlers != n_handlers) {
          destroy_all_channels(dpif);
          dpif->handlers = xzalloc(n_handlers * sizeof *dpif->handlers);
          for (i = 0; i < n_handlers; i++) {
              int error;
              struct dpif_handler *handler = &dpif->handlers[i];
  
              error = dpif_netlink_handler_init(handler);
              if (error) {
                  size_t j;
  
                  for (j = 0; j < i; j++) {
                      struct dpif_handler *tmp = &dpif->handlers[j];
                      dpif_netlink_handler_uninit(tmp);
                  }
                  free(dpif->handlers);
                  dpif->handlers = NULL;
  
                  return error;
              }
          }
          dpif->n_handlers = n_handlers;
      }
  
      for (i = 0; i < n_handlers; i++) {
          struct dpif_handler *handler = &dpif->handlers[i];
  
          handler->event_offset = handler->n_events = 0;
      }
  
      keep_channels_nbits = dpif->uc_array_size;
      keep_channels = bitmap_allocate(keep_channels_nbits);
  
      ofpbuf_use_stub(&buf, reply_stub, sizeof reply_stub);
      dpif_netlink_port_dump_start__(dpif, &dump);
      while (!dpif_netlink_port_dump_next__(dpif, &dump, &vport, &buf)) {
          uint32_t port_no = odp_to_u32(vport.port_no);
          uint32_t *upcall_pids = NULL;
          int error;
  
          if (port_no >= dpif->uc_array_size
              || !vport_get_pids(dpif, port_no, &upcall_pids)) {
              struct nl_sock **socksp = vport_create_socksp(dpif, &error);
  
              if (!socksp) {
                  goto error;
              }
  
              error = vport_add_channels(dpif, vport.port_no, socksp);
              if (error) {
                  VLOG_INFO("%s: could not add channels for port %s",
                            dpif_name(&dpif->dpif), vport.name);
                  vport_del_socksp(dpif, socksp);
                  retval = error;
                  goto error;
              }
              upcall_pids = vport_socksp_to_pids(socksp, dpif->n_handlers);
              free(socksp);
          }
  
          /* Configure the vport to deliver misses to 'sock'. */
          if (vport.upcall_pids[0] == 0
              || vport.n_upcall_pids != dpif->n_handlers
              || memcmp(upcall_pids, vport.upcall_pids, n_handlers * sizeof
                        *upcall_pids)) {
              struct dpif_netlink_vport vport_request;
  
              dpif_netlink_vport_init(&vport_request);
              vport_request.cmd = OVS_VPORT_CMD_SET;
              vport_request.dp_ifindex = dpif->dp_ifindex;
              vport_request.port_no = vport.port_no;
              vport_request.n_upcall_pids = dpif->n_handlers;
              vport_request.upcall_pids = upcall_pids;
              error = dpif_netlink_vport_transact(&vport_request, NULL, NULL);
              if (error) {
                  VLOG_WARN_RL(&error_rl,
                               "%s: failed to set upcall pid on port: %s",
                               dpif_name(&dpif->dpif), ovs_strerror(error));
  
                  if (error != ENODEV && error != ENOENT) {
                      retval = error;
                  } else {
                      /* The vport isn't really there, even though the dump says
                       * it is.  Probably we just hit a race after a port
                       * disappeared. */
                  }
                  goto error;
              }
          }
  
          if (port_no < keep_channels_nbits) {
              bitmap_set1(keep_channels, port_no);
          }
          free(upcall_pids);
          continue;
  
      error:
          free(upcall_pids);
          vport_del_channels(dpif, vport.port_no);
      }
      nl_dump_done(&dump);
      ofpbuf_uninit(&buf);
  
      /* Discard any saved channels that we didn't reuse. */
      for (i = 0; i < keep_channels_nbits; i++) {
          if (!bitmap_is_set(keep_channels, i)) {
              vport_del_channels(dpif, u32_to_odp(i));
          }
      }
      free(keep_channels);
  
      return retval;
  }
  
  static int
  dpif_netlink_recv_set__(struct dpif_netlink *dpif, bool enable)
      OVS_REQ_WRLOCK(dpif->upcall_lock)
  {
      if ((dpif->handlers != NULL) == enable) {
          return 0;
      } else if (!enable) {
          destroy_all_channels(dpif);
          return 0;
      } else {
          return dpif_netlink_refresh_channels(dpif, 1);
      }
  }
  
  static int
  dpif_netlink_recv_set(struct dpif *dpif_, bool enable)
  {
      struct dpif_netlink *dpif = dpif_netlink_cast(dpif_);
      int error;
  
      fat_rwlock_wrlock(&dpif->upcall_lock);
      error = dpif_netlink_recv_set__(dpif, enable);
      fat_rwlock_unlock(&dpif->upcall_lock);
  
      return error;
  }
  
  static int
  dpif_netlink_handlers_set(struct dpif *dpif_, uint32_t n_handlers)
  {
      struct dpif_netlink *dpif = dpif_netlink_cast(dpif_);
      int error = 0;
  
  #ifdef _WIN32
      /* Multiple upcall handlers will be supported once kernel datapath supports
       * it. */
      if (n_handlers > 1) {
          return error;
      }
  #endif
  
      fat_rwlock_wrlock(&dpif->upcall_lock);
      if (dpif->handlers) {
          error = dpif_netlink_refresh_channels(dpif, n_handlers);
      }
      fat_rwlock_unlock(&dpif->upcall_lock);
  
      return error;
  }
  
  static int
  dpif_netlink_queue_to_priority(const struct dpif *dpif OVS_UNUSED,
                               uint32_t queue_id, uint32_t *priority)
  {
      if (queue_id < 0xf000) {
          *priority = TC_H_MAKE(1 << 16, queue_id + 1);
          return 0;
      } else {
          return EINVAL;
      }
  }
  
  static int
  parse_odp_packet(const struct dpif_netlink *dpif, struct ofpbuf *buf,
                   struct dpif_upcall *upcall, int *dp_ifindex)
  {
      static const struct nl_policy ovs_packet_policy[] = {
          /* Always present. */
          [OVS_PACKET_ATTR_PACKET] = { .type = NL_A_UNSPEC,
                                       .min_len = ETH_HEADER_LEN },
          [OVS_PACKET_ATTR_KEY] = { .type = NL_A_NESTED },
  
          /* OVS_PACKET_CMD_ACTION only. */
          [OVS_PACKET_ATTR_USERDATA] = { .type = NL_A_UNSPEC, .optional = true },
          [OVS_PACKET_ATTR_EGRESS_TUN_KEY] = { .type = NL_A_NESTED, .optional = true },
          [OVS_PACKET_ATTR_ACTIONS] = { .type = NL_A_NESTED, .optional = true },
          [OVS_PACKET_ATTR_MRU] = { .type = NL_A_U16, .optional = true }
      };
  
      struct ovs_header *ovs_header;
      struct nlattr *a[ARRAY_SIZE(ovs_packet_policy)];
      struct nlmsghdr *nlmsg;
      struct genlmsghdr *genl;
      struct ofpbuf b;
      int type;
  
      ofpbuf_use_const(&b, buf->data, buf->size);
  
      nlmsg = ofpbuf_try_pull(&b, sizeof *nlmsg);
      genl = ofpbuf_try_pull(&b, sizeof *genl);
      ovs_header = ofpbuf_try_pull(&b, sizeof *ovs_header);
      if (!nlmsg || !genl || !ovs_header
          || nlmsg->nlmsg_type != ovs_packet_family
          || !nl_policy_parse(&b, 0, ovs_packet_policy, a,
                              ARRAY_SIZE(ovs_packet_policy))) {
          return EINVAL;
      }
  
      type = (genl->cmd == OVS_PACKET_CMD_MISS ? DPIF_UC_MISS
              : genl->cmd == OVS_PACKET_CMD_ACTION ? DPIF_UC_ACTION
              : -1);
      
      /*add by Zhiheng Liu, for packet Hash*/
      /*DPIF_UC_HASH*/
      if(genl->cmd == OVS_PACKET_CMD_HASH)
      {
          type = DPIF_UC_HASH;
      }
      
      if (type < 0) {
          return EINVAL;
      }
  
      /* (Re)set ALL fields of '*upcall' on successful return. */
      upcall->type = type;
      upcall->key = CONST_CAST(struct nlattr *,
                               nl_attr_get(a[OVS_PACKET_ATTR_KEY]));
      upcall->key_len = nl_attr_get_size(a[OVS_PACKET_ATTR_KEY]);
      dpif_flow_hash(&dpif->dpif, upcall->key, upcall->key_len, &upcall->ufid);
      upcall->userdata = a[OVS_PACKET_ATTR_USERDATA];
      upcall->out_tun_key = a[OVS_PACKET_ATTR_EGRESS_TUN_KEY];
      upcall->actions = a[OVS_PACKET_ATTR_ACTIONS];
      upcall->mru = a[OVS_PACKET_ATTR_MRU];
  
      /* Allow overwriting the netlink attribute header without reallocating. */
      dp_packet_use_stub(&upcall->packet,
                      CONST_CAST(struct nlattr *,
                                 nl_attr_get(a[OVS_PACKET_ATTR_PACKET])) - 1,
                      nl_attr_get_size(a[OVS_PACKET_ATTR_PACKET]) +
                      sizeof(struct nlattr));
      dp_packet_set_data(&upcall->packet,
                      (char *)dp_packet_data(&upcall->packet) + sizeof(struct nlattr));
      dp_packet_set_size(&upcall->packet, nl_attr_get_size(a[OVS_PACKET_ATTR_PACKET]));
  
      *dp_ifindex = ovs_header->dp_ifindex;
  
      return 0;
  }
  
  #ifdef _WIN32
  #define PACKET_RECV_BATCH_SIZE 50
  static int
  dpif_netlink_recv_windows(struct dpif_netlink *dpif, uint32_t handler_id,
                            struct dpif_upcall *upcall, struct ofpbuf *buf)
      OVS_REQ_RDLOCK(dpif->upcall_lock)
  {
      struct dpif_handler *handler;
      int read_tries = 0;
      struct dpif_windows_vport_sock *sock_pool;
      uint32_t i;
  
      if (!dpif->handlers) {
          return EAGAIN;
      }
  
      /* Only one handler is supported currently. */
      if (handler_id >= 1) {
          return EAGAIN;
      }
  
      if (handler_id >= dpif->n_handlers) {
          return EAGAIN;
      }
  
      handler = &dpif->handlers[handler_id];
      sock_pool = handler->vport_sock_pool;
  
      for (i = 0; i < VPORT_SOCK_POOL_SIZE; i++) {
          for (;;) {
              int dp_ifindex;
              int error;
  
              if (++read_tries > PACKET_RECV_BATCH_SIZE) {
                  return EAGAIN;
              }
  
              error = nl_sock_recv(sock_pool[i].nl_sock, buf, false);
              if (error == ENOBUFS) {
                  /* ENOBUFS typically means that we've received so many
                   * packets that the buffer overflowed.  Try again
                   * immediately because there's almost certainly a packet
                   * waiting for us. */
                  /* XXX: report_loss(dpif, ch, idx, handler_id); */
                  continue;
              }
  
              /* XXX: ch->last_poll = time_msec(); */
              if (error) {
                  if (error == EAGAIN) {
                      break;
                  }
                  return error;
              }
  
              error = parse_odp_packet(dpif, buf, upcall, &dp_ifindex);
              if (!error && dp_ifindex == dpif->dp_ifindex) {
                  return 0;
              } else if (error) {
                  return error;
              }
          }
      }
  
      return EAGAIN;
  }
  #else
  static int
  dpif_netlink_recv__(struct dpif_netlink *dpif, uint32_t handler_id,
                      struct dpif_upcall *upcall, struct ofpbuf *buf)
      OVS_REQ_RDLOCK(dpif->upcall_lock)
  {
      struct dpif_handler *handler;
      int read_tries = 0;
  
      if (!dpif->handlers || handler_id >= dpif->n_handlers) {
          return EAGAIN;
      }
  
      handler = &dpif->handlers[handler_id];
      if (handler->event_offset >= handler->n_events) {
          int retval;
  
          handler->event_offset = handler->n_events = 0;
  
          do {
              retval = epoll_wait(handler->epoll_fd, handler->epoll_events,
                                  dpif->uc_array_size, 0);
          } while (retval < 0 && errno == EINTR);
  
          if (retval < 0) {
              static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(1, 1);
              VLOG_WARN_RL(&rl, "epoll_wait failed (%s)", ovs_strerror(errno));
          } else if (retval > 0) {
              handler->n_events = retval;
          }
      }
  
      while (handler->event_offset < handler->n_events) {
          int idx = handler->epoll_events[handler->event_offset].data.u32;
          struct dpif_channel *ch = &dpif->handlers[handler_id].channels[idx];
  
          handler->event_offset++;
  
          for (;;) {
              int dp_ifindex;
              int error;
  
              if (++read_tries > 50) {
                  return EAGAIN;
              }
  
              error = nl_sock_recv(ch->sock, buf, false);
              if (error == ENOBUFS) {
                  /* ENOBUFS typically means that we've received so many
                   * packets that the buffer overflowed.  Try again
                   * immediately because there's almost certainly a packet
                   * waiting for us. */
                  report_loss(dpif, ch, idx, handler_id);
                  continue;
              }
  
              ch->last_poll = time_msec();
              if (error) {
                  if (error == EAGAIN) {
                      break;
                  }
                  return error;
              }
  
              error = parse_odp_packet(dpif, buf, upcall, &dp_ifindex);
              if (!error && dp_ifindex == dpif->dp_ifindex) {
                  return 0;
              } else if (error) {
                  return error;
              }
          }
      }
  
      return EAGAIN;
  }
  #endif
  
  static int
  dpif_netlink_recv(struct dpif *dpif_, uint32_t handler_id,
                    struct dpif_upcall *upcall, struct ofpbuf *buf)
  {
      struct dpif_netlink *dpif = dpif_netlink_cast(dpif_);
      int error;
  
      fat_rwlock_rdlock(&dpif->upcall_lock);
  #ifdef _WIN32
      error = dpif_netlink_recv_windows(dpif, handler_id, upcall, buf);
  #else
      error = dpif_netlink_recv__(dpif, handler_id, upcall, buf);
  #endif
      fat_rwlock_unlock(&dpif->upcall_lock);
  
      return error;
  }
  
  static void
  dpif_netlink_recv_wait__(struct dpif_netlink *dpif, uint32_t handler_id)
      OVS_REQ_RDLOCK(dpif->upcall_lock)
  {
  #ifdef _WIN32
      uint32_t i;
      struct dpif_windows_vport_sock *sock_pool =
          dpif->handlers[handler_id].vport_sock_pool;
  
      /* Only one handler is supported currently. */
      if (handler_id >= 1) {
          return;
      }
  
      for (i = 0; i < VPORT_SOCK_POOL_SIZE; i++) {
          nl_sock_wait(sock_pool[i].nl_sock, POLLIN);
      }
  #else
      if (dpif->handlers && handler_id < dpif->n_handlers) {
          struct dpif_handler *handler = &dpif->handlers[handler_id];
  
          poll_fd_wait(handler->epoll_fd, POLLIN);
      }
  #endif
  }
  
  static void
  dpif_netlink_recv_wait(struct dpif *dpif_, uint32_t handler_id)
  {
      struct dpif_netlink *dpif = dpif_netlink_cast(dpif_);
  
      fat_rwlock_rdlock(&dpif->upcall_lock);
      dpif_netlink_recv_wait__(dpif, handler_id);
      fat_rwlock_unlock(&dpif->upcall_lock);
  }
  
  static void
  dpif_netlink_recv_purge__(struct dpif_netlink *dpif)
      OVS_REQ_WRLOCK(dpif->upcall_lock)
  {
      if (dpif->handlers) {
          size_t i, j;
  
          for (i = 0; i < dpif->uc_array_size; i++ ) {
              if (!dpif->handlers[0].channels[i].sock) {
                  continue;
              }
  
              for (j = 0; j < dpif->n_handlers; j++) {
                  nl_sock_drain(dpif->handlers[j].channels[i].sock);
              }
          }
      }
  }
  
  static void
  dpif_netlink_recv_purge(struct dpif *dpif_)
  {
      struct dpif_netlink *dpif = dpif_netlink_cast(dpif_);
  
      fat_rwlock_wrlock(&dpif->upcall_lock);
      dpif_netlink_recv_purge__(dpif);
      fat_rwlock_unlock(&dpif->upcall_lock);
  }
  
  static char *
  dpif_netlink_get_datapath_version(void)
  {
      char *version_str = NULL;
  
  #ifdef __linux__
  
  #define MAX_VERSION_STR_SIZE 80
  #define LINUX_DATAPATH_VERSION_FILE  "/sys/module/openvswitch/version"
      FILE *f;
  
      f = fopen(LINUX_DATAPATH_VERSION_FILE, "r");
      if (f) {
          char *newline;
          char version[MAX_VERSION_STR_SIZE];
  
          if (fgets(version, MAX_VERSION_STR_SIZE, f)) {
              newline = strchr(version, '\n');
              if (newline) {
                  *newline = '\0';
              }
              version_str = xstrdup(version);
          }
          fclose(f);
      }
  #endif
  
      return version_str;
  }
  
  #ifdef __linux__
  struct dpif_netlink_ct_dump_state {
      struct ct_dpif_dump_state up;
      struct nl_ct_dump_state *nl_ct_dump;
  };
  
  static int
  dpif_netlink_ct_dump_start(struct dpif *dpif OVS_UNUSED,
                             struct ct_dpif_dump_state **dump_,
                             const uint16_t *zone)
  {
      struct dpif_netlink_ct_dump_state *dump;
      int err;
  
      dump = xzalloc(sizeof *dump);
      err = nl_ct_dump_start(&dump->nl_ct_dump, zone);
      if (err) {
          free(dump);
          return err;
      }
  
      *dump_ = &dump->up;
  
      return 0;
  }
  
  static int
  dpif_netlink_ct_dump_next(struct dpif *dpif OVS_UNUSED,
                            struct ct_dpif_dump_state *dump_,
                            struct ct_dpif_entry *entry)
  {
      struct dpif_netlink_ct_dump_state *dump;
  
      INIT_CONTAINER(dump, dump_, up);
  
      return nl_ct_dump_next(dump->nl_ct_dump, entry);
  }
  
  static int
  dpif_netlink_ct_dump_done(struct dpif *dpif OVS_UNUSED,
                            struct ct_dpif_dump_state *dump_)
  {
      struct dpif_netlink_ct_dump_state *dump;
      int err;
  
      INIT_CONTAINER(dump, dump_, up);
  
      err = nl_ct_dump_done(dump->nl_ct_dump);
      free(dump);
      return err;
  }
  
  static int
  dpif_netlink_ct_flush(struct dpif *dpif OVS_UNUSED, const uint16_t *zone)
  {
      if (zone) {
          return nl_ct_flush_zone(*zone);
      } else {
          return nl_ct_flush();
      }
  }
  #endif
  
  const struct dpif_class dpif_netlink_class = {
      "system",
      NULL,                       /* init */
      dpif_netlink_enumerate,
      NULL,
      dpif_netlink_open,
      dpif_netlink_close,
      dpif_netlink_destroy,
      dpif_netlink_run,
      NULL,                       /* wait */
      dpif_netlink_get_stats,
      dpif_netlink_port_add,
      dpif_netlink_port_del,
      dpif_netlink_port_query_by_number,
      dpif_netlink_port_query_by_name,
      dpif_netlink_port_get_pid,
      dpif_netlink_port_dump_start,
      dpif_netlink_port_dump_next,
      dpif_netlink_port_dump_done,
      dpif_netlink_port_poll,
      dpif_netlink_port_poll_wait,
      dpif_netlink_flow_flush,
      dpif_netlink_flow_dump_create,
      dpif_netlink_flow_dump_destroy,
      dpif_netlink_flow_dump_thread_create,
      dpif_netlink_flow_dump_thread_destroy,
      dpif_netlink_flow_dump_next,
      dpif_netlink_operate,
      dpif_netlink_recv_set,
      dpif_netlink_handlers_set,
      NULL,                       /* poll_thread_set */
      dpif_netlink_queue_to_priority,
      dpif_netlink_recv,
      dpif_netlink_recv_wait,
      dpif_netlink_recv_purge,
      NULL,                       /* register_dp_purge_cb */
      NULL,                       /* register_upcall_cb */
      NULL,                       /* enable_upcall */
      NULL,                       /* disable_upcall */
      dpif_netlink_get_datapath_version, /* get_datapath_version */
  #ifdef __linux__
      dpif_netlink_ct_dump_start,
      dpif_netlink_ct_dump_next,
      dpif_netlink_ct_dump_done,
      dpif_netlink_ct_flush,
  #else
      NULL,                       /* ct_dump_start */
      NULL,                       /* ct_dump_next */
      NULL,                       /* ct_dump_done */
      NULL,                       /* ct_flush */
  #endif
  };
  
  static int
  dpif_netlink_init(void)
  {
      static struct ovsthread_once once = OVSTHREAD_ONCE_INITIALIZER;
      static int error;
  
      if (ovsthread_once_start(&once)) {
          error = nl_lookup_genl_family(OVS_DATAPATH_FAMILY,
                                        &ovs_datapath_family);
          if (error) {
              VLOG_ERR("Generic Netlink family '%s' does not exist. "
                       "The Open vSwitch kernel module is probably not loaded.",
                       OVS_DATAPATH_FAMILY);
          }
          if (!error) {
              error = nl_lookup_genl_family(OVS_VPORT_FAMILY, &ovs_vport_family);
          }
          if (!error) {
              error = nl_lookup_genl_family(OVS_FLOW_FAMILY, &ovs_flow_family);
          }
          if (!error) {
              error = nl_lookup_genl_family(OVS_PACKET_FAMILY,
                                            &ovs_packet_family);
          }
          if (!error) {
              error = nl_lookup_genl_mcgroup(OVS_VPORT_FAMILY, OVS_VPORT_MCGROUP,
                                             &ovs_vport_mcgroup);
          }
  
          ovsthread_once_done(&once);
      }
  
      return error;
  }
  
  bool
  dpif_netlink_is_internal_device(const char *name)
  {
      struct dpif_netlink_vport reply;
      struct ofpbuf *buf;
      int error;
  
      error = dpif_netlink_vport_get(name, &reply, &buf);
      if (!error) {
          ofpbuf_delete(buf);
      } else if (error != ENODEV && error != ENOENT) {
          VLOG_WARN_RL(&error_rl, "%s: vport query failed (%s)",
                       name, ovs_strerror(error));
      }
  
      return reply.type == OVS_VPORT_TYPE_INTERNAL;
  }
  
  /* Parses the contents of 'buf', which contains a "struct ovs_header" followed
   * by Netlink attributes, into 'vport'.  Returns 0 if successful, otherwise a
   * positive errno value.
   *
   * 'vport' will contain pointers into 'buf', so the caller should not free
   * 'buf' while 'vport' is still in use. */
  static int
  dpif_netlink_vport_from_ofpbuf(struct dpif_netlink_vport *vport,
                               const struct ofpbuf *buf)
  {
      static const struct nl_policy ovs_vport_policy[] = {
          [OVS_VPORT_ATTR_PORT_NO] = { .type = NL_A_U32 },
          [OVS_VPORT_ATTR_TYPE] = { .type = NL_A_U32 },
          [OVS_VPORT_ATTR_NAME] = { .type = NL_A_STRING, .max_len = IFNAMSIZ },
          [OVS_VPORT_ATTR_UPCALL_PID] = { .type = NL_A_UNSPEC },
          [OVS_VPORT_ATTR_STATS] = { NL_POLICY_FOR(struct ovs_vport_stats),
                                     .optional = true },
          [OVS_VPORT_ATTR_OPTIONS] = { .type = NL_A_NESTED, .optional = true },
      };
  
      struct nlattr *a[ARRAY_SIZE(ovs_vport_policy)];
      struct ovs_header *ovs_header;
      struct nlmsghdr *nlmsg;
      struct genlmsghdr *genl;
      struct ofpbuf b;
  
      dpif_netlink_vport_init(vport);
  
      ofpbuf_use_const(&b, buf->data, buf->size);
      nlmsg = ofpbuf_try_pull(&b, sizeof *nlmsg);
      genl = ofpbuf_try_pull(&b, sizeof *genl);
      ovs_header = ofpbuf_try_pull(&b, sizeof *ovs_header);
      if (!nlmsg || !genl || !ovs_header
          || nlmsg->nlmsg_type != ovs_vport_family
          || !nl_policy_parse(&b, 0, ovs_vport_policy, a,
                              ARRAY_SIZE(ovs_vport_policy))) {
          return EINVAL;
      }
  
      vport->cmd = genl->cmd;
      vport->dp_ifindex = ovs_header->dp_ifindex;
      vport->port_no = nl_attr_get_odp_port(a[OVS_VPORT_ATTR_PORT_NO]);
      vport->type = nl_attr_get_u32(a[OVS_VPORT_ATTR_TYPE]);
      vport->name = nl_attr_get_string(a[OVS_VPORT_ATTR_NAME]);
      if (a[OVS_VPORT_ATTR_UPCALL_PID]) {
          vport->n_upcall_pids = nl_attr_get_size(a[OVS_VPORT_ATTR_UPCALL_PID])
                                 / (sizeof *vport->upcall_pids);
          vport->upcall_pids = nl_attr_get(a[OVS_VPORT_ATTR_UPCALL_PID]);
  
      }
      if (a[OVS_VPORT_ATTR_STATS]) {
          vport->stats = nl_attr_get(a[OVS_VPORT_ATTR_STATS]);
      }
      if (a[OVS_VPORT_ATTR_OPTIONS]) {
          vport->options = nl_attr_get(a[OVS_VPORT_ATTR_OPTIONS]);
          vport->options_len = nl_attr_get_size(a[OVS_VPORT_ATTR_OPTIONS]);
      }
      return 0;
  }
  
  /* Appends to 'buf' (which must initially be empty) a "struct ovs_header"
   * followed by Netlink attributes corresponding to 'vport'. */
  static void
  dpif_netlink_vport_to_ofpbuf(const struct dpif_netlink_vport *vport,
                               struct ofpbuf *buf)
  {
      struct ovs_header *ovs_header;
  
      nl_msg_put_genlmsghdr(buf, 0, ovs_vport_family, NLM_F_REQUEST | NLM_F_ECHO,
                            vport->cmd, OVS_VPORT_VERSION);
  
      ovs_header = ofpbuf_put_uninit(buf, sizeof *ovs_header);
      ovs_header->dp_ifindex = vport->dp_ifindex;
  
      if (vport->port_no != ODPP_NONE) {
          nl_msg_put_odp_port(buf, OVS_VPORT_ATTR_PORT_NO, vport->port_no);
      }
  
      if (vport->type != OVS_VPORT_TYPE_UNSPEC) {
          nl_msg_put_u32(buf, OVS_VPORT_ATTR_TYPE, vport->type);
      }
  
      if (vport->name) {
          nl_msg_put_string(buf, OVS_VPORT_ATTR_NAME, vport->name);
      }
  
      if (vport->upcall_pids) {
          nl_msg_put_unspec(buf, OVS_VPORT_ATTR_UPCALL_PID,
                            vport->upcall_pids,
                            vport->n_upcall_pids * sizeof *vport->upcall_pids);
      }
  
      if (vport->stats) {
          nl_msg_put_unspec(buf, OVS_VPORT_ATTR_STATS,
                            vport->stats, sizeof *vport->stats);
      }
  
      if (vport->options) {
          nl_msg_put_nested(buf, OVS_VPORT_ATTR_OPTIONS,
                            vport->options, vport->options_len);
      }
  }
  
  /* Clears 'vport' to "empty" values. */
  void
  dpif_netlink_vport_init(struct dpif_netlink_vport *vport)
  {
      memset(vport, 0, sizeof *vport);
      vport->port_no = ODPP_NONE;
  }
  
  /* Executes 'request' in the kernel datapath.  If the command fails, returns a
   * positive errno value.  Otherwise, if 'reply' and 'bufp' are null, returns 0
   * without doing anything else.  If 'reply' and 'bufp' are nonnull, then the
   * result of the command is expected to be an ovs_vport also, which is decoded
   * and stored in '*reply' and '*bufp'.  The caller must free '*bufp' when the
   * reply is no longer needed ('reply' will contain pointers into '*bufp'). */
  int
  dpif_netlink_vport_transact(const struct dpif_netlink_vport *request,
                              struct dpif_netlink_vport *reply,
                              struct ofpbuf **bufp)
  {
      struct ofpbuf *request_buf;
      int error;
  
      ovs_assert((reply != NULL) == (bufp != NULL));
  
      error = dpif_netlink_init();
      if (error) {
          if (reply) {
              *bufp = NULL;
              dpif_netlink_vport_init(reply);
          }
          return error;
      }
  
      request_buf = ofpbuf_new(1024);
      dpif_netlink_vport_to_ofpbuf(request, request_buf);
      error = nl_transact(NETLINK_GENERIC, request_buf, bufp);
      ofpbuf_delete(request_buf);
  
      if (reply) {
          if (!error) {
              error = dpif_netlink_vport_from_ofpbuf(reply, *bufp);
          }
          if (error) {
              dpif_netlink_vport_init(reply);
              ofpbuf_delete(*bufp);
              *bufp = NULL;
          }
      }
      return error;
  }
  
  /* Obtains information about the kernel vport named 'name' and stores it into
   * '*reply' and '*bufp'.  The caller must free '*bufp' when the reply is no
   * longer needed ('reply' will contain pointers into '*bufp').  */
  int
  dpif_netlink_vport_get(const char *name, struct dpif_netlink_vport *reply,
                         struct ofpbuf **bufp)
  {
      struct dpif_netlink_vport request;
  
      dpif_netlink_vport_init(&request);
      request.cmd = OVS_VPORT_CMD_GET;
      request.name = name;
  
      return dpif_netlink_vport_transact(&request, reply, bufp);
  }
  
  /* Parses the contents of 'buf', which contains a "struct ovs_header" followed
   * by Netlink attributes, into 'dp'.  Returns 0 if successful, otherwise a
   * positive errno value.
   *
   * 'dp' will contain pointers into 'buf', so the caller should not free 'buf'
   * while 'dp' is still in use. */
  static int
  dpif_netlink_dp_from_ofpbuf(struct dpif_netlink_dp *dp, const struct ofpbuf *buf)
  {
      static const struct nl_policy ovs_datapath_policy[] = {
          [OVS_DP_ATTR_NAME] = { .type = NL_A_STRING, .max_len = IFNAMSIZ },
          [OVS_DP_ATTR_STATS] = { NL_POLICY_FOR(struct ovs_dp_stats),
                                  .optional = true },
          [OVS_DP_ATTR_MEGAFLOW_STATS] = {
                          NL_POLICY_FOR(struct ovs_dp_megaflow_stats),
                          .optional = true },
      };
  
      struct nlattr *a[ARRAY_SIZE(ovs_datapath_policy)];
      struct ovs_header *ovs_header;
      struct nlmsghdr *nlmsg;
      struct genlmsghdr *genl;
      struct ofpbuf b;
  
      dpif_netlink_dp_init(dp);
  
      ofpbuf_use_const(&b, buf->data, buf->size);
      nlmsg = ofpbuf_try_pull(&b, sizeof *nlmsg);
      genl = ofpbuf_try_pull(&b, sizeof *genl);
      ovs_header = ofpbuf_try_pull(&b, sizeof *ovs_header);
      if (!nlmsg || !genl || !ovs_header
          || nlmsg->nlmsg_type != ovs_datapath_family
          || !nl_policy_parse(&b, 0, ovs_datapath_policy, a,
                              ARRAY_SIZE(ovs_datapath_policy))) {
          return EINVAL;
      }
  
      dp->cmd = genl->cmd;
      dp->dp_ifindex = ovs_header->dp_ifindex;
      dp->name = nl_attr_get_string(a[OVS_DP_ATTR_NAME]);
      if (a[OVS_DP_ATTR_STATS]) {
          dp->stats = nl_attr_get(a[OVS_DP_ATTR_STATS]);
      }
  
      if (a[OVS_DP_ATTR_MEGAFLOW_STATS]) {
          dp->megaflow_stats = nl_attr_get(a[OVS_DP_ATTR_MEGAFLOW_STATS]);
      }
  
      return 0;
  }
  
  /* Appends to 'buf' the Generic Netlink message described by 'dp'. */
  static void
  dpif_netlink_dp_to_ofpbuf(const struct dpif_netlink_dp *dp, struct ofpbuf *buf)
  {
      struct ovs_header *ovs_header;
  
      nl_msg_put_genlmsghdr(buf, 0, ovs_datapath_family,
                            NLM_F_REQUEST | NLM_F_ECHO, dp->cmd,
                            OVS_DATAPATH_VERSION);
  
      ovs_header = ofpbuf_put_uninit(buf, sizeof *ovs_header);
      ovs_header->dp_ifindex = dp->dp_ifindex;
  
      if (dp->name) {
          nl_msg_put_string(buf, OVS_DP_ATTR_NAME, dp->name);
      }
  
      if (dp->upcall_pid) {
          nl_msg_put_u32(buf, OVS_DP_ATTR_UPCALL_PID, *dp->upcall_pid);
      }
  
      if (dp->user_features) {
          nl_msg_put_u32(buf, OVS_DP_ATTR_USER_FEATURES, dp->user_features);
      }
  
      /* Skip OVS_DP_ATTR_STATS since we never have a reason to serialize it. */
  }
  
  /* Clears 'dp' to "empty" values. */
  static void
  dpif_netlink_dp_init(struct dpif_netlink_dp *dp)
  {
      memset(dp, 0, sizeof *dp);
  }
  
  static void
  dpif_netlink_dp_dump_start(struct nl_dump *dump)
  {
      struct dpif_netlink_dp request;
      struct ofpbuf *buf;
  
      dpif_netlink_dp_init(&request);
      request.cmd = OVS_DP_CMD_GET;
  
      buf = ofpbuf_new(1024);
      dpif_netlink_dp_to_ofpbuf(&request, buf);
      nl_dump_start(dump, NETLINK_GENERIC, buf);
      ofpbuf_delete(buf);
  }
  
  /* Executes 'request' in the kernel datapath.  If the command fails, returns a
   * positive errno value.  Otherwise, if 'reply' and 'bufp' are null, returns 0
   * without doing anything else.  If 'reply' and 'bufp' are nonnull, then the
   * result of the command is expected to be of the same form, which is decoded
   * and stored in '*reply' and '*bufp'.  The caller must free '*bufp' when the
   * reply is no longer needed ('reply' will contain pointers into '*bufp'). */
  static int
  dpif_netlink_dp_transact(const struct dpif_netlink_dp *request,
                           struct dpif_netlink_dp *reply, struct ofpbuf **bufp)
  {
      struct ofpbuf *request_buf;
      int error;
  
      ovs_assert((reply != NULL) == (bufp != NULL));
  
      request_buf = ofpbuf_new(1024);
      dpif_netlink_dp_to_ofpbuf(request, request_buf);
      error = nl_transact(NETLINK_GENERIC, request_buf, bufp);
      ofpbuf_delete(request_buf);
  
      if (reply) {
          dpif_netlink_dp_init(reply);
          if (!error) {
              error = dpif_netlink_dp_from_ofpbuf(reply, *bufp);
          }
          if (error) {
              ofpbuf_delete(*bufp);
              *bufp = NULL;
          }
      }
      return error;
  }
  
  /* Obtains information about 'dpif_' and stores it into '*reply' and '*bufp'.
   * The caller must free '*bufp' when the reply is no longer needed ('reply'
   * will contain pointers into '*bufp').  */
  static int
  dpif_netlink_dp_get(const struct dpif *dpif_, struct dpif_netlink_dp *reply,
                      struct ofpbuf **bufp)
  {
      struct dpif_netlink *dpif = dpif_netlink_cast(dpif_);
      struct dpif_netlink_dp request;
  
      dpif_netlink_dp_init(&request);
      request.cmd = OVS_DP_CMD_GET;
      request.dp_ifindex = dpif->dp_ifindex;
  
      return dpif_netlink_dp_transact(&request, reply, bufp);
  }
  
  /* Parses the contents of 'buf', which contains a "struct ovs_header" followed
   * by Netlink attributes, into 'flow'.  Returns 0 if successful, otherwise a
   * positive errno value.
   *
   * 'flow' will contain pointers into 'buf', so the caller should not free 'buf'
   * while 'flow' is still in use. */
  static int
  dpif_netlink_flow_from_ofpbuf(struct dpif_netlink_flow *flow,
                                const struct ofpbuf *buf)
  {
      static const struct nl_policy ovs_flow_policy[__OVS_FLOW_ATTR_MAX] = {
          [OVS_FLOW_ATTR_KEY] = { .type = NL_A_NESTED, .optional = true },
          [OVS_FLOW_ATTR_MASK] = { .type = NL_A_NESTED, .optional = true },
          [OVS_FLOW_ATTR_ACTIONS] = { .type = NL_A_NESTED, .optional = true },
          [OVS_FLOW_ATTR_STATS] = { NL_POLICY_FOR(struct ovs_flow_stats),
                                    .optional = true },
          [OVS_FLOW_ATTR_TCP_FLAGS] = { .type = NL_A_U8, .optional = true },
          [OVS_FLOW_ATTR_USED] = { .type = NL_A_U64, .optional = true },
          [OVS_FLOW_ATTR_UFID] = { .type = NL_A_UNSPEC, .optional = true,
                                   .min_len = sizeof(ovs_u128) },
          /* The kernel never uses OVS_FLOW_ATTR_CLEAR. */
          /* The kernel never uses OVS_FLOW_ATTR_PROBE. */
          /* The kernel never uses OVS_FLOW_ATTR_UFID_FLAGS. */
      };
  
      struct nlattr *a[ARRAY_SIZE(ovs_flow_policy)];
      struct ovs_header *ovs_header;
      struct nlmsghdr *nlmsg;
      struct genlmsghdr *genl;
      struct ofpbuf b;
  
      dpif_netlink_flow_init(flow);
  
      ofpbuf_use_const(&b, buf->data, buf->size);
      nlmsg = ofpbuf_try_pull(&b, sizeof *nlmsg);
      genl = ofpbuf_try_pull(&b, sizeof *genl);
      ovs_header = ofpbuf_try_pull(&b, sizeof *ovs_header);
      if (!nlmsg || !genl || !ovs_header
          || nlmsg->nlmsg_type != ovs_flow_family
          || !nl_policy_parse(&b, 0, ovs_flow_policy, a,
                              ARRAY_SIZE(ovs_flow_policy))) {
          return EINVAL;
      }
      if (!a[OVS_FLOW_ATTR_KEY] && !a[OVS_FLOW_ATTR_UFID]) {
          return EINVAL;
      }
  
      flow->nlmsg_flags = nlmsg->nlmsg_flags;
      flow->dp_ifindex = ovs_header->dp_ifindex;
      if (a[OVS_FLOW_ATTR_KEY]) {
          flow->key = nl_attr_get(a[OVS_FLOW_ATTR_KEY]);
          flow->key_len = nl_attr_get_size(a[OVS_FLOW_ATTR_KEY]);
      }
  
      if (a[OVS_FLOW_ATTR_UFID]) {
          const ovs_u128 *ufid;
  
          ufid = nl_attr_get_unspec(a[OVS_FLOW_ATTR_UFID],
                                    nl_attr_get_size(a[OVS_FLOW_ATTR_UFID]));
          flow->ufid = *ufid;
          flow->ufid_present = true;
      }
      if (a[OVS_FLOW_ATTR_MASK]) {
          flow->mask = nl_attr_get(a[OVS_FLOW_ATTR_MASK]);
          flow->mask_len = nl_attr_get_size(a[OVS_FLOW_ATTR_MASK]);
      }
      if (a[OVS_FLOW_ATTR_ACTIONS]) {
          flow->actions = nl_attr_get(a[OVS_FLOW_ATTR_ACTIONS]);
          flow->actions_len = nl_attr_get_size(a[OVS_FLOW_ATTR_ACTIONS]);
      }
      if (a[OVS_FLOW_ATTR_STATS]) {
          flow->stats = nl_attr_get(a[OVS_FLOW_ATTR_STATS]);
      }
      if (a[OVS_FLOW_ATTR_TCP_FLAGS]) {
          flow->tcp_flags = nl_attr_get(a[OVS_FLOW_ATTR_TCP_FLAGS]);
      }
      if (a[OVS_FLOW_ATTR_USED]) {
          flow->used = nl_attr_get(a[OVS_FLOW_ATTR_USED]);
      }
      return 0;
  }
  
  /* Appends to 'buf' (which must initially be empty) a "struct ovs_header"
   * followed by Netlink attributes corresponding to 'flow'. */
  static void
  dpif_netlink_flow_to_ofpbuf(const struct dpif_netlink_flow *flow,
                              struct ofpbuf *buf)
  {
      struct ovs_header *ovs_header;
  
      nl_msg_put_genlmsghdr(buf, 0, ovs_flow_family,
                            NLM_F_REQUEST | flow->nlmsg_flags,
                            flow->cmd, OVS_FLOW_VERSION);
  
      ovs_header = ofpbuf_put_uninit(buf, sizeof *ovs_header);
      ovs_header->dp_ifindex = flow->dp_ifindex;
  
      if (flow->ufid_present) {
          nl_msg_put_unspec(buf, OVS_FLOW_ATTR_UFID, &flow->ufid,
                            sizeof flow->ufid);
      }
      if (flow->ufid_terse) {
          nl_msg_put_u32(buf, OVS_FLOW_ATTR_UFID_FLAGS,
                         OVS_UFID_F_OMIT_KEY | OVS_UFID_F_OMIT_MASK
                         | OVS_UFID_F_OMIT_ACTIONS);
      }
      if (!flow->ufid_terse || !flow->ufid_present) {
          if (flow->key_len) {
              nl_msg_put_unspec(buf, OVS_FLOW_ATTR_KEY,
                                flow->key, flow->key_len);
          }
  
          if (flow->mask_len) {
              nl_msg_put_unspec(buf, OVS_FLOW_ATTR_MASK,
                                flow->mask, flow->mask_len);
          }
          if (flow->actions || flow->actions_len) {
              nl_msg_put_unspec(buf, OVS_FLOW_ATTR_ACTIONS,
                                flow->actions, flow->actions_len);
          }
      }
  
      /* We never need to send these to the kernel. */
      ovs_assert(!flow->stats);
      ovs_assert(!flow->tcp_flags);
      ovs_assert(!flow->used);
  
      if (flow->clear) {
          nl_msg_put_flag(buf, OVS_FLOW_ATTR_CLEAR);
      }
      if (flow->probe) {
          nl_msg_put_flag(buf, OVS_FLOW_ATTR_PROBE);
      }
  }
  
  /* Clears 'flow' to "empty" values. */
  static void
  dpif_netlink_flow_init(struct dpif_netlink_flow *flow)
  {
      memset(flow, 0, sizeof *flow);
  }
  
  /* Executes 'request' in the kernel datapath.  If the command fails, returns a
   * positive errno value.  Otherwise, if 'reply' and 'bufp' are null, returns 0
   * without doing anything else.  If 'reply' and 'bufp' are nonnull, then the
   * result of the command is expected to be a flow also, which is decoded and
   * stored in '*reply' and '*bufp'.  The caller must free '*bufp' when the reply
   * is no longer needed ('reply' will contain pointers into '*bufp'). */
  static int
  dpif_netlink_flow_transact(struct dpif_netlink_flow *request,
                             struct dpif_netlink_flow *reply,
                             struct ofpbuf **bufp)
  {
      struct ofpbuf *request_buf;
      int error;
  
      ovs_assert((reply != NULL) == (bufp != NULL));
  
      if (reply) {
          request->nlmsg_flags |= NLM_F_ECHO;
      }
  
      request_buf = ofpbuf_new(1024);
      dpif_netlink_flow_to_ofpbuf(request, request_buf);
      error = nl_transact(NETLINK_GENERIC, request_buf, bufp);
      ofpbuf_delete(request_buf);
  
      if (reply) {
          if (!error) {
              error = dpif_netlink_flow_from_ofpbuf(reply, *bufp);
          }
          if (error) {
              dpif_netlink_flow_init(reply);
              ofpbuf_delete(*bufp);
              *bufp = NULL;
          }
      }
      return error;
  }
  
  static void
  dpif_netlink_flow_get_stats(const struct dpif_netlink_flow *flow,
                              struct dpif_flow_stats *stats)
  {
      if (flow->stats) {
          stats->n_packets = get_32aligned_u64(&flow->stats->n_packets);
          stats->n_bytes = get_32aligned_u64(&flow->stats->n_bytes);
      } else {
          stats->n_packets = 0;
          stats->n_bytes = 0;
      }
      stats->used = flow->used ? get_32aligned_u64(flow->used) : 0;
      stats->tcp_flags = flow->tcp_flags ? *flow->tcp_flags : 0;
  }
  
  /* Logs information about a packet that was recently lost in 'ch' (in
   * 'dpif_'). */
  static void
  report_loss(struct dpif_netlink *dpif, struct dpif_channel *ch, uint32_t ch_idx,
              uint32_t handler_id)
  {
      static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(5, 5);
      struct ds s;
  
      if (VLOG_DROP_WARN(&rl)) {
          return;
      }
  
      ds_init(&s);
      if (ch->last_poll != LLONG_MIN) {
          ds_put_format(&s, " (last polled %lld ms ago)",
                        time_msec() - ch->last_poll);
      }
  
      VLOG_WARN("%s: lost packet on port channel %u of handler %u",
                dpif_name(&dpif->dpif), ch_idx, handler_id);
      ds_destroy(&s);
  }
  