text: /*
   * Copyright (c) 2009, 2010, 2011 Nicira Networks.
   *
   * 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.h"
  
  #include <assert.h>
  #include <ctype.h>
  #include <errno.h>
  #include <fcntl.h>
  #include <inttypes.h>
  #include <netinet/in.h>
  #include <sys/socket.h>
  #include <net/if.h>
  #include <stdint.h>
  #include <stdlib.h>
  #include <string.h>
  #include <sys/ioctl.h>
  #include <sys/stat.h>
  #include <unistd.h>
  
  #include "csum.h"
  #include "dpif.h"
  #include "dpif-provider.h"
  #include "dummy.h"
  #include "dynamic-string.h"
  #include "flow.h"
  #include "hmap.h"
  #include "list.h"
  #include "netdev.h"
  #include "netlink.h"
  #include "odp-util.h"
  #include "ofp-print.h"
  #include "ofpbuf.h"
  #include "packets.h"
  #include "poll-loop.h"
  #include "shash.h"
  #include "timeval.h"
  #include "util.h"
  #include "vlog.h"
  
  VLOG_DEFINE_THIS_MODULE(dpif_netdev);
  
  /* Configuration parameters. */
  enum { MAX_PORTS = 256 };       /* Maximum number of ports. */
  enum { MAX_FLOWS = 65536 };     /* Maximum number of flows in flow table. */
  
  /* Enough headroom to add a vlan tag, plus an extra 2 bytes to allow IP
   * headers to be aligned on a 4-byte boundary.  */
  enum { DP_NETDEV_HEADROOM = 2 + VLAN_HEADER_LEN };
  
  /* Queues. */
  enum { N_QUEUES = 2 };          /* Number of queues for dpif_recv(). */
  enum { MAX_QUEUE_LEN = 128 };   /* Maximum number of packets per queue. */
  enum { QUEUE_MASK = MAX_QUEUE_LEN - 1 };
  BUILD_ASSERT_DECL(IS_POW2(MAX_QUEUE_LEN));
  
  struct dp_netdev_queue {
      struct dpif_upcall *upcalls[MAX_QUEUE_LEN];
      unsigned int head, tail;
  };
  
  /* Datapath based on the network device interface from netdev.h. */
  struct dp_netdev {
      const struct dpif_class *class;
      char *name;
      int open_cnt;
      bool destroyed;
  
      bool drop_frags;            /* Drop all IP fragments, if true. */
      struct dp_netdev_queue queues[N_QUEUES];
      struct hmap flow_table;     /* Flow table. */
  
      /* Statistics. */
      long long int n_frags;      /* Number of dropped IP fragments. */
      long long int n_hit;        /* Number of flow table matches. */
      long long int n_missed;     /* Number of flow table misses. */
      long long int n_lost;       /* Number of misses not passed to client. */
  
      /* Ports. */
      struct dp_netdev_port *ports[MAX_PORTS];
      struct list port_list;
      unsigned int serial;
  };
  
  /* A port in a netdev-based datapath. */
  struct dp_netdev_port {
      int port_no;                /* Index into dp_netdev's 'ports'. */
      struct list node;           /* Element in dp_netdev's 'port_list'. */
      struct netdev *netdev;
      bool internal;              /* Internal port? */
  };
  
  /* A flow in dp_netdev's 'flow_table'. */
  struct dp_netdev_flow {
      struct hmap_node node;      /* Element in dp_netdev's 'flow_table'. */
      struct flow key;
  
      /* Statistics. */
      long long int used;         /* Last used time, in monotonic msecs. */
      long long int packet_count; /* Number of packets matched. */
      long long int byte_count;   /* Number of bytes matched. */
      ovs_be16 tcp_ctl;           /* Bitwise-OR of seen tcp_ctl values. */
  
      /* Actions. */
      struct nlattr *actions;
      size_t actions_len;
  };
  
  /* Interface to netdev-based datapath. */
  struct dpif_netdev {
      struct dpif dpif;
      struct dp_netdev *dp;
      int listen_mask;
      unsigned int dp_serial;
  };
  
  /* All netdev-based datapaths. */
  static struct shash dp_netdevs = SHASH_INITIALIZER(&dp_netdevs);
  
  /* Maximum port MTU seen so far. */
  static int max_mtu = ETH_PAYLOAD_MAX;
  
  static int get_port_by_number(struct dp_netdev *, uint16_t port_no,
                                struct dp_netdev_port **portp);
  static int get_port_by_name(struct dp_netdev *, const char *devname,
                              struct dp_netdev_port **portp);
  static void dp_netdev_free(struct dp_netdev *);
  static void dp_netdev_flow_flush(struct dp_netdev *);
  static int do_add_port(struct dp_netdev *, const char *devname,
                         const char *type, uint16_t port_no);
  static int do_del_port(struct dp_netdev *, uint16_t port_no);
  static int dpif_netdev_open(const struct dpif_class *, const char *name,
                              bool create, struct dpif **);
  static int dp_netdev_output_userspace(struct dp_netdev *, const struct ofpbuf *,
                                      int queue_no, const struct flow *,
                                      uint64_t arg);
  static int dp_netdev_execute_actions(struct dp_netdev *,
                                       struct ofpbuf *, struct flow *,
                                       const struct nlattr *actions,
                                       size_t actions_len);
  
  static struct dpif_class dpif_dummy_class;
  
  static struct dpif_netdev *
  dpif_netdev_cast(const struct dpif *dpif)
  {
      assert(dpif->dpif_class->open == dpif_netdev_open);
      return CONTAINER_OF(dpif, struct dpif_netdev, dpif);
  }
  
  static struct dp_netdev *
  get_dp_netdev(const struct dpif *dpif)
  {
      return dpif_netdev_cast(dpif)->dp;
  }
  
  static struct dpif *
  create_dpif_netdev(struct dp_netdev *dp)
  {
      uint16_t netflow_id = hash_string(dp->name, 0);
      struct dpif_netdev *dpif;
  
      dp->open_cnt++;
  
      dpif = xmalloc(sizeof *dpif);
      dpif_init(&dpif->dpif, dp->class, dp->name, netflow_id >> 8, netflow_id);
      dpif->dp = dp;
      dpif->listen_mask = 0;
      dpif->dp_serial = dp->serial;
  
      return &dpif->dpif;
  }
  
  static int
  create_dp_netdev(const char *name, const struct dpif_class *class,
                   struct dp_netdev **dpp)
  {
      struct dp_netdev *dp;
      int error;
      int i;
  
      dp = xzalloc(sizeof *dp);
      dp->class = class;
      dp->name = xstrdup(name);
      dp->open_cnt = 0;
      dp->drop_frags = false;
      for (i = 0; i < N_QUEUES; i++) {
          dp->queues[i].head = dp->queues[i].tail = 0;
      }
      hmap_init(&dp->flow_table);
      list_init(&dp->port_list);
      error = do_add_port(dp, name, "internal", OVSP_LOCAL);
      if (error) {
          dp_netdev_free(dp);
          return error;
      }
  
      shash_add(&dp_netdevs, name, dp);
  
      *dpp = dp;
      return 0;
  }
  
  static int
  dpif_netdev_open(const struct dpif_class *class, const char *name,
                   bool create, struct dpif **dpifp)
  {
      struct dp_netdev *dp;
  
      dp = shash_find_data(&dp_netdevs, name);
      if (!dp) {
          if (!create) {
              return ENODEV;
          } else {
              int error = create_dp_netdev(name, class, &dp);
              if (error) {
                  return error;
              }
              assert(dp != NULL);
          }
      } else {
          if (dp->class != class) {
              return EINVAL;
          } else if (create) {
              return EEXIST;
          }
      }
  
      *dpifp = create_dpif_netdev(dp);
      return 0;
  }
  
  static void
  dp_netdev_purge_queues(struct dp_netdev *dp)
  {
      int i;
  
      for (i = 0; i < N_QUEUES; i++) {
          struct dp_netdev_queue *q = &dp->queues[i];
  
          while (q->tail != q->head) {
              struct dpif_upcall *upcall = q->upcalls[q->tail++ & QUEUE_MASK];
  
              ofpbuf_delete(upcall->packet);
              free(upcall);
          }
      }
  }
  
  static void
  dp_netdev_free(struct dp_netdev *dp)
  {
      struct dp_netdev_port *port, *next;
  
      dp_netdev_flow_flush(dp);
      LIST_FOR_EACH_SAFE (port, next, node, &dp->port_list) {
          do_del_port(dp, port->port_no);
      }
      dp_netdev_purge_queues(dp);
      hmap_destroy(&dp->flow_table);
      free(dp->name);
      free(dp);
  }
  
  static void
  dpif_netdev_close(struct dpif *dpif)
  {
      struct dp_netdev *dp = get_dp_netdev(dpif);
      assert(dp->open_cnt > 0);
      if (--dp->open_cnt == 0 && dp->destroyed) {
          shash_find_and_delete(&dp_netdevs, dp->name);
          dp_netdev_free(dp);
      }
      free(dpif);
  }
  
  static int
  dpif_netdev_destroy(struct dpif *dpif)
  {
      struct dp_netdev *dp = get_dp_netdev(dpif);
      dp->destroyed = true;
      return 0;
  }
  
  static int
  dpif_netdev_get_stats(const struct dpif *dpif, struct ovs_dp_stats *stats)
  {
      struct dp_netdev *dp = get_dp_netdev(dpif);
      memset(stats, 0, sizeof *stats);
      stats->n_flows = hmap_count(&dp->flow_table);
      stats->n_frags = dp->n_frags;
      stats->n_hit = dp->n_hit;
      stats->n_missed = dp->n_missed;
      stats->n_lost = dp->n_lost;
      return 0;
  }
  
  static int
  dpif_netdev_get_drop_frags(const struct dpif *dpif, bool *drop_fragsp)
  {
      struct dp_netdev *dp = get_dp_netdev(dpif);
      *drop_fragsp = dp->drop_frags;
      return 0;
  }
  
  static int
  dpif_netdev_set_drop_frags(struct dpif *dpif, bool drop_frags)
  {
      struct dp_netdev *dp = get_dp_netdev(dpif);
      dp->drop_frags = drop_frags;
      return 0;
  }
  
  static int
  do_add_port(struct dp_netdev *dp, const char *devname, const char *type,
              uint16_t port_no)
  {
      struct dp_netdev_port *port;
      struct netdev *netdev;
      bool internal;
      int mtu;
      int error;
  
      /* XXX reject devices already in some dp_netdev. */
      if (type[0] == '\0' || !strcmp(type, "system") || !strcmp(type, "dummy")) {
          internal = false;
      } else if (!strcmp(type, "internal")) {
          internal = true;
      } else {
          VLOG_WARN("%s: unsupported port type %s", devname, type);
          return EINVAL;
      }
  
      /* Open and validate network device. */
      if (dp->class == &dpif_dummy_class) {
          type = "dummy";
      } else if (internal) {
          type = "tap";
      }
  
      error = netdev_open(devname, type, &netdev);
      if (error) {
          return error;
      }
      /* XXX reject loopback devices */
      /* XXX reject non-Ethernet devices */
  
      error = netdev_listen(netdev);
      if (error) {
          VLOG_ERR("%s: cannot receive packets on this network device (%s)",
                   devname, strerror(errno));
          netdev_close(netdev);
          return error;
      }
  
      error = netdev_turn_flags_on(netdev, NETDEV_PROMISC, false);
      if (error) {
          netdev_close(netdev);
          return error;
      }
  
      port = xmalloc(sizeof *port);
      port->port_no = port_no;
      port->netdev = netdev;
      port->internal = internal;
  
      error = netdev_get_mtu(netdev, &mtu);
      if (!error) {
          max_mtu = mtu;
      }
  
      list_push_back(&dp->port_list, &port->node);
      dp->ports[port_no] = port;
      dp->serial++;
  
      return 0;
  }
  
  static int
  dpif_netdev_port_add(struct dpif *dpif, struct netdev *netdev,
                       uint16_t *port_nop)
  {
      struct dp_netdev *dp = get_dp_netdev(dpif);
      int port_no;
  
      for (port_no = 0; port_no < MAX_PORTS; port_no++) {
          if (!dp->ports[port_no]) {
              *port_nop = port_no;
              return do_add_port(dp, netdev_get_name(netdev),
                                 netdev_get_type(netdev), port_no);
          }
      }
      return EFBIG;
  }
  
  static int
  dpif_netdev_port_del(struct dpif *dpif, uint16_t port_no)
  {
      struct dp_netdev *dp = get_dp_netdev(dpif);
      return port_no == OVSP_LOCAL ? EINVAL : do_del_port(dp, port_no);
  }
  
  static bool
  is_valid_port_number(uint16_t port_no)
  {
      return port_no < MAX_PORTS;
  }
  
  static int
  get_port_by_number(struct dp_netdev *dp,
                     uint16_t port_no, struct dp_netdev_port **portp)
  {
      if (!is_valid_port_number(port_no)) {
          *portp = NULL;
          return EINVAL;
      } else {
          *portp = dp->ports[port_no];
          return *portp ? 0 : ENOENT;
      }
  }
  
  static int
  get_port_by_name(struct dp_netdev *dp,
                   const char *devname, struct dp_netdev_port **portp)
  {
      struct dp_netdev_port *port;
  
      LIST_FOR_EACH (port, node, &dp->port_list) {
          if (!strcmp(netdev_get_name(port->netdev), devname)) {
              *portp = port;
              return 0;
          }
      }
      return ENOENT;
  }
  
  static int
  do_del_port(struct dp_netdev *dp, uint16_t port_no)
  {
      struct dp_netdev_port *port;
      char *name;
      int error;
  
      error = get_port_by_number(dp, port_no, &port);
      if (error) {
          return error;
      }
  
      list_remove(&port->node);
      dp->ports[port->port_no] = NULL;
      dp->serial++;
  
      name = xstrdup(netdev_get_name(port->netdev));
      netdev_close(port->netdev);
  
      free(name);
      free(port);
  
      return 0;
  }
  
  static void
  answer_port_query(const struct dp_netdev_port *port,
                    struct dpif_port *dpif_port)
  {
      dpif_port->name = xstrdup(netdev_get_name(port->netdev));
      dpif_port->type = xstrdup(port->internal ? "internal" : "system");
      dpif_port->port_no = port->port_no;
  }
  
  static int
  dpif_netdev_port_query_by_number(const struct dpif *dpif, uint16_t port_no,
                                   struct dpif_port *dpif_port)
  {
      struct dp_netdev *dp = get_dp_netdev(dpif);
      struct dp_netdev_port *port;
      int error;
  
      error = get_port_by_number(dp, port_no, &port);
      if (!error) {
          answer_port_query(port, dpif_port);
      }
      return error;
  }
  
  static int
  dpif_netdev_port_query_by_name(const struct dpif *dpif, const char *devname,
                                 struct dpif_port *dpif_port)
  {
      struct dp_netdev *dp = get_dp_netdev(dpif);
      struct dp_netdev_port *port;
      int error;
  
      error = get_port_by_name(dp, devname, &port);
      if (!error) {
          answer_port_query(port, dpif_port);
      }
      return error;
  }
  
  static int
  dpif_netdev_get_max_ports(const struct dpif *dpif OVS_UNUSED)
  {
      return MAX_PORTS;
  }
  
  static void
  dp_netdev_free_flow(struct dp_netdev *dp, struct dp_netdev_flow *flow)
  {
      hmap_remove(&dp->flow_table, &flow->node);
      free(flow->actions);
      free(flow);
  }
  
  static void
  dp_netdev_flow_flush(struct dp_netdev *dp)
  {
      struct dp_netdev_flow *flow, *next;
  
      HMAP_FOR_EACH_SAFE (flow, next, node, &dp->flow_table) {
          dp_netdev_free_flow(dp, flow);
      }
  }
  
  static int
  dpif_netdev_flow_flush(struct dpif *dpif)
  {
      struct dp_netdev *dp = get_dp_netdev(dpif);
      dp_netdev_flow_flush(dp);
      return 0;
  }
  
  struct dp_netdev_port_state {
      uint32_t port_no;
      char *name;
  };
  
  static int
  dpif_netdev_port_dump_start(const struct dpif *dpif OVS_UNUSED, void **statep)
  {
      *statep = xzalloc(sizeof(struct dp_netdev_port_state));
      return 0;
  }
  
  static int
  dpif_netdev_port_dump_next(const struct dpif *dpif, void *state_,
                             struct dpif_port *dpif_port)
  {
      struct dp_netdev_port_state *state = state_;
      struct dp_netdev *dp = get_dp_netdev(dpif);
      uint32_t port_no;
  
      for (port_no = state->port_no; port_no < MAX_PORTS; port_no++) {
          struct dp_netdev_port *port = dp->ports[port_no];
          if (port) {
              free(state->name);
              state->name = xstrdup(netdev_get_name(port->netdev));
              dpif_port->name = state->name;
              dpif_port->type = port->internal ? "internal" : "system";
              dpif_port->port_no = port->port_no;
              state->port_no = port_no + 1;
              return 0;
          }
      }
      return EOF;
  }
  
  static int
  dpif_netdev_port_dump_done(const struct dpif *dpif OVS_UNUSED, void *state_)
  {
      struct dp_netdev_port_state *state = state_;
      free(state->name);
      free(state);
      return 0;
  }
  
  static int
  dpif_netdev_port_poll(const struct dpif *dpif_, char **devnamep OVS_UNUSED)
  {
      struct dpif_netdev *dpif = dpif_netdev_cast(dpif_);
      if (dpif->dp_serial != dpif->dp->serial) {
          dpif->dp_serial = dpif->dp->serial;
          return ENOBUFS;
      } else {
          return EAGAIN;
      }
  }
  
  static void
  dpif_netdev_port_poll_wait(const struct dpif *dpif_)
  {
      struct dpif_netdev *dpif = dpif_netdev_cast(dpif_);
      if (dpif->dp_serial != dpif->dp->serial) {
          poll_immediate_wake();
      }
  }
  
  static struct dp_netdev_flow *
  dp_netdev_lookup_flow(const struct dp_netdev *dp, const struct flow *key)
  {
      struct dp_netdev_flow *flow;
  
      HMAP_FOR_EACH_WITH_HASH (flow, node, flow_hash(key, 0), &dp->flow_table) {
          if (flow_equal(&flow->key, key)) {
              return flow;
          }
      }
      return NULL;
  }
  
  static void
  get_dpif_flow_stats(struct dp_netdev_flow *flow, struct dpif_flow_stats *stats)
  {
      stats->n_packets = flow->packet_count;
      stats->n_bytes = flow->byte_count;
      stats->used = flow->used;
      stats->tcp_flags = TCP_FLAGS(flow->tcp_ctl);
  }
  
  static int
  dpif_netdev_flow_from_nlattrs(const struct nlattr *key, uint32_t key_len,
                                struct flow *flow)
  {
      if (odp_flow_key_to_flow(key, key_len, flow)) {
          /* This should not happen: it indicates that odp_flow_key_from_flow()
           * and odp_flow_key_to_flow() disagree on the acceptable form of a
           * flow.  Log the problem as an error, with enough details to enable
           * debugging. */
          static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(1, 5);
  
          if (!VLOG_DROP_ERR(&rl)) {
              struct ds s;
  
              ds_init(&s);
              odp_flow_key_format(key, key_len, &s);
              VLOG_ERR("internal error parsing flow key %s", ds_cstr(&s));
              ds_destroy(&s);
          }
  
          return EINVAL;
      }
  
      if (flow->in_port < OFPP_MAX
          ? flow->in_port >= MAX_PORTS
          : flow->in_port != OFPP_LOCAL && flow->in_port != OFPP_NONE) {
          return EINVAL;
      }
  
      return 0;
  }
  
  static int
  dpif_netdev_flow_get(const struct dpif *dpif,
                       const struct nlattr *nl_key, size_t nl_key_len,
                       struct ofpbuf **actionsp, struct dpif_flow_stats *stats)
  {
      struct dp_netdev *dp = get_dp_netdev(dpif);
      struct dp_netdev_flow *flow;
      struct flow key;
      int error;
  
      error = dpif_netdev_flow_from_nlattrs(nl_key, nl_key_len, &key);
      if (error) {
          return error;
      }
  
      flow = dp_netdev_lookup_flow(dp, &key);
      if (!flow) {
          return ENOENT;
      }
  
      if (stats) {
          get_dpif_flow_stats(flow, stats);
      }
      if (actionsp) {
          *actionsp = ofpbuf_clone_data(flow->actions, flow->actions_len);
      }
      return 0;
  }
  
  static int
  dpif_netdev_validate_actions(const struct nlattr *actions,
                               size_t actions_len, bool *mutates)
  {
      const struct nlattr *a;
      unsigned int left;
  
      *mutates = false;
      NL_ATTR_FOR_EACH (a, left, actions, actions_len) {
          uint16_t type = nl_attr_type(a);
          int len = odp_action_len(type);
  
          if (len != nl_attr_get_size(a)) {
              return EINVAL;
          }
  
          switch (type) {
          case OVS_ACTION_ATTR_OUTPUT:
              if (nl_attr_get_u32(a) >= MAX_PORTS) {
                  return EINVAL;
              }
              break;
  
          case OVS_ACTION_ATTR_USERSPACE:
              break;
  
          case OVS_ACTION_ATTR_PUSH_VLAN:
              *mutates = true;
              if (nl_attr_get_be16(a) & htons(VLAN_CFI)) {
                  return EINVAL;
              }
              break;
  
          case OVS_ACTION_ATTR_SET_NW_TOS:
              *mutates = true;
              if (nl_attr_get_u8(a) & IP_ECN_MASK) {
                  return EINVAL;
              }
              break;
  
          case OVS_ACTION_ATTR_POP_VLAN:
          case OVS_ACTION_ATTR_SET_DL_SRC:
          case OVS_ACTION_ATTR_SET_DL_DST:
          case OVS_ACTION_ATTR_SET_NW_SRC:
          case OVS_ACTION_ATTR_SET_NW_DST:
          case OVS_ACTION_ATTR_SET_TP_SRC:
          case OVS_ACTION_ATTR_SET_TP_DST:
              *mutates = true;
              break;
  
          case OVS_ACTION_ATTR_SET_TUNNEL:
          case OVS_ACTION_ATTR_SET_PRIORITY:
          case OVS_ACTION_ATTR_POP_PRIORITY:
          default:
              return EOPNOTSUPP;
          }
      }
      return 0;
  }
  
  static int
  set_flow_actions(struct dp_netdev_flow *flow,
                   const struct nlattr *actions, size_t actions_len)
  {
      bool mutates;
      int error;
  
      error = dpif_netdev_validate_actions(actions, actions_len, &mutates);
      if (error) {
          return error;
      }
  
      flow->actions = xrealloc(flow->actions, actions_len);
      flow->actions_len = actions_len;
      memcpy(flow->actions, actions, actions_len);
      return 0;
  }
  
  static int
  add_flow(struct dpif *dpif, const struct flow *key,
           const struct nlattr *actions, size_t actions_len)
  {
      struct dp_netdev *dp = get_dp_netdev(dpif);
      struct dp_netdev_flow *flow;
      int error;
  
      flow = xzalloc(sizeof *flow);
      flow->key = *key;
  
      error = set_flow_actions(flow, actions, actions_len);
      if (error) {
          free(flow);
          return error;
      }
  
      hmap_insert(&dp->flow_table, &flow->node, flow_hash(&flow->key, 0));
      return 0;
  }
  
  static void
  clear_stats(struct dp_netdev_flow *flow)
  {
      flow->used = 0;
      flow->packet_count = 0;
      flow->byte_count = 0;
      flow->tcp_ctl = 0;
  }
  
  static int
  dpif_netdev_flow_put(struct dpif *dpif, enum dpif_flow_put_flags flags,
                      const struct nlattr *nl_key, size_t nl_key_len,
                      const struct nlattr *actions, size_t actions_len,
                      struct dpif_flow_stats *stats)
  {
      struct dp_netdev *dp = get_dp_netdev(dpif);
      struct dp_netdev_flow *flow;
      struct flow key;
      int error;
  
      error = dpif_netdev_flow_from_nlattrs(nl_key, nl_key_len, &key);
      if (error) {
          return error;
      }
  
      flow = dp_netdev_lookup_flow(dp, &key);
      if (!flow) {
          if (flags & DPIF_FP_CREATE) {
              if (hmap_count(&dp->flow_table) < MAX_FLOWS) {
                  if (stats) {
                      memset(stats, 0, sizeof *stats);
                  }
                  return add_flow(dpif, &key, actions, actions_len);
              } else {
                  return EFBIG;
              }
          } else {
              return ENOENT;
          }
      } else {
          if (flags & DPIF_FP_MODIFY) {
              int error = set_flow_actions(flow, actions, actions_len);
              if (!error) {
                  if (stats) {
                      get_dpif_flow_stats(flow, stats);
                  }
                  if (flags & DPIF_FP_ZERO_STATS) {
                      clear_stats(flow);
                  }
              }
              return error;
          } else {
              return EEXIST;
          }
      }
  }
  
  static int
  dpif_netdev_flow_del(struct dpif *dpif,
                       const struct nlattr *nl_key, size_t nl_key_len,
                       struct dpif_flow_stats *stats)
  {
      struct dp_netdev *dp = get_dp_netdev(dpif);
      struct dp_netdev_flow *flow;
      struct flow key;
      int error;
  
      error = dpif_netdev_flow_from_nlattrs(nl_key, nl_key_len, &key);
      if (error) {
          return error;
      }
  
      flow = dp_netdev_lookup_flow(dp, &key);
      if (flow) {
          if (stats) {
              get_dpif_flow_stats(flow, stats);
          }
          dp_netdev_free_flow(dp, flow);
          return 0;
      } else {
          return ENOENT;
      }
  }
  
  struct dp_netdev_flow_state {
      uint32_t bucket;
      uint32_t offset;
      struct nlattr *actions;
      struct odputil_keybuf keybuf;
      struct dpif_flow_stats stats;
  };
  
  static int
  dpif_netdev_flow_dump_start(const struct dpif *dpif OVS_UNUSED, void **statep)
  {
      struct dp_netdev_flow_state *state;
  
      *statep = state = xmalloc(sizeof *state);
      state->bucket = 0;
      state->offset = 0;
      state->actions = NULL;
      return 0;
  }
  
  static int
  dpif_netdev_flow_dump_next(const struct dpif *dpif, void *state_,
                             const struct nlattr **key, size_t *key_len,
                             const struct nlattr **actions, size_t *actions_len,
                             const struct dpif_flow_stats **stats)
  {
      struct dp_netdev_flow_state *state = state_;
      struct dp_netdev *dp = get_dp_netdev(dpif);
      struct dp_netdev_flow *flow;
      struct hmap_node *node;
  
      node = hmap_at_position(&dp->flow_table, &state->bucket, &state->offset);
      if (!node) {
          return EOF;
      }
  
      flow = CONTAINER_OF(node, struct dp_netdev_flow, node);
  
      if (key) {
          struct ofpbuf buf;
  
          ofpbuf_use_stack(&buf, &state->keybuf, sizeof state->keybuf);
          odp_flow_key_from_flow(&buf, &flow->key);
  
          *key = buf.data;
          *key_len = buf.size;
      }
  
      if (actions) {
          free(state->actions);
          state->actions = xmemdup(flow->actions, flow->actions_len);
  
          *actions = state->actions;
          *actions_len = flow->actions_len;
      }
  
      if (stats) {
          get_dpif_flow_stats(flow, &state->stats);
          *stats = &state->stats;
      }
  
      return 0;
  }
  
  static int
  dpif_netdev_flow_dump_done(const struct dpif *dpif OVS_UNUSED, void *state_)
  {
      struct dp_netdev_flow_state *state = state_;
  
      free(state->actions);
      free(state);
      return 0;
  }
  
  static int
  dpif_netdev_execute(struct dpif *dpif,
                      const struct nlattr *key_attrs, size_t key_len,
                      const struct nlattr *actions, size_t actions_len,
                      const struct ofpbuf *packet)
  {
      struct dp_netdev *dp = get_dp_netdev(dpif);
      struct ofpbuf copy;
      bool mutates;
      struct flow key;
      int error;
  
      if (packet->size < ETH_HEADER_LEN || packet->size > UINT16_MAX) {
          return EINVAL;
      }
  
      error = dpif_netdev_validate_actions(actions, actions_len, &mutates);
      if (error) {
          return error;
      }
  
      if (mutates) {
          /* We need a deep copy of 'packet' since we're going to modify its
           * data. */
          ofpbuf_init(&copy, DP_NETDEV_HEADROOM + packet->size);
          ofpbuf_reserve(&copy, DP_NETDEV_HEADROOM);
          ofpbuf_put(&copy, packet->data, packet->size);
      } else {
          /* We still need a shallow copy of 'packet', even though we won't
           * modify its data, because flow_extract() modifies packet->l2, etc.
           * We could probably get away with modifying those but it's more polite
           * if we don't. */
          copy = *packet;
      }
  
      flow_extract(&copy, 0, -1, &key);
      error = dpif_netdev_flow_from_nlattrs(key_attrs, key_len, &key);
      if (!error) {
          error = dp_netdev_execute_actions(dp, &copy, &key,
                                            actions, actions_len);
      }
      if (mutates) {
          ofpbuf_uninit(&copy);
      }
      return error;
  }
  
  static int
  dpif_netdev_recv_get_mask(const struct dpif *dpif, int *listen_mask)
  {
      struct dpif_netdev *dpif_netdev = dpif_netdev_cast(dpif);
      *listen_mask = dpif_netdev->listen_mask;
      return 0;
  }
  
  static int
  dpif_netdev_recv_set_mask(struct dpif *dpif, int listen_mask)
  {
      struct dpif_netdev *dpif_netdev = dpif_netdev_cast(dpif);
      dpif_netdev->listen_mask = listen_mask;
      return 0;
  }
  
  static struct dp_netdev_queue *
  find_nonempty_queue(struct dpif *dpif)
  {
      struct dpif_netdev *dpif_netdev = dpif_netdev_cast(dpif);
      struct dp_netdev *dp = get_dp_netdev(dpif);
      int mask = dpif_netdev->listen_mask;
      int i;
  
      for (i = 0; i < N_QUEUES; i++) {
          struct dp_netdev_queue *q = &dp->queues[i];
          if (q->head != q->tail && mask & (1u << i)) {
              return q;
          }
      }
      return NULL;
  }
  
  static int
  dpif_netdev_recv(struct dpif *dpif, struct dpif_upcall *upcall)
  {
      struct dp_netdev_queue *q = find_nonempty_queue(dpif);
      if (q) {
          struct dpif_upcall *u = q->upcalls[q->tail++ & QUEUE_MASK];
          *upcall = *u;
          free(u);
  
          return 0;
      } else {
          return EAGAIN;
      }
  }
  
  static void
  dpif_netdev_recv_wait(struct dpif *dpif)
  {
      if (find_nonempty_queue(dpif)) {
          poll_immediate_wake();
      } else {
          /* No messages ready to be received, and dp_wait() will ensure that we
           * wake up to queue new messages, so there is nothing to do. */
      }
  }
  
  static void
  dpif_netdev_recv_purge(struct dpif *dpif)
  {
      struct dpif_netdev *dpif_netdev = dpif_netdev_cast(dpif);
      dp_netdev_purge_queues(dpif_netdev->dp);
  }
  
  static void
  dp_netdev_flow_used(struct dp_netdev_flow *flow, struct flow *key,
                      const struct ofpbuf *packet)
  {
      flow->used = time_msec();
      flow->packet_count++;
      flow->byte_count += packet->size;
      if (key->dl_type == htons(ETH_TYPE_IP) && key->nw_proto == IPPROTO_TCP) {
          struct tcp_header *th = packet->l4;
          flow->tcp_ctl |= th->tcp_ctl;
      }
  }
  
  static void
  dp_netdev_port_input(struct dp_netdev *dp, struct dp_netdev_port *port,
                       struct ofpbuf *packet)
  {
      struct dp_netdev_flow *flow;
      struct flow key;
  
      if (packet->size < ETH_HEADER_LEN) {
          return;
      }
      if (flow_extract(packet, 0, port->port_no, &key) && dp->drop_frags) {
          dp->n_frags++;
          return;
      }
  
      flow = dp_netdev_lookup_flow(dp, &key);
      if (flow) {
          dp_netdev_flow_used(flow, &key, packet);
          dp_netdev_execute_actions(dp, packet, &key,
                                    flow->actions, flow->actions_len);
          dp->n_hit++;
      } else {
          dp->n_missed++;
          dp_netdev_output_userspace(dp, packet, DPIF_UC_MISS, &key, 0);
      }
  }
  
  static void
  dpif_netdev_run(struct dpif *dpif)
  {
      struct dp_netdev *dp = get_dp_netdev(dpif);
      struct dp_netdev_port *port;
      struct ofpbuf packet;
  
      ofpbuf_init(&packet, DP_NETDEV_HEADROOM + VLAN_ETH_HEADER_LEN + max_mtu);
  
      LIST_FOR_EACH (port, node, &dp->port_list) {
          int error;
  
          /* Reset packet contents. */
          ofpbuf_clear(&packet);
          ofpbuf_reserve(&packet, DP_NETDEV_HEADROOM);
  
          error = netdev_recv(port->netdev, &packet);
          if (!error) {
              dp_netdev_port_input(dp, port, &packet);
          } else if (error != EAGAIN && error != EOPNOTSUPP) {
              static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(1, 5);
              VLOG_ERR_RL(&rl, "error receiving data from %s: %s",
                          netdev_get_name(port->netdev), strerror(error));
          }
      }
      ofpbuf_uninit(&packet);
  }
  
  static void
  dpif_netdev_wait(struct dpif *dpif)
  {
      struct dp_netdev *dp = get_dp_netdev(dpif);
      struct dp_netdev_port *port;
  
      LIST_FOR_EACH (port, node, &dp->port_list) {
          netdev_recv_wait(port->netdev);
      }
  }
  
  static void
  dp_netdev_pop_vlan(struct ofpbuf *packet)
  {
      struct vlan_eth_header *veh = packet->l2;
      if (packet->size >= sizeof *veh
          && veh->veth_type == htons(ETH_TYPE_VLAN)) {
          struct eth_header tmp;
  
          memcpy(tmp.eth_dst, veh->veth_dst, ETH_ADDR_LEN);
          memcpy(tmp.eth_src, veh->veth_src, ETH_ADDR_LEN);
          tmp.eth_type = veh->veth_next_type;
  
          ofpbuf_pull(packet, VLAN_HEADER_LEN);
          packet->l2 = (char*)packet->l2 + VLAN_HEADER_LEN;
          memcpy(packet->data, &tmp, sizeof tmp);
      }
  }
  
  static void
  dp_netdev_set_dl_src(struct ofpbuf *packet, const uint8_t dl_addr[ETH_ADDR_LEN])
  {
      struct eth_header *eh = packet->l2;
      memcpy(eh->eth_src, dl_addr, sizeof eh->eth_src);
  }
  
  static void
  dp_netdev_set_dl_dst(struct ofpbuf *packet, const uint8_t dl_addr[ETH_ADDR_LEN])
  {
      struct eth_header *eh = packet->l2;
      memcpy(eh->eth_dst, dl_addr, sizeof eh->eth_dst);
  }
  
  static bool
  is_ip(const struct ofpbuf *packet, const struct flow *key)
  {
      return key->dl_type == htons(ETH_TYPE_IP) && packet->l4;
  }
  
  static void
  dp_netdev_set_nw_addr(struct ofpbuf *packet, const struct flow *key,
                        const struct nlattr *a)
  {
      if (is_ip(packet, key)) {
          struct ip_header *nh = packet->l3;
          ovs_be32 ip = nl_attr_get_be32(a);
          uint16_t type = nl_attr_type(a);
          ovs_be32 *field;
  
          field = type == OVS_ACTION_ATTR_SET_NW_SRC ? &nh->ip_src : &nh->ip_dst;
          if (key->nw_proto == IPPROTO_TCP && packet->l7) {
              struct tcp_header *th = packet->l4;
              th->tcp_csum = recalc_csum32(th->tcp_csum, *field, ip);
          } else if (key->nw_proto == IPPROTO_UDP && packet->l7) {
              struct udp_header *uh = packet->l4;
              if (uh->udp_csum) {
                  uh->udp_csum = recalc_csum32(uh->udp_csum, *field, ip);
                  if (!uh->udp_csum) {
                      uh->udp_csum = htons(0xffff);
                  }
              }
          }
          nh->ip_csum = recalc_csum32(nh->ip_csum, *field, ip);
          *field = ip;
      }
  }
  
  static void
  dp_netdev_set_nw_tos(struct ofpbuf *packet, const struct flow *key,
                       uint8_t nw_tos)
  {
      if (is_ip(packet, key)) {
          struct ip_header *nh = packet->l3;
          uint8_t *field = &nh->ip_tos;
  
          /* Set the DSCP bits and preserve the ECN bits. */
          uint8_t new = nw_tos | (nh->ip_tos & IP_ECN_MASK);
  
          nh->ip_csum = recalc_csum16(nh->ip_csum, htons((uint16_t)*field),
                  htons((uint16_t) new));
          *field = new;
      }
  }
  
  static void
  dp_netdev_set_tp_port(struct ofpbuf *packet, const struct flow *key,
                        const struct nlattr *a)
  {
  	if (is_ip(packet, key)) {
          uint16_t type = nl_attr_type(a);
          ovs_be16 port = nl_attr_get_be16(a);
          ovs_be16 *field;
  
          if (key->nw_proto == IPPROTO_TCP && packet->l7) {
              struct tcp_header *th = packet->l4;
              field = (type == OVS_ACTION_ATTR_SET_TP_SRC
                       ? &th->tcp_src : &th->tcp_dst);
              th->tcp_csum = recalc_csum16(th->tcp_csum, *field, port);
              *field = port;
          } else if (key->nw_proto == IPPROTO_UDP && packet->l7) {
              struct udp_header *uh = packet->l4;
              field = (type == OVS_ACTION_ATTR_SET_TP_SRC
                       ? &uh->udp_src : &uh->udp_dst);
              uh->udp_csum = recalc_csum16(uh->udp_csum, *field, port);
              *field = port;
          } else {
              return;
          }
      }
  }
  
  static void
  dp_netdev_output_port(struct dp_netdev *dp, struct ofpbuf *packet,
                        uint16_t out_port)
  {
      struct dp_netdev_port *p = dp->ports[out_port];
      if (p) {
          netdev_send(p->netdev, packet);
      }
  }
  
  static int
  dp_netdev_output_userspace(struct dp_netdev *dp, const struct ofpbuf *packet,
                           int queue_no, const struct flow *flow, uint64_t arg)
  {
      struct dp_netdev_queue *q = &dp->queues[queue_no];
      struct dpif_upcall *upcall;
      struct ofpbuf *buf;
      size_t key_len;
  
      if (q->head - q->tail >= MAX_QUEUE_LEN) {
          dp->n_lost++;
          return ENOBUFS;
      }
  
      buf = ofpbuf_new(ODPUTIL_FLOW_KEY_BYTES + 2 + packet->size);
      odp_flow_key_from_flow(buf, flow);
      key_len = buf->size;
      ofpbuf_pull(buf, key_len);
      ofpbuf_reserve(buf, 2);
      ofpbuf_put(buf, packet->data, packet->size);
  
      upcall = xzalloc(sizeof *upcall);
      upcall->type = queue_no;
      upcall->packet = buf;
      upcall->key = buf->base;
      upcall->key_len = key_len;
      upcall->userdata = arg;
  
      q->upcalls[q->head++ & QUEUE_MASK] = upcall;
  
      return 0;
  }
  
  static int
  dp_netdev_execute_actions(struct dp_netdev *dp,
                            struct ofpbuf *packet, struct flow *key,
                            const struct nlattr *actions,
                            size_t actions_len)
  {
      const struct nlattr *a;
      unsigned int left;
  
      NL_ATTR_FOR_EACH_UNSAFE (a, left, actions, actions_len) {
          switch (nl_attr_type(a)) {
          case OVS_ACTION_ATTR_OUTPUT:
              dp_netdev_output_port(dp, packet, nl_attr_get_u32(a));
              break;
  
          case OVS_ACTION_ATTR_USERSPACE:
              dp_netdev_output_userspace(dp, packet, DPIF_UC_ACTION,
                                       key, nl_attr_get_u64(a));
              break;
  
          case OVS_ACTION_ATTR_PUSH_VLAN:
              eth_push_vlan(packet, nl_attr_get_be16(a));
              break;
  
          case OVS_ACTION_ATTR_POP_VLAN:
              dp_netdev_pop_vlan(packet);
              break;
  
          case OVS_ACTION_ATTR_SET_DL_SRC:
              dp_netdev_set_dl_src(packet, nl_attr_get_unspec(a, ETH_ADDR_LEN));
              break;
  
          case OVS_ACTION_ATTR_SET_DL_DST:
              dp_netdev_set_dl_dst(packet, nl_attr_get_unspec(a, ETH_ADDR_LEN));
              break;
  
          case OVS_ACTION_ATTR_SET_NW_SRC:
          case OVS_ACTION_ATTR_SET_NW_DST:
              dp_netdev_set_nw_addr(packet, key, a);
              break;
  
          case OVS_ACTION_ATTR_SET_NW_TOS:
              dp_netdev_set_nw_tos(packet, key, nl_attr_get_u8(a));
              break;
  
          case OVS_ACTION_ATTR_SET_TP_SRC:
          case OVS_ACTION_ATTR_SET_TP_DST:
              dp_netdev_set_tp_port(packet, key, a);
              break;
          }
      }
      return 0;
  }
  
  const struct dpif_class dpif_netdev_class = {
      "netdev",
      NULL,                       /* enumerate */
      dpif_netdev_open,
      dpif_netdev_close,
      dpif_netdev_destroy,
      dpif_netdev_run,
      dpif_netdev_wait,
      dpif_netdev_get_stats,
      dpif_netdev_get_drop_frags,
      dpif_netdev_set_drop_frags,
      dpif_netdev_port_add,
      dpif_netdev_port_del,
      dpif_netdev_port_query_by_number,
      dpif_netdev_port_query_by_name,
      dpif_netdev_get_max_ports,
      dpif_netdev_port_dump_start,
      dpif_netdev_port_dump_next,
      dpif_netdev_port_dump_done,
      dpif_netdev_port_poll,
      dpif_netdev_port_poll_wait,
      dpif_netdev_flow_get,
      dpif_netdev_flow_put,
      dpif_netdev_flow_del,
      dpif_netdev_flow_flush,
      dpif_netdev_flow_dump_start,
      dpif_netdev_flow_dump_next,
      dpif_netdev_flow_dump_done,
      dpif_netdev_execute,
      dpif_netdev_recv_get_mask,
      dpif_netdev_recv_set_mask,
      NULL,                       /* get_sflow_probability */
      NULL,                       /* set_sflow_probability */
      NULL,                       /* queue_to_priority */
      dpif_netdev_recv,
      dpif_netdev_recv_wait,
      dpif_netdev_recv_purge,
  };
  
  void
  dpif_dummy_register(void)
  {
      if (!dpif_dummy_class.type) {
          dpif_dummy_class = dpif_netdev_class;
          dpif_dummy_class.type = "dummy";
          dp_register_provider(&dpif_dummy_class);
      }
  }
  