text: /*
   * Copyright (c) 2009, 2010, 2011, 2012 Nicira, Inc.
   * Copyright (c) 2010 Jean Tourrilhes - HP-Labs.
   *
   * 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 "ofproto.h"
  #include <errno.h>
  #include <inttypes.h>
  #include <stdbool.h>
  #include <stdlib.h>
  #include "bitmap.h"
  #include "byte-order.h"
  #include "classifier.h"
  #include "connmgr.h"
  #include "coverage.h"
  #include "dynamic-string.h"
  #include "hash.h"
  #include "hmap.h"
  #include "meta-flow.h"
  #include "netdev.h"
  #include "nx-match.h"
  #include "ofp-actions.h"
  #include "ofp-errors.h"
  #include "ofp-msgs.h"
  #include "ofp-print.h"
  #include "ofp-util.h"
  #include "ofpbuf.h"
  #include "ofproto-provider.h"
  #include "openflow/nicira-ext.h"
  #include "openflow/openflow.h"
  #include "packets.h"
  #include "pinsched.h"
  #include "pktbuf.h"
  #include "poll-loop.h"
  #include "random.h"
  #include "shash.h"
  #include "simap.h"
  #include "sset.h"
  #include "timeval.h"
  #include "unaligned.h"
  #include "unixctl.h"
  #include "vlog.h"
  
  VLOG_DEFINE_THIS_MODULE(ofproto);
  
  COVERAGE_DEFINE(ofproto_error);
  COVERAGE_DEFINE(ofproto_flush);
  COVERAGE_DEFINE(ofproto_no_packet_in);
  COVERAGE_DEFINE(ofproto_packet_out);
  COVERAGE_DEFINE(ofproto_queue_req);
  COVERAGE_DEFINE(ofproto_recv_openflow);
  COVERAGE_DEFINE(ofproto_reinit_ports);
  COVERAGE_DEFINE(ofproto_uninstallable);
  COVERAGE_DEFINE(ofproto_update_port);
  
  enum ofproto_state {
      S_OPENFLOW,                 /* Processing OpenFlow commands. */
      S_EVICT,                    /* Evicting flows from over-limit tables. */
      S_FLUSH,                    /* Deleting all flow table rules. */
  };
  
  enum ofoperation_type {
      OFOPERATION_ADD,
      OFOPERATION_DELETE,
      OFOPERATION_MODIFY
  };
  
  /* A single OpenFlow request can execute any number of operations.  The
   * ofopgroup maintain OpenFlow state common to all of the operations, e.g. the
   * ofconn to which an error reply should be sent if necessary.
   *
   * ofproto initiates some operations internally.  These operations are still
   * assigned to groups but will not have an associated ofconn. */
  struct ofopgroup {
      struct ofproto *ofproto;    /* Owning ofproto. */
      struct list ofproto_node;   /* In ofproto's "pending" list. */
      struct list ops;            /* List of "struct ofoperation"s. */
      int n_running;              /* Number of ops still pending. */
  
      /* Data needed to send OpenFlow reply on failure or to send a buffered
       * packet on success.
       *
       * If list_is_empty(ofconn_node) then this ofopgroup never had an
       * associated ofconn or its ofconn's connection dropped after it initiated
       * the operation.  In the latter case 'ofconn' is a wild pointer that
       * refers to freed memory, so the 'ofconn' member must be used only if
       * !list_is_empty(ofconn_node).
       */
      struct list ofconn_node;    /* In ofconn's list of pending opgroups. */
      struct ofconn *ofconn;      /* ofconn for reply (but see note above). */
      struct ofp_header *request; /* Original request (truncated at 64 bytes). */
      uint32_t buffer_id;         /* Buffer id from original request. */
  };
  
  static struct ofopgroup *ofopgroup_create_unattached(struct ofproto *);
  static struct ofopgroup *ofopgroup_create(struct ofproto *, struct ofconn *,
                                            const struct ofp_header *,
                                            uint32_t buffer_id);
  static void ofopgroup_submit(struct ofopgroup *);
  static void ofopgroup_complete(struct ofopgroup *);
  
  /* A single flow table operation. */
  struct ofoperation {
      struct ofopgroup *group;    /* Owning group. */
      struct list group_node;     /* In ofopgroup's "ops" list. */
      struct hmap_node hmap_node; /* In ofproto's "deletions" hmap. */
      struct rule *rule;          /* Rule being operated upon. */
      enum ofoperation_type type; /* Type of operation. */
  
      /* OFOPERATION_ADD. */
      struct rule *victim;        /* Rule being replaced, if any.. */
  
      /* OFOPERATION_MODIFY: The old actions, if the actions are changing. */
      struct ofpact *ofpacts;
      size_t ofpacts_len;
  
      /* OFOPERATION_DELETE. */
      enum ofp_flow_removed_reason reason; /* Reason flow was removed. */
  
      ovs_be64 flow_cookie;       /* Rule's old flow cookie. */
      enum ofperr error;          /* 0 if no error. */
  };
  
  static struct ofoperation *ofoperation_create(struct ofopgroup *,
                                                struct rule *,
                                                enum ofoperation_type,
                                                enum ofp_flow_removed_reason);
  static void ofoperation_destroy(struct ofoperation *);
  
  /* oftable. */
  static void oftable_init(struct oftable *);
  static void oftable_destroy(struct oftable *);
  
  static void oftable_set_name(struct oftable *, const char *name);
  
  static void oftable_disable_eviction(struct oftable *);
  static void oftable_enable_eviction(struct oftable *,
                                      const struct mf_subfield *fields,
                                      size_t n_fields);
  
  static void oftable_remove_rule(struct rule *);
  static struct rule *oftable_replace_rule(struct rule *);
  static void oftable_substitute_rule(struct rule *old, struct rule *new);
  
  /* A set of rules within a single OpenFlow table (oftable) that have the same
   * values for the oftable's eviction_fields.  A rule to be evicted, when one is
   * needed, is taken from the eviction group that contains the greatest number
   * of rules.
   *
   * An oftable owns any number of eviction groups, each of which contains any
   * number of rules.
   *
   * Membership in an eviction group is imprecise, based on the hash of the
   * oftable's eviction_fields (in the eviction_group's id_node.hash member).
   * That is, if two rules have different eviction_fields, but those
   * eviction_fields hash to the same value, then they will belong to the same
   * eviction_group anyway.
   *
   * (When eviction is not enabled on an oftable, we don't track any eviction
   * groups, to save time and space.) */
  struct eviction_group {
      struct hmap_node id_node;   /* In oftable's "eviction_groups_by_id". */
      struct heap_node size_node; /* In oftable's "eviction_groups_by_size". */
      struct heap rules;          /* Contains "struct rule"s. */
  };
  
  static struct rule *choose_rule_to_evict(struct oftable *);
  static void ofproto_evict(struct ofproto *);
  static uint32_t rule_eviction_priority(struct rule *);
  
  /* ofport. */
  static void ofport_destroy__(struct ofport *);
  static void ofport_destroy(struct ofport *);
  
  static void update_port(struct ofproto *, const char *devname);
  static int init_ports(struct ofproto *);
  static void reinit_ports(struct ofproto *);
  
  /* rule. */
  static void ofproto_rule_destroy__(struct rule *);
  static void ofproto_rule_send_removed(struct rule *, uint8_t reason);
  static bool rule_is_modifiable(const struct rule *);
  
  /* OpenFlow. */
  static enum ofperr add_flow(struct ofproto *, struct ofconn *,
                              const struct ofputil_flow_mod *,
                              const struct ofp_header *);
  static void delete_flow__(struct rule *, struct ofopgroup *);
  static bool handle_openflow(struct ofconn *, struct ofpbuf *);
  static enum ofperr handle_flow_mod__(struct ofproto *, struct ofconn *,
                                       const struct ofputil_flow_mod *,
                                       const struct ofp_header *);
  
  /* ofproto. */
  static uint64_t pick_datapath_id(const struct ofproto *);
  static uint64_t pick_fallback_dpid(void);
  static void ofproto_destroy__(struct ofproto *);
  static void update_mtu(struct ofproto *, struct ofport *);
  
  /* unixctl. */
  static void ofproto_unixctl_init(void);
  
  /* All registered ofproto classes, in probe order. */
  static const struct ofproto_class **ofproto_classes;
  static size_t n_ofproto_classes;
  static size_t allocated_ofproto_classes;
  
  /* Map from datapath name to struct ofproto, for use by unixctl commands. */
  static struct hmap all_ofprotos = HMAP_INITIALIZER(&all_ofprotos);
  
  static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(1, 5);
  
  static void
  ofproto_initialize(void)
  {
      static bool inited;
  
      if (!inited) {
          inited = true;
          ofproto_class_register(&ofproto_dpif_class);
      }
  }
  
  /* 'type' should be a normalized datapath type, as returned by
   * ofproto_normalize_type().  Returns the corresponding ofproto_class
   * structure, or a null pointer if there is none registered for 'type'. */
  static const struct ofproto_class *
  ofproto_class_find__(const char *type)
  {
      size_t i;
  
      ofproto_initialize();
      for (i = 0; i < n_ofproto_classes; i++) {
          const struct ofproto_class *class = ofproto_classes[i];
          struct sset types;
          bool found;
  
          sset_init(&types);
          class->enumerate_types(&types);
          found = sset_contains(&types, type);
          sset_destroy(&types);
  
          if (found) {
              return class;
          }
      }
      VLOG_WARN("unknown datapath type %s", type);
      return NULL;
  }
  
  /* Registers a new ofproto class.  After successful registration, new ofprotos
   * of that type can be created using ofproto_create(). */
  int
  ofproto_class_register(const struct ofproto_class *new_class)
  {
      size_t i;
  
      for (i = 0; i < n_ofproto_classes; i++) {
          if (ofproto_classes[i] == new_class) {
              return EEXIST;
          }
      }
  
      if (n_ofproto_classes >= allocated_ofproto_classes) {
          ofproto_classes = x2nrealloc(ofproto_classes,
                                       &allocated_ofproto_classes,
                                       sizeof *ofproto_classes);
      }
      ofproto_classes[n_ofproto_classes++] = new_class;
      return 0;
  }
  
  /* Unregisters a datapath provider.  'type' must have been previously
   * registered and not currently be in use by any ofprotos.  After
   * unregistration new datapaths of that type cannot be opened using
   * ofproto_create(). */
  int
  ofproto_class_unregister(const struct ofproto_class *class)
  {
      size_t i;
  
      for (i = 0; i < n_ofproto_classes; i++) {
          if (ofproto_classes[i] == class) {
              for (i++; i < n_ofproto_classes; i++) {
                  ofproto_classes[i - 1] = ofproto_classes[i];
              }
              n_ofproto_classes--;
              return 0;
          }
      }
      VLOG_WARN("attempted to unregister an ofproto class that is not "
                "registered");
      return EAFNOSUPPORT;
  }
  
  /* Clears 'types' and enumerates all registered ofproto types into it.  The
   * caller must first initialize the sset. */
  void
  ofproto_enumerate_types(struct sset *types)
  {
      size_t i;
  
      ofproto_initialize();
      for (i = 0; i < n_ofproto_classes; i++) {
          ofproto_classes[i]->enumerate_types(types);
      }
  }
  
  /* Returns the fully spelled out name for the given ofproto 'type'.
   *
   * Normalized type string can be compared with strcmp().  Unnormalized type
   * string might be the same even if they have different spellings. */
  const char *
  ofproto_normalize_type(const char *type)
  {
      return type && type[0] ? type : "system";
  }
  
  /* Clears 'names' and enumerates the names of all known created ofprotos with
   * the given 'type'.  The caller must first initialize the sset.  Returns 0 if
   * successful, otherwise a positive errno value.
   *
   * Some kinds of datapaths might not be practically enumerable.  This is not
   * considered an error. */
  int
  ofproto_enumerate_names(const char *type, struct sset *names)
  {
      const struct ofproto_class *class = ofproto_class_find__(type);
      return class ? class->enumerate_names(type, names) : EAFNOSUPPORT;
   }
  
  int
  ofproto_create(const char *datapath_name, const char *datapath_type,
                 struct ofproto **ofprotop)
  {
      const struct ofproto_class *class;
      struct ofproto *ofproto;
      int error;
  
      *ofprotop = NULL;
  
      ofproto_initialize();
      ofproto_unixctl_init();
  
      datapath_type = ofproto_normalize_type(datapath_type);
      class = ofproto_class_find__(datapath_type);
      if (!class) {
          VLOG_WARN("could not create datapath %s of unknown type %s",
                    datapath_name, datapath_type);
          return EAFNOSUPPORT;
      }
  
      ofproto = class->alloc();
      if (!ofproto) {
          VLOG_ERR("failed to allocate datapath %s of type %s",
                   datapath_name, datapath_type);
          return ENOMEM;
      }
  
      /* Initialize. */
      memset(ofproto, 0, sizeof *ofproto);
      ofproto->ofproto_class = class;
      ofproto->name = xstrdup(datapath_name);
      ofproto->type = xstrdup(datapath_type);
      hmap_insert(&all_ofprotos, &ofproto->hmap_node,
                  hash_string(ofproto->name, 0));
      ofproto->datapath_id = 0;
      ofproto_set_flow_eviction_threshold(ofproto,
                                          OFPROTO_FLOW_EVICTON_THRESHOLD_DEFAULT);
      ofproto->forward_bpdu = false;
      ofproto->fallback_dpid = pick_fallback_dpid();
      ofproto->mfr_desc = xstrdup(DEFAULT_MFR_DESC);
      ofproto->hw_desc = xstrdup(DEFAULT_HW_DESC);
      ofproto->sw_desc = xstrdup(DEFAULT_SW_DESC);
      ofproto->serial_desc = xstrdup(DEFAULT_SERIAL_DESC);
      ofproto->dp_desc = xstrdup(DEFAULT_DP_DESC);
      ofproto->frag_handling = OFPC_FRAG_NORMAL;
      hmap_init(&ofproto->ports);
      shash_init(&ofproto->port_by_name);
      ofproto->tables = NULL;
      ofproto->n_tables = 0;
      ofproto->connmgr = connmgr_create(ofproto, datapath_name, datapath_name);
      ofproto->state = S_OPENFLOW;
      list_init(&ofproto->pending);
      ofproto->n_pending = 0;
      hmap_init(&ofproto->deletions);
      ofproto->n_add = ofproto->n_delete = ofproto->n_modify = 0;
      ofproto->first_op = ofproto->last_op = LLONG_MIN;
      ofproto->next_op_report = LLONG_MAX;
      ofproto->op_backoff = LLONG_MIN;
      ofproto->vlan_bitmap = NULL;
      ofproto->vlans_changed = false;
      ofproto->min_mtu = INT_MAX;
  
      error = ofproto->ofproto_class->construct(ofproto);
      if (error) {
          VLOG_ERR("failed to open datapath %s: %s",
                   datapath_name, strerror(error));
          ofproto_destroy__(ofproto);
          return error;
      }
  
      assert(ofproto->n_tables);
  
      ofproto->datapath_id = pick_datapath_id(ofproto);
      init_ports(ofproto);
  
      *ofprotop = ofproto;
      return 0;
  }
  
  void
  ofproto_init_tables(struct ofproto *ofproto, int n_tables)
  {
      struct oftable *table;
  
      assert(!ofproto->n_tables);
      assert(n_tables >= 1 && n_tables <= 255);
  
      ofproto->n_tables = n_tables;
      ofproto->tables = xmalloc(n_tables * sizeof *ofproto->tables);
      OFPROTO_FOR_EACH_TABLE (table, ofproto) {
          oftable_init(table);
      }
  }
  
  uint64_t
  ofproto_get_datapath_id(const struct ofproto *ofproto)
  {
      return ofproto->datapath_id;
  }
  
  void
  ofproto_set_datapath_id(struct ofproto *p, uint64_t datapath_id)
  {
      uint64_t old_dpid = p->datapath_id;
      p->datapath_id = datapath_id ? datapath_id : pick_datapath_id(p);
      if (p->datapath_id != old_dpid) {
          /* Force all active connections to reconnect, since there is no way to
           * notify a controller that the datapath ID has changed. */
          ofproto_reconnect_controllers(p);
      }
  }
  
  void
  ofproto_set_controllers(struct ofproto *p,
                          const struct ofproto_controller *controllers,
                          size_t n_controllers)
  {
      connmgr_set_controllers(p->connmgr, controllers, n_controllers);
  }
  
  void
  ofproto_set_fail_mode(struct ofproto *p, enum ofproto_fail_mode fail_mode)
  {
      connmgr_set_fail_mode(p->connmgr, fail_mode);
  }
  
  /* Drops the connections between 'ofproto' and all of its controllers, forcing
   * them to reconnect. */
  void
  ofproto_reconnect_controllers(struct ofproto *ofproto)
  {
      connmgr_reconnect(ofproto->connmgr);
  }
  
  /* Sets the 'n' TCP port addresses in 'extras' as ones to which 'ofproto''s
   * in-band control should guarantee access, in the same way that in-band
   * control guarantees access to OpenFlow controllers. */
  void
  ofproto_set_extra_in_band_remotes(struct ofproto *ofproto,
                                    const struct sockaddr_in *extras, size_t n)
  {
      connmgr_set_extra_in_band_remotes(ofproto->connmgr, extras, n);
  }
  
  /* Sets the OpenFlow queue used by flows set up by in-band control on
   * 'ofproto' to 'queue_id'.  If 'queue_id' is negative, then in-band control
   * flows will use the default queue. */
  void
  ofproto_set_in_band_queue(struct ofproto *ofproto, int queue_id)
  {
      connmgr_set_in_band_queue(ofproto->connmgr, queue_id);
  }
  
  /* Sets the number of flows at which eviction from the kernel flow table
   * will occur. */
  void
  ofproto_set_flow_eviction_threshold(struct ofproto *ofproto, unsigned threshold)
  {
      if (threshold < OFPROTO_FLOW_EVICTION_THRESHOLD_MIN) {
          ofproto->flow_eviction_threshold = OFPROTO_FLOW_EVICTION_THRESHOLD_MIN;
      } else {
          ofproto->flow_eviction_threshold = threshold;
      }
  }
  
  /* If forward_bpdu is true, the NORMAL action will forward frames with
   * reserved (e.g. STP) destination Ethernet addresses. if forward_bpdu is false,
   * the NORMAL action will drop these frames. */
  void
  ofproto_set_forward_bpdu(struct ofproto *ofproto, bool forward_bpdu)
  {
      bool old_val = ofproto->forward_bpdu;
      ofproto->forward_bpdu = forward_bpdu;
      if (old_val != ofproto->forward_bpdu) {
          if (ofproto->ofproto_class->forward_bpdu_changed) {
              ofproto->ofproto_class->forward_bpdu_changed(ofproto);
          }
      }
  }
  
  /* Sets the MAC aging timeout for the OFPP_NORMAL action on 'ofproto' to
   * 'idle_time', in seconds. */
  void
  ofproto_set_mac_idle_time(struct ofproto *ofproto, unsigned idle_time)
  {
      if (ofproto->ofproto_class->set_mac_idle_time) {
          ofproto->ofproto_class->set_mac_idle_time(ofproto, idle_time);
      }
  }
  
  void
  ofproto_set_desc(struct ofproto *p,
                   const char *mfr_desc, const char *hw_desc,
                   const char *sw_desc, const char *serial_desc,
                   const char *dp_desc)
  {
      struct ofp_desc_stats *ods;
  
      if (mfr_desc) {
          if (strlen(mfr_desc) >= sizeof ods->mfr_desc) {
              VLOG_WARN("%s: truncating mfr_desc, must be less than %zu bytes",
                        p->name, sizeof ods->mfr_desc);
          }
          free(p->mfr_desc);
          p->mfr_desc = xstrdup(mfr_desc);
      }
      if (hw_desc) {
          if (strlen(hw_desc) >= sizeof ods->hw_desc) {
              VLOG_WARN("%s: truncating hw_desc, must be less than %zu bytes",
                        p->name, sizeof ods->hw_desc);
          }
          free(p->hw_desc);
          p->hw_desc = xstrdup(hw_desc);
      }
      if (sw_desc) {
          if (strlen(sw_desc) >= sizeof ods->sw_desc) {
              VLOG_WARN("%s: truncating sw_desc, must be less than %zu bytes",
                        p->name, sizeof ods->sw_desc);
          }
          free(p->sw_desc);
          p->sw_desc = xstrdup(sw_desc);
      }
      if (serial_desc) {
          if (strlen(serial_desc) >= sizeof ods->serial_num) {
              VLOG_WARN("%s: truncating serial_desc, must be less than %zu "
                        "bytes", p->name, sizeof ods->serial_num);
          }
          free(p->serial_desc);
          p->serial_desc = xstrdup(serial_desc);
      }
      if (dp_desc) {
          if (strlen(dp_desc) >= sizeof ods->dp_desc) {
              VLOG_WARN("%s: truncating dp_desc, must be less than %zu bytes",
                        p->name, sizeof ods->dp_desc);
          }
          free(p->dp_desc);
          p->dp_desc = xstrdup(dp_desc);
      }
  }
  
  int
  ofproto_set_snoops(struct ofproto *ofproto, const struct sset *snoops)
  {
      return connmgr_set_snoops(ofproto->connmgr, snoops);
  }
  
  int
  ofproto_set_netflow(struct ofproto *ofproto,
                      const struct netflow_options *nf_options)
  {
      if (nf_options && sset_is_empty(&nf_options->collectors)) {
          nf_options = NULL;
      }
  
      if (ofproto->ofproto_class->set_netflow) {
          return ofproto->ofproto_class->set_netflow(ofproto, nf_options);
      } else {
          return nf_options ? EOPNOTSUPP : 0;
      }
  }
  
  int
  ofproto_set_sflow(struct ofproto *ofproto,
                    const struct ofproto_sflow_options *oso)
  {
      if (oso && sset_is_empty(&oso->targets)) {
          oso = NULL;
      }
  
      if (ofproto->ofproto_class->set_sflow) {
          return ofproto->ofproto_class->set_sflow(ofproto, oso);
      } else {
          return oso ? EOPNOTSUPP : 0;
      }
  }
  
  /* Spanning Tree Protocol (STP) configuration. */
  
  /* Configures STP on 'ofproto' using the settings defined in 's'.  If
   * 's' is NULL, disables STP.
   *
   * Returns 0 if successful, otherwise a positive errno value. */
  int
  ofproto_set_stp(struct ofproto *ofproto,
                  const struct ofproto_stp_settings *s)
  {
      return (ofproto->ofproto_class->set_stp
              ? ofproto->ofproto_class->set_stp(ofproto, s)
              : EOPNOTSUPP);
  }
  
  /* Retrieves STP status of 'ofproto' and stores it in 's'.  If the
   * 'enabled' member of 's' is false, then the other members are not
   * meaningful.
   *
   * Returns 0 if successful, otherwise a positive errno value. */
  int
  ofproto_get_stp_status(struct ofproto *ofproto,
                         struct ofproto_stp_status *s)
  {
      return (ofproto->ofproto_class->get_stp_status
              ? ofproto->ofproto_class->get_stp_status(ofproto, s)
              : EOPNOTSUPP);
  }
  
  /* Configures STP on 'ofp_port' of 'ofproto' using the settings defined
   * in 's'.  The caller is responsible for assigning STP port numbers
   * (using the 'port_num' member in the range of 1 through 255, inclusive)
   * and ensuring there are no duplicates.  If the 's' is NULL, then STP
   * is disabled on the port.
   *
   * Returns 0 if successful, otherwise a positive errno value.*/
  int
  ofproto_port_set_stp(struct ofproto *ofproto, uint16_t ofp_port,
                       const struct ofproto_port_stp_settings *s)
  {
      struct ofport *ofport = ofproto_get_port(ofproto, ofp_port);
      if (!ofport) {
          VLOG_WARN("%s: cannot configure STP on nonexistent port %"PRIu16,
                    ofproto->name, ofp_port);
          return ENODEV;
      }
  
      return (ofproto->ofproto_class->set_stp_port
              ? ofproto->ofproto_class->set_stp_port(ofport, s)
              : EOPNOTSUPP);
  }
  
  /* Retrieves STP port status of 'ofp_port' on 'ofproto' and stores it in
   * 's'.  If the 'enabled' member in 's' is false, then the other members
   * are not meaningful.
   *
   * Returns 0 if successful, otherwise a positive errno value.*/
  int
  ofproto_port_get_stp_status(struct ofproto *ofproto, uint16_t ofp_port,
                              struct ofproto_port_stp_status *s)
  {
      struct ofport *ofport = ofproto_get_port(ofproto, ofp_port);
      if (!ofport) {
          VLOG_WARN_RL(&rl, "%s: cannot get STP status on nonexistent "
                       "port %"PRIu16, ofproto->name, ofp_port);
          return ENODEV;
      }
  
      return (ofproto->ofproto_class->get_stp_port_status
              ? ofproto->ofproto_class->get_stp_port_status(ofport, s)
              : EOPNOTSUPP);
  }
  
  /* Queue DSCP configuration. */
  
  /* Registers meta-data associated with the 'n_qdscp' Qualities of Service
   * 'queues' attached to 'ofport'.  This data is not intended to be sufficient
   * to implement QoS.  Instead, it is used to implement features which require
   * knowledge of what queues exist on a port, and some basic information about
   * them.
   *
   * Returns 0 if successful, otherwise a positive errno value. */
  int
  ofproto_port_set_queues(struct ofproto *ofproto, uint16_t ofp_port,
                          const struct ofproto_port_queue *queues,
                          size_t n_queues)
  {
      struct ofport *ofport = ofproto_get_port(ofproto, ofp_port);
  
      if (!ofport) {
          VLOG_WARN("%s: cannot set queues on nonexistent port %"PRIu16,
                    ofproto->name, ofp_port);
          return ENODEV;
      }
  
      return (ofproto->ofproto_class->set_queues
              ? ofproto->ofproto_class->set_queues(ofport, queues, n_queues)
              : EOPNOTSUPP);
  }
  
  /* Connectivity Fault Management configuration. */
  
  /* Clears the CFM configuration from 'ofp_port' on 'ofproto'. */
  void
  ofproto_port_clear_cfm(struct ofproto *ofproto, uint16_t ofp_port)
  {
      struct ofport *ofport = ofproto_get_port(ofproto, ofp_port);
      if (ofport && ofproto->ofproto_class->set_cfm) {
          ofproto->ofproto_class->set_cfm(ofport, NULL);
      }
  }
  
  /* Configures connectivity fault management on 'ofp_port' in 'ofproto'.  Takes
   * basic configuration from the configuration members in 'cfm', and the remote
   * maintenance point ID from  remote_mpid.  Ignores the statistics members of
   * 'cfm'.
   *
   * This function has no effect if 'ofproto' does not have a port 'ofp_port'. */
  void
  ofproto_port_set_cfm(struct ofproto *ofproto, uint16_t ofp_port,
                       const struct cfm_settings *s)
  {
      struct ofport *ofport;
      int error;
  
      ofport = ofproto_get_port(ofproto, ofp_port);
      if (!ofport) {
          VLOG_WARN("%s: cannot configure CFM on nonexistent port %"PRIu16,
                    ofproto->name, ofp_port);
          return;
      }
  
      /* XXX: For configuration simplicity, we only support one remote_mpid
       * outside of the CFM module.  It's not clear if this is the correct long
       * term solution or not. */
      error = (ofproto->ofproto_class->set_cfm
               ? ofproto->ofproto_class->set_cfm(ofport, s)
               : EOPNOTSUPP);
      if (error) {
          VLOG_WARN("%s: CFM configuration on port %"PRIu16" (%s) failed (%s)",
                    ofproto->name, ofp_port, netdev_get_name(ofport->netdev),
                    strerror(error));
      }
  }
  
  /* Checks the status of LACP negotiation for 'ofp_port' within ofproto.
   * Returns 1 if LACP partner information for 'ofp_port' is up-to-date,
   * 0 if LACP partner information is not current (generally indicating a
   * connectivity problem), or -1 if LACP is not enabled on 'ofp_port'. */
  int
  ofproto_port_is_lacp_current(struct ofproto *ofproto, uint16_t ofp_port)
  {
      struct ofport *ofport = ofproto_get_port(ofproto, ofp_port);
      return (ofport && ofproto->ofproto_class->port_is_lacp_current
              ? ofproto->ofproto_class->port_is_lacp_current(ofport)
              : -1);
  }
  
  /* Bundles. */
  
  /* Registers a "bundle" associated with client data pointer 'aux' in 'ofproto'.
   * A bundle is the same concept as a Port in OVSDB, that is, it consists of one
   * or more "slave" devices (Interfaces, in OVSDB) along with a VLAN
   * configuration plus, if there is more than one slave, a bonding
   * configuration.
   *
   * If 'aux' is already registered then this function updates its configuration
   * to 's'.  Otherwise, this function registers a new bundle.
   *
   * Bundles only affect the NXAST_AUTOPATH action and output to the OFPP_NORMAL
   * port. */
  int
  ofproto_bundle_register(struct ofproto *ofproto, void *aux,
                          const struct ofproto_bundle_settings *s)
  {
      return (ofproto->ofproto_class->bundle_set
              ? ofproto->ofproto_class->bundle_set(ofproto, aux, s)
              : EOPNOTSUPP);
  }
  
  /* Unregisters the bundle registered on 'ofproto' with auxiliary data 'aux'.
   * If no such bundle has been registered, this has no effect. */
  int
  ofproto_bundle_unregister(struct ofproto *ofproto, void *aux)
  {
      return ofproto_bundle_register(ofproto, aux, NULL);
  }
  
  
  /* Registers a mirror associated with client data pointer 'aux' in 'ofproto'.
   * If 'aux' is already registered then this function updates its configuration
   * to 's'.  Otherwise, this function registers a new mirror. */
  int
  ofproto_mirror_register(struct ofproto *ofproto, void *aux,
                          const struct ofproto_mirror_settings *s)
  {
      return (ofproto->ofproto_class->mirror_set
              ? ofproto->ofproto_class->mirror_set(ofproto, aux, s)
              : EOPNOTSUPP);
  }
  
  /* Unregisters the mirror registered on 'ofproto' with auxiliary data 'aux'.
   * If no mirror has been registered, this has no effect. */
  int
  ofproto_mirror_unregister(struct ofproto *ofproto, void *aux)
  {
      return ofproto_mirror_register(ofproto, aux, NULL);
  }
  
  /* Retrieves statistics from mirror associated with client data pointer
   * 'aux' in 'ofproto'.  Stores packet and byte counts in 'packets' and
   * 'bytes', respectively.  If a particular counters is not supported,
   * the appropriate argument is set to UINT64_MAX. */
  int
  ofproto_mirror_get_stats(struct ofproto *ofproto, void *aux,
                           uint64_t *packets, uint64_t *bytes)
  {
      if (!ofproto->ofproto_class->mirror_get_stats) {
          *packets = *bytes = UINT64_MAX;
          return EOPNOTSUPP;
      }
  
      return ofproto->ofproto_class->mirror_get_stats(ofproto, aux,
                                                      packets, bytes);
  }
  
  /* Configures the VLANs whose bits are set to 1 in 'flood_vlans' as VLANs on
   * which all packets are flooded, instead of using MAC learning.  If
   * 'flood_vlans' is NULL, then MAC learning applies to all VLANs.
   *
   * Flood VLANs affect only the treatment of packets output to the OFPP_NORMAL
   * port. */
  int
  ofproto_set_flood_vlans(struct ofproto *ofproto, unsigned long *flood_vlans)
  {
      return (ofproto->ofproto_class->set_flood_vlans
              ? ofproto->ofproto_class->set_flood_vlans(ofproto, flood_vlans)
              : EOPNOTSUPP);
  }
  
  /* Returns true if 'aux' is a registered bundle that is currently in use as the
   * output for a mirror. */
  bool
  ofproto_is_mirror_output_bundle(const struct ofproto *ofproto, void *aux)
  {
      return (ofproto->ofproto_class->is_mirror_output_bundle
              ? ofproto->ofproto_class->is_mirror_output_bundle(ofproto, aux)
              : false);
  }
  
  /* Configuration of OpenFlow tables. */
  
  /* Returns the number of OpenFlow tables in 'ofproto'. */
  int
  ofproto_get_n_tables(const struct ofproto *ofproto)
  {
      return ofproto->n_tables;
  }
  
  /* Configures the OpenFlow table in 'ofproto' with id 'table_id' with the
   * settings from 's'.  'table_id' must be in the range 0 through the number of
   * OpenFlow tables in 'ofproto' minus 1, inclusive.
   *
   * For read-only tables, only the name may be configured. */
  void
  ofproto_configure_table(struct ofproto *ofproto, int table_id,
                          const struct ofproto_table_settings *s)
  {
      struct oftable *table;
  
      assert(table_id >= 0 && table_id < ofproto->n_tables);
      table = &ofproto->tables[table_id];
  
      oftable_set_name(table, s->name);
  
      if (table->flags & OFTABLE_READONLY) {
          return;
      }
  
      if (s->groups) {
          oftable_enable_eviction(table, s->groups, s->n_groups);
      } else {
          oftable_disable_eviction(table);
      }
  
      table->max_flows = s->max_flows;
      if (classifier_count(&table->cls) > table->max_flows
          && table->eviction_fields) {
          /* 'table' contains more flows than allowed.  We might not be able to
           * evict them right away because of the asynchronous nature of flow
           * table changes.  Schedule eviction for later. */
          switch (ofproto->state) {
          case S_OPENFLOW:
              ofproto->state = S_EVICT;
              break;
          case S_EVICT:
          case S_FLUSH:
              /* We're already deleting flows, nothing more to do. */
              break;
          }
      }
  }
  
  bool
  ofproto_has_snoops(const struct ofproto *ofproto)
  {
      return connmgr_has_snoops(ofproto->connmgr);
  }
  
  void
  ofproto_get_snoops(const struct ofproto *ofproto, struct sset *snoops)
  {
      connmgr_get_snoops(ofproto->connmgr, snoops);
  }
  
  static void
  ofproto_flush__(struct ofproto *ofproto)
  {
      struct ofopgroup *group;
      struct oftable *table;
  
      if (ofproto->ofproto_class->flush) {
          ofproto->ofproto_class->flush(ofproto);
      }
  
      group = ofopgroup_create_unattached(ofproto);
      OFPROTO_FOR_EACH_TABLE (table, ofproto) {
          struct rule *rule, *next_rule;
          struct cls_cursor cursor;
  
          if (table->flags & OFTABLE_HIDDEN) {
              continue;
          }
  
          cls_cursor_init(&cursor, &table->cls, NULL);
          CLS_CURSOR_FOR_EACH_SAFE (rule, next_rule, cr, &cursor) {
              if (!rule->pending) {
                  ofoperation_create(group, rule, OFOPERATION_DELETE,
                                     OFPRR_DELETE);
                  oftable_remove_rule(rule);
                  ofproto->ofproto_class->rule_destruct(rule);
              }
          }
      }
      ofopgroup_submit(group);
  }
  
  static void
  ofproto_destroy__(struct ofproto *ofproto)
  {
      struct oftable *table;
  
      assert(list_is_empty(&ofproto->pending));
      assert(!ofproto->n_pending);
  
      connmgr_destroy(ofproto->connmgr);
  
      hmap_remove(&all_ofprotos, &ofproto->hmap_node);
      free(ofproto->name);
      free(ofproto->type);
      free(ofproto->mfr_desc);
      free(ofproto->hw_desc);
      free(ofproto->sw_desc);
      free(ofproto->serial_desc);
      free(ofproto->dp_desc);
      hmap_destroy(&ofproto->ports);
      shash_destroy(&ofproto->port_by_name);
  
      OFPROTO_FOR_EACH_TABLE (table, ofproto) {
          oftable_destroy(table);
      }
      free(ofproto->tables);
  
      hmap_destroy(&ofproto->deletions);
  
      free(ofproto->vlan_bitmap);
  
      ofproto->ofproto_class->dealloc(ofproto);
  }
  
  void
  ofproto_destroy(struct ofproto *p)
  {
      struct ofport *ofport, *next_ofport;
  
      if (!p) {
          return;
      }
  
      ofproto_flush__(p);
      HMAP_FOR_EACH_SAFE (ofport, next_ofport, hmap_node, &p->ports) {
          ofport_destroy(ofport);
      }
  
      p->ofproto_class->destruct(p);
      ofproto_destroy__(p);
  }
  
  /* Destroys the datapath with the respective 'name' and 'type'.  With the Linux
   * kernel datapath, for example, this destroys the datapath in the kernel, and
   * with the netdev-based datapath, it tears down the data structures that
   * represent the datapath.
   *
   * The datapath should not be currently open as an ofproto. */
  int
  ofproto_delete(const char *name, const char *type)
  {
      const struct ofproto_class *class = ofproto_class_find__(type);
      return (!class ? EAFNOSUPPORT
              : !class->del ? EACCES
              : class->del(type, name));
  }
  
  static void
  process_port_change(struct ofproto *ofproto, int error, char *devname)
  {
      if (error == ENOBUFS) {
          reinit_ports(ofproto);
      } else if (!error) {
          update_port(ofproto, devname);
          free(devname);
      }
  }
  
  int
  ofproto_run(struct ofproto *p)
  {
      struct sset changed_netdevs;
      const char *changed_netdev;
      struct ofport *ofport;
      int error;
  
      error = p->ofproto_class->run(p);
      if (error && error != EAGAIN) {
          VLOG_ERR_RL(&rl, "%s: run failed (%s)", p->name, strerror(error));
      }
  
      if (p->ofproto_class->port_poll) {
          char *devname;
  
          while ((error = p->ofproto_class->port_poll(p, &devname)) != EAGAIN) {
              process_port_change(p, error, devname);
          }
      }
  
      /* Update OpenFlow port status for any port whose netdev has changed.
       *
       * Refreshing a given 'ofport' can cause an arbitrary ofport to be
       * destroyed, so it's not safe to update ports directly from the
       * HMAP_FOR_EACH loop, or even to use HMAP_FOR_EACH_SAFE.  Instead, we
       * need this two-phase approach. */
      sset_init(&changed_netdevs);
      HMAP_FOR_EACH (ofport, hmap_node, &p->ports) {
          unsigned int change_seq = netdev_change_seq(ofport->netdev);
          if (ofport->change_seq != change_seq) {
              ofport->change_seq = change_seq;
              sset_add(&changed_netdevs, netdev_get_name(ofport->netdev));
          }
      }
      SSET_FOR_EACH (changed_netdev, &changed_netdevs) {
          update_port(p, changed_netdev);
      }
      sset_destroy(&changed_netdevs);
  
      switch (p->state) {
      case S_OPENFLOW:
          connmgr_run(p->connmgr, handle_openflow);
          break;
  
      case S_EVICT:
          connmgr_run(p->connmgr, NULL);
          ofproto_evict(p);
          if (list_is_empty(&p->pending) && hmap_is_empty(&p->deletions)) {
              p->state = S_OPENFLOW;
          }
          break;
  
      case S_FLUSH:
          connmgr_run(p->connmgr, NULL);
          ofproto_flush__(p);
          if (list_is_empty(&p->pending) && hmap_is_empty(&p->deletions)) {
              connmgr_flushed(p->connmgr);
              p->state = S_OPENFLOW;
          }
          break;
  
      default:
          NOT_REACHED();
      }
  
      if (time_msec() >= p->next_op_report) {
          long long int ago = (time_msec() - p->first_op) / 1000;
          long long int interval = (p->last_op - p->first_op) / 1000;
          struct ds s;
  
          ds_init(&s);
          ds_put_format(&s, "%d flow_mods ",
                        p->n_add + p->n_delete + p->n_modify);
          if (interval == ago) {
              ds_put_format(&s, "in the last %lld s", ago);
          } else if (interval) {
              ds_put_format(&s, "in the %lld s starting %lld s ago",
                            interval, ago);
          } else {
              ds_put_format(&s, "%lld s ago", ago);
          }
  
          ds_put_cstr(&s, " (");
          if (p->n_add) {
              ds_put_format(&s, "%d adds, ", p->n_add);
          }
          if (p->n_delete) {
              ds_put_format(&s, "%d deletes, ", p->n_delete);
          }
          if (p->n_modify) {
              ds_put_format(&s, "%d modifications, ", p->n_modify);
          }
          s.length -= 2;
          ds_put_char(&s, ')');
  
          VLOG_INFO("%s: %s", p->name, ds_cstr(&s));
          ds_destroy(&s);
  
          p->n_add = p->n_delete = p->n_modify = 0;
          p->next_op_report = LLONG_MAX;
      }
  
      return error;
  }
  
  /* Performs periodic activity required by 'ofproto' that needs to be done
   * with the least possible latency.
   *
   * It makes sense to call this function a couple of times per poll loop, to
   * provide a significant performance boost on some benchmarks with the
   * ofproto-dpif implementation. */
  int
  ofproto_run_fast(struct ofproto *p)
  {
      int error;
  
      error = p->ofproto_class->run_fast ? p->ofproto_class->run_fast(p) : 0;
      if (error && error != EAGAIN) {
          VLOG_ERR_RL(&rl, "%s: fastpath run failed (%s)",
                      p->name, strerror(error));
      }
      return error;
  }
  
  void
  ofproto_wait(struct ofproto *p)
  {
      struct ofport *ofport;
  
      p->ofproto_class->wait(p);
      if (p->ofproto_class->port_poll_wait) {
          p->ofproto_class->port_poll_wait(p);
      }
  
      HMAP_FOR_EACH (ofport, hmap_node, &p->ports) {
          if (ofport->change_seq != netdev_change_seq(ofport->netdev)) {
              poll_immediate_wake();
          }
      }
  
      switch (p->state) {
      case S_OPENFLOW:
          connmgr_wait(p->connmgr, true);
          break;
  
      case S_EVICT:
      case S_FLUSH:
          connmgr_wait(p->connmgr, false);
          if (list_is_empty(&p->pending) && hmap_is_empty(&p->deletions)) {
              poll_immediate_wake();
          }
          break;
      }
  }
  
  bool
  ofproto_is_alive(const struct ofproto *p)
  {
      return connmgr_has_controllers(p->connmgr);
  }
  
  /* Adds some memory usage statistics for 'ofproto' into 'usage', for use with
   * memory_report(). */
  void
  ofproto_get_memory_usage(const struct ofproto *ofproto, struct simap *usage)
  {
      const struct oftable *table;
      unsigned int n_rules;
  
      simap_increase(usage, "ports", hmap_count(&ofproto->ports));
      simap_increase(usage, "ops",
                     ofproto->n_pending + hmap_count(&ofproto->deletions));
  
      n_rules = 0;
      OFPROTO_FOR_EACH_TABLE (table, ofproto) {
          n_rules += classifier_count(&table->cls);
      }
      simap_increase(usage, "rules", n_rules);
  
      if (ofproto->ofproto_class->get_memory_usage) {
          ofproto->ofproto_class->get_memory_usage(ofproto, usage);
      }
  
      connmgr_get_memory_usage(ofproto->connmgr, usage);
  }
  
  void
  ofproto_get_ofproto_controller_info(const struct ofproto *ofproto,
                                      struct shash *info)
  {
      connmgr_get_controller_info(ofproto->connmgr, info);
  }
  
  void
  ofproto_free_ofproto_controller_info(struct shash *info)
  {
      connmgr_free_controller_info(info);
  }
  
  /* Makes a deep copy of 'old' into 'port'. */
  void
  ofproto_port_clone(struct ofproto_port *port, const struct ofproto_port *old)
  {
      port->name = xstrdup(old->name);
      port->type = xstrdup(old->type);
      port->ofp_port = old->ofp_port;
  }
  
  /* Frees memory allocated to members of 'ofproto_port'.
   *
   * Do not call this function on an ofproto_port obtained from
   * ofproto_port_dump_next(): that function retains ownership of the data in the
   * ofproto_port. */
  void
  ofproto_port_destroy(struct ofproto_port *ofproto_port)
  {
      free(ofproto_port->name);
      free(ofproto_port->type);
  }
  
  /* Initializes 'dump' to begin dumping the ports in an ofproto.
   *
   * This function provides no status indication.  An error status for the entire
   * dump operation is provided when it is completed by calling
   * ofproto_port_dump_done().
   */
  void
  ofproto_port_dump_start(struct ofproto_port_dump *dump,
                          const struct ofproto *ofproto)
  {
      dump->ofproto = ofproto;
      dump->error = ofproto->ofproto_class->port_dump_start(ofproto,
                                                            &dump->state);
  }
  
  /* Attempts to retrieve another port from 'dump', which must have been created
   * with ofproto_port_dump_start().  On success, stores a new ofproto_port into
   * 'port' and returns true.  On failure, returns false.
   *
   * Failure might indicate an actual error or merely that the last port has been
   * dumped.  An error status for the entire dump operation is provided when it
   * is completed by calling ofproto_port_dump_done().
   *
   * The ofproto owns the data stored in 'port'.  It will remain valid until at
   * least the next time 'dump' is passed to ofproto_port_dump_next() or
   * ofproto_port_dump_done(). */
  bool
  ofproto_port_dump_next(struct ofproto_port_dump *dump,
                         struct ofproto_port *port)
  {
      const struct ofproto *ofproto = dump->ofproto;
  
      if (dump->error) {
          return false;
      }
  
      dump->error = ofproto->ofproto_class->port_dump_next(ofproto, dump->state,
                                                           port);
      if (dump->error) {
          ofproto->ofproto_class->port_dump_done(ofproto, dump->state);
          return false;
      }
      return true;
  }
  
  /* Completes port table dump operation 'dump', which must have been created
   * with ofproto_port_dump_start().  Returns 0 if the dump operation was
   * error-free, otherwise a positive errno value describing the problem. */
  int
  ofproto_port_dump_done(struct ofproto_port_dump *dump)
  {
      const struct ofproto *ofproto = dump->ofproto;
      if (!dump->error) {
          dump->error = ofproto->ofproto_class->port_dump_done(ofproto,
                                                               dump->state);
      }
      return dump->error == EOF ? 0 : dump->error;
  }
  
  /* Attempts to add 'netdev' as a port on 'ofproto'.  If successful, returns 0
   * and sets '*ofp_portp' to the new port's OpenFlow port number (if 'ofp_portp'
   * is non-null).  On failure, returns a positive errno value and sets
   * '*ofp_portp' to OFPP_NONE (if 'ofp_portp' is non-null). */
  int
  ofproto_port_add(struct ofproto *ofproto, struct netdev *netdev,
                   uint16_t *ofp_portp)
  {
      uint16_t ofp_port;
      int error;
  
      error = ofproto->ofproto_class->port_add(ofproto, netdev, &ofp_port);
      if (!error) {
          update_port(ofproto, netdev_get_name(netdev));
      }
      if (ofp_portp) {
          *ofp_portp = error ? OFPP_NONE : ofp_port;
      }
      return error;
  }
  
  /* Looks up a port named 'devname' in 'ofproto'.  On success, returns 0 and
   * initializes '*port' appropriately; on failure, returns a positive errno
   * value.
   *
   * The caller owns the data in 'ofproto_port' and must free it with
   * ofproto_port_destroy() when it is no longer needed. */
  int
  ofproto_port_query_by_name(const struct ofproto *ofproto, const char *devname,
                             struct ofproto_port *port)
  {
      int error;
  
      error = ofproto->ofproto_class->port_query_by_name(ofproto, devname, port);
      if (error) {
          memset(port, 0, sizeof *port);
      }
      return error;
  }
  
  /* Deletes port number 'ofp_port' from the datapath for 'ofproto'.
   * Returns 0 if successful, otherwise a positive errno. */
  int
  ofproto_port_del(struct ofproto *ofproto, uint16_t ofp_port)
  {
      struct ofport *ofport = ofproto_get_port(ofproto, ofp_port);
      const char *name = ofport ? netdev_get_name(ofport->netdev) : "<unknown>";
      int error;
  
      error = ofproto->ofproto_class->port_del(ofproto, ofp_port);
      if (!error && ofport) {
          /* 'name' is the netdev's name and update_port() is going to close the
           * netdev.  Just in case update_port() refers to 'name' after it
           * destroys 'ofport', make a copy of it around the update_port()
           * call. */
          char *devname = xstrdup(name);
          update_port(ofproto, devname);
          free(devname);
      }
      return error;
  }
  
  /* Adds a flow to OpenFlow flow table 0 in 'p' that matches 'cls_rule' and
   * performs the 'n_actions' actions in 'actions'.  The new flow will not
   * timeout.
   *
   * If cls_rule->priority is in the range of priorities supported by OpenFlow
   * (0...65535, inclusive) then the flow will be visible to OpenFlow
   * controllers; otherwise, it will be hidden.
   *
   * The caller retains ownership of 'cls_rule' and 'ofpacts'.
   *
   * This is a helper function for in-band control and fail-open. */
  void
  ofproto_add_flow(struct ofproto *ofproto, const struct cls_rule *cls_rule,
                   const struct ofpact *ofpacts, size_t ofpacts_len)
  {
      const struct rule *rule;
  
      rule = rule_from_cls_rule(classifier_find_rule_exactly(
                                      &ofproto->tables[0].cls, cls_rule));
      if (!rule || !ofpacts_equal(rule->ofpacts, rule->ofpacts_len,
                                  ofpacts, ofpacts_len)) {
          struct ofputil_flow_mod fm;
  
          memset(&fm, 0, sizeof fm);
          fm.cr = *cls_rule;
          fm.buffer_id = UINT32_MAX;
          fm.ofpacts = xmemdup(ofpacts, ofpacts_len);
          fm.ofpacts_len = ofpacts_len;
          add_flow(ofproto, NULL, &fm, NULL);
          free(fm.ofpacts);
      }
  }
  
  /* Executes the flow modification specified in 'fm'.  Returns 0 on success, an
   * OFPERR_* OpenFlow error code on failure, or OFPROTO_POSTPONE if the
   * operation cannot be initiated now but may be retried later.
   *
   * This is a helper function for in-band control and fail-open. */
  int
  ofproto_flow_mod(struct ofproto *ofproto, const struct ofputil_flow_mod *fm)
  {
      return handle_flow_mod__(ofproto, NULL, fm, NULL);
  }
  
  /* Searches for a rule with matching criteria exactly equal to 'target' in
   * ofproto's table 0 and, if it finds one, deletes it.
   *
   * This is a helper function for in-band control and fail-open. */
  bool
  ofproto_delete_flow(struct ofproto *ofproto, const struct cls_rule *target)
  {
      struct rule *rule;
  
      rule = rule_from_cls_rule(classifier_find_rule_exactly(
                                    &ofproto->tables[0].cls, target));
      if (!rule) {
          /* No such rule -> success. */
          return true;
      } else if (rule->pending) {
          /* An operation on the rule is already pending -> failure.
           * Caller must retry later if it's important. */
          return false;
      } else {
          /* Initiate deletion -> success. */
          struct ofopgroup *group = ofopgroup_create_unattached(ofproto);
          ofoperation_create(group, rule, OFOPERATION_DELETE, OFPRR_DELETE);
          oftable_remove_rule(rule);
          ofproto->ofproto_class->rule_destruct(rule);
          ofopgroup_submit(group);
          return true;
      }
  
  }
  
  /* Starts the process of deleting all of the flows from all of ofproto's flow
   * tables and then reintroducing the flows required by in-band control and
   * fail-open.  The process will complete in a later call to ofproto_run(). */
  void
  ofproto_flush_flows(struct ofproto *ofproto)
  {
      COVERAGE_INC(ofproto_flush);
      ofproto->state = S_FLUSH;
  }
  
  static void
  reinit_ports(struct ofproto *p)
  {
      struct ofproto_port_dump dump;
      struct sset devnames;
      struct ofport *ofport;
      struct ofproto_port ofproto_port;
      const char *devname;
  
      COVERAGE_INC(ofproto_reinit_ports);
  
      sset_init(&devnames);
      HMAP_FOR_EACH (ofport, hmap_node, &p->ports) {
          sset_add(&devnames, netdev_get_name(ofport->netdev));
      }
      OFPROTO_PORT_FOR_EACH (&ofproto_port, &dump, p) {
          sset_add(&devnames, ofproto_port.name);
      }
  
      SSET_FOR_EACH (devname, &devnames) {
          update_port(p, devname);
      }
      sset_destroy(&devnames);
  }
  
  /* Opens and returns a netdev for 'ofproto_port' in 'ofproto', or a null
   * pointer if the netdev cannot be opened.  On success, also fills in
   * 'opp'.  */
  static struct netdev *
  ofport_open(const struct ofproto *ofproto,
              const struct ofproto_port *ofproto_port,
              struct ofputil_phy_port *pp)
  {
      enum netdev_flags flags;
      struct netdev *netdev;
      int error;
  
      error = netdev_open(ofproto_port->name, ofproto_port->type, &netdev);
      if (error) {
          VLOG_WARN_RL(&rl, "%s: ignoring port %s (%"PRIu16") because netdev %s "
                       "cannot be opened (%s)",
                       ofproto->name,
                       ofproto_port->name, ofproto_port->ofp_port,
                       ofproto_port->name, strerror(error));
          return NULL;
      }
  
      pp->port_no = ofproto_port->ofp_port;
      netdev_get_etheraddr(netdev, pp->hw_addr);
      ovs_strlcpy(pp->name, ofproto_port->name, sizeof pp->name);
      netdev_get_flags(netdev, &flags);
      pp->config = flags & NETDEV_UP ? 0 : OFPUTIL_PC_PORT_DOWN;
      pp->state = netdev_get_carrier(netdev) ? 0 : OFPUTIL_PS_LINK_DOWN;
      netdev_get_features(netdev, &pp->curr, &pp->advertised,
                          &pp->supported, &pp->peer);
      pp->curr_speed = netdev_features_to_bps(pp->curr);
      pp->max_speed = netdev_features_to_bps(pp->supported);
  
      return netdev;
  }
  
  /* Returns true if most fields of 'a' and 'b' are equal.  Differences in name,
   * port number, and 'config' bits other than OFPUTIL_PS_LINK_DOWN are
   * disregarded. */
  static bool
  ofport_equal(const struct ofputil_phy_port *a,
               const struct ofputil_phy_port *b)
  {
      return (eth_addr_equals(a->hw_addr, b->hw_addr)
              && a->state == b->state
              && !((a->config ^ b->config) & OFPUTIL_PC_PORT_DOWN)
              && a->curr == b->curr
              && a->advertised == b->advertised
              && a->supported == b->supported
              && a->peer == b->peer
              && a->curr_speed == b->curr_speed
              && a->max_speed == b->max_speed);
  }
  
  /* Adds an ofport to 'p' initialized based on the given 'netdev' and 'opp'.
   * The caller must ensure that 'p' does not have a conflicting ofport (that is,
   * one with the same name or port number). */
  static void
  ofport_install(struct ofproto *p,
                 struct netdev *netdev, const struct ofputil_phy_port *pp)
  {
      const char *netdev_name = netdev_get_name(netdev);
      struct ofport *ofport;
      int error;
  
      /* Create ofport. */
      ofport = p->ofproto_class->port_alloc();
      if (!ofport) {
          error = ENOMEM;
          goto error;
      }
      ofport->ofproto = p;
      ofport->netdev = netdev;
      ofport->change_seq = netdev_change_seq(netdev);
      ofport->pp = *pp;
      ofport->ofp_port = pp->port_no;
  
      /* Add port to 'p'. */
      hmap_insert(&p->ports, &ofport->hmap_node, hash_int(ofport->ofp_port, 0));
      shash_add(&p->port_by_name, netdev_name, ofport);
  
      update_mtu(p, ofport);
  
      /* Let the ofproto_class initialize its private data. */
      error = p->ofproto_class->port_construct(ofport);
      if (error) {
          goto error;
      }
      connmgr_send_port_status(p->connmgr, pp, OFPPR_ADD);
      return;
  
  error:
      VLOG_WARN_RL(&rl, "%s: could not add port %s (%s)",
                   p->name, netdev_name, strerror(error));
      if (ofport) {
          ofport_destroy__(ofport);
      } else {
          netdev_close(netdev);
      }
  }
  
  /* Removes 'ofport' from 'p' and destroys it. */
  static void
  ofport_remove(struct ofport *ofport)
  {
      connmgr_send_port_status(ofport->ofproto->connmgr, &ofport->pp,
                               OFPPR_DELETE);
      ofport_destroy(ofport);
  }
  
  /* If 'ofproto' contains an ofport named 'name', removes it from 'ofproto' and
   * destroys it. */
  static void
  ofport_remove_with_name(struct ofproto *ofproto, const char *name)
  {
      struct ofport *port = shash_find_data(&ofproto->port_by_name, name);
      if (port) {
          ofport_remove(port);
      }
  }
  
  /* Updates 'port' with new 'pp' description.
   *
   * Does not handle a name or port number change.  The caller must implement
   * such a change as a delete followed by an add.  */
  static void
  ofport_modified(struct ofport *port, struct ofputil_phy_port *pp)
  {
      memcpy(port->pp.hw_addr, pp->hw_addr, ETH_ADDR_LEN);
      port->pp.config = ((port->pp.config & ~OFPUTIL_PC_PORT_DOWN)
                          | (pp->config & OFPUTIL_PC_PORT_DOWN));
      port->pp.state = pp->state;
      port->pp.curr = pp->curr;
      port->pp.advertised = pp->advertised;
      port->pp.supported = pp->supported;
      port->pp.peer = pp->peer;
      port->pp.curr_speed = pp->curr_speed;
      port->pp.max_speed = pp->max_speed;
  
      connmgr_send_port_status(port->ofproto->connmgr, &port->pp, OFPPR_MODIFY);
  }
  
  /* Update OpenFlow 'state' in 'port' and notify controller. */
  void
  ofproto_port_set_state(struct ofport *port, enum ofputil_port_state state)
  {
      if (port->pp.state != state) {
          port->pp.state = state;
          connmgr_send_port_status(port->ofproto->connmgr, &port->pp,
                                   OFPPR_MODIFY);
      }
  }
  
  void
  ofproto_port_unregister(struct ofproto *ofproto, uint16_t ofp_port)
  {
      struct ofport *port = ofproto_get_port(ofproto, ofp_port);
      if (port) {
          if (port->ofproto->ofproto_class->set_realdev) {
              port->ofproto->ofproto_class->set_realdev(port, 0, 0);
          }
          if (port->ofproto->ofproto_class->set_stp_port) {
              port->ofproto->ofproto_class->set_stp_port(port, NULL);
          }
          if (port->ofproto->ofproto_class->set_cfm) {
              port->ofproto->ofproto_class->set_cfm(port, NULL);
          }
          if (port->ofproto->ofproto_class->bundle_remove) {
              port->ofproto->ofproto_class->bundle_remove(port);
          }
      }
  }
  
  static void
  ofport_destroy__(struct ofport *port)
  {
      struct ofproto *ofproto = port->ofproto;
      const char *name = netdev_get_name(port->netdev);
  
      hmap_remove(&ofproto->ports, &port->hmap_node);
      shash_delete(&ofproto->port_by_name,
                   shash_find(&ofproto->port_by_name, name));
  
      netdev_close(port->netdev);
      ofproto->ofproto_class->port_dealloc(port);
  }
  
  static void
  ofport_destroy(struct ofport *port)
  {
      if (port) {
          port->ofproto->ofproto_class->port_destruct(port);
          ofport_destroy__(port);
       }
  }
  
  struct ofport *
  ofproto_get_port(const struct ofproto *ofproto, uint16_t ofp_port)
  {
      struct ofport *port;
  
      HMAP_FOR_EACH_IN_BUCKET (port, hmap_node,
                               hash_int(ofp_port, 0), &ofproto->ports) {
          if (port->ofp_port == ofp_port) {
              return port;
          }
      }
      return NULL;
  }
  
  int
  ofproto_port_get_stats(const struct ofport *port, struct netdev_stats *stats)
  {
      struct ofproto *ofproto = port->ofproto;
      int error;
  
      if (ofproto->ofproto_class->port_get_stats) {
          error = ofproto->ofproto_class->port_get_stats(port, stats);
      } else {
          error = EOPNOTSUPP;
      }
  
      return error;
  }
  
  static void
  update_port(struct ofproto *ofproto, const char *name)
  {
      struct ofproto_port ofproto_port;
      struct ofputil_phy_port pp;
      struct netdev *netdev;
      struct ofport *port;
  
      COVERAGE_INC(ofproto_update_port);
  
      /* Fetch 'name''s location and properties from the datapath. */
      netdev = (!ofproto_port_query_by_name(ofproto, name, &ofproto_port)
                ? ofport_open(ofproto, &ofproto_port, &pp)
                : NULL);
      if (netdev) {
          port = ofproto_get_port(ofproto, ofproto_port.ofp_port);
          if (port && !strcmp(netdev_get_name(port->netdev), name)) {
              struct netdev *old_netdev = port->netdev;
  
              /* 'name' hasn't changed location.  Any properties changed? */
              if (!ofport_equal(&port->pp, &pp)) {
                  ofport_modified(port, &pp);
              }
  
              update_mtu(ofproto, port);
  
              /* Install the newly opened netdev in case it has changed.
               * Don't close the old netdev yet in case port_modified has to
               * remove a retained reference to it.*/
              port->netdev = netdev;
              port->change_seq = netdev_change_seq(netdev);
  
              if (port->ofproto->ofproto_class->port_modified) {
                  port->ofproto->ofproto_class->port_modified(port);
              }
  
              netdev_close(old_netdev);
          } else {
              /* If 'port' is nonnull then its name differs from 'name' and thus
               * we should delete it.  If we think there's a port named 'name'
               * then its port number must be wrong now so delete it too. */
              if (port) {
                  ofport_remove(port);
              }
              ofport_remove_with_name(ofproto, name);
              ofport_install(ofproto, netdev, &pp);
          }
      } else {
          /* Any port named 'name' is gone now. */
          ofport_remove_with_name(ofproto, name);
      }
      ofproto_port_destroy(&ofproto_port);
  }
  
  static int
  init_ports(struct ofproto *p)
  {
      struct ofproto_port_dump dump;
      struct ofproto_port ofproto_port;
  
      OFPROTO_PORT_FOR_EACH (&ofproto_port, &dump, p) {
          uint16_t ofp_port = ofproto_port.ofp_port;
          if (ofproto_get_port(p, ofp_port)) {
              VLOG_WARN_RL(&rl, "%s: ignoring duplicate port %"PRIu16" "
                           "in datapath", p->name, ofp_port);
          } else if (shash_find(&p->port_by_name, ofproto_port.name)) {
              VLOG_WARN_RL(&rl, "%s: ignoring duplicate device %s in datapath",
                           p->name, ofproto_port.name);
          } else {
              struct ofputil_phy_port pp;
              struct netdev *netdev;
  
              netdev = ofport_open(p, &ofproto_port, &pp);
              if (netdev) {
                  ofport_install(p, netdev, &pp);
              }
          }
      }
  
      return 0;
  }
  
  /* Find the minimum MTU of all non-datapath devices attached to 'p'.
   * Returns ETH_PAYLOAD_MAX or the minimum of the ports. */
  static int
  find_min_mtu(struct ofproto *p)
  {
      struct ofport *ofport;
      int mtu = 0;
  
      HMAP_FOR_EACH (ofport, hmap_node, &p->ports) {
          struct netdev *netdev = ofport->netdev;
          int dev_mtu;
  
          /* Skip any internal ports, since that's what we're trying to
           * set. */
          if (!strcmp(netdev_get_type(netdev), "internal")) {
              continue;
          }
  
          if (netdev_get_mtu(netdev, &dev_mtu)) {
              continue;
          }
          if (!mtu || dev_mtu < mtu) {
              mtu = dev_mtu;
          }
      }
  
      return mtu ? mtu: ETH_PAYLOAD_MAX;
  }
  
  /* Update MTU of all datapath devices on 'p' to the minimum of the
   * non-datapath ports in event of 'port' added or changed. */
  static void
  update_mtu(struct ofproto *p, struct ofport *port)
  {
      struct ofport *ofport;
      struct netdev *netdev = port->netdev;
      int dev_mtu, old_min;
  
      if (netdev_get_mtu(netdev, &dev_mtu)) {
          port->mtu = 0;
          return;
      }
      if (!strcmp(netdev_get_type(port->netdev), "internal")) {
          if (dev_mtu > p->min_mtu) {
             if (!netdev_set_mtu(port->netdev, p->min_mtu)) {
                 dev_mtu = p->min_mtu;
             }
          }
          port->mtu = dev_mtu;
          return;
      }
  
      /* For non-internal port find new min mtu. */
      old_min = p->min_mtu;
      port->mtu = dev_mtu;
      p->min_mtu = find_min_mtu(p);
      if (p->min_mtu == old_min) {
          return;
      }
  
      HMAP_FOR_EACH (ofport, hmap_node, &p->ports) {
          struct netdev *netdev = ofport->netdev;
  
          if (!strcmp(netdev_get_type(netdev), "internal")) {
              if (!netdev_set_mtu(netdev, p->min_mtu)) {
                  ofport->mtu = p->min_mtu;
              }
          }
      }
  }
  
  static void
  ofproto_rule_destroy__(struct rule *rule)
  {
      if (rule) {
          free(rule->ofpacts);
          rule->ofproto->ofproto_class->rule_dealloc(rule);
      }
  }
  
  /* This function allows an ofproto implementation to destroy any rules that
   * remain when its ->destruct() function is called.  The caller must have
   * already uninitialized any derived members of 'rule' (step 5 described in the
   * large comment in ofproto/ofproto-provider.h titled "Life Cycle").
   * This function implements steps 6 and 7.
   *
   * This function should only be called from an ofproto implementation's
   * ->destruct() function.  It is not suitable elsewhere. */
  void
  ofproto_rule_destroy(struct rule *rule)
  {
      assert(!rule->pending);
      oftable_remove_rule(rule);
      ofproto_rule_destroy__(rule);
  }
  
  /* Returns true if 'rule' has an OpenFlow OFPAT_OUTPUT or OFPAT_ENQUEUE action
   * that outputs to 'port' (output to OFPP_FLOOD and OFPP_ALL doesn't count). */
  bool
  ofproto_rule_has_out_port(const struct rule *rule, uint16_t port)
  {
      return (port == OFPP_NONE
              || ofpacts_output_to_port(rule->ofpacts, rule->ofpacts_len, port));
  }
  
  /* Returns true if a rule related to 'op' has an OpenFlow OFPAT_OUTPUT or
   * OFPAT_ENQUEUE action that outputs to 'out_port'. */
  bool
  ofoperation_has_out_port(const struct ofoperation *op, uint16_t out_port)
  {
      if (ofproto_rule_has_out_port(op->rule, out_port)) {
          return true;
      }
  
      switch (op->type) {
      case OFOPERATION_ADD:
          return op->victim && ofproto_rule_has_out_port(op->victim, out_port);
  
      case OFOPERATION_DELETE:
          return false;
  
      case OFOPERATION_MODIFY:
          return ofpacts_output_to_port(op->ofpacts, op->ofpacts_len, out_port);
      }
  
      NOT_REACHED();
  }
  
  /* Executes the actions indicated by 'rule' on 'packet' and credits 'rule''s
   * statistics appropriately.  'packet' must have at least sizeof(struct
   * ofp_packet_in) bytes of headroom.
   *
   * 'packet' doesn't necessarily have to match 'rule'.  'rule' will be credited
   * with statistics for 'packet' either way.
   *
   * Takes ownership of 'packet'. */
  static int
  rule_execute(struct rule *rule, uint16_t in_port, struct ofpbuf *packet)
  {
      struct flow flow;
  
      assert(ofpbuf_headroom(packet) >= sizeof(struct ofp_packet_in));
  
      flow_extract(packet, 0, 0, in_port, &flow);
      return rule->ofproto->ofproto_class->rule_execute(rule, &flow, packet);
  }
  
  /* Returns true if 'rule' should be hidden from the controller.
   *
   * Rules with priority higher than UINT16_MAX are set up by ofproto itself
   * (e.g. by in-band control) and are intentionally hidden from the
   * controller. */
  bool
  ofproto_rule_is_hidden(const struct rule *rule)
  {
      return rule->cr.priority > UINT16_MAX;
  }
  
  static enum oftable_flags
  rule_get_flags(const struct rule *rule)
  {
      return rule->ofproto->tables[rule->table_id].flags;
  }
  
  static bool
  rule_is_modifiable(const struct rule *rule)
  {
      return !(rule_get_flags(rule) & OFTABLE_READONLY);
  }
  
  static enum ofperr
  handle_echo_request(struct ofconn *ofconn, const struct ofp_header *oh)
  {
      ofconn_send_reply(ofconn, make_echo_reply(oh));
      return 0;
  }
  
  static enum ofperr
  handle_features_request(struct ofconn *ofconn, const struct ofp_header *oh)
  {
      struct ofproto *ofproto = ofconn_get_ofproto(ofconn);
      struct ofputil_switch_features features;
      struct ofport *port;
      bool arp_match_ip;
      struct ofpbuf *b;
  
      ofproto->ofproto_class->get_features(ofproto, &arp_match_ip,
                                           &features.actions);
      assert(features.actions & OFPUTIL_A_OUTPUT); /* sanity check */
  
      features.datapath_id = ofproto->datapath_id;
      features.n_buffers = pktbuf_capacity();
      features.n_tables = ofproto->n_tables;
      features.capabilities = (OFPUTIL_C_FLOW_STATS | OFPUTIL_C_TABLE_STATS |
                               OFPUTIL_C_PORT_STATS | OFPUTIL_C_QUEUE_STATS);
      if (arp_match_ip) {
          features.capabilities |= OFPUTIL_C_ARP_MATCH_IP;
      }
  
      b = ofputil_encode_switch_features(&features, ofconn_get_protocol(ofconn),
                                         oh->xid);
      HMAP_FOR_EACH (port, hmap_node, &ofproto->ports) {
          ofputil_put_switch_features_port(&port->pp, b);
      }
  
      ofconn_send_reply(ofconn, b);
      return 0;
  }
  
  static enum ofperr
  handle_get_config_request(struct ofconn *ofconn, const struct ofp_header *oh)
  {
      struct ofproto *ofproto = ofconn_get_ofproto(ofconn);
      struct ofp_switch_config *osc;
      enum ofp_config_flags flags;
      struct ofpbuf *buf;
  
      /* Send reply. */
      buf = ofpraw_alloc_reply(OFPRAW_OFPT_GET_CONFIG_REPLY, oh, 0);
      osc = ofpbuf_put_uninit(buf, sizeof *osc);
      flags = ofproto->frag_handling;
      if (ofconn_get_invalid_ttl_to_controller(ofconn)) {
          flags |= OFPC_INVALID_TTL_TO_CONTROLLER;
      }
      osc->flags = htons(flags);
      osc->miss_send_len = htons(ofconn_get_miss_send_len(ofconn));
      ofconn_send_reply(ofconn, buf);
  
      return 0;
  }
  
  static enum ofperr
  handle_set_config(struct ofconn *ofconn, const struct ofp_header *oh)
  {
      const struct ofp_switch_config *osc = ofpmsg_body(oh);
      struct ofproto *ofproto = ofconn_get_ofproto(ofconn);
      uint16_t flags = ntohs(osc->flags);
  
      if (ofconn_get_type(ofconn) != OFCONN_PRIMARY
          || ofconn_get_role(ofconn) != NX_ROLE_SLAVE) {
          enum ofp_config_flags cur = ofproto->frag_handling;
          enum ofp_config_flags next = flags & OFPC_FRAG_MASK;
  
          assert((cur & OFPC_FRAG_MASK) == cur);
          if (cur != next) {
              if (ofproto->ofproto_class->set_frag_handling(ofproto, next)) {
                  ofproto->frag_handling = next;
              } else {
                  VLOG_WARN_RL(&rl, "%s: unsupported fragment handling mode %s",
                               ofproto->name,
                               ofputil_frag_handling_to_string(next));
              }
          }
      }
      ofconn_set_invalid_ttl_to_controller(ofconn,
               (flags & OFPC_INVALID_TTL_TO_CONTROLLER));
  
      ofconn_set_miss_send_len(ofconn, ntohs(osc->miss_send_len));
  
      return 0;
  }
  
  /* Checks whether 'ofconn' is a slave controller.  If so, returns an OpenFlow
   * error message code for the caller to propagate upward.  Otherwise, returns
   * 0.
   *
   * The log message mentions 'msg_type'. */
  static enum ofperr
  reject_slave_controller(struct ofconn *ofconn)
  {
      if (ofconn_get_type(ofconn) == OFCONN_PRIMARY
          && ofconn_get_role(ofconn) == NX_ROLE_SLAVE) {
          return OFPERR_OFPBRC_EPERM;
      } else {
          return 0;
      }
  }
  
  static enum ofperr
  handle_packet_out(struct ofconn *ofconn, const struct ofp_header *oh)
  {
      struct ofproto *p = ofconn_get_ofproto(ofconn);
      struct ofputil_packet_out po;
      struct ofpbuf *payload;
      uint64_t ofpacts_stub[1024 / 8];
      struct ofpbuf ofpacts;
      struct flow flow;
      enum ofperr error;
  
      COVERAGE_INC(ofproto_packet_out);
  
      error = reject_slave_controller(ofconn);
      if (error) {
          goto exit;
      }
  
      /* Decode message. */
      ofpbuf_use_stub(&ofpacts, ofpacts_stub, sizeof ofpacts_stub);
      error = ofputil_decode_packet_out(&po, oh, &ofpacts);
      if (error) {
          goto exit_free_ofpacts;
      }
  
      /* Get payload. */
      if (po.buffer_id != UINT32_MAX) {
          error = ofconn_pktbuf_retrieve(ofconn, po.buffer_id, &payload, NULL);
          if (error || !payload) {
              goto exit_free_ofpacts;
          }
      } else {
          payload = xmalloc(sizeof *payload);
          ofpbuf_use_const(payload, po.packet, po.packet_len);
      }
  
      /* Send out packet. */
      flow_extract(payload, 0, 0, po.in_port, &flow);
      error = p->ofproto_class->packet_out(p, payload, &flow,
                                           po.ofpacts, po.ofpacts_len);
      ofpbuf_delete(payload);
  
  exit_free_ofpacts:
      ofpbuf_uninit(&ofpacts);
  exit:
      return error;
  }
  
  static void
  update_port_config(struct ofport *port,
                     enum ofputil_port_config config,
                     enum ofputil_port_config mask)
  {
      enum ofputil_port_config old_config = port->pp.config;
      enum ofputil_port_config toggle;
  
      toggle = (config ^ port->pp.config) & mask;
      if (toggle & OFPUTIL_PC_PORT_DOWN) {
          if (config & OFPUTIL_PC_PORT_DOWN) {
              netdev_turn_flags_off(port->netdev, NETDEV_UP, true);
          } else {
              netdev_turn_flags_on(port->netdev, NETDEV_UP, true);
          }
          toggle &= ~OFPUTIL_PC_PORT_DOWN;
      }
  
      port->pp.config ^= toggle;
      if (port->pp.config != old_config) {
          port->ofproto->ofproto_class->port_reconfigured(port, old_config);
      }
  }
  
  static enum ofperr
  handle_port_mod(struct ofconn *ofconn, const struct ofp_header *oh)
  {
      struct ofproto *p = ofconn_get_ofproto(ofconn);
      struct ofputil_port_mod pm;
      struct ofport *port;
      enum ofperr error;
  
      error = reject_slave_controller(ofconn);
      if (error) {
          return error;
      }
  
      error = ofputil_decode_port_mod(oh, &pm);
      if (error) {
          return error;
      }
  
      port = ofproto_get_port(p, pm.port_no);
      if (!port) {
          return OFPERR_OFPPMFC_BAD_PORT;
      } else if (!eth_addr_equals(port->pp.hw_addr, pm.hw_addr)) {
          return OFPERR_OFPPMFC_BAD_HW_ADDR;
      } else {
          update_port_config(port, pm.config, pm.mask);
          if (pm.advertise) {
              netdev_set_advertisements(port->netdev, pm.advertise);
          }
      }
      return 0;
  }
  
  static enum ofperr
  handle_desc_stats_request(struct ofconn *ofconn,
                            const struct ofp_header *request)
  {
      struct ofproto *p = ofconn_get_ofproto(ofconn);
      struct ofp_desc_stats *ods;
      struct ofpbuf *msg;
  
      msg = ofpraw_alloc_stats_reply(request, 0);
      ods = ofpbuf_put_zeros(msg, sizeof *ods);
      ovs_strlcpy(ods->mfr_desc, p->mfr_desc, sizeof ods->mfr_desc);
      ovs_strlcpy(ods->hw_desc, p->hw_desc, sizeof ods->hw_desc);
      ovs_strlcpy(ods->sw_desc, p->sw_desc, sizeof ods->sw_desc);
      ovs_strlcpy(ods->serial_num, p->serial_desc, sizeof ods->serial_num);
      ovs_strlcpy(ods->dp_desc, p->dp_desc, sizeof ods->dp_desc);
      ofconn_send_reply(ofconn, msg);
  
      return 0;
  }
  
  static enum ofperr
  handle_table_stats_request(struct ofconn *ofconn,
                             const struct ofp_header *request)
  {
      struct ofproto *p = ofconn_get_ofproto(ofconn);
      struct ofp10_table_stats *ots;
      struct ofpbuf *msg;
      size_t i;
  
      msg = ofpraw_alloc_stats_reply(request, sizeof *ots * p->n_tables);
      ots = ofpbuf_put_zeros(msg, sizeof *ots * p->n_tables);
      for (i = 0; i < p->n_tables; i++) {
          ots[i].table_id = i;
          sprintf(ots[i].name, "table%zu", i);
          ots[i].wildcards = htonl(OFPFW10_ALL);
          ots[i].max_entries = htonl(1000000); /* An arbitrary big number. */
          ots[i].active_count = htonl(classifier_count(&p->tables[i].cls));
      }
  
      p->ofproto_class->get_tables(p, ots);
  
      for (i = 0; i < p->n_tables; i++) {
          const struct oftable *table = &p->tables[i];
  
          if (table->name) {
              ovs_strzcpy(ots[i].name, table->name, sizeof ots[i].name);
          }
  
          if (table->max_flows < ntohl(ots[i].max_entries)) {
              ots[i].max_entries = htonl(table->max_flows);
          }
      }
  
      ofconn_send_reply(ofconn, msg);
      return 0;
  }
  
  static void
  append_port_stat(struct ofport *port, struct list *replies)
  {
      struct netdev_stats stats;
      struct ofp10_port_stats *ops;
  
      /* Intentionally ignore return value, since errors will set
       * 'stats' to all-1s, which is correct for OpenFlow, and
       * netdev_get_stats() will log errors. */
      ofproto_port_get_stats(port, &stats);
  
      ops = ofpmp_append(replies, sizeof *ops);
      ops->port_no = htons(port->pp.port_no);
      memset(ops->pad, 0, sizeof ops->pad);
      put_32aligned_be64(&ops->rx_packets, htonll(stats.rx_packets));
      put_32aligned_be64(&ops->tx_packets, htonll(stats.tx_packets));
      put_32aligned_be64(&ops->rx_bytes, htonll(stats.rx_bytes));
      put_32aligned_be64(&ops->tx_bytes, htonll(stats.tx_bytes));
      put_32aligned_be64(&ops->rx_dropped, htonll(stats.rx_dropped));
      put_32aligned_be64(&ops->tx_dropped, htonll(stats.tx_dropped));
      put_32aligned_be64(&ops->rx_errors, htonll(stats.rx_errors));
      put_32aligned_be64(&ops->tx_errors, htonll(stats.tx_errors));
      put_32aligned_be64(&ops->rx_frame_err, htonll(stats.rx_frame_errors));
      put_32aligned_be64(&ops->rx_over_err, htonll(stats.rx_over_errors));
      put_32aligned_be64(&ops->rx_crc_err, htonll(stats.rx_crc_errors));
      put_32aligned_be64(&ops->collisions, htonll(stats.collisions));
  }
  
  static enum ofperr
  handle_port_stats_request(struct ofconn *ofconn,
                            const struct ofp_header *request)
  {
      struct ofproto *p = ofconn_get_ofproto(ofconn);
      const struct ofp10_port_stats_request *psr = ofpmsg_body(request);
      struct ofport *port;
      struct list replies;
  
      ofpmp_init(&replies, request);
      if (psr->port_no != htons(OFPP_NONE)) {
          port = ofproto_get_port(p, ntohs(psr->port_no));
          if (port) {
              append_port_stat(port, &replies);
          }
      } else {
          HMAP_FOR_EACH (port, hmap_node, &p->ports) {
              append_port_stat(port, &replies);
          }
      }
  
      ofconn_send_replies(ofconn, &replies);
      return 0;
  }
  
  static enum ofperr
  handle_port_desc_stats_request(struct ofconn *ofconn,
                                 const struct ofp_header *request)
  {
      struct ofproto *p = ofconn_get_ofproto(ofconn);
      enum ofp_version version;
      struct ofport *port;
      struct list replies;
  
      ofpmp_init(&replies, request);
  
      version = ofputil_protocol_to_ofp_version(ofconn_get_protocol(ofconn));
      HMAP_FOR_EACH (port, hmap_node, &p->ports) {
          ofputil_append_port_desc_stats_reply(version, &port->pp, &replies);
      }
  
      ofconn_send_replies(ofconn, &replies);
      return 0;
  }
  
  static void
  calc_flow_duration__(long long int start, long long int now,
                       uint32_t *sec, uint32_t *nsec)
  {
      long long int msecs = now - start;
      *sec = msecs / 1000;
      *nsec = (msecs % 1000) * (1000 * 1000);
  }
  
  /* Checks whether 'table_id' is 0xff or a valid table ID in 'ofproto'.  Returns
   * 0 if 'table_id' is OK, otherwise an OpenFlow error code.  */
  static enum ofperr
  check_table_id(const struct ofproto *ofproto, uint8_t table_id)
  {
      return (table_id == 0xff || table_id < ofproto->n_tables
              ? 0
              : OFPERR_NXBRC_BAD_TABLE_ID);
  
  }
  
  static struct oftable *
  next_visible_table(const struct ofproto *ofproto, uint8_t table_id)
  {
      struct oftable *table;
  
      for (table = &ofproto->tables[table_id];
           table < &ofproto->tables[ofproto->n_tables];
           table++) {
          if (!(table->flags & OFTABLE_HIDDEN)) {
              return table;
          }
      }
  
      return NULL;
  }
  
  static struct oftable *
  first_matching_table(const struct ofproto *ofproto, uint8_t table_id)
  {
      if (table_id == 0xff) {
          return next_visible_table(ofproto, 0);
      } else if (table_id < ofproto->n_tables) {
          return &ofproto->tables[table_id];
      } else {
          return NULL;
      }
  }
  
  static struct oftable *
  next_matching_table(const struct ofproto *ofproto,
                      const struct oftable *table, uint8_t table_id)
  {
      return (table_id == 0xff
              ? next_visible_table(ofproto, (table - ofproto->tables) + 1)
              : NULL);
  }
  
  /* Assigns TABLE to each oftable, in turn, that matches TABLE_ID in OFPROTO:
   *
   *   - If TABLE_ID is 0xff, this iterates over every classifier table in
   *     OFPROTO, skipping tables marked OFTABLE_HIDDEN.
   *
   *   - If TABLE_ID is the number of a table in OFPROTO, then the loop iterates
   *     only once, for that table.  (This can be used to access tables marked
   *     OFTABLE_HIDDEN.)
   *
   *   - Otherwise, TABLE_ID isn't valid for OFPROTO, so the loop won't be
   *     entered at all.  (Perhaps you should have validated TABLE_ID with
   *     check_table_id().)
   *
   * All parameters are evaluated multiple times.
   */
  #define FOR_EACH_MATCHING_TABLE(TABLE, TABLE_ID, OFPROTO)         \
      for ((TABLE) = first_matching_table(OFPROTO, TABLE_ID);       \
           (TABLE) != NULL;                                         \
           (TABLE) = next_matching_table(OFPROTO, TABLE, TABLE_ID))
  
  /* Searches 'ofproto' for rules in table 'table_id' (or in all tables, if
   * 'table_id' is 0xff) that match 'match' in the "loose" way required for
   * OpenFlow OFPFC_MODIFY and OFPFC_DELETE requests and puts them on list
   * 'rules'.
   *
   * If 'out_port' is anything other than OFPP_NONE, then only rules that output
   * to 'out_port' are included.
   *
   * Hidden rules are always omitted.
   *
   * Returns 0 on success, otherwise an OpenFlow error code. */
  static enum ofperr
  collect_rules_loose(struct ofproto *ofproto, uint8_t table_id,
                      const struct cls_rule *match,
                      ovs_be64 cookie, ovs_be64 cookie_mask,
                      uint16_t out_port, struct list *rules)
  {
      struct oftable *table;
      enum ofperr error;
  
      error = check_table_id(ofproto, table_id);
      if (error) {
          return error;
      }
  
      list_init(rules);
      FOR_EACH_MATCHING_TABLE (table, table_id, ofproto) {
          struct cls_cursor cursor;
          struct rule *rule;
  
          cls_cursor_init(&cursor, &table->cls, match);
          CLS_CURSOR_FOR_EACH (rule, cr, &cursor) {
              if (rule->pending) {
                  return OFPROTO_POSTPONE;
              }
              if (!ofproto_rule_is_hidden(rule)
                  && ofproto_rule_has_out_port(rule, out_port)
                      && !((rule->flow_cookie ^ cookie) & cookie_mask)) {
                  list_push_back(rules, &rule->ofproto_node);
              }
          }
      }
      return 0;
  }
  
  /* Searches 'ofproto' for rules in table 'table_id' (or in all tables, if
   * 'table_id' is 0xff) that match 'match' in the "strict" way required for
   * OpenFlow OFPFC_MODIFY_STRICT and OFPFC_DELETE_STRICT requests and puts them
   * on list 'rules'.
   *
   * If 'out_port' is anything other than OFPP_NONE, then only rules that output
   * to 'out_port' are included.
   *
   * Hidden rules are always omitted.
   *
   * Returns 0 on success, otherwise an OpenFlow error code. */
  static enum ofperr
  collect_rules_strict(struct ofproto *ofproto, uint8_t table_id,
                       const struct cls_rule *match,
                       ovs_be64 cookie, ovs_be64 cookie_mask,
                       uint16_t out_port, struct list *rules)
  {
      struct oftable *table;
      int error;
  
      error = check_table_id(ofproto, table_id);
      if (error) {
          return error;
      }
  
      list_init(rules);
      FOR_EACH_MATCHING_TABLE (table, table_id, ofproto) {
          struct rule *rule;
  
          rule = rule_from_cls_rule(classifier_find_rule_exactly(&table->cls,
                                                                 match));
          if (rule) {
              if (rule->pending) {
                  return OFPROTO_POSTPONE;
              }
              if (!ofproto_rule_is_hidden(rule)
                  && ofproto_rule_has_out_port(rule, out_port)
                      && !((rule->flow_cookie ^ cookie) & cookie_mask)) {
                  list_push_back(rules, &rule->ofproto_node);
              }
          }
      }
      return 0;
  }
  
  /* Returns 'age_ms' (a duration in milliseconds), converted to seconds and
   * forced into the range of a uint16_t. */
  static int
  age_secs(long long int age_ms)
  {
      return (age_ms < 0 ? 0
              : age_ms >= UINT16_MAX * 1000 ? UINT16_MAX
              : (unsigned int) age_ms / 1000);
  }
  
  static enum ofperr
  handle_flow_stats_request(struct ofconn *ofconn,
                            const struct ofp_header *request)
  {
      struct ofproto *ofproto = ofconn_get_ofproto(ofconn);
      struct ofputil_flow_stats_request fsr;
      struct list replies;
      struct list rules;
      struct rule *rule;
      enum ofperr error;
  
      error = ofputil_decode_flow_stats_request(&fsr, request);
      if (error) {
          return error;
      }
  
      error = collect_rules_loose(ofproto, fsr.table_id, &fsr.match,
                                  fsr.cookie, fsr.cookie_mask,
                                  fsr.out_port, &rules);
      if (error) {
          return error;
      }
  
      ofpmp_init(&replies, request);
      LIST_FOR_EACH (rule, ofproto_node, &rules) {
          long long int now = time_msec();
          struct ofputil_flow_stats fs;
  
          fs.rule = rule->cr;
          fs.cookie = rule->flow_cookie;
          fs.table_id = rule->table_id;
          calc_flow_duration__(rule->created, now, &fs.duration_sec,
                               &fs.duration_nsec);
          fs.idle_timeout = rule->idle_timeout;
          fs.hard_timeout = rule->hard_timeout;
          fs.idle_age = age_secs(now - rule->used);
          fs.hard_age = age_secs(now - rule->modified);
          ofproto->ofproto_class->rule_get_stats(rule, &fs.packet_count,
                                                 &fs.byte_count);
          fs.ofpacts = rule->ofpacts;
          fs.ofpacts_len = rule->ofpacts_len;
          ofputil_append_flow_stats_reply(&fs, &replies);
      }
      ofconn_send_replies(ofconn, &replies);
  
      return 0;
  }
  
  static void
  flow_stats_ds(struct rule *rule, struct ds *results)
  {
      uint64_t packet_count, byte_count;
  
      rule->ofproto->ofproto_class->rule_get_stats(rule,
                                                   &packet_count, &byte_count);
  
      if (rule->table_id != 0) {
          ds_put_format(results, "table_id=%"PRIu8", ", rule->table_id);
      }
      ds_put_format(results, "duration=%llds, ",
                    (time_msec() - rule->created) / 1000);
      ds_put_format(results, "priority=%u, ", rule->cr.priority);
      ds_put_format(results, "n_packets=%"PRIu64", ", packet_count);
      ds_put_format(results, "n_bytes=%"PRIu64", ", byte_count);
      cls_rule_format(&rule->cr, results);
      ds_put_char(results, ',');
      if (rule->ofpacts_len > 0) {
          ofpacts_format(rule->ofpacts, rule->ofpacts_len, results);
      } else {
          ds_put_cstr(results, "drop");
      }
      ds_put_cstr(results, "\n");
  }
  
  /* Adds a pretty-printed description of all flows to 'results', including
   * hidden flows (e.g., set up by in-band control). */
  void
  ofproto_get_all_flows(struct ofproto *p, struct ds *results)
  {
      struct oftable *table;
  
      OFPROTO_FOR_EACH_TABLE (table, p) {
          struct cls_cursor cursor;
          struct rule *rule;
  
          cls_cursor_init(&cursor, &table->cls, NULL);
          CLS_CURSOR_FOR_EACH (rule, cr, &cursor) {
              flow_stats_ds(rule, results);
          }
      }
  }
  
  /* Obtains the NetFlow engine type and engine ID for 'ofproto' into
   * '*engine_type' and '*engine_id', respectively. */
  void
  ofproto_get_netflow_ids(const struct ofproto *ofproto,
                          uint8_t *engine_type, uint8_t *engine_id)
  {
      ofproto->ofproto_class->get_netflow_ids(ofproto, engine_type, engine_id);
  }
  
  /* Checks the fault status of CFM for 'ofp_port' within 'ofproto'.  Returns a
   * bitmask of 'cfm_fault_reason's to indicate a CFM fault (generally
   * indicating a connectivity problem).  Returns zero if CFM is not faulted,
   * and -1 if CFM is not enabled on 'port'. */
  int
  ofproto_port_get_cfm_fault(const struct ofproto *ofproto, uint16_t ofp_port)
  {
      struct ofport *ofport = ofproto_get_port(ofproto, ofp_port);
      return (ofport && ofproto->ofproto_class->get_cfm_fault
              ? ofproto->ofproto_class->get_cfm_fault(ofport)
              : -1);
  }
  
  /* Gets the MPIDs of the remote maintenance points broadcasting to 'ofp_port'
   * within 'ofproto'.  Populates 'rmps' with an array of MPIDs owned by
   * 'ofproto', and 'n_rmps' with the number of MPIDs in 'rmps'.  Returns a
   * number less than 0 if CFM is not enabled on 'ofp_port'. */
  int
  ofproto_port_get_cfm_remote_mpids(const struct ofproto *ofproto,
                                    uint16_t ofp_port, const uint64_t **rmps,
                                    size_t *n_rmps)
  {
      struct ofport *ofport = ofproto_get_port(ofproto, ofp_port);
  
      *rmps = NULL;
      *n_rmps = 0;
      return (ofport && ofproto->ofproto_class->get_cfm_remote_mpids
              ? ofproto->ofproto_class->get_cfm_remote_mpids(ofport, rmps,
                                                             n_rmps)
              : -1);
  }
  
  /* Checks the health of the CFM for 'ofp_port' within 'ofproto'.  Returns an
   * integer value between 0 and 100 to indicate the health of the port as a
   * percentage which is the average of cfm health of all the remote_mpids or
   * returns -1 if CFM is not enabled on 'ofport'. */
  int
  ofproto_port_get_cfm_health(const struct ofproto *ofproto, uint16_t ofp_port)
  {
      struct ofport *ofport = ofproto_get_port(ofproto, ofp_port);
      return (ofport && ofproto->ofproto_class->get_cfm_health
              ? ofproto->ofproto_class->get_cfm_health(ofport)
              : -1);
  }
  
  static enum ofperr
  handle_aggregate_stats_request(struct ofconn *ofconn,
                                 const struct ofp_header *oh)
  {
      struct ofproto *ofproto = ofconn_get_ofproto(ofconn);
      struct ofputil_flow_stats_request request;
      struct ofputil_aggregate_stats stats;
      bool unknown_packets, unknown_bytes;
      struct ofpbuf *reply;
      struct list rules;
      struct rule *rule;
      enum ofperr error;
  
      error = ofputil_decode_flow_stats_request(&request, oh);
      if (error) {
          return error;
      }
  
      error = collect_rules_loose(ofproto, request.table_id, &request.match,
                                  request.cookie, request.cookie_mask,
                                  request.out_port, &rules);
      if (error) {
          return error;
      }
  
      memset(&stats, 0, sizeof stats);
      unknown_packets = unknown_bytes = false;
      LIST_FOR_EACH (rule, ofproto_node, &rules) {
          uint64_t packet_count;
          uint64_t byte_count;
  
          ofproto->ofproto_class->rule_get_stats(rule, &packet_count,
                                                 &byte_count);
  
          if (packet_count == UINT64_MAX) {
              unknown_packets = true;
          } else {
              stats.packet_count += packet_count;
          }
  
          if (byte_count == UINT64_MAX) {
              unknown_bytes = true;
          } else {
              stats.byte_count += byte_count;
          }
  
          stats.flow_count++;
      }
      if (unknown_packets) {
          stats.packet_count = UINT64_MAX;
      }
      if (unknown_bytes) {
          stats.byte_count = UINT64_MAX;
      }
  
      reply = ofputil_encode_aggregate_stats_reply(&stats, oh);
      ofconn_send_reply(ofconn, reply);
  
      return 0;
  }
  
  struct queue_stats_cbdata {
      struct ofport *ofport;
      struct list replies;
  };
  
  static void
  put_queue_stats(struct queue_stats_cbdata *cbdata, uint32_t queue_id,
                  const struct netdev_queue_stats *stats)
  {
      struct ofp10_queue_stats *reply;
  
      reply = ofpmp_append(&cbdata->replies, sizeof *reply);
      reply->port_no = htons(cbdata->ofport->pp.port_no);
      memset(reply->pad, 0, sizeof reply->pad);
      reply->queue_id = htonl(queue_id);
      put_32aligned_be64(&reply->tx_bytes, htonll(stats->tx_bytes));
      put_32aligned_be64(&reply->tx_packets, htonll(stats->tx_packets));
      put_32aligned_be64(&reply->tx_errors, htonll(stats->tx_errors));
  }
  
  static void
  handle_queue_stats_dump_cb(uint32_t queue_id,
                             struct netdev_queue_stats *stats,
                             void *cbdata_)
  {
      struct queue_stats_cbdata *cbdata = cbdata_;
  
      put_queue_stats(cbdata, queue_id, stats);
  }
  
  static enum ofperr
  handle_queue_stats_for_port(struct ofport *port, uint32_t queue_id,
                              struct queue_stats_cbdata *cbdata)
  {
      cbdata->ofport = port;
      if (queue_id == OFPQ_ALL) {
          netdev_dump_queue_stats(port->netdev,
                                  handle_queue_stats_dump_cb, cbdata);
      } else {
          struct netdev_queue_stats stats;
  
          if (!netdev_get_queue_stats(port->netdev, queue_id, &stats)) {
              put_queue_stats(cbdata, queue_id, &stats);
          } else {
              return OFPERR_OFPQOFC_BAD_QUEUE;
          }
      }
      return 0;
  }
  
  static enum ofperr
  handle_queue_stats_request(struct ofconn *ofconn,
                             const struct ofp_header *rq)
  {
      struct ofproto *ofproto = ofconn_get_ofproto(ofconn);
      const struct ofp10_queue_stats_request *qsr = ofpmsg_body(rq);
      struct queue_stats_cbdata cbdata;
      unsigned int port_no;
      struct ofport *port;
      uint32_t queue_id;
      enum ofperr error;
  
      COVERAGE_INC(ofproto_queue_req);
  
      ofpmp_init(&cbdata.replies, rq);
  
      port_no = ntohs(qsr->port_no);
      queue_id = ntohl(qsr->queue_id);
      if (port_no == OFPP_ALL) {
          error = OFPERR_OFPQOFC_BAD_QUEUE;
          HMAP_FOR_EACH (port, hmap_node, &ofproto->ports) {
              if (!handle_queue_stats_for_port(port, queue_id, &cbdata)) {
                  error = 0;
              }
          }
      } else {
          port = ofproto_get_port(ofproto, port_no);
          error = (port
                   ? handle_queue_stats_for_port(port, queue_id, &cbdata)
                   : OFPERR_OFPQOFC_BAD_PORT);
      }
      if (!error) {
          ofconn_send_replies(ofconn, &cbdata.replies);
      } else {
          ofpbuf_list_delete(&cbdata.replies);
      }
  
      return error;
  }
  
  static bool
  is_flow_deletion_pending(const struct ofproto *ofproto,
                           const struct cls_rule *cls_rule,
                           uint8_t table_id)
  {
      if (!hmap_is_empty(&ofproto->deletions)) {
          struct ofoperation *op;
  
          HMAP_FOR_EACH_WITH_HASH (op, hmap_node,
                                   cls_rule_hash(cls_rule, table_id),
                                   &ofproto->deletions) {
              if (cls_rule_equal(cls_rule, &op->rule->cr)) {
                  return true;
              }
          }
      }
  
      return false;
  }
  
  /* Implements OFPFC_ADD and the cases for OFPFC_MODIFY and OFPFC_MODIFY_STRICT
   * in which no matching flow already exists in the flow table.
   *
   * Adds the flow specified by 'ofm', which is followed by 'n_actions'
   * ofp_actions, to the ofproto's flow table.  Returns 0 on success, an OpenFlow
   * error code on failure, or OFPROTO_POSTPONE if the operation cannot be
   * initiated now but may be retried later.
   *
   * Upon successful return, takes ownership of 'fm->ofpacts'.  On failure,
   * ownership remains with the caller.
   *
   * 'ofconn' is used to retrieve the packet buffer specified in ofm->buffer_id,
   * if any. */
  static enum ofperr
  add_flow(struct ofproto *ofproto, struct ofconn *ofconn,
           const struct ofputil_flow_mod *fm, const struct ofp_header *request)
  {
      struct oftable *table;
      struct ofopgroup *group;
      struct rule *victim;
      struct rule *rule;
      int error;
  
      error = check_table_id(ofproto, fm->table_id);
      if (error) {
          return error;
      }
  
      /* Pick table. */
      if (fm->table_id == 0xff) {
          uint8_t table_id;
          if (ofproto->ofproto_class->rule_choose_table) {
              error = ofproto->ofproto_class->rule_choose_table(ofproto, &fm->cr,
                                                                &table_id);
              if (error) {
                  return error;
              }
              assert(table_id < ofproto->n_tables);
              table = &ofproto->tables[table_id];
          } else {
              table = &ofproto->tables[0];
          }
      } else if (fm->table_id < ofproto->n_tables) {
          table = &ofproto->tables[fm->table_id];
      } else {
          return OFPERR_NXFMFC_BAD_TABLE_ID;
      }
  
      if (table->flags & OFTABLE_READONLY) {
          return OFPERR_OFPBRC_EPERM;
      }
  
      /* Check for overlap, if requested. */
      if (fm->flags & OFPFF_CHECK_OVERLAP
          && classifier_rule_overlaps(&table->cls, &fm->cr)) {
          return OFPERR_OFPFMFC_OVERLAP;
      }
  
      /* Serialize against pending deletion. */
      if (is_flow_deletion_pending(ofproto, &fm->cr, table - ofproto->tables)) {
          return OFPROTO_POSTPONE;
      }
  
      /* Allocate new rule. */
      rule = ofproto->ofproto_class->rule_alloc();
      if (!rule) {
          VLOG_WARN_RL(&rl, "%s: failed to create rule (%s)",
                       ofproto->name, strerror(error));
          return ENOMEM;
      }
      rule->ofproto = ofproto;
      rule->cr = fm->cr;
      rule->pending = NULL;
      rule->flow_cookie = fm->new_cookie;
      rule->created = rule->modified = rule->used = time_msec();
      rule->idle_timeout = fm->idle_timeout;
      rule->hard_timeout = fm->hard_timeout;
      rule->table_id = table - ofproto->tables;
      rule->send_flow_removed = (fm->flags & OFPFF_SEND_FLOW_REM) != 0;
      rule->ofpacts = xmemdup(fm->ofpacts, fm->ofpacts_len);
      rule->ofpacts_len = fm->ofpacts_len;
      rule->evictable = true;
      rule->eviction_group = NULL;
      rule->monitor_flags = 0;
      rule->add_seqno = 0;
      rule->modify_seqno = 0;
  
      /* Insert new rule. */
      victim = oftable_replace_rule(rule);
      if (victim && !rule_is_modifiable(victim)) {
          error = OFPERR_OFPBRC_EPERM;
      } else if (victim && victim->pending) {
          error = OFPROTO_POSTPONE;
      } else {
          struct ofoperation *op;
          struct rule *evict;
  
          if (classifier_count(&table->cls) > table->max_flows) {
              bool was_evictable;
  
              was_evictable = rule->evictable;
              rule->evictable = false;
              evict = choose_rule_to_evict(table);
              rule->evictable = was_evictable;
  
              if (!evict) {
                  error = OFPERR_OFPFMFC_ALL_TABLES_FULL;
                  goto exit;
              } else if (evict->pending) {
                  error = OFPROTO_POSTPONE;
                  goto exit;
              }
          } else {
              evict = NULL;
          }
  
          group = ofopgroup_create(ofproto, ofconn, request, fm->buffer_id);
          op = ofoperation_create(group, rule, OFOPERATION_ADD, 0);
          op->victim = victim;
  
          error = ofproto->ofproto_class->rule_construct(rule);
          if (error) {
              op->group->n_running--;
              ofoperation_destroy(rule->pending);
          } else if (evict) {
              delete_flow__(evict, group);
          }
          ofopgroup_submit(group);
      }
  
  exit:
      /* Back out if an error occurred. */
      if (error) {
          oftable_substitute_rule(rule, victim);
          ofproto_rule_destroy__(rule);
      }
      return error;
  }
  
  /* OFPFC_MODIFY and OFPFC_MODIFY_STRICT. */
  
  /* Modifies the rules listed in 'rules', changing their actions to match those
   * in 'fm'.
   *
   * 'ofconn' is used to retrieve the packet buffer specified in fm->buffer_id,
   * if any.
   *
   * Returns 0 on success, otherwise an OpenFlow error code. */
  static enum ofperr
  modify_flows__(struct ofproto *ofproto, struct ofconn *ofconn,
                 const struct ofputil_flow_mod *fm,
                 const struct ofp_header *request, struct list *rules)
  {
      struct ofopgroup *group;
      struct rule *rule;
      enum ofperr error;
  
      group = ofopgroup_create(ofproto, ofconn, request, fm->buffer_id);
      error = OFPERR_OFPBRC_EPERM;
      LIST_FOR_EACH (rule, ofproto_node, rules) {
          struct ofoperation *op;
          bool actions_changed;
          ovs_be64 new_cookie;
  
          if (rule_is_modifiable(rule)) {
              /* At least one rule is modifiable, don't report EPERM error. */
              error = 0;
          } else {
              continue;
          }
  
          actions_changed = !ofpacts_equal(fm->ofpacts, fm->ofpacts_len,
                                           rule->ofpacts, rule->ofpacts_len);
          new_cookie = (fm->new_cookie != htonll(UINT64_MAX)
                        ? fm->new_cookie
                        : rule->flow_cookie);
          if (!actions_changed && new_cookie == rule->flow_cookie) {
              /* No change at all. */
              continue;
          }
  
          op = ofoperation_create(group, rule, OFOPERATION_MODIFY, 0);
          rule->flow_cookie = new_cookie;
          if (actions_changed) {
              op->ofpacts = rule->ofpacts;
              op->ofpacts_len = rule->ofpacts_len;
              rule->ofpacts = xmemdup(fm->ofpacts, fm->ofpacts_len);
              rule->ofpacts_len = fm->ofpacts_len;
              rule->ofproto->ofproto_class->rule_modify_actions(rule);
          } else {
              ofoperation_complete(op, 0);
          }
      }
      ofopgroup_submit(group);
  
      return error;
  }
  
  /* Implements OFPFC_MODIFY.  Returns 0 on success or an OpenFlow error code on
   * failure.
   *
   * 'ofconn' is used to retrieve the packet buffer specified in fm->buffer_id,
   * if any. */
  static enum ofperr
  modify_flows_loose(struct ofproto *ofproto, struct ofconn *ofconn,
                     const struct ofputil_flow_mod *fm,
                     const struct ofp_header *request)
  {
      struct list rules;
      int error;
  
      error = collect_rules_loose(ofproto, fm->table_id, &fm->cr,
                                  fm->cookie, fm->cookie_mask,
                                  OFPP_NONE, &rules);
      if (error) {
          return error;
      } else if (list_is_empty(&rules)) {
          return fm->cookie_mask ? 0 : add_flow(ofproto, ofconn, fm, request);
      } else {
          return modify_flows__(ofproto, ofconn, fm, request, &rules);
      }
  }
  
  /* Implements OFPFC_MODIFY_STRICT.  Returns 0 on success or an OpenFlow error
   * code on failure.
   *
   * 'ofconn' is used to retrieve the packet buffer specified in fm->buffer_id,
   * if any. */
  static enum ofperr
  modify_flow_strict(struct ofproto *ofproto, struct ofconn *ofconn,
                     const struct ofputil_flow_mod *fm,
                     const struct ofp_header *request)
  {
      struct list rules;
      int error;
  
      error = collect_rules_strict(ofproto, fm->table_id, &fm->cr,
                                   fm->cookie, fm->cookie_mask,
                                   OFPP_NONE, &rules);
  
      if (error) {
          return error;
      } else if (list_is_empty(&rules)) {
          return fm->cookie_mask ? 0 : add_flow(ofproto, ofconn, fm, request);
      } else {
          return list_is_singleton(&rules) ? modify_flows__(ofproto, ofconn,
                                                            fm, request, &rules)
                                           : 0;
      }
  }
  
  /* OFPFC_DELETE implementation. */
  
  static void
  delete_flow__(struct rule *rule, struct ofopgroup *group)
  {
      struct ofproto *ofproto = rule->ofproto;
  
      ofproto_rule_send_removed(rule, OFPRR_DELETE);
  
      ofoperation_create(group, rule, OFOPERATION_DELETE, OFPRR_DELETE);
      oftable_remove_rule(rule);
      ofproto->ofproto_class->rule_destruct(rule);
  }
  
  /* Deletes the rules listed in 'rules'.
   *
   * Returns 0 on success, otherwise an OpenFlow error code. */
  static enum ofperr
  delete_flows__(struct ofproto *ofproto, struct ofconn *ofconn,
                 const struct ofp_header *request, struct list *rules)
  {
      struct rule *rule, *next;
      struct ofopgroup *group;
  
      group = ofopgroup_create(ofproto, ofconn, request, UINT32_MAX);
      LIST_FOR_EACH_SAFE (rule, next, ofproto_node, rules) {
          delete_flow__(rule, group);
      }
      ofopgroup_submit(group);
  
      return 0;
  }
  
  /* Implements OFPFC_DELETE. */
  static enum ofperr
  delete_flows_loose(struct ofproto *ofproto, struct ofconn *ofconn,
                     const struct ofputil_flow_mod *fm,
                     const struct ofp_header *request)
  {
      struct list rules;
      enum ofperr error;
  
      error = collect_rules_loose(ofproto, fm->table_id, &fm->cr,
                                  fm->cookie, fm->cookie_mask,
                                  fm->out_port, &rules);
      return (error ? error
              : !list_is_empty(&rules) ? delete_flows__(ofproto, ofconn, request,
                                                        &rules)
              : 0);
  }
  
  /* Implements OFPFC_DELETE_STRICT. */
  static enum ofperr
  delete_flow_strict(struct ofproto *ofproto, struct ofconn *ofconn,
                     const struct ofputil_flow_mod *fm,
                     const struct ofp_header *request)
  {
      struct list rules;
      enum ofperr error;
  
      error = collect_rules_strict(ofproto, fm->table_id, &fm->cr,
                                   fm->cookie, fm->cookie_mask,
                                   fm->out_port, &rules);
      return (error ? error
              : list_is_singleton(&rules) ? delete_flows__(ofproto, ofconn,
                                                           request, &rules)
              : 0);
  }
  
  static void
  ofproto_rule_send_removed(struct rule *rule, uint8_t reason)
  {
      struct ofputil_flow_removed fr;
  
      if (ofproto_rule_is_hidden(rule) || !rule->send_flow_removed) {
          return;
      }
  
      fr.rule = rule->cr;
      fr.cookie = rule->flow_cookie;
      fr.reason = reason;
      calc_flow_duration__(rule->created, time_msec(),
                           &fr.duration_sec, &fr.duration_nsec);
      fr.idle_timeout = rule->idle_timeout;
      rule->ofproto->ofproto_class->rule_get_stats(rule, &fr.packet_count,
                                                   &fr.byte_count);
  
      connmgr_send_flow_removed(rule->ofproto->connmgr, &fr);
  }
  
  void
  ofproto_rule_update_used(struct rule *rule, long long int used)
  {
      if (used > rule->used) {
          struct eviction_group *evg = rule->eviction_group;
  
          rule->used = used;
          if (evg) {
              heap_change(&evg->rules, &rule->evg_node,
                          rule_eviction_priority(rule));
          }
      }
  }
  
  /* Sends an OpenFlow "flow removed" message with the given 'reason' (either
   * OFPRR_HARD_TIMEOUT or OFPRR_IDLE_TIMEOUT), and then removes 'rule' from its
   * ofproto.
   *
   * 'rule' must not have a pending operation (that is, 'rule->pending' must be
   * NULL).
   *
   * ofproto implementation ->run() functions should use this function to expire
   * OpenFlow flows. */
  void
  ofproto_rule_expire(struct rule *rule, uint8_t reason)
  {
      struct ofproto *ofproto = rule->ofproto;
      struct ofopgroup *group;
  
      assert(reason == OFPRR_HARD_TIMEOUT || reason == OFPRR_IDLE_TIMEOUT);
  
      ofproto_rule_send_removed(rule, reason);
  
      group = ofopgroup_create_unattached(ofproto);
      ofoperation_create(group, rule, OFOPERATION_DELETE, reason);
      oftable_remove_rule(rule);
      ofproto->ofproto_class->rule_destruct(rule);
      ofopgroup_submit(group);
  }
  
  static enum ofperr
  handle_flow_mod(struct ofconn *ofconn, const struct ofp_header *oh)
  {
      struct ofproto *ofproto = ofconn_get_ofproto(ofconn);
      struct ofputil_flow_mod fm;
      uint64_t ofpacts_stub[1024 / 8];
      struct ofpbuf ofpacts;
      enum ofperr error;
      long long int now;
  
      error = reject_slave_controller(ofconn);
      if (error) {
          goto exit;
      }
  
      ofpbuf_use_stub(&ofpacts, ofpacts_stub, sizeof ofpacts_stub);
      error = ofputil_decode_flow_mod(&fm, oh, ofconn_get_protocol(ofconn),
                                      &ofpacts);
      if (error) {
          goto exit_free_ofpacts;
      }
  
      if (fm.flags & OFPFF10_EMERG) {
      /* We do not support the OpenFlow 1.0 emergency flow cache, which is not
       * required in OpenFlow 1.0.1 and removed from OpenFlow 1.1. */
          /* We do not support the emergency flow cache.  It will hopefully get
           * dropped from OpenFlow in the near future.  There is no good error
           * code, so just state that the flow table is full. */
          error = OFPERR_OFPFMFC_ALL_TABLES_FULL;
      } else {
          error = handle_flow_mod__(ofconn_get_ofproto(ofconn), ofconn, &fm, oh);
      }
      if (error) {
          goto exit_free_ofpacts;
      }
  
      /* Record the operation for logging a summary report. */
      switch (fm.command) {
      case OFPFC_ADD:
          ofproto->n_add++;
          break;
  
      case OFPFC_MODIFY:
      case OFPFC_MODIFY_STRICT:
          ofproto->n_modify++;
          break;
  
      case OFPFC_DELETE:
      case OFPFC_DELETE_STRICT:
          ofproto->n_delete++;
          break;
      }
  
      now = time_msec();
      if (ofproto->next_op_report == LLONG_MAX) {
          ofproto->first_op = now;
          ofproto->next_op_report = MAX(now + 10 * 1000,
                                        ofproto->op_backoff);
          ofproto->op_backoff = ofproto->next_op_report + 60 * 1000;
      }
      ofproto->last_op = now;
  
  exit_free_ofpacts:
      ofpbuf_uninit(&ofpacts);
  exit:
      return error;
  }
  
  static enum ofperr
  handle_flow_mod__(struct ofproto *ofproto, struct ofconn *ofconn,
                    const struct ofputil_flow_mod *fm,
                    const struct ofp_header *oh)
  {
      if (ofproto->n_pending >= 50) {
          assert(!list_is_empty(&ofproto->pending));
          return OFPROTO_POSTPONE;
      }
  
      switch (fm->command) {
      case OFPFC_ADD:
          return add_flow(ofproto, ofconn, fm, oh);
  
      case OFPFC_MODIFY:
          return modify_flows_loose(ofproto, ofconn, fm, oh);
  
      case OFPFC_MODIFY_STRICT:
          return modify_flow_strict(ofproto, ofconn, fm, oh);
  
      case OFPFC_DELETE:
          return delete_flows_loose(ofproto, ofconn, fm, oh);
  
      case OFPFC_DELETE_STRICT:
          return delete_flow_strict(ofproto, ofconn, fm, oh);
  
      default:
          if (fm->command > 0xff) {
              VLOG_WARN_RL(&rl, "%s: flow_mod has explicit table_id but "
                           "flow_mod_table_id extension is not enabled",
                           ofproto->name);
          }
          return OFPERR_OFPFMFC_BAD_COMMAND;
      }
  }
  
  static enum ofperr
  handle_role_request(struct ofconn *ofconn, const struct ofp_header *oh)
  {
      const struct nx_role_request *nrr = ofpmsg_body(oh);
      struct nx_role_request *reply;
      struct ofpbuf *buf;
      uint32_t role;
  
      role = ntohl(nrr->role);
      if (role != NX_ROLE_OTHER && role != NX_ROLE_MASTER
          && role != NX_ROLE_SLAVE) {
          return OFPERR_OFPRRFC_BAD_ROLE;
      }
  
      if (ofconn_get_role(ofconn) != role
          && ofconn_has_pending_opgroups(ofconn)) {
          return OFPROTO_POSTPONE;
      }
  
      ofconn_set_role(ofconn, role);
  
      buf = ofpraw_alloc_reply(OFPRAW_NXT_ROLE_REPLY, oh, 0);
      reply = ofpbuf_put_zeros(buf, sizeof *reply);
      reply->role = htonl(role);
      ofconn_send_reply(ofconn, buf);
  
      return 0;
  }
  
  static enum ofperr
  handle_nxt_flow_mod_table_id(struct ofconn *ofconn,
                               const struct ofp_header *oh)
  {
      const struct nx_flow_mod_table_id *msg = ofpmsg_body(oh);
      enum ofputil_protocol cur, next;
  
      cur = ofconn_get_protocol(ofconn);
      next = ofputil_protocol_set_tid(cur, msg->set != 0);
      ofconn_set_protocol(ofconn, next);
  
      return 0;
  }
  
  static enum ofperr
  handle_nxt_set_flow_format(struct ofconn *ofconn, const struct ofp_header *oh)
  {
      const struct nx_set_flow_format *msg = ofpmsg_body(oh);
      enum ofputil_protocol cur, next;
      enum ofputil_protocol next_base;
  
      next_base = ofputil_nx_flow_format_to_protocol(ntohl(msg->format));
      if (!next_base) {
          return OFPERR_OFPBRC_EPERM;
      }
  
      cur = ofconn_get_protocol(ofconn);
      next = ofputil_protocol_set_base(cur, next_base);
      if (cur != next && ofconn_has_pending_opgroups(ofconn)) {
          /* Avoid sending async messages in surprising protocol. */
          return OFPROTO_POSTPONE;
      }
  
      ofconn_set_protocol(ofconn, next);
      return 0;
  }
  
  static enum ofperr
  handle_nxt_set_packet_in_format(struct ofconn *ofconn,
                                  const struct ofp_header *oh)
  {
      const struct nx_set_packet_in_format *msg = ofpmsg_body(oh);
      uint32_t format;
  
      format = ntohl(msg->format);
      if (format != NXPIF_OPENFLOW10 && format != NXPIF_NXM) {
          return OFPERR_OFPBRC_EPERM;
      }
  
      if (format != ofconn_get_packet_in_format(ofconn)
          && ofconn_has_pending_opgroups(ofconn)) {
          /* Avoid sending async message in surprsing packet in format. */
          return OFPROTO_POSTPONE;
      }
  
      ofconn_set_packet_in_format(ofconn, format);
      return 0;
  }
  
  static enum ofperr
  handle_nxt_set_async_config(struct ofconn *ofconn, const struct ofp_header *oh)
  {
      const struct nx_async_config *msg = ofpmsg_body(oh);
      uint32_t master[OAM_N_TYPES];
      uint32_t slave[OAM_N_TYPES];
  
      master[OAM_PACKET_IN] = ntohl(msg->packet_in_mask[0]);
      master[OAM_PORT_STATUS] = ntohl(msg->port_status_mask[0]);
      master[OAM_FLOW_REMOVED] = ntohl(msg->flow_removed_mask[0]);
  
      slave[OAM_PACKET_IN] = ntohl(msg->packet_in_mask[1]);
      slave[OAM_PORT_STATUS] = ntohl(msg->port_status_mask[1]);
      slave[OAM_FLOW_REMOVED] = ntohl(msg->flow_removed_mask[1]);
  
      ofconn_set_async_config(ofconn, master, slave);
      if (ofconn_get_type(ofconn) == OFCONN_SERVICE &&
          !ofconn_get_miss_send_len(ofconn)) {
          ofconn_set_miss_send_len(ofconn, OFP_DEFAULT_MISS_SEND_LEN);
      }
  
      return 0;
  }
  
  static enum ofperr
  handle_nxt_set_controller_id(struct ofconn *ofconn,
                               const struct ofp_header *oh)
  {
      const struct nx_controller_id *nci = ofpmsg_body(oh);
  
      if (!is_all_zeros(nci->zero, sizeof nci->zero)) {
          return OFPERR_NXBRC_MUST_BE_ZERO;
      }
  
      ofconn_set_controller_id(ofconn, ntohs(nci->controller_id));
      return 0;
  }
  
  static enum ofperr
  handle_barrier_request(struct ofconn *ofconn, const struct ofp_header *oh)
  {
      struct ofpbuf *buf;
  
      if (ofconn_has_pending_opgroups(ofconn)) {
          return OFPROTO_POSTPONE;
      }
  
      buf = ofpraw_alloc_reply((oh->version == OFP10_VERSION
                                ? OFPRAW_OFPT10_BARRIER_REPLY
                                : OFPRAW_OFPT11_BARRIER_REPLY), oh, 0);
      ofconn_send_reply(ofconn, buf);
      return 0;
  }
  
  static void
  ofproto_compose_flow_refresh_update(const struct rule *rule,
                                      enum nx_flow_monitor_flags flags,
                                      struct list *msgs)
  {
      struct ofoperation *op = rule->pending;
      struct ofputil_flow_update fu;
  
      if (op && op->type == OFOPERATION_ADD && !op->victim) {
          /* We'll report the final flow when the operation completes.  Reporting
           * it now would cause a duplicate report later. */
          return;
      }
  
      fu.event = (flags & (NXFMF_INITIAL | NXFMF_ADD)
                  ? NXFME_ADDED : NXFME_MODIFIED);
      fu.reason = 0;
      fu.idle_timeout = rule->idle_timeout;
      fu.hard_timeout = rule->hard_timeout;
      fu.table_id = rule->table_id;
      fu.cookie = rule->flow_cookie;
      fu.match = (struct cls_rule *) &rule->cr;
      if (!(flags & NXFMF_ACTIONS)) {
          fu.ofpacts = NULL;
          fu.ofpacts_len = 0;
      } else if (!op) {
          fu.ofpacts = rule->ofpacts;
          fu.ofpacts_len = rule->ofpacts_len;
      } else {
          /* An operation is in progress.  Use the previous version of the flow's
           * actions, so that when the operation commits we report the change. */
          switch (op->type) {
          case OFOPERATION_ADD:
              /* We already verified that there was a victim. */
              fu.ofpacts = op->victim->ofpacts;
              fu.ofpacts_len = op->victim->ofpacts_len;
              break;
  
          case OFOPERATION_MODIFY:
              if (op->ofpacts) {
                  fu.ofpacts = op->ofpacts;
                  fu.ofpacts_len = op->ofpacts_len;
              } else {
                  fu.ofpacts = rule->ofpacts;
                  fu.ofpacts_len = rule->ofpacts_len;
              }
              break;
  
          case OFOPERATION_DELETE:
              fu.ofpacts = rule->ofpacts;
              fu.ofpacts_len = rule->ofpacts_len;
              break;
  
          default:
              NOT_REACHED();
          }
      }
  
      if (list_is_empty(msgs)) {
          ofputil_start_flow_update(msgs);
      }
      ofputil_append_flow_update(&fu, msgs);
  }
  
  void
  ofmonitor_compose_refresh_updates(struct list *rules, struct list *msgs)
  {
      struct rule *rule;
  
      LIST_FOR_EACH (rule, ofproto_node, rules) {
          enum nx_flow_monitor_flags flags = rule->monitor_flags;
          rule->monitor_flags = 0;
  
          ofproto_compose_flow_refresh_update(rule, flags, msgs);
      }
  }
  
  static void
  ofproto_collect_ofmonitor_refresh_rule(const struct ofmonitor *m,
                                         struct rule *rule, uint64_t seqno,
                                         struct list *rules)
  {
      enum nx_flow_monitor_flags update;
  
      if (ofproto_rule_is_hidden(rule)) {
          return;
      }
  
      if (!(rule->pending
            ? ofoperation_has_out_port(rule->pending, m->out_port)
            : ofproto_rule_has_out_port(rule, m->out_port))) {
          return;
      }
  
      if (seqno) {
          if (rule->add_seqno > seqno) {
              update = NXFMF_ADD | NXFMF_MODIFY;
          } else if (rule->modify_seqno > seqno) {
              update = NXFMF_MODIFY;
          } else {
              return;
          }
  
          if (!(m->flags & update)) {
              return;
          }
      } else {
          update = NXFMF_INITIAL;
      }
  
      if (!rule->monitor_flags) {
          list_push_back(rules, &rule->ofproto_node);
      }
      rule->monitor_flags |= update | (m->flags & NXFMF_ACTIONS);
  }
  
  static void
  ofproto_collect_ofmonitor_refresh_rules(const struct ofmonitor *m,
                                          uint64_t seqno,
                                          struct list *rules)
  {
      const struct ofproto *ofproto = ofconn_get_ofproto(m->ofconn);
      const struct ofoperation *op;
      const struct oftable *table;
  
      FOR_EACH_MATCHING_TABLE (table, m->table_id, ofproto) {
          struct cls_cursor cursor;
          struct rule *rule;
  
          cls_cursor_init(&cursor, &table->cls, &m->match);
          CLS_CURSOR_FOR_EACH (rule, cr, &cursor) {
              assert(!rule->pending); /* XXX */
              ofproto_collect_ofmonitor_refresh_rule(m, rule, seqno, rules);
          }
      }
  
      HMAP_FOR_EACH (op, hmap_node, &ofproto->deletions) {
          struct rule *rule = op->rule;
  
          if (((m->table_id == 0xff
                ? !(ofproto->tables[rule->table_id].flags & OFTABLE_HIDDEN)
                : m->table_id == rule->table_id))
              && cls_rule_is_loose_match(&rule->cr, &m->match)) {
              ofproto_collect_ofmonitor_refresh_rule(m, rule, seqno, rules);
          }
      }
  }
  
  static void
  ofproto_collect_ofmonitor_initial_rules(struct ofmonitor *m,
                                          struct list *rules)
  {
      if (m->flags & NXFMF_INITIAL) {
          ofproto_collect_ofmonitor_refresh_rules(m, 0, rules);
      }
  }
  
  void
  ofmonitor_collect_resume_rules(struct ofmonitor *m,
                                 uint64_t seqno, struct list *rules)
  {
      ofproto_collect_ofmonitor_refresh_rules(m, seqno, rules);
  }
  
  static enum ofperr
  handle_flow_monitor_request(struct ofconn *ofconn, const struct ofp_header *oh)
  {
      struct ofproto *ofproto = ofconn_get_ofproto(ofconn);
      struct ofmonitor **monitors;
      size_t n_monitors, allocated_monitors;
      struct list replies;
      enum ofperr error;
      struct list rules;
      struct ofpbuf b;
      size_t i;
  
      error = 0;
      ofpbuf_use_const(&b, oh, ntohs(oh->length));
      monitors = NULL;
      n_monitors = allocated_monitors = 0;
      for (;;) {
          struct ofputil_flow_monitor_request request;
          struct ofmonitor *m;
          int retval;
  
          retval = ofputil_decode_flow_monitor_request(&request, &b);
          if (retval == EOF) {
              break;
          } else if (retval) {
              error = retval;
              goto error;
          }
  
          if (request.table_id != 0xff
              && request.table_id >= ofproto->n_tables) {
              error = OFPERR_OFPBRC_BAD_TABLE_ID;
              goto error;
          }
  
          error = ofmonitor_create(&request, ofconn, &m);
          if (error) {
              goto error;
          }
  
          if (n_monitors >= allocated_monitors) {
              monitors = x2nrealloc(monitors, &allocated_monitors,
                                    sizeof *monitors);
          }
          monitors[n_monitors++] = m;
      }
  
      list_init(&rules);
      for (i = 0; i < n_monitors; i++) {
          ofproto_collect_ofmonitor_initial_rules(monitors[i], &rules);
      }
  
      ofpmp_init(&replies, oh);
      ofmonitor_compose_refresh_updates(&rules, &replies);
      ofconn_send_replies(ofconn, &replies);
  
      free(monitors);
  
      return 0;
  
  error:
      for (i = 0; i < n_monitors; i++) {
          ofmonitor_destroy(monitors[i]);
      }
      free(monitors);
      return error;
  }
  
  static enum ofperr
  handle_flow_monitor_cancel(struct ofconn *ofconn, const struct ofp_header *oh)
  {
      struct ofmonitor *m;
      uint32_t id;
  
      id = ofputil_decode_flow_monitor_cancel(oh);
      m = ofmonitor_lookup(ofconn, id);
      if (!m) {
          return OFPERR_NXBRC_FM_BAD_ID;
      }
  
      ofmonitor_destroy(m);
      return 0;
  }
  
  static enum ofperr
  handle_openflow__(struct ofconn *ofconn, const struct ofpbuf *msg)
  {
      const struct ofp_header *oh = msg->data;
      enum ofptype type;
      enum ofperr error;
  
      error = ofptype_decode(&type, oh);
      if (error) {
          return error;
      }
  
      switch (type) {
          /* OpenFlow requests. */
      case OFPTYPE_ECHO_REQUEST:
          return handle_echo_request(ofconn, oh);
  
      case OFPTYPE_FEATURES_REQUEST:
          return handle_features_request(ofconn, oh);
  
      case OFPTYPE_GET_CONFIG_REQUEST:
          return handle_get_config_request(ofconn, oh);
  
      case OFPTYPE_SET_CONFIG:
          return handle_set_config(ofconn, oh);
  
      case OFPTYPE_PACKET_OUT:
          return handle_packet_out(ofconn, oh);
  
      case OFPTYPE_PORT_MOD:
          return handle_port_mod(ofconn, oh);
  
      case OFPTYPE_FLOW_MOD:
          return handle_flow_mod(ofconn, oh);
  
      case OFPTYPE_BARRIER_REQUEST:
          return handle_barrier_request(ofconn, oh);
  
          /* OpenFlow replies. */
      case OFPTYPE_ECHO_REPLY:
          return 0;
  
          /* Nicira extension requests. */
      case OFPTYPE_ROLE_REQUEST:
          return handle_role_request(ofconn, oh);
  
      case OFPTYPE_FLOW_MOD_TABLE_ID:
          return handle_nxt_flow_mod_table_id(ofconn, oh);
  
      case OFPTYPE_SET_FLOW_FORMAT:
          return handle_nxt_set_flow_format(ofconn, oh);
  
      case OFPTYPE_SET_PACKET_IN_FORMAT:
          return handle_nxt_set_packet_in_format(ofconn, oh);
  
      case OFPTYPE_SET_CONTROLLER_ID:
          return handle_nxt_set_controller_id(ofconn, oh);
  
      case OFPTYPE_FLOW_AGE:
          /* Nothing to do. */
          return 0;
  
      case OFPTYPE_FLOW_MONITOR_CANCEL:
          return handle_flow_monitor_cancel(ofconn, oh);
  
      case OFPTYPE_SET_ASYNC_CONFIG:
          return handle_nxt_set_async_config(ofconn, oh);
  
          /* Statistics requests. */
      case OFPTYPE_DESC_STATS_REQUEST:
          return handle_desc_stats_request(ofconn, oh);
  
      case OFPTYPE_FLOW_STATS_REQUEST:
          return handle_flow_stats_request(ofconn, oh);
  
      case OFPTYPE_AGGREGATE_STATS_REQUEST:
          return handle_aggregate_stats_request(ofconn, oh);
  
      case OFPTYPE_TABLE_STATS_REQUEST:
          return handle_table_stats_request(ofconn, oh);
  
      case OFPTYPE_PORT_STATS_REQUEST:
          return handle_port_stats_request(ofconn, oh);
  
      case OFPTYPE_QUEUE_STATS_REQUEST:
          return handle_queue_stats_request(ofconn, oh);
  
      case OFPTYPE_PORT_DESC_STATS_REQUEST:
          return handle_port_desc_stats_request(ofconn, oh);
  
      case OFPTYPE_FLOW_MONITOR_STATS_REQUEST:
          return handle_flow_monitor_request(ofconn, oh);
  
      case OFPTYPE_HELLO:
      case OFPTYPE_ERROR:
      case OFPTYPE_FEATURES_REPLY:
      case OFPTYPE_GET_CONFIG_REPLY:
      case OFPTYPE_PACKET_IN:
      case OFPTYPE_FLOW_REMOVED:
      case OFPTYPE_PORT_STATUS:
      case OFPTYPE_BARRIER_REPLY:
      case OFPTYPE_DESC_STATS_REPLY:
      case OFPTYPE_FLOW_STATS_REPLY:
      case OFPTYPE_QUEUE_STATS_REPLY:
      case OFPTYPE_PORT_STATS_REPLY:
      case OFPTYPE_TABLE_STATS_REPLY:
      case OFPTYPE_AGGREGATE_STATS_REPLY:
      case OFPTYPE_PORT_DESC_STATS_REPLY:
      case OFPTYPE_ROLE_REPLY:
      case OFPTYPE_FLOW_MONITOR_PAUSED:
      case OFPTYPE_FLOW_MONITOR_RESUMED:
      case OFPTYPE_FLOW_MONITOR_STATS_REPLY:
      default:
          return OFPERR_OFPBRC_BAD_TYPE;
      }
  }
  
  static bool
  handle_openflow(struct ofconn *ofconn, struct ofpbuf *ofp_msg)
  {
      int error = handle_openflow__(ofconn, ofp_msg);
      if (error && error != OFPROTO_POSTPONE) {
          ofconn_send_error(ofconn, ofp_msg->data, error);
      }
      COVERAGE_INC(ofproto_recv_openflow);
      return error != OFPROTO_POSTPONE;
  }
  
  /* Asynchronous operations. */
  
  /* Creates and returns a new ofopgroup that is not associated with any
   * OpenFlow connection.
   *
   * The caller should add operations to the returned group with
   * ofoperation_create() and then submit it with ofopgroup_submit(). */
  static struct ofopgroup *
  ofopgroup_create_unattached(struct ofproto *ofproto)
  {
      struct ofopgroup *group = xzalloc(sizeof *group);
      group->ofproto = ofproto;
      list_init(&group->ofproto_node);
      list_init(&group->ops);
      list_init(&group->ofconn_node);
      return group;
  }
  
  /* Creates and returns a new ofopgroup for 'ofproto'.
   *
   * If 'ofconn' is NULL, the new ofopgroup is not associated with any OpenFlow
   * connection.  The 'request' and 'buffer_id' arguments are ignored.
   *
   * If 'ofconn' is nonnull, then the new ofopgroup is associated with 'ofconn'.
   * If the ofopgroup eventually fails, then the error reply will include
   * 'request'.  If the ofopgroup eventually succeeds, then the packet with
   * buffer id 'buffer_id' on 'ofconn' will be sent by 'ofconn''s ofproto.
   *
   * The caller should add operations to the returned group with
   * ofoperation_create() and then submit it with ofopgroup_submit(). */
  static struct ofopgroup *
  ofopgroup_create(struct ofproto *ofproto, struct ofconn *ofconn,
                   const struct ofp_header *request, uint32_t buffer_id)
  {
      struct ofopgroup *group = ofopgroup_create_unattached(ofproto);
      if (ofconn) {
          size_t request_len = ntohs(request->length);
  
          assert(ofconn_get_ofproto(ofconn) == ofproto);
  
          ofconn_add_opgroup(ofconn, &group->ofconn_node);
          group->ofconn = ofconn;
          group->request = xmemdup(request, MIN(request_len, 64));
          group->buffer_id = buffer_id;
      }
      return group;
  }
  
  /* Submits 'group' for processing.
   *
   * If 'group' contains no operations (e.g. none were ever added, or all of the
   * ones that were added completed synchronously), then it is destroyed
   * immediately.  Otherwise it is added to the ofproto's list of pending
   * groups. */
  static void
  ofopgroup_submit(struct ofopgroup *group)
  {
      if (!group->n_running) {
          ofopgroup_complete(group);
      } else {
          list_push_back(&group->ofproto->pending, &group->ofproto_node);
          group->ofproto->n_pending++;
      }
  }
  
  static void
  ofopgroup_complete(struct ofopgroup *group)
  {
      struct ofproto *ofproto = group->ofproto;
  
      struct ofconn *abbrev_ofconn;
      ovs_be32 abbrev_xid;
  
      struct ofoperation *op, *next_op;
      int error;
  
      assert(!group->n_running);
  
      error = 0;
      LIST_FOR_EACH (op, group_node, &group->ops) {
          if (op->error) {
              error = op->error;
              break;
          }
      }
  
      if (!error && group->ofconn && group->buffer_id != UINT32_MAX) {
          LIST_FOR_EACH (op, group_node, &group->ops) {
              if (op->type != OFOPERATION_DELETE) {
                  struct ofpbuf *packet;
                  uint16_t in_port;
  
                  error = ofconn_pktbuf_retrieve(group->ofconn, group->buffer_id,
                                                 &packet, &in_port);
                  if (packet) {
                      assert(!error);
                      error = rule_execute(op->rule, in_port, packet);
                  }
                  break;
              }
          }
      }
  
      if (!error && !list_is_empty(&group->ofconn_node)) {
          abbrev_ofconn = group->ofconn;
          abbrev_xid = group->request->xid;
      } else {
          abbrev_ofconn = NULL;
          abbrev_xid = htonl(0);
      }
      LIST_FOR_EACH_SAFE (op, next_op, group_node, &group->ops) {
          struct rule *rule = op->rule;
  
          if (!op->error && !ofproto_rule_is_hidden(rule)) {
              /* Check that we can just cast from ofoperation_type to
               * nx_flow_update_event. */
              BUILD_ASSERT_DECL((enum nx_flow_update_event) OFOPERATION_ADD
                                == NXFME_ADDED);
              BUILD_ASSERT_DECL((enum nx_flow_update_event) OFOPERATION_DELETE
                                == NXFME_DELETED);
              BUILD_ASSERT_DECL((enum nx_flow_update_event) OFOPERATION_MODIFY
                                == NXFME_MODIFIED);
  
              ofmonitor_report(ofproto->connmgr, rule,
                               (enum nx_flow_update_event) op->type,
                               op->reason, abbrev_ofconn, abbrev_xid);
          }
  
          rule->pending = NULL;
  
          switch (op->type) {
          case OFOPERATION_ADD:
              if (!op->error) {
                  ofproto_rule_destroy__(op->victim);
                  if ((rule->cr.wc.vlan_tci_mask & htons(VLAN_VID_MASK))
                      == htons(VLAN_VID_MASK)) {
                      if (ofproto->vlan_bitmap) {
                          uint16_t vid = vlan_tci_to_vid(rule->cr.flow.vlan_tci);
  
                          if (!bitmap_is_set(ofproto->vlan_bitmap, vid)) {
                              bitmap_set1(ofproto->vlan_bitmap, vid);
                              ofproto->vlans_changed = true;
                          }
                      } else {
                          ofproto->vlans_changed = true;
                      }
                  }
              } else {
                  oftable_substitute_rule(rule, op->victim);
                  ofproto_rule_destroy__(rule);
              }
              break;
  
          case OFOPERATION_DELETE:
              assert(!op->error);
              ofproto_rule_destroy__(rule);
              op->rule = NULL;
              break;
  
          case OFOPERATION_MODIFY:
              if (!op->error) {
                  rule->modified = time_msec();
              } else {
                  rule->flow_cookie = op->flow_cookie;
                  if (op->ofpacts) {
                      free(rule->ofpacts);
                      rule->ofpacts = op->ofpacts;
                      rule->ofpacts_len = op->ofpacts_len;
                      op->ofpacts = NULL;
                      op->ofpacts_len = 0;
                  }
              }
              break;
  
          default:
              NOT_REACHED();
          }
  
          ofoperation_destroy(op);
      }
  
      ofmonitor_flush(ofproto->connmgr);
  
      if (!list_is_empty(&group->ofproto_node)) {
          assert(ofproto->n_pending > 0);
          ofproto->n_pending--;
          list_remove(&group->ofproto_node);
      }
      if (!list_is_empty(&group->ofconn_node)) {
          list_remove(&group->ofconn_node);
          if (error) {
              ofconn_send_error(group->ofconn, group->request, error);
          }
          connmgr_retry(ofproto->connmgr);
      }
      free(group->request);
      free(group);
  }
  
  /* Initiates a new operation on 'rule', of the specified 'type', within
   * 'group'.  Prior to calling, 'rule' must not have any pending operation.
   *
   * For a 'type' of OFOPERATION_DELETE, 'reason' should specify the reason that
   * the flow is being deleted.  For other 'type's, 'reason' is ignored (use 0).
   *
   * Returns the newly created ofoperation (which is also available as
   * rule->pending). */
  static struct ofoperation *
  ofoperation_create(struct ofopgroup *group, struct rule *rule,
                     enum ofoperation_type type,
                     enum ofp_flow_removed_reason reason)
  {
      struct ofproto *ofproto = group->ofproto;
      struct ofoperation *op;
  
      assert(!rule->pending);
  
      op = rule->pending = xzalloc(sizeof *op);
      op->group = group;
      list_push_back(&group->ops, &op->group_node);
      op->rule = rule;
      op->type = type;
      op->reason = reason;
      op->flow_cookie = rule->flow_cookie;
  
      group->n_running++;
  
      if (type == OFOPERATION_DELETE) {
          hmap_insert(&ofproto->deletions, &op->hmap_node,
                      cls_rule_hash(&rule->cr, rule->table_id));
      }
  
      return op;
  }
  
  static void
  ofoperation_destroy(struct ofoperation *op)
  {
      struct ofopgroup *group = op->group;
  
      if (op->rule) {
          op->rule->pending = NULL;
      }
      if (op->type == OFOPERATION_DELETE) {
          hmap_remove(&group->ofproto->deletions, &op->hmap_node);
      }
      list_remove(&op->group_node);
      free(op->ofpacts);
      free(op);
  }
  
  /* Indicates that 'op' completed with status 'error', which is either 0 to
   * indicate success or an OpenFlow error code on failure.
   *
   * If 'error' is 0, indicating success, the operation will be committed
   * permanently to the flow table.  There is one interesting subcase:
   *
   *   - If 'op' is an "add flow" operation that is replacing an existing rule in
   *     the flow table (the "victim" rule) by a new one, then the caller must
   *     have uninitialized any derived state in the victim rule, as in step 5 in
   *     the "Life Cycle" in ofproto/ofproto-provider.h.  ofoperation_complete()
   *     performs steps 6 and 7 for the victim rule, most notably by calling its
   *     ->rule_dealloc() function.
   *
   * If 'error' is nonzero, then generally the operation will be rolled back:
   *
   *   - If 'op' is an "add flow" operation, ofproto removes the new rule or
   *     restores the original rule.  The caller must have uninitialized any
   *     derived state in the new rule, as in step 5 of in the "Life Cycle" in
   *     ofproto/ofproto-provider.h.  ofoperation_complete() performs steps 6 and
   *     and 7 for the new rule, calling its ->rule_dealloc() function.
   *
   *   - If 'op' is a "modify flow" operation, ofproto restores the original
   *     actions.
   *
   *   - 'op' must not be a "delete flow" operation.  Removing a rule is not
   *     allowed to fail.  It must always succeed.
   *
   * Please see the large comment in ofproto/ofproto-provider.h titled
   * "Asynchronous Operation Support" for more information. */
  void
  ofoperation_complete(struct ofoperation *op, enum ofperr error)
  {
      struct ofopgroup *group = op->group;
  
      assert(op->rule->pending == op);
      assert(group->n_running > 0);
      assert(!error || op->type != OFOPERATION_DELETE);
  
      op->error = error;
      if (!--group->n_running && !list_is_empty(&group->ofproto_node)) {
          ofopgroup_complete(group);
      }
  }
  
  struct rule *
  ofoperation_get_victim(struct ofoperation *op)
  {
      assert(op->type == OFOPERATION_ADD);
      return op->victim;
  }
  
  static uint64_t
  pick_datapath_id(const struct ofproto *ofproto)
  {
      const struct ofport *port;
  
      port = ofproto_get_port(ofproto, OFPP_LOCAL);
      if (port) {
          uint8_t ea[ETH_ADDR_LEN];
          int error;
  
          error = netdev_get_etheraddr(port->netdev, ea);
          if (!error) {
              return eth_addr_to_uint64(ea);
          }
          VLOG_WARN("%s: could not get MAC address for %s (%s)",
                    ofproto->name, netdev_get_name(port->netdev),
                    strerror(error));
      }
      return ofproto->fallback_dpid;
  }
  
  static uint64_t
  pick_fallback_dpid(void)
  {
      uint8_t ea[ETH_ADDR_LEN];
      eth_addr_nicira_random(ea);
      return eth_addr_to_uint64(ea);
  }
  
  /* Table overflow policy. */
  
  /* Chooses and returns a rule to evict from 'table'.  Returns NULL if the table
   * is not configured to evict rules or if the table contains no evictable
   * rules.  (Rules with 'evictable' set to false or with no timeouts are not
   * evictable.) */
  static struct rule *
  choose_rule_to_evict(struct oftable *table)
  {
      struct eviction_group *evg;
  
      if (!table->eviction_fields) {
          return NULL;
      }
  
      /* In the common case, the outer and inner loops here will each be entered
       * exactly once:
       *
       *   - The inner loop normally "return"s in its first iteration.  If the
       *     eviction group has any evictable rules, then it always returns in
       *     some iteration.
       *
       *   - The outer loop only iterates more than once if the largest eviction
       *     group has no evictable rules.
       *
       *   - The outer loop can exit only if table's 'max_flows' is all filled up
       *     by unevictable rules'. */
      HEAP_FOR_EACH (evg, size_node, &table->eviction_groups_by_size) {
          struct rule *rule;
  
          HEAP_FOR_EACH (rule, evg_node, &evg->rules) {
              if (rule->evictable) {
                  return rule;
              }
          }
      }
  
      return NULL;
  }
  
  /* Searches 'ofproto' for tables that have more flows than their configured
   * maximum and that have flow eviction enabled, and evicts as many flows as
   * necessary and currently feasible from them.
   *
   * This triggers only when an OpenFlow table has N flows in it and then the
   * client configures a maximum number of flows less than N. */
  static void
  ofproto_evict(struct ofproto *ofproto)
  {
      struct ofopgroup *group;
      struct oftable *table;
  
      group = ofopgroup_create_unattached(ofproto);
      OFPROTO_FOR_EACH_TABLE (table, ofproto) {
          while (classifier_count(&table->cls) > table->max_flows
                 && table->eviction_fields) {
              struct rule *rule;
  
              rule = choose_rule_to_evict(table);
              if (!rule || rule->pending) {
                  break;
              }
  
              ofoperation_create(group, rule,
                                 OFOPERATION_DELETE, OFPRR_EVICTION);
              oftable_remove_rule(rule);
              ofproto->ofproto_class->rule_destruct(rule);
          }
      }
      ofopgroup_submit(group);
  }
  
  /* Eviction groups. */
  
  /* Returns the priority to use for an eviction_group that contains 'n_rules'
   * rules.  The priority contains low-order random bits to ensure that eviction
   * groups with the same number of rules are prioritized randomly. */
  static uint32_t
  eviction_group_priority(size_t n_rules)
  {
      uint16_t size = MIN(UINT16_MAX, n_rules);
      return (size << 16) | random_uint16();
  }
  
  /* Updates 'evg', an eviction_group within 'table', following a change that
   * adds or removes rules in 'evg'. */
  static void
  eviction_group_resized(struct oftable *table, struct eviction_group *evg)
  {
      heap_change(&table->eviction_groups_by_size, &evg->size_node,
                  eviction_group_priority(heap_count(&evg->rules)));
  }
  
  /* Destroys 'evg', an eviction_group within 'table':
   *
   *   - Removes all the rules, if any, from 'evg'.  (It doesn't destroy the
   *     rules themselves, just removes them from the eviction group.)
   *
   *   - Removes 'evg' from 'table'.
   *
   *   - Frees 'evg'. */
  static void
  eviction_group_destroy(struct oftable *table, struct eviction_group *evg)
  {
      while (!heap_is_empty(&evg->rules)) {
          struct rule *rule;
  
          rule = CONTAINER_OF(heap_pop(&evg->rules), struct rule, evg_node);
          rule->eviction_group = NULL;
      }
      hmap_remove(&table->eviction_groups_by_id, &evg->id_node);
      heap_remove(&table->eviction_groups_by_size, &evg->size_node);
      heap_destroy(&evg->rules);
      free(evg);
  }
  
  /* Removes 'rule' from its eviction group, if any. */
  static void
  eviction_group_remove_rule(struct rule *rule)
  {
      if (rule->eviction_group) {
          struct oftable *table = &rule->ofproto->tables[rule->table_id];
          struct eviction_group *evg = rule->eviction_group;
  
          rule->eviction_group = NULL;
          heap_remove(&evg->rules, &rule->evg_node);
          if (heap_is_empty(&evg->rules)) {
              eviction_group_destroy(table, evg);
          } else {
              eviction_group_resized(table, evg);
          }
      }
  }
  
  /* Hashes the 'rule''s values for the eviction_fields of 'rule''s table, and
   * returns the hash value. */
  static uint32_t
  eviction_group_hash_rule(struct rule *rule)
  {
      struct oftable *table = &rule->ofproto->tables[rule->table_id];
      const struct mf_subfield *sf;
      uint32_t hash;
  
      hash = table->eviction_group_id_basis;
      for (sf = table->eviction_fields;
           sf < &table->eviction_fields[table->n_eviction_fields];
           sf++)
      {
          if (mf_are_prereqs_ok(sf->field, &rule->cr.flow)) {
              union mf_value value;
  
              mf_get_value(sf->field, &rule->cr.flow, &value);
              if (sf->ofs) {
                  bitwise_zero(&value, sf->field->n_bytes, 0, sf->ofs);
              }
              if (sf->ofs + sf->n_bits < sf->field->n_bytes * 8) {
                  unsigned int start = sf->ofs + sf->n_bits;
                  bitwise_zero(&value, sf->field->n_bytes, start,
                               sf->field->n_bytes * 8 - start);
              }
              hash = hash_bytes(&value, sf->field->n_bytes, hash);
          } else {
              hash = hash_int(hash, 0);
          }
      }
  
      return hash;
  }
  
  /* Returns an eviction group within 'table' with the given 'id', creating one
   * if necessary. */
  static struct eviction_group *
  eviction_group_find(struct oftable *table, uint32_t id)
  {
      struct eviction_group *evg;
  
      HMAP_FOR_EACH_WITH_HASH (evg, id_node, id, &table->eviction_groups_by_id) {
          return evg;
      }
  
      evg = xmalloc(sizeof *evg);
      hmap_insert(&table->eviction_groups_by_id, &evg->id_node, id);
      heap_insert(&table->eviction_groups_by_size, &evg->size_node,
                  eviction_group_priority(0));
      heap_init(&evg->rules);
  
      return evg;
  }
  
  /* Returns an eviction priority for 'rule'.  The return value should be
   * interpreted so that higher priorities make a rule more attractive candidates
   * for eviction. */
  static uint32_t
  rule_eviction_priority(struct rule *rule)
  {
      long long int hard_expiration;
      long long int idle_expiration;
      long long int expiration;
      uint32_t expiration_offset;
  
      /* Calculate time of expiration. */
      hard_expiration = (rule->hard_timeout
                         ? rule->modified + rule->hard_timeout * 1000
                         : LLONG_MAX);
      idle_expiration = (rule->idle_timeout
                         ? rule->used + rule->idle_timeout * 1000
                         : LLONG_MAX);
      expiration = MIN(hard_expiration, idle_expiration);
      if (expiration == LLONG_MAX) {
          return 0;
      }
  
      /* Calculate the time of expiration as a number of (approximate) seconds
       * after program startup.
       *
       * This should work OK for program runs that last UINT32_MAX seconds or
       * less.  Therefore, please restart OVS at least once every 136 years. */
      expiration_offset = (expiration >> 10) - (time_boot_msec() >> 10);
  
      /* Invert the expiration offset because we're using a max-heap. */
      return UINT32_MAX - expiration_offset;
  }
  
  /* Adds 'rule' to an appropriate eviction group for its oftable's
   * configuration.  Does nothing if 'rule''s oftable doesn't have eviction
   * enabled, or if 'rule' is a permanent rule (one that will never expire on its
   * own).
   *
   * The caller must ensure that 'rule' is not already in an eviction group. */
  static void
  eviction_group_add_rule(struct rule *rule)
  {
      struct ofproto *ofproto = rule->ofproto;
      struct oftable *table = &ofproto->tables[rule->table_id];
  
      if (table->eviction_fields
          && (rule->hard_timeout || rule->idle_timeout)) {
          struct eviction_group *evg;
  
          evg = eviction_group_find(table, eviction_group_hash_rule(rule));
  
          rule->eviction_group = evg;
          heap_insert(&evg->rules, &rule->evg_node,
                      rule_eviction_priority(rule));
          eviction_group_resized(table, evg);
      }
  }
  
  /* oftables. */
  
  /* Initializes 'table'. */
  static void
  oftable_init(struct oftable *table)
  {
      memset(table, 0, sizeof *table);
      classifier_init(&table->cls);
      table->max_flows = UINT_MAX;
  }
  
  /* Destroys 'table', including its classifier and eviction groups.
   *
   * The caller is responsible for freeing 'table' itself. */
  static void
  oftable_destroy(struct oftable *table)
  {
      assert(classifier_is_empty(&table->cls));
      oftable_disable_eviction(table);
      classifier_destroy(&table->cls);
      free(table->name);
  }
  
  /* Changes the name of 'table' to 'name'.  If 'name' is NULL or the empty
   * string, then 'table' will use its default name.
   *
   * This only affects the name exposed for a table exposed through the OpenFlow
   * OFPST_TABLE (as printed by "ovs-ofctl dump-tables"). */
  static void
  oftable_set_name(struct oftable *table, const char *name)
  {
      if (name && name[0]) {
          int len = strnlen(name, OFP_MAX_TABLE_NAME_LEN);
          if (!table->name || strncmp(name, table->name, len)) {
              free(table->name);
              table->name = xmemdup0(name, len);
          }
      } else {
          free(table->name);
          table->name = NULL;
      }
  }
  
  /* oftables support a choice of two policies when adding a rule would cause the
   * number of flows in the table to exceed the configured maximum number: either
   * they can refuse to add the new flow or they can evict some existing flow.
   * This function configures the former policy on 'table'. */
  static void
  oftable_disable_eviction(struct oftable *table)
  {
      if (table->eviction_fields) {
          struct eviction_group *evg, *next;
  
          HMAP_FOR_EACH_SAFE (evg, next, id_node,
                              &table->eviction_groups_by_id) {
              eviction_group_destroy(table, evg);
          }
          hmap_destroy(&table->eviction_groups_by_id);
          heap_destroy(&table->eviction_groups_by_size);
  
          free(table->eviction_fields);
          table->eviction_fields = NULL;
          table->n_eviction_fields = 0;
      }
  }
  
  /* oftables support a choice of two policies when adding a rule would cause the
   * number of flows in the table to exceed the configured maximum number: either
   * they can refuse to add the new flow or they can evict some existing flow.
   * This function configures the latter policy on 'table', with fairness based
   * on the values of the 'n_fields' fields specified in 'fields'.  (Specifying
   * 'n_fields' as 0 disables fairness.) */
  static void
  oftable_enable_eviction(struct oftable *table,
                          const struct mf_subfield *fields, size_t n_fields)
  {
      struct cls_cursor cursor;
      struct rule *rule;
  
      if (table->eviction_fields
          && n_fields == table->n_eviction_fields
          && (!n_fields
              || !memcmp(fields, table->eviction_fields,
                         n_fields * sizeof *fields))) {
          /* No change. */
          return;
      }
  
      oftable_disable_eviction(table);
  
      table->n_eviction_fields = n_fields;
      table->eviction_fields = xmemdup(fields, n_fields * sizeof *fields);
  
      table->eviction_group_id_basis = random_uint32();
      hmap_init(&table->eviction_groups_by_id);
      heap_init(&table->eviction_groups_by_size);
  
      cls_cursor_init(&cursor, &table->cls, NULL);
      CLS_CURSOR_FOR_EACH (rule, cr, &cursor) {
          eviction_group_add_rule(rule);
      }
  }
  
  /* Removes 'rule' from the oftable that contains it. */
  static void
  oftable_remove_rule(struct rule *rule)
  {
      struct ofproto *ofproto = rule->ofproto;
      struct oftable *table = &ofproto->tables[rule->table_id];
  
      classifier_remove(&table->cls, &rule->cr);
      eviction_group_remove_rule(rule);
  }
  
  /* Inserts 'rule' into its oftable.  Removes any existing rule from 'rule''s
   * oftable that has an identical cls_rule.  Returns the rule that was removed,
   * if any, and otherwise NULL. */
  static struct rule *
  oftable_replace_rule(struct rule *rule)
  {
      struct ofproto *ofproto = rule->ofproto;
      struct oftable *table = &ofproto->tables[rule->table_id];
      struct rule *victim;
  
      victim = rule_from_cls_rule(classifier_replace(&table->cls, &rule->cr));
      if (victim) {
          eviction_group_remove_rule(victim);
      }
      eviction_group_add_rule(rule);
      return victim;
  }
  
  /* Removes 'old' from its oftable then, if 'new' is nonnull, inserts 'new'. */
  static void
  oftable_substitute_rule(struct rule *old, struct rule *new)
  {
      if (new) {
          oftable_replace_rule(new);
      } else {
          oftable_remove_rule(old);
      }
  }
  
  /* unixctl commands. */
  
  struct ofproto *
  ofproto_lookup(const char *name)
  {
      struct ofproto *ofproto;
  
      HMAP_FOR_EACH_WITH_HASH (ofproto, hmap_node, hash_string(name, 0),
                               &all_ofprotos) {
          if (!strcmp(ofproto->name, name)) {
              return ofproto;
          }
      }
      return NULL;
  }
  
  static void
  ofproto_unixctl_list(struct unixctl_conn *conn, int argc OVS_UNUSED,
                       const char *argv[] OVS_UNUSED, void *aux OVS_UNUSED)
  {
      struct ofproto *ofproto;
      struct ds results;
  
      ds_init(&results);
      HMAP_FOR_EACH (ofproto, hmap_node, &all_ofprotos) {
          ds_put_format(&results, "%s\n", ofproto->name);
      }
      unixctl_command_reply(conn, ds_cstr(&results));
      ds_destroy(&results);
  }
  
  static void
  ofproto_unixctl_init(void)
  {
      static bool registered;
      if (registered) {
          return;
      }
      registered = true;
  
      unixctl_command_register("ofproto/list", "", 0, 0,
                               ofproto_unixctl_list, NULL);
  }
  
  /* Linux VLAN device support (e.g. "eth0.10" for VLAN 10.)
   *
   * This is deprecated.  It is only for compatibility with broken device drivers
   * in old versions of Linux that do not properly support VLANs when VLAN
   * devices are not used.  When broken device drivers are no longer in
   * widespread use, we will delete these interfaces. */
  
  /* Sets a 1-bit in the 4096-bit 'vlan_bitmap' for each VLAN ID that is matched
   * (exactly) by an OpenFlow rule in 'ofproto'. */
  void
  ofproto_get_vlan_usage(struct ofproto *ofproto, unsigned long int *vlan_bitmap)
  {
      const struct oftable *oftable;
  
      free(ofproto->vlan_bitmap);
      ofproto->vlan_bitmap = bitmap_allocate(4096);
      ofproto->vlans_changed = false;
  
      OFPROTO_FOR_EACH_TABLE (oftable, ofproto) {
          const struct cls_table *table;
  
          HMAP_FOR_EACH (table, hmap_node, &oftable->cls.tables) {
              if ((table->wc.vlan_tci_mask & htons(VLAN_VID_MASK))
                  == htons(VLAN_VID_MASK)) {
                  const struct cls_rule *rule;
  
                  HMAP_FOR_EACH (rule, hmap_node, &table->rules) {
                      uint16_t vid = vlan_tci_to_vid(rule->flow.vlan_tci);
                      bitmap_set1(vlan_bitmap, vid);
                      bitmap_set1(ofproto->vlan_bitmap, vid);
                  }
              }
          }
      }
  }
  
  /* Returns true if new VLANs have come into use by the flow table since the
   * last call to ofproto_get_vlan_usage().
   *
   * We don't track when old VLANs stop being used. */
  bool
  ofproto_has_vlan_usage_changed(const struct ofproto *ofproto)
  {
      return ofproto->vlans_changed;
  }
  
  /* Configures a VLAN splinter binding between the ports identified by OpenFlow
   * port numbers 'vlandev_ofp_port' and 'realdev_ofp_port'.  If
   * 'realdev_ofp_port' is nonzero, then the VLAN device is enslaved to the real
   * device as a VLAN splinter for VLAN ID 'vid'.  If 'realdev_ofp_port' is zero,
   * then the VLAN device is un-enslaved. */
  int
  ofproto_port_set_realdev(struct ofproto *ofproto, uint16_t vlandev_ofp_port,
                           uint16_t realdev_ofp_port, int vid)
  {
      struct ofport *ofport;
      int error;
  
      assert(vlandev_ofp_port != realdev_ofp_port);
  
      ofport = ofproto_get_port(ofproto, vlandev_ofp_port);
      if (!ofport) {
          VLOG_WARN("%s: cannot set realdev on nonexistent port %"PRIu16,
                    ofproto->name, vlandev_ofp_port);
          return EINVAL;
      }
  
      if (!ofproto->ofproto_class->set_realdev) {
          if (!vlandev_ofp_port) {
              return 0;
          }
          VLOG_WARN("%s: vlan splinters not supported", ofproto->name);
          return EOPNOTSUPP;
      }
  
      error = ofproto->ofproto_class->set_realdev(ofport, realdev_ofp_port, vid);
      if (error) {
          VLOG_WARN("%s: setting realdev on port %"PRIu16" (%s) failed (%s)",
                    ofproto->name, vlandev_ofp_port,
                    netdev_get_name(ofport->netdev), strerror(error));
      }
      return error;
  }
  