text: /*
   * Copyright (c) 2009, 2010, 2011, 2012 Nicira, Inc.
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at:
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  #include <config.h>
  #include "classifier.h"
  #include <assert.h>
  #include <errno.h>
  #include <netinet/in.h>
  #include "byte-order.h"
  #include "dynamic-string.h"
  #include "flow.h"
  #include "hash.h"
  #include "odp-util.h"
  #include "ofp-util.h"
  #include "packets.h"
  
  static struct cls_table *find_table(const struct classifier *,
                                      const struct minimask *);
  static struct cls_table *insert_table(struct classifier *,
                                        const struct minimask *);
  
  static void destroy_table(struct classifier *, struct cls_table *);
  
  static struct cls_rule *find_match(const struct cls_table *,
                                     const struct flow *);
  static struct cls_rule *find_equal(struct cls_table *,
                                     const struct miniflow *, uint32_t hash);
  static struct cls_rule *insert_rule(struct cls_table *, struct cls_rule *);
  
  /* Iterates RULE over HEAD and all of the cls_rules on HEAD->list. */
  #define FOR_EACH_RULE_IN_LIST(RULE, HEAD)                               \
      for ((RULE) = (HEAD); (RULE) != NULL; (RULE) = next_rule_in_list(RULE))
  #define FOR_EACH_RULE_IN_LIST_SAFE(RULE, NEXT, HEAD)                    \
      for ((RULE) = (HEAD);                                               \
           (RULE) != NULL && ((NEXT) = next_rule_in_list(RULE), true);    \
           (RULE) = (NEXT))
  
  static struct cls_rule *next_rule_in_list__(struct cls_rule *);
  static struct cls_rule *next_rule_in_list(struct cls_rule *);
  
  /* cls_rule. */
  
  /* Initializes 'rule' to match packets specified by 'match' at the given
   * 'priority'.  'match' must satisfy the invariant described in the comment at
   * the definition of struct match.
   *
   * The caller must eventually destroy 'rule' with cls_rule_destroy().
   *
   * (OpenFlow uses priorities between 0 and UINT16_MAX, inclusive, but
   * internally Open vSwitch supports a wider range.) */
  void
  cls_rule_init(struct cls_rule *rule,
                const struct match *match, unsigned int priority)
  {
      minimatch_init(&rule->match, match);
      rule->priority = priority;
  }
  
  /* Same as cls_rule_init() for initialization from a "struct minimatch". */
  void
  cls_rule_init_from_minimatch(struct cls_rule *rule,
                               const struct minimatch *match,
                               unsigned int priority)
  {
      minimatch_clone(&rule->match, match);
      rule->priority = priority;
  }
  
  /* Initializes 'dst' as a copy of 'src'.
   *
   * The caller must eventually destroy 'rule' with cls_rule_destroy(). */
  void
  cls_rule_clone(struct cls_rule *dst, const struct cls_rule *src)
  {
      minimatch_clone(&dst->match, &src->match);
      dst->priority = src->priority;
  }
  
  /* Frees memory referenced by 'rule'.  Doesn't free 'rule' itself (it's
   * normally embedded into a larger structure).
   *
   * ('rule' must not currently be in a classifier.) */
  void
  cls_rule_destroy(struct cls_rule *rule)
  {
      minimatch_destroy(&rule->match);
  }
  
  /* Returns true if 'a' and 'b' match the same packets at the same priority,
   * false if they differ in some way. */
  bool
  cls_rule_equal(const struct cls_rule *a, const struct cls_rule *b)
  {
      return a->priority == b->priority && minimatch_equal(&a->match, &b->match);
  }
  
  /* Returns a hash value for 'rule', folding in 'basis'. */
  uint32_t
  cls_rule_hash(const struct cls_rule *rule, uint32_t basis)
  {
      return minimatch_hash(&rule->match, hash_int(rule->priority, basis));
  }
  
  /* Appends a string describing 'rule' to 's'. */
  void
  cls_rule_format(const struct cls_rule *rule, struct ds *s)
  {
      minimatch_format(&rule->match, s, rule->priority);
  }
  
  /* Returns true if 'rule' matches every packet, false otherwise. */
  bool
  cls_rule_is_catchall(const struct cls_rule *rule)
  {
      return minimask_is_catchall(&rule->match.mask);
  }
  
  /* Initializes 'cls' as a classifier that initially contains no classification
   * rules. */
  void
  classifier_init(struct classifier *cls)
  {
      cls->n_rules = 0;
      hmap_init(&cls->tables);
  }
  
  /* Destroys 'cls'.  Rules within 'cls', if any, are not freed; this is the
   * caller's responsibility. */
  void
  classifier_destroy(struct classifier *cls)
  {
      if (cls) {
          struct cls_table *table, *next_table;
  
          HMAP_FOR_EACH_SAFE (table, next_table, hmap_node, &cls->tables) {
              destroy_table(cls, table);
          }
          hmap_destroy(&cls->tables);
      }
  }
  
  /* Returns true if 'cls' contains no classification rules, false otherwise. */
  bool
  classifier_is_empty(const struct classifier *cls)
  {
      return cls->n_rules == 0;
  }
  
  /* Returns the number of rules in 'cls'. */
  int
  classifier_count(const struct classifier *cls)
  {
      return cls->n_rules;
  }
  
  /* Inserts 'rule' into 'cls'.  Until 'rule' is removed from 'cls', the caller
   * must not modify or free it.
   *
   * If 'cls' already contains an identical rule (including wildcards, values of
   * fixed fields, and priority), replaces the old rule by 'rule' and returns the
   * rule that was replaced.  The caller takes ownership of the returned rule and
   * is thus responsible for destroying it with cls_rule_destroy(), freeing the
   * memory block in which it resides, etc., as necessary.
   *
   * Returns NULL if 'cls' does not contain a rule with an identical key, after
   * inserting the new rule.  In this case, no rules are displaced by the new
   * rule, even rules that cannot have any effect because the new rule matches a
   * superset of their flows and has higher priority. */
  struct cls_rule *
  classifier_replace(struct classifier *cls, struct cls_rule *rule)
  {
      struct cls_rule *old_rule;
      struct cls_table *table;
  
      table = find_table(cls, &rule->match.mask);
      if (!table) {
          table = insert_table(cls, &rule->match.mask);
      }
  
      old_rule = insert_rule(table, rule);
      if (!old_rule) {
          table->n_table_rules++;
          cls->n_rules++;
      }
      return old_rule;
  }
  
  /* Inserts 'rule' into 'cls'.  Until 'rule' is removed from 'cls', the caller
   * must not modify or free it.
   *
   * 'cls' must not contain an identical rule (including wildcards, values of
   * fixed fields, and priority).  Use classifier_find_rule_exactly() to find
   * such a rule. */
  void
  classifier_insert(struct classifier *cls, struct cls_rule *rule)
  {
      struct cls_rule *displaced_rule = classifier_replace(cls, rule);
      assert(!displaced_rule);
  }
  
  /* Removes 'rule' from 'cls'.  It is the caller's responsibility to destroy
   * 'rule' with cls_rule_destroy(), freeing the memory block in which 'rule'
   * resides, etc., as necessary. */
  void
  classifier_remove(struct classifier *cls, struct cls_rule *rule)
  {
      struct cls_rule *head;
      struct cls_table *table;
  
      table = find_table(cls, &rule->match.mask);
      head = find_equal(table, &rule->match.flow, rule->hmap_node.hash);
      if (head != rule) {
          list_remove(&rule->list);
      } else if (list_is_empty(&rule->list)) {
          hmap_remove(&table->rules, &rule->hmap_node);
      } else {
          struct cls_rule *next = CONTAINER_OF(rule->list.next,
                                               struct cls_rule, list);
  
          list_remove(&rule->list);
          hmap_replace(&table->rules, &rule->hmap_node, &next->hmap_node);
      }
  
      if (--table->n_table_rules == 0) {
          destroy_table(cls, table);
      }
  
      cls->n_rules--;
  }
  
  /* Finds and returns the highest-priority rule in 'cls' that matches 'flow'.
   * Returns a null pointer if no rules in 'cls' match 'flow'.  If multiple rules
   * of equal priority match 'flow', returns one arbitrarily. */
  struct cls_rule *
  classifier_lookup(const struct classifier *cls, const struct flow *flow)
  {
      struct cls_table *table;
      struct cls_rule *best;
  
      best = NULL;
      HMAP_FOR_EACH (table, hmap_node, &cls->tables) {
          struct cls_rule *rule = find_match(table, flow);
          if (rule && (!best || rule->priority > best->priority)) {
              best = rule;
          }
      }
      return best;
  }
  
  /* Finds and returns a rule in 'cls' with exactly the same priority and
   * matching criteria as 'target'.  Returns a null pointer if 'cls' doesn't
   * contain an exact match. */
  struct cls_rule *
  classifier_find_rule_exactly(const struct classifier *cls,
                               const struct cls_rule *target)
  {
      struct cls_rule *head, *rule;
      struct cls_table *table;
  
      table = find_table(cls, &target->match.mask);
      if (!table) {
          return NULL;
      }
  
      head = find_equal(table, &target->match.flow,
                        miniflow_hash_in_minimask(&target->match.flow,
                                                  &target->match.mask, 0));
      FOR_EACH_RULE_IN_LIST (rule, head) {
          if (target->priority >= rule->priority) {
              return target->priority == rule->priority ? rule : NULL;
          }
      }
      return NULL;
  }
  
  /* Finds and returns a rule in 'cls' with priority 'priority' and exactly the
   * same matching criteria as 'target'.  Returns a null pointer if 'cls' doesn't
   * contain an exact match. */
  struct cls_rule *
  classifier_find_match_exactly(const struct classifier *cls,
                                const struct match *target,
                                unsigned int priority)
  {
      struct cls_rule *retval;
      struct cls_rule cr;
  
      cls_rule_init(&cr, target, priority);
      retval = classifier_find_rule_exactly(cls, &cr);
      cls_rule_destroy(&cr);
  
      return retval;
  }
  
  /* Checks if 'target' would overlap any other rule in 'cls'.  Two rules are
   * considered to overlap if both rules have the same priority and a packet
   * could match both. */
  bool
  classifier_rule_overlaps(const struct classifier *cls,
                           const struct cls_rule *target)
  {
      struct cls_table *table;
  
      HMAP_FOR_EACH (table, hmap_node, &cls->tables) {
          uint32_t storage[FLOW_U32S];
          struct minimask mask;
          struct cls_rule *head;
  
          minimask_combine(&mask, &target->match.mask, &table->mask, storage);
          HMAP_FOR_EACH (head, hmap_node, &table->rules) {
              struct cls_rule *rule;
  
              FOR_EACH_RULE_IN_LIST (rule, head) {
                  if (rule->priority == target->priority
                      && miniflow_equal_in_minimask(&target->match.flow,
                                                    &rule->match.flow, &mask)) {
                      return true;
                  }
              }
          }
      }
  
      return false;
  }
  
  /* Returns true if 'rule' exactly matches 'criteria' or if 'rule' is more
   * specific than 'criteria'.  That is, 'rule' matches 'criteria' and this
   * function returns true if, for every field:
   *
   *   - 'criteria' and 'rule' specify the same (non-wildcarded) value for the
   *     field, or
   *
   *   - 'criteria' wildcards the field,
   *
   * Conversely, 'rule' does not match 'criteria' and this function returns false
   * if, for at least one field:
   *
   *   - 'criteria' and 'rule' specify different values for the field, or
   *
   *   - 'criteria' specifies a value for the field but 'rule' wildcards it.
   *
   * Equivalently, the truth table for whether a field matches is:
   *
   *                                     rule
   *
   *                   c         wildcard    exact
   *                   r        +---------+---------+
   *                   i   wild |   yes   |   yes   |
   *                   t   card |         |         |
   *                   e        +---------+---------+
   *                   r  exact |    no   |if values|
   *                   i        |         |are equal|
   *                   a        +---------+---------+
   *
   * This is the matching rule used by OpenFlow 1.0 non-strict OFPT_FLOW_MOD
   * commands and by OpenFlow 1.0 aggregate and flow stats.
   *
   * Ignores rule->priority. */
  bool
  cls_rule_is_loose_match(const struct cls_rule *rule,
                          const struct minimatch *criteria)
  {
      return (!minimask_has_extra(&rule->match.mask, &criteria->mask)
              && miniflow_equal_in_minimask(&rule->match.flow, &criteria->flow,
                                            &criteria->mask));
  }
  
  /* Iteration. */
  
  static bool
  rule_matches(const struct cls_rule *rule, const struct cls_rule *target)
  {
      return (!target
              || miniflow_equal_in_minimask(&rule->match.flow,
                                            &target->match.flow,
                                            &target->match.mask));
  }
  
  static struct cls_rule *
  search_table(const struct cls_table *table, const struct cls_rule *target)
  {
      if (!target || !minimask_has_extra(&table->mask, &target->match.mask)) {
          struct cls_rule *rule;
  
          HMAP_FOR_EACH (rule, hmap_node, &table->rules) {
              if (rule_matches(rule, target)) {
                  return rule;
              }
          }
      }
      return NULL;
  }
  
  /* Initializes 'cursor' for iterating through rules in 'cls':
   *
   *     - If 'target' is null, the cursor will visit every rule in 'cls'.
   *
   *     - If 'target' is nonnull, the cursor will visit each 'rule' in 'cls'
   *       such that cls_rule_is_loose_match(rule, target) returns true.
   *
   * Ignores target->priority. */
  void
  cls_cursor_init(struct cls_cursor *cursor, const struct classifier *cls,
                  const struct cls_rule *target)
  {
      cursor->cls = cls;
      cursor->target = target && !cls_rule_is_catchall(target) ? target : NULL;
  }
  
  /* Returns the first matching cls_rule in 'cursor''s iteration, or a null
   * pointer if there are no matches. */
  struct cls_rule *
  cls_cursor_first(struct cls_cursor *cursor)
  {
      struct cls_table *table;
  
      HMAP_FOR_EACH (table, hmap_node, &cursor->cls->tables) {
          struct cls_rule *rule = search_table(table, cursor->target);
          if (rule) {
              cursor->table = table;
              return rule;
          }
      }
  
      return NULL;
  }
  
  /* Returns the next matching cls_rule in 'cursor''s iteration, or a null
   * pointer if there are no more matches. */
  struct cls_rule *
  cls_cursor_next(struct cls_cursor *cursor, struct cls_rule *rule)
  {
      const struct cls_table *table;
      struct cls_rule *next;
  
      next = next_rule_in_list__(rule);
      if (next->priority < rule->priority) {
          return next;
      }
  
      /* 'next' is the head of the list, that is, the rule that is included in
       * the table's hmap.  (This is important when the classifier contains rules
       * that differ only in priority.) */
      rule = next;
      HMAP_FOR_EACH_CONTINUE (rule, hmap_node, &cursor->table->rules) {
          if (rule_matches(rule, cursor->target)) {
              return rule;
          }
      }
  
      table = cursor->table;
      HMAP_FOR_EACH_CONTINUE (table, hmap_node, &cursor->cls->tables) {
          rule = search_table(table, cursor->target);
          if (rule) {
              cursor->table = table;
              return rule;
          }
      }
  
      return NULL;
  }
  
  static struct cls_table *
  find_table(const struct classifier *cls, const struct minimask *mask)
  {
      struct cls_table *table;
  
      HMAP_FOR_EACH_IN_BUCKET (table, hmap_node, minimask_hash(mask, 0),
                               &cls->tables) {
          if (minimask_equal(mask, &table->mask)) {
              return table;
          }
      }
      return NULL;
  }
  
  static struct cls_table *
  insert_table(struct classifier *cls, const struct minimask *mask)
  {
      struct cls_table *table;
  
      table = xzalloc(sizeof *table);
      hmap_init(&table->rules);
      minimask_clone(&table->mask, mask);
      hmap_insert(&cls->tables, &table->hmap_node, minimask_hash(mask, 0));
  
      return table;
  }
  
  static void
  destroy_table(struct classifier *cls, struct cls_table *table)
  {
      minimask_destroy(&table->mask);
      hmap_remove(&cls->tables, &table->hmap_node);
      hmap_destroy(&table->rules);
      free(table);
  }
  
  static struct cls_rule *
  find_match(const struct cls_table *table, const struct flow *flow)
  {
      uint32_t hash = flow_hash_in_minimask(flow, &table->mask, 0);
      struct cls_rule *rule;
  
      HMAP_FOR_EACH_WITH_HASH (rule, hmap_node, hash, &table->rules) {
          if (miniflow_equal_flow_in_minimask(&rule->match.flow, flow,
                                              &table->mask)) {
              return rule;
          }
      }
  
      return NULL;
  }
  
  static struct cls_rule *
  find_equal(struct cls_table *table, const struct miniflow *flow, uint32_t hash)
  {
      struct cls_rule *head;
  
      HMAP_FOR_EACH_WITH_HASH (head, hmap_node, hash, &table->rules) {
          if (miniflow_equal(&head->match.flow, flow)) {
              return head;
          }
      }
      return NULL;
  }
  
  static struct cls_rule *
  insert_rule(struct cls_table *table, struct cls_rule *new)
  {
      struct cls_rule *head;
  
      new->hmap_node.hash = miniflow_hash_in_minimask(&new->match.flow,
                                                      &new->match.mask, 0);
  
      head = find_equal(table, &new->match.flow, new->hmap_node.hash);
      if (!head) {
          hmap_insert(&table->rules, &new->hmap_node, new->hmap_node.hash);
          list_init(&new->list);
          return NULL;
      } else {
          /* Scan the list for the insertion point that will keep the list in
           * order of decreasing priority. */
          struct cls_rule *rule;
          FOR_EACH_RULE_IN_LIST (rule, head) {
              if (new->priority >= rule->priority) {
                  if (rule == head) {
                      /* 'new' is the new highest-priority flow in the list. */
                      hmap_replace(&table->rules,
                                   &rule->hmap_node, &new->hmap_node);
                  }
  
                  if (new->priority == rule->priority) {
                      list_replace(&new->list, &rule->list);
                      return rule;
                  } else {
                      list_insert(&rule->list, &new->list);
                      return NULL;
                  }
              }
          }
  
          /* Insert 'new' at the end of the list. */
          list_push_back(&head->list, &new->list);
          return NULL;
      }
  }
  
  static struct cls_rule *
  next_rule_in_list__(struct cls_rule *rule)
  {
      struct cls_rule *next = OBJECT_CONTAINING(rule->list.next, next, list);
      return next;
  }
  
  static struct cls_rule *
  next_rule_in_list(struct cls_rule *rule)
  {
      struct cls_rule *next = next_rule_in_list__(rule);
      return next->priority < rule->priority ? next : NULL;
  }
  