+
+
+/**
+ * Get the canonical regex of the given automaton.
+ * When constructing the automaton a proof is computed for each state,
+ * consisting of the regular expression leading to this state. A complete
+ * regex for the automaton can be computed by combining these proofs.
+ * As of now this function is only useful for testing.
+ *
+ * @param a automaton for which the canonical regex should be returned.
+ *
+ * @return
+ */
+const char *
+GNUNET_REGEX_get_canonical_regex (struct GNUNET_REGEX_Automaton *a)
+{
+ if (NULL == a)
+ return NULL;
+
+ return a->canonical_regex;
+}
+
+
+/**
+ * Get the first key for the given 'input_string'. This hashes the first x bits
+ * of the 'input_string'.
+ *
+ * @param input_string string.
+ * @param string_len length of the 'input_string'.
+ * @param key pointer to where to write the hash code.
+ *
+ * @return number of bits of 'input_string' that have been consumed
+ * to construct the key
+ */
+size_t
+GNUNET_REGEX_get_first_key (const char *input_string, size_t string_len,
+ struct GNUNET_HashCode * key)
+{
+ unsigned int size;
+
+ size = string_len < INITIAL_BITS ? string_len : INITIAL_BITS;
+
+ if (NULL == input_string)
+ {
+ GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "Given input string was NULL!\n");
+ return 0;
+ }
+
+ GNUNET_CRYPTO_hash (input_string, size, key);
+
+ return size;
+}
+
+
+/**
+ * Check if the given 'proof' matches the given 'key'.
+ *
+ * @param proof partial regex of a state.
+ * @param key hash of a state.
+ *
+ * @return GNUNET_OK if the proof is valid for the given key.
+ */
+int
+GNUNET_REGEX_check_proof (const char *proof, const struct GNUNET_HashCode *key)
+{
+ struct GNUNET_HashCode key_check;
+
+ GNUNET_CRYPTO_hash (proof, strlen (proof), &key_check);
+ return (0 ==
+ GNUNET_CRYPTO_hash_cmp (key, &key_check)) ? GNUNET_OK : GNUNET_NO;
+}
+
+
+/**
+ * Recursive helper function for iterate_initial_edges. Will call iterator
+ * function for each initial state.
+ *
+ * @param min_len minimum length of the path in the graph.
+ * @param max_len maximum length of the path in the graph.
+ * @param cur_len current length of the path already traversed.
+ * @param consumed_string string consumed by traversing the graph till this state.
+ * @param state current state of the automaton.
+ * @param iterator iterator function called for each edge.
+ * @param iterator_cls closure for the iterator function.
+ */
+static void
+iterate_initial_edge (const unsigned int min_len, const unsigned int max_len,
+ unsigned int cur_len, char *consumed_string,
+ struct GNUNET_REGEX_State *state,
+ GNUNET_REGEX_KeyIterator iterator, void *iterator_cls)
+{
+ unsigned int i;
+ char label[state->transition_count][2];
+ char *temp;
+ struct GNUNET_REGEX_Transition *t;
+ unsigned int num_edges = state->transition_count;
+ struct GNUNET_REGEX_Edge edges[num_edges];
+ struct GNUNET_HashCode hash;
+
+ if (cur_len > min_len && NULL != consumed_string && cur_len <= max_len)
+ {
+ for (i = 0, t = state->transitions_head; NULL != t; t = t->next, i++)
+ {
+ label[i][0] = t->label;
+ label[i][1] = '\0';
+ edges[i].label = label[i];
+ edges[i].destination = t->to_state->hash;
+ }
+
+ GNUNET_CRYPTO_hash (consumed_string, strlen (consumed_string), &hash);
+ iterator (iterator_cls, &hash, consumed_string, state->accepting, num_edges,
+ edges);
+ }
+
+ if (cur_len < max_len)
+ {
+ cur_len++;
+ for (t = state->transitions_head; NULL != t; t = t->next)
+ {
+ if (NULL != consumed_string)
+ GNUNET_asprintf (&temp, "%s%c", consumed_string, t->label);
+ else
+ GNUNET_asprintf (&temp, "%c", t->label);
+
+ iterate_initial_edge (min_len, max_len, cur_len, temp, t->to_state,
+ iterator, iterator_cls);
+ GNUNET_free (temp);
+ }
+ }
+}
+
+
+/**
+ * Iterate over all initial edges that aren't actually part of the automaton.
+ * This is needed to find the initial states returned by
+ * GNUNET_REGEX_get_first_key. Iteration will start at the first branch state (a
+ * state that has more than one outgoing edge, can be the first state), because
+ * all previous states will have the same proof and be iterated over in
+ * iterate_all_edges.
+ *
+ * @param a the automaton for which the initial states should be computed.
+ * @param initial_len length of the initial state string.
+ * @param iterator iterator function called for each edge.
+ * @param iterator_cls closure for the iterator function.
+ */
+void
+iterate_initial_edges (struct GNUNET_REGEX_Automaton *a,
+ const unsigned int initial_len,
+ GNUNET_REGEX_KeyIterator iterator, void *iterator_cls)
+{
+ char *consumed_string;
+ char *temp;
+ struct GNUNET_REGEX_State *s;
+ unsigned int cur_len;
+
+ if (1 > initial_len)
+ return;
+
+ consumed_string = NULL;
+ s = a->start;
+ cur_len = 0;
+
+ if (1 == s->transition_count)
+ {
+ do
+ {
+ if (NULL != consumed_string)
+ {
+ temp = consumed_string;
+ GNUNET_asprintf (&consumed_string, "%s%c", consumed_string,
+ s->transitions_head->label);
+ GNUNET_free (temp);
+ }
+ else
+ GNUNET_asprintf (&consumed_string, "%c", s->transitions_head->label);
+
+ s = s->transitions_head->to_state;
+ cur_len++;
+ }
+ while (cur_len < initial_len && 1 == s->transition_count);
+ }
+
+ iterate_initial_edge (cur_len, initial_len, cur_len, consumed_string, s,
+ iterator, iterator_cls);
+
+ GNUNET_free_non_null (consumed_string);
+}
+
+
+/**
+ * Iterate over all edges helper function starting from state 's', calling
+ * iterator on for each edge.
+ *
+ * @param s state.
+ * @param iterator iterator function called for each edge.
+ * @param iterator_cls closure.
+ */
+static void
+iterate_edge (struct GNUNET_REGEX_State *s, GNUNET_REGEX_KeyIterator iterator,
+ void *iterator_cls)
+{
+ struct GNUNET_REGEX_Transition *t;
+ struct GNUNET_REGEX_Edge edges[s->transition_count];
+ unsigned int num_edges;
+
+ if (GNUNET_YES != s->marked)
+ {
+ s->marked = GNUNET_YES;
+
+ num_edges = state_get_edges (s, edges);
+
+ if (0 < strlen (s->proof) || s->accepting)
+ iterator (iterator_cls, &s->hash, s->proof, s->accepting, num_edges,
+ edges);
+
+ for (t = s->transitions_head; NULL != t; t = t->next)
+ iterate_edge (t->to_state, iterator, iterator_cls);
+ }
+}
+
+
+/**
+ * Iterate over all edges starting from start state of automaton 'a'. Calling
+ * iterator for each edge.
+ *
+ * @param a automaton.
+ * @param iterator iterator called for each edge.
+ * @param iterator_cls closure.
+ */
+void
+GNUNET_REGEX_iterate_all_edges (struct GNUNET_REGEX_Automaton *a,
+ GNUNET_REGEX_KeyIterator iterator,
+ void *iterator_cls)
+{
+ struct GNUNET_REGEX_State *s;
+
+ for (s = a->states_head; NULL != s; s = s->next)
+ s->marked = GNUNET_NO;
+
+ iterate_initial_edges (a, INITIAL_BITS, iterator, iterator_cls);
+ iterate_edge (a->start, iterator, iterator_cls);
+}