#define INITIAL_BITS 8
-/**
- * Context that contains an id counter for states and transitions as well as a
- * DLL of automatons used as a stack for NFA construction.
- */
-struct GNUNET_REGEX_Context
-{
- /**
- * Unique state id.
- */
- unsigned int state_id;
-
- /**
- * Unique transition id.
- */
- unsigned int transition_id;
-
- /**
- * DLL of GNUNET_REGEX_Automaton's used as a stack.
- */
- struct GNUNET_REGEX_Automaton *stack_head;
-
- /**
- * DLL of GNUNET_REGEX_Automaton's used as a stack.
- */
- struct GNUNET_REGEX_Automaton *stack_tail;
-};
-
-
/**
* Set of states.
*/
};
-/*
- * Debug helper functions
- */
-
-/**
- * Print all the transitions of state 's'.
- *
- * @param s state for which to print it's transitions.
- */
-void
-debug_print_transitions (struct GNUNET_REGEX_State *s);
-
-
-/**
- * Print information of the given state 's'.
- *
- * @param s state for which debug information should be printed.
- */
-void
-debug_print_state (struct GNUNET_REGEX_State *s)
-{
- char *proof;
-
- if (NULL == s->proof)
- proof = "NULL";
- else
- proof = s->proof;
-
- GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
- "State %i: %s marked: %i accepting: %i scc_id: %i transitions: %i proof: %s\n",
- s->id, s->name, s->marked, s->accepting, s->scc_id,
- s->transition_count, proof);
-
- GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "Transitions:\n");
- debug_print_transitions (s);
-}
-
-
-/**
- * Print debug information for all states contained in the automaton 'a'.
- *
- * @param a automaton for which debug information of it's states should be printed.
- */
-void
-debug_print_states (struct GNUNET_REGEX_Automaton *a)
-{
- struct GNUNET_REGEX_State *s;
-
- for (s = a->states_head; NULL != s; s = s->next)
- debug_print_state (s);
-}
-
-
-/**
- * Print debug information for given transition 't'.
- *
- * @param t transition for which to print debug info.
- */
-void
-debug_print_transition (struct GNUNET_REGEX_Transition *t)
-{
- char *to_state;
- char *from_state;
- char *label;
-
- if (NULL == t)
- return;
-
- if (0 == t->label)
- label = "0";
- else
- label = t->label;
-
- if (NULL == t->to_state)
- to_state = "NULL";
- else
- to_state = t->to_state->name;
-
- if (NULL == t->from_state)
- from_state = "NULL";
- else
- from_state = t->from_state->name;
-
- GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "Transition %i: From %s on %s to %s\n",
- t->id, from_state, label, to_state);
-}
-
-
-void
-debug_print_transitions (struct GNUNET_REGEX_State *s)
-{
- struct GNUNET_REGEX_Transition *t;
-
- for (t = s->transitions_head; NULL != t; t = t->next)
- debug_print_transition (t);
-}
-
-
/**
* Compare two strings for equality. If either is NULL they are not equal.
*
}
t = GNUNET_malloc (sizeof (struct GNUNET_REGEX_Transition));
- t->id = ctx->transition_id++;
+ if (NULL != ctx)
+ t->id = ctx->transition_id++;
if (NULL != label)
t->label = GNUNET_strdup (label);
else
/**
- * Depth-first traversal of all states that are reachable from state 's'. Expects the states to
- * be unmarked (s->marked == GNUNET_NO). Performs 'action' on each visited
- * state.
+ * Depth-first traversal (DFS) of all states that are reachable from state
+ * 's'. Performs 'action' on each visited state.
*
* @param s start state.
+ * @param marks an array of size a->state_count to remember which state was
+ * already visited.
* @param count current count of the state.
+ * @param check function that is checked before advancing on each transition
+ * in the DFS.
+ * @param check_cls closure for check.
* @param action action to be performed on each state.
- * @param action_cls closure for action
+ * @param action_cls closure for action.
*/
static void
-automaton_state_traverse (struct GNUNET_REGEX_State *s, unsigned int *count,
+automaton_state_traverse (struct GNUNET_REGEX_State *s, int *marks,
+ unsigned int *count,
+ GNUNET_REGEX_traverse_check check, void *check_cls,
GNUNET_REGEX_traverse_action action, void *action_cls)
{
struct GNUNET_REGEX_Transition *t;
- if (GNUNET_NO != s->marked)
+ if (GNUNET_YES == marks[s->traversal_id])
return;
- s->marked = GNUNET_YES;
+
+ marks[s->traversal_id] = GNUNET_YES;
+
if (NULL != action)
action (action_cls, *count, s);
+
(*count)++;
+
for (t = s->transitions_head; NULL != t; t = t->next)
- automaton_state_traverse (t->to_state, count, action, action_cls);
+ {
+ if (NULL == check ||
+ (NULL != check && GNUNET_YES == check (check_cls, s, t)))
+ {
+ automaton_state_traverse (t->to_state, marks, count, check, check_cls,
+ action, action_cls);
+ }
+ }
}
/**
- * Traverses the given automaton from it's start state, visiting all reachable
- * states and calling 'action' on each one of them.
- *
- * @param a automaton.
+ * Traverses the given automaton using depth-first-search (DFS) from it's start
+ * state, visiting all reachable states and calling 'action' on each one of
+ * them.
+ *
+ * @param a automaton to be traversed.
+ * @param start start state, pass a->start or NULL to traverse the whole automaton.
+ * @param check function that is checked before advancing on each transition
+ * in the DFS.
+ * @param check_cls closure for check.
* @param action action to be performed on each state.
* @param action_cls closure for action
*/
void
-GNUNET_REGEX_automaton_traverse (struct GNUNET_REGEX_Automaton *a,
+GNUNET_REGEX_automaton_traverse (const struct GNUNET_REGEX_Automaton *a,
+ struct GNUNET_REGEX_State *start,
+ GNUNET_REGEX_traverse_check check,
+ void *check_cls,
GNUNET_REGEX_traverse_action action,
void *action_cls)
{
unsigned int count;
struct GNUNET_REGEX_State *s;
+ int marks[a->state_count];
+
+ if (NULL == a || 0 == a->state_count)
+ return;
+
+ for (count = 0, s = a->states_head; NULL != s && count < a->state_count;
+ s = s->next, count++)
+ {
+ s->traversal_id = count;
+ marks[s->traversal_id] = GNUNET_NO;
+ }
- for (s = a->states_head; NULL != s; s = s->next)
- s->marked = GNUNET_NO;
count = 0;
- automaton_state_traverse (a->start, &count, action, action_cls);
+
+ if (NULL == start)
+ s = a->start;
+ else
+ s = start;
+
+ automaton_state_traverse (s, marks, &count, check, check_cls, action,
+ action_cls);
+}
+
+
+/**
+ * Context for adding strided transitions to a DFA.
+ */
+struct GNUNET_REGEX_Strided_Context
+{
+ /**
+ * Length of the strides.
+ */
+ const unsigned int stride;
+
+ /**
+ * Strided transitions DLL. New strided transitions will be stored in this DLL
+ * and afterwards added to the DFA.
+ */
+ struct GNUNET_REGEX_Transition *transitions_head;
+
+ /**
+ * Strided transitions DLL.
+ */
+ struct GNUNET_REGEX_Transition *transitions_tail;
+};
+
+
+/**
+ * Recursive helper function to add strides to a DFA.
+ *
+ * @param cls context, contains stride length and strided transitions DLL.
+ * @param depth current depth of the depth-first traversal of the graph.
+ * @param label current label, string that contains all labels on the path from
+ * 'start' to 's'.
+ * @param start start state for the depth-first traversal of the graph.
+ * @param s current state in the depth-first traversal
+ */
+void
+add_multi_strides_to_dfa_helper (void *cls, const unsigned int depth,
+ char *label, struct GNUNET_REGEX_State *start,
+ struct GNUNET_REGEX_State *s)
+{
+ struct GNUNET_REGEX_Strided_Context *ctx = cls;
+ struct GNUNET_REGEX_Transition *t;
+ char *new_label;
+
+ if (depth == ctx->stride)
+ {
+ t = GNUNET_malloc (sizeof (struct GNUNET_REGEX_Transition));
+ t->label = GNUNET_strdup (label);
+ t->to_state = s;
+ t->from_state = start;
+ GNUNET_CONTAINER_DLL_insert (ctx->transitions_head, ctx->transitions_tail,
+ t);
+ }
+ else
+ {
+ for (t = s->transitions_head; NULL != t; t = t->next)
+ {
+ /* Do not consider self-loops, because it end's up in too many
+ * transitions */
+ if (t->to_state == t->from_state)
+ continue;
+
+ if (NULL != label)
+ {
+ GNUNET_asprintf (&new_label, "%s%s", label, t->label);
+ }
+ else
+ new_label = GNUNET_strdup (t->label);
+
+ add_multi_strides_to_dfa_helper (cls, (depth + 1), new_label, start,
+ t->to_state);
+ }
+ }
+ GNUNET_free_non_null (label);
+}
+
+
+/**
+ * Function called for each state in the DFA. Starts a traversal of depth set in
+ * context starting from state 's'.
+ *
+ * @param cls context.
+ * @param count not used.
+ * @param s current state.
+ */
+void
+add_multi_strides_to_dfa (void *cls, const unsigned int count,
+ struct GNUNET_REGEX_State *s)
+{
+ add_multi_strides_to_dfa_helper (cls, 0, NULL, s, s);
+}
+
+
+/**
+ * Adds multi-strided transitions to the given 'dfa'.
+ *
+ * @param regex_ctx regex context needed to add transitions to the automaton.
+ * @param dfa DFA to which the multi strided transitions should be added.
+ * @param stride_len length of the strides.
+ */
+void
+GNUNET_REGEX_add_multi_strides_to_dfa (struct GNUNET_REGEX_Context *regex_ctx,
+ struct GNUNET_REGEX_Automaton *dfa,
+ const unsigned int stride_len)
+{
+ struct GNUNET_REGEX_Strided_Context ctx = { stride_len, NULL, NULL };
+ struct GNUNET_REGEX_Transition *t;
+ struct GNUNET_REGEX_Transition *t_next;
+
+ if (1 > stride_len || GNUNET_YES == dfa->is_multistrided)
+ return;
+
+ // Compute the new transitions.
+ GNUNET_REGEX_automaton_traverse (dfa, dfa->start, NULL, NULL,
+ &add_multi_strides_to_dfa, &ctx);
+
+ // Add all the new transitions to the automaton.
+ for (t = ctx.transitions_head; NULL != t; t = t_next)
+ {
+ t_next = t->next;
+ state_add_transition (regex_ctx, t->from_state, t->label, t->to_state);
+ GNUNET_CONTAINER_DLL_remove (ctx.transitions_head, ctx.transitions_tail, t);
+ GNUNET_free_non_null (t->label);
+ GNUNET_free (t);
+ }
+
+ dfa->is_multistrided = GNUNET_YES;
}
+
/**
* Check if the given string 'str' needs parentheses around it when
* using it to generate a regex.
*
* @param str string
*
- * @return string without preceding epsilon, string 'str' if no preceding epsilon
- * could be found, NULL if 'str' was NULL
+ * @return string without preceding epsilon, string 'str' if no preceding
+ * epsilon could be found, NULL if 'str' was NULL
*/
static char *
remove_epsilon (const char *str)
/**
- * Helper function used as 'action' in 'GNUNET_REGEX_automaton_traverse' function to create
- * the depth-first numbering of the states.
+ * Helper function used as 'action' in 'GNUNET_REGEX_automaton_traverse'
+ * function to create the depth-first numbering of the states.
*
* @param cls states array.
* @param count current state counter.
* @param s current state.
*/
-static void
-number_states (void *cls, unsigned int count, struct GNUNET_REGEX_State *s)
+void
+number_states (void *cls, const unsigned int count,
+ struct GNUNET_REGEX_State *s)
{
struct GNUNET_REGEX_State **states = cls;
- s->proof_id = count;
+ s->dfs_id = count;
if (NULL != states)
states[count] = s;
}
unsigned int j;
unsigned int k;
+ if (NULL == a)
+ {
+ GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+ "Could not create proofs, automaton was NULL\n");
+ return;
+ }
/* create depth-first numbering of the states, initializes 'state' */
- GNUNET_REGEX_automaton_traverse (a, &number_states, states);
+ GNUNET_REGEX_automaton_traverse (a, a->start, NULL, NULL, &number_states,
+ states);
+
+ for (i = 0; i < n; i++)
+ GNUNET_assert (NULL != states[i]);
/* Compute regular expressions of length "1" between each pair of states */
for (i = 0; i < n; i++)
}
for (t = states[i]->transitions_head; NULL != t; t = t->next)
{
- j = t->to_state->proof_id;
+ j = t->to_state->dfs_id;
if (NULL == R_last[i][j])
GNUNET_asprintf (&R_last[i][j], "%s", t->label);
else
GNUNET_free (temp);
}
- /* Compute regular expressions of length "k" between each pair of states per induction */
+ /* Compute regular expressions of length "k" between each pair of states per
+ * induction */
for (k = 0; k < n; k++)
{
for (i = 0; i < n; i++)
// assign proofs and hashes
for (i = 0; i < n; i++)
{
- if (NULL != R_last[a->start->proof_id][i])
+ if (NULL != R_last[a->start->dfs_id][i])
{
- states[i]->proof = GNUNET_strdup (R_last[a->start->proof_id][i]);
+ states[i]->proof = GNUNET_strdup (R_last[a->start->dfs_id][i]);
GNUNET_CRYPTO_hash (states[i]->proof, strlen (states[i]->proof),
&states[i]->hash);
}
}
- // complete regex for whole DFA: union of all pairs (start state/accepting state(s)).
+ // complete regex for whole DFA: union of all pairs (start state/accepting
+ // state(s)).
complete_regex = NULL;
for (i = 0; i < n; i++)
{
if (states[i]->accepting)
{
- if (NULL == complete_regex && 0 < strlen (R_last[a->start->proof_id][i]))
+ if (NULL == complete_regex && 0 < strlen (R_last[a->start->dfs_id][i]))
{
- GNUNET_asprintf (&complete_regex, "%s", R_last[a->start->proof_id][i]);
+ GNUNET_asprintf (&complete_regex, "%s", R_last[a->start->dfs_id][i]);
}
- else if (NULL != R_last[a->start->proof_id][i] &&
- 0 < strlen (R_last[a->start->proof_id][i]))
+ else if (NULL != R_last[a->start->dfs_id][i] &&
+ 0 < strlen (R_last[a->start->dfs_id][i]))
{
temp = complete_regex;
GNUNET_asprintf (&complete_regex, "%s|%s", complete_regex,
- R_last[a->start->proof_id][i]);
+ R_last[a->start->dfs_id][i]);
GNUNET_free (temp);
}
}
s = GNUNET_malloc (sizeof (struct GNUNET_REGEX_State));
s->id = ctx->state_id++;
s->accepting = 0;
- s->marked = 0;
+ s->marked = GNUNET_NO;
s->name = NULL;
s->scc_id = 0;
s->index = -1;
if (nfa_states->len < 1)
return s;
- // Create a name based on 'sset'
+ // Create a name based on 'nfa_states'
s->name = GNUNET_malloc (sizeof (char) * 2);
strcat (s->name, "{");
name = NULL;
return new_s;
}
+/**
+ * Set the given state 'marked' to GNUNET_YES. Used by the
+ * 'dfa_remove_unreachable_states' function to detect unreachable states in the
+ * automaton.
+ *
+ * @param cls closure, not used.
+ * @param count count, not used.
+ * @param s state where the marked attribute will be set to GNUNET_YES.
+ */
+void
+mark_states (void *cls, const unsigned int count, struct GNUNET_REGEX_State *s)
+{
+ s->marked = GNUNET_YES;
+}
/**
* Remove all unreachable states from DFA 'a'. Unreachable states are those
s->marked = GNUNET_NO;
// 2. traverse dfa from start state and mark all visited states
- GNUNET_REGEX_automaton_traverse (a, NULL, NULL);
+ GNUNET_REGEX_automaton_traverse (a, a->start, NULL, NULL, &mark_states, NULL);
// 3. delete all states that were not visited
for (s = a->states_head; NULL != s; s = s_next)
dfa_merge_nondistinguishable_states (struct GNUNET_REGEX_Context *ctx,
struct GNUNET_REGEX_Automaton *a)
{
- unsigned int i;
int table[a->state_count][a->state_count];
struct GNUNET_REGEX_State *s1;
struct GNUNET_REGEX_State *s2;
struct GNUNET_REGEX_State *s2_next;
int change;
unsigned int num_equal_edges;
+ unsigned int i;
for (i = 0, s1 = a->states_head; i < a->state_count && NULL != s1;
i++, s1 = s1->next)
n->type = NFA;
n->start = NULL;
n->end = NULL;
+ n->state_count = 0;
if (NULL == start || NULL == end)
return n;
automaton_add_state (n, end);
automaton_add_state (n, start);
+ n->state_count = 2;
+
n->start = start;
n->end = end;
s = GNUNET_malloc (sizeof (struct GNUNET_REGEX_State));
s->id = ctx->state_id++;
s->accepting = accepting;
- s->marked = 0;
+ s->marked = GNUNET_NO;
s->contained = 0;
s->index = -1;
s->lowlink = -1;
nfa_add_states (new_nfa, b->states_head, b->states_tail);
new_nfa->start = a->start;
new_nfa->end = b->end;
+ new_nfa->state_count += a->state_count + b->state_count;
automaton_fragment_clear (a);
automaton_fragment_clear (b);
}
nfa_add_question_op (&ctx);
break;
- case 92: /* escape: \ */
- regexp++;
- count++;
- /* fall through! */
default:
if (atomcount > 1)
{
goto error;
}
+ /* Remember the regex that was used to generate this NFA */
nfa->regex = GNUNET_strdup (regex);
/* create depth-first numbering of the states for pretty printing */
- GNUNET_REGEX_automaton_traverse (nfa, &number_states, NULL);
+ GNUNET_REGEX_automaton_traverse (nfa, NULL, NULL, NULL, &number_states, NULL);
+
+ /* No multistriding added so far */
+ nfa->is_multistrided = GNUNET_NO;
return nfa;
struct GNUNET_REGEX_Context ctx;
struct GNUNET_REGEX_Automaton *dfa;
struct GNUNET_REGEX_Automaton *nfa;
- struct GNUNET_REGEX_StateSet *nfa_set;
+ struct GNUNET_REGEX_StateSet *nfa_start_eps_cls;
GNUNET_REGEX_context_init (&ctx);
dfa = GNUNET_malloc (sizeof (struct GNUNET_REGEX_Automaton));
dfa->type = DFA;
+ dfa->state_count = 0;
+ dfa->states_head = NULL;
+ dfa->states_tail = NULL;
dfa->regex = GNUNET_strdup (regex);
+ dfa->is_multistrided = GNUNET_NO;
// Create DFA start state from epsilon closure
- nfa_set = nfa_closure_create (nfa, nfa->start, 0);
- dfa->start = dfa_state_create (&ctx, nfa_set);
+ nfa_start_eps_cls = nfa_closure_create (nfa, nfa->start, 0);
+ dfa->start = dfa_state_create (&ctx, nfa_start_eps_cls);
automaton_add_state (dfa, dfa->start);
construct_dfa_states (&ctx, nfa, dfa, dfa->start);
// Create proofs for all states
automaton_create_proofs (dfa);
+ // Add strides to DFA
+ // GNUNET_REGEX_add_multi_strides_to_dfa (&ctx, dfa, 2);
+
return dfa;
}
}
+/**
+ * Get the number of transitions that are contained in the given automaton.
+ *
+ * @param a automaton for which the number of transitions should be returned.
+ *
+ * @return number of transitions in the given automaton.
+ */
+unsigned int
+GNUNET_REGEX_get_transition_count (struct GNUNET_REGEX_Automaton *a)
+{
+ unsigned int t_count;
+ struct GNUNET_REGEX_State *s;
+
+ if (NULL == a)
+ return 0;
+
+ for (t_count = 0, s = a->states_head; NULL != s; s = s->next)
+ {
+ t_count += s->transition_count;
+ }
+
+ return t_count;
+}
+
+
/**
* Get the first key for the given 'input_string'. This hashes the first x bits
* of the 'input_string'.
{
struct GNUNET_HashCode key_check;
+ if (NULL == proof || NULL == key)
+ {
+ GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "Proof check failed, was NULL.\n");
+ return GNUNET_NO;
+ }
+
GNUNET_CRYPTO_hash (proof, strlen (proof), &key_check);
return (0 ==
GNUNET_CRYPTO_hash_cmp (key, &key_check)) ? GNUNET_OK : GNUNET_NO;
/**
* 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.
+ * GNUNET_REGEX_get_first_key. Iteration will start at the first state that has
+ * more than one outgoing edge, i.e. the state that branches the graph.
+ * For example consider the following graph:
+ * a -> b -> c -> d -> ...
+ * \-> e -> ...
+ *
+ * This function will not iterate over the edges leading to "c", because these
+ * will be covered by the iterate_edges function.
*
* @param a the automaton for which the initial states should be computed.
* @param initial_len length of the initial state string.
GNUNET_asprintf (&consumed_string, "%s", s->transitions_head->label);
s = s->transitions_head->to_state;
- cur_len++;
+ cur_len += strlen (s->transitions_head->label);
}
while (cur_len < initial_len && 1 == s->transition_count);
}
/**
* Iterate over all edges helper function starting from state 's', calling
- * iterator on for each edge.
+ * iterator function for each edge.
*
* @param s state.
* @param iterator iterator function called for each edge.
num_edges = state_get_edges (s, edges);
- if (0 < strlen (s->proof) || s->accepting)
+ if ((NULL != s->proof && 0 < strlen (s->proof)) || s->accepting)
iterator (iterator_cls, &s->hash, s->proof, s->accepting, num_edges,
edges);
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