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21 * @file src/regex/regex.c
22 * @brief library to create automatons from regular expressions
23 * @author Maximilian Szengel
26 #include "gnunet_container_lib.h"
27 #include "gnunet_crypto_lib.h"
28 #include "gnunet_regex_lib.h"
29 #include "regex_internal.h"
33 * Constant for how many bits the initial string regex should have.
35 #define INITIAL_BITS 8
41 struct GNUNET_REGEX_StateSet
46 struct GNUNET_REGEX_State **states;
49 * Length of the 'states' array.
56 * Compare two strings for equality. If either is NULL they are not equal.
58 * @param str1 first string for comparison.
59 * @param str2 second string for comparison.
61 * @return 0 if the strings are the same or both NULL, 1 or -1 if not.
64 nullstrcmp (const char *str1, const char *str2)
66 if ((NULL == str1) != (NULL == str2))
68 if ((NULL == str1) && (NULL == str2))
71 return strcmp (str1, str2);
76 * Adds a transition from one state to another on 'label'. Does not add
80 * @param from_state starting state for the transition
81 * @param label transition label
82 * @param to_state state to where the transition should point to
85 state_add_transition (struct GNUNET_REGEX_Context *ctx,
86 struct GNUNET_REGEX_State *from_state, const char *label,
87 struct GNUNET_REGEX_State *to_state)
90 struct GNUNET_REGEX_Transition *t;
91 struct GNUNET_REGEX_Transition *oth;
93 if (NULL == from_state)
95 GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "Could not create Transition.\n");
99 // Do not add duplicate state transitions
101 for (t = from_state->transitions_head; NULL != t; t = t->next)
103 if (t->to_state == to_state && 0 == nullstrcmp (t->label, label) &&
104 t->from_state == from_state)
111 if (GNUNET_YES == is_dup)
114 // sort transitions by label
115 for (oth = from_state->transitions_head; NULL != oth; oth = oth->next)
117 if (0 < nullstrcmp (oth->label, label))
121 t = GNUNET_malloc (sizeof (struct GNUNET_REGEX_Transition));
123 t->id = ctx->transition_id++;
125 t->label = GNUNET_strdup (label);
128 t->to_state = to_state;
129 t->from_state = from_state;
131 // Add outgoing transition to 'from_state'
132 from_state->transition_count++;
133 GNUNET_CONTAINER_DLL_insert_before (from_state->transitions_head,
134 from_state->transitions_tail, oth, t);
139 * Remove a 'transition' from 'state'.
141 * @param state state from which the to-be-removed transition originates.
142 * @param transition transition that should be removed from state 'state'.
145 state_remove_transition (struct GNUNET_REGEX_State *state,
146 struct GNUNET_REGEX_Transition *transition)
148 if (NULL == state || NULL == transition)
151 if (transition->from_state != state)
154 state->transition_count--;
155 GNUNET_CONTAINER_DLL_remove (state->transitions_head, state->transitions_tail,
157 GNUNET_free_non_null (transition->label);
158 GNUNET_free (transition);
163 * Compare two states. Used for sorting.
165 * @param a first state
166 * @param b second state
168 * @return an integer less than, equal to, or greater than zero
169 * if the first argument is considered to be respectively
170 * less than, equal to, or greater than the second.
173 state_compare (const void *a, const void *b)
175 struct GNUNET_REGEX_State **s1;
176 struct GNUNET_REGEX_State **s2;
178 s1 = (struct GNUNET_REGEX_State **) a;
179 s2 = (struct GNUNET_REGEX_State **) b;
181 return (*s1)->id - (*s2)->id;
186 * Get all edges leaving state 's'.
189 * @param edges all edges leaving 's', expected to be allocated and have enough
190 * space for s->transitions_count elements.
192 * @return number of edges.
195 state_get_edges (struct GNUNET_REGEX_State *s, struct GNUNET_REGEX_Edge *edges)
197 struct GNUNET_REGEX_Transition *t;
205 for (t = s->transitions_head; NULL != t; t = t->next)
207 if (NULL != t->to_state)
209 edges[count].label = t->label;
210 edges[count].destination = t->to_state->hash;
219 * Compare to state sets by comparing the id's of the states that are contained
220 * in each set. Both sets are expected to be sorted by id!
222 * @param sset1 first state set
223 * @param sset2 second state set
225 * @return an integer less than, equal to, or greater than zero
226 * if the first argument is considered to be respectively
227 * less than, equal to, or greater than the second.
230 state_set_compare (struct GNUNET_REGEX_StateSet *sset1,
231 struct GNUNET_REGEX_StateSet *sset2)
236 if (NULL == sset1 || NULL == sset2)
239 result = sset1->len - sset2->len;
241 for (i = 0; i < sset1->len; i++)
246 result = state_compare (&sset1->states[i], &sset2->states[i]);
253 * Clears the given StateSet 'set'
255 * @param set set to be cleared
258 state_set_clear (struct GNUNET_REGEX_StateSet *set)
262 GNUNET_free_non_null (set->states);
269 * Clears an automaton fragment. Does not destroy the states inside the
272 * @param a automaton to be cleared
275 automaton_fragment_clear (struct GNUNET_REGEX_Automaton *a)
282 a->states_head = NULL;
283 a->states_tail = NULL;
290 * Frees the memory used by State 's'
292 * @param s state that should be destroyed
295 automaton_destroy_state (struct GNUNET_REGEX_State *s)
297 struct GNUNET_REGEX_Transition *t;
298 struct GNUNET_REGEX_Transition *next_t;
303 GNUNET_free_non_null (s->name);
304 GNUNET_free_non_null (s->proof);
306 for (t = s->transitions_head; NULL != t; t = next_t)
309 GNUNET_CONTAINER_DLL_remove (s->transitions_head, s->transitions_tail, t);
310 GNUNET_free_non_null (t->label);
314 state_set_clear (s->nfa_set);
321 * Remove a state from the given automaton 'a'. Always use this function when
322 * altering the states of an automaton. Will also remove all transitions leading
323 * to this state, before destroying it.
326 * @param s state to remove
329 automaton_remove_state (struct GNUNET_REGEX_Automaton *a,
330 struct GNUNET_REGEX_State *s)
332 struct GNUNET_REGEX_State *ss;
333 struct GNUNET_REGEX_State *s_check;
334 struct GNUNET_REGEX_Transition *t_check;
336 if (NULL == a || NULL == s)
341 GNUNET_CONTAINER_DLL_remove (a->states_head, a->states_tail, s);
344 // remove all transitions leading to this state
345 for (s_check = a->states_head; NULL != s_check; s_check = s_check->next)
347 for (t_check = s_check->transitions_head; NULL != t_check;
348 t_check = t_check->next)
350 if (t_check->to_state == ss)
352 GNUNET_CONTAINER_DLL_remove (s_check->transitions_head,
353 s_check->transitions_tail, t_check);
354 s_check->transition_count--;
359 automaton_destroy_state (ss);
364 * Merge two states into one. Will merge 's1' and 's2' into 's1' and destroy
369 * @param s1 first state
370 * @param s2 second state, will be destroyed
373 automaton_merge_states (struct GNUNET_REGEX_Context *ctx,
374 struct GNUNET_REGEX_Automaton *a,
375 struct GNUNET_REGEX_State *s1,
376 struct GNUNET_REGEX_State *s2)
378 struct GNUNET_REGEX_State *s_check;
379 struct GNUNET_REGEX_Transition *t_check;
380 struct GNUNET_REGEX_Transition *t;
381 struct GNUNET_REGEX_Transition *t_next;
385 GNUNET_assert (NULL != ctx && NULL != a && NULL != s1 && NULL != s2);
390 // 1. Make all transitions pointing to s2 point to s1, unless this transition
391 // does not already exists, if it already exists remove transition.
392 for (s_check = a->states_head; NULL != s_check; s_check = s_check->next)
394 for (t_check = s_check->transitions_head; NULL != t_check; t_check = t_next)
396 t_next = t_check->next;
398 if (s2 == t_check->to_state)
401 for (t = t_check->from_state->transitions_head; NULL != t; t = t->next)
403 if (t->to_state == s1 && 0 == strcmp (t_check->label, t->label))
406 if (GNUNET_NO == is_dup)
407 t_check->to_state = s1;
409 state_remove_transition (t_check->from_state, t_check);
414 // 2. Add all transitions from s2 to sX to s1
415 for (t_check = s2->transitions_head; NULL != t_check; t_check = t_check->next)
417 if (t_check->to_state != s1)
418 state_add_transition (ctx, s1, t_check->label, t_check->to_state);
421 // 3. Rename s1 to {s1,s2}
423 GNUNET_asprintf (&s1->name, "{%s,%s}", new_name, s2->name);
424 GNUNET_free (new_name);
427 GNUNET_CONTAINER_DLL_remove (a->states_head, a->states_tail, s2);
429 automaton_destroy_state (s2);
434 * Add a state to the automaton 'a', always use this function to alter the
435 * states DLL of the automaton.
437 * @param a automaton to add the state to
438 * @param s state that should be added
441 automaton_add_state (struct GNUNET_REGEX_Automaton *a,
442 struct GNUNET_REGEX_State *s)
444 GNUNET_CONTAINER_DLL_insert (a->states_head, a->states_tail, s);
450 * Depth-first traversal (DFS) of all states that are reachable from state
451 * 's'. Performs 'action' on each visited state.
453 * @param s start state.
454 * @param marks an array of size a->state_count to remember which state was
456 * @param count current count of the state.
457 * @param check function that is checked before advancing on each transition
459 * @param check_cls closure for check.
460 * @param action action to be performed on each state.
461 * @param action_cls closure for action.
464 automaton_state_traverse (struct GNUNET_REGEX_State *s, int *marks,
466 GNUNET_REGEX_traverse_check check, void *check_cls,
467 GNUNET_REGEX_traverse_action action, void *action_cls)
469 struct GNUNET_REGEX_Transition *t;
471 if (GNUNET_YES == marks[s->traversal_id])
474 marks[s->traversal_id] = GNUNET_YES;
477 action (action_cls, *count, s);
481 for (t = s->transitions_head; NULL != t; t = t->next)
484 (NULL != check && GNUNET_YES == check (check_cls, s, t)))
486 automaton_state_traverse (t->to_state, marks, count, check, check_cls,
494 * Traverses the given automaton using depth-first-search (DFS) from it's start
495 * state, visiting all reachable states and calling 'action' on each one of
498 * @param a automaton to be traversed.
499 * @param start start state, pass a->start or NULL to traverse the whole automaton.
500 * @param check function that is checked before advancing on each transition
502 * @param check_cls closure for check.
503 * @param action action to be performed on each state.
504 * @param action_cls closure for action
507 GNUNET_REGEX_automaton_traverse (const struct GNUNET_REGEX_Automaton *a,
508 struct GNUNET_REGEX_State *start,
509 GNUNET_REGEX_traverse_check check,
511 GNUNET_REGEX_traverse_action action,
515 struct GNUNET_REGEX_State *s;
516 int marks[a->state_count];
518 if (NULL == a || 0 == a->state_count)
521 for (count = 0, s = a->states_head; NULL != s && count < a->state_count;
522 s = s->next, count++)
524 s->traversal_id = count;
525 marks[s->traversal_id] = GNUNET_NO;
535 automaton_state_traverse (s, marks, &count, check, check_cls, action,
541 * Context for adding strided transitions to a DFA.
543 struct GNUNET_REGEX_Strided_Context
546 * Length of the strides.
548 const unsigned int stride;
551 * Strided transitions DLL. New strided transitions will be stored in this DLL
552 * and afterwards added to the DFA.
554 struct GNUNET_REGEX_Transition *transitions_head;
557 * Strided transitions DLL.
559 struct GNUNET_REGEX_Transition *transitions_tail;
564 * Recursive helper function to add strides to a DFA.
566 * @param cls context, contains stride length and strided transitions DLL.
567 * @param depth current depth of the depth-first traversal of the graph.
568 * @param label current label, string that contains all labels on the path from
570 * @param start start state for the depth-first traversal of the graph.
571 * @param s current state in the depth-first traversal
574 add_multi_strides_to_dfa_helper (void *cls, const unsigned int depth,
575 char *label, struct GNUNET_REGEX_State *start,
576 struct GNUNET_REGEX_State *s)
578 struct GNUNET_REGEX_Strided_Context *ctx = cls;
579 struct GNUNET_REGEX_Transition *t;
582 if (depth == ctx->stride)
584 t = GNUNET_malloc (sizeof (struct GNUNET_REGEX_Transition));
585 t->label = GNUNET_strdup (label);
587 t->from_state = start;
588 GNUNET_CONTAINER_DLL_insert (ctx->transitions_head, ctx->transitions_tail,
593 for (t = s->transitions_head; NULL != t; t = t->next)
595 /* Do not consider self-loops, because it end's up in too many
597 if (t->to_state == t->from_state)
602 GNUNET_asprintf (&new_label, "%s%s", label, t->label);
605 new_label = GNUNET_strdup (t->label);
607 add_multi_strides_to_dfa_helper (cls, (depth + 1), new_label, start,
611 GNUNET_free_non_null (label);
616 * Function called for each state in the DFA. Starts a traversal of depth set in
617 * context starting from state 's'.
619 * @param cls context.
620 * @param count not used.
621 * @param s current state.
624 add_multi_strides_to_dfa (void *cls, const unsigned int count,
625 struct GNUNET_REGEX_State *s)
627 add_multi_strides_to_dfa_helper (cls, 0, NULL, s, s);
632 * Adds multi-strided transitions to the given 'dfa'.
634 * @param regex_ctx regex context needed to add transitions to the automaton.
635 * @param dfa DFA to which the multi strided transitions should be added.
636 * @param stride_len length of the strides.
639 GNUNET_REGEX_add_multi_strides_to_dfa (struct GNUNET_REGEX_Context *regex_ctx,
640 struct GNUNET_REGEX_Automaton *dfa,
641 const unsigned int stride_len)
643 struct GNUNET_REGEX_Strided_Context ctx = { stride_len, NULL, NULL };
644 struct GNUNET_REGEX_Transition *t;
645 struct GNUNET_REGEX_Transition *t_next;
650 // Compute the new transitions.
651 GNUNET_REGEX_automaton_traverse (dfa, dfa->start, NULL, NULL,
652 &add_multi_strides_to_dfa, &ctx);
654 // Add all the new transitions to the automaton.
655 for (t = ctx.transitions_head; NULL != t; t = t_next)
658 state_add_transition (regex_ctx, t->from_state, t->label, t->to_state);
659 GNUNET_CONTAINER_DLL_remove (ctx.transitions_head, ctx.transitions_tail, t);
660 GNUNET_free_non_null (t->label);
668 * Check if the given string 'str' needs parentheses around it when
669 * using it to generate a regex.
673 * @return GNUNET_YES if parentheses are needed, GNUNET_NO otherwise
676 needs_parentheses (const char *str)
684 if ((NULL == str) || ((slen = strlen (str)) < 2))
693 cl = strchr (pos, ')');
699 op = strchr (pos, '(');
700 if ((NULL != op) && (op < cl))
710 return (*pos == '\0') ? GNUNET_NO : GNUNET_YES;
715 * Remove parentheses surrounding string 'str'.
716 * Example: "(a)" becomes "a", "(a|b)|(a|c)" stays the same.
717 * You need to GNUNET_free the returned string.
719 * @param str string, free'd or re-used by this function, can be NULL
721 * @return string without surrounding parentheses, string 'str' if no preceding
722 * epsilon could be found, NULL if 'str' was NULL
725 remove_parentheses (char *str)
730 if ((NULL == str) || ('(' != str[0]) ||
731 (str[(slen = strlen (str)) - 1] != ')'))
734 pos = strchr (&str[1], ')');
735 if (pos == &str[slen - 1])
737 memmove (str, &str[1], slen - 2);
738 str[slen - 2] = '\0';
745 * Check if the string 'str' starts with an epsilon (empty string).
746 * Example: "(|a)" is starting with an epsilon.
748 * @param str string to test
750 * @return 0 if str has no epsilon, 1 if str starts with '(|' and ends with ')'
753 has_epsilon (const char *str)
755 return (NULL != str) && ('(' == str[0]) && ('|' == str[1]) &&
756 (')' == str[strlen (str) - 1]);
761 * Remove an epsilon from the string str. Where epsilon is an empty string
762 * Example: str = "(|a|b|c)", result: "a|b|c"
763 * The returned string needs to be freed.
767 * @return string without preceding epsilon, string 'str' if no preceding
768 * epsilon could be found, NULL if 'str' was NULL
771 remove_epsilon (const char *str)
777 if (('(' == str[0]) && ('|' == str[1]))
780 if (')' == str[len - 1])
781 return GNUNET_strndup (&str[2], len - 3);
783 return GNUNET_strdup (str);
788 * Compare 'str1', starting from position 'k', with whole 'str2'
790 * @param str1 first string to compare, starting from position 'k'
791 * @param str2 second string for comparison
792 * @param k starting position in 'str1'
794 * @return -1 if any of the strings is NULL, 0 if equal, non 0 otherwise
797 strkcmp (const char *str1, const char *str2, size_t k)
799 if ((NULL == str1) || (NULL == str2) || (strlen (str1) < k))
801 return strcmp (&str1[k], str2);
806 * Helper function used as 'action' in 'GNUNET_REGEX_automaton_traverse'
807 * function to create the depth-first numbering of the states.
809 * @param cls states array.
810 * @param count current state counter.
811 * @param s current state.
814 number_states (void *cls, const unsigned int count,
815 struct GNUNET_REGEX_State *s)
817 struct GNUNET_REGEX_State **states = cls;
826 * Construct the regular expression given the inductive step,
827 * $R^{(k)}_{ij} = R^{(k-1)}_{ij} | R^{(k-1)}_{ik} ( R^{(k-1)}_{kk} )^*
828 * R^{(k-1)}_{kj}, and simplify the resulting expression saved in R_cur_ij.
830 * @param R_last_ij value of $R^{(k-1)_{ij}.
831 * @param R_last_ik value of $R^{(k-1)_{ik}.
832 * @param R_last_kk value of $R^{(k-1)_{kk}.
833 * @param R_last_kj value of $R^{(k-1)_{kj}.
834 * @param R_cur_ij result for this inductive step is saved in R_cur_ij, R_cur_ij
835 * is expected to be NULL when called!
838 automaton_create_proofs_simplify (char *R_last_ij, char *R_last_ik,
839 char *R_last_kk, char *R_last_kj,
865 GNUNET_assert (NULL == *R_cur_ij && NULL != R_cur_ij);
867 // $R^{(k)}_{ij} = R^{(k-1)}_{ij} | R^{(k-1)}_{ik} ( R^{(k-1)}_{kk} )^* R^{(k-1)}_{kj}
868 // R_last == R^{(k-1)}, R_cur == R^{(k)}
869 // R_cur_ij = R_cur_l | R_cur_r
870 // R_cur_l == R^{(k-1)}_{ij}
871 // R_cur_r == R^{(k-1)}_{ik} ( R^{(k-1)}_{kk} )^* R^{(k-1)}_{kj}
873 if ((NULL == R_last_ij) && ((NULL == R_last_ik) || (NULL == R_last_kk) || /* technically cannot happen, but looks saner */
874 (NULL == R_last_kj)))
876 /* R^{(k)}_{ij} = N | N */
881 if ((NULL == R_last_ik) || (NULL == R_last_kk) || /* technically cannot happen, but looks saner */
884 /* R^{(k)}_{ij} = R^{(k-1)}_{ij} | N */
885 *R_cur_ij = GNUNET_strdup (R_last_ij);
889 // $R^{(k)}_{ij} = N | R^{(k-1)}_{ik} ( R^{(k-1)}_{kk} )^* R^{(k-1)}_{kj} OR
890 // $R^{(k)}_{ij} = R^{(k-1)}_{ij} | R^{(k-1)}_{ik} ( R^{(k-1)}_{kk} )^* R^{(k-1)}_{kj}
895 // cache results from strcmp, we might need these many times
896 ij_kj_cmp = nullstrcmp (R_last_ij, R_last_kj);
897 ij_ik_cmp = nullstrcmp (R_last_ij, R_last_ik);
898 ik_kk_cmp = nullstrcmp (R_last_ik, R_last_kk);
899 kk_kj_cmp = nullstrcmp (R_last_kk, R_last_kj);
901 // Assign R_temp_(ik|kk|kj) to R_last[][] and remove epsilon as well
902 // as parentheses, so we can better compare the contents
903 R_temp_ik = remove_parentheses (remove_epsilon (R_last_ik));
904 R_temp_kk = remove_parentheses (remove_epsilon (R_last_kk));
905 R_temp_kj = remove_parentheses (remove_epsilon (R_last_kj));
907 clean_ik_kk_cmp = nullstrcmp (R_last_ik, R_temp_kk);
908 clean_kk_kj_cmp = nullstrcmp (R_temp_kk, R_last_kj);
910 // construct R_cur_l (and, if necessary R_cur_r)
911 if (NULL != R_last_ij)
913 // Assign R_temp_ij to R_last_ij and remove epsilon as well
914 // as parentheses, so we can better compare the contents
915 R_temp_ij = remove_parentheses (remove_epsilon (R_last_ij));
917 if (0 == strcmp (R_temp_ij, R_temp_ik) && 0 == strcmp (R_temp_ik, R_temp_kk)
918 && 0 == strcmp (R_temp_kk, R_temp_kj))
920 if (0 == strlen (R_temp_ij))
922 R_cur_r = GNUNET_strdup ("");
924 else if ((0 == strncmp (R_last_ij, "(|", 2)) ||
925 (0 == strncmp (R_last_ik, "(|", 2) &&
926 0 == strncmp (R_last_kj, "(|", 2)))
928 // a|(e|a)a*(e|a) = a*
929 // a|(e|a)(e|a)*(e|a) = a*
931 // (e|a)|aa*(e|a) = a*
932 // (e|a)|(e|a)a*a = a*
933 // (e|a)|(e|a)a*(e|a) = a*
934 // (e|a)|(e|a)(e|a)*(e|a) = a*
935 if (GNUNET_YES == needs_parentheses (R_temp_ij))
936 GNUNET_asprintf (&R_cur_r, "(%s)*", R_temp_ij);
938 GNUNET_asprintf (&R_cur_r, "%s*", R_temp_ij);
945 // a|(e|a)(e|a)*a = a+
946 // a|a(e|a)*(e|a) = a+
947 if (GNUNET_YES == needs_parentheses (R_temp_ij))
948 GNUNET_asprintf (&R_cur_r, "(%s)+", R_temp_ij);
950 GNUNET_asprintf (&R_cur_r, "%s+", R_temp_ij);
953 else if (0 == ij_ik_cmp && 0 == clean_kk_kj_cmp && 0 != clean_ik_kk_cmp)
956 if (strlen (R_last_kk) < 1)
957 R_cur_r = GNUNET_strdup (R_last_ij);
958 else if (GNUNET_YES == needs_parentheses (R_temp_kk))
959 GNUNET_asprintf (&R_cur_r, "%s(%s)*", R_last_ij, R_temp_kk);
961 GNUNET_asprintf (&R_cur_r, "%s%s*", R_last_ij, R_last_kk);
965 else if (0 == ij_kj_cmp && 0 == clean_ik_kk_cmp && 0 != clean_kk_kj_cmp)
968 if (strlen (R_last_kk) < 1)
969 R_cur_r = GNUNET_strdup (R_last_kj);
970 else if (GNUNET_YES == needs_parentheses (R_temp_kk))
971 GNUNET_asprintf (&R_cur_r, "(%s)*%s", R_temp_kk, R_last_kj);
973 GNUNET_asprintf (&R_cur_r, "%s*%s", R_temp_kk, R_last_kj);
977 else if (0 == ij_ik_cmp && 0 == kk_kj_cmp && !has_epsilon (R_last_ij) &&
978 has_epsilon (R_last_kk))
980 // a|a(e|b)*(e|b) = a|ab* = a|a|ab|abb|abbb|... = ab*
981 if (needs_parentheses (R_temp_kk))
982 GNUNET_asprintf (&R_cur_r, "%s(%s)*", R_last_ij, R_temp_kk);
984 GNUNET_asprintf (&R_cur_r, "%s%s*", R_last_ij, R_temp_kk);
988 else if (0 == ij_kj_cmp && 0 == ik_kk_cmp && !has_epsilon (R_last_ij) &&
989 has_epsilon (R_last_kk))
991 // a|(e|b)(e|b)*a = a|b*a = a|a|ba|bba|bbba|... = b*a
992 if (needs_parentheses (R_temp_kk))
993 GNUNET_asprintf (&R_cur_r, "(%s)*%s", R_temp_kk, R_last_ij);
995 GNUNET_asprintf (&R_cur_r, "%s*%s", R_temp_kk, R_last_ij);
1001 temp_a = (NULL == R_last_ij) ? NULL : GNUNET_strdup (R_last_ij);
1002 temp_a = remove_parentheses (temp_a);
1006 GNUNET_free_non_null (R_temp_ij);
1010 // we have no left side
1014 // construct R_cur_r, if not already constructed
1015 if (NULL == R_cur_r)
1017 length = strlen (R_temp_kk) - strlen (R_last_ik);
1019 // a(ba)*bx = (ab)+x
1020 if (length > 0 && NULL != R_last_kk && 0 < strlen (R_last_kk) &&
1021 NULL != R_last_kj && 0 < strlen (R_last_kj) && NULL != R_last_ik &&
1022 0 < strlen (R_last_ik) && 0 == strkcmp (R_temp_kk, R_last_ik, length) &&
1023 0 == strncmp (R_temp_kk, R_last_kj, length))
1025 temp_a = GNUNET_malloc (length + 1);
1026 temp_b = GNUNET_malloc ((strlen (R_last_kj) - length) + 1);
1031 for (cnt = 0; cnt < strlen (R_last_kj); cnt++)
1035 temp_a[length_l] = R_last_kj[cnt];
1040 temp_b[length_r] = R_last_kj[cnt];
1044 temp_a[length_l] = '\0';
1045 temp_b[length_r] = '\0';
1048 if (NULL != R_cur_l && 0 == strlen (R_cur_l) && 0 == strlen (temp_b))
1050 GNUNET_asprintf (&R_cur_r, "(%s%s)*", R_last_ik, temp_a);
1051 GNUNET_free (R_cur_l);
1056 GNUNET_asprintf (&R_cur_r, "(%s%s)+%s", R_last_ik, temp_a, temp_b);
1058 GNUNET_free (temp_a);
1059 GNUNET_free (temp_b);
1061 else if (0 == strcmp (R_temp_ik, R_temp_kk) &&
1062 0 == strcmp (R_temp_kk, R_temp_kj))
1064 // (e|a)a*(e|a) = a*
1065 // (e|a)(e|a)*(e|a) = a*
1066 if (has_epsilon (R_last_ik) && has_epsilon (R_last_kj))
1068 if (needs_parentheses (R_temp_kk))
1069 GNUNET_asprintf (&R_cur_r, "(%s)*", R_temp_kk);
1071 GNUNET_asprintf (&R_cur_r, "%s*", R_temp_kk);
1074 else if (0 == clean_ik_kk_cmp && 0 == clean_kk_kj_cmp &&
1075 !has_epsilon (R_last_ik))
1077 if (needs_parentheses (R_temp_kk))
1078 GNUNET_asprintf (&R_cur_r, "(%s)+%s", R_temp_kk, R_temp_kk);
1080 GNUNET_asprintf (&R_cur_r, "(%s)+%s", R_temp_kk, R_temp_kk);
1084 // a(e|a)*(e|a) = a+
1089 (has_epsilon (R_last_ik) + has_epsilon (R_last_kk) +
1090 has_epsilon (R_last_kj));
1094 if (needs_parentheses (R_temp_kk))
1095 GNUNET_asprintf (&R_cur_r, "(%s)+", R_temp_kk);
1097 GNUNET_asprintf (&R_cur_r, "%s+", R_temp_kk);
1102 // (e|a)(e|a)*b = a*b
1103 else if (0 == strcmp (R_temp_ik, R_temp_kk))
1105 if (has_epsilon (R_last_ik))
1107 if (needs_parentheses (R_temp_kk))
1108 GNUNET_asprintf (&R_cur_r, "(%s)*%s", R_temp_kk, R_last_kj);
1110 GNUNET_asprintf (&R_cur_r, "%s*%s", R_temp_kk, R_last_kj);
1114 if (needs_parentheses (R_temp_kk))
1115 GNUNET_asprintf (&R_cur_r, "(%s)+%s", R_temp_kk, R_last_kj);
1117 GNUNET_asprintf (&R_cur_r, "%s+%s", R_temp_kk, R_last_kj);
1121 // b(e|a)*(e|a) = ba*
1122 else if (0 == strcmp (R_temp_kk, R_temp_kj))
1124 if (has_epsilon (R_last_kj))
1126 if (needs_parentheses (R_temp_kk))
1127 GNUNET_asprintf (&R_cur_r, "%s(%s)*", R_last_ik, R_temp_kk);
1129 GNUNET_asprintf (&R_cur_r, "%s%s*", R_last_ik, R_temp_kk);
1133 if (needs_parentheses (R_temp_kk))
1134 GNUNET_asprintf (&R_cur_r, "(%s)+%s", R_last_ik, R_temp_kk);
1136 GNUNET_asprintf (&R_cur_r, "%s+%s", R_last_ik, R_temp_kk);
1141 if (strlen (R_temp_kk) > 0)
1143 if (needs_parentheses (R_temp_kk))
1145 GNUNET_asprintf (&R_cur_r, "%s(%s)*%s", R_last_ik, R_temp_kk,
1150 GNUNET_asprintf (&R_cur_r, "%s%s*%s", R_last_ik, R_temp_kk,
1156 GNUNET_asprintf (&R_cur_r, "%s%s", R_last_ik, R_last_kj);
1161 GNUNET_free_non_null (R_temp_ik);
1162 GNUNET_free_non_null (R_temp_kk);
1163 GNUNET_free_non_null (R_temp_kj);
1165 if (NULL == R_cur_l && NULL == R_cur_r)
1171 if (NULL != R_cur_l && NULL == R_cur_r)
1173 *R_cur_ij = R_cur_l;
1177 if (NULL == R_cur_l && NULL != R_cur_r)
1179 *R_cur_ij = R_cur_r;
1183 if (0 == nullstrcmp (R_cur_l, R_cur_r))
1185 *R_cur_ij = R_cur_l;
1186 GNUNET_free (R_cur_r);
1190 GNUNET_asprintf (R_cur_ij, "(%s|%s)", R_cur_l, R_cur_r);
1192 GNUNET_free (R_cur_l);
1193 GNUNET_free (R_cur_r);
1198 * create proofs for all states in the given automaton. Implementation of the
1199 * algorithm descriped in chapter 3.2.1 of "Automata Theory, Languages, and
1200 * Computation 3rd Edition" by Hopcroft, Motwani and Ullman.
1202 * @param a automaton.
1205 automaton_create_proofs (struct GNUNET_REGEX_Automaton *a)
1207 unsigned int n = a->state_count;
1208 struct GNUNET_REGEX_State *states[n];
1212 struct GNUNET_REGEX_Transition *t;
1213 char *complete_regex;
1220 GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
1221 "Could not create proofs, automaton was NULL\n");
1225 /* create depth-first numbering of the states, initializes 'state' */
1226 GNUNET_REGEX_automaton_traverse (a, a->start, NULL, NULL, &number_states,
1229 for (i = 0; i < n; i++)
1230 GNUNET_assert (NULL != states[i]);
1232 /* Compute regular expressions of length "1" between each pair of states */
1233 for (i = 0; i < n; i++)
1235 for (j = 0; j < n; j++)
1238 R_last[i][j] = NULL;
1240 for (t = states[i]->transitions_head; NULL != t; t = t->next)
1242 j = t->to_state->dfs_id;
1243 if (NULL == R_last[i][j])
1244 GNUNET_asprintf (&R_last[i][j], "%s", t->label);
1247 temp = R_last[i][j];
1248 GNUNET_asprintf (&R_last[i][j], "%s|%s", R_last[i][j], t->label);
1252 if (NULL == R_last[i][i])
1253 GNUNET_asprintf (&R_last[i][i], "");
1256 temp = R_last[i][i];
1257 GNUNET_asprintf (&R_last[i][i], "(|%s)", R_last[i][i]);
1261 for (i = 0; i < n; i++)
1262 for (j = 0; j < n; j++)
1263 if (needs_parentheses (R_last[i][j]))
1265 temp = R_last[i][j];
1266 GNUNET_asprintf (&R_last[i][j], "(%s)", R_last[i][j]);
1270 /* Compute regular expressions of length "k" between each pair of states per
1272 for (k = 0; k < n; k++)
1274 for (i = 0; i < n; i++)
1276 for (j = 0; j < n; j++)
1278 // Basis for the recursion:
1279 // $R^{(k)}_{ij} = R^{(k-1)}_{ij} | R^{(k-1)}_{ik} ( R^{(k-1)}_{kk} )^* R^{(k-1)}_{kj}
1280 // R_last == R^{(k-1)}, R_cur == R^{(k)}
1282 // Create R_cur[i][j] and simplify the expression
1283 automaton_create_proofs_simplify (R_last[i][j], R_last[i][k],
1284 R_last[k][k], R_last[k][j],
1289 // set R_last = R_cur
1290 for (i = 0; i < n; i++)
1292 for (j = 0; j < n; j++)
1294 GNUNET_free_non_null (R_last[i][j]);
1295 R_last[i][j] = R_cur[i][j];
1301 // assign proofs and hashes
1302 for (i = 0; i < n; i++)
1304 if (NULL != R_last[a->start->dfs_id][i])
1306 states[i]->proof = GNUNET_strdup (R_last[a->start->dfs_id][i]);
1307 GNUNET_CRYPTO_hash (states[i]->proof, strlen (states[i]->proof),
1312 // complete regex for whole DFA: union of all pairs (start state/accepting
1314 complete_regex = NULL;
1315 for (i = 0; i < n; i++)
1317 if (states[i]->accepting)
1319 if (NULL == complete_regex && 0 < strlen (R_last[a->start->dfs_id][i]))
1321 GNUNET_asprintf (&complete_regex, "%s", R_last[a->start->dfs_id][i]);
1323 else if (NULL != R_last[a->start->dfs_id][i] &&
1324 0 < strlen (R_last[a->start->dfs_id][i]))
1326 temp = complete_regex;
1327 GNUNET_asprintf (&complete_regex, "%s|%s", complete_regex,
1328 R_last[a->start->dfs_id][i]);
1333 a->canonical_regex = complete_regex;
1336 for (i = 0; i < n; i++)
1338 for (j = 0; j < n; j++)
1339 GNUNET_free_non_null (R_last[i][j]);
1345 * Creates a new DFA state based on a set of NFA states. Needs to be freed using
1346 * automaton_destroy_state.
1348 * @param ctx context
1349 * @param nfa_states set of NFA states on which the DFA should be based on
1351 * @return new DFA state
1353 static struct GNUNET_REGEX_State *
1354 dfa_state_create (struct GNUNET_REGEX_Context *ctx,
1355 struct GNUNET_REGEX_StateSet *nfa_states)
1357 struct GNUNET_REGEX_State *s;
1360 struct GNUNET_REGEX_State *cstate;
1361 struct GNUNET_REGEX_Transition *ctran;
1364 s = GNUNET_malloc (sizeof (struct GNUNET_REGEX_State));
1365 s->id = ctx->state_id++;
1367 s->marked = GNUNET_NO;
1375 if (NULL == nfa_states)
1377 GNUNET_asprintf (&s->name, "s%i", s->id);
1381 s->nfa_set = nfa_states;
1383 if (nfa_states->len < 1)
1386 // Create a name based on 'sset'
1387 s->name = GNUNET_malloc (sizeof (char) * 2);
1388 strcat (s->name, "{");
1391 for (i = 0; i < nfa_states->len; i++)
1393 cstate = nfa_states->states[i];
1394 GNUNET_asprintf (&name, "%i,", cstate->id);
1398 len = strlen (s->name) + strlen (name) + 1;
1399 s->name = GNUNET_realloc (s->name, len);
1400 strcat (s->name, name);
1405 // Add a transition for each distinct label to NULL state
1406 for (ctran = cstate->transitions_head; NULL != ctran; ctran = ctran->next)
1408 if (NULL != ctran->label)
1409 state_add_transition (ctx, s, ctran->label, NULL);
1412 // If the nfa_states contain an accepting state, the new dfa state is also
1414 if (cstate->accepting)
1418 s->name[strlen (s->name) - 1] = '}';
1425 * Move from the given state 's' to the next state on transition 'label'
1427 * @param s starting state
1428 * @param label edge label to follow
1430 * @return new state or NULL, if transition on label not possible
1432 static struct GNUNET_REGEX_State *
1433 dfa_move (struct GNUNET_REGEX_State *s, const char *label)
1435 struct GNUNET_REGEX_Transition *t;
1436 struct GNUNET_REGEX_State *new_s;
1443 for (t = s->transitions_head; NULL != t; t = t->next)
1445 // TODO: Use strstr to match substring and return number of char's that have
1447 if (0 == strcmp (label, t->label))
1449 new_s = t->to_state;
1458 * Set the given state 'marked' to GNUNET_YES. Used by the
1459 * 'dfa_remove_unreachable_states' function to detect unreachable states in the
1462 * @param cls closure, not used.
1463 * @param count count, not used.
1464 * @param s state where the marked attribute will be set to GNUNET_YES.
1467 mark_states (void *cls, const unsigned int count, struct GNUNET_REGEX_State *s)
1469 s->marked = GNUNET_YES;
1473 * Remove all unreachable states from DFA 'a'. Unreachable states are those
1474 * states that are not reachable from the starting state.
1476 * @param a DFA automaton
1479 dfa_remove_unreachable_states (struct GNUNET_REGEX_Automaton *a)
1481 struct GNUNET_REGEX_State *s;
1482 struct GNUNET_REGEX_State *s_next;
1484 // 1. unmark all states
1485 for (s = a->states_head; NULL != s; s = s->next)
1486 s->marked = GNUNET_NO;
1488 // 2. traverse dfa from start state and mark all visited states
1489 GNUNET_REGEX_automaton_traverse (a, a->start, NULL, NULL, &mark_states, NULL);
1491 // 3. delete all states that were not visited
1492 for (s = a->states_head; NULL != s; s = s_next)
1495 if (GNUNET_NO == s->marked)
1496 automaton_remove_state (a, s);
1502 * Remove all dead states from the DFA 'a'. Dead states are those states that do
1503 * not transition to any other state but themselves.
1505 * @param a DFA automaton
1508 dfa_remove_dead_states (struct GNUNET_REGEX_Automaton *a)
1510 struct GNUNET_REGEX_State *s;
1511 struct GNUNET_REGEX_Transition *t;
1514 GNUNET_assert (DFA == a->type);
1516 for (s = a->states_head; NULL != s; s = s->next)
1522 for (t = s->transitions_head; NULL != t; t = t->next)
1524 if (NULL != t->to_state && t->to_state != s)
1534 // state s is dead, remove it
1535 automaton_remove_state (a, s);
1541 * Merge all non distinguishable states in the DFA 'a'
1543 * @param ctx context
1544 * @param a DFA automaton
1547 dfa_merge_nondistinguishable_states (struct GNUNET_REGEX_Context *ctx,
1548 struct GNUNET_REGEX_Automaton *a)
1550 int table[a->state_count][a->state_count];
1551 struct GNUNET_REGEX_State *s1;
1552 struct GNUNET_REGEX_State *s2;
1553 struct GNUNET_REGEX_Transition *t1;
1554 struct GNUNET_REGEX_Transition *t2;
1555 struct GNUNET_REGEX_State *s1_next;
1556 struct GNUNET_REGEX_State *s2_next;
1558 unsigned int num_equal_edges;
1561 for (i = 0, s1 = a->states_head; i < a->state_count && NULL != s1;
1567 // Mark all pairs of accepting/!accepting states
1568 for (s1 = a->states_head; NULL != s1; s1 = s1->next)
1570 for (s2 = a->states_head; NULL != s2; s2 = s2->next)
1572 table[s1->marked][s2->marked] = 0;
1574 if ((s1->accepting && !s2->accepting) ||
1575 (!s1->accepting && s2->accepting))
1577 table[s1->marked][s2->marked] = 1;
1582 // Find all equal states
1587 for (s1 = a->states_head; NULL != s1; s1 = s1->next)
1589 for (s2 = a->states_head; NULL != s2 && s1 != s2; s2 = s2->next)
1591 if (0 != table[s1->marked][s2->marked])
1594 num_equal_edges = 0;
1595 for (t1 = s1->transitions_head; NULL != t1; t1 = t1->next)
1597 for (t2 = s2->transitions_head; NULL != t2; t2 = t2->next)
1599 if (0 == strcmp (t1->label, t2->label))
1602 if (0 != table[t1->to_state->marked][t2->to_state->marked] ||
1603 0 != table[t2->to_state->marked][t1->to_state->marked])
1605 table[s1->marked][s2->marked] = 1;
1611 if (num_equal_edges != s1->transition_count ||
1612 num_equal_edges != s2->transition_count)
1614 // Make sure ALL edges of possible equal states are the same
1615 table[s1->marked][s2->marked] = -2;
1621 // Merge states that are equal
1622 for (s1 = a->states_head; NULL != s1; s1 = s1_next)
1625 for (s2 = a->states_head; NULL != s2 && s1 != s2; s2 = s2_next)
1628 if (table[s1->marked][s2->marked] == 0)
1629 automaton_merge_states (ctx, a, s1, s2);
1636 * Minimize the given DFA 'a' by removing all unreachable states, removing all
1637 * dead states and merging all non distinguishable states
1639 * @param ctx context
1640 * @param a DFA automaton
1643 dfa_minimize (struct GNUNET_REGEX_Context *ctx,
1644 struct GNUNET_REGEX_Automaton *a)
1649 GNUNET_assert (DFA == a->type);
1651 // 1. remove unreachable states
1652 dfa_remove_unreachable_states (a);
1654 // 2. remove dead states
1655 dfa_remove_dead_states (a);
1657 // 3. Merge nondistinguishable states
1658 dfa_merge_nondistinguishable_states (ctx, a);
1663 * Creates a new NFA fragment. Needs to be cleared using
1664 * automaton_fragment_clear.
1666 * @param start starting state
1667 * @param end end state
1669 * @return new NFA fragment
1671 static struct GNUNET_REGEX_Automaton *
1672 nfa_fragment_create (struct GNUNET_REGEX_State *start,
1673 struct GNUNET_REGEX_State *end)
1675 struct GNUNET_REGEX_Automaton *n;
1677 n = GNUNET_malloc (sizeof (struct GNUNET_REGEX_Automaton));
1684 if (NULL == start || NULL == end)
1687 automaton_add_state (n, end);
1688 automaton_add_state (n, start);
1700 * Adds a list of states to the given automaton 'n'.
1702 * @param n automaton to which the states should be added
1703 * @param states_head head of the DLL of states
1704 * @param states_tail tail of the DLL of states
1707 nfa_add_states (struct GNUNET_REGEX_Automaton *n,
1708 struct GNUNET_REGEX_State *states_head,
1709 struct GNUNET_REGEX_State *states_tail)
1711 struct GNUNET_REGEX_State *s;
1713 if (NULL == n || NULL == states_head)
1715 GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "Could not add states\n");
1719 if (NULL == n->states_head)
1721 n->states_head = states_head;
1722 n->states_tail = states_tail;
1726 if (NULL != states_head)
1728 n->states_tail->next = states_head;
1729 n->states_tail = states_tail;
1732 for (s = states_head; NULL != s; s = s->next)
1738 * Creates a new NFA state. Needs to be freed using automaton_destroy_state.
1740 * @param ctx context
1741 * @param accepting is it an accepting state or not
1743 * @return new NFA state
1745 static struct GNUNET_REGEX_State *
1746 nfa_state_create (struct GNUNET_REGEX_Context *ctx, int accepting)
1748 struct GNUNET_REGEX_State *s;
1750 s = GNUNET_malloc (sizeof (struct GNUNET_REGEX_State));
1751 s->id = ctx->state_id++;
1752 s->accepting = accepting;
1753 s->marked = GNUNET_NO;
1759 GNUNET_asprintf (&s->name, "s%i", s->id);
1766 * Calculates the NFA closure set for the given state.
1768 * @param nfa the NFA containing 's'
1769 * @param s starting point state
1770 * @param label transitioning label on which to base the closure on,
1771 * pass NULL for epsilon transition
1773 * @return sorted nfa closure on 'label' (epsilon closure if 'label' is NULL)
1775 static struct GNUNET_REGEX_StateSet *
1776 nfa_closure_create (struct GNUNET_REGEX_Automaton *nfa,
1777 struct GNUNET_REGEX_State *s, const char *label)
1779 struct GNUNET_REGEX_StateSet *cls;
1780 struct GNUNET_REGEX_StateSet *cls_check;
1781 struct GNUNET_REGEX_State *clsstate;
1782 struct GNUNET_REGEX_State *currentstate;
1783 struct GNUNET_REGEX_Transition *ctran;
1788 cls = GNUNET_malloc (sizeof (struct GNUNET_REGEX_StateSet));
1789 cls_check = GNUNET_malloc (sizeof (struct GNUNET_REGEX_StateSet));
1791 for (clsstate = nfa->states_head; NULL != clsstate; clsstate = clsstate->next)
1792 clsstate->contained = 0;
1794 // Add start state to closure only for epsilon closure
1796 GNUNET_array_append (cls->states, cls->len, s);
1798 GNUNET_array_append (cls_check->states, cls_check->len, s);
1799 while (cls_check->len > 0)
1801 currentstate = cls_check->states[cls_check->len - 1];
1802 GNUNET_array_grow (cls_check->states, cls_check->len, cls_check->len - 1);
1804 for (ctran = currentstate->transitions_head; NULL != ctran;
1805 ctran = ctran->next)
1807 if (NULL != ctran->to_state && 0 == nullstrcmp (label, ctran->label))
1809 clsstate = ctran->to_state;
1811 if (NULL != clsstate && 0 == clsstate->contained)
1813 GNUNET_array_append (cls->states, cls->len, clsstate);
1814 GNUNET_array_append (cls_check->states, cls_check->len, clsstate);
1815 clsstate->contained = 1;
1820 GNUNET_assert (0 == cls_check->len);
1821 GNUNET_free (cls_check);
1825 qsort (cls->states, cls->len, sizeof (struct GNUNET_REGEX_State *),
1833 * Calculates the closure set for the given set of states.
1835 * @param nfa the NFA containing 's'
1836 * @param states list of states on which to base the closure on
1837 * @param label transitioning label for which to base the closure on,
1838 * pass NULL for epsilon transition
1840 * @return sorted nfa closure on 'label' (epsilon closure if 'label' is NULL)
1842 static struct GNUNET_REGEX_StateSet *
1843 nfa_closure_set_create (struct GNUNET_REGEX_Automaton *nfa,
1844 struct GNUNET_REGEX_StateSet *states, const char *label)
1846 struct GNUNET_REGEX_State *s;
1847 struct GNUNET_REGEX_StateSet *sset;
1848 struct GNUNET_REGEX_StateSet *cls;
1852 unsigned int contains;
1857 cls = GNUNET_malloc (sizeof (struct GNUNET_REGEX_StateSet));
1859 for (i = 0; i < states->len; i++)
1861 s = states->states[i];
1862 sset = nfa_closure_create (nfa, s, label);
1864 for (j = 0; j < sset->len; j++)
1867 for (k = 0; k < cls->len; k++)
1869 if (sset->states[j]->id == cls->states[k]->id)
1876 GNUNET_array_append (cls->states, cls->len, sset->states[j]);
1878 state_set_clear (sset);
1882 qsort (cls->states, cls->len, sizeof (struct GNUNET_REGEX_State *),
1890 * Pops two NFA fragments (a, b) from the stack and concatenates them (ab)
1892 * @param ctx context
1895 nfa_add_concatenation (struct GNUNET_REGEX_Context *ctx)
1897 struct GNUNET_REGEX_Automaton *a;
1898 struct GNUNET_REGEX_Automaton *b;
1899 struct GNUNET_REGEX_Automaton *new_nfa;
1901 b = ctx->stack_tail;
1902 GNUNET_assert (NULL != b);
1903 GNUNET_CONTAINER_DLL_remove (ctx->stack_head, ctx->stack_tail, b);
1904 a = ctx->stack_tail;
1905 GNUNET_assert (NULL != a);
1906 GNUNET_CONTAINER_DLL_remove (ctx->stack_head, ctx->stack_tail, a);
1908 state_add_transition (ctx, a->end, NULL, b->start);
1909 a->end->accepting = 0;
1910 b->end->accepting = 1;
1912 new_nfa = nfa_fragment_create (NULL, NULL);
1913 nfa_add_states (new_nfa, a->states_head, a->states_tail);
1914 nfa_add_states (new_nfa, b->states_head, b->states_tail);
1915 new_nfa->start = a->start;
1916 new_nfa->end = b->end;
1917 new_nfa->state_count += a->state_count + b->state_count;
1918 automaton_fragment_clear (a);
1919 automaton_fragment_clear (b);
1921 GNUNET_CONTAINER_DLL_insert_tail (ctx->stack_head, ctx->stack_tail, new_nfa);
1926 * Pops a NFA fragment from the stack (a) and adds a new fragment (a*)
1928 * @param ctx context
1931 nfa_add_star_op (struct GNUNET_REGEX_Context *ctx)
1933 struct GNUNET_REGEX_Automaton *a;
1934 struct GNUNET_REGEX_Automaton *new_nfa;
1935 struct GNUNET_REGEX_State *start;
1936 struct GNUNET_REGEX_State *end;
1938 a = ctx->stack_tail;
1942 GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
1943 "nfa_add_star_op failed, because there was no element on the stack");
1947 GNUNET_CONTAINER_DLL_remove (ctx->stack_head, ctx->stack_tail, a);
1949 start = nfa_state_create (ctx, 0);
1950 end = nfa_state_create (ctx, 1);
1952 state_add_transition (ctx, start, NULL, a->start);
1953 state_add_transition (ctx, start, NULL, end);
1954 state_add_transition (ctx, a->end, NULL, a->start);
1955 state_add_transition (ctx, a->end, NULL, end);
1957 a->end->accepting = 0;
1960 new_nfa = nfa_fragment_create (start, end);
1961 nfa_add_states (new_nfa, a->states_head, a->states_tail);
1962 automaton_fragment_clear (a);
1964 GNUNET_CONTAINER_DLL_insert_tail (ctx->stack_head, ctx->stack_tail, new_nfa);
1969 * Pops an NFA fragment (a) from the stack and adds a new fragment (a+)
1971 * @param ctx context
1974 nfa_add_plus_op (struct GNUNET_REGEX_Context *ctx)
1976 struct GNUNET_REGEX_Automaton *a;
1978 a = ctx->stack_tail;
1979 GNUNET_CONTAINER_DLL_remove (ctx->stack_head, ctx->stack_tail, a);
1981 state_add_transition (ctx, a->end, NULL, a->start);
1983 GNUNET_CONTAINER_DLL_insert_tail (ctx->stack_head, ctx->stack_tail, a);
1988 * Pops an NFA fragment (a) from the stack and adds a new fragment (a?)
1990 * @param ctx context
1993 nfa_add_question_op (struct GNUNET_REGEX_Context *ctx)
1995 struct GNUNET_REGEX_Automaton *a;
1996 struct GNUNET_REGEX_Automaton *new_nfa;
1997 struct GNUNET_REGEX_State *start;
1998 struct GNUNET_REGEX_State *end;
2000 a = ctx->stack_tail;
2004 GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
2005 "nfa_add_question_op failed, because there was no element on the stack");
2009 GNUNET_CONTAINER_DLL_remove (ctx->stack_head, ctx->stack_tail, a);
2011 start = nfa_state_create (ctx, 0);
2012 end = nfa_state_create (ctx, 1);
2014 state_add_transition (ctx, start, NULL, a->start);
2015 state_add_transition (ctx, start, NULL, end);
2016 state_add_transition (ctx, a->end, NULL, end);
2018 a->end->accepting = 0;
2020 new_nfa = nfa_fragment_create (start, end);
2021 nfa_add_states (new_nfa, a->states_head, a->states_tail);
2022 automaton_fragment_clear (a);
2024 GNUNET_CONTAINER_DLL_insert_tail (ctx->stack_head, ctx->stack_tail, new_nfa);
2029 * Pops two NFA fragments (a, b) from the stack and adds a new NFA fragment that
2030 * alternates between a and b (a|b)
2032 * @param ctx context
2035 nfa_add_alternation (struct GNUNET_REGEX_Context *ctx)
2037 struct GNUNET_REGEX_Automaton *a;
2038 struct GNUNET_REGEX_Automaton *b;
2039 struct GNUNET_REGEX_Automaton *new_nfa;
2040 struct GNUNET_REGEX_State *start;
2041 struct GNUNET_REGEX_State *end;
2043 b = ctx->stack_tail;
2044 GNUNET_assert (NULL != b);
2045 GNUNET_CONTAINER_DLL_remove (ctx->stack_head, ctx->stack_tail, b);
2046 a = ctx->stack_tail;
2047 GNUNET_assert (NULL != a);
2048 GNUNET_CONTAINER_DLL_remove (ctx->stack_head, ctx->stack_tail, a);
2050 start = nfa_state_create (ctx, 0);
2051 end = nfa_state_create (ctx, 1);
2052 state_add_transition (ctx, start, NULL, a->start);
2053 state_add_transition (ctx, start, NULL, b->start);
2055 state_add_transition (ctx, a->end, NULL, end);
2056 state_add_transition (ctx, b->end, NULL, end);
2058 a->end->accepting = 0;
2059 b->end->accepting = 0;
2062 new_nfa = nfa_fragment_create (start, end);
2063 nfa_add_states (new_nfa, a->states_head, a->states_tail);
2064 nfa_add_states (new_nfa, b->states_head, b->states_tail);
2065 automaton_fragment_clear (a);
2066 automaton_fragment_clear (b);
2068 GNUNET_CONTAINER_DLL_insert_tail (ctx->stack_head, ctx->stack_tail, new_nfa);
2073 * Adds a new nfa fragment to the stack
2075 * @param ctx context
2076 * @param label label for nfa transition
2079 nfa_add_label (struct GNUNET_REGEX_Context *ctx, const char *label)
2081 struct GNUNET_REGEX_Automaton *n;
2082 struct GNUNET_REGEX_State *start;
2083 struct GNUNET_REGEX_State *end;
2085 GNUNET_assert (NULL != ctx);
2087 start = nfa_state_create (ctx, 0);
2088 end = nfa_state_create (ctx, 1);
2089 state_add_transition (ctx, start, label, end);
2090 n = nfa_fragment_create (start, end);
2091 GNUNET_assert (NULL != n);
2092 GNUNET_CONTAINER_DLL_insert_tail (ctx->stack_head, ctx->stack_tail, n);
2097 * Initialize a new context
2099 * @param ctx context
2102 GNUNET_REGEX_context_init (struct GNUNET_REGEX_Context *ctx)
2106 GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "Context was NULL!");
2110 ctx->transition_id = 0;
2111 ctx->stack_head = NULL;
2112 ctx->stack_tail = NULL;
2117 * Construct an NFA by parsing the regex string of length 'len'.
2119 * @param regex regular expression string
2120 * @param len length of the string
2122 * @return NFA, needs to be freed using GNUNET_REGEX_destroy_automaton
2124 struct GNUNET_REGEX_Automaton *
2125 GNUNET_REGEX_construct_nfa (const char *regex, const size_t len)
2127 struct GNUNET_REGEX_Context ctx;
2128 struct GNUNET_REGEX_Automaton *nfa;
2133 unsigned int altcount;
2134 unsigned int atomcount;
2135 unsigned int pcount;
2142 GNUNET_REGEX_context_init (&ctx);
2152 for (count = 0; count < len && *regexp; count++, regexp++)
2160 nfa_add_concatenation (&ctx);
2162 GNUNET_array_grow (p, pcount, pcount + 1);
2163 p[pcount - 1].altcount = altcount;
2164 p[pcount - 1].atomcount = atomcount;
2171 error_msg = "Cannot append '|' to nothing";
2174 while (--atomcount > 0)
2175 nfa_add_concatenation (&ctx);
2181 error_msg = "Missing opening '('";
2186 // Ignore this: "()"
2188 altcount = p[pcount].altcount;
2189 atomcount = p[pcount].atomcount;
2192 while (--atomcount > 0)
2193 nfa_add_concatenation (&ctx);
2194 for (; altcount > 0; altcount--)
2195 nfa_add_alternation (&ctx);
2197 altcount = p[pcount].altcount;
2198 atomcount = p[pcount].atomcount;
2204 error_msg = "Cannot append '*' to nothing";
2207 nfa_add_star_op (&ctx);
2212 error_msg = "Cannot append '+' to nothing";
2215 nfa_add_plus_op (&ctx);
2220 error_msg = "Cannot append '?' to nothing";
2223 nfa_add_question_op (&ctx);
2229 nfa_add_concatenation (&ctx);
2231 curlabel[0] = *regexp;
2232 nfa_add_label (&ctx, curlabel);
2239 error_msg = "Unbalanced parenthesis";
2242 while (--atomcount > 0)
2243 nfa_add_concatenation (&ctx);
2244 for (; altcount > 0; altcount--)
2245 nfa_add_alternation (&ctx);
2247 GNUNET_free_non_null (p);
2249 nfa = ctx.stack_tail;
2250 GNUNET_CONTAINER_DLL_remove (ctx.stack_head, ctx.stack_tail, nfa);
2252 if (NULL != ctx.stack_head)
2254 error_msg = "Creating the NFA failed. NFA stack was not empty!";
2258 nfa->regex = GNUNET_strdup (regex);
2260 /* create depth-first numbering of the states for pretty printing */
2261 GNUNET_REGEX_automaton_traverse (nfa, NULL, NULL, NULL, &number_states, NULL);
2266 GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "Could not parse regex: %s\n", regex);
2267 if (NULL != error_msg)
2268 GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "%s\n", error_msg);
2270 GNUNET_free_non_null (p);
2272 while (NULL != (nfa = ctx.stack_head))
2274 GNUNET_CONTAINER_DLL_remove (ctx.stack_head, ctx.stack_tail, nfa);
2275 GNUNET_REGEX_automaton_destroy (nfa);
2283 * Create DFA states based on given 'nfa' and starting with 'dfa_state'.
2285 * @param ctx context.
2286 * @param nfa NFA automaton.
2287 * @param dfa DFA automaton.
2288 * @param dfa_state current dfa state, pass epsilon closure of first nfa state
2292 construct_dfa_states (struct GNUNET_REGEX_Context *ctx,
2293 struct GNUNET_REGEX_Automaton *nfa,
2294 struct GNUNET_REGEX_Automaton *dfa,
2295 struct GNUNET_REGEX_State *dfa_state)
2297 struct GNUNET_REGEX_Transition *ctran;
2298 struct GNUNET_REGEX_State *state_iter;
2299 struct GNUNET_REGEX_State *new_dfa_state;
2300 struct GNUNET_REGEX_State *state_contains;
2301 struct GNUNET_REGEX_StateSet *tmp;
2302 struct GNUNET_REGEX_StateSet *nfa_set;
2304 for (ctran = dfa_state->transitions_head; NULL != ctran; ctran = ctran->next)
2306 if (NULL == ctran->label || NULL != ctran->to_state)
2309 tmp = nfa_closure_set_create (nfa, dfa_state->nfa_set, ctran->label);
2310 nfa_set = nfa_closure_set_create (nfa, tmp, 0);
2311 state_set_clear (tmp);
2312 new_dfa_state = dfa_state_create (ctx, nfa_set);
2313 state_contains = NULL;
2314 for (state_iter = dfa->states_head; NULL != state_iter;
2315 state_iter = state_iter->next)
2317 if (0 == state_set_compare (state_iter->nfa_set, new_dfa_state->nfa_set))
2318 state_contains = state_iter;
2321 if (NULL == state_contains)
2323 automaton_add_state (dfa, new_dfa_state);
2324 ctran->to_state = new_dfa_state;
2325 construct_dfa_states (ctx, nfa, dfa, new_dfa_state);
2329 ctran->to_state = state_contains;
2330 automaton_destroy_state (new_dfa_state);
2337 * Construct DFA for the given 'regex' of length 'len'
2339 * @param regex regular expression string
2340 * @param len length of the regular expression
2342 * @return DFA, needs to be freed using GNUNET_REGEX_destroy_automaton
2344 struct GNUNET_REGEX_Automaton *
2345 GNUNET_REGEX_construct_dfa (const char *regex, const size_t len)
2347 struct GNUNET_REGEX_Context ctx;
2348 struct GNUNET_REGEX_Automaton *dfa;
2349 struct GNUNET_REGEX_Automaton *nfa;
2350 struct GNUNET_REGEX_StateSet *nfa_start_eps_cls;
2352 GNUNET_REGEX_context_init (&ctx);
2355 nfa = GNUNET_REGEX_construct_nfa (regex, len);
2359 GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
2360 "Could not create DFA, because NFA creation failed\n");
2364 dfa = GNUNET_malloc (sizeof (struct GNUNET_REGEX_Automaton));
2366 dfa->state_count = 0;
2367 dfa->states_head = NULL;
2368 dfa->states_tail = NULL;
2369 dfa->regex = GNUNET_strdup (regex);
2371 // Create DFA start state from epsilon closure
2372 nfa_start_eps_cls = nfa_closure_create (nfa, nfa->start, 0);
2373 dfa->start = dfa_state_create (&ctx, nfa_start_eps_cls);
2374 automaton_add_state (dfa, dfa->start);
2376 construct_dfa_states (&ctx, nfa, dfa, dfa->start);
2378 GNUNET_REGEX_automaton_destroy (nfa);
2381 dfa_minimize (&ctx, dfa);
2383 // Create proofs for all states
2384 automaton_create_proofs (dfa);
2386 // Add strides to DFA
2387 // GNUNET_REGEX_add_multi_strides_to_dfa (&ctx, dfa, 2);
2394 * Free the memory allocated by constructing the GNUNET_REGEX_Automaton data
2397 * @param a automaton to be destroyed
2400 GNUNET_REGEX_automaton_destroy (struct GNUNET_REGEX_Automaton *a)
2402 struct GNUNET_REGEX_State *s;
2403 struct GNUNET_REGEX_State *next_state;
2408 GNUNET_free_non_null (a->regex);
2409 GNUNET_free_non_null (a->canonical_regex);
2411 for (s = a->states_head; NULL != s;)
2413 next_state = s->next;
2414 automaton_destroy_state (s);
2423 * Evaluates the given string using the given DFA automaton
2425 * @param a automaton, type must be DFA
2426 * @param string string that should be evaluated
2428 * @return 0 if string matches, non 0 otherwise
2431 evaluate_dfa (struct GNUNET_REGEX_Automaton *a, const char *string)
2435 struct GNUNET_REGEX_State *s;
2439 GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
2440 "Tried to evaluate DFA, but NFA automaton given");
2446 // If the string is empty but the starting state is accepting, we accept.
2447 if ((NULL == string || 0 == strlen (string)) && s->accepting)
2451 for (strp = string; NULL != strp && *strp; strp++)
2454 s = dfa_move (s, str);
2459 if (NULL != s && s->accepting)
2467 * Evaluates the given string using the given NFA automaton
2469 * @param a automaton, type must be NFA
2470 * @param string string that should be evaluated
2472 * @return 0 if string matches, non 0 otherwise
2475 evaluate_nfa (struct GNUNET_REGEX_Automaton *a, const char *string)
2479 struct GNUNET_REGEX_State *s;
2480 struct GNUNET_REGEX_StateSet *sset;
2481 struct GNUNET_REGEX_StateSet *new_sset;
2487 GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
2488 "Tried to evaluate NFA, but DFA automaton given");
2492 // If the string is empty but the starting state is accepting, we accept.
2493 if ((NULL == string || 0 == strlen (string)) && a->start->accepting)
2497 sset = nfa_closure_create (a, a->start, 0);
2500 for (strp = string; NULL != strp && *strp; strp++)
2503 new_sset = nfa_closure_set_create (a, sset, str);
2504 state_set_clear (sset);
2505 sset = nfa_closure_set_create (a, new_sset, 0);
2506 state_set_clear (new_sset);
2509 for (i = 0; i < sset->len; i++)
2511 s = sset->states[i];
2512 if (NULL != s && s->accepting)
2519 state_set_clear (sset);
2525 * Evaluates the given 'string' against the given compiled regex
2527 * @param a automaton
2528 * @param string string to check
2530 * @return 0 if string matches, non 0 otherwise
2533 GNUNET_REGEX_eval (struct GNUNET_REGEX_Automaton *a, const char *string)
2540 result = evaluate_dfa (a, string);
2543 result = evaluate_nfa (a, string);
2546 GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
2547 "Evaluating regex failed, automaton has no type!\n");
2548 result = GNUNET_SYSERR;
2557 * Get the canonical regex of the given automaton.
2558 * When constructing the automaton a proof is computed for each state,
2559 * consisting of the regular expression leading to this state. A complete
2560 * regex for the automaton can be computed by combining these proofs.
2561 * As of now this function is only useful for testing.
2563 * @param a automaton for which the canonical regex should be returned.
2568 GNUNET_REGEX_get_canonical_regex (struct GNUNET_REGEX_Automaton *a)
2573 return a->canonical_regex;
2578 * Get the number of transitions that are contained in the given automaton.
2580 * @param a automaton for which the number of transitions should be returned.
2582 * @return number of transitions in the given automaton.
2585 GNUNET_REGEX_get_transition_count (struct GNUNET_REGEX_Automaton *a)
2587 unsigned int t_count;
2588 struct GNUNET_REGEX_State *s;
2593 for (t_count = 0, s = a->states_head; NULL != s; s = s->next)
2595 t_count += s->transition_count;
2603 * Get the first key for the given 'input_string'. This hashes the first x bits
2604 * of the 'input_string'.
2606 * @param input_string string.
2607 * @param string_len length of the 'input_string'.
2608 * @param key pointer to where to write the hash code.
2610 * @return number of bits of 'input_string' that have been consumed
2611 * to construct the key
2614 GNUNET_REGEX_get_first_key (const char *input_string, size_t string_len,
2615 struct GNUNET_HashCode * key)
2619 size = string_len < INITIAL_BITS ? string_len : INITIAL_BITS;
2621 if (NULL == input_string)
2623 GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "Given input string was NULL!\n");
2627 GNUNET_CRYPTO_hash (input_string, size, key);
2634 * Check if the given 'proof' matches the given 'key'.
2636 * @param proof partial regex of a state.
2637 * @param key hash of a state.
2639 * @return GNUNET_OK if the proof is valid for the given key.
2642 GNUNET_REGEX_check_proof (const char *proof, const struct GNUNET_HashCode *key)
2644 struct GNUNET_HashCode key_check;
2646 if (NULL == proof || NULL == key)
2648 GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "Proof check failed, was NULL.\n");
2652 GNUNET_CRYPTO_hash (proof, strlen (proof), &key_check);
2654 GNUNET_CRYPTO_hash_cmp (key, &key_check)) ? GNUNET_OK : GNUNET_NO;
2659 * Recursive helper function for iterate_initial_edges. Will call iterator
2660 * function for each initial state.
2662 * @param min_len minimum length of the path in the graph.
2663 * @param max_len maximum length of the path in the graph.
2664 * @param cur_len current length of the path already traversed.
2665 * @param consumed_string string consumed by traversing the graph till this state.
2666 * @param state current state of the automaton.
2667 * @param iterator iterator function called for each edge.
2668 * @param iterator_cls closure for the iterator function.
2671 iterate_initial_edge (const unsigned int min_len, const unsigned int max_len,
2672 unsigned int cur_len, char *consumed_string,
2673 struct GNUNET_REGEX_State *state,
2674 GNUNET_REGEX_KeyIterator iterator, void *iterator_cls)
2678 struct GNUNET_REGEX_Transition *t;
2679 unsigned int num_edges = state->transition_count;
2680 struct GNUNET_REGEX_Edge edges[num_edges];
2681 struct GNUNET_HashCode hash;
2683 if (cur_len > min_len && NULL != consumed_string && cur_len <= max_len)
2685 for (i = 0, t = state->transitions_head; NULL != t; t = t->next, i++)
2687 edges[i].label = t->label;
2688 edges[i].destination = t->to_state->hash;
2691 GNUNET_CRYPTO_hash (consumed_string, strlen (consumed_string), &hash);
2692 iterator (iterator_cls, &hash, consumed_string, state->accepting, num_edges,
2696 if (cur_len < max_len)
2699 for (t = state->transitions_head; NULL != t; t = t->next)
2701 if (NULL != consumed_string)
2702 GNUNET_asprintf (&temp, "%s%s", consumed_string, t->label);
2704 GNUNET_asprintf (&temp, "%s", t->label);
2706 iterate_initial_edge (min_len, max_len, cur_len, temp, t->to_state,
2707 iterator, iterator_cls);
2715 * Iterate over all initial edges that aren't actually part of the automaton.
2716 * This is needed to find the initial states returned by
2717 * GNUNET_REGEX_get_first_key. Iteration will start at the first state that has
2718 * more than one outgoing edge, i.e. the state that branches the graph.
2719 * For example consider the following graph:
2720 * a -> b -> c -> d -> ...
2723 * This function will not iterate over the edges leading to "c", because these
2724 * will be covered by the iterate_edges function.
2726 * @param a the automaton for which the initial states should be computed.
2727 * @param initial_len length of the initial state string.
2728 * @param iterator iterator function called for each edge.
2729 * @param iterator_cls closure for the iterator function.
2732 iterate_initial_edges (struct GNUNET_REGEX_Automaton *a,
2733 const unsigned int initial_len,
2734 GNUNET_REGEX_KeyIterator iterator, void *iterator_cls)
2736 char *consumed_string;
2738 struct GNUNET_REGEX_State *s;
2739 unsigned int cur_len;
2741 if (1 > initial_len)
2744 consumed_string = NULL;
2748 if (1 == s->transition_count)
2752 if (NULL != consumed_string)
2754 temp = consumed_string;
2755 GNUNET_asprintf (&consumed_string, "%s%s", consumed_string,
2756 s->transitions_head->label);
2760 GNUNET_asprintf (&consumed_string, "%s", s->transitions_head->label);
2762 s = s->transitions_head->to_state;
2763 cur_len += strlen (s->transitions_head->label);
2765 while (cur_len < initial_len && 1 == s->transition_count);
2768 iterate_initial_edge (cur_len, initial_len, cur_len, consumed_string, s,
2769 iterator, iterator_cls);
2771 GNUNET_free_non_null (consumed_string);
2776 * Iterate over all edges helper function starting from state 's', calling
2777 * iterator function for each edge.
2780 * @param iterator iterator function called for each edge.
2781 * @param iterator_cls closure.
2784 iterate_edge (struct GNUNET_REGEX_State *s, GNUNET_REGEX_KeyIterator iterator,
2787 struct GNUNET_REGEX_Transition *t;
2788 struct GNUNET_REGEX_Edge edges[s->transition_count];
2789 unsigned int num_edges;
2791 if (GNUNET_YES != s->marked)
2793 s->marked = GNUNET_YES;
2795 num_edges = state_get_edges (s, edges);
2797 if ((NULL != s->proof && 0 < strlen (s->proof)) || s->accepting)
2798 iterator (iterator_cls, &s->hash, s->proof, s->accepting, num_edges,
2801 for (t = s->transitions_head; NULL != t; t = t->next)
2802 iterate_edge (t->to_state, iterator, iterator_cls);
2808 * Iterate over all edges starting from start state of automaton 'a'. Calling
2809 * iterator for each edge.
2811 * @param a automaton.
2812 * @param iterator iterator called for each edge.
2813 * @param iterator_cls closure.
2816 GNUNET_REGEX_iterate_all_edges (struct GNUNET_REGEX_Automaton *a,
2817 GNUNET_REGEX_KeyIterator iterator,
2820 struct GNUNET_REGEX_State *s;
2822 for (s = a->states_head; NULL != s; s = s->next)
2823 s->marked = GNUNET_NO;
2825 iterate_initial_edges (a, INITIAL_BITS, iterator, iterator_cls);
2826 iterate_edge (a->start, iterator, iterator_cls);