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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"
31 #define INITIAL_BITS 10
34 * Context that contains an id counter for states and transitions as well as a
35 * DLL of automatons used as a stack for NFA construction.
37 struct GNUNET_REGEX_Context
42 unsigned int state_id;
45 * Unique transition id.
47 unsigned int transition_id;
50 * Unique SCC (Strongly Connected Component) id.
55 * DLL of GNUNET_REGEX_Automaton's used as a stack.
57 struct GNUNET_REGEX_Automaton *stack_head;
60 * DLL of GNUNET_REGEX_Automaton's used as a stack.
62 struct GNUNET_REGEX_Automaton *stack_tail;
66 * Type of an automaton.
68 enum GNUNET_REGEX_AutomatonType
75 * Automaton representation.
77 struct GNUNET_REGEX_Automaton
80 * This is a linked list.
82 struct GNUNET_REGEX_Automaton *prev;
85 * This is a linked list.
87 struct GNUNET_REGEX_Automaton *next;
90 * First state of the automaton. This is mainly used for constructing an NFA,
91 * where each NFA itself consists of one or more NFAs linked together.
93 struct GNUNET_REGEX_State *start;
96 * End state of the automaton.
98 struct GNUNET_REGEX_State *end;
101 * Number of states in the automaton.
103 unsigned int state_count;
108 struct GNUNET_REGEX_State *states_head;
113 struct GNUNET_REGEX_State *states_tail;
116 * Type of the automaton.
118 enum GNUNET_REGEX_AutomatonType type;
126 * Computed regex (result of RX->NFA->DFA->RX)
128 char *computed_regex;
132 * A state. Can be used in DFA and NFA automatons.
134 struct GNUNET_REGEX_State
137 * This is a linked list.
139 struct GNUNET_REGEX_State *prev;
142 * This is a linked list.
144 struct GNUNET_REGEX_State *next;
152 * If this is an accepting state or not.
157 * Marking of the state. This is used for marking all visited states when
158 * traversing all states of an automaton and for cases where the state id
159 * cannot be used (dfa minimization).
164 * Marking the state as contained. This is used for checking, if the state is
165 * contained in a set in constant time
170 * Marking the state as part of an SCC (Strongly Connected Component). All
171 * states with the same scc_id are part of the same SCC. scc_id is 0, if state
172 * is not a part of any SCC.
177 * Used for SCC detection.
182 * Used for SCC detection.
187 * Human readable name of the automaton. Used for debugging and graph
195 struct GNUNET_HashCode hash;
198 * State ID for proof creation.
200 unsigned int proof_id;
203 * Proof for this state.
208 * Number of transitions from this state to other states.
210 unsigned int transition_count;
213 * DLL of transitions.
215 struct Transition *transitions_head;
218 * DLL of transitions.
220 struct Transition *transitions_tail;
223 * Set of states on which this state is based on. Used when creating a DFA out
224 * of several NFA states.
226 struct GNUNET_REGEX_StateSet *nfa_set;
230 * Transition between two states. Each state can have 0-n transitions. If label
231 * is 0, this is considered to be an epsilon transition.
236 * This is a linked list.
238 struct Transition *prev;
241 * This is a linked list.
243 struct Transition *next;
246 * Unique id of this transition.
251 * Label for this transition. This is basically the edge label for the graph.
256 * State to which this transition leads.
258 struct GNUNET_REGEX_State *to_state;
261 * State from which this transition origins.
263 struct GNUNET_REGEX_State *from_state;
266 * Mark this transition. For example when reversing the automaton.
274 struct GNUNET_REGEX_StateSet
279 struct GNUNET_REGEX_State **states;
282 * Length of the 'states' array.
288 * Debug helper functions
291 debug_print_transitions (struct GNUNET_REGEX_State *);
294 debug_print_state (struct GNUNET_REGEX_State *s)
298 if (NULL == s->proof)
303 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
304 "State %i: %s marked: %i accepting: %i scc_id: %i transitions: %i proof: %s\n",
305 s->id, s->name, s->marked, s->accepting, s->scc_id,
306 s->transition_count, proof);
308 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "Transitions:\n");
309 debug_print_transitions (s);
313 debug_print_states (struct GNUNET_REGEX_Automaton *a)
315 struct GNUNET_REGEX_State *s;
317 for (s = a->states_head; NULL != s; s = s->next)
318 debug_print_state (s);
322 debug_print_transition (struct Transition *t)
336 if (NULL == t->to_state)
339 to_state = t->to_state->name;
341 if (NULL == t->from_state)
344 from_state = t->from_state->name;
346 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "Transition %i: From %s on %c to %s\n",
347 t->id, from_state, label, to_state);
351 debug_print_transitions (struct GNUNET_REGEX_State *s)
353 struct Transition *t;
355 for (t = s->transitions_head; NULL != t; t = t->next)
356 debug_print_transition (t);
360 * Recursive function doing DFS with 'v' as a start, detecting all SCCs inside
361 * the subgraph reachable from 'v'. Used with scc_tarjan function to detect all
362 * SCCs inside an automaton.
365 * @param v start vertex
366 * @param index current index
367 * @param stack stack for saving all SCCs
368 * @param stack_size current size of the stack
371 scc_tarjan_strongconnect (struct GNUNET_REGEX_Context *ctx,
372 struct GNUNET_REGEX_State *v, int *index,
373 struct GNUNET_REGEX_State **stack,
374 unsigned int *stack_size)
376 struct GNUNET_REGEX_State *w;
377 struct Transition *t;
382 stack[(*stack_size)++] = v;
385 for (t = v->transitions_head; NULL != t; t = t->next)
388 if (NULL != w && w->index < 0)
390 scc_tarjan_strongconnect (ctx, w, index, stack, stack_size);
391 v->lowlink = (v->lowlink > w->lowlink) ? w->lowlink : v->lowlink;
393 else if (0 != w->contained)
394 v->lowlink = (v->lowlink > w->index) ? w->index : v->lowlink;
397 if (v->lowlink == v->index)
399 w = stack[--(*stack_size)];
407 w->scc_id = ctx->scc_id;
408 w = stack[--(*stack_size)];
411 w->scc_id = ctx->scc_id;
417 * Detect all SCCs (Strongly Connected Components) inside the given automaton.
418 * SCCs will be marked using the scc_id on each state.
424 scc_tarjan (struct GNUNET_REGEX_Context *ctx, struct GNUNET_REGEX_Automaton *a)
427 struct GNUNET_REGEX_State *v;
428 struct GNUNET_REGEX_State *stack[a->state_count];
429 unsigned int stack_size;
431 for (v = a->states_head; NULL != v; v = v->next)
441 for (v = a->states_head; NULL != v; v = v->next)
444 scc_tarjan_strongconnect (ctx, v, &index, stack, &stack_size);
449 * Adds a transition from one state to another on 'label'. Does not add
453 * @param from_state starting state for the transition
454 * @param label transition label
455 * @param to_state state to where the transition should point to
458 state_add_transition (struct GNUNET_REGEX_Context *ctx,
459 struct GNUNET_REGEX_State *from_state, const char label,
460 struct GNUNET_REGEX_State *to_state)
463 struct Transition *t;
464 struct Transition *oth;
466 if (NULL == from_state)
468 GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "Could not create Transition.\n");
472 // Do not add duplicate state transitions
474 for (t = from_state->transitions_head; NULL != t; t = t->next)
476 if (t->to_state == to_state && t->label == label &&
477 t->from_state == from_state)
487 // sort transitions by label
488 for (oth = from_state->transitions_head; NULL != oth; oth = oth->next)
490 if (oth->label > label)
494 t = GNUNET_malloc (sizeof (struct Transition));
495 t->id = ctx->transition_id++;
497 t->to_state = to_state;
498 t->from_state = from_state;
500 // Add outgoing transition to 'from_state'
501 from_state->transition_count++;
502 GNUNET_CONTAINER_DLL_insert_before (from_state->transitions_head,
503 from_state->transitions_tail, oth, t);
507 * Compare two states. Used for sorting.
509 * @param a first state
510 * @param b second state
512 * @return an integer less than, equal to, or greater than zero
513 * if the first argument is considered to be respectively
514 * less than, equal to, or greater than the second.
517 state_compare (const void *a, const void *b)
519 struct GNUNET_REGEX_State **s1;
520 struct GNUNET_REGEX_State **s2;
522 s1 = (struct GNUNET_REGEX_State **) a;
523 s2 = (struct GNUNET_REGEX_State **) b;
525 return (*s1)->id - (*s2)->id;
529 * Get all edges leaving state 's'.
532 * @param edges all edges leaving 's'.
534 * @return number of edges.
537 state_get_edges (struct GNUNET_REGEX_State *s, struct GNUNET_REGEX_Edge *edges)
539 struct Transition *t;
547 for (t = s->transitions_head; NULL != t; t = t->next)
549 if (NULL != t->to_state)
551 edges[count].label = &t->label;
552 edges[count].destination = t->to_state->hash;
560 * Compare to state sets by comparing the id's of the states that are contained
561 * in each set. Both sets are expected to be sorted by id!
563 * @param sset1 first state set
564 * @param sset2 second state set
566 * @return an integer less than, equal to, or greater than zero
567 * if the first argument is considered to be respectively
568 * less than, equal to, or greater than the second.
571 state_set_compare (struct GNUNET_REGEX_StateSet *sset1,
572 struct GNUNET_REGEX_StateSet *sset2)
577 if (NULL == sset1 || NULL == sset2)
580 result = sset1->len - sset2->len;
582 for (i = 0; i < sset1->len; i++)
587 result = state_compare (&sset1->states[i], &sset2->states[i]);
593 * Clears the given StateSet 'set'
595 * @param set set to be cleared
598 state_set_clear (struct GNUNET_REGEX_StateSet *set)
602 GNUNET_free_non_null (set->states);
608 * Clears an automaton fragment. Does not destroy the states inside the
611 * @param a automaton to be cleared
614 automaton_fragment_clear (struct GNUNET_REGEX_Automaton *a)
621 a->states_head = NULL;
622 a->states_tail = NULL;
628 * Frees the memory used by State 's'
630 * @param s state that should be destroyed
633 automaton_destroy_state (struct GNUNET_REGEX_State *s)
635 struct Transition *t;
636 struct Transition *next_t;
641 GNUNET_free_non_null (s->name);
642 GNUNET_free_non_null (s->proof);
644 for (t = s->transitions_head; NULL != t; t = next_t)
647 GNUNET_CONTAINER_DLL_remove (s->transitions_head, s->transitions_tail, t);
651 state_set_clear (s->nfa_set);
657 * Remove a state from the given automaton 'a'. Always use this function when
658 * altering the states of an automaton. Will also remove all transitions leading
659 * to this state, before destroying it.
662 * @param s state to remove
665 automaton_remove_state (struct GNUNET_REGEX_Automaton *a,
666 struct GNUNET_REGEX_State *s)
668 struct GNUNET_REGEX_State *ss;
669 struct GNUNET_REGEX_State *s_check;
670 struct Transition *t_check;
672 if (NULL == a || NULL == s)
677 GNUNET_CONTAINER_DLL_remove (a->states_head, a->states_tail, s);
680 // remove all transitions leading to this state
681 for (s_check = a->states_head; NULL != s_check; s_check = s_check->next)
683 for (t_check = s_check->transitions_head; NULL != t_check;
684 t_check = t_check->next)
686 if (t_check->to_state == ss)
688 GNUNET_CONTAINER_DLL_remove (s_check->transitions_head,
689 s_check->transitions_tail, t_check);
690 s_check->transition_count--;
695 automaton_destroy_state (ss);
699 * Merge two states into one. Will merge 's1' and 's2' into 's1' and destroy
704 * @param s1 first state
705 * @param s2 second state, will be destroyed
708 automaton_merge_states (struct GNUNET_REGEX_Context *ctx,
709 struct GNUNET_REGEX_Automaton *a,
710 struct GNUNET_REGEX_State *s1,
711 struct GNUNET_REGEX_State *s2)
713 struct GNUNET_REGEX_State *s_check;
714 struct Transition *t_check;
717 GNUNET_assert (NULL != ctx && NULL != a && NULL != s1 && NULL != s2);
722 // 1. Make all transitions pointing to s2 point to s1
723 for (s_check = a->states_head; NULL != s_check; s_check = s_check->next)
725 for (t_check = s_check->transitions_head; NULL != t_check;
726 t_check = t_check->next)
728 if (s2 == t_check->to_state)
729 t_check->to_state = s1;
733 // 2. Add all transitions from s2 to sX to s1
734 for (t_check = s2->transitions_head; NULL != t_check; t_check = t_check->next)
736 if (t_check->to_state != s1)
737 state_add_transition (ctx, s1, t_check->label, t_check->to_state);
740 // 3. Rename s1 to {s1,s2}
742 GNUNET_asprintf (&s1->name, "{%s,%s}", new_name, s2->name);
743 GNUNET_free (new_name);
746 GNUNET_CONTAINER_DLL_remove (a->states_head, a->states_tail, s2);
748 automaton_destroy_state (s2);
752 * Add a state to the automaton 'a', always use this function to alter the
753 * states DLL of the automaton.
755 * @param a automaton to add the state to
756 * @param s state that should be added
759 automaton_add_state (struct GNUNET_REGEX_Automaton *a,
760 struct GNUNET_REGEX_State *s)
762 GNUNET_CONTAINER_DLL_insert (a->states_head, a->states_tail, s);
767 * Function that is called with each state, when traversing an automaton.
769 * @param cls closure.
770 * @param count current count of the state, from 0 to a->state_count -1.
773 typedef void (*GNUNET_REGEX_traverse_action) (void *cls, unsigned int count,
774 struct GNUNET_REGEX_State * s);
777 * Depth-first traversal of all states that are reachable from state 's'. Expects the states to
778 * be unmarked (s->marked == GNUNET_NO). Performs 'action' on each visited
781 * @param s start state.
782 * @param count current count of the state.
783 * @param action action to be performed on each state.
784 * @param action_cls closure for action
787 automaton_state_traverse (struct GNUNET_REGEX_State *s,
789 GNUNET_REGEX_traverse_action action,
792 struct Transition *t;
794 if (GNUNET_NO != s->marked)
796 s->marked = GNUNET_YES;
798 action (action_cls, *count, s);
800 for (t = s->transitions_head; NULL != t; t = t->next)
801 automaton_state_traverse (t->to_state, count, action, action_cls);
806 * Traverses the given automaton from it's start state, visiting all reachable
807 * states and calling 'action' on each one of them.
809 * @param a automaton.
810 * @param action action to be performed on each state.
811 * @param action_cls closure for action
814 automaton_traverse (struct GNUNET_REGEX_Automaton *a,
815 GNUNET_REGEX_traverse_action action,
819 struct GNUNET_REGEX_State *s;
821 for (s = a->states_head; NULL != s; s = s->next)
822 s->marked = GNUNET_NO;
824 automaton_state_traverse (a->start, &count, action, action_cls);
829 * Check if the given string 'str' needs parentheses around it when
830 * using it to generate a regex.
832 * Currently only tests for first and last characters being '()' respectively.
833 * FIXME: What about "(ab)|(cd)"?
837 * @return GNUNET_YES if parentheses are needed, GNUNET_NO otherwise
840 needs_parentheses (const char *str)
844 if ( (NULL == str) ||
845 ((slen = strlen(str)) < 2) ||
846 ( ('(' == str[0]) && (')' == str[slen-1]) ) )
853 * Remove parentheses surrounding string 'str'.
854 * Example: "(a)" becomes "a".
855 * You need to GNUNET_free the returned string.
857 * Currently only tests for first and last characters being '()' respectively.
858 * FIXME: What about "(ab)|(cd)"?
860 * @param str string, free'd or re-used by this function, can be NULL
862 * @return string without surrounding parentheses, string 'str' if no preceding
863 * epsilon could be found, NULL if 'str' was NULL
866 remove_parentheses (char *str)
870 if ( (NULL == str) || ('(' != str[0]) || (str[(slen = strlen(str)) - 1] != ')') )
872 memmove (str, &str[1], slen - 2);
873 str[slen - 2] = '\0';
879 * Check if the string 'str' starts with an epsilon (empty string).
880 * Example: "(|a)" is starting with an epsilon.
882 * @param str string to test
884 * @return 0 if str has no epsilon, 1 if str starts with '(|' and ends with ')'
887 has_epsilon (const char *str)
889 return (NULL != str) && ('(' == str[0]) && ('|' == str[1]) && (')' == str[strlen(str) - 1]);
894 * Remove an epsilon from the string str. Where epsilon is an empty string
895 * Example: str = "(|a|b|c)", result: "a|b|c"
896 * The returned string needs to be freed.
900 * @return string without preceding epsilon, string 'str' if no preceding epsilon
901 * could be found, NULL if 'str' was NULL
904 remove_epsilon (const char *str)
910 if ( ('(' == str[0]) && ('|' == str[1]) )
913 if (')' == str[len-1])
914 return GNUNET_strndup (&str[2], len - 3);
916 return GNUNET_strdup (str);
920 * Compare 'str1', starting from position 'k', with whole 'str2'
922 * @param str1 first string to compare, starting from position 'k'
923 * @param str2 second string for comparison
924 * @param k starting position in 'str1'
926 * @return -1 if any of the strings is NULL, 0 if equal, non 0 otherwise
929 strkcmp (const char *str1, const char *str2, size_t k)
931 if ( (NULL == str1) || (NULL == str2) || (strlen(str1) < k) )
933 return strcmp (&str1[k], str2);
938 * Compare two strings for equality. If either is NULL (or if both are
939 * NULL), they are not equal.
941 * @return 0 if the strings are the same, 1 or -1 if not
944 nullstrcmp (const char *str1, const char *str2)
946 if ( (NULL == str1) || (NULL == str2) )
948 return strcmp (str1, str2);
953 number_states (void *cls, unsigned int count, struct GNUNET_REGEX_State *s)
955 struct GNUNET_REGEX_State **states = cls;
963 * create proofs for all states in the given automaton. Implementation of the
964 * algorithm descriped in chapter 3.2.1 of "Automata Theory, Languages, and
965 * Computation 3rd Edition" by Hopcroft, Motwani and Ullman.
967 * @param a automaton.
970 automaton_create_proofs (struct GNUNET_REGEX_Automaton *a)
972 unsigned int n = a->state_count;
973 struct GNUNET_REGEX_State *states[n];
976 struct Transition *t;
985 char *complete_regex;
1002 /* create depth-first numbering of the states, initializes 'state' */
1003 automaton_traverse (a, &number_states, states);
1005 /* Compute regular expressions of length "1" between each pair of states */
1006 for (i = 0; i < n; i++)
1011 R_last[i][j] = NULL;
1013 for (t = states[i]->transitions_head; NULL != t; t = t->next)
1015 j = t->to_state->proof_id;
1016 if (NULL == R_last[i][j])
1017 GNUNET_asprintf (&R_last[i][j], "%c", t->label);
1020 temp_a = R_last[i][j];
1021 GNUNET_asprintf (&R_last[i][j], "%s|%c", R_last[i][j], t->label);
1022 GNUNET_free (temp_a);
1024 if (GNUNET_YES == needs_parentheses (R_last[i][j]))
1026 temp_a = R_last[i][j];
1027 GNUNET_asprintf (&R_last[i][j], "(%s)", R_last[i][j]);
1028 GNUNET_free (temp_a);
1031 if (NULL == R_last[i][i])
1032 GNUNET_asprintf (&R_last[i][i], "");
1035 temp_a = R_last[i][i];
1036 GNUNET_asprintf (&R_last[i][i], "(|%s)", R_last[i][i]);
1037 GNUNET_free (temp_a);
1043 for (k = 0; k < n; k++)
1045 for (i = 0; i < n; i++)
1047 for (j = 0; j < n; j++)
1049 /* GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, */
1050 /* ">>> R_last[i][j] = %s R_last[i][k] = %s " */
1051 /* "R_last[k][k] = %s R_last[k][j] = %s\n", R_last[i][j], */
1052 /* R_last[i][k], R_last[k][k], R_last[k][j]); */
1058 // cache results from strcmp, we might need these many times
1059 ij_kj_cmp = nullstrcmp (R_last[i][j], R_last[k][j]);
1060 ij_ik_cmp = nullstrcmp (R_last[i][j], R_last[i][k]);
1061 ik_kk_cmp = nullstrcmp (R_last[i][k], R_last[k][k]);
1062 ik_kj_cmp = nullstrcmp (R_last[i][k], R_last[k][j]);
1063 kk_kj_cmp = nullstrcmp (R_last[k][k], R_last[k][j]);
1065 // $R^{(k)}_{ij} = R^{(k-1)}_{ij} | R^{(k-1)}_{ik} ( R^{(k-1)}_{kk})^* R^{(k-1)}_{kj}
1066 // With: R_cur[i][j] = R_cur_l | R_cur_r
1067 // Rij(k) = Rij(k-1), because right side (R_cur_r) is empty set (NULL)
1068 if ((NULL == R_last[i][k] || NULL == R_last[k][j] ||
1069 NULL == R_last[k][k]) && NULL != R_last[i][j])
1071 R_cur[i][j] = GNUNET_strdup (R_last[i][j]);
1073 // Everything is NULL, so Rij(k) = NULL
1074 else if ((NULL == R_last[i][k] || NULL == R_last[k][j] ||
1075 NULL == R_last[k][k]) && NULL == R_last[i][j])
1079 // Right side (R_cur_r) not NULL
1082 /* GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, */
1083 /* "R_temp_ij = %s R_temp_ik = %s R_temp_kk = %s R_temp_kj = %s\n", */
1084 /* R_temp_ij, R_temp_ik, R_temp_kk, R_temp_kj); */
1086 // Assign R_temp_(ik|kk|kj) to R_last[][] and remove epsilon as well
1087 // as parentheses, so we can better compare the contents
1088 R_temp_ik = remove_parentheses (remove_epsilon (R_last[i][k]));
1089 R_temp_kk = remove_parentheses (remove_epsilon (R_last[k][k]));
1090 R_temp_kj = remove_parentheses (remove_epsilon (R_last[k][j]));
1092 clean_ik_kk_cmp = nullstrcmp (R_last[i][k], R_temp_kk);
1093 clean_kk_kj_cmp = nullstrcmp (R_temp_kk, R_last[k][j]);
1095 // construct R_cur_l (and, if necessary R_cur_r)
1096 if (NULL != R_last[i][j])
1098 // Assign R_temp_ij to R_last[i][j] and remove epsilon as well
1099 // as parentheses, so we can better compare the contents
1100 R_temp_ij = remove_parentheses (remove_epsilon (R_last[i][j]));
1102 if (0 == strcmp (R_temp_ij, R_temp_ik) &&
1103 0 == strcmp (R_temp_ik, R_temp_kk) &&
1104 0 == strcmp (R_temp_kk, R_temp_kj))
1106 if (0 == strlen (R_temp_ij))
1108 R_cur_r = GNUNET_strdup ("");
1110 // a|(e|a)a*(e|a) = a*
1111 // a|(e|a)(e|a)*(e|a) = a*
1113 // (e|a)|aa*(e|a) = a*
1114 // (e|a)|(e|a)a*a = a*
1115 // (e|a)|(e|a)a*(e|a) = a*
1116 // (e|a)|(e|a)(e|a)*(e|a) = a*
1117 else if ((0 == strncmp (R_last[i][j], "(|", 2)) ||
1118 (0 == strncmp (R_last[i][k], "(|", 2) &&
1119 0 == strncmp (R_last[k][j], "(|", 2)))
1121 if (GNUNET_YES == needs_parentheses (R_temp_ij))
1122 GNUNET_asprintf (&R_cur_r, "(%s)*", R_temp_ij);
1124 GNUNET_asprintf (&R_cur_r, "%s*", R_temp_ij);
1129 // a|(e|a)(e|a)*a = a+
1130 // a|a(e|a)*(e|a) = a+
1133 if (GNUNET_YES == needs_parentheses (R_temp_ij))
1134 GNUNET_asprintf (&R_cur_r, "(%s)+", R_temp_ij);
1136 GNUNET_asprintf (&R_cur_r, "%s+", R_temp_ij);
1140 else if (0 == ij_ik_cmp && 0 == clean_kk_kj_cmp &&
1141 0 != clean_ik_kk_cmp)
1143 if (strlen (R_last[k][k]) < 1)
1144 R_cur_r = GNUNET_strdup (R_last[i][j]);
1145 else if (GNUNET_YES == needs_parentheses (R_temp_kk))
1146 GNUNET_asprintf (&R_cur_r, "%s(%s)*", R_last[i][j], R_temp_kk);
1148 GNUNET_asprintf (&R_cur_r, "%s%s*", R_last[i][j], R_last[k][k]);
1153 else if (0 == ij_kj_cmp && 0 == clean_ik_kk_cmp &&
1154 0 != clean_kk_kj_cmp)
1156 if (strlen (R_last[k][k]) < 1)
1157 R_cur_r = GNUNET_strdup (R_last[k][j]);
1158 else if (GNUNET_YES == needs_parentheses (R_temp_kk))
1159 GNUNET_asprintf (&R_cur_r, "(%s)*%s", R_temp_kk, R_last[k][j]);
1161 GNUNET_asprintf (&R_cur_r, "%s*%s", R_temp_kk, R_last[k][j]);
1165 // a|a(e|b)*(e|b) = a|ab* = a|a|ab|abb|abbb|... = ab*
1166 else if (0 == ij_ik_cmp && 0 == kk_kj_cmp &&
1167 !has_epsilon (R_last[i][j]) && has_epsilon (R_last[k][k]))
1169 if (needs_parentheses (R_temp_kk))
1170 GNUNET_asprintf (&R_cur_r, "%s(%s)*", R_last[i][j], R_temp_kk);
1172 GNUNET_asprintf (&R_cur_r, "%s%s*", R_last[i][j], R_temp_kk);
1176 // a|(e|b)(e|b)*a = a|b*a = a|a|ba|bba|bbba|... = b*a
1177 else if (0 == ij_kj_cmp && 0 == ik_kk_cmp &&
1178 !has_epsilon (R_last[i][j]) && has_epsilon (R_last[k][k]))
1180 if (needs_parentheses (R_temp_kk))
1181 GNUNET_asprintf (&R_cur_r, "(%s)*%s", R_temp_kk, R_last[i][j]);
1183 GNUNET_asprintf (&R_cur_r, "%s*%s", R_temp_kk, R_last[i][j]);
1189 /* GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "NO SIMPLIFICATION\n"); */
1190 temp_a = (NULL == R_last[i][j]) ? NULL : GNUNET_strdup (R_last[i][j]);
1191 temp_a = remove_parentheses (temp_a);
1195 GNUNET_free_non_null (R_temp_ij);
1197 // we have no left side
1203 // construct R_cur_r, if not already constructed
1204 if (NULL == R_cur_r)
1206 length = strlen (R_temp_kk) - strlen (R_last[i][k]);
1208 // a(ba)*bx = (ab)+x
1209 if (length > 0 && NULL != R_last[k][k] && 0 < strlen (R_last[k][k])
1210 && NULL != R_last[k][j] && 0 < strlen (R_last[k][j]) &&
1211 NULL != R_last[i][k] && 0 < strlen (R_last[i][k]) &&
1212 0 == strkcmp (R_temp_kk, R_last[i][k], length) &&
1213 0 == strncmp (R_temp_kk, R_last[k][j], length))
1215 temp_a = GNUNET_malloc (length + 1);
1216 temp_b = GNUNET_malloc ((strlen (R_last[k][j]) - length) + 1);
1221 for (cnt = 0; cnt < strlen (R_last[k][j]); cnt++)
1225 temp_a[length_l] = R_last[k][j][cnt];
1230 temp_b[length_r] = R_last[k][j][cnt];
1234 temp_a[length_l] = '\0';
1235 temp_b[length_r] = '\0';
1238 if (NULL != R_cur_l && 0 == strlen (R_cur_l) &&
1239 0 == strlen (temp_b))
1241 GNUNET_asprintf (&R_cur_r, "(%s%s)*", R_last[i][k], temp_a);
1242 GNUNET_free (R_cur_l);
1247 GNUNET_asprintf (&R_cur_r, "(%s%s)+%s", R_last[i][k], temp_a,
1250 GNUNET_free (temp_a);
1251 GNUNET_free (temp_b);
1253 else if (0 == strcmp (R_temp_ik, R_temp_kk) &&
1254 0 == strcmp (R_temp_kk, R_temp_kj))
1256 // (e|a)a*(e|a) = a*
1257 // (e|a)(e|a)*(e|a) = a*
1258 if (has_epsilon (R_last[i][k]) && has_epsilon (R_last[k][j]))
1260 if (needs_parentheses (R_temp_kk))
1261 GNUNET_asprintf (&R_cur_r, "(%s)*", R_temp_kk);
1263 GNUNET_asprintf (&R_cur_r, "%s*", R_temp_kk);
1266 else if (0 == clean_ik_kk_cmp && 0 == clean_kk_kj_cmp &&
1267 !has_epsilon (R_last[i][k]))
1269 if (needs_parentheses (R_temp_kk))
1270 GNUNET_asprintf (&R_cur_r, "(%s)+%s", R_temp_kk, R_temp_kk);
1272 GNUNET_asprintf (&R_cur_r, "(%s)+%s", R_temp_kk, R_temp_kk);
1276 // a(e|a)*(e|a) = a+
1281 (has_epsilon (R_last[i][k]) + has_epsilon (R_last[k][k]) +
1282 has_epsilon (R_last[k][j]));
1286 if (needs_parentheses (R_temp_kk))
1287 GNUNET_asprintf (&R_cur_r, "(%s)+", R_temp_kk);
1289 GNUNET_asprintf (&R_cur_r, "%s+", R_temp_kk);
1294 // (e|a)(e|a)*b = a*b
1295 else if (0 == strcmp (R_temp_ik, R_temp_kk))
1297 if (has_epsilon (R_last[i][k]))
1299 if (needs_parentheses (R_temp_kk))
1300 GNUNET_asprintf (&R_cur_r, "(%s)*%s", R_temp_kk,
1303 GNUNET_asprintf (&R_cur_r, "%s*%s", R_temp_kk, R_last[k][j]);
1307 if (needs_parentheses (R_temp_kk))
1308 GNUNET_asprintf (&R_cur_r, "(%s)+%s", R_temp_kk,
1311 GNUNET_asprintf (&R_cur_r, "%s+%s", R_temp_kk, R_last[k][j]);
1315 // b(e|a)*(e|a) = ba*
1316 else if (0 == strcmp (R_temp_kk, R_temp_kj))
1318 if (has_epsilon (R_last[k][j]))
1320 if (needs_parentheses (R_temp_kk))
1321 GNUNET_asprintf (&R_cur_r, "%s(%s)*", R_last[i][k],
1324 GNUNET_asprintf (&R_cur_r, "%s%s*", R_last[i][k], R_temp_kk);
1328 if (needs_parentheses (R_temp_kk))
1329 GNUNET_asprintf (&R_cur_r, "(%s)+%s", R_last[i][k],
1332 GNUNET_asprintf (&R_cur_r, "%s+%s", R_last[i][k], R_temp_kk);
1337 if (strlen (R_temp_kk) > 0)
1339 if (needs_parentheses (R_temp_kk))
1341 GNUNET_asprintf (&R_cur_r, "%s(%s)*%s", R_last[i][k],
1342 R_temp_kk, R_last[k][j]);
1346 GNUNET_asprintf (&R_cur_r, "%s%s*%s", R_last[i][k], R_temp_kk,
1352 GNUNET_asprintf (&R_cur_r, "%s%s", R_last[i][k], R_last[k][j]);
1357 /* GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "R_cur_l: %s\n", R_cur_l); */
1358 /* GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "R_cur_r: %s\n", R_cur_r); */
1360 // putting it all together
1361 if (NULL != R_cur_l && NULL != R_cur_r)
1364 if (0 == strcmp (R_cur_l, R_cur_r))
1366 R_cur[i][j] = GNUNET_strdup (R_cur_l);
1368 // R_cur_l | R_cur_r
1371 GNUNET_asprintf (&R_cur[i][j], "(%s|%s)", R_cur_l, R_cur_r);
1374 else if (NULL != R_cur_l)
1376 R_cur[i][j] = GNUNET_strdup (R_cur_l);
1378 else if (NULL != R_cur_r)
1380 R_cur[i][j] = GNUNET_strdup (R_cur_r);
1387 GNUNET_free_non_null (R_cur_l);
1388 GNUNET_free_non_null (R_cur_r);
1390 GNUNET_free_non_null (R_temp_ik);
1391 GNUNET_free_non_null (R_temp_kk);
1392 GNUNET_free_non_null (R_temp_kj);
1397 // set R_last = R_cur
1398 for (i = 0; i < n; i++)
1400 for (j = 0; j < n; j++)
1402 GNUNET_free_non_null (R_last[i][j]);
1403 R_last[i][j] = R_cur[i][j];
1409 // assign proofs and hashes
1410 for (i = 0; i < n; i++)
1412 if (NULL != R_last[a->start->proof_id][i])
1414 states[i]->proof = GNUNET_strdup (R_last[a->start->proof_id][i]);
1415 GNUNET_CRYPTO_hash (states[i]->proof, strlen (states[i]->proof),
1420 // complete regex for whole DFA: union of all pairs (start state/accepting state(s)).
1421 complete_regex = NULL;
1422 for (i = 0; i < n; i++)
1424 if (states[i]->accepting)
1426 if (NULL == complete_regex && 0 < strlen (R_last[a->start->proof_id][i]))
1427 GNUNET_asprintf (&complete_regex, "%s", R_last[a->start->proof_id][i]);
1428 else if (NULL != R_last[a->start->proof_id][i] &&
1429 0 < strlen (R_last[a->start->proof_id][i]))
1431 temp_a = complete_regex;
1432 GNUNET_asprintf (&complete_regex, "%s|%s", complete_regex,
1433 R_last[a->start->proof_id][i]);
1434 GNUNET_free (temp_a);
1438 a->computed_regex = complete_regex;
1440 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
1441 "---------------------------------------------\n");
1442 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "Regex: %s\n", a->regex);
1443 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "Complete Regex: %s\n", complete_regex);
1444 GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
1445 "---------------------------------------------\n");
1448 for (i = 0; i < n; i++)
1450 for (j = 0; j < n; j++)
1451 GNUNET_free_non_null (R_last[i][j]);
1456 * Creates a new DFA state based on a set of NFA states. Needs to be freed using
1457 * automaton_destroy_state.
1459 * @param ctx context
1460 * @param nfa_states set of NFA states on which the DFA should be based on
1462 * @return new DFA state
1464 static struct GNUNET_REGEX_State *
1465 dfa_state_create (struct GNUNET_REGEX_Context *ctx,
1466 struct GNUNET_REGEX_StateSet *nfa_states)
1468 struct GNUNET_REGEX_State *s;
1471 struct GNUNET_REGEX_State *cstate;
1472 struct Transition *ctran;
1474 struct Transition *t;
1477 s = GNUNET_malloc (sizeof (struct GNUNET_REGEX_State));
1478 s->id = ctx->state_id++;
1488 if (NULL == nfa_states)
1490 GNUNET_asprintf (&s->name, "s%i", s->id);
1494 s->nfa_set = nfa_states;
1496 if (nfa_states->len < 1)
1499 // Create a name based on 'sset'
1500 s->name = GNUNET_malloc (sizeof (char) * 2);
1501 strcat (s->name, "{");
1504 for (i = 0; i < nfa_states->len; i++)
1506 cstate = nfa_states->states[i];
1507 GNUNET_asprintf (&name, "%i,", cstate->id);
1511 len = strlen (s->name) + strlen (name) + 1;
1512 s->name = GNUNET_realloc (s->name, len);
1513 strcat (s->name, name);
1518 // Add a transition for each distinct label to NULL state
1519 for (ctran = cstate->transitions_head; NULL != ctran; ctran = ctran->next)
1521 if (0 != ctran->label)
1525 for (t = s->transitions_head; NULL != t; t = t->next)
1527 if (t->label == ctran->label)
1535 state_add_transition (ctx, s, ctran->label, NULL);
1539 // If the nfa_states contain an accepting state, the new dfa state is also
1541 if (cstate->accepting)
1545 s->name[strlen (s->name) - 1] = '}';
1551 * Move from the given state 's' to the next state on transition 'label'
1553 * @param s starting state
1554 * @param label edge label to follow
1556 * @return new state or NULL, if transition on label not possible
1558 static struct GNUNET_REGEX_State *
1559 dfa_move (struct GNUNET_REGEX_State *s, const char label)
1561 struct Transition *t;
1562 struct GNUNET_REGEX_State *new_s;
1569 for (t = s->transitions_head; NULL != t; t = t->next)
1571 if (label == t->label)
1573 new_s = t->to_state;
1582 * Remove all unreachable states from DFA 'a'. Unreachable states are those
1583 * states that are not reachable from the starting state.
1585 * @param a DFA automaton
1588 dfa_remove_unreachable_states (struct GNUNET_REGEX_Automaton *a)
1590 struct GNUNET_REGEX_State *s;
1591 struct GNUNET_REGEX_State *s_next;
1593 // 1. unmark all states
1594 for (s = a->states_head; NULL != s; s = s->next)
1595 s->marked = GNUNET_NO;
1597 // 2. traverse dfa from start state and mark all visited states
1598 automaton_traverse (a, NULL, NULL);
1600 // 3. delete all states that were not visited
1601 for (s = a->states_head; NULL != s; s = s_next)
1604 if (GNUNET_NO == s->marked)
1605 automaton_remove_state (a, s);
1610 * Remove all dead states from the DFA 'a'. Dead states are those states that do
1611 * not transition to any other state but themselfes.
1613 * @param a DFA automaton
1616 dfa_remove_dead_states (struct GNUNET_REGEX_Automaton *a)
1618 struct GNUNET_REGEX_State *s;
1619 struct Transition *t;
1622 GNUNET_assert (DFA == a->type);
1624 for (s = a->states_head; NULL != s; s = s->next)
1630 for (t = s->transitions_head; NULL != t; t = t->next)
1632 if (NULL != t->to_state && t->to_state != s)
1642 // state s is dead, remove it
1643 automaton_remove_state (a, s);
1648 * Merge all non distinguishable states in the DFA 'a'
1650 * @param ctx context
1651 * @param a DFA automaton
1654 dfa_merge_nondistinguishable_states (struct GNUNET_REGEX_Context *ctx,
1655 struct GNUNET_REGEX_Automaton *a)
1658 int table[a->state_count][a->state_count];
1659 struct GNUNET_REGEX_State *s1;
1660 struct GNUNET_REGEX_State *s2;
1661 struct Transition *t1;
1662 struct Transition *t2;
1663 struct GNUNET_REGEX_State *s1_next;
1664 struct GNUNET_REGEX_State *s2_next;
1666 int num_equal_edges;
1668 for (i = 0, s1 = a->states_head; i < a->state_count && NULL != s1;
1674 // Mark all pairs of accepting/!accepting states
1675 for (s1 = a->states_head; NULL != s1; s1 = s1->next)
1677 for (s2 = a->states_head; NULL != s2; s2 = s2->next)
1679 table[s1->marked][s2->marked] = 0;
1681 if ((s1->accepting && !s2->accepting) ||
1682 (!s1->accepting && s2->accepting))
1684 table[s1->marked][s2->marked] = 1;
1689 // Find all equal states
1694 for (s1 = a->states_head; NULL != s1; s1 = s1->next)
1696 for (s2 = a->states_head; NULL != s2 && s1 != s2; s2 = s2->next)
1698 if (0 != table[s1->marked][s2->marked])
1701 num_equal_edges = 0;
1702 for (t1 = s1->transitions_head; NULL != t1; t1 = t1->next)
1704 for (t2 = s2->transitions_head; NULL != t2; t2 = t2->next)
1706 if (t1->label == t2->label)
1709 if (0 != table[t1->to_state->marked][t2->to_state->marked] ||
1710 0 != table[t2->to_state->marked][t1->to_state->marked])
1712 table[s1->marked][s2->marked] = t1->label != 0 ? t1->label : 1;
1718 if (num_equal_edges != s1->transition_count ||
1719 num_equal_edges != s2->transition_count)
1721 // Make sure ALL edges of possible equal states are the same
1722 table[s1->marked][s2->marked] = -2;
1728 // Merge states that are equal
1729 for (s1 = a->states_head; NULL != s1; s1 = s1_next)
1732 for (s2 = a->states_head; NULL != s2 && s1 != s2; s2 = s2_next)
1735 if (table[s1->marked][s2->marked] == 0)
1736 automaton_merge_states (ctx, a, s1, s2);
1742 * Minimize the given DFA 'a' by removing all unreachable states, removing all
1743 * dead states and merging all non distinguishable states
1745 * @param ctx context
1746 * @param a DFA automaton
1749 dfa_minimize (struct GNUNET_REGEX_Context *ctx,
1750 struct GNUNET_REGEX_Automaton *a)
1755 GNUNET_assert (DFA == a->type);
1757 // 1. remove unreachable states
1758 dfa_remove_unreachable_states (a);
1760 // 2. remove dead states
1761 dfa_remove_dead_states (a);
1763 // 3. Merge nondistinguishable states
1764 dfa_merge_nondistinguishable_states (ctx, a);
1768 * Creates a new NFA fragment. Needs to be cleared using
1769 * automaton_fragment_clear.
1771 * @param start starting state
1772 * @param end end state
1774 * @return new NFA fragment
1776 static struct GNUNET_REGEX_Automaton *
1777 nfa_fragment_create (struct GNUNET_REGEX_State *start,
1778 struct GNUNET_REGEX_State *end)
1780 struct GNUNET_REGEX_Automaton *n;
1782 n = GNUNET_malloc (sizeof (struct GNUNET_REGEX_Automaton));
1788 if (NULL == start && NULL == end)
1791 automaton_add_state (n, end);
1792 automaton_add_state (n, start);
1801 * Adds a list of states to the given automaton 'n'.
1803 * @param n automaton to which the states should be added
1804 * @param states_head head of the DLL of states
1805 * @param states_tail tail of the DLL of states
1808 nfa_add_states (struct GNUNET_REGEX_Automaton *n,
1809 struct GNUNET_REGEX_State *states_head,
1810 struct GNUNET_REGEX_State *states_tail)
1812 struct GNUNET_REGEX_State *s;
1814 if (NULL == n || NULL == states_head)
1816 GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "Could not add states\n");
1820 if (NULL == n->states_head)
1822 n->states_head = states_head;
1823 n->states_tail = states_tail;
1827 if (NULL != states_head)
1829 n->states_tail->next = states_head;
1830 n->states_tail = states_tail;
1833 for (s = states_head; NULL != s; s = s->next)
1838 * Creates a new NFA state. Needs to be freed using automaton_destroy_state.
1840 * @param ctx context
1841 * @param accepting is it an accepting state or not
1843 * @return new NFA state
1845 static struct GNUNET_REGEX_State *
1846 nfa_state_create (struct GNUNET_REGEX_Context *ctx, int accepting)
1848 struct GNUNET_REGEX_State *s;
1850 s = GNUNET_malloc (sizeof (struct GNUNET_REGEX_State));
1851 s->id = ctx->state_id++;
1852 s->accepting = accepting;
1859 GNUNET_asprintf (&s->name, "s%i", s->id);
1865 * Calculates the NFA closure set for the given state.
1867 * @param nfa the NFA containing 's'
1868 * @param s starting point state
1869 * @param label transitioning label on which to base the closure on,
1870 * pass 0 for epsilon transition
1872 * @return sorted nfa closure on 'label' (epsilon closure if 'label' is 0)
1874 static struct GNUNET_REGEX_StateSet *
1875 nfa_closure_create (struct GNUNET_REGEX_Automaton *nfa,
1876 struct GNUNET_REGEX_State *s, const char label)
1878 struct GNUNET_REGEX_StateSet *cls;
1879 struct GNUNET_REGEX_StateSet *cls_check;
1880 struct GNUNET_REGEX_State *clsstate;
1881 struct GNUNET_REGEX_State *currentstate;
1882 struct Transition *ctran;
1887 cls = GNUNET_malloc (sizeof (struct GNUNET_REGEX_StateSet));
1888 cls_check = GNUNET_malloc (sizeof (struct GNUNET_REGEX_StateSet));
1890 for (clsstate = nfa->states_head; NULL != clsstate; clsstate = clsstate->next)
1891 clsstate->contained = 0;
1893 // Add start state to closure only for epsilon closure
1895 GNUNET_array_append (cls->states, cls->len, s);
1897 GNUNET_array_append (cls_check->states, cls_check->len, s);
1898 while (cls_check->len > 0)
1900 currentstate = cls_check->states[cls_check->len - 1];
1901 GNUNET_array_grow (cls_check->states, cls_check->len, cls_check->len - 1);
1903 for (ctran = currentstate->transitions_head; NULL != ctran;
1904 ctran = ctran->next)
1906 if (NULL != ctran->to_state && label == ctran->label)
1908 clsstate = ctran->to_state;
1910 if (NULL != clsstate && 0 == clsstate->contained)
1912 GNUNET_array_append (cls->states, cls->len, clsstate);
1913 GNUNET_array_append (cls_check->states, cls_check->len, clsstate);
1914 clsstate->contained = 1;
1919 GNUNET_assert (0 == cls_check->len);
1920 GNUNET_free (cls_check);
1924 qsort (cls->states, cls->len, sizeof (struct GNUNET_REGEX_State *),
1931 * Calculates the closure set for the given set of states.
1933 * @param nfa the NFA containing 's'
1934 * @param states list of states on which to base the closure on
1935 * @param label transitioning label for which to base the closure on,
1936 * pass 0 for epsilon transition
1938 * @return sorted nfa closure on 'label' (epsilon closure if 'label' is 0)
1940 static struct GNUNET_REGEX_StateSet *
1941 nfa_closure_set_create (struct GNUNET_REGEX_Automaton *nfa,
1942 struct GNUNET_REGEX_StateSet *states, const char label)
1944 struct GNUNET_REGEX_State *s;
1945 struct GNUNET_REGEX_StateSet *sset;
1946 struct GNUNET_REGEX_StateSet *cls;
1955 cls = GNUNET_malloc (sizeof (struct GNUNET_REGEX_StateSet));
1957 for (i = 0; i < states->len; i++)
1959 s = states->states[i];
1960 sset = nfa_closure_create (nfa, s, label);
1962 for (j = 0; j < sset->len; j++)
1965 for (k = 0; k < cls->len; k++)
1967 if (sset->states[j]->id == cls->states[k]->id)
1974 GNUNET_array_append (cls->states, cls->len, sset->states[j]);
1976 state_set_clear (sset);
1980 qsort (cls->states, cls->len, sizeof (struct GNUNET_REGEX_State *),
1987 * Pops two NFA fragments (a, b) from the stack and concatenates them (ab)
1989 * @param ctx context
1992 nfa_add_concatenation (struct GNUNET_REGEX_Context *ctx)
1994 struct GNUNET_REGEX_Automaton *a;
1995 struct GNUNET_REGEX_Automaton *b;
1996 struct GNUNET_REGEX_Automaton *new;
1998 b = ctx->stack_tail;
1999 GNUNET_CONTAINER_DLL_remove (ctx->stack_head, ctx->stack_tail, b);
2000 a = ctx->stack_tail;
2001 GNUNET_CONTAINER_DLL_remove (ctx->stack_head, ctx->stack_tail, a);
2003 state_add_transition (ctx, a->end, 0, b->start);
2004 a->end->accepting = 0;
2005 b->end->accepting = 1;
2007 new = nfa_fragment_create (NULL, NULL);
2008 nfa_add_states (new, a->states_head, a->states_tail);
2009 nfa_add_states (new, b->states_head, b->states_tail);
2010 new->start = a->start;
2012 automaton_fragment_clear (a);
2013 automaton_fragment_clear (b);
2015 GNUNET_CONTAINER_DLL_insert_tail (ctx->stack_head, ctx->stack_tail, new);
2019 * Pops a NFA fragment from the stack (a) and adds a new fragment (a*)
2021 * @param ctx context
2024 nfa_add_star_op (struct GNUNET_REGEX_Context *ctx)
2026 struct GNUNET_REGEX_Automaton *a;
2027 struct GNUNET_REGEX_Automaton *new;
2028 struct GNUNET_REGEX_State *start;
2029 struct GNUNET_REGEX_State *end;
2031 a = ctx->stack_tail;
2032 GNUNET_CONTAINER_DLL_remove (ctx->stack_head, ctx->stack_tail, a);
2036 GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
2037 "nfa_add_star_op failed, because there was no element on the stack");
2041 start = nfa_state_create (ctx, 0);
2042 end = nfa_state_create (ctx, 1);
2044 state_add_transition (ctx, start, 0, a->start);
2045 state_add_transition (ctx, start, 0, end);
2046 state_add_transition (ctx, a->end, 0, a->start);
2047 state_add_transition (ctx, a->end, 0, end);
2049 a->end->accepting = 0;
2052 new = nfa_fragment_create (start, end);
2053 nfa_add_states (new, a->states_head, a->states_tail);
2054 automaton_fragment_clear (a);
2056 GNUNET_CONTAINER_DLL_insert_tail (ctx->stack_head, ctx->stack_tail, new);
2060 * Pops an NFA fragment (a) from the stack and adds a new fragment (a+)
2062 * @param ctx context
2065 nfa_add_plus_op (struct GNUNET_REGEX_Context *ctx)
2067 struct GNUNET_REGEX_Automaton *a;
2069 a = ctx->stack_tail;
2070 GNUNET_CONTAINER_DLL_remove (ctx->stack_head, ctx->stack_tail, a);
2072 state_add_transition (ctx, a->end, 0, a->start);
2074 GNUNET_CONTAINER_DLL_insert_tail (ctx->stack_head, ctx->stack_tail, a);
2078 * Pops an NFA fragment (a) from the stack and adds a new fragment (a?)
2080 * @param ctx context
2083 nfa_add_question_op (struct GNUNET_REGEX_Context *ctx)
2085 struct GNUNET_REGEX_Automaton *a;
2086 struct GNUNET_REGEX_Automaton *new;
2087 struct GNUNET_REGEX_State *start;
2088 struct GNUNET_REGEX_State *end;
2090 a = ctx->stack_tail;
2091 GNUNET_CONTAINER_DLL_remove (ctx->stack_head, ctx->stack_tail, a);
2095 GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
2096 "nfa_add_question_op failed, because there was no element on the stack");
2100 start = nfa_state_create (ctx, 0);
2101 end = nfa_state_create (ctx, 1);
2103 state_add_transition (ctx, start, 0, a->start);
2104 state_add_transition (ctx, start, 0, end);
2105 state_add_transition (ctx, a->end, 0, end);
2107 a->end->accepting = 0;
2109 new = nfa_fragment_create (start, end);
2110 nfa_add_states (new, a->states_head, a->states_tail);
2111 automaton_fragment_clear (a);
2113 GNUNET_CONTAINER_DLL_insert_tail (ctx->stack_head, ctx->stack_tail, new);
2117 * Pops two NFA fragments (a, b) from the stack and adds a new NFA fragment that
2118 * alternates between a and b (a|b)
2120 * @param ctx context
2123 nfa_add_alternation (struct GNUNET_REGEX_Context *ctx)
2125 struct GNUNET_REGEX_Automaton *a;
2126 struct GNUNET_REGEX_Automaton *b;
2127 struct GNUNET_REGEX_Automaton *new;
2128 struct GNUNET_REGEX_State *start;
2129 struct GNUNET_REGEX_State *end;
2131 b = ctx->stack_tail;
2132 GNUNET_CONTAINER_DLL_remove (ctx->stack_head, ctx->stack_tail, b);
2133 a = ctx->stack_tail;
2134 GNUNET_CONTAINER_DLL_remove (ctx->stack_head, ctx->stack_tail, a);
2136 start = nfa_state_create (ctx, 0);
2137 end = nfa_state_create (ctx, 1);
2138 state_add_transition (ctx, start, 0, a->start);
2139 state_add_transition (ctx, start, 0, b->start);
2141 state_add_transition (ctx, a->end, 0, end);
2142 state_add_transition (ctx, b->end, 0, end);
2144 a->end->accepting = 0;
2145 b->end->accepting = 0;
2148 new = nfa_fragment_create (start, end);
2149 nfa_add_states (new, a->states_head, a->states_tail);
2150 nfa_add_states (new, b->states_head, b->states_tail);
2151 automaton_fragment_clear (a);
2152 automaton_fragment_clear (b);
2154 GNUNET_CONTAINER_DLL_insert_tail (ctx->stack_head, ctx->stack_tail, new);
2158 * Adds a new nfa fragment to the stack
2160 * @param ctx context
2161 * @param lit label for nfa transition
2164 nfa_add_label (struct GNUNET_REGEX_Context *ctx, const char lit)
2166 struct GNUNET_REGEX_Automaton *n;
2167 struct GNUNET_REGEX_State *start;
2168 struct GNUNET_REGEX_State *end;
2170 GNUNET_assert (NULL != ctx);
2172 start = nfa_state_create (ctx, 0);
2173 end = nfa_state_create (ctx, 1);
2174 state_add_transition (ctx, start, lit, end);
2175 n = nfa_fragment_create (start, end);
2176 GNUNET_assert (NULL != n);
2177 GNUNET_CONTAINER_DLL_insert_tail (ctx->stack_head, ctx->stack_tail, n);
2181 * Initialize a new context
2183 * @param ctx context
2186 GNUNET_REGEX_context_init (struct GNUNET_REGEX_Context *ctx)
2190 GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "Context was NULL!");
2194 ctx->transition_id = 0;
2196 ctx->stack_head = NULL;
2197 ctx->stack_tail = NULL;
2201 * Construct an NFA by parsing the regex string of length 'len'.
2203 * @param regex regular expression string
2204 * @param len length of the string
2206 * @return NFA, needs to be freed using GNUNET_REGEX_destroy_automaton
2208 struct GNUNET_REGEX_Automaton *
2209 GNUNET_REGEX_construct_nfa (const char *regex, const size_t len)
2211 struct GNUNET_REGEX_Context ctx;
2212 struct GNUNET_REGEX_Automaton *nfa;
2216 unsigned int altcount;
2217 unsigned int atomcount;
2218 unsigned int pcount;
2225 GNUNET_REGEX_context_init (&ctx);
2234 for (count = 0; count < len && *regexp; count++, regexp++)
2242 nfa_add_concatenation (&ctx);
2244 GNUNET_array_grow (p, pcount, pcount + 1);
2245 p[pcount - 1].altcount = altcount;
2246 p[pcount - 1].atomcount = atomcount;
2253 error_msg = "Cannot append '|' to nothing";
2256 while (--atomcount > 0)
2257 nfa_add_concatenation (&ctx);
2263 error_msg = "Missing opening '('";
2268 // Ignore this: "()"
2270 altcount = p[pcount].altcount;
2271 atomcount = p[pcount].atomcount;
2274 while (--atomcount > 0)
2275 nfa_add_concatenation (&ctx);
2276 for (; altcount > 0; altcount--)
2277 nfa_add_alternation (&ctx);
2279 altcount = p[pcount].altcount;
2280 atomcount = p[pcount].atomcount;
2286 error_msg = "Cannot append '*' to nothing";
2289 nfa_add_star_op (&ctx);
2294 error_msg = "Cannot append '+' to nothing";
2297 nfa_add_plus_op (&ctx);
2302 error_msg = "Cannot append '?' to nothing";
2305 nfa_add_question_op (&ctx);
2307 case 92: /* escape: \ */
2314 nfa_add_concatenation (&ctx);
2316 nfa_add_label (&ctx, *regexp);
2323 error_msg = "Unbalanced parenthesis";
2326 while (--atomcount > 0)
2327 nfa_add_concatenation (&ctx);
2328 for (; altcount > 0; altcount--)
2329 nfa_add_alternation (&ctx);
2331 GNUNET_free_non_null (p);
2333 nfa = ctx.stack_tail;
2334 GNUNET_CONTAINER_DLL_remove (ctx.stack_head, ctx.stack_tail, nfa);
2336 if (NULL != ctx.stack_head)
2338 error_msg = "Creating the NFA failed. NFA stack was not empty!";
2342 nfa->regex = GNUNET_strdup (regex);
2347 GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "Could not parse regex: %s\n", regex);
2348 if (NULL != error_msg)
2349 GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "%s\n", error_msg);
2351 GNUNET_free_non_null (p);
2353 while (NULL != (nfa = ctx.stack_head))
2355 GNUNET_CONTAINER_DLL_remove (ctx.stack_head, ctx.stack_tail, nfa);
2356 GNUNET_REGEX_automaton_destroy (nfa);
2363 * Create DFA states based on given 'nfa' and starting with 'dfa_state'.
2365 * @param ctx context.
2366 * @param nfa NFA automaton.
2367 * @param dfa DFA automaton.
2368 * @param dfa_state current dfa state, pass epsilon closure of first nfa state
2372 construct_dfa_states (struct GNUNET_REGEX_Context *ctx,
2373 struct GNUNET_REGEX_Automaton *nfa,
2374 struct GNUNET_REGEX_Automaton *dfa,
2375 struct GNUNET_REGEX_State *dfa_state)
2377 struct Transition *ctran;
2378 struct GNUNET_REGEX_State *state_iter;
2379 struct GNUNET_REGEX_State *new_dfa_state;
2380 struct GNUNET_REGEX_State *state_contains;
2381 struct GNUNET_REGEX_StateSet *tmp;
2382 struct GNUNET_REGEX_StateSet *nfa_set;
2384 for (ctran = dfa_state->transitions_head; NULL != ctran; ctran = ctran->next)
2386 if (0 == ctran->label || NULL != ctran->to_state)
2389 tmp = nfa_closure_set_create (nfa, dfa_state->nfa_set, ctran->label);
2390 nfa_set = nfa_closure_set_create (nfa, tmp, 0);
2391 state_set_clear (tmp);
2392 new_dfa_state = dfa_state_create (ctx, nfa_set);
2393 state_contains = NULL;
2394 for (state_iter = dfa->states_head; NULL != state_iter;
2395 state_iter = state_iter->next)
2397 if (0 == state_set_compare (state_iter->nfa_set, new_dfa_state->nfa_set))
2398 state_contains = state_iter;
2401 if (NULL == state_contains)
2403 automaton_add_state (dfa, new_dfa_state);
2404 ctran->to_state = new_dfa_state;
2405 construct_dfa_states (ctx, nfa, dfa, new_dfa_state);
2409 ctran->to_state = state_contains;
2410 automaton_destroy_state (new_dfa_state);
2416 * Construct DFA for the given 'regex' of length 'len'
2418 * @param regex regular expression string
2419 * @param len length of the regular expression
2421 * @return DFA, needs to be freed using GNUNET_REGEX_destroy_automaton
2423 struct GNUNET_REGEX_Automaton *
2424 GNUNET_REGEX_construct_dfa (const char *regex, const size_t len)
2426 struct GNUNET_REGEX_Context ctx;
2427 struct GNUNET_REGEX_Automaton *dfa;
2428 struct GNUNET_REGEX_Automaton *nfa;
2429 struct GNUNET_REGEX_StateSet *nfa_set;
2431 GNUNET_REGEX_context_init (&ctx);
2434 nfa = GNUNET_REGEX_construct_nfa (regex, len);
2438 GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
2439 "Could not create DFA, because NFA creation failed\n");
2443 dfa = GNUNET_malloc (sizeof (struct GNUNET_REGEX_Automaton));
2445 dfa->regex = GNUNET_strdup (regex);
2447 // Create DFA start state from epsilon closure
2448 nfa_set = nfa_closure_create (nfa, nfa->start, 0);
2449 dfa->start = dfa_state_create (&ctx, nfa_set);
2450 automaton_add_state (dfa, dfa->start);
2452 construct_dfa_states (&ctx, nfa, dfa, dfa->start);
2454 GNUNET_REGEX_automaton_destroy (nfa);
2457 dfa_minimize (&ctx, dfa);
2460 scc_tarjan (&ctx, dfa);
2462 // Create proofs for all states
2463 automaton_create_proofs (dfa);
2469 * Free the memory allocated by constructing the GNUNET_REGEX_Automaton data
2472 * @param a automaton to be destroyed
2475 GNUNET_REGEX_automaton_destroy (struct GNUNET_REGEX_Automaton *a)
2477 struct GNUNET_REGEX_State *s;
2478 struct GNUNET_REGEX_State *next_state;
2483 GNUNET_free_non_null (a->regex);
2484 GNUNET_free_non_null (a->computed_regex);
2486 for (s = a->states_head; NULL != s;)
2488 next_state = s->next;
2489 automaton_destroy_state (s);
2497 * Save a state to an open file pointer. cls is expected to be a file pointer to
2498 * an open file. Used only in conjunction with
2499 * GNUNET_REGEX_automaton_save_graph.
2501 * @param cls file pointer.
2502 * @param count current count of the state, not used.
2506 GNUNET_REGEX_automaton_save_graph_step (void *cls, unsigned int count,
2507 struct GNUNET_REGEX_State *s)
2510 struct Transition *ctran;
2512 char *s_tran = NULL;
2518 GNUNET_asprintf (&s_acc,
2519 "\"%s(%i)\" [shape=doublecircle, color=\"0.%i 0.8 0.95\"];\n",
2520 s->name, s->proof_id, s->scc_id);
2524 GNUNET_asprintf (&s_acc, "\"%s(%i)\" [color=\"0.%i 0.8 0.95\"];\n", s->name,
2525 s->proof_id, s->scc_id);
2530 GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "Could not print state %s\n", s->name);
2533 fwrite (s_acc, strlen (s_acc), 1, p);
2534 GNUNET_free (s_acc);
2537 for (ctran = s->transitions_head; NULL != ctran; ctran = ctran->next)
2539 if (NULL == ctran->to_state)
2541 GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
2542 "Transition from State %i has no state for transitioning\n",
2547 if (ctran->label == 0)
2549 GNUNET_asprintf (&s_tran,
2550 "\"%s(%i)\" -> \"%s(%i)\" [label = \"epsilon\", color=\"0.%i 0.8 0.95\"];\n",
2551 s->name, s->proof_id, ctran->to_state->name,
2552 ctran->to_state->proof_id, s->scc_id);
2556 GNUNET_asprintf (&s_tran,
2557 "\"%s(%i)\" -> \"%s(%i)\" [label = \"%c\", color=\"0.%i 0.8 0.95\"];\n",
2558 s->name, s->proof_id, ctran->to_state->name,
2559 ctran->to_state->proof_id, ctran->label, s->scc_id);
2564 GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "Could not print state %s\n",
2569 fwrite (s_tran, strlen (s_tran), 1, p);
2570 GNUNET_free (s_tran);
2576 * Save the given automaton as a GraphViz dot file
2578 * @param a the automaton to be saved
2579 * @param filename where to save the file
2582 GNUNET_REGEX_automaton_save_graph (struct GNUNET_REGEX_Automaton *a,
2583 const char *filename)
2591 GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "Could not print NFA, was NULL!");
2595 if (NULL == filename || strlen (filename) < 1)
2597 GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "No Filename given!");
2601 p = fopen (filename, "w");
2605 GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "Could not open file for writing: %s",
2610 start = "digraph G {\nrankdir=LR\n";
2611 fwrite (start, strlen (start), 1, p);
2613 automaton_traverse (a, &GNUNET_REGEX_automaton_save_graph_step, p);
2616 fwrite (end, strlen (end), 1, p);
2621 * Evaluates the given string using the given DFA automaton
2623 * @param a automaton, type must be DFA
2624 * @param string string that should be evaluated
2626 * @return 0 if string matches, non 0 otherwise
2629 evaluate_dfa (struct GNUNET_REGEX_Automaton *a, const char *string)
2632 struct GNUNET_REGEX_State *s;
2636 GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
2637 "Tried to evaluate DFA, but NFA automaton given");
2643 // If the string is empty but the starting state is accepting, we accept.
2644 if ((NULL == string || 0 == strlen (string)) && s->accepting)
2647 for (strp = string; NULL != strp && *strp; strp++)
2649 s = dfa_move (s, *strp);
2654 if (NULL != s && s->accepting)
2661 * Evaluates the given string using the given NFA automaton
2663 * @param a automaton, type must be NFA
2664 * @param string string that should be evaluated
2666 * @return 0 if string matches, non 0 otherwise
2669 evaluate_nfa (struct GNUNET_REGEX_Automaton *a, const char *string)
2672 struct GNUNET_REGEX_State *s;
2673 struct GNUNET_REGEX_StateSet *sset;
2674 struct GNUNET_REGEX_StateSet *new_sset;
2680 GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
2681 "Tried to evaluate NFA, but DFA automaton given");
2685 // If the string is empty but the starting state is accepting, we accept.
2686 if ((NULL == string || 0 == strlen (string)) && a->start->accepting)
2691 sset = nfa_closure_create (a, a->start, 0);
2693 for (strp = string; NULL != strp && *strp; strp++)
2695 new_sset = nfa_closure_set_create (a, sset, *strp);
2696 state_set_clear (sset);
2697 sset = nfa_closure_set_create (a, new_sset, 0);
2698 state_set_clear (new_sset);
2701 for (i = 0; i < sset->len; i++)
2703 s = sset->states[i];
2704 if (NULL != s && s->accepting)
2711 state_set_clear (sset);
2716 * Evaluates the given 'string' against the given compiled regex
2718 * @param a automaton
2719 * @param string string to check
2721 * @return 0 if string matches, non 0 otherwise
2724 GNUNET_REGEX_eval (struct GNUNET_REGEX_Automaton *a, const char *string)
2731 result = evaluate_dfa (a, string);
2734 result = evaluate_nfa (a, string);
2737 GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
2738 "Evaluating regex failed, automaton has no type!\n");
2739 result = GNUNET_SYSERR;
2747 * Get the computed regex of the given automaton.
2748 * When constructing the automaton a proof is computed for each state,
2749 * consisting of the regular expression leading to this state. A complete
2750 * regex for the automaton can be computed by combining these proofs.
2751 * As of now this computed regex is only useful for testing.
2754 GNUNET_REGEX_get_computed_regex (struct GNUNET_REGEX_Automaton *a)
2759 return a->computed_regex;
2763 * Get the first key for the given 'input_string'. This hashes the first x bits
2764 * of the 'input_strings'.
2766 * @param input_string string.
2767 * @param string_len length of the 'input_string'.
2768 * @param key pointer to where to write the hash code.
2770 * @return number of bits of 'input_string' that have been consumed
2771 * to construct the key
2774 GNUNET_REGEX_get_first_key (const char *input_string, unsigned int string_len,
2775 struct GNUNET_HashCode *key)
2779 size = string_len < INITIAL_BITS ? string_len : INITIAL_BITS;
2781 if (NULL == input_string)
2783 GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "Given input string was NULL!\n");
2787 GNUNET_CRYPTO_hash (input_string, size, key);
2793 * Check if the given 'proof' matches the given 'key'.
2795 * @param proof partial regex
2798 * @return GNUNET_OK if the proof is valid for the given key
2801 GNUNET_REGEX_check_proof (const char *proof, const struct GNUNET_HashCode *key)
2807 * Iterate over all edges helper function starting from state 's', calling
2808 * iterator on for each edge.
2811 * @param iterator iterator function called for each edge.
2812 * @param iterator_cls closure.
2815 iterate_edge (struct GNUNET_REGEX_State *s, GNUNET_REGEX_KeyIterator iterator,
2818 struct Transition *t;
2819 struct GNUNET_REGEX_Edge edges[s->transition_count];
2820 unsigned int num_edges;
2822 if (GNUNET_YES != s->marked)
2824 s->marked = GNUNET_YES;
2826 num_edges = state_get_edges (s, edges);
2828 iterator (iterator_cls, &s->hash, s->proof, s->accepting, num_edges, edges);
2830 for (t = s->transitions_head; NULL != t; t = t->next)
2831 iterate_edge (t->to_state, iterator, iterator_cls);
2836 * Iterate over all edges starting from start state of automaton 'a'. Calling
2837 * iterator for each edge.
2839 * @param a automaton.
2840 * @param iterator iterator called for each edge.
2841 * @param iterator_cls closure.
2844 GNUNET_REGEX_iterate_all_edges (struct GNUNET_REGEX_Automaton *a,
2845 GNUNET_REGEX_KeyIterator iterator,
2848 struct GNUNET_REGEX_State *s;
2850 for (s = a->states_head; NULL != s; s = s->next)
2851 s->marked = GNUNET_NO;
2853 iterate_edge (a->start, iterator, iterator_cls);