/* This file is part of GNUnet (C) 2012 Christian Grothoff (and other contributing authors) GNUnet is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 3, or (at your option) any later version. GNUnet is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with GNUnet; see the file COPYING. If not, write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ /** * @file src/regex/regex.c * @brief library to create automatons from regular expressions * @author Maximilian Szengel */ #include "platform.h" #include "gnunet_container_lib.h" #include "gnunet_crypto_lib.h" #include "gnunet_regex_lib.h" #include "regex_internal.h" /** * Constant for how many bits the initial string regex should have. */ #define INITIAL_BITS 10 /** * Context that contains an id counter for states and transitions as well as a * DLL of automatons used as a stack for NFA construction. */ struct GNUNET_REGEX_Context { /** * Unique state id. */ unsigned int state_id; /** * Unique transition id. */ unsigned int transition_id; /** * DLL of GNUNET_REGEX_Automaton's used as a stack. */ struct GNUNET_REGEX_Automaton *stack_head; /** * DLL of GNUNET_REGEX_Automaton's used as a stack. */ struct GNUNET_REGEX_Automaton *stack_tail; }; /** * Type of an automaton. */ enum GNUNET_REGEX_AutomatonType { NFA, DFA }; /** * Automaton representation. */ struct GNUNET_REGEX_Automaton { /** * Linked list of NFAs used for partial NFA creation. */ struct GNUNET_REGEX_Automaton *prev; /** * Linked list of NFAs used for partial NFA creation. */ struct GNUNET_REGEX_Automaton *next; /** * First state of the automaton. This is mainly used for constructing an NFA, * where each NFA itself consists of one or more NFAs linked together. */ struct GNUNET_REGEX_State *start; /** * End state of the partial NFA. This is undefined for DFAs */ struct GNUNET_REGEX_State *end; /** * Number of states in the automaton. */ unsigned int state_count; /** * DLL of states. */ struct GNUNET_REGEX_State *states_head; /** * DLL of states */ struct GNUNET_REGEX_State *states_tail; /** * Type of the automaton. */ enum GNUNET_REGEX_AutomatonType type; /** * Regex */ char *regex; /** * Canonical regex (result of RX->NFA->DFA->RX) */ char *canonical_regex; }; /** * A state. Can be used in DFA and NFA automatons. */ struct GNUNET_REGEX_State { /** * This is a linked list. */ struct GNUNET_REGEX_State *prev; /** * This is a linked list. */ struct GNUNET_REGEX_State *next; /** * Unique state id. */ unsigned int id; /** * If this is an accepting state or not. */ int accepting; /** * Marking of the state. This is used for marking all visited states when * traversing all states of an automaton and for cases where the state id * cannot be used (dfa minimization). */ int marked; /** * Marking the state as contained. This is used for checking, if the state is * contained in a set in constant time */ int contained; /** * Marking the state as part of an SCC (Strongly Connected Component). All * states with the same scc_id are part of the same SCC. scc_id is 0, if state * is not a part of any SCC. */ unsigned int scc_id; /** * Used for SCC detection. */ int index; /** * Used for SCC detection. */ int lowlink; /** * Human readable name of the automaton. Used for debugging and graph * creation. */ char *name; /** * Hash of the state. */ struct GNUNET_HashCode hash; /** * State ID for proof creation. */ unsigned int proof_id; /** * Proof for this state. */ char *proof; /** * Number of transitions from this state to other states. */ unsigned int transition_count; /** * DLL of transitions. */ struct Transition *transitions_head; /** * DLL of transitions. */ struct Transition *transitions_tail; /** * Set of states on which this state is based on. Used when creating a DFA out * of several NFA states. */ struct GNUNET_REGEX_StateSet *nfa_set; }; /** * Transition between two states. Each state can have 0-n transitions. If label * is 0, this is considered to be an epsilon transition. */ struct Transition { /** * This is a linked list. */ struct Transition *prev; /** * This is a linked list. */ struct Transition *next; /** * Unique id of this transition. */ unsigned int id; /** * Label for this transition. This is basically the edge label for the graph. */ char label; /** * State to which this transition leads. */ struct GNUNET_REGEX_State *to_state; /** * State from which this transition origins. */ struct GNUNET_REGEX_State *from_state; /** * Mark this transition. For example when reversing the automaton. */ int mark; }; /** * Set of states. */ struct GNUNET_REGEX_StateSet { /** * Array of states. */ struct GNUNET_REGEX_State **states; /** * Length of the 'states' array. */ unsigned int len; }; /* * Debug helper functions */ /** * Print all the transitions of state 's'. * * @param s state for which to print it's transitions. */ void debug_print_transitions (struct GNUNET_REGEX_State *s); /** * Print information of the given state 's'. * * @param s state for which debug information should be printed. */ void debug_print_state (struct GNUNET_REGEX_State *s) { char *proof; if (NULL == s->proof) proof = "NULL"; else proof = s->proof; GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "State %i: %s marked: %i accepting: %i scc_id: %i transitions: %i proof: %s\n", s->id, s->name, s->marked, s->accepting, s->scc_id, s->transition_count, proof); GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "Transitions:\n"); debug_print_transitions (s); } /** * Print debug information for all states contained in the automaton 'a'. * * @param a automaton for which debug information of it's states should be printed. */ void debug_print_states (struct GNUNET_REGEX_Automaton *a) { struct GNUNET_REGEX_State *s; for (s = a->states_head; NULL != s; s = s->next) debug_print_state (s); } /** * Print debug information for given transition 't'. * * @param t transition for which to print debug info. */ void debug_print_transition (struct Transition *t) { char *to_state; char *from_state; char label; if (NULL == t) return; if (0 == t->label) label = '0'; else label = t->label; if (NULL == t->to_state) to_state = "NULL"; else to_state = t->to_state->name; if (NULL == t->from_state) from_state = "NULL"; else from_state = t->from_state->name; GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "Transition %i: From %s on %c to %s\n", t->id, from_state, label, to_state); } void debug_print_transitions (struct GNUNET_REGEX_State *s) { struct Transition *t; for (t = s->transitions_head; NULL != t; t = t->next) debug_print_transition (t); } /** * Recursive function doing DFS with 'v' as a start, detecting all SCCs inside * the subgraph reachable from 'v'. Used with scc_tarjan function to detect all * SCCs inside an automaton. * * @param scc_counter counter for numbering the sccs * @param v start vertex * @param index current index * @param stack stack for saving all SCCs * @param stack_size current size of the stack */ static void scc_tarjan_strongconnect (unsigned int *scc_counter, struct GNUNET_REGEX_State *v, unsigned int *index, struct GNUNET_REGEX_State **stack, unsigned int *stack_size) { struct GNUNET_REGEX_State *w; struct Transition *t; v->index = *index; v->lowlink = *index; (*index)++; stack[(*stack_size)++] = v; v->contained = 1; for (t = v->transitions_head; NULL != t; t = t->next) { w = t->to_state; if (NULL != w && w->index < 0) { scc_tarjan_strongconnect (scc_counter, w, index, stack, stack_size); v->lowlink = (v->lowlink > w->lowlink) ? w->lowlink : v->lowlink; } else if (0 != w->contained) v->lowlink = (v->lowlink > w->index) ? w->index : v->lowlink; } if (v->lowlink == v->index) { w = stack[--(*stack_size)]; w->contained = 0; if (v != w) { (*scc_counter)++; while (v != w) { w->scc_id = *scc_counter; w = stack[--(*stack_size)]; w->contained = 0; } w->scc_id = *scc_counter; } } } /** * Detect all SCCs (Strongly Connected Components) inside the given automaton. * SCCs will be marked using the scc_id on each state. * * @param a the automaton for which SCCs should be computed and assigned. */ static void scc_tarjan (struct GNUNET_REGEX_Automaton *a) { unsigned int index; unsigned int scc_counter; struct GNUNET_REGEX_State *v; struct GNUNET_REGEX_State *stack[a->state_count]; unsigned int stack_size; for (v = a->states_head; NULL != v; v = v->next) { v->contained = 0; v->index = -1; v->lowlink = -1; } stack_size = 0; index = 0; scc_counter = 0; for (v = a->states_head; NULL != v; v = v->next) { if (v->index < 0) scc_tarjan_strongconnect (&scc_counter, v, &index, stack, &stack_size); } } /** * Adds a transition from one state to another on 'label'. Does not add * duplicate states. * * @param ctx context * @param from_state starting state for the transition * @param label transition label * @param to_state state to where the transition should point to */ static void state_add_transition (struct GNUNET_REGEX_Context *ctx, struct GNUNET_REGEX_State *from_state, const char label, struct GNUNET_REGEX_State *to_state) { int is_dup; struct Transition *t; struct Transition *oth; if (NULL == from_state) { GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "Could not create Transition.\n"); return; } // Do not add duplicate state transitions is_dup = GNUNET_NO; for (t = from_state->transitions_head; NULL != t; t = t->next) { if (t->to_state == to_state && t->label == label && t->from_state == from_state) { is_dup = GNUNET_YES; break; } } if (is_dup) return; // sort transitions by label for (oth = from_state->transitions_head; NULL != oth; oth = oth->next) { if (oth->label > label) break; } t = GNUNET_malloc (sizeof (struct Transition)); t->id = ctx->transition_id++; t->label = label; t->to_state = to_state; t->from_state = from_state; // Add outgoing transition to 'from_state' from_state->transition_count++; GNUNET_CONTAINER_DLL_insert_before (from_state->transitions_head, from_state->transitions_tail, oth, t); } /** * Compare two states. Used for sorting. * * @param a first state * @param b second state * * @return an integer less than, equal to, or greater than zero * if the first argument is considered to be respectively * less than, equal to, or greater than the second. */ static int state_compare (const void *a, const void *b) { struct GNUNET_REGEX_State **s1; struct GNUNET_REGEX_State **s2; s1 = (struct GNUNET_REGEX_State **) a; s2 = (struct GNUNET_REGEX_State **) b; return (*s1)->id - (*s2)->id; } /** * Get all edges leaving state 's'. * * @param s state. * @param edges all edges leaving 's'. * * @return number of edges. */ static unsigned int state_get_edges (struct GNUNET_REGEX_State *s, struct GNUNET_REGEX_Edge *edges) { struct Transition *t; unsigned int count; if (NULL == s) return 0; count = 0; for (t = s->transitions_head; NULL != t; t = t->next) { if (NULL != t->to_state) { edges[count].label = &t->label; edges[count].destination = t->to_state->hash; count++; } } return count; } /** * Compare to state sets by comparing the id's of the states that are contained * in each set. Both sets are expected to be sorted by id! * * @param sset1 first state set * @param sset2 second state set * * @return an integer less than, equal to, or greater than zero * if the first argument is considered to be respectively * less than, equal to, or greater than the second. */ static int state_set_compare (struct GNUNET_REGEX_StateSet *sset1, struct GNUNET_REGEX_StateSet *sset2) { int result; unsigned int i; if (NULL == sset1 || NULL == sset2) return 1; result = sset1->len - sset2->len; for (i = 0; i < sset1->len; i++) { if (0 != result) break; result = state_compare (&sset1->states[i], &sset2->states[i]); } return result; } /** * Clears the given StateSet 'set' * * @param set set to be cleared */ static void state_set_clear (struct GNUNET_REGEX_StateSet *set) { if (NULL != set) { GNUNET_free_non_null (set->states); GNUNET_free (set); } } /** * Clears an automaton fragment. Does not destroy the states inside the * automaton. * * @param a automaton to be cleared */ static void automaton_fragment_clear (struct GNUNET_REGEX_Automaton *a) { if (NULL == a) return; a->start = NULL; a->end = NULL; a->states_head = NULL; a->states_tail = NULL; a->state_count = 0; GNUNET_free (a); } /** * Frees the memory used by State 's' * * @param s state that should be destroyed */ static void automaton_destroy_state (struct GNUNET_REGEX_State *s) { struct Transition *t; struct Transition *next_t; if (NULL == s) return; GNUNET_free_non_null (s->name); GNUNET_free_non_null (s->proof); for (t = s->transitions_head; NULL != t; t = next_t) { next_t = t->next; GNUNET_CONTAINER_DLL_remove (s->transitions_head, s->transitions_tail, t); GNUNET_free (t); } state_set_clear (s->nfa_set); GNUNET_free (s); } /** * Remove a state from the given automaton 'a'. Always use this function when * altering the states of an automaton. Will also remove all transitions leading * to this state, before destroying it. * * @param a automaton * @param s state to remove */ static void automaton_remove_state (struct GNUNET_REGEX_Automaton *a, struct GNUNET_REGEX_State *s) { struct GNUNET_REGEX_State *ss; struct GNUNET_REGEX_State *s_check; struct Transition *t_check; if (NULL == a || NULL == s) return; // remove state ss = s; GNUNET_CONTAINER_DLL_remove (a->states_head, a->states_tail, s); a->state_count--; // remove all transitions leading to this state for (s_check = a->states_head; NULL != s_check; s_check = s_check->next) { for (t_check = s_check->transitions_head; NULL != t_check; t_check = t_check->next) { if (t_check->to_state == ss) { GNUNET_CONTAINER_DLL_remove (s_check->transitions_head, s_check->transitions_tail, t_check); s_check->transition_count--; } } } automaton_destroy_state (ss); } /** * Merge two states into one. Will merge 's1' and 's2' into 's1' and destroy * 's2'. * * @param ctx context * @param a automaton * @param s1 first state * @param s2 second state, will be destroyed */ static void automaton_merge_states (struct GNUNET_REGEX_Context *ctx, struct GNUNET_REGEX_Automaton *a, struct GNUNET_REGEX_State *s1, struct GNUNET_REGEX_State *s2) { struct GNUNET_REGEX_State *s_check; struct Transition *t_check; char *new_name; GNUNET_assert (NULL != ctx && NULL != a && NULL != s1 && NULL != s2); if (s1 == s2) return; // 1. Make all transitions pointing to s2 point to s1 for (s_check = a->states_head; NULL != s_check; s_check = s_check->next) { for (t_check = s_check->transitions_head; NULL != t_check; t_check = t_check->next) { if (s2 == t_check->to_state) t_check->to_state = s1; } } // 2. Add all transitions from s2 to sX to s1 for (t_check = s2->transitions_head; NULL != t_check; t_check = t_check->next) { if (t_check->to_state != s1) state_add_transition (ctx, s1, t_check->label, t_check->to_state); } // 3. Rename s1 to {s1,s2} new_name = s1->name; GNUNET_asprintf (&s1->name, "{%s,%s}", new_name, s2->name); GNUNET_free (new_name); // remove state GNUNET_CONTAINER_DLL_remove (a->states_head, a->states_tail, s2); a->state_count--; automaton_destroy_state (s2); } /** * Add a state to the automaton 'a', always use this function to alter the * states DLL of the automaton. * * @param a automaton to add the state to * @param s state that should be added */ static void automaton_add_state (struct GNUNET_REGEX_Automaton *a, struct GNUNET_REGEX_State *s) { GNUNET_CONTAINER_DLL_insert (a->states_head, a->states_tail, s); a->state_count++; } /** * Function that is called with each state, when traversing an automaton. * * @param cls closure. * @param count current count of the state, from 0 to a->state_count -1. * @param s state. */ typedef void (*GNUNET_REGEX_traverse_action) (void *cls, unsigned int count, struct GNUNET_REGEX_State * s); /** * Depth-first traversal of all states that are reachable from state 's'. Expects the states to * be unmarked (s->marked == GNUNET_NO). Performs 'action' on each visited * state. * * @param s start state. * @param count current count of the state. * @param action action to be performed on each state. * @param action_cls closure for action */ static void automaton_state_traverse (struct GNUNET_REGEX_State *s, unsigned int *count, GNUNET_REGEX_traverse_action action, void *action_cls) { struct Transition *t; if (GNUNET_NO != s->marked) return; s->marked = GNUNET_YES; if (NULL != action) action (action_cls, *count, s); (*count)++; for (t = s->transitions_head; NULL != t; t = t->next) automaton_state_traverse (t->to_state, count, action, action_cls); } /** * Traverses the given automaton from it's start state, visiting all reachable * states and calling 'action' on each one of them. * * @param a automaton. * @param action action to be performed on each state. * @param action_cls closure for action */ static void automaton_traverse (struct GNUNET_REGEX_Automaton *a, GNUNET_REGEX_traverse_action action, void *action_cls) { unsigned int count; struct GNUNET_REGEX_State *s; for (s = a->states_head; NULL != s; s = s->next) s->marked = GNUNET_NO; count = 0; automaton_state_traverse (a->start, &count, action, action_cls); } /** * Check if the given string 'str' needs parentheses around it when * using it to generate a regex. * * Currently only tests for first and last characters being '()' respectively. * FIXME: What about "(ab)|(cd)"? * * @param str string * * @return GNUNET_YES if parentheses are needed, GNUNET_NO otherwise */ static int needs_parentheses (const char *str) { size_t slen; const char *op; const char *cl; const char *pos; unsigned int cnt; if ((NULL == str) || ((slen = strlen (str)) < 2)) return GNUNET_NO; if ('(' != str[0]) return GNUNET_YES; cnt = 1; pos = &str[1]; while (cnt > 0) { cl = strchr (pos, ')'); if (NULL == cl) { GNUNET_break (0); return GNUNET_YES; } op = strchr (pos, '('); if ((NULL != op) && (op < cl)) { cnt++; pos = op + 1; continue; } /* got ')' first */ cnt--; pos = cl + 1; } return (*pos == '\0') ? GNUNET_NO : GNUNET_YES; } /** * Remove parentheses surrounding string 'str'. * Example: "(a)" becomes "a". * You need to GNUNET_free the returned string. * * Currently only tests for first and last characters being '()' respectively. * FIXME: What about "(ab)|(cd)"? * * @param str string, free'd or re-used by this function, can be NULL * * @return string without surrounding parentheses, string 'str' if no preceding * epsilon could be found, NULL if 'str' was NULL */ static char * remove_parentheses (char *str) { size_t slen; if ((NULL == str) || ('(' != str[0]) || (str[(slen = strlen (str)) - 1] != ')')) return str; memmove (str, &str[1], slen - 2); str[slen - 2] = '\0'; return str; } /** * Check if the string 'str' starts with an epsilon (empty string). * Example: "(|a)" is starting with an epsilon. * * @param str string to test * * @return 0 if str has no epsilon, 1 if str starts with '(|' and ends with ')' */ static int has_epsilon (const char *str) { return (NULL != str) && ('(' == str[0]) && ('|' == str[1]) && (')' == str[strlen (str) - 1]); } /** * Remove an epsilon from the string str. Where epsilon is an empty string * Example: str = "(|a|b|c)", result: "a|b|c" * The returned string needs to be freed. * * @param str string * * @return string without preceding epsilon, string 'str' if no preceding epsilon * could be found, NULL if 'str' was NULL */ static char * remove_epsilon (const char *str) { size_t len; if (NULL == str) return NULL; if (('(' == str[0]) && ('|' == str[1])) { len = strlen (str); if (')' == str[len - 1]) return GNUNET_strndup (&str[2], len - 3); } return GNUNET_strdup (str); } /** * Compare 'str1', starting from position 'k', with whole 'str2' * * @param str1 first string to compare, starting from position 'k' * @param str2 second string for comparison * @param k starting position in 'str1' * * @return -1 if any of the strings is NULL, 0 if equal, non 0 otherwise */ static int strkcmp (const char *str1, const char *str2, size_t k) { if ((NULL == str1) || (NULL == str2) || (strlen (str1) < k)) return -1; return strcmp (&str1[k], str2); } /** * Compare two strings for equality. If either is NULL (or if both are * NULL), they are not equal. * * @param str1 first string for comparison. * @param str2 second string for comparison. * * @return 0 if the strings are the same, 1 or -1 if not */ static int nullstrcmp (const char *str1, const char *str2) { if ((NULL == str1) || (NULL == str2)) return -1; return strcmp (str1, str2); } /** * Helper function used as 'action' in 'automaton_traverse' function to create * the depth-first numbering of the states. * * @param cls states array. * @param count current state counter. * @param s current state. */ static void number_states (void *cls, unsigned int count, struct GNUNET_REGEX_State *s) { struct GNUNET_REGEX_State **states = cls; s->proof_id = count; states[count] = s; } /** * create proofs for all states in the given automaton. Implementation of the * algorithm descriped in chapter 3.2.1 of "Automata Theory, Languages, and * Computation 3rd Edition" by Hopcroft, Motwani and Ullman. * * @param a automaton. */ static void automaton_create_proofs (struct GNUNET_REGEX_Automaton *a) { unsigned int n = a->state_count; struct GNUNET_REGEX_State *states[n]; char *R_last[n][n]; char *R_cur[n][n]; struct Transition *t; char *R_cur_l; char *R_cur_r; char *temp_a; char *temp_b; char *R_temp_ij; char *R_temp_ik; char *R_temp_kj; char *R_temp_kk; char *complete_regex; unsigned int i; unsigned int j; unsigned int k; unsigned int cnt; int eps_check; int ij_ik_cmp; int ij_kj_cmp; //int ik_kj_cmp; int ik_kk_cmp; int kk_kj_cmp; int clean_ik_kk_cmp; int clean_kk_kj_cmp; size_t length; size_t length_l; size_t length_r; /* create depth-first numbering of the states, initializes 'state' */ automaton_traverse (a, &number_states, states); /* Compute regular expressions of length "1" between each pair of states */ for (i = 0; i < n; i++) { for (j = 0; j < n; j++) { R_cur[i][j] = NULL; R_last[i][j] = NULL; } for (t = states[i]->transitions_head; NULL != t; t = t->next) { j = t->to_state->proof_id; if (NULL == R_last[i][j]) GNUNET_asprintf (&R_last[i][j], "%c", t->label); else { temp_a = R_last[i][j]; GNUNET_asprintf (&R_last[i][j], "%s|%c", R_last[i][j], t->label); GNUNET_free (temp_a); } } if (NULL == R_last[i][i]) GNUNET_asprintf (&R_last[i][i], ""); else { temp_a = R_last[i][i]; GNUNET_asprintf (&R_last[i][i], "(|%s)", R_last[i][i]); GNUNET_free (temp_a); } } for (i = 0; i < n; i++) for (j = 0; j < n; j++) if (needs_parentheses (R_last[i][j])) { temp_a = R_last[i][j]; GNUNET_asprintf (&R_last[i][j], "(%s)", R_last[i][j]); GNUNET_free (temp_a); } // TODO: clean up and fix the induction part /* Compute regular expressions of length "k" between each pair of states per induction */ for (k = 0; k < n; k++) { for (i = 0; i < n; i++) { for (j = 0; j < n; j++) { // Basis for the recursion: // $R^{(k)}_{ij} = R^{(k-1)}_{ij} | R^{(k-1)}_{ik} ( R^{(k-1)}_{kk} )^* R^{(k-1)}_{kj} // R_last == R^{(k-1)}, R_cur == R^{(k)} // With: R_cur[i][j] = R_cur_l | R_cur_r // R_cur_l == R^{(k-1)}_{ij} // R_cur_r == R^{(k-1)}_{ik} ( R^{(k-1)}_{kk} )^* R^{(k-1)}_{kj} if ((NULL == R_last[i][j]) && ((NULL == R_last[i][k]) || (NULL == R_last[k][k]) || /* technically cannot happen, but looks saner */ (NULL == R_last[k][j]))) { /* R^{(k)}_{ij} = N | N */ /* R_cur[i][j] is already NULL */ continue; } if ((NULL == R_last[i][k]) || (NULL == R_last[k][k]) || /* technically cannot happen, but looks saner */ (NULL == R_last[k][j])) { /* R^{(k)}_{ij} = R^{(k-1)}_{ij} | N */ R_cur[i][j] = GNUNET_strdup (R_last[i][j]); continue; } // $R^{(k)}_{ij} = N | R^{(k-1)}_{ik} ( R^{(k-1)}_{kk} )^* R^{(k-1)}_{kj} OR // $R^{(k)}_{ij} = R^{(k-1)}_{ij} | R^{(k-1)}_{ik} ( R^{(k-1)}_{kk} )^* R^{(k-1)}_{kj} R_cur[i][j] = NULL; R_cur_r = NULL; R_cur_l = NULL; // cache results from strcmp, we might need these many times ij_kj_cmp = nullstrcmp (R_last[i][j], R_last[k][j]); ij_ik_cmp = nullstrcmp (R_last[i][j], R_last[i][k]); ik_kk_cmp = nullstrcmp (R_last[i][k], R_last[k][k]); //ik_kj_cmp = nullstrcmp (R_last[i][k], R_last[k][j]); kk_kj_cmp = nullstrcmp (R_last[k][k], R_last[k][j]); // Assign R_temp_(ik|kk|kj) to R_last[][] and remove epsilon as well // as parentheses, so we can better compare the contents R_temp_ik = remove_parentheses (remove_epsilon (R_last[i][k])); R_temp_kk = remove_parentheses (remove_epsilon (R_last[k][k])); R_temp_kj = remove_parentheses (remove_epsilon (R_last[k][j])); clean_ik_kk_cmp = nullstrcmp (R_last[i][k], R_temp_kk); clean_kk_kj_cmp = nullstrcmp (R_temp_kk, R_last[k][j]); // construct R_cur_l (and, if necessary R_cur_r) if (NULL != R_last[i][j]) { // Assign R_temp_ij to R_last[i][j] and remove epsilon as well // as parentheses, so we can better compare the contents R_temp_ij = remove_parentheses (remove_epsilon (R_last[i][j])); if (0 == strcmp (R_temp_ij, R_temp_ik) && 0 == strcmp (R_temp_ik, R_temp_kk) && 0 == strcmp (R_temp_kk, R_temp_kj)) { if (0 == strlen (R_temp_ij)) { R_cur_r = GNUNET_strdup (""); } else if ((0 == strncmp (R_last[i][j], "(|", 2)) || (0 == strncmp (R_last[i][k], "(|", 2) && 0 == strncmp (R_last[k][j], "(|", 2))) { // a|(e|a)a*(e|a) = a* // a|(e|a)(e|a)*(e|a) = a* // (e|a)|aa*a = a* // (e|a)|aa*(e|a) = a* // (e|a)|(e|a)a*a = a* // (e|a)|(e|a)a*(e|a) = a* // (e|a)|(e|a)(e|a)*(e|a) = a* if (GNUNET_YES == needs_parentheses (R_temp_ij)) GNUNET_asprintf (&R_cur_r, "(%s)*", R_temp_ij); else GNUNET_asprintf (&R_cur_r, "%s*", R_temp_ij); } else { // a|aa*a = a+ // a|(e|a)a*a = a+ // a|aa*(e|a) = a+ // a|(e|a)(e|a)*a = a+ // a|a(e|a)*(e|a) = a+ if (GNUNET_YES == needs_parentheses (R_temp_ij)) GNUNET_asprintf (&R_cur_r, "(%s)+", R_temp_ij); else GNUNET_asprintf (&R_cur_r, "%s+", R_temp_ij); } } else if (0 == ij_ik_cmp && 0 == clean_kk_kj_cmp && 0 != clean_ik_kk_cmp) { // a|ab*b = ab* if (strlen (R_last[k][k]) < 1) R_cur_r = GNUNET_strdup (R_last[i][j]); else if (GNUNET_YES == needs_parentheses (R_temp_kk)) GNUNET_asprintf (&R_cur_r, "%s(%s)*", R_last[i][j], R_temp_kk); else GNUNET_asprintf (&R_cur_r, "%s%s*", R_last[i][j], R_last[k][k]); R_cur_l = NULL; } else if (0 == ij_kj_cmp && 0 == clean_ik_kk_cmp && 0 != clean_kk_kj_cmp) { // a|bb*a = b*a if (strlen (R_last[k][k]) < 1) R_cur_r = GNUNET_strdup (R_last[k][j]); else if (GNUNET_YES == needs_parentheses (R_temp_kk)) GNUNET_asprintf (&R_cur_r, "(%s)*%s", R_temp_kk, R_last[k][j]); else GNUNET_asprintf (&R_cur_r, "%s*%s", R_temp_kk, R_last[k][j]); R_cur_l = NULL; } else if (0 == ij_ik_cmp && 0 == kk_kj_cmp && !has_epsilon (R_last[i][j]) && has_epsilon (R_last[k][k])) { // a|a(e|b)*(e|b) = a|ab* = a|a|ab|abb|abbb|... = ab* if (needs_parentheses (R_temp_kk)) GNUNET_asprintf (&R_cur_r, "%s(%s)*", R_last[i][j], R_temp_kk); else GNUNET_asprintf (&R_cur_r, "%s%s*", R_last[i][j], R_temp_kk); R_cur_l = NULL; } else if (0 == ij_kj_cmp && 0 == ik_kk_cmp && !has_epsilon (R_last[i][j]) && has_epsilon (R_last[k][k])) { // a|(e|b)(e|b)*a = a|b*a = a|a|ba|bba|bbba|... = b*a if (needs_parentheses (R_temp_kk)) GNUNET_asprintf (&R_cur_r, "(%s)*%s", R_temp_kk, R_last[i][j]); else GNUNET_asprintf (&R_cur_r, "%s*%s", R_temp_kk, R_last[i][j]); R_cur_l = NULL; } else { temp_a = (NULL == R_last[i][j]) ? NULL : GNUNET_strdup (R_last[i][j]); temp_a = remove_parentheses (temp_a); R_cur_l = temp_a; } GNUNET_free_non_null (R_temp_ij); } else { // we have no left side R_cur_l = NULL; } // construct R_cur_r, if not already constructed if (NULL == R_cur_r) { length = strlen (R_temp_kk) - strlen (R_last[i][k]); // a(ba)*bx = (ab)+x if (length > 0 && NULL != R_last[k][k] && 0 < strlen (R_last[k][k]) && NULL != R_last[k][j] && 0 < strlen (R_last[k][j]) && NULL != R_last[i][k] && 0 < strlen (R_last[i][k]) && 0 == strkcmp (R_temp_kk, R_last[i][k], length) && 0 == strncmp (R_temp_kk, R_last[k][j], length)) { temp_a = GNUNET_malloc (length + 1); temp_b = GNUNET_malloc ((strlen (R_last[k][j]) - length) + 1); length_l = 0; length_r = 0; for (cnt = 0; cnt < strlen (R_last[k][j]); cnt++) { if (cnt < length) { temp_a[length_l] = R_last[k][j][cnt]; length_l++; } else { temp_b[length_r] = R_last[k][j][cnt]; length_r++; } } temp_a[length_l] = '\0'; temp_b[length_r] = '\0'; // e|(ab)+ = (ab)* if (NULL != R_cur_l && 0 == strlen (R_cur_l) && 0 == strlen (temp_b)) { GNUNET_asprintf (&R_cur_r, "(%s%s)*", R_last[i][k], temp_a); GNUNET_free (R_cur_l); R_cur_l = NULL; } else { GNUNET_asprintf (&R_cur_r, "(%s%s)+%s", R_last[i][k], temp_a, temp_b); } GNUNET_free (temp_a); GNUNET_free (temp_b); } else if (0 == strcmp (R_temp_ik, R_temp_kk) && 0 == strcmp (R_temp_kk, R_temp_kj)) { // (e|a)a*(e|a) = a* // (e|a)(e|a)*(e|a) = a* if (has_epsilon (R_last[i][k]) && has_epsilon (R_last[k][j])) { if (needs_parentheses (R_temp_kk)) GNUNET_asprintf (&R_cur_r, "(%s)*", R_temp_kk); else GNUNET_asprintf (&R_cur_r, "%s*", R_temp_kk); } // aa*a = a+a else if (0 == clean_ik_kk_cmp && 0 == clean_kk_kj_cmp && !has_epsilon (R_last[i][k])) { if (needs_parentheses (R_temp_kk)) GNUNET_asprintf (&R_cur_r, "(%s)+%s", R_temp_kk, R_temp_kk); else GNUNET_asprintf (&R_cur_r, "(%s)+%s", R_temp_kk, R_temp_kk); } // (e|a)a*a = a+ // aa*(e|a) = a+ // a(e|a)*(e|a) = a+ // (e|a)a*a = a+ else { eps_check = (has_epsilon (R_last[i][k]) + has_epsilon (R_last[k][k]) + has_epsilon (R_last[k][j])); if (eps_check == 1) { if (needs_parentheses (R_temp_kk)) GNUNET_asprintf (&R_cur_r, "(%s)+", R_temp_kk); else GNUNET_asprintf (&R_cur_r, "%s+", R_temp_kk); } } } // aa*b = a+b // (e|a)(e|a)*b = a*b else if (0 == strcmp (R_temp_ik, R_temp_kk)) { if (has_epsilon (R_last[i][k])) { if (needs_parentheses (R_temp_kk)) GNUNET_asprintf (&R_cur_r, "(%s)*%s", R_temp_kk, R_last[k][j]); else GNUNET_asprintf (&R_cur_r, "%s*%s", R_temp_kk, R_last[k][j]); } else { if (needs_parentheses (R_temp_kk)) GNUNET_asprintf (&R_cur_r, "(%s)+%s", R_temp_kk, R_last[k][j]); else GNUNET_asprintf (&R_cur_r, "%s+%s", R_temp_kk, R_last[k][j]); } } // ba*a = ba+ // b(e|a)*(e|a) = ba* else if (0 == strcmp (R_temp_kk, R_temp_kj)) { if (has_epsilon (R_last[k][j])) { if (needs_parentheses (R_temp_kk)) GNUNET_asprintf (&R_cur_r, "%s(%s)*", R_last[i][k], R_temp_kk); else GNUNET_asprintf (&R_cur_r, "%s%s*", R_last[i][k], R_temp_kk); } else { if (needs_parentheses (R_temp_kk)) GNUNET_asprintf (&R_cur_r, "(%s)+%s", R_last[i][k], R_temp_kk); else GNUNET_asprintf (&R_cur_r, "%s+%s", R_last[i][k], R_temp_kk); } } else { if (strlen (R_temp_kk) > 0) { if (needs_parentheses (R_temp_kk)) { GNUNET_asprintf (&R_cur_r, "%s(%s)*%s", R_last[i][k], R_temp_kk, R_last[k][j]); } else { GNUNET_asprintf (&R_cur_r, "%s%s*%s", R_last[i][k], R_temp_kk, R_last[k][j]); } } else { GNUNET_asprintf (&R_cur_r, "%s%s", R_last[i][k], R_last[k][j]); } } } /* GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "R_cur_l: %s\n", R_cur_l); */ /* GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "R_cur_r: %s\n", R_cur_r); */ // putting it all together if (NULL != R_cur_l && NULL != R_cur_r) { // a|a = a if (0 == strcmp (R_cur_l, R_cur_r)) { R_cur[i][j] = GNUNET_strdup (R_cur_l); } // R_cur_l | R_cur_r else { GNUNET_asprintf (&R_cur[i][j], "(%s|%s)", R_cur_l, R_cur_r); } } else if (NULL != R_cur_l) { R_cur[i][j] = GNUNET_strdup (R_cur_l); } else if (NULL != R_cur_r) { R_cur[i][j] = GNUNET_strdup (R_cur_r); } else { R_cur[i][j] = NULL; } GNUNET_free_non_null (R_cur_l); GNUNET_free_non_null (R_cur_r); GNUNET_free_non_null (R_temp_ik); GNUNET_free_non_null (R_temp_kk); GNUNET_free_non_null (R_temp_kj); } } // set R_last = R_cur for (i = 0; i < n; i++) { for (j = 0; j < n; j++) { GNUNET_free_non_null (R_last[i][j]); R_last[i][j] = R_cur[i][j]; R_cur[i][j] = NULL; } } } // assign proofs and hashes for (i = 0; i < n; i++) { if (NULL != R_last[a->start->proof_id][i]) { states[i]->proof = GNUNET_strdup (R_last[a->start->proof_id][i]); GNUNET_CRYPTO_hash (states[i]->proof, strlen (states[i]->proof), &states[i]->hash); } } // complete regex for whole DFA: union of all pairs (start state/accepting state(s)). complete_regex = NULL; for (i = 0; i < n; i++) { if (states[i]->accepting) { if (NULL == complete_regex && 0 < strlen (R_last[a->start->proof_id][i])) GNUNET_asprintf (&complete_regex, "%s", R_last[a->start->proof_id][i]); else if (NULL != R_last[a->start->proof_id][i] && 0 < strlen (R_last[a->start->proof_id][i])) { temp_a = complete_regex; GNUNET_asprintf (&complete_regex, "%s|%s", complete_regex, R_last[a->start->proof_id][i]); GNUNET_free (temp_a); } } } a->canonical_regex = complete_regex; GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "---------------------------------------------\n"); GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "Regex: %s\n", a->regex); GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "Complete Regex: %s\n", complete_regex); GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "---------------------------------------------\n"); // cleanup for (i = 0; i < n; i++) { for (j = 0; j < n; j++) GNUNET_free_non_null (R_last[i][j]); } } /** * Creates a new DFA state based on a set of NFA states. Needs to be freed using * automaton_destroy_state. * * @param ctx context * @param nfa_states set of NFA states on which the DFA should be based on * * @return new DFA state */ static struct GNUNET_REGEX_State * dfa_state_create (struct GNUNET_REGEX_Context *ctx, struct GNUNET_REGEX_StateSet *nfa_states) { struct GNUNET_REGEX_State *s; char *name; int len = 0; struct GNUNET_REGEX_State *cstate; struct Transition *ctran; int insert = 1; struct Transition *t; unsigned int i; s = GNUNET_malloc (sizeof (struct GNUNET_REGEX_State)); s->id = ctx->state_id++; s->accepting = 0; s->marked = 0; s->name = NULL; s->scc_id = 0; s->index = -1; s->lowlink = -1; s->contained = 0; s->proof = NULL; if (NULL == nfa_states) { GNUNET_asprintf (&s->name, "s%i", s->id); return s; } s->nfa_set = nfa_states; if (nfa_states->len < 1) return s; // Create a name based on 'sset' s->name = GNUNET_malloc (sizeof (char) * 2); strcat (s->name, "{"); name = NULL; for (i = 0; i < nfa_states->len; i++) { cstate = nfa_states->states[i]; GNUNET_asprintf (&name, "%i,", cstate->id); if (NULL != name) { len = strlen (s->name) + strlen (name) + 1; s->name = GNUNET_realloc (s->name, len); strcat (s->name, name); GNUNET_free (name); name = NULL; } // Add a transition for each distinct label to NULL state for (ctran = cstate->transitions_head; NULL != ctran; ctran = ctran->next) { if (0 != ctran->label) { insert = 1; for (t = s->transitions_head; NULL != t; t = t->next) { if (t->label == ctran->label) { insert = 0; break; } } if (insert) state_add_transition (ctx, s, ctran->label, NULL); } } // If the nfa_states contain an accepting state, the new dfa state is also // accepting if (cstate->accepting) s->accepting = 1; } s->name[strlen (s->name) - 1] = '}'; return s; } /** * Move from the given state 's' to the next state on transition 'label' * * @param s starting state * @param label edge label to follow * * @return new state or NULL, if transition on label not possible */ static struct GNUNET_REGEX_State * dfa_move (struct GNUNET_REGEX_State *s, const char label) { struct Transition *t; struct GNUNET_REGEX_State *new_s; if (NULL == s) return NULL; new_s = NULL; for (t = s->transitions_head; NULL != t; t = t->next) { if (label == t->label) { new_s = t->to_state; break; } } return new_s; } /** * Remove all unreachable states from DFA 'a'. Unreachable states are those * states that are not reachable from the starting state. * * @param a DFA automaton */ static void dfa_remove_unreachable_states (struct GNUNET_REGEX_Automaton *a) { struct GNUNET_REGEX_State *s; struct GNUNET_REGEX_State *s_next; // 1. unmark all states for (s = a->states_head; NULL != s; s = s->next) s->marked = GNUNET_NO; // 2. traverse dfa from start state and mark all visited states automaton_traverse (a, NULL, NULL); // 3. delete all states that were not visited for (s = a->states_head; NULL != s; s = s_next) { s_next = s->next; if (GNUNET_NO == s->marked) automaton_remove_state (a, s); } } /** * Remove all dead states from the DFA 'a'. Dead states are those states that do * not transition to any other state but themselfes. * * @param a DFA automaton */ static void dfa_remove_dead_states (struct GNUNET_REGEX_Automaton *a) { struct GNUNET_REGEX_State *s; struct Transition *t; int dead; GNUNET_assert (DFA == a->type); for (s = a->states_head; NULL != s; s = s->next) { if (s->accepting) continue; dead = 1; for (t = s->transitions_head; NULL != t; t = t->next) { if (NULL != t->to_state && t->to_state != s) { dead = 0; break; } } if (0 == dead) continue; // state s is dead, remove it automaton_remove_state (a, s); } } /** * Merge all non distinguishable states in the DFA 'a' * * @param ctx context * @param a DFA automaton */ static void dfa_merge_nondistinguishable_states (struct GNUNET_REGEX_Context *ctx, struct GNUNET_REGEX_Automaton *a) { unsigned int i; int table[a->state_count][a->state_count]; struct GNUNET_REGEX_State *s1; struct GNUNET_REGEX_State *s2; struct Transition *t1; struct Transition *t2; struct GNUNET_REGEX_State *s1_next; struct GNUNET_REGEX_State *s2_next; int change; unsigned int num_equal_edges; for (i = 0, s1 = a->states_head; i < a->state_count && NULL != s1; i++, s1 = s1->next) { s1->marked = i; } // Mark all pairs of accepting/!accepting states for (s1 = a->states_head; NULL != s1; s1 = s1->next) { for (s2 = a->states_head; NULL != s2; s2 = s2->next) { table[s1->marked][s2->marked] = 0; if ((s1->accepting && !s2->accepting) || (!s1->accepting && s2->accepting)) { table[s1->marked][s2->marked] = 1; } } } // Find all equal states change = 1; while (0 != change) { change = 0; for (s1 = a->states_head; NULL != s1; s1 = s1->next) { for (s2 = a->states_head; NULL != s2 && s1 != s2; s2 = s2->next) { if (0 != table[s1->marked][s2->marked]) continue; num_equal_edges = 0; for (t1 = s1->transitions_head; NULL != t1; t1 = t1->next) { for (t2 = s2->transitions_head; NULL != t2; t2 = t2->next) { if (t1->label == t2->label) { num_equal_edges++; if (0 != table[t1->to_state->marked][t2->to_state->marked] || 0 != table[t2->to_state->marked][t1->to_state->marked]) { table[s1->marked][s2->marked] = t1->label != 0 ? t1->label : 1; change = 1; } } } } if (num_equal_edges != s1->transition_count || num_equal_edges != s2->transition_count) { // Make sure ALL edges of possible equal states are the same table[s1->marked][s2->marked] = -2; } } } } // Merge states that are equal for (s1 = a->states_head; NULL != s1; s1 = s1_next) { s1_next = s1->next; for (s2 = a->states_head; NULL != s2 && s1 != s2; s2 = s2_next) { s2_next = s2->next; if (table[s1->marked][s2->marked] == 0) automaton_merge_states (ctx, a, s1, s2); } } } /** * Minimize the given DFA 'a' by removing all unreachable states, removing all * dead states and merging all non distinguishable states * * @param ctx context * @param a DFA automaton */ static void dfa_minimize (struct GNUNET_REGEX_Context *ctx, struct GNUNET_REGEX_Automaton *a) { if (NULL == a) return; GNUNET_assert (DFA == a->type); // 1. remove unreachable states dfa_remove_unreachable_states (a); // 2. remove dead states dfa_remove_dead_states (a); // 3. Merge nondistinguishable states dfa_merge_nondistinguishable_states (ctx, a); } /** * Creates a new NFA fragment. Needs to be cleared using * automaton_fragment_clear. * * @param start starting state * @param end end state * * @return new NFA fragment */ static struct GNUNET_REGEX_Automaton * nfa_fragment_create (struct GNUNET_REGEX_State *start, struct GNUNET_REGEX_State *end) { struct GNUNET_REGEX_Automaton *n; n = GNUNET_malloc (sizeof (struct GNUNET_REGEX_Automaton)); n->type = NFA; n->start = NULL; n->end = NULL; if (NULL == start && NULL == end) return n; automaton_add_state (n, end); automaton_add_state (n, start); n->start = start; n->end = end; return n; } /** * Adds a list of states to the given automaton 'n'. * * @param n automaton to which the states should be added * @param states_head head of the DLL of states * @param states_tail tail of the DLL of states */ static void nfa_add_states (struct GNUNET_REGEX_Automaton *n, struct GNUNET_REGEX_State *states_head, struct GNUNET_REGEX_State *states_tail) { struct GNUNET_REGEX_State *s; if (NULL == n || NULL == states_head) { GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "Could not add states\n"); return; } if (NULL == n->states_head) { n->states_head = states_head; n->states_tail = states_tail; return; } if (NULL != states_head) { n->states_tail->next = states_head; n->states_tail = states_tail; } for (s = states_head; NULL != s; s = s->next) n->state_count++; } /** * Creates a new NFA state. Needs to be freed using automaton_destroy_state. * * @param ctx context * @param accepting is it an accepting state or not * * @return new NFA state */ static struct GNUNET_REGEX_State * nfa_state_create (struct GNUNET_REGEX_Context *ctx, int accepting) { struct GNUNET_REGEX_State *s; s = GNUNET_malloc (sizeof (struct GNUNET_REGEX_State)); s->id = ctx->state_id++; s->accepting = accepting; s->marked = 0; s->contained = 0; s->index = -1; s->lowlink = -1; s->scc_id = 0; s->name = NULL; GNUNET_asprintf (&s->name, "s%i", s->id); return s; } /** * Calculates the NFA closure set for the given state. * * @param nfa the NFA containing 's' * @param s starting point state * @param label transitioning label on which to base the closure on, * pass 0 for epsilon transition * * @return sorted nfa closure on 'label' (epsilon closure if 'label' is 0) */ static struct GNUNET_REGEX_StateSet * nfa_closure_create (struct GNUNET_REGEX_Automaton *nfa, struct GNUNET_REGEX_State *s, const char label) { struct GNUNET_REGEX_StateSet *cls; struct GNUNET_REGEX_StateSet *cls_check; struct GNUNET_REGEX_State *clsstate; struct GNUNET_REGEX_State *currentstate; struct Transition *ctran; if (NULL == s) return NULL; cls = GNUNET_malloc (sizeof (struct GNUNET_REGEX_StateSet)); cls_check = GNUNET_malloc (sizeof (struct GNUNET_REGEX_StateSet)); for (clsstate = nfa->states_head; NULL != clsstate; clsstate = clsstate->next) clsstate->contained = 0; // Add start state to closure only for epsilon closure if (0 == label) GNUNET_array_append (cls->states, cls->len, s); GNUNET_array_append (cls_check->states, cls_check->len, s); while (cls_check->len > 0) { currentstate = cls_check->states[cls_check->len - 1]; GNUNET_array_grow (cls_check->states, cls_check->len, cls_check->len - 1); for (ctran = currentstate->transitions_head; NULL != ctran; ctran = ctran->next) { if (NULL != ctran->to_state && label == ctran->label) { clsstate = ctran->to_state; if (NULL != clsstate && 0 == clsstate->contained) { GNUNET_array_append (cls->states, cls->len, clsstate); GNUNET_array_append (cls_check->states, cls_check->len, clsstate); clsstate->contained = 1; } } } } GNUNET_assert (0 == cls_check->len); GNUNET_free (cls_check); // sort the states if (cls->len > 1) qsort (cls->states, cls->len, sizeof (struct GNUNET_REGEX_State *), state_compare); return cls; } /** * Calculates the closure set for the given set of states. * * @param nfa the NFA containing 's' * @param states list of states on which to base the closure on * @param label transitioning label for which to base the closure on, * pass 0 for epsilon transition * * @return sorted nfa closure on 'label' (epsilon closure if 'label' is 0) */ static struct GNUNET_REGEX_StateSet * nfa_closure_set_create (struct GNUNET_REGEX_Automaton *nfa, struct GNUNET_REGEX_StateSet *states, const char label) { struct GNUNET_REGEX_State *s; struct GNUNET_REGEX_StateSet *sset; struct GNUNET_REGEX_StateSet *cls; unsigned int i; unsigned int j; unsigned int k; unsigned int contains; if (NULL == states) return NULL; cls = GNUNET_malloc (sizeof (struct GNUNET_REGEX_StateSet)); for (i = 0; i < states->len; i++) { s = states->states[i]; sset = nfa_closure_create (nfa, s, label); for (j = 0; j < sset->len; j++) { contains = 0; for (k = 0; k < cls->len; k++) { if (sset->states[j]->id == cls->states[k]->id) { contains = 1; break; } } if (!contains) GNUNET_array_append (cls->states, cls->len, sset->states[j]); } state_set_clear (sset); } if (cls->len > 1) qsort (cls->states, cls->len, sizeof (struct GNUNET_REGEX_State *), state_compare); return cls; } /** * Pops two NFA fragments (a, b) from the stack and concatenates them (ab) * * @param ctx context */ static void nfa_add_concatenation (struct GNUNET_REGEX_Context *ctx) { struct GNUNET_REGEX_Automaton *a; struct GNUNET_REGEX_Automaton *b; struct GNUNET_REGEX_Automaton *new; b = ctx->stack_tail; GNUNET_CONTAINER_DLL_remove (ctx->stack_head, ctx->stack_tail, b); a = ctx->stack_tail; GNUNET_CONTAINER_DLL_remove (ctx->stack_head, ctx->stack_tail, a); state_add_transition (ctx, a->end, 0, b->start); a->end->accepting = 0; b->end->accepting = 1; new = nfa_fragment_create (NULL, NULL); nfa_add_states (new, a->states_head, a->states_tail); nfa_add_states (new, b->states_head, b->states_tail); new->start = a->start; new->end = b->end; automaton_fragment_clear (a); automaton_fragment_clear (b); GNUNET_CONTAINER_DLL_insert_tail (ctx->stack_head, ctx->stack_tail, new); } /** * Pops a NFA fragment from the stack (a) and adds a new fragment (a*) * * @param ctx context */ static void nfa_add_star_op (struct GNUNET_REGEX_Context *ctx) { struct GNUNET_REGEX_Automaton *a; struct GNUNET_REGEX_Automaton *new; struct GNUNET_REGEX_State *start; struct GNUNET_REGEX_State *end; a = ctx->stack_tail; GNUNET_CONTAINER_DLL_remove (ctx->stack_head, ctx->stack_tail, a); if (NULL == a) { GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "nfa_add_star_op failed, because there was no element on the stack"); return; } start = nfa_state_create (ctx, 0); end = nfa_state_create (ctx, 1); state_add_transition (ctx, start, 0, a->start); state_add_transition (ctx, start, 0, end); state_add_transition (ctx, a->end, 0, a->start); state_add_transition (ctx, a->end, 0, end); a->end->accepting = 0; end->accepting = 1; new = nfa_fragment_create (start, end); nfa_add_states (new, a->states_head, a->states_tail); automaton_fragment_clear (a); GNUNET_CONTAINER_DLL_insert_tail (ctx->stack_head, ctx->stack_tail, new); } /** * Pops an NFA fragment (a) from the stack and adds a new fragment (a+) * * @param ctx context */ static void nfa_add_plus_op (struct GNUNET_REGEX_Context *ctx) { struct GNUNET_REGEX_Automaton *a; a = ctx->stack_tail; GNUNET_CONTAINER_DLL_remove (ctx->stack_head, ctx->stack_tail, a); state_add_transition (ctx, a->end, 0, a->start); GNUNET_CONTAINER_DLL_insert_tail (ctx->stack_head, ctx->stack_tail, a); } /** * Pops an NFA fragment (a) from the stack and adds a new fragment (a?) * * @param ctx context */ static void nfa_add_question_op (struct GNUNET_REGEX_Context *ctx) { struct GNUNET_REGEX_Automaton *a; struct GNUNET_REGEX_Automaton *new; struct GNUNET_REGEX_State *start; struct GNUNET_REGEX_State *end; a = ctx->stack_tail; GNUNET_CONTAINER_DLL_remove (ctx->stack_head, ctx->stack_tail, a); if (NULL == a) { GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "nfa_add_question_op failed, because there was no element on the stack"); return; } start = nfa_state_create (ctx, 0); end = nfa_state_create (ctx, 1); state_add_transition (ctx, start, 0, a->start); state_add_transition (ctx, start, 0, end); state_add_transition (ctx, a->end, 0, end); a->end->accepting = 0; new = nfa_fragment_create (start, end); nfa_add_states (new, a->states_head, a->states_tail); automaton_fragment_clear (a); GNUNET_CONTAINER_DLL_insert_tail (ctx->stack_head, ctx->stack_tail, new); } /** * Pops two NFA fragments (a, b) from the stack and adds a new NFA fragment that * alternates between a and b (a|b) * * @param ctx context */ static void nfa_add_alternation (struct GNUNET_REGEX_Context *ctx) { struct GNUNET_REGEX_Automaton *a; struct GNUNET_REGEX_Automaton *b; struct GNUNET_REGEX_Automaton *new; struct GNUNET_REGEX_State *start; struct GNUNET_REGEX_State *end; b = ctx->stack_tail; GNUNET_CONTAINER_DLL_remove (ctx->stack_head, ctx->stack_tail, b); a = ctx->stack_tail; GNUNET_CONTAINER_DLL_remove (ctx->stack_head, ctx->stack_tail, a); start = nfa_state_create (ctx, 0); end = nfa_state_create (ctx, 1); state_add_transition (ctx, start, 0, a->start); state_add_transition (ctx, start, 0, b->start); state_add_transition (ctx, a->end, 0, end); state_add_transition (ctx, b->end, 0, end); a->end->accepting = 0; b->end->accepting = 0; end->accepting = 1; new = nfa_fragment_create (start, end); nfa_add_states (new, a->states_head, a->states_tail); nfa_add_states (new, b->states_head, b->states_tail); automaton_fragment_clear (a); automaton_fragment_clear (b); GNUNET_CONTAINER_DLL_insert_tail (ctx->stack_head, ctx->stack_tail, new); } /** * Adds a new nfa fragment to the stack * * @param ctx context * @param lit label for nfa transition */ static void nfa_add_label (struct GNUNET_REGEX_Context *ctx, const char lit) { struct GNUNET_REGEX_Automaton *n; struct GNUNET_REGEX_State *start; struct GNUNET_REGEX_State *end; GNUNET_assert (NULL != ctx); start = nfa_state_create (ctx, 0); end = nfa_state_create (ctx, 1); state_add_transition (ctx, start, lit, end); n = nfa_fragment_create (start, end); GNUNET_assert (NULL != n); GNUNET_CONTAINER_DLL_insert_tail (ctx->stack_head, ctx->stack_tail, n); } /** * Initialize a new context * * @param ctx context */ static void GNUNET_REGEX_context_init (struct GNUNET_REGEX_Context *ctx) { if (NULL == ctx) { GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "Context was NULL!"); return; } ctx->state_id = 0; ctx->transition_id = 0; ctx->stack_head = NULL; ctx->stack_tail = NULL; } /** * Construct an NFA by parsing the regex string of length 'len'. * * @param regex regular expression string * @param len length of the string * * @return NFA, needs to be freed using GNUNET_REGEX_destroy_automaton */ struct GNUNET_REGEX_Automaton * GNUNET_REGEX_construct_nfa (const char *regex, const size_t len) { struct GNUNET_REGEX_Context ctx; struct GNUNET_REGEX_Automaton *nfa; const char *regexp; char *error_msg; unsigned int count; unsigned int altcount; unsigned int atomcount; unsigned int pcount; struct { int altcount; int atomcount; } *p; GNUNET_REGEX_context_init (&ctx); regexp = regex; p = NULL; error_msg = NULL; altcount = 0; atomcount = 0; pcount = 0; for (count = 0; count < len && *regexp; count++, regexp++) { switch (*regexp) { case '(': if (atomcount > 1) { --atomcount; nfa_add_concatenation (&ctx); } GNUNET_array_grow (p, pcount, pcount + 1); p[pcount - 1].altcount = altcount; p[pcount - 1].atomcount = atomcount; altcount = 0; atomcount = 0; break; case '|': if (0 == atomcount) { error_msg = "Cannot append '|' to nothing"; goto error; } while (--atomcount > 0) nfa_add_concatenation (&ctx); altcount++; break; case ')': if (0 == pcount) { error_msg = "Missing opening '('"; goto error; } if (0 == atomcount) { // Ignore this: "()" pcount--; altcount = p[pcount].altcount; atomcount = p[pcount].atomcount; break; } while (--atomcount > 0) nfa_add_concatenation (&ctx); for (; altcount > 0; altcount--) nfa_add_alternation (&ctx); pcount--; altcount = p[pcount].altcount; atomcount = p[pcount].atomcount; atomcount++; break; case '*': if (atomcount == 0) { error_msg = "Cannot append '*' to nothing"; goto error; } nfa_add_star_op (&ctx); break; case '+': if (atomcount == 0) { error_msg = "Cannot append '+' to nothing"; goto error; } nfa_add_plus_op (&ctx); break; case '?': if (atomcount == 0) { error_msg = "Cannot append '?' to nothing"; goto error; } nfa_add_question_op (&ctx); break; case 92: /* escape: \ */ regexp++; count++; default: if (atomcount > 1) { --atomcount; nfa_add_concatenation (&ctx); } nfa_add_label (&ctx, *regexp); atomcount++; break; } } if (0 != pcount) { error_msg = "Unbalanced parenthesis"; goto error; } while (--atomcount > 0) nfa_add_concatenation (&ctx); for (; altcount > 0; altcount--) nfa_add_alternation (&ctx); GNUNET_free_non_null (p); nfa = ctx.stack_tail; GNUNET_CONTAINER_DLL_remove (ctx.stack_head, ctx.stack_tail, nfa); if (NULL != ctx.stack_head) { error_msg = "Creating the NFA failed. NFA stack was not empty!"; goto error; } nfa->regex = GNUNET_strdup (regex); return nfa; error: GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "Could not parse regex: %s\n", regex); if (NULL != error_msg) GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "%s\n", error_msg); GNUNET_free_non_null (p); while (NULL != (nfa = ctx.stack_head)) { GNUNET_CONTAINER_DLL_remove (ctx.stack_head, ctx.stack_tail, nfa); GNUNET_REGEX_automaton_destroy (nfa); } return NULL; } /** * Create DFA states based on given 'nfa' and starting with 'dfa_state'. * * @param ctx context. * @param nfa NFA automaton. * @param dfa DFA automaton. * @param dfa_state current dfa state, pass epsilon closure of first nfa state * for starting. */ static void construct_dfa_states (struct GNUNET_REGEX_Context *ctx, struct GNUNET_REGEX_Automaton *nfa, struct GNUNET_REGEX_Automaton *dfa, struct GNUNET_REGEX_State *dfa_state) { struct Transition *ctran; struct GNUNET_REGEX_State *state_iter; struct GNUNET_REGEX_State *new_dfa_state; struct GNUNET_REGEX_State *state_contains; struct GNUNET_REGEX_StateSet *tmp; struct GNUNET_REGEX_StateSet *nfa_set; for (ctran = dfa_state->transitions_head; NULL != ctran; ctran = ctran->next) { if (0 == ctran->label || NULL != ctran->to_state) continue; tmp = nfa_closure_set_create (nfa, dfa_state->nfa_set, ctran->label); nfa_set = nfa_closure_set_create (nfa, tmp, 0); state_set_clear (tmp); new_dfa_state = dfa_state_create (ctx, nfa_set); state_contains = NULL; for (state_iter = dfa->states_head; NULL != state_iter; state_iter = state_iter->next) { if (0 == state_set_compare (state_iter->nfa_set, new_dfa_state->nfa_set)) state_contains = state_iter; } if (NULL == state_contains) { automaton_add_state (dfa, new_dfa_state); ctran->to_state = new_dfa_state; construct_dfa_states (ctx, nfa, dfa, new_dfa_state); } else { ctran->to_state = state_contains; automaton_destroy_state (new_dfa_state); } } } /** * Construct DFA for the given 'regex' of length 'len' * * @param regex regular expression string * @param len length of the regular expression * * @return DFA, needs to be freed using GNUNET_REGEX_destroy_automaton */ struct GNUNET_REGEX_Automaton * GNUNET_REGEX_construct_dfa (const char *regex, const size_t len) { struct GNUNET_REGEX_Context ctx; struct GNUNET_REGEX_Automaton *dfa; struct GNUNET_REGEX_Automaton *nfa; struct GNUNET_REGEX_StateSet *nfa_set; GNUNET_REGEX_context_init (&ctx); // Create NFA nfa = GNUNET_REGEX_construct_nfa (regex, len); if (NULL == nfa) { GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "Could not create DFA, because NFA creation failed\n"); return NULL; } dfa = GNUNET_malloc (sizeof (struct GNUNET_REGEX_Automaton)); dfa->type = DFA; dfa->regex = GNUNET_strdup (regex); // Create DFA start state from epsilon closure nfa_set = nfa_closure_create (nfa, nfa->start, 0); dfa->start = dfa_state_create (&ctx, nfa_set); automaton_add_state (dfa, dfa->start); construct_dfa_states (&ctx, nfa, dfa, dfa->start); GNUNET_REGEX_automaton_destroy (nfa); // Minimize DFA dfa_minimize (&ctx, dfa); // Create proofs for all states automaton_create_proofs (dfa); return dfa; } /** * Free the memory allocated by constructing the GNUNET_REGEX_Automaton data * structure. * * @param a automaton to be destroyed */ void GNUNET_REGEX_automaton_destroy (struct GNUNET_REGEX_Automaton *a) { struct GNUNET_REGEX_State *s; struct GNUNET_REGEX_State *next_state; if (NULL == a) return; GNUNET_free_non_null (a->regex); GNUNET_free_non_null (a->canonical_regex); for (s = a->states_head; NULL != s;) { next_state = s->next; automaton_destroy_state (s); s = next_state; } GNUNET_free (a); } /** * Save a state to an open file pointer. cls is expected to be a file pointer to * an open file. Used only in conjunction with * GNUNET_REGEX_automaton_save_graph. * * @param cls file pointer. * @param count current count of the state, not used. * @param s state. */ void GNUNET_REGEX_automaton_save_graph_step (void *cls, unsigned int count, struct GNUNET_REGEX_State *s) { FILE *p; struct Transition *ctran; char *s_acc = NULL; char *s_tran = NULL; p = cls; if (s->accepting) { GNUNET_asprintf (&s_acc, "\"%s(%i)\" [shape=doublecircle, color=\"0.%i 0.8 0.95\"];\n", s->name, s->proof_id, s->scc_id); } else { GNUNET_asprintf (&s_acc, "\"%s(%i)\" [color=\"0.%i 0.8 0.95\"];\n", s->name, s->proof_id, s->scc_id); } if (NULL == s_acc) { GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "Could not print state %s\n", s->name); return; } fwrite (s_acc, strlen (s_acc), 1, p); GNUNET_free (s_acc); s_acc = NULL; for (ctran = s->transitions_head; NULL != ctran; ctran = ctran->next) { if (NULL == ctran->to_state) { GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "Transition from State %i has no state for transitioning\n", s->id); continue; } if (ctran->label == 0) { GNUNET_asprintf (&s_tran, "\"%s(%i)\" -> \"%s(%i)\" [label = \"epsilon\", color=\"0.%i 0.8 0.95\"];\n", s->name, s->proof_id, ctran->to_state->name, ctran->to_state->proof_id, s->scc_id); } else { GNUNET_asprintf (&s_tran, "\"%s(%i)\" -> \"%s(%i)\" [label = \"%c\", color=\"0.%i 0.8 0.95\"];\n", s->name, s->proof_id, ctran->to_state->name, ctran->to_state->proof_id, ctran->label, s->scc_id); } if (NULL == s_tran) { GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "Could not print state %s\n", s->name); return; } fwrite (s_tran, strlen (s_tran), 1, p); GNUNET_free (s_tran); s_tran = NULL; } } /** * Save the given automaton as a GraphViz dot file * * @param a the automaton to be saved * @param filename where to save the file */ void GNUNET_REGEX_automaton_save_graph (struct GNUNET_REGEX_Automaton *a, const char *filename) { char *start; char *end; FILE *p; if (NULL == a) { GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "Could not print NFA, was NULL!"); return; } if (NULL == filename || strlen (filename) < 1) { GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "No Filename given!"); return; } p = fopen (filename, "w"); if (NULL == p) { GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "Could not open file for writing: %s", filename); return; } /* First add the SCCs to the automaton, so we can color them nicely */ scc_tarjan (a); start = "digraph G {\nrankdir=LR\n"; fwrite (start, strlen (start), 1, p); automaton_traverse (a, &GNUNET_REGEX_automaton_save_graph_step, p); end = "\n}\n"; fwrite (end, strlen (end), 1, p); fclose (p); } /** * Evaluates the given string using the given DFA automaton * * @param a automaton, type must be DFA * @param string string that should be evaluated * * @return 0 if string matches, non 0 otherwise */ static int evaluate_dfa (struct GNUNET_REGEX_Automaton *a, const char *string) { const char *strp; struct GNUNET_REGEX_State *s; if (DFA != a->type) { GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "Tried to evaluate DFA, but NFA automaton given"); return -1; } s = a->start; // If the string is empty but the starting state is accepting, we accept. if ((NULL == string || 0 == strlen (string)) && s->accepting) return 0; for (strp = string; NULL != strp && *strp; strp++) { s = dfa_move (s, *strp); if (NULL == s) break; } if (NULL != s && s->accepting) return 0; return 1; } /** * Evaluates the given string using the given NFA automaton * * @param a automaton, type must be NFA * @param string string that should be evaluated * * @return 0 if string matches, non 0 otherwise */ static int evaluate_nfa (struct GNUNET_REGEX_Automaton *a, const char *string) { const char *strp; struct GNUNET_REGEX_State *s; struct GNUNET_REGEX_StateSet *sset; struct GNUNET_REGEX_StateSet *new_sset; unsigned int i; int result; if (NFA != a->type) { GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "Tried to evaluate NFA, but DFA automaton given"); return -1; } // If the string is empty but the starting state is accepting, we accept. if ((NULL == string || 0 == strlen (string)) && a->start->accepting) return 0; result = 1; strp = string; sset = nfa_closure_create (a, a->start, 0); for (strp = string; NULL != strp && *strp; strp++) { new_sset = nfa_closure_set_create (a, sset, *strp); state_set_clear (sset); sset = nfa_closure_set_create (a, new_sset, 0); state_set_clear (new_sset); } for (i = 0; i < sset->len; i++) { s = sset->states[i]; if (NULL != s && s->accepting) { result = 0; break; } } state_set_clear (sset); return result; } /** * Evaluates the given 'string' against the given compiled regex * * @param a automaton * @param string string to check * * @return 0 if string matches, non 0 otherwise */ int GNUNET_REGEX_eval (struct GNUNET_REGEX_Automaton *a, const char *string) { int result; switch (a->type) { case DFA: result = evaluate_dfa (a, string); break; case NFA: result = evaluate_nfa (a, string); break; default: GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "Evaluating regex failed, automaton has no type!\n"); result = GNUNET_SYSERR; break; } return result; } /** * Get the canonical regex of the given automaton. * When constructing the automaton a proof is computed for each state, * consisting of the regular expression leading to this state. A complete * regex for the automaton can be computed by combining these proofs. * As of now this function is only useful for testing. * * @param a automaton for which the canonical regex should be returned. * * @return */ const char * GNUNET_REGEX_get_canonical_regex (struct GNUNET_REGEX_Automaton *a) { if (NULL == a) return NULL; return a->canonical_regex; } /** * Get the first key for the given 'input_string'. This hashes the first x bits * of the 'input_strings'. * * @param input_string string. * @param string_len length of the 'input_string'. * @param key pointer to where to write the hash code. * * @return number of bits of 'input_string' that have been consumed * to construct the key */ unsigned int GNUNET_REGEX_get_first_key (const char *input_string, unsigned int string_len, struct GNUNET_HashCode *key) { unsigned int size; size = string_len < INITIAL_BITS ? string_len : INITIAL_BITS; if (NULL == input_string) { GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "Given input string was NULL!\n"); return 0; } GNUNET_CRYPTO_hash (input_string, size, key); return size; } /** * Check if the given 'proof' matches the given 'key'. * * @param proof partial regex * @param key hash * * @return GNUNET_OK if the proof is valid for the given key */ int GNUNET_REGEX_check_proof (const char *proof, const struct GNUNET_HashCode *key) { return GNUNET_OK; } /** * Iterate over all edges helper function starting from state 's', calling * iterator on for each edge. * * @param s state. * @param iterator iterator function called for each edge. * @param iterator_cls closure. */ static void iterate_edge (struct GNUNET_REGEX_State *s, GNUNET_REGEX_KeyIterator iterator, void *iterator_cls) { struct Transition *t; struct GNUNET_REGEX_Edge edges[s->transition_count]; unsigned int num_edges; if (GNUNET_YES != s->marked) { s->marked = GNUNET_YES; num_edges = state_get_edges (s, edges); iterator (iterator_cls, &s->hash, s->proof, s->accepting, num_edges, edges); for (t = s->transitions_head; NULL != t; t = t->next) iterate_edge (t->to_state, iterator, iterator_cls); } } /** * Iterate over all edges starting from start state of automaton 'a'. Calling * iterator for each edge. * * @param a automaton. * @param iterator iterator called for each edge. * @param iterator_cls closure. */ void GNUNET_REGEX_iterate_all_edges (struct GNUNET_REGEX_Automaton *a, GNUNET_REGEX_KeyIterator iterator, void *iterator_cls) { struct GNUNET_REGEX_State *s; for (s = a->states_head; NULL != s; s = s->next) s->marked = GNUNET_NO; iterate_edge (a->start, iterator, iterator_cls); }