Imported Upstream version 0.9.3upstream/0.9.3

1 files changed, 2252 insertions, 0 deletions

diff --git a/src/regex/regex.c b/src/regex/regex.c
new file mode 100644
index 0000000..5244c26
--- /dev/null
+++ b/src/regex/regex.c
@@ -0,0 +1,2252 @@
+/*
+     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.h"
+
+#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;
+
+  /**
+   * Unique SCC (Strongly Connected Component) id.
+   */
+  unsigned int scc_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_automaton_type
+{
+  NFA,
+  DFA
+};
+
+/**
+ * Automaton representation.
+ */
+struct GNUNET_REGEX_Automaton
+{
+  /**
+   * This is a linked list.
+   */
+  struct GNUNET_REGEX_Automaton *prev;
+
+  /**
+   * This is a linked list.
+   */
+  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 automaton.
+   */
+  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_automaton_type type;
+};
+
+/**
+ * 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.
+   */
+  GNUNET_HashCode hash;
+
+  /**
+   * 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
+ */
+void
+debug_print_transitions (struct GNUNET_REGEX_State *);
+
+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);
+}
+
+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);
+}
+
+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 ctx context
+ * @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 (struct GNUNET_REGEX_Context *ctx,
+                          struct GNUNET_REGEX_State *v, 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 (ctx, 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)
+    {
+      ctx->scc_id++;
+      while (v != w)
+      {
+        w->scc_id = ctx->scc_id;
+        w = stack[--(*stack_size)];
+        w->contained = 0;
+      }
+      w->scc_id = ctx->scc_id;
+    }
+  }
+}
+
+/**
+ * Detect all SCCs (Strongly Connected Components) inside the given automaton.
+ * SCCs will be marked using the scc_id on each state.
+ *
+ * @param ctx context
+ * @param a automaton
+ */
+static void
+scc_tarjan (struct GNUNET_REGEX_Context *ctx, struct GNUNET_REGEX_Automaton *a)
+{
+  int index;
+  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;
+
+  for (v = a->states_head; NULL != v; v = v->next)
+  {
+    if (v->index < 0)
+      scc_tarjan_strongconnect (ctx, 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;
+
+  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;
+
+  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 (from_state->transitions_head,
+                               from_state->transitions_tail, 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;
+  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)
+  {
+    if (NULL != set->states)
+      GNUNET_free (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;
+
+  if (NULL != s->name)
+    GNUNET_free (s->name);
+
+  if (NULL != s->proof)
+    GNUNET_free (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 = GNUNET_strdup (s1->name);
+  if (NULL != s1->name)
+  {
+    GNUNET_free (s1->name);
+    s1->name = NULL;
+  }
+  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 s state
+ */
+typedef void (*GNUNET_REGEX_traverse_action) (void *cls,
+                                              struct GNUNET_REGEX_State * s);
+
+/**
+ * Traverses 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 cls closure.
+ * @param s start state.
+ * @param action action to be performed on each state.
+ */
+static void
+automaton_state_traverse (void *cls, struct GNUNET_REGEX_State *s,
+                          GNUNET_REGEX_traverse_action action)
+{
+  struct Transition *t;
+
+  if (GNUNET_NO == s->marked)
+  {
+    s->marked = GNUNET_YES;
+
+    if (action > 0)
+      action (cls, s);
+
+    for (t = s->transitions_head; NULL != t; t = t->next)
+      automaton_state_traverse (cls, t->to_state, action);
+  }
+}
+
+/**
+ * Traverses the given automaton from it's start state, visiting all reachable
+ * states and calling 'action' on each one of them.
+ *
+ * @param cls closure.
+ * @param a automaton.
+ * @param action action to be performed on each state.
+ */
+static void
+automaton_traverse (void *cls, struct GNUNET_REGEX_Automaton *a,
+                    GNUNET_REGEX_traverse_action action)
+{
+  struct GNUNET_REGEX_State *s;
+
+  for (s = a->states_head; NULL != s; s = s->next)
+    s->marked = GNUNET_NO;
+
+  automaton_state_traverse (cls, a->start, action);
+}
+
+/**
+ * Reverses all transitions of the given automaton.
+ *
+ * @param a automaton.
+ */
+static void
+automaton_reverse (struct GNUNET_REGEX_Automaton *a)
+{
+  struct GNUNET_REGEX_State *s;
+  struct Transition *t;
+  struct Transition *t_next;
+  struct GNUNET_REGEX_State *s_swp;
+
+  for (s = a->states_head; NULL != s; s = s->next)
+    for (t = s->transitions_head; NULL != t; t = t->next)
+      t->mark = GNUNET_NO;
+
+  for (s = a->states_head; NULL != s; s = s->next)
+  {
+    for (t = s->transitions_head; NULL != t; t = t_next)
+    {
+      t_next = t->next;
+
+      if (GNUNET_YES == t->mark || t->from_state == t->to_state)
+        continue;
+
+      t->mark = GNUNET_YES;
+
+      GNUNET_CONTAINER_DLL_remove (t->from_state->transitions_head,
+                                   t->from_state->transitions_tail, t);
+      t->from_state->transition_count--;
+      GNUNET_CONTAINER_DLL_insert (t->to_state->transitions_head,
+                                   t->to_state->transitions_tail, t);
+      t->to_state->transition_count++;
+
+      s_swp = t->from_state;
+      t->from_state = t->to_state;
+      t->to_state = s_swp;
+    }
+  }
+}
+
+/**
+ * Create proof for the given state.
+ *
+ * @param cls closure.
+ * @param s state.
+ */
+static void
+automaton_create_proofs_step (void *cls, struct GNUNET_REGEX_State *s)
+{
+  struct Transition *t;
+  int i;
+  char *tmp;
+
+  for (i = 0, t = s->transitions_head; NULL != t; t = t->next, i++)
+  {
+    if (t->to_state == s)
+      GNUNET_asprintf (&tmp, "%c*", t->label);
+    else if (i != s->transition_count - 1)
+      GNUNET_asprintf (&tmp, "%c|", t->label);
+    else
+      GNUNET_asprintf (&tmp, "%c", t->label);
+
+    if (NULL != s->proof)
+      s->proof =
+          GNUNET_realloc (s->proof, strlen (s->proof) + strlen (tmp) + 1);
+    else
+      s->proof = GNUNET_malloc (strlen (tmp) + 1);
+    strcat (s->proof, tmp);
+    GNUNET_free (tmp);
+  }
+}
+
+/**
+ * Create proofs for all states in the given automaton.
+ *
+ * @param a automaton.
+ */
+static void
+automaton_create_proofs (struct GNUNET_REGEX_Automaton *a)
+{
+  struct GNUNET_REGEX_State *s;
+
+  automaton_reverse (a);
+
+  for (s = a->states_head; NULL != s; s = s->next)
+    automaton_create_proofs_step (NULL, s);
+
+  automaton_reverse (a);
+}
+
+/**
+ * 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;
+  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 (NULL, a, 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)
+{
+  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;
+  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_state