Complete rewrite to support class trees. Makes the behaviour of the set

[become] / src / class.c

/* -*-c-*-
 *
 * $Id: class.c,v 1.6 1997/09/17 10:14:56 mdw Exp $
 *
 * Handling classes of things nicely
 *
 * (c) 1997 EBI
 */

/*----- Licensing notice --------------------------------------------------*
 *
 * This file is part of `become'
 *
 * `Become' 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 2 of the License, or
 * (at your option) any later version.
 *
 * `Become' 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 `become'; if not, write to the Free Software Foundation,
 * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 */

/*----- Revision history --------------------------------------------------*
 *
 * $Log: class.c,v $
 * Revision 1.6  1997/09/17 10:14:56  mdw
 * Complete rewrite to support class trees.  Makes the behaviour of the set
 * operators much more logical.
 *
 * Revision 1.5  1997/08/20  16:16:13  mdw
 * Patch memory leak.  Don't try to trace when tracing's turned off.
 *
 * Revision 1.4  1997/08/07 09:56:37  mdw
 * (Log entry for previous version is bogus.)  Minor changes to host
 * checking code.
 *
 * Revision 1.2  1997/08/04 10:24:21  mdw
 * Sources placed under CVS control.
 *
 * Revision 1.1  1997/07/21  13:47:52  mdw
 * Initial revision
 *
 */

/*----- Header files ------------------------------------------------------*/

/* --- ANSI headers --- */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

/* --- Unix headers --- */

#include <sys/types.h>
#include <sys/socket.h>

#include <netinet/in.h>

#include <arpa/inet.h>

#include <netdb.h>

/* --- Local headers --- */

#include "become.h"
#include "class.h"
#include "sym.h"
#include "utils.h"

/*----- Global variables --------------------------------------------------*/

static class_node class__all = { clType_all | clNode_any, -1, { 0 }};
class_node *class_all = &class__all;

static class_node class__none = { clType_all | clNode_any, -1, { 0 }};
class_node *class_none = &class__none;

/*----- Wildcard matching -------------------------------------------------*/

/* --- @class__wildMatch@ --- *
 *
 * Arguments:   @const char *pat@ = pointer to pattern string
 *              @const char *p@ = pointer to target string
 *
 * Returns:     Zero if no match, nonzero if match.
 *
 * Use:         Wildcard-matches the pattern against the target string.
 */

static int class__wildMatch(const char *pat, const char *p)
{
  for (;;) {
    if (*pat == 0 && *p == 0)
      return (42); /* For sadism's sake */
    else if (*pat == '*') {
      while (*pat == '*')
        pat++;
      do {
        if (class__wildMatch(pat, p))
          return (27); /* Nyahaha */
        p++;
      } while (*p);
      return (pat[1] == 0);
    } else if (*pat == '?' || *pat == *p)
      p++, pat++;
    else
      return (0);
  }
}

/*----- Creating new class nodes ------------------------------------------*/

/* --- @class_fromString@ --- *
 *
 * Arguments:   @unsigned type@ = a type field
 *              @const char *s@ = pointer to string to copy
 *
 * Returns:     A pointer to a class node containing that string, typed to
 *              be the right thing.
 *
 * Use:         Given a string, wrap a class node around it.  The node has
 *              one reference (the one you get returned).  The string is
 *              copied, so you can get rid of your original one if you like.
 */

class_node *class_fromString(unsigned type, const char *s)
{
  class_node *c = xmalloc(sizeof(*c));
  c->type = type | clNode_immed;
  if (s[strcspn(s, "*?")] == 0)
    c->type |= clFlag_friendly;
  c->ref = 1;
  c->v.s = xstrdup(s);
  return (c);
}

/* --- @class_fromUser@ --- *
 *
 * Arguments:   @unsigned type@ = a type field
 *              @uid_t u@ = a user-id number
 *
 * Returns:     A pointer to a class node containing the uid, typed to be
 *              the thing you asked for.  Hopefully this will be
 *              @clType_user@.
 *
 * Use:         Given a uid, wrap a class node around it.
 */

class_node *class_fromUser(unsigned type, uid_t u)
{
  class_node *c = xmalloc(sizeof(*c));
  c->type = type | clNode_immed | clFlag_friendly;
  c->ref = 1;
  c->v.u = u;
  return (c);
}

/*----- Reference counter tricks ------------------------------------------*/

/* --- @class_inc@ --- *
 *
 * Arguments:   @class_node *c@ = pointer to a class block
 *
 * Returns:     ---
 *
 * Use:         Adds a reference to the class definition.
 */

void class_inc(class_node *c)
{
  if (c != class_all && c != class_none)
    c->ref++;
}

/* --- @class_dec@ --- *
 *
 * Arguments:   @class_node *c@ = pointer to a class block
 *
 * Returns:     ---
 *
 * Use:         Removes a reference to a class block.
 */

void class_dec(class_node *c)
{
  class_node *cc;

  for (cc = 0; c; c = cc, cc = 0) {
    if (c == class_all || c == class_none || --c->ref)
      continue;
    switch (c->type & clNode_mask) {
      case clNode_any:
        /* Nothing to do */
        break;
      case clNode_immed:
        if (c->type & (clType_host | clType_command))
          free(c->v.s);
        break;
      case clNode_hash:
        sym_destroyTable(&c->v.t);
        break;
      case clNode_union:
      case clNode_diff:
      case clNode_isect:
        class_dec(c->v.c.l);
        cc = c->v.c.r;
        break;
    }
    free(c);
  }
}

/* --- @class_mod@ --- *
 *
 * Arguments:   @class_node *c@ = pointer to a class node
 *
 * Returns:     A pointer to a class node, maybe the same one, maybe not,
 *              with a reference count of 1, containing the same data.
 *
 * Use:         Gives you a node which you can modify.  Don't call this
 *              for @class_all@ or @class_none@.
 */

class_node *class_mod(class_node *c)
{
  class_node *cc;

  if (c->ref == 1)
    return (c);

  cc = xmalloc(sizeof(*cc));
  cc->type = c->type;
  cc->ref = 1;
  switch (c->type & clNode_mask) {
    case clNode_any:
      die("internal error: class_mod called on non-modifiable class node");
      break;

    case clNode_immed:
      if (c->type & clType_user)
        cc->v.u = c->v.u;
      else
        cc->v.s = xstrdup(c->v.s);
      break;

    case clNode_hash: {
      sym_iter i;
      sym_base *b;

      sym_createTable(&cc->v.t);
      for (sym_createIter(&i, &c->v.t); (b = sym_next(&i)) != 0; )
        sym_find(&cc->v.t, b->name, b->len, sizeof(sym_base), 0);
    } break;

    case clNode_union:
    case clNode_diff:
    case clNode_isect:
      cc->v.c.l = c->v.c.l;
      cc->v.c.r = c->v.c.r;
      class_inc(cc->v.c.l);
      class_inc(cc->v.c.r);
      break;
  }

  class_dec(c);
  return (cc);
}

/*----- Some weirder operations on classes --------------------------------*/

/* --- @class__hashify@ --- *
 *
 * Arguments:   @class_node *c@ = pointer to a node
 *
 * Returns:     A pointer to a hash node containing the node's value.
 *
 * Use:         The original node must have type `immediate', and it must
 *              be friendly.  The old reference is discarded -- you get this
 *              one instead.
 */

static class_node *class__hashify(class_node *c)
{
  /* --- Some sanity checking --- */

  if (~c->type & clFlag_friendly)
    die("internal error: class__hashify can't hashify unfriendly nodes");
  if ((c->type & clNode_mask) != clNode_immed)
    die("internal error: class__hashify can't hashify non-immediate nodes");

  /* --- Split off a private copy of the node --- */

  c = class_mod(c);
  
  c->type = (c->type & clType_mask) | clNode_hash | clFlag_friendly;

  if (c->type & clType_user) {
    uid_t u = c->v.u;
    sym_createTable(&c->v.t);
    sym_find(&c->v.t, (char *)&u, sizeof(u), sizeof(sym_base), 0);
  } else {
    char *s = c->v.s;
    sym_createTable(&c->v.t);
    sym_find(&c->v.t, s, -1, sizeof(sym_base), 0);
    free(s);
  }

  return (c);
}

/*----- Arithmetic on classes ---------------------------------------------*/

/* --- @class__binop@ --- *
 *
 * Arguments:   @class_node *l@ = left argument
 *              @class_node *r@ = right argument
 *              @unsigned op@ = the binop code
 *
 * Returns:     A class node representing the result of a binary operation
 *              upon two classes.
 *
 * Use:         Performs a binary operation on classes.  If the types don't
 *              match, then a null pointer is returned.  Both @l@ and @r@
 *              may be modified, and will be decremented before they get
 *              returned to you.  If you don't want that to happen, ensure
 *              that you've claimed a reference to the original versions.
 *
 *              If both nodes are `friendly' (see below), then an attempt is
 *              made to combine them sensibly using a hashtable.
 *
 *              If one or both nodes is/are unfriendly, a binop node is
 *              created with type @op@ to allow the matcher to decide on
 *              membership appropriately at match time.
 *
 *              A friendly node is one which can be placed in a hash table to
 *              speed up searching.  It's friendly, because it doesn't mind
 *              living with other nodes.  Uid numbers are friendly.
 *              Wildcarded strings aren't.  Hashtables are trivially
 *              friendly.
 */

class_node *class__binop(class_node *l, class_node *r, int op)
{
  unsigned type = l->type & r->type & clType_mask;
  unsigned lnode = l->type & clNode_mask, rnode = r->type & clNode_mask;

  /* --- Check for compatible types --- */

  if (!type) {
    class_dec(l);
    class_dec(r);
    return (0);
  }

  /* --- Handle `friendly' nodes --- */

  if ((l->type & r->type & clFlag_friendly)) {

    /* --- Consider promoting an item to a hash --- *
     *
     * If both are immediate nodes, and they're both `friendly', we can
     * profitably hash them together.
     *
     * Life gets complicated when we do subtraction, because it's not
     * commutative.  In this case, I have to promote the left operand anyway.
     */

    if (lnode == clNode_immed &&
        (rnode == clNode_immed || op == clNode_diff)) {

      /* --- Quick check for triviality --- *
       *
       * There are some more short-cuts I can employ if the values are
       * the same.
       */

      if (rnode == clNode_immed) {

        /* --- See whether the two items are equal --- */

        int eq = (type & clType_user ?
                  l->v.u == r->v.u : strcmp(l->v.s, r->v.s) == 0);

        /* --- Now do something appropriate --- */

        switch (op) {
          case clNode_union:
            if (eq) {
              class_dec(r);
              return (l);
            }
            break;
          case clNode_diff:
            if (eq) {
              class_dec(l);
              class_dec(r);
              return (class_none);
            }
            break;
          case clNode_isect:
            if (eq) {
              class_dec(r);
              return (l);
            } else {
              class_dec(l);
              class_dec(r);
              return (class_none);
            }
            break;
        }
      }

      /* --- Turn @l@ into a hash containing itself --- */

      l = class__hashify(l);
      lnode = clNode_hash;
    }

    /* --- Otherwise, make @l@ the hash --- *
     *
     * Both @l@ and @r@ are friendly.  Since they're not both immediates,
     * one must be a hash.
     */

    else if ((l->type & clNode_mask) == clNode_immed) {
      class_node *tn;
      unsigned tt;

      tn = l, l = r, r = tn;
      tt = lnode, lnode = rnode, rnode = tt;
    }

    /* --- Now merge @r@ with @l@ --- */

    l = class_mod(l);

    switch (op) {

      /* --- The union operation isn't hard --- */

      case clNode_union:
        if (rnode == clNode_immed) {
          if (type & clType_user) {
            sym_find(&l->v.t, (char *)&r->v.u,
                     sizeof(r->v.u), sizeof(sym_base), 0);
          } else
            sym_find(&l->v.t, r->v.s, -1, sizeof(sym_base), 0);
        } else {
          sym_iter i;
          sym_base *b;

          for (sym_createIter(&i, &r->v.t); (b = sym_next(&i)) != 0; )
            sym_find(&l->v.t, b->name, b->len, sizeof(sym_base), 0);
        }
        break;

      /* --- Set difference is similar in spirit --- */

      case clNode_diff:
        if (rnode == clNode_immed) {
          sym_base *f;

          if (type & clType_user)
            f = sym_find(&l->v.t, (char *)&r->v.u, sizeof(r->v.u), 0, 0);
          else
            f = sym_find(&l->v.t, r->v.s, -1, 0, 0);
          if (f)
            sym_remove(&l->v.t, f);
        } else {
          sym_iter i;
          sym_base *b, *f;

          for (sym_createIter(&i, &r->v.t); (b = sym_next(&i)) != 0; ) {
            if ((f = sym_find(&l->v.t, b->name, b->len, 0, 0)) != 0)
              sym_remove(&l->v.t, f);
          }
        }
        break;

      /* --- Intersection is wild and wacky --- */

      case clNode_isect:
        if (rnode == clNode_immed) {
          sym_base *f;

          if (type & clType_user)
            f = sym_find(&l->v.t, (char *)&r->v.u, sizeof(r->v.u), 0, 0);
          else
            f = sym_find(&l->v.t, r->v.s, -1, 0, 0);
          if (f) {
            class_dec(l);
            return (r);
          } else {
            class_dec(l);
            class_dec(r);
            return (class_none);
          }         
        } else {
          sym_iter i;
          sym_base *b;

          for (sym_createIter(&i, &l->v.t); (b = sym_next(&i)) != 0; ) {
            if (!sym_find(&r->v.t, b->name, b->len, 0, 0))
              sym_remove(&l->v.t, b);
          }
        }
        break;
    }

    /* --- Now trim the @l@ table to size --- *
     *
     * It may have lost a load of elements.  Maybe it can be represented
     * better as an immediate or even as @class_none@.
     */

    {
      sym_iter i;
      sym_base *b;

      class_dec(r);

      sym_createIter(&i, &l->v.t);
      if ((b = sym_next(&i)) == 0) {
        class_dec(l);
        return (class_none);
      }
      if (!sym_next(&i)) {
        if (type & clType_user) {
          uid_t u = *(uid_t *)b->name;
          sym_destroyTable(&l->v.t);
          l->type = (l->type & ~clNode_mask) | clNode_immed;
          l->v.u = u;
        } else {
          char *s = xstrdup(b->name);
          sym_destroyTable(&l->v.t);
          l->type = (l->type & ~clNode_mask) | clNode_immed;
          l->v.s = s;
        }
      }
    }

    /* --- Done --- */

    return (l);
  }

  /* --- Unfriendly nodes --- *
   *
   * Create a binop node and return that.  If @l@ is a binop node, and @r@
   * isn't, and the operation isn't set difference (i.e., it's commutative)
   * then swap the two over to lessen the depth of recursion later.
   */

  else {
    class_node *c = xmalloc(sizeof(*c));

    c->type = type | op;
    c->ref = 1;
    if (lnode >= clNode_binop && rnode < clNode_binop && op != clNode_diff) {
      c->v.c.l = r;
      c->v.c.r = l;
    } else {
      c->v.c.l = l;
      c->v.c.r = r;
    }
    return (c);
  }
}

/* --- @class_union@ --- *
 *
 * Arguments:   @class_node *l@ = left argument
 *              @class_node *r@ = right argument
 *
 * Returns:     A class node representing the union of the two classes.
 *
 * Use:         Performs the union operation on classes.  If the types don't
 *              match, then a null pointer is returned.  Both @l@ and @r@
 *              may be modified, and will be decremented before they get
 *              returned to you.  If you don't want that to happen, ensure
 *              that you've claimed a reference to the original versions.
 */

class_node *class_union(class_node *l, class_node *r)
{
  /* --- Check for the really simple cases --- */

  if (l == class_all || r == class_all) {
    class_dec(l);
    class_dec(r);
    return (class_all);
  }

  if (l == class_none)
    return (r);
  if (r == class_none)
    return (l);

  /* --- Do the job --- */

  return (class__binop(l, r, clNode_union));
}

/* --- @class_diff@ --- *
 *
 * Arguments:   @class_node *l@ = left argument
 *              @class_node *r@ = right argument
 *
 * Returns:     A class node representing the difference of the two classes.
 *
 * Use:         Performs the set difference operation on classes.  If the
 *              types don't match, then a null pointer is returned.  Both
 *              @l@ and @r@ may be modified, and will be decremented before
 *              they get returned to you.  If you don't want that to happen,
 *              ensure that you've claimed a reference to the original
 *              versions.
 */

class_node *class_diff(class_node *l, class_node *r)
{
  /* --- Check for the really simple cases --- */

  if (l == class_none || r == class_all) {
    class_dec(l);
    class_dec(r);
    return (class_none);
  }

  if (r == class_none)
    return (l);

  /* --- Do the job --- */

  return (class__binop(l, r, clNode_diff));
}

/* --- @class_isect@ --- *
 *
 * Arguments:   @class_node *l@ = left argument
 *              @class_node *r@ = right argument
 *
 * Returns:     A class node representing the intersection of the two
 *              classes.
 *
 * Use:         Performs the intersecion operation on classes.  If the types
 *              don't match, then a null pointer is returned.  Both @l@ and
 *              @r@ may be modified, and will be decremented before they get
 *              returned to you.  If you don't want that to happen, ensure
 *              that you've claimed a reference to the original versions.
 */

class_node *class_isect(class_node *l, class_node *r)
{
  /* --- Check for the really simple cases --- */

  if (l == class_none || r == class_none) {
    class_dec(l);
    class_dec(r);
    return (class_none);
  }

  if (l == class_all)
    return (r);
  if (r == class_all)
    return (l);

  /* --- Do the job --- */

  return (class__binop(l, r, clNode_isect));
}

/*----- Building the predefined classes -----------------------------------*/

/* --- @class_addUser@ --- *
 *
 * Arguments:   @class_node *c@ = pointer to a class node (may be null)
 *              @uid_t u@ = user id number
 *
 * Returns:     Pointer to the combined node.
 *
 * Use:         Adds a user to a node, maybe hashifying it.
 */

class_node *class_addUser(class_node *c, uid_t u)
{
  if (!c)
    return (class_fromUser(clType_user, u));
  if ((c->type & clNode_mask) == clNode_immed)
    c = class__hashify(c);
  sym_find(&c->v.t, (char *)&u, sizeof(u), sizeof(sym_base), 0);
  return (c);
}

/* --- @class_addString@ --- *
 *
 * Arguments:   @class_node *c@ = pointer to a class node (may be null)
 *              @const char *s@ = pointer to a string
 *
 * Returns:     Pointer to the combined node.
 *
 * Use:         Adds a user to a node, maybe hashifying it.
 */

class_node *class_addString(class_node *c, const char *s)
{
  class_node *n = class_fromString(clType_host, s); /* hack */
  if (c)
    return (class_union(c, n));
  else
    return (n);
}

/*----- Matching functions ------------------------------------------------*/

/* --- @class_matchUser@ --- *
 *
 * Arguments:   @class_node *c@ = pointer to root class node
 *              @uid_t u@ = user id number
 *
 * Returns:     Nonzero if it matches, zero if it doesn't.
 *
 * Use:         Determines whether a user is matched by a class.  Assumes
 *              that the types are correct.
 */

int class_matchUser(class_node *c, uid_t u)
{
  class_node *cc;

  for (cc = 0; c; c = cc, cc = 0) {
    if (c == class_none)
      return (0);
    if (c == class_all)
      return (1);
    switch (c->type & clNode_mask) {
      case clNode_immed:
        return (u == c->v.u);
        break;
      case clNode_hash:
        return (sym_find(&c->v.t, (char *)&u, sizeof(u), 0, 0) != 0);
        break;
      case clNode_union:
        if (class_matchUser(c->v.c.l, u))
          return (1);
        cc = c->v.c.r;
        break;
      case clNode_isect:
        if (!class_matchUser(c->v.c.l, u))
          return (0);
        cc = c->v.c.r;
        break;
      case clNode_diff:
        return (class_matchUser(c->v.c.l, u) &&
                !class_matchUser(c->v.c.r, u));
        break;
    }
  }

  die("internal error: can't get here in class_matchUser");
  return (0);
}

/* --- @class_matchCommand@ --- *
 *
 * Arguments:   @class_node *c@ = pointer to root class node
 *              @const char *s@ = pointer to a string
 *
 * Returns:     Nonzero if it matches, zero if it doesn't.
 *
 * Use:         Determines whether a string is matched by a class.  Assumes
 *              that the types are correct.
 */

int class_matchCommand(class_node *c, const char *s)
{
  class_node *cc;

  for (cc = 0; c; c = cc, cc = 0) {
    if (c == class_none)
      return (0);
    if (c == class_all)
      return (1);
    switch (c->type & clNode_mask) {
      case clNode_immed:
        return (class__wildMatch(c->v.s, s));
        break;
      case clNode_hash:
        return (sym_find(&c->v.t, s, -1, 0, 0) != 0);
        break;
      case clNode_union:
        if (class_matchCommand(c->v.c.l, s))
          return (1);
        cc = c->v.c.r;
        break;
      case clNode_isect:
        if (!class_matchCommand(c->v.c.l, s))
          return (0);
        cc = c->v.c.r;
        break;
      case clNode_diff:
        return (class_matchCommand(c->v.c.l, s) &&
                !class_matchCommand(c->v.c.r, s));
        break;
    }
  }

  die("internal error: can't get here in class_matchCommand");
  return (0);
}

/* --- @class_matchHost@ --- *
 *
 * Arguments:   @class_node *c@ = pointer to root class node
 *              @struct in_addr a@ = IP address to match
 *
 * Returns:     Nonzero if it matches, zero if it doesn't.
 *
 * Use:         Determines whether a host matches a host class.  Assumes
 *              that the types are correct.  The actual mechanism is a bit
 *              odd here, but I think this is the Right Thing.  At each stage
 *              I try to match %%@/all/%% of the possible names for the host.
 *              Thus host `splat' with address 1.2.3.4 would fail to match
 *              the class "1.2.*" - "splat".  This seems to be what the
 *              author intuitively expects.  It's just a bit weird.
 */

static int class__doMatchHost(class_node *c, const char *ip,
                              const char *name, char **aliases)
{
  class_node *cc;

  for (cc = 0; c; c = cc, cc = 0) {
    if (c == class_none)
      return (0);
    if (c == class_all)
      return (1);
    switch (c->type & clNode_mask) {
      case clNode_immed:
        if ((ip && class__wildMatch(c->v.s, ip)) ||
            (name && class__wildMatch(c->v.s, name)))
          return (1);
        if (aliases) for (; *aliases; aliases++) {
          if (class__wildMatch(c->v.s, *aliases))
            return (1);
        }
        return (0);
        break;
      case clNode_hash:
        if ((ip && sym_find(&c->v.t, ip, -1, 0, 0)) ||
            (name && sym_find(&c->v.t, name, -1, 0, 0)))
          return (1);
        if (aliases) for (; *aliases; aliases++) {
          if (sym_find(&c->v.t, *aliases, -1, 0, 0))
            return (1);
        }
        return (0);
        break;
      case clNode_union:
        if (class__doMatchHost(c->v.c.l, ip, name, aliases))
          return (1);
        cc = c->v.c.r;
        break;
      case clNode_isect:
        if (!class__doMatchHost(c->v.c.l, ip, name, aliases))
          return (0);
        cc = c->v.c.r;
        break;
      case clNode_diff:
        return (class__doMatchHost(c->v.c.l, ip, name, aliases) &&
                !class__doMatchHost(c->v.c.r, ip, name, aliases));
        break;
    }
  }

  die("internal error: can't get here in class_matchUser");
  return (0);
}  

int class_matchHost(class_node *c, struct in_addr a)
{
  char *ip, *name, **aliases;
  struct hostent *h;

  ip = inet_ntoa(a);
  if ((h = gethostbyaddr((char *)&a, sizeof(a), AF_INET)) != 0) {
    name = h->h_name;
    aliases = h->h_aliases;
  } else {
    name = 0;
    aliases = 0;
  }

  return (class__doMatchHost(c, ip, name, aliases));
}

/*----- Debugging code ----------------------------------------------------*/

/* --- @class_dump@ --- *
 *
 * Argumemnts:  @class_node *c@ = pointer to root node
 *              @int indent@ = indent depth
 *
 * Returns:     ---
 *
 * Use:         Dumps a class to the trace output.
 */

void class_dump(class_node *c, int indent)
{
#ifdef TRACING

  static char *types[] = {
    "<duff>",
    "user",
    "command",
    "<duff>",
    "host"
  };

  static char *nodes[] = {
    "<duff>",
    "<magical>",
    "immediate",
    "hash",
    "binop: union",
    "binop: difference",
    "binop: intersection"
  };

  /* --- Handle some magical cases --- */

  if (c == class_all) {
    trace(TRACE_RULE, "rule:%*s class ALL", indent * 2, "");
    return;
  }
  if (c == class_none) {
    trace(TRACE_RULE, "rule:%*s class NONE", indent * 2, "");
    return;
  }

  /* --- Dump basic type information --- */

  trace(TRACE_RULE, "rule:%*s type == [%s], node type == [%s]%s",
        indent * 2, "",
        types[c->type & clType_mask],
        nodes[(c->type & clNode_mask) >> 4],
        (c->type & clFlag_friendly) ? " Friendly" : "");

  /* --- Now trace the contents --- */

  switch (c->type & clNode_mask) {
    case clNode_immed:
      if (c->type & clType_user) {
        trace(TRACE_RULE, "rule:%*s   user %lu",
              indent * 2, "", (unsigned long)c->v.u);
      } else
        trace(TRACE_RULE, "rule:%*s   `%s'", indent * 2, "", c->v.s);
      break;
    case clNode_hash: {
      sym_iter i;
      sym_base *b;

      for (sym_createIter(&i, &c->v.t); (b = sym_next(&i)) != 0; ) {
        if (c->type & clType_user) {
          trace(TRACE_RULE, "rule:%*s   user %lu",
                indent * 2, "", (unsigned long)*(uid_t *)b->name);
        } else
          trace(TRACE_RULE, "rule:%*s   `%s'", indent * 2, "", b->name);
      }
    } break;
    case clNode_union:
    case clNode_diff:
    case clNode_isect:
      class_dump(c->v.c.l, indent + 1);
      class_dump(c->v.c.r, indent + 1);
      break;
  }

#endif
}

/*----- That's all, folks -------------------------------------------------*/