mdw@git.distorted.org.uk Git - fwd/blob - acl.c

   1 /* -*-c-*-
   2  *
   3  * Access control list handling
   4  *
   5  * (c) 1999 Straylight/Edgeware
   6  */
   7
   8 /*----- Licensing notice --------------------------------------------------*
   9  *
  10  * This file is part of the `fwd' port forwarder.
  11  *
  12  * `fwd' is free software; you can redistribute it and/or modify
  13  * it under the terms of the GNU General Public License as published by
  14  * the Free Software Foundation; either version 2 of the License, or
  15  * (at your option) any later version.
  16  *
  17  * `fwd' is distributed in the hope that it will be useful,
  18  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  19  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  20  * GNU General Public License for more details.
  21  *
  22  * You should have received a copy of the GNU General Public License
  23  * along with `fwd'; if not, write to the Free Software Foundation,
  24  * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  25  */
  26
  27 #include "fwd.h"
  28
  29 /*----- Main code ---------------------------------------------------------*/
  30
  31 /* --- @acl_addhost@ --- *
  32  *
  33  * Arguments:   @acl_entry ***a@ = address of pointer to list tail
  34  *              @unsigned act@ = what to do with matching addresses
  35  *              @struct in_addr addr, mask@ = address and mask to match
  36  *
  37  * Returns:     ---
  38  *
  39  * Use:         Adds a host-authentication entry to the end of an access
  40  *              control list.
  41  */
  42
  43 static int acl_checkhost(void *aa, struct in_addr addr, unsigned port)
  44 {
  45   acl_host *a = aa;
  46   return ((addr.s_addr & a->mask.s_addr) == a->addr.s_addr);
  47 }
  48
  49 static void acl_dumphost(void *aa, FILE *fp)
  50 {
  51   acl_host *a = aa;
  52
  53   fputs("from ", fp);
  54   fputs(inet_ntoa(a->addr), fp);
  55   fputc('/', fp);
  56   fputs(inet_ntoa(a->mask), fp);
  57 }
  58
  59 static void acl_freehost(void *aa)
  60 {
  61   acl_host *a = aa;
  62   DESTROY(a);
  63 }
  64
  65 static const acl_ops acl_hostops = {
  66   acl_checkhost, acl_dumphost, acl_freehost
  67 };
  68
  69 void acl_addhost(acl_entry ***a, unsigned act,
  70                  struct in_addr addr, struct in_addr mask)
  71 {
  72   acl_host *aa = CREATE(acl_host);
  73   aa->a.next = 0;
  74   aa->a.ops = &acl_hostops;
  75   aa->a.act = act;
  76   aa->addr.s_addr = addr.s_addr & mask.s_addr;
  77   aa->mask = mask;
  78   **a = &aa->a;
  79   *a = &aa->a.next;
  80 }
  81
  82 /* --- @acl_addpriv@ --- *
  83  *
  84  * Arguments:   @acl_entry ***a@ = address of pointer to list tail
  85  *              @unsigned act@ = what to do with matching addresses
  86  *
  87  * Returns:     ---
  88  *
  89  * Use:         Adds a privileged-port check to the end of an access control
  90  *              list.
  91  */
  92
  93 static int acl_checkpriv(void *aa, struct in_addr addr, unsigned port)
  94 {
  95   return (port < 1024);
  96 }
  97
  98 static void acl_dumppriv(void *aa, FILE *fp)
  99 {
 100   fputs("from privileged ports", fp);
 101 }
 102
 103 static void acl_freepriv(void *aa)
 104 {
 105   acl_entry *a = aa;
 106   DESTROY(a);
 107 }
 108
 109 static const acl_ops acl_privops = {
 110   acl_checkpriv, acl_dumppriv, acl_freepriv
 111 };
 112
 113 void acl_addpriv(acl_entry ***a, unsigned act)
 114 {
 115   acl_entry *aa = CREATE(acl_entry);
 116   aa->next = 0;
 117   aa->ops = &acl_privops;
 118   aa->act = act;
 119   **a = aa;
 120   *a = &aa->next;
 121 }
 122
 123 /* --- @acl_check@ --- *
 124  *
 125  * Arguments:   @acl_entry *a@ = pointer to ACL to check against
 126  *              @struct in_addr addr@ = address to check
 127  *              @unsigned port@ = port number to check
 128  *              @int *act@ = verdict (should initially be @ACT_ALLOW@)
 129  *
 130  * Returns:     Zero if undecided, nonzero if a rule matched.
 131  *
 132  * Use:         Checks an address against an ACL.
 133  */
 134
 135 int acl_check(acl_entry *a, struct in_addr addr, unsigned port, int *act)
 136 {
 137   for (; a; a = a->next) {
 138     if (a->ops->check(a, addr, port)) {
 139       *act = a->act & ACL_PERM;
 140       return (1);
 141     }
 142     *act = (a->act & ACL_PERM) ^ 1;
 143   }
 144   return (0);
 145 }
 146
 147 /* --- @acl_dump@ --- *
 148  *
 149  * Arguments:   @acl_entry *a@ = pointer to ACL to dump
 150  *              @FILE *fp@ = pointer to stream to dump on
 151  *
 152  * Returns:     ---
 153  *
 154  * Use:         Dumps an access control list to an output stream.
 155  */
 156
 157 void acl_dump(acl_entry *a, FILE *fp)
 158 {
 159   for (; a; a = a->next) {
 160     fprintf(fp, "  %s ",
 161             (a->act & ACL_PERM) == ACL_ALLOW ? "allow" : "deny");
 162     a->ops->dump(a, fp);
 163     fputc('\n', fp);
 164   }
 165 }
 166
 167 /* --- @acl_free@ --- *
 168  *
 169  * Arguments:   @acl_entry *a@ = pointer to a list of ACLs
 170  *
 171  * Returns:     ---
 172  *
 173  * Use:         Frees all of the memory used by an ACL.
 174  */
 175
 176 void acl_free(acl_entry *a)
 177 {
 178   while (a) {
 179     acl_entry *aa = a;
 180     a = a->next;
 181     aa->ops->free(aa);
 182   }
 183 }
 184
 185 /*----- That's all, folks -------------------------------------------------*/