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

   1 /* -*-c-*-
   2  *
   3  * $Id: acl.c,v 1.2 1999/07/26 23:28:15 mdw Exp $
   4  *
   5  * Access control list handling
   6  *
   7  * (c) 1999 Straylight/Edgeware
   8  */
   9
  10 /*----- Licensing notice --------------------------------------------------*
  11  *
  12  * This file is part of the `fw' port forwarder.
  13  *
  14  * `fw' is free software; you can redistribute it and/or modify
  15  * it under the terms of the GNU General Public License as published by
  16  * the Free Software Foundation; either version 2 of the License, or
  17  * (at your option) any later version.
  18  *
  19  * `fw' is distributed in the hope that it will be useful,
  20  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  21  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  22  * GNU General Public License for more details.
  23  *
  24  * You should have received a copy of the GNU General Public License
  25  * along with `fw'; if not, write to the Free Software Foundation,
  26  * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  27  */
  28
  29 /*----- Revision history --------------------------------------------------*
  30  *
  31  * $Log: acl.c,v $
  32  * Revision 1.2  1999/07/26 23:28:15  mdw
  33  * Minor modifications for new design.
  34  *
  35  * Revision 1.1.1.1  1999/07/01 08:56:23  mdw
  36  * Initial revision.
  37  *
  38  */
  39
  40 /*----- Header files ------------------------------------------------------*/
  41
  42 #include "config.h"
  43
  44 #include <errno.h>
  45 #include <stdio.h>
  46 #include <stdlib.h>
  47 #include <string.h>
  48
  49 #include <sys/socket.h>
  50 #include <netinet/in.h>
  51 #include <arpa/inet.h>
  52 #include <netdb.h>
  53
  54 #include <mLib/sub.h>
  55
  56 #include "acl.h"
  57
  58 /*----- Static variables --------------------------------------------------*/
  59
  60 static acl_entry *global = 0;
  61 static acl_entry **gtail = &global;
  62
  63 /*----- Main code ---------------------------------------------------------*/
  64
  65 /* --- @acl_check@ --- *
  66  *
  67  * Arguments:   @acl_entry *a@ = pointer to ACL to check against
  68  *              @struct in_addr addr@ = address to check
  69  *
  70  * Returns:     Nonzero if allowed.
  71  *
  72  * Use:         Checks an address against an ACL.
  73  */
  74
  75 int acl_check(acl_entry *a, struct in_addr addr)
  76 {
  77   int act = ACL_ALLOW;
  78   int i;
  79
  80   for (i = 0; i < 2; i++) {
  81     for (; a; a = a->next) {
  82       if ((addr.s_addr & a->mask.s_addr) == a->addr.s_addr)
  83         return (a->act & ACL_PERM);
  84       act = (a->act & ACL_PERM) ^ 1;
  85     }
  86     a = global;
  87   }
  88
  89   return (act);
  90 }
  91
  92 /* --- @acl_dump@ --- *
  93  *
  94  * Arguments:   @acl_entry *a@ = pointer to ACL to dump
  95  *              @FILE *fp@ = pointer to stream to dump on
  96  *
  97  * Returns:     ---
  98  *
  99  * Use:         Dumps an access control list to an output stream.
 100  */
 101
 102 void acl_dump(acl_entry *a, FILE *fp)
 103 {
 104   if (!a)
 105     a = global;
 106   for (; a; a = a->next) {
 107     fprintf(fp, "  %s from ",
 108             (a->act & ACL_PERM) == ACL_ALLOW ? "allow" : "deny");
 109     fputs(inet_ntoa(a->addr), fp);
 110     fputc('/', fp);
 111     fputs(inet_ntoa(a->mask), fp);
 112     fputc('\n', fp);
 113   }
 114 }
 115
 116 /* --- @acl_free@ --- *
 117  *
 118  * Arguments:   @acl_entry *a@ = pointer to a list of ACLs
 119  *
 120  * Returns:     ---
 121  *
 122  * Use:         Frees all of the memory used by an ACL.
 123  */
 124
 125 void acl_free(acl_entry *a)
 126 {
 127   while (a) {
 128     acl_entry *aa = a;
 129     a = a->next;
 130     DESTROY(aa);
 131   }
 132 }
 133
 134 /* --- @acl_add@ --- *
 135  *
 136  * Arguments:   @acl_entry ***a@ = address of pointer to list tail
 137  *              @unsigned act@ = what to do with matching addresses
 138  *              @struct in_addr addr, mask@ = address and mask to match
 139  *
 140  * Returns:     ---
 141  *
 142  * Use:         Adds an entry to the end of an access control list.
 143  */
 144
 145 void acl_add(acl_entry ***a, unsigned act,
 146              struct in_addr addr, struct in_addr mask)
 147 {
 148   acl_entry *aa = CREATE(acl_entry);
 149   aa->act = act;
 150   aa->addr.s_addr = addr.s_addr & mask.s_addr;
 151   aa->mask = mask;
 152   aa->next = 0;
 153   if (!a)
 154     a = &gtail;
 155   **a = aa;
 156   *a = &aa->next;
 157 }
 158
 159 /*----- That's all, folks -------------------------------------------------*/