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

   1 /* -*-c-*-
   2  *
   3  * $Id: acl.c,v 1.3 1999/07/27 18:30:53 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 1.3  1999/07/27 18:30:53  mdw
  33  * Various minor portability fixes.
  34  *
  35  * Revision 1.2  1999/07/26 23:28:15  mdw
  36  * Minor modifications for new design.
  37  *
  38  * Revision 1.1.1.1  1999/07/01 08:56:23  mdw
  39  * Initial revision.
  40  *
  41  */
  42
  43 /*----- Header files ------------------------------------------------------*/
  44
  45 #include "config.h"
  46
  47 #include <errno.h>
  48 #include <stdio.h>
  49 #include <stdlib.h>
  50 #include <string.h>
  51
  52 #include <sys/types.h>
  53 #include <unistd.h>
  54
  55 #include <sys/socket.h>
  56 #include <netinet/in.h>
  57 #include <arpa/inet.h>
  58 #include <netdb.h>
  59
  60 #include <mLib/sub.h>
  61
  62 #include "acl.h"
  63
  64 /*----- Static variables --------------------------------------------------*/
  65
  66 static acl_entry *global = 0;
  67 static acl_entry **gtail = &global;
  68
  69 /*----- Main code ---------------------------------------------------------*/
  70
  71 /* --- @acl_check@ --- *
  72  *
  73  * Arguments:   @acl_entry *a@ = pointer to ACL to check against
  74  *              @struct in_addr addr@ = address to check
  75  *
  76  * Returns:     Nonzero if allowed.
  77  *
  78  * Use:         Checks an address against an ACL.
  79  */
  80
  81 int acl_check(acl_entry *a, struct in_addr addr)
  82 {
  83   int act = ACL_ALLOW;
  84   int i;
  85
  86   for (i = 0; i < 2; i++) {
  87     for (; a; a = a->next) {
  88       if ((addr.s_addr & a->mask.s_addr) == a->addr.s_addr)
  89         return (a->act & ACL_PERM);
  90       act = (a->act & ACL_PERM) ^ 1;
  91     }
  92     a = global;
  93   }
  94
  95   return (act);
  96 }
  97
  98 /* --- @acl_dump@ --- *
  99  *
 100  * Arguments:   @acl_entry *a@ = pointer to ACL to dump
 101  *              @FILE *fp@ = pointer to stream to dump on
 102  *
 103  * Returns:     ---
 104  *
 105  * Use:         Dumps an access control list to an output stream.
 106  */
 107
 108 void acl_dump(acl_entry *a, FILE *fp)
 109 {
 110   if (!a)
 111     a = global;
 112   for (; a; a = a->next) {
 113     fprintf(fp, "  %s from ",
 114             (a->act & ACL_PERM) == ACL_ALLOW ? "allow" : "deny");
 115     fputs(inet_ntoa(a->addr), fp);
 116     fputc('/', fp);
 117     fputs(inet_ntoa(a->mask), fp);
 118     fputc('\n', fp);
 119   }
 120 }
 121
 122 /* --- @acl_free@ --- *
 123  *
 124  * Arguments:   @acl_entry *a@ = pointer to a list of ACLs
 125  *
 126  * Returns:     ---
 127  *
 128  * Use:         Frees all of the memory used by an ACL.
 129  */
 130
 131 void acl_free(acl_entry *a)
 132 {
 133   while (a) {
 134     acl_entry *aa = a;
 135     a = a->next;
 136     DESTROY(aa);
 137   }
 138 }
 139
 140 /* --- @acl_add@ --- *
 141  *
 142  * Arguments:   @acl_entry ***a@ = address of pointer to list tail
 143  *              @unsigned act@ = what to do with matching addresses
 144  *              @struct in_addr addr, mask@ = address and mask to match
 145  *
 146  * Returns:     ---
 147  *
 148  * Use:         Adds an entry to the end of an access control list.
 149  */
 150
 151 void acl_add(acl_entry ***a, unsigned act,
 152              struct in_addr addr, struct in_addr mask)
 153 {
 154   acl_entry *aa = CREATE(acl_entry);
 155   aa->act = act;
 156   aa->addr.s_addr = addr.s_addr & mask.s_addr;
 157   aa->mask = mask;
 158   aa->next = 0;
 159   if (!a)
 160     a = &gtail;
 161   **a = aa;
 162   *a = &aa->next;
 163 }
 164
 165 /*----- That's all, folks -------------------------------------------------*/