acl.c

   1 /*
   2  * Copyright (C) 2005-2008 Andre Noll <maan@systemlinux.org>
   3  *
   4  * Licensed under the GPL v2. For licencing details see COPYING.
   5  */
   6
   7 /** \file acl.c Access control lists for paraslash senders. */
   8
   9 #include "para.h"
  10 #include "error.h"
  11 #include "string.h"
  12 #include "list.h"
  13 #include "net.h"
  14
  15 /**
  16  * Describes one entry in the blacklist/whitelist of a paraslash sender.
  17  */
  18 struct access_info {
  19         /** The address to be black/whitelisted. */
  20         struct in_addr addr;
  21         /** The netmask for this entry. */
  22         unsigned netmask;
  23         /** The position of this entry in the acl. */
  24         struct list_head node;
  25 };
  26
  27
  28 /**
  29  * Return true if addr_1 matches addr_2 in the first `netmask' bits.
  30  */
  31 static int v4_addr_match(uint32_t addr_1, uint32_t addr_2, uint8_t netmask)
  32 {
  33         uint32_t mask = ~0U;
  34
  35         if (netmask < 32)
  36                 mask <<= (32 - netmask);
  37         return (htonl(addr_1) & mask) == (htonl(addr_2) & mask);
  38 }
  39
  40 int acl_lookup(int fd, struct list_head *acl)
  41 {
  42         struct access_info *ai, *tmp;
  43         struct sockaddr_storage ss;
  44         socklen_t sslen = sizeof(ss);
  45         struct in_addr v4_addr;
  46
  47         if (getpeername(fd, (struct sockaddr *)&ss, &sslen) < 0) {
  48                 PARA_ERROR_LOG("Can not determine peer address: %s\n", strerror(errno));
  49                 goto no_match;
  50         }
  51         v4_addr = extract_v4_addr(&ss);
  52         if (!v4_addr.s_addr)
  53                 goto no_match;
  54
  55         list_for_each_entry_safe(ai, tmp, acl, node)
  56                 if (v4_addr_match(v4_addr.s_addr, ai->addr.s_addr, ai->netmask))
  57                         return 1;
  58 no_match:
  59         return 0;
  60 }
  61
  62 void acl_add_entry(struct list_head *acl, struct in_addr addr,
  63                 int netmask)
  64 {
  65         struct access_info *ai = para_malloc(sizeof(struct access_info));
  66         ai->addr = addr;
  67         ai->netmask = netmask;
  68         PARA_INFO_LOG("adding %s/%i to access list\n", inet_ntoa(ai->addr),
  69                 ai->netmask);
  70         para_list_add(&ai->node, acl);
  71 }
  72
  73
  74 void acl_del_entry(struct list_head *acl, struct in_addr addr,
  75                 int netmask)
  76 {
  77         struct access_info *ai, *tmp;
  78
  79         list_for_each_entry_safe(ai, tmp, acl, node) {
  80                 char *nad = para_strdup(inet_ntoa(ai->addr));
  81                 if (!strcmp(nad, inet_ntoa(addr)) &&
  82                                 ai->netmask == netmask) {
  83                         PARA_NOTICE_LOG("removing %s/%i from access list\n",
  84                                 nad, ai->netmask);
  85                         list_del(&ai->node);
  86                         free(ai);
  87                 }
  88                 free(nad);
  89         }
  90 }
  91
  92 char *acl_get_contents(struct list_head *acl)
  93 {
  94         struct access_info *ai, *tmp_ai;
  95         char *ret = NULL;
  96
  97         list_for_each_entry_safe(ai, tmp_ai, acl, node) {
  98                 char *tmp = make_message("%s%s/%d ", ret? ret : "",
  99                         inet_ntoa(ai->addr), ai->netmask);
 100                 free(ret);
 101                 ret = tmp;
 102         }
 103         return ret;
 104 }
 105
 106 void acl_init(struct list_head *acl, char * const *acl_info, int num)
 107 {
 108         int i;
 109
 110         INIT_LIST_HEAD(acl);
 111         for (i = 0; i < num; i++) {
 112                 char *arg = para_strdup(acl_info[i]);
 113                 char *p = strchr(arg, '/');
 114                 struct in_addr addr;
 115                 int netmask;
 116
 117                 if (!p)
 118                         goto err;
 119                 *p = '\0';
 120                 if (!inet_pton(AF_INET, arg, &addr))
 121                         goto err;
 122                 netmask = atoi(++p);
 123                 if (netmask < 0 || netmask > 32)
 124                         goto err;
 125                 acl_add_entry(acl, addr, netmask);
 126                 goto success;
 127 err:
 128                 PARA_CRIT_LOG("syntax error: %s\n", acl_info[i]);
 129 success:
 130                 free(arg);
 131                 continue;
 132         }
 133 }
 134