source4/lib/socket/interface.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3
   4    multiple interface handling
   5
   6    Copyright (C) Andrew Tridgell 1992-2005
   7
   8    This program is free software; you can redistribute it and/or modify
   9    it under the terms of the GNU General Public License as published by
  10    the Free Software Foundation; either version 3 of the License, or
  11    (at your option) any later version.
  12
  13    This program is distributed in the hope that it will be useful,
  14    but WITHOUT ANY WARRANTY; without even the implied warranty of
  15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16    GNU General Public License for more details.
  17
  18    You should have received a copy of the GNU General Public License
  19    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  20 */
  21
  22 #include "includes.h"
  23 #include "system/network.h"
  24 #include "lib/socket/netif.h"
  25 #include "../lib/util/util_net.h"
  26 #include "../lib/util/dlinklist.h"
  27
  28 /** used for network interfaces */
  29 struct interface {
  30         struct interface *next, *prev;
  31         struct in_addr ip;
  32         struct in_addr nmask;
  33         const char *ip_s;
  34         const char *bcast_s;
  35         const char *nmask_s;
  36 };
  37
  38 #define ALLONES  ((uint32_t)0xFFFFFFFF)
  39 /*
  40   address construction based on a patch from fred@datalync.com
  41 */
  42 #define MKBCADDR(_IP, _NM) ((_IP & _NM) | (_NM ^ ALLONES))
  43 #define MKNETADDR(_IP, _NM) (_IP & _NM)
  44
  45 /****************************************************************************
  46 Try and find an interface that matches an ip. If we cannot, return NULL
  47   **************************************************************************/
  48 static struct interface *iface_find(struct interface *interfaces,
  49                                     struct in_addr ip, bool CheckMask)
  50 {
  51         struct interface *i;
  52         if (is_zero_ip_v4(ip)) return interfaces;
  53
  54         for (i=interfaces;i;i=i->next)
  55                 if (CheckMask) {
  56                         if (same_net_v4(i->ip,ip,i->nmask)) return i;
  57                 } else if (i->ip.s_addr == ip.s_addr) return i;
  58
  59         return NULL;
  60 }
  61
  62
  63 /****************************************************************************
  64 add an interface to the linked list of interfaces
  65 ****************************************************************************/
  66 static void add_interface(TALLOC_CTX *mem_ctx, struct in_addr ip, struct in_addr nmask, struct interface **interfaces)
  67 {
  68         struct interface *iface;
  69         struct in_addr bcast;
  70
  71         if (iface_find(*interfaces, ip, false)) {
  72                 DEBUG(3,("not adding duplicate interface %s\n",inet_ntoa(ip)));
  73                 return;
  74         }
  75
  76         iface = talloc(*interfaces == NULL ? mem_ctx : *interfaces, struct interface);
  77         if (iface == NULL)
  78                 return;
  79
  80         ZERO_STRUCTPN(iface);
  81
  82         iface->ip = ip;
  83         iface->nmask = nmask;
  84         bcast.s_addr = MKBCADDR(iface->ip.s_addr, iface->nmask.s_addr);
  85
  86         /* keep string versions too, to avoid people tripping over the implied
  87            static in inet_ntoa() */
  88         iface->ip_s = talloc_strdup(iface, inet_ntoa(iface->ip));
  89         iface->nmask_s = talloc_strdup(iface, inet_ntoa(iface->nmask));
  90
  91         if (nmask.s_addr != ~0) {
  92                 iface->bcast_s = talloc_strdup(iface, inet_ntoa(bcast));
  93         }
  94
  95         DLIST_ADD_END(*interfaces, iface, struct interface *);
  96
  97         DEBUG(3,("added interface ip=%s nmask=%s\n", iface->ip_s, iface->nmask_s));
  98 }
  99
 100
 101
 102 /**
 103 interpret a single element from a interfaces= config line
 104
 105 This handles the following different forms:
 106
 107 1) wildcard interface name
 108 2) DNS name
 109 3) IP/masklen
 110 4) ip/mask
 111 5) bcast/mask
 112 **/
 113 static void interpret_interface(TALLOC_CTX *mem_ctx,
 114                                 const char *token,
 115                                 struct iface_struct *probed_ifaces,
 116                                 int total_probed,
 117                                 struct interface **local_interfaces)
 118 {
 119         struct in_addr ip, nmask;
 120         char *p;
 121         char *address;
 122         int i, added=0;
 123
 124         ip.s_addr = 0;
 125         nmask.s_addr = 0;
 126
 127         /* first check if it is an interface name */
 128         for (i=0;i<total_probed;i++) {
 129                 if (gen_fnmatch(token, probed_ifaces[i].name) == 0) {
 130                         add_interface(mem_ctx, probed_ifaces[i].ip,
 131                                       probed_ifaces[i].netmask,
 132                                       local_interfaces);
 133                         added = 1;
 134                 }
 135         }
 136         if (added) return;
 137
 138         /* maybe it is a DNS name */
 139         p = strchr_m(token,'/');
 140         if (!p) {
 141                 /* don't try to do dns lookups on wildcard names */
 142                 if (strpbrk(token, "*?") != NULL) {
 143                         return;
 144                 }
 145                 ip.s_addr = interpret_addr2(token).s_addr;
 146                 for (i=0;i<total_probed;i++) {
 147                         if (ip.s_addr == probed_ifaces[i].ip.s_addr) {
 148                                 add_interface(mem_ctx, probed_ifaces[i].ip,
 149                                               probed_ifaces[i].netmask,
 150                                               local_interfaces);
 151                                 return;
 152                         }
 153                 }
 154                 DEBUG(2,("can't determine netmask for %s\n", token));
 155                 return;
 156         }
 157
 158         address = talloc_strdup(mem_ctx, token);
 159         p = strchr_m(address,'/');
 160
 161         /* parse it into an IP address/netmasklength pair */
 162         *p++ = 0;
 163
 164         ip.s_addr = interpret_addr2(address).s_addr;
 165
 166         if (strlen(p) > 2) {
 167                 nmask.s_addr = interpret_addr2(p).s_addr;
 168         } else {
 169                 nmask.s_addr = htonl(((ALLONES >> atoi(p)) ^ ALLONES));
 170         }
 171
 172         /* maybe the first component was a broadcast address */
 173         if (ip.s_addr == MKBCADDR(ip.s_addr, nmask.s_addr) ||
 174             ip.s_addr == MKNETADDR(ip.s_addr, nmask.s_addr)) {
 175                 for (i=0;i<total_probed;i++) {
 176                         if (same_net_v4(ip, probed_ifaces[i].ip, nmask)) {
 177                                 add_interface(mem_ctx, probed_ifaces[i].ip, nmask,
 178                                               local_interfaces);
 179                                 talloc_free(address);
 180                                 return;
 181                         }
 182                 }
 183                 DEBUG(2,("Can't determine ip for broadcast address %s\n", address));
 184                 talloc_free(address);
 185                 return;
 186         }
 187
 188         add_interface(mem_ctx, ip, nmask, local_interfaces);
 189         talloc_free(address);
 190 }
 191
 192
 193 /**
 194 load the list of network interfaces
 195 **/
 196 void load_interfaces(TALLOC_CTX *mem_ctx, const char **interfaces, struct interface **local_interfaces)
 197 {
 198         const char **ptr = interfaces;
 199         int i;
 200         struct iface_struct ifaces[MAX_INTERFACES];
 201         struct in_addr loopback_ip;
 202         int total_probed;
 203
 204         *local_interfaces = NULL;
 205
 206         loopback_ip = interpret_addr2("127.0.0.1");
 207
 208         /* probe the kernel for interfaces */
 209         total_probed = get_interfaces(ifaces, MAX_INTERFACES);
 210
 211         /* if we don't have a interfaces line then use all interfaces
 212            except loopback */
 213         if (!ptr || !*ptr || !**ptr) {
 214                 if (total_probed <= 0) {
 215                         DEBUG(0,("ERROR: Could not determine network interfaces, you must use a interfaces config line\n"));
 216                 }
 217                 for (i=0;i<total_probed;i++) {
 218                         if (ifaces[i].ip.s_addr != loopback_ip.s_addr) {
 219                                 add_interface(mem_ctx, ifaces[i].ip,
 220                                               ifaces[i].netmask, local_interfaces);
 221                         }
 222                 }
 223         }
 224
 225         while (ptr && *ptr) {
 226                 interpret_interface(mem_ctx, *ptr, ifaces, total_probed, local_interfaces);
 227                 ptr++;
 228         }
 229
 230         if (!*local_interfaces) {
 231                 DEBUG(0,("WARNING: no network interfaces found\n"));
 232         }
 233 }
 234
 235 /**
 236   how many interfaces do we have
 237   **/
 238 int iface_count(struct interface *ifaces)
 239 {
 240         int ret = 0;
 241         struct interface *i;
 242
 243         for (i=ifaces;i;i=i->next)
 244                 ret++;
 245         return ret;
 246 }
 247
 248 /**
 249   return IP of the Nth interface
 250   **/
 251 const char *iface_n_ip(struct interface *ifaces, int n)
 252 {
 253         struct interface *i;
 254
 255         for (i=ifaces;i && n;i=i->next)
 256                 n--;
 257
 258         if (i) {
 259                 return i->ip_s;
 260         }
 261         return NULL;
 262 }
 263
 264 /**
 265   return bcast of the Nth interface
 266   **/
 267 const char *iface_n_bcast(struct interface *ifaces, int n)
 268 {
 269         struct interface *i;
 270
 271         for (i=ifaces;i && n;i=i->next)
 272                 n--;
 273
 274         if (i) {
 275                 return i->bcast_s;
 276         }
 277         return NULL;
 278 }
 279
 280 /**
 281   return netmask of the Nth interface
 282   **/
 283 const char *iface_n_netmask(struct interface *ifaces, int n)
 284 {
 285         struct interface *i;
 286
 287         for (i=ifaces;i && n;i=i->next)
 288                 n--;
 289
 290         if (i) {
 291                 return i->nmask_s;
 292         }
 293         return NULL;
 294 }
 295
 296 /**
 297   return the local IP address that best matches a destination IP, or
 298   our first interface if none match
 299 */
 300 const char *iface_best_ip(struct interface *ifaces, const char *dest)
 301 {
 302         struct interface *iface;
 303         struct in_addr ip;
 304
 305         ip.s_addr = interpret_addr(dest);
 306         iface = iface_find(ifaces, ip, true);
 307         if (iface) {
 308                 return iface->ip_s;
 309         }
 310         return iface_n_ip(ifaces, 0);
 311 }
 312
 313 /**
 314   return true if an IP is one one of our local networks
 315 */
 316 bool iface_is_local(struct interface *ifaces, const char *dest)
 317 {
 318         struct in_addr ip;
 319
 320         ip.s_addr = interpret_addr(dest);
 321         if (iface_find(ifaces, ip, true)) {
 322                 return true;
 323         }
 324         return false;
 325 }
 326
 327 /**
 328   return true if a IP matches a IP/netmask pair
 329 */
 330 bool iface_same_net(const char *ip1, const char *ip2, const char *netmask)
 331 {
 332         return same_net_v4(interpret_addr2(ip1),
 333                         interpret_addr2(ip2),
 334                         interpret_addr2(netmask));
 335 }