source/lib/interface.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3    multiple interface handling
   4    Copyright (C) Andrew Tridgell 1992-1998
   5
   6    This program is free software; you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 2 of the License, or
   9    (at your option) any later version.
  10
  11    This program is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with this program; if not, write to the Free Software
  18    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  19 */
  20
  21 #include "includes.h"
  22
  23 static struct iface_struct *probed_ifaces;
  24 static int total_probed;
  25
  26 struct in_addr allones_ip;
  27 struct in_addr loopback_ip;
  28
  29 static struct interface *local_interfaces;
  30
  31 #define ALLONES  ((uint32)0xFFFFFFFF)
  32 #define MKBCADDR(_IP, _NM) ((_IP & _NM) | (_NM ^ ALLONES))
  33 #define MKNETADDR(_IP, _NM) (_IP & _NM)
  34
  35 /****************************************************************************
  36 Try and find an interface that matches an ip. If we cannot, return NULL
  37   **************************************************************************/
  38 static struct interface *iface_find(struct in_addr ip, BOOL CheckMask)
  39 {
  40         struct interface *i;
  41         if (is_zero_ip(ip)) return local_interfaces;
  42
  43         for (i=local_interfaces;i;i=i->next)
  44                 if (CheckMask) {
  45                         if (same_net(i->ip,ip,i->nmask)) return i;
  46                 } else if ((i->ip).s_addr == ip.s_addr) return i;
  47
  48         return NULL;
  49 }
  50
  51
  52 /****************************************************************************
  53 add an interface to the linked list of interfaces
  54 ****************************************************************************/
  55 static void add_interface(struct in_addr ip, struct in_addr nmask)
  56 {
  57         struct interface *iface;
  58         if (iface_find(ip, False)) {
  59                 DEBUG(3,("not adding duplicate interface %s\n",inet_ntoa(ip)));
  60                 return;
  61         }
  62
  63         if (ip_equal(nmask, allones_ip)) {
  64                 DEBUG(3,("not adding non-broadcast interface %s\n",inet_ntoa(ip)));
  65                 return;
  66         }
  67
  68         iface = (struct interface *)malloc(sizeof(*iface));
  69         if (!iface) return;
  70
  71         ZERO_STRUCTPN(iface);
  72
  73         iface->ip = ip;
  74         iface->nmask = nmask;
  75         iface->bcast.s_addr = MKBCADDR(iface->ip.s_addr, iface->nmask.s_addr);
  76
  77         DLIST_ADD(local_interfaces, iface);
  78
  79         DEBUG(2,("added interface ip=%s ",inet_ntoa(iface->ip)));
  80         DEBUG(2,("bcast=%s ",inet_ntoa(iface->bcast)));
  81         DEBUG(2,("nmask=%s\n",inet_ntoa(iface->nmask)));
  82 }
  83
  84
  85
  86 /****************************************************************************
  87 interpret a single element from a interfaces= config line
  88
  89 This handles the following different forms:
  90
  91 1) wildcard interface name
  92 2) DNS name
  93 3) IP/masklen
  94 4) ip/mask
  95 5) bcast/mask
  96 ****************************************************************************/
  97 static void interpret_interface(char *token)
  98 {
  99         struct in_addr ip, nmask;
 100         char *p;
 101         int i, added=0;
 102
 103         zero_ip(&ip);
 104         zero_ip(&nmask);
 105
 106         /* first check if it is an interface name */
 107         for (i=0;i<total_probed;i++) {
 108                 if (gen_fnmatch(token, probed_ifaces[i].name) == 0) {
 109                         add_interface(probed_ifaces[i].ip,
 110                                       probed_ifaces[i].netmask);
 111                         added = 1;
 112                 }
 113         }
 114         if (added) return;
 115
 116         /* maybe it is a DNS name */
 117         p = strchr_m(token,'/');
 118         if (!p) {
 119                 ip = *interpret_addr2(token);
 120                 for (i=0;i<total_probed;i++) {
 121                         if (ip.s_addr == probed_ifaces[i].ip.s_addr &&
 122                             !ip_equal(allones_ip, probed_ifaces[i].netmask)) {
 123                                 add_interface(probed_ifaces[i].ip,
 124                                               probed_ifaces[i].netmask);
 125                                 return;
 126                         }
 127                 }
 128                 DEBUG(2,("can't determine netmask for %s\n", token));
 129                 return;
 130         }
 131
 132         /* parse it into an IP address/netmasklength pair */
 133         *p = 0;
 134         ip = *interpret_addr2(token);
 135         *p++ = '/';
 136
 137         if (strlen(p) > 2) {
 138                 nmask = *interpret_addr2(p);
 139         } else {
 140                 nmask.s_addr = htonl(((ALLONES >> atoi(p)) ^ ALLONES));
 141         }
 142
 143         /* maybe the first component was a broadcast address */
 144         if (ip.s_addr == MKBCADDR(ip.s_addr, nmask.s_addr) ||
 145             ip.s_addr == MKNETADDR(ip.s_addr, nmask.s_addr)) {
 146                 for (i=0;i<total_probed;i++) {
 147                         if (same_net(ip, probed_ifaces[i].ip, nmask)) {
 148                                 add_interface(probed_ifaces[i].ip, nmask);
 149                                 return;
 150                         }
 151                 }
 152                 DEBUG(2,("Can't determine ip for broadcast address %s\n", token));
 153                 return;
 154         }
 155
 156         add_interface(ip, nmask);
 157 }
 158
 159
 160 /****************************************************************************
 161 load the list of network interfaces
 162 ****************************************************************************/
 163 void load_interfaces(void)
 164 {
 165         const char **ptr;
 166         int i;
 167         struct iface_struct ifaces[MAX_INTERFACES];
 168
 169         ptr = lp_interfaces();
 170
 171         allones_ip = *interpret_addr2("255.255.255.255");
 172         loopback_ip = *interpret_addr2("127.0.0.1");
 173
 174         SAFE_FREE(probed_ifaces);
 175
 176         /* dump the current interfaces if any */
 177         while (local_interfaces) {
 178                 struct interface *iface = local_interfaces;
 179                 DLIST_REMOVE(local_interfaces, local_interfaces);
 180                 ZERO_STRUCTPN(iface);
 181                 SAFE_FREE(iface);
 182         }
 183
 184         /* probe the kernel for interfaces */
 185         total_probed = get_interfaces(ifaces, MAX_INTERFACES);
 186
 187         if (total_probed > 0) {
 188                 probed_ifaces = memdup(ifaces, sizeof(ifaces[0])*total_probed);
 189         }
 190
 191         /* if we don't have a interfaces line then use all broadcast capable
 192            interfaces except loopback */
 193         if (!ptr || !*ptr || !**ptr) {
 194                 if (total_probed <= 0) {
 195                         DEBUG(0,("ERROR: Could not determine network interfaces, you must use a interfaces config line\n"));
 196                         exit(1);
 197                 }
 198                 for (i=0;i<total_probed;i++) {
 199                         if (probed_ifaces[i].netmask.s_addr != allones_ip.s_addr &&
 200                             probed_ifaces[i].ip.s_addr != loopback_ip.s_addr) {
 201                                 add_interface(probed_ifaces[i].ip,
 202                                               probed_ifaces[i].netmask);
 203                         }
 204                 }
 205                 return;
 206         }
 207
 208         if (ptr) {
 209                 while (*ptr) {
 210                         char *ptr_cpy = strdup(*ptr);
 211                         if (ptr_cpy) {
 212                                 interpret_interface(ptr_cpy);
 213                                 free(ptr_cpy);
 214                         }
 215                         ptr++;
 216                 }
 217         }
 218
 219         if (!local_interfaces) {
 220                 DEBUG(0,("WARNING: no network interfaces found\n"));
 221         }
 222 }
 223
 224
 225 /****************************************************************************
 226 return True if the list of probed interfaces has changed
 227 ****************************************************************************/
 228 BOOL interfaces_changed(void)
 229 {
 230         int n;
 231         struct iface_struct ifaces[MAX_INTERFACES];
 232
 233         n = get_interfaces(ifaces, MAX_INTERFACES);
 234
 235         if ((n > 0 )&& (n != total_probed ||
 236             memcmp(ifaces, probed_ifaces, sizeof(ifaces[0])*n))) {
 237                 return True;
 238         }
 239
 240         return False;
 241 }
 242
 243
 244 /****************************************************************************
 245   check if an IP is one of mine
 246   **************************************************************************/
 247 BOOL ismyip(struct in_addr ip)
 248 {
 249         struct interface *i;
 250         for (i=local_interfaces;i;i=i->next)
 251                 if (ip_equal(i->ip,ip)) return True;
 252         return False;
 253 }
 254
 255 /****************************************************************************
 256   check if a packet is from a local (known) net
 257   **************************************************************************/
 258 BOOL is_local_net(struct in_addr from)
 259 {
 260         struct interface *i;
 261         for (i=local_interfaces;i;i=i->next) {
 262                 if((from.s_addr & i->nmask.s_addr) ==
 263                    (i->ip.s_addr & i->nmask.s_addr))
 264                         return True;
 265         }
 266         return False;
 267 }
 268
 269 /****************************************************************************
 270   how many interfaces do we have
 271   **************************************************************************/
 272 int iface_count(void)
 273 {
 274         int ret = 0;
 275         struct interface *i;
 276
 277         for (i=local_interfaces;i;i=i->next)
 278                 ret++;
 279         return ret;
 280 }
 281
 282 /****************************************************************************
 283   return the Nth interface
 284   **************************************************************************/
 285 struct interface *get_interface(int n)
 286 {
 287         struct interface *i;
 288
 289         for (i=local_interfaces;i && n;i=i->next)
 290                 n--;
 291
 292         if (i) return i;
 293         return NULL;
 294 }
 295
 296 /****************************************************************************
 297   return IP of the Nth interface
 298   **************************************************************************/
 299 struct in_addr *iface_n_ip(int n)
 300 {
 301         struct interface *i;
 302
 303         for (i=local_interfaces;i && n;i=i->next)
 304                 n--;
 305
 306         if (i) return &i->ip;
 307         return NULL;
 308 }
 309
 310 /****************************************************************************
 311   return bcast of the Nth interface
 312   **************************************************************************/
 313 struct in_addr *iface_n_bcast(int n)
 314 {
 315         struct interface *i;
 316
 317         for (i=local_interfaces;i && n;i=i->next)
 318                 n--;
 319
 320         if (i) return &i->bcast;
 321         return NULL;
 322 }
 323
 324
 325 /* these 3 functions return the ip/bcast/nmask for the interface
 326    most appropriate for the given ip address. If they can't find
 327    an appropriate interface they return the requested field of the
 328    first known interface. */
 329
 330 struct in_addr *iface_ip(struct in_addr ip)
 331 {
 332         struct interface *i = iface_find(ip, True);
 333         return(i ? &i->ip : &local_interfaces->ip);
 334 }
 335
 336 /*
 337   return True if a IP is directly reachable on one of our interfaces
 338 */
 339 BOOL iface_local(struct in_addr ip)
 340 {
 341         return iface_find(ip, True) ? True : False;
 342 }