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interface.c

/* 
   Unix SMB/Netbios implementation.
   Version 1.9.
   multiple interface handling
   Copyright (C) Andrew Tridgell 1992-1998
   
   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2 of the License, or
   (at your option) any later version.
   
   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.
   
   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/

#include "includes.h"

static struct iface_struct *probed_ifaces;
static int total_probed;

struct in_addr allones_ip;
struct in_addr loopback_ip;

static struct interface *local_interfaces  = NULL;

#define ALLONES  ((uint32)0xFFFFFFFF)
#define MKBCADDR(_IP, _NM) ((_IP & _NM) | (_NM ^ ALLONES))
#define MKNETADDR(_IP, _NM) (_IP & _NM)

/****************************************************************************
Try and find an interface that matches an ip. If we cannot, return NULL
  **************************************************************************/
static struct interface *iface_find(struct in_addr ip, BOOL CheckMask)
{
      struct interface *i;
      if (is_zero_ip(ip))
            return local_interfaces;

      for (i=local_interfaces;i;i=i->next)
            if (CheckMask) {
                  if (same_net(i->ip,ip,i->nmask)) return i;
            } else if ((i->ip).s_addr == ip.s_addr) return i;

      return NULL;
}


/****************************************************************************
add an interface to the linked list of interfaces
****************************************************************************/
static void add_interface(struct in_addr ip, struct in_addr nmask)
{
      struct interface *iface;
      if (iface_find(ip, False)) {
            DEBUG(3,("not adding duplicate interface %s\n",inet_ntoa(ip)));
            return;
      }

      if (ip_equal(nmask, allones_ip)) {
            DEBUG(3,("not adding non-broadcast interface %s\n",inet_ntoa(ip)));
            return;
      }

      iface = (struct interface *)malloc(sizeof(*iface));
      if (!iface) return;
      
      ZERO_STRUCTPN(iface);

      iface->ip = ip;
      iface->nmask = nmask;
      iface->bcast.s_addr = MKBCADDR(iface->ip.s_addr, iface->nmask.s_addr);

      DLIST_ADD(local_interfaces, iface);

      DEBUG(2,("added interface ip=%s ",inet_ntoa(iface->ip)));
      DEBUG(2,("bcast=%s ",inet_ntoa(iface->bcast)));
      DEBUG(2,("nmask=%s\n",inet_ntoa(iface->nmask)));           
}



/****************************************************************************
interpret a single element from a interfaces= config line 

This handles the following different forms:

1) wildcard interface name
2) DNS name
3) IP/masklen
4) ip/mask
5) bcast/mask
****************************************************************************/
static void interpret_interface(char *token)
{
      struct in_addr ip, nmask;
      char *p;
      int i, added=0;
      pstring dos_token, dos_name;

      zero_ip(&ip);
      zero_ip(&nmask);
      
      /* first check if it is an interface name */
      for (i=0;i<total_probed;i++) {
            unix_to_dos(dos_token, token);
            unix_to_dos(dos_name, probed_ifaces[i].name);
            if (ms_fnmatch(dos_token, dos_name) == 0) {
                  add_interface(probed_ifaces[i].ip,
                              probed_ifaces[i].netmask);
                  added = 1;
            }
      }
      if (added) return;

      /* maybe it is a DNS name */
      p = strchr(token,'/');
      if (!p) {
            ip = *interpret_addr2(token);
            for (i=0;i<total_probed;i++) {
                  if (ip.s_addr == probed_ifaces[i].ip.s_addr &&
                      !ip_equal(allones_ip, probed_ifaces[i].netmask)) {
                        add_interface(probed_ifaces[i].ip,
                                    probed_ifaces[i].netmask);
                        return;
                  }
            }
            DEBUG(2,("can't determine netmask for %s\n", token));
            return;
      }

      /* parse it into an IP address/netmasklength pair */
      *p++ = 0;

      ip = *interpret_addr2(token);

      if (strlen(p) > 2) {
            nmask = *interpret_addr2(p);
      } else {
            nmask.s_addr = htonl(((ALLONES >> atoi(p)) ^ ALLONES));
      }

      /* maybe the first component was a broadcast address */
      if (ip.s_addr == MKBCADDR(ip.s_addr, nmask.s_addr) ||
          ip.s_addr == MKNETADDR(ip.s_addr, nmask.s_addr)) {
            for (i=0;i<total_probed;i++) {
                  if (same_net(ip, probed_ifaces[i].ip, nmask)) {
                        add_interface(probed_ifaces[i].ip, nmask);
                        return;
                  }
            }
            DEBUG(2,("Can't determine ip for broadcast address %s\n", token));
            return;
      }

      add_interface(ip, nmask);
}


/****************************************************************************
load the list of network interfaces
****************************************************************************/
void load_interfaces(void)
{
      const char *ptr;
      fstring token;
      int i;
      struct iface_struct ifaces[MAX_INTERFACES];

      ptr = lp_interfaces();

      allones_ip = *interpret_addr2("255.255.255.255");
      loopback_ip = *interpret_addr2("127.0.0.1");

      SAFE_FREE(probed_ifaces);

      /* dump the current interfaces if any */
      while (local_interfaces) {
            struct interface *iface = local_interfaces;
            DLIST_REMOVE(local_interfaces, local_interfaces);
            ZERO_STRUCTPN(iface);
            SAFE_FREE(iface);
      }

      /* probe the kernel for interfaces */
      total_probed = get_interfaces(ifaces, MAX_INTERFACES);

      if (total_probed > 0) {
            probed_ifaces = memdup(ifaces, sizeof(ifaces[0])*total_probed);
      }

      /* if we don't have a interfaces line then use all broadcast capable 
         interfaces except loopback */
      if (!ptr || !*ptr) {
            if (total_probed <= 0) {
                  DEBUG(0,("ERROR: Could not determine network interfaces, you must use a interfaces config line\n"));
                  exit(1);
            }
            for (i=0;i<total_probed;i++) {
                  if (probed_ifaces[i].netmask.s_addr != allones_ip.s_addr &&
                      probed_ifaces[i].ip.s_addr != loopback_ip.s_addr) {
                        add_interface(probed_ifaces[i].ip, 
                                    probed_ifaces[i].netmask);
                  }
            }
            return;
      }

      while (next_token(&ptr,token,NULL,sizeof(token))) {
            interpret_interface(token);
      }

      if (!local_interfaces) {
            DEBUG(0,("WARNING: no network interfaces found\n"));
      }
}


/****************************************************************************
return True if the list of probed interfaces has changed
****************************************************************************/
BOOL interfaces_changed(void)
{
      int n;
      struct iface_struct ifaces[MAX_INTERFACES];

      n = get_interfaces(ifaces, MAX_INTERFACES);

      if ((n > 0 )&& (n != total_probed ||
          memcmp(ifaces, probed_ifaces, sizeof(ifaces[0])*n))) {
            return True;
      }
      
      return False;
}


/****************************************************************************
  check if an IP is one of mine
  **************************************************************************/
BOOL ismyip(struct in_addr ip)
{
      struct interface *i;
      for (i=local_interfaces;i;i=i->next)
            if (ip_equal(i->ip,ip)) return True;
      return False;
}

/****************************************************************************
  check if a packet is from a local (known) net
  **************************************************************************/
BOOL is_local_net(struct in_addr from)
{
      struct interface *i;
      for (i=local_interfaces;i;i=i->next) {
            if((from.s_addr & i->nmask.s_addr) == 
               (i->ip.s_addr & i->nmask.s_addr))
                  return True;
      }
      return False;
}

/****************************************************************************
  how many interfaces do we have
  **************************************************************************/
int iface_count(void)
{
      int ret = 0;
      struct interface *i;

      for (i=local_interfaces;i;i=i->next)
            ret++;
      return ret;
}

/****************************************************************************
 True if we have two or more interfaces.
  **************************************************************************/
BOOL we_are_multihomed(void)
{
      static int multi = -1;

      if(multi == -1)
            multi = (iface_count() > 1 ? True : False);
      
      return multi;
}

/****************************************************************************
  return the Nth interface
  **************************************************************************/
struct interface *get_interface(int n)
{ 
      struct interface *i;
  
      for (i=local_interfaces;i && n;i=i->next)
            n--;

      if (i) return i;
      return NULL;
}

/****************************************************************************
  return IP of the Nth interface
  **************************************************************************/
struct in_addr *iface_n_ip(int n)
{
      struct interface *i;
  
      for (i=local_interfaces;i && n;i=i->next)
            n--;

      if (i) return &i->ip;
      return NULL;
}

/****************************************************************************
  return bcast of the Nth interface
  **************************************************************************/
struct in_addr *iface_n_bcast(int n)
{
      struct interface *i;
  
      for (i=local_interfaces;i && n;i=i->next)
            n--;

      if (i) return &i->bcast;
      return NULL;
}


/****************************************************************************
this function provides a simple hash of the configured interfaces. It is
used to detect a change in interfaces to tell us whether to discard
the current wins.dat file.
Note that the result is independent of the order of the interfaces
  **************************************************************************/
unsigned iface_hash(void)
{
      unsigned ret = 0;
      struct interface *i;

      for (i=local_interfaces;i;i=i->next) {
            unsigned x1 = (unsigned)str_checksum(inet_ntoa(i->ip));
            unsigned x2 = (unsigned)str_checksum(inet_ntoa(i->nmask));
            ret ^= (x1 ^ x2);
      }

      return ret;
}


/* these 3 functions return the ip/bcast/nmask for the interface
   most appropriate for the given ip address. If they can't find
   an appropriate interface they return the requested field of the
   first known interface. */

struct in_addr *iface_bcast(struct in_addr ip)
{
      struct interface *i = iface_find(ip, True);
      return(i ? &i->bcast : &local_interfaces->bcast);
}

struct in_addr *iface_ip(struct in_addr ip)
{
      struct interface *i = iface_find(ip, True);
      return(i ? &i->ip : &local_interfaces->ip);
}

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