lib/interface.c

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/* 
   Unix SMB/CIFS implementation.
   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;

#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 !defined(__s390__)
        if (ip_equal(nmask, allones_ip)) {
                DEBUG(3,("not adding non-broadcast interface %s\n",inet_ntoa(ip)));
                return;
        }
#endif

        iface = SMB_MALLOC_P(struct interface);
        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;

        zero_ip(&ip);
        zero_ip(&nmask);
        
        /* first check if it is an interface name */
        for (i=0;i<total_probed;i++) {
                if (gen_fnmatch(token, probed_ifaces[i].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_m(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);
        *p++ = '/';

        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;
        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 = (struct iface_struct *)memdup(ifaces, sizeof(ifaces[0])*total_probed);
                if (!probed_ifaces) {
                        DEBUG(0,("ERROR: memdup failed\n"));
                        exit(1);
                }
        }

        /* if we don't have a interfaces line then use all broadcast capable 
           interfaces except loopback */
        if (!ptr || !*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 (
#if !defined(__s390__)
                            probed_ifaces[i].netmask.s_addr != allones_ip.s_addr &&
#endif
                            probed_ifaces[i].ip.s_addr != loopback_ip.s_addr) {
                                add_interface(probed_ifaces[i].ip, 
                                              probed_ifaces[i].netmask);
                        }
                }
                return;
        }

        if (ptr) {
                while (*ptr) {
                        char *ptr_cpy = SMB_STRDUP(*ptr);
                        if (ptr_cpy) {
                                interpret_interface(ptr_cpy);
                                free(ptr_cpy);
                        }
                        ptr++;
                }
        }

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


void gfree_interfaces(void)
{
        while (local_interfaces) {
                struct interface *iface = local_interfaces;
                DLIST_REMOVE(local_interfaces, local_interfaces);
                ZERO_STRUCTPN(iface);
                SAFE_FREE(iface);
        }

        SAFE_FREE(probed_ifaces);
}

/****************************************************************************
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;
}

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

        for (i=local_interfaces;i;i=i->next) {
                if (ip_equal(i->ip, loopback_ip)) {
                        continue;
                }
                ret++;
        }
        return ret;
}

/****************************************************************************
  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;
}


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

/*
  return True if a IP is directly reachable on one of our interfaces
*/
BOOL iface_local(struct in_addr ip)
{
        return iface_find(ip, True) ? True : False;
}

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