source: branches/samba-3.2.x/source/lib/interface.c

/*
   Unix SMB/CIFS implementation.
   multiple interface handling
   Copyright (C) Andrew Tridgell 1992-1998
   Copyright (C) Jeremy Allison 2007

   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 3 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, see <http://www.gnu.org/licenses/>.
*/

#include "includes.h"

static struct iface_struct *probed_ifaces;
static int total_probed;

static struct interface *local_interfaces;

/****************************************************************************
 Check if an IP is one of mine.
**************************************************************************/

bool ismyaddr(const struct sockaddr_storage *ip)
{
        struct interface *i;
        for (i=local_interfaces;i;i=i->next) {
                if (sockaddr_equal(&i->ip,ip)) {
                        return true;
                }
        }
        return false;
}

bool ismyip_v4(struct in_addr ip)
{
        struct sockaddr_storage ss;
        in_addr_to_sockaddr_storage(&ss, ip);
        return ismyaddr(&ss);
}

/****************************************************************************
 Try and find an interface that matches an ip. If we cannot, return NULL.
**************************************************************************/

static struct interface *iface_find(const struct sockaddr_storage *ip,
                                bool check_mask)
{
        struct interface *i;

        if (is_address_any(ip)) {
                return local_interfaces;
        }

        for (i=local_interfaces;i;i=i->next) {
                if (check_mask) {
                        if (same_net(ip, &i->ip, &i->netmask)) {
                                return i;
                        }
                } else if (sockaddr_equal(&i->ip, ip)) {
                        return i;
                }
        }

        return NULL;
}

/****************************************************************************
 Check if a packet is from a local (known) net.
**************************************************************************/

bool is_local_net(const struct sockaddr_storage *from)
{
        struct interface *i;
        for (i=local_interfaces;i;i=i->next) {
                if (same_net(from, &i->ip, &i->netmask)) {
                        return true;
                }
        }
        return false;
}

#if defined(HAVE_IPV6)
void setup_linklocal_scope_id(struct sockaddr_storage *pss)
{
        struct interface *i;
        for (i=local_interfaces;i;i=i->next) {
                if (sockaddr_equal(&i->ip,pss)) {
                        struct sockaddr_in6 *psa6 =
                                (struct sockaddr_in6 *)pss;
                        psa6->sin6_scope_id = if_nametoindex(i->name);
                        return;
                }
        }
}
#endif

/****************************************************************************
 Check if a packet is from a local (known) net.
**************************************************************************/

bool is_local_net_v4(struct in_addr from)
{
        struct sockaddr_storage ss;

        in_addr_to_sockaddr_storage(&ss, from);
        return is_local_net(&ss);
}

/****************************************************************************
 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 IPv4 interfaces do we have ?
**************************************************************************/

int iface_count_v4_nl(void)
{
        int ret = 0;
        struct interface *i;

        for (i=local_interfaces;i;i=i->next) {
                if (is_loopback_addr(&i->ip)) {
                        continue;
                }
                if (i->ip.ss_family == AF_INET) {
                        ret++;
                }
        }
        return ret;
}

/****************************************************************************
 Return a pointer to the in_addr of the first IPv4 interface that's
 not 0.0.0.0.
**************************************************************************/

const struct in_addr *first_ipv4_iface(void)
{
        struct interface *i;

        for (i=local_interfaces;i ;i=i->next) {
                if ((i->ip.ss_family == AF_INET) &&
                    (!is_zero_ip_v4(((struct sockaddr_in *)&i->ip)->sin_addr)))
                {
                        break;
                }
        }

        if (!i) {
                return NULL;
        }
        return &((const struct sockaddr_in *)&i->ip)->sin_addr;
}

/****************************************************************************
 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 sockaddr_storage of the Nth interface.
**************************************************************************/

const struct sockaddr_storage *iface_n_sockaddr_storage(int n)
{
        struct interface *i;

        for (i=local_interfaces;i && n;i=i->next) {
                n--;
        }

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

/****************************************************************************
 Return IPv4 of the Nth interface (if a v4 address). NULL otherwise.
**************************************************************************/

const struct in_addr *iface_n_ip_v4(int n)
{
        struct interface *i;

        for (i=local_interfaces;i && n;i=i->next) {
                n--;
        }

        if (i && i->ip.ss_family == AF_INET) {
                return &((const struct sockaddr_in *)&i->ip)->sin_addr;
        }
        return NULL;
}

/****************************************************************************
 Return IPv4 bcast of the Nth interface (if a v4 address). NULL otherwise.
**************************************************************************/

const struct in_addr *iface_n_bcast_v4(int n)
{
        struct interface *i;

        for (i=local_interfaces;i && n;i=i->next) {
                n--;
        }

        if (i && i->ip.ss_family == AF_INET) {
                return &((const struct sockaddr_in *)&i->bcast)->sin_addr;
        }
        return NULL;
}

/****************************************************************************
 Return bcast of the Nth interface.
**************************************************************************/

const struct sockaddr_storage *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. */

const struct sockaddr_storage *iface_ip(const struct sockaddr_storage *ip)
{
        struct interface *i = iface_find(ip, true);
        if (i) {
                return &i->ip;
        }

        /* Search for the first interface with
         * matching address family. */

        for (i=local_interfaces;i;i=i->next) {
                if (i->ip.ss_family == ip->ss_family) {
                        return &i->ip;
                }
        }
        return NULL;
}

/*
  return True if a IP is directly reachable on one of our interfaces
*/

bool iface_local(const struct sockaddr_storage *ip)
{
        return iface_find(ip, True) ? true : false;
}

/****************************************************************************
 Add an interface to the linked list of interfaces.
****************************************************************************/

static void add_interface(const struct iface_struct *ifs)
{
        char addr[INET6_ADDRSTRLEN];
        struct interface *iface;

        if (iface_find(&ifs->ip, False)) {
                DEBUG(3,("add_interface: not adding duplicate interface %s\n",
                        print_sockaddr(addr, sizeof(addr), &ifs->ip) ));
                return;
        }

        if (!(ifs->flags & (IFF_BROADCAST|IFF_LOOPBACK))) {
                DEBUG(3,("not adding non-broadcast interface %s\n",
                                        ifs->name ));
                return;
        }

        iface = SMB_MALLOC_P(struct interface);
        if (!iface) {
                return;
        }

        ZERO_STRUCTPN(iface);

        iface->name = SMB_STRDUP(ifs->name);
        if (!iface->name) {
                SAFE_FREE(iface);
                return;
        }
        iface->flags = ifs->flags;
        iface->ip = ifs->ip;
        iface->netmask = ifs->netmask;
        iface->bcast = ifs->bcast;

        DLIST_ADD(local_interfaces, iface);

        DEBUG(2,("added interface %s ip=%s ",
                iface->name,
                print_sockaddr(addr, sizeof(addr), &iface->ip) ));
        DEBUG(2,("bcast=%s ",
                print_sockaddr(addr, sizeof(addr),
                        &iface->bcast) ));
        DEBUG(2,("netmask=%s\n",
                print_sockaddr(addr, sizeof(addr),
                        &iface->netmask) ));
}

/****************************************************************************
 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 sockaddr_storage ss;
        struct sockaddr_storage ss_mask;
        struct sockaddr_storage ss_net;
        struct sockaddr_storage ss_bcast;
        struct iface_struct ifs;
        char *p;
        int i;
        bool added=false;
        bool goodaddr = false;

        /* 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]);
                        added = true;
                }
        }
        if (added) {
                return;
        }

        /* maybe it is a DNS name */
        p = strchr_m(token,'/');
        if (p == NULL) {
                if (!interpret_string_addr(&ss, token, 0)) {
                        DEBUG(2, ("interpret_interface: Can't find address "
                                  "for %s\n", token));
                        return;
                }

                for (i=0;i<total_probed;i++) {
                        if (sockaddr_equal(&ss, &probed_ifaces[i].ip)) {
                                add_interface(&probed_ifaces[i]);
                                return;
                        }
                }
                DEBUG(2,("interpret_interface: "
                        "can't determine interface for %s\n",
                        token));
                return;
        }

        /* parse it into an IP address/netmasklength pair */
        *p = 0;
        goodaddr = interpret_string_addr(&ss, token, 0);
        *p++ = '/';

        if (!goodaddr) {
                DEBUG(2,("interpret_interface: "
                        "can't determine interface for %s\n",
                        token));
                return;
        }

        if (strlen(p) > 2) {
                goodaddr = interpret_string_addr(&ss_mask, p, 0);
                if (!goodaddr) {
                        DEBUG(2,("interpret_interface: "
                                "can't determine netmask from %s\n",
                                p));
                        return;
                }
        } else {
                char *endp = NULL;
                unsigned long val = strtoul(p, &endp, 0);
                if (p == endp || (endp && *endp != '\0')) {
                        DEBUG(2,("interpret_interface: "
                                "can't determine netmask value from %s\n",
                                p));
                        return;
                }
                if (!make_netmask(&ss_mask, &ss, val)) {
                        DEBUG(2,("interpret_interface: "
                                "can't apply netmask value %lu from %s\n",
                                val,
                                p));
                        return;
                }
        }

        make_bcast(&ss_bcast, &ss, &ss_mask);
        make_net(&ss_net, &ss, &ss_mask);

        /* Maybe the first component was a broadcast address. */
        if (sockaddr_equal(&ss_bcast, &ss) || sockaddr_equal(&ss_net, &ss)) {
                for (i=0;i<total_probed;i++) {
                        if (same_net(&ss, &probed_ifaces[i].ip, &ss_mask)) {
                                /* Temporarily replace netmask on
                                 * the detected interface - user knows
                                 * best.... */
                                struct sockaddr_storage saved_mask =
                                        probed_ifaces[i].netmask;
                                probed_ifaces[i].netmask = ss_mask;
                                DEBUG(2,("interpret_interface: "
                                        "using netmask value %s from "
                                        "config file on interface %s\n",
                                        p,
                                        probed_ifaces[i].name));
                                add_interface(&probed_ifaces[i]);
                                probed_ifaces[i].netmask = saved_mask;
                                return;
                        }
                }
                DEBUG(2,("interpret_interface: Can't determine ip for "
                        "broadcast address %s\n",
                        token));
                return;
        }

        /* Just fake up the interface definition. User knows best. */

        DEBUG(2,("interpret_interface: Adding interface %s\n",
                token));

        ZERO_STRUCT(ifs);
        (void)strlcpy(ifs.name, token, sizeof(ifs.name));
        ifs.flags = IFF_BROADCAST;
        ifs.ip = ss;
        ifs.netmask = ss_mask;
        ifs.bcast = ss_bcast;
        add_interface(&ifs);
}

/****************************************************************************
 Load the list of network interfaces.
****************************************************************************/

void load_interfaces(void)
{
        struct iface_struct ifaces[MAX_INTERFACES];
        const char **ptr = lp_interfaces();
        int i;

        SAFE_FREE(probed_ifaces);

        /* dump the current interfaces if any */
        while (local_interfaces) {
                struct interface *iface = local_interfaces;
                DLIST_REMOVE(local_interfaces, local_interfaces);
                SAFE_FREE(iface->name);
                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 (probed_ifaces[i].flags & IFF_BROADCAST) {
                                add_interface(&probed_ifaces[i]);
                        }
                }
                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);
                SAFE_FREE(iface->name);
                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;
}