src/firewall.c

/********************************************************************\
 * 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, contact:                        *
 *                                                                  *
 * Free Software Foundation           Voice:  +1-617-542-5942       *
 * 59 Temple Place - Suite 330        Fax:    +1-617-542-2652       *
 * Boston, MA  02111-1307,  USA       gnu@gnu.org                   *
 *                                                                  *
 \********************************************************************/

/*
 * $Header: /cvsroot/wifidog/wifidog/src/firewall.c,v 1.32 2004/04/23
 * 11:37:43 aprilp Exp $
 */
#define _GNU_SOURCE

#include <stdio.h>
#include <stdlib.h>
#include <syslog.h>
#include <errno.h>
#include <pthread.h>
#include <sys/wait.h>
#include <sys/types.h>
#include <sys/unistd.h>

#include <string.h>

#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <sys/uio.h>
#include <fcntl.h>
#include <netdb.h>
#include <sys/time.h>

#ifdef __linux__
#include <net/ethernet.h>
#include <netinet/ip.h>
#include <netinet/ip_icmp.h>
#include <netpacket/packet.h>
#endif

#include "httpd.h"
#include "safe.h"
#include "debug.h"
#include "conf.h"
#include "firewall.h"
#include "fw_iptables.h"
#include "auth.h"
#include "centralserver.h"
#include "client_list.h"

extern pthread_mutex_t client_list_mutex;

int icmp_fd = 0;

int
fw_allow(char *ip, char *mac, int fw_connection_state)
{
    debug(LOG_DEBUG, "Allowing %s %s with fw_connection_state %d", ip, mac, fw_connection_state);

    return iptables_fw_access(FW_ACCESS_ALLOW, ip, mac, fw_connection_state);
}

int
fw_deny(char *ip, char *mac, int fw_connection_state)
{
    debug(LOG_DEBUG, "Denying %s %s with fw_connection_state %d", ip, mac, fw_connection_state);

    return iptables_fw_access(FW_ACCESS_DENY, ip, mac, fw_connection_state);
}

char           *
arp_get(char *req_ip)
{
    FILE           *proc;
         char ip[16];
         char mac[18];
         char * reply = NULL;

    if (!(proc = fopen("/proc/net/arp", "r"))) {
        return NULL;
    }

    /* Skip first line */
         while (!feof(proc) && fgetc(proc) != '\n');

         /* Find ip, copy mac in reply */
         reply = NULL;
    while (!feof(proc) && (fscanf(proc, " %15[0-9.] %*s %*s %17[A-F0-9:] %*s %*s", ip, mac) == 2)) {
                  if (strcmp(ip, req_ip) == 0) {
                                reply = safe_strdup(mac);
                                break;
                  }
    }

    fclose(proc);

    return reply;
}

int
fw_init(void)
{
    int flags, oneopt = 1, zeroopt = 0;

    debug(LOG_INFO, "Creating ICMP socket");
    if ((icmp_fd = socket (AF_INET, SOCK_RAW, IPPROTO_ICMP)) == -1 ||
            (flags = fcntl(icmp_fd, F_GETFL, 0)) == -1 ||
             fcntl(icmp_fd, F_SETFL, flags | O_NONBLOCK) == -1 ||
             setsockopt(icmp_fd, SOL_SOCKET, SO_RCVBUF, &oneopt, sizeof(oneopt)) ||
             setsockopt(icmp_fd, SOL_SOCKET, SO_DONTROUTE, &zeroopt, sizeof(zeroopt)) == -1) {
        debug(LOG_ERR, "Cannot create ICMP raw socket.");
        return;
    }

    debug(LOG_INFO, "Initializing Firewall");
    return iptables_fw_init();
}

void
fw_clear_authservers(void)
{
        debug(LOG_INFO, "Clearing the authservers list");
        iptables_fw_clear_authservers();
}

void
fw_set_authservers(void)
{
        debug(LOG_INFO, "Setting the authservers list");
        iptables_fw_set_authservers();
}

int
fw_destroy(void)
{
    if (icmp_fd != 0) {
        debug(LOG_INFO, "Closing ICMP socket");
        close(icmp_fd);
    }

    debug(LOG_INFO, "Removing Firewall rules");
    return iptables_fw_destroy();
}

void
fw_counter(void)
{
    t_authresponse  authresponse;
    char            *token, *ip, *mac;
    t_client        *p1, *p2;
    unsigned long long      incoming, outgoing;
    s_config *config = config_get_config();

    if (-1 == iptables_fw_counters_update()) {
        debug(LOG_ERR, "Could not get counters from firewall!");
        return;
    }

    LOCK_CLIENT_LIST();

    for (p1 = p2 = client_get_first_client(); NULL != p1; p1 = p2) {
        p2 = p1->next;

        ip = safe_strdup(p1->ip);
        token = safe_strdup(p1->token);
        mac = safe_strdup(p1->mac);
            outgoing = p1->counters.outgoing;
            incoming = p1->counters.incoming;

            UNLOCK_CLIENT_LIST();
        /* Ping the client, if he responds it'll keep activity on the link */
        icmp_ping(ip);
        /* Update the counters on the remote server */
        auth_server_request(&authresponse, REQUEST_TYPE_COUNTERS, ip, mac, token, incoming, outgoing);
            LOCK_CLIENT_LIST();
        
        if (!(p1 = client_list_find(ip, mac))) {
            debug(LOG_ERR, "Node %s was freed while being re-validated!", ip);
        } else {
            if (p1->counters.last_updated +
                                (config->checkinterval * config->clienttimeout)
                                <= time(NULL)) {
                /* Timing out user */
                debug(LOG_INFO, "%s - Inactive for %ld seconds, removing client and denying in firewall", p1->ip, config->checkinterval * config->clienttimeout);
                fw_deny(p1->ip, p1->mac, p1->fw_connection_state);
                client_list_delete(p1);

                /* Advertise the logout */
                                        UNLOCK_CLIENT_LIST();
                                        auth_server_request(&authresponse, REQUEST_TYPE_LOGOUT, ip, mac, token, 0, 0);
                                        LOCK_CLIENT_LIST();
            }
                                else {
                /*
                 * This handles any change in
                 * the status this allows us
                 * to change the status of a
                 * user while he's connected
                 */
                switch (authresponse.authcode) {
                    case AUTH_DENIED:
                        debug(LOG_NOTICE, "%s - Denied. Removing client and firewall rules", p1->ip);
                        fw_deny(p1->ip, p1->mac, p1->fw_connection_state);
                        client_list_delete(p1);
                        break;

                    case AUTH_VALIDATION_FAILED:
                        debug(LOG_NOTICE, "%s - Validation timeout, now denied. Removing client and firewall rules", p1->ip);
                        fw_deny(p1->ip, p1->mac, p1->fw_connection_state);
                        client_list_delete(p1);
                        break;

                    case AUTH_ALLOWED:
                        if (p1->fw_connection_state != FW_MARK_KNOWN) {
                            debug(LOG_INFO, "%s - Access has changed to allowed, refreshing firewall and clearing counters", p1->ip);
                            fw_deny(p1->ip, p1->mac, p1->fw_connection_state);
                            p1->fw_connection_state = FW_MARK_KNOWN;
                            p1->counters.incoming = p1->counters.outgoing = 0;
                            fw_allow(p1->ip, p1->mac, p1->fw_connection_state);
                        }
                        break;

                    case AUTH_VALIDATION:
                        /*
                         * Do nothing, user
                         * is in validation
                         * period
                         */
                        debug(LOG_INFO, "%s - User in validation period", p1->ip);
                        break;

                                                  case AUTH_ERROR:
                                                                debug(LOG_WARNING, "Error communicating with auth server - leaving %s as-is for now", p1->ip);
                                                                break;

                    default:
                        debug(LOG_DEBUG, "I do not know about authentication code %d", authresponse.authcode);
                        break;
                }
            }
        }

        free(token);
        free(ip);
        free(mac);
    }
    UNLOCK_CLIENT_LIST();
}

void icmp_ping(char *host) {
  struct sockaddr_in saddr;
#ifdef __linux__
  struct { 
    struct ip ip;
    struct icmp icmp;
  } packet;
#endif
  unsigned int i, j;
  int opt = 2000;
  unsigned short id = rand16();

  saddr.sin_family = AF_INET;
  saddr.sin_port = 0;
  inet_aton(host, &saddr.sin_addr);
#ifdef HAVE_SOCKADDR_SA_LEN
  saddr.sin_len = sizeof(struct sockaddr_in);
#endif

  memset(&(saddr.sin_zero), '\0', sizeof(saddr.sin_zero));

#ifdef __linux__
  memset(&packet.icmp, 0, sizeof(packet.icmp));
  packet.icmp.icmp_type = ICMP_ECHO;
  packet.icmp.icmp_id = id;
  for (j = 0, i = 0; i < sizeof(struct icmp) / 2; i++)
    j += ((unsigned short *)&packet.icmp)[i];
  while (j>>16)
    j = (j & 0xffff) + (j >> 16);  
  packet.icmp.icmp_cksum = (j == 0xffff) ? j : ~j;

  if (setsockopt(icmp_fd, SOL_SOCKET, SO_RCVBUF, &opt, sizeof(opt)) == -1) {
      debug(LOG_ERR, "setsockopt(): %s", strerror(errno));
  }
  if (sendto(icmp_fd, (char *)&packet.icmp, sizeof(struct icmp), 0, (struct sockaddr *)&saddr, sizeof(saddr)) == -1) {
      debug(LOG_ERR, "sendto(): %s", strerror(errno));
  }
  opt = 1;
  if (setsockopt(icmp_fd, SOL_SOCKET, SO_RCVBUF, &opt, sizeof(opt)) == -1) {
      debug(LOG_ERR, "setsockopt(): %s", strerror(errno));
  }
#endif

  return;
}

unsigned short rand16(void) {
  static int been_seeded = 0;

  if (!been_seeded) {
    int fd, n = 0;
    unsigned int c = 0, seed = 0;
    char sbuf[sizeof(seed)];
    char *s;
    struct timeval now;

    /* not a very good seed but what the heck, it needs to be quickly acquired */
    gettimeofday(&now, NULL);
    seed = now.tv_sec ^ now.tv_usec ^ (getpid() << 16);

    srand(seed);
    been_seeded = 1;
    }

    /* Some rand() implementations have less randomness in low bits
     * than in high bits, so we only pay attention to the high ones.
     * But most implementations don't touch the high bit, so we 
     * ignore that one.
     **/
      return( (unsigned short) (rand() >> 15) );
}

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