networkinterfaces.c

wifi 无线网络路由协议OLSR linux下C代码

/*
 * OLSR Basic Multicast Forwarding (BMF) plugin.
 * Copyright (c) 2005 - 2007, Thales Communications, Huizen, The Netherlands.
 * Written by Erik Tromp.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without 
 * modification, are permitted provided that the following conditions 
 * are met:
 *
 * * Redistributions of source code must retain the above copyright 
 *   notice, this list of conditions and the following disclaimer.
 * * Redistributions in binary form must reproduce the above copyright 
 *   notice, this list of conditions and the following disclaimer in 
 *   the documentation and/or other materials provided with the 
 *   distribution.
 * * Neither the name of Thales, BMF nor the names of its 
 *   contributors may be used to endorse or promote products derived 
 *   from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND 
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED 
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 
 * IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, 
 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, 
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY 
 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE 
 * OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED 
 * OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/* -------------------------------------------------------------------------
 * File       : NetworkInterfaces.c
 * Description: Functions to open and close sockets
 * Created    : 29 Jun 2006
 *
 * ------------------------------------------------------------------------- */

#include "NetworkInterfaces.h"

/* System includes */
#include <stddef.h> /* NULL */
#include <syslog.h> /* syslog() */
#include <string.h> /* strerror(), strchr(), strcmp() */
#include <errno.h> /* errno */
#include <unistd.h> /* close() */
#include <sys/ioctl.h> /* ioctl() */
#include <fcntl.h> /* fcntl() */
#include <assert.h> /* assert() */
#include <net/if.h> /* socket(), ifreq, if_indextoname(), if_nametoindex() */
#include <netinet/in.h> /* htons() */
#include <linux/if_ether.h> /* ETH_P_IP */
#include <linux/if_packet.h> /* packet_mreq, PACKET_MR_PROMISC, PACKET_ADD_MEMBERSHIP */
#include <linux/if_tun.h> /* IFF_TAP */
#include <netinet/ip.h> /* struct ip */
#include <netinet/udp.h> /* SOL_UDP */

/* OLSRD includes */
#include "olsr.h" /* olsr_printf() */
#include "defs.h" /* olsr_cnf */
#include "local_hna_set.h" /* add_local_hna4_entry() */
#include "link_set.h" /* get_link_set() */
#include "lq_route.h" /* MIN_LINK_QUALITY */
#include "tc_set.h" /* olsr_lookup_tc_entry(), olsr_tc_lookup_dst() */

/* Plugin includes */
#include "Packet.h" /* IFHWADDRLEN */
#include "Bmf.h" /* PLUGIN_NAME, MainAddressOf() */
#include "Address.h" /* IsMulticast() */

/* List of network interface objects used by BMF plugin */
struct TBmfInterface* BmfInterfaces = NULL;
struct TBmfInterface* LastBmfInterface = NULL;

/* Highest-numbered open socket file descriptor. To be used as first
 * parameter in calls to select(...). */
int HighestSkfd = -1;

/* Set of socket file descriptors */
fd_set InputSet;

/* File descriptor of EtherTunTap interface */
int EtherTunTapFd = -1;

/* Network interface name of EtherTunTap interface. May be overruled by
 * setting the plugin parameter "BmfInterface". */
char EtherTunTapIfName[IFNAMSIZ] = "bmf0";

/* The underlying mechanism to forward multicast packets. Either:
 * - BM_BROADCAST: BMF uses the IP local broadcast as destination address
 * - BM_UNICAST_PROMISCUOUS: BMF uses the IP address of the best neighbor as
 *   destination address. The other neighbors listen promiscuously. */
enum TBmfMechanism BmfMechanism = BM_BROADCAST;

#define ETHERTUNTAPIPNOTSET 0

/* The IP address of the BMF network interface in host byte order.
 * May be overruled by setting the plugin parameter "BmfInterfaceIp". */
u_int32_t EtherTunTapIp = ETHERTUNTAPIPNOTSET;

/* 255.255.255.255 in host byte order. May be overruled by
 * setting the plugin parameter "BmfInterfaceIp". */
u_int32_t EtherTunTapIpMask = 0xFFFFFFFF;

/* The IP broadcast address of the BMF network interface in host byte order.
 * May be overruled by setting the plugin parameter "BmfinterfaceIp". */
u_int32_t EtherTunTapIpBroadcast = ETHERTUNTAPIPNOTSET;

/* Whether or not the configuration has overruled the default IP
 * configuration of the EtherTunTap interface */
int TunTapIpOverruled = 0;

/* Whether or not to capture packets on the OLSR-enabled
 * interfaces (in promiscuous mode). May be overruled by setting the plugin
 * parameter "CapturePacketsOnOlsrInterfaces" to "yes". */
int CapturePacketsOnOlsrInterfaces = 0;

/* -------------------------------------------------------------------------
 * Function   : SetBmfInterfaceName
 * Description: Overrule the default network interface name ("bmf0") of the
 *              EtherTunTap interface
 * Input      : ifname - network interface name (e.g. "mybmf0")
 *              data - not used
 *              addon - not used
 * Output     : none
 * Return     : success (0) or fail (1)
 * Data Used  : EtherTunTapIfName
 * ------------------------------------------------------------------------- */
int SetBmfInterfaceName(const char* ifname, void* data __attribute__((unused)), set_plugin_parameter_addon addon  __attribute__((unused)))
{
  strncpy(EtherTunTapIfName, ifname, IFNAMSIZ - 1);
  EtherTunTapIfName[IFNAMSIZ - 1] = '\0'; /* Ensures null termination */
  return 0;
} /* SetBmfInterfaceName */

/* -------------------------------------------------------------------------
 * Function   : SetBmfInterfaceIp
 * Description: Overrule the default IP address and prefix length
 *              ("10.255.255.253/30") of the EtherTunTap interface
 * Input      : ip - IP address string, followed by '/' and prefix length
 *              data - not used
 *              addon - not used
 * Output     : none
 * Return     : success (0) or fail (1)
 * Data Used  : EtherTunTapIp, EtherTunTapIpMask, EtherTunTapIpBroadcast,
 *              TunTapIpOverruled
 * ------------------------------------------------------------------------- */
int SetBmfInterfaceIp(const char* ip, void* data __attribute__((unused)), set_plugin_parameter_addon addon  __attribute__((unused)))
{
#define IPV4_MAX_ADDRLEN 16
#define IPV4_MAX_PREFIXLEN 32
  char* slashAt;
  char ipAddr[IPV4_MAX_ADDRLEN];
  struct in_addr sinaddr;
  int prefixLen;
  int i;

  /* Inspired by function str2prefix_ipv4 as found in Quagga source
   * file lib/prefix.c */

  /* Find slash inside string. */
  slashAt = strchr(ip, '/');

  /* String doesn't contain slash. */
  if (slashAt == NULL || slashAt - ip >= IPV4_MAX_ADDRLEN)
  {
    /* No prefix length specified, or IP address too long */
    return 1;
  }

  strncpy(ipAddr, ip, slashAt - ip);
  *(ipAddr + (slashAt - ip)) = '\0';
  if (inet_aton(ipAddr, &sinaddr) == 0)
  {
    /* Invalid address passed */
    return 1;
  }

  EtherTunTapIp = ntohl(sinaddr.s_addr);

  /* Get prefix length. */
  prefixLen = atoi(++slashAt);
  if (prefixLen <= 0 || prefixLen > IPV4_MAX_PREFIXLEN)
  {
    return 1;
  }

  /* Compose IP subnet mask in host byte order */
  EtherTunTapIpMask = 0;
  for (i = 0; i < prefixLen; i++)
  {
    EtherTunTapIpMask |= (1 << (IPV4_MAX_PREFIXLEN - 1 - i));
  }

  /* Compose IP broadcast address in host byte order */
  EtherTunTapIpBroadcast = EtherTunTapIp;
  for (i = prefixLen; i < IPV4_MAX_PREFIXLEN; i++)
  {
    EtherTunTapIpBroadcast |= (1 << (IPV4_MAX_PREFIXLEN - 1 - i));
  }

  TunTapIpOverruled = 1;

  return 0;
} /* SetBmfInterfaceIp */

/* -------------------------------------------------------------------------
 * Function   : SetCapturePacketsOnOlsrInterfaces
 * Description: Overrule the default setting, enabling or disabling the
 *              capturing of packets on OLSR-enabled interfaces.
 * Input      : enable - either "yes" or "no"
 *              data - not used
 *              addon - not used
 * Output     : none
 * Return     : success (0) or fail (1)
 * Data Used  : none
 * ------------------------------------------------------------------------- */
int SetCapturePacketsOnOlsrInterfaces(const char* enable, void* data __attribute__((unused)), set_plugin_parameter_addon addon  __attribute__((unused)))
{
  if (strcmp(enable, "yes") == 0)
  {
    CapturePacketsOnOlsrInterfaces = 1;
    return 0;
  }
  else if (strcmp(enable, "no") == 0)
  {
    CapturePacketsOnOlsrInterfaces = 0;
    return 0;
  }

  /* Value not recognized */
  return 1;
} /* SetCapturePacketsOnOlsrInterfaces */

/* -------------------------------------------------------------------------
 * Function   : SetBmfMechanism
 * Description: Overrule the default BMF mechanism to either BM_BROADCAST or
 *              BM_UNICAST_PROMISCUOUS.
 * Input      : mechanism - either "Broadcast" or "UnicastPromiscuous"
 *              data - not used
 *              addon - not used
 * Output     : none
 * Return     : success (0) or fail (1)
 * Data Used  : none
 * ------------------------------------------------------------------------- */
int SetBmfMechanism(const char* mechanism, void* data __attribute__((unused)), set_plugin_parameter_addon addon  __attribute__((unused)))
{
  if (strcmp(mechanism, "Broadcast") == 0)
  {
    BmfMechanism = BM_BROADCAST;
    return 0;
  }
  else if (strcmp(mechanism, "UnicastPromiscuous") == 0)
  {
    BmfMechanism = BM_UNICAST_PROMISCUOUS;
    return 0;
  }

  /* Value not recognized */
  return 1;
} /* SetBmfMechanism */

/* -------------------------------------------------------------------------
 * Function   : AddDescriptorToInputSet
 * Description: Add a socket descriptor to the global set of socket file descriptors
 * Input      : skfd - socket file descriptor
 * Output     : none
 * Return     : none
 * Data Used  : HighestSkfd, InputSet
 * Notes      : Keeps track of the highest-numbered descriptor
 * ------------------------------------------------------------------------- */
static void AddDescriptorToInputSet(int skfd)
{
  /* Keep the highest-numbered descriptor */
  if (skfd > HighestSkfd)
  {
    HighestSkfd = skfd;
  }

  /* Add descriptor to input set */
  FD_SET(skfd, &InputSet);
} /* AddDescriptorToInputSet */

/* To save the state of the IP spoof filter for the EtherTunTap interface */
static char EthTapSpoofState = '1';

/* -------------------------------------------------------------------------
 * Function   : DeactivateSpoofFilter
 * Description: Deactivates the Linux anti-spoofing filter for the tuntap
 *              interface
 * Input      : none
 * Output     : none
 * Return     : fail (0) or success (1)
 * Data Used  : EtherTunTapIfName, EthTapSpoofState
 * Notes      : Saves the current filter state for later restoring
 * ------------------------------------------------------------------------- */
int DeactivateSpoofFilter(void)
{
  FILE* procSpoof;
  char procFile[FILENAME_MAX];

  /* Generate the procfile name */
  sprintf(procFile, "/proc/sys/net/ipv4/conf/%s/rp_filter", EtherTunTapIfName);

  /* Open procfile for reading */
  procSpoof = fopen(procFile, "r");
  if (procSpoof == NULL)
  {
    fprintf(
      stderr,
      "WARNING! Could not open the %s file to check/disable the IP spoof filter!\n"
      "Are you using the procfile filesystem?\n"
      "Does your system support IPv4?\n"
      "I will continue (in 3 sec) - but you should manually ensure that IP spoof\n"
      "filtering is disabled!\n\n",
      procFile);
      
    sleep(3);
    return 0;
  }

  EthTapSpoofState = fgetc(procSpoof);
  fclose(procSpoof);

  /* Open procfile for writing */
  procSpoof = fopen(procFile, "w");
  if (procSpoof == NULL)
  {
    fprintf(stderr, "Could not open %s for writing!\n", procFile);
    fprintf(
      stderr,
      "I will continue (in 3 sec) - but you should manually ensure that IP"
      " spoof filtering is disabled!\n\n");
    sleep(3);
    return 0;
  }

  syslog(LOG_INFO, "Writing \"0\" to %s", procFile);
  fputs("0", procSpoof);

  fclose(procSpoof);

  return 1;
} /* DeactivateSpoofFilter */

/* -------------------------------------------------------------------------
 * Function   : RestoreSpoofFilter
 * Description: Restores the Linux anti-spoofing filter setting for the tuntap
 *              interface
 * Input      : none
 * Output     : none
 * Return     : none
 * Data Used  : EtherTunTapIfName, EthTapSpoofState
 * ------------------------------------------------------------------------- */
void RestoreSpoofFilter(void)
{
  FILE* procSpoof;
  char procFile[FILENAME_MAX];

  /* Generate the procfile name */
  sprintf(procFile, "/proc/sys/net/ipv4/conf/%s/rp_filter", EtherTunTapIfName);

  /* Open procfile for writing */
  procSpoof = fopen(procFile, "w");
  if (procSpoof == NULL)
  {
    fprintf(stderr, "Could not open %s for writing!\nSettings not restored!\n", procFile);
  }
  else
  {
    syslog(LOG_INFO, "Resetting %s to %c\n", procFile, EthTapSpoofState);

    fputc(EthTapSpoofState, procSpoof);
    fclose(procSpoof);
  }
} /* RestoreSpoofFilter */

#ifndef USING_THALES_LINK_COST_ROUTING
/* -------------------------------------------------------------------------
 * Function   : CalcEtx
 * Description: Calculate the Expected Transmission Count (ETX) value, based on
 *              link loss fraction and inverse link loss fraction
 * Input      : loss - link loss fraction
 *              neigh_loss - inverse link loss fraction 
 * Output     : none
 * Return     : the ETX value
 * Data Used  : none
 * ------------------------------------------------------------------------- */
static float CalcEtx(float loss, float neigh_loss) 
{
  if (loss < MIN_LINK_QUALITY || neigh_loss < MIN_LINK_QUALITY)
  {
    return INFINITE_ETX;