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path: root/src/transport/gnunet-transport-wlan-helper.c
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/*
 This file is part of GNUnet.
 (C) 2010, 2011 Christian Grothoff (and other contributing authors)

 GNUnet 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, or (at your
 option) any later version.

 GNUnet 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 GNUnet; see the file COPYING.  If not, write to the
 Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 Boston, MA 02111-1307, USA.
 */

/**
 * @file src/transport/gnunet-transport-wlan-helper.c
 * @brief wlan layer two server; must run as root (SUID will do)
 *        This code will work under GNU/Linux only.
 * @author David Brodski
 *
 * This program serves as the mediator between the wlan interface and
 * gnunet
 */

#define _GNU_SOURCE
#include <sys/socket.h>
#include <sys/ioctl.h>
#include <sys/types.h>
#include <unistd.h>
#include <sys/wait.h>
#include <sys/time.h>
#include <sys/stat.h>
#include <netpacket/packet.h>
#include <linux/if_ether.h>
#include <linux/if.h>
#include <linux/wireless.h>
#include <netinet/in.h>
#include <linux/if_tun.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdarg.h>
#include <fcntl.h>
#include <errno.h>
#include <dirent.h>
//#include <sys/utsname.h>
#include <sys/param.h>

/*
 //#include <resolv.h>
 #include <string.h>
 #include <utime.h>
 #include <getopt.h>
 */
//#include "platform.h"
#include "gnunet_constants.h"
#include "gnunet_os_lib.h"
#include "gnunet_transport_plugin.h"
#include "transport.h"
#include "gnunet_util_lib.h"
#include "plugin_transport_wlan.h"
#include "gnunet_common.h"
#include "gnunet-transport-wlan-helper.h"
#include "gnunet_crypto_lib.h"

#include "wlan/radiotap-parser.h"
/* radiotap-parser defines types like u8 that
 * ieee80211_radiotap.h needs
 *
 * we use our local copy of ieee80211_radiotap.h
 *
 * - since we can't support extensions we don't understand
 * - since linux does not include it in userspace headers
 */
#include "wlan/ieee80211_radiotap.h"
#include "wlan/crctable_osdep.h"
#include "wlan/loopback_helper.h"
#include "wlan/ieee80211.h"

#define ARPHRD_IEEE80211        801
#define ARPHRD_IEEE80211_PRISM  802
#define ARPHRD_IEEE80211_FULL   803

#include "wlan/loopback_helper.h"

#define DEBUG 1

#define MAC_ADDR_SIZE 6

struct Hardware_Infos
{

  struct sendbuf write_pout;
  int fd_raw;
  int arptype_in;

  /**
   * Name of the interface, not necessarily 0-terminated (!).
   */
  char iface[IFNAMSIZ];
  unsigned char pl_mac[MAC_ADDR_SIZE];
};

// FIXME: inline?
int getChannelFromFrequency(int frequency);

// FIXME: make nice...
static unsigned long
calc_crc_osdep(unsigned char * buf, int len)
{
  unsigned long crc = 0xFFFFFFFF;

  for (; len > 0; len--, buf++)
    crc = crc_tbl_osdep[(crc ^ *buf) & 0xFF] ^ (crc >> 8);

  return (~crc);
}

/* CRC checksum verification routine */

// FIXME: make nice...
static int
check_crc_buf_osdep(unsigned char *buf, int len)
{
  unsigned long crc;

  if (0 > len)
    return 0;

  crc = calc_crc_osdep(buf, len);
  buf += len;
  return (((crc) & 0xFF) == buf[0] && ((crc >> 8) & 0xFF) == buf[1] && ((crc
      >> 16) & 0xFF) == buf[2] && ((crc >> 24) & 0xFF) == buf[3]);
}


// FIXME: make nice...
static int
linux_get_channel(struct Hardware_Infos *dev)
{
  struct iwreq wrq;
  int fd, frequency;
  int chan = 0;

  memset(&wrq, 0, sizeof(struct iwreq));

  strncpy(wrq.ifr_name, dev->iface, IFNAMSIZ );

  fd = dev->fd_raw;
  if (0 > ioctl(fd, SIOCGIWFREQ, &wrq))
    return (-1);

  frequency = wrq.u.freq.m;
  if (100000000 < frequency  )
    frequency /= 100000;
  else if (1000000 < frequency )
    frequency /= 1000;

  if (1000 < frequency)
    chan = getChannelFromFrequency(frequency);
  else
    chan = frequency;

  return chan;
}


// FIXME: make nice...
static ssize_t
linux_read (struct Hardware_Infos *dev,
	    unsigned char *buf,  /* FIXME: void*? */
	    size_t buf_size,
	    struct Radiotap_rx *ri)
{
  unsigned char tmpbuf[buf_size];
  ssize_t caplen;
  int n, got_signal, got_noise, got_channel, fcs_removed;

  n = got_signal = got_noise = got_channel = fcs_removed = 0;

  caplen = read(dev->fd_raw, tmpbuf, buf_size);
  if (0 > caplen)
    {
      if (EAGAIN == errno)
        return 0;
      fprintf (stderr,
	       "Failed to read from RAW socket: %s\n",
	       strerror (errno));
      return -1;
    }

  memset(buf, 0, buf_size);
  memset(ri, 0, sizeof(*ri));

  switch (dev->arptype_in)
    {
    case ARPHRD_IEEE80211_PRISM:
      {
	/* skip the prism header */
	if (tmpbuf[7] == 0x40)
	  {
	    /* prism54 uses a different format */
	    ri->ri_power = tmpbuf[0x33];
	    ri->ri_noise = *(unsigned int *) (tmpbuf + 0x33 + 12);
	    ri->ri_rate = (*(unsigned int *) (tmpbuf + 0x33 + 24)) * 500000;
	    got_signal = 1;
	    got_noise = 1;
	    n = 0x40;
	  }
	else
	  {
	    ri->ri_mactime = *(u_int64_t*) (tmpbuf + 0x5C - 48);
	    ri->ri_channel = *(unsigned int *) (tmpbuf + 0x5C - 36);
	    ri->ri_power = *(unsigned int *) (tmpbuf + 0x5C);
	    ri->ri_noise = *(unsigned int *) (tmpbuf + 0x5C + 12);
	    ri->ri_rate = (*(unsigned int *) (tmpbuf + 0x5C + 24)) * 500000;
	    got_channel = 1;
	    got_signal = 1;
	    got_noise = 1;
	    n = *(int *) (tmpbuf + 4);
	  }
	
	if (n < 8 || n >= caplen)
	  return (0);
      }
      break;

    case ARPHRD_IEEE80211_FULL:
      {
	struct ieee80211_radiotap_iterator iterator;
	struct ieee80211_radiotap_header *rthdr;
	
	rthdr = (struct ieee80211_radiotap_header *) tmpbuf;
	
	if (ieee80211_radiotap_iterator_init(&iterator, rthdr, caplen) < 0)
	  return (0);
	
	/* go through the radiotap arguments we have been given
	 * by the driver
	 */
	
	while (ieee80211_radiotap_iterator_next(&iterator) >= 0)
	  {
	    
	    switch (iterator.this_arg_index)
	      {
		
	      case IEEE80211_RADIOTAP_TSFT:
		ri->ri_mactime = le64_to_cpu(*((uint64_t*) iterator.this_arg));
		break;
		
	      case IEEE80211_RADIOTAP_DBM_ANTSIGNAL:
		if (!got_signal)
		  {
		    if (*iterator.this_arg < 127)
		      ri->ri_power = *iterator.this_arg;
		    else
		      ri->ri_power = *iterator.this_arg - 255;
		    
		    got_signal = 1;
		  }
		break;
		
	      case IEEE80211_RADIOTAP_DB_ANTSIGNAL:
		if (!got_signal)
		  {
		    if (*iterator.this_arg < 127)
		      ri->ri_power = *iterator.this_arg;
		    else
		      ri->ri_power = *iterator.this_arg - 255;
		    
		    got_signal = 1;
		  }
		break;
		
	      case IEEE80211_RADIOTAP_DBM_ANTNOISE:
		if (!got_noise)
		  {
		    if (*iterator.this_arg < 127)
		      ri->ri_noise = *iterator.this_arg;
		    else
		      ri->ri_noise = *iterator.this_arg - 255;
		    
		    got_noise = 1;
		  }
		break;
		
	      case IEEE80211_RADIOTAP_DB_ANTNOISE:
		if (!got_noise)
		  {
		    if (*iterator.this_arg < 127)
		      ri->ri_noise = *iterator.this_arg;
		    else
		      ri->ri_noise = *iterator.this_arg - 255;
		    
		    got_noise = 1;
		  }
		break;
		
	      case IEEE80211_RADIOTAP_ANTENNA:
		ri->ri_antenna = *iterator.this_arg;
		break;
		
	      case IEEE80211_RADIOTAP_CHANNEL:
		ri->ri_channel = *iterator.this_arg;
		got_channel = 1;
		break;
		
	      case IEEE80211_RADIOTAP_RATE:
		ri->ri_rate = (*iterator.this_arg) * 500000;
		break;
		
	      case IEEE80211_RADIOTAP_FLAGS:
		/* is the CRC visible at the end?
		 * remove
		 */
		if (*iterator.this_arg & IEEE80211_RADIOTAP_F_FCS)
		  {
		    fcs_removed = 1;
		    caplen -= 4;
		  }
		
		if (*iterator.this_arg & IEEE80211_RADIOTAP_F_RX_BADFCS)
		  return (0);
		
		break;	    
	      }
	  }	
	n = le16_to_cpu(rthdr->it_len);	
	if (n <= 0 || n >= caplen)
	  return 0;
      }
      break;
    case ARPHRD_IEEE80211:
      /* do nothing? */
      break;
    default:
      errno = ENOTSUP;
      return -1;
    }

  caplen -= n;

  //detect fcs at the end, even if the flag wasn't set and remove it
  if ( (0 == fcs_removed) && 
       (1 == check_crc_buf_osdep(tmpbuf + n, caplen - 4)) )
    {
      caplen -= 4;
    }
  memcpy(buf, tmpbuf + n, caplen);
  if (! got_channel)
    ri->ri_channel = linux_get_channel(dev);

  return caplen;
}


/**
 * @return 0 on success
 */
static int
openraw (struct Hardware_Infos *dev)
{
  struct ifreq ifr;
  struct iwreq wrq;
  struct packet_mreq mr;
  struct sockaddr_ll sll;

  /* find the interface index */
  memset(&ifr, 0, sizeof(ifr));
  strncpy(ifr.ifr_name, dev->iface, IFNAMSIZ);
  if (-1 == ioctl(dev->fd_raw, SIOCGIFINDEX, &ifr))
    {
      fprintf (stderr,
	       "ioctl(SIOCGIFINDEX) on interface `%.*s' failed: %s\n",
	       IFNAMSIZ,
	       dev->iface,
	       strerror (errno));
      return 1;
    }

  /* lookup the hardware type */
  memset (&sll, 0, sizeof(sll));
  sll.sll_family = AF_PACKET;
  sll.sll_ifindex = ifr.ifr_ifindex;
  sll.sll_protocol = htons(ETH_P_ALL);
  if (-1 == ioctl(dev->fd_raw, SIOCGIFHWADDR, &ifr))
    {
      fprintf (stderr,
	       "ioctl(SIOCGIFHWADDR) on interface `%.*s' failed: %s\n",
	       IFNAMSIZ,
	       dev->iface,
	       strerror (errno));
      return 1;
    }

  /* lookup iw mode */
  memset(&wrq, 0, sizeof(struct iwreq));
  strncpy(wrq.ifr_name, dev->iface, IFNAMSIZ);
  if (-1 == ioctl(dev->fd_raw, SIOCGIWMODE, &wrq))
    {
      /* most probably not supported (ie for rtap ipw interface) *
       * so just assume its correctly set...                     */
      wrq.u.mode = IW_MODE_MONITOR;
    }

  if ( ( (ifr.ifr_hwaddr.sa_family != ARPHRD_IEEE80211) && 
	 (ifr.ifr_hwaddr.sa_family != ARPHRD_IEEE80211_PRISM) && 
	 (ifr.ifr_hwaddr.sa_family != ARPHRD_IEEE80211_FULL) ) || 
       (wrq.u.mode != IW_MODE_MONITOR) )
    {
      fprintf (stderr,
	       "Error: interface `%.*s' is not in monitor mode\n", 
	       IFNAMSIZ,
	       dev->iface);
      return 1;
    }

  /* Is interface st to up, broadcast & running ? */
  if ((ifr.ifr_flags | IFF_UP | IFF_BROADCAST | IFF_RUNNING) != ifr.ifr_flags)
    {
      /* Bring interface up*/
      ifr.ifr_flags |= IFF_UP | IFF_BROADCAST | IFF_RUNNING;

      if (-1 != ioctl(dev->fd_raw, SIOCSIFFLAGS, &ifr))
        {
	  fprintf (stderr,
		   "ioctl(SIOCSIFFLAGS) on interface `%.*s' failed: %s\n",
		   IFNAMSIZ,
		   dev->iface,
		   strerror (errno));
          return 1;
        }
    }

  /* bind the raw socket to the interface */
  if (-1 == bind(dev->fd_raw, (struct sockaddr *) &sll, sizeof(sll)))
    {
      fprintf (stderr,
	       "Failed to bind interface `%.*s': %s\n",
	       IFNAMSIZ,
	       dev->iface,
	       strerror (errno));
      return 1;
    }

  /* lookup the hardware type */
  if (-1 != ioctl(dev->fd_raw, SIOCGIFHWADDR, &ifr))
    {
      fprintf (stderr,
	       "ioctl(SIOCGIFHWADDR) on interface `%.*s' failed: %s\n",
	       IFNAMSIZ,
	       dev->iface,
	       strerror (errno));
      return 1;
    }

  memcpy (dev->pl_mac, 
	  ifr.ifr_hwaddr.sa_data, 
	  MAC_ADDR_SIZE);
  dev->arptype_in = ifr.ifr_hwaddr.sa_family;
  if ( (ifr.ifr_hwaddr.sa_family != ARPHRD_IEEE80211) && 
       (ifr.ifr_hwaddr.sa_family != ARPHRD_IEEE80211_PRISM) && 
       (ifr.ifr_hwaddr.sa_family != ARPHRD_IEEE80211_FULL) )
    {
      fprintf (stderr,
	       "Unsupported hardware link type %d on interface `%.*s'\n",
	       ifr.ifr_hwaddr.sa_family,
	       IFNAMSIZ,
	       dev->iface);
      return 1;
    }

  /* enable promiscuous mode */
  memset(&mr, 0, sizeof(mr));
  mr.mr_ifindex = sll.sll_ifindex;
  mr.mr_type = PACKET_MR_PROMISC;
  if (0 != setsockopt(dev->fd_raw, SOL_PACKET, PACKET_ADD_MEMBERSHIP, &mr, sizeof(mr)))
    {
      fprintf (stderr,
	       "Failed to enable promiscuous mode on interface `%.*s'\n",
	       IFNAMSIZ,
	       dev->iface);
      return 1;
    }

  return 0;
}

/**
 * @return 0 on success
 */
static int
wlaninit (struct Hardware_Infos *dev, 
	  const char *iface)
{
  char strbuf[512];
  struct stat sbuf;
  int ret;

  dev->fd_raw = socket (PF_PACKET, SOCK_RAW, htons(ETH_P_ALL));
  if (0 > dev->fd_raw)
    {
      fprintf (stderr,
	       "Failed to create raw socket: %s\n",
	       strerror (errno));
      return 1;
    }
  if (dev->fd_raw >= FD_SETSIZE)
    {
      fprintf (stderr,
	       "File descriptor too large for select (%d > %d)\n",
	       dev->fd_raw,
	       FD_SETSIZE);
      close (dev->fd_raw);
      return 1;
    }

  /* mac80211 stack detection */
  ret = snprintf(strbuf, 
		 sizeof(strbuf),
		 "/sys/class/net/%s/phy80211/subsystem", 
		 iface);
  if ( (ret < 0) ||
       (ret >= sizeof (strbuf)) ||
       (0 != stat(strbuf, &sbuf)) )
    {
      fprintf(stderr, 
	      "Did not find 802.11 interface `%s'. Exiting.\n",
	      iface);
      close (dev->fd_raw);
      return 1;
    }
  strncpy(dev->iface, iface, IFNAMSIZ);
  if (0 != openraw(dev))
    {
      close(dev->fd_raw);
      return 1;
    }
  return 0;
}


/**
 * Function to test incoming packets mac for being our own.
 *
 * @param u8aIeeeHeader buffer of the packet
 * @param dev the Hardware_Infos struct
 * @return 0 if mac belongs to us, 1 if mac is for another target
 */
static int
mac_test (const struct ieee80211_frame *u8aIeeeHeader, 
	  const struct Hardware_Infos *dev)
{
  if (0 != memcmp(u8aIeeeHeader->i_addr3, &mac_bssid, MAC_ADDR_SIZE))
    return 1;
  if (0 == memcmp(u8aIeeeHeader->i_addr1, dev->pl_mac, MAC_ADDR_SIZE))
    return 0;
  if (0 == memcmp(u8aIeeeHeader->i_addr1, &bc_all_mac, MAC_ADDR_SIZE))
    return 0;
  return 1;
}


/**
 * function to set the wlan header to make attacks more difficult
 * @param buf buffer of the packet
 * @param dev pointer to the Hardware_Infos struct
 */
static void
mac_set (struct ieee80211_frame *u8aIeeeHeader, 
	 const struct Hardware_Infos * dev)
{
  u8aIeeeHeader->i_fc[0] = 0x08;
  u8aIeeeHeader->i_fc[1] = 0x00;
  memcpy(u8aIeeeHeader->i_addr2, 
	 dev->pl_mac, 
	 MAC_ADDR_SIZE);
  memcpy(u8aIeeeHeader->i_addr3, 
	 &mac_bssid, 
	 MAC_ADDR_SIZE);

}


static void
stdin_send_hw (void *cls, 
	       void *client, 
	       const struct GNUNET_MessageHeader *hdr)
{
  struct Hardware_Infos * dev = cls;
  struct sendbuf *write_pout = &dev->write_pout;
  struct Radiotap_Send * header = (struct Radiotap_Send *) &hdr[1];
  struct ieee80211_frame * wlanheader;
  size_t sendsize;

  // struct? // FIXME: make nice...
  unsigned char u8aRadiotap[] =
    { 0x00, 0x00, // <-- radiotap version
      0x0c, 0x00, // <- radiotap header length
      0x04, 0x80, 0x00, 0x00, // <-- bitmap
      0x00, // <-- rate
      0x00, // <-- padding for natural alignment
      0x18, 0x00, // <-- TX flags
    };

  sendsize = ntohs(hdr->size);
  if (sendsize < sizeof(struct Radiotap_Send) + sizeof(struct GNUNET_MessageHeader))
    {
      fprintf(stderr, 
	      "Function stdin_send_hw: mailformed packet (too small)\n");
      exit (1);
    }
  sendsize -= sizeof(struct Radiotap_Send) + sizeof(struct GNUNET_MessageHeader);

  if (MAXLINE < sendsize)
    {
      fprintf(stderr, 
	      "Function stdin_send_hw: Packet too big for buffer\n");
      exit(1);
    }
  if (GNUNET_MESSAGE_TYPE_WLAN_HELPER_DATA != ntohs(hdr->type))
    {
      fprintf(stderr, "Function stdin_send: wrong packet type\n");
      exit(1);
    }

  u8aRadiotap[2] = htole16(sizeof(u8aRadiotap)); // WTF?
  u8aRadiotap[8] = header->rate;
  memcpy(write_pout->buf, u8aRadiotap, sizeof(u8aRadiotap));
  memcpy(write_pout->buf + sizeof(u8aRadiotap), &header[1], sendsize);
  /* payload contains MAC address, but we don't trust it, so we'll 
     overwrite it with OUR MAC address again to prevent mischief */
  wlanheader = (struct ieee80211_frame *) (write_pout->buf + sizeof(u8aRadiotap));
  mac_set(wlanheader, dev);
  write_pout->size = sendsize + sizeof(u8aRadiotap);
}

#if 0
static int
maketest(unsigned char * buf, struct Hardware_Infos * dev)
{
  uint16_t * tmp16;
  static uint16_t seqenz = 0;
  static int first = 0;

  const int rate = 11000000;
  static const char
      txt[] =
          "Hallo1Hallo2 Hallo3 Hallo4...998877665544332211Hallo1Hallo2 Hallo3 Hallo4...998877665544332211";

  unsigned char u8aRadiotap[] =
    { 0x00, 0x00, // <-- radiotap version
        0x00, 0x00, // <- radiotap header length
        0x04, 0x80, 0x02, 0x00, // <-- bitmap
        0x00, // <-- rate
        0x00, // <-- padding for natural alignment
        0x10, 0x00, // <-- TX flags
        0x04 //retries
      };

  /*uint8_t u8aRadiotap[] =
   {
   0x00, 0x00, // <-- radiotap version
   0x19, 0x00, // <- radiotap header length
   0x6f, 0x08, 0x00, 0x00, // <-- bitmap
   0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // <-- timestamp
   0x00, // <-- flags (Offset +0x10)
   0x6c, // <-- rate (0ffset +0x11)
   0x71, 0x09, 0xc0, 0x00, // <-- channel
   0xde, // <-- antsignal
   0x00, // <-- antnoise
   0x01, // <-- antenna
   };*/

  u8aRadiotap[8] = (rate / 500000);
  u8aRadiotap[2] = htole16(sizeof(u8aRadiotap));

  static struct ieee80211_frame u8aIeeeHeader;

  uint8_t u8aIeeeHeader_def[] =
    { 0x08, 0x00, // Frame Control 0x08= 00001000 -> | b1,2 = 0 -> Version 0;
        //      b3,4 = 10 -> Data; b5-8 = 0 -> Normal Data
        //      0x01 = 00000001 -> | b1 = 1 to DS; b2 = 0 not from DS;
        0x00, 0x00, // Duration/ID

        //0x00, 0x1f, 0x3f, 0xd1, 0x8e, 0xe6, // mac1 - in this case receiver
        0x00, 0x1d, 0xe0, 0xb0, 0x17, 0xdf, // mac1 - in this case receiver
        0xC0, 0x3F, 0x0E, 0x44, 0x2D, 0x51, // mac2 - in this case sender
        //0x02, 0x1d, 0xe0, 0x00, 0x01, 0xc4,
        0x13, 0x22, 0x33, 0x44, 0x55, 0x66, // mac3 - in this case bssid
        0x10, 0x86, //Sequence Control
      };
  if (0 == first)
    {
      memcpy(&u8aIeeeHeader, u8aIeeeHeader_def, sizeof(struct ieee80211_frame));
      memcpy(u8aIeeeHeader.i_addr2, dev->pl_mac, MAC_ADDR_SIZE);
      first = 1;
    }

  tmp16 = (uint16_t*) u8aIeeeHeader.i_dur;
  *tmp16
      = (uint16_t) htole16((sizeof(txt) + sizeof(struct ieee80211_frame) * 1000000) / rate + 290);
  tmp16 = (uint16_t*) u8aIeeeHeader.i_seq;
  *tmp16 = (*tmp16 & IEEE80211_SEQ_FRAG_MASK) | (htole16(seqenz)
      << IEEE80211_SEQ_SEQ_SHIFT);
  seqenz++;

  memcpy(buf, u8aRadiotap, sizeof(u8aRadiotap));
  memcpy(buf + sizeof(u8aRadiotap), &u8aIeeeHeader, sizeof(u8aIeeeHeader));
  memcpy(buf + sizeof(u8aRadiotap) + sizeof(u8aIeeeHeader), txt, sizeof(txt));
  return sizeof(u8aRadiotap) + sizeof(u8aIeeeHeader) + sizeof(txt);

}
#endif


/**
 * function to create GNUNET_MESSAGE_TYPE_WLAN_HELPER_CONTROL message for plugin
 * @param buffer pointer to buffer for the message
 * @param mac pointer to the mac address
 * @return number of bytes written
 */
// FIXME: use 'struct MacAddress' for 'mac' (everywhere in this file)
static int
send_mac_to_plugin(char * buffer, uint8_t * mac)
{
  struct Wlan_Helper_Control_Message macmsg;

  macmsg.hdr.size = htons(sizeof(struct Wlan_Helper_Control_Message));
  macmsg.hdr.type = htons(GNUNET_MESSAGE_TYPE_WLAN_HELPER_CONTROL);
  memcpy(macmsg.mac.mac, mac, sizeof(struct MacAddress));
  memcpy(buffer, &macmsg, sizeof(struct Wlan_Helper_Control_Message));
  return sizeof(struct Wlan_Helper_Control_Message);
}


static int
hardwaremode (int argc, 
	      char *argv[])
{
  uid_t uid;
  struct Hardware_Infos dev;
  char readbuf[MAXLINE];
  struct sendbuf write_std;
  ssize_t ret;
  int maxfd;
  fd_set rfds;
  fd_set wfds;
  int retval;
  int stdin_open;
  struct GNUNET_SERVER_MessageStreamTokenizer * stdin_mst;

  if (2 != argc)
    {
      fprintf (stderr,
	       "This program must be started with the interface argument.\n");
      fprintf (stderr,
	       "Usage: interface-name\n");
      return 1;
    }
  if (0 != wlaninit(&dev, argv[1]))
    return 1;    
  uid = getuid();
  if (0 != setresuid(uid, uid, uid))
    {
      fprintf(stderr, 
	      "Failed to setresuid: %s\n",
	      strerror(errno));
      /* not critical, continue anyway */
    }

  dev.write_pout.size = 0;
  dev.write_pout.pos = 0;
  stdin_mst = GNUNET_SERVER_mst_create (&stdin_send_hw, &dev);

  /* send mac to STDOUT first */
  write_std.pos = 0;
  write_std.size = send_mac_to_plugin((char *) &write_std.buf, dev.pl_mac);
  stdin_open = 1;

  while (1)
    {
      maxfd = -1;
      FD_ZERO (&rfds);
      if ( (0 == dev.write_pout.size) &&
	   (1 == stdin_open) )
	{
	  FD_SET (STDIN_FILENO, &rfds);
	  maxfd = MAX (maxfd, STDIN_FILENO);
	}
      if (0 == write_std.size)
        {
          FD_SET (dev.fd_raw, &rfds);
          maxfd = MAX(maxfd, dev.fd_raw);
        }
      FD_ZERO(&wfds);
      if (0 < write_std.size)
        {
          FD_SET (STDOUT_FILENO, &wfds);
          maxfd = MAX(maxfd, STDOUT_FILENO);
        }
      if (0 < dev.write_pout.size)
        {
          FD_SET(dev.fd_raw, &wfds);
          maxfd = MAX(maxfd, dev.fd_raw);
        }
      retval = select(maxfd + 1, &rfds, &wfds, NULL, NULL);
      if ( (-1 == retval) && 
	   (EINTR == errno) )        
	continue;        
      if (0 > retval)
        {
          fprintf(stderr, 
		  "select failed: %s\n", 
		  strerror(errno));
          break;
        }

      if (FD_ISSET(STDOUT_FILENO, &wfds))
        {
          ret = write(STDOUT_FILENO, 
		      write_std.buf + write_std.pos,
		      write_std.size - write_std.pos);
          if (0 > ret)
            {
              fprintf (stderr, 
		       "Failed to write to STDOUT: %s\n",
		       strerror (errno));
              break;
            }
	  write_std.pos += ret;
	  if (write_std.pos == write_std.size)
	    {
	      write_std.pos = 0;
	      write_std.size = 0;
	    }
	}        

      if (FD_ISSET(dev.fd_raw, &wfds))
        {
	  ret = write (dev.fd_raw, 
		       dev.write_pout.buf, 
		       dev.write_pout.size);
	  if (0 > ret)
	    {
	      fprintf (stderr, 
		       "Failed to write to WLAN device: %s\n",
		       strerror (errno));
              break;
	    }
	  dev.write_pout.pos += ret;
	  if ( (dev.write_pout.pos != dev.write_pout.size) && 
	       (ret != 0) )
	    {
	      fprintf(stderr,
                      "Write error, partial send: %u/%u\n",
		      dev.write_pout.pos, dev.write_pout.size);
	      break;
	    }
	  if (dev.write_pout.pos == dev.write_pout.size)
	    {
	      dev.write_pout.pos = 0;
	      dev.write_pout.size = 0;
	    }
        }

      if (FD_ISSET(STDIN_FILENO, &rfds))
        {
          ret = read(STDIN_FILENO, readbuf, sizeof(readbuf));
          if (0 > ret)
            {
              fprintf(stderr, 
		      "Read error from STDIN: %s\n",
		      strerror (errno));
	      break;
            }
	  if (0 == ret)
	    {
	      /* stop reading... */
	      stdin_open = 0;
	    }
	  GNUNET_SERVER_mst_receive (stdin_mst, NULL, 
				     readbuf, ret,
				     GNUNET_NO, GNUNET_NO);
        }

      if (FD_ISSET(dev.fd_raw, &rfds))
        {
	  struct GNUNET_MessageHeader * header;
	  struct Radiotap_rx * rxinfo;
	  struct ieee80211_frame * datastart;

	  header = (struct GNUNET_MessageHeader *) write_std.buf;
          rxinfo = (struct Radiotap_rx *) &header[1];
          datastart = (struct ieee80211_frame *) &rxinfo[1];
          ret = linux_read (&dev,
			    (unsigned char *) datastart,
			    sizeof(write_std.buf) - sizeof(struct Radiotap_rx) - sizeof(struct GNUNET_MessageHeader), 
			    rxinfo);
          if (0 > ret)
            {
              fprintf(stderr, 
		      "Read error from raw socket: %s\n", 
		      strerror(errno));
              break;
            }
	  if ( (0 < ret) &&
	       (0 == mac_test(datastart, &dev)) )
	    {
	      write_std.size = ret + sizeof(struct GNUNET_MessageHeader) + sizeof(struct Radiotap_rx);
	      header->size = htons(write_std.size);
	      header->type = htons(GNUNET_MESSAGE_TYPE_WLAN_HELPER_DATA);
            }
        }

    }
  /* Error handling, try to clean up a bit at least */
  GNUNET_SERVER_mst_destroy(stdin_mst);
  close (dev.fd_raw);
  return 1; 
}

int
main(int argc, char *argv[])
{
  if (3 != argc)
    {
      fprintf (stderr,
	       "This program must be started with the interface and the operating mode as argument.\n");
      fprintf (stderr,
	       "Usage: interface-name options\n"
	       "options: 0 = with hardware\n"
	       "1 = first loopback file\n"
	       "2 = second loopback file\n"
	       "\n");
      return 1;
    }
  if (strstr(argv[2], "1") || strstr(argv[2], "2"))
    return testmode(argc, argv);
  return hardwaremode(argc - 1, argv);
}