pcap-dos.c

Windows XP下的抓包程序实现

    else if (IN_CLASSC(*netmask))
       *localnet = IN_CLASSC_NET;
    else
    {
      sprintf (errbuf, "inet class for 0x%lx unknown", *netmask);
      return (-1);
    }
  }
  ARGSUSED (device);
  return (0);
}      

/*
 * Get a list of all interfaces that are present and that we probe okay.
 * Returns -1 on error, 0 otherwise.
 * The list, as returned through "alldevsp", may be null if no interfaces
 * were up and could be opened.
 */
int pcap_findalldevs (pcap_if_t **alldevsp, char *errbuf)
{
  struct device     *dev;
  struct sockaddr_ll sa_ll_1, sa_ll_2;
  struct sockaddr   *addr, *netmask, *broadaddr, *dstaddr;
  pcap_if_t *devlist = NULL;
  int       ret = 0;
  size_t    addr_size = sizeof(struct sockaddr_ll);

  for (dev = (struct device*)dev_base; dev; dev = dev->next)
  {
    PCAP_ASSERT (dev->probe);

    if (!(*dev->probe)(dev))
       continue;

    PCAP_ASSERT (dev->close);  /* set by probe routine */
    FLUSHK();
    (*dev->close) (dev);

    memset (&sa_ll_1, 0, sizeof(sa_ll_1));
    memset (&sa_ll_2, 0, sizeof(sa_ll_2));
    sa_ll_1.sll_family = AF_PACKET;
    sa_ll_2.sll_family = AF_PACKET;

    addr      = (struct sockaddr*) &sa_ll_1;
    netmask   = (struct sockaddr*) &sa_ll_1;
    dstaddr   = (struct sockaddr*) &sa_ll_1;
    broadaddr = (struct sockaddr*) &sa_ll_2;
    memset (&sa_ll_2.sll_addr, 0xFF, sizeof(sa_ll_2.sll_addr));

    if (pcap_add_if(&devlist, dev->name, dev->flags,
                    dev->long_name, errbuf) < 0)
    {
      ret = -1;
      break;
    }
    if (add_addr_to_iflist(&devlist,dev->name, dev->flags, addr, addr_size,
                           netmask, addr_size, broadaddr, addr_size,
                           dstaddr, addr_size, errbuf) < 0)
    {
      ret = -1;
      break;
    }
  }

  if (devlist && ret < 0)
  {
    pcap_freealldevs (devlist);
    devlist = NULL;
  }
  else
  if (!devlist)
     strcpy (errbuf, "No drivers found");

  *alldevsp = devlist;
  return (ret);
}

/*
 * pcap_assert() is mainly used for debugging
 */
void pcap_assert (const char *what, const char *file, unsigned line)
{
  FLUSHK();
  fprintf (stderr, "%s (%u): Assertion \"%s\" failed\n",
           file, line, what);
  close_driver();
  _exit (-1);
}

/*
 * For pcap_offline_read(): wait and yield between printing packets
 * to simulate the pace packets where actually recorded.
 */
void pcap_set_wait (pcap_t *p, void (*yield)(void), int wait)
{
  if (p)
  {
    p->wait_proc         = yield;
    p->inter_packet_wait = wait;
  }
}

/*
 * Initialise a named network device.
 */
static struct device *
open_driver (const char *dev_name, char *ebuf, int promisc)
{
  struct device *dev;

  for (dev = (struct device*)dev_base; dev; dev = dev->next)
  {
    PCAP_ASSERT (dev->name);

    if (strcmp (dev_name,dev->name))
       continue;

    if (!probed_dev)   /* user didn't call pcap_lookupdev() first */
    {
      PCAP_ASSERT (dev->probe);

      if (!(*dev->probe)(dev))    /* call the xx_probe() function */
      {
        sprintf (ebuf, "failed to detect device `%s'", dev_name);
        return (NULL);
      }
      probed_dev = dev;  /* device is probed okay and may be used */
    }
    else if (dev != probed_dev)
    {
      goto not_probed;
    }

    FLUSHK();

    /* Select what traffic to receive
     */
    if (promisc)
         dev->flags |=  (IFF_ALLMULTI | IFF_PROMISC);
    else dev->flags &= ~(IFF_ALLMULTI | IFF_PROMISC);

    PCAP_ASSERT (dev->open);

    if (!(*dev->open)(dev))
    {
      sprintf (ebuf, "failed to activate device `%s'", dev_name);
      if (pktInfo.error && !strncmp(dev->name,"pkt",3))
      {
        strcat (ebuf, ": ");
        strcat (ebuf, pktInfo.error);
      }
      return (NULL);
    }

    /* Some devices need this to operate in promiscous mode
     */
    if (promisc && dev->set_multicast_list)
       (*dev->set_multicast_list) (dev);

    active_dev = dev;   /* remember our active device */
    break;
  }

  /* 'dev_name' not matched in 'dev_base' list.
   */
  if (!dev)
  {
    sprintf (ebuf, "device `%s' not supported", dev_name);
    return (NULL);
  }

not_probed:
  if (!probed_dev)
  {
    sprintf (ebuf, "device `%s' not probed", dev_name);
    return (NULL);
  }
  return (dev);
}

/*
 * Deinitialise MAC driver.
 * Set receive mode back to default mode.
 */
static void close_driver (void)
{
  /* !!todo: loop over all 'handle_to_device[]' ? */
  struct device *dev = active_dev;

  if (dev && dev->close)
  {
    (*dev->close) (dev);
    FLUSHK();
  }

  active_dev = NULL;

#ifdef USE_32BIT_DRIVERS
  if (rx_pool)
  {
    k_free (rx_pool);
    rx_pool = NULL;
  }
  if (dev)
     pcibios_exit();
#endif
}


#ifdef __DJGPP__
static void setup_signals (void (*handler)(int))
{
  signal (SIGSEGV,handler);
  signal (SIGILL, handler);
  signal (SIGFPE, handler);
}

static void exc_handler (int sig)
{
#ifdef USE_32BIT_DRIVERS
  if (active_dev->irq > 0)    /* excludes IRQ 0 */
  {
    disable_irq (active_dev->irq);
    irq_eoi_cmd (active_dev->irq);
    _printk_safe = 1;
  }
#endif

  switch (sig)
  {
    case SIGSEGV:
         fputs ("Catching SIGSEGV.\n", stderr);
         break;
    case SIGILL:
         fputs ("Catching SIGILL.\n", stderr);
         break;
    case SIGFPE:
         _fpreset();
         fputs ("Catching SIGFPE.\n", stderr);
         break;
    default:
         fprintf (stderr, "Catching signal %d.\n", sig);
  }
  exc_occured = 1;
  pcap_close_dos (NULL);
}
#endif  /* __DJGPP__ */


/*
 * Open the pcap device for the first client calling pcap_open_live()
 */
static int first_init (const char *name, char *ebuf, int promisc)
{
  struct device *dev;

#ifdef USE_32BIT_DRIVERS
  rx_pool = k_calloc (RECEIVE_BUF_SIZE, RECEIVE_QUEUE_SIZE);
  if (!rx_pool)
  {
    strcpy (ebuf, "Not enough memory (Rx pool)");
    return (0);
  }
#endif

#ifdef __DJGPP__
  setup_signals (exc_handler);
#endif

#ifdef USE_32BIT_DRIVERS
  init_32bit();
#endif

  dev = open_driver (name, ebuf, promisc);
  if (!dev)
  {
#ifdef USE_32BIT_DRIVERS
    k_free (rx_pool);
    rx_pool = NULL;
#endif

#ifdef __DJGPP__
    setup_signals (SIG_DFL);
#endif
    return (0);
  }

#ifdef USE_32BIT_DRIVERS
  /*
   * If driver is NOT a 16-bit "pkt/ndis" driver (having a 'copy_rx_buf'
   * set in it's probe handler), initialise near-memory ring-buffer for
   * the 32-bit device.
   */
  if (dev->copy_rx_buf == NULL)
  {
    dev->get_rx_buf     = get_rxbuf;
    dev->peek_rx_buf    = peek_rxbuf;
    dev->release_rx_buf = release_rxbuf;
    pktq_init (&dev->queue, RECEIVE_BUF_SIZE, RECEIVE_QUEUE_SIZE, rx_pool);
  }
#endif
  return (1);
}

#ifdef USE_32BIT_DRIVERS
static void init_32bit (void)
{
  static int init_pci = 0;

  if (!_printk_file)
     _printk_init (64*1024, NULL); /* calls atexit(printk_exit) */

  if (!init_pci)
     (void)pci_init();             /* init BIOS32+PCI interface */
  init_pci = 1;
}
#endif


/*
 * Hook functions for using Watt-32 together with pcap
 */
static char rxbuf [ETH_MAX+100]; /* rx-buffer with some margin */
static WORD etype;
static pcap_t pcap_save;

static void watt32_recv_hook (u_char *dummy, const struct pcap_pkthdr *pcap,
                              const u_char *buf)
{
  /* Fix me: assumes Ethernet II only */
  struct ether_header *ep = (struct ether_header*) buf;

  memcpy (rxbuf, buf, pcap->caplen);
  etype = ep->ether_type;
  ARGSUSED (dummy);
}

#if (WATTCP_VER >= 0x0224)
/*
 * This function is used by Watt-32 to poll for a packet.
 * i.e. it's set to bypass _eth_arrived()
 */
static void *pcap_recv_hook (WORD *type)
{
  int len = pcap_read_dos (&pcap_save, 1, watt32_recv_hook, NULL);

  if (len < 0)
     return (NULL);

  *type = etype;
  return (void*) &rxbuf;
}

/*
 * This function is called by Watt-32 (via _eth_xmit_hook).
 * If dbug_init() was called, we should trace packets sent.
 */
static int pcap_xmit_hook (const void *buf, unsigned len)
{
  int rc = 0;

  if (pcap_pkt_debug > 0)
     dbug_write ("pcap_xmit_hook: ");

  if (active_dev && active_dev->xmit)
     if ((*active_dev->xmit) (active_dev, buf, len) > 0)
        rc = len;

  if (pcap_pkt_debug > 0)
     dbug_write (rc ? "ok\n" : "fail\n");
  return (rc);
}
#endif

static int pcap_sendpacket_dos (pcap_t *p, const void *buf, size_t len)
{
  struct device *dev = p ? get_device(p->fd) : NULL;

  if (!dev || !dev->xmit)
     return (-1);
  return (*dev->xmit) (dev, buf, len);
}

/*
 * This function is called by Watt-32 in tcp_post_init().
 * We should prevent Watt-32 from using BOOTP/DHCP/RARP etc.
 */
static void (*prev_post_hook) (void);

static void pcap_init_hook (void)
{
  _w32__bootp_on = _w32__dhcp_on = _w32__rarp_on = 0;
  _w32__do_mask_req = 0;
  _w32_dynamic_host = 0;
  if (prev_post_hook)
    (*prev_post_hook)();
}

/*
 * Supress PRINT message from Watt-32's sock_init()
 */
static void null_print (void) {}

/*
 * To use features of Watt-32 (netdb functions and socket etc.)
 * we must call sock_init(). But we set various hooks to prevent
 * using normal PKTDRVR functions in pcpkt.c. This should hopefully
 * make Watt-32 and pcap co-operate.
 */
static int init_watt32 (struct pcap *pcap, const char *dev_name, char *err_buf)
{
  char *env;
  int   rc, MTU, has_ip_addr;
  int   using_pktdrv = 1;

  /* If user called sock_init() first, we need to reinit in
   * order to open debug/trace-file properly
   */
  if (_watt_is_init)
     sock_exit();

  env = getenv ("PCAP_DEBUG");
  if (env && atoi(env) > 0 &&
      pcap_pkt_debug < 0)   /* if not already set */
  {
    dbug_init();
    pcap_pkt_debug = atoi (env);
  }

  _watt_do_exit      = 0;    /* prevent sock_init() calling exit() */
  prev_post_hook     = _w32_usr_post_init;
  _w32_usr_post_init = pcap_init_hook;
  _w32_print_hook    = null_print;

  if (dev_name && strncmp(dev_name,"pkt",3))
     using_pktdrv = FALSE;

  rc = sock_init();
  has_ip_addr = (rc != 8);  /* IP-address assignment failed */

  /* if pcap is using a 32-bit driver w/o a pktdrvr loaded, we
   * just pretend Watt-32 is initialised okay.
   *
   * !! fix-me: The Watt-32 config isn't done if no pktdrvr
   *            was found. In that case my_ip_addr + sin_mask
   *            have default values. Should be taken from another
   *            ini-file/environment in any case (ref. tcpdump.ini)
   */
  _watt_is_init = 1;  

  if (!using_pktdrv || !has_ip_addr)  /* for now .... */
  {
    static const char myip[] = "192.168.0.1";
    static const char mask[] = "255.255.255.0";

    printf ("Just guessing, using IP %s and netmask %s\n", myip, mask);
    my_ip_addr    = aton (myip);
    _w32_sin_mask = aton (mask);
  }
  else if (rc && using_pktdrv)
  {
    sprintf (err_buf, "sock_init() failed, code %d", rc);
    return (0);
  }

  /* Set recv-hook for peeking in _eth_arrived().
   */
#if (WATTCP_VER >= 0x0224)
  _eth_recv_hook = pcap_recv_hook;
  _eth_xmit_hook = pcap_xmit_hook;
#endif

  /* Free the pkt-drvr handle allocated in pkt_init().
   * The above hooks should thus use the handle reopened in open_driver()
   */
  if (using_pktdrv)
  {
    _eth_release();
/*  _eth_is_init = 1; */  /* hack to get Rx/Tx-hooks in Watt-32 working */
  }

  memcpy (&pcap_save, pcap, sizeof(pcap_save));
  MTU = pkt_get_mtu();
  pcap_save.fcode.bf_insns = NULL;
  pcap_save.linktype       = _eth_get_hwtype (NULL, NULL);
  pcap_save.snapshot       = MTU > 0 ? MTU : ETH_MAX; /* assume 1514 */

#if 1
  /* prevent use of resolve() and resolve_ip()
   */
  last_nameserver = 0;
#endif