irnet_ppp.c

Linux内核源代码 为压缩文件 是<<Linux内核>>一书中的源代码

  else
    mask |= irnet_ctrl_poll(ap, file, wait);

  DEXIT(FS_TRACE, " - mask=0x%X\n", mask);
  return(mask);
}

/*------------------------------------------------------------------*/
/*
 * IOCtl : Called when someone does some ioctls on /dev/irnet
 * This is the way pppd configure us and control us while the PPP
 * instance is active.
 */
static int
dev_irnet_ioctl(struct inode *	inode,
		struct file *	file,
		unsigned int	cmd,
		unsigned long	arg)
{
  irnet_socket *	ap = (struct irnet_socket *) file->private_data;
  int			err;
  int			val;

  DENTER(FS_TRACE, "(file=0x%X, ap=0x%X, cmd=0x%X)\n",
	 (unsigned int) file, (unsigned int) ap, cmd);

  /* Basic checks... */
  DASSERT(ap != NULL, -ENXIO, PPP_ERROR, "ap is NULL...\n");
#ifdef SECURE_DEVIRNET
  if(!capable(CAP_NET_ADMIN))
    return -EPERM;
#endif SECURE_DEVIRNET

  err = -EFAULT;
  switch(cmd)
    {
      /* Set discipline (should be N_SYNC_PPP or N_TTY) */
    case TIOCSETD:
      if(get_user(val, (int *) arg))
	break;
      if((val == N_SYNC_PPP) || (val == N_PPP))
	{
	  DEBUG(FS_INFO, "Entering PPP discipline.\n");
	  /* PPP channel setup */
	  ap->chan.private = ap;
	  ap->chan.ops = &irnet_ppp_ops;
	  ap->chan.mtu = PPP_MRU;
	  err = ppp_register_channel(&ap->chan);
	  if(err == 0)
	    {
	      /* Our ppp side is active */
	      ap->ppp_open = 1;

	      DEBUG(FS_INFO, "Trying to establish a connection.\n");
	      /* Setup the IrDA link now - may fail... */
	      irda_irnet_connect(ap);
	    }
	  else
	    DERROR(FS_ERROR, "Can't setup PPP channel...\n");
	}
      else
	{
	  /* In theory, should be N_TTY */
	  DEBUG(FS_INFO, "Exiting PPP discipline.\n");
	  /* Disconnect from the generic PPP layer */
	  if(ap->ppp_open)
	    ppp_unregister_channel(&ap->chan);
	  else
	    DERROR(FS_ERROR, "Channel not registered !\n");
	  ap->ppp_open = 0;
	  err = 0;
	}
      break;

      /* Attach this PPP instance to the PPP driver (set it active) */
    case PPPIOCATTACH:
    case PPPIOCDETACH:
      if(ap->ppp_open)
	err = ppp_channel_ioctl(&ap->chan, cmd, arg);
      else
	DERROR(FS_ERROR, "Channel not registered !\n");
      break;

      /* Query PPP channel and unit number */
    case PPPIOCGCHAN:
      if(!ap->ppp_open)
	break;
      if(put_user(ppp_channel_index(&ap->chan), (int *) arg))
	break;
      DEBUG(FS_INFO, "Query channel.\n");
      err = 0;
      break;
    case PPPIOCGUNIT:
      if(!ap->ppp_open)
	break;
      if(put_user(ppp_unit_number(&ap->chan), (int *) arg))
	break;
      DEBUG(FS_INFO, "Query unit number.\n");
      err = 0;
      break;

      /* All these ioctls can be passed both directly and from ppp_generic,
       * so we just deal with them in one place...
       */
    case PPPIOCGFLAGS:
    case PPPIOCSFLAGS:
    case PPPIOCGASYNCMAP:
    case PPPIOCSASYNCMAP:
    case PPPIOCGRASYNCMAP:
    case PPPIOCSRASYNCMAP:
    case PPPIOCGXASYNCMAP:
    case PPPIOCSXASYNCMAP:
    case PPPIOCGMRU:
    case PPPIOCSMRU:
      DEBUG(FS_INFO, "Standard PPP ioctl.\n");
      if(!capable(CAP_NET_ADMIN))
	err = -EPERM;
      else
	err = ppp_irnet_ioctl(&ap->chan, cmd, arg);
      break;

      /* TTY IOCTLs : Pretend that we are a tty, to keep pppd happy */
      /* Get termios */
    case TCGETS:
      DEBUG(FS_INFO, "Get termios.\n");
      if(kernel_termios_to_user_termios((struct termios *)arg, &ap->termios))
	break;
      err = 0;
      break;
      /* Set termios */
    case TCSETSF:
      DEBUG(FS_INFO, "Set termios.\n");
      if(user_termios_to_kernel_termios(&ap->termios, (struct termios *) arg))
	break;
      err = 0;
      break;

      /* Set DTR/RTS */
    case TIOCMBIS: 
    case TIOCMBIC:
      /* Set exclusive/non-exclusive mode */
    case TIOCEXCL:
    case TIOCNXCL:
      DEBUG(FS_INFO, "TTY compatibility.\n");
      err = 0;
      break;

    case TCGETA:
      DEBUG(FS_INFO, "TCGETA\n");
      break;

    case TCFLSH:
      DEBUG(FS_INFO, "TCFLSH\n");
      /* Note : this will flush buffers in PPP, so it *must* be done
       * We should also worry that we don't accept junk here and that
       * we get rid of our own buffers */
#ifdef FLUSH_TO_PPP
      ppp_output_wakeup(&ap->chan);
#endif FLUSH_TO_PPP
      err = 0;
      break;

    case FIONREAD:
      DEBUG(FS_INFO, "FIONREAD\n");
      val = 0;
      if(put_user(val, (int *) arg))
	break;
      err = 0;
      break;

    default:
      DERROR(FS_ERROR, "Unsupported ioctl (0x%X)\n", cmd);
      err = -ENOIOCTLCMD;
    }

  DEXIT(FS_TRACE, " - err = 0x%X\n", err);
  return err;
}

/************************** PPP CALLBACKS **************************/
/*
 * This are the functions that the generic PPP driver in the kernel
 * will call to communicate to us.
 */

/*------------------------------------------------------------------*/
/*
 * Prepare the ppp frame for transmission over the IrDA socket.
 * We make sure that the header space is enough, and we change ppp header
 * according to flags passed by pppd.
 * This is not a callback, but just a helper function used in ppp_irnet_send()
 */
static inline struct sk_buff *
irnet_prepare_skb(irnet_socket *	ap,
		  struct sk_buff *	skb)
{
  unsigned char *	data;
  int			proto;		/* PPP protocol */
  int			islcp;		/* Protocol == LCP */
  int			needaddr;	/* Need PPP address */

  DENTER(PPP_TRACE, "(ap=0x%X, skb=0x%X)\n",
	 (unsigned int) ap, (unsigned int) skb);

  /* Extract PPP protocol from the frame */
  data  = skb->data;
  proto = (data[0] << 8) + data[1];

  /* LCP packets with codes between 1 (configure-request)
   * and 7 (code-reject) must be sent as though no options
   * have been negotiated. */
  islcp = (proto == PPP_LCP) && (1 <= data[2]) && (data[2] <= 7);

  /* compress protocol field if option enabled */
  if((data[0] == 0) && (ap->flags & SC_COMP_PROT) && (!islcp))
    skb_pull(skb,1);

  /* Check if we need address/control fields */
  needaddr = 2*((ap->flags & SC_COMP_AC) == 0 || islcp);

  /* Is the skb headroom large enough to contain all IrDA-headers? */
  if((skb_headroom(skb) < (ap->max_header_size + needaddr)) ||
      (skb_shared(skb)))
    {
      struct sk_buff *	new_skb;

      DEBUG(PPP_INFO, "Reallocating skb\n");

      /* Create a new skb */
      new_skb = skb_realloc_headroom(skb, ap->max_header_size + needaddr);

      /* We have to free the original skb anyway */
      dev_kfree_skb(skb);

      /* Did the realloc succeed ? */
      DABORT(new_skb == NULL, NULL, PPP_ERROR, "Could not realloc skb\n");

      /* Use the new skb instead */
      skb = new_skb;
    }

  /* prepend address/control fields if necessary */
  if(needaddr)
    {
      skb_push(skb,2);
      skb->data[0] = PPP_ALLSTATIONS;
      skb->data[1] = PPP_UI;
    }

  DEXIT(PPP_TRACE, "\n");

  return skb;
}

/*------------------------------------------------------------------*/
/*
 * Send a packet to the peer over the IrTTP connection.
 * Returns 1 iff the packet was accepted.
 * Returns 0 iff packet was not consumed.
 * If the packet was not accepted, we will call ppp_output_wakeup
 * at some later time to reactivate flow control in ppp_generic.
 */
static int
ppp_irnet_send(struct ppp_channel *	chan,
	       struct sk_buff *		skb)
{
  irnet_socket *	self = (struct irnet_socket *) chan->private;
  int			ret;

  DENTER(PPP_TRACE, "(channel=0x%X, ap/self=0x%X)\n",
	 (unsigned int) chan, (unsigned int) self);

  /* Check if things are somewhat valid... */
  DASSERT(self != NULL, 0, PPP_ERROR, "Self is NULL !!!\n");

  /* Check if we are connected */
  if(self->ttp_open == 0)
    {
#ifdef CONNECT_IN_SEND
      /* Let's try to connect one more time... */
      /* Note : we won't connect fully yet, but we should be ready for
       * next packet... */
      /* Note : we can't do that, we need to have a process context to
       * go through interruptible_sleep_on() in irnet_find_lsap_sel()
       * We need to find another way... */
      irda_irnet_connect(self);
#endif CONNECT_IN_SEND

      DEBUG(PPP_INFO, "IrTTP not ready ! (%d-0x%X)\n",
	    self->ttp_open, (unsigned int) self->tsap);

      /* Note : we can either drop the packet or block the packet.
       *
       * Blocking the packet allow us a better connection time,
       * because by calling ppp_output_wakeup() we can have
       * ppp_generic resending the LCP request immediately to us,
       * rather than waiting for one of pppd periodic transmission of
       * LCP request.
       *
       * On the other hand, if we block all packet, all those periodic
       * transmissions of pppd accumulate in ppp_generic, creating a
       * backlog of LCP request. When we eventually connect later on,
       * we have to transmit all this backlog before we can connect
       * proper (if we don't timeout before).
       *
       * The current strategy is as follow :
       * While we are attempting to connect, we block packets to get
       * a better connection time.
       * If we fail to connect, we drain the queue and start dropping packets
       */
#ifdef BLOCK_WHEN_CONNECT
      /* If we are attempting to connect */
      if(self->tsap)
	{
	  /* Blocking packet, ppp_generic will retry later */
	  return 0;
	}
#endif BLOCK_WHEN_CONNECT

      /* Dropping packet, pppd will retry later */
      dev_kfree_skb(skb);
      return 1;
    }

  /* Check if the queue can accept any packet, otherwise block */
  if(self->tx_flow != FLOW_START)
    DRETURN(0, PPP_INFO, "IrTTP queue full (%d skbs)...\n",
	    skb_queue_len(&self->tsap->tx_queue));

  /* Prepare ppp frame for transmission */
  skb = irnet_prepare_skb(self, skb);
  DABORT(skb == NULL, 1, PPP_ERROR, "Prepare skb for Tx failed.\n");

  /* Send the packet to IrTTP */
  ret = irttp_data_request(self->tsap, skb);
  if(ret < 0)
    {
      /*   
       * > IrTTPs tx queue is full, so we just have to
       * > drop the frame! You might think that we should
       * > just return -1 and don't deallocate the frame,
       * > but that is dangerous since it's possible that
       * > we have replaced the original skb with a new
       * > one with larger headroom, and that would really
       * > confuse do_dev_queue_xmit() in dev.c! I have
       * > tried :-) DB 
       * Correction : we verify the flow control above (self->tx_flow),
       * so we come here only if IrTTP doesn't like the packet (empty,
       * too large, IrTTP not connected). In those rare cases, it's ok
       * to drop it, we don't want to see it here again...
       * Jean II
       */
      DERROR(PPP_ERROR, "IrTTP doesn't like this packet !!! (0x%X)\n", ret);
      dev_kfree_skb(skb);
    }

  DEXIT(PPP_TRACE, "\n");
  return 1;	/* Packet has been consumed */
}

/*------------------------------------------------------------------*/
/*
 * Take care of the ioctls that ppp_generic doesn't want to deal with...
 * Note : we are also called from dev_irnet_ioctl().
 */
static int
ppp_irnet_ioctl(struct ppp_channel *	chan,
		unsigned int		cmd,
		unsigned long		arg)
{
  irnet_socket *	ap = (struct irnet_socket *) chan->private;
  int			err;
  int			val;
  u32			accm[8];

  DENTER(PPP_TRACE, "(channel=0x%X, ap=0x%X, cmd=0x%X)\n",
	 (unsigned int) chan, (unsigned int) ap, cmd);

  /* Basic checks... */
  DASSERT(ap != NULL, -ENXIO, PPP_ERROR, "ap is NULL...\n");

  err = -EFAULT;
  switch(cmd)
    {
      /* PPP flags */
    case PPPIOCGFLAGS:
      val = ap->flags | ap->rbits;
      if(put_user(val, (int *) arg))
	break;
      err = 0;
      break;
    case PPPIOCSFLAGS:
      if(get_user(val, (int *) arg))
	break;
      ap->flags = val & ~SC_RCV_BITS;
      ap->rbits = val & SC_RCV_BITS;
      err = 0;
      break;

      /* Async map stuff - all dummy to please pppd */
    case PPPIOCGASYNCMAP:
      if(put_user(ap->xaccm[0], (u32 *) arg))
	break;
      err = 0;
      break;
    case PPPIOCSASYNCMAP:
      if(get_user(ap->xaccm[0], (u32 *) arg))
	break;
      err = 0;
      break;
    case PPPIOCGRASYNCMAP:
      if(put_user(ap->raccm, (u32 *) arg))
	break;
      err = 0;
      break;
    case PPPIOCSRASYNCMAP:
      if(get_user(ap->raccm, (u32 *) arg))
	break;
      err = 0;
      break;
    case PPPIOCGXASYNCMAP:
      if(copy_to_user((void *) arg, ap->xaccm, sizeof(ap->xaccm)))
	break;
      err = 0;
      break;
    case PPPIOCSXASYNCMAP:
      if(copy_from_user(accm, (void *) arg, sizeof(accm)))
	break;
      accm[2] &= ~0x40000000U;		/* can't escape 0x5e */
      accm[3] |= 0x60000000U;		/* must escape 0x7d, 0x7e */
      memcpy(ap->xaccm, accm, sizeof(ap->xaccm));
      err = 0;
      break;

      /* Max PPP frame size */
    case PPPIOCGMRU:
      if(put_user(ap->mru, (int *) arg))
	break;
      err = 0;
      break;
    case PPPIOCSMRU:
      if(get_user(val, (int *) arg))
	break;
      if(val < PPP_MRU)
	val = PPP_MRU;
      ap->mru = val;
      err = 0;
      break;

    default:
      DEBUG(PPP_INFO, "Unsupported ioctl (0x%X)\n", cmd);
      err = -ENOIOCTLCMD;
    }

  DEXIT(PPP_TRACE, " - err = 0x%X\n", err);
  return err;
}

/************************** INITIALISATION **************************/
/*
 * Module initialisation and all that jazz...
 */

/*------------------------------------------------------------------*/
/*
 * Hook our device callbacks in the filesystem, to connect our code
 * to /dev/irnet
 */
int
ppp_irnet_init(void)
{
  int err = 0;

  DENTER(MODULE_TRACE, "()\n");

  /* Allocate ourselves as a minor in the misc range */
  err = misc_register(&irnet_misc_device);

  DEXIT(MODULE_TRACE, "\n");
  return err;
}

/*------------------------------------------------------------------*/
/*
 * Cleanup at exit...
 */
void
ppp_irnet_cleanup(void)
{
  DENTER(MODULE_TRACE, "()\n");

  /* De-allocate /dev/irnet minor in misc range */
  misc_deregister(&irnet_misc_device);

  DEXIT(MODULE_TRACE, "\n");
}

#ifdef MODULE
/*------------------------------------------------------------------*/
/*
 * Module main entry point
 */
int
init_module(void)
{
  int err;

  /* Initialise both parts... */
  err = irda_irnet_init();
  if(!err)
    err = ppp_irnet_init();
  return err;
}

/*------------------------------------------------------------------*/
/*
 * Module exit
 */
void
cleanup_module(void)
{
  irda_irnet_cleanup();
  return ppp_irnet_cleanup();
}
#endif /* MODULE */