irlap_frame.c

linux 内核源代码

		irlap_send_i_frame(self, tx_skb, RSP_FRAME);
	} else {
		irlap_send_ui_frame(self, skb_get(skb), self->caddr, RSP_FRAME);
		self->window -= 1;
	}
}

/*
 * Function irlap_resend_rejected_frames (nr)
 *
 *    Resend frames which has not been acknowledged. Should be safe to
 *    traverse the list without locking it since this function will only be
 *    called from interrupt context (BH)
 */
void irlap_resend_rejected_frames(struct irlap_cb *self, int command)
{
	struct sk_buff *tx_skb;
	struct sk_buff *skb;
	int count;

	IRDA_ASSERT(self != NULL, return;);
	IRDA_ASSERT(self->magic == LAP_MAGIC, return;);

	/* Initialize variables */
	count = skb_queue_len(&self->wx_list);

	/*  Resend unacknowledged frame(s) */
	skb = skb_peek(&self->wx_list);
	while (skb != NULL) {
		irlap_wait_min_turn_around(self, &self->qos_tx);

		/* We copy the skb to be retransmitted since we will have to
		 * modify it. Cloning will confuse packet sniffers
		 */
		/* tx_skb = skb_clone( skb, GFP_ATOMIC); */
		tx_skb = skb_copy(skb, GFP_ATOMIC);
		if (!tx_skb) {
			IRDA_DEBUG(0, "%s(), unable to copy\n", __FUNCTION__);
			return;
		}

		/* Clear old Nr field + poll bit */
		tx_skb->data[1] &= 0x0f;

		/*
		 *  Set poll bit on the last frame retransmitted
		 */
		if (count-- == 1)
			tx_skb->data[1] |= PF_BIT; /* Set p/f bit */
		else
			tx_skb->data[1] &= ~PF_BIT; /* Clear p/f bit */

		irlap_send_i_frame(self, tx_skb, command);

		/*
		 *  If our skb is the last buffer in the list, then
		 *  we are finished, if not, move to the next sk-buffer
		 */
		if (skb == skb_peek_tail(&self->wx_list))
			skb = NULL;
		else
			skb = skb->next;
	}
#if 0 /* Not yet */
	/*
	 *  We can now fill the window with additional data frames
	 */
	while (!skb_queue_empty(&self->txq)) {

		IRDA_DEBUG(0, "%s(), sending additional frames!\n", __FUNCTION__);
		if (self->window > 0) {
			skb = skb_dequeue( &self->txq);
			IRDA_ASSERT(skb != NULL, return;);

			/*
			 *  If send window > 1 then send frame with pf
			 *  bit cleared
			 */
			if ((self->window > 1) &&
			    !skb_queue_empty(&self->txq)) {
				irlap_send_data_primary(self, skb);
			} else {
				irlap_send_data_primary_poll(self, skb);
			}
			kfree_skb(skb);
		}
	}
#endif
}

void irlap_resend_rejected_frame(struct irlap_cb *self, int command)
{
	struct sk_buff *tx_skb;
	struct sk_buff *skb;

	IRDA_ASSERT(self != NULL, return;);
	IRDA_ASSERT(self->magic == LAP_MAGIC, return;);

	/*  Resend unacknowledged frame(s) */
	skb = skb_peek(&self->wx_list);
	if (skb != NULL) {
		irlap_wait_min_turn_around(self, &self->qos_tx);

		/* We copy the skb to be retransmitted since we will have to
		 * modify it. Cloning will confuse packet sniffers
		 */
		/* tx_skb = skb_clone( skb, GFP_ATOMIC); */
		tx_skb = skb_copy(skb, GFP_ATOMIC);
		if (!tx_skb) {
			IRDA_DEBUG(0, "%s(), unable to copy\n", __FUNCTION__);
			return;
		}

		/* Clear old Nr field + poll bit */
		tx_skb->data[1] &= 0x0f;

		/*  Set poll/final bit */
		tx_skb->data[1] |= PF_BIT; /* Set p/f bit */

		irlap_send_i_frame(self, tx_skb, command);
	}
}

/*
 * Function irlap_send_ui_frame (self, skb, command)
 *
 *    Contruct and transmit an Unnumbered Information (UI) frame
 *
 */
void irlap_send_ui_frame(struct irlap_cb *self, struct sk_buff *skb,
			 __u8 caddr, int command)
{
	IRDA_DEBUG(4, "%s()\n", __FUNCTION__);

	IRDA_ASSERT(self != NULL, return;);
	IRDA_ASSERT(self->magic == LAP_MAGIC, return;);
	IRDA_ASSERT(skb != NULL, return;);

	/* Insert connection address */
	skb->data[0] = caddr | ((command) ? CMD_FRAME : 0);

	irlap_queue_xmit(self, skb);
}

/*
 * Function irlap_send_i_frame (skb)
 *
 *    Contruct and transmit Information (I) frame
 */
static void irlap_send_i_frame(struct irlap_cb *self, struct sk_buff *skb,
			       int command)
{
	/* Insert connection address */
	skb->data[0] = self->caddr;
	skb->data[0] |= (command) ? CMD_FRAME : 0;

	/* Insert next to receive (Vr) */
	skb->data[1] |= (self->vr << 5);  /* insert nr */

	irlap_queue_xmit(self, skb);
}

/*
 * Function irlap_recv_i_frame (skb, frame)
 *
 *    Receive and parse an I (Information) frame, no harm in making it inline
 *    since it's called only from one single place (irlap_driver_rcv).
 */
static inline void irlap_recv_i_frame(struct irlap_cb *self,
				      struct sk_buff *skb,
				      struct irlap_info *info, int command)
{
	info->nr = skb->data[1] >> 5;          /* Next to receive */
	info->pf = skb->data[1] & PF_BIT;      /* Final bit */
	info->ns = (skb->data[1] >> 1) & 0x07; /* Next to send */

	/* Check if this is a command or a response frame */
	if (command)
		irlap_do_event(self, RECV_I_CMD, skb, info);
	else
		irlap_do_event(self, RECV_I_RSP, skb, info);
}

/*
 * Function irlap_recv_ui_frame (self, skb, info)
 *
 *    Receive and parse an Unnumbered Information (UI) frame
 *
 */
static void irlap_recv_ui_frame(struct irlap_cb *self, struct sk_buff *skb,
				struct irlap_info *info)
{
	IRDA_DEBUG( 4, "%s()\n", __FUNCTION__);

	info->pf = skb->data[1] & PF_BIT;      /* Final bit */

	irlap_do_event(self, RECV_UI_FRAME, skb, info);
}

/*
 * Function irlap_recv_frmr_frame (skb, frame)
 *
 *    Received Frame Reject response.
 *
 */
static void irlap_recv_frmr_frame(struct irlap_cb *self, struct sk_buff *skb,
				  struct irlap_info *info)
{
	__u8 *frame;
	int w, x, y, z;

	IRDA_DEBUG(0, "%s()\n", __FUNCTION__);

	IRDA_ASSERT(self != NULL, return;);
	IRDA_ASSERT(self->magic == LAP_MAGIC, return;);
	IRDA_ASSERT(skb != NULL, return;);
	IRDA_ASSERT(info != NULL, return;);

	if (!pskb_may_pull(skb, 4)) {
		IRDA_ERROR("%s: frame too short!\n", __FUNCTION__);
		return;
	}

	frame = skb->data;

	info->nr = frame[2] >> 5;          /* Next to receive */
	info->pf = frame[2] & PF_BIT;      /* Final bit */
	info->ns = (frame[2] >> 1) & 0x07; /* Next to send */

	w = frame[3] & 0x01;
	x = frame[3] & 0x02;
	y = frame[3] & 0x04;
	z = frame[3] & 0x08;

	if (w) {
		IRDA_DEBUG(0, "Rejected control field is undefined or not "
		      "implemented.\n");
	}
	if (x) {
		IRDA_DEBUG(0, "Rejected control field was invalid because it "
		      "contained a non permitted I field.\n");
	}
	if (y) {
		IRDA_DEBUG(0, "Received I field exceeded the maximum negotiated "
		      "for the existing connection or exceeded the maximum "
		      "this station supports if no connection exists.\n");
	}
	if (z) {
		IRDA_DEBUG(0, "Rejected control field control field contained an "
		      "invalid Nr count.\n");
	}
	irlap_do_event(self, RECV_FRMR_RSP, skb, info);
}

/*
 * Function irlap_send_test_frame (self, daddr)
 *
 *    Send a test frame response
 *
 */
void irlap_send_test_frame(struct irlap_cb *self, __u8 caddr, __u32 daddr,
			   struct sk_buff *cmd)
{
	struct sk_buff *tx_skb;
	struct test_frame *frame;
	__u8 *info;

	tx_skb = alloc_skb(cmd->len + sizeof(struct test_frame), GFP_ATOMIC);
	if (!tx_skb)
		return;

	/* Broadcast frames must include saddr and daddr fields */
	if (caddr == CBROADCAST) {
		frame = (struct test_frame *)
			skb_put(tx_skb, sizeof(struct test_frame));

		/* Insert the swapped addresses */
		frame->saddr = cpu_to_le32(self->saddr);
		frame->daddr = cpu_to_le32(daddr);
	} else
		frame = (struct test_frame *) skb_put(tx_skb, LAP_ADDR_HEADER + LAP_CTRL_HEADER);

	frame->caddr = caddr;
	frame->control = TEST_RSP | PF_BIT;

	/* Copy info */
	info = skb_put(tx_skb, cmd->len);
	memcpy(info, cmd->data, cmd->len);

	/* Return to sender */
	irlap_wait_min_turn_around(self, &self->qos_tx);
	irlap_queue_xmit(self, tx_skb);
}

/*
 * Function irlap_recv_test_frame (self, skb)
 *
 *    Receive a test frame
 *
 */
static void irlap_recv_test_frame(struct irlap_cb *self, struct sk_buff *skb,
				  struct irlap_info *info, int command)
{
	struct test_frame *frame;

	IRDA_DEBUG(2, "%s()\n", __FUNCTION__);

	if (!pskb_may_pull(skb, sizeof(*frame))) {
		IRDA_ERROR("%s: frame too short!\n", __FUNCTION__);
		return;
	}
	frame = (struct test_frame *) skb->data;

	/* Broadcast frames must carry saddr and daddr fields */
	if (info->caddr == CBROADCAST) {
		if (skb->len < sizeof(struct test_frame)) {
			IRDA_DEBUG(0, "%s() test frame too short!\n",
				   __FUNCTION__);
			return;
		}

		/* Read and swap addresses */
		info->daddr = le32_to_cpu(frame->saddr);
		info->saddr = le32_to_cpu(frame->daddr);

		/* Make sure frame is addressed to us */
		if ((info->saddr != self->saddr) &&
		    (info->saddr != BROADCAST)) {
			return;
		}
	}

	if (command)
		irlap_do_event(self, RECV_TEST_CMD, skb, info);
	else
		irlap_do_event(self, RECV_TEST_RSP, skb, info);
}

/*
 * Function irlap_driver_rcv (skb, netdev, ptype)
 *
 *    Called when a frame is received. Dispatches the right receive function
 *    for processing of the frame.
 *
 * Note on skb management :
 * After calling the higher layers of the IrDA stack, we always
 * kfree() the skb, which drop the reference count (and potentially
 * destroy it).
 * If a higher layer of the stack want to keep the skb around (to put
 * in a queue or pass it to the higher layer), it will need to use
 * skb_get() to keep a reference on it. This is usually done at the
 * LMP level in irlmp.c.
 * Jean II
 */
int irlap_driver_rcv(struct sk_buff *skb, struct net_device *dev,
		     struct packet_type *ptype, struct net_device *orig_dev)
{
	struct irlap_info info;
	struct irlap_cb *self;
	int command;
	__u8 control;

	if (dev->nd_net != &init_net)
		goto out;

	/* FIXME: should we get our own field? */
	self = (struct irlap_cb *) dev->atalk_ptr;

	/* If the net device is down, then IrLAP is gone! */
	if (!self || self->magic != LAP_MAGIC) {
		dev_kfree_skb(skb);
		return -1;
	}

	/* We are no longer an "old" protocol, so we need to handle
	 * share and non linear skbs. This should never happen, so
	 * we don't need to be clever about it. Jean II */
	if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL) {
		IRDA_ERROR("%s: can't clone shared skb!\n", __FUNCTION__);
		dev_kfree_skb(skb);
		return -1;
	}

	/* Check if frame is large enough for parsing */
	if (!pskb_may_pull(skb, 2)) {
		IRDA_ERROR("%s: frame too short!\n", __FUNCTION__);
		dev_kfree_skb(skb);
		return -1;
	}

	command    = skb->data[0] & CMD_FRAME;
	info.caddr = skb->data[0] & CBROADCAST;

	info.pf      = skb->data[1] &  PF_BIT;
	info.control = skb->data[1] & ~PF_BIT; /* Mask away poll/final bit */

	control = info.control;

	/*  First we check if this frame has a valid connection address */
	if ((info.caddr != self->caddr) && (info.caddr != CBROADCAST)) {
		IRDA_DEBUG(0, "%s(), wrong connection address!\n",
			   __FUNCTION__);
		goto out;
	}
	/*
	 *  Optimize for the common case and check if the frame is an
	 *  I(nformation) frame. Only I-frames have bit 0 set to 0
	 */
	if (~control & 0x01) {
		irlap_recv_i_frame(self, skb, &info, command);
		goto out;
	}
	/*
	 *  We now check is the frame is an S(upervisory) frame. Only
	 *  S-frames have bit 0 set to 1 and bit 1 set to 0
	 */
	if (~control & 0x02) {
		/*
		 *  Received S(upervisory) frame, check which frame type it is
		 *  only the first nibble is of interest
		 */
		switch (control & 0x0f) {
		case RR:
			irlap_recv_rr_frame(self, skb, &info, command);
			break;
		case RNR:
			irlap_recv_rnr_frame(self, skb, &info, command);
			break;
		case REJ:
			irlap_recv_rej_frame(self, skb, &info, command);
			break;
		case SREJ:
			irlap_recv_srej_frame(self, skb, &info, command);
			break;
		default:
			IRDA_WARNING("%s: Unknown S-frame %02x received!\n",
				__FUNCTION__, info.control);
			break;
		}
		goto out;
	}
	/*
	 *  This must be a C(ontrol) frame
	 */
	switch (control) {
	case XID_RSP:
		irlap_recv_discovery_xid_rsp(self, skb, &info);
		break;
	case XID_CMD:
		irlap_recv_discovery_xid_cmd(self, skb, &info);
		break;
	case SNRM_CMD:
		irlap_recv_snrm_cmd(self, skb, &info);
		break;
	case DM_RSP:
		irlap_do_event(self, RECV_DM_RSP, skb, &info);
		break;
	case DISC_CMD: /* And RD_RSP since they have the same value */
		irlap_recv_disc_frame(self, skb, &info, command);
		break;
	case TEST_CMD:
		irlap_recv_test_frame(self, skb, &info, command);
		break;
	case UA_RSP:
		irlap_recv_ua_frame(self, skb, &info);
		break;
	case FRMR_RSP:
		irlap_recv_frmr_frame(self, skb, &info);
		break;
	case UI_FRAME:
		irlap_recv_ui_frame(self, skb, &info);
		break;
	default:
		IRDA_WARNING("%s: Unknown frame %02x received!\n",
				__FUNCTION__, info.control);
		break;
	}
out:
	/* Always drop our reference on the skb */
	dev_kfree_skb(skb);
	return 0;
}