ppp.c

unix and linux net driver

{
	unsigned long flags;

	save_flags(flags);
	cli();
	ppp->flags &= ~(SC_CCP_OPEN | SC_CCP_UP | SC_COMP_RUN | SC_DECOMP_RUN);
	restore_flags(flags);
	if (ppp->flags & SC_DEBUG)
		printk(KERN_DEBUG "%s: ccp closed\n", ppp->name);
	if (ppp->sc_xc_state) {
		(*ppp->sc_xcomp->comp_free) (ppp->sc_xc_state);
		ppp->sc_xc_state = NULL;
	}

	if (ppp->sc_rc_state) {
		(*ppp->sc_rcomp->decomp_free) (ppp->sc_rc_state);
		ppp->sc_rc_state = NULL;
	}
}

/*************************************************************
 * RECEIVE-SIDE ROUTINES
 *************************************************************/

/*
 * On entry, a received frame is in skb.
 * Check it and dispose as appropriate.
 */
static int
ppp_receive_frame(struct ppp *ppp, struct sk_buff *skb)
{
	__u8	*data;
	int	count;
	int	proto;
	int	new_count;
	struct sk_buff *new_skb;
	ppp_proto_type	*proto_ptr;

	/*
	 * An empty frame is ignored. This occurs if the FLAG sequence
	 * precedes and follows each frame.
	 */
	if (skb == NULL)
		return 1;
	if (skb->len == 0) {
		KFREE_SKB(skb);
		return 1;
	}
	data = skb->data;
	count = skb->len;

	/*
	 * Generate an error if the frame is too small.
	 */
	if (count < PPP_HDRLEN + 2) {
		if (ppp->flags & SC_DEBUG)
			printk(KERN_DEBUG
			       "ppp: got runt ppp frame, %d chars\n", count);
		++ppp->estats.rx_length_errors;
		return 0;
	}

	if ( !(ppp->flags & SC_SYNC) ) { 
		/*
		 * Verify the FCS of the frame and discard the FCS characters
		 * from the end of the buffer.
		 */
		if (ppp->rfcs != PPP_GOODFCS) {
			if (ppp->flags & SC_DEBUG) {
				printk(KERN_DEBUG
				       "ppp: frame with bad fcs, length = %d\n",
				       count);
				ppp_print_buffer("bad frame", data, count);
			}
			++ppp->estats.rx_crc_errors;
			return 0;
		}
		count -= 2;		/* ignore the fcs characters */
		skb_trim(skb, count);
	}
	
	/*
	 * Process the active decompressor.
	 */
	if (ppp->sc_rc_state != NULL &&
	    (ppp->flags & SC_DECOMP_RUN) &&
	    ((ppp->flags & (SC_DC_FERROR | SC_DC_ERROR)) == 0)) {
		if (PPP_PROTOCOL(data) == PPP_COMP) {
			/*
			 * If the frame is compressed then decompress it.
			 */
			new_skb = dev_alloc_skb(ppp->mru + 128 + PPP_HDRLEN);
			if (new_skb == NULL) {
				printk(KERN_ERR "ppp_recv_frame: no memory\n");
				new_count = DECOMP_ERROR;
			} else {
				LIBERATE_SKB(new_skb);
				new_count = (*ppp->sc_rcomp->decompress)
					(ppp->sc_rc_state, data, count,
					 new_skb->data, ppp->mru + PPP_HDRLEN);
			}
			if (new_count > 0) {
				/* Frame was decompressed OK */
				KFREE_SKB(skb);
				skb = new_skb;
				count = new_count;
				data = skb_put(skb, count);

			} else {
				/*
				 * On a decompression error, we pass the
				 * compressed frame up to pppd as an
				 * error indication.
				 */
				if (ppp->flags & SC_DEBUG)
					printk(KERN_INFO "%s: decomp err %d\n",
					       ppp->name, new_count);
				if (new_skb != 0)
					KFREE_SKB(new_skb);
				if (ppp->slcomp != 0)
					slhc_toss(ppp->slcomp);
				++ppp->stats.ppp_ierrors;
				if (new_count == DECOMP_FATALERROR) {
					ppp->flags |= SC_DC_FERROR;
				} else {
					ppp->flags |= SC_DC_ERROR;
				}
			}


		} else {
			/*
			 * The frame is not compressed. Pass it to the
			 * decompression code so it can update its
			 * dictionary if necessary.
			 */
			(*ppp->sc_rcomp->incomp)(ppp->sc_rc_state,
						 data, count);
		}
	}
	else if (PPP_PROTOCOL(data) == PPP_COMP && (ppp->flags & SC_DEBUG))
		printk(KERN_INFO "%s: not decomp, rc_state=%p flags=%x\n",
		       ppp->name, ppp->sc_rc_state, ppp->flags);

	/*
	 * Count the frame and print it
	 */
	++ppp->stats.ppp_ipackets;
	ppp->stats.ppp_ioctects += count;
	if (ppp->flags & SC_LOG_INPKT)
		ppp_print_buffer ("receive frame", data, count);

	/*
	 * Find the procedure to handle this protocol.
	 * The last one is marked as protocol 0 which is the 'catch-all'
	 * to feed it to the pppd daemon.
	 */
	proto = PPP_PROTOCOL(data);
	proto_ptr = proto_list;
	while (proto_ptr->proto != 0 && proto_ptr->proto != proto)
		++proto_ptr;

	/*
	 * Update the appropriate statistic counter.
	 */
	if (!(*proto_ptr->func)(ppp, skb)) {
		KFREE_SKB(skb);
		++ppp->stats.ppp_discards;
	}

	return 1;
}

/*
 * An input error has been detected, so we need to inform
 * the VJ decompressor.
 */
static void
ppp_receive_error(struct ppp *ppp)
{
	CHECK_PPP_VOID();

	if (ppp->slcomp != 0)
		slhc_toss(ppp->slcomp);
}

/*
 * Put the input frame into the networking system for the indicated protocol
 */
static int
ppp_rcv_rx(struct ppp *ppp, __u16 proto, struct sk_buff *skb)
{

	/*
	 * Fill in a few fields of the skb and give it to netif_rx().
	 */
	skb->dev      = ppp2dev(ppp);	/* We are the device */
	skb->protocol = htons(proto);
	skb_pull(skb, PPP_HDRLEN);	/* pull off ppp header */
	skb->mac.raw   = skb->data;
	ppp->last_recv = jiffies;
	netif_rx (skb);
	return 1;
}

/*
 * Process the receipt of an IP frame
 */
static int
rcv_proto_ip(struct ppp *ppp, struct sk_buff *skb)
{
	CHECK_PPP(0);
	if ((ppp2dev(ppp)->flags & IFF_UP) && (skb->len > 0)
	    && ppp->sc_npmode[NP_IP] == NPMODE_PASS)
		return ppp_rcv_rx(ppp, ETH_P_IP, skb);
	return 0;
}

/*
 * Process the receipt of an IPv6 frame
 */
static int
rcv_proto_ipv6(struct ppp *ppp, struct sk_buff *skb)
{
	CHECK_PPP(0);
	if ((ppp2dev(ppp)->flags & IFF_UP) && (skb->len > 0)
	    && ppp->sc_npmode[NP_IPV6] == NPMODE_PASS)
		return ppp_rcv_rx(ppp, ETH_P_IPV6, skb);
	return 0;
}

/*
 * Process the receipt of an IPX frame
 */
static int
rcv_proto_ipx(struct ppp *ppp, struct sk_buff *skb)
{
	CHECK_PPP(0);
	if (((ppp2dev(ppp)->flags & IFF_UP) != 0) && (skb->len > 0)
	    && ppp->sc_npmode[NP_IPX] == NPMODE_PASS)
		return ppp_rcv_rx(ppp, ETH_P_IPX, skb);
	return 0;
}

/*
 * Process the receipt of an Appletalk frame
 */
static int
rcv_proto_at(struct ppp *ppp, struct sk_buff *skb)
{
	CHECK_PPP(0);
	if ((ppp2dev(ppp)->flags & IFF_UP) && (skb->len > 0)
	    && ppp->sc_npmode[NP_AT] == NPMODE_PASS)
		return ppp_rcv_rx(ppp, ETH_P_PPPTALK, skb);
	return 0;
}

/*
 * Process the receipt of an VJ Compressed frame
 */
static int
rcv_proto_vjc_comp(struct ppp *ppp, struct sk_buff *skb)
{
	int new_count;

	CHECK_PPP(0);
	if ((ppp->flags & SC_REJ_COMP_TCP) || ppp->slcomp == NULL)
		return 0;
	new_count = slhc_uncompress(ppp->slcomp, skb->data + PPP_HDRLEN,
				    skb->len - PPP_HDRLEN);
	if (new_count <= 0) {
		if (ppp->flags & SC_DEBUG)
			printk(KERN_NOTICE
			       "ppp: error in VJ decompression\n");
		return 0;
	}
	new_count += PPP_HDRLEN;
	if (new_count > skb->len)
		skb_put(skb, new_count - skb->len);
	else
		skb_trim(skb, new_count);
	return rcv_proto_ip(ppp, skb);
}

/*
 * Process the receipt of an VJ Un-compressed frame
 */
static int
rcv_proto_vjc_uncomp(struct ppp *ppp, struct sk_buff *skb)
{
	CHECK_PPP(0);
	if ((ppp->flags & SC_REJ_COMP_TCP) || ppp->slcomp == NULL)
		return 0;
	if (slhc_remember(ppp->slcomp, skb->data + PPP_HDRLEN,
			  skb->len - PPP_HDRLEN) <= 0) {
		if (ppp->flags & SC_DEBUG)
			printk(KERN_NOTICE "ppp: error in VJ memorizing\n");
		return 0;
	}
	return rcv_proto_ip(ppp, skb);
}

static int
rcv_proto_ccp(struct ppp *ppp, struct sk_buff *skb)
{
	CHECK_PPP(0);
	ppp_proto_ccp (ppp, skb->data + PPP_HDRLEN, skb->len - PPP_HDRLEN, 1);
	return rcv_proto_unknown(ppp, skb);
}

/*
 * Receive all unclassified protocols.
 */
static int
rcv_proto_unknown(struct ppp *ppp, struct sk_buff *skb)
{
	CHECK_PPP(0);

	/*
	 * Limit queue length by dropping old frames.
	 */
	skb_queue_tail(&ppp->rcv_q, skb);
	while (ppp->rcv_q.qlen > PPP_MAX_RCV_QLEN) {
		struct sk_buff *skb = skb_dequeue(&ppp->rcv_q);
		if (skb)
			KFREE_SKB(skb);
	}

	wake_up_interruptible (&ppp->read_wait);
	if (ppp->tty->fasync != NULL)
		kill_fasync (ppp->tty->fasync, SIGIO);

	return 1;
}

/*************************************************************
 * TRANSMIT-SIDE ROUTINES
 *************************************************************/

/* local function to store a value into the LQR frame */
extern inline __u8 * store_long (register __u8 *p, register int value) {
	*p++ = (__u8) (value >> 24);
	*p++ = (__u8) (value >> 16);
	*p++ = (__u8) (value >>	 8);
	*p++ = (__u8) value;
	return p;
}

/*
 * Compress and send an frame to the peer.
 * Should be called with xmit_busy == 1, having been set by the caller.
 * That is, we use xmit_busy as a lock to prevent reentry of this
 * procedure.
 */
static void
ppp_send_frame(struct ppp *ppp, struct sk_buff *skb)
{
	int	proto;
	__u8	*data;
	int	count;
	__u8	*p;
	int	ret;

	CHECK_PPP_VOID();
	data = skb->data;
	count = skb->len;

	/* dump the buffer */
	if (ppp->flags & SC_LOG_OUTPKT)
		ppp_print_buffer ("write frame", data, count);

	/*
	 * Handle various types of protocol-specific compression
	 * and other processing, including:
	 * - VJ TCP header compression
	 * - updating LQR packets
	 * - updating CCP state on CCP packets
	 */
	proto = PPP_PROTOCOL(data);
	switch (proto) {
	case PPP_IP:
		if ((ppp->flags & SC_COMP_TCP) && ppp->slcomp != NULL)
			skb = ppp_vj_compress(ppp, skb);
		break;

	case PPP_LQR:
		/*
		 * Update the LQR frame with the current MIB information.
		 * This way the information is accurate and up-to-date.
		 */
		if (count < 48)
			break;
		p = data + 40;	/* Point to last two items. */
		p = store_long(p, ppp->stats.ppp_opackets + 1);
		p = store_long(p, ppp->stats.ppp_ooctects + count);
		++ppp->stats.ppp_olqrs;
		break;

	case PPP_CCP:
		/*
		 * Outbound compression control frames
		 */
		ppp_proto_ccp(ppp, data + PPP_HDRLEN, count - PPP_HDRLEN, 0);
		break;
	}
	data = skb->data;
	count = skb->len;

	/*
	 * Compress the whole frame if possible.
	 */
	if (((ppp->flags & SC_COMP_RUN) != 0)	&&
	    (ppp->sc_xc_state != (void *) 0)	&&
	    (proto != PPP_LCP)			&&
	    (proto != PPP_CCP)) {
		struct sk_buff *new_skb;
		int new_count;

		/* Allocate an skb for the compressed frame. */
		new_skb = alloc_skb(ppp->mtu + PPP_HDRLEN, GFP_ATOMIC);
		if (new_skb == NULL) {
			printk(KERN_ERR "ppp_send_frame: no memory\n");
			KFREE_SKB(skb);
			ppp->xmit_busy = 0;
			return;
		}
		LIBERATE_SKB(new_skb);

		/* Compress the frame. */
		new_count = (*ppp->sc_xcomp->compress)
			(ppp->sc_xc_state, data, new_skb->data,
			 count, ppp->mtu + PPP_HDRLEN);

		/* Did it compress? */
		if (new_count > 0 && (ppp->flags & SC_CCP_UP)) {
			skb_put(new_skb, new_count);
			KFREE_SKB(skb);
			skb = new_skb;
		} else {
			/*
			 * The frame could not be compressed, or it could not
			 * be sent in compressed form because CCP is down.
			 */
			KFREE_SKB(new_skb);
		}
	}

	/*
	 * Send the frame
	 */
	if ( ppp->flags & SC_SYNC ) 
		ret = ppp_sync_send(ppp, skb);
	else
		ret = ppp_async_send(ppp, skb);
	if (ret > 0) {
		/* we can release the lock */
		ppp->xmit_busy = 0;
	} else if (ret < 0) {
		/* can't happen, since the caller got the xmit_busy lock */
		printk(KERN_ERR "ppp: ppp_async_send didn't accept pkt\n");
	}
}

/*
 * Apply VJ TCP header compression to a packet.
 */
static struct sk_buff *
ppp_vj_compress(struct ppp *ppp, struct sk_buff *skb)
{
	__u8 *orig_data, *data;
	struct sk_buff *new_skb;
	int len, proto;

	new_skb = alloc_skb(skb->len, GFP_ATOMIC);
	if (new_skb == NULL) {
		printk(KERN_ERR "ppp: no memory for vj compression\n");
		return skb;
	}
	LIBERATE_SKB(new_skb);

	orig_data = data = skb->data + PPP_HDRLEN;
	len = slhc_compress(ppp->slcomp, data, skb->len - PPP_HDRLEN,
			    new_skb->data + PPP_HDRLEN, &data,
			    (ppp->flags & SC_NO_TCP_CCID) == 0);

	if (data == orig_data) {
		/* Couldn't compress the data */
		KFREE_SKB(new_skb);
		return skb;
	}

	/* The data has been changed */
	if (data[0] & SL_TYPE_COMPRESSED_TCP) {
		proto = PPP_VJC_COMP;
		data[0] ^= SL_TYPE_COMPRESSED_TCP;
	} else {
		if (data[0] >= SL_TYPE_UNCOMPRESSED_TCP)
			proto = PPP_VJC_UNCOMP;
		else
			proto = PPP_IP;
		data[0] = orig_data[0];
	}

	data = skb_put(new_skb, len + PPP_HDRLEN);
	data[0] = PPP_ALLSTATIONS;
	data[1] = PPP_UI;
	data[2] = 0;
	data[3] = proto;

	KFREE_SKB(skb);
	return new_skb;
}

static inline void
ppp_send_frames(struct ppp *ppp)
{
	struct sk_buff *skb;

	while (!test_and_set_bit(0, &ppp->xmit_busy)) {
		skb = skb_dequeue(&ppp->xmt_q);
		if (skb == NULL) {
			ppp->xmit_busy = 0;
			break;
		}
		ppp_send_frame(ppp, skb);
	}
	if (!ppp->xmit_busy && ppp->dev.tbusy) {
		ppp->dev.tbusy = 0;
		mark_bh(NET_BH);
	}
}

/*
 * Called from the hardware (tty) layer when it can accept
 * another packet.
 */
static void
ppp_output_wakeup(struct ppp *ppp)
{
	CHECK_PPP_VOID();

	if (!ppp->xmit_busy) {
		printk(KERN_ERR "ppp_output_wakeup called but xmit_busy==0\n");
		return;
	}
	ppp->xmit_busy = 0;
	ppp_send_frames(ppp);
}

/*
 * Send a control frame (from pppd).
 */
static void
ppp_send_ctrl(struct ppp *ppp, struct sk_buff *skb)