isdn_ppp.c

linux-2.6.15.6

		break;
	default:
		printk(KERN_ERR "isdn_ppp_autodial_filter: unsupported protocol 0x%x.\n",
		       skb->protocol);
		return 1;
	}

	/* the filter instructions are constructed assuming
	 * a four-byte PPP header on each packet. we have to
	 * temporarily remove part of the fake header stuck on
	 * earlier.
	 */
	*skb_pull(skb, IPPP_MAX_HEADER - 4) = 1; /* indicate outbound */

	{
		u_int16_t *p = (u_int16_t *) skb->data;

		p++;
		*p   = htons(proto);
	}
	
	drop |= is->pass_filter
	        && sk_run_filter(skb, is->pass_filter, is->pass_len) == 0;
	drop |= is->active_filter
	        && sk_run_filter(skb, is->active_filter, is->active_len) == 0;
	
	skb_push(skb, IPPP_MAX_HEADER - 4);
	return drop;
}
#endif
#ifdef CONFIG_ISDN_MPP

/* this is _not_ rfc1990 header, but something we convert both short and long
 * headers to for convinience's sake:
 * 	byte 0 is flags as in rfc1990
 *	bytes 1...4 is 24-bit seqence number converted to host byte order 
 */
#define MP_HEADER_LEN	5

#define MP_LONGSEQ_MASK		0x00ffffff
#define MP_SHORTSEQ_MASK	0x00000fff
#define MP_LONGSEQ_MAX		MP_LONGSEQ_MASK
#define MP_SHORTSEQ_MAX		MP_SHORTSEQ_MASK
#define MP_LONGSEQ_MAXBIT	((MP_LONGSEQ_MASK+1)>>1)
#define MP_SHORTSEQ_MAXBIT	((MP_SHORTSEQ_MASK+1)>>1)

/* sequence-wrap safe comparisions (for long sequence)*/ 
#define MP_LT(a,b)	((a-b)&MP_LONGSEQ_MAXBIT)
#define MP_LE(a,b) 	!((b-a)&MP_LONGSEQ_MAXBIT)
#define MP_GT(a,b) 	((b-a)&MP_LONGSEQ_MAXBIT)
#define MP_GE(a,b)	!((a-b)&MP_LONGSEQ_MAXBIT)

#define MP_SEQ(f)	((*(u32*)(f->data+1)))
#define MP_FLAGS(f)	(f->data[0])

static int isdn_ppp_mp_bundle_array_init(void)
{
	int i;
	int sz = ISDN_MAX_CHANNELS*sizeof(ippp_bundle);
	if( (isdn_ppp_bundle_arr = (ippp_bundle*)kmalloc(sz, 
							GFP_KERNEL)) == NULL )
		return -ENOMEM;
	memset(isdn_ppp_bundle_arr, 0, sz);
	for( i = 0; i < ISDN_MAX_CHANNELS; i++ )
		spin_lock_init(&isdn_ppp_bundle_arr[i].lock);
	return 0;
}

static ippp_bundle * isdn_ppp_mp_bundle_alloc(void)
{
	int i;
	for( i = 0; i < ISDN_MAX_CHANNELS; i++ )
		if (isdn_ppp_bundle_arr[i].ref_ct <= 0)
			return (isdn_ppp_bundle_arr + i);
	return NULL;
}

static int isdn_ppp_mp_init( isdn_net_local * lp, ippp_bundle * add_to )
{
	struct ippp_struct * is;

	if (lp->ppp_slot < 0) {
		printk(KERN_ERR "%s: lp->ppp_slot(%d) out of range\n",
			__FUNCTION__, lp->ppp_slot);
		return(-EINVAL);
	}

	is = ippp_table[lp->ppp_slot];
	if (add_to) {
		if( lp->netdev->pb )
			lp->netdev->pb->ref_ct--;
		lp->netdev->pb = add_to;
	} else {		/* first link in a bundle */
		is->mp_seqno = 0;
		if ((lp->netdev->pb = isdn_ppp_mp_bundle_alloc()) == NULL)
			return -ENOMEM;
		lp->next = lp->last = lp;	/* nobody else in a queue */
		lp->netdev->pb->frags = NULL;
		lp->netdev->pb->frames = 0;
		lp->netdev->pb->seq = UINT_MAX;
	}
	lp->netdev->pb->ref_ct++;
	
	is->last_link_seqno = 0;
	return 0;
}

static u32 isdn_ppp_mp_get_seq( int short_seq, 
					struct sk_buff * skb, u32 last_seq );
static struct sk_buff * isdn_ppp_mp_discard( ippp_bundle * mp,
			struct sk_buff * from, struct sk_buff * to );
static void isdn_ppp_mp_reassembly( isdn_net_dev * net_dev, isdn_net_local * lp,
				struct sk_buff * from, struct sk_buff * to );
static void isdn_ppp_mp_free_skb( ippp_bundle * mp, struct sk_buff * skb );
static void isdn_ppp_mp_print_recv_pkt( int slot, struct sk_buff * skb );

static void isdn_ppp_mp_receive(isdn_net_dev * net_dev, isdn_net_local * lp, 
							struct sk_buff *skb)
{
	struct ippp_struct *is;
	isdn_net_local * lpq;
	ippp_bundle * mp;
	isdn_mppp_stats * stats;
	struct sk_buff * newfrag, * frag, * start, *nextf;
	u32 newseq, minseq, thisseq;
	unsigned long flags;
	int slot;

	spin_lock_irqsave(&net_dev->pb->lock, flags);
    	mp = net_dev->pb;
        stats = &mp->stats;
	slot = lp->ppp_slot;
	if (slot < 0 || slot > ISDN_MAX_CHANNELS) {
		printk(KERN_ERR "%s: lp->ppp_slot(%d)\n",
			__FUNCTION__, lp->ppp_slot);
		stats->frame_drops++;
		dev_kfree_skb(skb);
		spin_unlock_irqrestore(&mp->lock, flags);
		return;
	}
	is = ippp_table[slot];
    	if( ++mp->frames > stats->max_queue_len )
		stats->max_queue_len = mp->frames;
	
	if (is->debug & 0x8)
		isdn_ppp_mp_print_recv_pkt(lp->ppp_slot, skb);

	newseq = isdn_ppp_mp_get_seq(is->mpppcfg & SC_IN_SHORT_SEQ, 
						skb, is->last_link_seqno);


	/* if this packet seq # is less than last already processed one,
	 * toss it right away, but check for sequence start case first 
	 */
	if( mp->seq > MP_LONGSEQ_MAX && (newseq & MP_LONGSEQ_MAXBIT) ) {
		mp->seq = newseq;	/* the first packet: required for
					 * rfc1990 non-compliant clients --
					 * prevents constant packet toss */
	} else if( MP_LT(newseq, mp->seq) ) {
		stats->frame_drops++;
		isdn_ppp_mp_free_skb(mp, skb);
		spin_unlock_irqrestore(&mp->lock, flags);
		return;
	}
	
	/* find the minimum received sequence number over all links */
	is->last_link_seqno = minseq = newseq;
	for (lpq = net_dev->queue;;) {
		slot = lpq->ppp_slot;
		if (slot < 0 || slot > ISDN_MAX_CHANNELS) {
			printk(KERN_ERR "%s: lpq->ppp_slot(%d)\n",
				__FUNCTION__, lpq->ppp_slot);
		} else {
			u32 lls = ippp_table[slot]->last_link_seqno;
			if (MP_LT(lls, minseq))
				minseq = lls;
		}
		if ((lpq = lpq->next) == net_dev->queue)
			break;
	}
	if (MP_LT(minseq, mp->seq))
		minseq = mp->seq;	/* can't go beyond already processed
					 * packets */
	newfrag = skb;

  	/* if this new fragment is before the first one, then enqueue it now. */
  	if ((frag = mp->frags) == NULL || MP_LT(newseq, MP_SEQ(frag))) {
		newfrag->next = frag;
    		mp->frags = frag = newfrag;
    		newfrag = NULL;
  	}

  	start = MP_FLAGS(frag) & MP_BEGIN_FRAG &&
				MP_SEQ(frag) == mp->seq ? frag : NULL;

	/* 
	 * main fragment traversing loop
	 *
	 * try to accomplish several tasks:
	 * - insert new fragment into the proper sequence slot (once that's done
	 *   newfrag will be set to NULL)
	 * - reassemble any complete fragment sequence (non-null 'start'
	 *   indicates there is a continguous sequence present)
	 * - discard any incomplete sequences that are below minseq -- due
	 *   to the fact that sender always increment sequence number, if there
	 *   is an incomplete sequence below minseq, no new fragments would
	 *   come to complete such sequence and it should be discarded
	 *
	 * loop completes when we accomplished the following tasks:
	 * - new fragment is inserted in the proper sequence ('newfrag' is 
	 *   set to NULL)
	 * - we hit a gap in the sequence, so no reassembly/processing is 
	 *   possible ('start' would be set to NULL)
	 *
	 * algorightm for this code is derived from code in the book
	 * 'PPP Design And Debugging' by James Carlson (Addison-Wesley)
	 */
  	while (start != NULL || newfrag != NULL) {

    		thisseq = MP_SEQ(frag);
    		nextf = frag->next;

    		/* drop any duplicate fragments */
    		if (newfrag != NULL && thisseq == newseq) {
      			isdn_ppp_mp_free_skb(mp, newfrag);
      			newfrag = NULL;
    		}

    		/* insert new fragment before next element if possible. */
    		if (newfrag != NULL && (nextf == NULL || 
						MP_LT(newseq, MP_SEQ(nextf)))) {
      			newfrag->next = nextf;
      			frag->next = nextf = newfrag;
      			newfrag = NULL;
    		}

    		if (start != NULL) {
	    		/* check for misplaced start */
      			if (start != frag && (MP_FLAGS(frag) & MP_BEGIN_FRAG)) {
				printk(KERN_WARNING"isdn_mppp(seq %d): new "
				      "BEGIN flag with no prior END", thisseq);
				stats->seqerrs++;
				stats->frame_drops++;
				start = isdn_ppp_mp_discard(mp, start,frag);
				nextf = frag->next;
      			}
    		} else if (MP_LE(thisseq, minseq)) {		
      			if (MP_FLAGS(frag) & MP_BEGIN_FRAG)
				start = frag;
      			else {
				if (MP_FLAGS(frag) & MP_END_FRAG)
	  				stats->frame_drops++;
				if( mp->frags == frag )
					mp->frags = nextf;	
				isdn_ppp_mp_free_skb(mp, frag);
				frag = nextf;
				continue;
      			}
		}
		
		/* if start is non-null and we have end fragment, then
		 * we have full reassembly sequence -- reassemble 
		 * and process packet now
		 */
    		if (start != NULL && (MP_FLAGS(frag) & MP_END_FRAG)) {
      			minseq = mp->seq = (thisseq+1) & MP_LONGSEQ_MASK;
      			/* Reassemble the packet then dispatch it */
			isdn_ppp_mp_reassembly(net_dev, lp, start, nextf);
      
      			start = NULL;
      			frag = NULL;

      			mp->frags = nextf;
    		}

		/* check if need to update start pointer: if we just
		 * reassembled the packet and sequence is contiguous
		 * then next fragment should be the start of new reassembly
		 * if sequence is contiguous, but we haven't reassembled yet,
		 * keep going.
		 * if sequence is not contiguous, either clear everyting
		 * below low watermark and set start to the next frag or
		 * clear start ptr.
		 */ 
    		if (nextf != NULL && 
		    ((thisseq+1) & MP_LONGSEQ_MASK) == MP_SEQ(nextf)) {
      			/* if we just reassembled and the next one is here, 
			 * then start another reassembly. */

      			if (frag == NULL) {
				if (MP_FLAGS(nextf) & MP_BEGIN_FRAG)
	  				start = nextf;
				else
				{
	  				printk(KERN_WARNING"isdn_mppp(seq %d):"
						" END flag with no following "
						"BEGIN", thisseq);
					stats->seqerrs++;
				}
			}

    		} else {
			if ( nextf != NULL && frag != NULL &&
						MP_LT(thisseq, minseq)) {
				/* we've got a break in the sequence
				 * and we not at the end yet
				 * and we did not just reassembled
				 *(if we did, there wouldn't be anything before)
				 * and we below the low watermark 
			 	 * discard all the frames below low watermark 
				 * and start over */
				stats->frame_drops++;
				mp->frags = isdn_ppp_mp_discard(mp,start,nextf);
			}
			/* break in the sequence, no reassembly */
      			start = NULL;
    		}
	  			
    		frag = nextf;
  	}	/* while -- main loop */
	
  	if (mp->frags == NULL)
    		mp->frags = frag;
		
	/* rather straighforward way to deal with (not very) possible 
	 * queue overflow */
	if (mp->frames > MP_MAX_QUEUE_LEN) {
		stats->overflows++;
		while (mp->frames > MP_MAX_QUEUE_LEN) {
			frag = mp->frags->next;
			isdn_ppp_mp_free_skb(mp, mp->frags);
			mp->frags = frag;
		}
	}
	spin_unlock_irqrestore(&mp->lock, flags);
}

static void isdn_ppp_mp_cleanup( isdn_net_local * lp )
{
	struct sk_buff * frag = lp->netdev->pb->frags;
	struct sk_buff * nextfrag;
    	while( frag ) {
		nextfrag = frag->next;
		isdn_ppp_mp_free_skb(lp->netdev->pb, frag);
		frag = nextfrag;
	}
	lp->netdev->pb->frags = NULL;
}

static u32 isdn_ppp_mp_get_seq( int short_seq, 
					struct sk_buff * skb, u32 last_seq )
{
	u32 seq;
	int flags = skb->data[0] & (MP_BEGIN_FRAG | MP_END_FRAG);
   
   	if( !short_seq )
	{
		seq = ntohl(*(u32*)skb->data) & MP_LONGSEQ_MASK;
		skb_push(skb,1);
	}
	else
	{
		/* convert 12-bit short seq number to 24-bit long one 
	 	*/
		seq = ntohs(*(u16*)skb->data) & MP_SHORTSEQ_MASK;
	
		/* check for seqence wrap */
		if( !(seq &  MP_SHORTSEQ_MAXBIT) && 
		     (last_seq &  MP_SHORTSEQ_MAXBIT) && 
		     (unsigned long)last_seq <= MP_LONGSEQ_MAX )
			seq |= (last_seq + MP_SHORTSEQ_MAX+1) & 
					(~MP_SHORTSEQ_MASK & MP_LONGSEQ_MASK);
		else
			seq |= last_seq & (~MP_SHORTSEQ_MASK & MP_LONGSEQ_MASK);
		
		skb_push(skb, 3);	/* put converted seqence back in skb */
	}
	*(u32*)(skb->data+1) = seq; 	/* put seqence back in _host_ byte
					 * order */
	skb->data[0] = flags;	        /* restore flags */
	return seq;
}

struct sk_buff * isdn_ppp_mp_discard( ippp_bundle * mp,
			struct sk_buff * from, struct sk_buff * to )
{
	if( from )
		while (from != to) {
	  		struct sk_buff * next = from->next;
			isdn_ppp_mp_free_skb(mp, from);
	  		from = next;
		}
	return from;
}

void isdn_ppp_mp_reassembly( isdn_net_dev * net_dev, isdn_net_local * lp,
				struct sk_buff * from, struct sk_buff * to )
{
	ippp_bundle * mp = net_dev->pb;
	int proto;
	struct sk_buff * skb;
	unsigned int tot_len;

	if (lp->ppp_slot < 0 || lp->ppp_slot >= ISDN_MAX_CHANNELS) {
		printk(KERN_ERR "%s: lp->ppp_slot(%d) out of range\n",
			__FUNCTION__, lp->ppp_slot);
		return;
	}
	if( MP_FLAGS(from) == (MP_BEGIN_FRAG | MP_END_FRAG) ) {
		if( ippp_table[lp->ppp_slot]->debug & 0x40 )
			printk(KERN_DEBUG "isdn_mppp: reassembly: frame %d, "
					"len %d\n", MP_SEQ(from), from->len );
		skb = from;
		skb_pull(skb, MP_HEADER_LEN);
		mp->frames--;	
	} else {
		struct sk_buff * frag;
		int n;

		for(tot_len=n=0, frag=from; frag != to; frag=frag->next, n++)
			tot_len += frag->len - MP_HEADER_LEN;

		if( ippp_table[lp->ppp_slot]->debug & 0x40 )
			printk(KERN_DEBUG"isdn_mppp: reassembling frames %d "
				"to %d, len %d\n", MP_SEQ(from), 
				(MP_SEQ(from)+n-1) & MP_LONGSEQ_MASK, tot_len );
		if( (skb = dev_alloc_skb(tot_len)) == NULL ) {
			printk(KERN_ERR "isdn_mppp: cannot allocate sk buff "
					"of size %d\n", tot_len);
			isdn_ppp_mp_discard(mp, from, to);
			return;
		}

		while( from != to ) {
			unsigned int len = from->len - MP_HEADER_LEN;

			memcpy(skb_put(skb,len), from->data+MP_HEADER_LEN, len);
			frag = from->next;
			isdn_ppp_mp_free_skb(mp, from);
			from = frag; 
		}
	}
   	proto = isdn_ppp_strip_proto(skb);
	isdn_ppp_push_higher(net_dev, lp, skb, proto);
}

static void isdn_ppp_mp_free_skb(ippp_bundle * mp, struct sk_buff * skb)
{
	dev_kfree_skb(skb);
	mp->frames--;
}

static void isdn_ppp_mp_print_recv_pkt( int slot, struct sk_buff * skb )
{
	printk(KERN_DEBUG "mp_recv: %d/%d -> %02x %02x %02x %02x %02x %02x\n", 
		slot, (int) skb->len, 
		(int) skb->data[0], (int) skb->data[1], (int) skb->data[2],
		(int) skb->data[3], (int) skb->data[4], (int) skb->data[5]);
}

static int
isdn_ppp_bundle(struct ippp_struct *is, int unit)
{
	char ifn[IFNAMSIZ + 1];
	isdn_net_dev *p;
	isdn_net_local *lp, *nlp;
	int rc;
	unsigned long flags;

	sprintf(ifn, "ippp%d", unit);
	p = isdn_net_findif(ifn);
	if (!p) {
		printk(KERN_ERR "ippp_bundle: cannot find %s\n", ifn);
		return -EINVAL;
	}

    	spin_lock_irqsave(&p->pb->lock, flags);

	nlp = is->lp;
	lp = p->queue;
	if( nlp->ppp_slot < 0 || nlp->ppp_slot >= ISDN_MAX_CHANNELS ||
		lp->ppp_slot < 0 || lp->ppp_slot >= ISDN_MAX_CHANNELS ) {
		printk(KERN_ERR "ippp_bundle: binding to invalid slot %d\n",
			nlp->ppp_slot < 0 || nlp->ppp_slot >= ISDN_MAX_CHANNELS ? 
			nlp->ppp_slot : lp->ppp_slot );
		rc = -EINVAL;
		goto out;
 	}

	isdn_net_add_to_bundle(p, nlp);