[net-next-2.6.git] / net / dccp / ackvec.c

/*
 *  net/dccp/ackvec.c
 *
 *  An implementation of the DCCP protocol
 *  Copyright (c) 2005 Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
 *
 *      This program is free software; you can redistribute it and/or modify it
 *      under the terms of the GNU General Public License as published by the
 *      Free Software Foundation; version 2 of the License;
 */

#include "ackvec.h"
#include "dccp.h"

#include <linux/dccp.h>
#include <linux/init.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/skbuff.h>
#include <linux/slab.h>

#include <net/sock.h>

static kmem_cache_t *dccp_ackvec_slab;
static kmem_cache_t *dccp_ackvec_record_slab;

static struct dccp_ackvec_record *dccp_ackvec_record_new(void)
{
	struct dccp_ackvec_record *avr =
			kmem_cache_alloc(dccp_ackvec_record_slab, GFP_ATOMIC);

	if (avr != NULL)
		INIT_LIST_HEAD(&avr->dccpavr_node);

	return avr;
}

static void dccp_ackvec_record_delete(struct dccp_ackvec_record *avr)
{
	if (unlikely(avr == NULL))
		return;
	/* Check if deleting a linked record */
	WARN_ON(!list_empty(&avr->dccpavr_node));
	kmem_cache_free(dccp_ackvec_record_slab, avr);
}

static void dccp_ackvec_insert_avr(struct dccp_ackvec *av,
				   struct dccp_ackvec_record *avr)
{
	/*
	 * AVRs are sorted by seqno. Since we are sending them in order, we
	 * just add the AVR at the head of the list.
	 * -sorbo.
	 */
	if (!list_empty(&av->dccpav_records)) {
		const struct dccp_ackvec_record *head =
					list_entry(av->dccpav_records.next,
						   struct dccp_ackvec_record,
						   dccpavr_node);
		BUG_ON(before48(avr->dccpavr_ack_seqno,
				head->dccpavr_ack_seqno));
	}

	list_add(&avr->dccpavr_node, &av->dccpav_records);
}

int dccp_insert_option_ackvec(struct sock *sk, struct sk_buff *skb)
{
	struct dccp_sock *dp = dccp_sk(sk);
	struct dccp_ackvec *av = dp->dccps_hc_rx_ackvec;
	int len = av->dccpav_vec_len + 2;
	struct timeval now;
	u32 elapsed_time;
	unsigned char *to, *from;
	struct dccp_ackvec_record *avr;

	if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN)
		return -1;

	dccp_timestamp(sk, &now);
	elapsed_time = timeval_delta(&now, &av->dccpav_time) / 10;

	if (elapsed_time != 0 &&
	    dccp_insert_option_elapsed_time(sk, skb, elapsed_time))
		return -1;

	avr = dccp_ackvec_record_new();
	if (avr == NULL)
		return -1;

	DCCP_SKB_CB(skb)->dccpd_opt_len += len;

	to    = skb_push(skb, len);
	*to++ = DCCPO_ACK_VECTOR_0;
	*to++ = len;

	len  = av->dccpav_vec_len;
	from = av->dccpav_buf + av->dccpav_buf_head;

	/* Check if buf_head wraps */
	if ((int)av->dccpav_buf_head + len > DCCP_MAX_ACKVEC_LEN) {
		const u32 tailsize = DCCP_MAX_ACKVEC_LEN - av->dccpav_buf_head;

		memcpy(to, from, tailsize);
		to   += tailsize;
		len  -= tailsize;
		from = av->dccpav_buf;
	}

	memcpy(to, from, len);
	/*
	 *	From RFC 4340, A.2:
	 *
	 *	For each acknowledgement it sends, the HC-Receiver will add an
	 *	acknowledgement record.  ack_seqno will equal the HC-Receiver
	 *	sequence number it used for the ack packet; ack_ptr will equal
	 *	buf_head; ack_ackno will equal buf_ackno; and ack_nonce will
	 *	equal buf_nonce.
	 */
	avr->dccpavr_ack_seqno = DCCP_SKB_CB(skb)->dccpd_seq;
	avr->dccpavr_ack_ptr   = av->dccpav_buf_head;
	avr->dccpavr_ack_ackno = av->dccpav_buf_ackno;
	avr->dccpavr_ack_nonce = av->dccpav_buf_nonce;
	avr->dccpavr_sent_len  = av->dccpav_vec_len;

	dccp_ackvec_insert_avr(av, avr);

	dccp_pr_debug("%s ACK Vector 0, len=%d, ack_seqno=%llu, "
		      "ack_ackno=%llu\n",
		      dccp_role(sk), avr->dccpavr_sent_len,
		      (unsigned long long)avr->dccpavr_ack_seqno,
		      (unsigned long long)avr->dccpavr_ack_ackno);
	return 0;
}

struct dccp_ackvec *dccp_ackvec_alloc(const gfp_t priority)
{
	struct dccp_ackvec *av = kmem_cache_alloc(dccp_ackvec_slab, priority);

	if (av != NULL) {
		av->dccpav_buf_head	= DCCP_MAX_ACKVEC_LEN - 1;
		av->dccpav_buf_ackno	= DCCP_MAX_SEQNO + 1;
		av->dccpav_buf_nonce = av->dccpav_buf_nonce = 0;
		av->dccpav_ack_ptr	= 0;
		av->dccpav_time.tv_sec	= 0;
		av->dccpav_time.tv_usec	= 0;
		av->dccpav_vec_len	= 0;
		INIT_LIST_HEAD(&av->dccpav_records);
	}

	return av;
}

void dccp_ackvec_free(struct dccp_ackvec *av)
{
	if (unlikely(av == NULL))
		return;

	if (!list_empty(&av->dccpav_records)) {
		struct dccp_ackvec_record *avr, *next;

		list_for_each_entry_safe(avr, next, &av->dccpav_records,
					 dccpavr_node) {
			list_del_init(&avr->dccpavr_node);
			dccp_ackvec_record_delete(avr);
		}
	}

	kmem_cache_free(dccp_ackvec_slab, av);
}

static inline u8 dccp_ackvec_state(const struct dccp_ackvec *av,
				   const u8 index)
{
	return av->dccpav_buf[index] & DCCP_ACKVEC_STATE_MASK;
}

static inline u8 dccp_ackvec_len(const struct dccp_ackvec *av,
				 const u8 index)
{
	return av->dccpav_buf[index] & DCCP_ACKVEC_LEN_MASK;
}

/*
 * If several packets are missing, the HC-Receiver may prefer to enter multiple
 * bytes with run length 0, rather than a single byte with a larger run length;
 * this simplifies table updates if one of the missing packets arrives.
 */
static inline int dccp_ackvec_set_buf_head_state(struct dccp_ackvec *av,
						 const unsigned int packets,
						 const unsigned char state)
{
	unsigned int gap;
	long new_head;

	if (av->dccpav_vec_len + packets > DCCP_MAX_ACKVEC_LEN)
		return -ENOBUFS;

	gap	 = packets - 1;
	new_head = av->dccpav_buf_head - packets;

	if (new_head < 0) {
		if (gap > 0) {
			memset(av->dccpav_buf, DCCP_ACKVEC_STATE_NOT_RECEIVED,
			       gap + new_head + 1);
			gap = -new_head;
		}
		new_head += DCCP_MAX_ACKVEC_LEN;
	} 

	av->dccpav_buf_head = new_head;

	if (gap > 0)
		memset(av->dccpav_buf + av->dccpav_buf_head + 1,
		       DCCP_ACKVEC_STATE_NOT_RECEIVED, gap);

	av->dccpav_buf[av->dccpav_buf_head] = state;
	av->dccpav_vec_len += packets;
	return 0;
}

/*
 * Implements the RFC 4340, Appendix A
 */
int dccp_ackvec_add(struct dccp_ackvec *av, const struct sock *sk,
		    const u64 ackno, const u8 state)
{
	/*
	 * Check at the right places if the buffer is full, if it is, tell the
	 * caller to start dropping packets till the HC-Sender acks our ACK
	 * vectors, when we will free up space in dccpav_buf.
	 *
	 * We may well decide to do buffer compression, etc, but for now lets
	 * just drop.
	 *
	 * From Appendix A.1.1 (`New Packets'):
	 *
	 *	Of course, the circular buffer may overflow, either when the
	 *	HC-Sender is sending data at a very high rate, when the
	 *	HC-Receiver's acknowledgements are not reaching the HC-Sender,
	 *	or when the HC-Sender is forgetting to acknowledge those acks
	 *	(so the HC-Receiver is unable to clean up old state). In this
	 *	case, the HC-Receiver should either compress the buffer (by
	 *	increasing run lengths when possible), transfer its state to
	 *	a larger buffer, or, as a last resort, drop all received
	 *	packets, without processing them whatsoever, until its buffer
	 *	shrinks again.
	 */

	/* See if this is the first ackno being inserted */
	if (av->dccpav_vec_len == 0) {
		av->dccpav_buf[av->dccpav_buf_head] = state;
		av->dccpav_vec_len = 1;
	} else if (after48(ackno, av->dccpav_buf_ackno)) {
		const u64 delta = dccp_delta_seqno(av->dccpav_buf_ackno,
						   ackno);

		/*
		 * Look if the state of this packet is the same as the
		 * previous ackno and if so if we can bump the head len.
		 */
		if (delta == 1 &&
		    dccp_ackvec_state(av, av->dccpav_buf_head) == state &&
		    (dccp_ackvec_len(av, av->dccpav_buf_head) <
		     DCCP_ACKVEC_LEN_MASK))
			av->dccpav_buf[av->dccpav_buf_head]++;
		else if (dccp_ackvec_set_buf_head_state(av, delta, state))
			return -ENOBUFS;
	} else {
		/*
		 * A.1.2.  Old Packets
		 *
		 *	When a packet with Sequence Number S <= buf_ackno
		 *	arrives, the HC-Receiver will scan the table for
		 *	the byte corresponding to S. (Indexing structures
		 *	could reduce the complexity of this scan.)
		 */
		u64 delta = dccp_delta_seqno(ackno, av->dccpav_buf_ackno);
		u8 index = av->dccpav_buf_head;

		while (1) {
			const u8 len = dccp_ackvec_len(av, index);
			const u8 state = dccp_ackvec_state(av, index);
			/*
			 * valid packets not yet in dccpav_buf have a reserved
			 * entry, with a len equal to 0.
			 */
			if (state == DCCP_ACKVEC_STATE_NOT_RECEIVED &&
			    len == 0 && delta == 0) { /* Found our
							 reserved seat! */
				dccp_pr_debug("Found %llu reserved seat!\n",
					      (unsigned long long)ackno);
				av->dccpav_buf[index] = state;
				goto out;
			}
			/* len == 0 means one packet */
			if (delta < len + 1)
				goto out_duplicate;

			delta -= len + 1;
			if (++index == DCCP_MAX_ACKVEC_LEN)
				index = 0;
		}
	}

	av->dccpav_buf_ackno = ackno;
	dccp_timestamp(sk, &av->dccpav_time);
out:
	return 0;

out_duplicate:
	/* Duplicate packet */
	dccp_pr_debug("Received a dup or already considered lost "
		      "packet: %llu\n", (unsigned long long)ackno);
	return -EILSEQ;
}

#ifdef CONFIG_IP_DCCP_DEBUG
void dccp_ackvector_print(const u64 ackno, const unsigned char *vector, int len)
{
	if (!dccp_debug)
		return;

	printk("ACK vector len=%d, ackno=%llu |", len,
	       (unsigned long long)ackno);

	while (len--) {
		const u8 state = (*vector & DCCP_ACKVEC_STATE_MASK) >> 6;
		const u8 rl = *vector & DCCP_ACKVEC_LEN_MASK;

		printk("%d,%d|", state, rl);
		++vector;
	}

	printk("\n");
}

void dccp_ackvec_print(const struct dccp_ackvec *av)
{
	dccp_ackvector_print(av->dccpav_buf_ackno,
			     av->dccpav_buf + av->dccpav_buf_head,
			     av->dccpav_vec_len);
}
#endif

static void dccp_ackvec_throw_record(struct dccp_ackvec *av,
				     struct dccp_ackvec_record *avr)
{
	struct dccp_ackvec_record *next;

	/* sort out vector length */
	if (av->dccpav_buf_head <= avr->dccpavr_ack_ptr)
		av->dccpav_vec_len = avr->dccpavr_ack_ptr - av->dccpav_buf_head;
	else
		av->dccpav_vec_len = DCCP_MAX_ACKVEC_LEN - 1
				     - av->dccpav_buf_head
				     + avr->dccpavr_ack_ptr;

	/* free records */
	list_for_each_entry_safe_from(avr, next, &av->dccpav_records,
				      dccpavr_node) {
		list_del_init(&avr->dccpavr_node);
		dccp_ackvec_record_delete(avr);
	}
}

void dccp_ackvec_check_rcv_ackno(struct dccp_ackvec *av, struct sock *sk,
				 const u64 ackno)
{
	struct dccp_ackvec_record *avr;

	/*
	 * If we traverse backwards, it should be faster when we have large
	 * windows. We will be receiving ACKs for stuff we sent a while back
	 * -sorbo.
	 */
	list_for_each_entry_reverse(avr, &av->dccpav_records, dccpavr_node) {
		if (ackno == avr->dccpavr_ack_seqno) {
			dccp_pr_debug("%s ACK packet 0, len=%d, ack_seqno=%llu, "
				      "ack_ackno=%llu, ACKED!\n",
				      dccp_role(sk), 1,
				      (unsigned long long)avr->dccpavr_ack_seqno,
				      (unsigned long long)avr->dccpavr_ack_ackno);
			dccp_ackvec_throw_record(av, avr);
			break;
		}
	}
}

static void dccp_ackvec_check_rcv_ackvector(struct dccp_ackvec *av,
					    struct sock *sk, u64 ackno,
					    const unsigned char len,
					    const unsigned char *vector)
{
	unsigned char i;
	struct dccp_ackvec_record *avr;

	/* Check if we actually sent an ACK vector */
	if (list_empty(&av->dccpav_records))
		return;

	i = len;
	/*
	 * XXX
	 * I think it might be more efficient to work backwards. See comment on
	 * rcv_ackno. -sorbo.
	 */
	avr = list_entry(av->dccpav_records.next, struct dccp_ackvec_record,
			 dccpavr_node);
	while (i--) {
		const u8 rl = *vector & DCCP_ACKVEC_LEN_MASK;
		u64 ackno_end_rl;

		dccp_set_seqno(&ackno_end_rl, ackno - rl);

		/*
		 * If our AVR sequence number is greater than the ack, go
		 * forward in the AVR list until it is not so.
		 */
		list_for_each_entry_from(avr, &av->dccpav_records,
					 dccpavr_node) {
			if (!after48(avr->dccpavr_ack_seqno, ackno))
				goto found;
		}
		/* End of the dccpav_records list, not found, exit */
		break;
found:
		if (between48(avr->dccpavr_ack_seqno, ackno_end_rl, ackno)) {
			const u8 state = *vector & DCCP_ACKVEC_STATE_MASK;
			if (state != DCCP_ACKVEC_STATE_NOT_RECEIVED) {
				dccp_pr_debug("%s ACK vector 0, len=%d, "
					      "ack_seqno=%llu, ack_ackno=%llu, "
					      "ACKED!\n",
					      dccp_role(sk), len,
					      (unsigned long long)
					      avr->dccpavr_ack_seqno,
					      (unsigned long long)
					      avr->dccpavr_ack_ackno);
				dccp_ackvec_throw_record(av, avr);
				break;
			}
			/*
			 * If it wasn't received, continue scanning... we might
			 * find another one.
			 */
		}

		dccp_set_seqno(&ackno, ackno_end_rl - 1);
		++vector;
	}
}

int dccp_ackvec_parse(struct sock *sk, const struct sk_buff *skb,
		      const u8 opt, const u8 *value, const u8 len)
{
	if (len > DCCP_MAX_ACKVEC_LEN)
		return -1;

	/* dccp_ackvector_print(DCCP_SKB_CB(skb)->dccpd_ack_seq, value, len); */
	dccp_ackvec_check_rcv_ackvector(dccp_sk(sk)->dccps_hc_rx_ackvec, sk,
					DCCP_SKB_CB(skb)->dccpd_ack_seq,
				        len, value);
	return 0;
}

static char dccp_ackvec_slab_msg[] __initdata =
	KERN_CRIT "DCCP: Unable to create ack vectors slab caches\n";

int __init dccp_ackvec_init(void)
{
	dccp_ackvec_slab = kmem_cache_create("dccp_ackvec",
					     sizeof(struct dccp_ackvec), 0,
					     SLAB_HWCACHE_ALIGN, NULL, NULL);
	if (dccp_ackvec_slab == NULL)
		goto out_err;

	dccp_ackvec_record_slab =
			kmem_cache_create("dccp_ackvec_record",
					  sizeof(struct dccp_ackvec_record),
					  0, SLAB_HWCACHE_ALIGN, NULL, NULL);
	if (dccp_ackvec_record_slab == NULL)
		goto out_destroy_slab;

	return 0;

out_destroy_slab:
	kmem_cache_destroy(dccp_ackvec_slab);
	dccp_ackvec_slab = NULL;
out_err:
	printk(dccp_ackvec_slab_msg);
	return -ENOBUFS;
}

void dccp_ackvec_exit(void)
{
	if (dccp_ackvec_slab != NULL) {
		kmem_cache_destroy(dccp_ackvec_slab);
		dccp_ackvec_slab = NULL;
	}
	if (dccp_ackvec_record_slab != NULL) {
		kmem_cache_destroy(dccp_ackvec_record_slab);
		dccp_ackvec_record_slab = NULL;
	}
}
Commit	Line	Data
ae31c339 ACM	1	/*
	2	* net/dccp/ackvec.c
	3	*
	4	* An implementation of the DCCP protocol
	5	* Copyright (c) 2005 Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
	6	*
	7	* This program is free software; you can redistribute it and/or modify it
	8	* under the terms of the GNU General Public License as published by the
	9	* Free Software Foundation; version 2 of the License;
	10	*/
	11
	12	#include "ackvec.h"
	13	#include "dccp.h"
	14
	15	#include <linux/dccp.h>
9b07ef5d ACM	16	#include <linux/init.h>
	17	#include <linux/errno.h>
	18	#include <linux/kernel.h>
ae31c339	19	#include <linux/skbuff.h>
9b07ef5d	20	#include <linux/slab.h>
ae31c339 ACM	21
	22	#include <net/sock.h>
	23
9b07ef5d	24	static kmem_cache_t *dccp_ackvec_slab;
02bcf28c AB	25	static kmem_cache_t *dccp_ackvec_record_slab;
	26
	27	static struct dccp_ackvec_record *dccp_ackvec_record_new(void)
	28	{
	29	struct dccp_ackvec_record *avr =
	30	kmem_cache_alloc(dccp_ackvec_record_slab, GFP_ATOMIC);
	31
	32	if (avr != NULL)
	33	INIT_LIST_HEAD(&avr->dccpavr_node);
	34
	35	return avr;
	36	}
	37
	38	static void dccp_ackvec_record_delete(struct dccp_ackvec_record *avr)
	39	{
	40	if (unlikely(avr == NULL))
	41	return;
	42	/* Check if deleting a linked record */
	43	WARN_ON(!list_empty(&avr->dccpavr_node));
	44	kmem_cache_free(dccp_ackvec_record_slab, avr);
	45	}
	46
	47	static void dccp_ackvec_insert_avr(struct dccp_ackvec *av,
	48	struct dccp_ackvec_record *avr)
	49	{
	50	/*
	51	* AVRs are sorted by seqno. Since we are sending them in order, we
	52	* just add the AVR at the head of the list.
	53	* -sorbo.
	54	*/
	55	if (!list_empty(&av->dccpav_records)) {
	56	const struct dccp_ackvec_record *head =
	57	list_entry(av->dccpav_records.next,
	58	struct dccp_ackvec_record,
	59	dccpavr_node);
	60	BUG_ON(before48(avr->dccpavr_ack_seqno,
	61	head->dccpavr_ack_seqno));
	62	}
	63
	64	list_add(&avr->dccpavr_node, &av->dccpav_records);
	65	}
9b07ef5d	66
ae31c339 ACM	67	int dccp_insert_option_ackvec(struct sock sk, struct sk_buff skb)
	68	{
	69	struct dccp_sock *dp = dccp_sk(sk);
	70	struct dccp_ackvec *av = dp->dccps_hc_rx_ackvec;
	71	int len = av->dccpav_vec_len + 2;
	72	struct timeval now;
	73	u32 elapsed_time;
	74	unsigned char to, from;
02bcf28c AB	75	struct dccp_ackvec_record *avr;
	76
	77	if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN)
	78	return -1;
	79
ae31c339 ACM	80	dccp_timestamp(sk, &now);
	81	elapsed_time = timeval_delta(&now, &av->dccpav_time) / 10;
	82
2d0817d1 ACM	83	if (elapsed_time != 0 &&
	84	dccp_insert_option_elapsed_time(sk, skb, elapsed_time))
	85	return -1;
	86
	87	avr = dccp_ackvec_record_new();
	88	if (avr == NULL)
	89	return -1;
ae31c339	90
ae31c339 ACM	91	DCCP_SKB_CB(skb)->dccpd_opt_len += len;
	92
	93	to = skb_push(skb, len);
	94	*to++ = DCCPO_ACK_VECTOR_0;
	95	*to++ = len;
	96
	97	len = av->dccpav_vec_len;
	98	from = av->dccpav_buf + av->dccpav_buf_head;
	99
	100	/* Check if buf_head wraps */
02bcf28c AB	101	if ((int)av->dccpav_buf_head + len > DCCP_MAX_ACKVEC_LEN) {
02bcf28c AB	102	const u32 tailsize = DCCP_MAX_ACKVEC_LEN - av->dccpav_buf_head;
ae31c339 ACM	103
	104	memcpy(to, from, tailsize);
	105	to += tailsize;
	106	len -= tailsize;
	107	from = av->dccpav_buf;
	108	}
	109
	110	memcpy(to, from, len);
	111	/*
0e64e94e	112	* From RFC 4340, A.2:
ae31c339 ACM	113	*
	114	* For each acknowledgement it sends, the HC-Receiver will add an
	115	* acknowledgement record. ack_seqno will equal the HC-Receiver
	116	* sequence number it used for the ack packet; ack_ptr will equal
	117	* buf_head; ack_ackno will equal buf_ackno; and ack_nonce will
	118	* equal buf_nonce.
ae31c339	119	*/
02bcf28c AB	120	avr->dccpavr_ack_seqno = DCCP_SKB_CB(skb)->dccpd_seq;
	121	avr->dccpavr_ack_ptr = av->dccpav_buf_head;
	122	avr->dccpavr_ack_ackno = av->dccpav_buf_ackno;
	123	avr->dccpavr_ack_nonce = av->dccpav_buf_nonce;
	124	avr->dccpavr_sent_len = av->dccpav_vec_len;
	125
	126	dccp_ackvec_insert_avr(av, avr);
ae31c339	127
09dbc389	128	dccp_pr_debug("%s ACK Vector 0, len=%d, ack_seqno=%llu, "
ae31c339	129	"ack_ackno=%llu\n",
09dbc389	130	dccp_role(sk), avr->dccpavr_sent_len,
02bcf28c AB	131	(unsigned long long)avr->dccpavr_ack_seqno,
	132	(unsigned long long)avr->dccpavr_ack_ackno);
	133	return 0;
ae31c339 ACM	134	}
ae31c339 ACM	135
7400d781	136	struct dccp_ackvec *dccp_ackvec_alloc(const gfp_t priority)
ae31c339	137	{
9b07ef5d	138	struct dccp_ackvec *av = kmem_cache_alloc(dccp_ackvec_slab, priority);
e4dfd449	139
ae31c339	140	if (av != NULL) {
4a0a50fb	141	av->dccpav_buf_head = DCCP_MAX_ACKVEC_LEN - 1;
02bcf28c	142	av->dccpav_buf_ackno = DCCP_MAX_SEQNO + 1;
ae31c339 ACM	143	av->dccpav_buf_nonce = av->dccpav_buf_nonce = 0;
	144	av->dccpav_ack_ptr = 0;
	145	av->dccpav_time.tv_sec = 0;
	146	av->dccpav_time.tv_usec = 0;
4a0a50fb	147	av->dccpav_vec_len = 0;
02bcf28c	148	INIT_LIST_HEAD(&av->dccpav_records);
ae31c339 ACM	149	}
	150
	151	return av;
	152	}
	153
	154	void dccp_ackvec_free(struct dccp_ackvec *av)
	155	{
02bcf28c AB	156	if (unlikely(av == NULL))
02bcf28c AB	157	return;
d5e9b2c7 ACM	158
	159	if (!list_empty(&av->dccpav_records)) {
	160	struct dccp_ackvec_record avr, next;
	161
	162	list_for_each_entry_safe(avr, next, &av->dccpav_records,
	163	dccpavr_node) {
	164	list_del_init(&avr->dccpavr_node);
	165	dccp_ackvec_record_delete(avr);
	166	}
	167	}
	168
9b07ef5d	169	kmem_cache_free(dccp_ackvec_slab, av);
ae31c339 ACM	170	}
	171
	172	static inline u8 dccp_ackvec_state(const struct dccp_ackvec *av,
e4dfd449	173	const u8 index)
ae31c339 ACM	174	{
	175	return av->dccpav_buf[index] & DCCP_ACKVEC_STATE_MASK;
	176	}
	177
	178	static inline u8 dccp_ackvec_len(const struct dccp_ackvec *av,
e4dfd449	179	const u8 index)
ae31c339 ACM	180	{
	181	return av->dccpav_buf[index] & DCCP_ACKVEC_LEN_MASK;
	182	}
	183
	184	/*
	185	* If several packets are missing, the HC-Receiver may prefer to enter multiple
	186	* bytes with run length 0, rather than a single byte with a larger run length;
	187	* this simplifies table updates if one of the missing packets arrives.
	188	*/
	189	static inline int dccp_ackvec_set_buf_head_state(struct dccp_ackvec *av,
	190	const unsigned int packets,
e4dfd449	191	const unsigned char state)
ae31c339 ACM	192	{
ae31c339 ACM	193	unsigned int gap;
a8fc3d8d	194	long new_head;
ae31c339	195
7400d781	196	if (av->dccpav_vec_len + packets > DCCP_MAX_ACKVEC_LEN)
ae31c339 ACM	197	return -ENOBUFS;
	198
	199	gap = packets - 1;
	200	new_head = av->dccpav_buf_head - packets;
	201
	202	if (new_head < 0) {
	203	if (gap > 0) {
	204	memset(av->dccpav_buf, DCCP_ACKVEC_STATE_NOT_RECEIVED,
	205	gap + new_head + 1);
	206	gap = -new_head;
	207	}
7400d781	208	new_head += DCCP_MAX_ACKVEC_LEN;
ae31c339 ACM	209	}
	210
	211	av->dccpav_buf_head = new_head;
	212
	213	if (gap > 0)
	214	memset(av->dccpav_buf + av->dccpav_buf_head + 1,
	215	DCCP_ACKVEC_STATE_NOT_RECEIVED, gap);
	216
	217	av->dccpav_buf[av->dccpav_buf_head] = state;
	218	av->dccpav_vec_len += packets;
	219	return 0;
	220	}
	221
	222	/*
0e64e94e	223	* Implements the RFC 4340, Appendix A
ae31c339 ACM	224	*/
	225	int dccp_ackvec_add(struct dccp_ackvec av, const struct sock sk,
	226	const u64 ackno, const u8 state)
	227	{
	228	/*
	229	* Check at the right places if the buffer is full, if it is, tell the
	230	* caller to start dropping packets till the HC-Sender acks our ACK
	231	* vectors, when we will free up space in dccpav_buf.
	232	*
	233	* We may well decide to do buffer compression, etc, but for now lets
	234	* just drop.
	235	*
0e64e94e	236	* From Appendix A.1.1 (`New Packets'):
ae31c339 ACM	237	*
	238	* Of course, the circular buffer may overflow, either when the
	239	* HC-Sender is sending data at a very high rate, when the
	240	* HC-Receiver's acknowledgements are not reaching the HC-Sender,
	241	* or when the HC-Sender is forgetting to acknowledge those acks
	242	* (so the HC-Receiver is unable to clean up old state). In this
	243	* case, the HC-Receiver should either compress the buffer (by
	244	* increasing run lengths when possible), transfer its state to
	245	* a larger buffer, or, as a last resort, drop all received
	246	* packets, without processing them whatsoever, until its buffer
	247	* shrinks again.
	248	*/
	249
	250	/* See if this is the first ackno being inserted */
	251	if (av->dccpav_vec_len == 0) {
	252	av->dccpav_buf[av->dccpav_buf_head] = state;
	253	av->dccpav_vec_len = 1;
	254	} else if (after48(ackno, av->dccpav_buf_ackno)) {
	255	const u64 delta = dccp_delta_seqno(av->dccpav_buf_ackno,
	256	ackno);
	257
	258	/*
	259	* Look if the state of this packet is the same as the
	260	* previous ackno and if so if we can bump the head len.
	261	*/
	262	if (delta == 1 &&
	263	dccp_ackvec_state(av, av->dccpav_buf_head) == state &&
	264	(dccp_ackvec_len(av, av->dccpav_buf_head) <
	265	DCCP_ACKVEC_LEN_MASK))
	266	av->dccpav_buf[av->dccpav_buf_head]++;
	267	else if (dccp_ackvec_set_buf_head_state(av, delta, state))
	268	return -ENOBUFS;
	269	} else {
	270	/*
	271	* A.1.2. Old Packets
	272	*
0e64e94e GR	273	* When a packet with Sequence Number S <= buf_ackno
	274	* arrives, the HC-Receiver will scan the table for
	275	* the byte corresponding to S. (Indexing structures
ae31c339 ACM	276	* could reduce the complexity of this scan.)
	277	*/
	278	u64 delta = dccp_delta_seqno(ackno, av->dccpav_buf_ackno);
e4dfd449	279	u8 index = av->dccpav_buf_head;
ae31c339 ACM	280
	281	while (1) {
	282	const u8 len = dccp_ackvec_len(av, index);
	283	const u8 state = dccp_ackvec_state(av, index);
	284	/*
	285	* valid packets not yet in dccpav_buf have a reserved
	286	* entry, with a len equal to 0.
	287	*/
	288	if (state == DCCP_ACKVEC_STATE_NOT_RECEIVED &&
	289	len == 0 && delta == 0) { /* Found our
	290	reserved seat! */
	291	dccp_pr_debug("Found %llu reserved seat!\n",
	292	(unsigned long long)ackno);
	293	av->dccpav_buf[index] = state;
	294	goto out;
	295	}
	296	/* len == 0 means one packet */
	297	if (delta < len + 1)
	298	goto out_duplicate;
	299
	300	delta -= len + 1;
7400d781	301	if (++index == DCCP_MAX_ACKVEC_LEN)
ae31c339 ACM	302	index = 0;
	303	}
	304	}
	305
	306	av->dccpav_buf_ackno = ackno;
	307	dccp_timestamp(sk, &av->dccpav_time);
	308	out:
ae31c339 ACM	309	return 0;
	310
	311	out_duplicate:
	312	/* Duplicate packet */
	313	dccp_pr_debug("Received a dup or already considered lost "
	314	"packet: %llu\n", (unsigned long long)ackno);
	315	return -EILSEQ;
	316	}
	317
	318	#ifdef CONFIG_IP_DCCP_DEBUG
	319	void dccp_ackvector_print(const u64 ackno, const unsigned char *vector, int len)
	320	{
	321	if (!dccp_debug)
	322	return;
	323
	324	printk("ACK vector len=%d, ackno=%llu \|", len,
	325	(unsigned long long)ackno);
	326
	327	while (len--) {
	328	const u8 state = (*vector & DCCP_ACKVEC_STATE_MASK) >> 6;
	329	const u8 rl = *vector & DCCP_ACKVEC_LEN_MASK;
	330
	331	printk("%d,%d\|", state, rl);
	332	++vector;
	333	}
	334
	335	printk("\n");
	336	}
	337
	338	void dccp_ackvec_print(const struct dccp_ackvec *av)
	339	{
	340	dccp_ackvector_print(av->dccpav_buf_ackno,
	341	av->dccpav_buf + av->dccpav_buf_head,
	342	av->dccpav_vec_len);
	343	}
	344	#endif
	345
02bcf28c AB	346	static void dccp_ackvec_throw_record(struct dccp_ackvec *av,
02bcf28c AB	347	struct dccp_ackvec_record *avr)
ae31c339	348	{
02bcf28c AB	349	struct dccp_ackvec_record *next;
02bcf28c AB	350
23d06e3b AB	351	/* sort out vector length */
	352	if (av->dccpav_buf_head <= avr->dccpavr_ack_ptr)
	353	av->dccpav_vec_len = avr->dccpavr_ack_ptr - av->dccpav_buf_head;
	354	else
	355	av->dccpav_vec_len = DCCP_MAX_ACKVEC_LEN - 1
	356	- av->dccpav_buf_head
	357	+ avr->dccpavr_ack_ptr;
02bcf28c AB	358
	359	/* free records */
	360	list_for_each_entry_safe_from(avr, next, &av->dccpav_records,
	361	dccpavr_node) {
	362	list_del_init(&avr->dccpavr_node);
	363	dccp_ackvec_record_delete(avr);
	364	}
ae31c339 ACM	365	}
	366
	367	void dccp_ackvec_check_rcv_ackno(struct dccp_ackvec av, struct sock sk,
	368	const u64 ackno)
	369	{
02bcf28c	370	struct dccp_ackvec_record *avr;
ae31c339	371
02bcf28c AB	372	/*
	373	* If we traverse backwards, it should be faster when we have large
	374	* windows. We will be receiving ACKs for stuff we sent a while back
	375	* -sorbo.
	376	*/
	377	list_for_each_entry_reverse(avr, &av->dccpav_records, dccpavr_node) {
	378	if (ackno == avr->dccpavr_ack_seqno) {
09dbc389	379	dccp_pr_debug("%s ACK packet 0, len=%d, ack_seqno=%llu, "
02bcf28c	380	"ack_ackno=%llu, ACKED!\n",
09dbc389	381	dccp_role(sk), 1,
02bcf28c AB	382	(unsigned long long)avr->dccpavr_ack_seqno,
	383	(unsigned long long)avr->dccpavr_ack_ackno);
	384	dccp_ackvec_throw_record(av, avr);
	385	break;
	386	}
ae31c339 ACM	387	}
	388	}
	389
	390	static void dccp_ackvec_check_rcv_ackvector(struct dccp_ackvec *av,
	391	struct sock *sk, u64 ackno,
	392	const unsigned char len,
	393	const unsigned char *vector)
	394	{
	395	unsigned char i;
02bcf28c	396	struct dccp_ackvec_record *avr;
ae31c339 ACM	397
ae31c339 ACM	398	/* Check if we actually sent an ACK vector */
02bcf28c	399	if (list_empty(&av->dccpav_records))
ae31c339	400	return;
ae31c339 ACM	401
ae31c339 ACM	402	i = len;
02bcf28c AB	403	/*
	404	* XXX
	405	* I think it might be more efficient to work backwards. See comment on
	406	* rcv_ackno. -sorbo.
	407	*/
	408	avr = list_entry(av->dccpav_records.next, struct dccp_ackvec_record,
	409	dccpavr_node);
ae31c339 ACM	410	while (i--) {
	411	const u8 rl = *vector & DCCP_ACKVEC_LEN_MASK;
	412	u64 ackno_end_rl;
	413
	414	dccp_set_seqno(&ackno_end_rl, ackno - rl);
	415
	416	/*
02bcf28c AB	417	* If our AVR sequence number is greater than the ack, go
02bcf28c AB	418	* forward in the AVR list until it is not so.
ae31c339	419	*/
02bcf28c AB	420	list_for_each_entry_from(avr, &av->dccpav_records,
	421	dccpavr_node) {
	422	if (!after48(avr->dccpavr_ack_seqno, ackno))
	423	goto found;
	424	}
	425	/* End of the dccpav_records list, not found, exit */
	426	break;
	427	found:
	428	if (between48(avr->dccpavr_ack_seqno, ackno_end_rl, ackno)) {
8e27e465	429	const u8 state = *vector & DCCP_ACKVEC_STATE_MASK;
ae31c339	430	if (state != DCCP_ACKVEC_STATE_NOT_RECEIVED) {
09dbc389	431	dccp_pr_debug("%s ACK vector 0, len=%d, "
ae31c339 ACM	432	"ack_seqno=%llu, ack_ackno=%llu, "
ae31c339 ACM	433	"ACKED!\n",
09dbc389	434	dccp_role(sk), len,
ae31c339	435	(unsigned long long)
02bcf28c	436	avr->dccpavr_ack_seqno,
ae31c339	437	(unsigned long long)
02bcf28c AB	438	avr->dccpavr_ack_ackno);
02bcf28c AB	439	dccp_ackvec_throw_record(av, avr);
afec35e3	440	break;
ae31c339 ACM	441	}
ae31c339 ACM	442	/*
02bcf28c AB	443	* If it wasn't received, continue scanning... we might
02bcf28c AB	444	* find another one.
ae31c339	445	*/
ae31c339	446	}
ae31c339 ACM	447
	448	dccp_set_seqno(&ackno, ackno_end_rl - 1);
	449	++vector;
	450	}
	451	}
	452
	453	int dccp_ackvec_parse(struct sock sk, const struct sk_buff skb,
	454	const u8 opt, const u8 *value, const u8 len)
	455	{
	456	if (len > DCCP_MAX_ACKVEC_LEN)
	457	return -1;
	458
	459	/* dccp_ackvector_print(DCCP_SKB_CB(skb)->dccpd_ack_seq, value, len); */
	460	dccp_ackvec_check_rcv_ackvector(dccp_sk(sk)->dccps_hc_rx_ackvec, sk,
	461	DCCP_SKB_CB(skb)->dccpd_ack_seq,
	462	len, value);
	463	return 0;
	464	}
9b07ef5d ACM	465
9b07ef5d ACM	466	static char dccp_ackvec_slab_msg[] __initdata =
02bcf28c	467	KERN_CRIT "DCCP: Unable to create ack vectors slab caches\n";
9b07ef5d ACM	468
	469	int __init dccp_ackvec_init(void)
	470	{
	471	dccp_ackvec_slab = kmem_cache_create("dccp_ackvec",
	472	sizeof(struct dccp_ackvec), 0,
	473	SLAB_HWCACHE_ALIGN, NULL, NULL);
02bcf28c AB	474	if (dccp_ackvec_slab == NULL)
	475	goto out_err;
	476
	477	dccp_ackvec_record_slab =
	478	kmem_cache_create("dccp_ackvec_record",
	479	sizeof(struct dccp_ackvec_record),
	480	0, SLAB_HWCACHE_ALIGN, NULL, NULL);
	481	if (dccp_ackvec_record_slab == NULL)
	482	goto out_destroy_slab;
9b07ef5d ACM	483
9b07ef5d ACM	484	return 0;
02bcf28c AB	485
	486	out_destroy_slab:
	487	kmem_cache_destroy(dccp_ackvec_slab);
	488	dccp_ackvec_slab = NULL;
	489	out_err:
	490	printk(dccp_ackvec_slab_msg);
	491	return -ENOBUFS;
9b07ef5d ACM	492	}
	493
	494	void dccp_ackvec_exit(void)
	495	{
	496	if (dccp_ackvec_slab != NULL) {
	497	kmem_cache_destroy(dccp_ackvec_slab);
	498	dccp_ackvec_slab = NULL;
	499	}
02bcf28c AB	500	if (dccp_ackvec_record_slab != NULL) {
	501	kmem_cache_destroy(dccp_ackvec_record_slab);
	502	dccp_ackvec_record_slab = NULL;
	503	}
9b07ef5d	504	}