[DCCP] ackvec: Introduce ack vector records

#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 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;

	avr = dccp_ackvec_record_new();

	if (avr == NULL)

		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);

	if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN)

		return -1;

	/*

	 * XXX: now we have just one ack vector sent record, so

	 * we have to wait for it to be cleared.

	 *

	 * Of course this is not acceptable, but this is just for

	 * basic testing now.

	 */

	if (av->dccpav_ack_seqno != DCCP_MAX_SEQNO + 1)

		return -1;

	DCCP_SKB_CB(skb)->dccpd_opt_len += len;

	to    = skb_push(skb, len);

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

	/* Check if buf_head wraps */

	if ((int)av->dccpav_buf_head + len > av->dccpav_vec_len) {

		const u32 tailsize = av->dccpav_vec_len - av->dccpav_buf_head;

	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;

	 *	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.

	 *

	 * This implemention uses just one ack record for now.

	 */

	av->dccpav_ack_seqno = DCCP_SKB_CB(skb)->dccpd_seq;

	av->dccpav_ack_ptr   = av->dccpav_buf_head;

	av->dccpav_ack_ackno = av->dccpav_buf_ackno;

	av->dccpav_ack_nonce = av->dccpav_buf_nonce;

	av->dccpav_sent_len  = av->dccpav_vec_len;

	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("%sACK Vector 0, len=%d, ack_seqno=%llu, "

		      "ack_ackno=%llu\n",

		      debug_prefix, av->dccpav_sent_len,

		      (unsigned long long)av->dccpav_ack_seqno,

		      (unsigned long long)av->dccpav_ack_ackno);

	return -1;

		      debug_prefix, 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)

	if (av != NULL) {

		av->dccpav_buf_head	=

			av->dccpav_buf_tail = DCCP_MAX_ACKVEC_LEN - 1;

		av->dccpav_buf_ackno	=

			av->dccpav_ack_ackno = av->dccpav_ack_seqno = ~0LLU;

		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_sent_len	= 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;

	WARN_ON(!list_empty(&av->dccpav_records));

	kmem_cache_free(dccp_ackvec_slab, av);

}

}

#endif

static void dccp_ackvec_throw_away_ack_record(struct dccp_ackvec *av)

static void dccp_ackvec_throw_record(struct dccp_ackvec *av,

				     struct dccp_ackvec_record *avr)

{

	/*

	 * As we're keeping track of the ack vector size (dccpav_vec_len) and

	 * the sent ack vector size (dccpav_sent_len) we don't need

	 * dccpav_buf_tail at all, but keep this code here as in the future

	 * we'll implement a vector of ack records, as suggested in

	 * draft-ietf-dccp-spec-11.txt Appendix A. -acme

	 */

#if 0

	u32 new_buf_tail = av->dccpav_ack_ptr + 1;

	if (new_buf_tail >= av->dccpav_vec_len)

		new_buf_tail -= av->dccpav_vec_len;

	av->dccpav_buf_tail = new_buf_tail;

#endif

	av->dccpav_vec_len -= av->dccpav_sent_len;

	struct dccp_ackvec_record *next;

	av->dccpav_buf_tail = avr->dccpavr_ack_ptr - 1;

	if (av->dccpav_buf_tail == 0)

		av->dccpav_buf_tail = DCCP_MAX_ACKVEC_LEN - 1;

	av->dccpav_vec_len -= avr->dccpavr_sent_len;

	/* 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)

{

	/* Check if we actually sent an ACK vector */

	if (av->dccpav_ack_seqno == DCCP_MAX_SEQNO + 1)

		return;

	struct dccp_ackvec_record *avr;

	if (ackno == av->dccpav_ack_seqno) {

	/*

	 * 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) {

#ifdef CONFIG_IP_DCCP_DEBUG

			struct dccp_sock *dp = dccp_sk(sk);

			const char *debug_prefix = dp->dccps_role == DCCP_ROLE_CLIENT ?

			dccp_pr_debug("%sACK packet 0, len=%d, ack_seqno=%llu, "

				      "ack_ackno=%llu, ACKED!\n",

				      debug_prefix, 1,

			      (unsigned long long)av->dccpav_ack_seqno,

			      (unsigned long long)av->dccpav_ack_ackno);

		dccp_ackvec_throw_away_ack_record(av);

		av->dccpav_ack_seqno = DCCP_MAX_SEQNO + 1;

				      (unsigned long long)avr->dccpavr_ack_seqno,

				      (unsigned long long)avr->dccpavr_ack_ackno);

			dccp_ackvec_throw_record(av, avr);

			break;

		}

	}

}

					    const unsigned char *vector)

{

	unsigned char i;

	struct dccp_ackvec_record *avr;

	/* Check if we actually sent an ACK vector */

	if (av->dccpav_ack_seqno == DCCP_MAX_SEQNO + 1)

		return;

	/*

	 * We're in the receiver half connection, so if the received an ACK

	 * vector ackno (e.g. 50) before dccpav_ack_seqno (e.g. 52), we're

	 * not interested.

	 *

	 * Extra explanation with example:

	 * 

	 * if we received an ACK vector with ackno 50, it can only be acking

	 * 50, 49, 48, etc, not 52 (the seqno for the ACK vector we sent).

	 */

	/* dccp_pr_debug("is %llu < %llu? ", ackno, av->dccpav_ack_seqno); */

	if (before48(ackno, av->dccpav_ack_seqno)) {

		/* dccp_pr_debug_cat("yes\n"); */

	if (list_empty(&av->dccpav_records))

		return;

	}

	/* dccp_pr_debug_cat("no\n"); */

	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);

		/*

		 * dccp_pr_debug("is %llu <= %llu <= %llu? ", ackno_end_rl,

		 * av->dccpav_ack_seqno, ackno);

		 * If our AVR sequence number is greater than the ack, go

		 * forward in the AVR list until it is not so.

		 */

		if (between48(av->dccpav_ack_seqno, ackno_end_rl, ackno)) {

		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) >> 6;

			/* dccp_pr_debug_cat("yes\n"); */

			if (state != DCCP_ACKVEC_STATE_NOT_RECEIVED) {

#ifdef CONFIG_IP_DCCP_DEBUG

				struct dccp_sock *dp = dccp_sk(sk);

					      "ACKED!\n",

					      debug_prefix, len,

					      (unsigned long long)

					      av->dccpav_ack_seqno,

					      avr->dccpavr_ack_seqno,

					      (unsigned long long)

					      av->dccpav_ack_ackno);

				dccp_ackvec_throw_away_ack_record(av);

					      avr->dccpavr_ack_ackno);

				dccp_ackvec_throw_record(av, avr);

			}

			/*

			 * If dccpav_ack_seqno was not received, no problem

			 * we'll send another ACK vector.

			 * If it wasn't received, continue scanning... we might

			 * find another one.

			 */

			av->dccpav_ack_seqno = DCCP_MAX_SEQNO + 1;

			break;

		}

		/* dccp_pr_debug_cat("no\n"); */

		dccp_set_seqno(&ackno, ackno_end_rl - 1);

		++vector;

}

static char dccp_ackvec_slab_msg[] __initdata =

	KERN_CRIT "DCCP: Unable to create ack vectors slab cache\n";

	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) {

		printk(dccp_ackvec_slab_msg);

		return -ENOBUFS;

	}

	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)

		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;

	}

}

#include <linux/config.h>

#include <linux/compiler.h>

#include <linux/list.h>

#include <linux/time.h>

#include <linux/types.h>

 * Ack Vectors it has recently sent. For each packet sent carrying an

 * Ack Vector, it remembers four variables:

 *

 * @dccpav_ack_seqno - the Sequence Number used for the packet

 * 		       (HC-Receiver seqno)

 * @dccpav_ack_ptr - the value of buf_head at the time of acknowledgement.

 * @dccpav_ack_ackno - the Acknowledgement Number used for the packet

 * 		       (HC-Sender seqno)

 * @dccpav_records - list of dccp_ackvec_record

 * @dccpav_ack_nonce - the one-bit sum of the ECN Nonces for all State 0.

 *

 * @dccpav_time		- the time in usecs

 */

struct dccp_ackvec {

	u64		dccpav_buf_ackno;

	u64		dccpav_ack_seqno;

	u64		dccpav_ack_ackno;

	struct list_head dccpav_records;

	struct timeval	dccpav_time;

	u8		dccpav_buf_head;

	u8		dccpav_buf_tail;

	u8		dccpav_buf[DCCP_MAX_ACKVEC_LEN];

};

/** struct dccp_ackvec_record - ack vector record

 *

 * ACK vector record as defined in Appendix A of spec.

 *

 * The list is sorted by dccpavr_ack_seqno

 *

 * @dccpavr_node - node in dccpav_records

 * @dccpavr_ack_seqno - sequence number of the packet this record was sent on

 * @dccpavr_ack_ackno - sequence number being acknowledged

 * @dccpavr_ack_ptr - pointer into dccpav_buf where this record starts

 * @dccpavr_ack_nonce - dccpav_ack_nonce at the time this record was sent

 * @dccpavr_sent_len - lenght of the record in dccpav_buf

 */

struct dccp_ackvec_record {

	struct list_head dccpavr_node;

	u64		 dccpavr_ack_seqno;

	u64		 dccpavr_ack_ackno;

	u8		 dccpavr_ack_ptr;

	u8		 dccpavr_ack_nonce;

	u8		 dccpavr_sent_len;

};

struct sock;

struct sk_buff;