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Commit 522f1d09 authored by Andrea Bittau's avatar Andrea Bittau Committed by David S. Miller
Browse files

[DCCP] ackvec: Split long ack vectors across multiple options 



Ack vectors grow proportional to the window size.  If an ack vector does not fit
into a single option, it must be spread across multiple options.  This patch
will allow for windows to grow larger.

Committer note: Simplified the patch a bit, original algorithm kept.

Signed-off-by: default avatarAndrea Bittau <a.bittau@cs.ucl.ac.uk>
Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@mandriva.com>
parent bdf13d20

net/dccp/ackvec.c

+32 −14
Original line number Diff line number Diff line
@@ -68,10 +68,15 @@ 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;

	/* Figure out how many options do we need to represent the ackvec */

	const u16 nr_opts = (av->dccpav_vec_len +

			     DCCP_MAX_ACKVEC_OPT_LEN - 1) /

			    DCCP_MAX_ACKVEC_OPT_LEN;

	u16 len = av->dccpav_vec_len + 2 * nr_opts, i;

	struct timeval now;

	u32 elapsed_time;

	unsigned char *to, *from;

	const unsigned char *tail, *from;

	unsigned char *to;

	struct dccp_ackvec_record *avr;



	if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN)
@@ -91,23 +96,36 @@ int dccp_insert_option_ackvec(struct sock *sk, struct sk_buff *skb) 
	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;

	tail = av->dccpav_buf + DCCP_MAX_ACKVEC_LEN;



	for (i = 0; i < nr_opts; ++i) {

		int copylen = len;



		if (len > DCCP_MAX_ACKVEC_OPT_LEN)

			copylen = DCCP_MAX_ACKVEC_OPT_LEN;



		*to++ = DCCPO_ACK_VECTOR_0;

		*to++ = copylen + 2;



		/* 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;

		if (from + copylen > tail) {

			const u16 tailsize = tail - from;



			memcpy(to, from, tailsize);

			to	+= tailsize;

			len	-= tailsize;

			copylen	-= tailsize;

			from	= av->dccpav_buf;

		}



	memcpy(to, from, len);

		memcpy(to, from, copylen);

		from += copylen;

		to   += copylen;

		len  -= copylen;

	}



	/*

	 *	From RFC 4340, A.2:

	 *