#ifndef _ACKVEC_H#define _ACKVEC_H/* *  net/dccp/ackvec.h * *  An implementation of Ack Vectors for the DCCP protocol *  Copyright (c) 2007 University of Aberdeen, Scotland, UK *  Copyright (c) 2005 Arnaldo Carvalho de Melo <acme@mandriva.com> *	This program is free software; you can redistribute it and/or modify it *	under the terms of the GNU General Public License version 2 as *	published by the Free Software Foundation. */ #include <linux/dccp.h>#include <linux/compiler.h>#include <linux/list.h>#include <linux/types.h> /* * Ack Vector buffer space is static, in multiples of %DCCP_SINGLE_OPT_MAXLEN, * the maximum size of a single Ack Vector. Setting %DCCPAV_NUM_ACKVECS to 1 * will be sufficient for most cases of low Ack Ratios, using a value of 2 gives * more headroom if Ack Ratio is higher or when the sender acknowledges slowly. * The maximum value is bounded by the u16 types for indices and functions. */#define DCCPAV_NUM_ACKVECS	2#define DCCPAV_MAX_ACKVEC_LEN	(DCCP_SINGLE_OPT_MAXLEN * DCCPAV_NUM_ACKVECS) /* Estimated minimum average Ack Vector length - used for updating MPS */#define DCCPAV_MIN_OPTLEN	16 /* Threshold for coping with large bursts of losses */#define DCCPAV_BURST_THRESH	(DCCPAV_MAX_ACKVEC_LEN / 8) enum dccp_ackvec_states {	DCCPAV_RECEIVED =	0x00,	DCCPAV_ECN_MARKED =	0x40,	DCCPAV_RESERVED =	0x80,	DCCPAV_NOT_RECEIVED =	0xC0};#define DCCPAV_MAX_RUNLEN	0x3F static inline u8 dccp_ackvec_runlen(const u8 *cell){	return *cell & DCCPAV_MAX_RUNLEN;} static inline u8 dccp_ackvec_state(const u8 *cell){	return *cell & ~DCCPAV_MAX_RUNLEN;} /** struct dccp_ackvec - Ack Vector main data structure * * This implements a fixed-size circular buffer within an array and is largely * based on Appendix A of RFC 4340. * * @av_buf:	   circular buffer storage area * @av_buf_head:   head index; begin of live portion in @av_buf * @av_buf_tail:   tail index; first index _after_ the live portion in @av_buf * @av_buf_ackno:  highest seqno of acknowledgeable packet recorded in @av_buf * @av_tail_ackno: lowest  seqno of acknowledgeable packet recorded in @av_buf * @av_buf_nonce:  ECN nonce sums, each covering subsequent segments of up to *		   %DCCP_SINGLE_OPT_MAXLEN cells in the live portion of @av_buf * @av_overflow:   if 1 then buf_head == buf_tail indicates buffer wraparound * @av_records:	   list of %dccp_ackvec_record (Ack Vectors sent previously) */struct dccp_ackvec {	u8			av_buf[DCCPAV_MAX_ACKVEC_LEN];	u16			av_buf_head;	u16			av_buf_tail;	u64			av_buf_ackno:48;	u64			av_tail_ackno:48;	bool			av_buf_nonce[DCCPAV_NUM_ACKVECS];	u8			av_overflow:1;	struct list_head	av_records;}; /** struct dccp_ackvec_record - Records information about sent Ack Vectors * * These list entries define the additional information which the HC-Receiver * keeps about recently-sent Ack Vectors; again refer to RFC 4340, Appendix A. * * @avr_node:	    the list node in @av_records * @avr_ack_seqno:  sequence number of the packet the Ack Vector was sent on * @avr_ack_ackno:  the Ack number that this record/Ack Vector refers to * @avr_ack_ptr:    pointer into @av_buf where this record starts * @avr_ack_runlen: run length of @avr_ack_ptr at the time of sending * @avr_ack_nonce:  the sum of @av_buf_nonce's at the time this record was sent * * The list as a whole is sorted in descending order by @avr_ack_seqno. */struct dccp_ackvec_record {	struct list_head avr_node;	u64		 avr_ack_seqno:48;	u64		 avr_ack_ackno:48;	u16		 avr_ack_ptr;	u8		 avr_ack_runlen;	u8		 avr_ack_nonce:1;}; extern int dccp_ackvec_init(void);extern void dccp_ackvec_exit(void); extern struct dccp_ackvec *dccp_ackvec_alloc(const gfp_t priority);extern void dccp_ackvec_free(struct dccp_ackvec *av); extern void dccp_ackvec_input(struct dccp_ackvec *av, struct sk_buff *skb);extern int  dccp_ackvec_update_records(struct dccp_ackvec *av, u64 seq, u8 sum);extern void dccp_ackvec_clear_state(struct dccp_ackvec *av, const u64 ackno);extern u16  dccp_ackvec_buflen(const struct dccp_ackvec *av); static inline bool dccp_ackvec_is_empty(const struct dccp_ackvec *av){	return av->av_overflow == 0 && av->av_buf_head == av->av_buf_tail;} /** * struct dccp_ackvec_parsed  -  Record offsets of Ack Vectors in skb * @vec:	start of vector (offset into skb) * @len:	length of @vec * @nonce:	whether @vec had an ECN nonce of 0 or 1 * @node:	FIFO - arranged in descending order of ack_ackno * This structure is used by CCIDs to access Ack Vectors in a received skb. */struct dccp_ackvec_parsed {	u8		 *vec,			 len,			 nonce:1;	struct list_head node;}; extern int dccp_ackvec_parsed_add(struct list_head *head,				  u8 *vec, u8 len, u8 nonce);extern void dccp_ackvec_parsed_cleanup(struct list_head *parsed_chunks);#endif /* _ACKVEC_H */