ackvec.h

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#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 <[email protected]>
 *  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 {
    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 {
    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 {
    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 */