net/dccp/ackvec.h

   1 #ifndef _ACKVEC_H
   2 #define _ACKVEC_H
   3 /*
   4  *  net/dccp/ackvec.h
   5  *
   6  *  An implementation of Ack Vectors for the DCCP protocol
   7  *  Copyright (c) 2007 University of Aberdeen, Scotland, UK
   8  *  Copyright (c) 2005 Arnaldo Carvalho de Melo <acme@mandriva.com>
   9  *      This program is free software; you can redistribute it and/or modify it
  10  *      under the terms of the GNU General Public License version 2 as
  11  *      published by the Free Software Foundation.
  12  */
  13
  14 #include <linux/dccp.h>
  15 #include <linux/compiler.h>
  16 #include <linux/list.h>
  17 #include <linux/types.h>
  18
  19 /*
  20  * Ack Vector buffer space is static, in multiples of %DCCP_SINGLE_OPT_MAXLEN,
  21  * the maximum size of a single Ack Vector. Setting %DCCPAV_NUM_ACKVECS to 1
  22  * will be sufficient for most cases of low Ack Ratios, using a value of 2 gives
  23  * more headroom if Ack Ratio is higher or when the sender acknowledges slowly.
  24  * The maximum value is bounded by the u16 types for indices and functions.
  25  */
  26 #define DCCPAV_NUM_ACKVECS      2
  27 #define DCCPAV_MAX_ACKVEC_LEN   (DCCP_SINGLE_OPT_MAXLEN * DCCPAV_NUM_ACKVECS)
  28
  29 /* Estimated minimum average Ack Vector length - used for updating MPS */
  30 #define DCCPAV_MIN_OPTLEN       16
  31
  32 enum dccp_ackvec_states {
  33         DCCPAV_RECEIVED =       0x00,
  34         DCCPAV_ECN_MARKED =     0x40,
  35         DCCPAV_RESERVED =       0x80,
  36         DCCPAV_NOT_RECEIVED =   0xC0
  37 };
  38 #define DCCPAV_MAX_RUNLEN       0x3F
  39
  40 static inline u8 dccp_ackvec_runlen(const u8 *cell)
  41 {
  42         return *cell & DCCPAV_MAX_RUNLEN;
  43 }
  44
  45 static inline u8 dccp_ackvec_state(const u8 *cell)
  46 {
  47         return *cell & ~DCCPAV_MAX_RUNLEN;
  48 }
  49
  50 /** struct dccp_ackvec - Ack Vector main data structure
  51  *
  52  * This implements a fixed-size circular buffer within an array and is largely
  53  * based on Appendix A of RFC 4340.
  54  *
  55  * @av_buf:        circular buffer storage area
  56  * @av_buf_head:   head index; begin of live portion in @av_buf
  57  * @av_buf_tail:   tail index; first index _after_ the live portion in @av_buf
  58  * @av_buf_ackno:  highest seqno of acknowledgeable packet recorded in @av_buf
  59  * @av_tail_ackno: lowest  seqno of acknowledgeable packet recorded in @av_buf
  60  * @av_buf_nonce:  ECN nonce sums, each covering subsequent segments of up to
  61  *                 %DCCP_SINGLE_OPT_MAXLEN cells in the live portion of @av_buf
  62  * @av_overflow:   if 1 then buf_head == buf_tail indicates buffer wraparound
  63  * @av_records:    list of %dccp_ackvec_record (Ack Vectors sent previously)
  64  * @av_veclen:     length of the live portion of @av_buf
  65  */
  66 struct dccp_ackvec {
  67         u8                      av_buf[DCCPAV_MAX_ACKVEC_LEN];
  68         u16                     av_buf_head;
  69         u16                     av_buf_tail;
  70         u64                     av_buf_ackno:48;
  71         u64                     av_tail_ackno:48;
  72         bool                    av_buf_nonce[DCCPAV_NUM_ACKVECS];
  73         u8                      av_overflow:1;
  74         struct list_head        av_records;
  75         u16                     av_vec_len;
  76 };
  77
  78 /** struct dccp_ackvec_record - Records information about sent Ack Vectors
  79  *
  80  * These list entries define the additional information which the HC-Receiver
  81  * keeps about recently-sent Ack Vectors; again refer to RFC 4340, Appendix A.
  82  *
  83  * @avr_node:       the list node in @av_records
  84  * @avr_ack_seqno:  sequence number of the packet the Ack Vector was sent on
  85  * @avr_ack_ackno:  the Ack number that this record/Ack Vector refers to
  86  * @avr_ack_ptr:    pointer into @av_buf where this record starts
  87  * @avr_ack_runlen: run length of @avr_ack_ptr at the time of sending
  88  * @avr_ack_nonce:  the sum of @av_buf_nonce's at the time this record was sent
  89  *
  90  * The list as a whole is sorted in descending order by @avr_ack_seqno.
  91  */
  92 struct dccp_ackvec_record {
  93         struct list_head avr_node;
  94         u64              avr_ack_seqno:48;
  95         u64              avr_ack_ackno:48;
  96         u16              avr_ack_ptr;
  97         u8               avr_ack_runlen;
  98         u8               avr_ack_nonce:1;
  99 };
 100
 101 struct sock;
 102 struct sk_buff;
 103
 104 #ifdef CONFIG_IP_DCCP_ACKVEC
 105 extern int dccp_ackvec_init(void);
 106 extern void dccp_ackvec_exit(void);
 107
 108 extern struct dccp_ackvec *dccp_ackvec_alloc(const gfp_t priority);
 109 extern void dccp_ackvec_free(struct dccp_ackvec *av);
 110
 111 extern int dccp_ackvec_add(struct dccp_ackvec *av, const struct sock *sk,
 112                            const u64 ackno, const u8 state);
 113
 114 extern void dccp_ackvec_check_rcv_ackno(struct dccp_ackvec *av,
 115                                         struct sock *sk, const u64 ackno);
 116 extern int dccp_ackvec_parse(struct sock *sk, const struct sk_buff *skb,
 117                              u64 *ackno, const u8 opt,
 118                              const u8 *value, const u8 len);
 119
 120 extern int  dccp_ackvec_update_records(struct dccp_ackvec *av, u64 seq, u8 sum);
 121 extern void dccp_ackvec_clear_state(struct dccp_ackvec *av, const u64 ackno);
 122 extern u16  dccp_ackvec_buflen(const struct dccp_ackvec *av);
 123
 124 static inline bool dccp_ackvec_is_empty(const struct dccp_ackvec *av)
 125 {
 126         return av->av_overflow == 0 && av->av_buf_head == av->av_buf_tail;
 127 }
 128 #else /* CONFIG_IP_DCCP_ACKVEC */
 129 static inline int dccp_ackvec_init(void)
 130 {
 131         return 0;
 132 }
 133
 134 static inline void dccp_ackvec_exit(void)
 135 {
 136 }
 137
 138 static inline struct dccp_ackvec *dccp_ackvec_alloc(const gfp_t priority)
 139 {
 140         return NULL;
 141 }
 142
 143 static inline void dccp_ackvec_free(struct dccp_ackvec *av)
 144 {
 145 }
 146
 147 static inline int dccp_ackvec_add(struct dccp_ackvec *av, const struct sock *sk,
 148                                   const u64 ackno, const u8 state)
 149 {
 150         return -1;
 151 }
 152
 153 static inline void dccp_ackvec_clear_state(struct dccp_ackvec *av,
 154                                             const u64 ackno)
 155 {
 156 }
 157
 158 static inline void dccp_ackvec_check_rcv_ackno(struct dccp_ackvec *av,
 159                                                struct sock *sk, const u64 ackno)
 160 {
 161 }
 162
 163 static inline int dccp_ackvec_parse(struct sock *sk, const struct sk_buff *skb,
 164                                     const u64 *ackno, const u8 opt,
 165                                     const u8 *value, const u8 len)
 166 {
 167         return -1;
 168 }
 169
 170 static inline int dccp_ackvec_update_records(struct dccp_ackvec *av, u64 seq, u8 nonce)
 171 {
 172         return -1;
 173 }
 174
 175 static inline u16 dccp_ackvec_buflen(const struct dccp_ackvec *av)
 176 {
 177         return 0;
 178 }
 179
 180 static inline bool dccp_ackvec_is_empty(const struct dccp_ackvec *av)
 181 {
 182         return true;
 183 }
 184 #endif /* CONFIG_IP_DCCP_ACKVEC */
 185 #endif /* _ACKVEC_H */