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  */
  25 #define DCCPAV_NUM_ACKVECS      2
  26 #define DCCPAV_MAX_ACKVEC_LEN   (DCCP_SINGLE_OPT_MAXLEN * DCCPAV_NUM_ACKVECS)
  27
  28 /* Estimated minimum average Ack Vector length - used for updating MPS */
  29 #define DCCPAV_MIN_OPTLEN       16
  30
  31 enum dccp_ackvec_states {
  32         DCCPAV_RECEIVED =       0x00,
  33         DCCPAV_ECN_MARKED =     0x40,
  34         DCCPAV_RESERVED =       0x80,
  35         DCCPAV_NOT_RECEIVED =   0xC0
  36 };
  37 #define DCCPAV_MAX_RUNLEN       0x3F
  38
  39 static inline u8 dccp_ackvec_runlen(const u8 *cell)
  40 {
  41         return *cell & DCCPAV_MAX_RUNLEN;
  42 }
  43
  44 static inline u8 dccp_ackvec_state(const u8 *cell)
  45 {
  46         return *cell & ~DCCPAV_MAX_RUNLEN;
  47 }
  48
  49 /** struct dccp_ackvec - Ack Vector main data structure
  50  *
  51  * This implements a fixed-size circular buffer within an array and is largely
  52  * based on Appendix A of RFC 4340.
  53  *
  54  * @av_buf:        circular buffer storage area
  55  * @av_buf_head:   head index; begin of live portion in @av_buf
  56  * @av_buf_tail:   tail index; first index _after_ the live portion in @av_buf
  57  * @av_buf_ackno:  highest seqno of acknowledgeable packet recorded in @av_buf
  58  * @av_buf_nonce:  ECN nonce sums, each covering subsequent segments of up to
  59  *                 %DCCP_SINGLE_OPT_MAXLEN cells in the live portion of @av_buf
  60  * @av_records:    list of %dccp_ackvec_record (Ack Vectors sent previously)
  61  * @av_veclen:     length of the live portion of @av_buf
  62  */
  63 struct dccp_ackvec {
  64         u8                      av_buf[DCCPAV_MAX_ACKVEC_LEN];
  65         u16                     av_buf_head;
  66         u16                     av_buf_tail;
  67         u64                     av_buf_ackno:48;
  68         bool                    av_buf_nonce[DCCPAV_NUM_ACKVECS];
  69         struct list_head        av_records;
  70         u16                     av_vec_len;
  71 };
  72
  73 /** struct dccp_ackvec_record - Records information about sent Ack Vectors
  74  *
  75  * These list entries define the additional information which the HC-Receiver
  76  * keeps about recently-sent Ack Vectors; again refer to RFC 4340, Appendix A.
  77  *
  78  * @avr_node:       the list node in @av_records
  79  * @avr_ack_seqno:  sequence number of the packet the Ack Vector was sent on
  80  * @avr_ack_ackno:  the Ack number that this record/Ack Vector refers to
  81  * @avr_ack_ptr:    pointer into @av_buf where this record starts
  82  * @avr_ack_runlen: run length of @avr_ack_ptr at the time of sending
  83  * @avr_ack_nonce:  the sum of @av_buf_nonce's at the time this record was sent
  84  *
  85  * The list as a whole is sorted in descending order by @avr_ack_seqno.
  86  */
  87 struct dccp_ackvec_record {
  88         struct list_head avr_node;
  89         u64              avr_ack_seqno:48;
  90         u64              avr_ack_ackno:48;
  91         u16              avr_ack_ptr;
  92         u8               avr_ack_runlen;
  93         u8               avr_ack_nonce:1;
  94 };
  95
  96 struct sock;
  97 struct sk_buff;
  98
  99 #ifdef CONFIG_IP_DCCP_ACKVEC
 100 extern int dccp_ackvec_init(void);
 101 extern void dccp_ackvec_exit(void);
 102
 103 extern struct dccp_ackvec *dccp_ackvec_alloc(const gfp_t priority);
 104 extern void dccp_ackvec_free(struct dccp_ackvec *av);
 105
 106 extern int dccp_ackvec_add(struct dccp_ackvec *av, const struct sock *sk,
 107                            const u64 ackno, const u8 state);
 108
 109 extern void dccp_ackvec_check_rcv_ackno(struct dccp_ackvec *av,
 110                                         struct sock *sk, const u64 ackno);
 111 extern int dccp_ackvec_parse(struct sock *sk, const struct sk_buff *skb,
 112                              u64 *ackno, const u8 opt,
 113                              const u8 *value, const u8 len);
 114
 115 extern int dccp_insert_option_ackvec(struct sock *sk, struct sk_buff *skb);
 116
 117 static inline int dccp_ackvec_pending(const struct dccp_ackvec *av)
 118 {
 119         return av->av_vec_len;
 120 }
 121 #else /* CONFIG_IP_DCCP_ACKVEC */
 122 static inline int dccp_ackvec_init(void)
 123 {
 124         return 0;
 125 }
 126
 127 static inline void dccp_ackvec_exit(void)
 128 {
 129 }
 130
 131 static inline struct dccp_ackvec *dccp_ackvec_alloc(const gfp_t priority)
 132 {
 133         return NULL;
 134 }
 135
 136 static inline void dccp_ackvec_free(struct dccp_ackvec *av)
 137 {
 138 }
 139
 140 static inline int dccp_ackvec_add(struct dccp_ackvec *av, const struct sock *sk,
 141                                   const u64 ackno, const u8 state)
 142 {
 143         return -1;
 144 }
 145
 146 static inline void dccp_ackvec_check_rcv_ackno(struct dccp_ackvec *av,
 147                                                struct sock *sk, const u64 ackno)
 148 {
 149 }
 150
 151 static inline int dccp_ackvec_parse(struct sock *sk, const struct sk_buff *skb,
 152                                     const u64 *ackno, const u8 opt,
 153                                     const u8 *value, const u8 len)
 154 {
 155         return -1;
 156 }
 157
 158 static inline int dccp_insert_option_ackvec(const struct sock *sk,
 159                                             const struct sk_buff *skb)
 160 {
 161         return -1;
 162 }
 163
 164 static inline int dccp_ackvec_pending(const struct dccp_ackvec *av)
 165 {
 166         return 0;
 167 }
 168 #endif /* CONFIG_IP_DCCP_ACKVEC */
 169 #endif /* _ACKVEC_H */