net/dccp/ackvec.h

   1 #ifndef _ACKVEC_H
   2 #define _ACKVEC_H
   3 /*
   4  *  net/dccp/ackvec.h
   5  *
   6  *  An implementation of the DCCP protocol
   7  *  Copyright (c) 2005 Arnaldo Carvalho de Melo <acme@mandriva.com>
   8  *
   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/compiler.h>
  15 #include <linux/ktime.h>
  16 #include <linux/list.h>
  17 #include <linux/types.h>
  18
  19 /* Read about the ECN nonce to see why it is 253 */
  20 #define DCCP_MAX_ACKVEC_OPT_LEN 253
  21 /* We can spread an ack vector across multiple options */
  22 #define DCCP_MAX_ACKVEC_LEN (DCCP_MAX_ACKVEC_OPT_LEN * 2)
  23
  24 #define DCCP_ACKVEC_STATE_RECEIVED      0
  25 #define DCCP_ACKVEC_STATE_ECN_MARKED    (1 << 6)
  26 #define DCCP_ACKVEC_STATE_NOT_RECEIVED  (3 << 6)
  27
  28 #define DCCP_ACKVEC_STATE_MASK          0xC0 /* 11000000 */
  29 #define DCCP_ACKVEC_LEN_MASK            0x3F /* 00111111 */
  30
  31 /** struct dccp_ackvec - ack vector
  32  *
  33  * This data structure is the one defined in RFC 4340, Appendix A.
  34  *
  35  * @av_buf_head - circular buffer head
  36  * @av_buf_tail - circular buffer tail
  37  * @av_buf_ackno - ack # of the most recent packet acknowledgeable in the
  38  *                     buffer (i.e. %av_buf_head)
  39  * @av_buf_nonce - the one-bit sum of the ECN Nonces on all packets acked
  40  *                     by the buffer with State 0
  41  *
  42  * Additionally, the HC-Receiver must keep some information about the
  43  * Ack Vectors it has recently sent. For each packet sent carrying an
  44  * Ack Vector, it remembers four variables:
  45  *
  46  * @av_records - list of dccp_ackvec_record
  47  * @av_ack_nonce - the one-bit sum of the ECN Nonces for all State 0.
  48  *
  49  * @av_time - the time in usecs
  50  * @av_buf - circular buffer of acknowledgeable packets
  51  */
  52 struct dccp_ackvec {
  53         u64                     av_buf_ackno;
  54         struct list_head        av_records;
  55         ktime_t                 av_time;
  56         u16                     av_buf_head;
  57         u16                     av_vec_len;
  58         u8                      av_buf_nonce;
  59         u8                      av_ack_nonce;
  60         u8                      av_buf[DCCP_MAX_ACKVEC_LEN];
  61 };
  62
  63 /** struct dccp_ackvec_record - ack vector record
  64  *
  65  * ACK vector record as defined in Appendix A of spec.
  66  *
  67  * The list is sorted by avr_ack_seqno
  68  *
  69  * @avr_node - node in av_records
  70  * @avr_ack_seqno - sequence number of the packet this record was sent on
  71  * @avr_ack_ackno - sequence number being acknowledged
  72  * @avr_ack_ptr - pointer into av_buf where this record starts
  73  * @avr_ack_nonce - av_ack_nonce at the time this record was sent
  74  * @avr_sent_len - lenght of the record in av_buf
  75  */
  76 struct dccp_ackvec_record {
  77         struct list_head avr_node;
  78         u64              avr_ack_seqno;
  79         u64              avr_ack_ackno;
  80         u16              avr_ack_ptr;
  81         u16              avr_sent_len;
  82         u8               avr_ack_nonce;
  83 };
  84
  85 struct sock;
  86 struct sk_buff;
  87
  88 #ifdef CONFIG_IP_DCCP_ACKVEC
  89 extern int dccp_ackvec_init(void);
  90 extern void dccp_ackvec_exit(void);
  91
  92 extern struct dccp_ackvec *dccp_ackvec_alloc(const gfp_t priority);
  93 extern void dccp_ackvec_free(struct dccp_ackvec *av);
  94
  95 extern int dccp_ackvec_add(struct dccp_ackvec *av, const struct sock *sk,
  96                            const u64 ackno, const u8 state);
  97
  98 extern void dccp_ackvec_check_rcv_ackno(struct dccp_ackvec *av,
  99                                         struct sock *sk, const u64 ackno);
 100 extern int dccp_ackvec_parse(struct sock *sk, const struct sk_buff *skb,
 101                              u64 *ackno, const u8 opt,
 102                              const u8 *value, const u8 len);
 103
 104 extern int dccp_insert_option_ackvec(struct sock *sk, struct sk_buff *skb);
 105
 106 static inline int dccp_ackvec_pending(const struct dccp_ackvec *av)
 107 {
 108         return av->av_vec_len;
 109 }
 110 #else /* CONFIG_IP_DCCP_ACKVEC */
 111 static inline int dccp_ackvec_init(void)
 112 {
 113         return 0;
 114 }
 115
 116 static inline void dccp_ackvec_exit(void)
 117 {
 118 }
 119
 120 static inline struct dccp_ackvec *dccp_ackvec_alloc(const gfp_t priority)
 121 {
 122         return NULL;
 123 }
 124
 125 static inline void dccp_ackvec_free(struct dccp_ackvec *av)
 126 {
 127 }
 128
 129 static inline int dccp_ackvec_add(struct dccp_ackvec *av, const struct sock *sk,
 130                                   const u64 ackno, const u8 state)
 131 {
 132         return -1;
 133 }
 134
 135 static inline void dccp_ackvec_check_rcv_ackno(struct dccp_ackvec *av,
 136                                                struct sock *sk, const u64 ackno)
 137 {
 138 }
 139
 140 static inline int dccp_ackvec_parse(struct sock *sk, const struct sk_buff *skb,
 141                                     const u64 *ackno, const u8 opt,
 142                                     const u8 *value, const u8 len)
 143 {
 144         return -1;
 145 }
 146
 147 static inline int dccp_insert_option_ackvec(const struct sock *sk,
 148                                             const struct sk_buff *skb)
 149 {
 150         return -1;
 151 }
 152
 153 static inline int dccp_ackvec_pending(const struct dccp_ackvec *av)
 154 {
 155         return 0;
 156 }
 157 #endif /* CONFIG_IP_DCCP_ACKVEC */
 158 #endif /* _ACKVEC_H */