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/dccp.h>
  15 #include <linux/compiler.h>
  16 #include <linux/ktime.h>
  17 #include <linux/list.h>
  18 #include <linux/types.h>
  19
  20 /* We can spread an ack vector across multiple options */
  21 #define DCCP_MAX_ACKVEC_LEN (DCCP_SINGLE_OPT_MAXLEN * 2)
  22
  23 #define DCCP_ACKVEC_STATE_RECEIVED      0
  24 #define DCCP_ACKVEC_STATE_ECN_MARKED    (1 << 6)
  25 #define DCCP_ACKVEC_STATE_NOT_RECEIVED  (3 << 6)
  26
  27 #define DCCP_ACKVEC_STATE_MASK          0xC0 /* 11000000 */
  28 #define DCCP_ACKVEC_LEN_MASK            0x3F /* 00111111 */
  29
  30 /** struct dccp_ackvec - ack vector
  31  *
  32  * This data structure is the one defined in RFC 4340, Appendix A.
  33  *
  34  * @av_buf_head - circular buffer head
  35  * @av_buf_tail - circular buffer tail
  36  * @av_buf_ackno - ack # of the most recent packet acknowledgeable in the
  37  *                     buffer (i.e. %av_buf_head)
  38  * @av_buf_nonce - the one-bit sum of the ECN Nonces on all packets acked
  39  *                     by the buffer with State 0
  40  *
  41  * Additionally, the HC-Receiver must keep some information about the
  42  * Ack Vectors it has recently sent. For each packet sent carrying an
  43  * Ack Vector, it remembers four variables:
  44  *
  45  * @av_records - list of dccp_ackvec_record
  46  * @av_ack_nonce - the one-bit sum of the ECN Nonces for all State 0.
  47  *
  48  * @av_time - the time in usecs
  49  * @av_buf - circular buffer of acknowledgeable packets
  50  */
  51 struct dccp_ackvec {
  52         u64                     av_buf_ackno;
  53         struct list_head        av_records;
  54         ktime_t                 av_time;
  55         u16                     av_buf_head;
  56         u16                     av_vec_len;
  57         u8                      av_buf_nonce;
  58         u8                      av_ack_nonce;
  59         u8                      av_buf[DCCP_MAX_ACKVEC_LEN];
  60 };
  61
  62 /** struct dccp_ackvec_record - ack vector record
  63  *
  64  * ACK vector record as defined in Appendix A of spec.
  65  *
  66  * The list is sorted by avr_ack_seqno
  67  *
  68  * @avr_node - node in av_records
  69  * @avr_ack_seqno - sequence number of the packet this record was sent on
  70  * @avr_ack_ackno - sequence number being acknowledged
  71  * @avr_ack_ptr - pointer into av_buf where this record starts
  72  * @avr_ack_nonce - av_ack_nonce at the time this record was sent
  73  * @avr_sent_len - lenght of the record in av_buf
  74  */
  75 struct dccp_ackvec_record {
  76         struct list_head avr_node;
  77         u64              avr_ack_seqno;
  78         u64              avr_ack_ackno;
  79         u16              avr_ack_ptr;
  80         u16              avr_sent_len;
  81         u8               avr_ack_nonce;
  82 };
  83
  84 struct sock;
  85 struct sk_buff;
  86
  87 extern int dccp_ackvec_init(void);
  88 extern void dccp_ackvec_exit(void);
  89
  90 extern struct dccp_ackvec *dccp_ackvec_alloc(const gfp_t priority);
  91 extern void dccp_ackvec_free(struct dccp_ackvec *av);
  92
  93 extern int dccp_ackvec_add(struct dccp_ackvec *av, const struct sock *sk,
  94                            const u64 ackno, const u8 state);
  95
  96 extern void dccp_ackvec_check_rcv_ackno(struct dccp_ackvec *av,
  97                                         struct sock *sk, const u64 ackno);
  98 extern int dccp_ackvec_parse(struct sock *sk, const struct sk_buff *skb,
  99                              u64 *ackno, const u8 opt,
 100                              const u8 *value, const u8 len);
 101
 102 extern int dccp_insert_option_ackvec(struct sock *sk, struct sk_buff *skb);
 103
 104 static inline int dccp_ackvec_pending(const struct dccp_ackvec *av)
 105 {
 106         return av->av_vec_len;
 107 }
 108 #endif /* _ACKVEC_H */