net/dccp/ccids/lib/packet_history.h

   1 /* SPDX-License-Identifier: GPL-2.0-or-later */
   2 /*
   3  *  Packet RX/TX history data structures and routines for TFRC-based protocols.
   4  *
   5  *  Copyright (c) 2007   The University of Aberdeen, Scotland, UK
   6  *  Copyright (c) 2005-6 The University of Waikato, Hamilton, New Zealand.
   7  *
   8  *  This code has been developed by the University of Waikato WAND
   9  *  research group. For further information please see https://www.wand.net.nz/
  10  *  or e-mail Ian McDonald - ian.mcdonald@jandi.co.nz
  11  *
  12  *  This code also uses code from Lulea University, rereleased as GPL by its
  13  *  authors:
  14  *  Copyright (c) 2003 Nils-Erik Mattsson, Joacim Haggmark, Magnus Erixzon
  15  *
  16  *  Changes to meet Linux coding standards, to make it meet latest ccid3 draft
  17  *  and to make it work as a loadable module in the DCCP stack written by
  18  *  Arnaldo Carvalho de Melo <acme@conectiva.com.br>.
  19  *
  20  *  Copyright (c) 2005 Arnaldo Carvalho de Melo <acme@conectiva.com.br>
  21  */
  22
  23 #ifndef _DCCP_PKT_HIST_
  24 #define _DCCP_PKT_HIST_
  25
  26 #include <linux/list.h>
  27 #include <linux/slab.h>
  28 #include "tfrc.h"
  29
  30 /**
  31  *  tfrc_tx_hist_entry  -  Simple singly-linked TX history list
  32  *  @next:  next oldest entry (LIFO order)
  33  *  @seqno: sequence number of this entry
  34  *  @stamp: send time of packet with sequence number @seqno
  35  */
  36 struct tfrc_tx_hist_entry {
  37         struct tfrc_tx_hist_entry *next;
  38         u64                       seqno;
  39         ktime_t                   stamp;
  40 };
  41
  42 static inline struct tfrc_tx_hist_entry *
  43         tfrc_tx_hist_find_entry(struct tfrc_tx_hist_entry *head, u64 seqno)
  44 {
  45         while (head != NULL && head->seqno != seqno)
  46                 head = head->next;
  47         return head;
  48 }
  49
  50 int tfrc_tx_hist_add(struct tfrc_tx_hist_entry **headp, u64 seqno);
  51 void tfrc_tx_hist_purge(struct tfrc_tx_hist_entry **headp);
  52
  53 /* Subtraction a-b modulo-16, respects circular wrap-around */
  54 #define SUB16(a, b) (((a) + 16 - (b)) & 0xF)
  55
  56 /* Number of packets to wait after a missing packet (RFC 4342, 6.1) */
  57 #define TFRC_NDUPACK 3
  58
  59 /**
  60  * tfrc_rx_hist_entry - Store information about a single received packet
  61  * @tfrchrx_seqno:      DCCP packet sequence number
  62  * @tfrchrx_ccval:      window counter value of packet (RFC 4342, 8.1)
  63  * @tfrchrx_ndp:        the NDP count (if any) of the packet
  64  * @tfrchrx_tstamp:     actual receive time of packet
  65  */
  66 struct tfrc_rx_hist_entry {
  67         u64              tfrchrx_seqno:48,
  68                          tfrchrx_ccval:4,
  69                          tfrchrx_type:4;
  70         u64              tfrchrx_ndp:48;
  71         ktime_t          tfrchrx_tstamp;
  72 };
  73
  74 /**
  75  * tfrc_rx_hist  -  RX history structure for TFRC-based protocols
  76  * @ring:               Packet history for RTT sampling and loss detection
  77  * @loss_count:         Number of entries in circular history
  78  * @loss_start:         Movable index (for loss detection)
  79  * @rtt_sample_prev:    Used during RTT sampling, points to candidate entry
  80  */
  81 struct tfrc_rx_hist {
  82         struct tfrc_rx_hist_entry *ring[TFRC_NDUPACK + 1];
  83         u8                        loss_count:2,
  84                                   loss_start:2;
  85 #define rtt_sample_prev           loss_start
  86 };
  87
  88 /**
  89  * tfrc_rx_hist_index - index to reach n-th entry after loss_start
  90  */
  91 static inline u8 tfrc_rx_hist_index(const struct tfrc_rx_hist *h, const u8 n)
  92 {
  93         return (h->loss_start + n) & TFRC_NDUPACK;
  94 }
  95
  96 /**
  97  * tfrc_rx_hist_last_rcv - entry with highest-received-seqno so far
  98  */
  99 static inline struct tfrc_rx_hist_entry *
 100                         tfrc_rx_hist_last_rcv(const struct tfrc_rx_hist *h)
 101 {
 102         return h->ring[tfrc_rx_hist_index(h, h->loss_count)];
 103 }
 104
 105 /**
 106  * tfrc_rx_hist_entry - return the n-th history entry after loss_start
 107  */
 108 static inline struct tfrc_rx_hist_entry *
 109                         tfrc_rx_hist_entry(const struct tfrc_rx_hist *h, const u8 n)
 110 {
 111         return h->ring[tfrc_rx_hist_index(h, n)];
 112 }
 113
 114 /**
 115  * tfrc_rx_hist_loss_prev - entry with highest-received-seqno before loss was detected
 116  */
 117 static inline struct tfrc_rx_hist_entry *
 118                         tfrc_rx_hist_loss_prev(const struct tfrc_rx_hist *h)
 119 {
 120         return h->ring[h->loss_start];
 121 }
 122
 123 /* indicate whether previously a packet was detected missing */
 124 static inline bool tfrc_rx_hist_loss_pending(const struct tfrc_rx_hist *h)
 125 {
 126         return h->loss_count > 0;
 127 }
 128
 129 void tfrc_rx_hist_add_packet(struct tfrc_rx_hist *h, const struct sk_buff *skb,
 130                              const u64 ndp);
 131
 132 int tfrc_rx_hist_duplicate(struct tfrc_rx_hist *h, struct sk_buff *skb);
 133
 134 struct tfrc_loss_hist;
 135 int tfrc_rx_handle_loss(struct tfrc_rx_hist *h, struct tfrc_loss_hist *lh,
 136                         struct sk_buff *skb, const u64 ndp,
 137                         u32 (*first_li)(struct sock *sk), struct sock *sk);
 138 u32 tfrc_rx_hist_sample_rtt(struct tfrc_rx_hist *h, const struct sk_buff *skb);
 139 int tfrc_rx_hist_alloc(struct tfrc_rx_hist *h);
 140 void tfrc_rx_hist_purge(struct tfrc_rx_hist *h);
 141
 142 #endif /* _DCCP_PKT_HIST_ */