LXR linux/net/dccp/ccids/lib/packet

   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 http://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 */
  36struct tfrc_tx_hist_entry {
  37        struct tfrc_tx_hist_entry *next;
  38        u64                       seqno;
  39        ktime_t                   stamp;
  40};
  41
  42static 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
  50int tfrc_tx_hist_add(struct tfrc_tx_hist_entry **headp, u64 seqno);
  51void 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 */
  66struct 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 */
  81struct 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 */
  91static 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 */
  99static 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 */
 108static 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 */
 117static 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 */
 124static inline bool tfrc_rx_hist_loss_pending(const struct tfrc_rx_hist *h)
 125{
 126        return h->loss_count > 0;
 127}
 128
 129void tfrc_rx_hist_add_packet(struct tfrc_rx_hist *h, const struct sk_buff *skb,
 130                             const u64 ndp);
 131
 132int tfrc_rx_hist_duplicate(struct tfrc_rx_hist *h, struct sk_buff *skb);
 133
 134struct tfrc_loss_hist;
 135int 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);
 138u32 tfrc_rx_hist_sample_rtt(struct tfrc_rx_hist *h, const struct sk_buff *skb);
 139int tfrc_rx_hist_alloc(struct tfrc_rx_hist *h);
 140void tfrc_rx_hist_purge(struct tfrc_rx_hist *h);
 141
 142#endif /* _DCCP_PKT_HIST_ */
 143