net/dccp/ccids/lib/packet_history.h

   1 /*
   2  *  Packet RX/TX history data structures and routines for TFRC-based protocols.
   3  *
   4  *  Copyright (c) 2007   The University of Aberdeen, Scotland, UK
   5  *  Copyright (c) 2005-6 The University of Waikato, Hamilton, New Zealand.
   6  *
   7  *  This code has been developed by the University of Waikato WAND
   8  *  research group. For further information please see http://www.wand.net.nz/
   9  *  or e-mail Ian McDonald - ian.mcdonald@jandi.co.nz
  10  *
  11  *  This code also uses code from Lulea University, rereleased as GPL by its
  12  *  authors:
  13  *  Copyright (c) 2003 Nils-Erik Mattsson, Joacim Haggmark, Magnus Erixzon
  14  *
  15  *  Changes to meet Linux coding standards, to make it meet latest ccid3 draft
  16  *  and to make it work as a loadable module in the DCCP stack written by
  17  *  Arnaldo Carvalho de Melo <acme@conectiva.com.br>.
  18  *
  19  *  Copyright (c) 2005 Arnaldo Carvalho de Melo <acme@conectiva.com.br>
  20  *
  21  *  This program is free software; you can redistribute it and/or modify
  22  *  it under the terms of the GNU General Public License as published by
  23  *  the Free Software Foundation; either version 2 of the License, or
  24  *  (at your option) any later version.
  25  *
  26  *  This program is distributed in the hope that it will be useful,
  27  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  28  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  29  *  GNU General Public License for more details.
  30  *
  31  *  You should have received a copy of the GNU General Public License
  32  *  along with this program; if not, write to the Free Software
  33  *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  34  */
  35
  36 #ifndef _DCCP_PKT_HIST_
  37 #define _DCCP_PKT_HIST_
  38
  39 #include <linux/list.h>
  40 #include <linux/slab.h>
  41 #include "tfrc.h"
  42
  43 /**
  44  *  tfrc_tx_hist_entry  -  Simple singly-linked TX history list
  45  *  @next:  next oldest entry (LIFO order)
  46  *  @seqno: sequence number of this entry
  47  *  @stamp: send time of packet with sequence number @seqno
  48  */
  49 struct tfrc_tx_hist_entry {
  50         struct tfrc_tx_hist_entry *next;
  51         u64                       seqno;
  52         ktime_t                   stamp;
  53 };
  54
  55 static inline struct tfrc_tx_hist_entry *
  56         tfrc_tx_hist_find_entry(struct tfrc_tx_hist_entry *head, u64 seqno)
  57 {
  58         while (head != NULL && head->seqno != seqno)
  59                 head = head->next;
  60         return head;
  61 }
  62
  63 extern int  tfrc_tx_hist_add(struct tfrc_tx_hist_entry **headp, u64 seqno);
  64 extern void tfrc_tx_hist_purge(struct tfrc_tx_hist_entry **headp);
  65
  66 /* Subtraction a-b modulo-16, respects circular wrap-around */
  67 #define SUB16(a, b) (((a) + 16 - (b)) & 0xF)
  68
  69 /* Number of packets to wait after a missing packet (RFC 4342, 6.1) */
  70 #define TFRC_NDUPACK 3
  71
  72 /**
  73  * tfrc_rx_hist_entry - Store information about a single received packet
  74  * @tfrchrx_seqno:      DCCP packet sequence number
  75  * @tfrchrx_ccval:      window counter value of packet (RFC 4342, 8.1)
  76  * @tfrchrx_ndp:        the NDP count (if any) of the packet
  77  * @tfrchrx_tstamp:     actual receive time of packet
  78  */
  79 struct tfrc_rx_hist_entry {
  80         u64              tfrchrx_seqno:48,
  81                          tfrchrx_ccval:4,
  82                          tfrchrx_type:4;
  83         u64              tfrchrx_ndp:48;
  84         ktime_t          tfrchrx_tstamp;
  85 };
  86
  87 /**
  88  * tfrc_rx_hist  -  RX history structure for TFRC-based protocols
  89  *
  90  * @ring:               Packet history for RTT sampling and loss detection
  91  * @loss_count:         Number of entries in circular history
  92  * @loss_start:         Movable index (for loss detection)
  93  * @rtt_sample_prev:    Used during RTT sampling, points to candidate entry
  94  * @packet_size:        Packet size in bytes (as per RFC 3448, 3.1)
  95  * @bytes_recvd:        Number of bytes received since last sending feedback
  96  */
  97 struct tfrc_rx_hist {
  98         struct tfrc_rx_hist_entry *ring[TFRC_NDUPACK + 1];
  99         u8                        loss_count:2,
 100                                   loss_start:2;
 101 #define rtt_sample_prev           loss_start
 102         u32                       packet_size,
 103                                   bytes_recvd;
 104 };
 105
 106 /**
 107  * tfrc_rx_hist_index - index to reach n-th entry after loss_start
 108  */
 109 static inline u8 tfrc_rx_hist_index(const struct tfrc_rx_hist *h, const u8 n)
 110 {
 111         return (h->loss_start + n) & TFRC_NDUPACK;
 112 }
 113
 114 /**
 115  * tfrc_rx_hist_last_rcv - entry with highest-received-seqno so far
 116  */
 117 static inline struct tfrc_rx_hist_entry *
 118                         tfrc_rx_hist_last_rcv(const struct tfrc_rx_hist *h)
 119 {
 120         return h->ring[tfrc_rx_hist_index(h, h->loss_count)];
 121 }
 122
 123 /**
 124  * tfrc_rx_hist_entry - return the n-th history entry after loss_start
 125  */
 126 static inline struct tfrc_rx_hist_entry *
 127                         tfrc_rx_hist_entry(const struct tfrc_rx_hist *h, const u8 n)
 128 {
 129         return h->ring[tfrc_rx_hist_index(h, n)];
 130 }
 131
 132 /**
 133  * tfrc_rx_hist_loss_prev - entry with highest-received-seqno before loss was detected
 134  */
 135 static inline struct tfrc_rx_hist_entry *
 136                         tfrc_rx_hist_loss_prev(const struct tfrc_rx_hist *h)
 137 {
 138         return h->ring[h->loss_start];
 139 }
 140
 141 /* indicate whether previously a packet was detected missing */
 142 static inline bool tfrc_rx_hist_loss_pending(const struct tfrc_rx_hist *h)
 143 {
 144         return h->loss_count > 0;
 145 }
 146
 147 /*
 148  * Accessor functions to retrieve parameters sampled by the RX history
 149  */
 150 static inline u32 tfrc_rx_hist_packet_size(const struct tfrc_rx_hist *h)
 151 {
 152         if (h->packet_size == 0) {
 153                 DCCP_WARN("No sample for s, using fallback\n");
 154                 return TCP_MIN_RCVMSS;
 155         }
 156         return h->packet_size;
 157 }
 158
 159 extern void tfrc_rx_hist_add_packet(struct tfrc_rx_hist *h,
 160                                     const struct sk_buff *skb, const u64 ndp);
 161
 162 extern int tfrc_rx_hist_duplicate(struct tfrc_rx_hist *h, struct sk_buff *skb);
 163
 164 struct tfrc_loss_hist;
 165 extern int  tfrc_rx_handle_loss(struct tfrc_rx_hist *h,
 166                                 struct tfrc_loss_hist *lh,
 167                                 struct sk_buff *skb, const u64 ndp,
 168                                 u32 (*first_li)(struct sock *sk),
 169                                 struct sock *sk);
 170 extern u32 tfrc_rx_hist_sample_rtt(struct tfrc_rx_hist *h,
 171                                    const struct sk_buff *skb);
 172 extern int  tfrc_rx_hist_init(struct tfrc_rx_hist *h, struct sock *sk);
 173 extern void tfrc_rx_hist_purge(struct tfrc_rx_hist *h);
 174
 175 #endif /* _DCCP_PKT_HIST_ */