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 struct tfrc_tx_hist_entry; 44 45 extern int tfrc_tx_hist_add(struct tfrc_tx_hist_entry **headp, u64 seqno); 46 extern void tfrc_tx_hist_purge(struct tfrc_tx_hist_entry **headp); 47 extern u32 tfrc_tx_hist_rtt(struct tfrc_tx_hist_entry *head, 48 const u64 seqno, const ktime_t now); 49 50 /* Subtraction a-b modulo-16, respects circular wrap-around */ 51 #define SUB16(a, b) (((a) + 16 - (b)) & 0xF) 52 53 /* Number of packets to wait after a missing packet (RFC 4342, 6.1) */ 54 #define TFRC_NDUPACK 3 55 56 /** 57 * tfrc_rx_hist_entry - Store information about a single received packet 58 * @tfrchrx_seqno: DCCP packet sequence number 59 * @tfrchrx_ccval: window counter value of packet (RFC 4342, 8.1) 60 * @tfrchrx_ndp: the NDP count (if any) of the packet 61 * @tfrchrx_tstamp: actual receive time of packet 62 */ 63 struct tfrc_rx_hist_entry { 64 u64 tfrchrx_seqno:48, 65 tfrchrx_ccval:4, 66 tfrchrx_type:4; 67 u32 tfrchrx_ndp; /* In fact it is from 8 to 24 bits */ 68 ktime_t tfrchrx_tstamp; 69 }; 70 71 /** 72 * tfrc_rx_hist - RX history structure for TFRC-based protocols 73 * 74 * @ring: Packet history for RTT sampling and loss detection 75 * @loss_count: Number of entries in circular history 76 * @loss_start: Movable index (for loss detection) 77 * @rtt_sample_prev: Used during RTT sampling, points to candidate entry 78 */ 79 struct tfrc_rx_hist { 80 struct tfrc_rx_hist_entry *ring[TFRC_NDUPACK + 1]; 81 u8 loss_count:2, 82 loss_start:2; 83 #define rtt_sample_prev loss_start 84 }; 85 86 /** 87 * tfrc_rx_hist_index - index to reach n-th entry after loss_start 88 */ 89 static inline u8 tfrc_rx_hist_index(const struct tfrc_rx_hist *h, const u8 n) 90 { 91 return (h->loss_start + n) & TFRC_NDUPACK; 92 } 93 94 /** 95 * tfrc_rx_hist_last_rcv - entry with highest-received-seqno so far 96 */ 97 static inline struct tfrc_rx_hist_entry * 98 tfrc_rx_hist_last_rcv(const struct tfrc_rx_hist *h) 99 { 100 return h->ring[tfrc_rx_hist_index(h, h->loss_count)]; 101 } 102 103 /** 104 * tfrc_rx_hist_entry - return the n-th history entry after loss_start 105 */ 106 static inline struct tfrc_rx_hist_entry * 107 tfrc_rx_hist_entry(const struct tfrc_rx_hist *h, const u8 n) 108 { 109 return h->ring[tfrc_rx_hist_index(h, n)]; 110 } 111 112 /** 113 * tfrc_rx_hist_loss_prev - entry with highest-received-seqno before loss was detected 114 */ 115 static inline struct tfrc_rx_hist_entry * 116 tfrc_rx_hist_loss_prev(const struct tfrc_rx_hist *h) 117 { 118 return h->ring[h->loss_start]; 119 } 120 121 /* initialise loss detection and disable RTT sampling */ 122 static inline void tfrc_rx_hist_loss_indicated(struct tfrc_rx_hist *h) 123 { 124 h->loss_count = 1; 125 } 126 127 /* indicate whether previously a packet was detected missing */ 128 static inline int tfrc_rx_hist_loss_pending(const struct tfrc_rx_hist *h) 129 { 130 return h->loss_count; 131 } 132 133 /* any data packets missing between last reception and skb ? */ 134 static inline int tfrc_rx_hist_new_loss_indicated(struct tfrc_rx_hist *h, 135 const struct sk_buff *skb, 136 u32 ndp) 137 { 138 int delta = dccp_delta_seqno(tfrc_rx_hist_last_rcv(h)->tfrchrx_seqno, 139 DCCP_SKB_CB(skb)->dccpd_seq); 140 141 if (delta > 1 && ndp < delta) 142 tfrc_rx_hist_loss_indicated(h); 143 144 return tfrc_rx_hist_loss_pending(h); 145 } 146 147 extern void tfrc_rx_hist_add_packet(struct tfrc_rx_hist *h, 148 const struct sk_buff *skb, const u32 ndp); 149 150 extern int tfrc_rx_hist_duplicate(struct tfrc_rx_hist *h, struct sk_buff *skb); 151 152 struct tfrc_loss_hist; 153 extern int tfrc_rx_handle_loss(struct tfrc_rx_hist *h, 154 struct tfrc_loss_hist *lh, 155 struct sk_buff *skb, u32 ndp, 156 u32 (*first_li)(struct sock *sk), 157 struct sock *sk); 158 extern u32 tfrc_rx_hist_sample_rtt(struct tfrc_rx_hist *h, 159 const struct sk_buff *skb); 160 extern int tfrc_rx_hist_alloc(struct tfrc_rx_hist *h); 161 extern void tfrc_rx_hist_purge(struct tfrc_rx_hist *h); 162 163 #endif /* _DCCP_PKT_HIST_ */ 164