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 u64 tfrchrx_ndp:48; 68 ktime_t tfrchrx_tstamp; 69 }; 70 71 /** 72 * tfrc_rx_hist - RX history structure for TFRC-based protocols 73 * @ring: Packet history for RTT sampling and loss detection 74 * @loss_count: Number of entries in circular history 75 * @loss_start: Movable index (for loss detection) 76 * @rtt_sample_prev: Used during RTT sampling, points to candidate entry 77 */ 78 struct tfrc_rx_hist { 79 struct tfrc_rx_hist_entry *ring[TFRC_NDUPACK + 1]; 80 u8 loss_count:2, 81 loss_start:2; 82 #define rtt_sample_prev loss_start 83 }; 84 85 /** 86 * tfrc_rx_hist_index - index to reach n-th entry after loss_start 87 */ 88 static inline u8 tfrc_rx_hist_index(const struct tfrc_rx_hist *h, const u8 n) 89 { 90 return (h->loss_start + n) & TFRC_NDUPACK; 91 } 92 93 /** 94 * tfrc_rx_hist_last_rcv - entry with highest-received-seqno so far 95 */ 96 static inline struct tfrc_rx_hist_entry * 97 tfrc_rx_hist_last_rcv(const struct tfrc_rx_hist *h) 98 { 99 return h->ring[tfrc_rx_hist_index(h, h->loss_count)]; 100 } 101 102 /** 103 * tfrc_rx_hist_entry - return the n-th history entry after loss_start 104 */ 105 static inline struct tfrc_rx_hist_entry * 106 tfrc_rx_hist_entry(const struct tfrc_rx_hist *h, const u8 n) 107 { 108 return h->ring[tfrc_rx_hist_index(h, n)]; 109 } 110 111 /** 112 * tfrc_rx_hist_loss_prev - entry with highest-received-seqno before loss was detected 113 */ 114 static inline struct tfrc_rx_hist_entry * 115 tfrc_rx_hist_loss_prev(const struct tfrc_rx_hist *h) 116 { 117 return h->ring[h->loss_start]; 118 } 119 120 /* indicate whether previously a packet was detected missing */ 121 static inline bool tfrc_rx_hist_loss_pending(const struct tfrc_rx_hist *h) 122 { 123 return h->loss_count > 0; 124 } 125 126 extern void tfrc_rx_hist_add_packet(struct tfrc_rx_hist *h, 127 const struct sk_buff *skb, const u64 ndp); 128 129 extern int tfrc_rx_hist_duplicate(struct tfrc_rx_hist *h, struct sk_buff *skb); 130 131 struct tfrc_loss_hist; 132 extern int tfrc_rx_handle_loss(struct tfrc_rx_hist *h, 133 struct tfrc_loss_hist *lh, 134 struct sk_buff *skb, const u64 ndp, 135 u32 (*first_li)(struct sock *sk), 136 struct sock *sk); 137 extern u32 tfrc_rx_hist_sample_rtt(struct tfrc_rx_hist *h, 138 const struct sk_buff *skb); 139 extern int tfrc_rx_hist_alloc(struct tfrc_rx_hist *h); 140 extern void tfrc_rx_hist_purge(struct tfrc_rx_hist *h); 141 142 #endif /* _DCCP_PKT_HIST_ */ 143