164 lines
5.3 KiB
C
164 lines
5.3 KiB
C
/*
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* Packet RX/TX history data structures and routines for TFRC-based protocols.
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*
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* Copyright (c) 2007 The University of Aberdeen, Scotland, UK
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* Copyright (c) 2005-6 The University of Waikato, Hamilton, New Zealand.
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*
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* This code has been developed by the University of Waikato WAND
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* research group. For further information please see http://www.wand.net.nz/
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* or e-mail Ian McDonald - ian.mcdonald@jandi.co.nz
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*
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* This code also uses code from Lulea University, rereleased as GPL by its
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* authors:
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* Copyright (c) 2003 Nils-Erik Mattsson, Joacim Haggmark, Magnus Erixzon
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*
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* Changes to meet Linux coding standards, to make it meet latest ccid3 draft
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* and to make it work as a loadable module in the DCCP stack written by
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* Arnaldo Carvalho de Melo <acme@conectiva.com.br>.
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*
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* Copyright (c) 2005 Arnaldo Carvalho de Melo <acme@conectiva.com.br>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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#ifndef _DCCP_PKT_HIST_
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#define _DCCP_PKT_HIST_
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#include <linux/list.h>
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#include <linux/slab.h>
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#include "tfrc.h"
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struct tfrc_tx_hist_entry;
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extern int tfrc_tx_hist_add(struct tfrc_tx_hist_entry **headp, u64 seqno);
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extern void tfrc_tx_hist_purge(struct tfrc_tx_hist_entry **headp);
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extern u32 tfrc_tx_hist_rtt(struct tfrc_tx_hist_entry *head,
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const u64 seqno, const ktime_t now);
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/* Subtraction a-b modulo-16, respects circular wrap-around */
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#define SUB16(a, b) (((a) + 16 - (b)) & 0xF)
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/* Number of packets to wait after a missing packet (RFC 4342, 6.1) */
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#define TFRC_NDUPACK 3
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/**
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* tfrc_rx_hist_entry - Store information about a single received packet
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* @tfrchrx_seqno: DCCP packet sequence number
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* @tfrchrx_ccval: window counter value of packet (RFC 4342, 8.1)
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* @tfrchrx_ndp: the NDP count (if any) of the packet
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* @tfrchrx_tstamp: actual receive time of packet
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*/
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struct tfrc_rx_hist_entry {
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u64 tfrchrx_seqno:48,
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tfrchrx_ccval:4,
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tfrchrx_type:4;
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u32 tfrchrx_ndp; /* In fact it is from 8 to 24 bits */
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ktime_t tfrchrx_tstamp;
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};
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/**
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* tfrc_rx_hist - RX history structure for TFRC-based protocols
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*
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* @ring: Packet history for RTT sampling and loss detection
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* @loss_count: Number of entries in circular history
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* @loss_start: Movable index (for loss detection)
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* @rtt_sample_prev: Used during RTT sampling, points to candidate entry
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*/
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struct tfrc_rx_hist {
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struct tfrc_rx_hist_entry *ring[TFRC_NDUPACK + 1];
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u8 loss_count:2,
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loss_start:2;
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#define rtt_sample_prev loss_start
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};
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/**
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* tfrc_rx_hist_index - index to reach n-th entry after loss_start
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*/
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static inline u8 tfrc_rx_hist_index(const struct tfrc_rx_hist *h, const u8 n)
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{
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return (h->loss_start + n) & TFRC_NDUPACK;
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}
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/**
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* tfrc_rx_hist_last_rcv - entry with highest-received-seqno so far
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*/
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static inline struct tfrc_rx_hist_entry *
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tfrc_rx_hist_last_rcv(const struct tfrc_rx_hist *h)
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{
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return h->ring[tfrc_rx_hist_index(h, h->loss_count)];
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}
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/**
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* tfrc_rx_hist_entry - return the n-th history entry after loss_start
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*/
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static inline struct tfrc_rx_hist_entry *
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tfrc_rx_hist_entry(const struct tfrc_rx_hist *h, const u8 n)
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{
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return h->ring[tfrc_rx_hist_index(h, n)];
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}
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/**
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* tfrc_rx_hist_loss_prev - entry with highest-received-seqno before loss was detected
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*/
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static inline struct tfrc_rx_hist_entry *
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tfrc_rx_hist_loss_prev(const struct tfrc_rx_hist *h)
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{
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return h->ring[h->loss_start];
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}
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/* initialise loss detection and disable RTT sampling */
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static inline void tfrc_rx_hist_loss_indicated(struct tfrc_rx_hist *h)
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{
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h->loss_count = 1;
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}
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/* indicate whether previously a packet was detected missing */
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static inline int tfrc_rx_hist_loss_pending(const struct tfrc_rx_hist *h)
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{
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return h->loss_count;
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}
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/* any data packets missing between last reception and skb ? */
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static inline int tfrc_rx_hist_new_loss_indicated(struct tfrc_rx_hist *h,
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const struct sk_buff *skb,
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u32 ndp)
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{
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int delta = dccp_delta_seqno(tfrc_rx_hist_last_rcv(h)->tfrchrx_seqno,
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DCCP_SKB_CB(skb)->dccpd_seq);
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if (delta > 1 && ndp < delta)
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tfrc_rx_hist_loss_indicated(h);
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return tfrc_rx_hist_loss_pending(h);
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}
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extern void tfrc_rx_hist_add_packet(struct tfrc_rx_hist *h,
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const struct sk_buff *skb, const u32 ndp);
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extern int tfrc_rx_hist_duplicate(struct tfrc_rx_hist *h, struct sk_buff *skb);
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struct tfrc_loss_hist;
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extern int tfrc_rx_handle_loss(struct tfrc_rx_hist *h,
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struct tfrc_loss_hist *lh,
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struct sk_buff *skb, u32 ndp,
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u32 (*first_li)(struct sock *sk),
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struct sock *sk);
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extern u32 tfrc_rx_hist_sample_rtt(struct tfrc_rx_hist *h,
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const struct sk_buff *skb);
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extern int tfrc_rx_hist_alloc(struct tfrc_rx_hist *h);
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extern void tfrc_rx_hist_purge(struct tfrc_rx_hist *h);
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#endif /* _DCCP_PKT_HIST_ */
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