packet_history.h revision 88e97a93342c0b9e835d510921e7b2df8547d1bd
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 */
49struct tfrc_tx_hist_entry {
50	struct tfrc_tx_hist_entry *next;
51	u64			  seqno;
52	ktime_t			  stamp;
53};
54
55static 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
63extern int  tfrc_tx_hist_add(struct tfrc_tx_hist_entry **headp, u64 seqno);
64extern 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 */
79struct 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 * @rtt_estimate:	Receiver RTT estimate
95 * @packet_size:	Packet size in bytes (as per RFC 3448, 3.1)
96 * @bytes_recvd:	Number of bytes received since @bytes_start
97 * @bytes_start:	Start time for counting @bytes_recvd
98 */
99struct tfrc_rx_hist {
100	struct tfrc_rx_hist_entry *ring[TFRC_NDUPACK + 1];
101	u8			  loss_count:2,
102				  loss_start:2;
103	/* Receiver RTT sampling */
104#define rtt_sample_prev		  loss_start
105	u32			  rtt_estimate;
106	/* Receiver sampling of application payload lengths */
107	u32			  packet_size,
108				  bytes_recvd;
109	ktime_t			  bytes_start;
110};
111
112/**
113 * tfrc_rx_hist_index - index to reach n-th entry after loss_start
114 */
115static inline u8 tfrc_rx_hist_index(const struct tfrc_rx_hist *h, const u8 n)
116{
117	return (h->loss_start + n) & TFRC_NDUPACK;
118}
119
120/**
121 * tfrc_rx_hist_last_rcv - entry with highest-received-seqno so far
122 */
123static inline struct tfrc_rx_hist_entry *
124			tfrc_rx_hist_last_rcv(const struct tfrc_rx_hist *h)
125{
126	return h->ring[tfrc_rx_hist_index(h, h->loss_count)];
127}
128
129/**
130 * tfrc_rx_hist_entry - return the n-th history entry after loss_start
131 */
132static inline struct tfrc_rx_hist_entry *
133			tfrc_rx_hist_entry(const struct tfrc_rx_hist *h, const u8 n)
134{
135	return h->ring[tfrc_rx_hist_index(h, n)];
136}
137
138/**
139 * tfrc_rx_hist_loss_prev - entry with highest-received-seqno before loss was detected
140 */
141static inline struct tfrc_rx_hist_entry *
142			tfrc_rx_hist_loss_prev(const struct tfrc_rx_hist *h)
143{
144	return h->ring[h->loss_start];
145}
146
147/* indicate whether previously a packet was detected missing */
148static inline bool tfrc_rx_hist_loss_pending(const struct tfrc_rx_hist *h)
149{
150	return h->loss_count > 0;
151}
152
153/*
154 * Accessor functions to retrieve parameters sampled by the RX history
155 */
156static inline u32 tfrc_rx_hist_packet_size(const struct tfrc_rx_hist *h)
157{
158	if (h->packet_size == 0) {
159		DCCP_WARN("No sample for s, using fallback\n");
160		return TCP_MIN_RCVMSS;
161	}
162	return h->packet_size;
163
164}
165static inline u32 tfrc_rx_hist_rtt(const struct tfrc_rx_hist *h)
166{
167	if (h->rtt_estimate == 0) {
168		DCCP_WARN("No RTT estimate available, using fallback RTT\n");
169		return  DCCP_FALLBACK_RTT;
170	}
171	return h->rtt_estimate;
172}
173
174static inline void tfrc_rx_hist_restart_byte_counter(struct tfrc_rx_hist *h)
175{
176	h->bytes_recvd = 0;
177	h->bytes_start = ktime_get_real();
178}
179
180extern u32  tfrc_rx_hist_x_recv(struct tfrc_rx_hist *h, const u32 last_x_recv);
181
182
183extern void tfrc_rx_hist_add_packet(struct tfrc_rx_hist *h,
184				    const struct sk_buff *skb, const u64 ndp);
185
186extern int tfrc_rx_hist_duplicate(struct tfrc_rx_hist *h, struct sk_buff *skb);
187
188struct tfrc_loss_hist;
189extern bool tfrc_rx_congestion_event(struct tfrc_rx_hist *h,
190				     struct tfrc_loss_hist *lh,
191				     struct sk_buff *skb, const u64 ndp,
192				     u32 (*first_li)(struct sock *sk),
193				     struct sock *sk);
194extern void tfrc_rx_hist_sample_rtt(struct tfrc_rx_hist *h,
195				    const struct sk_buff *skb);
196extern int  tfrc_rx_hist_init(struct tfrc_rx_hist *h, struct sock *sk);
197extern void tfrc_rx_hist_purge(struct tfrc_rx_hist *h);
198
199#endif /* _DCCP_PKT_HIST_ */
200