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 *
tfrc_tx_hist_find_entry(struct tfrc_tx_hist_entry * head,u64 seqno)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 * @ring: Packet history for RTT sampling and loss detection
90 * @loss_count: Number of entries in circular history
91 * @loss_start: Movable index (for loss detection)
92 * @rtt_sample_prev: Used during RTT sampling, points to candidate entry
93 */
94 struct tfrc_rx_hist {
95 struct tfrc_rx_hist_entry *ring[TFRC_NDUPACK + 1];
96 u8 loss_count:2,
97 loss_start:2;
98 #define rtt_sample_prev loss_start
99 };
100
101 /**
102 * tfrc_rx_hist_index - index to reach n-th entry after loss_start
103 */
tfrc_rx_hist_index(const struct tfrc_rx_hist * h,const u8 n)104 static inline u8 tfrc_rx_hist_index(const struct tfrc_rx_hist *h, const u8 n)
105 {
106 return (h->loss_start + n) & TFRC_NDUPACK;
107 }
108
109 /**
110 * tfrc_rx_hist_last_rcv - entry with highest-received-seqno so far
111 */
112 static inline struct tfrc_rx_hist_entry *
tfrc_rx_hist_last_rcv(const struct tfrc_rx_hist * h)113 tfrc_rx_hist_last_rcv(const struct tfrc_rx_hist *h)
114 {
115 return h->ring[tfrc_rx_hist_index(h, h->loss_count)];
116 }
117
118 /**
119 * tfrc_rx_hist_entry - return the n-th history entry after loss_start
120 */
121 static inline struct tfrc_rx_hist_entry *
tfrc_rx_hist_entry(const struct tfrc_rx_hist * h,const u8 n)122 tfrc_rx_hist_entry(const struct tfrc_rx_hist *h, const u8 n)
123 {
124 return h->ring[tfrc_rx_hist_index(h, n)];
125 }
126
127 /**
128 * tfrc_rx_hist_loss_prev - entry with highest-received-seqno before loss was detected
129 */
130 static inline struct tfrc_rx_hist_entry *
tfrc_rx_hist_loss_prev(const struct tfrc_rx_hist * h)131 tfrc_rx_hist_loss_prev(const struct tfrc_rx_hist *h)
132 {
133 return h->ring[h->loss_start];
134 }
135
136 /* indicate whether previously a packet was detected missing */
tfrc_rx_hist_loss_pending(const struct tfrc_rx_hist * h)137 static inline bool tfrc_rx_hist_loss_pending(const struct tfrc_rx_hist *h)
138 {
139 return h->loss_count > 0;
140 }
141
142 extern void tfrc_rx_hist_add_packet(struct tfrc_rx_hist *h,
143 const struct sk_buff *skb, const u64 ndp);
144
145 extern int tfrc_rx_hist_duplicate(struct tfrc_rx_hist *h, struct sk_buff *skb);
146
147 struct tfrc_loss_hist;
148 extern int tfrc_rx_handle_loss(struct tfrc_rx_hist *h,
149 struct tfrc_loss_hist *lh,
150 struct sk_buff *skb, const u64 ndp,
151 u32 (*first_li)(struct sock *sk),
152 struct sock *sk);
153 extern u32 tfrc_rx_hist_sample_rtt(struct tfrc_rx_hist *h,
154 const struct sk_buff *skb);
155 extern int tfrc_rx_hist_alloc(struct tfrc_rx_hist *h);
156 extern void tfrc_rx_hist_purge(struct tfrc_rx_hist *h);
157
158 #endif /* _DCCP_PKT_HIST_ */
159