2 * Packet RX/TX history data structures and routines for TFRC-based protocols.
4 * Copyright (c) 2007 The University of Aberdeen, Scotland, UK
5 * Copyright (c) 2005-6 The University of Waikato, Hamilton, New Zealand.
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
11 * This code also uses code from Lulea University, rereleased as GPL by its
13 * Copyright (c) 2003 Nils-Erik Mattsson, Joacim Haggmark, Magnus Erixzon
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>.
19 * Copyright (c) 2005 Arnaldo Carvalho de Melo <acme@conectiva.com.br>
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.
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.
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.
36 #ifndef _DCCP_PKT_HIST_
37 #define _DCCP_PKT_HIST_
39 #include <linux/list.h>
40 #include <linux/slab.h>
43 struct tfrc_tx_hist_entry;
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);
50 /* Subtraction a-b modulo-16, respects circular wrap-around */
51 #define SUB16(a, b) (((a) + 16 - (b)) & 0xF)
53 /* Number of packets to wait after a missing packet (RFC 4342, 6.1) */
54 #define TFRC_NDUPACK 3
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
63 struct tfrc_rx_hist_entry {
67 u32 tfrchrx_ndp; /* In fact it is from 8 to 24 bits */
68 ktime_t tfrchrx_tstamp;
72 * tfrc_rx_hist - RX history structure for TFRC-based protocols
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
80 struct tfrc_rx_hist_entry *ring[TFRC_NDUPACK + 1];
83 #define rtt_sample_prev loss_start
87 * tfrc_rx_hist_index - index to reach n-th entry after loss_start
89 static inline u8 tfrc_rx_hist_index(const struct tfrc_rx_hist *h, const u8 n)
91 return (h->loss_start + n) & TFRC_NDUPACK;
95 * tfrc_rx_hist_last_rcv - entry with highest-received-seqno so far
97 static inline struct tfrc_rx_hist_entry *
98 tfrc_rx_hist_last_rcv(const struct tfrc_rx_hist *h)
100 return h->ring[tfrc_rx_hist_index(h, h->loss_count)];
104 * tfrc_rx_hist_entry - return the n-th history entry after loss_start
106 static inline struct tfrc_rx_hist_entry *
107 tfrc_rx_hist_entry(const struct tfrc_rx_hist *h, const u8 n)
109 return h->ring[tfrc_rx_hist_index(h, n)];
113 * tfrc_rx_hist_loss_prev - entry with highest-received-seqno before loss was detected
115 static inline struct tfrc_rx_hist_entry *
116 tfrc_rx_hist_loss_prev(const struct tfrc_rx_hist *h)
118 return h->ring[h->loss_start];
121 /* initialise loss detection and disable RTT sampling */
122 static inline void tfrc_rx_hist_loss_indicated(struct tfrc_rx_hist *h)
127 /* indicate whether previously a packet was detected missing */
128 static inline int tfrc_rx_hist_loss_pending(const struct tfrc_rx_hist *h)
130 return h->loss_count;
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,
138 int delta = dccp_delta_seqno(tfrc_rx_hist_last_rcv(h)->tfrchrx_seqno,
139 DCCP_SKB_CB(skb)->dccpd_seq);
141 if (delta > 1 && ndp < delta)
142 tfrc_rx_hist_loss_indicated(h);
144 return tfrc_rx_hist_loss_pending(h);
147 extern void tfrc_rx_hist_add_packet(struct tfrc_rx_hist *h,
148 const struct sk_buff *skb, const u32 ndp);
150 extern int tfrc_rx_hist_duplicate(struct tfrc_rx_hist *h, struct sk_buff *skb);
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),
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);
163 #endif /* _DCCP_PKT_HIST_ */