1 /*
2  *  Copyright (c) 2005 Andrea Bittau <a.bittau@cs.ucl.ac.uk>
3  *
4  *  This program is free software; you can redistribute it and/or modify
5  *  it under the terms of the GNU General Public License as published by
6  *  the Free Software Foundation; either version 2 of the License, or
7  *  (at your option) any later version.
8  *
9  *  This program is distributed in the hope that it will be useful,
10  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
11  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
12  *  GNU General Public License for more details.
13  *
14  *  You should have received a copy of the GNU General Public License
15  *  along with this program; if not, write to the Free Software
16  *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
17  */
18 #ifndef _DCCP_CCID2_H_
19 #define _DCCP_CCID2_H_
20 
21 #include <linux/timer.h>
22 #include <linux/types.h>
23 #include "../ccid.h"
24 #include "../dccp.h"
25 
26 /*
27  * CCID-2 timestamping faces the same issues as TCP timestamping.
28  * Hence we reuse/share as much of the code as possible.
29  */
30 #define ccid2_time_stamp	tcp_time_stamp
31 
32 /* NUMDUPACK parameter from RFC 4341, p. 6 */
33 #define NUMDUPACK	3
34 
35 struct ccid2_seq {
36 	u64			ccid2s_seq;
37 	u32			ccid2s_sent;
38 	int			ccid2s_acked;
39 	struct ccid2_seq	*ccid2s_prev;
40 	struct ccid2_seq	*ccid2s_next;
41 };
42 
43 #define CCID2_SEQBUF_LEN 1024
44 #define CCID2_SEQBUF_MAX 128
45 
46 /*
47  * Multiple of congestion window to keep the sequence window at
48  * (RFC 4340 7.5.2)
49  */
50 #define CCID2_WIN_CHANGE_FACTOR 5
51 
52 /**
53  * struct ccid2_hc_tx_sock - CCID2 TX half connection
54  * @tx_{cwnd,ssthresh,pipe}: as per RFC 4341, section 5
55  * @tx_packets_acked:	     Ack counter for deriving cwnd growth (RFC 3465)
56  * @tx_srtt:		     smoothed RTT estimate, scaled by 2^3
57  * @tx_mdev:		     smoothed RTT variation, scaled by 2^2
58  * @tx_mdev_max:	     maximum of @mdev during one flight
59  * @tx_rttvar:		     moving average/maximum of @mdev_max
60  * @tx_rto:		     RTO value deriving from SRTT and RTTVAR (RFC 2988)
61  * @tx_rtt_seq:		     to decay RTTVAR at most once per flight
62  * @tx_cwnd_used:	     actually used cwnd, W_used of RFC 2861
63  * @tx_expected_wnd:	     moving average of @tx_cwnd_used
64  * @tx_cwnd_stamp:	     to track idle periods in CWV
65  * @tx_lsndtime:	     last time (in jiffies) a data packet was sent
66  * @tx_rpseq:		     last consecutive seqno
67  * @tx_rpdupack:	     dupacks since rpseq
68  * @tx_av_chunks:	     list of Ack Vectors received on current skb
69  */
70 struct ccid2_hc_tx_sock {
71 	u32			tx_cwnd;
72 	u32			tx_ssthresh;
73 	u32			tx_pipe;
74 	u32			tx_packets_acked;
75 	struct ccid2_seq	*tx_seqbuf[CCID2_SEQBUF_MAX];
76 	int			tx_seqbufc;
77 	struct ccid2_seq	*tx_seqh;
78 	struct ccid2_seq	*tx_seqt;
79 
80 	/* RTT measurement: variables/principles are the same as in TCP */
81 	u32			tx_srtt,
82 				tx_mdev,
83 				tx_mdev_max,
84 				tx_rttvar,
85 				tx_rto;
86 	u64			tx_rtt_seq:48;
87 	struct timer_list	tx_rtotimer;
88 
89 	/* Congestion Window validation (optional, RFC 2861) */
90 	u32			tx_cwnd_used,
91 				tx_expected_wnd,
92 				tx_cwnd_stamp,
93 				tx_lsndtime;
94 
95 	u64			tx_rpseq;
96 	int			tx_rpdupack;
97 	u32			tx_last_cong;
98 	u64			tx_high_ack;
99 	struct list_head	tx_av_chunks;
100 };
101 
ccid2_cwnd_network_limited(struct ccid2_hc_tx_sock * hc)102 static inline bool ccid2_cwnd_network_limited(struct ccid2_hc_tx_sock *hc)
103 {
104 	return hc->tx_pipe >= hc->tx_cwnd;
105 }
106 
107 /*
108  * Convert RFC 3390 larger initial window into an equivalent number of packets.
109  * This is based on the numbers specified in RFC 5681, 3.1.
110  */
rfc3390_bytes_to_packets(const u32 smss)111 static inline u32 rfc3390_bytes_to_packets(const u32 smss)
112 {
113 	return smss <= 1095 ? 4 : (smss > 2190 ? 2 : 3);
114 }
115 
116 /**
117  * struct ccid2_hc_rx_sock  -  Receiving end of CCID-2 half-connection
118  * @rx_num_data_pkts: number of data packets received since last feedback
119  */
120 struct ccid2_hc_rx_sock {
121 	u32	rx_num_data_pkts;
122 };
123 
ccid2_hc_tx_sk(const struct sock * sk)124 static inline struct ccid2_hc_tx_sock *ccid2_hc_tx_sk(const struct sock *sk)
125 {
126 	return ccid_priv(dccp_sk(sk)->dccps_hc_tx_ccid);
127 }
128 
ccid2_hc_rx_sk(const struct sock * sk)129 static inline struct ccid2_hc_rx_sock *ccid2_hc_rx_sk(const struct sock *sk)
130 {
131 	return ccid_priv(dccp_sk(sk)->dccps_hc_rx_ccid);
132 }
133 #endif /* _DCCP_CCID2_H_ */
134