xref: /linux/net/dccp/ccids/ccid2.h (revision 58e16d792a6a8c6b750f637a4649967fcac853dc)
1 /* SPDX-License-Identifier: GPL-2.0-or-later */
2 /*
3  *  Copyright (c) 2005 Andrea Bittau <a.bittau@cs.ucl.ac.uk>
4  */
5 #ifndef _DCCP_CCID2_H_
6 #define _DCCP_CCID2_H_
7 
8 #include <linux/timer.h>
9 #include <linux/types.h>
10 #include "../ccid.h"
11 #include "../dccp.h"
12 
13 /*
14  * CCID-2 timestamping faces the same issues as TCP timestamping.
15  * Hence we reuse/share as much of the code as possible.
16  */
17 #define ccid2_jiffies32	((u32)jiffies)
18 
19 /* NUMDUPACK parameter from RFC 4341, p. 6 */
20 #define NUMDUPACK	3
21 
22 struct ccid2_seq {
23 	u64			ccid2s_seq;
24 	u32			ccid2s_sent;
25 	int			ccid2s_acked;
26 	struct ccid2_seq	*ccid2s_prev;
27 	struct ccid2_seq	*ccid2s_next;
28 };
29 
30 #define CCID2_SEQBUF_LEN 1024
31 #define CCID2_SEQBUF_MAX 128
32 
33 /*
34  * Multiple of congestion window to keep the sequence window at
35  * (RFC 4340 7.5.2)
36  */
37 #define CCID2_WIN_CHANGE_FACTOR 5
38 
39 /**
40  * struct ccid2_hc_tx_sock - CCID2 TX half connection
41  * @tx_{cwnd,ssthresh,pipe}: as per RFC 4341, section 5
42  * @tx_packets_acked:	     Ack counter for deriving cwnd growth (RFC 3465)
43  * @tx_srtt:		     smoothed RTT estimate, scaled by 2^3
44  * @tx_mdev:		     smoothed RTT variation, scaled by 2^2
45  * @tx_mdev_max:	     maximum of @mdev during one flight
46  * @tx_rttvar:		     moving average/maximum of @mdev_max
47  * @tx_rto:		     RTO value deriving from SRTT and RTTVAR (RFC 2988)
48  * @tx_rtt_seq:		     to decay RTTVAR at most once per flight
49  * @tx_cwnd_used:	     actually used cwnd, W_used of RFC 2861
50  * @tx_expected_wnd:	     moving average of @tx_cwnd_used
51  * @tx_cwnd_stamp:	     to track idle periods in CWV
52  * @tx_lsndtime:	     last time (in jiffies) a data packet was sent
53  * @tx_rpseq:		     last consecutive seqno
54  * @tx_rpdupack:	     dupacks since rpseq
55  * @tx_av_chunks:	     list of Ack Vectors received on current skb
56  */
57 struct ccid2_hc_tx_sock {
58 	u32			tx_cwnd;
59 	u32			tx_ssthresh;
60 	u32			tx_pipe;
61 	u32			tx_packets_acked;
62 	struct ccid2_seq	*tx_seqbuf[CCID2_SEQBUF_MAX];
63 	int			tx_seqbufc;
64 	struct ccid2_seq	*tx_seqh;
65 	struct ccid2_seq	*tx_seqt;
66 
67 	/* RTT measurement: variables/principles are the same as in TCP */
68 	u32			tx_srtt,
69 				tx_mdev,
70 				tx_mdev_max,
71 				tx_rttvar,
72 				tx_rto;
73 	u64			tx_rtt_seq:48;
74 	struct timer_list	tx_rtotimer;
75 	struct sock		*sk;
76 
77 	/* Congestion Window validation (optional, RFC 2861) */
78 	u32			tx_cwnd_used,
79 				tx_expected_wnd,
80 				tx_cwnd_stamp,
81 				tx_lsndtime;
82 
83 	u64			tx_rpseq;
84 	int			tx_rpdupack;
85 	u32			tx_last_cong;
86 	u64			tx_high_ack;
87 	struct list_head	tx_av_chunks;
88 };
89 
ccid2_cwnd_network_limited(struct ccid2_hc_tx_sock * hc)90 static inline bool ccid2_cwnd_network_limited(struct ccid2_hc_tx_sock *hc)
91 {
92 	return hc->tx_pipe >= hc->tx_cwnd;
93 }
94 
95 /*
96  * Convert RFC 3390 larger initial window into an equivalent number of packets.
97  * This is based on the numbers specified in RFC 5681, 3.1.
98  */
rfc3390_bytes_to_packets(const u32 smss)99 static inline u32 rfc3390_bytes_to_packets(const u32 smss)
100 {
101 	return smss <= 1095 ? 4 : (smss > 2190 ? 2 : 3);
102 }
103 
104 /**
105  * struct ccid2_hc_rx_sock  -  Receiving end of CCID-2 half-connection
106  * @rx_num_data_pkts: number of data packets received since last feedback
107  */
108 struct ccid2_hc_rx_sock {
109 	u32	rx_num_data_pkts;
110 };
111 
ccid2_hc_tx_sk(const struct sock * sk)112 static inline struct ccid2_hc_tx_sock *ccid2_hc_tx_sk(const struct sock *sk)
113 {
114 	return ccid_priv(dccp_sk(sk)->dccps_hc_tx_ccid);
115 }
116 
ccid2_hc_rx_sk(const struct sock * sk)117 static inline struct ccid2_hc_rx_sock *ccid2_hc_rx_sk(const struct sock *sk)
118 {
119 	return ccid_priv(dccp_sk(sk)->dccps_hc_rx_ccid);
120 }
121 #endif /* _DCCP_CCID2_H_ */
122