1 /* SPDX-License-Identifier: GPL-2.0-or-later */
2 /*
3  *  Copyright (c) 2005-7 The University of Waikato, Hamilton, New Zealand.
4  *  Copyright (c) 2007   The University of Aberdeen, Scotland, UK
5  *
6  *  An implementation of the DCCP protocol
7  *
8  *  This code has been developed by the University of Waikato WAND
9  *  research group. For further information please see https://www.wand.net.nz/
10  *  or e-mail Ian McDonald - ian.mcdonald@jandi.co.nz
11  *
12  *  This code also uses code from Lulea University, rereleased as GPL by its
13  *  authors:
14  *  Copyright (c) 2003 Nils-Erik Mattsson, Joacim Haggmark, Magnus Erixzon
15  *
16  *  Changes to meet Linux coding standards, to make it meet latest ccid3 draft
17  *  and to make it work as a loadable module in the DCCP stack written by
18  *  Arnaldo Carvalho de Melo <acme@conectiva.com.br>.
19  *
20  *  Copyright (c) 2005 Arnaldo Carvalho de Melo <acme@conectiva.com.br>
21  */
22 #ifndef _DCCP_CCID3_H_
23 #define _DCCP_CCID3_H_
24 
25 #include <linux/ktime.h>
26 #include <linux/list.h>
27 #include <linux/types.h>
28 #include <linux/tfrc.h>
29 #include "lib/tfrc.h"
30 #include "../ccid.h"
31 
32 /* Two seconds as per RFC 5348, 4.2 */
33 #define TFRC_INITIAL_TIMEOUT	   (2 * USEC_PER_SEC)
34 
35 /* Parameter t_mbi from [RFC 3448, 4.3]: backoff interval in seconds */
36 #define TFRC_T_MBI		   64
37 
38 /*
39  * The t_delta parameter (RFC 5348, 8.3): delays of less than %USEC_PER_MSEC are
40  * rounded down to 0, since sk_reset_timer() here uses millisecond granularity.
41  * Hence we can use a constant t_delta = %USEC_PER_MSEC when HZ >= 500. A coarse
42  * resolution of HZ < 500 means that the error is below one timer tick (t_gran)
43  * when using the constant t_delta  =  t_gran / 2  =  %USEC_PER_SEC / (2 * HZ).
44  */
45 #if (HZ >= 500)
46 # define TFRC_T_DELTA		   USEC_PER_MSEC
47 #else
48 # define TFRC_T_DELTA		   (USEC_PER_SEC / (2 * HZ))
49 #endif
50 
51 enum ccid3_options {
52 	TFRC_OPT_LOSS_EVENT_RATE = 192,
53 	TFRC_OPT_LOSS_INTERVALS	 = 193,
54 	TFRC_OPT_RECEIVE_RATE	 = 194,
55 };
56 
57 /* TFRC sender states */
58 enum ccid3_hc_tx_states {
59 	TFRC_SSTATE_NO_SENT = 1,
60 	TFRC_SSTATE_NO_FBACK,
61 	TFRC_SSTATE_FBACK,
62 };
63 
64 /**
65  * struct ccid3_hc_tx_sock - CCID3 sender half-connection socket
66  * @tx_x:		  Current sending rate in 64 * bytes per second
67  * @tx_x_recv:		  Receive rate in 64 * bytes per second
68  * @tx_x_calc:		  Calculated rate in bytes per second
69  * @tx_rtt:		  Estimate of current round trip time in usecs
70  * @tx_p:		  Current loss event rate (0-1) scaled by 1000000
71  * @tx_s:		  Packet size in bytes
72  * @tx_t_rto:		  Nofeedback Timer setting in usecs
73  * @tx_t_ipi:		  Interpacket (send) interval (RFC 3448, 4.6) in usecs
74  * @tx_state:		  Sender state, one of %ccid3_hc_tx_states
75  * @tx_last_win_count:	  Last window counter sent
76  * @tx_t_last_win_count:  Timestamp of earliest packet
77  *			  with last_win_count value sent
78  * @tx_no_feedback_timer: Handle to no feedback timer
79  * @tx_t_ld:		  Time last doubled during slow start
80  * @tx_t_nom:		  Nominal send time of next packet
81  * @tx_hist:		  Packet history
82  */
83 struct ccid3_hc_tx_sock {
84 	u64				tx_x;
85 	u64				tx_x_recv;
86 	u32				tx_x_calc;
87 	u32				tx_rtt;
88 	u32				tx_p;
89 	u32				tx_t_rto;
90 	u32				tx_t_ipi;
91 	u16				tx_s;
92 	enum ccid3_hc_tx_states		tx_state:8;
93 	u8				tx_last_win_count;
94 	ktime_t				tx_t_last_win_count;
95 	struct timer_list		tx_no_feedback_timer;
96 	struct sock			*sk;
97 	ktime_t				tx_t_ld;
98 	ktime_t				tx_t_nom;
99 	struct tfrc_tx_hist_entry	*tx_hist;
100 };
101 
ccid3_hc_tx_sk(const struct sock * sk)102 static inline struct ccid3_hc_tx_sock *ccid3_hc_tx_sk(const struct sock *sk)
103 {
104 	struct ccid3_hc_tx_sock *hctx = ccid_priv(dccp_sk(sk)->dccps_hc_tx_ccid);
105 	BUG_ON(hctx == NULL);
106 	return hctx;
107 }
108 
109 /* TFRC receiver states */
110 enum ccid3_hc_rx_states {
111 	TFRC_RSTATE_NO_DATA = 1,
112 	TFRC_RSTATE_DATA,
113 };
114 
115 /**
116  * struct ccid3_hc_rx_sock - CCID3 receiver half-connection socket
117  * @rx_last_counter:	     Tracks window counter (RFC 4342, 8.1)
118  * @rx_state:		     Receiver state, one of %ccid3_hc_rx_states
119  * @rx_bytes_recv:	     Total sum of DCCP payload bytes
120  * @rx_x_recv:		     Receiver estimate of send rate (RFC 3448, sec. 4.3)
121  * @rx_rtt:		     Receiver estimate of RTT
122  * @rx_tstamp_last_feedback: Time at which last feedback was sent
123  * @rx_hist:		     Packet history (loss detection + RTT sampling)
124  * @rx_li_hist:		     Loss Interval database
125  * @rx_s:		     Received packet size in bytes
126  * @rx_pinv:		     Inverse of Loss Event Rate (RFC 4342, sec. 8.5)
127  */
128 struct ccid3_hc_rx_sock {
129 	u8				rx_last_counter:4;
130 	enum ccid3_hc_rx_states		rx_state:8;
131 	u32				rx_bytes_recv;
132 	u32				rx_x_recv;
133 	u32				rx_rtt;
134 	ktime_t				rx_tstamp_last_feedback;
135 	struct tfrc_rx_hist		rx_hist;
136 	struct tfrc_loss_hist		rx_li_hist;
137 	u16				rx_s;
138 #define rx_pinv				rx_li_hist.i_mean
139 };
140 
ccid3_hc_rx_sk(const struct sock * sk)141 static inline struct ccid3_hc_rx_sock *ccid3_hc_rx_sk(const struct sock *sk)
142 {
143 	struct ccid3_hc_rx_sock *hcrx = ccid_priv(dccp_sk(sk)->dccps_hc_rx_ccid);
144 	BUG_ON(hcrx == NULL);
145 	return hcrx;
146 }
147 
148 #endif /* _DCCP_CCID3_H_ */
149