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1 | #ifndef _ACKVEC_H |
2 | #define _ACKVEC_H |
3 | /* |
4 | * net/dccp/ackvec.h |
5 | * |
6 | * An implementation of Ack Vectors for the DCCP protocol |
7 | * Copyright (c) 2007 University of Aberdeen, Scotland, UK |
8 | * Copyright (c) 2005 Arnaldo Carvalho de Melo <acme@mandriva.com> |
9 | * This program is free software; you can redistribute it and/or modify it |
10 | * under the terms of the GNU General Public License version 2 as |
11 | * published by the Free Software Foundation. |
12 | */ |
13 | |
14 | #include <linux/dccp.h> |
15 | #include <linux/compiler.h> |
16 | #include <linux/list.h> |
17 | #include <linux/types.h> |
18 | |
19 | /* |
20 | * Ack Vector buffer space is static, in multiples of %DCCP_SINGLE_OPT_MAXLEN, |
21 | * the maximum size of a single Ack Vector. Setting %DCCPAV_NUM_ACKVECS to 1 |
22 | * will be sufficient for most cases of low Ack Ratios, using a value of 2 gives |
23 | * more headroom if Ack Ratio is higher or when the sender acknowledges slowly. |
24 | * The maximum value is bounded by the u16 types for indices and functions. |
25 | */ |
26 | #define DCCPAV_NUM_ACKVECS 2 |
27 | #define DCCPAV_MAX_ACKVEC_LEN (DCCP_SINGLE_OPT_MAXLEN * DCCPAV_NUM_ACKVECS) |
28 | |
29 | /* Estimated minimum average Ack Vector length - used for updating MPS */ |
30 | #define DCCPAV_MIN_OPTLEN 16 |
31 | |
32 | /* Threshold for coping with large bursts of losses */ |
33 | #define DCCPAV_BURST_THRESH (DCCPAV_MAX_ACKVEC_LEN / 8) |
34 | |
35 | enum dccp_ackvec_states { |
36 | DCCPAV_RECEIVED = 0x00, |
37 | DCCPAV_ECN_MARKED = 0x40, |
38 | DCCPAV_RESERVED = 0x80, |
39 | DCCPAV_NOT_RECEIVED = 0xC0 |
40 | }; |
41 | #define DCCPAV_MAX_RUNLEN 0x3F |
42 | |
43 | static inline u8 dccp_ackvec_runlen(const u8 *cell) |
44 | { |
45 | return *cell & DCCPAV_MAX_RUNLEN; |
46 | } |
47 | |
48 | static inline u8 dccp_ackvec_state(const u8 *cell) |
49 | { |
50 | return *cell & ~DCCPAV_MAX_RUNLEN; |
51 | } |
52 | |
53 | /** |
54 | * struct dccp_ackvec - Ack Vector main data structure |
55 | * |
56 | * This implements a fixed-size circular buffer within an array and is largely |
57 | * based on Appendix A of RFC 4340. |
58 | * |
59 | * @av_buf: circular buffer storage area |
60 | * @av_buf_head: head index; begin of live portion in @av_buf |
61 | * @av_buf_tail: tail index; first index _after_ the live portion in @av_buf |
62 | * @av_buf_ackno: highest seqno of acknowledgeable packet recorded in @av_buf |
63 | * @av_tail_ackno: lowest seqno of acknowledgeable packet recorded in @av_buf |
64 | * @av_buf_nonce: ECN nonce sums, each covering subsequent segments of up to |
65 | * %DCCP_SINGLE_OPT_MAXLEN cells in the live portion of @av_buf |
66 | * @av_overflow: if 1 then buf_head == buf_tail indicates buffer wraparound |
67 | * @av_records: list of %dccp_ackvec_record (Ack Vectors sent previously) |
68 | */ |
69 | struct dccp_ackvec { |
70 | u8 av_buf[DCCPAV_MAX_ACKVEC_LEN]; |
71 | u16 av_buf_head; |
72 | u16 av_buf_tail; |
73 | u64 av_buf_ackno:48; |
74 | u64 av_tail_ackno:48; |
75 | bool av_buf_nonce[DCCPAV_NUM_ACKVECS]; |
76 | u8 av_overflow:1; |
77 | struct list_head av_records; |
78 | }; |
79 | |
80 | /** |
81 | * struct dccp_ackvec_record - Records information about sent Ack Vectors |
82 | * |
83 | * These list entries define the additional information which the HC-Receiver |
84 | * keeps about recently-sent Ack Vectors; again refer to RFC 4340, Appendix A. |
85 | * |
86 | * @avr_node: the list node in @av_records |
87 | * @avr_ack_seqno: sequence number of the packet the Ack Vector was sent on |
88 | * @avr_ack_ackno: the Ack number that this record/Ack Vector refers to |
89 | * @avr_ack_ptr: pointer into @av_buf where this record starts |
90 | * @avr_ack_runlen: run length of @avr_ack_ptr at the time of sending |
91 | * @avr_ack_nonce: the sum of @av_buf_nonce's at the time this record was sent |
92 | * |
93 | * The list as a whole is sorted in descending order by @avr_ack_seqno. |
94 | */ |
95 | struct dccp_ackvec_record { |
96 | struct list_head avr_node; |
97 | u64 avr_ack_seqno:48; |
98 | u64 avr_ack_ackno:48; |
99 | u16 avr_ack_ptr; |
100 | u8 avr_ack_runlen; |
101 | u8 avr_ack_nonce:1; |
102 | }; |
103 | |
104 | extern int dccp_ackvec_init(void); |
105 | extern void dccp_ackvec_exit(void); |
106 | |
107 | extern struct dccp_ackvec *dccp_ackvec_alloc(const gfp_t priority); |
108 | extern void dccp_ackvec_free(struct dccp_ackvec *av); |
109 | |
110 | extern void dccp_ackvec_input(struct dccp_ackvec *av, struct sk_buff *skb); |
111 | extern int dccp_ackvec_update_records(struct dccp_ackvec *av, u64 seq, u8 sum); |
112 | extern void dccp_ackvec_clear_state(struct dccp_ackvec *av, const u64 ackno); |
113 | extern u16 dccp_ackvec_buflen(const struct dccp_ackvec *av); |
114 | |
115 | static inline bool dccp_ackvec_is_empty(const struct dccp_ackvec *av) |
116 | { |
117 | return av->av_overflow == 0 && av->av_buf_head == av->av_buf_tail; |
118 | } |
119 | |
120 | /** |
121 | * struct dccp_ackvec_parsed - Record offsets of Ack Vectors in skb |
122 | * @vec: start of vector (offset into skb) |
123 | * @len: length of @vec |
124 | * @nonce: whether @vec had an ECN nonce of 0 or 1 |
125 | * @node: FIFO - arranged in descending order of ack_ackno |
126 | * |
127 | * This structure is used by CCIDs to access Ack Vectors in a received skb. |
128 | */ |
129 | struct dccp_ackvec_parsed { |
130 | u8 *vec, |
131 | len, |
132 | nonce:1; |
133 | struct list_head node; |
134 | }; |
135 | |
136 | extern int dccp_ackvec_parsed_add(struct list_head *head, |
137 | u8 *vec, u8 len, u8 nonce); |
138 | extern void dccp_ackvec_parsed_cleanup(struct list_head *parsed_chunks); |
139 | #endif /* _ACKVEC_H */ |
140 |
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