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
dccp_ackvec_runlen(const u8 * cell)43 static inline u8 dccp_ackvec_runlen(const u8 *cell)
44 {
45 return *cell & DCCPAV_MAX_RUNLEN;
46 }
47
dccp_ackvec_state(const u8 * cell)48 static inline u8 dccp_ackvec_state(const u8 *cell)
49 {
50 return *cell & ~DCCPAV_MAX_RUNLEN;
51 }
52
53 /** struct dccp_ackvec - Ack Vector main data structure
54 *
55 * This implements a fixed-size circular buffer within an array and is largely
56 * based on Appendix A of RFC 4340.
57 *
58 * @av_buf: circular buffer storage area
59 * @av_buf_head: head index; begin of live portion in @av_buf
60 * @av_buf_tail: tail index; first index _after_ the live portion in @av_buf
61 * @av_buf_ackno: highest seqno of acknowledgeable packet recorded in @av_buf
62 * @av_tail_ackno: lowest seqno of acknowledgeable packet recorded in @av_buf
63 * @av_buf_nonce: ECN nonce sums, each covering subsequent segments of up to
64 * %DCCP_SINGLE_OPT_MAXLEN cells in the live portion of @av_buf
65 * @av_overflow: if 1 then buf_head == buf_tail indicates buffer wraparound
66 * @av_records: list of %dccp_ackvec_record (Ack Vectors sent previously)
67 */
68 struct dccp_ackvec {
69 u8 av_buf[DCCPAV_MAX_ACKVEC_LEN];
70 u16 av_buf_head;
71 u16 av_buf_tail;
72 u64 av_buf_ackno:48;
73 u64 av_tail_ackno:48;
74 bool av_buf_nonce[DCCPAV_NUM_ACKVECS];
75 u8 av_overflow:1;
76 struct list_head av_records;
77 };
78
79 /** struct dccp_ackvec_record - Records information about sent Ack Vectors
80 *
81 * These list entries define the additional information which the HC-Receiver
82 * keeps about recently-sent Ack Vectors; again refer to RFC 4340, Appendix A.
83 *
84 * @avr_node: the list node in @av_records
85 * @avr_ack_seqno: sequence number of the packet the Ack Vector was sent on
86 * @avr_ack_ackno: the Ack number that this record/Ack Vector refers to
87 * @avr_ack_ptr: pointer into @av_buf where this record starts
88 * @avr_ack_runlen: run length of @avr_ack_ptr at the time of sending
89 * @avr_ack_nonce: the sum of @av_buf_nonce's at the time this record was sent
90 *
91 * The list as a whole is sorted in descending order by @avr_ack_seqno.
92 */
93 struct dccp_ackvec_record {
94 struct list_head avr_node;
95 u64 avr_ack_seqno:48;
96 u64 avr_ack_ackno:48;
97 u16 avr_ack_ptr;
98 u8 avr_ack_runlen;
99 u8 avr_ack_nonce:1;
100 };
101
102 extern int dccp_ackvec_init(void);
103 extern void dccp_ackvec_exit(void);
104
105 extern struct dccp_ackvec *dccp_ackvec_alloc(const gfp_t priority);
106 extern void dccp_ackvec_free(struct dccp_ackvec *av);
107
108 extern void dccp_ackvec_input(struct dccp_ackvec *av, struct sk_buff *skb);
109 extern int dccp_ackvec_update_records(struct dccp_ackvec *av, u64 seq, u8 sum);
110 extern void dccp_ackvec_clear_state(struct dccp_ackvec *av, const u64 ackno);
111 extern u16 dccp_ackvec_buflen(const struct dccp_ackvec *av);
112
dccp_ackvec_is_empty(const struct dccp_ackvec * av)113 static inline bool dccp_ackvec_is_empty(const struct dccp_ackvec *av)
114 {
115 return av->av_overflow == 0 && av->av_buf_head == av->av_buf_tail;
116 }
117
118 /**
119 * struct dccp_ackvec_parsed - Record offsets of Ack Vectors in skb
120 * @vec: start of vector (offset into skb)
121 * @len: length of @vec
122 * @nonce: whether @vec had an ECN nonce of 0 or 1
123 * @node: FIFO - arranged in descending order of ack_ackno
124 * This structure is used by CCIDs to access Ack Vectors in a received skb.
125 */
126 struct dccp_ackvec_parsed {
127 u8 *vec,
128 len,
129 nonce:1;
130 struct list_head node;
131 };
132
133 extern int dccp_ackvec_parsed_add(struct list_head *head,
134 u8 *vec, u8 len, u8 nonce);
135 extern void dccp_ackvec_parsed_cleanup(struct list_head *parsed_chunks);
136 #endif /* _ACKVEC_H */
137