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.
14 #include <linux/dccp.h>
15 #include <linux/compiler.h>
16 #include <linux/list.h>
17 #include <linux/types.h>
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.
26 #define DCCPAV_NUM_ACKVECS 2
27 #define DCCPAV_MAX_ACKVEC_LEN (DCCP_SINGLE_OPT_MAXLEN * DCCPAV_NUM_ACKVECS)
29 /* Estimated minimum average Ack Vector length - used for updating MPS */
30 #define DCCPAV_MIN_OPTLEN 16
32 /* Threshold for coping with large bursts of losses */
33 #define DCCPAV_BURST_THRESH (DCCPAV_MAX_ACKVEC_LEN / 8)
35 enum dccp_ackvec_states {
36 DCCPAV_RECEIVED = 0x00,
37 DCCPAV_ECN_MARKED = 0x40,
38 DCCPAV_RESERVED = 0x80,
39 DCCPAV_NOT_RECEIVED = 0xC0
41 #define DCCPAV_MAX_RUNLEN 0x3F
43 static inline u8 dccp_ackvec_runlen(const u8 *cell)
45 return *cell & DCCPAV_MAX_RUNLEN;
48 static inline u8 dccp_ackvec_state(const u8 *cell)
50 return *cell & ~DCCPAV_MAX_RUNLEN;
53 /** struct dccp_ackvec - Ack Vector main data structure
55 * This implements a fixed-size circular buffer within an array and is largely
56 * based on Appendix A of RFC 4340.
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 * @av_veclen: length of the live portion of @av_buf
70 u8 av_buf[DCCPAV_MAX_ACKVEC_LEN];
75 bool av_buf_nonce[DCCPAV_NUM_ACKVECS];
77 struct list_head av_records;
81 /** struct dccp_ackvec_record - Records information about sent Ack Vectors
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.
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
93 * The list as a whole is sorted in descending order by @avr_ack_seqno.
95 struct dccp_ackvec_record {
96 struct list_head avr_node;
107 #ifdef CONFIG_IP_DCCP_ACKVEC
108 extern int dccp_ackvec_init(void);
109 extern void dccp_ackvec_exit(void);
111 extern struct dccp_ackvec *dccp_ackvec_alloc(const gfp_t priority);
112 extern void dccp_ackvec_free(struct dccp_ackvec *av);
114 extern int dccp_ackvec_add(struct dccp_ackvec *av, const struct sock *sk,
115 const u64 ackno, const u8 state);
117 extern void dccp_ackvec_check_rcv_ackno(struct dccp_ackvec *av,
118 struct sock *sk, const u64 ackno);
119 extern int dccp_ackvec_parse(struct sock *sk, const struct sk_buff *skb,
120 u64 *ackno, const u8 opt,
121 const u8 *value, const u8 len);
123 extern void dccp_ackvec_input(struct dccp_ackvec *av, struct sk_buff *skb);
124 extern int dccp_ackvec_update_records(struct dccp_ackvec *av, u64 seq, u8 sum);
125 extern void dccp_ackvec_clear_state(struct dccp_ackvec *av, const u64 ackno);
126 extern u16 dccp_ackvec_buflen(const struct dccp_ackvec *av);
128 static inline bool dccp_ackvec_is_empty(const struct dccp_ackvec *av)
130 return av->av_overflow == 0 && av->av_buf_head == av->av_buf_tail;
132 #else /* CONFIG_IP_DCCP_ACKVEC */
133 static inline int dccp_ackvec_init(void)
138 static inline void dccp_ackvec_exit(void)
142 static inline struct dccp_ackvec *dccp_ackvec_alloc(const gfp_t priority)
147 static inline void dccp_ackvec_free(struct dccp_ackvec *av)
151 static inline void dccp_ackvec_input(struct dccp_ackvec *av, struct sk_buff *skb)
156 static inline int dccp_ackvec_add(struct dccp_ackvec *av, const struct sock *sk,
157 const u64 ackno, const u8 state)
162 static inline void dccp_ackvec_clear_state(struct dccp_ackvec *av,
167 static inline void dccp_ackvec_check_rcv_ackno(struct dccp_ackvec *av,
168 struct sock *sk, const u64 ackno)
172 static inline int dccp_ackvec_parse(struct sock *sk, const struct sk_buff *skb,
173 const u64 *ackno, const u8 opt,
174 const u8 *value, const u8 len)
179 static inline int dccp_ackvec_update_records(struct dccp_ackvec *av, u64 seq, u8 nonce)
184 static inline u16 dccp_ackvec_buflen(const struct dccp_ackvec *av)
189 static inline bool dccp_ackvec_is_empty(const struct dccp_ackvec *av)
193 #endif /* CONFIG_IP_DCCP_ACKVEC */
194 #endif /* _ACKVEC_H */