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.
25 #define DCCPAV_NUM_ACKVECS 2
26 #define DCCPAV_MAX_ACKVEC_LEN (DCCP_SINGLE_OPT_MAXLEN * DCCPAV_NUM_ACKVECS)
28 /* Estimated minimum average Ack Vector length - used for updating MPS */
29 #define DCCPAV_MIN_OPTLEN 16
31 enum dccp_ackvec_states {
32 DCCPAV_RECEIVED = 0x00,
33 DCCPAV_ECN_MARKED = 0x40,
34 DCCPAV_RESERVED = 0x80,
35 DCCPAV_NOT_RECEIVED = 0xC0
37 #define DCCPAV_MAX_RUNLEN 0x3F
39 static inline u8 dccp_ackvec_runlen(const u8 *cell)
41 return *cell & DCCPAV_MAX_RUNLEN;
44 static inline u8 dccp_ackvec_state(const u8 *cell)
46 return *cell & ~DCCPAV_MAX_RUNLEN;
49 /** struct dccp_ackvec - Ack Vector main data structure
51 * This implements a fixed-size circular buffer within an array and is largely
52 * based on Appendix A of RFC 4340.
54 * @av_buf: circular buffer storage area
55 * @av_buf_head: head index; begin of live portion in @av_buf
56 * @av_buf_tail: tail index; first index _after_ the live portion in @av_buf
57 * @av_buf_ackno: highest seqno of acknowledgeable packet recorded in @av_buf
58 * @av_buf_nonce: ECN nonce sums, each covering subsequent segments of up to
59 * %DCCP_SINGLE_OPT_MAXLEN cells in the live portion of @av_buf
60 * @av_records: list of %dccp_ackvec_record (Ack Vectors sent previously)
61 * @av_veclen: length of the live portion of @av_buf
64 u8 av_buf[DCCPAV_MAX_ACKVEC_LEN];
68 bool av_buf_nonce[DCCPAV_NUM_ACKVECS];
69 struct list_head av_records;
73 /** struct dccp_ackvec_record - Records information about sent Ack Vectors
75 * These list entries define the additional information which the HC-Receiver
76 * keeps about recently-sent Ack Vectors; again refer to RFC 4340, Appendix A.
78 * @avr_node: the list node in @av_records
79 * @avr_ack_seqno: sequence number of the packet the Ack Vector was sent on
80 * @avr_ack_ackno: the Ack number that this record/Ack Vector refers to
81 * @avr_ack_ptr: pointer into @av_buf where this record starts
82 * @avr_ack_runlen: run length of @avr_ack_ptr at the time of sending
83 * @avr_ack_nonce: the sum of @av_buf_nonce's at the time this record was sent
85 * The list as a whole is sorted in descending order by @avr_ack_seqno.
87 struct dccp_ackvec_record {
88 struct list_head avr_node;
99 extern int dccp_ackvec_init(void);
100 extern void dccp_ackvec_exit(void);
102 extern struct dccp_ackvec *dccp_ackvec_alloc(const gfp_t priority);
103 extern void dccp_ackvec_free(struct dccp_ackvec *av);
105 extern int dccp_ackvec_add(struct dccp_ackvec *av, const struct sock *sk,
106 const u64 ackno, const u8 state);
108 extern void dccp_ackvec_check_rcv_ackno(struct dccp_ackvec *av,
109 struct sock *sk, const u64 ackno);
110 extern int dccp_ackvec_parse(struct sock *sk, const struct sk_buff *skb,
111 u64 *ackno, const u8 opt,
112 const u8 *value, const u8 len);
114 extern int dccp_insert_option_ackvec(struct sock *sk, struct sk_buff *skb);
116 static inline int dccp_ackvec_pending(const struct dccp_ackvec *av)
118 return av->av_vec_len;
120 #endif /* _ACKVEC_H */