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This patch brings the Ack Vector interface up to date. Its main purpose is
to lay the basis for the subsequent patches of this set, which will use the
new data structure fields and routines.
There are no real algorithmic changes, rather an adaptation:
(1) Replaced the static Ack Vector size (2) with a #define so that it can
be adapted (with low loss / Ack Ratio, a value of 1 works, so 2 seems
to be sufficient for the moment) and added a solution so that computing
the ECN nonce will continue to work - even with larger Ack Vectors.
(2) Replaced the #defines for Ack Vector states with a complete enum.
(3) Replaced #defines to compute Ack Vector length and state with general
purpose routines (inlines), and updated code to use these.
(4) Added a `tail' field (conversion to circular buffer in subsequent patch).
(5) Updated the (outdated) documentation for Ack Vector struct.
(6) All sequence number containers now trimmed to 48 bits.
(7) Removal of unused bits:
* removed dccpav_ack_nonce from struct dccp_ackvec, since this is already
redundantly stored in the `dccpavr_ack_nonce' (of Ack Vector record);
* removed Elapsed Time for Ack Vectors (it was nowhere used);
* replaced semantics of dccpavr_sent_len with dccpavr_ack_runlen, since
the code needs to be able to remember the old run length;
* reduced the de-/allocation routines (redundant / duplicate tests).
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
121 lines
4.0 KiB
C
121 lines
4.0 KiB
C
#ifndef _ACKVEC_H
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#define _ACKVEC_H
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/*
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* net/dccp/ackvec.h
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*
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* An implementation of Ack Vectors for the DCCP protocol
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* Copyright (c) 2007 University of Aberdeen, Scotland, UK
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* Copyright (c) 2005 Arnaldo Carvalho de Melo <acme@mandriva.com>
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/dccp.h>
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#include <linux/compiler.h>
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#include <linux/list.h>
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#include <linux/types.h>
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/*
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* Ack Vector buffer space is static, in multiples of %DCCP_SINGLE_OPT_MAXLEN,
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* the maximum size of a single Ack Vector. Setting %DCCPAV_NUM_ACKVECS to 1
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* will be sufficient for most cases of low Ack Ratios, using a value of 2 gives
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* more headroom if Ack Ratio is higher or when the sender acknowledges slowly.
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*/
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#define DCCPAV_NUM_ACKVECS 2
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#define DCCPAV_MAX_ACKVEC_LEN (DCCP_SINGLE_OPT_MAXLEN * DCCPAV_NUM_ACKVECS)
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/* Estimated minimum average Ack Vector length - used for updating MPS */
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#define DCCPAV_MIN_OPTLEN 16
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enum dccp_ackvec_states {
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DCCPAV_RECEIVED = 0x00,
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DCCPAV_ECN_MARKED = 0x40,
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DCCPAV_RESERVED = 0x80,
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DCCPAV_NOT_RECEIVED = 0xC0
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};
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#define DCCPAV_MAX_RUNLEN 0x3F
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static inline u8 dccp_ackvec_runlen(const u8 *cell)
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{
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return *cell & DCCPAV_MAX_RUNLEN;
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}
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static inline u8 dccp_ackvec_state(const u8 *cell)
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{
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return *cell & ~DCCPAV_MAX_RUNLEN;
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}
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/** struct dccp_ackvec - Ack Vector main data structure
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*
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* This implements a fixed-size circular buffer within an array and is largely
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* based on Appendix A of RFC 4340.
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*
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* @av_buf: circular buffer storage area
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* @av_buf_head: head index; begin of live portion in @av_buf
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* @av_buf_tail: tail index; first index _after_ the live portion in @av_buf
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* @av_buf_ackno: highest seqno of acknowledgeable packet recorded in @av_buf
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* @av_buf_nonce: ECN nonce sums, each covering subsequent segments of up to
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* %DCCP_SINGLE_OPT_MAXLEN cells in the live portion of @av_buf
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* @av_records: list of %dccp_ackvec_record (Ack Vectors sent previously)
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* @av_veclen: length of the live portion of @av_buf
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*/
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struct dccp_ackvec {
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u8 av_buf[DCCPAV_MAX_ACKVEC_LEN];
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u16 av_buf_head;
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u16 av_buf_tail;
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u64 av_buf_ackno:48;
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bool av_buf_nonce[DCCPAV_NUM_ACKVECS];
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struct list_head av_records;
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u16 av_vec_len;
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};
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/** struct dccp_ackvec_record - Records information about sent Ack Vectors
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*
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* These list entries define the additional information which the HC-Receiver
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* keeps about recently-sent Ack Vectors; again refer to RFC 4340, Appendix A.
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*
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* @avr_node: the list node in @av_records
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* @avr_ack_seqno: sequence number of the packet the Ack Vector was sent on
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* @avr_ack_ackno: the Ack number that this record/Ack Vector refers to
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* @avr_ack_ptr: pointer into @av_buf where this record starts
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* @avr_ack_runlen: run length of @avr_ack_ptr at the time of sending
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* @avr_ack_nonce: the sum of @av_buf_nonce's at the time this record was sent
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*
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* The list as a whole is sorted in descending order by @avr_ack_seqno.
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*/
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struct dccp_ackvec_record {
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struct list_head avr_node;
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u64 avr_ack_seqno:48;
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u64 avr_ack_ackno:48;
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u16 avr_ack_ptr;
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u8 avr_ack_runlen;
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u8 avr_ack_nonce:1;
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};
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struct sock;
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struct sk_buff;
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extern int dccp_ackvec_init(void);
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extern void dccp_ackvec_exit(void);
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extern struct dccp_ackvec *dccp_ackvec_alloc(const gfp_t priority);
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extern void dccp_ackvec_free(struct dccp_ackvec *av);
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extern int dccp_ackvec_add(struct dccp_ackvec *av, const struct sock *sk,
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const u64 ackno, const u8 state);
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extern void dccp_ackvec_check_rcv_ackno(struct dccp_ackvec *av,
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struct sock *sk, const u64 ackno);
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extern int dccp_ackvec_parse(struct sock *sk, const struct sk_buff *skb,
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u64 *ackno, const u8 opt,
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const u8 *value, const u8 len);
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extern int dccp_insert_option_ackvec(struct sock *sk, struct sk_buff *skb);
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static inline int dccp_ackvec_pending(const struct dccp_ackvec *av)
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{
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return av->av_vec_len;
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}
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#endif /* _ACKVEC_H */
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