361a5c1dd0
This patch resolves a long-standing FIXME to dynamically update the Maximum Packet Size depending on actual options usage. It uses the flags set by the feature-negotiation infrastructure to compute the required header option size. Most options are fixed-size, a notable exception are Ack Vectors (required currently only by CCID-2). These can have any length between 3 and 1020 bytes. As a result of testing, 16 bytes (2 bytes for type/length plus 14 Ack Vector cells) have been found to be sufficient for loss-free situations. There are currently no CCID-specific header options which may appear on data packets, thus it is not necessary to define a corresponding CCID field as suggested in the old comment. Further changes: ---------------- Adjusted the type of 'cur_mps' to match the unsigned return type of the function. Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk> Acked-by: Ian McDonald <ian.mcdonald@jandi.co.nz> Signed-off-by: David S. Miller <davem@davemloft.net>
111 lines
3.3 KiB
C
111 lines
3.3 KiB
C
#ifndef _ACKVEC_H
|
|
#define _ACKVEC_H
|
|
/*
|
|
* net/dccp/ackvec.h
|
|
*
|
|
* An implementation of the DCCP protocol
|
|
* Copyright (c) 2005 Arnaldo Carvalho de Melo <acme@mandriva.com>
|
|
*
|
|
* This program is free software; you can redistribute it and/or modify it
|
|
* under the terms of the GNU General Public License version 2 as
|
|
* published by the Free Software Foundation.
|
|
*/
|
|
|
|
#include <linux/dccp.h>
|
|
#include <linux/compiler.h>
|
|
#include <linux/ktime.h>
|
|
#include <linux/list.h>
|
|
#include <linux/types.h>
|
|
|
|
/* We can spread an ack vector across multiple options */
|
|
#define DCCP_MAX_ACKVEC_LEN (DCCP_SINGLE_OPT_MAXLEN * 2)
|
|
|
|
/* Estimated minimum average Ack Vector length - used for updating MPS */
|
|
#define DCCPAV_MIN_OPTLEN 16
|
|
|
|
#define DCCP_ACKVEC_STATE_RECEIVED 0
|
|
#define DCCP_ACKVEC_STATE_ECN_MARKED (1 << 6)
|
|
#define DCCP_ACKVEC_STATE_NOT_RECEIVED (3 << 6)
|
|
|
|
#define DCCP_ACKVEC_STATE_MASK 0xC0 /* 11000000 */
|
|
#define DCCP_ACKVEC_LEN_MASK 0x3F /* 00111111 */
|
|
|
|
/** struct dccp_ackvec - ack vector
|
|
*
|
|
* This data structure is the one defined in RFC 4340, Appendix A.
|
|
*
|
|
* @av_buf_head - circular buffer head
|
|
* @av_buf_tail - circular buffer tail
|
|
* @av_buf_ackno - ack # of the most recent packet acknowledgeable in the
|
|
* buffer (i.e. %av_buf_head)
|
|
* @av_buf_nonce - the one-bit sum of the ECN Nonces on all packets acked
|
|
* by the buffer with State 0
|
|
*
|
|
* Additionally, the HC-Receiver must keep some information about the
|
|
* Ack Vectors it has recently sent. For each packet sent carrying an
|
|
* Ack Vector, it remembers four variables:
|
|
*
|
|
* @av_records - list of dccp_ackvec_record
|
|
* @av_ack_nonce - the one-bit sum of the ECN Nonces for all State 0.
|
|
*
|
|
* @av_time - the time in usecs
|
|
* @av_buf - circular buffer of acknowledgeable packets
|
|
*/
|
|
struct dccp_ackvec {
|
|
u64 av_buf_ackno;
|
|
struct list_head av_records;
|
|
ktime_t av_time;
|
|
u16 av_buf_head;
|
|
u16 av_vec_len;
|
|
u8 av_buf_nonce;
|
|
u8 av_ack_nonce;
|
|
u8 av_buf[DCCP_MAX_ACKVEC_LEN];
|
|
};
|
|
|
|
/** struct dccp_ackvec_record - ack vector record
|
|
*
|
|
* ACK vector record as defined in Appendix A of spec.
|
|
*
|
|
* The list is sorted by avr_ack_seqno
|
|
*
|
|
* @avr_node - node in av_records
|
|
* @avr_ack_seqno - sequence number of the packet this record was sent on
|
|
* @avr_ack_ackno - sequence number being acknowledged
|
|
* @avr_ack_ptr - pointer into av_buf where this record starts
|
|
* @avr_ack_nonce - av_ack_nonce at the time this record was sent
|
|
* @avr_sent_len - lenght of the record in av_buf
|
|
*/
|
|
struct dccp_ackvec_record {
|
|
struct list_head avr_node;
|
|
u64 avr_ack_seqno;
|
|
u64 avr_ack_ackno;
|
|
u16 avr_ack_ptr;
|
|
u16 avr_sent_len;
|
|
u8 avr_ack_nonce;
|
|
};
|
|
|
|
struct sock;
|
|
struct sk_buff;
|
|
|
|
extern int dccp_ackvec_init(void);
|
|
extern void dccp_ackvec_exit(void);
|
|
|
|
extern struct dccp_ackvec *dccp_ackvec_alloc(const gfp_t priority);
|
|
extern void dccp_ackvec_free(struct dccp_ackvec *av);
|
|
|
|
extern int dccp_ackvec_add(struct dccp_ackvec *av, const struct sock *sk,
|
|
const u64 ackno, const u8 state);
|
|
|
|
extern void dccp_ackvec_check_rcv_ackno(struct dccp_ackvec *av,
|
|
struct sock *sk, const u64 ackno);
|
|
extern int dccp_ackvec_parse(struct sock *sk, const struct sk_buff *skb,
|
|
u64 *ackno, const u8 opt,
|
|
const u8 *value, const u8 len);
|
|
|
|
extern int dccp_insert_option_ackvec(struct sock *sk, struct sk_buff *skb);
|
|
|
|
static inline int dccp_ackvec_pending(const struct dccp_ackvec *av)
|
|
{
|
|
return av->av_vec_len;
|
|
}
|
|
#endif /* _ACKVEC_H */
|