linux/net/dccp/ackvec.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 *  net/dccp/ackvec.c
 *
 *  An implementation of Ack Vectors for the DCCP protocol
 *  Copyright (c) 2007 University of Aberdeen, Scotland, UK
 *  Copyright (c) 2005 Arnaldo Carvalho de Melo <[email protected]>
 */
#include "dccp.h"
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/export.h>

static struct kmem_cache *dccp_ackvec_slab;
static struct kmem_cache *dccp_ackvec_record_slab;

struct dccp_ackvec *dccp_ackvec_alloc(const gfp_t priority)
{ … }

static void dccp_ackvec_purge_records(struct dccp_ackvec *av)
{ … }

void dccp_ackvec_free(struct dccp_ackvec *av)
{ … }

/**
 * dccp_ackvec_update_records  -  Record information about sent Ack Vectors
 * @av:		Ack Vector records to update
 * @seqno:	Sequence number of the packet carrying the Ack Vector just sent
 * @nonce_sum:	The sum of all buffer nonces contained in the Ack Vector
 */
int dccp_ackvec_update_records(struct dccp_ackvec *av, u64 seqno, u8 nonce_sum)
{ … }

static struct dccp_ackvec_record *dccp_ackvec_lookup(struct list_head *av_list,
						     const u64 ackno)
{ … }

/*
 * Buffer index and length computation using modulo-buffersize arithmetic.
 * Note that, as pointers move from right to left, head is `before' tail.
 */
static inline u16 __ackvec_idx_add(const u16 a, const u16 b)
{ … }

static inline u16 __ackvec_idx_sub(const u16 a, const u16 b)
{ … }

u16 dccp_ackvec_buflen(const struct dccp_ackvec *av)
{ … }

/**
 * dccp_ackvec_update_old  -  Update previous state as per RFC 4340, 11.4.1
 * @av:		non-empty buffer to update
 * @distance:   negative or zero distance of @seqno from buf_ackno downward
 * @seqno:	the (old) sequence number whose record is to be updated
 * @state:	state in which packet carrying @seqno was received
 */
static void dccp_ackvec_update_old(struct dccp_ackvec *av, s64 distance,
				   u64 seqno, enum dccp_ackvec_states state)
{ … }

/* Mark @num entries after buf_head as "Not yet received". */
static void dccp_ackvec_reserve_seats(struct dccp_ackvec *av, u16 num)
{ … }

/**
 * dccp_ackvec_add_new  -  Record one or more new entries in Ack Vector buffer
 * @av:		 container of buffer to update (can be empty or non-empty)
 * @num_packets: number of packets to register (must be >= 1)
 * @seqno:	 sequence number of the first packet in @num_packets
 * @state:	 state in which packet carrying @seqno was received
 */
static void dccp_ackvec_add_new(struct dccp_ackvec *av, u32 num_packets,
				u64 seqno, enum dccp_ackvec_states state)
{ … }

/**
 * dccp_ackvec_input  -  Register incoming packet in the buffer
 * @av: Ack Vector to register packet to
 * @skb: Packet to register
 */
void dccp_ackvec_input(struct dccp_ackvec *av, struct sk_buff *skb)
{ … }

/**
 * dccp_ackvec_clear_state  -  Perform house-keeping / garbage-collection
 * @av: Ack Vector record to clean
 * @ackno: last Ack Vector which has been acknowledged
 *
 * This routine is called when the peer acknowledges the receipt of Ack Vectors
 * up to and including @ackno. While based on section A.3 of RFC 4340, here
 * are additional precautions to prevent corrupted buffer state. In particular,
 * we use tail_ackno to identify outdated records; it always marks the earliest
 * packet of group (2) in 11.4.2.
 */
void dccp_ackvec_clear_state(struct dccp_ackvec *av, const u64 ackno)
{ … }

/*
 *	Routines to keep track of Ack Vectors received in an skb
 */
int dccp_ackvec_parsed_add(struct list_head *head, u8 *vec, u8 len, u8 nonce)
{ … }
EXPORT_SYMBOL_GPL(…);

void dccp_ackvec_parsed_cleanup(struct list_head *parsed_chunks)
{ … }
EXPORT_SYMBOL_GPL(…);

int __init dccp_ackvec_init(void)
{ … }

void dccp_ackvec_exit(void)
{ … }