/* [<][>][^][v][top][bottom][index][help] */
DEFINITIONS
This source file includes following definitions.
- dccp_ackvec_record_new
- dccp_ackvec_record_delete
- dccp_ackvec_insert_avr
- dccp_insert_option_ackvec
- dccp_ackvec_alloc
- dccp_ackvec_free
- dccp_ackvec_state
- dccp_ackvec_len
- dccp_ackvec_set_buf_head_state
- dccp_ackvec_add
- dccp_ackvec_throw_record
- dccp_ackvec_check_rcv_ackno
- dccp_ackvec_check_rcv_ackvector
- dccp_ackvec_parse
- dccp_ackvec_init
- dccp_ackvec_exit
/*
* net/dccp/ackvec.c
*
* An implementation of the DCCP protocol
* Copyright (c) 2005 Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the
* Free Software Foundation; version 2 of the License;
*/
#include "ackvec.h"
#include "dccp.h"
#include <linux/dccp.h>
#include <linux/init.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/skbuff.h>
#include <linux/slab.h>
#include <net/sock.h>
static struct kmem_cache *dccp_ackvec_slab;
static struct kmem_cache *dccp_ackvec_record_slab;
static struct dccp_ackvec_record *dccp_ackvec_record_new(void)
{
struct dccp_ackvec_record *avr =
kmem_cache_alloc(dccp_ackvec_record_slab, GFP_ATOMIC);
if (avr != NULL)
INIT_LIST_HEAD(&avr->avr_node);
return avr;
}
static void dccp_ackvec_record_delete(struct dccp_ackvec_record *avr)
{
if (unlikely(avr == NULL))
return;
/* Check if deleting a linked record */
WARN_ON(!list_empty(&avr->avr_node));
kmem_cache_free(dccp_ackvec_record_slab, avr);
}
static void dccp_ackvec_insert_avr(struct dccp_ackvec *av,
struct dccp_ackvec_record *avr)
{
/*
* AVRs are sorted by seqno. Since we are sending them in order, we
* just add the AVR at the head of the list.
* -sorbo.
*/
if (!list_empty(&av->av_records)) {
const struct dccp_ackvec_record *head =
list_entry(av->av_records.next,
struct dccp_ackvec_record,
avr_node);
BUG_ON(before48(avr->avr_ack_seqno, head->avr_ack_seqno));
}
list_add(&avr->avr_node, &av->av_records);
}
int dccp_insert_option_ackvec(struct sock *sk, struct sk_buff *skb)
{
struct dccp_sock *dp = dccp_sk(sk);
struct dccp_ackvec *av = dp->dccps_hc_rx_ackvec;
/* Figure out how many options do we need to represent the ackvec */
const u16 nr_opts = DIV_ROUND_UP(av->av_vec_len, DCCP_MAX_ACKVEC_OPT_LEN);
u16 len = av->av_vec_len + 2 * nr_opts, i;
u32 elapsed_time;
const unsigned char *tail, *from;
unsigned char *to;
struct dccp_ackvec_record *avr;
suseconds_t delta;
if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN)
return -1;
delta = ktime_us_delta(ktime_get_real(), av->av_time);
elapsed_time = delta / 10;
if (elapsed_time != 0 &&
dccp_insert_option_elapsed_time(sk, skb, elapsed_time))
return -1;
avr = dccp_ackvec_record_new();
if (avr == NULL)
return -1;
DCCP_SKB_CB(skb)->dccpd_opt_len += len;
to = skb_push(skb, len);
len = av->av_vec_len;
from = av->av_buf + av->av_buf_head;
tail = av->av_buf + DCCP_MAX_ACKVEC_LEN;
for (i = 0; i < nr_opts; ++i) {
int copylen = len;
if (len > DCCP_MAX_ACKVEC_OPT_LEN)
copylen = DCCP_MAX_ACKVEC_OPT_LEN;
*to++ = DCCPO_ACK_VECTOR_0;
*to++ = copylen + 2;
/* Check if buf_head wraps */
if (from + copylen > tail) {
const u16 tailsize = tail - from;
memcpy(to, from, tailsize);
to += tailsize;
len -= tailsize;
copylen -= tailsize;
from = av->av_buf;
}
memcpy(to, from, copylen);
from += copylen;
to += copylen;
len -= copylen;
}
/*
* From RFC 4340, A.2:
*
* For each acknowledgement it sends, the HC-Receiver will add an
* acknowledgement record. ack_seqno will equal the HC-Receiver
* sequence number it used for the ack packet; ack_ptr will equal
* buf_head; ack_ackno will equal buf_ackno; and ack_nonce will
* equal buf_nonce.
*/
avr->avr_ack_seqno = DCCP_SKB_CB(skb)->dccpd_seq;
avr->avr_ack_ptr = av->av_buf_head;
avr->avr_ack_ackno = av->av_buf_ackno;
avr->avr_ack_nonce = av->av_buf_nonce;
avr->avr_sent_len = av->av_vec_len;
dccp_ackvec_insert_avr(av, avr);
dccp_pr_debug("%s ACK Vector 0, len=%d, ack_seqno=%llu, "
"ack_ackno=%llu\n",
dccp_role(sk), avr->avr_sent_len,
(unsigned long long)avr->avr_ack_seqno,
(unsigned long long)avr->avr_ack_ackno);
return 0;
}
struct dccp_ackvec *dccp_ackvec_alloc(const gfp_t priority)
{
struct dccp_ackvec *av = kmem_cache_alloc(dccp_ackvec_slab, priority);
if (av != NULL) {
av->av_buf_head = DCCP_MAX_ACKVEC_LEN - 1;
av->av_buf_ackno = UINT48_MAX + 1;
av->av_buf_nonce = 0;
av->av_time = ktime_set(0, 0);
av->av_vec_len = 0;
INIT_LIST_HEAD(&av->av_records);
}
return av;
}
void dccp_ackvec_free(struct dccp_ackvec *av)
{
if (unlikely(av == NULL))
return;
if (!list_empty(&av->av_records)) {
struct dccp_ackvec_record *avr, *next;
list_for_each_entry_safe(avr, next, &av->av_records, avr_node) {
list_del_init(&avr->avr_node);
dccp_ackvec_record_delete(avr);
}
}
kmem_cache_free(dccp_ackvec_slab, av);
}
static inline u8 dccp_ackvec_state(const struct dccp_ackvec *av,
const u32 index)
{
return av->av_buf[index] & DCCP_ACKVEC_STATE_MASK;
}
static inline u8 dccp_ackvec_len(const struct dccp_ackvec *av,
const u32 index)
{
return av->av_buf[index] & DCCP_ACKVEC_LEN_MASK;
}
/*
* If several packets are missing, the HC-Receiver may prefer to enter multiple
* bytes with run length 0, rather than a single byte with a larger run length;
* this simplifies table updates if one of the missing packets arrives.
*/
static inline int dccp_ackvec_set_buf_head_state(struct dccp_ackvec *av,
const unsigned int packets,
const unsigned char state)
{
unsigned int gap;
long new_head;
if (av->av_vec_len + packets > DCCP_MAX_ACKVEC_LEN)
return -ENOBUFS;
gap = packets - 1;
new_head = av->av_buf_head - packets;
if (new_head < 0) {
if (gap > 0) {
memset(av->av_buf, DCCP_ACKVEC_STATE_NOT_RECEIVED,
gap + new_head + 1);
gap = -new_head;
}
new_head += DCCP_MAX_ACKVEC_LEN;
}
av->av_buf_head = new_head;
if (gap > 0)
memset(av->av_buf + av->av_buf_head + 1,
DCCP_ACKVEC_STATE_NOT_RECEIVED, gap);
av->av_buf[av->av_buf_head] = state;
av->av_vec_len += packets;
return 0;
}
/*
* Implements the RFC 4340, Appendix A
*/
int dccp_ackvec_add(struct dccp_ackvec *av, const struct sock *sk,
const u64 ackno, const u8 state)
{
/*
* Check at the right places if the buffer is full, if it is, tell the
* caller to start dropping packets till the HC-Sender acks our ACK
* vectors, when we will free up space in av_buf.
*
* We may well decide to do buffer compression, etc, but for now lets
* just drop.
*
* From Appendix A.1.1 (`New Packets'):
*
* Of course, the circular buffer may overflow, either when the
* HC-Sender is sending data at a very high rate, when the
* HC-Receiver's acknowledgements are not reaching the HC-Sender,
* or when the HC-Sender is forgetting to acknowledge those acks
* (so the HC-Receiver is unable to clean up old state). In this
* case, the HC-Receiver should either compress the buffer (by
* increasing run lengths when possible), transfer its state to
* a larger buffer, or, as a last resort, drop all received
* packets, without processing them whatsoever, until its buffer
* shrinks again.
*/
/* See if this is the first ackno being inserted */
if (av->av_vec_len == 0) {
av->av_buf[av->av_buf_head] = state;
av->av_vec_len = 1;
} else if (after48(ackno, av->av_buf_ackno)) {
const u64 delta = dccp_delta_seqno(av->av_buf_ackno, ackno);
/*
* Look if the state of this packet is the same as the
* previous ackno and if so if we can bump the head len.
*/
if (delta == 1 &&
dccp_ackvec_state(av, av->av_buf_head) == state &&
dccp_ackvec_len(av, av->av_buf_head) < DCCP_ACKVEC_LEN_MASK)
av->av_buf[av->av_buf_head]++;
else if (dccp_ackvec_set_buf_head_state(av, delta, state))
return -ENOBUFS;
} else {
/*
* A.1.2. Old Packets
*
* When a packet with Sequence Number S <= buf_ackno
* arrives, the HC-Receiver will scan the table for
* the byte corresponding to S. (Indexing structures
* could reduce the complexity of this scan.)
*/
u64 delta = dccp_delta_seqno(ackno, av->av_buf_ackno);
u32 index = av->av_buf_head;
while (1) {
const u8 len = dccp_ackvec_len(av, index);
const u8 av_state = dccp_ackvec_state(av, index);
/*
* valid packets not yet in av_buf have a reserved
* entry, with a len equal to 0.
*/
if (av_state == DCCP_ACKVEC_STATE_NOT_RECEIVED &&
len == 0 && delta == 0) { /* Found our
reserved seat! */
dccp_pr_debug("Found %llu reserved seat!\n",
(unsigned long long)ackno);
av->av_buf[index] = state;
goto out;
}
/* len == 0 means one packet */
if (delta < len + 1)
goto out_duplicate;
delta -= len + 1;
if (++index == DCCP_MAX_ACKVEC_LEN)
index = 0;
}
}
av->av_buf_ackno = ackno;
av->av_time = ktime_get_real();
out:
return 0;
out_duplicate:
/* Duplicate packet */
dccp_pr_debug("Received a dup or already considered lost "
"packet: %llu\n", (unsigned long long)ackno);
return -EILSEQ;
}
static void dccp_ackvec_throw_record(struct dccp_ackvec *av,
struct dccp_ackvec_record *avr)
{
struct dccp_ackvec_record *next;
/* sort out vector length */
if (av->av_buf_head <= avr->avr_ack_ptr)
av->av_vec_len = avr->avr_ack_ptr - av->av_buf_head;
else
av->av_vec_len = DCCP_MAX_ACKVEC_LEN - 1 -
av->av_buf_head + avr->avr_ack_ptr;
/* free records */
list_for_each_entry_safe_from(avr, next, &av->av_records, avr_node) {
list_del_init(&avr->avr_node);
dccp_ackvec_record_delete(avr);
}
}
void dccp_ackvec_check_rcv_ackno(struct dccp_ackvec *av, struct sock *sk,
const u64 ackno)
{
struct dccp_ackvec_record *avr;
/*
* If we traverse backwards, it should be faster when we have large
* windows. We will be receiving ACKs for stuff we sent a while back
* -sorbo.
*/
list_for_each_entry_reverse(avr, &av->av_records, avr_node) {
if (ackno == avr->avr_ack_seqno) {
dccp_pr_debug("%s ACK packet 0, len=%d, ack_seqno=%llu, "
"ack_ackno=%llu, ACKED!\n",
dccp_role(sk), 1,
(unsigned long long)avr->avr_ack_seqno,
(unsigned long long)avr->avr_ack_ackno);
dccp_ackvec_throw_record(av, avr);
break;
} else if (avr->avr_ack_seqno > ackno)
break; /* old news */
}
}
static void dccp_ackvec_check_rcv_ackvector(struct dccp_ackvec *av,
struct sock *sk, u64 *ackno,
const unsigned char len,
const unsigned char *vector)
{
unsigned char i;
struct dccp_ackvec_record *avr;
/* Check if we actually sent an ACK vector */
if (list_empty(&av->av_records))
return;
i = len;
/*
* XXX
* I think it might be more efficient to work backwards. See comment on
* rcv_ackno. -sorbo.
*/
avr = list_entry(av->av_records.next, struct dccp_ackvec_record, avr_node);
while (i--) {
const u8 rl = *vector & DCCP_ACKVEC_LEN_MASK;
u64 ackno_end_rl;
dccp_set_seqno(&ackno_end_rl, *ackno - rl);
/*
* If our AVR sequence number is greater than the ack, go
* forward in the AVR list until it is not so.
*/
list_for_each_entry_from(avr, &av->av_records, avr_node) {
if (!after48(avr->avr_ack_seqno, *ackno))
goto found;
}
/* End of the av_records list, not found, exit */
break;
found:
if (between48(avr->avr_ack_seqno, ackno_end_rl, *ackno)) {
const u8 state = *vector & DCCP_ACKVEC_STATE_MASK;
if (state != DCCP_ACKVEC_STATE_NOT_RECEIVED) {
dccp_pr_debug("%s ACK vector 0, len=%d, "
"ack_seqno=%llu, ack_ackno=%llu, "
"ACKED!\n",
dccp_role(sk), len,
(unsigned long long)
avr->avr_ack_seqno,
(unsigned long long)
avr->avr_ack_ackno);
dccp_ackvec_throw_record(av, avr);
break;
}
/*
* If it wasn't received, continue scanning... we might
* find another one.
*/
}
dccp_set_seqno(ackno, ackno_end_rl - 1);
++vector;
}
}
int dccp_ackvec_parse(struct sock *sk, const struct sk_buff *skb,
u64 *ackno, const u8 opt, const u8 *value, const u8 len)
{
if (len > DCCP_MAX_ACKVEC_OPT_LEN)
return -1;
/* dccp_ackvector_print(DCCP_SKB_CB(skb)->dccpd_ack_seq, value, len); */
dccp_ackvec_check_rcv_ackvector(dccp_sk(sk)->dccps_hc_rx_ackvec, sk,
ackno, len, value);
return 0;
}
int __init dccp_ackvec_init(void)
{
dccp_ackvec_slab = kmem_cache_create("dccp_ackvec",
sizeof(struct dccp_ackvec), 0,
SLAB_HWCACHE_ALIGN, NULL);
if (dccp_ackvec_slab == NULL)
goto out_err;
dccp_ackvec_record_slab =
kmem_cache_create("dccp_ackvec_record",
sizeof(struct dccp_ackvec_record),
0, SLAB_HWCACHE_ALIGN, NULL);
if (dccp_ackvec_record_slab == NULL)
goto out_destroy_slab;
return 0;
out_destroy_slab:
kmem_cache_destroy(dccp_ackvec_slab);
dccp_ackvec_slab = NULL;
out_err:
DCCP_CRIT("Unable to create Ack Vector slab cache");
return -ENOBUFS;
}
void dccp_ackvec_exit(void)
{
if (dccp_ackvec_slab != NULL) {
kmem_cache_destroy(dccp_ackvec_slab);
dccp_ackvec_slab = NULL;
}
if (dccp_ackvec_record_slab != NULL) {
kmem_cache_destroy(dccp_ackvec_record_slab);
dccp_ackvec_record_slab = NULL;
}
}