/*
* 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/skbuff.h>
#include <net/sock.h>
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;
int len = av->dccpav_vec_len + 2;
struct timeval now;
u32 elapsed_time;
unsigned char *to, *from;
dccp_timestamp(sk, &now);
elapsed_time = timeval_delta(&now, &av->dccpav_time) / 10;
if (elapsed_time != 0)
dccp_insert_option_elapsed_time(sk, skb, elapsed_time);
if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN)
return -1;
/*
* XXX: now we have just one ack vector sent record, so
* we have to wait for it to be cleared.
*
* Of course this is not acceptable, but this is just for
* basic testing now.
*/
if (av->dccpav_ack_seqno != DCCP_MAX_SEQNO + 1)
return -1;
DCCP_SKB_CB(skb)->dccpd_opt_len += len;
to = skb_push(skb, len);
*to++ = DCCPO_ACK_VECTOR_0;
*to++ = len;
len = av->dccpav_vec_len;
from = av->dccpav_buf + av->dccpav_buf_head;
/* Check if buf_head wraps */
if (av->dccpav_buf_head + len > av->dccpav_vec_len) {
const u32 tailsize = (av->dccpav_vec_len - av->dccpav_buf_head);
memcpy(to, from, tailsize);
to += tailsize;
len -= tailsize;
from = av->dccpav_buf;
}
memcpy(to, from, len);
/*
* From draft-ietf-dccp-spec-11.txt:
*
* 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.
*
* This implemention uses just one ack record for now.
*/
av->dccpav_ack_seqno = DCCP_SKB_CB(skb)->dccpd_seq;
av->dccpav_ack_ptr = av->dccpav_buf_head;
av->dccpav_ack_ackno = av->dccpav_buf_ackno;
av->dccpav_ack_nonce = av->dccpav_buf_nonce;
av->dccpav_sent_len = av->dccpav_vec_len;
dccp_pr_debug("%sACK Vector 0, len=%d, ack_seqno=%llu, "
"ack_ackno=%llu\n",
debug_prefix, av->dccpav_sent_len,
(unsigned long long)av->dccpav_ack_seqno,
(unsigned long long)av->dccpav_ack_ackno);
return -1;
}
struct dccp_ackvec *dccp_ackvec_alloc(const unsigned int len,
const unsigned int __nocast priority)
{
struct dccp_ackvec *av = kmalloc(sizeof(*av) + len, priority);
if (av != NULL) {
av->dccpav_buf_len = len;
av->dccpav_buf_head =
av->dccpav_buf_tail = av->dccpav_buf_len - 1;
av->dccpav_buf_ackno =
av->dccpav_ack_ackno = av->dccpav_ack_seqno = ~0LLU;
av->dccpav_buf_nonce = av->dccpav_buf_nonce = 0;
av->dccpav_ack_ptr = 0;
av->dccpav_time.tv_sec = 0;
av->dccpav_time.tv_usec = 0;
av->dccpav_sent_len = av->dccpav_vec_len = 0;
}
return av;
}
void dccp_ackvec_free(struct dccp_ackvec *av)
{
kfree(av);
}
static inline u8 dccp_ackvec_state(const struct dccp_ackvec *av,
const unsigned int index)
{
return av->dccpav_buf[index] & DCCP_ACKVEC_STATE_MASK;
}
static inline u8 dccp_ackvec_len(const struct dccp_ackvec *av,
const unsigned int index)
{
return av->dccpav_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;
signed long new_head;
if (av->dccpav_vec_len + packets > av->dccpav_buf_len)
return -ENOBUFS;
gap = packets - 1;
new_head = av->dccpav_buf_head - packets;
if (new_head < 0) {
if (gap > 0) {
memset(av->dccpav_buf, DCCP_ACKVEC_STATE_NOT_RECEIVED,
gap + new_head + 1);
gap = -new_head;
}
new_head += av->dccpav_buf_len;
}
av->dccpav_buf_head = new_head;
if (gap > 0)
memset(av->dccpav_buf + av->dccpav_buf_head + 1,
DCCP_ACKVEC_STATE_NOT_RECEIVED, gap);
av->dccpav_buf[av->dccpav_buf_head] = state;
av->dccpav_vec_len += packets;
return 0;
}
/*
* Implements the draft-ietf-dccp-spec-11.txt 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 dccpav_buf.
*
* We may well decide to do buffer compression, etc, but for now lets
* just drop.
*
* From Appendix A:
*
* 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->dccpav_vec_len == 0) {
av->dccpav_buf[av->dccpav_buf_head] = state;
av->dccpav_vec_len = 1;
} else if (after48(ackno, av->dccpav_buf_ackno)) {
const u64 delta = dccp_delta_seqno(av->dccpav_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->dccpav_buf_head) == state &&
(dccp_ackvec_len(av, av->dccpav_buf_head) <
DCCP_ACKVEC_LEN_MASK))
av->dccpav_buf[av->dccpav_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 arrives, and
* S <= buf_ackno, 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->dccpav_buf_ackno);
unsigned int index = av->dccpav_buf_head;
while (1) {
const u8 len = dccp_ackvec_len(av, index);
const u8 state = dccp_ackvec_state(av, index);
/*
* valid packets not yet in dccpav_buf have a reserved
* entry, with a len equal to 0.
*/
if (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->dccpav_buf[index] = state;
goto out;
}
/* len == 0 means one packet */
if (delta < len + 1)
goto out_duplicate;
delta -= len + 1;
if (++index == av->dccpav_buf_len)
index = 0;
}
}
av->dccpav_buf_ackno = ackno;
dccp_timestamp(sk, &av->dccpav_time);
out:
dccp_pr_debug("");
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;
}
#ifdef CONFIG_IP_DCCP_DEBUG
void dccp_ackvector_print(const u64 ackno, const unsigned char *vector, int len)
{
if (!dccp_debug)
return;
printk("ACK vector len=%d, ackno=%llu |", len,
(unsigned long long)ackno);
while (len--) {
const u8 state = (*vector & DCCP_ACKVEC_STATE_MASK) >> 6;
const u8 rl = *vector & DCCP_ACKVEC_LEN_MASK;
printk("%d,%d|", state, rl);
++vector;
}
printk("\n");
}
void dccp_ackvec_print(const struct dccp_ackvec *av)
{
dccp_ackvector_print(av->dccpav_buf_ackno,
av->dccpav_buf + av->dccpav_buf_head,
av->dccpav_vec_len);
}
#endif
static void dccp_ackvec_trow_away_ack_record(struct dccp_ackvec *av)
{
/*
* As we're keeping track of the ack vector size (dccpav_vec_len) and
* the sent ack vector size (dccpav_sent_len) we don't need
* dccpav_buf_tail at all, but keep this code here as in the future
* we'll implement a vector of ack records, as suggested in
* draft-ietf-dccp-spec-11.txt Appendix A. -acme
*/
#if 0
av->dccpav_buf_tail = av->dccpav_ack_ptr + 1;
if (av->dccpav_buf_tail >= av->dccpav_vec_len)
av->dccpav_buf_tail -= av->dccpav_vec_len;
#endif
av->dccpav_vec_len -= av->dccpav_sent_len;
}
void dccp_ackvec_check_rcv_ackno(struct dccp_ackvec *av, struct sock *sk,
const u64 ackno)
{
/* Check if we actually sent an ACK vector */
if (av->dccpav_ack_seqno == DCCP_MAX_SEQNO + 1)
return;
if (ackno == av->dccpav_ack_seqno) {
#ifdef CONFIG_IP_DCCP_DEBUG
struct dccp_sock *dp = dccp_sk(sk);
const char *debug_prefix = dp->dccps_role == DCCP_ROLE_CLIENT ?
"CLIENT rx ack: " : "server rx ack: ";
#endif
dccp_pr_debug("%sACK packet 0, len=%d, ack_seqno=%llu, "
"ack_ackno=%llu, ACKED!\n",
debug_prefix, 1,
(unsigned long long)av->dccpav_ack_seqno,
(unsigned long long)av->dccpav_ack_ackno);
dccp_ackvec_trow_away_ack_record(av);
av->dccpav_ack_seqno = DCCP_MAX_SEQNO + 1;
}
}
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;
/* Check if we actually sent an ACK vector */
if (av->dccpav_ack_seqno == DCCP_MAX_SEQNO + 1)
return;
/*
* We're in the receiver half connection, so if the received an ACK
* vector ackno (e.g. 50) before dccpav_ack_seqno (e.g. 52), we're
* not interested.
*
* Extra explanation with example:
*
* if we received an ACK vector with ackno 50, it can only be acking
* 50, 49, 48, etc, not 52 (the seqno for the ACK vector we sent).
*/
/* dccp_pr_debug("is %llu < %llu? ", ackno, av->dccpav_ack_seqno); */
if (before48(ackno, av->dccpav_ack_seqno)) {
/* dccp_pr_debug_cat("yes\n"); */
return;
}
/* dccp_pr_debug_cat("no\n"); */
i = len;
while (i--) {
const u8 rl = *vector & DCCP_ACKVEC_LEN_MASK;
u64 ackno_end_rl;
dccp_set_seqno(&ackno_end_rl, ackno - rl);
/*
* dccp_pr_debug("is %llu <= %llu <= %llu? ", ackno_end_rl,
* av->dccpav_ack_seqno, ackno);
*/
if (between48(av->dccpav_ack_seqno, ackno_end_rl, ackno)) {
const u8 state = (*vector &
DCCP_ACKVEC_STATE_MASK) >> 6;
/* dccp_pr_debug_cat("yes\n"); */
if (state != DCCP_ACKVEC_STATE_NOT_RECEIVED) {
#ifdef CONFIG_IP_DCCP_DEBUG
struct dccp_sock *dp = dccp_sk(sk);
const char *debug_prefix =
dp->dccps_role == DCCP_ROLE_CLIENT ?
"CLIENT rx ack: " : "server rx ack: ";
#endif
dccp_pr_debug("%sACK vector 0, len=%d, "
"ack_seqno=%llu, ack_ackno=%llu, "
"ACKED!\n",
debug_prefix, len,
(unsigned long long)
av->dccpav_ack_seqno,
(unsigned long long)
av->dccpav_ack_ackno);
dccp_ackvec_trow_away_ack_record(av);
}
/*
* If dccpav_ack_seqno was not received, no problem
* we'll send another ACK vector.
*/
av->dccpav_ack_seqno = DCCP_MAX_SEQNO + 1;
break;
}
/* dccp_pr_debug_cat("no\n"); */
dccp_set_seqno(&ackno, ackno_end_rl - 1);
++vector;
}
}
int dccp_ackvec_parse(struct sock *sk, const struct sk_buff *skb,
const u8 opt, const u8 *value, const u8 len)
{
if (len > DCCP_MAX_ACKVEC_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,
DCCP_SKB_CB(skb)->dccpd_ack_seq,
len, value);
return 0;
}
