linux-kernel-test/net/dccp/ackvec.c
Gerrit Renker fade756f18 dccp: Set per-connection CCIDs via socket options
With this patch, TX/RX CCIDs can now be changed on a per-connection basis, which
overrides the defaults set by the global sysctl variables for TX/RX CCIDs.

To make full use of this facility, the remaining patches of this patch set are
needed, which track dependencies and activate negotiated feature values.

Note on the maximum number of CCIDs that can be registered:
-----------------------------------------------------------
The maximum number of CCIDs that can be registered on the socket is constrained
by the space in a Confirm/Change feature negotiation option. 

The space in these in turn depends on the size of header options as defined
in RFC 4340, 5.8. Since this is a recurring constant, it has been moved from
ackvec.h into linux/dccp.h, clarifying its purpose.

Relative to this size, the maximum number of CCID identifiers that can be 
present in a Confirm option (which always consumes 1 byte more than a Change
option, cf. 6.1) is 2 bytes less than the maximum TLV size: one for the
CCID-feature-type and one for the selected value.

Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
2008-09-04 07:45:28 +02:00

479 lines
13 KiB
C

/*
* 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/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 u8 nr_opts = DIV_ROUND_UP(av->av_vec_len, DCCP_SINGLE_OPT_MAXLEN);
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_SINGLE_OPT_MAXLEN)
copylen = DCCP_SINGLE_OPT_MAXLEN;
*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_SINGLE_OPT_MAXLEN)
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;
}
}