1
linux/net/dccp/ccids/ccid3.c
Gerrit Renker 9d497a2c91 dccp ccid-3: Implement rfc3448bis change to initial-rate computation
The patch updates CCID-3 with regard to the latest rfc3448bis-06: 
 * in the first revisions of the draft, MSS was used for the RFC 3390 window; 
 * then (from revision #1 to revision #2), it used the packet size `s';
 * now, in this revision (and apparently final), the value is back to MSS.

This change has an implication for the case when no RTT sample is available,
at the time of sending the first packet:

 * with RTT sample, 2*MSS/RTT <= initial_rate <= 4*MSS/RTT;
 * without RTT sample, the initial rate is one packet (s bytes) per second
   (sec. 4.2), but using s instead of MSS here creates an imbalance, since
   this would further reduce the initial sending rate.

Hence the patch uses MSS (called MPS in RFC 4340) in all places.

Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
2008-09-04 07:45:42 +02:00

786 lines
23 KiB
C

/*
* net/dccp/ccids/ccid3.c
*
* Copyright (c) 2007 The University of Aberdeen, Scotland, UK
* Copyright (c) 2005-7 The University of Waikato, Hamilton, New Zealand.
* Copyright (c) 2005-7 Ian McDonald <ian.mcdonald@jandi.co.nz>
*
* An implementation of the DCCP protocol
*
* This code has been developed by the University of Waikato WAND
* research group. For further information please see http://www.wand.net.nz/
*
* This code also uses code from Lulea University, rereleased as GPL by its
* authors:
* Copyright (c) 2003 Nils-Erik Mattsson, Joacim Haggmark, Magnus Erixzon
*
* Changes to meet Linux coding standards, to make it meet latest ccid3 draft
* and to make it work as a loadable module in the DCCP stack written by
* Arnaldo Carvalho de Melo <acme@conectiva.com.br>.
*
* Copyright (c) 2005 Arnaldo Carvalho de Melo <acme@conectiva.com.br>
*
* 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; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include "../dccp.h"
#include "ccid3.h"
#include <asm/unaligned.h>
#ifdef CONFIG_IP_DCCP_CCID3_DEBUG
static int ccid3_debug;
#define ccid3_pr_debug(format, a...) DCCP_PR_DEBUG(ccid3_debug, format, ##a)
#else
#define ccid3_pr_debug(format, a...)
#endif
/*
* Transmitter Half-Connection Routines
*/
/*
* Compute the initial sending rate X_init in the manner of RFC 3390:
*
* X_init = min(4 * MPS, max(2 * MPS, 4380 bytes)) / RTT
*
* For consistency with other parts of the code, X_init is scaled by 2^6.
*/
static inline u64 rfc3390_initial_rate(struct sock *sk)
{
const u32 mps = dccp_sk(sk)->dccps_mss_cache,
w_init = clamp(4380U, 2 * mps, 4 * mps);
return scaled_div(w_init << 6, ccid3_hc_tx_sk(sk)->rtt);
}
/**
* ccid3_update_send_interval - Calculate new t_ipi = s / X_inst
* This respects the granularity of X_inst (64 * bytes/second).
*/
static void ccid3_update_send_interval(struct ccid3_hc_tx_sock *hctx)
{
hctx->t_ipi = scaled_div32(((u64)hctx->s) << 6, hctx->x);
ccid3_pr_debug("t_ipi=%u, s=%u, X=%u\n", hctx->t_ipi,
hctx->s, (unsigned)(hctx->x >> 6));
}
static u32 ccid3_hc_tx_idle_rtt(struct ccid3_hc_tx_sock *hctx, ktime_t now)
{
u32 delta = ktime_us_delta(now, hctx->t_last_win_count);
return delta / hctx->rtt;
}
/**
* ccid3_hc_tx_update_x - Update allowed sending rate X
* @stamp: most recent time if available - can be left NULL.
* This function tracks draft rfc3448bis, check there for latest details.
*
* Note: X and X_recv are both stored in units of 64 * bytes/second, to support
* fine-grained resolution of sending rates. This requires scaling by 2^6
* throughout the code. Only X_calc is unscaled (in bytes/second).
*
*/
static void ccid3_hc_tx_update_x(struct sock *sk, ktime_t *stamp)
{
struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);
u64 min_rate = 2 * hctx->x_recv;
const u64 old_x = hctx->x;
ktime_t now = stamp ? *stamp : ktime_get_real();
/*
* Handle IDLE periods: do not reduce below RFC3390 initial sending rate
* when idling [RFC 4342, 5.1]. Definition of idling is from rfc3448bis:
* a sender is idle if it has not sent anything over a 2-RTT-period.
* For consistency with X and X_recv, min_rate is also scaled by 2^6.
*/
if (ccid3_hc_tx_idle_rtt(hctx, now) >= 2) {
min_rate = rfc3390_initial_rate(sk);
min_rate = max(min_rate, 2 * hctx->x_recv);
}
if (hctx->p > 0) {
hctx->x = min(((u64)hctx->x_calc) << 6, min_rate);
hctx->x = max(hctx->x, (((u64)hctx->s) << 6) / TFRC_T_MBI);
} else if (ktime_us_delta(now, hctx->t_ld) - (s64)hctx->rtt >= 0) {
hctx->x = min(2 * hctx->x, min_rate);
hctx->x = max(hctx->x,
scaled_div(((u64)hctx->s) << 6, hctx->rtt));
hctx->t_ld = now;
}
if (hctx->x != old_x) {
ccid3_pr_debug("X_prev=%u, X_now=%u, X_calc=%u, "
"X_recv=%u\n", (unsigned)(old_x >> 6),
(unsigned)(hctx->x >> 6), hctx->x_calc,
(unsigned)(hctx->x_recv >> 6));
ccid3_update_send_interval(hctx);
}
}
/*
* Track the mean packet size `s' (cf. RFC 4342, 5.3 and RFC 3448, 4.1)
* @len: DCCP packet payload size in bytes
*/
static inline void ccid3_hc_tx_update_s(struct ccid3_hc_tx_sock *hctx, int len)
{
const u16 old_s = hctx->s;
hctx->s = tfrc_ewma(hctx->s, len, 9);
if (hctx->s != old_s)
ccid3_update_send_interval(hctx);
}
/*
* Update Window Counter using the algorithm from [RFC 4342, 8.1].
* As elsewhere, RTT > 0 is assumed by using dccp_sample_rtt().
*/
static inline void ccid3_hc_tx_update_win_count(struct ccid3_hc_tx_sock *hctx,
ktime_t now)
{
u32 delta = ktime_us_delta(now, hctx->t_last_win_count),
quarter_rtts = (4 * delta) / hctx->rtt;
if (quarter_rtts > 0) {
hctx->t_last_win_count = now;
hctx->last_win_count += min(quarter_rtts, 5U);
hctx->last_win_count &= 0xF; /* mod 16 */
}
}
static void ccid3_hc_tx_no_feedback_timer(unsigned long data)
{
struct sock *sk = (struct sock *)data;
struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);
unsigned long t_nfb = USEC_PER_SEC / 5;
bh_lock_sock(sk);
if (sock_owned_by_user(sk)) {
/* Try again later. */
/* XXX: set some sensible MIB */
goto restart_timer;
}
ccid3_pr_debug("%s(%p) entry with%s feedback\n", dccp_role(sk), sk,
hctx->feedback ? "" : "out");
/* Ignore and do not restart after leaving the established state */
if ((1 << sk->sk_state) & ~(DCCPF_OPEN | DCCPF_PARTOPEN))
goto out;
/* Reset feedback state to "no feedback received" */
hctx->feedback = false;
/*
* Determine new allowed sending rate X as per draft rfc3448bis-00, 4.4
* RTO is 0 if and only if no feedback has been received yet.
*/
if (hctx->t_rto == 0 || hctx->p == 0) {
/* halve send rate directly */
hctx->x = max(hctx->x / 2, (((u64)hctx->s) << 6) / TFRC_T_MBI);
ccid3_update_send_interval(hctx);
} else {
/*
* Modify the cached value of X_recv
*
* If (X_calc > 2 * X_recv)
* X_recv = max(X_recv / 2, s / (2 * t_mbi));
* Else
* X_recv = X_calc / 4;
*
* Note that X_recv is scaled by 2^6 while X_calc is not
*/
BUG_ON(hctx->p && !hctx->x_calc);
if (hctx->x_calc > (hctx->x_recv >> 5))
hctx->x_recv =
max(hctx->x_recv / 2,
(((__u64)hctx->s) << 6) / (2 * TFRC_T_MBI));
else {
hctx->x_recv = hctx->x_calc;
hctx->x_recv <<= 4;
}
ccid3_hc_tx_update_x(sk, NULL);
}
ccid3_pr_debug("Reduced X to %llu/64 bytes/sec\n",
(unsigned long long)hctx->x);
/*
* Set new timeout for the nofeedback timer.
* See comments in packet_recv() regarding the value of t_RTO.
*/
if (unlikely(hctx->t_rto == 0)) /* no feedback received yet */
t_nfb = TFRC_INITIAL_TIMEOUT;
else
t_nfb = max(hctx->t_rto, 2 * hctx->t_ipi);
restart_timer:
sk_reset_timer(sk, &hctx->no_feedback_timer,
jiffies + usecs_to_jiffies(t_nfb));
out:
bh_unlock_sock(sk);
sock_put(sk);
}
/**
* ccid3_hc_tx_send_packet - Delay-based dequeueing of TX packets
* @skb: next packet candidate to send on @sk
* This function uses the convention of ccid_packet_dequeue_eval() and
* returns a millisecond-delay value between 0 and t_mbi = 64000 msec.
*/
static int ccid3_hc_tx_send_packet(struct sock *sk, struct sk_buff *skb)
{
struct dccp_sock *dp = dccp_sk(sk);
struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);
ktime_t now = ktime_get_real();
s64 delay;
/*
* This function is called only for Data and DataAck packets. Sending
* zero-sized Data(Ack)s is theoretically possible, but for congestion
* control this case is pathological - ignore it.
*/
if (unlikely(skb->len == 0))
return -EBADMSG;
if (hctx->s == 0) {
sk_reset_timer(sk, &hctx->no_feedback_timer, (jiffies +
usecs_to_jiffies(TFRC_INITIAL_TIMEOUT)));
hctx->last_win_count = 0;
hctx->t_last_win_count = now;
/* Set t_0 for initial packet */
hctx->t_nom = now;
hctx->s = skb->len;
/*
* Use initial RTT sample when available: recommended by erratum
* to RFC 4342. This implements the initialisation procedure of
* draft rfc3448bis, section 4.2. Remember, X is scaled by 2^6.
*/
if (dp->dccps_syn_rtt) {
ccid3_pr_debug("SYN RTT = %uus\n", dp->dccps_syn_rtt);
hctx->rtt = dp->dccps_syn_rtt;
hctx->x = rfc3390_initial_rate(sk);
hctx->t_ld = now;
} else {
/*
* Sender does not have RTT sample:
* - set fallback RTT (RFC 4340, 3.4) since a RTT value
* is needed in several parts (e.g. window counter);
* - set sending rate X_pps = 1pps as per RFC 3448, 4.2.
*/
hctx->rtt = DCCP_FALLBACK_RTT;
hctx->x = dp->dccps_mss_cache;
hctx->x <<= 6;
}
ccid3_update_send_interval(hctx);
} else {
delay = ktime_us_delta(hctx->t_nom, now);
ccid3_pr_debug("delay=%ld\n", (long)delay);
/*
* Scheduling of packet transmissions [RFC 3448, 4.6]
*
* if (t_now > t_nom - delta)
* // send the packet now
* else
* // send the packet in (t_nom - t_now) milliseconds.
*/
if (delay >= TFRC_T_DELTA)
return (u32)delay / USEC_PER_MSEC;
ccid3_hc_tx_update_win_count(hctx, now);
}
/* prepare to send now (add options etc.) */
dp->dccps_hc_tx_insert_options = 1;
DCCP_SKB_CB(skb)->dccpd_ccval = hctx->last_win_count;
/* set the nominal send time for the next following packet */
hctx->t_nom = ktime_add_us(hctx->t_nom, hctx->t_ipi);
return CCID_PACKET_SEND_AT_ONCE;
}
static void ccid3_hc_tx_packet_sent(struct sock *sk, unsigned int len)
{
struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);
ccid3_hc_tx_update_s(hctx, len);
if (tfrc_tx_hist_add(&hctx->hist, dccp_sk(sk)->dccps_gss))
DCCP_CRIT("packet history - out of memory!");
}
static void ccid3_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb)
{
struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);
struct tfrc_tx_hist_entry *acked;
ktime_t now;
unsigned long t_nfb;
u32 r_sample;
/* we are only interested in ACKs */
if (!(DCCP_SKB_CB(skb)->dccpd_type == DCCP_PKT_ACK ||
DCCP_SKB_CB(skb)->dccpd_type == DCCP_PKT_DATAACK))
return;
/*
* Locate the acknowledged packet in the TX history.
*
* Returning "entry not found" here can for instance happen when
* - the host has not sent out anything (e.g. a passive server),
* - the Ack is outdated (packet with higher Ack number was received),
* - it is a bogus Ack (for a packet not sent on this connection).
*/
acked = tfrc_tx_hist_find_entry(hctx->hist, dccp_hdr_ack_seq(skb));
if (acked == NULL)
return;
/* For the sake of RTT sampling, ignore/remove all older entries */
tfrc_tx_hist_purge(&acked->next);
/* Update the moving average for the RTT estimate (RFC 3448, 4.3) */
now = ktime_get_real();
r_sample = dccp_sample_rtt(sk, ktime_us_delta(now, acked->stamp));
hctx->rtt = tfrc_ewma(hctx->rtt, r_sample, 9);
/*
* Update allowed sending rate X as per draft rfc3448bis-00, 4.2/3
*/
if (!hctx->feedback) {
hctx->feedback = true;
if (hctx->t_rto == 0) {
/*
* Initial feedback packet: Larger Initial Windows (4.2)
*/
hctx->x = rfc3390_initial_rate(sk);
hctx->t_ld = now;
ccid3_update_send_interval(hctx);
goto done_computing_x;
} else if (hctx->p == 0) {
/*
* First feedback after nofeedback timer expiry (4.3)
*/
goto done_computing_x;
}
}
/* Update sending rate (step 4 of [RFC 3448, 4.3]) */
if (hctx->p > 0)
hctx->x_calc = tfrc_calc_x(hctx->s, hctx->rtt, hctx->p);
ccid3_hc_tx_update_x(sk, &now);
done_computing_x:
ccid3_pr_debug("%s(%p), RTT=%uus (sample=%uus), s=%u, "
"p=%u, X_calc=%u, X_recv=%u, X=%u\n",
dccp_role(sk), sk, hctx->rtt, r_sample,
hctx->s, hctx->p, hctx->x_calc,
(unsigned)(hctx->x_recv >> 6),
(unsigned)(hctx->x >> 6));
/* unschedule no feedback timer */
sk_stop_timer(sk, &hctx->no_feedback_timer);
/*
* As we have calculated new ipi, delta, t_nom it is possible
* that we now can send a packet, so wake up dccp_wait_for_ccid
*/
sk->sk_write_space(sk);
/*
* Update timeout interval for the nofeedback timer.
* We use a configuration option to increase the lower bound.
* This can help avoid triggering the nofeedback timer too
* often ('spinning') on LANs with small RTTs.
*/
hctx->t_rto = max_t(u32, 4 * hctx->rtt, (CONFIG_IP_DCCP_CCID3_RTO *
(USEC_PER_SEC / 1000)));
/*
* Schedule no feedback timer to expire in
* max(t_RTO, 2 * s/X) = max(t_RTO, 2 * t_ipi)
*/
t_nfb = max(hctx->t_rto, 2 * hctx->t_ipi);
ccid3_pr_debug("%s(%p), Scheduled no feedback timer to "
"expire in %lu jiffies (%luus)\n",
dccp_role(sk), sk, usecs_to_jiffies(t_nfb), t_nfb);
sk_reset_timer(sk, &hctx->no_feedback_timer,
jiffies + usecs_to_jiffies(t_nfb));
}
static int ccid3_hc_tx_parse_options(struct sock *sk, u8 packet_type,
u8 option, u8 *optval, u8 optlen)
{
struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);
__be32 opt_val;
switch (option) {
case TFRC_OPT_RECEIVE_RATE:
case TFRC_OPT_LOSS_EVENT_RATE:
/* Must be ignored on Data packets, cf. RFC 4342 8.3 and 8.5 */
if (packet_type == DCCP_PKT_DATA)
break;
if (unlikely(optlen != 4)) {
DCCP_WARN("%s(%p), invalid len %d for %u\n",
dccp_role(sk), sk, optlen, option);
return -EINVAL;
}
opt_val = ntohl(get_unaligned((__be32 *)optval));
if (option == TFRC_OPT_RECEIVE_RATE) {
/* Receive Rate is kept in units of 64 bytes/second */
hctx->x_recv = opt_val;
hctx->x_recv <<= 6;
ccid3_pr_debug("%s(%p), RECEIVE_RATE=%u\n",
dccp_role(sk), sk, opt_val);
} else {
/* Update the fixpoint Loss Event Rate fraction */
hctx->p = tfrc_invert_loss_event_rate(opt_val);
ccid3_pr_debug("%s(%p), LOSS_EVENT_RATE=%u\n",
dccp_role(sk), sk, opt_val);
}
}
return 0;
}
static int ccid3_hc_tx_init(struct ccid *ccid, struct sock *sk)
{
struct ccid3_hc_tx_sock *hctx = ccid_priv(ccid);
hctx->hist = NULL;
setup_timer(&hctx->no_feedback_timer,
ccid3_hc_tx_no_feedback_timer, (unsigned long)sk);
return 0;
}
static void ccid3_hc_tx_exit(struct sock *sk)
{
struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);
sk_stop_timer(sk, &hctx->no_feedback_timer);
tfrc_tx_hist_purge(&hctx->hist);
}
static void ccid3_hc_tx_get_info(struct sock *sk, struct tcp_info *info)
{
info->tcpi_rto = ccid3_hc_tx_sk(sk)->t_rto;
info->tcpi_rtt = ccid3_hc_tx_sk(sk)->rtt;
}
static int ccid3_hc_tx_getsockopt(struct sock *sk, const int optname, int len,
u32 __user *optval, int __user *optlen)
{
const struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);
struct tfrc_tx_info tfrc;
const void *val;
switch (optname) {
case DCCP_SOCKOPT_CCID_TX_INFO:
if (len < sizeof(tfrc))
return -EINVAL;
tfrc.tfrctx_x = hctx->x;
tfrc.tfrctx_x_recv = hctx->x_recv;
tfrc.tfrctx_x_calc = hctx->x_calc;
tfrc.tfrctx_rtt = hctx->rtt;
tfrc.tfrctx_p = hctx->p;
tfrc.tfrctx_rto = hctx->t_rto;
tfrc.tfrctx_ipi = hctx->t_ipi;
len = sizeof(tfrc);
val = &tfrc;
break;
default:
return -ENOPROTOOPT;
}
if (put_user(len, optlen) || copy_to_user(optval, val, len))
return -EFAULT;
return 0;
}
/*
* Receiver Half-Connection Routines
*/
static void ccid3_hc_rx_send_feedback(struct sock *sk,
const struct sk_buff *skb,
enum ccid3_fback_type fbtype)
{
struct ccid3_hc_rx_sock *hcrx = ccid3_hc_rx_sk(sk);
switch (fbtype) {
case CCID3_FBACK_INITIAL:
hcrx->x_recv = 0;
hcrx->p_inverse = ~0U; /* see RFC 4342, 8.5 */
break;
case CCID3_FBACK_PARAM_CHANGE:
if (unlikely(hcrx->feedback == CCID3_FBACK_NONE)) {
/*
* rfc3448bis-06, 6.3.1: First packet(s) lost or marked
* FIXME: in rfc3448bis the receiver returns X_recv=0
* here as it normally would in the first feedback packet.
* However this is not possible yet, since the code still
* uses RFC 3448, i.e.
* If (p > 0)
* Calculate X_calc using the TCP throughput equation.
* X = max(min(X_calc, 2*X_recv), s/t_mbi);
* would bring X down to s/t_mbi. That is why we return
* X_recv according to rfc3448bis-06 for the moment.
*/
u32 s = tfrc_rx_hist_packet_size(&hcrx->hist),
rtt = tfrc_rx_hist_rtt(&hcrx->hist);
hcrx->x_recv = scaled_div32(s, 2 * rtt);
break;
}
/*
* When parameters change (new loss or p > p_prev), we do not
* have a reliable estimate for R_m of [RFC 3448, 6.2] and so
* always check whether at least RTT time units were covered.
*/
hcrx->x_recv = tfrc_rx_hist_x_recv(&hcrx->hist, hcrx->x_recv);
break;
case CCID3_FBACK_PERIODIC:
/*
* Step (2) of rfc3448bis-06, 6.2:
* - if no data packets have been received, just restart timer
* - if data packets have been received, re-compute X_recv
*/
if (hcrx->hist.bytes_recvd == 0)
goto prepare_for_next_time;
hcrx->x_recv = tfrc_rx_hist_x_recv(&hcrx->hist, hcrx->x_recv);
break;
default:
return;
}
ccid3_pr_debug("X_recv=%u, 1/p=%u\n", hcrx->x_recv, hcrx->p_inverse);
dccp_sk(sk)->dccps_hc_rx_insert_options = 1;
dccp_send_ack(sk);
prepare_for_next_time:
tfrc_rx_hist_restart_byte_counter(&hcrx->hist);
hcrx->last_counter = dccp_hdr(skb)->dccph_ccval;
hcrx->feedback = fbtype;
}
static int ccid3_hc_rx_insert_options(struct sock *sk, struct sk_buff *skb)
{
const struct ccid3_hc_rx_sock *hcrx = ccid3_hc_rx_sk(sk);
__be32 x_recv, pinv;
if (!(sk->sk_state == DCCP_OPEN || sk->sk_state == DCCP_PARTOPEN))
return 0;
if (dccp_packet_without_ack(skb))
return 0;
x_recv = htonl(hcrx->x_recv);
pinv = htonl(hcrx->p_inverse);
if (dccp_insert_option(sk, skb, TFRC_OPT_LOSS_EVENT_RATE,
&pinv, sizeof(pinv)) ||
dccp_insert_option(sk, skb, TFRC_OPT_RECEIVE_RATE,
&x_recv, sizeof(x_recv)))
return -1;
return 0;
}
/** ccid3_first_li - Implements [RFC 3448, 6.3.1]
*
* Determine the length of the first loss interval via inverse lookup.
* Assume that X_recv can be computed by the throughput equation
* s
* X_recv = --------
* R * fval
* Find some p such that f(p) = fval; return 1/p (scaled).
*/
static u32 ccid3_first_li(struct sock *sk)
{
struct ccid3_hc_rx_sock *hcrx = ccid3_hc_rx_sk(sk);
u32 s = tfrc_rx_hist_packet_size(&hcrx->hist),
rtt = tfrc_rx_hist_rtt(&hcrx->hist), x_recv, p;
u64 fval;
/*
* rfc3448bis-06, 6.3.1: First data packet(s) are marked or lost. Set p
* to give the equivalent of X_target = s/(2*R). Thus fval = 2 and so p
* is about 20.64%. This yields an interval length of 4.84 (rounded up).
*/
if (unlikely(hcrx->feedback == CCID3_FBACK_NONE))
return 5;
x_recv = tfrc_rx_hist_x_recv(&hcrx->hist, hcrx->x_recv);
if (x_recv == 0)
goto failed;
fval = scaled_div32(scaled_div(s, rtt), x_recv);
p = tfrc_calc_x_reverse_lookup(fval);
ccid3_pr_debug("%s(%p), receive rate=%u bytes/s, implied "
"loss rate=%u\n", dccp_role(sk), sk, x_recv, p);
if (p > 0)
return scaled_div(1, p);
failed:
return UINT_MAX;
}
static void ccid3_hc_rx_packet_recv(struct sock *sk, struct sk_buff *skb)
{
struct ccid3_hc_rx_sock *hcrx = ccid3_hc_rx_sk(sk);
const u64 ndp = dccp_sk(sk)->dccps_options_received.dccpor_ndp;
const bool is_data_packet = dccp_data_packet(skb);
/*
* Perform loss detection and handle pending losses
*/
if (tfrc_rx_congestion_event(&hcrx->hist, &hcrx->li_hist,
skb, ndp, ccid3_first_li, sk))
ccid3_hc_rx_send_feedback(sk, skb, CCID3_FBACK_PARAM_CHANGE);
/*
* Feedback for first non-empty data packet (RFC 3448, 6.3)
*/
else if (unlikely(hcrx->feedback == CCID3_FBACK_NONE && is_data_packet))
ccid3_hc_rx_send_feedback(sk, skb, CCID3_FBACK_INITIAL);
/*
* Check if the periodic once-per-RTT feedback is due; RFC 4342, 10.3
*/
else if (!tfrc_rx_hist_loss_pending(&hcrx->hist) && is_data_packet &&
SUB16(dccp_hdr(skb)->dccph_ccval, hcrx->last_counter) > 3)
ccid3_hc_rx_send_feedback(sk, skb, CCID3_FBACK_PERIODIC);
}
static int ccid3_hc_rx_init(struct ccid *ccid, struct sock *sk)
{
struct ccid3_hc_rx_sock *hcrx = ccid_priv(ccid);
tfrc_lh_init(&hcrx->li_hist);
return tfrc_rx_hist_init(&hcrx->hist, sk);
}
static void ccid3_hc_rx_exit(struct sock *sk)
{
struct ccid3_hc_rx_sock *hcrx = ccid3_hc_rx_sk(sk);
tfrc_rx_hist_purge(&hcrx->hist);
tfrc_lh_cleanup(&hcrx->li_hist);
}
static void ccid3_hc_rx_get_info(struct sock *sk, struct tcp_info *info)
{
info->tcpi_options |= TCPI_OPT_TIMESTAMPS;
info->tcpi_rcv_rtt = tfrc_rx_hist_rtt(&ccid3_hc_rx_sk(sk)->hist);
}
static int ccid3_hc_rx_getsockopt(struct sock *sk, const int optname, int len,
u32 __user *optval, int __user *optlen)
{
const struct ccid3_hc_rx_sock *hcrx = ccid3_hc_rx_sk(sk);
struct tfrc_rx_info rx_info;
const void *val;
switch (optname) {
case DCCP_SOCKOPT_CCID_RX_INFO:
if (len < sizeof(rx_info))
return -EINVAL;
rx_info.tfrcrx_x_recv = hcrx->x_recv;
rx_info.tfrcrx_rtt = tfrc_rx_hist_rtt(&hcrx->hist);
rx_info.tfrcrx_p = tfrc_invert_loss_event_rate(hcrx->p_inverse);
len = sizeof(rx_info);
val = &rx_info;
break;
default:
return -ENOPROTOOPT;
}
if (put_user(len, optlen) || copy_to_user(optval, val, len))
return -EFAULT;
return 0;
}
static struct ccid_operations ccid3 = {
.ccid_id = DCCPC_CCID3,
.ccid_name = "TCP-Friendly Rate Control",
.ccid_owner = THIS_MODULE,
.ccid_hc_tx_obj_size = sizeof(struct ccid3_hc_tx_sock),
.ccid_hc_tx_init = ccid3_hc_tx_init,
.ccid_hc_tx_exit = ccid3_hc_tx_exit,
.ccid_hc_tx_send_packet = ccid3_hc_tx_send_packet,
.ccid_hc_tx_packet_sent = ccid3_hc_tx_packet_sent,
.ccid_hc_tx_packet_recv = ccid3_hc_tx_packet_recv,
.ccid_hc_tx_parse_options = ccid3_hc_tx_parse_options,
.ccid_hc_rx_obj_size = sizeof(struct ccid3_hc_rx_sock),
.ccid_hc_rx_init = ccid3_hc_rx_init,
.ccid_hc_rx_exit = ccid3_hc_rx_exit,
.ccid_hc_rx_insert_options = ccid3_hc_rx_insert_options,
.ccid_hc_rx_packet_recv = ccid3_hc_rx_packet_recv,
.ccid_hc_rx_get_info = ccid3_hc_rx_get_info,
.ccid_hc_tx_get_info = ccid3_hc_tx_get_info,
.ccid_hc_rx_getsockopt = ccid3_hc_rx_getsockopt,
.ccid_hc_tx_getsockopt = ccid3_hc_tx_getsockopt,
};
#ifdef CONFIG_IP_DCCP_CCID3_DEBUG
module_param(ccid3_debug, bool, 0644);
MODULE_PARM_DESC(ccid3_debug, "Enable debug messages");
#endif
static __init int ccid3_module_init(void)
{
struct timespec tp;
/*
* Without a fine-grained clock resolution, RTTs/X_recv are not sampled
* correctly and feedback is sent either too early or too late.
*/
hrtimer_get_res(CLOCK_MONOTONIC, &tp);
if (tp.tv_sec || tp.tv_nsec > DCCP_TIME_RESOLUTION * NSEC_PER_USEC) {
printk(KERN_ERR "%s: Timer too coarse (%ld usec), need %u-usec"
" resolution - check your clocksource.\n", __func__,
tp.tv_nsec/NSEC_PER_USEC, DCCP_TIME_RESOLUTION);
return -ESOCKTNOSUPPORT;
}
return ccid_register(&ccid3);
}
module_init(ccid3_module_init);
static __exit void ccid3_module_exit(void)
{
ccid_unregister(&ccid3);
}
module_exit(ccid3_module_exit);
MODULE_AUTHOR("Ian McDonald <ian.mcdonald@jandi.co.nz>, "
"Arnaldo Carvalho de Melo <acme@ghostprotocols.net>");
MODULE_DESCRIPTION("DCCP TFRC CCID3 CCID");
MODULE_LICENSE("GPL");
MODULE_ALIAS("net-dccp-ccid-3");