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OpenCloudOS-Kernel/net/dccp/ccids/ccid3.c

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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* 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>
*/
#include "../dccp.h"
#include "ccid3.h"
#include <asm/unaligned.h>
#ifdef CONFIG_IP_DCCP_CCID3_DEBUG
static bool 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
*/
#ifdef CONFIG_IP_DCCP_CCID3_DEBUG
static const char *ccid3_tx_state_name(enum ccid3_hc_tx_states state)
{
static const char *const ccid3_state_names[] = {
[TFRC_SSTATE_NO_SENT] = "NO_SENT",
[TFRC_SSTATE_NO_FBACK] = "NO_FBACK",
[TFRC_SSTATE_FBACK] = "FBACK",
};
return ccid3_state_names[state];
}
#endif
static void ccid3_hc_tx_set_state(struct sock *sk,
enum ccid3_hc_tx_states state)
{
struct ccid3_hc_tx_sock *hc = ccid3_hc_tx_sk(sk);
enum ccid3_hc_tx_states oldstate = hc->tx_state;
ccid3_pr_debug("%s(%p) %-8.8s -> %s\n",
dccp_role(sk), sk, ccid3_tx_state_name(oldstate),
ccid3_tx_state_name(state));
WARN_ON(state == oldstate);
hc->tx_state = state;
}
/*
* Compute the initial sending rate X_init in the manner of RFC 3390:
*
* X_init = min(4 * s, max(2 * s, 4380 bytes)) / RTT
*
* Note that RFC 3390 uses MSS, RFC 4342 refers to RFC 3390, and rfc3448bis
* (rev-02) clarifies the use of RFC 3390 with regard to the above formula.
* 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 struct ccid3_hc_tx_sock *hc = ccid3_hc_tx_sk(sk);
const __u32 w_init = clamp_t(__u32, 4380U, 2 * hc->tx_s, 4 * hc->tx_s);
return scaled_div(w_init << 6, hc->tx_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 *hc)
{
hc->tx_t_ipi = scaled_div32(((u64)hc->tx_s) << 6, hc->tx_x);
DCCP_BUG_ON(hc->tx_t_ipi == 0);
ccid3_pr_debug("t_ipi=%u, s=%u, X=%u\n", hc->tx_t_ipi,
hc->tx_s, (unsigned int)(hc->tx_x >> 6));
}
static u32 ccid3_hc_tx_idle_rtt(struct ccid3_hc_tx_sock *hc, ktime_t now)
{
u32 delta = ktime_us_delta(now, hc->tx_t_last_win_count);
return delta / hc->tx_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 *hc = ccid3_hc_tx_sk(sk);
__u64 min_rate = 2 * hc->tx_x_recv;
const __u64 old_x = hc->tx_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(hc, now) >= 2) {
min_rate = rfc3390_initial_rate(sk);
min_rate = max(min_rate, 2 * hc->tx_x_recv);
}
if (hc->tx_p > 0) {
hc->tx_x = min(((__u64)hc->tx_x_calc) << 6, min_rate);
hc->tx_x = max(hc->tx_x, (((__u64)hc->tx_s) << 6) / TFRC_T_MBI);
} else if (ktime_us_delta(now, hc->tx_t_ld) - (s64)hc->tx_rtt >= 0) {
hc->tx_x = min(2 * hc->tx_x, min_rate);
hc->tx_x = max(hc->tx_x,
scaled_div(((__u64)hc->tx_s) << 6, hc->tx_rtt));
hc->tx_t_ld = now;
}
if (hc->tx_x != old_x) {
ccid3_pr_debug("X_prev=%u, X_now=%u, X_calc=%u, "
"X_recv=%u\n", (unsigned int)(old_x >> 6),
(unsigned int)(hc->tx_x >> 6), hc->tx_x_calc,
(unsigned int)(hc->tx_x_recv >> 6));
ccid3_update_send_interval(hc);
}
}
/**
* ccid3_hc_tx_update_s - Track the mean packet size `s'
* @len: DCCP packet payload size in bytes
*
* cf. RFC 4342, 5.3 and RFC 3448, 4.1
*/
static inline void ccid3_hc_tx_update_s(struct ccid3_hc_tx_sock *hc, int len)
{
const u16 old_s = hc->tx_s;
hc->tx_s = tfrc_ewma(hc->tx_s, len, 9);
if (hc->tx_s != old_s)
ccid3_update_send_interval(hc);
}
/*
* 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 *hc,
ktime_t now)
{
u32 delta = ktime_us_delta(now, hc->tx_t_last_win_count),
quarter_rtts = (4 * delta) / hc->tx_rtt;
if (quarter_rtts > 0) {
hc->tx_t_last_win_count = now;
hc->tx_last_win_count += min(quarter_rtts, 5U);
hc->tx_last_win_count &= 0xF; /* mod 16 */
}
}
static void ccid3_hc_tx_no_feedback_timer(struct timer_list *t)
{
struct ccid3_hc_tx_sock *hc = from_timer(hc, t, tx_no_feedback_timer);
struct sock *sk = hc->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, state=%s) - entry\n", dccp_role(sk), sk,
ccid3_tx_state_name(hc->tx_state));
/* 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" */
if (hc->tx_state == TFRC_SSTATE_FBACK)
ccid3_hc_tx_set_state(sk, TFRC_SSTATE_NO_FBACK);
/*
* 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 (hc->tx_t_rto == 0 || hc->tx_p == 0) {
/* halve send rate directly */
hc->tx_x = max(hc->tx_x / 2,
(((__u64)hc->tx_s) << 6) / TFRC_T_MBI);
ccid3_update_send_interval(hc);
} 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
*/
if (hc->tx_x_calc > (hc->tx_x_recv >> 5))
hc->tx_x_recv =
max(hc->tx_x_recv / 2,
(((__u64)hc->tx_s) << 6) / (2*TFRC_T_MBI));
else {
hc->tx_x_recv = hc->tx_x_calc;
hc->tx_x_recv <<= 4;
}
ccid3_hc_tx_update_x(sk, NULL);
}
ccid3_pr_debug("Reduced X to %llu/64 bytes/sec\n",
(unsigned long long)hc->tx_x);
/*
* Set new timeout for the nofeedback timer.
* See comments in packet_recv() regarding the value of t_RTO.
*/
if (unlikely(hc->tx_t_rto == 0)) /* no feedback received yet */
t_nfb = TFRC_INITIAL_TIMEOUT;
else
t_nfb = max(hc->tx_t_rto, 2 * hc->tx_t_ipi);
restart_timer:
sk_reset_timer(sk, &hc->tx_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 *hc = 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 (hc->tx_state == TFRC_SSTATE_NO_SENT) {
sk_reset_timer(sk, &hc->tx_no_feedback_timer, (jiffies +
usecs_to_jiffies(TFRC_INITIAL_TIMEOUT)));
hc->tx_last_win_count = 0;
hc->tx_t_last_win_count = now;
/* Set t_0 for initial packet */
hc->tx_t_nom = now;
hc->tx_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);
hc->tx_rtt = dp->dccps_syn_rtt;
hc->tx_x = rfc3390_initial_rate(sk);
hc->tx_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.
*/
hc->tx_rtt = DCCP_FALLBACK_RTT;
hc->tx_x = hc->tx_s;
hc->tx_x <<= 6;
}
ccid3_update_send_interval(hc);
ccid3_hc_tx_set_state(sk, TFRC_SSTATE_NO_FBACK);
} else {
delay = ktime_us_delta(hc->tx_t_nom, now);
ccid3_pr_debug("delay=%ld\n", (long)delay);
/*
* Scheduling of packet transmissions (RFC 5348, 8.3)
*
* 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(hc, now);
}
/* prepare to send now (add options etc.) */
dp->dccps_hc_tx_insert_options = 1;
DCCP_SKB_CB(skb)->dccpd_ccval = hc->tx_last_win_count;
/* set the nominal send time for the next following packet */
hc->tx_t_nom = ktime_add_us(hc->tx_t_nom, hc->tx_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 *hc = ccid3_hc_tx_sk(sk);
ccid3_hc_tx_update_s(hc, len);
if (tfrc_tx_hist_add(&hc->tx_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 *hc = 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(hc->tx_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));
hc->tx_rtt = tfrc_ewma(hc->tx_rtt, r_sample, 9);
/*
* Update allowed sending rate X as per draft rfc3448bis-00, 4.2/3
*/
if (hc->tx_state == TFRC_SSTATE_NO_FBACK) {
ccid3_hc_tx_set_state(sk, TFRC_SSTATE_FBACK);
if (hc->tx_t_rto == 0) {
/*
* Initial feedback packet: Larger Initial Windows (4.2)
*/
hc->tx_x = rfc3390_initial_rate(sk);
hc->tx_t_ld = now;
ccid3_update_send_interval(hc);
goto done_computing_x;
} else if (hc->tx_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 (hc->tx_p > 0)
hc->tx_x_calc = tfrc_calc_x(hc->tx_s, hc->tx_rtt, hc->tx_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, hc->tx_rtt, r_sample,
hc->tx_s, hc->tx_p, hc->tx_x_calc,
(unsigned int)(hc->tx_x_recv >> 6),
(unsigned int)(hc->tx_x >> 6));
/* unschedule no feedback timer */
sk_stop_timer(sk, &hc->tx_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. In order to control
* rate halving on networks with very low RTTs (<= 1 ms), use per-route
* tunable RTAX_RTO_MIN value as the lower bound.
*/
hc->tx_t_rto = max_t(u32, 4 * hc->tx_rtt,
USEC_PER_SEC/HZ * tcp_rto_min(sk));
/*
* Schedule no feedback timer to expire in
* max(t_RTO, 2 * s/X) = max(t_RTO, 2 * t_ipi)
*/
t_nfb = max(hc->tx_t_rto, 2 * hc->tx_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, &hc->tx_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 *hc = 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 */
hc->tx_x_recv = opt_val;
hc->tx_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 */
hc->tx_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 *hc = ccid_priv(ccid);
hc->tx_state = TFRC_SSTATE_NO_SENT;
hc->tx_hist = NULL;
hc->sk = sk;
timer_setup(&hc->tx_no_feedback_timer,
ccid3_hc_tx_no_feedback_timer, 0);
return 0;
}
static void ccid3_hc_tx_exit(struct sock *sk)
{
struct ccid3_hc_tx_sock *hc = ccid3_hc_tx_sk(sk);
sk_stop_timer(sk, &hc->tx_no_feedback_timer);
tfrc_tx_hist_purge(&hc->tx_hist);
}
static void ccid3_hc_tx_get_info(struct sock *sk, struct tcp_info *info)
{
info->tcpi_rto = ccid3_hc_tx_sk(sk)->tx_t_rto;
info->tcpi_rtt = ccid3_hc_tx_sk(sk)->tx_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 *hc = 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;
memset(&tfrc, 0, sizeof(tfrc));
tfrc.tfrctx_x = hc->tx_x;
tfrc.tfrctx_x_recv = hc->tx_x_recv;
tfrc.tfrctx_x_calc = hc->tx_x_calc;
tfrc.tfrctx_rtt = hc->tx_rtt;
tfrc.tfrctx_p = hc->tx_p;
tfrc.tfrctx_rto = hc->tx_t_rto;
tfrc.tfrctx_ipi = hc->tx_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
*/
/* CCID3 feedback types */
enum ccid3_fback_type {
CCID3_FBACK_NONE = 0,
CCID3_FBACK_INITIAL,
CCID3_FBACK_PERIODIC,
CCID3_FBACK_PARAM_CHANGE
};
#ifdef CONFIG_IP_DCCP_CCID3_DEBUG
static const char *ccid3_rx_state_name(enum ccid3_hc_rx_states state)
{
static const char *const ccid3_rx_state_names[] = {
[TFRC_RSTATE_NO_DATA] = "NO_DATA",
[TFRC_RSTATE_DATA] = "DATA",
};
return ccid3_rx_state_names[state];
}
#endif
static void ccid3_hc_rx_set_state(struct sock *sk,
enum ccid3_hc_rx_states state)
{
struct ccid3_hc_rx_sock *hc = ccid3_hc_rx_sk(sk);
enum ccid3_hc_rx_states oldstate = hc->rx_state;
ccid3_pr_debug("%s(%p) %-8.8s -> %s\n",
dccp_role(sk), sk, ccid3_rx_state_name(oldstate),
ccid3_rx_state_name(state));
WARN_ON(state == oldstate);
hc->rx_state = state;
}
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 *hc = ccid3_hc_rx_sk(sk);
struct dccp_sock *dp = dccp_sk(sk);
ktime_t now = ktime_get();
s64 delta = 0;
switch (fbtype) {
case CCID3_FBACK_INITIAL:
hc->rx_x_recv = 0;
hc->rx_pinv = ~0U; /* see RFC 4342, 8.5 */
break;
case CCID3_FBACK_PARAM_CHANGE:
/*
* 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
* need to reuse the previous value of X_recv. However, when
* X_recv was 0 (due to early loss), this would kill X down to
* s/t_mbi (i.e. one packet in 64 seconds).
* To avoid such drastic reduction, we approximate X_recv as
* the number of bytes since last feedback.
* This is a safe fallback, since X is bounded above by X_calc.
*/
if (hc->rx_x_recv > 0)
break;
/* fall through */
case CCID3_FBACK_PERIODIC:
delta = ktime_us_delta(now, hc->rx_tstamp_last_feedback);
if (delta <= 0)
delta = 1;
hc->rx_x_recv = scaled_div32(hc->rx_bytes_recv, delta);
break;
default:
return;
}
ccid3_pr_debug("Interval %lldusec, X_recv=%u, 1/p=%u\n", delta,
hc->rx_x_recv, hc->rx_pinv);
hc->rx_tstamp_last_feedback = now;
hc->rx_last_counter = dccp_hdr(skb)->dccph_ccval;
hc->rx_bytes_recv = 0;
dp->dccps_hc_rx_insert_options = 1;
dccp_send_ack(sk);
}
static int ccid3_hc_rx_insert_options(struct sock *sk, struct sk_buff *skb)
{
const struct ccid3_hc_rx_sock *hc = 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(hc->rx_x_recv);
pinv = htonl(hc->rx_pinv);
if (dccp_insert_option(skb, TFRC_OPT_LOSS_EVENT_RATE,
&pinv, sizeof(pinv)) ||
dccp_insert_option(skb, TFRC_OPT_RECEIVE_RATE,
&x_recv, sizeof(x_recv)))
return -1;
return 0;
}
/**
* ccid3_first_li - Implements [RFC 5348, 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 *hc = ccid3_hc_rx_sk(sk);
u32 x_recv, p;
s64 delta;
u64 fval;
if (hc->rx_rtt == 0) {
DCCP_WARN("No RTT estimate available, using fallback RTT\n");
hc->rx_rtt = DCCP_FALLBACK_RTT;
}
delta = ktime_us_delta(ktime_get(), hc->rx_tstamp_last_feedback);
if (delta <= 0)
delta = 1;
x_recv = scaled_div32(hc->rx_bytes_recv, delta);
if (x_recv == 0) { /* would also trigger divide-by-zero */
DCCP_WARN("X_recv==0\n");
if (hc->rx_x_recv == 0) {
DCCP_BUG("stored value of X_recv is zero");
return ~0U;
}
x_recv = hc->rx_x_recv;
}
fval = scaled_div(hc->rx_s, hc->rx_rtt);
fval = scaled_div32(fval, 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);
return p == 0 ? ~0U : scaled_div(1, p);
}
static void ccid3_hc_rx_packet_recv(struct sock *sk, struct sk_buff *skb)
{
struct ccid3_hc_rx_sock *hc = ccid3_hc_rx_sk(sk);
enum ccid3_fback_type do_feedback = CCID3_FBACK_NONE;
const u64 ndp = dccp_sk(sk)->dccps_options_received.dccpor_ndp;
const bool is_data_packet = dccp_data_packet(skb);
if (unlikely(hc->rx_state == TFRC_RSTATE_NO_DATA)) {
if (is_data_packet) {
const u32 payload = skb->len - dccp_hdr(skb)->dccph_doff * 4;
do_feedback = CCID3_FBACK_INITIAL;
ccid3_hc_rx_set_state(sk, TFRC_RSTATE_DATA);
hc->rx_s = payload;
/*
* Not necessary to update rx_bytes_recv here,
* since X_recv = 0 for the first feedback packet (cf.
* RFC 3448, 6.3) -- gerrit
*/
}
goto update_records;
}
if (tfrc_rx_hist_duplicate(&hc->rx_hist, skb))
return; /* done receiving */
if (is_data_packet) {
const u32 payload = skb->len - dccp_hdr(skb)->dccph_doff * 4;
/*
* Update moving-average of s and the sum of received payload bytes
*/
hc->rx_s = tfrc_ewma(hc->rx_s, payload, 9);
hc->rx_bytes_recv += payload;
}
/*
* Perform loss detection and handle pending losses
*/
if (tfrc_rx_handle_loss(&hc->rx_hist, &hc->rx_li_hist,
skb, ndp, ccid3_first_li, sk)) {
do_feedback = CCID3_FBACK_PARAM_CHANGE;
goto done_receiving;
}
if (tfrc_rx_hist_loss_pending(&hc->rx_hist))
return; /* done receiving */
/*
* Handle data packets: RTT sampling and monitoring p
*/
if (unlikely(!is_data_packet))
goto update_records;
if (!tfrc_lh_is_initialised(&hc->rx_li_hist)) {
const u32 sample = tfrc_rx_hist_sample_rtt(&hc->rx_hist, skb);
/*
* Empty loss history: no loss so far, hence p stays 0.
* Sample RTT values, since an RTT estimate is required for the
* computation of p when the first loss occurs; RFC 3448, 6.3.1.
*/
if (sample != 0)
hc->rx_rtt = tfrc_ewma(hc->rx_rtt, sample, 9);
} else if (tfrc_lh_update_i_mean(&hc->rx_li_hist, skb)) {
/*
* Step (3) of [RFC 3448, 6.1]: Recompute I_mean and, if I_mean
* has decreased (resp. p has increased), send feedback now.
*/
do_feedback = CCID3_FBACK_PARAM_CHANGE;
}
/*
* Check if the periodic once-per-RTT feedback is due; RFC 4342, 10.3
*/
if (SUB16(dccp_hdr(skb)->dccph_ccval, hc->rx_last_counter) > 3)
do_feedback = CCID3_FBACK_PERIODIC;
update_records:
tfrc_rx_hist_add_packet(&hc->rx_hist, skb, ndp);
done_receiving:
if (do_feedback)
ccid3_hc_rx_send_feedback(sk, skb, do_feedback);
}
static int ccid3_hc_rx_init(struct ccid *ccid, struct sock *sk)
{
struct ccid3_hc_rx_sock *hc = ccid_priv(ccid);
hc->rx_state = TFRC_RSTATE_NO_DATA;
tfrc_lh_init(&hc->rx_li_hist);
return tfrc_rx_hist_alloc(&hc->rx_hist);
}
static void ccid3_hc_rx_exit(struct sock *sk)
{
struct ccid3_hc_rx_sock *hc = ccid3_hc_rx_sk(sk);
tfrc_rx_hist_purge(&hc->rx_hist);
tfrc_lh_cleanup(&hc->rx_li_hist);
}
static void ccid3_hc_rx_get_info(struct sock *sk, struct tcp_info *info)
{
info->tcpi_ca_state = ccid3_hc_rx_sk(sk)->rx_state;
info->tcpi_options |= TCPI_OPT_TIMESTAMPS;
info->tcpi_rcv_rtt = ccid3_hc_rx_sk(sk)->rx_rtt;
}
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 *hc = 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 = hc->rx_x_recv;
rx_info.tfrcrx_rtt = hc->rx_rtt;
rx_info.tfrcrx_p = tfrc_invert_loss_event_rate(hc->rx_pinv);
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;
}
struct ccid_operations ccid3_ops = {
.ccid_id = DCCPC_CCID3,
.ccid_name = "TCP-Friendly Rate Control",
.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 CCID-3 debug messages");
#endif
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