827 lines
25 KiB
C
827 lines
25 KiB
C
/*
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* net/dccp/ccids/ccid3.c
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*
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* Copyright (c) 2007 The University of Aberdeen, Scotland, UK
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* Copyright (c) 2005-7 The University of Waikato, Hamilton, New Zealand.
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* Copyright (c) 2005-7 Ian McDonald <ian.mcdonald@jandi.co.nz>
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*
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* An implementation of the DCCP protocol
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*
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* This code has been developed by the University of Waikato WAND
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* research group. For further information please see http://www.wand.net.nz/
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*
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* This code also uses code from Lulea University, rereleased as GPL by its
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* authors:
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* Copyright (c) 2003 Nils-Erik Mattsson, Joacim Haggmark, Magnus Erixzon
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*
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* Changes to meet Linux coding standards, to make it meet latest ccid3 draft
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* and to make it work as a loadable module in the DCCP stack written by
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* Arnaldo Carvalho de Melo <acme@conectiva.com.br>.
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*
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* Copyright (c) 2005 Arnaldo Carvalho de Melo <acme@conectiva.com.br>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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#include "../dccp.h"
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#include "ccid3.h"
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#include <asm/unaligned.h>
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#ifdef CONFIG_IP_DCCP_CCID3_DEBUG
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static int ccid3_debug;
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#define ccid3_pr_debug(format, a...) DCCP_PR_DEBUG(ccid3_debug, format, ##a)
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#else
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#define ccid3_pr_debug(format, a...)
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#endif
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/*
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* Transmitter Half-Connection Routines
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*/
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/* Oscillation Prevention/Reduction: recommended by rfc3448bis, on by default */
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static int do_osc_prev = true;
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/*
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* Compute the initial sending rate X_init in the manner of RFC 3390:
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*
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* X_init = min(4 * MPS, max(2 * MPS, 4380 bytes)) / RTT
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*
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* For consistency with other parts of the code, X_init is scaled by 2^6.
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*/
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static inline u64 rfc3390_initial_rate(struct sock *sk)
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{
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const u32 mps = dccp_sk(sk)->dccps_mss_cache,
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w_init = clamp(4380U, 2 * mps, 4 * mps);
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return scaled_div(w_init << 6, ccid3_hc_tx_sk(sk)->rtt);
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}
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/**
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* ccid3_update_send_interval - Calculate new t_ipi = s / X
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* This respects the granularity of X (64 * bytes/second) and enforces the
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* scaled minimum of s * 64 / t_mbi = `s' bytes/second as per RFC 3448/4342.
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*/
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static void ccid3_update_send_interval(struct ccid3_hc_tx_sock *hctx)
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{
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if (unlikely(hctx->x <= hctx->s))
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hctx->x = hctx->s;
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hctx->t_ipi = scaled_div32(((u64)hctx->s) << 6, hctx->x);
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}
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static u32 ccid3_hc_tx_idle_rtt(struct ccid3_hc_tx_sock *hctx, ktime_t now)
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{
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u32 delta = ktime_us_delta(now, hctx->t_last_win_count);
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return delta / hctx->rtt;
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}
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/**
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* ccid3_hc_tx_update_x - Update allowed sending rate X
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* @stamp: most recent time if available - can be left NULL.
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* This function tracks draft rfc3448bis, check there for latest details.
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*
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* Note: X and X_recv are both stored in units of 64 * bytes/second, to support
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* fine-grained resolution of sending rates. This requires scaling by 2^6
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* throughout the code. Only X_calc is unscaled (in bytes/second).
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*
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*/
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static void ccid3_hc_tx_update_x(struct sock *sk, ktime_t *stamp)
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{
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struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);
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u64 min_rate = 2 * hctx->x_recv;
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const u64 old_x = hctx->x;
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ktime_t now = stamp ? *stamp : ktime_get_real();
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/*
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* Handle IDLE periods: do not reduce below RFC3390 initial sending rate
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* when idling [RFC 4342, 5.1]. Definition of idling is from rfc3448bis:
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* a sender is idle if it has not sent anything over a 2-RTT-period.
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* For consistency with X and X_recv, min_rate is also scaled by 2^6.
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*/
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if (ccid3_hc_tx_idle_rtt(hctx, now) >= 2) {
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min_rate = rfc3390_initial_rate(sk);
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min_rate = max(min_rate, 2 * hctx->x_recv);
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}
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if (hctx->p > 0) {
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hctx->x = min(((u64)hctx->x_calc) << 6, min_rate);
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} else if (ktime_us_delta(now, hctx->t_ld) - (s64)hctx->rtt >= 0) {
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hctx->x = min(2 * hctx->x, min_rate);
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hctx->x = max(hctx->x,
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scaled_div(((u64)hctx->s) << 6, hctx->rtt));
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hctx->t_ld = now;
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}
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if (hctx->x != old_x) {
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ccid3_pr_debug("X_prev=%u, X_now=%u, X_calc=%u, "
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"X_recv=%u\n", (unsigned)(old_x >> 6),
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(unsigned)(hctx->x >> 6), hctx->x_calc,
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(unsigned)(hctx->x_recv >> 6));
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ccid3_update_send_interval(hctx);
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}
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}
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/*
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* ccid3_hc_tx_measure_packet_size - Measuring the packet size `s' (sec 4.1)
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* @new_len: DCCP payload size in bytes (not used by all methods)
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*/
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static u32 ccid3_hc_tx_measure_packet_size(struct sock *sk, const u16 new_len)
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{
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#if defined(CONFIG_IP_DCCP_CCID3_MEASURE_S_AS_AVG)
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return tfrc_ewma(ccid3_hc_tx_sk(sk)->s, new_len, 9);
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#elif defined(CONFIG_IP_DCCP_CCID3_MEASURE_S_AS_MAX)
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return max(ccid3_hc_tx_sk(sk)->s, new_len);
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#else /* CONFIG_IP_DCCP_CCID3_MEASURE_S_AS_MPS */
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return dccp_sk(sk)->dccps_mss_cache;
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#endif
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}
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/*
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* Update Window Counter using the algorithm from [RFC 4342, 8.1].
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* As elsewhere, RTT > 0 is assumed by using dccp_sample_rtt().
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*/
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static inline void ccid3_hc_tx_update_win_count(struct ccid3_hc_tx_sock *hctx,
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ktime_t now)
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{
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u32 delta = ktime_us_delta(now, hctx->t_last_win_count),
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quarter_rtts = (4 * delta) / hctx->rtt;
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if (quarter_rtts > 0) {
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hctx->t_last_win_count = now;
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hctx->last_win_count += min(quarter_rtts, 5U);
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hctx->last_win_count &= 0xF; /* mod 16 */
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}
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}
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static void ccid3_hc_tx_no_feedback_timer(unsigned long data)
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{
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struct sock *sk = (struct sock *)data;
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struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);
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unsigned long t_nfb = USEC_PER_SEC / 5;
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bh_lock_sock(sk);
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if (sock_owned_by_user(sk)) {
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/* Try again later. */
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/* XXX: set some sensible MIB */
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goto restart_timer;
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}
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ccid3_pr_debug("%s(%p) entry with%s feedback\n", dccp_role(sk), sk,
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hctx->feedback ? "" : "out");
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/* Ignore and do not restart after leaving the established state */
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if ((1 << sk->sk_state) & ~(DCCPF_OPEN | DCCPF_PARTOPEN))
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goto out;
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/* Reset feedback state to "no feedback received" */
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hctx->feedback = false;
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/*
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* Determine new allowed sending rate X as per draft rfc3448bis-00, 4.4
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* RTO is 0 if and only if no feedback has been received yet.
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*/
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if (hctx->t_rto == 0 || hctx->p == 0) {
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/* halve send rate directly */
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hctx->x /= 2;
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ccid3_update_send_interval(hctx);
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} else {
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/*
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* Modify the cached value of X_recv
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*
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* If (X_calc > 2 * X_recv)
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* X_recv = max(X_recv / 2, s / (2 * t_mbi));
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* Else
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* X_recv = X_calc / 4;
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*
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* Note that X_recv is scaled by 2^6 while X_calc is not
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*/
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BUG_ON(hctx->p && !hctx->x_calc);
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if (hctx->x_calc > (hctx->x_recv >> 5))
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hctx->x_recv /= 2;
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else {
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hctx->x_recv = hctx->x_calc;
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hctx->x_recv <<= 4;
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}
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ccid3_hc_tx_update_x(sk, NULL);
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}
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ccid3_pr_debug("Reduced X to %llu/64 bytes/sec\n",
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(unsigned long long)hctx->x);
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/*
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* Set new timeout for the nofeedback timer.
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* See comments in packet_recv() regarding the value of t_RTO.
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*/
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if (unlikely(hctx->t_rto == 0)) /* no feedback received yet */
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t_nfb = TFRC_INITIAL_TIMEOUT;
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else
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t_nfb = max(hctx->t_rto, 2 * hctx->t_ipi);
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restart_timer:
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sk_reset_timer(sk, &hctx->no_feedback_timer,
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jiffies + usecs_to_jiffies(t_nfb));
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out:
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bh_unlock_sock(sk);
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sock_put(sk);
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}
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/**
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* ccid3_hc_tx_send_packet - Delay-based dequeueing of TX packets
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* @skb: next packet candidate to send on @sk
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* This function uses the convention of ccid_packet_dequeue_eval() and
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* returns a millisecond-delay value between 0 and t_mbi = 64000 msec.
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*/
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static int ccid3_hc_tx_send_packet(struct sock *sk, struct sk_buff *skb)
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{
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struct dccp_sock *dp = dccp_sk(sk);
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struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);
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ktime_t now = ktime_get_real();
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s64 delay;
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/*
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* This function is called only for Data and DataAck packets. Sending
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* zero-sized Data(Ack)s is theoretically possible, but for congestion
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* control this case is pathological - ignore it.
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*/
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if (unlikely(skb->len == 0))
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return -EBADMSG;
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if (hctx->s == 0) {
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sk_reset_timer(sk, &hctx->no_feedback_timer, (jiffies +
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usecs_to_jiffies(TFRC_INITIAL_TIMEOUT)));
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hctx->last_win_count = 0;
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hctx->t_last_win_count = now;
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/* Set t_0 for initial packet */
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hctx->t_nom = now;
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/*
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* Use initial RTT sample when available: recommended by erratum
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* to RFC 4342. This implements the initialisation procedure of
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* draft rfc3448bis, section 4.2. Remember, X is scaled by 2^6.
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*/
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if (dp->dccps_syn_rtt) {
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ccid3_pr_debug("SYN RTT = %uus\n", dp->dccps_syn_rtt);
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hctx->rtt = dp->dccps_syn_rtt;
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hctx->x = rfc3390_initial_rate(sk);
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hctx->t_ld = now;
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} else {
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/*
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* Sender does not have RTT sample:
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* - set fallback RTT (RFC 4340, 3.4) since a RTT value
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* is needed in several parts (e.g. window counter);
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* - set sending rate X_pps = 1pps as per RFC 3448, 4.2.
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*/
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hctx->rtt = DCCP_FALLBACK_RTT;
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hctx->x = dp->dccps_mss_cache;
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hctx->x <<= 6;
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}
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/* Compute t_ipi = s / X */
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hctx->s = ccid3_hc_tx_measure_packet_size(sk, skb->len);
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ccid3_update_send_interval(hctx);
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/* Seed value for Oscillation Prevention (sec. 4.5) */
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hctx->r_sqmean = tfrc_scaled_sqrt(hctx->rtt);
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} else {
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delay = ktime_us_delta(hctx->t_nom, now);
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ccid3_pr_debug("delay=%ld\n", (long)delay);
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/*
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* Scheduling of packet transmissions [RFC 3448, 4.6]
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*
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* if (t_now > t_nom - delta)
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* // send the packet now
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* else
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* // send the packet in (t_nom - t_now) milliseconds.
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*/
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if (delay >= TFRC_T_DELTA)
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return (u32)delay / USEC_PER_MSEC;
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ccid3_hc_tx_update_win_count(hctx, now);
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}
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/* prepare to send now (add options etc.) */
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dp->dccps_hc_tx_insert_options = 1;
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DCCP_SKB_CB(skb)->dccpd_ccval = hctx->last_win_count;
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/* set the nominal send time for the next following packet */
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hctx->t_nom = ktime_add_us(hctx->t_nom, hctx->t_ipi);
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return CCID_PACKET_SEND_AT_ONCE;
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}
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static void ccid3_hc_tx_packet_sent(struct sock *sk, unsigned int len)
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{
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struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);
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/* Changes to s will become effective the next time X is computed */
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hctx->s = ccid3_hc_tx_measure_packet_size(sk, len);
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if (tfrc_tx_hist_add(&hctx->hist, dccp_sk(sk)->dccps_gss))
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DCCP_CRIT("packet history - out of memory!");
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}
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static void ccid3_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb)
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{
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struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);
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struct tfrc_tx_hist_entry *acked;
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ktime_t now;
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unsigned long t_nfb;
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u32 r_sample;
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/* we are only interested in ACKs */
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if (!(DCCP_SKB_CB(skb)->dccpd_type == DCCP_PKT_ACK ||
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DCCP_SKB_CB(skb)->dccpd_type == DCCP_PKT_DATAACK))
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return;
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/*
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* Locate the acknowledged packet in the TX history.
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*
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* Returning "entry not found" here can for instance happen when
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* - the host has not sent out anything (e.g. a passive server),
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* - the Ack is outdated (packet with higher Ack number was received),
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* - it is a bogus Ack (for a packet not sent on this connection).
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*/
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acked = tfrc_tx_hist_find_entry(hctx->hist, dccp_hdr_ack_seq(skb));
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if (acked == NULL)
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return;
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/* For the sake of RTT sampling, ignore/remove all older entries */
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tfrc_tx_hist_purge(&acked->next);
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|
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/* Update the moving average for the RTT estimate (RFC 3448, 4.3) */
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now = ktime_get_real();
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r_sample = dccp_sample_rtt(sk, ktime_us_delta(now, acked->stamp));
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hctx->rtt = tfrc_ewma(hctx->rtt, r_sample, 9);
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|
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/*
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* Update allowed sending rate X as per draft rfc3448bis-00, 4.2/3
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*/
|
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if (!hctx->feedback) {
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hctx->feedback = true;
|
|
|
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if (hctx->t_rto == 0) {
|
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/*
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* Initial feedback packet: Larger Initial Windows (4.2)
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*/
|
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hctx->x = rfc3390_initial_rate(sk);
|
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hctx->t_ld = now;
|
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|
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ccid3_update_send_interval(hctx);
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|
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goto done_computing_x;
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} else if (hctx->p == 0) {
|
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/*
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* First feedback after nofeedback timer expiry (4.3)
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*/
|
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goto done_computing_x;
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}
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}
|
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|
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/* Update sending rate (step 4 of [RFC 3448, 4.3]) */
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if (hctx->p > 0)
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hctx->x_calc = tfrc_calc_x(hctx->s, hctx->rtt, hctx->p);
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ccid3_hc_tx_update_x(sk, &now);
|
|
|
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done_computing_x:
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ccid3_pr_debug("%s(%p), RTT=%uus (sample=%uus), s=%u, "
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"p=%u, X_calc=%u, X_recv=%u, X=%u\n",
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dccp_role(sk), sk, hctx->rtt, r_sample,
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hctx->s, hctx->p, hctx->x_calc,
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(unsigned)(hctx->x_recv >> 6),
|
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(unsigned)(hctx->x >> 6));
|
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/*
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* Oscillation Reduction (RFC 3448, 4.5) - modifying t_ipi according to
|
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* RTT changes, multiplying by X/X_inst = sqrt(R_sample)/R_sqmean. This
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* can be useful if few connections share a link, avoiding that buffer
|
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* fill levels (RTT) oscillate as a result of frequent adjustments to X.
|
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* A useful presentation with background information is in
|
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* Joerg Widmer, "Equation-Based Congestion Control",
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* MSc Thesis, University of Mannheim, Germany, 2000
|
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* (sec. 3.6.4), who calls this ISM ("Inter-packet Space Modulation").
|
|
*/
|
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if (do_osc_prev) {
|
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r_sample = tfrc_scaled_sqrt(r_sample);
|
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/*
|
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* The modulation can work in both ways: increase/decrease t_ipi
|
|
* according to long-term increases/decreases of the RTT. The
|
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* former is a useful measure, since it works against queue
|
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* build-up. The latter temporarily increases the sending rate,
|
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* so that buffers fill up more quickly. This in turn causes
|
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* the RTT to increase, so that either later reduction becomes
|
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* necessary or the RTT stays at a very high level. Decreasing
|
|
* t_ipi is therefore not supported.
|
|
* Furthermore, during the initial slow-start phase the RTT
|
|
* naturally increases, where using the algorithm would cause
|
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* delays. Hence it is disabled during the initial slow-start.
|
|
*/
|
|
if (r_sample > hctx->r_sqmean && hctx->p > 0)
|
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hctx->t_ipi = div_u64((u64)hctx->t_ipi * (u64)r_sample,
|
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hctx->r_sqmean);
|
|
hctx->t_ipi = min_t(u32, hctx->t_ipi, TFRC_T_MBI);
|
|
/* update R_sqmean _after_ computing the modulation factor */
|
|
hctx->r_sqmean = tfrc_ewma(hctx->r_sqmean, r_sample, 9);
|
|
}
|
|
|
|
/* 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,
|
|
};
|
|
|
|
module_param(do_osc_prev, bool, 0644);
|
|
MODULE_PARM_DESC(do_osc_prev, "Use Oscillation Prevention (RFC 3448, 4.5)");
|
|
|
|
#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");
|