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// SPDX-License-Identifier: GPL-2.0-or-later |
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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 <[email protected]> |
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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 https://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 <[email protected]>. |
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* |
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* Copyright (c) 2005 Arnaldo Carvalho de Melo <[email protected]> |
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*/ |
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#include "../dccp.h" |
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#include "ccid3.h" |
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|
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#include <asm/unaligned.h> |
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#ifdef CONFIG_IP_DCCP_CCID3_DEBUG |
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static bool 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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/* |
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* Transmitter Half-Connection Routines |
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*/ |
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#ifdef CONFIG_IP_DCCP_CCID3_DEBUG |
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static const char *ccid3_tx_state_name(enum ccid3_hc_tx_states state) |
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{ |
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static const char *const ccid3_state_names[] = { |
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[TFRC_SSTATE_NO_SENT] = "NO_SENT", |
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[TFRC_SSTATE_NO_FBACK] = "NO_FBACK", |
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[TFRC_SSTATE_FBACK] = "FBACK", |
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}; |
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|
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return ccid3_state_names[state]; |
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} |
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#endif |
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static void ccid3_hc_tx_set_state(struct sock *sk, |
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enum ccid3_hc_tx_states state) |
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{ |
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struct ccid3_hc_tx_sock *hc = ccid3_hc_tx_sk(sk); |
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enum ccid3_hc_tx_states oldstate = hc->tx_state; |
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ccid3_pr_debug("%s(%p) %-8.8s -> %s\n", |
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dccp_role(sk), sk, ccid3_tx_state_name(oldstate), |
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ccid3_tx_state_name(state)); |
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WARN_ON(state == oldstate); |
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hc->tx_state = state; |
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} |
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|
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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 * s, max(2 * s, 4380 bytes)) / RTT |
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* |
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* Note that RFC 3390 uses MSS, RFC 4342 refers to RFC 3390, and rfc3448bis |
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* (rev-02) clarifies the use of RFC 3390 with regard to the above formula. |
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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 struct ccid3_hc_tx_sock *hc = ccid3_hc_tx_sk(sk); |
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const __u32 w_init = clamp_t(__u32, 4380U, 2 * hc->tx_s, 4 * hc->tx_s); |
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return scaled_div(w_init << 6, hc->tx_rtt); |
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} |
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/** |
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* ccid3_update_send_interval - Calculate new t_ipi = s / X_inst |
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* @hc: socket to have the send interval updated |
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* |
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* This respects the granularity of X_inst (64 * bytes/second). |
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*/ |
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static void ccid3_update_send_interval(struct ccid3_hc_tx_sock *hc) |
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{ |
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hc->tx_t_ipi = scaled_div32(((u64)hc->tx_s) << 6, hc->tx_x); |
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DCCP_BUG_ON(hc->tx_t_ipi == 0); |
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ccid3_pr_debug("t_ipi=%u, s=%u, X=%u\n", hc->tx_t_ipi, |
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hc->tx_s, (unsigned int)(hc->tx_x >> 6)); |
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} |
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static u32 ccid3_hc_tx_idle_rtt(struct ccid3_hc_tx_sock *hc, ktime_t now) |
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{ |
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u32 delta = ktime_us_delta(now, hc->tx_t_last_win_count); |
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return delta / hc->tx_rtt; |
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} |
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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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* @sk: socket to be updated |
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* @stamp: most recent time if available - can be left NULL. |
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* |
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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 *hc = ccid3_hc_tx_sk(sk); |
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__u64 min_rate = 2 * hc->tx_x_recv; |
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const __u64 old_x = hc->tx_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(hc, now) >= 2) { |
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min_rate = rfc3390_initial_rate(sk); |
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min_rate = max(min_rate, 2 * hc->tx_x_recv); |
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} |
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if (hc->tx_p > 0) { |
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hc->tx_x = min(((__u64)hc->tx_x_calc) << 6, min_rate); |
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hc->tx_x = max(hc->tx_x, (((__u64)hc->tx_s) << 6) / TFRC_T_MBI); |
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} else if (ktime_us_delta(now, hc->tx_t_ld) - (s64)hc->tx_rtt >= 0) { |
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hc->tx_x = min(2 * hc->tx_x, min_rate); |
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hc->tx_x = max(hc->tx_x, |
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scaled_div(((__u64)hc->tx_s) << 6, hc->tx_rtt)); |
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hc->tx_t_ld = now; |
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} |
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if (hc->tx_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 int)(old_x >> 6), |
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(unsigned int)(hc->tx_x >> 6), hc->tx_x_calc, |
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(unsigned int)(hc->tx_x_recv >> 6)); |
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ccid3_update_send_interval(hc); |
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} |
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} |
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/** |
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* ccid3_hc_tx_update_s - Track the mean packet size `s' |
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* @hc: socket to be updated |
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* @len: DCCP packet payload size in bytes |
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* |
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* cf. RFC 4342, 5.3 and RFC 3448, 4.1 |
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*/ |
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static inline void ccid3_hc_tx_update_s(struct ccid3_hc_tx_sock *hc, int len) |
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{ |
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const u16 old_s = hc->tx_s; |
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hc->tx_s = tfrc_ewma(hc->tx_s, len, 9); |
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if (hc->tx_s != old_s) |
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ccid3_update_send_interval(hc); |
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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 *hc, |
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ktime_t now) |
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{ |
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u32 delta = ktime_us_delta(now, hc->tx_t_last_win_count), |
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quarter_rtts = (4 * delta) / hc->tx_rtt; |
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if (quarter_rtts > 0) { |
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hc->tx_t_last_win_count = now; |
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hc->tx_last_win_count += min(quarter_rtts, 5U); |
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hc->tx_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(struct timer_list *t) |
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{ |
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struct ccid3_hc_tx_sock *hc = from_timer(hc, t, tx_no_feedback_timer); |
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struct sock *sk = hc->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, state=%s) - entry\n", dccp_role(sk), sk, |
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ccid3_tx_state_name(hc->tx_state)); |
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|
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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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if (hc->tx_state == TFRC_SSTATE_FBACK) |
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ccid3_hc_tx_set_state(sk, TFRC_SSTATE_NO_FBACK); |
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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 (hc->tx_t_rto == 0 || hc->tx_p == 0) { |
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/* halve send rate directly */ |
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hc->tx_x = max(hc->tx_x / 2, |
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(((__u64)hc->tx_s) << 6) / TFRC_T_MBI); |
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ccid3_update_send_interval(hc); |
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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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if (hc->tx_x_calc > (hc->tx_x_recv >> 5)) |
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hc->tx_x_recv = |
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max(hc->tx_x_recv / 2, |
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(((__u64)hc->tx_s) << 6) / (2*TFRC_T_MBI)); |
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else { |
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hc->tx_x_recv = hc->tx_x_calc; |
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hc->tx_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)hc->tx_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(hc->tx_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(hc->tx_t_rto, 2 * hc->tx_t_ipi); |
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restart_timer: |
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sk_reset_timer(sk, &hc->tx_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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* @sk: socket to send packet from |
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* @skb: next packet candidate to send on @sk |
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* |
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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 *hc = 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 (hc->tx_state == TFRC_SSTATE_NO_SENT) { |
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sk_reset_timer(sk, &hc->tx_no_feedback_timer, (jiffies + |
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usecs_to_jiffies(TFRC_INITIAL_TIMEOUT))); |
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hc->tx_last_win_count = 0; |
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hc->tx_t_last_win_count = now; |
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/* Set t_0 for initial packet */ |
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hc->tx_t_nom = now; |
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hc->tx_s = skb->len; |
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|
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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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hc->tx_rtt = dp->dccps_syn_rtt; |
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hc->tx_x = rfc3390_initial_rate(sk); |
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hc->tx_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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hc->tx_rtt = DCCP_FALLBACK_RTT; |
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hc->tx_x = hc->tx_s; |
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hc->tx_x <<= 6; |
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} |
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ccid3_update_send_interval(hc); |
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ccid3_hc_tx_set_state(sk, TFRC_SSTATE_NO_FBACK); |
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} else { |
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delay = ktime_us_delta(hc->tx_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 5348, 8.3) |
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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(hc, now); |
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} |
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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 = hc->tx_last_win_count; |
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|
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/* set the nominal send time for the next following packet */ |
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hc->tx_t_nom = ktime_add_us(hc->tx_t_nom, hc->tx_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 *hc = ccid3_hc_tx_sk(sk); |
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|
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ccid3_hc_tx_update_s(hc, len); |
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if (tfrc_tx_hist_add(&hc->tx_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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|
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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 *hc = 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(hc->tx_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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hc->tx_rtt = tfrc_ewma(hc->tx_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 (hc->tx_state == TFRC_SSTATE_NO_FBACK) { |
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ccid3_hc_tx_set_state(sk, TFRC_SSTATE_FBACK); |
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|
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if (hc->tx_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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hc->tx_x = rfc3390_initial_rate(sk); |
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hc->tx_t_ld = now; |
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ccid3_update_send_interval(hc); |
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|
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goto done_computing_x; |
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} else if (hc->tx_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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/* Update sending rate (step 4 of [RFC 3448, 4.3]) */ |
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if (hc->tx_p > 0) |
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hc->tx_x_calc = tfrc_calc_x(hc->tx_s, hc->tx_rtt, hc->tx_p); |
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ccid3_hc_tx_update_x(sk, &now); |
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|
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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, hc->tx_rtt, r_sample, |
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hc->tx_s, hc->tx_p, hc->tx_x_calc, |
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(unsigned int)(hc->tx_x_recv >> 6), |
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(unsigned int)(hc->tx_x >> 6)); |
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|
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/* unschedule no feedback timer */ |
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sk_stop_timer(sk, &hc->tx_no_feedback_timer); |
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|
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/* |
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* As we have calculated new ipi, delta, t_nom it is possible |
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* that we now can send a packet, so wake up dccp_wait_for_ccid |
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*/ |
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sk->sk_write_space(sk); |
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|
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/* |
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* Update timeout interval for the nofeedback timer. In order to control |
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* rate halving on networks with very low RTTs (<= 1 ms), use per-route |
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* tunable RTAX_RTO_MIN value as the lower bound. |
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*/ |
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hc->tx_t_rto = max_t(u32, 4 * hc->tx_rtt, |
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USEC_PER_SEC/HZ * tcp_rto_min(sk)); |
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/* |
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* Schedule no feedback timer to expire in |
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* max(t_RTO, 2 * s/X) = max(t_RTO, 2 * t_ipi) |
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*/ |
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t_nfb = max(hc->tx_t_rto, 2 * hc->tx_t_ipi); |
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|
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ccid3_pr_debug("%s(%p), Scheduled no feedback timer to " |
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"expire in %lu jiffies (%luus)\n", |
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dccp_role(sk), sk, usecs_to_jiffies(t_nfb), t_nfb); |
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|
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sk_reset_timer(sk, &hc->tx_no_feedback_timer, |
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jiffies + usecs_to_jiffies(t_nfb)); |
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} |
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|
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static int ccid3_hc_tx_parse_options(struct sock *sk, u8 packet_type, |
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u8 option, u8 *optval, u8 optlen) |
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{ |
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struct ccid3_hc_tx_sock *hc = ccid3_hc_tx_sk(sk); |
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__be32 opt_val; |
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|
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switch (option) { |
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case TFRC_OPT_RECEIVE_RATE: |
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case TFRC_OPT_LOSS_EVENT_RATE: |
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/* Must be ignored on Data packets, cf. RFC 4342 8.3 and 8.5 */ |
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if (packet_type == DCCP_PKT_DATA) |
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break; |
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if (unlikely(optlen != 4)) { |
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DCCP_WARN("%s(%p), invalid len %d for %u\n", |
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dccp_role(sk), sk, optlen, option); |
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return -EINVAL; |
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} |
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opt_val = ntohl(get_unaligned((__be32 *)optval)); |
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|
|
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; |
|
fallthrough; |
|
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] |
|
* @sk: socket to calculate loss interval for |
|
* |
|
* 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
|
|
|