488 lines
14 KiB
C
488 lines
14 KiB
C
/*
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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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*
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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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* or e-mail Ian McDonald - ian.mcdonald@jandi.co.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 <linux/string.h>
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#include <linux/slab.h>
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#include "packet_history.h"
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#include "../../dccp.h"
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/**
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* tfrc_tx_hist_entry - Simple singly-linked TX history list
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* @next: next oldest entry (LIFO order)
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* @seqno: sequence number of this entry
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* @stamp: send time of packet with sequence number @seqno
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*/
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struct tfrc_tx_hist_entry {
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struct tfrc_tx_hist_entry *next;
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u64 seqno;
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ktime_t stamp;
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};
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/*
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* Transmitter History Routines
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*/
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static struct kmem_cache *tfrc_tx_hist_slab;
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int __init tfrc_tx_packet_history_init(void)
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{
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tfrc_tx_hist_slab = kmem_cache_create("tfrc_tx_hist",
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sizeof(struct tfrc_tx_hist_entry),
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0, SLAB_HWCACHE_ALIGN, NULL);
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return tfrc_tx_hist_slab == NULL ? -ENOBUFS : 0;
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}
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void tfrc_tx_packet_history_exit(void)
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{
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if (tfrc_tx_hist_slab != NULL) {
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kmem_cache_destroy(tfrc_tx_hist_slab);
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tfrc_tx_hist_slab = NULL;
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}
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}
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static struct tfrc_tx_hist_entry *
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tfrc_tx_hist_find_entry(struct tfrc_tx_hist_entry *head, u64 seqno)
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{
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while (head != NULL && head->seqno != seqno)
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head = head->next;
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return head;
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}
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int tfrc_tx_hist_add(struct tfrc_tx_hist_entry **headp, u64 seqno)
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{
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struct tfrc_tx_hist_entry *entry = kmem_cache_alloc(tfrc_tx_hist_slab, gfp_any());
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if (entry == NULL)
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return -ENOBUFS;
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entry->seqno = seqno;
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entry->stamp = ktime_get_real();
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entry->next = *headp;
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*headp = entry;
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return 0;
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}
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void tfrc_tx_hist_purge(struct tfrc_tx_hist_entry **headp)
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{
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struct tfrc_tx_hist_entry *head = *headp;
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while (head != NULL) {
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struct tfrc_tx_hist_entry *next = head->next;
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kmem_cache_free(tfrc_tx_hist_slab, head);
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head = next;
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}
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*headp = NULL;
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}
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u32 tfrc_tx_hist_rtt(struct tfrc_tx_hist_entry *head, const u64 seqno,
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const ktime_t now)
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{
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u32 rtt = 0;
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struct tfrc_tx_hist_entry *packet = tfrc_tx_hist_find_entry(head, seqno);
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if (packet != NULL) {
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rtt = ktime_us_delta(now, packet->stamp);
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/*
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* Garbage-collect older (irrelevant) entries:
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*/
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tfrc_tx_hist_purge(&packet->next);
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}
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return rtt;
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}
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/*
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* Receiver History Routines
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*/
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static struct kmem_cache *tfrc_rx_hist_slab;
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int __init tfrc_rx_packet_history_init(void)
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{
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tfrc_rx_hist_slab = kmem_cache_create("tfrc_rxh_cache",
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sizeof(struct tfrc_rx_hist_entry),
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0, SLAB_HWCACHE_ALIGN, NULL);
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return tfrc_rx_hist_slab == NULL ? -ENOBUFS : 0;
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}
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void tfrc_rx_packet_history_exit(void)
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{
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if (tfrc_rx_hist_slab != NULL) {
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kmem_cache_destroy(tfrc_rx_hist_slab);
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tfrc_rx_hist_slab = NULL;
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}
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}
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static inline void tfrc_rx_hist_entry_from_skb(struct tfrc_rx_hist_entry *entry,
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const struct sk_buff *skb,
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const u64 ndp)
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{
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const struct dccp_hdr *dh = dccp_hdr(skb);
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entry->tfrchrx_seqno = DCCP_SKB_CB(skb)->dccpd_seq;
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entry->tfrchrx_ccval = dh->dccph_ccval;
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entry->tfrchrx_type = dh->dccph_type;
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entry->tfrchrx_ndp = ndp;
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entry->tfrchrx_tstamp = ktime_get_real();
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}
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void tfrc_rx_hist_add_packet(struct tfrc_rx_hist *h,
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const struct sk_buff *skb,
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const u64 ndp)
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{
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struct tfrc_rx_hist_entry *entry = tfrc_rx_hist_last_rcv(h);
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tfrc_rx_hist_entry_from_skb(entry, skb, ndp);
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}
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/* has the packet contained in skb been seen before? */
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int tfrc_rx_hist_duplicate(struct tfrc_rx_hist *h, struct sk_buff *skb)
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{
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const u64 seq = DCCP_SKB_CB(skb)->dccpd_seq;
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int i;
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if (dccp_delta_seqno(tfrc_rx_hist_loss_prev(h)->tfrchrx_seqno, seq) <= 0)
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return 1;
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for (i = 1; i <= h->loss_count; i++)
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if (tfrc_rx_hist_entry(h, i)->tfrchrx_seqno == seq)
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return 1;
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return 0;
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}
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static void tfrc_rx_hist_swap(struct tfrc_rx_hist *h, const u8 a, const u8 b)
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{
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const u8 idx_a = tfrc_rx_hist_index(h, a),
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idx_b = tfrc_rx_hist_index(h, b);
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struct tfrc_rx_hist_entry *tmp = h->ring[idx_a];
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h->ring[idx_a] = h->ring[idx_b];
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h->ring[idx_b] = tmp;
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}
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/*
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* Private helper functions for loss detection.
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*
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* In the descriptions, `Si' refers to the sequence number of entry number i,
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* whose NDP count is `Ni' (lower case is used for variables).
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* Note: All __xxx_loss functions expect that a test against duplicates has been
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* performed already: the seqno of the skb must not be less than the seqno
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* of loss_prev; and it must not equal that of any valid history entry.
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*/
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static void __do_track_loss(struct tfrc_rx_hist *h, struct sk_buff *skb, u64 n1)
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{
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u64 s0 = tfrc_rx_hist_loss_prev(h)->tfrchrx_seqno,
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s1 = DCCP_SKB_CB(skb)->dccpd_seq;
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if (!dccp_loss_free(s0, s1, n1)) { /* gap between S0 and S1 */
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h->loss_count = 1;
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tfrc_rx_hist_entry_from_skb(tfrc_rx_hist_entry(h, 1), skb, n1);
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}
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}
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static void __one_after_loss(struct tfrc_rx_hist *h, struct sk_buff *skb, u32 n2)
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{
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u64 s0 = tfrc_rx_hist_loss_prev(h)->tfrchrx_seqno,
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s1 = tfrc_rx_hist_entry(h, 1)->tfrchrx_seqno,
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s2 = DCCP_SKB_CB(skb)->dccpd_seq;
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if (likely(dccp_delta_seqno(s1, s2) > 0)) { /* S1 < S2 */
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h->loss_count = 2;
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tfrc_rx_hist_entry_from_skb(tfrc_rx_hist_entry(h, 2), skb, n2);
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return;
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}
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/* S0 < S2 < S1 */
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if (dccp_loss_free(s0, s2, n2)) {
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u64 n1 = tfrc_rx_hist_entry(h, 1)->tfrchrx_ndp;
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if (dccp_loss_free(s2, s1, n1)) {
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/* hole is filled: S0, S2, and S1 are consecutive */
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h->loss_count = 0;
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h->loss_start = tfrc_rx_hist_index(h, 1);
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} else
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/* gap between S2 and S1: just update loss_prev */
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tfrc_rx_hist_entry_from_skb(tfrc_rx_hist_loss_prev(h), skb, n2);
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} else { /* gap between S0 and S2 */
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/*
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* Reorder history to insert S2 between S0 and S1
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*/
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tfrc_rx_hist_swap(h, 0, 3);
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h->loss_start = tfrc_rx_hist_index(h, 3);
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tfrc_rx_hist_entry_from_skb(tfrc_rx_hist_entry(h, 1), skb, n2);
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h->loss_count = 2;
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}
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}
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/* return 1 if a new loss event has been identified */
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static int __two_after_loss(struct tfrc_rx_hist *h, struct sk_buff *skb, u32 n3)
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{
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u64 s0 = tfrc_rx_hist_loss_prev(h)->tfrchrx_seqno,
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s1 = tfrc_rx_hist_entry(h, 1)->tfrchrx_seqno,
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s2 = tfrc_rx_hist_entry(h, 2)->tfrchrx_seqno,
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s3 = DCCP_SKB_CB(skb)->dccpd_seq;
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if (likely(dccp_delta_seqno(s2, s3) > 0)) { /* S2 < S3 */
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h->loss_count = 3;
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tfrc_rx_hist_entry_from_skb(tfrc_rx_hist_entry(h, 3), skb, n3);
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return 1;
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}
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/* S3 < S2 */
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if (dccp_delta_seqno(s1, s3) > 0) { /* S1 < S3 < S2 */
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/*
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* Reorder history to insert S3 between S1 and S2
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*/
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tfrc_rx_hist_swap(h, 2, 3);
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tfrc_rx_hist_entry_from_skb(tfrc_rx_hist_entry(h, 2), skb, n3);
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h->loss_count = 3;
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return 1;
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}
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/* S0 < S3 < S1 */
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if (dccp_loss_free(s0, s3, n3)) {
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u64 n1 = tfrc_rx_hist_entry(h, 1)->tfrchrx_ndp;
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if (dccp_loss_free(s3, s1, n1)) {
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/* hole between S0 and S1 filled by S3 */
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u64 n2 = tfrc_rx_hist_entry(h, 2)->tfrchrx_ndp;
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if (dccp_loss_free(s1, s2, n2)) {
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/* entire hole filled by S0, S3, S1, S2 */
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h->loss_start = tfrc_rx_hist_index(h, 2);
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h->loss_count = 0;
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} else {
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/* gap remains between S1 and S2 */
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h->loss_start = tfrc_rx_hist_index(h, 1);
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h->loss_count = 1;
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}
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} else /* gap exists between S3 and S1, loss_count stays at 2 */
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tfrc_rx_hist_entry_from_skb(tfrc_rx_hist_loss_prev(h), skb, n3);
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return 0;
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}
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/*
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* The remaining case: S0 < S3 < S1 < S2; gap between S0 and S3
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* Reorder history to insert S3 between S0 and S1.
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*/
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tfrc_rx_hist_swap(h, 0, 3);
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h->loss_start = tfrc_rx_hist_index(h, 3);
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tfrc_rx_hist_entry_from_skb(tfrc_rx_hist_entry(h, 1), skb, n3);
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h->loss_count = 3;
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return 1;
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}
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/* recycle RX history records to continue loss detection if necessary */
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static void __three_after_loss(struct tfrc_rx_hist *h)
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{
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/*
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* At this stage we know already that there is a gap between S0 and S1
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* (since S0 was the highest sequence number received before detecting
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* the loss). To recycle the loss record, it is thus only necessary to
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* check for other possible gaps between S1/S2 and between S2/S3.
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*/
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u64 s1 = tfrc_rx_hist_entry(h, 1)->tfrchrx_seqno,
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s2 = tfrc_rx_hist_entry(h, 2)->tfrchrx_seqno,
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s3 = tfrc_rx_hist_entry(h, 3)->tfrchrx_seqno;
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u64 n2 = tfrc_rx_hist_entry(h, 2)->tfrchrx_ndp,
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n3 = tfrc_rx_hist_entry(h, 3)->tfrchrx_ndp;
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if (dccp_loss_free(s1, s2, n2)) {
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if (dccp_loss_free(s2, s3, n3)) {
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/* no gap between S2 and S3: entire hole is filled */
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h->loss_start = tfrc_rx_hist_index(h, 3);
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h->loss_count = 0;
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} else {
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/* gap between S2 and S3 */
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h->loss_start = tfrc_rx_hist_index(h, 2);
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h->loss_count = 1;
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}
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} else { /* gap between S1 and S2 */
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h->loss_start = tfrc_rx_hist_index(h, 1);
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h->loss_count = 2;
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}
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}
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/**
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* tfrc_rx_handle_loss - Loss detection and further processing
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* @h: The non-empty RX history object
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* @lh: Loss Intervals database to update
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* @skb: Currently received packet
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* @ndp: The NDP count belonging to @skb
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* @calc_first_li: Caller-dependent computation of first loss interval in @lh
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* @sk: Used by @calc_first_li (see tfrc_lh_interval_add)
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* Chooses action according to pending loss, updates LI database when a new
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* loss was detected, and does required post-processing. Returns 1 when caller
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* should send feedback, 0 otherwise.
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* Since it also takes care of reordering during loss detection and updates the
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* records accordingly, the caller should not perform any more RX history
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* operations when loss_count is greater than 0 after calling this function.
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*/
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int tfrc_rx_handle_loss(struct tfrc_rx_hist *h,
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struct tfrc_loss_hist *lh,
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struct sk_buff *skb, const u64 ndp,
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u32 (*calc_first_li)(struct sock *), struct sock *sk)
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{
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int is_new_loss = 0;
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if (h->loss_count == 0) {
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__do_track_loss(h, skb, ndp);
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} else if (h->loss_count == 1) {
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__one_after_loss(h, skb, ndp);
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} else if (h->loss_count != 2) {
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DCCP_BUG("invalid loss_count %d", h->loss_count);
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} else if (__two_after_loss(h, skb, ndp)) {
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/*
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* Update Loss Interval database and recycle RX records
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*/
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is_new_loss = tfrc_lh_interval_add(lh, h, calc_first_li, sk);
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__three_after_loss(h);
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}
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return is_new_loss;
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}
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int tfrc_rx_hist_alloc(struct tfrc_rx_hist *h)
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{
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int i;
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for (i = 0; i <= TFRC_NDUPACK; i++) {
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h->ring[i] = kmem_cache_alloc(tfrc_rx_hist_slab, GFP_ATOMIC);
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if (h->ring[i] == NULL)
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goto out_free;
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}
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h->loss_count = h->loss_start = 0;
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return 0;
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out_free:
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while (i-- != 0) {
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kmem_cache_free(tfrc_rx_hist_slab, h->ring[i]);
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h->ring[i] = NULL;
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}
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return -ENOBUFS;
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}
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void tfrc_rx_hist_purge(struct tfrc_rx_hist *h)
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{
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int i;
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for (i = 0; i <= TFRC_NDUPACK; ++i)
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if (h->ring[i] != NULL) {
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kmem_cache_free(tfrc_rx_hist_slab, h->ring[i]);
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h->ring[i] = NULL;
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}
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}
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/**
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* tfrc_rx_hist_rtt_last_s - reference entry to compute RTT samples against
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*/
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static inline struct tfrc_rx_hist_entry *
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tfrc_rx_hist_rtt_last_s(const struct tfrc_rx_hist *h)
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{
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return h->ring[0];
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}
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/**
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* tfrc_rx_hist_rtt_prev_s: previously suitable (wrt rtt_last_s) RTT-sampling entry
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*/
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static inline struct tfrc_rx_hist_entry *
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tfrc_rx_hist_rtt_prev_s(const struct tfrc_rx_hist *h)
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{
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return h->ring[h->rtt_sample_prev];
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}
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/**
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* tfrc_rx_hist_sample_rtt - Sample RTT from timestamp / CCVal
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* Based on ideas presented in RFC 4342, 8.1. Returns 0 if it was not able
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* to compute a sample with given data - calling function should check this.
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*/
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u32 tfrc_rx_hist_sample_rtt(struct tfrc_rx_hist *h, const struct sk_buff *skb)
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{
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u32 sample = 0,
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delta_v = SUB16(dccp_hdr(skb)->dccph_ccval,
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tfrc_rx_hist_rtt_last_s(h)->tfrchrx_ccval);
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if (delta_v < 1 || delta_v > 4) { /* unsuitable CCVal delta */
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if (h->rtt_sample_prev == 2) { /* previous candidate stored */
|
|
sample = SUB16(tfrc_rx_hist_rtt_prev_s(h)->tfrchrx_ccval,
|
|
tfrc_rx_hist_rtt_last_s(h)->tfrchrx_ccval);
|
|
if (sample)
|
|
sample = 4 / sample *
|
|
ktime_us_delta(tfrc_rx_hist_rtt_prev_s(h)->tfrchrx_tstamp,
|
|
tfrc_rx_hist_rtt_last_s(h)->tfrchrx_tstamp);
|
|
else /*
|
|
* FIXME: This condition is in principle not
|
|
* possible but occurs when CCID is used for
|
|
* two-way data traffic. I have tried to trace
|
|
* it, but the cause does not seem to be here.
|
|
*/
|
|
DCCP_BUG("please report to dccp@vger.kernel.org"
|
|
" => prev = %u, last = %u",
|
|
tfrc_rx_hist_rtt_prev_s(h)->tfrchrx_ccval,
|
|
tfrc_rx_hist_rtt_last_s(h)->tfrchrx_ccval);
|
|
} else if (delta_v < 1) {
|
|
h->rtt_sample_prev = 1;
|
|
goto keep_ref_for_next_time;
|
|
}
|
|
|
|
} else if (delta_v == 4) /* optimal match */
|
|
sample = ktime_to_us(net_timedelta(tfrc_rx_hist_rtt_last_s(h)->tfrchrx_tstamp));
|
|
else { /* suboptimal match */
|
|
h->rtt_sample_prev = 2;
|
|
goto keep_ref_for_next_time;
|
|
}
|
|
|
|
if (unlikely(sample > DCCP_SANE_RTT_MAX)) {
|
|
DCCP_WARN("RTT sample %u too large, using max\n", sample);
|
|
sample = DCCP_SANE_RTT_MAX;
|
|
}
|
|
|
|
h->rtt_sample_prev = 0; /* use current entry as next reference */
|
|
keep_ref_for_next_time:
|
|
|
|
return sample;
|
|
}
|