From 57f0f512b273f60d52568b8c6b77e17f5636edc0 Mon Sep 17 00:00:00 2001 From: André Fabian Silva Delgado Date: Wed, 5 Aug 2015 17:04:01 -0300 Subject: Initial import --- net/dccp/ccids/lib/packet_history.c | 449 ++++++++++++++++++++++++++++++++++++ 1 file changed, 449 insertions(+) create mode 100644 net/dccp/ccids/lib/packet_history.c (limited to 'net/dccp/ccids/lib/packet_history.c') diff --git a/net/dccp/ccids/lib/packet_history.c b/net/dccp/ccids/lib/packet_history.c new file mode 100644 index 000000000..08df7a3ac --- /dev/null +++ b/net/dccp/ccids/lib/packet_history.c @@ -0,0 +1,449 @@ +/* + * Copyright (c) 2007 The University of Aberdeen, Scotland, UK + * Copyright (c) 2005-7 The University of Waikato, Hamilton, New Zealand. + * + * An implementation of the DCCP protocol + * + * This code has been developed by the University of Waikato WAND + * research group. For further information please see http://www.wand.net.nz/ + * or e-mail Ian McDonald - ian.mcdonald@jandi.co.nz + * + * This code also uses code from Lulea University, rereleased as GPL by its + * authors: + * Copyright (c) 2003 Nils-Erik Mattsson, Joacim Haggmark, Magnus Erixzon + * + * Changes to meet Linux coding standards, to make it meet latest ccid3 draft + * and to make it work as a loadable module in the DCCP stack written by + * Arnaldo Carvalho de Melo . + * + * Copyright (c) 2005 Arnaldo Carvalho de Melo + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. + */ + +#include +#include +#include "packet_history.h" +#include "../../dccp.h" + +/* + * Transmitter History Routines + */ +static struct kmem_cache *tfrc_tx_hist_slab; + +int __init tfrc_tx_packet_history_init(void) +{ + tfrc_tx_hist_slab = kmem_cache_create("tfrc_tx_hist", + sizeof(struct tfrc_tx_hist_entry), + 0, SLAB_HWCACHE_ALIGN, NULL); + return tfrc_tx_hist_slab == NULL ? -ENOBUFS : 0; +} + +void tfrc_tx_packet_history_exit(void) +{ + if (tfrc_tx_hist_slab != NULL) { + kmem_cache_destroy(tfrc_tx_hist_slab); + tfrc_tx_hist_slab = NULL; + } +} + +int tfrc_tx_hist_add(struct tfrc_tx_hist_entry **headp, u64 seqno) +{ + struct tfrc_tx_hist_entry *entry = kmem_cache_alloc(tfrc_tx_hist_slab, gfp_any()); + + if (entry == NULL) + return -ENOBUFS; + entry->seqno = seqno; + entry->stamp = ktime_get_real(); + entry->next = *headp; + *headp = entry; + return 0; +} + +void tfrc_tx_hist_purge(struct tfrc_tx_hist_entry **headp) +{ + struct tfrc_tx_hist_entry *head = *headp; + + while (head != NULL) { + struct tfrc_tx_hist_entry *next = head->next; + + kmem_cache_free(tfrc_tx_hist_slab, head); + head = next; + } + + *headp = NULL; +} + +/* + * Receiver History Routines + */ +static struct kmem_cache *tfrc_rx_hist_slab; + +int __init tfrc_rx_packet_history_init(void) +{ + tfrc_rx_hist_slab = kmem_cache_create("tfrc_rxh_cache", + sizeof(struct tfrc_rx_hist_entry), + 0, SLAB_HWCACHE_ALIGN, NULL); + return tfrc_rx_hist_slab == NULL ? -ENOBUFS : 0; +} + +void tfrc_rx_packet_history_exit(void) +{ + if (tfrc_rx_hist_slab != NULL) { + kmem_cache_destroy(tfrc_rx_hist_slab); + tfrc_rx_hist_slab = NULL; + } +} + +static inline void tfrc_rx_hist_entry_from_skb(struct tfrc_rx_hist_entry *entry, + const struct sk_buff *skb, + const u64 ndp) +{ + const struct dccp_hdr *dh = dccp_hdr(skb); + + entry->tfrchrx_seqno = DCCP_SKB_CB(skb)->dccpd_seq; + entry->tfrchrx_ccval = dh->dccph_ccval; + entry->tfrchrx_type = dh->dccph_type; + entry->tfrchrx_ndp = ndp; + entry->tfrchrx_tstamp = ktime_get_real(); +} + +void tfrc_rx_hist_add_packet(struct tfrc_rx_hist *h, + const struct sk_buff *skb, + const u64 ndp) +{ + struct tfrc_rx_hist_entry *entry = tfrc_rx_hist_last_rcv(h); + + tfrc_rx_hist_entry_from_skb(entry, skb, ndp); +} + +/* has the packet contained in skb been seen before? */ +int tfrc_rx_hist_duplicate(struct tfrc_rx_hist *h, struct sk_buff *skb) +{ + const u64 seq = DCCP_SKB_CB(skb)->dccpd_seq; + int i; + + if (dccp_delta_seqno(tfrc_rx_hist_loss_prev(h)->tfrchrx_seqno, seq) <= 0) + return 1; + + for (i = 1; i <= h->loss_count; i++) + if (tfrc_rx_hist_entry(h, i)->tfrchrx_seqno == seq) + return 1; + + return 0; +} + +static void tfrc_rx_hist_swap(struct tfrc_rx_hist *h, const u8 a, const u8 b) +{ + const u8 idx_a = tfrc_rx_hist_index(h, a), + idx_b = tfrc_rx_hist_index(h, b); + struct tfrc_rx_hist_entry *tmp = h->ring[idx_a]; + + h->ring[idx_a] = h->ring[idx_b]; + h->ring[idx_b] = tmp; +} + +/* + * Private helper functions for loss detection. + * + * In the descriptions, `Si' refers to the sequence number of entry number i, + * whose NDP count is `Ni' (lower case is used for variables). + * Note: All __xxx_loss functions expect that a test against duplicates has been + * performed already: the seqno of the skb must not be less than the seqno + * of loss_prev; and it must not equal that of any valid history entry. + */ +static void __do_track_loss(struct tfrc_rx_hist *h, struct sk_buff *skb, u64 n1) +{ + u64 s0 = tfrc_rx_hist_loss_prev(h)->tfrchrx_seqno, + s1 = DCCP_SKB_CB(skb)->dccpd_seq; + + if (!dccp_loss_free(s0, s1, n1)) { /* gap between S0 and S1 */ + h->loss_count = 1; + tfrc_rx_hist_entry_from_skb(tfrc_rx_hist_entry(h, 1), skb, n1); + } +} + +static void __one_after_loss(struct tfrc_rx_hist *h, struct sk_buff *skb, u32 n2) +{ + u64 s0 = tfrc_rx_hist_loss_prev(h)->tfrchrx_seqno, + s1 = tfrc_rx_hist_entry(h, 1)->tfrchrx_seqno, + s2 = DCCP_SKB_CB(skb)->dccpd_seq; + + if (likely(dccp_delta_seqno(s1, s2) > 0)) { /* S1 < S2 */ + h->loss_count = 2; + tfrc_rx_hist_entry_from_skb(tfrc_rx_hist_entry(h, 2), skb, n2); + return; + } + + /* S0 < S2 < S1 */ + + if (dccp_loss_free(s0, s2, n2)) { + u64 n1 = tfrc_rx_hist_entry(h, 1)->tfrchrx_ndp; + + if (dccp_loss_free(s2, s1, n1)) { + /* hole is filled: S0, S2, and S1 are consecutive */ + h->loss_count = 0; + h->loss_start = tfrc_rx_hist_index(h, 1); + } else + /* gap between S2 and S1: just update loss_prev */ + tfrc_rx_hist_entry_from_skb(tfrc_rx_hist_loss_prev(h), skb, n2); + + } else { /* gap between S0 and S2 */ + /* + * Reorder history to insert S2 between S0 and S1 + */ + tfrc_rx_hist_swap(h, 0, 3); + h->loss_start = tfrc_rx_hist_index(h, 3); + tfrc_rx_hist_entry_from_skb(tfrc_rx_hist_entry(h, 1), skb, n2); + h->loss_count = 2; + } +} + +/* return 1 if a new loss event has been identified */ +static int __two_after_loss(struct tfrc_rx_hist *h, struct sk_buff *skb, u32 n3) +{ + u64 s0 = tfrc_rx_hist_loss_prev(h)->tfrchrx_seqno, + s1 = tfrc_rx_hist_entry(h, 1)->tfrchrx_seqno, + s2 = tfrc_rx_hist_entry(h, 2)->tfrchrx_seqno, + s3 = DCCP_SKB_CB(skb)->dccpd_seq; + + if (likely(dccp_delta_seqno(s2, s3) > 0)) { /* S2 < S3 */ + h->loss_count = 3; + tfrc_rx_hist_entry_from_skb(tfrc_rx_hist_entry(h, 3), skb, n3); + return 1; + } + + /* S3 < S2 */ + + if (dccp_delta_seqno(s1, s3) > 0) { /* S1 < S3 < S2 */ + /* + * Reorder history to insert S3 between S1 and S2 + */ + tfrc_rx_hist_swap(h, 2, 3); + tfrc_rx_hist_entry_from_skb(tfrc_rx_hist_entry(h, 2), skb, n3); + h->loss_count = 3; + return 1; + } + + /* S0 < S3 < S1 */ + + if (dccp_loss_free(s0, s3, n3)) { + u64 n1 = tfrc_rx_hist_entry(h, 1)->tfrchrx_ndp; + + if (dccp_loss_free(s3, s1, n1)) { + /* hole between S0 and S1 filled by S3 */ + u64 n2 = tfrc_rx_hist_entry(h, 2)->tfrchrx_ndp; + + if (dccp_loss_free(s1, s2, n2)) { + /* entire hole filled by S0, S3, S1, S2 */ + h->loss_start = tfrc_rx_hist_index(h, 2); + h->loss_count = 0; + } else { + /* gap remains between S1 and S2 */ + h->loss_start = tfrc_rx_hist_index(h, 1); + h->loss_count = 1; + } + + } else /* gap exists between S3 and S1, loss_count stays at 2 */ + tfrc_rx_hist_entry_from_skb(tfrc_rx_hist_loss_prev(h), skb, n3); + + return 0; + } + + /* + * The remaining case: S0 < S3 < S1 < S2; gap between S0 and S3 + * Reorder history to insert S3 between S0 and S1. + */ + tfrc_rx_hist_swap(h, 0, 3); + h->loss_start = tfrc_rx_hist_index(h, 3); + tfrc_rx_hist_entry_from_skb(tfrc_rx_hist_entry(h, 1), skb, n3); + h->loss_count = 3; + + return 1; +} + +/* recycle RX history records to continue loss detection if necessary */ +static void __three_after_loss(struct tfrc_rx_hist *h) +{ + /* + * At this stage we know already that there is a gap between S0 and S1 + * (since S0 was the highest sequence number received before detecting + * the loss). To recycle the loss record, it is thus only necessary to + * check for other possible gaps between S1/S2 and between S2/S3. + */ + u64 s1 = tfrc_rx_hist_entry(h, 1)->tfrchrx_seqno, + s2 = tfrc_rx_hist_entry(h, 2)->tfrchrx_seqno, + s3 = tfrc_rx_hist_entry(h, 3)->tfrchrx_seqno; + u64 n2 = tfrc_rx_hist_entry(h, 2)->tfrchrx_ndp, + n3 = tfrc_rx_hist_entry(h, 3)->tfrchrx_ndp; + + if (dccp_loss_free(s1, s2, n2)) { + + if (dccp_loss_free(s2, s3, n3)) { + /* no gap between S2 and S3: entire hole is filled */ + h->loss_start = tfrc_rx_hist_index(h, 3); + h->loss_count = 0; + } else { + /* gap between S2 and S3 */ + h->loss_start = tfrc_rx_hist_index(h, 2); + h->loss_count = 1; + } + + } else { /* gap between S1 and S2 */ + h->loss_start = tfrc_rx_hist_index(h, 1); + h->loss_count = 2; + } +} + +/** + * tfrc_rx_handle_loss - Loss detection and further processing + * @h: The non-empty RX history object + * @lh: Loss Intervals database to update + * @skb: Currently received packet + * @ndp: The NDP count belonging to @skb + * @calc_first_li: Caller-dependent computation of first loss interval in @lh + * @sk: Used by @calc_first_li (see tfrc_lh_interval_add) + * + * Chooses action according to pending loss, updates LI database when a new + * loss was detected, and does required post-processing. Returns 1 when caller + * should send feedback, 0 otherwise. + * Since it also takes care of reordering during loss detection and updates the + * records accordingly, the caller should not perform any more RX history + * operations when loss_count is greater than 0 after calling this function. + */ +int tfrc_rx_handle_loss(struct tfrc_rx_hist *h, + struct tfrc_loss_hist *lh, + struct sk_buff *skb, const u64 ndp, + u32 (*calc_first_li)(struct sock *), struct sock *sk) +{ + int is_new_loss = 0; + + if (h->loss_count == 0) { + __do_track_loss(h, skb, ndp); + } else if (h->loss_count == 1) { + __one_after_loss(h, skb, ndp); + } else if (h->loss_count != 2) { + DCCP_BUG("invalid loss_count %d", h->loss_count); + } else if (__two_after_loss(h, skb, ndp)) { + /* + * Update Loss Interval database and recycle RX records + */ + is_new_loss = tfrc_lh_interval_add(lh, h, calc_first_li, sk); + __three_after_loss(h); + } + return is_new_loss; +} + +int tfrc_rx_hist_alloc(struct tfrc_rx_hist *h) +{ + int i; + + for (i = 0; i <= TFRC_NDUPACK; i++) { + h->ring[i] = kmem_cache_alloc(tfrc_rx_hist_slab, GFP_ATOMIC); + if (h->ring[i] == NULL) + goto out_free; + } + + h->loss_count = h->loss_start = 0; + return 0; + +out_free: + while (i-- != 0) { + kmem_cache_free(tfrc_rx_hist_slab, h->ring[i]); + h->ring[i] = NULL; + } + return -ENOBUFS; +} + +void tfrc_rx_hist_purge(struct tfrc_rx_hist *h) +{ + int i; + + for (i = 0; i <= TFRC_NDUPACK; ++i) + if (h->ring[i] != NULL) { + kmem_cache_free(tfrc_rx_hist_slab, h->ring[i]); + h->ring[i] = NULL; + } +} + +/** + * tfrc_rx_hist_rtt_last_s - reference entry to compute RTT samples against + */ +static inline struct tfrc_rx_hist_entry * + tfrc_rx_hist_rtt_last_s(const struct tfrc_rx_hist *h) +{ + return h->ring[0]; +} + +/** + * tfrc_rx_hist_rtt_prev_s - previously suitable (wrt rtt_last_s) RTT-sampling entry + */ +static inline struct tfrc_rx_hist_entry * + tfrc_rx_hist_rtt_prev_s(const struct tfrc_rx_hist *h) +{ + return h->ring[h->rtt_sample_prev]; +} + +/** + * tfrc_rx_hist_sample_rtt - Sample RTT from timestamp / CCVal + * Based on ideas presented in RFC 4342, 8.1. Returns 0 if it was not able + * to compute a sample with given data - calling function should check this. + */ +u32 tfrc_rx_hist_sample_rtt(struct tfrc_rx_hist *h, const struct sk_buff *skb) +{ + u32 sample = 0, + delta_v = SUB16(dccp_hdr(skb)->dccph_ccval, + tfrc_rx_hist_rtt_last_s(h)->tfrchrx_ccval); + + if (delta_v < 1 || delta_v > 4) { /* unsuitable CCVal delta */ + 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; +} -- cgit v1.2.3-54-g00ecf