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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Copyright (c) 2007 The University of Aberdeen, Scotland, UK
* Copyright (c) 2005-7 The University of Waikato, Hamilton, New Zealand.
*
* An implementation of the DCCP protocol
*
* This code has been developed by the University of Waikato WAND
* research group. For further information please see https://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 <acme@conectiva.com.br>.
*
* Copyright (c) 2005 Arnaldo Carvalho de Melo <acme@conectiva.com.br>
*/
#include <linux/string.h>
#include <linux/slab.h>
#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);
swap(h->ring[idx_a], h->ring[idx_b]);
}
/*
* 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(tfr
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