packet_history.h

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/*
 *  Packet RX/TX history data structures and routines for TFRC-based protocols.
 *
 *  Copyright (c) 2007   The University of Aberdeen, Scotland, UK
 *  Copyright (c) 2005-6 The University of Waikato, Hamilton, New Zealand.
 *
 *  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 - [email protected]
 *
 *  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 <[email protected]>.
 *
 *  Copyright (c) 2005 Arnaldo Carvalho de Melo <[email protected]>
 *
 *  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.
 */

#ifndef _DCCP_PKT_HIST_
#define _DCCP_PKT_HIST_

#include <linux/list.h>
#include <linux/slab.h>
#include "tfrc.h"

struct tfrc_tx_hist_entry {
    struct tfrc_tx_hist_entry *next;
    u64           seqno;
    ktime_t           stamp;
};

static inline struct tfrc_tx_hist_entry *
    tfrc_tx_hist_find_entry(struct tfrc_tx_hist_entry *head, u64 seqno)
{
    while (head != NULL && head->seqno != seqno)
        head = head->next;
    return head;
}

extern int  tfrc_tx_hist_add(struct tfrc_tx_hist_entry **headp, u64 seqno);
extern void tfrc_tx_hist_purge(struct tfrc_tx_hist_entry **headp);

/* Subtraction a-b modulo-16, respects circular wrap-around */
#define SUB16(a, b) (((a) + 16 - (b)) & 0xF)

/* Number of packets to wait after a missing packet (RFC 4342, 6.1) */
#define TFRC_NDUPACK 3

struct tfrc_rx_hist_entry {
    u64      tfrchrx_seqno:48,
             tfrchrx_ccval:4,
             tfrchrx_type:4;
    u64      tfrchrx_ndp:48;
    ktime_t      tfrchrx_tstamp;
};

struct tfrc_rx_hist {
    struct tfrc_rx_hist_entry *ring[TFRC_NDUPACK + 1];
    u8            loss_count:2,
                  loss_start:2;
#define rtt_sample_prev       loss_start
};

static inline u8 tfrc_rx_hist_index(const struct tfrc_rx_hist *h, const u8 n)
{
    return (h->loss_start + n) & TFRC_NDUPACK;
}

static inline struct tfrc_rx_hist_entry *
            tfrc_rx_hist_last_rcv(const struct tfrc_rx_hist *h)
{
    return h->ring[tfrc_rx_hist_index(h, h->loss_count)];
}

static inline struct tfrc_rx_hist_entry *
            tfrc_rx_hist_entry(const struct tfrc_rx_hist *h, const u8 n)
{
    return h->ring[tfrc_rx_hist_index(h, n)];
}

static inline struct tfrc_rx_hist_entry *
            tfrc_rx_hist_loss_prev(const struct tfrc_rx_hist *h)
{
    return h->ring[h->loss_start];
}

/* indicate whether previously a packet was detected missing */
static inline bool tfrc_rx_hist_loss_pending(const struct tfrc_rx_hist *h)
{
    return h->loss_count > 0;
}

extern void tfrc_rx_hist_add_packet(struct tfrc_rx_hist *h,
                    const struct sk_buff *skb, const u64 ndp);

extern int tfrc_rx_hist_duplicate(struct tfrc_rx_hist *h, struct sk_buff *skb);

struct tfrc_loss_hist;
extern int  tfrc_rx_handle_loss(struct tfrc_rx_hist *h,
                struct tfrc_loss_hist *lh,
                struct sk_buff *skb, const u64 ndp,
                u32 (*first_li)(struct sock *sk),
                struct sock *sk);
extern u32 tfrc_rx_hist_sample_rtt(struct tfrc_rx_hist *h,
                   const struct sk_buff *skb);
extern int tfrc_rx_hist_alloc(struct tfrc_rx_hist *h);
extern void tfrc_rx_hist_purge(struct tfrc_rx_hist *h);

#endif /* _DCCP_PKT_HIST_ */