source: mainline/uspace/srv/net/tl/tcp/iqueue.c@ 32aea9f4

/*
 * Copyright (c) 2011 Jiri Svoboda
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 * - The name of the author may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/** @addtogroup tcp
 * @{
 */

/**
 * @file Connection incoming segments queue
 *
 * Segments are sorted in order of their sequence number.
 */

#include <adt/list.h>
#include <errno.h>
#include <io/log.h>
#include <stdlib.h>
#include "iqueue.h"
#include "segment.h"
#include "seq_no.h"
#include "tcp_type.h"

/** Initialize incoming segments queue.
 *
 * @param iqueue        Incoming queue
 * @param conn          Connection the queue is associated with
 */
void tcp_iqueue_init(tcp_iqueue_t *iqueue, tcp_conn_t *conn)
{
        list_initialize(&iqueue->list);
        iqueue->conn = conn;
}

/** Insert segment into incoming queue.
 *
 * @param iqueue        Incoming queue
 * @param seg           Segment
 */
void tcp_iqueue_insert_seg(tcp_iqueue_t *iqueue, tcp_segment_t *seg)
{
        tcp_iqueue_entry_t *iqe;
        tcp_iqueue_entry_t *qe;
        link_t *link;
        log_msg(LVL_DEBUG, "tcp_iqueue_insert_seg()");

        iqe = calloc(1, sizeof(tcp_iqueue_entry_t));
        if (iqe == NULL) {
                log_msg(LVL_ERROR, "Failed allocating IQE.");
                return;
        }

        iqe->seg = seg;

        /* Sort by sequence number */

        link = list_first(&iqueue->list);
        while (link != NULL) {
                qe = list_get_instance(link,
                    tcp_iqueue_entry_t, link);

                if (seq_no_seg_cmp(iqueue->conn, iqe->seg, qe->seg) >= 0)
                        break;
        }

        if (link != NULL)
                list_insert_before(&iqe->link, &qe->link);
        else
                list_append(&iqe->link, &iqueue->list);
}

/** Get next ready segment from incoming queue.
 *
 * Return the segment with the earliest sequence number if it is ready.
 * A segment is ready if its SEG.SEQ is earlier or equal to RCV.NXT.
 *
 * @param iqueue        Incoming queue
 * @param seg           Place to store pointer to segment
 * @return              EOK on success, ENOENT if no segment is ready
 */
int tcp_iqueue_get_ready_seg(tcp_iqueue_t *iqueue, tcp_segment_t **seg)
{
        tcp_iqueue_entry_t *iqe;
        link_t *link;

        log_msg(LVL_DEBUG, "tcp_get_ready_seg()");

        link = list_first(&iqueue->list);
        if (link == NULL) {
                log_msg(LVL_DEBUG, "iqueue is empty");
                return ENOENT;
        }

        iqe = list_get_instance(link, tcp_iqueue_entry_t, link);

        while (!seq_no_segment_acceptable(iqueue->conn, iqe->seg)) {
                log_msg(LVL_DEBUG, "Skipping unacceptable segment (RCV.NXT=%"
                    PRIu32 ", RCV.NXT+RCV.WND=%" PRIu32 ", SEG.SEQ=%" PRIu32
                    ", SEG.LEN=%" PRIu32 ")", iqueue->conn->rcv_nxt,
                    iqueue->conn->rcv_nxt + iqueue->conn->rcv_wnd,
                    iqe->seg->seq, iqe->seg->len);

                list_remove(&iqe->link);
                tcp_segment_delete(iqe->seg);

                link = list_first(&iqueue->list);
                if (link == NULL) {
                        log_msg(LVL_DEBUG, "iqueue is empty");
                        return ENOENT;
                }

                iqe = list_get_instance(link, tcp_iqueue_entry_t, link);
        }

        /* Do not return segments that are not ready for processing */
        if (!seq_no_segment_ready(iqueue->conn, iqe->seg)) {
                log_msg(LVL_DEBUG, "Next segment not ready: SEG.SEQ=%u, "
                    "RCV.NXT=%u, SEG.LEN=%u", iqe->seg->seq,
                    iqueue->conn->rcv_nxt, iqe->seg->len);
                return ENOENT;
        }

        log_msg(LVL_DEBUG, "Returning ready segment %p", iqe->seg);
        list_remove(&iqe->link);
        *seg = iqe->seg;

        return EOK;
}

/**
 * @}
 */