source: mainline/uspace/srv/net/tl/tcp/tqueue.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 TCP transmission queue
 */

#include <byteorder.h>
#include <io/log.h>
#include <macros.h>
#include <mem.h>
#include "conn.h"
#include "header.h"
#include "rqueue.h"
#include "segment.h"
#include "tqueue.h"
#include "tcp_type.h"

void tcp_tqueue_ctrl_seg(tcp_conn_t *conn, tcp_control_t ctrl)
{
        tcp_segment_t *seg;

        log_msg(LVL_DEBUG, "tcp_tqueue_ctrl_seg(%p, %u)", conn, ctrl);

        seg = tcp_segment_make_ctrl(ctrl);
        tcp_tqueue_seg(conn, seg);
}

void tcp_tqueue_seg(tcp_conn_t *conn, tcp_segment_t *seg)
{
        log_msg(LVL_DEBUG, "tcp_tqueue_seg(%p, %p)", conn, seg);
        /* XXX queue */

        /*
         * Always send ACK once we have received SYN, except for RST segments.
         * (Spec says we should always send ACK once connection has been
         * established.)
         */
        if (tcp_conn_got_syn(conn) && (seg->ctrl & CTL_RST) == 0)
                seg->ctrl |= CTL_ACK;

        seg->seq = conn->snd_nxt;
        seg->wnd = conn->rcv_wnd;

        log_msg(LVL_DEBUG, "SEG.SEQ=%" PRIu32 ", SEG.WND=%" PRIu32,
            seg->seq, seg->wnd);

        if ((seg->ctrl & CTL_ACK) != 0)
                seg->ack = conn->rcv_nxt;
        else
                seg->ack = 0;

        conn->snd_nxt += seg->len;

        tcp_transmit_segment(&conn->ident, seg);
}

/** Transmit data from the send buffer.
 *
 * @param conn  Connection
 */
void tcp_tqueue_new_data(tcp_conn_t *conn)
{
        size_t avail_wnd;
        size_t xfer_seqlen;
        size_t snd_buf_seqlen;
        size_t data_size;
        tcp_control_t ctrl;

        tcp_segment_t *seg;

        log_msg(LVL_DEBUG, "tcp_tqueue_new_data()");

        /* Number of free sequence numbers in send window */
        avail_wnd = (conn->snd_una + conn->snd_wnd) - conn->snd_nxt;
        snd_buf_seqlen = conn->snd_buf_used + (conn->snd_buf_fin ? 1 : 0);

        xfer_seqlen = min(snd_buf_seqlen, avail_wnd);
        log_msg(LVL_DEBUG, "snd_buf_seqlen = %zu, SND.WND = %zu, "
            "xfer_seqlen = %zu", snd_buf_seqlen, conn->snd_wnd,
            xfer_seqlen);

        if (xfer_seqlen == 0)
                return;

        /* XXX Do not always send immediately */

        data_size = xfer_seqlen - (conn->snd_buf_fin ? 1 : 0);
        if (conn->snd_buf_fin && data_size + 1 == xfer_seqlen) {
                /* We are sending out FIN */
                ctrl = CTL_FIN;
        } else {
                ctrl = 0;
        }

        seg = tcp_segment_make_data(ctrl, conn->snd_buf, data_size);
        if (seg == NULL) {
                log_msg(LVL_ERROR, "Memory allocation failure.");
                return;
        }

        /* Remove data from send buffer */
        memmove(conn->snd_buf, conn->snd_buf + data_size,
            conn->snd_buf_used - data_size);
        conn->snd_buf_used -= data_size;
        conn->snd_buf_fin = false;

        tcp_tqueue_seg(conn, seg);
}

/** Remove ACKed segments from retransmission queue and possibly transmit
 * more data.
 *
 * This should be called when SND.UNA is updated due to incoming ACK.
 */
void tcp_tqueue_ack_received(tcp_conn_t *conn)
{
        (void) conn;

        tcp_tqueue_new_data(conn);
}

void tcp_transmit_segment(tcp_sockpair_t *sp, tcp_segment_t *seg)
{
        log_msg(LVL_DEBUG, "tcp_transmit_segment(%p, %p)", sp, seg);
/*
        tcp_pdu_prepare(conn, seg, &data, &len);
        tcp_pdu_transmit(data, len);
*/
        tcp_rqueue_bounce_seg(sp, seg);
}

/**
 * @}
 */