source: mainline/uspace/srv/net/tcp/tqueue.c@ 0a1e7e4

/*
 * Copyright (c) 2015 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 <adt/list.h>
#include <errno.h>
#include <fibril_synch.h>
#include <byteorder.h>
#include <io/log.h>
#include <macros.h>
#include <mem.h>
#include <stdlib.h>

#include "conn.h"
#include "inet.h"
#include "ncsim.h"
#include "rqueue.h"
#include "segment.h"
#include "seq_no.h"
#include "tqueue.h"
#include "tcp_type.h"

#define RETRANSMIT_TIMEOUT      (2*1000*1000)

static void retransmit_timeout_func(void *);
static void tcp_tqueue_timer_set(tcp_conn_t *);
static void tcp_tqueue_timer_clear(tcp_conn_t *);
static void tcp_tqueue_seg(tcp_conn_t *, tcp_segment_t *);
static void tcp_conn_transmit_segment(tcp_conn_t *, tcp_segment_t *);
static void tcp_prepare_transmit_segment(tcp_conn_t *, tcp_segment_t *);
static void tcp_tqueue_send_immed(tcp_conn_t *, tcp_segment_t *);

int tcp_tqueue_init(tcp_tqueue_t *tqueue, tcp_conn_t *conn,
    tcp_tqueue_cb_t *cb)
{
        tqueue->conn = conn;
        tqueue->timer = fibril_timer_create(&conn->lock);
        tqueue->cb = cb;
        if (tqueue->timer == NULL)
                return ENOMEM;

        list_initialize(&tqueue->list);

        return EOK;
}

void tcp_tqueue_clear(tcp_tqueue_t *tqueue)
{
        tcp_tqueue_timer_clear(tqueue->conn);
}

void tcp_tqueue_fini(tcp_tqueue_t *tqueue)
{
        link_t *link;
        tcp_tqueue_entry_t *tqe;

        if (tqueue->timer != NULL) {
                fibril_timer_destroy(tqueue->timer);
                tqueue->timer = NULL;
        }

        while (!list_empty(&tqueue->list)) {
                link = list_first(&tqueue->list);
                tqe = list_get_instance(link, tcp_tqueue_entry_t, link);
                list_remove(link);

                tcp_segment_delete(tqe->seg);
                free(tqe);
        }
}

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

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

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

static void tcp_tqueue_seg(tcp_conn_t *conn, tcp_segment_t *seg)
{
        tcp_segment_t *rt_seg;
        tcp_tqueue_entry_t *tqe;

        log_msg(LOG_DEFAULT, LVL_DEBUG, "%s: tcp_tqueue_seg(%p, %p)", conn->name, conn,
            seg);

        /*
         * Add segment to retransmission queue
         */

        if (seg->len > 0) {
                rt_seg = tcp_segment_dup(seg);
                if (rt_seg == NULL) {
                        log_msg(LOG_DEFAULT, LVL_ERROR, "Memory allocation failed.");
                        /* XXX Handle properly */
                        return;
                }

                tqe = calloc(1, sizeof(tcp_tqueue_entry_t));
                if (tqe == NULL) {
                        log_msg(LOG_DEFAULT, LVL_ERROR, "Memory allocation failed.");
                        /* XXX Handle properly */
                        return;
                }

                tqe->conn = conn;
                tqe->seg = rt_seg;
                rt_seg->seq = conn->snd_nxt;

                list_append(&tqe->link, &conn->retransmit.list);

                /* Set retransmission timer */
                tcp_tqueue_timer_set(conn);
        }

        tcp_prepare_transmit_segment(conn, seg);
}

static void tcp_prepare_transmit_segment(tcp_conn_t *conn, tcp_segment_t *seg)
{
        /*
         * 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;
        conn->snd_nxt += seg->len;

        tcp_conn_transmit_segment(conn, 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;
        bool send_fin;

        tcp_segment_t *seg;

        log_msg(LOG_DEFAULT, LVL_DEBUG, "%s: tcp_tqueue_new_data()", conn->name);

        /* 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(LOG_DEFAULT, LVL_DEBUG, "%s: snd_buf_seqlen = %zu, SND.WND = %" PRIu32 ", "
            "xfer_seqlen = %zu", conn->name, snd_buf_seqlen, conn->snd_wnd,
            xfer_seqlen);

        if (xfer_seqlen == 0)
                return;

        /* XXX Do not always send immediately */

        send_fin = conn->snd_buf_fin && xfer_seqlen == snd_buf_seqlen;
        data_size = xfer_seqlen - (send_fin ? 1 : 0);

        if (send_fin) {
                log_msg(LOG_DEFAULT, LVL_DEBUG, "%s: Sending out FIN.", conn->name);
                /* 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(LOG_DEFAULT, 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;

        if (send_fin)
                conn->snd_buf_fin = false;

        fibril_condvar_broadcast(&conn->snd_buf_cv);

        if (send_fin)
                tcp_conn_fin_sent(conn);

        tcp_tqueue_seg(conn, seg);
        tcp_segment_delete(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)
{
        link_t *cur, *next;

        log_msg(LOG_DEFAULT, LVL_DEBUG, "%s: tcp_tqueue_ack_received(%p)", conn->name,
            conn);

        cur = conn->retransmit.list.head.next;

        while (cur != &conn->retransmit.list.head) {
                next = cur->next;

                tcp_tqueue_entry_t *tqe = list_get_instance(cur,
                    tcp_tqueue_entry_t, link);

                if (seq_no_segment_acked(conn, tqe->seg, conn->snd_una)) {
                        /* Remove acknowledged segment */
                        list_remove(cur);

                        if ((tqe->seg->ctrl & CTL_FIN) != 0) {
                                log_msg(LOG_DEFAULT, LVL_DEBUG, "Fin has been acked");
                                log_msg(LOG_DEFAULT, LVL_DEBUG, "SND.UNA=%" PRIu32
                                    " SEG.SEQ=%" PRIu32 " SEG.LEN=%" PRIu32,
                                    conn->snd_una, tqe->seg->seq, tqe->seg->len);
                                /* Our FIN has been acked */
                                conn->fin_is_acked = true;
                        }

                        tcp_segment_delete(tqe->seg);
                        free(tqe);

                        /* Reset retransmission timer */
                        tcp_tqueue_timer_set(conn);
                }

                cur = next;
        }

        /* Clear retransmission timer if the queue is empty. */
        if (list_empty(&conn->retransmit.list))
                tcp_tqueue_timer_clear(conn);

        /* Possibly transmit more data */
        tcp_tqueue_new_data(conn);
}

static void tcp_conn_transmit_segment(tcp_conn_t *conn, tcp_segment_t *seg)
{
        log_msg(LOG_DEFAULT, LVL_DEBUG, "%s: tcp_conn_transmit_segment(%p, %p)",
            conn->name, conn, seg);

        seg->wnd = conn->rcv_wnd;

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

        tcp_tqueue_send_immed(conn, seg);
}

void tcp_tqueue_send_immed(tcp_conn_t *conn, tcp_segment_t *seg)
{
        log_msg(LOG_DEFAULT, LVL_DEBUG,
            "tcp_tqueue_send_immed(l:(%u),f:(%u), %p)",
            conn->ident.local.port, conn->ident.remote.port, seg);

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

        tcp_segment_dump(seg);

        conn->retransmit.cb->transmit_seg(&conn->ident, seg);
}

static void retransmit_timeout_func(void *arg)
{
        tcp_conn_t *conn = (tcp_conn_t *) arg;
        tcp_tqueue_entry_t *tqe;
        tcp_segment_t *rt_seg;
        link_t *link;

        log_msg(LOG_DEFAULT, LVL_DEBUG, "### %s: retransmit_timeout_func(%p)", conn->name, conn);

        tcp_conn_lock(conn);

        if (conn->cstate == st_closed) {
                log_msg(LOG_DEFAULT, LVL_DEBUG, "Connection already closed.");
                tcp_conn_unlock(conn);
                tcp_conn_delref(conn);
                return;
        }

        link = list_first(&conn->retransmit.list);
        if (link == NULL) {
                log_msg(LOG_DEFAULT, LVL_DEBUG, "Nothing to retransmit");
                tcp_conn_unlock(conn);
                tcp_conn_delref(conn);
                return;
        }

        tqe = list_get_instance(link, tcp_tqueue_entry_t, link);

        rt_seg = tcp_segment_dup(tqe->seg);
        if (rt_seg == NULL) {
                log_msg(LOG_DEFAULT, LVL_ERROR, "Memory allocation failed.");
                tcp_conn_unlock(conn);
                tcp_conn_delref(conn);
                /* XXX Handle properly */
                return;
        }

        log_msg(LOG_DEFAULT, LVL_DEBUG, "### %s: retransmitting segment", conn->name);
        tcp_conn_transmit_segment(tqe->conn, rt_seg);

        /* Reset retransmission timer */
        fibril_timer_set_locked(conn->retransmit.timer, RETRANSMIT_TIMEOUT,
            retransmit_timeout_func, (void *) conn);

        tcp_conn_unlock(conn);

        log_msg(LOG_DEFAULT, LVL_DEBUG, "### %s: retransmit_timeout_func(%p) end", conn->name, conn);
}

/** Set or re-set retransmission timer */
static void tcp_tqueue_timer_set(tcp_conn_t *conn)
{
        log_msg(LOG_DEFAULT, LVL_DEBUG, "### %s: tcp_tqueue_timer_set() begin", conn->name);

        /* Clear first to make sure we update refcnt correctly */
        tcp_tqueue_timer_clear(conn);

        tcp_conn_addref(conn);
        fibril_timer_set_locked(conn->retransmit.timer, RETRANSMIT_TIMEOUT,
            retransmit_timeout_func, (void *) conn);

        log_msg(LOG_DEFAULT, LVL_DEBUG, "### %s: tcp_tqueue_timer_set() end", conn->name);
}

/** Clear retransmission timer */
static void tcp_tqueue_timer_clear(tcp_conn_t *conn)
{
        log_msg(LOG_DEFAULT, LVL_DEBUG, "### %s: tcp_tqueue_timer_clear() begin", conn->name);

        if (fibril_timer_clear_locked(conn->retransmit.timer) == fts_active)
                tcp_conn_delref(conn);

        log_msg(LOG_DEFAULT, LVL_DEBUG, "### %s: tcp_tqueue_timer_clear() end", conn->name);
}

/**
 * @}
 */