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root/net/x25/x25_in.c

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DEFINITIONS

This source file includes following definitions.
  1. x25_queue_rx_frame
  2. x25_state1_machine
  3. x25_state2_machine
  4. x25_state3_machine
  5. x25_state4_machine
  6. x25_process_rx_frame
  7. x25_backlog_rcv

/*
 *      X.25 Packet Layer release 002
 *
 *      This is ALPHA test software. This code may break your machine,
 *      randomly fail to work with new releases, misbehave and/or generally
 *      screw up. It might even work.
 *
 *      This code REQUIRES 2.1.15 or higher
 *
 *      This module:
 *              This module 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.
 *
 *      History
 *      X.25 001        Jonathan Naylor   Started coding.
 *      X.25 002        Jonathan Naylor   Centralised disconnection code.
 *                                        New timer architecture.
 *      2000-03-20      Daniela Squassoni Disabling/enabling of facilities
 *                                        negotiation.
 *      2000-11-10      Henner Eisen      Check and reset for out-of-sequence
 *                                        i-frames.
 */

#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/skbuff.h>
#include <net/sock.h>
#include <net/tcp_states.h>
#include <net/x25.h>

static int x25_queue_rx_frame(struct sock *sk, struct sk_buff *skb, int more)
{
        struct sk_buff *skbo, *skbn = skb;
        struct x25_sock *x25 = x25_sk(sk);

        if (more) {
                x25->fraglen += skb->len;
                skb_queue_tail(&x25->fragment_queue, skb);
                skb_set_owner_r(skb, sk);
                return 0;
        }

        if (!more && x25->fraglen > 0) {        /* End of fragment */
                int len = x25->fraglen + skb->len;

                if ((skbn = alloc_skb(len, GFP_ATOMIC)) == NULL){
                        kfree_skb(skb);
                        return 1;
                }

                skb_queue_tail(&x25->fragment_queue, skb);

                skb_reset_transport_header(skbn);

                skbo = skb_dequeue(&x25->fragment_queue);
                skb_copy_from_linear_data(skbo, skb_put(skbn, skbo->len),
                                          skbo->len);
                kfree_skb(skbo);

                while ((skbo =
                        skb_dequeue(&x25->fragment_queue)) != NULL) {
                        skb_pull(skbo, (x25->neighbour->extended) ?
                                        X25_EXT_MIN_LEN : X25_STD_MIN_LEN);
                        skb_copy_from_linear_data(skbo,
                                                  skb_put(skbn, skbo->len),
                                                  skbo->len);
                        kfree_skb(skbo);
                }

                x25->fraglen = 0;
        }

        skb_set_owner_r(skbn, sk);
        skb_queue_tail(&sk->sk_receive_queue, skbn);
        if (!sock_flag(sk, SOCK_DEAD))
                sk->sk_data_ready(sk, skbn->len);

        return 0;
}

/*
 * State machine for state 1, Awaiting Call Accepted State.
 * The handling of the timer(s) is in file x25_timer.c.
 * Handling of state 0 and connection release is in af_x25.c.
 */
static int x25_state1_machine(struct sock *sk, struct sk_buff *skb, int frametype)
{
        struct x25_address source_addr, dest_addr;

        switch (frametype) {
                case X25_CALL_ACCEPTED: {
                        struct x25_sock *x25 = x25_sk(sk);

                        x25_stop_timer(sk);
                        x25->condition = 0x00;
                        x25->vs        = 0;
                        x25->va        = 0;
                        x25->vr        = 0;
                        x25->vl        = 0;
                        x25->state     = X25_STATE_3;
                        sk->sk_state   = TCP_ESTABLISHED;
                        /*
                         *      Parse the data in the frame.
                         */
                        skb_pull(skb, X25_STD_MIN_LEN);
                        skb_pull(skb, x25_addr_ntoa(skb->data, &source_addr, &dest_addr));
                        skb_pull(skb,
                                 x25_parse_facilities(skb, &x25->facilities,
                                                &x25->dte_facilities,
                                                &x25->vc_facil_mask));
                        /*
                         *      Copy any Call User Data.
                         */
                        if (skb->len >= 0) {
                                skb_copy_from_linear_data(skb,
                                              x25->calluserdata.cuddata,
                                              skb->len);
                                x25->calluserdata.cudlength = skb->len;
                        }
                        if (!sock_flag(sk, SOCK_DEAD))
                                sk->sk_state_change(sk);
                        break;
                }
                case X25_CLEAR_REQUEST:
                        x25_write_internal(sk, X25_CLEAR_CONFIRMATION);
                        x25_disconnect(sk, ECONNREFUSED, skb->data[3], skb->data[4]);
                        break;

                default:
                        break;
        }

        return 0;
}

/*
 * State machine for state 2, Awaiting Clear Confirmation State.
 * The handling of the timer(s) is in file x25_timer.c
 * Handling of state 0 and connection release is in af_x25.c.
 */
static int x25_state2_machine(struct sock *sk, struct sk_buff *skb, int frametype)
{
        switch (frametype) {

                case X25_CLEAR_REQUEST:
                        x25_write_internal(sk, X25_CLEAR_CONFIRMATION);
                        x25_disconnect(sk, 0, skb->data[3], skb->data[4]);
                        break;

                case X25_CLEAR_CONFIRMATION:
                        x25_disconnect(sk, 0, 0, 0);
                        break;

                default:
                        break;
        }

        return 0;
}

/*
 * State machine for state 3, Connected State.
 * The handling of the timer(s) is in file x25_timer.c
 * Handling of state 0 and connection release is in af_x25.c.
 */
static int x25_state3_machine(struct sock *sk, struct sk_buff *skb, int frametype, int ns, int nr, int q, int d, int m)
{
        int queued = 0;
        int modulus;
        struct x25_sock *x25 = x25_sk(sk);

        modulus = (x25->neighbour->extended) ? X25_EMODULUS : X25_SMODULUS;

        switch (frametype) {

                case X25_RESET_REQUEST:
                        x25_write_internal(sk, X25_RESET_CONFIRMATION);
                        x25_stop_timer(sk);
                        x25->condition = 0x00;
                        x25->vs        = 0;
                        x25->vr        = 0;
                        x25->va        = 0;
                        x25->vl        = 0;
                        x25_requeue_frames(sk);
                        break;

                case X25_CLEAR_REQUEST:
                        x25_write_internal(sk, X25_CLEAR_CONFIRMATION);
                        x25_disconnect(sk, 0, skb->data[3], skb->data[4]);
                        break;

                case X25_RR:
                case X25_RNR:
                        if (!x25_validate_nr(sk, nr)) {
                                x25_clear_queues(sk);
                                x25_write_internal(sk, X25_RESET_REQUEST);
                                x25_start_t22timer(sk);
                                x25->condition = 0x00;
                                x25->vs        = 0;
                                x25->vr        = 0;
                                x25->va        = 0;
                                x25->vl        = 0;
                                x25->state     = X25_STATE_4;
                        } else {
                                x25_frames_acked(sk, nr);
                                if (frametype == X25_RNR) {
                                        x25->condition |= X25_COND_PEER_RX_BUSY;
                                } else {
                                        x25->condition &= ~X25_COND_PEER_RX_BUSY;
                                }
                        }
                        break;

                case X25_DATA:  /* XXX */
                        x25->condition &= ~X25_COND_PEER_RX_BUSY;
                        if ((ns != x25->vr) || !x25_validate_nr(sk, nr)) {
                                x25_clear_queues(sk);
                                x25_write_internal(sk, X25_RESET_REQUEST);
                                x25_start_t22timer(sk);
                                x25->condition = 0x00;
                                x25->vs        = 0;
                                x25->vr        = 0;
                                x25->va        = 0;
                                x25->vl        = 0;
                                x25->state     = X25_STATE_4;
                                break;
                        }
                        x25_frames_acked(sk, nr);
                        if (ns == x25->vr) {
                                if (x25_queue_rx_frame(sk, skb, m) == 0) {
                                        x25->vr = (x25->vr + 1) % modulus;
                                        queued = 1;
                                } else {
                                        /* Should never happen */
                                        x25_clear_queues(sk);
                                        x25_write_internal(sk, X25_RESET_REQUEST);
                                        x25_start_t22timer(sk);
                                        x25->condition = 0x00;
                                        x25->vs        = 0;
                                        x25->vr        = 0;
                                        x25->va        = 0;
                                        x25->vl        = 0;
                                        x25->state     = X25_STATE_4;
                                        break;
                                }
                                if (atomic_read(&sk->sk_rmem_alloc) >
                                    (sk->sk_rcvbuf >> 1))
                                        x25->condition |= X25_COND_OWN_RX_BUSY;
                        }
                        /*
                         *      If the window is full Ack it immediately, else
                         *      start the holdback timer.
                         */
                        if (((x25->vl + x25->facilities.winsize_in) % modulus) == x25->vr) {
                                x25->condition &= ~X25_COND_ACK_PENDING;
                                x25_stop_timer(sk);
                                x25_enquiry_response(sk);
                        } else {
                                x25->condition |= X25_COND_ACK_PENDING;
                                x25_start_t2timer(sk);
                        }
                        break;

                case X25_INTERRUPT_CONFIRMATION:
                        x25->intflag = 0;
                        break;

                case X25_INTERRUPT:
                        if (sock_flag(sk, SOCK_URGINLINE))
                                queued = !sock_queue_rcv_skb(sk, skb);
                        else {
                                skb_set_owner_r(skb, sk);
                                skb_queue_tail(&x25->interrupt_in_queue, skb);
                                queued = 1;
                        }
                        sk_send_sigurg(sk);
                        x25_write_internal(sk, X25_INTERRUPT_CONFIRMATION);
                        break;

                default:
                        printk(KERN_WARNING "x25: unknown %02X in state 3\n", frametype);
                        break;
        }

        return queued;
}

/*
 * State machine for state 4, Awaiting Reset Confirmation State.
 * The handling of the timer(s) is in file x25_timer.c
 * Handling of state 0 and connection release is in af_x25.c.
 */
static int x25_state4_machine(struct sock *sk, struct sk_buff *skb, int frametype)
{
        switch (frametype) {

                case X25_RESET_REQUEST:
                        x25_write_internal(sk, X25_RESET_CONFIRMATION);
                case X25_RESET_CONFIRMATION: {
                        struct x25_sock *x25 = x25_sk(sk);

                        x25_stop_timer(sk);
                        x25->condition = 0x00;
                        x25->va        = 0;
                        x25->vr        = 0;
                        x25->vs        = 0;
                        x25->vl        = 0;
                        x25->state     = X25_STATE_3;
                        x25_requeue_frames(sk);
                        break;
                }
                case X25_CLEAR_REQUEST:
                        x25_write_internal(sk, X25_CLEAR_CONFIRMATION);
                        x25_disconnect(sk, 0, skb->data[3], skb->data[4]);
                        break;

                default:
                        break;
        }

        return 0;
}

/* Higher level upcall for a LAPB frame */
int x25_process_rx_frame(struct sock *sk, struct sk_buff *skb)
{
        struct x25_sock *x25 = x25_sk(sk);
        int queued = 0, frametype, ns, nr, q, d, m;

        if (x25->state == X25_STATE_0)
                return 0;

        frametype = x25_decode(sk, skb, &ns, &nr, &q, &d, &m);

        switch (x25->state) {
                case X25_STATE_1:
                        queued = x25_state1_machine(sk, skb, frametype);
                        break;
                case X25_STATE_2:
                        queued = x25_state2_machine(sk, skb, frametype);
                        break;
                case X25_STATE_3:
                        queued = x25_state3_machine(sk, skb, frametype, ns, nr, q, d, m);
                        break;
                case X25_STATE_4:
                        queued = x25_state4_machine(sk, skb, frametype);
                        break;
        }

        x25_kick(sk);

        return queued;
}

int x25_backlog_rcv(struct sock *sk, struct sk_buff *skb)
{
        int queued = x25_process_rx_frame(sk, skb);

        if (!queued)
                kfree_skb(skb);

        return 0;
}

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