Subversion Repositories or1k

/*

 *      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 New timer architecture.

 *      2000-09-04      Henner Eisen    Prevented x25_output() skb leakage.

 *      2000-10-27      Henner Eisen    MSG_DONTWAIT for fragment allocation.

 *      2000-11-10      Henner Eisen    x25_send_iframe(): re-queued frames

 *                                      needed cleaned seq-number fields.

 */

#include <linux/errno.h>

#include <linux/types.h>

#include <linux/socket.h>

#include <linux/in.h>

#include <linux/kernel.h>

#include <linux/sched.h>

#include <linux/timer.h>

#include <linux/string.h>

#include <linux/sockios.h>

#include <linux/net.h>

#include <linux/inet.h>

#include <linux/netdevice.h>

#include <linux/skbuff.h>

#include <net/sock.h>

#include <asm/segment.h>

#include <asm/system.h>

#include <linux/fcntl.h>

#include <linux/mm.h>

#include <linux/interrupt.h>

#include <net/x25.h>

static int x25_pacsize_to_bytes(unsigned int pacsize)

{

        int bytes = 1;

        if (pacsize == 0)

                return 128;

        while (pacsize-- > 0)

                bytes *= 2;

        return bytes;

}

/*

 *      This is where all X.25 information frames pass.

 *

 *      Returns the amount of user data bytes sent on success

 *      or a negative error code on failure.

 */

int x25_output(struct sock *sk, struct sk_buff *skb)

{

        struct sk_buff *skbn;

        unsigned char header[X25_EXT_MIN_LEN];

        int err, frontlen, len, header_len, max_len;

        int sent=0, noblock = X25_SKB_CB(skb)->flags & MSG_DONTWAIT;

        header_len = (sk->protinfo.x25->neighbour->extended) ? X25_EXT_MIN_LEN : X25_STD_MIN_LEN;

        max_len    = x25_pacsize_to_bytes(sk->protinfo.x25->facilities.pacsize_out);

        if (skb->len - header_len > max_len) {

                /* Save a copy of the Header */

                memcpy(header, skb->data, header_len);

                skb_pull(skb, header_len);

                frontlen = skb_headroom(skb);

                while (skb->len > 0) {

                        if ((skbn = sock_alloc_send_skb(sk, frontlen + max_len, noblock, &err)) == NULL){

                                if(err == -EWOULDBLOCK && noblock){

                                        kfree_skb(skb);

                                        return sent;

                                }

                                SOCK_DEBUG(sk, "x25_output: fragment allocation failed, err=%d, %d bytes sent\n", err, sent);

                                return err;

                        }

                        skb_reserve(skbn, frontlen);

                        len = (max_len > skb->len) ? skb->len : max_len;

                        /* Copy the user data */

                        memcpy(skb_put(skbn, len), skb->data, len);

                        skb_pull(skb, len);

                        /* Duplicate the Header */

                        skb_push(skbn, header_len);

                        memcpy(skbn->data, header, header_len);

                        if (skb->len > 0) {

                                if (sk->protinfo.x25->neighbour->extended)

                                        skbn->data[3] |= X25_EXT_M_BIT;

                                else

                                        skbn->data[2] |= X25_STD_M_BIT;

                        }

                        skb_queue_tail(&sk->write_queue, skbn);

                        sent += len;

                }

                kfree_skb(skb);

        } else {

                skb_queue_tail(&sk->write_queue, skb);

                sent = skb->len - header_len;

        }

        return sent;

}

/*

 *      This procedure is passed a buffer descriptor for an iframe. It builds

 *      the rest of the control part of the frame and then writes it out.

 */

static void x25_send_iframe(struct sock *sk, struct sk_buff *skb)

{

        if (skb == NULL)

                return;

        if (sk->protinfo.x25->neighbour->extended) {

                skb->data[2]  = (sk->protinfo.x25->vs << 1) & 0xFE;

                skb->data[3] &= X25_EXT_M_BIT;

                skb->data[3] |= (sk->protinfo.x25->vr << 1) & 0xFE;

        } else {

                skb->data[2] &= X25_STD_M_BIT;

                skb->data[2] |= (sk->protinfo.x25->vs << 1) & 0x0E;

                skb->data[2] |= (sk->protinfo.x25->vr << 5) & 0xE0;

        }

        x25_transmit_link(skb, sk->protinfo.x25->neighbour);

}

void x25_kick(struct sock *sk)

{

        struct sk_buff *skb, *skbn;

        unsigned short start, end;

        int modulus;

        if (sk->protinfo.x25->state != X25_STATE_3)

                return;

        /*

         *      Transmit interrupt data.

         */

        if (!sk->protinfo.x25->intflag && skb_peek(&sk->protinfo.x25->interrupt_out_queue) != NULL) {

                sk->protinfo.x25->intflag = 1;

                skb = skb_dequeue(&sk->protinfo.x25->interrupt_out_queue);

                x25_transmit_link(skb, sk->protinfo.x25->neighbour);

        }

        if (sk->protinfo.x25->condition & X25_COND_PEER_RX_BUSY)

                return;

        if (skb_peek(&sk->write_queue) == NULL)

                return;

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

        start   = (skb_peek(&sk->protinfo.x25->ack_queue) == NULL) ? sk->protinfo.x25->va : sk->protinfo.x25->vs;

        end     = (sk->protinfo.x25->va + sk->protinfo.x25->facilities.winsize_out) % modulus;

        if (start == end)

                return;

        sk->protinfo.x25->vs = start;

        /*

         * Transmit data until either we're out of data to send or

         * the window is full.

         */

        skb = skb_dequeue(&sk->write_queue);

        do {

                if ((skbn = skb_clone(skb, GFP_ATOMIC)) == NULL) {

                        skb_queue_head(&sk->write_queue, skb);

                        break;

                }

                skb_set_owner_w(skbn, sk);

                /*

                 * Transmit the frame copy.

                 */

                x25_send_iframe(sk, skbn);

                sk->protinfo.x25->vs = (sk->protinfo.x25->vs + 1) % modulus;

                /*

                 * Requeue the original data frame.

                 */

                skb_queue_tail(&sk->protinfo.x25->ack_queue, skb);

        } while (sk->protinfo.x25->vs != end && (skb = skb_dequeue(&sk->write_queue)) != NULL);

        sk->protinfo.x25->vl         = sk->protinfo.x25->vr;

        sk->protinfo.x25->condition &= ~X25_COND_ACK_PENDING;

        x25_stop_timer(sk);

}

/*

 * The following routines are taken from page 170 of the 7th ARRL Computer

 * Networking Conference paper, as is the whole state machine.

 */

void x25_enquiry_response(struct sock *sk)

{

        if (sk->protinfo.x25->condition & X25_COND_OWN_RX_BUSY)

                x25_write_internal(sk, X25_RNR);

        else

                x25_write_internal(sk, X25_RR);

        sk->protinfo.x25->vl         = sk->protinfo.x25->vr;

        sk->protinfo.x25->condition &= ~X25_COND_ACK_PENDING;

        x25_stop_timer(sk);

}