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/*
* ax25_subr.c: Subroutines for NEW-AX.25 state machine
*
* Authors: Jens David (DG1KJD), Matthias Welwarsky (DG2FEF), Jonathan (G4KL
* Alan Cox (GW4PTS), Joerg (DL1BKE), et al
*
* Comment: Most of this code is based on the SDL diagrams published in the
* ARRL Computer Networking Conference papers. The diagrams have mi
* in them, but are mostly correct. Before you modify the code coul
* read the SDL diagrams as the code is not obvious and probably ve
* easy to break;
*
* Changelog:
*
* License: 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.
*/
#include <linux/skbuff.h>
#include <linux/tcp.h>
#include <linux/mm.h>
#include <net/sock.h>
#include <net/ax25.h>
#include <net/ax25dev.h>
#include "ax25_ddi.h"
#include "ax25_in.h"
#include "ax25_subr.h"
#include "ax25_core.h"
#include "ax25_vj.h"
#include "ax25_timer.h"
/*
* This routine purges all the queues of frames.
*/
void ax25_clear_queues(ax25_cb *ax25)
{
int i;
skb_queue_purge(&ax25->frag_queue);
skb_queue_purge(&ax25->rcv_queue);
skb_queue_purge(&ax25->write_queue);
skb_queue_purge(&ax25->ack_queue);
for (i = 0; i <= AX25_SEQMASK; i++) {
struct sk_buff *skb;
if ((skb = ax25->reseq[i].skb) != NULL) {
ax25->reseq[i].skb = NULL;
ax25->reseq[i].csum = 0;
kfree_skb(skb);
}
}
}
/*
* this is new
*/
void ax25_tx_command(ax25_cb *ax25, int frametype, int poll_bit)
{
if (poll_bit)
frametype |= 0x100;
ax25->tx_cmd = frametype;
ax25_kick(ax25);
}
void ax25_tx_response(ax25_cb *ax25, int frametype, int poll_bit)
{
if (poll_bit)
frametype |= 0x100;
ax25->tx_rsp = frametype;
ax25_kick(ax25);
}
/*
* Send a 'DM' to an unknown connection attempt, or an invalid caller.
*
* Note: src here is the sender, thus it's the target of the DM
*/
void ax25_return_dm(struct net_device *dev, ax25_pktinfo *pkt)
{
struct sk_buff *skb;
unsigned char *dptr;
int sizeof_addr;
ax25_addr_t addr;
sizeof_addr = ax25_sizeof_addr(&pkt->addr);
if ((skb = alloc_skb(AX25_BPQ_HEADER_LEN + sizeof_addr + 1, GFP_ATOMIC)) == NULL)
return; /* Next SABM will get DM'd */
skb_reserve(skb, AX25_BPQ_HEADER_LEN + sizeof_addr);
ax25_invert_addr(&pkt->addr, &addr);
*skb_put(skb, 1) = AX25_DM|AX25_PF;
/*
* Do the address ourselves
*/
skb->nh.raw = skb->data;
dptr = skb_push(skb, sizeof_addr);
dptr += ax25_build_addr(dptr, &addr, AX25_RESPONSE, AX25_SEQMASK);
ax25_send_unproto(skb, dev);
}
/*
* Exponential backoff for AX.25
*/
unsigned short ax25_calculate_t1(ax25_cb *ax25)
{
int n;
int t = 1;
switch (ax25->backoff) {
case 0:
break;
case 1:
t += 2 * ax25->n2count;
break;
case 2:
t <<= (ax25->n2count < 8 ? ax25->n2count : 8);
break;
}
n = (t * ax25->rtt);
if (n > AX25_T1CLAMPHI)
return AX25_T1CLAMPHI;
if (n < AX25_T1CLAMPLO)
return AX25_T1CLAMPLO;
return n;
}
void ax25_close_socket(struct sock *sk, int reason)
{
sk->err = reason;
sk->shutdown = SHUTDOWN_MASK;
sk->state = TCP_CLOSE;
sk->state_change(sk);
sk->dead = 1;
}
void ax25_disconnect(ax25_cb *ax25, int reason)
{
ax25_clear_queues(ax25);
ax25_link_failed(ax25, reason);
write_lock(&ax25->timer_lock);
ax25->wrt_timer = 0;
ax25->ack_timer = 0;
ax25->idletimer = 0;
ax25->vs = 0;
ax25->va = 0;
ax25->vr = 0;
ax25->vl = 0;
ax25->killtimer = 90 * AX25_SLOWHZ;
ax25->state = AX25_STATE_0;
write_unlock(&ax25->timer_lock);
if (ax25->peer && ax25->peer->state > AX25_STATE_2)
ax25_set_cond(ax25->peer, AX25_COND_RELEASE);
if (ax25->slcomp) {
axhc_free(ax25->slcomp);
ax25->slcomp = NULL;
}
}
void ax25_nr_error_recovery(ax25_cb *ax25)
{
if (ax25->peer != NULL)
ax25->peer->condition |= AX25_COND_RELEASE;
ax25_clear_queues(ax25);
ax25_start_t1(ax25);
ax25->state = AX25_STATE_2;
ax25_tx_command(ax25, AX25_DISC, AX25_POLLON);
}
void ax25_establish_data_link(ax25_cb *ax25)
{
ax25->timer_lock= RW_LOCK_UNLOCKED;
ax25->state = AX25_STATE_1;
ax25->n2count = 0;
ax25->ack_timer = 0;
ax25->vs = 0;
ax25->va = 0;
ax25->vr = 0;
ax25->vl = 0;
ax25_set_cond(ax25, AX25_COND_SETUP);
ax25_start_t1(ax25);
if (ax25->seqmask == AX25_SEQMASK)
ax25_tx_command(ax25, AX25_SABM, AX25_POLLON);
else
ax25_tx_command(ax25, AX25_SABME, AX25_POLLON);
}
void ax25_transmit_enquiry(ax25_cb *ax25)
{
int ft = (ax25->condition & AX25_COND_OWN_RX_BUSY) ? AX25_RNR:AX25_RR;
ax25_tx_command(ax25, ft, AX25_POLLON);
ax25_start_t1(ax25);
ax25_clr_cond(ax25, AX25_COND_ACK_PENDING);
if (DAMA_STATE(ax25) & DAMA_SLAVE) AX25_PTR(ax25->device)->dama_polled = 1;
}
void ax25_enquiry_response(ax25_cb *ax25)
{
int ft = (ax25->condition & AX25_COND_OWN_RX_BUSY) ? AX25_RNR:AX25_RR;
ax25_tx_response(ax25, ft, AX25_POLLON);
ax25_clr_cond(ax25, AX25_COND_ACK_PENDING);
}
void ax25_timeout_response(ax25_cb *ax25)
{
int ft = (ax25->condition & AX25_COND_OWN_RX_BUSY) ? AX25_RNR:AX25_RR;
ax25_tx_response(ax25, ft, AX25_POLLOFF);
ax25_clr_cond(ax25, AX25_COND_ACK_PENDING);
}
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