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alistair23-linux/net/ax25/ax25_subr.c
Thomas Gleixner 2874c5fd28 treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 
Based on 1 normalized pattern(s):

  this program 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

extracted by the scancode license scanner the SPDX license identifier

  GPL-2.0-or-later

has been chosen to replace the boilerplate/reference in 3029 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190527070032.746973796@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-05-30 11:26:32 -07:00

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// SPDX-License-Identifier: GPL-2.0-or-later
/*
*
* Copyright (C) Alan Cox GW4PTS (alan@lxorguk.ukuu.org.uk)
* Copyright (C) Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk)
* Copyright (C) Joerg Reuter DL1BKE (jreuter@yaina.de)
* Copyright (C) Frederic Rible F1OAT (frible@teaser.fr)
*/
#include <linux/errno.h>
#include <linux/types.h>
#include <linux/socket.h>
#include <linux/in.h>
#include <linux/kernel.h>
#include <linux/timer.h>
#include <linux/string.h>
#include <linux/sockios.h>
#include <linux/net.h>
#include <linux/slab.h>
#include <net/ax25.h>
#include <linux/inet.h>
#include <linux/netdevice.h>
#include <linux/skbuff.h>
#include <net/sock.h>
#include <net/tcp_states.h>
#include <linux/uaccess.h>
#include <linux/fcntl.h>
#include <linux/mm.h>
#include <linux/interrupt.h>
/*
* This routine purges all the queues of frames.
*/
void ax25_clear_queues(ax25_cb *ax25)
{
skb_queue_purge(&ax25->write_queue);
skb_queue_purge(&ax25->ack_queue);
skb_queue_purge(&ax25->reseq_queue);
skb_queue_purge(&ax25->frag_queue);
}
/*
* This routine purges the input queue of those frames that have been
* acknowledged. This replaces the boxes labelled "V(a) <- N(r)" on the
* SDL diagram.
*/
void ax25_frames_acked(ax25_cb *ax25, unsigned short nr)
{
struct sk_buff *skb;
/*
* Remove all the ack-ed frames from the ack queue.
*/
if (ax25->va != nr) {
while (skb_peek(&ax25->ack_queue) != NULL && ax25->va != nr) {
skb = skb_dequeue(&ax25->ack_queue);
kfree_skb(skb);
ax25->va = (ax25->va + 1) % ax25->modulus;
}
}
}
void ax25_requeue_frames(ax25_cb *ax25)
{
struct sk_buff *skb;
/*
* Requeue all the un-ack-ed frames on the output queue to be picked
* up by ax25_kick called from the timer. This arrangement handles the
* possibility of an empty output queue.
*/
while ((skb = skb_dequeue_tail(&ax25->ack_queue)) != NULL)
skb_queue_head(&ax25->write_queue, skb);
}
/*
* Validate that the value of nr is between va and vs. Return true or
* false for testing.
*/
int ax25_validate_nr(ax25_cb *ax25, unsigned short nr)
{
unsigned short vc = ax25->va;
while (vc != ax25->vs) {
if (nr == vc) return 1;
vc = (vc + 1) % ax25->modulus;
}
if (nr == ax25->vs) return 1;
return 0;
}
/*
* This routine is the centralised routine for parsing the control
* information for the different frame formats.
*/
int ax25_decode(ax25_cb *ax25, struct sk_buff *skb, int *ns, int *nr, int *pf)
{
unsigned char *frame;
int frametype = AX25_ILLEGAL;
frame = skb->data;
*ns = *nr = *pf = 0;
if (ax25->modulus == AX25_MODULUS) {
if ((frame[0] & AX25_S) == 0) {
frametype = AX25_I; /* I frame - carries NR/NS/PF */
*ns = (frame[0] >> 1) & 0x07;
*nr = (frame[0] >> 5) & 0x07;
*pf = frame[0] & AX25_PF;
} else if ((frame[0] & AX25_U) == 1) { /* S frame - take out PF/NR */
frametype = frame[0] & 0x0F;
*nr = (frame[0] >> 5) & 0x07;
*pf = frame[0] & AX25_PF;
} else if ((frame[0] & AX25_U) == 3) { /* U frame - take out PF */
frametype = frame[0] & ~AX25_PF;
*pf = frame[0] & AX25_PF;
}
skb_pull(skb, 1);
} else {
if ((frame[0] & AX25_S) == 0) {
frametype = AX25_I; /* I frame - carries NR/NS/PF */
*ns = (frame[0] >> 1) & 0x7F;
*nr = (frame[1] >> 1) & 0x7F;
*pf = frame[1] & AX25_EPF;
skb_pull(skb, 2);
} else if ((frame[0] & AX25_U) == 1) { /* S frame - take out PF/NR */
frametype = frame[0] & 0x0F;
*nr = (frame[1] >> 1) & 0x7F;
*pf = frame[1] & AX25_EPF;
skb_pull(skb, 2);
} else if ((frame[0] & AX25_U) == 3) { /* U frame - take out PF */
frametype = frame[0] & ~AX25_PF;
*pf = frame[0] & AX25_PF;
skb_pull(skb, 1);
}
}
return frametype;
}
/*
* This routine is called when the HDLC layer internally generates a
* command or response for the remote machine ( eg. RR, UA etc. ).
* Only supervisory or unnumbered frames are processed.
*/
void ax25_send_control(ax25_cb *ax25, int frametype, int poll_bit, int type)
{
struct sk_buff *skb;
unsigned char *dptr;
if ((skb = alloc_skb(ax25->ax25_dev->dev->hard_header_len + 2, GFP_ATOMIC)) == NULL)
return;
skb_reserve(skb, ax25->ax25_dev->dev->hard_header_len);
skb_reset_network_header(skb);
/* Assume a response - address structure for DTE */
if (ax25->modulus == AX25_MODULUS) {
dptr = skb_put(skb, 1);
*dptr = frametype;
*dptr |= (poll_bit) ? AX25_PF : 0;
if ((frametype & AX25_U) == AX25_S) /* S frames carry NR */
*dptr |= (ax25->vr << 5);
} else {
if ((frametype & AX25_U) == AX25_U) {
dptr = skb_put(skb, 1);
*dptr = frametype;
*dptr |= (poll_bit) ? AX25_PF : 0;
} else {
dptr = skb_put(skb, 2);
dptr[0] = frametype;
dptr[1] = (ax25->vr << 1);
dptr[1] |= (poll_bit) ? AX25_EPF : 0;
}
}
ax25_transmit_buffer(ax25, skb, type);
}
/*
* 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_address *src, ax25_address *dest, ax25_digi *digi)
{
struct sk_buff *skb;
char *dptr;
ax25_digi retdigi;
if (dev == NULL)
return;
if ((skb = alloc_skb(dev->hard_header_len + 1, GFP_ATOMIC)) == NULL)
return; /* Next SABM will get DM'd */
skb_reserve(skb, dev->hard_header_len);
skb_reset_network_header(skb);
ax25_digi_invert(digi, &retdigi);
dptr = skb_put(skb, 1);
*dptr = AX25_DM | AX25_PF;
/*
* Do the address ourselves
*/
dptr = skb_push(skb, ax25_addr_size(digi));
dptr += ax25_addr_build(dptr, dest, src, &retdigi, AX25_RESPONSE, AX25_MODULUS);
ax25_queue_xmit(skb, dev);
}
/*
* Exponential backoff for AX.25
*/
void ax25_calculate_t1(ax25_cb *ax25)
{
int n, t = 2;
switch (ax25->backoff) {
case 0:
break;
case 1:
t += 2 * ax25->n2count;
break;
case 2:
for (n = 0; n < ax25->n2count; n++)
t *= 2;
if (t > 8) t = 8;
break;
}
ax25->t1 = t * ax25->rtt;
}
/*
* Calculate the Round Trip Time
*/
void ax25_calculate_rtt(ax25_cb *ax25)
{
if (ax25->backoff == 0)
return;
if (ax25_t1timer_running(ax25) && ax25->n2count == 0)
ax25->rtt = (9 * ax25->rtt + ax25->t1 - ax25_display_timer(&ax25->t1timer)) / 10;
if (ax25->rtt < AX25_T1CLAMPLO)
ax25->rtt = AX25_T1CLAMPLO;
if (ax25->rtt > AX25_T1CLAMPHI)
ax25->rtt = AX25_T1CLAMPHI;
}
void ax25_disconnect(ax25_cb *ax25, int reason)
{
ax25_clear_queues(ax25);
if (!ax25->sk || !sock_flag(ax25->sk, SOCK_DESTROY))
ax25_stop_heartbeat(ax25);
ax25_stop_t1timer(ax25);
ax25_stop_t2timer(ax25);
ax25_stop_t3timer(ax25);
ax25_stop_idletimer(ax25);
ax25->state = AX25_STATE_0;
ax25_link_failed(ax25, reason);
if (ax25->sk != NULL) {
local_bh_disable();
bh_lock_sock(ax25->sk);
ax25->sk->sk_state = TCP_CLOSE;
ax25->sk->sk_err = reason;
ax25->sk->sk_shutdown |= SEND_SHUTDOWN;
if (!sock_flag(ax25->sk, SOCK_DEAD)) {
ax25->sk->sk_state_change(ax25->sk);
sock_set_flag(ax25->sk, SOCK_DEAD);
}
bh_unlock_sock(ax25->sk);
local_bh_enable();
}
}
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