forked from Qortal/Brooklyn
You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
288 lines
6.8 KiB
288 lines
6.8 KiB
// SPDX-License-Identifier: GPL-2.0-or-later |
|
/* |
|
* |
|
* Copyright (C) Alan Cox GW4PTS ([email protected]) |
|
* Copyright (C) Jonathan Naylor G4KLX ([email protected]) |
|
* Copyright (C) Joerg Reuter DL1BKE ([email protected]) |
|
* Copyright (C) Frederic Rible F1OAT ([email protected]) |
|
*/ |
|
#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(); |
|
} |
|
}
|
|
|