/*
* NET/ROM release 003
*
* 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 1.2.1 or higher/ NET3.029
*
* 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
* NET/ROM 001 Jonathan(G4KLX) Cloned from ax25_subr.c
* NET/ROM 003 Jonathan(G4KLX) Added G8BPQ NET/ROM extensions.
*/
#include <linux/config.h>
#ifdef CONFIG_NETROM
#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 <net/ax25.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/netrom.h>
/*
* This routine purges all of the queues of frames.
*/
void nr_clear_queues(struct sock *sk)
{
struct sk_buff *skb;
while ((skb = skb_dequeue(&sk->write_queue)) != NULL) {
skb->sk = sk;
skb->free = 1;
kfree_skb(skb, FREE_WRITE);
}
while ((skb = skb_dequeue(&sk->nr->ack_queue)) != NULL) {
skb->sk = sk;
skb->free = 1;
kfree_skb(skb, FREE_WRITE);
}
while ((skb = skb_dequeue(&sk->nr->reseq_queue)) != NULL) {
kfree_skb(skb, FREE_READ);
}
while ((skb = skb_dequeue(&sk->nr->frag_queue)) != NULL) {
kfree_skb(skb, FREE_READ);
}
}
/*
* 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 nr_frames_acked(struct sock *sk, unsigned short nr)
{
struct sk_buff *skb;
/*
* Remove all the ack-ed frames from the ack queue.
*/
if (sk->nr->va != nr) {
while (skb_peek(&sk->nr->ack_queue) != NULL && sk->nr->va != nr) {
skb = skb_dequeue(&sk->nr->ack_queue);
skb->sk = sk;
skb->free = 1;
kfree_skb(skb, FREE_WRITE);
sk->nr->va = (sk->nr->va + 1) % NR_MODULUS;
}
}
}
/*
* Requeue all the un-ack-ed frames on the output queue to be picked
* up by nr_kick called from the timer. This arrangement handles the
* possibility of an empty output queue.
*/
void nr_requeue_frames(struct sock *sk)
{
struct sk_buff *skb, *skb_prev = NULL;
while ((skb = skb_dequeue(&sk->nr->ack_queue)) != NULL) {
if (skb_prev == NULL)
skb_queue_head(&sk->write_queue, skb);
else
skb_append(skb_prev, skb);
skb_prev = skb;
}
}
/*
* Validate that the value of nr is between va and vs. Return true or
* false for testing.
*/
int nr_validate_nr(struct sock *sk, unsigned short nr)
{
unsigned short vc = sk->nr->va;
while (vc != sk->nr->vs) {
if (nr == vc) return 1;
vc = (vc + 1) % NR_MODULUS;
}
if (nr == sk->nr->vs) return 1;
return 0;
}
/*
* Check that ns is within the receive window.
*/
int nr_in_rx_window(struct sock *sk, unsigned short ns)
{
unsigned short vc = sk->nr->vr;
unsigned short vt = (sk->nr->vl + sk->window) % NR_MODULUS;
while (vc != vt) {
if (ns == vc) return 1;
vc = (vc + 1) % NR_MODULUS;
}
return 0;
}
/*
* This routine is called when the HDLC layer internally generates a
* control frame.
*/
void nr_write_internal(struct sock *sk, int frametype)
{
struct sk_buff *skb;
unsigned char *dptr;
int len, timeout;
len = AX25_BPQ_HEADER_LEN + AX25_MAX_HEADER_LEN + NR_NETWORK_LEN + NR_TRANSPORT_LEN;
switch (frametype & 0x0F) {
case NR_CONNREQ:
len += 17;
break;
case NR_CONNACK:
len += (sk->nr->bpqext) ? 2 : 1;
break;
case NR_DISCREQ:
case NR_DISCACK:
case NR_INFOACK:
break;
default:
printk(KERN_ERR "nr_write_internal: invalid frame type %d\n", frametype);
return;
}
if ((skb = alloc_skb(len, GFP_ATOMIC)) == NULL)
return;
/*
* Space for AX.25 and NET/ROM network header
*/
skb_reserve(skb, AX25_BPQ_HEADER_LEN + AX25_MAX_HEADER_LEN + NR_NETWORK_LEN);
dptr = skb_put(skb, skb_tailroom(skb));
switch (frametype & 0x0F) {
case NR_CONNREQ:
timeout = (sk->nr->rtt / PR_SLOWHZ) * 2;
*dptr++ = sk->nr->my_index;
*dptr++ = sk->nr->my_id;
*dptr++ = 0;
*dptr++ = 0;
*dptr++ = frametype;
*dptr++ = sk->window;
memcpy(dptr, &sk->nr->user_addr, AX25_ADDR_LEN);
dptr[6] &= ~LAPB_C;
dptr[6] &= ~LAPB_E;
dptr[6] |= SSSID_SPARE;
dptr += AX25_ADDR_LEN;
memcpy(dptr, &sk->nr->source_addr, AX25_ADDR_LEN);
dptr[6] &= ~LAPB_C;
dptr[6] &= ~LAPB_E;
dptr[6] |= SSSID_SPARE;
dptr += AX25_ADDR_LEN;
*dptr++ = timeout % 256;
*dptr++ = timeout / 256;
break;
case NR_CONNACK:
*dptr++ = sk->nr->your_index;
*dptr++ = sk->nr->your_id;
*dptr++ = sk->nr->my_index;
*dptr++ = sk->nr->my_id;
*dptr++ = frametype;
*dptr++ = sk->window;
if (sk->nr->bpqext) *dptr++ = nr_default.ttl;
break;
case NR_DISCREQ:
case NR_DISCACK:
*dptr++ = sk->nr->your_index;
*dptr++ = sk->nr->your_id;
*dptr++ = 0;
*dptr++ = 0;
*dptr++ = frametype;
break;
case NR_INFOACK:
*dptr++ = sk->nr->your_index;
*dptr++ = sk->nr->your_id;
*dptr++ = 0;
*dptr++ = sk->nr->vr;
*dptr++ = frametype;
break;
}
skb->free = 1;
nr_transmit_buffer(sk, skb);
}
/*
* This routine is called when a Connect Acknowledge with the Choke Flag
* set is needed to refuse a connection.
*/
void nr_transmit_dm(struct sk_buff *skb)
{
struct sk_buff *skbn;
unsigned char *dptr;
int len;
len = AX25_BPQ_HEADER_LEN + AX25_MAX_HEADER_LEN + NR_NETWORK_LEN + NR_TRANSPORT_LEN + 1;
if ((skbn = alloc_skb(len, GFP_ATOMIC)) == NULL)
return;
skb_reserve(skbn, AX25_BPQ_HEADER_LEN + AX25_MAX_HEADER_LEN);
dptr = skb_put(skbn, NR_NETWORK_LEN + NR_TRANSPORT_LEN);
memcpy(dptr, skb->data + 7, AX25_ADDR_LEN);
dptr[6] &= ~LAPB_C;
dptr[6] &= ~LAPB_E;
dptr[6] |= SSSID_SPARE;
dptr += AX25_ADDR_LEN;
memcpy(dptr, skb->data + 0, AX25_ADDR_LEN);
dptr[6] &= ~LAPB_C;
dptr[6] |= LAPB_E;
dptr[6] |= SSSID_SPARE;
dptr += AX25_ADDR_LEN;
*dptr++ = nr_default.ttl;
*dptr++ = skb->data[15];
*dptr++ = skb->data[16];
*dptr++ = 0;
*dptr++ = 0;
*dptr++ = NR_CONNACK | NR_CHOKE_FLAG;
*dptr++ = 0;
skbn->free = 1;
skbn->sk = NULL;
if (!nr_route_frame(skbn, NULL))
kfree_skb(skbn, FREE_WRITE);
}
/*
* Exponential backoff for NET/ROM
*/
unsigned short nr_calculate_t1(struct sock *sk)
{
int n, t;
for (t = 2, n = 0; n < sk->nr->n2count; n++)
t *= 2;
if (t > 8) t = 8;
return t * sk->nr->rtt;
}
/*
* Calculate the Round Trip Time
*/
void nr_calculate_rtt(struct sock *sk)
{
if (sk->nr->t1timer > 0 && sk->nr->n2count == 0)
sk->nr->rtt = (9 * sk->nr->rtt + sk->nr->t1 - sk->nr->t1timer) / 10;
#ifdef NR_T1CLAMPLO
/* Don't go below one tenth of a second */
if (sk->nr->rtt < (NR_T1CLAMPLO))
sk->nr->rtt = (NR_T1CLAMPLO);
#else /* Failsafe - some people might have sub 1/10th RTTs :-) **/
if (sk->nr->rtt == 0)
sk->nr->rtt = PR_SLOWHZ;
#endif
#ifdef NR_T1CLAMPHI
/* OR above clamped seconds **/
if (sk->nr->rtt > (NR_T1CLAMPHI))
sk->nr->rtt = (NR_T1CLAMPHI);
#endif
}
#endif
