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/*
* AX.25 release 037
*
* This code REQUIRES 2.1.15 or higher/ NET3.038
*
* 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.
*
* Most of this code is based on the SDL diagrams published in the 7th
* ARRL Computer Networking Conference papers. The diagrams have mistakes
* in them, but are mostly correct. Before you modify the code could you
* read the SDL diagrams as the code is not obvious and probably very
* easy to break;
*
* History
* AX.25 028a Jonathan(G4KLX) New state machine based on SDL diagrams.
* AX.25 029 Alan(GW4PTS) Switched to KA9Q constant names.
* Jonathan(G4KLX) Only poll when window is full.
* AX.25 030 Jonathan(G4KLX) Added fragmentation to ax25_output.
* Added support for extended AX.25.
* AX.25 031 Joerg(DL1BKE) Added DAMA support
* Joerg(DL1BKE) Modified fragmenter to fragment vanilla
* AX.25 I-Frames. Added PACLEN parameter.
* Joerg(DL1BKE) Fixed a problem with buffer allocation
* for fragments.
* AX.25 037 Jonathan(G4KLX) New timer architecture.
* Joerg(DL1BKE) Fixed DAMA Slave mode: will work
* on non-DAMA interfaces like AX25L2V2
* again (this behaviour is _required_).
* Joerg(DL1BKE) ax25_check_iframes_acked() returns a
* value now (for DAMA n2count handling)
*/
#include <linux/config.h>
#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 <linux/netfilter.h>
#include <net/sock.h>
#include <asm/uaccess.h>
#include <asm/system.h>
#include <linux/fcntl.h>
#include <linux/mm.h>
#include <linux/interrupt.h>
ax25_cb *ax25_send_frame(struct sk_buff *skb, int paclen, ax25_address *src, ax25_address *dest, ax25_digi *digi, struct net_device *dev)
{
ax25_dev *ax25_dev;
ax25_cb *ax25;
/*
* Take the default packet length for the device if zero is
* specified.
*/
if (paclen == 0) {
if ((ax25_dev = ax25_dev_ax25dev(dev)) == NULL)
return NULL;
paclen = ax25_dev->values[AX25_VALUES_PACLEN];
}
/*
* Look for an existing connection.
*/
if ((ax25 = ax25_find_cb(src, dest, digi, dev)) != NULL) {
ax25_output(ax25, paclen, skb);
return ax25; /* It already existed */
}
if ((ax25_dev = ax25_dev_ax25dev(dev)) == NULL)
return NULL;
if ((ax25 = ax25_create_cb()) == NULL)
return NULL;
ax25_fillin_cb(ax25, ax25_dev);
ax25->source_addr = *src;
ax25->dest_addr = *dest;
if (digi != NULL) {
if ((ax25->digipeat = kmalloc(sizeof(ax25_digi), GFP_ATOMIC)) == NULL) {
ax25_free_cb(ax25);
return NULL;
}
memcpy(ax25->digipeat, digi, sizeof(ax25_digi));
}
switch (ax25->ax25_dev->values[AX25_VALUES_PROTOCOL]) {
case AX25_PROTO_STD_SIMPLEX:
case AX25_PROTO_STD_DUPLEX:
ax25_std_establish_data_link(ax25);
break;
#ifdef CONFIG_AX25_DAMA_SLAVE
case AX25_PROTO_DAMA_SLAVE:
if (ax25_dev->dama.slave)
ax25_ds_establish_data_link(ax25);
else
ax25_std_establish_data_link(ax25);
break;
#endif
}
ax25_insert_socket(ax25);
ax25->state = AX25_STATE_1;
ax25_start_heartbeat(ax25);
ax25_output(ax25, paclen, skb);
return ax25; /* We had to create it */
}
/*
* All outgoing AX.25 I frames pass via this routine. Therefore this is
* where the fragmentation of frames takes place. If fragment is set to
* zero then we are not allowed to do fragmentation, even if the frame
* is too large.
*/
void ax25_output(ax25_cb *ax25, int paclen, struct sk_buff *skb)
{
struct sk_buff *skbn;
unsigned char *p;
int frontlen, len, fragno, ka9qfrag, first = 1;
long flags;
if ((skb->len - 1) > paclen) {
if (*skb->data == AX25_P_TEXT) {
skb_pull(skb, 1); /* skip PID */
ka9qfrag = 0;
} else {
paclen -= 2; /* Allow for fragment control info */
ka9qfrag = 1;
}
fragno = skb->len / paclen;
if (skb->len % paclen == 0) fragno--;
frontlen = skb_headroom(skb); /* Address space + CTRL */
while (skb->len > 0) {
save_flags(flags);
cli();
if ((skbn = alloc_skb(paclen + 2 + frontlen, GFP_ATOMIC)) == NULL) {
restore_flags(flags);
printk(KERN_CRIT "AX.25: ax25_output - out of memory\n");
return;
}
if (skb->sk != NULL)
skb_set_owner_w(skbn, skb->sk);
restore_flags(flags);
len = (paclen > skb->len) ? skb->len : paclen;
if (ka9qfrag == 1) {
skb_reserve(skbn, frontlen + 2);
skbn->nh.raw = skbn->data + (skb->nh.raw - skb->data);
memcpy(skb_put(skbn, len), skb->data, len);
p = skb_push(skbn, 2);
*p++ = AX25_P_SEGMENT;
*p = fragno--;
if (first) {
*p |= AX25_SEG_FIRST;
first = 0;
}
} else {
skb_reserve(skbn, frontlen + 1);
skbn->nh.raw = skbn->data + (skb->nh.raw - skb->data);
memcpy(skb_put(skbn, len), skb->data, len);
p = skb_push(skbn, 1);
*p = AX25_P_TEXT;
}
skb_pull(skb, len);
skb_queue_tail(&ax25->write_queue, skbn); /* Throw it on the queue */
}
kfree_skb(skb);
} else {
skb_queue_tail(&ax25->write_queue, skb); /* Throw it on the queue */
}
switch (ax25->ax25_dev->values[AX25_VALUES_PROTOCOL]) {
case AX25_PROTO_STD_SIMPLEX:
case AX25_PROTO_STD_DUPLEX:
ax25_kick(ax25);
break;
#ifdef CONFIG_AX25_DAMA_SLAVE
/*
* A DAMA slave is _required_ to work as normal AX.25L2V2
* if no DAMA master is available.
*/
case AX25_PROTO_DAMA_SLAVE:
if (!ax25->ax25_dev->dama.slave) ax25_kick(ax25);
break;
#endif
}
}
/*
* 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 ax25_send_iframe(ax25_cb *ax25, struct sk_buff *skb, int poll_bit)
{
unsigned char *frame;
if (skb == NULL)
return;
skb->nh.raw = skb->data;
if (ax25->modulus == AX25_MODULUS) {
frame = skb_push(skb, 1);
*frame = AX25_I;
*frame |= (poll_bit) ? AX25_PF : 0;
*frame |= (ax25->vr << 5);
*frame |= (ax25->vs << 1);
} else {
frame = skb_push(skb, 2);
frame[0] = AX25_I;
frame[0] |= (ax25->vs << 1);
frame[1] = (poll_bit) ? AX25_EPF : 0;
frame[1] |= (ax25->vr << 1);
}
ax25_start_idletimer(ax25);
ax25_transmit_buffer(ax25, skb, AX25_COMMAND);
}
void ax25_kick(ax25_cb *ax25)
{
struct sk_buff *skb, *skbn;
int last = 1;
unsigned short start, end, next;
if (ax25->state != AX25_STATE_3 && ax25->state != AX25_STATE_4)
return;
if (ax25->condition & AX25_COND_PEER_RX_BUSY)
return;
if (skb_peek(&ax25->write_queue) == NULL)
return;
start = (skb_peek(&ax25->ack_queue) == NULL) ? ax25->va : ax25->vs;
end = (ax25->va + ax25->window) % ax25->modulus;
if (start == end)
return;
ax25->vs = start;
/*
* Transmit data until either we're out of data to send or
* the window is full. Send a poll on the final I frame if
* the window is filled.
*/
/*
* Dequeue the frame and copy it.
*/
skb = skb_dequeue(&ax25->write_queue);
do {
if ((skbn = skb_clone(skb, GFP_ATOMIC)) == NULL) {
skb_queue_head(&ax25->write_queue, skb);
break;
}
if (skb->sk != NULL)
skb_set_owner_w(skbn, skb->sk);
next = (ax25->vs + 1) % ax25->modulus;
last = (next == end);
/*
* Transmit the frame copy.
* bke 960114: do not set the Poll bit on the last frame
* in DAMA mode.
*/
switch (ax25->ax25_dev->values[AX25_VALUES_PROTOCOL]) {
case AX25_PROTO_STD_SIMPLEX:
case AX25_PROTO_STD_DUPLEX:
ax25_send_iframe(ax25, skbn, (last) ? AX25_POLLON : AX25_POLLOFF);
break;
#ifdef CONFIG_AX25_DAMA_SLAVE
case AX25_PROTO_DAMA_SLAVE:
ax25_send_iframe(ax25, skbn, AX25_POLLOFF);
break;
#endif
}
ax25->vs = next;
/*
* Requeue the original data frame.
*/
skb_queue_tail(&ax25->ack_queue, skb);
} while (!last && (skb = skb_dequeue(&ax25->write_queue)) != NULL);
ax25->condition &= ~AX25_COND_ACK_PENDING;
if (!ax25_t1timer_running(ax25)) {
ax25_stop_t3timer(ax25);
ax25_calculate_t1(ax25);
ax25_start_t1timer(ax25);
}
}
void ax25_transmit_buffer(ax25_cb *ax25, struct sk_buff *skb, int type)
{
struct sk_buff *skbn;
unsigned char *ptr;
int headroom;
if (ax25->ax25_dev == NULL) {
ax25_disconnect(ax25, ENETUNREACH);
return;
}
headroom = ax25_addr_size(ax25->digipeat);
if (skb_headroom(skb) < headroom) {
if ((skbn = skb_realloc_headroom(skb, headroom)) == NULL) {
printk(KERN_CRIT "AX.25: ax25_transmit_buffer - out of memory\n");
kfree_skb(skb);
return;
}
if (skb->sk != NULL)
skb_set_owner_w(skbn, skb->sk);
kfree_skb(skb);
skb = skbn;
}
ptr = skb_push(skb, headroom);
ax25_addr_build(ptr, &ax25->source_addr, &ax25->dest_addr, ax25->digipeat, type, ax25->modulus);
skb->dev = ax25->ax25_dev->dev;
ax25_queue_xmit(skb);
}
/*
* A small shim to dev_queue_xmit to add the KISS control byte, and do
* any packet forwarding in operation.
*/
void ax25_queue_xmit(struct sk_buff *skb)
{
unsigned char *ptr;
skb->protocol = htons(ETH_P_AX25);
skb->dev = ax25_fwd_dev(skb->dev);
ptr = skb_push(skb, 1);
*ptr = 0x00; /* KISS */
dev_queue_xmit(skb);
}
int ax25_check_iframes_acked(ax25_cb *ax25, unsigned short nr)
{
if (ax25->vs == nr) {
ax25_frames_acked(ax25, nr);
ax25_calculate_rtt(ax25);
ax25_stop_t1timer(ax25);
ax25_start_t3timer(ax25);
return 1;
} else {
if (ax25->va != nr) {
ax25_frames_acked(ax25, nr);
ax25_calculate_t1(ax25);
ax25_start_t1timer(ax25);
return 1;
}
}
return 0;
}
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