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.
313 lines
7.8 KiB
313 lines
7.8 KiB
/*
|
|
* LAPB release 002
|
|
*
|
|
* 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.
|
|
*
|
|
* History
|
|
* LAPB 001 Jonathan Naylor Started Coding
|
|
*/
|
|
|
|
#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/inet.h>
|
|
#include <linux/skbuff.h>
|
|
#include <linux/slab.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>
|
|
#include <net/lapb.h>
|
|
|
|
/*
|
|
* This routine purges all the queues of frames.
|
|
*/
|
|
void lapb_clear_queues(struct lapb_cb *lapb)
|
|
{
|
|
skb_queue_purge(&lapb->write_queue);
|
|
skb_queue_purge(&lapb->ack_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 lapb_frames_acked(struct lapb_cb *lapb, unsigned short nr)
|
|
{
|
|
struct sk_buff *skb;
|
|
int modulus;
|
|
|
|
modulus = (lapb->mode & LAPB_EXTENDED) ? LAPB_EMODULUS : LAPB_SMODULUS;
|
|
|
|
/*
|
|
* Remove all the ack-ed frames from the ack queue.
|
|
*/
|
|
if (lapb->va != nr)
|
|
while (skb_peek(&lapb->ack_queue) && lapb->va != nr) {
|
|
skb = skb_dequeue(&lapb->ack_queue);
|
|
kfree_skb(skb);
|
|
lapb->va = (lapb->va + 1) % modulus;
|
|
}
|
|
}
|
|
|
|
void lapb_requeue_frames(struct lapb_cb *lapb)
|
|
{
|
|
struct sk_buff *skb, *skb_prev = NULL;
|
|
|
|
/*
|
|
* Requeue all the un-ack-ed frames on the output queue to be picked
|
|
* up by lapb_kick called from the timer. This arrangement handles the
|
|
* possibility of an empty output queue.
|
|
*/
|
|
while ((skb = skb_dequeue(&lapb->ack_queue)) != NULL) {
|
|
if (!skb_prev)
|
|
skb_queue_head(&lapb->write_queue, skb);
|
|
else
|
|
skb_append(skb_prev, skb, &lapb->write_queue);
|
|
skb_prev = skb;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Validate that the value of nr is between va and vs. Return true or
|
|
* false for testing.
|
|
*/
|
|
int lapb_validate_nr(struct lapb_cb *lapb, unsigned short nr)
|
|
{
|
|
unsigned short vc = lapb->va;
|
|
int modulus;
|
|
|
|
modulus = (lapb->mode & LAPB_EXTENDED) ? LAPB_EMODULUS : LAPB_SMODULUS;
|
|
|
|
while (vc != lapb->vs) {
|
|
if (nr == vc)
|
|
return 1;
|
|
vc = (vc + 1) % modulus;
|
|
}
|
|
|
|
return nr == lapb->vs;
|
|
}
|
|
|
|
/*
|
|
* This routine is the centralised routine for parsing the control
|
|
* information for the different frame formats.
|
|
*/
|
|
int lapb_decode(struct lapb_cb *lapb, struct sk_buff *skb,
|
|
struct lapb_frame *frame)
|
|
{
|
|
frame->type = LAPB_ILLEGAL;
|
|
|
|
#if LAPB_DEBUG > 2
|
|
printk(KERN_DEBUG "lapb: (%p) S%d RX %02X %02X %02X\n",
|
|
lapb->dev, lapb->state,
|
|
skb->data[0], skb->data[1], skb->data[2]);
|
|
#endif
|
|
|
|
/* We always need to look at 2 bytes, sometimes we need
|
|
* to look at 3 and those cases are handled below.
|
|
*/
|
|
if (!pskb_may_pull(skb, 2))
|
|
return -1;
|
|
|
|
if (lapb->mode & LAPB_MLP) {
|
|
if (lapb->mode & LAPB_DCE) {
|
|
if (skb->data[0] == LAPB_ADDR_D)
|
|
frame->cr = LAPB_COMMAND;
|
|
if (skb->data[0] == LAPB_ADDR_C)
|
|
frame->cr = LAPB_RESPONSE;
|
|
} else {
|
|
if (skb->data[0] == LAPB_ADDR_C)
|
|
frame->cr = LAPB_COMMAND;
|
|
if (skb->data[0] == LAPB_ADDR_D)
|
|
frame->cr = LAPB_RESPONSE;
|
|
}
|
|
} else {
|
|
if (lapb->mode & LAPB_DCE) {
|
|
if (skb->data[0] == LAPB_ADDR_B)
|
|
frame->cr = LAPB_COMMAND;
|
|
if (skb->data[0] == LAPB_ADDR_A)
|
|
frame->cr = LAPB_RESPONSE;
|
|
} else {
|
|
if (skb->data[0] == LAPB_ADDR_A)
|
|
frame->cr = LAPB_COMMAND;
|
|
if (skb->data[0] == LAPB_ADDR_B)
|
|
frame->cr = LAPB_RESPONSE;
|
|
}
|
|
}
|
|
|
|
skb_pull(skb, 1);
|
|
|
|
if (lapb->mode & LAPB_EXTENDED) {
|
|
if (!(skb->data[0] & LAPB_S)) {
|
|
if (!pskb_may_pull(skb, 2))
|
|
return -1;
|
|
/*
|
|
* I frame - carries NR/NS/PF
|
|
*/
|
|
frame->type = LAPB_I;
|
|
frame->ns = (skb->data[0] >> 1) & 0x7F;
|
|
frame->nr = (skb->data[1] >> 1) & 0x7F;
|
|
frame->pf = skb->data[1] & LAPB_EPF;
|
|
frame->control[0] = skb->data[0];
|
|
frame->control[1] = skb->data[1];
|
|
skb_pull(skb, 2);
|
|
} else if ((skb->data[0] & LAPB_U) == 1) {
|
|
if (!pskb_may_pull(skb, 2))
|
|
return -1;
|
|
/*
|
|
* S frame - take out PF/NR
|
|
*/
|
|
frame->type = skb->data[0] & 0x0F;
|
|
frame->nr = (skb->data[1] >> 1) & 0x7F;
|
|
frame->pf = skb->data[1] & LAPB_EPF;
|
|
frame->control[0] = skb->data[0];
|
|
frame->control[1] = skb->data[1];
|
|
skb_pull(skb, 2);
|
|
} else if ((skb->data[0] & LAPB_U) == 3) {
|
|
/*
|
|
* U frame - take out PF
|
|
*/
|
|
frame->type = skb->data[0] & ~LAPB_SPF;
|
|
frame->pf = skb->data[0] & LAPB_SPF;
|
|
frame->control[0] = skb->data[0];
|
|
frame->control[1] = 0x00;
|
|
skb_pull(skb, 1);
|
|
}
|
|
} else {
|
|
if (!(skb->data[0] & LAPB_S)) {
|
|
/*
|
|
* I frame - carries NR/NS/PF
|
|
*/
|
|
frame->type = LAPB_I;
|
|
frame->ns = (skb->data[0] >> 1) & 0x07;
|
|
frame->nr = (skb->data[0] >> 5) & 0x07;
|
|
frame->pf = skb->data[0] & LAPB_SPF;
|
|
} else if ((skb->data[0] & LAPB_U) == 1) {
|
|
/*
|
|
* S frame - take out PF/NR
|
|
*/
|
|
frame->type = skb->data[0] & 0x0F;
|
|
frame->nr = (skb->data[0] >> 5) & 0x07;
|
|
frame->pf = skb->data[0] & LAPB_SPF;
|
|
} else if ((skb->data[0] & LAPB_U) == 3) {
|
|
/*
|
|
* U frame - take out PF
|
|
*/
|
|
frame->type = skb->data[0] & ~LAPB_SPF;
|
|
frame->pf = skb->data[0] & LAPB_SPF;
|
|
}
|
|
|
|
frame->control[0] = skb->data[0];
|
|
|
|
skb_pull(skb, 1);
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* 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, FRMRs are handled
|
|
* by lapb_transmit_frmr below.
|
|
*/
|
|
void lapb_send_control(struct lapb_cb *lapb, int frametype,
|
|
int poll_bit, int type)
|
|
{
|
|
struct sk_buff *skb;
|
|
unsigned char *dptr;
|
|
|
|
if ((skb = alloc_skb(LAPB_HEADER_LEN + 3, GFP_ATOMIC)) == NULL)
|
|
return;
|
|
|
|
skb_reserve(skb, LAPB_HEADER_LEN + 1);
|
|
|
|
if (lapb->mode & LAPB_EXTENDED) {
|
|
if ((frametype & LAPB_U) == LAPB_U) {
|
|
dptr = skb_put(skb, 1);
|
|
*dptr = frametype;
|
|
*dptr |= poll_bit ? LAPB_SPF : 0;
|
|
} else {
|
|
dptr = skb_put(skb, 2);
|
|
dptr[0] = frametype;
|
|
dptr[1] = (lapb->vr << 1);
|
|
dptr[1] |= poll_bit ? LAPB_EPF : 0;
|
|
}
|
|
} else {
|
|
dptr = skb_put(skb, 1);
|
|
*dptr = frametype;
|
|
*dptr |= poll_bit ? LAPB_SPF : 0;
|
|
if ((frametype & LAPB_U) == LAPB_S) /* S frames carry NR */
|
|
*dptr |= (lapb->vr << 5);
|
|
}
|
|
|
|
lapb_transmit_buffer(lapb, skb, type);
|
|
}
|
|
|
|
/*
|
|
* This routine generates FRMRs based on information previously stored in
|
|
* the LAPB control block.
|
|
*/
|
|
void lapb_transmit_frmr(struct lapb_cb *lapb)
|
|
{
|
|
struct sk_buff *skb;
|
|
unsigned char *dptr;
|
|
|
|
if ((skb = alloc_skb(LAPB_HEADER_LEN + 7, GFP_ATOMIC)) == NULL)
|
|
return;
|
|
|
|
skb_reserve(skb, LAPB_HEADER_LEN + 1);
|
|
|
|
if (lapb->mode & LAPB_EXTENDED) {
|
|
dptr = skb_put(skb, 6);
|
|
*dptr++ = LAPB_FRMR;
|
|
*dptr++ = lapb->frmr_data.control[0];
|
|
*dptr++ = lapb->frmr_data.control[1];
|
|
*dptr++ = (lapb->vs << 1) & 0xFE;
|
|
*dptr = (lapb->vr << 1) & 0xFE;
|
|
if (lapb->frmr_data.cr == LAPB_RESPONSE)
|
|
*dptr |= 0x01;
|
|
dptr++;
|
|
*dptr++ = lapb->frmr_type;
|
|
|
|
#if LAPB_DEBUG > 1
|
|
printk(KERN_DEBUG "lapb: (%p) S%d TX FRMR %02X %02X %02X %02X %02X\n",
|
|
lapb->dev, lapb->state,
|
|
skb->data[1], skb->data[2], skb->data[3],
|
|
skb->data[4], skb->data[5]);
|
|
#endif
|
|
} else {
|
|
dptr = skb_put(skb, 4);
|
|
*dptr++ = LAPB_FRMR;
|
|
*dptr++ = lapb->frmr_data.control[0];
|
|
*dptr = (lapb->vs << 1) & 0x0E;
|
|
*dptr |= (lapb->vr << 5) & 0xE0;
|
|
if (lapb->frmr_data.cr == LAPB_RESPONSE)
|
|
*dptr |= 0x10;
|
|
dptr++;
|
|
*dptr++ = lapb->frmr_type;
|
|
|
|
#if LAPB_DEBUG > 1
|
|
printk(KERN_DEBUG "lapb: (%p) S%d TX FRMR %02X %02X %02X\n",
|
|
lapb->dev, lapb->state, skb->data[1],
|
|
skb->data[2], skb->data[3]);
|
|
#endif
|
|
}
|
|
|
|
lapb_transmit_buffer(lapb, skb, LAPB_RESPONSE);
|
|
}
|
|
|