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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.25 036 Jonathan(G4KLX) Split from ax25_subr.c.
*/
#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/uaccess.h>
#include <asm/system.h>
#include <linux/fcntl.h>
#include <linux/mm.h>
#include <linux/interrupt.h>
/*
* The null address is defined as a callsign of all spaces with an
* SSID of zero.
*/
ax25_address null_ax25_address = {{0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x00}};
/*
* ax25 -> ascii conversion
*/
char *ax2asc(ax25_address *a)
{
static char buf[11];
char c, *s;
int n;
for (n = 0, s = buf; n < 6; n++) {
c = (a->ax25_call[n] >> 1) & 0x7F;
if (c != ' ') *s++ = c;
}
*s++ = '-';
if ((n = ((a->ax25_call[6] >> 1) & 0x0F)) > 9) {
*s++ = '1';
n -= 10;
}
*s++ = n + '0';
*s++ = '\0';
if (*buf == '\0' || *buf == '-')
return "*";
return buf;
}
/*
* ascii -> ax25 conversion
*/
ax25_address *asc2ax(char *callsign)
{
static ax25_address addr;
char *s;
int n;
for (s = callsign, n = 0; n < 6; n++) {
if (*s != '\0' && *s != '-')
addr.ax25_call[n] = *s++;
else
addr.ax25_call[n] = ' ';
addr.ax25_call[n] <<= 1;
addr.ax25_call[n] &= 0xFE;
}
if (*s++ == '\0') {
addr.ax25_call[6] = 0x00;
return &addr;
}
addr.ax25_call[6] = *s++ - '0';
if (*s != '\0') {
addr.ax25_call[6] *= 10;
addr.ax25_call[6] += *s++ - '0';
}
addr.ax25_call[6] <<= 1;
addr.ax25_call[6] &= 0x1E;
return &addr;
}
/*
* Compare two ax.25 addresses
*/
int ax25cmp(ax25_address *a, ax25_address *b)
{
int ct = 0;
while (ct < 6) {
if ((a->ax25_call[ct] & 0xFE) != (b->ax25_call[ct] & 0xFE)) /* Clean off repeater bits */
return 1;
ct++;
}
if ((a->ax25_call[ct] & 0x1E) == (b->ax25_call[ct] & 0x1E)) /* SSID without control bit */
return 0;
return 2; /* Partial match */
}
/*
* Compare two AX.25 digipeater paths.
*/
int ax25digicmp(ax25_digi *digi1, ax25_digi *digi2)
{
int i;
if (digi1->ndigi != digi2->ndigi)
return 1;
if (digi1->lastrepeat != digi2->lastrepeat)
return 1;
for (i = 0; i < digi1->ndigi; i++)
if (ax25cmp(&digi1->calls[i], &digi2->calls[i]) != 0)
return 1;
return 0;
}
/*
* Given an AX.25 address pull of to, from, digi list, command/response and the start of data
*
*/
unsigned char *ax25_addr_parse(unsigned char *buf, int len, ax25_address *src, ax25_address *dest, ax25_digi *digi, int *flags, int *dama)
{
int d = 0;
if (len < 14) return NULL;
if (flags != NULL) {
*flags = 0;
if (buf[6] & AX25_CBIT)
*flags = AX25_COMMAND;
if (buf[13] & AX25_CBIT)
*flags = AX25_RESPONSE;
}
if (dama != NULL)
*dama = ~buf[13] & AX25_DAMA_FLAG;
/* Copy to, from */
if (dest != NULL)
memcpy(dest, buf + 0, AX25_ADDR_LEN);
if (src != NULL)
memcpy(src, buf + 7, AX25_ADDR_LEN);
buf += 2 * AX25_ADDR_LEN;
len -= 2 * AX25_ADDR_LEN;
digi->lastrepeat = -1;
digi->ndigi = 0;
while (!(buf[-1] & AX25_EBIT)) {
if (d >= AX25_MAX_DIGIS) return NULL; /* Max of 6 digis */
if (len < 7) return NULL; /* Short packet */
memcpy(&digi->calls[d], buf, AX25_ADDR_LEN);
digi->ndigi = d + 1;
if (buf[6] & AX25_HBIT) {
digi->repeated[d] = 1;
digi->lastrepeat = d;
} else {
digi->repeated[d] = 0;
}
buf += AX25_ADDR_LEN;
len -= AX25_ADDR_LEN;
d++;
}
return buf;
}
/*
* Assemble an AX.25 header from the bits
*/
int ax25_addr_build(unsigned char *buf, ax25_address *src, ax25_address *dest, ax25_digi *d, int flag, int modulus)
{
int len = 0;
int ct = 0;
memcpy(buf, dest, AX25_ADDR_LEN);
buf[6] &= ~(AX25_EBIT | AX25_CBIT);
buf[6] |= AX25_SSSID_SPARE;
if (flag == AX25_COMMAND) buf[6] |= AX25_CBIT;
buf += AX25_ADDR_LEN;
len += AX25_ADDR_LEN;
memcpy(buf, src, AX25_ADDR_LEN);
buf[6] &= ~(AX25_EBIT | AX25_CBIT);
buf[6] &= ~AX25_SSSID_SPARE;
if (modulus == AX25_MODULUS)
buf[6] |= AX25_SSSID_SPARE;
else
buf[6] |= AX25_ESSID_SPARE;
if (flag == AX25_RESPONSE) buf[6] |= AX25_CBIT;
/*
* Fast path the normal digiless path
*/
if (d == NULL || d->ndigi == 0) {
buf[6] |= AX25_EBIT;
return 2 * AX25_ADDR_LEN;
}
buf += AX25_ADDR_LEN;
len += AX25_ADDR_LEN;
while (ct < d->ndigi) {
memcpy(buf, &d->calls[ct], AX25_ADDR_LEN);
if (d->repeated[ct])
buf[6] |= AX25_HBIT;
else
buf[6] &= ~AX25_HBIT;
buf[6] &= ~AX25_EBIT;
buf[6] |= AX25_SSSID_SPARE;
buf += AX25_ADDR_LEN;
len += AX25_ADDR_LEN;
ct++;
}
buf[-1] |= AX25_EBIT;
return len;
}
int ax25_addr_size(ax25_digi *dp)
{
if (dp == NULL)
return 2 * AX25_ADDR_LEN;
return AX25_ADDR_LEN * (2 + dp->ndigi);
}
/*
* Reverse Digipeat List. May not pass both parameters as same struct
*/
void ax25_digi_invert(ax25_digi *in, ax25_digi *out)
{
int ct;
out->ndigi = in->ndigi;
out->lastrepeat = in->ndigi - in->lastrepeat - 2;
/* Invert the digipeaters */
for (ct = 0; ct < in->ndigi; ct++) {
out->calls[ct] = in->calls[in->ndigi - ct - 1];
if (ct <= out->lastrepeat) {
out->calls[ct].ax25_call[6] |= AX25_HBIT;
out->repeated[ct] = 1;
} else {
out->calls[ct].ax25_call[6] &= ~AX25_HBIT;
out->repeated[ct] = 0;
}
}
}
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