/*
   * This program 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.
   *
   * Copyright (C) Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk)
   */
  #include <linux/errno.h>
  #include <linux/types.h>
  #include <linux/socket.h>
  #include <linux/in.h>
  #include <linux/kernel.h>

  #include <linux/module.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 <linux/fcntl.h>
  #include <linux/mm.h>
  #include <linux/interrupt.h>
  
  /*

   * The default broadcast address of an interface is QST-0; the default address
   * is LINUX-1.  The null address is defined as a callsign of all spaces with
   * an SSID of zero.

   */

  const ax25_address ax25_bcast =
  	{{'Q' << 1, 'S' << 1, 'T' << 1, ' ' << 1, ' ' << 1, ' ' << 1, 0 << 1}};
  const ax25_address ax25_defaddr =
  	{{'L' << 1, 'I' << 1, 'N' << 1, 'U' << 1, 'X' << 1, ' ' << 1, 1 << 1}};
  const ax25_address null_ax25_address =
  	{{' ' << 1, ' ' << 1, ' ' << 1, ' ' << 1, ' ' << 1, ' ' << 1, 0 << 1}};
  
  EXPORT_SYMBOL_GPL(ax25_bcast);
  EXPORT_SYMBOL_GPL(ax25_defaddr);

  EXPORT_SYMBOL(null_ax25_address);

  /*
   *	ax25 -> ascii conversion
   */

  char *ax2asc(char *buf, const ax25_address *a)

  {

  	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;
  
  }

  EXPORT_SYMBOL(ax2asc);

  /*
   *	ascii -> ax25 conversion
   */

  void asc2ax(ax25_address *addr, const char *callsign)

  {

  	const 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->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;

  }

  EXPORT_SYMBOL(asc2ax);

  /*
   *	Compare two ax.25 addresses
   */

  int ax25cmp(const ax25_address *a, const 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 */

  }

  EXPORT_SYMBOL(ax25cmp);

  /*
   *	Compare two AX.25 digipeater paths.
   */

  int ax25digicmp(const ax25_digi *digi1, const 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
   *
   */

  const unsigned char *ax25_addr_parse(const 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;
  		if (len < AX25_ADDR_LEN)
  			return NULL;

  
  		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, const ax25_address *src,
  	const ax25_address *dest, const 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(const 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(const 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;
  		}
  	}
  }