/*
 * 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 <asm/system.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;  /* 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, 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;
                }
        }
}