linux/net/ax25/ax25_addr.c
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   1/*
   2 * This program is free software; you can redistribute it and/or modify
   3 * it under the terms of the GNU General Public License as published by
   4 * the Free Software Foundation; either version 2 of the License, or
   5 * (at your option) any later version.
   6 *
   7 * Copyright (C) Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk)
   8 */
   9#include <linux/errno.h>
  10#include <linux/types.h>
  11#include <linux/socket.h>
  12#include <linux/in.h>
  13#include <linux/kernel.h>
  14#include <linux/module.h>
  15#include <linux/timer.h>
  16#include <linux/string.h>
  17#include <linux/sockios.h>
  18#include <linux/net.h>
  19#include <net/ax25.h>
  20#include <linux/inet.h>
  21#include <linux/netdevice.h>
  22#include <linux/skbuff.h>
  23#include <net/sock.h>
  24#include <asm/uaccess.h>
  25#include <linux/fcntl.h>
  26#include <linux/mm.h>
  27#include <linux/interrupt.h>
  28
  29/*
  30 * The default broadcast address of an interface is QST-0; the default address
  31 * is LINUX-1.  The null address is defined as a callsign of all spaces with
  32 * an SSID of zero.
  33 */
  34
  35const ax25_address ax25_bcast =
  36        {{'Q' << 1, 'S' << 1, 'T' << 1, ' ' << 1, ' ' << 1, ' ' << 1, 0 << 1}};
  37const ax25_address ax25_defaddr =
  38        {{'L' << 1, 'I' << 1, 'N' << 1, 'U' << 1, 'X' << 1, ' ' << 1, 1 << 1}};
  39const ax25_address null_ax25_address =
  40        {{' ' << 1, ' ' << 1, ' ' << 1, ' ' << 1, ' ' << 1, ' ' << 1, 0 << 1}};
  41
  42EXPORT_SYMBOL_GPL(ax25_bcast);
  43EXPORT_SYMBOL_GPL(ax25_defaddr);
  44EXPORT_SYMBOL(null_ax25_address);
  45
  46/*
  47 *      ax25 -> ascii conversion
  48 */
  49char *ax2asc(char *buf, const ax25_address *a)
  50{
  51        char c, *s;
  52        int n;
  53
  54        for (n = 0, s = buf; n < 6; n++) {
  55                c = (a->ax25_call[n] >> 1) & 0x7F;
  56
  57                if (c != ' ') *s++ = c;
  58        }
  59
  60        *s++ = '-';
  61
  62        if ((n = ((a->ax25_call[6] >> 1) & 0x0F)) > 9) {
  63                *s++ = '1';
  64                n -= 10;
  65        }
  66
  67        *s++ = n + '0';
  68        *s++ = '\0';
  69
  70        if (*buf == '\0' || *buf == '-')
  71           return "*";
  72
  73        return buf;
  74
  75}
  76
  77EXPORT_SYMBOL(ax2asc);
  78
  79/*
  80 *      ascii -> ax25 conversion
  81 */
  82void asc2ax(ax25_address *addr, const char *callsign)
  83{
  84        const char *s;
  85        int n;
  86
  87        for (s = callsign, n = 0; n < 6; n++) {
  88                if (*s != '\0' && *s != '-')
  89                        addr->ax25_call[n] = *s++;
  90                else
  91                        addr->ax25_call[n] = ' ';
  92                addr->ax25_call[n] <<= 1;
  93                addr->ax25_call[n] &= 0xFE;
  94        }
  95
  96        if (*s++ == '\0') {
  97                addr->ax25_call[6] = 0x00;
  98                return;
  99        }
 100
 101        addr->ax25_call[6] = *s++ - '0';
 102
 103        if (*s != '\0') {
 104                addr->ax25_call[6] *= 10;
 105                addr->ax25_call[6] += *s++ - '0';
 106        }
 107
 108        addr->ax25_call[6] <<= 1;
 109        addr->ax25_call[6] &= 0x1E;
 110}
 111
 112EXPORT_SYMBOL(asc2ax);
 113
 114/*
 115 *      Compare two ax.25 addresses
 116 */
 117int ax25cmp(const ax25_address *a, const ax25_address *b)
 118{
 119        int ct = 0;
 120
 121        while (ct < 6) {
 122                if ((a->ax25_call[ct] & 0xFE) != (b->ax25_call[ct] & 0xFE))     /* Clean off repeater bits */
 123                        return 1;
 124                ct++;
 125        }
 126
 127        if ((a->ax25_call[ct] & 0x1E) == (b->ax25_call[ct] & 0x1E))     /* SSID without control bit */
 128                return 0;
 129
 130        return 2;                       /* Partial match */
 131}
 132
 133EXPORT_SYMBOL(ax25cmp);
 134
 135/*
 136 *      Compare two AX.25 digipeater paths.
 137 */
 138int ax25digicmp(const ax25_digi *digi1, const ax25_digi *digi2)
 139{
 140        int i;
 141
 142        if (digi1->ndigi != digi2->ndigi)
 143                return 1;
 144
 145        if (digi1->lastrepeat != digi2->lastrepeat)
 146                return 1;
 147
 148        for (i = 0; i < digi1->ndigi; i++)
 149                if (ax25cmp(&digi1->calls[i], &digi2->calls[i]) != 0)
 150                        return 1;
 151
 152        return 0;
 153}
 154
 155/*
 156 *      Given an AX.25 address pull of to, from, digi list, command/response and the start of data
 157 *
 158 */
 159const unsigned char *ax25_addr_parse(const unsigned char *buf, int len,
 160        ax25_address *src, ax25_address *dest, ax25_digi *digi, int *flags,
 161        int *dama)
 162{
 163        int d = 0;
 164
 165        if (len < 14) return NULL;
 166
 167        if (flags != NULL) {
 168                *flags = 0;
 169
 170                if (buf[6] & AX25_CBIT)
 171                        *flags = AX25_COMMAND;
 172                if (buf[13] & AX25_CBIT)
 173                        *flags = AX25_RESPONSE;
 174        }
 175
 176        if (dama != NULL)
 177                *dama = ~buf[13] & AX25_DAMA_FLAG;
 178
 179        /* Copy to, from */
 180        if (dest != NULL)
 181                memcpy(dest, buf + 0, AX25_ADDR_LEN);
 182        if (src != NULL)
 183                memcpy(src,  buf + 7, AX25_ADDR_LEN);
 184
 185        buf += 2 * AX25_ADDR_LEN;
 186        len -= 2 * AX25_ADDR_LEN;
 187
 188        digi->lastrepeat = -1;
 189        digi->ndigi      = 0;
 190
 191        while (!(buf[-1] & AX25_EBIT)) {
 192                if (d >= AX25_MAX_DIGIS)
 193                        return NULL;
 194                if (len < AX25_ADDR_LEN)
 195                        return NULL;
 196
 197                memcpy(&digi->calls[d], buf, AX25_ADDR_LEN);
 198                digi->ndigi = d + 1;
 199
 200                if (buf[6] & AX25_HBIT) {
 201                        digi->repeated[d] = 1;
 202                        digi->lastrepeat  = d;
 203                } else {
 204                        digi->repeated[d] = 0;
 205                }
 206
 207                buf += AX25_ADDR_LEN;
 208                len -= AX25_ADDR_LEN;
 209                d++;
 210        }
 211
 212        return buf;
 213}
 214
 215/*
 216 *      Assemble an AX.25 header from the bits
 217 */
 218int ax25_addr_build(unsigned char *buf, const ax25_address *src,
 219        const ax25_address *dest, const ax25_digi *d, int flag, int modulus)
 220{
 221        int len = 0;
 222        int ct  = 0;
 223
 224        memcpy(buf, dest, AX25_ADDR_LEN);
 225        buf[6] &= ~(AX25_EBIT | AX25_CBIT);
 226        buf[6] |= AX25_SSSID_SPARE;
 227
 228        if (flag == AX25_COMMAND) buf[6] |= AX25_CBIT;
 229
 230        buf += AX25_ADDR_LEN;
 231        len += AX25_ADDR_LEN;
 232
 233        memcpy(buf, src, AX25_ADDR_LEN);
 234        buf[6] &= ~(AX25_EBIT | AX25_CBIT);
 235        buf[6] &= ~AX25_SSSID_SPARE;
 236
 237        if (modulus == AX25_MODULUS)
 238                buf[6] |= AX25_SSSID_SPARE;
 239        else
 240                buf[6] |= AX25_ESSID_SPARE;
 241
 242        if (flag == AX25_RESPONSE) buf[6] |= AX25_CBIT;
 243
 244        /*
 245         *      Fast path the normal digiless path
 246         */
 247        if (d == NULL || d->ndigi == 0) {
 248                buf[6] |= AX25_EBIT;
 249                return 2 * AX25_ADDR_LEN;
 250        }
 251
 252        buf += AX25_ADDR_LEN;
 253        len += AX25_ADDR_LEN;
 254
 255        while (ct < d->ndigi) {
 256                memcpy(buf, &d->calls[ct], AX25_ADDR_LEN);
 257
 258                if (d->repeated[ct])
 259                        buf[6] |= AX25_HBIT;
 260                else
 261                        buf[6] &= ~AX25_HBIT;
 262
 263                buf[6] &= ~AX25_EBIT;
 264                buf[6] |= AX25_SSSID_SPARE;
 265
 266                buf += AX25_ADDR_LEN;
 267                len += AX25_ADDR_LEN;
 268                ct++;
 269        }
 270
 271        buf[-1] |= AX25_EBIT;
 272
 273        return len;
 274}
 275
 276int ax25_addr_size(const ax25_digi *dp)
 277{
 278        if (dp == NULL)
 279                return 2 * AX25_ADDR_LEN;
 280
 281        return AX25_ADDR_LEN * (2 + dp->ndigi);
 282}
 283
 284/*
 285 *      Reverse Digipeat List. May not pass both parameters as same struct
 286 */
 287void ax25_digi_invert(const ax25_digi *in, ax25_digi *out)
 288{
 289        int ct;
 290
 291        out->ndigi      = in->ndigi;
 292        out->lastrepeat = in->ndigi - in->lastrepeat - 2;
 293
 294        /* Invert the digipeaters */
 295        for (ct = 0; ct < in->ndigi; ct++) {
 296                out->calls[ct] = in->calls[in->ndigi - ct - 1];
 297
 298                if (ct <= out->lastrepeat) {
 299                        out->calls[ct].ax25_call[6] |= AX25_HBIT;
 300                        out->repeated[ct]            = 1;
 301                } else {
 302                        out->calls[ct].ax25_call[6] &= ~AX25_HBIT;
 303                        out->repeated[ct]            = 0;
 304                }
 305        }
 306}
 307
 308
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