net/ax25/ax25_addr.c

   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 <linux/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
  35 const ax25_address ax25_bcast =
  36         {{'Q' << 1, 'S' << 1, 'T' << 1, ' ' << 1, ' ' << 1, ' ' << 1, 0 << 1}};
  37 const ax25_address ax25_defaddr =
  38         {{'L' << 1, 'I' << 1, 'N' << 1, 'U' << 1, 'X' << 1, ' ' << 1, 1 << 1}};
  39 const ax25_address null_ax25_address =
  40         {{' ' << 1, ' ' << 1, ' ' << 1, ' ' << 1, ' ' << 1, ' ' << 1, 0 << 1}};
  41
  42 EXPORT_SYMBOL_GPL(ax25_bcast);
  43 EXPORT_SYMBOL_GPL(ax25_defaddr);
  44 EXPORT_SYMBOL(null_ax25_address);
  45
  46 /*
  47  *      ax25 -> ascii conversion
  48  */
  49 char *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
  77 EXPORT_SYMBOL(ax2asc);
  78
  79 /*
  80  *      ascii -> ax25 conversion
  81  */
  82 void 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
 112 EXPORT_SYMBOL(asc2ax);
 113
 114 /*
 115  *      Compare two ax.25 addresses
 116  */
 117 int 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
 133 EXPORT_SYMBOL(ax25cmp);
 134
 135 /*
 136  *      Compare two AX.25 digipeater paths.
 137  */
 138 int 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  */
 159 const 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  */
 218 int 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
 276 int 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  */
 287 void 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 }