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 <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
  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)  return NULL;  /* Max of 6 digis */
 193                 if (len < 7) return NULL;       /* Short packet */
 194
 195                 memcpy(&digi->calls[d], buf, AX25_ADDR_LEN);
 196                 digi->ndigi = d + 1;
 197
 198                 if (buf[6] & AX25_HBIT) {
 199                         digi->repeated[d] = 1;
 200                         digi->lastrepeat  = d;
 201                 } else {
 202                         digi->repeated[d] = 0;
 203                 }
 204
 205                 buf += AX25_ADDR_LEN;
 206                 len -= AX25_ADDR_LEN;
 207                 d++;
 208         }
 209
 210         return buf;
 211 }
 212
 213 /*
 214  *      Assemble an AX.25 header from the bits
 215  */
 216 int ax25_addr_build(unsigned char *buf, const ax25_address *src,
 217         const ax25_address *dest, const ax25_digi *d, int flag, int modulus)
 218 {
 219         int len = 0;
 220         int ct  = 0;
 221
 222         memcpy(buf, dest, AX25_ADDR_LEN);
 223         buf[6] &= ~(AX25_EBIT | AX25_CBIT);
 224         buf[6] |= AX25_SSSID_SPARE;
 225
 226         if (flag == AX25_COMMAND) buf[6] |= AX25_CBIT;
 227
 228         buf += AX25_ADDR_LEN;
 229         len += AX25_ADDR_LEN;
 230
 231         memcpy(buf, src, AX25_ADDR_LEN);
 232         buf[6] &= ~(AX25_EBIT | AX25_CBIT);
 233         buf[6] &= ~AX25_SSSID_SPARE;
 234
 235         if (modulus == AX25_MODULUS)
 236                 buf[6] |= AX25_SSSID_SPARE;
 237         else
 238                 buf[6] |= AX25_ESSID_SPARE;
 239
 240         if (flag == AX25_RESPONSE) buf[6] |= AX25_CBIT;
 241
 242         /*
 243          *      Fast path the normal digiless path
 244          */
 245         if (d == NULL || d->ndigi == 0) {
 246                 buf[6] |= AX25_EBIT;
 247                 return 2 * AX25_ADDR_LEN;
 248         }
 249
 250         buf += AX25_ADDR_LEN;
 251         len += AX25_ADDR_LEN;
 252
 253         while (ct < d->ndigi) {
 254                 memcpy(buf, &d->calls[ct], AX25_ADDR_LEN);
 255
 256                 if (d->repeated[ct])
 257                         buf[6] |= AX25_HBIT;
 258                 else
 259                         buf[6] &= ~AX25_HBIT;
 260
 261                 buf[6] &= ~AX25_EBIT;
 262                 buf[6] |= AX25_SSSID_SPARE;
 263
 264                 buf += AX25_ADDR_LEN;
 265                 len += AX25_ADDR_LEN;
 266                 ct++;
 267         }
 268
 269         buf[-1] |= AX25_EBIT;
 270
 271         return len;
 272 }
 273
 274 int ax25_addr_size(const ax25_digi *dp)
 275 {
 276         if (dp == NULL)
 277                 return 2 * AX25_ADDR_LEN;
 278
 279         return AX25_ADDR_LEN * (2 + dp->ndigi);
 280 }
 281
 282 /*
 283  *      Reverse Digipeat List. May not pass both parameters as same struct
 284  */
 285 void ax25_digi_invert(const ax25_digi *in, ax25_digi *out)
 286 {
 287         int ct;
 288
 289         out->ndigi      = in->ndigi;
 290         out->lastrepeat = in->ndigi - in->lastrepeat - 2;
 291
 292         /* Invert the digipeaters */
 293         for (ct = 0; ct < in->ndigi; ct++) {
 294                 out->calls[ct] = in->calls[in->ndigi - ct - 1];
 295
 296                 if (ct <= out->lastrepeat) {
 297                         out->calls[ct].ax25_call[6] |= AX25_HBIT;
 298                         out->repeated[ct]            = 1;
 299                 } else {
 300                         out->calls[ct].ax25_call[6] &= ~AX25_HBIT;
 301                         out->repeated[ct]            = 0;
 302                 }
 303         }
 304 }
 305