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