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/sched.h>
  16 #include <linux/timer.h>
  17 #include <linux/string.h>
  18 #include <linux/sockios.h>
  19 #include <linux/net.h>
  20 #include <net/ax25.h>
  21 #include <linux/inet.h>
  22 #include <linux/netdevice.h>
  23 #include <linux/skbuff.h>
  24 #include <net/sock.h>
  25 #include <asm/uaccess.h>
  26 #include <asm/system.h>
  27 #include <linux/fcntl.h>
  28 #include <linux/mm.h>
  29 #include <linux/interrupt.h>
  30
  31 /*
  32  *      The null address is defined as a callsign of all spaces with an
  33  *      SSID of zero.
  34  */
  35 ax25_address null_ax25_address = {{0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x00}};
  36
  37 EXPORT_SYMBOL(null_ax25_address);
  38
  39 /*
  40  *      ax25 -> ascii conversion
  41  */
  42 char *ax2asc(char *buf, ax25_address *a)
  43 {
  44         char c, *s;
  45         int n;
  46
  47         for (n = 0, s = buf; n < 6; n++) {
  48                 c = (a->ax25_call[n] >> 1) & 0x7F;
  49
  50                 if (c != ' ') *s++ = c;
  51         }
  52
  53         *s++ = '-';
  54
  55         if ((n = ((a->ax25_call[6] >> 1) & 0x0F)) > 9) {
  56                 *s++ = '1';
  57                 n -= 10;
  58         }
  59
  60         *s++ = n + '0';
  61         *s++ = '\0';
  62
  63         if (*buf == '\0' || *buf == '-')
  64            return "*";
  65
  66         return buf;
  67
  68 }
  69
  70 EXPORT_SYMBOL(ax2asc);
  71
  72 /*
  73  *      ascii -> ax25 conversion
  74  */
  75 void asc2ax(ax25_address *addr, char *callsign)
  76 {
  77         char *s;
  78         int n;
  79
  80         for (s = callsign, n = 0; n < 6; n++) {
  81                 if (*s != '\0' && *s != '-')
  82                         addr->ax25_call[n] = *s++;
  83                 else
  84                         addr->ax25_call[n] = ' ';
  85                 addr->ax25_call[n] <<= 1;
  86                 addr->ax25_call[n] &= 0xFE;
  87         }
  88
  89         if (*s++ == '\0') {
  90                 addr->ax25_call[6] = 0x00;
  91                 return;
  92         }
  93
  94         addr->ax25_call[6] = *s++ - '0';
  95
  96         if (*s != '\0') {
  97                 addr->ax25_call[6] *= 10;
  98                 addr->ax25_call[6] += *s++ - '0';
  99         }
 100
 101         addr->ax25_call[6] <<= 1;
 102         addr->ax25_call[6] &= 0x1E;
 103 }
 104
 105 EXPORT_SYMBOL(asc2ax);
 106
 107 /*
 108  *      Compare two ax.25 addresses
 109  */
 110 int ax25cmp(ax25_address *a, ax25_address *b)
 111 {
 112         int ct = 0;
 113
 114         while (ct < 6) {
 115                 if ((a->ax25_call[ct] & 0xFE) != (b->ax25_call[ct] & 0xFE))     /* Clean off repeater bits */
 116                         return 1;
 117                 ct++;
 118         }
 119
 120         if ((a->ax25_call[ct] & 0x1E) == (b->ax25_call[ct] & 0x1E))     /* SSID without control bit */
 121                 return 0;
 122
 123         return 2;                       /* Partial match */
 124 }
 125
 126 EXPORT_SYMBOL(ax25cmp);
 127
 128 /*
 129  *      Compare two AX.25 digipeater paths.
 130  */
 131 int ax25digicmp(ax25_digi *digi1, ax25_digi *digi2)
 132 {
 133         int i;
 134
 135         if (digi1->ndigi != digi2->ndigi)
 136                 return 1;
 137
 138         if (digi1->lastrepeat != digi2->lastrepeat)
 139                 return 1;
 140
 141         for (i = 0; i < digi1->ndigi; i++)
 142                 if (ax25cmp(&digi1->calls[i], &digi2->calls[i]) != 0)
 143                         return 1;
 144
 145         return 0;
 146 }
 147
 148 /*
 149  *      Given an AX.25 address pull of to, from, digi list, command/response and the start of data
 150  *
 151  */
 152 unsigned char *ax25_addr_parse(unsigned char *buf, int len, ax25_address *src, ax25_address *dest, ax25_digi *digi, int *flags, int *dama)
 153 {
 154         int d = 0;
 155
 156         if (len < 14) return NULL;
 157
 158         if (flags != NULL) {
 159                 *flags = 0;
 160
 161                 if (buf[6] & AX25_CBIT)
 162                         *flags = AX25_COMMAND;
 163                 if (buf[13] & AX25_CBIT)
 164                         *flags = AX25_RESPONSE;
 165         }
 166
 167         if (dama != NULL)
 168                 *dama = ~buf[13] & AX25_DAMA_FLAG;
 169
 170         /* Copy to, from */
 171         if (dest != NULL)
 172                 memcpy(dest, buf + 0, AX25_ADDR_LEN);
 173         if (src != NULL)
 174                 memcpy(src,  buf + 7, AX25_ADDR_LEN);
 175
 176         buf += 2 * AX25_ADDR_LEN;
 177         len -= 2 * AX25_ADDR_LEN;
 178
 179         digi->lastrepeat = -1;
 180         digi->ndigi      = 0;
 181
 182         while (!(buf[-1] & AX25_EBIT)) {
 183                 if (d >= AX25_MAX_DIGIS)  return NULL;  /* Max of 6 digis */
 184                 if (len < 7) return NULL;       /* Short packet */
 185
 186                 memcpy(&digi->calls[d], buf, AX25_ADDR_LEN);
 187                 digi->ndigi = d + 1;
 188
 189                 if (buf[6] & AX25_HBIT) {
 190                         digi->repeated[d] = 1;
 191                         digi->lastrepeat  = d;
 192                 } else {
 193                         digi->repeated[d] = 0;
 194                 }
 195
 196                 buf += AX25_ADDR_LEN;
 197                 len -= AX25_ADDR_LEN;
 198                 d++;
 199         }
 200
 201         return buf;
 202 }
 203
 204 /*
 205  *      Assemble an AX.25 header from the bits
 206  */
 207 int ax25_addr_build(unsigned char *buf, ax25_address *src, ax25_address *dest, ax25_digi *d, int flag, int modulus)
 208 {
 209         int len = 0;
 210         int ct  = 0;
 211
 212         memcpy(buf, dest, AX25_ADDR_LEN);
 213         buf[6] &= ~(AX25_EBIT | AX25_CBIT);
 214         buf[6] |= AX25_SSSID_SPARE;
 215
 216         if (flag == AX25_COMMAND) buf[6] |= AX25_CBIT;
 217
 218         buf += AX25_ADDR_LEN;
 219         len += AX25_ADDR_LEN;
 220
 221         memcpy(buf, src, AX25_ADDR_LEN);
 222         buf[6] &= ~(AX25_EBIT | AX25_CBIT);
 223         buf[6] &= ~AX25_SSSID_SPARE;
 224
 225         if (modulus == AX25_MODULUS)
 226                 buf[6] |= AX25_SSSID_SPARE;
 227         else
 228                 buf[6] |= AX25_ESSID_SPARE;
 229
 230         if (flag == AX25_RESPONSE) buf[6] |= AX25_CBIT;
 231
 232         /*
 233          *      Fast path the normal digiless path
 234          */
 235         if (d == NULL || d->ndigi == 0) {
 236                 buf[6] |= AX25_EBIT;
 237                 return 2 * AX25_ADDR_LEN;
 238         }
 239
 240         buf += AX25_ADDR_LEN;
 241         len += AX25_ADDR_LEN;
 242
 243         while (ct < d->ndigi) {
 244                 memcpy(buf, &d->calls[ct], AX25_ADDR_LEN);
 245
 246                 if (d->repeated[ct])
 247                         buf[6] |= AX25_HBIT;
 248                 else
 249                         buf[6] &= ~AX25_HBIT;
 250
 251                 buf[6] &= ~AX25_EBIT;
 252                 buf[6] |= AX25_SSSID_SPARE;
 253
 254                 buf += AX25_ADDR_LEN;
 255                 len += AX25_ADDR_LEN;
 256                 ct++;
 257         }
 258
 259         buf[-1] |= AX25_EBIT;
 260
 261         return len;
 262 }
 263
 264 int ax25_addr_size(ax25_digi *dp)
 265 {
 266         if (dp == NULL)
 267                 return 2 * AX25_ADDR_LEN;
 268
 269         return AX25_ADDR_LEN * (2 + dp->ndigi);
 270 }
 271
 272 /*
 273  *      Reverse Digipeat List. May not pass both parameters as same struct
 274  */
 275 void ax25_digi_invert(ax25_digi *in, ax25_digi *out)
 276 {
 277         int ct;
 278
 279         out->ndigi      = in->ndigi;
 280         out->lastrepeat = in->ndigi - in->lastrepeat - 2;
 281
 282         /* Invert the digipeaters */
 283         for (ct = 0; ct < in->ndigi; ct++) {
 284                 out->calls[ct] = in->calls[in->ndigi - ct - 1];
 285
 286                 if (ct <= out->lastrepeat) {
 287                         out->calls[ct].ax25_call[6] |= AX25_HBIT;
 288                         out->repeated[ct]            = 1;
 289                 } else {
 290                         out->calls[ct].ax25_call[6] &= ~AX25_HBIT;
 291                         out->repeated[ct]            = 0;
 292                 }
 293         }
 294 }
 295