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