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(ax25_address *a)
  40 {
  41         static char buf[11];
  42         char c, *s;
  43         int n;
  44
  45         for (n = 0, s = buf; n < 6; n++) {
  46                 c = (a->ax25_call[n] >> 1) & 0x7F;
  47
  48                 if (c != ' ') *s++ = c;
  49         }
  50
  51         *s++ = '-';
  52
  53         if ((n = ((a->ax25_call[6] >> 1) & 0x0F)) > 9) {
  54                 *s++ = '1';
  55                 n -= 10;
  56         }
  57
  58         *s++ = n + '0';
  59         *s++ = '\0';
  60
  61         if (*buf == '\0' || *buf == '-')
  62            return "*";
  63
  64         return buf;
  65
  66 }
  67
  68 /*
  69  *      ascii -> ax25 conversion
  70  */
  71 ax25_address *asc2ax(char *callsign)
  72 {
  73         static ax25_address addr;
  74         char *s;
  75         int n;
  76
  77         for (s = callsign, n = 0; n < 6; n++) {
  78                 if (*s != '\0' && *s != '-')
  79                         addr.ax25_call[n] = *s++;
  80                 else
  81                         addr.ax25_call[n] = ' ';
  82                 addr.ax25_call[n] <<= 1;
  83                 addr.ax25_call[n] &= 0xFE;
  84         }
  85
  86         if (*s++ == '\0') {
  87                 addr.ax25_call[6] = 0x00;
  88                 return &addr;
  89         }
  90
  91         addr.ax25_call[6] = *s++ - '0';
  92
  93         if (*s != '\0') {
  94                 addr.ax25_call[6] *= 10;
  95                 addr.ax25_call[6] += *s++ - '0';
  96         }
  97
  98         addr.ax25_call[6] <<= 1;
  99         addr.ax25_call[6] &= 0x1E;
 100
 101         return &addr;
 102 }
 103
 104 /*
 105  *      Compare two ax.25 addresses
 106  */
 107 int ax25cmp(ax25_address *a, ax25_address *b)
 108 {
 109         int ct = 0;
 110
 111         while (ct < 6) {
 112                 if ((a->ax25_call[ct] & 0xFE) != (b->ax25_call[ct] & 0xFE))     /* Clean off repeater bits */
 113                         return 1;
 114                 ct++;
 115         }
 116
 117         if ((a->ax25_call[ct] & 0x1E) == (b->ax25_call[ct] & 0x1E))     /* SSID without control bit */
 118                 return 0;
 119
 120         return 2;                       /* Partial match */
 121 }
 122
 123 /*
 124  *      Compare two AX.25 digipeater paths.
 125  */
 126 int ax25digicmp(ax25_digi *digi1, ax25_digi *digi2)
 127 {
 128         int i;
 129
 130         if (digi1->ndigi != digi2->ndigi)
 131                 return 1;
 132
 133         if (digi1->lastrepeat != digi2->lastrepeat)
 134                 return 1;
 135
 136         for (i = 0; i < digi1->ndigi; i++)
 137                 if (ax25cmp(&digi1->calls[i], &digi2->calls[i]) != 0)
 138                         return 1;
 139
 140         return 0;
 141 }
 142
 143 /*
 144  *      Given an AX.25 address pull of to, from, digi list, command/response and the start of data
 145  *
 146  */
 147 unsigned char *ax25_addr_parse(unsigned char *buf, int len, ax25_address *src, ax25_address *dest, ax25_digi *digi, int *flags, int *dama)
 148 {
 149         int d = 0;
 150
 151         if (len < 14) return NULL;
 152
 153         if (flags != NULL) {
 154                 *flags = 0;
 155
 156                 if (buf[6] & AX25_CBIT)
 157                         *flags = AX25_COMMAND;
 158                 if (buf[13] & AX25_CBIT)
 159                         *flags = AX25_RESPONSE;
 160         }
 161
 162         if (dama != NULL)
 163                 *dama = ~buf[13] & AX25_DAMA_FLAG;
 164
 165         /* Copy to, from */
 166         if (dest != NULL)
 167                 memcpy(dest, buf + 0, AX25_ADDR_LEN);
 168         if (src != NULL)
 169                 memcpy(src,  buf + 7, AX25_ADDR_LEN);
 170
 171         buf += 2 * AX25_ADDR_LEN;
 172         len -= 2 * AX25_ADDR_LEN;
 173
 174         digi->lastrepeat = -1;
 175         digi->ndigi      = 0;
 176
 177         while (!(buf[-1] & AX25_EBIT)) {
 178                 if (d >= AX25_MAX_DIGIS)  return NULL;  /* Max of 6 digis */
 179                 if (len < 7) return NULL;       /* Short packet */
 180
 181                 memcpy(&digi->calls[d], buf, AX25_ADDR_LEN);
 182                 digi->ndigi = d + 1;
 183
 184                 if (buf[6] & AX25_HBIT) {
 185                         digi->repeated[d] = 1;
 186                         digi->lastrepeat  = d;
 187                 } else {
 188                         digi->repeated[d] = 0;
 189                 }
 190
 191                 buf += AX25_ADDR_LEN;
 192                 len -= AX25_ADDR_LEN;
 193                 d++;
 194         }
 195
 196         return buf;
 197 }
 198
 199 /*
 200  *      Assemble an AX.25 header from the bits
 201  */
 202 int ax25_addr_build(unsigned char *buf, ax25_address *src, ax25_address *dest, ax25_digi *d, int flag, int modulus)
 203 {
 204         int len = 0;
 205         int ct  = 0;
 206
 207         memcpy(buf, dest, AX25_ADDR_LEN);
 208         buf[6] &= ~(AX25_EBIT | AX25_CBIT);
 209         buf[6] |= AX25_SSSID_SPARE;
 210
 211         if (flag == AX25_COMMAND) buf[6] |= AX25_CBIT;
 212
 213         buf += AX25_ADDR_LEN;
 214         len += AX25_ADDR_LEN;
 215
 216         memcpy(buf, src, AX25_ADDR_LEN);
 217         buf[6] &= ~(AX25_EBIT | AX25_CBIT);
 218         buf[6] &= ~AX25_SSSID_SPARE;
 219
 220         if (modulus == AX25_MODULUS)
 221                 buf[6] |= AX25_SSSID_SPARE;
 222         else
 223                 buf[6] |= AX25_ESSID_SPARE;
 224
 225         if (flag == AX25_RESPONSE) buf[6] |= AX25_CBIT;
 226
 227         /*
 228          *      Fast path the normal digiless path
 229          */
 230         if (d == NULL || d->ndigi == 0) {
 231                 buf[6] |= AX25_EBIT;
 232                 return 2 * AX25_ADDR_LEN;
 233         }
 234
 235         buf += AX25_ADDR_LEN;
 236         len += AX25_ADDR_LEN;
 237
 238         while (ct < d->ndigi) {
 239                 memcpy(buf, &d->calls[ct], AX25_ADDR_LEN);
 240
 241                 if (d->repeated[ct])
 242                         buf[6] |= AX25_HBIT;
 243                 else
 244                         buf[6] &= ~AX25_HBIT;
 245
 246                 buf[6] &= ~AX25_EBIT;
 247                 buf[6] |= AX25_SSSID_SPARE;
 248
 249                 buf += AX25_ADDR_LEN;
 250                 len += AX25_ADDR_LEN;
 251                 ct++;
 252         }
 253
 254         buf[-1] |= AX25_EBIT;
 255
 256         return len;
 257 }
 258
 259 int ax25_addr_size(ax25_digi *dp)
 260 {
 261         if (dp == NULL)
 262                 return 2 * AX25_ADDR_LEN;
 263
 264         return AX25_ADDR_LEN * (2 + dp->ndigi);
 265 }
 266
 267 /*
 268  *      Reverse Digipeat List. May not pass both parameters as same struct
 269  */
 270 void ax25_digi_invert(ax25_digi *in, ax25_digi *out)
 271 {
 272         int ct;
 273
 274         out->ndigi      = in->ndigi;
 275         out->lastrepeat = in->ndigi - in->lastrepeat - 2;
 276
 277         /* Invert the digipeaters */
 278         for (ct = 0; ct < in->ndigi; ct++) {
 279                 out->calls[ct] = in->calls[in->ndigi - ct - 1];
 280
 281                 if (ct <= out->lastrepeat) {
 282                         out->calls[ct].ax25_call[6] |= AX25_HBIT;
 283                         out->repeated[ct]            = 1;
 284                 } else {
 285                         out->calls[ct].ax25_call[6] &= ~AX25_HBIT;
 286                         out->repeated[ct]            = 0;
 287                 }
 288         }
 289 }
 290