1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 *
4 * Copyright (C) Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk)
5 */
6 #include <linux/errno.h>
7 #include <linux/types.h>
8 #include <linux/socket.h>
9 #include <linux/in.h>
10 #include <linux/kernel.h>
11 #include <linux/module.h>
12 #include <linux/timer.h>
13 #include <linux/string.h>
14 #include <linux/sockios.h>
15 #include <linux/net.h>
16 #include <net/ax25.h>
17 #include <linux/inet.h>
18 #include <linux/netdevice.h>
19 #include <linux/skbuff.h>
20 #include <net/sock.h>
21 #include <linux/uaccess.h>
22 #include <linux/fcntl.h>
23 #include <linux/mm.h>
24 #include <linux/interrupt.h>
25
26 /*
27 * The default broadcast address of an interface is QST-0; the default address
28 * is LINUX-1. The null address is defined as a callsign of all spaces with
29 * an SSID of zero.
30 */
31
32 const ax25_address ax25_bcast =
33 {{'Q' << 1, 'S' << 1, 'T' << 1, ' ' << 1, ' ' << 1, ' ' << 1, 0 << 1}};
34 const ax25_address ax25_defaddr =
35 {{'L' << 1, 'I' << 1, 'N' << 1, 'U' << 1, 'X' << 1, ' ' << 1, 1 << 1}};
36 const ax25_address null_ax25_address =
37 {{' ' << 1, ' ' << 1, ' ' << 1, ' ' << 1, ' ' << 1, ' ' << 1, 0 << 1}};
38
39 EXPORT_SYMBOL_GPL(ax25_bcast);
40 EXPORT_SYMBOL_GPL(ax25_defaddr);
41 EXPORT_SYMBOL(null_ax25_address);
42
43 /*
44 * ax25 -> ascii conversion
45 */
46 char *ax2asc(char *buf, const ax25_address *a)
47 {
48 char c, *s;
49 int n;
50
51 for (n = 0, s = buf; n < 6; n++) {
52 c = (a->ax25_call[n] >> 1) & 0x7F;
53
54 if (c != ' ') *s++ = c;
55 }
56
57 *s++ = '-';
58
59 if ((n = ((a->ax25_call[6] >> 1) & 0x0F)) > 9) {
60 *s++ = '1';
61 n -= 10;
62 }
63
64 *s++ = n + '';
65 *s++ = '\0';
66
67 if (*buf == '\0' || *buf == '-')
68 return "*";
69
70 return buf;
71
72 }
73
74 EXPORT_SYMBOL(ax2asc);
75
76 /*
77 * ascii -> ax25 conversion
78 */
79 void asc2ax(ax25_address *addr, const char *callsign)
80 {
81 const char *s;
82 int n;
83
84 for (s = callsign, n = 0; n < 6; n++) {
85 if (*s != '\0' && *s != '-')
86 addr->ax25_call[n] = *s++;
87 else
88 addr->ax25_call[n] = ' ';
89 addr->ax25_call[n] <<= 1;
90 addr->ax25_call[n] &= 0xFE;
91 }
92
93 if (*s++ == '\0') {
94 addr->ax25_call[6] = 0x00;
95 return;
96 }
97
98 addr->ax25_call[6] = *s++ - '';
99
100 if (*s != '\0') {
101 addr->ax25_call[6] *= 10;
102 addr->ax25_call[6] += *s++ - '';
103 }
104
105 addr->ax25_call[6] <<= 1;
106 addr->ax25_call[6] &= 0x1E;
107 }
108
109 EXPORT_SYMBOL(asc2ax);
110
111 /*
112 * Compare two ax.25 addresses
113 */
114 int ax25cmp(const ax25_address *a, const ax25_address *b)
115 {
116 int ct = 0;
117
118 while (ct < 6) {
119 if ((a->ax25_call[ct] & 0xFE) != (b->ax25_call[ct] & 0xFE)) /* Clean off repeater bits */
120 return 1;
121 ct++;
122 }
123
124 if ((a->ax25_call[ct] & 0x1E) == (b->ax25_call[ct] & 0x1E)) /* SSID without control bit */
125 return 0;
126
127 return 2; /* Partial match */
128 }
129
130 EXPORT_SYMBOL(ax25cmp);
131
132 /*
133 * Compare two AX.25 digipeater paths.
134 */
135 int ax25digicmp(const ax25_digi *digi1, const ax25_digi *digi2)
136 {
137 int i;
138
139 if (digi1->ndigi != digi2->ndigi)
140 return 1;
141
142 if (digi1->lastrepeat != digi2->lastrepeat)
143 return 1;
144
145 for (i = 0; i < digi1->ndigi; i++)
146 if (ax25cmp(&digi1->calls[i], &digi2->calls[i]) != 0)
147 return 1;
148
149 return 0;
150 }
151
152 /*
153 * Given an AX.25 address pull of to, from, digi list, command/response and the start of data
154 *
155 */
156 const unsigned char *ax25_addr_parse(const unsigned char *buf, int len,
157 ax25_address *src, ax25_address *dest, ax25_digi *digi, int *flags,
158 int *dama)
159 {
160 int d = 0;
161
162 if (len < 14) return NULL;
163
164 if (flags != NULL) {
165 *flags = 0;
166
167 if (buf[6] & AX25_CBIT)
168 *flags = AX25_COMMAND;
169 if (buf[13] & AX25_CBIT)
170 *flags = AX25_RESPONSE;
171 }
172
173 if (dama != NULL)
174 *dama = ~buf[13] & AX25_DAMA_FLAG;
175
176 /* Copy to, from */
177 if (dest != NULL)
178 memcpy(dest, buf + 0, AX25_ADDR_LEN);
179 if (src != NULL)
180 memcpy(src, buf + 7, AX25_ADDR_LEN);
181
182 buf += 2 * AX25_ADDR_LEN;
183 len -= 2 * AX25_ADDR_LEN;
184
185 digi->lastrepeat = -1;
186 digi->ndigi = 0;
187
188 while (!(buf[-1] & AX25_EBIT)) {
189 if (d >= AX25_MAX_DIGIS)
190 return NULL;
191 if (len < AX25_ADDR_LEN)
192 return NULL;
193
194 memcpy(&digi->calls[d], buf, AX25_ADDR_LEN);
195 digi->ndigi = d + 1;
196
197 if (buf[6] & AX25_HBIT) {
198 digi->repeated[d] = 1;
199 digi->lastrepeat = d;
200 } else {
201 digi->repeated[d] = 0;
202 }
203
204 buf += AX25_ADDR_LEN;
205 len -= AX25_ADDR_LEN;
206 d++;
207 }
208
209 return buf;
210 }
211
212 /*
213 * Assemble an AX.25 header from the bits
214 */
215 int ax25_addr_build(unsigned char *buf, const ax25_address *src,
216 const ax25_address *dest, const ax25_digi *d, int flag, int modulus)
217 {
218 int len = 0;
219 int ct = 0;
220
221 memcpy(buf, dest, AX25_ADDR_LEN);
222 buf[6] &= ~(AX25_EBIT | AX25_CBIT);
223 buf[6] |= AX25_SSSID_SPARE;
224
225 if (flag == AX25_COMMAND) buf[6] |= AX25_CBIT;
226
227 buf += AX25_ADDR_LEN;
228 len += AX25_ADDR_LEN;
229
230 memcpy(buf, src, AX25_ADDR_LEN);
231 buf[6] &= ~(AX25_EBIT | AX25_CBIT);
232 buf[6] &= ~AX25_SSSID_SPARE;
233
234 if (modulus == AX25_MODULUS)
235 buf[6] |= AX25_SSSID_SPARE;
236 else
237 buf[6] |= AX25_ESSID_SPARE;
238
239 if (flag == AX25_RESPONSE) buf[6] |= AX25_CBIT;
240
241 /*
242 * Fast path the normal digiless path
243 */
244 if (d == NULL || d->ndigi == 0) {
245 buf[6] |= AX25_EBIT;
246 return 2 * AX25_ADDR_LEN;
247 }
248
249 buf += AX25_ADDR_LEN;
250 len += AX25_ADDR_LEN;
251
252 while (ct < d->ndigi) {
253 memcpy(buf, &d->calls[ct], AX25_ADDR_LEN);
254
255 if (d->repeated[ct])
256 buf[6] |= AX25_HBIT;
257 else
258 buf[6] &= ~AX25_HBIT;
259
260 buf[6] &= ~AX25_EBIT;
261 buf[6] |= AX25_SSSID_SPARE;
262
263 buf += AX25_ADDR_LEN;
264 len += AX25_ADDR_LEN;
265 ct++;
266 }
267
268 buf[-1] |= AX25_EBIT;
269
270 return len;
271 }
272
273 int ax25_addr_size(const ax25_digi *dp)
274 {
275 if (dp == NULL)
276 return 2 * AX25_ADDR_LEN;
277
278 return AX25_ADDR_LEN * (2 + dp->ndigi);
279 }
280
281 /*
282 * Reverse Digipeat List. May not pass both parameters as same struct
283 */
284 void ax25_digi_invert(const ax25_digi *in, ax25_digi *out)
285 {
286 int ct;
287
288 out->ndigi = in->ndigi;
289 out->lastrepeat = in->ndigi - in->lastrepeat - 2;
290
291 /* Invert the digipeaters */
292 for (ct = 0; ct < in->ndigi; ct++) {
293 out->calls[ct] = in->calls[in->ndigi - ct - 1];
294
295 if (ct <= out->lastrepeat) {
296 out->calls[ct].ax25_call[6] |= AX25_HBIT;
297 out->repeated[ct] = 1;
298 } else {
299 out->calls[ct].ax25_call[6] &= ~AX25_HBIT;
300 out->repeated[ct] = 0;
301 }
302 }
303 }
304
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