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
32const ax25_address ax25_bcast =
33	{{'Q' << 1, 'S' << 1, 'T' << 1, ' ' << 1, ' ' << 1, ' ' << 1, 0 << 1}};
34const ax25_address ax25_defaddr =
35	{{'L' << 1, 'I' << 1, 'N' << 1, 'U' << 1, 'X' << 1, ' ' << 1, 1 << 1}};
36const ax25_address null_ax25_address =
37	{{' ' << 1, ' ' << 1, ' ' << 1, ' ' << 1, ' ' << 1, ' ' << 1, 0 << 1}};
38
39EXPORT_SYMBOL_GPL(ax25_bcast);
40EXPORT_SYMBOL_GPL(ax25_defaddr);
41EXPORT_SYMBOL(null_ax25_address);
42
43/*
44 *	ax25 -> ascii conversion
45 */
46char *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 + '0';
65	*s++ = '\0';
66
67	if (*buf == '\0' || *buf == '-')
68	   return "*";
69
70	return buf;
71
72}
73
74EXPORT_SYMBOL(ax2asc);
75
76/*
77 *	ascii -> ax25 conversion
78 */
79void 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++ - '0';
99
100	if (*s != '\0') {
101		addr->ax25_call[6] *= 10;
102		addr->ax25_call[6] += *s++ - '0';
103	}
104
105	addr->ax25_call[6] <<= 1;
106	addr->ax25_call[6] &= 0x1E;
107}
108
109EXPORT_SYMBOL(asc2ax);
110
111/*
112 *	Compare two ax.25 addresses
113 */
114int 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
130EXPORT_SYMBOL(ax25cmp);
131
132/*
133 *	Compare two AX.25 digipeater paths.
134 */
135int 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 */
156const 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 */
215int 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
273int 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 */
284void 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