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/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 <linux/fcntl.h>
26#include <linux/mm.h>
27#include <linux/interrupt.h>
28
29/*
30 * The default broadcast address of an interface is QST-0; the default address
31 * is LINUX-1.  The null address is defined as a callsign of all spaces with
32 * an SSID of zero.
33 */
34
35const ax25_address ax25_bcast =
36	{{'Q' << 1, 'S' << 1, 'T' << 1, ' ' << 1, ' ' << 1, ' ' << 1, 0 << 1}};
37const ax25_address ax25_defaddr =
38	{{'L' << 1, 'I' << 1, 'N' << 1, 'U' << 1, 'X' << 1, ' ' << 1, 1 << 1}};
39const ax25_address null_ax25_address =
40	{{' ' << 1, ' ' << 1, ' ' << 1, ' ' << 1, ' ' << 1, ' ' << 1, 0 << 1}};
41
42EXPORT_SYMBOL_GPL(ax25_bcast);
43EXPORT_SYMBOL_GPL(ax25_defaddr);
44EXPORT_SYMBOL(null_ax25_address);
45
46/*
47 *	ax25 -> ascii conversion
48 */
49char *ax2asc(char *buf, const ax25_address *a)
50{
51	char c, *s;
52	int n;
53
54	for (n = 0, s = buf; n < 6; n++) {
55		c = (a->ax25_call[n] >> 1) & 0x7F;
56
57		if (c != ' ') *s++ = c;
58	}
59
60	*s++ = '-';
61
62	if ((n = ((a->ax25_call[6] >> 1) & 0x0F)) > 9) {
63		*s++ = '1';
64		n -= 10;
65	}
66
67	*s++ = n + '0';
68	*s++ = '\0';
69
70	if (*buf == '\0' || *buf == '-')
71	   return "*";
72
73	return buf;
74
75}
76
77EXPORT_SYMBOL(ax2asc);
78
79/*
80 *	ascii -> ax25 conversion
81 */
82void asc2ax(ax25_address *addr, const char *callsign)
83{
84	const char *s;
85	int n;
86
87	for (s = callsign, n = 0; n < 6; n++) {
88		if (*s != '\0' && *s != '-')
89			addr->ax25_call[n] = *s++;
90		else
91			addr->ax25_call[n] = ' ';
92		addr->ax25_call[n] <<= 1;
93		addr->ax25_call[n] &= 0xFE;
94	}
95
96	if (*s++ == '\0') {
97		addr->ax25_call[6] = 0x00;
98		return;
99	}
100
101	addr->ax25_call[6] = *s++ - '0';
102
103	if (*s != '\0') {
104		addr->ax25_call[6] *= 10;
105		addr->ax25_call[6] += *s++ - '0';
106	}
107
108	addr->ax25_call[6] <<= 1;
109	addr->ax25_call[6] &= 0x1E;
110}
111
112EXPORT_SYMBOL(asc2ax);
113
114/*
115 *	Compare two ax.25 addresses
116 */
117int ax25cmp(const ax25_address *a, const ax25_address *b)
118{
119	int ct = 0;
120
121	while (ct < 6) {
122		if ((a->ax25_call[ct] & 0xFE) != (b->ax25_call[ct] & 0xFE))	/* Clean off repeater bits */
123			return 1;
124		ct++;
125	}
126
127	if ((a->ax25_call[ct] & 0x1E) == (b->ax25_call[ct] & 0x1E))	/* SSID without control bit */
128		return 0;
129
130	return 2;			/* Partial match */
131}
132
133EXPORT_SYMBOL(ax25cmp);
134
135/*
136 *	Compare two AX.25 digipeater paths.
137 */
138int ax25digicmp(const ax25_digi *digi1, const ax25_digi *digi2)
139{
140	int i;
141
142	if (digi1->ndigi != digi2->ndigi)
143		return 1;
144
145	if (digi1->lastrepeat != digi2->lastrepeat)
146		return 1;
147
148	for (i = 0; i < digi1->ndigi; i++)
149		if (ax25cmp(&digi1->calls[i], &digi2->calls[i]) != 0)
150			return 1;
151
152	return 0;
153}
154
155/*
156 *	Given an AX.25 address pull of to, from, digi list, command/response and the start of data
157 *
158 */
159const unsigned char *ax25_addr_parse(const unsigned char *buf, int len,
160	ax25_address *src, ax25_address *dest, ax25_digi *digi, int *flags,
161	int *dama)
162{
163	int d = 0;
164
165	if (len < 14) return NULL;
166
167	if (flags != NULL) {
168		*flags = 0;
169
170		if (buf[6] & AX25_CBIT)
171			*flags = AX25_COMMAND;
172		if (buf[13] & AX25_CBIT)
173			*flags = AX25_RESPONSE;
174	}
175
176	if (dama != NULL)
177		*dama = ~buf[13] & AX25_DAMA_FLAG;
178
179	/* Copy to, from */
180	if (dest != NULL)
181		memcpy(dest, buf + 0, AX25_ADDR_LEN);
182	if (src != NULL)
183		memcpy(src,  buf + 7, AX25_ADDR_LEN);
184
185	buf += 2 * AX25_ADDR_LEN;
186	len -= 2 * AX25_ADDR_LEN;
187
188	digi->lastrepeat = -1;
189	digi->ndigi      = 0;
190
191	while (!(buf[-1] & AX25_EBIT)) {
192		if (d >= AX25_MAX_DIGIS)
193			return NULL;
194		if (len < AX25_ADDR_LEN)
195			return NULL;
196
197		memcpy(&digi->calls[d], buf, AX25_ADDR_LEN);
198		digi->ndigi = d + 1;
199
200		if (buf[6] & AX25_HBIT) {
201			digi->repeated[d] = 1;
202			digi->lastrepeat  = d;
203		} else {
204			digi->repeated[d] = 0;
205		}
206
207		buf += AX25_ADDR_LEN;
208		len -= AX25_ADDR_LEN;
209		d++;
210	}
211
212	return buf;
213}
214
215/*
216 *	Assemble an AX.25 header from the bits
217 */
218int ax25_addr_build(unsigned char *buf, const ax25_address *src,
219	const ax25_address *dest, const ax25_digi *d, int flag, int modulus)
220{
221	int len = 0;
222	int ct  = 0;
223
224	memcpy(buf, dest, AX25_ADDR_LEN);
225	buf[6] &= ~(AX25_EBIT | AX25_CBIT);
226	buf[6] |= AX25_SSSID_SPARE;
227
228	if (flag == AX25_COMMAND) buf[6] |= AX25_CBIT;
229
230	buf += AX25_ADDR_LEN;
231	len += AX25_ADDR_LEN;
232
233	memcpy(buf, src, AX25_ADDR_LEN);
234	buf[6] &= ~(AX25_EBIT | AX25_CBIT);
235	buf[6] &= ~AX25_SSSID_SPARE;
236
237	if (modulus == AX25_MODULUS)
238		buf[6] |= AX25_SSSID_SPARE;
239	else
240		buf[6] |= AX25_ESSID_SPARE;
241
242	if (flag == AX25_RESPONSE) buf[6] |= AX25_CBIT;
243
244	/*
245	 *	Fast path the normal digiless path
246	 */
247	if (d == NULL || d->ndigi == 0) {
248		buf[6] |= AX25_EBIT;
249		return 2 * AX25_ADDR_LEN;
250	}
251
252	buf += AX25_ADDR_LEN;
253	len += AX25_ADDR_LEN;
254
255	while (ct < d->ndigi) {
256		memcpy(buf, &d->calls[ct], AX25_ADDR_LEN);
257
258		if (d->repeated[ct])
259			buf[6] |= AX25_HBIT;
260		else
261			buf[6] &= ~AX25_HBIT;
262
263		buf[6] &= ~AX25_EBIT;
264		buf[6] |= AX25_SSSID_SPARE;
265
266		buf += AX25_ADDR_LEN;
267		len += AX25_ADDR_LEN;
268		ct++;
269	}
270
271	buf[-1] |= AX25_EBIT;
272
273	return len;
274}
275
276int ax25_addr_size(const ax25_digi *dp)
277{
278	if (dp == NULL)
279		return 2 * AX25_ADDR_LEN;
280
281	return AX25_ADDR_LEN * (2 + dp->ndigi);
282}
283
284/*
285 *	Reverse Digipeat List. May not pass both parameters as same struct
286 */
287void ax25_digi_invert(const ax25_digi *in, ax25_digi *out)
288{
289	int ct;
290
291	out->ndigi      = in->ndigi;
292	out->lastrepeat = in->ndigi - in->lastrepeat - 2;
293
294	/* Invert the digipeaters */
295	for (ct = 0; ct < in->ndigi; ct++) {
296		out->calls[ct] = in->calls[in->ndigi - ct - 1];
297
298		if (ct <= out->lastrepeat) {
299			out->calls[ct].ax25_call[6] |= AX25_HBIT;
300			out->repeated[ct]            = 1;
301		} else {
302			out->calls[ct].ax25_call[6] &= ~AX25_HBIT;
303			out->repeated[ct]            = 0;
304		}
305	}
306}
307
308