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