xref: /openbmc/linux/net/ax25/ax25_addr.c (revision 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2) 
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 
291