xref: /openbmc/linux/net/ax25/ax25_addr.c (revision f75268cd) 
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(char *buf, ax25_address *a)
40 {
41 	char c, *s;
42 	int n;
43 
44 	for (n = 0, s = buf; n < 6; n++) {
45 		c = (a->ax25_call[n] >> 1) & 0x7F;
46 
47 		if (c != ' ') *s++ = c;
48 	}
49 
50 	*s++ = '-';
51 
52 	if ((n = ((a->ax25_call[6] >> 1) & 0x0F)) > 9) {
53 		*s++ = '1';
54 		n -= 10;
55 	}
56 
57 	*s++ = n + '0';
58 	*s++ = '\0';
59 
60 	if (*buf == '\0' || *buf == '-')
61 	   return "*";
62 
63 	return buf;
64 
65 }
66 
67 /*
68  *	ascii -> ax25 conversion
69  */
70 ax25_address *asc2ax(char *callsign)
71 {
72 	static ax25_address addr;
73 	char *s;
74 	int n;
75 
76 	for (s = callsign, n = 0; n < 6; n++) {
77 		if (*s != '\0' && *s != '-')
78 			addr.ax25_call[n] = *s++;
79 		else
80 			addr.ax25_call[n] = ' ';
81 		addr.ax25_call[n] <<= 1;
82 		addr.ax25_call[n] &= 0xFE;
83 	}
84 
85 	if (*s++ == '\0') {
86 		addr.ax25_call[6] = 0x00;
87 		return &addr;
88 	}
89 
90 	addr.ax25_call[6] = *s++ - '0';
91 
92 	if (*s != '\0') {
93 		addr.ax25_call[6] *= 10;
94 		addr.ax25_call[6] += *s++ - '0';
95 	}
96 
97 	addr.ax25_call[6] <<= 1;
98 	addr.ax25_call[6] &= 0x1E;
99 
100 	return &addr;
101 }
102 
103 /*
104  *	Compare two ax.25 addresses
105  */
106 int ax25cmp(ax25_address *a, ax25_address *b)
107 {
108 	int ct = 0;
109 
110 	while (ct < 6) {
111 		if ((a->ax25_call[ct] & 0xFE) != (b->ax25_call[ct] & 0xFE))	/* Clean off repeater bits */
112 			return 1;
113 		ct++;
114 	}
115 
116  	if ((a->ax25_call[ct] & 0x1E) == (b->ax25_call[ct] & 0x1E))	/* SSID without control bit */
117  		return 0;
118 
119  	return 2;			/* Partial match */
120 }
121 
122 /*
123  *	Compare two AX.25 digipeater paths.
124  */
125 int ax25digicmp(ax25_digi *digi1, ax25_digi *digi2)
126 {
127 	int i;
128 
129 	if (digi1->ndigi != digi2->ndigi)
130 		return 1;
131 
132 	if (digi1->lastrepeat != digi2->lastrepeat)
133 		return 1;
134 
135 	for (i = 0; i < digi1->ndigi; i++)
136 		if (ax25cmp(&digi1->calls[i], &digi2->calls[i]) != 0)
137 			return 1;
138 
139 	return 0;
140 }
141 
142 /*
143  *	Given an AX.25 address pull of to, from, digi list, command/response and the start of data
144  *
145  */
146 unsigned char *ax25_addr_parse(unsigned char *buf, int len, ax25_address *src, ax25_address *dest, ax25_digi *digi, int *flags, int *dama)
147 {
148 	int d = 0;
149 
150 	if (len < 14) return NULL;
151 
152 	if (flags != NULL) {
153 		*flags = 0;
154 
155 		if (buf[6] & AX25_CBIT)
156 			*flags = AX25_COMMAND;
157 		if (buf[13] & AX25_CBIT)
158 			*flags = AX25_RESPONSE;
159 	}
160 
161 	if (dama != NULL)
162 		*dama = ~buf[13] & AX25_DAMA_FLAG;
163 
164 	/* Copy to, from */
165 	if (dest != NULL)
166 		memcpy(dest, buf + 0, AX25_ADDR_LEN);
167 	if (src != NULL)
168 		memcpy(src,  buf + 7, AX25_ADDR_LEN);
169 
170 	buf += 2 * AX25_ADDR_LEN;
171 	len -= 2 * AX25_ADDR_LEN;
172 
173 	digi->lastrepeat = -1;
174 	digi->ndigi      = 0;
175 
176 	while (!(buf[-1] & AX25_EBIT)) {
177 		if (d >= AX25_MAX_DIGIS)  return NULL;	/* Max of 6 digis */
178 		if (len < 7) return NULL;	/* Short packet */
179 
180 		memcpy(&digi->calls[d], buf, AX25_ADDR_LEN);
181 		digi->ndigi = d + 1;
182 
183 		if (buf[6] & AX25_HBIT) {
184 			digi->repeated[d] = 1;
185 			digi->lastrepeat  = d;
186 		} else {
187 			digi->repeated[d] = 0;
188 		}
189 
190 		buf += AX25_ADDR_LEN;
191 		len -= AX25_ADDR_LEN;
192 		d++;
193 	}
194 
195 	return buf;
196 }
197 
198 /*
199  *	Assemble an AX.25 header from the bits
200  */
201 int ax25_addr_build(unsigned char *buf, ax25_address *src, ax25_address *dest, ax25_digi *d, int flag, int modulus)
202 {
203 	int len = 0;
204 	int ct  = 0;
205 
206 	memcpy(buf, dest, AX25_ADDR_LEN);
207 	buf[6] &= ~(AX25_EBIT | AX25_CBIT);
208 	buf[6] |= AX25_SSSID_SPARE;
209 
210 	if (flag == AX25_COMMAND) buf[6] |= AX25_CBIT;
211 
212 	buf += AX25_ADDR_LEN;
213 	len += AX25_ADDR_LEN;
214 
215 	memcpy(buf, src, AX25_ADDR_LEN);
216 	buf[6] &= ~(AX25_EBIT | AX25_CBIT);
217 	buf[6] &= ~AX25_SSSID_SPARE;
218 
219 	if (modulus == AX25_MODULUS)
220 		buf[6] |= AX25_SSSID_SPARE;
221 	else
222 		buf[6] |= AX25_ESSID_SPARE;
223 
224 	if (flag == AX25_RESPONSE) buf[6] |= AX25_CBIT;
225 
226 	/*
227 	 *	Fast path the normal digiless path
228 	 */
229 	if (d == NULL || d->ndigi == 0) {
230 		buf[6] |= AX25_EBIT;
231 		return 2 * AX25_ADDR_LEN;
232 	}
233 
234 	buf += AX25_ADDR_LEN;
235 	len += AX25_ADDR_LEN;
236 
237 	while (ct < d->ndigi) {
238 		memcpy(buf, &d->calls[ct], AX25_ADDR_LEN);
239 
240 		if (d->repeated[ct])
241 			buf[6] |= AX25_HBIT;
242 		else
243 			buf[6] &= ~AX25_HBIT;
244 
245 		buf[6] &= ~AX25_EBIT;
246 		buf[6] |= AX25_SSSID_SPARE;
247 
248 		buf += AX25_ADDR_LEN;
249 		len += AX25_ADDR_LEN;
250 		ct++;
251 	}
252 
253 	buf[-1] |= AX25_EBIT;
254 
255 	return len;
256 }
257 
258 int ax25_addr_size(ax25_digi *dp)
259 {
260 	if (dp == NULL)
261 		return 2 * AX25_ADDR_LEN;
262 
263 	return AX25_ADDR_LEN * (2 + dp->ndigi);
264 }
265 
266 /*
267  *	Reverse Digipeat List. May not pass both parameters as same struct
268  */
269 void ax25_digi_invert(ax25_digi *in, ax25_digi *out)
270 {
271 	int ct;
272 
273 	out->ndigi      = in->ndigi;
274 	out->lastrepeat = in->ndigi - in->lastrepeat - 2;
275 
276 	/* Invert the digipeaters */
277 	for (ct = 0; ct < in->ndigi; ct++) {
278 		out->calls[ct] = in->calls[in->ndigi - ct - 1];
279 
280 		if (ct <= out->lastrepeat) {
281 			out->calls[ct].ax25_call[6] |= AX25_HBIT;
282 			out->repeated[ct]            = 1;
283 		} else {
284 			out->calls[ct].ax25_call[6] &= ~AX25_HBIT;
285 			out->repeated[ct]            = 0;
286 		}
287 	}
288 }
289 
290