1 /*-------------------------------------------------------------------
2 *
3 * Name: ax25_pad.h
4 *
5 * Purpose: Header file for using ax25_pad.c
6 *
7 *------------------------------------------------------------------*/
8
9 #ifndef AX25_PAD_H
10 #define AX25_PAD_H 1
11
12
13 #define AX25_MAX_REPEATERS 8
14 #define AX25_MIN_ADDRS 2 /* Destinatin & Source. */
15 #define AX25_MAX_ADDRS 10 /* Destination, Source, 8 digipeaters. */
16
17 #define AX25_DESTINATION 0 /* Address positions in frame. */
18 #define AX25_SOURCE 1
19 #define AX25_REPEATER_1 2
20 #define AX25_REPEATER_2 3
21 #define AX25_REPEATER_3 4
22 #define AX25_REPEATER_4 5
23 #define AX25_REPEATER_5 6
24 #define AX25_REPEATER_6 7
25 #define AX25_REPEATER_7 8
26 #define AX25_REPEATER_8 9
27
28 #define AX25_MAX_ADDR_LEN 12 /* In theory, you would expect the maximum length */
29 /* to be 6 letters, dash, 2 digits, and nul for a */
30 /* total of 10. However, object labels can be 10 */
31 /* characters so throw in a couple extra bytes */
32 /* to be safe. */
33
34 #define AX25_MIN_INFO_LEN 0 /* Previously 1 when considering only APRS. */
35
36 #define AX25_MAX_INFO_LEN 2048 /* Maximum size for APRS. */
37 /* AX.25 starts out with 256 as the default max */
38 /* length but the end stations can negotiate */
39 /* something different. */
40 /* version 0.8: Change from 256 to 2028 to */
41 /* handle the larger paclen for Linux AX25. */
42
43 /* These don't include the 2 bytes for the */
44 /* HDLC frame FCS. */
45
46 /*
47 * Previously, for APRS only.
48 * #define AX25_MIN_PACKET_LEN ( 2 * 7 + 2 + AX25_MIN_INFO_LEN)
49 * #define AX25_MAX_PACKET_LEN ( AX25_MAX_ADDRS * 7 + 2 + AX25_MAX_INFO_LEN)
50 */
51
52 /* The more general case. */
53 /* An AX.25 frame can have a control byte and no protocol. */
54
55 #define AX25_MIN_PACKET_LEN ( 2 * 7 + 1 )
56
57 #define AX25_MAX_PACKET_LEN ( AX25_MAX_ADDRS * 7 + 2 + 3 + AX25_MAX_INFO_LEN)
58
59
60 /*
61 * packet_t is a pointer to a packet object.
62 *
63 * The actual implementation is not visible outside ax25_pad.c.
64 */
65
66 #define AX25_UI_FRAME 3 /* Control field value. */
67
68 #define AX25_PID_NO_LAYER_3 0xf0 /* protocol ID used for APRS */
69 #define AX25_PID_SEGMENTATION_FRAGMENT 0x08
70 #define AX25_PID_ESCAPE_CHARACTER 0xff
71
72
73 #ifdef AX25_PAD_C /* Keep this hidden - implementation could change. */
74
75 struct packet_s {
76
77 int magic1; /* for error checking. */
78
79 int seq; /* unique sequence number for debugging. */
80
81 double release_time; /* Time stamp in format returned by dtime_now(). */
82 /* When to release from the SATgate mode delay queue. */
83
84 #define MAGIC 0x41583235
85
86 struct packet_s *nextp; /* Pointer to next in queue. */
87
88 int num_addr; /* Number of addresses in frame. */
89 /* Range of AX25_MIN_ADDRS .. AX25_MAX_ADDRS for AX.25. */
90 /* It will be 0 if it doesn't look like AX.25. */
91 /* -1 is used temporarily at allocation to mean */
92 /* not determined yet. */
93
94
95
96 /*
97 * The 7th octet of each address contains:
98 *
99 * Bits: H R R SSID 0
100 *
101 * H for digipeaters set to 0 intially.
102 * Changed to 1 when position has been used.
103 *
104 * for source & destination it is called
105 * command/response. Normally both 1 for APRS.
106 * They should be opposites for connected mode.
107 *
108 * R R Reserved. Normally set to 1 1.
109 *
110 * SSID Substation ID. Range of 0 - 15.
111 *
112 * 0 Usually 0 but 1 for last address.
113 */
114
115
116 #define SSID_H_MASK 0x80
117 #define SSID_H_SHIFT 7
118
119 #define SSID_RR_MASK 0x60
120 #define SSID_RR_SHIFT 5
121
122 #define SSID_SSID_MASK 0x1e
123 #define SSID_SSID_SHIFT 1
124
125 #define SSID_LAST_MASK 0x01
126
127
128 int frame_len; /* Frame length without CRC. */
129
130 int modulo; /* I & S frames have sequence numbers of either 3 bits (modulo 8) */
131 /* or 7 bits (modulo 128). This is conveyed by either 1 or 2 */
132 /* control bytes. Unfortunately, we can't determine this by looking */
133 /* at an isolated frame. We need to know about the context. If we */
134 /* are part of the conversation, we would know. But if we are */
135 /* just listening to others, this would be more difficult to determine. */
136
137 /* For U frames: set to 0 - not applicable */
138 /* For I & S frames: 8 or 128 if known. 0 if unknown. */
139
140 unsigned char frame_data[AX25_MAX_PACKET_LEN+1];
141 /* Raw frame contents, without the CRC. */
142
143
144 int magic2; /* Will get stomped on if above overflows. */
145 };
146
147
148
149
150 #else /* Public view. */
151
152 struct packet_s {
153 int secret;
154 };
155
156 #endif
157
158
159 typedef struct packet_s *packet_t;
160
161 typedef enum cmdres_e { cr_00 = 2, cr_cmd = 1, cr_res = 0, cr_11 = 3 } cmdres_t;
162
163
164 extern packet_t ax25_new (void);
165
166
167 #ifdef AX25_PAD_C /* Keep this hidden - implementation could change. */
168
169
170 /*
171 * APRS always has one control octet of 0x03 but the more
172 * general AX.25 case is one or two control bytes depending on
173 * whether "modulo 128 operation" is in effect.
174 */
175
176 //#define DEBUGX 1
177
ax25_get_control_offset(packet_t this_p)178 static inline int ax25_get_control_offset (packet_t this_p)
179 {
180 return (this_p->num_addr*7);
181 }
182
ax25_get_num_control(packet_t this_p)183 static inline int ax25_get_num_control (packet_t this_p)
184 {
185 int c;
186
187 c = this_p->frame_data[ax25_get_control_offset(this_p)];
188
189 if ( (c & 0x01) == 0 ) { /* I xxxx xxx0 */
190 #if DEBUGX
191 dw_printf ("ax25_get_num_control, %02x is I frame, returns %d\n", c, (this_p->modulo == 128) ? 2 : 1);
192 #endif
193 return ((this_p->modulo == 128) ? 2 : 1);
194 }
195
196 if ( (c & 0x03) == 1 ) { /* S xxxx xx01 */
197 #if DEBUGX
198 dw_printf ("ax25_get_num_control, %02x is S frame, returns %d\n", c, (this_p->modulo == 128) ? 2 : 1);
199 #endif
200 return ((this_p->modulo == 128) ? 2 : 1);
201 }
202
203 #if DEBUGX
204 dw_printf ("ax25_get_num_control, %02x is U frame, always returns 1.\n", c);
205 #endif
206
207 return (1); /* U xxxx xx11 */
208 }
209
210
211
212 /*
213 * APRS always has one protocol octet of 0xF0 meaning no level 3
214 * protocol but the more general case is 0, 1 or 2 protocol ID octets.
215 */
216
ax25_get_pid_offset(packet_t this_p)217 static inline int ax25_get_pid_offset (packet_t this_p)
218 {
219 return (ax25_get_control_offset (this_p) + ax25_get_num_control(this_p));
220 }
221
ax25_get_num_pid(packet_t this_p)222 static int ax25_get_num_pid (packet_t this_p)
223 {
224 int c;
225 int pid;
226
227 c = this_p->frame_data[ax25_get_control_offset(this_p)];
228
229 if ( (c & 0x01) == 0 || /* I xxxx xxx0 */
230 c == 0x03 || c == 0x13) { /* UI 000x 0011 */
231
232 pid = this_p->frame_data[ax25_get_pid_offset(this_p)];
233 #if DEBUGX
234 dw_printf ("ax25_get_num_pid, %02x is I or UI frame, pid = %02x, returns %d\n", c, pid, (pid==AX25_PID_ESCAPE_CHARACTER) ? 2 : 1);
235 #endif
236 if (pid == AX25_PID_ESCAPE_CHARACTER) {
237 return (2); /* pid 1111 1111 means another follows. */
238 }
239 return (1);
240 }
241 #if DEBUGX
242 dw_printf ("ax25_get_num_pid, %02x is neither I nor UI frame, returns 0\n", c);
243 #endif
244 return (0);
245 }
246
247
248 /*
249 * AX.25 has info field for 5 frame types depending on the control field.
250 *
251 * xxxx xxx0 I
252 * 000x 0011 UI (which includes APRS)
253 * 101x 1111 XID
254 * 111x 0011 TEST
255 * 100x 0111 FRMR
256 *
257 * APRS always has an Information field with at least one octet for the Data Type Indicator.
258 */
259
ax25_get_info_offset(packet_t this_p)260 static inline int ax25_get_info_offset (packet_t this_p)
261 {
262 int offset = ax25_get_control_offset (this_p) + ax25_get_num_control(this_p) + ax25_get_num_pid(this_p);
263 #if DEBUGX
264 dw_printf ("ax25_get_info_offset, returns %d\n", offset);
265 #endif
266 return (offset);
267 }
268
ax25_get_num_info(packet_t this_p)269 static inline int ax25_get_num_info (packet_t this_p)
270 {
271 int len;
272
273 /* assuming AX.25 frame. */
274
275 len = this_p->frame_len - this_p->num_addr * 7 - ax25_get_num_control(this_p) - ax25_get_num_pid(this_p);
276 if (len < 0) {
277 len = 0; /* print error? */
278 }
279
280 return (len);
281 }
282
283 #endif
284
285
286 typedef enum ax25_modulo_e { modulo_unknown = 0, modulo_8 = 8, modulo_128 = 128 } ax25_modulo_t;
287
288 typedef enum ax25_frame_type_e {
289
290 frame_type_I = 0, // Information
291
292 frame_type_S_RR, // Receive Ready - System Ready To Receive
293 frame_type_S_RNR, // Receive Not Ready - TNC Buffer Full
294 frame_type_S_REJ, // Reject Frame - Out of Sequence or Duplicate
295 frame_type_S_SREJ, // Selective Reject - Request single frame repeat
296
297 frame_type_U_SABME, // Set Async Balanced Mode, Extended
298 frame_type_U_SABM, // Set Async Balanced Mode
299 frame_type_U_DISC, // Disconnect
300 frame_type_U_DM, // Disconnect Mode
301 frame_type_U_UA, // Unnumbered Acknowledge
302 frame_type_U_FRMR, // Frame Reject
303 frame_type_U_UI, // Unnumbered Information
304 frame_type_U_XID, // Exchange Identification
305 frame_type_U_TEST, // Test
306 frame_type_U, // other Unnumbered, not used by AX.25.
307
308 frame_not_AX25 // Could not get control byte from frame.
309 // This must be last because value plus 1 is
310 // for the size of an array.
311
312 } ax25_frame_type_t;
313
314
315 /*
316 * Originally this was a single number.
317 * Let's try something new in version 1.2.
318 * Also collect AGC values from the mark and space filters.
319 */
320
321 typedef struct alevel_s {
322
323 int rec;
324 int mark;
325 int space;
326 //float ms_ratio; // TODO: take out after temporary investigation.
327 } alevel_t;
328
329
330 #ifndef AXTEST
331 // TODO: remove this?
332 #define AX25MEMDEBUG 1
333 #endif
334
335
336 #if AX25MEMDEBUG // to investigate a memory leak problem
337
338
339 extern void ax25memdebug_set(void);
340 extern int ax25memdebug_get (void);
341 extern int ax25memdebug_seq (packet_t this_p);
342
343
344 extern packet_t ax25_from_text_debug (char *monitor, int strict, char *src_file, int src_line);
345 #define ax25_from_text(m,s) ax25_from_text_debug(m,s,__FILE__,__LINE__)
346
347 extern packet_t ax25_from_frame_debug (unsigned char *data, int len, alevel_t alevel, char *src_file, int src_line);
348 #define ax25_from_frame(d,l,a) ax25_from_frame_debug(d,l,a,__FILE__,__LINE__);
349
350 extern packet_t ax25_dup_debug (packet_t copy_from, char *src_file, int src_line);
351 #define ax25_dup(p) ax25_dup_debug(p,__FILE__,__LINE__);
352
353 extern void ax25_delete_debug (packet_t pp, char *src_file, int src_line);
354 #define ax25_delete(p) ax25_delete_debug(p,__FILE__,__LINE__);
355
356 #else
357
358 extern packet_t ax25_from_text (char *monitor, int strict);
359
360 extern packet_t ax25_from_frame (unsigned char *data, int len, alevel_t alevel);
361
362 extern packet_t ax25_dup (packet_t copy_from);
363
364 extern void ax25_delete (packet_t pp);
365
366 #endif
367
368
369
370
371 extern int ax25_parse_addr (int position, char *in_addr, int strict, char *out_addr, int *out_ssid, int *out_heard);
372 extern int ax25_check_addresses (packet_t pp);
373
374 extern packet_t ax25_unwrap_third_party (packet_t from_pp);
375
376 extern void ax25_set_addr (packet_t pp, int, char *);
377 extern void ax25_insert_addr (packet_t this_p, int n, char *ad);
378 extern void ax25_remove_addr (packet_t this_p, int n);
379
380 extern int ax25_get_num_addr (packet_t pp);
381 extern int ax25_get_num_repeaters (packet_t this_p);
382
383 extern void ax25_get_addr_with_ssid (packet_t pp, int n, char *station);
384 extern void ax25_get_addr_no_ssid (packet_t pp, int n, char *station);
385
386 extern int ax25_get_ssid (packet_t pp, int n);
387 extern void ax25_set_ssid (packet_t this_p, int n, int ssid);
388
389 extern int ax25_get_h (packet_t pp, int n);
390
391 extern void ax25_set_h (packet_t pp, int n);
392
393 extern int ax25_get_heard(packet_t this_p);
394
395 extern int ax25_get_first_not_repeated(packet_t pp);
396
397 extern int ax25_get_rr (packet_t this_p, int n);
398
399 extern int ax25_get_info (packet_t pp, unsigned char **paddr);
400 extern int ax25_cut_at_crlf (packet_t this_p);
401
402 extern void ax25_set_nextp (packet_t this_p, packet_t next_p);
403
404 extern int ax25_get_dti (packet_t this_p);
405
406 extern packet_t ax25_get_nextp (packet_t this_p);
407
408 extern void ax25_set_release_time (packet_t this_p, double release_time);
409 extern double ax25_get_release_time (packet_t this_p);
410
411 extern void ax25_set_modulo (packet_t this_p, int modulo);
412
413 extern void ax25_format_addrs (packet_t pp, char *);
414 extern void ax25_format_via_path (packet_t this_p, char *result, size_t result_size);
415
416 extern int ax25_pack (packet_t pp, unsigned char result[AX25_MAX_PACKET_LEN]);
417
418 extern ax25_frame_type_t ax25_frame_type (packet_t this_p, cmdres_t *cr, char *desc, int *pf, int *nr, int *ns);
419
420 extern void ax25_hex_dump (packet_t this_p);
421
422 extern int ax25_is_aprs (packet_t pp);
423 extern int ax25_is_null_frame (packet_t this_p);
424
425 extern int ax25_get_control (packet_t this_p);
426 extern int ax25_get_c2 (packet_t this_p);
427
428 extern int ax25_get_pid (packet_t this_p);
429
430 extern int ax25_get_frame_len (packet_t this_p);
431
432 extern unsigned short ax25_dedupe_crc (packet_t pp);
433
434 extern unsigned short ax25_m_m_crc (packet_t pp);
435
436 extern void ax25_safe_print (char *, int, int ascii_only);
437
438 #define AX25_ALEVEL_TO_TEXT_SIZE 40 // overkill but safe.
439 extern int ax25_alevel_to_text (alevel_t alevel, char text[AX25_ALEVEL_TO_TEXT_SIZE]);
440
441
442 #endif /* AX25_PAD_H */
443
444 /* end ax25_pad.h */
445
446
447