aboutsummaryrefslogtreecommitdiffstats
path: root/enum.c
blob: a17281c16e4aba244bbc36239c2a7be54e592658 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
/*
 * ENUM Support for Asterisk
 *
 * Copyright (C) 2003-2005, Digium, inc
 *
 * Written by Mark Spencer <markster@digium.com>
 *
 * Funding provided by nic.at
 *
 * Distributed under the terms of the GNU GPL
 *
 */

#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/nameser.h>
#if __APPLE_CC__ >= 1495
#include <arpa/nameser_compat.h>
#endif
#include <resolv.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <regex.h>
#include <unistd.h>
#include <errno.h>

#include "asterisk/logger.h"
#include "asterisk/options.h"
#include "asterisk/enum.h"
#include "asterisk/dns.h"
#include "asterisk/channel.h"
#include "asterisk/config.h"
#include "asterisk/utils.h"

#ifdef __APPLE__
#undef T_NAPTR
#define T_NAPTR 35
#endif

#ifdef __APPLE__
#undef T_TXT
#define T_TXT 16
#endif

/* The IETF Enum standard root, managed by the ITU */
#define TOPLEV "e164.arpa."

/* Linked list from config file */
static struct enum_search {
	char toplev[80];
	struct enum_search *next;
} *toplevs;

static int enumver = 0;

AST_MUTEX_DEFINE_STATIC(enumlock);

struct naptr {
	unsigned short order;
	unsigned short pref;
} __attribute__ ((__packed__));

/*--- parse_ie: Parse NAPTR record information elements */
static int parse_ie(unsigned char *data, int maxdatalen, unsigned char *src, int srclen)
{
	int len, olen;

	len = olen = (int)src[0];
	src++;
	srclen--;
	if (len > srclen) {
		ast_log(LOG_WARNING, "Want %d, got %d\n", len, srclen);
		return -1;
	}
	if (len > maxdatalen)
		len = maxdatalen;
	memcpy(data, src, len);
	return olen + 1;
}

/*--- parse_naptr: Parse DNS NAPTR record used in ENUM ---*/
static int parse_naptr(unsigned char *dst, int dstsize, char *tech, int techsize, unsigned char *answer, int len, char *naptrinput)
{
	unsigned char *oanswer = answer;
	unsigned char flags[80] = "";
	unsigned char services[80] = "";
	unsigned char regexp[80] = "";
	unsigned char repl[80] = "";
	unsigned char temp[80] = "";
	unsigned char delim;
	unsigned char *delim2;
	unsigned char *pattern, *subst, *d;
	int res;
	int regexp_len, size, backref;
	int d_len = sizeof(temp) - 1;
	regex_t preg;
	regmatch_t pmatch[9];


	dst[0] = '\0';
	
	if (len < sizeof(struct naptr)) {
		ast_log(LOG_WARNING, "NAPTR record length too short\n");
		return -1;
	}
	answer += sizeof(struct naptr);
	len -= sizeof(struct naptr);
	if ((res = parse_ie(flags, sizeof(flags) - 1, answer, len)) < 0) {
		ast_log(LOG_WARNING, "Failed to get flags from NAPTR record\n");
		return -1; 
	} else { 
		answer += res; 
		len -= res; 
	}
	if ((res = parse_ie(services, sizeof(services) - 1, answer, len)) < 0) {
		ast_log(LOG_WARNING, "Failed to get services from NAPTR record\n");
		return -1; 
	} else { 
		answer += res; 
		len -= res; 
	}
	if ((res = parse_ie(regexp, sizeof(regexp) - 1, answer, len)) < 0) {
		ast_log(LOG_WARNING, "Failed to get regexp from NAPTR record\n");
		return -1; 
	} else { 
		answer += res; 
		len -= res; 
	}
	if ((res = dn_expand(oanswer,answer + len,answer, repl, sizeof(repl) - 1)) < 0) {
		ast_log(LOG_WARNING, "Failed to expand hostname\n");
		return -1;
	} 

	if (option_debug > 2)	/* Advanced NAPTR debugging */
		ast_log(LOG_DEBUG, "NAPTR input='%s', flags='%s', services='%s', regexp='%s', repl='%s'\n",
			naptrinput, flags, services, regexp, repl);

	if (tolower(flags[0]) != 'u') {
		ast_log(LOG_WARNING, "NAPTR Flag must be 'U' or 'u'.\n");
		return -1;
	}

	if ((!strncasecmp(services, "e2u+sip", 7)) || 
	    (!strncasecmp(services, "sip+e2u", 7))) {
		strncpy(tech, "sip", techsize -1); 
	} else if ((!strncasecmp(services, "e2u+h323", 8)) || 
	    (!strncasecmp(services, "h323+e2u", 8))) {
		strncpy(tech, "h323", techsize -1); 
	} else if ((!strncasecmp(services, "e2u+x-iax2", 10)) || 
	    (!strncasecmp(services, "e2u+iax2", 8)) ||
	    (!strncasecmp(services, "iax2+e2u", 8))) {
		strncpy(tech, "iax2", techsize -1); 
	} else if ((!strncasecmp(services, "e2u+x-iax", 9)) ||
	    (!strncasecmp(services, "e2u+iax", 7)) ||
	    (!strncasecmp(services, "iax+e2u", 7))) {
		strncpy(tech, "iax", techsize -1); 
	} else if ((!strncasecmp(services, "e2u+tel", 7)) || 
	    (!strncasecmp(services, "tel+e2u", 7))) {
		strncpy(tech, "tel", techsize -1); 
	} else if (!strncasecmp(services, "e2u+voice:", 10)) {
		strncpy(tech, services+10, techsize -1); 
	} else {
		ast_log(LOG_DEBUG, 
		"Services must be e2u+${tech}, ${tech}+e2u, or e2u+voice: where $tech is from (sip, h323, tel, iax, iax2). \n");
		return 0;
	}

	/* DEDBUGGING STUB
	strncpy(regexp, "!^\\+43(.*)$!\\1@bla.fasel!", sizeof(regexp) - 1);
	*/

	regexp_len = strlen(regexp);
	if (regexp_len < 7) {
		ast_log(LOG_WARNING, "Regex too short to be meaningful.\n");
		return -1;
	} 


	delim = regexp[0];
	delim2 = strchr(regexp + 1, delim);
	if ((delim2 == NULL) || (regexp[regexp_len-1] != delim)) {
		ast_log(LOG_WARNING, "Regex delimiter error (on \"%s\").\n",regexp);
		return -1;
	}

	pattern = regexp + 1;
	*delim2 = 0;
	subst   = delim2 + 1;
	regexp[regexp_len-1] = 0;

#if 0
	printf("Pattern: %s\n", pattern);
	printf("Subst: %s\n", subst);
#endif

/*
 * now do the regex wizardry.
 */

	if (regcomp(&preg, pattern, REG_EXTENDED | REG_NEWLINE)) {
		ast_log(LOG_WARNING, "NAPTR Regex compilation error (regex = \"%s\").\n",regexp);
		return -1;
	}

	if (preg.re_nsub > 9) {
		ast_log(LOG_WARNING, "NAPTR Regex compilation error: too many subs.\n");
		regfree(&preg);
		return -1;
	}

	if (regexec(&preg, naptrinput, 9, pmatch, 0)) {
		ast_log(LOG_WARNING, "NAPTR Regex match failed.\n");
		regfree(&preg);
		return -1;
	}
	regfree(&preg);

	d = temp; 
	d_len--; 
	while( *subst && (d_len > 0) ) {
		if ((subst[0] == '\\') && isdigit(subst[1]) && (pmatch[subst[1]-'0'].rm_so != -1)) {
			backref = subst[1]-'0';
			size = pmatch[backref].rm_eo - pmatch[backref].rm_so;
			if (size > d_len) {
				ast_log(LOG_WARNING, "Not enough space during NAPTR regex substitution.\n");
				return -1;
				}
			memcpy(d, naptrinput + pmatch[backref].rm_so, size);
			d += size;
			d_len -= size;
			subst += 2;
		} else if (isprint(*subst)) {
			*d++ = *subst++;
			d_len--;
		} else {
			ast_log(LOG_WARNING, "Error during regex substitution.\n");
			return -1;
		}
	}
	*d = 0;
	strncpy(dst, temp, dstsize - 1);
	dst[dstsize - 1] = '\0';
	return 0;
}

struct enum_context {
	char *dst;	/* Destination part of URL from ENUM */
	int dstlen;	/* Length */
	char *tech;	/* Technology (from URL scheme) */
	int techlen;	/* Length */
	char *txt;	/* TXT record in TXT lookup */
	int txtlen;	/* Length */
	char *naptrinput;	/* The number to lookup */
};

/*--- txt_callback: Callback for TXT record lookup */
static int txt_callback(void *context, u_char *answer, int len, u_char *fullanswer)
{
	struct enum_context *c = (struct enum_context *)context;
#if 0
	printf("ENUMTXT Called\n");
#endif

	if (answer == NULL) {
		c->txt = NULL;
		c->txtlen = 0;
		return 0;
	}

	/* skip over first byte, as for some reason it's a vertical tab character */
	answer += 1;
	len -= 1;

	/* answer is not null-terminated, but should be */
	/* this is safe to do, as answer has extra bytes on the end we can 
           safely overwrite with a null */
	answer[len] = '\0';
	/* now increment len so that len includes the null, so that we can
	   compare apples to apples */
	len +=1;

	/* finally, copy the answer into c->txt */
	strncpy(c->txt, answer, len < c->txtlen ? len-1 : (c->txtlen)-1);
	
	/* just to be safe, let's make sure c->txt is null terminated */
	c->txt[(c->txtlen)-1] = '\0';

	return 1;
}

/*--- enum_callback: Callback from ENUM lookup function */
static int enum_callback(void *context, u_char *answer, int len, u_char *fullanswer)
{
	struct enum_context *c = (struct enum_context *)context;

	if (parse_naptr(c->dst, c->dstlen, c->tech, c->techlen, answer, len, c->naptrinput)) {
		ast_log(LOG_WARNING, "Failed to parse naptr :(\n");
		return -1;
	}

	if (!ast_strlen_zero(c->dst))
		return 1;

	return 0;
}

/*--- ast_get_enum: ENUM lookup */
int ast_get_enum(struct ast_channel *chan, const char *number, char *dst, int dstlen, char *tech, int techlen)
{
	struct enum_context context;
	char tmp[259 + 80];
	char naptrinput[80] = "+";
	int pos = strlen(number) - 1;
	int newpos = 0;
	int ret = -1;
	struct enum_search *s = NULL;
	int version = -1;

	strncat(naptrinput, number, sizeof(naptrinput) - 2);

	context.naptrinput = naptrinput;	/* The number */
	context.dst = dst;			/* Return string */
	context.dstlen = dstlen;
	context.tech = tech;			/* Return string */
	context.techlen = techlen;

	if (pos > 128)
		pos = 128;
	while(pos >= 0) {
		tmp[newpos++] = number[pos--];
		tmp[newpos++] = '.';
	}
	
	if (chan && ast_autoservice_start(chan) < 0)
		return -1;

	for(;;) {
		ast_mutex_lock(&enumlock);
		if (version != enumver) {
			/* Ooh, a reload... */
			s = toplevs;
			version = enumver;
		} else {
			s = s->next;
		}
		if (s) {
			strncpy(tmp + newpos, s->toplev, sizeof(tmp) - newpos - 1);
		}
		ast_mutex_unlock(&enumlock);
		if (!s)
			break;
		ret = ast_search_dns(&context, tmp, C_IN, T_NAPTR, enum_callback);
		if (ret > 0)
			break;
	}
	if (ret < 0) {
		ast_log(LOG_DEBUG, "No such number found: %s (%s)\n", tmp, strerror(errno));
		ret = 0;
	}
	if (chan)
		ret |= ast_autoservice_stop(chan);
	return ret;
}

/*--- ast_get_txt: Get TXT record from DNS. 
	Really has nothing to do with enum, but anyway...
 */
int ast_get_txt(struct ast_channel *chan, const char *number, char *dst, int dstlen, char *tech, int techlen, char *txt, int txtlen)
{
	struct enum_context context;
	char tmp[259 + 80];
	char naptrinput[80] = "+";
	int pos = strlen(number) - 1;
	int newpos = 0;
	int ret = -1;
	struct enum_search *s = NULL;
	int version = -1;

	strncat(naptrinput, number, sizeof(naptrinput) - 2);

	context.naptrinput = naptrinput;
	context.dst = dst;
	context.dstlen = dstlen;
	context.tech = tech;
	context.techlen = techlen;
	context.txt = txt;
	context.txtlen = txtlen;

	if (pos > 128)
		pos = 128;
	while(pos >= 0) {
		tmp[newpos++] = number[pos--];
		tmp[newpos++] = '.';
	}
	
	if (chan && ast_autoservice_start(chan) < 0)
		return -1;

	for(;;) {
		ast_mutex_lock(&enumlock);
		if (version != enumver) {
			/* Ooh, a reload... */
			s = toplevs;
			version = enumver;
		} else {
			s = s->next;
		}
		if (s) {
			strncpy(tmp + newpos, s->toplev, sizeof(tmp) - newpos - 1);
		}
		ast_mutex_unlock(&enumlock);
		if (!s)
			break;

		ret = ast_search_dns(&context, tmp, C_IN, T_TXT, txt_callback);
		if (ret > 0)
			break;
	}
	if (ret < 0) {
		ast_log(LOG_DEBUG, "No such number found: %s (%s)\n", tmp, strerror(errno));
		ret = 0;
	}
	if (chan)
		ret |= ast_autoservice_stop(chan);
	return ret;
}

/*--- enum_newtoplev: Add enum tree to linked list ---*/
static struct enum_search *enum_newtoplev(char *s)
{
	struct enum_search *tmp;

	tmp = malloc(sizeof(struct enum_search));
	if (tmp) {
		memset(tmp, 0, sizeof(struct enum_search));
		strncpy(tmp->toplev, s, sizeof(tmp->toplev) - 1);
	}
	return tmp;
}

/*--- ast_enum_init: Initialize the ENUM support subsystem */
int ast_enum_init(void)
{
	struct ast_config *cfg;
	struct enum_search *s, *sl;
	struct ast_variable *v;

	/* Destroy existing list */
	ast_mutex_lock(&enumlock);
	s = toplevs;
	while(s) {
		sl = s;
		s = s->next;
		free(sl);
	}
	toplevs = NULL;
	cfg = ast_config_load("enum.conf");
	if (cfg) {
		sl = NULL;
		v = ast_variable_browse(cfg, "general");
		while(v) {
			if (!strcasecmp(v->name, "search")) {
				s = enum_newtoplev(v->value);
				if (s) {
					if (sl)
						sl->next = s;
					else
						toplevs = s;
					sl = s;
				}
			}
			v = v->next;
		}
		ast_config_destroy(cfg);
	} else {
		toplevs = enum_newtoplev(TOPLEV);
	}
	enumver++;
	ast_mutex_unlock(&enumlock);
	return 0;
}

int ast_enum_reload(void)
{
	return ast_enum_init();
}