blob: 7be90018d9071ea71a3bfaac808a2ce077133e4b
1 | /* vi: set sw=4 ts=4: */ |
2 | /* |
3 | * Mini DNS server implementation for busybox |
4 | * |
5 | * Copyright (C) 2005 Roberto A. Foglietta (me@roberto.foglietta.name) |
6 | * Copyright (C) 2005 Odd Arild Olsen (oao at fibula dot no) |
7 | * Copyright (C) 2003 Paul Sheer |
8 | * |
9 | * Licensed under GPLv2 or later, see file LICENSE in this source tree. |
10 | * |
11 | * Odd Arild Olsen started out with the sheerdns [1] of Paul Sheer and rewrote |
12 | * it into a shape which I believe is both easier to understand and maintain. |
13 | * I also reused the input buffer for output and removed services he did not |
14 | * need. [1] http://threading.2038bug.com/sheerdns/ |
15 | * |
16 | * Some bugfix and minor changes was applied by Roberto A. Foglietta who made |
17 | * the first porting of oao' scdns to busybox also. |
18 | */ |
19 | //config:config DNSD |
20 | //config: bool "dnsd" |
21 | //config: default y |
22 | //config: help |
23 | //config: Small and static DNS server daemon. |
24 | |
25 | //applet:IF_DNSD(APPLET(dnsd, BB_DIR_USR_SBIN, BB_SUID_DROP)) |
26 | |
27 | //kbuild:lib-$(CONFIG_DNSD) += dnsd.o |
28 | |
29 | //usage:#define dnsd_trivial_usage |
30 | //usage: "[-dvs] [-c CONFFILE] [-t TTL_SEC] [-p PORT] [-i ADDR]" |
31 | //usage:#define dnsd_full_usage "\n\n" |
32 | //usage: "Small static DNS server daemon\n" |
33 | //usage: "\n -c FILE Config file" |
34 | //usage: "\n -t SEC TTL" |
35 | //usage: "\n -p PORT Listen on PORT" |
36 | //usage: "\n -i ADDR Listen on ADDR" |
37 | //usage: "\n -d Daemonize" |
38 | //usage: "\n -v Verbose" |
39 | //usage: "\n -s Send successful replies only. Use this if you want" |
40 | //usage: "\n to use /etc/resolv.conf with two nameserver lines:" |
41 | //usage: "\n nameserver DNSD_SERVER" |
42 | //usage: "\n nameserver NORMAL_DNS_SERVER" |
43 | |
44 | #include "libbb.h" |
45 | #include <syslog.h> |
46 | |
47 | //#define DEBUG 1 |
48 | #define DEBUG 0 |
49 | |
50 | enum { |
51 | /* can tweak this */ |
52 | DEFAULT_TTL = 120, |
53 | |
54 | /* cannot get bigger packets than 512 per RFC1035. */ |
55 | MAX_PACK_LEN = 512, |
56 | IP_STRING_LEN = sizeof(".xxx.xxx.xxx.xxx"), |
57 | MAX_NAME_LEN = IP_STRING_LEN - 1 + sizeof(".in-addr.arpa"), |
58 | REQ_A = 1, |
59 | REQ_PTR = 12, |
60 | }; |
61 | |
62 | /* the message from client and first part of response msg */ |
63 | struct dns_head { |
64 | uint16_t id; |
65 | uint16_t flags; |
66 | uint16_t nquer; |
67 | uint16_t nansw; |
68 | uint16_t nauth; |
69 | uint16_t nadd; |
70 | }; |
71 | /* Structure used to access type and class fields. |
72 | * They are totally unaligned, but gcc 4.3.4 thinks that pointer of type uint16_t* |
73 | * is 16-bit aligned and replaces 16-bit memcpy (in move_from_unaligned16 macro) |
74 | * with aligned halfword access on arm920t! |
75 | * Oh well. Slapping PACKED everywhere seems to help: */ |
76 | struct type_and_class { |
77 | uint16_t type PACKED; |
78 | uint16_t class PACKED; |
79 | } PACKED; |
80 | /* element of known name, ip address and reversed ip address */ |
81 | struct dns_entry { |
82 | struct dns_entry *next; |
83 | uint32_t ip; |
84 | char rip[IP_STRING_LEN]; /* length decimal reversed IP */ |
85 | char name[1]; |
86 | }; |
87 | |
88 | #define OPT_verbose (option_mask32 & 1) |
89 | #define OPT_silent (option_mask32 & 2) |
90 | |
91 | |
92 | /* |
93 | * Insert length of substrings instead of dots |
94 | */ |
95 | static void undot(char *rip) |
96 | { |
97 | int i = 0; |
98 | int s = 0; |
99 | |
100 | while (rip[i]) |
101 | i++; |
102 | for (--i; i >= 0; i--) { |
103 | if (rip[i] == '.') { |
104 | rip[i] = s; |
105 | s = 0; |
106 | } else { |
107 | s++; |
108 | } |
109 | } |
110 | } |
111 | |
112 | /* |
113 | * Read hostname/IP records from file |
114 | */ |
115 | static struct dns_entry *parse_conf_file(const char *fileconf) |
116 | { |
117 | char *token[2]; |
118 | parser_t *parser; |
119 | struct dns_entry *m, *conf_data; |
120 | struct dns_entry **nextp; |
121 | |
122 | conf_data = NULL; |
123 | nextp = &conf_data; |
124 | |
125 | parser = config_open(fileconf); |
126 | while (config_read(parser, token, 2, 2, "# \t", PARSE_NORMAL)) { |
127 | struct in_addr ip; |
128 | uint32_t v32; |
129 | |
130 | if (inet_aton(token[1], &ip) == 0) { |
131 | bb_error_msg("error at line %u, skipping", parser->lineno); |
132 | continue; |
133 | } |
134 | |
135 | if (OPT_verbose) |
136 | bb_error_msg("name:%s, ip:%s", token[0], token[1]); |
137 | |
138 | /* sizeof(*m) includes 1 byte for m->name[0] */ |
139 | m = xzalloc(sizeof(*m) + strlen(token[0]) + 1); |
140 | /*m->next = NULL;*/ |
141 | *nextp = m; |
142 | nextp = &m->next; |
143 | |
144 | m->name[0] = '.'; |
145 | strcpy(m->name + 1, token[0]); |
146 | undot(m->name); |
147 | m->ip = ip.s_addr; /* in network order */ |
148 | v32 = ntohl(m->ip); |
149 | /* inverted order */ |
150 | sprintf(m->rip, ".%u.%u.%u.%u", |
151 | (uint8_t)(v32), |
152 | (uint8_t)(v32 >> 8), |
153 | (uint8_t)(v32 >> 16), |
154 | (v32 >> 24) |
155 | ); |
156 | undot(m->rip); |
157 | } |
158 | config_close(parser); |
159 | return conf_data; |
160 | } |
161 | |
162 | /* |
163 | * Look query up in dns records and return answer if found. |
164 | */ |
165 | static char *table_lookup(struct dns_entry *d, |
166 | uint16_t type, |
167 | char* query_string) |
168 | { |
169 | while (d) { |
170 | unsigned len = d->name[0]; |
171 | /* d->name[len] is the last (non NUL) char */ |
172 | #if DEBUG |
173 | char *p, *q; |
174 | q = query_string + 1; |
175 | p = d->name + 1; |
176 | fprintf(stderr, "%d/%d p:%s q:%s %d\n", |
177 | (int)strlen(p), len, |
178 | p, q, (int)strlen(q) |
179 | ); |
180 | #endif |
181 | if (type == htons(REQ_A)) { |
182 | /* search by host name */ |
183 | if (len != 1 || d->name[1] != '*') { |
184 | /* we are lax, hope no name component is ever >64 so that length |
185 | * (which will be represented as 'A','B'...) matches a lowercase letter. |
186 | * Actually, I think false matches are hard to construct. |
187 | * Example. |
188 | * [31] len is represented as '1', [65] as 'A', [65+32] as 'a'. |
189 | * [65] <65 same chars>[31]<31 same chars>NUL |
190 | * [65+32]<65 same chars>1 <31 same chars>NUL |
191 | * This example seems to be the minimal case when false match occurs. |
192 | */ |
193 | if (strcasecmp(d->name, query_string) != 0) |
194 | goto next; |
195 | } |
196 | return (char *)&d->ip; |
197 | #if DEBUG |
198 | fprintf(stderr, "Found IP:%x\n", (int)d->ip); |
199 | #endif |
200 | return 0; |
201 | } |
202 | /* search by IP-address */ |
203 | if ((len != 1 || d->name[1] != '*') |
204 | /* we assume (do not check) that query_string |
205 | * ends in ".in-addr.arpa" */ |
206 | && is_prefixed_with(query_string, d->rip) |
207 | ) { |
208 | #if DEBUG |
209 | fprintf(stderr, "Found name:%s\n", d->name); |
210 | #endif |
211 | return d->name; |
212 | } |
213 | next: |
214 | d = d->next; |
215 | } |
216 | |
217 | return NULL; |
218 | } |
219 | |
220 | /* |
221 | * Decode message and generate answer |
222 | */ |
223 | /* RFC 1035 |
224 | ... |
225 | Whenever an octet represents a numeric quantity, the left most bit |
226 | in the diagram is the high order or most significant bit. |
227 | That is, the bit labeled 0 is the most significant bit. |
228 | ... |
229 | |
230 | 4.1.1. Header section format |
231 | 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 |
232 | +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ |
233 | | ID | |
234 | +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ |
235 | |QR| OPCODE |AA|TC|RD|RA| 0 0 0| RCODE | |
236 | +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ |
237 | | QDCOUNT | |
238 | +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ |
239 | | ANCOUNT | |
240 | +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ |
241 | | NSCOUNT | |
242 | +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ |
243 | | ARCOUNT | |
244 | +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ |
245 | ID 16 bit random identifier assigned by querying peer. |
246 | Used to match query/response. |
247 | QR message is a query (0), or a response (1). |
248 | OPCODE 0 standard query (QUERY) |
249 | 1 inverse query (IQUERY) |
250 | 2 server status request (STATUS) |
251 | AA Authoritative Answer - this bit is valid in responses. |
252 | Responding name server is an authority for the domain name |
253 | in question section. Answer section may have multiple owner names |
254 | because of aliases. The AA bit corresponds to the name which matches |
255 | the query name, or the first owner name in the answer section. |
256 | TC TrunCation - this message was truncated. |
257 | RD Recursion Desired - this bit may be set in a query and |
258 | is copied into the response. If RD is set, it directs |
259 | the name server to pursue the query recursively. |
260 | Recursive query support is optional. |
261 | RA Recursion Available - this be is set or cleared in a |
262 | response, and denotes whether recursive query support is |
263 | available in the name server. |
264 | RCODE Response code. |
265 | 0 No error condition |
266 | 1 Format error |
267 | 2 Server failure - server was unable to process the query |
268 | due to a problem with the name server. |
269 | 3 Name Error - meaningful only for responses from |
270 | an authoritative name server. The referenced domain name |
271 | does not exist. |
272 | 4 Not Implemented. |
273 | 5 Refused. |
274 | QDCOUNT number of entries in the question section. |
275 | ANCOUNT number of records in the answer section. |
276 | NSCOUNT number of records in the authority records section. |
277 | ARCOUNT number of records in the additional records section. |
278 | |
279 | 4.1.2. Question section format |
280 | |
281 | The section contains QDCOUNT (usually 1) entries, each of this format: |
282 | 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 |
283 | +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ |
284 | / QNAME / |
285 | / / |
286 | +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ |
287 | | QTYPE | |
288 | +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ |
289 | | QCLASS | |
290 | +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ |
291 | QNAME a domain name represented as a sequence of labels, where |
292 | each label consists of a length octet followed by that |
293 | number of octets. The domain name terminates with the |
294 | zero length octet for the null label of the root. Note |
295 | that this field may be an odd number of octets; no |
296 | padding is used. |
297 | QTYPE a two octet type of the query. |
298 | 1 a host address [REQ_A const] |
299 | 2 an authoritative name server |
300 | 3 a mail destination (Obsolete - use MX) |
301 | 4 a mail forwarder (Obsolete - use MX) |
302 | 5 the canonical name for an alias |
303 | 6 marks the start of a zone of authority |
304 | 7 a mailbox domain name (EXPERIMENTAL) |
305 | 8 a mail group member (EXPERIMENTAL) |
306 | 9 a mail rename domain name (EXPERIMENTAL) |
307 | 10 a null RR (EXPERIMENTAL) |
308 | 11 a well known service description |
309 | 12 a domain name pointer [REQ_PTR const] |
310 | 13 host information |
311 | 14 mailbox or mail list information |
312 | 15 mail exchange |
313 | 16 text strings |
314 | 0x1c IPv6? |
315 | 252 a request for a transfer of an entire zone |
316 | 253 a request for mailbox-related records (MB, MG or MR) |
317 | 254 a request for mail agent RRs (Obsolete - see MX) |
318 | 255 a request for all records |
319 | QCLASS a two octet code that specifies the class of the query. |
320 | 1 the Internet |
321 | (others are historic only) |
322 | 255 any class |
323 | |
324 | 4.1.3. Resource Record format |
325 | |
326 | The answer, authority, and additional sections all share the same format: |
327 | a variable number of resource records, where the number of records |
328 | is specified in the corresponding count field in the header. |
329 | Each resource record has this format: |
330 | 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 |
331 | +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ |
332 | / / |
333 | / NAME / |
334 | +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ |
335 | | TYPE | |
336 | +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ |
337 | | CLASS | |
338 | +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ |
339 | | TTL | |
340 | | | |
341 | +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ |
342 | | RDLENGTH | |
343 | +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--| |
344 | / RDATA / |
345 | / / |
346 | +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ |
347 | NAME a domain name to which this resource record pertains. |
348 | TYPE two octets containing one of the RR type codes. This |
349 | field specifies the meaning of the data in the RDATA field. |
350 | CLASS two octets which specify the class of the data in the RDATA field. |
351 | TTL a 32 bit unsigned integer that specifies the time interval |
352 | (in seconds) that the record may be cached. |
353 | RDLENGTH a 16 bit integer, length in octets of the RDATA field. |
354 | RDATA a variable length string of octets that describes the resource. |
355 | The format of this information varies according to the TYPE |
356 | and CLASS of the resource record. |
357 | If the TYPE is A and the CLASS is IN, it's a 4 octet IP address. |
358 | |
359 | 4.1.4. Message compression |
360 | |
361 | In order to reduce the size of messages, domain names coan be compressed. |
362 | An entire domain name or a list of labels at the end of a domain name |
363 | is replaced with a pointer to a prior occurance of the same name. |
364 | |
365 | The pointer takes the form of a two octet sequence: |
366 | +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ |
367 | | 1 1| OFFSET | |
368 | +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ |
369 | The first two bits are ones. This allows a pointer to be distinguished |
370 | from a label, since the label must begin with two zero bits because |
371 | labels are restricted to 63 octets or less. The OFFSET field specifies |
372 | an offset from the start of the message (i.e., the first octet |
373 | of the ID field in the domain header). |
374 | A zero offset specifies the first byte of the ID field, etc. |
375 | Domain name in a message can be represented as either: |
376 | - a sequence of labels ending in a zero octet |
377 | - a pointer |
378 | - a sequence of labels ending with a pointer |
379 | */ |
380 | static int process_packet(struct dns_entry *conf_data, |
381 | uint32_t conf_ttl, |
382 | uint8_t *buf) |
383 | { |
384 | struct dns_head *head; |
385 | struct type_and_class *unaligned_type_class; |
386 | const char *err_msg; |
387 | char *query_string; |
388 | char *answstr; |
389 | uint8_t *answb; |
390 | uint16_t outr_rlen; |
391 | uint16_t outr_flags; |
392 | uint16_t type; |
393 | uint16_t class; |
394 | int query_len; |
395 | |
396 | head = (struct dns_head *)buf; |
397 | if (head->nquer == 0) { |
398 | bb_error_msg("packet has 0 queries, ignored"); |
399 | return 0; /* don't reply */ |
400 | } |
401 | if (head->flags & htons(0x8000)) { /* QR bit */ |
402 | bb_error_msg("response packet, ignored"); |
403 | return 0; /* don't reply */ |
404 | } |
405 | /* QR = 1 "response", RCODE = 4 "Not Implemented" */ |
406 | outr_flags = htons(0x8000 | 4); |
407 | err_msg = NULL; |
408 | |
409 | /* start of query string */ |
410 | query_string = (void *)(head + 1); |
411 | /* caller guarantees strlen is <= MAX_PACK_LEN */ |
412 | query_len = strlen(query_string) + 1; |
413 | /* may be unaligned! */ |
414 | unaligned_type_class = (void *)(query_string + query_len); |
415 | query_len += sizeof(*unaligned_type_class); |
416 | /* where to append answer block */ |
417 | answb = (void *)(unaligned_type_class + 1); |
418 | |
419 | /* OPCODE != 0 "standard query"? */ |
420 | if ((head->flags & htons(0x7800)) != 0) { |
421 | err_msg = "opcode != 0"; |
422 | goto empty_packet; |
423 | } |
424 | move_from_unaligned16(class, &unaligned_type_class->class); |
425 | if (class != htons(1)) { /* not class INET? */ |
426 | err_msg = "class != 1"; |
427 | goto empty_packet; |
428 | } |
429 | move_from_unaligned16(type, &unaligned_type_class->type); |
430 | if (type != htons(REQ_A) && type != htons(REQ_PTR)) { |
431 | /* we can't handle this query type */ |
432 | //TODO: happens all the time with REQ_AAAA (0x1c) requests - implement those? |
433 | err_msg = "type is !REQ_A and !REQ_PTR"; |
434 | goto empty_packet; |
435 | } |
436 | |
437 | /* look up the name */ |
438 | answstr = table_lookup(conf_data, type, query_string); |
439 | #if DEBUG |
440 | /* Shows lengths instead of dots, unusable for !DEBUG */ |
441 | bb_error_msg("'%s'->'%s'", query_string, answstr); |
442 | #endif |
443 | outr_rlen = 4; |
444 | if (answstr && type == htons(REQ_PTR)) { |
445 | /* returning a host name */ |
446 | outr_rlen = strlen(answstr) + 1; |
447 | } |
448 | if (!answstr |
449 | || (unsigned)(answb - buf) + query_len + 4 + 2 + outr_rlen > MAX_PACK_LEN |
450 | ) { |
451 | /* QR = 1 "response" |
452 | * AA = 1 "Authoritative Answer" |
453 | * RCODE = 3 "Name Error" */ |
454 | err_msg = "name is not found"; |
455 | outr_flags = htons(0x8000 | 0x0400 | 3); |
456 | goto empty_packet; |
457 | } |
458 | |
459 | /* Append answer Resource Record */ |
460 | memcpy(answb, query_string, query_len); /* name, type, class */ |
461 | answb += query_len; |
462 | move_to_unaligned32((uint32_t *)answb, htonl(conf_ttl)); |
463 | answb += 4; |
464 | move_to_unaligned16((uint16_t *)answb, htons(outr_rlen)); |
465 | answb += 2; |
466 | memcpy(answb, answstr, outr_rlen); |
467 | answb += outr_rlen; |
468 | |
469 | /* QR = 1 "response", |
470 | * AA = 1 "Authoritative Answer", |
471 | * TODO: need to set RA bit 0x80? One user says nslookup complains |
472 | * "Got recursion not available from SERVER, trying next server" |
473 | * "** server can't find HOSTNAME" |
474 | * RCODE = 0 "success" |
475 | */ |
476 | if (OPT_verbose) |
477 | bb_error_msg("returning positive reply"); |
478 | outr_flags = htons(0x8000 | 0x0400 | 0); |
479 | /* we have one answer */ |
480 | head->nansw = htons(1); |
481 | |
482 | empty_packet: |
483 | if ((outr_flags & htons(0xf)) != 0) { /* not a positive response */ |
484 | if (OPT_verbose) { |
485 | bb_error_msg("%s, %s", |
486 | err_msg, |
487 | OPT_silent ? "dropping query" : "sending error reply" |
488 | ); |
489 | } |
490 | if (OPT_silent) |
491 | return 0; |
492 | } |
493 | head->flags |= outr_flags; |
494 | head->nauth = head->nadd = 0; |
495 | head->nquer = htons(1); // why??? |
496 | |
497 | return answb - buf; |
498 | } |
499 | |
500 | int dnsd_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; |
501 | int dnsd_main(int argc UNUSED_PARAM, char **argv) |
502 | { |
503 | const char *listen_interface = "0.0.0.0"; |
504 | const char *fileconf = "/etc/dnsd.conf"; |
505 | struct dns_entry *conf_data; |
506 | uint32_t conf_ttl = DEFAULT_TTL; |
507 | char *sttl, *sport; |
508 | len_and_sockaddr *lsa, *from, *to; |
509 | unsigned lsa_size; |
510 | int udps, opts; |
511 | uint16_t port = 53; |
512 | /* Ensure buf is 32bit aligned (we need 16bit, but 32bit can't hurt) */ |
513 | uint8_t buf[MAX_PACK_LEN + 1] ALIGN4; |
514 | |
515 | opts = getopt32(argv, "vsi:c:t:p:d", &listen_interface, &fileconf, &sttl, &sport); |
516 | //if (opts & (1 << 0)) // -v |
517 | //if (opts & (1 << 1)) // -s |
518 | //if (opts & (1 << 2)) // -i |
519 | //if (opts & (1 << 3)) // -c |
520 | if (opts & (1 << 4)) // -t |
521 | conf_ttl = xatou_range(sttl, 1, 0xffffffff); |
522 | if (opts & (1 << 5)) // -p |
523 | port = xatou_range(sport, 1, 0xffff); |
524 | if (opts & (1 << 6)) { // -d |
525 | bb_daemonize_or_rexec(DAEMON_CLOSE_EXTRA_FDS, argv); |
526 | openlog(applet_name, LOG_PID, LOG_DAEMON); |
527 | logmode = LOGMODE_SYSLOG; |
528 | } |
529 | |
530 | conf_data = parse_conf_file(fileconf); |
531 | |
532 | lsa = xdotted2sockaddr(listen_interface, port); |
533 | udps = xsocket(lsa->u.sa.sa_family, SOCK_DGRAM, 0); |
534 | xbind(udps, &lsa->u.sa, lsa->len); |
535 | socket_want_pktinfo(udps); /* needed for recv_from_to to work */ |
536 | lsa_size = LSA_LEN_SIZE + lsa->len; |
537 | from = xzalloc(lsa_size); |
538 | to = xzalloc(lsa_size); |
539 | |
540 | { |
541 | char *p = xmalloc_sockaddr2dotted(&lsa->u.sa); |
542 | bb_error_msg("accepting UDP packets on %s", p); |
543 | free(p); |
544 | } |
545 | |
546 | while (1) { |
547 | int r; |
548 | /* Try to get *DEST* address (to which of our addresses |
549 | * this query was directed), and reply from the same address. |
550 | * Or else we can exhibit usual UDP ugliness: |
551 | * [ip1.multihomed.ip2] <= query to ip1 <= peer |
552 | * [ip1.multihomed.ip2] => reply from ip2 => peer (confused) */ |
553 | memcpy(to, lsa, lsa_size); |
554 | r = recv_from_to(udps, buf, MAX_PACK_LEN + 1, 0, &from->u.sa, &to->u.sa, lsa->len); |
555 | if (r < 12 || r > MAX_PACK_LEN) { |
556 | bb_error_msg("packet size %d, ignored", r); |
557 | continue; |
558 | } |
559 | if (OPT_verbose) |
560 | bb_error_msg("got UDP packet"); |
561 | buf[r] = '\0'; /* paranoia */ |
562 | r = process_packet(conf_data, conf_ttl, buf); |
563 | if (r <= 0) |
564 | continue; |
565 | send_to_from(udps, buf, r, 0, &from->u.sa, &to->u.sa, lsa->len); |
566 | } |
567 | return 0; |
568 | } |
569 |