?  search:
summary | log | graphiclog1 | graphiclog2 | commit | commitdiff | tree | refs | edit | fork
blame | history | raw | HEAD
Kernel - Fix NOTE_EXIT.
[dragonfly.git] / contrib / libevent / evdns.c
blob1fc2075a4cf80efad12639a5c540644374bf1253
1 /* $Id: evdns.c 6979 2006-08-04 18:31:13Z nickm $ */
2
3 /* The original version of this module was written by Adam Langley; for
4 * a history of modifications, check out the subversion logs.
5 *
6 * When editing this module, try to keep it re-mergeable by Adam. Don't
7 * reformat the whitespace, add Tor dependencies, or so on.
8 *
9 * TODO:
10 * - Support IPv6 and PTR records.
11 * - Replace all externally visible magic numbers with #defined constants.
12 * - Write doccumentation for APIs of all external functions.
13 */
14
15 /* Async DNS Library
16 * Adam Langley <agl@imperialviolet.org>
17 * http://www.imperialviolet.org/eventdns.html
18 * Public Domain code
19 *
20 * This software is Public Domain. To view a copy of the public domain dedication,
21 * visit http://creativecommons.org/licenses/publicdomain/ or send a letter to
22 * Creative Commons, 559 Nathan Abbott Way, Stanford, California 94305, USA.
23 *
24 * I ask and expect, but do not require, that all derivative works contain an
25 * attribution similar to:
26 * Parts developed by Adam Langley <agl@imperialviolet.org>
27 *
28 * You may wish to replace the word "Parts" with something else depending on
29 * the amount of original code.
30 *
31 * (Derivative works does not include programs which link against, run or include
32 * the source verbatim in their source distributions)
33 *
34 * Version: 0.1b
35 */
36
37 #include <sys/types.h>
38 #ifdef HAVE_CONFIG_H
39 #include "config.h"
40 #endif
41
42 #ifdef WIN32
43 #include "misc.h"
44 #endif
45
46 /* #define NDEBUG */
47
48 #ifndef DNS_USE_CPU_CLOCK_FOR_ID
49 #ifndef DNS_USE_GETTIMEOFDAY_FOR_ID
50 #ifndef DNS_USE_OPENSSL_FOR_ID
51 #error Must configure at least one id generation method.
52 #error Please see the documentation.
53 #endif
54 #endif
55 #endif
56
57 /* #define _POSIX_C_SOURCE 200507 */
58 #define _GNU_SOURCE
59
60 #ifdef DNS_USE_CPU_CLOCK_FOR_ID
61 #ifdef DNS_USE_OPENSSL_FOR_ID
62 #error Multiple id options selected
63 #endif
64 #ifdef DNS_USE_GETTIMEOFDAY_FOR_ID
65 #error Multiple id options selected
66 #endif
67 #include <time.h>
68 #endif
69
70 #ifdef DNS_USE_OPENSSL_FOR_ID
71 #ifdef DNS_USE_GETTIMEOFDAY_FOR_ID
72 #error Multiple id options selected
73 #endif
74 #include <openssl/rand.h>
75 #endif
76
77 #define _FORTIFY_SOURCE 3
78
79 #include <string.h>
80 #include <fcntl.h>
81 #include <sys/time.h>
82 #ifdef HAVE_STDINT_H
83 #include <stdint.h>
84 #endif
85 #include <stdlib.h>
86 #include <string.h>
87 #include <errno.h>
88 #include <assert.h>
89 #include <unistd.h>
90 #include <limits.h>
91 #include <sys/stat.h>
92 #include <ctype.h>
93 #include <stdio.h>
94 #include <stdarg.h>
95
96 #include "evdns.h"
97 #include "log.h"
98 #ifdef WIN32
99 #include <windows.h>
100 #include <winsock2.h>
101 #include <iphlpapi.h>
102 #else
103 #include <sys/socket.h>
104 #include <netinet/in.h>
105 #include <arpa/inet.h>
106 #endif
107
108 #ifdef HAVE_NETINET_IN6_H
109 #include <netinet/in6.h>
110 #endif
111
112 #ifdef WIN32
113 typedef int socklen_t;
114 #endif
115
116 #define EVDNS_LOG_DEBUG 0
117 #define EVDNS_LOG_WARN 1
118
119 #ifndef HOST_NAME_MAX
120 #define HOST_NAME_MAX 255
121 #endif
122
123 #ifndef NDEBUG
124 #include <stdio.h>
125 #endif
126
127 #undef MIN
128 #define MIN(a,b) ((a)<(b)?(a):(b))
129
130 #ifdef __USE_ISOC99B
131 /* libevent doesn't work without this */
132 typedef uint8_t u_char;
133 typedef unsigned int uint;
134 #endif
135 #include <event.h>
136
137 #define u64 uint64_t
138 #define u32 uint32_t
139 #define u16 uint16_t
140 #define u8 uint8_t
141
142 #define MAX_ADDRS 4 /* maximum number of addresses from a single packet */
143 /* which we bother recording */
144
145 #define TYPE_A EVDNS_TYPE_A
146 #define TYPE_CNAME 5
147 #define TYPE_PTR EVDNS_TYPE_PTR
148 #define TYPE_AAAA EVDNS_TYPE_AAAA
149
150 #define CLASS_INET EVDNS_CLASS_INET
151
152 struct request {
153 u8 *request; /* the dns packet data */
154 unsigned int request_len;
155 int reissue_count;
156 int tx_count; /* the number of times that this packet has been sent */
157 unsigned int request_type; /* TYPE_PTR or TYPE_A */
158 void *user_pointer; /* the pointer given to us for this request */
159 evdns_callback_type user_callback;
160 struct nameserver *ns; /* the server which we last sent it */
161
162 /* elements used by the searching code */
163 int search_index;
164 struct search_state *search_state;
165 char *search_origname; /* needs to be free()ed */
166 int search_flags;
167
168 /* these objects are kept in a circular list */
169 struct request *next, *prev;
170
171 struct event timeout_event;
172
173 u16 trans_id; /* the transaction id */
174 char request_appended; /* true if the request pointer is data which follows this struct */
175 char transmit_me; /* needs to be transmitted */
176 };
177
178 #ifndef HAVE_STRUCT_IN6_ADDR
179 struct in6_addr {
180 u8 s6_addr[16];
181 };
182 #endif
183
184 struct reply {
185 unsigned int type;
186 unsigned int have_answer;
187 union {
188 struct {
189 u32 addrcount;
190 u32 addresses[MAX_ADDRS];
191 } a;
192 struct {
193 u32 addrcount;
194 struct in6_addr addresses[MAX_ADDRS];
195 } aaaa;
196 struct {
197 char name[HOST_NAME_MAX];
198 } ptr;
199 } data;
200 };
201
202 struct nameserver {
203 int socket; /* a connected UDP socket */
204 u32 address;
205 int failed_times; /* number of times which we have given this server a chance */
206 int timedout; /* number of times in a row a request has timed out */
207 struct event event;
208 /* these objects are kept in a circular list */
209 struct nameserver *next, *prev;
210 struct event timeout_event; /* used to keep the timeout for */
211 /* when we next probe this server. */
212 /* Valid if state == 0 */
213 char state; /* zero if we think that this server is down */
214 char choked; /* true if we have an EAGAIN from this server's socket */
215 char write_waiting; /* true if we are waiting for EV_WRITE events */
216 };
217
218 static struct request *req_head = NULL, *req_waiting_head = NULL;
219 static struct nameserver *server_head = NULL;
220
221 /* Represents a local port where we're listening for DNS requests. Right now, */
222 /* only UDP is supported. */
223 struct evdns_server_port {
224 int socket; /* socket we use to read queries and write replies. */
225 int refcnt; /* reference count. */
226 char choked; /* Are we currently blocked from writing? */
227 char closing; /* Are we trying to close this port, pending writes? */
228 evdns_request_callback_fn_type user_callback; /* Fn to handle requests */
229 void *user_data; /* Opaque pointer passed to user_callback */
230 struct event event; /* Read/write event */
231 /* circular list of replies that we want to write. */
232 struct server_request *pending_replies;
233 };
234
235 /* Represents part of a reply being built. (That is, a single RR.) */
236 struct server_reply_item {
237 struct server_reply_item *next; /* next item in sequence. */
238 char *name; /* name part of the RR */
239 u16 type : 16; /* The RR type */
240 u16 class : 16; /* The RR class (usually CLASS_INET) */
241 u32 ttl; /* The RR TTL */
242 char is_name; /* True iff data is a label */
243 u16 datalen; /* Length of data; -1 if data is a label */
244 void *data; /* The contents of the RR */
245 };
246
247 /* Represents a request that we've received as a DNS server, and holds */
248 /* the components of the reply as we're constructing it. */
249 struct server_request {
250 /* Pointers to the next and previous entries on the list of replies */
251 /* that we're waiting to write. Only set if we have tried to respond */
252 /* and gotten EAGAIN. */
253 struct server_request *next_pending;
254 struct server_request *prev_pending;
255
256 u16 trans_id; /* Transaction id. */
257 struct evdns_server_port *port; /* Which port received this request on? */
258 struct sockaddr_storage addr; /* Where to send the response */
259 socklen_t addrlen; /* length of addr */
260
261 int n_answer; /* how many answer RRs have been set? */
262 int n_authority; /* how many authority RRs have been set? */
263 int n_additional; /* how many additional RRs have been set? */
264
265 struct server_reply_item *answer; /* linked list of answer RRs */
266 struct server_reply_item *authority; /* linked list of authority RRs */
267 struct server_reply_item *additional; /* linked list of additional RRs */
268
269 /* Constructed response. Only set once we're ready to send a reply. */
270 /* Once this is set, the RR fields are cleared, and no more should be set. */
271 char *response;
272 size_t response_len;
273
274 /* Caller-visible fields: flags, questions. */
275 struct evdns_server_request base;
276 };
277
278 /* helper macro */
279 #define OFFSET_OF(st, member) ((off_t) (((char*)&((st*)0)->member)-(char*)0))
280
281 /* Given a pointer to an evdns_server_request, get the corresponding */
282 /* server_request. */
283 #define TO_SERVER_REQUEST(base_ptr) \
284 ((struct server_request*) \
285 (((char*)(base_ptr) - OFFSET_OF(struct server_request, base))))
286
287 /* The number of good nameservers that we have */
288 static int global_good_nameservers = 0;
289
290 /* inflight requests are contained in the req_head list */
291 /* and are actually going out across the network */
292 static int global_requests_inflight = 0;
293 /* requests which aren't inflight are in the waiting list */
294 /* and are counted here */
295 static int global_requests_waiting = 0;
296
297 static int global_max_requests_inflight = 64;
298
299 static struct timeval global_timeout = {5, 0}; /* 5 seconds */
300 static int global_max_reissues = 1; /* a reissue occurs when we get some errors from the server */
301 static int global_max_retransmits = 3; /* number of times we'll retransmit a request which timed out */
302 /* number of timeouts in a row before we consider this server to be down */
303 static int global_max_nameserver_timeout = 3;
304
305 /* These are the timeout values for nameservers. If we find a nameserver is down */
306 /* we try to probe it at intervals as given below. Values are in seconds. */
307 static const struct timeval global_nameserver_timeouts[] = {{10, 0}, {60, 0}, {300, 0}, {900, 0}, {3600, 0}};
308 static const int global_nameserver_timeouts_length = sizeof(global_nameserver_timeouts)/sizeof(struct timeval);
309
310 static struct nameserver *nameserver_pick(void);
311 static void evdns_request_insert(struct request *req, struct request **head);
312 static void nameserver_ready_callback(int fd, short events, void *arg);
313 static int evdns_transmit(void);
314 static int evdns_request_transmit(struct request *req);
315 static void nameserver_send_probe(struct nameserver *const ns);
316 static void search_request_finished(struct request *const);
317 static int search_try_next(struct request *const req);
318 static int search_request_new(int type, const char *const name, int flags, evdns_callback_type user_callback, void *user_arg);
319 static void evdns_requests_pump_waiting_queue(void);
320 static u16 transaction_id_pick(void);
321 static struct request *request_new(int type, const char *name, int flags, evdns_callback_type callback, void *ptr);
322 static void request_submit(struct request *req);
323
324 static int server_request_free(struct server_request *req);
325 static void server_request_free_answers(struct server_request *req);
326 static void server_port_free(struct evdns_server_port *port);
327 static void server_port_ready_callback(int fd, short events, void *arg);
328
329 static int strtoint(const char *const str);
330
331 #ifdef WIN32
332 static int
333 last_error(int sock)
334 {
335 int optval, optvallen=sizeof(optval);
336 int err = WSAGetLastError();
337 if (err == WSAEWOULDBLOCK && sock >= 0) {
338 if (getsockopt(sock, SOL_SOCKET, SO_ERROR, (void*)&optval,
339 &optvallen))
340 return err;
341 if (optval)
342 return optval;
343 }
344 return err;
345
346 }
347 static int
348 error_is_eagain(int err)
349 {
350 return err == EAGAIN || err == WSAEWOULDBLOCK;
351 }
352 static int
353 inet_aton(const char *c, struct in_addr *addr)
354 {
355 uint32_t r;
356 if (strcmp(c, "255.255.255.255") == 0) {
357 addr->s_addr = 0xffffffffu;
358 } else {
359 r = inet_addr(c);
360 if (r == INADDR_NONE)
361 return 0;
362 addr->s_addr = r;
363 }
364 return 1;
365 }
366 #define CLOSE_SOCKET(x) closesocket(x)
367 #else
368 #define last_error(sock) (errno)
369 #define error_is_eagain(err) ((err) == EAGAIN)
370 #define CLOSE_SOCKET(x) close(x)
371 #endif
372
373 #define ISSPACE(c) isspace((int)(unsigned char)(c))
374 #define ISDIGIT(c) isdigit((int)(unsigned char)(c))
375
376 #ifndef NDEBUG
377 static const char *
378 debug_ntoa(u32 address)
379 {
380 static char buf[32];
381 u32 a = ntohl(address);
382 snprintf(buf, sizeof(buf), "%d.%d.%d.%d",
383 (int)(u8)((a>>24)&0xff),
384 (int)(u8)((a>>16)&0xff),
385 (int)(u8)((a>>8 )&0xff),
386 (int)(u8)((a )&0xff));
387 return buf;
388 }
389 #endif
390
391 static evdns_debug_log_fn_type evdns_log_fn = NULL;
392
393 void
394 evdns_set_log_fn(evdns_debug_log_fn_type fn)
395 {
396 evdns_log_fn = fn;
397 }
398
399 #ifdef __GNUC__
400 #define EVDNS_LOG_CHECK __attribute__ ((format(printf, 2, 3)))
401 #else
402 #define EVDNS_LOG_CHECK
403 #endif
404
405 static void _evdns_log(int warn, const char *fmt, ...) EVDNS_LOG_CHECK;
406 static void
407 _evdns_log(int warn, const char *fmt, ...)
408 {
409 va_list args;
410 static char buf[512];
411 if (!evdns_log_fn)
412 return;
413 va_start(args,fmt);
414 #ifdef WIN32
415 _vsnprintf(buf, sizeof(buf), fmt, args);
416 #else
417 vsnprintf(buf, sizeof(buf), fmt, args);
418 #endif
419 buf[sizeof(buf)-1] = '\0';
420 evdns_log_fn(warn, buf);
421 va_end(args);
422 }
423
424 #define log _evdns_log
425
426 /* This walks the list of inflight requests to find the */
427 /* one with a matching transaction id. Returns NULL on */
428 /* failure */
429 static struct request *
430 request_find_from_trans_id(u16 trans_id) {
431 struct request *req = req_head, *const started_at = req_head;
432
433 if (req) {
434 do {
435 if (req->trans_id == trans_id) return req;
436 req = req->next;
437 } while (req != started_at);
438 }
439
440 return NULL;
441 }
442
443 /* a libevent callback function which is called when a nameserver */
444 /* has gone down and we want to test if it has came back to life yet */
445 static void
446 nameserver_prod_callback(int fd, short events, void *arg) {
447 struct nameserver *const ns = (struct nameserver *) arg;
448 (void)fd;
449 (void)events;
450
451 nameserver_send_probe(ns);
452 }
453
454 /* a libevent callback which is called when a nameserver probe (to see if */
455 /* it has come back to life) times out. We increment the count of failed_times */
456 /* and wait longer to send the next probe packet. */
457 static void
458 nameserver_probe_failed(struct nameserver *const ns) {
459 const struct timeval * timeout;
460 (void) evtimer_del(&ns->timeout_event);
461 if (ns->state == 1) {
462 /* This can happen if the nameserver acts in a way which makes us mark */
463 /* it as bad and then starts sending good replies. */
464 return;
465 }
466
467 timeout =
468 &global_nameserver_timeouts[MIN(ns->failed_times,
469 global_nameserver_timeouts_length - 1)];
470 ns->failed_times++;
471
472 evtimer_set(&ns->timeout_event, nameserver_prod_callback, ns);
473 if (evtimer_add(&ns->timeout_event, (struct timeval *) timeout) < 0) {
474 log(EVDNS_LOG_WARN,
475 "Error from libevent when adding timer event for %s",
476 debug_ntoa(ns->address));
477 /* ???? Do more? */
478 }
479 }
480
481 /* called when a nameserver has been deemed to have failed. For example, too */
482 /* many packets have timed out etc */
483 static void
484 nameserver_failed(struct nameserver *const ns, const char *msg) {
485 struct request *req, *started_at;
486 /* if this nameserver has already been marked as failed */
487 /* then don't do anything */
488 if (!ns->state) return;
489
490 log(EVDNS_LOG_WARN, "Nameserver %s has failed: %s",
491 debug_ntoa(ns->address), msg);
492 global_good_nameservers--;
493 assert(global_good_nameservers >= 0);
494 if (global_good_nameservers == 0) {
495 log(EVDNS_LOG_WARN, "All nameservers have failed");
496 }
497
498 ns->state = 0;
499 ns->failed_times = 1;
500
501 evtimer_set(&ns->timeout_event, nameserver_prod_callback, ns);
502 if (evtimer_add(&ns->timeout_event, (struct timeval *) &global_nameserver_timeouts[0]) < 0) {
503 log(EVDNS_LOG_WARN,
504 "Error from libevent when adding timer event for %s",
505 debug_ntoa(ns->address));
506 /* ???? Do more? */
507 }
508
509 /* walk the list of inflight requests to see if any can be reassigned to */
510 /* a different server. Requests in the waiting queue don't have a */
511 /* nameserver assigned yet */
512
513 /* if we don't have *any* good nameservers then there's no point */
514 /* trying to reassign requests to one */
515 if (!global_good_nameservers) return;
516
517 req = req_head;
518 started_at = req_head;
519 if (req) {
520 do {
521 if (req->tx_count == 0 && req->ns == ns) {
522 /* still waiting to go out, can be moved */
523 /* to another server */
524 req->ns = nameserver_pick();
525 }
526 req = req->next;
527 } while (req != started_at);
528 }
529 }
530
531 static void
532 nameserver_up(struct nameserver *const ns) {
533 if (ns->state) return;
534 log(EVDNS_LOG_WARN, "Nameserver %s is back up",
535 debug_ntoa(ns->address));
536 evtimer_del(&ns->timeout_event);
537 ns->state = 1;
538 ns->failed_times = 0;
539 ns->timedout = 0;
540 global_good_nameservers++;
541 }
542
543 static void
544 request_trans_id_set(struct request *const req, const u16 trans_id) {
545 req->trans_id = trans_id;
546 *((u16 *) req->request) = htons(trans_id);
547 }
548
549 /* Called to remove a request from a list and dealloc it. */
550 /* head is a pointer to the head of the list it should be */
551 /* removed from or NULL if the request isn't in a list. */
552 static void
553 request_finished(struct request *const req, struct request **head) {
554 if (head) {
555 if (req->next == req) {
556 /* only item in the list */
557 *head = NULL;
558 } else {
559 req->next->prev = req->prev;
560 req->prev->next = req->next;
561 if (*head == req) *head = req->next;
562 }
563 }
564
565 log(EVDNS_LOG_DEBUG, "Removing timeout for request %lx",
566 (unsigned long) req);
567 evtimer_del(&req->timeout_event);
568
569 search_request_finished(req);
570 global_requests_inflight--;
571
572 if (!req->request_appended) {
573 /* need to free the request data on it's own */
574 free(req->request);
575 } else {
576 /* the request data is appended onto the header */
577 /* so everything gets free()ed when we: */
578 }
579
580 free(req);
581
582 evdns_requests_pump_waiting_queue();
583 }
584
585 /* This is called when a server returns a funny error code. */
586 /* We try the request again with another server. */
587 /* */
588 /* return: */
589 /* 0 ok */
590 /* 1 failed/reissue is pointless */
591 static int
592 request_reissue(struct request *req) {
593 const struct nameserver *const last_ns = req->ns;
594 /* the last nameserver should have been marked as failing */
595 /* by the caller of this function, therefore pick will try */
596 /* not to return it */
597 req->ns = nameserver_pick();
598 if (req->ns == last_ns) {
599 /* ... but pick did return it */
600 /* not a lot of point in trying again with the */
601 /* same server */
602 return 1;
603 }
604
605 req->reissue_count++;
606 req->tx_count = 0;
607 req->transmit_me = 1;
608
609 return 0;
610 }
611
612 /* this function looks for space on the inflight queue and promotes */
613 /* requests from the waiting queue if it can. */
614 static void
615 evdns_requests_pump_waiting_queue(void) {
616 while (global_requests_inflight < global_max_requests_inflight &&
617 global_requests_waiting) {
618 struct request *req;
619 /* move a request from the waiting queue to the inflight queue */
620 assert(req_waiting_head);
621 if (req_waiting_head->next == req_waiting_head) {
622 /* only one item in the queue */
623 req = req_waiting_head;
624 req_waiting_head = NULL;
625 } else {
626 req = req_waiting_head;
627 req->next->prev = req->prev;
628 req->prev->next = req->next;
629 req_waiting_head = req->next;
630 }
631
632 global_requests_waiting--;
633 global_requests_inflight++;
634
635 req->ns = nameserver_pick();
636 request_trans_id_set(req, transaction_id_pick());
637
638 evdns_request_insert(req, &req_head);
639 evdns_request_transmit(req);
640 evdns_transmit();
641 }
642 }
643
644 static void
645 reply_callback(struct request *const req, u32 ttl, u32 err, struct reply *reply) {
646 switch (req->request_type) {
647 case TYPE_A:
648 if (reply)
649 req->user_callback(DNS_ERR_NONE, DNS_IPv4_A,
650 reply->data.a.addrcount, ttl,
651 reply->data.a.addresses,
652 req->user_pointer);
653 else
654 req->user_callback(err, 0, 0, 0, NULL, req->user_pointer);
655 return;
656 case TYPE_PTR:
657 if (reply) {
658 char *name = reply->data.ptr.name;
659 req->user_callback(DNS_ERR_NONE, DNS_PTR, 1, ttl,
660 &name, req->user_pointer);
661 } else {
662 req->user_callback(err, 0, 0, 0, NULL,
663 req->user_pointer);
664 }
665 return;
666 case TYPE_AAAA:
667 if (reply)
668 req->user_callback(DNS_ERR_NONE, DNS_IPv6_AAAA,
669 reply->data.aaaa.addrcount, ttl,
670 reply->data.aaaa.addresses,
671 req->user_pointer);
672 else
673 req->user_callback(err, 0, 0, 0, NULL, req->user_pointer);
674 return;
675 }
676 assert(0);
677 }
678
679 /* this processes a parsed reply packet */
680 static void
681 reply_handle(struct request *const req, u16 flags, u32 ttl, struct reply *reply) {
682 int error;
683 static const int error_codes[] = {DNS_ERR_FORMAT, DNS_ERR_SERVERFAILED, DNS_ERR_NOTEXIST, DNS_ERR_NOTIMPL, DNS_ERR_REFUSED};
684
685 if (flags & 0x020f || !reply || !reply->have_answer) {
686 /* there was an error */
687 if (flags & 0x0200) {
688 error = DNS_ERR_TRUNCATED;
689 } else {
690 u16 error_code = (flags & 0x000f) - 1;
691 if (error_code > 4) {
692 error = DNS_ERR_UNKNOWN;
693 } else {
694 error = error_codes[error_code];
695 }
696 }
697
698 switch(error) {
699 case DNS_ERR_NOTIMPL:
700 case DNS_ERR_REFUSED:
701 /* we regard these errors as marking a bad nameserver */
702 if (req->reissue_count < global_max_reissues) {
703 char msg[64];
704 snprintf(msg, sizeof(msg), "Bad response %d (%s)",
705 error, evdns_err_to_string(error));
706 nameserver_failed(req->ns, msg);
707 if (!request_reissue(req)) return;
708 }
709 break;
710 case DNS_ERR_SERVERFAILED:
711 /* rcode 2 (servfailed) sometimes means "we are broken" and
712 * sometimes (with some binds) means "that request was very
713 * confusing." Treat this as a timeout, not a failure.
714 */
715 log(EVDNS_LOG_DEBUG, "Got a SERVERFAILED from nameserver %s; "
716 "will allow the request to time out.",
717 debug_ntoa(req->ns->address));
718 break;
719 default:
720 /* we got a good reply from the nameserver */
721 nameserver_up(req->ns);
722 }
723
724 if (req->search_state && req->request_type != TYPE_PTR) {
725 /* if we have a list of domains to search in, try the next one */
726 if (!search_try_next(req)) {
727 /* a new request was issued so this request is finished and */
728 /* the user callback will be made when that request (or a */
729 /* child of it) finishes. */
730 request_finished(req, &req_head);
731 return;
732 }
733 }
734
735 /* all else failed. Pass the failure up */
736 reply_callback(req, 0, error, NULL);
737 request_finished(req, &req_head);
738 } else {
739 /* all ok, tell the user */
740 reply_callback(req, ttl, 0, reply);
741 nameserver_up(req->ns);
742 request_finished(req, &req_head);
743 }
744 }
745
746 static int
747 name_parse(u8 *packet, int length, int *idx, char *name_out, int name_out_len) {
748 int name_end = -1;
749 int j = *idx;
750 int ptr_count = 0;
751 #define GET32(x) do { if (j + 4 > length) goto err; memcpy(&_t32, packet + j, 4); j += 4; x = ntohl(_t32); } while(0)
752 #define GET16(x) do { if (j + 2 > length) goto err; memcpy(&_t, packet + j, 2); j += 2; x = ntohs(_t); } while(0)
753 #define GET8(x) do { if (j >= length) goto err; x = packet[j++]; } while(0)
754
755 char *cp = name_out;
756 const char *const end = name_out + name_out_len;
757
758 /* Normally, names are a series of length prefixed strings terminated */
759 /* with a length of 0 (the lengths are u8's < 63). */
760 /* However, the length can start with a pair of 1 bits and that */
761 /* means that the next 14 bits are a pointer within the current */
762 /* packet. */
763
764 for(;;) {
765 u8 label_len;
766 if (j >= length) return -1;
767 GET8(label_len);
768 if (!label_len) break;
769 if (label_len & 0xc0) {
770 u8 ptr_low;
771 GET8(ptr_low);
772 if (name_end < 0) name_end = j;
773 j = (((int)label_len & 0x3f) << 8) + ptr_low;
774 /* Make sure that the target offset is in-bounds. */
775 if (j < 0 || j >= length) return -1;
776 /* If we've jumped more times than there are characters in the
777 * message, we must have a loop. */
778 if (++ptr_count > length) return -1;
779 continue;
780 }
781 if (label_len > 63) return -1;
782 if (cp != name_out) {
783 if (cp + 1 >= end) return -1;
784 *cp++ = '.';
785 }
786 if (cp + label_len >= end) return -1;
787 memcpy(cp, packet + j, label_len);
788 cp += label_len;
789 j += label_len;
790 }
791 if (cp >= end) return -1;
792 *cp = '\0';
793 if (name_end < 0)
794 *idx = j;
795 else
796 *idx = name_end;
797 return 0;
798 err:
799 return -1;
800 }
801
802 /* parses a raw request from a nameserver */
803 static int
804 reply_parse(u8 *packet, int length) {
805 int j = 0; /* index into packet */
806 u16 _t; /* used by the macros */
807 u32 _t32; /* used by the macros */
808 char tmp_name[256]; /* used by the macros */
809
810 u16 trans_id, questions, answers, authority, additional, datalength;
811 u16 flags = 0;
812 u32 ttl, ttl_r = 0xffffffff;
813 struct reply reply;
814 struct request *req = NULL;
815 unsigned int i;
816
817 GET16(trans_id);
818 GET16(flags);
819 GET16(questions);
820 GET16(answers);
821 GET16(authority);
822 GET16(additional);
823 (void) authority; /* suppress "unused variable" warnings. */
824 (void) additional; /* suppress "unused variable" warnings. */
825
826 req = request_find_from_trans_id(trans_id);
827 if (!req) return -1;
828
829 memset(&reply, 0, sizeof(reply));
830
831 /* If it's not an answer, it doesn't correspond to any request. */
832 if (!(flags & 0x8000)) return -1; /* must be an answer */
833 if (flags & 0x020f) {
834 /* there was an error */
835 goto err;
836 }
837 /* if (!answers) return; */ /* must have an answer of some form */
838
839 /* This macro skips a name in the DNS reply. */
840 #define SKIP_NAME \
841 do { tmp_name[0] = '\0'; \
842 if (name_parse(packet, length, &j, tmp_name, sizeof(tmp_name))<0) \
843 goto err; \
844 } while(0);
845
846 reply.type = req->request_type;
847
848 /* skip over each question in the reply */
849 for (i = 0; i < questions; ++i) {
850 /* the question looks like
851 * <label:name><u16:type><u16:class>
852 */
853 SKIP_NAME;
854 j += 4;
855 if (j >= length) goto err;
856 }
857
858 /* now we have the answer section which looks like
859 * <label:name><u16:type><u16:class><u32:ttl><u16:len><data...>
860 */
861
862 for (i = 0; i < answers; ++i) {
863 u16 type, class;
864
865 SKIP_NAME;
866 GET16(type);
867 GET16(class);
868 GET32(ttl);
869 GET16(datalength);
870
871 if (type == TYPE_A && class == CLASS_INET) {
872 int addrcount, addrtocopy;
873 if (req->request_type != TYPE_A) {
874 j += datalength; continue;
875 }
876 if ((datalength & 3) != 0) /* not an even number of As. */
877 goto err;
878 addrcount = datalength >> 2;
879 addrtocopy = MIN(MAX_ADDRS - reply.data.a.addrcount, (unsigned)addrcount);
880
881 ttl_r = MIN(ttl_r, ttl);
882 /* we only bother with the first four addresses. */
883 if (j + 4*addrtocopy > length) goto err;
884 memcpy(&reply.data.a.addresses[reply.data.a.addrcount],
885 packet + j, 4*addrtocopy);
886 j += 4*addrtocopy;
887 reply.data.a.addrcount += addrtocopy;
888 reply.have_answer = 1;
889 if (reply.data.a.addrcount == MAX_ADDRS) break;
890 } else if (type == TYPE_PTR && class == CLASS_INET) {
891 if (req->request_type != TYPE_PTR) {
892 j += datalength; continue;
893 }
894 if (name_parse(packet, length, &j, reply.data.ptr.name,
895 sizeof(reply.data.ptr.name))<0)
896 goto err;
897 ttl_r = MIN(ttl_r, ttl);
898 reply.have_answer = 1;
899 break;
900 } else if (type == TYPE_AAAA && class == CLASS_INET) {
901 int addrcount, addrtocopy;
902 if (req->request_type != TYPE_AAAA) {
903 j += datalength; continue;
904 }
905 if ((datalength & 15) != 0) /* not an even number of AAAAs. */
906 goto err;
907 addrcount = datalength >> 4; /* each address is 16 bytes long */
908 addrtocopy = MIN(MAX_ADDRS - reply.data.aaaa.addrcount, (unsigned)addrcount);
909 ttl_r = MIN(ttl_r, ttl);
910
911 /* we only bother with the first four addresses. */
912 if (j + 16*addrtocopy > length) goto err;
913 memcpy(&reply.data.aaaa.addresses[reply.data.aaaa.addrcount],
914 packet + j, 16*addrtocopy);
915 reply.data.aaaa.addrcount += addrtocopy;
916 j += 16*addrtocopy;
917 reply.have_answer = 1;
918 if (reply.data.aaaa.addrcount == MAX_ADDRS) break;
919 } else {
920 /* skip over any other type of resource */
921 j += datalength;
922 }
923 }
924
925 reply_handle(req, flags, ttl_r, &reply);
926 return 0;
927 err:
928 if (req)
929 reply_handle(req, flags, 0, NULL);
930 return -1;
931 }
932
933 /* Parse a raw request (packet,length) sent to a nameserver port (port) from */
934 /* a DNS client (addr,addrlen), and if it's well-formed, call the corresponding */
935 /* callback. */
936 static int
937 request_parse(u8 *packet, int length, struct evdns_server_port *port, struct sockaddr *addr, socklen_t addrlen)
938 {
939 int j = 0; /* index into packet */
940 u16 _t; /* used by the macros */
941 char tmp_name[256]; /* used by the macros */
942
943 int i;
944 u16 trans_id, flags, questions, answers, authority, additional;
945 struct server_request *server_req = NULL;
946
947 /* Get the header fields */
948 GET16(trans_id);
949 GET16(flags);
950 GET16(questions);
951 GET16(answers);
952 GET16(authority);
953 GET16(additional);
954
955 if (flags & 0x8000) return -1; /* Must not be an answer. */
956 if (flags & 0x7800) return -1; /* only standard queries are supported */
957 flags &= 0x0300; /* Only TC and RD get preserved. */
958
959 server_req = malloc(sizeof(struct server_request));
960 if (server_req == NULL) return -1;
961 memset(server_req, 0, sizeof(struct server_request));
962
963 server_req->trans_id = trans_id;
964 memcpy(&server_req->addr, addr, addrlen);
965 server_req->addrlen = addrlen;
966
967 server_req->base.flags = flags;
968 server_req->base.nquestions = 0;
969 server_req->base.questions = malloc(sizeof(struct evdns_server_question *) * questions);
970 if (server_req->base.questions == NULL)
971 goto err;
972
973 for (i = 0; i < questions; ++i) {
974 u16 type, class;
975 struct evdns_server_question *q;
976 int namelen;
977 if (name_parse(packet, length, &j, tmp_name, sizeof(tmp_name))<0)
978 goto err;
979 GET16(type);
980 GET16(class);
981 namelen = strlen(tmp_name);
982 q = malloc(sizeof(struct evdns_server_question) + namelen);
983 if (!q)
984 goto err;
985 q->type = type;
986 q->class = class;
987 memcpy(q->name, tmp_name, namelen+1);
988 server_req->base.questions[server_req->base.nquestions++] = q;
989 }
990
991 /* Ignore answers, authority, and additional. */
992
993 server_req->port = port;
994 port->refcnt++;
995 port->user_callback(&(server_req->base), port->user_data);
996
997 return 0;
998 err:
999 if (server_req) {
1000 if (server_req->base.questions) {
1001 for (i = 0; i < server_req->base.nquestions; ++i)
1002 free(server_req->base.questions[i]);
1003 free(server_req->base.questions);
1004 }
1005 free(server_req);
1006 }
1007 return -1;
1008
1009 #undef SKIP_NAME
1010 #undef GET32
1011 #undef GET16
1012 #undef GET8
1013 }
1014
1015 /* Try to choose a strong transaction id which isn't already in flight */
1016 static u16
1017 transaction_id_pick(void) {
1018 for (;;) {
1019 const struct request *req = req_head, *started_at;
1020 #ifdef DNS_USE_CPU_CLOCK_FOR_ID
1021 struct timespec ts;
1022 u16 trans_id;
1023 #ifdef CLOCK_MONOTONIC
1024 if (clock_gettime(CLOCK_MONOTONIC, &ts) == -1)
1025 #else
1026 if (clock_gettime(CLOCK_REALTIME, &ts) == -1)
1027 #endif
1028 event_err(1, "clock_gettime");
1029 trans_id = ts.tv_nsec & 0xffff;
1030 #endif
1031
1032 #ifdef DNS_USE_GETTIMEOFDAY_FOR_ID
1033 struct timeval tv;
1034 u16 trans_id;
1035 gettimeofday(&tv, NULL);
1036 trans_id = tv.tv_usec & 0xffff;
1037 #endif
1038
1039 #ifdef DNS_USE_OPENSSL_FOR_ID
1040 u16 trans_id;
1041 if (RAND_pseudo_bytes((u8 *) &trans_id, 2) == -1) {
1042 /* in the case that the RAND call fails we back */
1043 /* down to using gettimeofday. */
1044 struct timeval tv;
1045 gettimeofday(&tv, NULL);
1046 trans_id = tv.tv_usec & 0xffff; */
1047 abort();
1048 }
1049 #endif
1050
1051 if (trans_id == 0xffff) continue;
1052 /* now check to see if that id is already inflight */
1053 req = started_at = req_head;
1054 if (req) {
1055 do {
1056 if (req->trans_id == trans_id) break;
1057 req = req->next;
1058 } while (req != started_at);
1059 }
1060 /* we didn't find it, so this is a good id */
1061 if (req == started_at) return trans_id;
1062 }
1063 }
1064
1065 /* choose a namesever to use. This function will try to ignore */
1066 /* nameservers which we think are down and load balance across the rest */
1067 /* by updating the server_head global each time. */
1068 static struct nameserver *
1069 nameserver_pick(void) {
1070 struct nameserver *started_at = server_head, *picked;
1071 if (!server_head) return NULL;
1072
1073 /* if we don't have any good nameservers then there's no */
1074 /* point in trying to find one. */
1075 if (!global_good_nameservers) {
1076 server_head = server_head->next;
1077 return server_head;
1078 }
1079
1080 /* remember that nameservers are in a circular list */
1081 for (;;) {
1082 if (server_head->state) {
1083 /* we think this server is currently good */
1084 picked = server_head;
1085 server_head = server_head->next;
1086 return picked;
1087 }
1088
1089 server_head = server_head->next;
1090 if (server_head == started_at) {
1091 /* all the nameservers seem to be down */
1092 /* so we just return this one and hope for the */
1093 /* best */
1094 assert(global_good_nameservers == 0);
1095 picked = server_head;
1096 server_head = server_head->next;
1097 return picked;
1098 }
1099 }
1100 }
1101
1102 /* this is called when a namesever socket is ready for reading */
1103 static void
1104 nameserver_read(struct nameserver *ns) {
1105 u8 packet[1500];
1106
1107 for (;;) {
1108 const int r = recv(ns->socket, packet, sizeof(packet), 0);
1109 if (r < 0) {
1110 int err = last_error(ns->socket);
1111 if (error_is_eagain(err)) return;
1112 nameserver_failed(ns, strerror(err));
1113 return;
1114 }
1115 ns->timedout = 0;
1116 reply_parse(packet, r);
1117 }
1118 }
1119
1120 /* Read a packet from a DNS client on a server port s, parse it, and */
1121 /* act accordingly. */
1122 static void
1123 server_port_read(struct evdns_server_port *s) {
1124 u8 packet[1500];
1125 struct sockaddr_storage addr;
1126 socklen_t addrlen;
1127 int r;
1128
1129 for (;;) {
1130 addrlen = sizeof(struct sockaddr_storage);
1131 r = recvfrom(s->socket, packet, sizeof(packet), 0,
1132 (struct sockaddr*) &addr, &addrlen);
1133 if (r < 0) {
1134 int err = last_error(s->socket);
1135 if (error_is_eagain(err)) return;
1136 log(EVDNS_LOG_WARN, "Error %s (%d) while reading request.",
1137 strerror(err), err);
1138 return;
1139 }
1140 request_parse(packet, r, s, (struct sockaddr*) &addr, addrlen);
1141 }
1142 }
1143
1144 /* Try to write all pending replies on a given DNS server port. */
1145 static void
1146 server_port_flush(struct evdns_server_port *port)
1147 {
1148 while (port->pending_replies) {
1149 struct server_request *req = port->pending_replies;
1150 int r = sendto(port->socket, req->response, req->response_len, 0,
1151 (struct sockaddr*) &req->addr, req->addrlen);
1152 if (r < 0) {
1153 int err = last_error(port->socket);
1154 if (error_is_eagain(err))
1155 return;
1156 log(EVDNS_LOG_WARN, "Error %s (%d) while writing response to port; dropping", strerror(err), err);
1157 }
1158 if (server_request_free(req)) {
1159 /* we released the last reference to req->port. */
1160 return;
1161 }
1162 }
1163
1164 /* We have no more pending requests; stop listening for 'writeable' events. */
1165 (void) event_del(&port->event);
1166 event_set(&port->event, port->socket, EV_READ | EV_PERSIST,
1167 server_port_ready_callback, port);
1168 if (event_add(&port->event, NULL) < 0) {
1169 log(EVDNS_LOG_WARN, "Error from libevent when adding event for DNS server.");
1170 /* ???? Do more? */
1171 }
1172 }
1173
1174 /* set if we are waiting for the ability to write to this server. */
1175 /* if waiting is true then we ask libevent for EV_WRITE events, otherwise */
1176 /* we stop these events. */
1177 static void
1178 nameserver_write_waiting(struct nameserver *ns, char waiting) {
1179 if (ns->write_waiting == waiting) return;
1180
1181 ns->write_waiting = waiting;
1182 (void) event_del(&ns->event);
1183 event_set(&ns->event, ns->socket, EV_READ | (waiting ? EV_WRITE : 0) | EV_PERSIST,
1184 nameserver_ready_callback, ns);
1185 if (event_add(&ns->event, NULL) < 0) {
1186 log(EVDNS_LOG_WARN, "Error from libevent when adding event for %s",
1187 debug_ntoa(ns->address));
1188 /* ???? Do more? */
1189 }
1190 }
1191
1192 /* a callback function. Called by libevent when the kernel says that */
1193 /* a nameserver socket is ready for writing or reading */
1194 static void
1195 nameserver_ready_callback(int fd, short events, void *arg) {
1196 struct nameserver *ns = (struct nameserver *) arg;
1197 (void)fd;
1198
1199 if (events & EV_WRITE) {
1200 ns->choked = 0;
1201 if (!evdns_transmit()) {
1202 nameserver_write_waiting(ns, 0);
1203 }
1204 }
1205 if (events & EV_READ) {
1206 nameserver_read(ns);
1207 }
1208 }
1209
1210 /* a callback function. Called by libevent when the kernel says that */
1211 /* a server socket is ready for writing or reading. */
1212 static void
1213 server_port_ready_callback(int fd, short events, void *arg) {
1214 struct evdns_server_port *port = (struct evdns_server_port *) arg;
1215 (void) fd;
1216
1217 if (events & EV_WRITE) {
1218 port->choked = 0;
1219 server_port_flush(port);
1220 }
1221 if (events & EV_READ) {
1222 server_port_read(port);
1223 }
1224 }
1225
1226 /* This is an inefficient representation; only use it via the dnslabel_table_*
1227 * functions, so that is can be safely replaced with something smarter later. */
1228 #define MAX_LABELS 128
1229 /* Structures used to implement name compression */
1230 struct dnslabel_entry { char *v; off_t pos; };
1231 struct dnslabel_table {
1232 int n_labels; /* number of current entries */
1233 /* map from name to position in message */
1234 struct dnslabel_entry labels[MAX_LABELS];
1235 };
1236
1237 /* Initialize dnslabel_table. */
1238 static void
1239 dnslabel_table_init(struct dnslabel_table *table)
1240 {
1241 table->n_labels = 0;
1242 }
1243
1244 /* Free all storage held by table, but not the table itself. */
1245 static void
1246 dnslabel_clear(struct dnslabel_table *table)
1247 {
1248 int i;
1249 for (i = 0; i < table->n_labels; ++i)
1250 free(table->labels[i].v);
1251 table->n_labels = 0;
1252 }
1253
1254 /* return the position of the label in the current message, or -1 if the label */
1255 /* hasn't been used yet. */
1256 static int
1257 dnslabel_table_get_pos(const struct dnslabel_table *table, const char *label)
1258 {
1259 int i;
1260 for (i = 0; i < table->n_labels; ++i) {
1261 if (!strcmp(label, table->labels[i].v))
1262 return table->labels[i].pos;
1263 }
1264 return -1;
1265 }
1266
1267 /* remember that we've used the label at position pos */
1268 static int
1269 dnslabel_table_add(struct dnslabel_table *table, const char *label, off_t pos)
1270 {
1271 char *v;
1272 int p;
1273 if (table->n_labels == MAX_LABELS)
1274 return (-1);
1275 v = strdup(label);
1276 if (v == NULL)
1277 return (-1);
1278 p = table->n_labels++;
1279 table->labels[p].v = v;
1280 table->labels[p].pos = pos;
1281
1282 return (0);
1283 }
1284
1285 /* Converts a string to a length-prefixed set of DNS labels, starting */
1286 /* at buf[j]. name and buf must not overlap. name_len should be the length */
1287 /* of name. table is optional, and is used for compression. */
1288 /* */
1289 /* Input: abc.def */
1290 /* Output: <3>abc<3>def<0> */
1291 /* */
1292 /* Returns the first index after the encoded name, or negative on error. */
1293 /* -1 label was > 63 bytes */
1294 /* -2 name too long to fit in buffer. */
1295 /* */
1296 static off_t
1297 dnsname_to_labels(u8 *const buf, size_t buf_len, off_t j,
1298 const char *name, const int name_len,
1299 struct dnslabel_table *table) {
1300 const char *end = name + name_len;
1301 int ref = 0;
1302 u16 _t;
1303
1304 #define APPEND16(x) do { \
1305 if (j + 2 > (off_t)buf_len) \
1306 goto overflow; \
1307 _t = htons(x); \
1308 memcpy(buf + j, &_t, 2); \
1309 j += 2; \
1310 } while (0)
1311 #define APPEND32(x) do { \
1312 if (j + 4 > (off_t)buf_len) \
1313 goto overflow; \
1314 _t32 = htonl(x); \
1315 memcpy(buf + j, &_t32, 4); \
1316 j += 4; \
1317 } while (0)
1318
1319 if (name_len > 255) return -2;
1320
1321 for (;;) {
1322 const char *const start = name;
1323 if (table && (ref = dnslabel_table_get_pos(table, name)) >= 0) {
1324 APPEND16(ref | 0xc000);
1325 return j;
1326 }
1327 name = strchr(name, '.');
1328 if (!name) {
1329 const unsigned int label_len = end - start;
1330 if (label_len > 63) return -1;
1331 if ((size_t)(j+label_len+1) > buf_len) return -2;
1332 if (table) dnslabel_table_add(table, start, j);
1333 buf[j++] = label_len;
1334
1335 memcpy(buf + j, start, end - start);
1336 j += end - start;
1337 break;
1338 } else {
1339 /* append length of the label. */
1340 const unsigned int label_len = name - start;
1341 if (label_len > 63) return -1;
1342 if ((size_t)(j+label_len+1) > buf_len) return -2;
1343 if (table) dnslabel_table_add(table, start, j);
1344 buf[j++] = label_len;
1345
1346 memcpy(buf + j, start, name - start);
1347 j += name - start;
1348 /* hop over the '.' */
1349 name++;
1350 }
1351 }
1352
1353 /* the labels must be terminated by a 0. */
1354 /* It's possible that the name ended in a . */
1355 /* in which case the zero is already there */
1356 if (!j || buf[j-1]) buf[j++] = 0;
1357 return j;
1358 overflow:
1359 return (-2);
1360 }
1361
1362 /* Finds the length of a dns request for a DNS name of the given */
1363 /* length. The actual request may be smaller than the value returned */
1364 /* here */
1365 static int
1366 evdns_request_len(const int name_len) {
1367 return 96 + /* length of the DNS standard header */
1368 name_len + 2 +
1369 4; /* space for the resource type */
1370 }
1371
1372 /* build a dns request packet into buf. buf should be at least as long */
1373 /* as evdns_request_len told you it should be. */
1374 /* */
1375 /* Returns the amount of space used. Negative on error. */
1376 static int
1377 evdns_request_data_build(const char *const name, const int name_len,
1378 const u16 trans_id, const u16 type, const u16 class,
1379 u8 *const buf, size_t buf_len) {
1380 off_t j = 0; /* current offset into buf */
1381 u16 _t; /* used by the macros */
1382
1383 APPEND16(trans_id);
1384 APPEND16(0x0100); /* standard query, recusion needed */
1385 APPEND16(1); /* one question */
1386 APPEND16(0); /* no answers */
1387 APPEND16(0); /* no authority */
1388 APPEND16(0); /* no additional */
1389
1390 j = dnsname_to_labels(buf, buf_len, j, name, name_len, NULL);
1391 if (j < 0) {
1392 return (int)j;
1393 }
1394
1395 APPEND16(type);
1396 APPEND16(class);
1397
1398 return (int)j;
1399 overflow:
1400 return (-1);
1401 }
1402
1403 /* exported function */
1404 struct evdns_server_port *
1405 evdns_add_server_port(int socket, int is_tcp, evdns_request_callback_fn_type cb, void *user_data)
1406 {
1407 struct evdns_server_port *port;
1408 if (!(port = malloc(sizeof(struct evdns_server_port))))
1409 return NULL;
1410 memset(port, 0, sizeof(struct evdns_server_port));
1411
1412 assert(!is_tcp); /* TCP sockets not yet implemented */
1413 port->socket = socket;
1414 port->refcnt = 1;
1415 port->choked = 0;
1416 port->closing = 0;
1417 port->user_callback = cb;
1418 port->user_data = user_data;
1419 port->pending_replies = NULL;
1420
1421 event_set(&port->event, port->socket, EV_READ | EV_PERSIST,
1422 server_port_ready_callback, port);
1423 event_add(&port->event, NULL); /* check return. */
1424 return port;
1425 }
1426
1427 /* exported function */
1428 void
1429 evdns_close_server_port(struct evdns_server_port *port)
1430 {
1431 if (--port->refcnt == 0)
1432 server_port_free(port);
1433 port->closing = 1;
1434 }
1435
1436 /* exported function */
1437 int
1438 evdns_server_request_add_reply(struct evdns_server_request *_req, int section, const char *name, int type, int class, int ttl, int datalen, int is_name, const char *data)
1439 {
1440 struct server_request *req = TO_SERVER_REQUEST(_req);
1441 struct server_reply_item **itemp, *item;
1442 int *countp;
1443
1444 if (req->response) /* have we already answered? */
1445 return (-1);
1446
1447 switch (section) {
1448 case EVDNS_ANSWER_SECTION:
1449 itemp = &req->answer;
1450 countp = &req->n_answer;
1451 break;
1452 case EVDNS_AUTHORITY_SECTION:
1453 itemp = &req->authority;
1454 countp = &req->n_authority;
1455 break;
1456 case EVDNS_ADDITIONAL_SECTION:
1457 itemp = &req->additional;
1458 countp = &req->n_additional;
1459 break;
1460 default:
1461 return (-1);
1462 }
1463 while (*itemp) {
1464 itemp = &((*itemp)->next);
1465 }
1466 item = malloc(sizeof(struct server_reply_item));
1467 if (!item)
1468 return -1;
1469 item->next = NULL;
1470 if (!(item->name = strdup(name))) {
1471 free(item);
1472 return -1;
1473 }
1474 item->type = type;
1475 item->class = class;
1476 item->ttl = ttl;
1477 item->is_name = is_name != 0;
1478 item->datalen = 0;
1479 item->data = NULL;
1480 if (data) {
1481 if (item->is_name) {
1482 if (!(item->data = strdup(data))) {
1483 free(item->name);
1484 free(item);
1485 return -1;
1486 }
1487 item->datalen = (u16)-1;
1488 } else {
1489 if (!(item->data = malloc(datalen))) {
1490 free(item->name);
1491 free(item);
1492 return -1;
1493 }
1494 item->datalen = datalen;
1495 memcpy(item->data, data, datalen);
1496 }
1497 }
1498
1499 *itemp = item;
1500 ++(*countp);
1501 return 0;
1502 }
1503
1504 /* exported function */
1505 int
1506 evdns_server_request_add_a_reply(struct evdns_server_request *req, const char *name, int n, void *addrs, int ttl)
1507 {
1508 return evdns_server_request_add_reply(
1509 req, EVDNS_ANSWER_SECTION, name, TYPE_A, CLASS_INET,
1510 ttl, n*4, 0, addrs);
1511 }
1512
1513 /* exported function */
1514 int
1515 evdns_server_request_add_aaaa_reply(struct evdns_server_request *req, const char *name, int n, void *addrs, int ttl)
1516 {
1517 return evdns_server_request_add_reply(
1518 req, EVDNS_ANSWER_SECTION, name, TYPE_AAAA, CLASS_INET,
1519 ttl, n*16, 0, addrs);
1520 }
1521
1522 /* exported function */
1523 int
1524 evdns_server_request_add_ptr_reply(struct evdns_server_request *req, struct in_addr *in, const char *inaddr_name, const char *hostname, int ttl)
1525 {
1526 u32 a;
1527 char buf[32];
1528 assert(in || inaddr_name);
1529 assert(!(in && inaddr_name));
1530 if (in) {
1531 a = ntohl(in->s_addr);
1532 snprintf(buf, sizeof(buf), "%d.%d.%d.%d.in-addr.arpa",
1533 (int)(u8)((a )&0xff),
1534 (int)(u8)((a>>8 )&0xff),
1535 (int)(u8)((a>>16)&0xff),
1536 (int)(u8)((a>>24)&0xff));
1537 inaddr_name = buf;
1538 }
1539 return evdns_server_request_add_reply(
1540 req, EVDNS_ANSWER_SECTION, inaddr_name, TYPE_PTR, CLASS_INET,
1541 ttl, -1, 1, hostname);
1542 }
1543
1544 /* exported function */
1545 int
1546 evdns_server_request_add_cname_reply(struct evdns_server_request *req, const char *name, const char *cname, int ttl)
1547 {
1548 return evdns_server_request_add_reply(
1549 req, EVDNS_ANSWER_SECTION, name, TYPE_A, CLASS_INET,
1550 ttl, -1, 1, cname);
1551 }
1552
1553
1554 static int
1555 evdns_server_request_format_response(struct server_request *req, int err)
1556 {
1557 unsigned char buf[1500];
1558 size_t buf_len = sizeof(buf);
1559 off_t j = 0, r;
1560 u16 _t;
1561 u32 _t32;
1562 int i;
1563 u16 flags;
1564 struct dnslabel_table table;
1565
1566 if (err < 0 || err > 15) return -1;
1567
1568 /* Set response bit and error code; copy OPCODE and RD fields from
1569 * question; copy RA and AA if set by caller. */
1570 flags = req->base.flags;
1571 flags |= (0x8000 | err);
1572
1573 dnslabel_table_init(&table);
1574 APPEND16(req->trans_id);
1575 APPEND16(flags);
1576 APPEND16(req->base.nquestions);
1577 APPEND16(req->n_answer);
1578 APPEND16(req->n_authority);
1579 APPEND16(req->n_additional);
1580
1581 /* Add questions. */
1582 for (i=0; i < req->base.nquestions; ++i) {
1583 const char *s = req->base.questions[i]->name;
1584 j = dnsname_to_labels(buf, buf_len, j, s, strlen(s), &table);
1585 if (j < 0) {
1586 dnslabel_clear(&table);
1587 return (int) j;
1588 }
1589 APPEND16(req->base.questions[i]->type);
1590 APPEND16(req->base.questions[i]->class);
1591 }
1592
1593 /* Add answer, authority, and additional sections. */
1594 for (i=0; i<3; ++i) {
1595 struct server_reply_item *item;
1596 if (i==0)
1597 item = req->answer;
1598 else if (i==1)
1599 item = req->authority;
1600 else
1601 item = req->additional;
1602 while (item) {
1603 r = dnsname_to_labels(buf, buf_len, j, item->name, strlen(item->name), &table);
1604 if (r < 0)
1605 goto overflow;
1606 j = r;
1607
1608 APPEND16(item->type);
1609 APPEND16(item->class);
1610 APPEND32(item->ttl);
1611 if (item->is_name) {
1612 off_t len_idx = j, name_start;
1613 j += 2;
1614 name_start = j;
1615 r = dnsname_to_labels(buf, buf_len, j, item->data, strlen(item->data), &table);
1616 if (r < 0)
1617 goto overflow;
1618 j = r;
1619 _t = htons( (j-name_start) );
1620 memcpy(buf+len_idx, &_t, 2);
1621 } else {
1622 APPEND16(item->datalen);
1623 if (j+item->datalen > (off_t)buf_len)
1624 goto overflow;
1625 memcpy(buf+j, item->data, item->datalen);
1626 j += item->datalen;
1627 }
1628 item = item->next;
1629 }
1630 }
1631
1632 if (j > 512) {
1633 overflow:
1634 j = 512;
1635 buf[3] |= 0x02; /* set the truncated bit. */
1636 }
1637
1638 req->response_len = j;
1639
1640 if (!(req->response = malloc(req->response_len))) {
1641 server_request_free_answers(req);
1642 dnslabel_clear(&table);
1643 return (-1);
1644 }
1645 memcpy(req->response, buf, req->response_len);
1646 server_request_free_answers(req);
1647 dnslabel_clear(&table);
1648 return (0);
1649 }
1650
1651 /* exported function */
1652 int
1653 evdns_server_request_respond(struct evdns_server_request *_req, int err)
1654 {
1655 struct server_request *req = TO_SERVER_REQUEST(_req);
1656 struct evdns_server_port *port = req->port;
1657 int r;
1658 if (!req->response) {
1659 if ((r = evdns_server_request_format_response(req, err))<0)
1660 return r;
1661 }
1662
1663 r = sendto(port->socket, req->response, req->response_len, 0,
1664 (struct sockaddr*) &req->addr, req->addrlen);
1665 if (r<0) {
1666 int err = last_error(port->socket);
1667 if (! error_is_eagain(err))
1668 return -1;
1669
1670 if (port->pending_replies) {
1671 req->prev_pending = port->pending_replies->prev_pending;
1672 req->next_pending = port->pending_replies;
1673 req->prev_pending->next_pending =
1674 req->next_pending->prev_pending = req;
1675 } else {
1676 req->prev_pending = req->next_pending = req;
1677 port->pending_replies = req;
1678 port->choked = 1;
1679
1680 (void) event_del(&port->event);
1681 event_set(&port->event, port->socket, (port->closing?0:EV_READ) | EV_WRITE | EV_PERSIST, server_port_ready_callback, port);
1682
1683 if (event_add(&port->event, NULL) < 0) {
1684 log(EVDNS_LOG_WARN, "Error from libevent when adding event for DNS server");
1685 }
1686
1687 }
1688
1689 return 1;
1690 }
1691 if (server_request_free(req))
1692 return 0;
1693
1694 if (port->pending_replies)
1695 server_port_flush(port);
1696
1697 return 0;
1698 }
1699
1700 /* Free all storage held by RRs in req. */
1701 static void
1702 server_request_free_answers(struct server_request *req)
1703 {
1704 struct server_reply_item *victim, *next, **list;
1705 int i;
1706 for (i = 0; i < 3; ++i) {
1707 if (i==0)
1708 list = &req->answer;
1709 else if (i==1)
1710 list = &req->authority;
1711 else
1712 list = &req->additional;
1713
1714 victim = *list;
1715 while (victim) {
1716 next = victim->next;
1717 free(victim->name);
1718 if (victim->data)
1719 free(victim->data);
1720 free(victim);
1721 victim = next;
1722 }
1723 *list = NULL;
1724 }
1725 }
1726
1727 /* Free all storage held by req, and remove links to it. */
1728 /* return true iff we just wound up freeing the server_port. */
1729 static int
1730 server_request_free(struct server_request *req)
1731 {
1732 int i, rc=1;
1733 if (req->base.questions) {
1734 for (i = 0; i < req->base.nquestions; ++i)
1735 free(req->base.questions[i]);
1736 free(req->base.questions);
1737 }
1738
1739 if (req->port) {
1740 if (req->port->pending_replies == req) {
1741 if (req->next_pending)
1742 req->port->pending_replies = req->next_pending;
1743 else
1744 req->port->pending_replies = NULL;
1745 }
1746 rc = --req->port->refcnt;
1747 }
1748
1749 if (req->response) {
1750 free(req->response);
1751 }
1752
1753 server_request_free_answers(req);
1754
1755 if (req->next_pending && req->next_pending != req) {
1756 req->next_pending->prev_pending = req->prev_pending;
1757 req->prev_pending->next_pending = req->next_pending;
1758 }
1759
1760 if (rc == 0) {
1761 server_port_free(req->port);
1762 free(req);
1763 return (1);
1764 }
1765 free(req);
1766 return (0);
1767 }
1768
1769 /* Free all storage held by an evdns_server_port. Only called when */
1770 static void
1771 server_port_free(struct evdns_server_port *port)
1772 {
1773 assert(port);
1774 assert(!port->refcnt);
1775 assert(!port->pending_replies);
1776 if (port->socket > 0) {
1777 CLOSE_SOCKET(port->socket);
1778 port->socket = -1;
1779 }
1780 (void) event_del(&port->event);
1781 /* XXXX actually free the port? -NM */
1782 }
1783
1784 /* exported function */
1785 int
1786 evdns_server_request_drop(struct evdns_server_request *_req)
1787 {
1788 struct server_request *req = TO_SERVER_REQUEST(_req);
1789 server_request_free(req);
1790 return 0;
1791 }
1792
1793 /* exported function */
1794 int
1795 evdns_server_request_get_requesting_addr(struct evdns_server_request *_req, struct sockaddr *sa, int addr_len)
1796 {
1797 struct server_request *req = TO_SERVER_REQUEST(_req);
1798 if (addr_len < (int)req->addrlen)
1799 return -1;
1800 memcpy(sa, &(req->addr), req->addrlen);
1801 return req->addrlen;
1802 }
1803
1804 #undef APPEND16
1805 #undef APPEND32
1806
1807 /* this is a libevent callback function which is called when a request */
1808 /* has timed out. */
1809 static void
1810 evdns_request_timeout_callback(int fd, short events, void *arg) {
1811 struct request *const req = (struct request *) arg;
1812 (void) fd;
1813 (void) events;
1814
1815 log(EVDNS_LOG_DEBUG, "Request %lx timed out", (unsigned long) arg);
1816
1817 req->ns->timedout++;
1818 if (req->ns->timedout > global_max_nameserver_timeout) {
1819 req->ns->timedout = 0;
1820 nameserver_failed(req->ns, "request timed out.");
1821 }
1822
1823 (void) evtimer_del(&req->timeout_event);
1824 if (req->tx_count >= global_max_retransmits) {
1825 /* this request has failed */
1826 reply_callback(req, 0, DNS_ERR_TIMEOUT, NULL);
1827 request_finished(req, &req_head);
1828 } else {
1829 /* retransmit it */
1830 evdns_request_transmit(req);
1831 }
1832 }
1833
1834 /* try to send a request to a given server. */
1835 /* */
1836 /* return: */
1837 /* 0 ok */
1838 /* 1 temporary failure */
1839 /* 2 other failure */
1840 static int
1841 evdns_request_transmit_to(struct request *req, struct nameserver *server) {
1842 const int r = send(server->socket, req->request, req->request_len, 0);
1843 if (r < 0) {
1844 int err = last_error(server->socket);
1845 if (error_is_eagain(err)) return 1;
1846 nameserver_failed(req->ns, strerror(err));
1847 return 2;
1848 } else if (r != (int)req->request_len) {
1849 return 1; /* short write */
1850 } else {
1851 return 0;
1852 }
1853 }
1854
1855 /* try to send a request, updating the fields of the request */
1856 /* as needed */
1857 /* */
1858 /* return: */
1859 /* 0 ok */
1860 /* 1 failed */
1861 static int
1862 evdns_request_transmit(struct request *req) {
1863 int retcode = 0, r;
1864
1865 /* if we fail to send this packet then this flag marks it */
1866 /* for evdns_transmit */
1867 req->transmit_me = 1;
1868 if (req->trans_id == 0xffff) abort();
1869
1870 if (req->ns->choked) {
1871 /* don't bother trying to write to a socket */
1872 /* which we have had EAGAIN from */
1873 return 1;
1874 }
1875
1876 r = evdns_request_transmit_to(req, req->ns);
1877 switch (r) {
1878 case 1:
1879 /* temp failure */
1880 req->ns->choked = 1;
1881 nameserver_write_waiting(req->ns, 1);
1882 return 1;
1883 case 2:
1884 /* failed in some other way */
1885 retcode = 1;
1886 /* fall through */
1887 default:
1888 /* all ok */
1889 log(EVDNS_LOG_DEBUG,
1890 "Setting timeout for request %lx", (unsigned long) req);
1891 evtimer_set(&req->timeout_event, evdns_request_timeout_callback, req);
1892 if (evtimer_add(&req->timeout_event, &global_timeout) < 0) {
1893 log(EVDNS_LOG_WARN,
1894 "Error from libevent when adding timer for request %lx",
1895 (unsigned long) req);
1896 /* ???? Do more? */
1897 }
1898 req->tx_count++;
1899 req->transmit_me = 0;
1900 return retcode;
1901 }
1902 }
1903
1904 static void
1905 nameserver_probe_callback(int result, char type, int count, int ttl, void *addresses, void *arg) {
1906 struct nameserver *const ns = (struct nameserver *) arg;
1907 (void) type;
1908 (void) count;
1909 (void) ttl;
1910 (void) addresses;
1911
1912 if (result == DNS_ERR_NONE || result == DNS_ERR_NOTEXIST) {
1913 /* this is a good reply */
1914 nameserver_up(ns);
1915 } else nameserver_probe_failed(ns);
1916 }
1917
1918 static void
1919 nameserver_send_probe(struct nameserver *const ns) {
1920 struct request *req;
1921 /* here we need to send a probe to a given nameserver */
1922 /* in the hope that it is up now. */
1923
1924 log(EVDNS_LOG_DEBUG, "Sending probe to %s", debug_ntoa(ns->address));
1925
1926 req = request_new(TYPE_A, "www.google.com", DNS_QUERY_NO_SEARCH, nameserver_probe_callback, ns);
1927 if (!req) return;
1928 /* we force this into the inflight queue no matter what */
1929 request_trans_id_set(req, transaction_id_pick());
1930 req->ns = ns;
1931 request_submit(req);
1932 }
1933
1934 /* returns: */
1935 /* 0 didn't try to transmit anything */
1936 /* 1 tried to transmit something */
1937 static int
1938 evdns_transmit(void) {
1939 char did_try_to_transmit = 0;
1940
1941 if (req_head) {
1942 struct request *const started_at = req_head, *req = req_head;
1943 /* first transmit all the requests which are currently waiting */
1944 do {
1945 if (req->transmit_me) {
1946 did_try_to_transmit = 1;
1947 evdns_request_transmit(req);
1948 }
1949
1950 req = req->next;
1951 } while (req != started_at);
1952 }
1953
1954 return did_try_to_transmit;
1955 }
1956
1957 /* exported function */
1958 int
1959 evdns_count_nameservers(void)
1960 {
1961 const struct nameserver *server = server_head;
1962 int n = 0;
1963 if (!server)
1964 return 0;
1965 do {
1966 ++n;
1967 server = server->next;
1968 } while (server != server_head);
1969 return n;
1970 }
1971
1972 /* exported function */
1973 int
1974 evdns_clear_nameservers_and_suspend(void)
1975 {
1976 struct nameserver *server = server_head, *started_at = server_head;
1977 struct request *req = req_head, *req_started_at = req_head;
1978
1979 if (!server)
1980 return 0;
1981 while (1) {
1982 struct nameserver *next = server->next;
1983 (void) event_del(&server->event);
1984 (void) evtimer_del(&server->timeout_event);
1985 if (server->socket >= 0)
1986 CLOSE_SOCKET(server->socket);
1987 free(server);
1988 if (next == started_at)
1989 break;
1990 server = next;
1991 }
1992 server_head = NULL;
1993 global_good_nameservers = 0;
1994
1995 while (req) {
1996 struct request *next = req->next;
1997 req->tx_count = req->reissue_count = 0;
1998 req->ns = NULL;
1999 /* ???? What to do about searches? */
2000 (void) evtimer_del(&req->timeout_event);
2001 req->trans_id = 0;
2002 req->transmit_me = 0;
2003
2004 global_requests_waiting++;
2005 evdns_request_insert(req, &req_waiting_head);
2006 /* We want to insert these suspended elements at the front of
2007 * the waiting queue, since they were pending before any of
2008 * the waiting entries were added. This is a circular list,
2009 * so we can just shift the start back by one.*/
2010 req_waiting_head = req_waiting_head->prev;
2011
2012 if (next == req_started_at)
2013 break;
2014 req = next;
2015 }
2016 req_head = NULL;
2017 global_requests_inflight = 0;
2018
2019 return 0;
2020 }
2021
2022
2023 /* exported function */
2024 int
2025 evdns_resume(void)
2026 {
2027 evdns_requests_pump_waiting_queue();
2028 return 0;
2029 }
2030
2031 static int
2032 _evdns_nameserver_add_impl(unsigned long int address, int port) {
2033 /* first check to see if we already have this nameserver */
2034
2035 const struct nameserver *server = server_head, *const started_at = server_head;
2036 struct nameserver *ns;
2037 struct sockaddr_in sin;
2038 int err = 0;
2039 if (server) {
2040 do {
2041 if (server->address == address) return 3;
2042 server = server->next;
2043 } while (server != started_at);
2044 }
2045
2046 ns = (struct nameserver *) malloc(sizeof(struct nameserver));
2047 if (!ns) return -1;
2048
2049 memset(ns, 0, sizeof(struct nameserver));
2050
2051 ns->socket = socket(PF_INET, SOCK_DGRAM, 0);
2052 if (ns->socket < 0) { err = 1; goto out1; }
2053 #ifdef WIN32
2054 {
2055 u_long nonblocking = 1;
2056 ioctlsocket(ns->socket, FIONBIO, &nonblocking);
2057 }
2058 #else
2059 fcntl(ns->socket, F_SETFL, O_NONBLOCK);
2060 #endif
2061 sin.sin_addr.s_addr = address;
2062 sin.sin_port = htons(port);
2063 sin.sin_family = AF_INET;
2064 if (connect(ns->socket, (struct sockaddr *) &sin, sizeof(sin)) != 0) {
2065 err = 2;
2066 goto out2;
2067 }
2068
2069 ns->address = address;
2070 ns->state = 1;
2071 event_set(&ns->event, ns->socket, EV_READ | EV_PERSIST, nameserver_ready_callback, ns);
2072 if (event_add(&ns->event, NULL) < 0) {
2073 err = 2;
2074 goto out2;
2075 }
2076
2077 log(EVDNS_LOG_DEBUG, "Added nameserver %s", debug_ntoa(address));
2078
2079 /* insert this nameserver into the list of them */
2080 if (!server_head) {
2081 ns->next = ns->prev = ns;
2082 server_head = ns;
2083 } else {
2084 ns->next = server_head->next;
2085 ns->prev = server_head;
2086 server_head->next = ns;
2087 if (server_head->prev == server_head) {
2088 server_head->prev = ns;
2089 }
2090 }
2091
2092 global_good_nameservers++;
2093
2094 return 0;
2095
2096 out2:
2097 CLOSE_SOCKET(ns->socket);
2098 out1:
2099 free(ns);
2100 log(EVDNS_LOG_WARN, "Unable to add nameserver %s: error %d", debug_ntoa(address), err);
2101 return err;
2102 }
2103
2104 /* exported function */
2105 int
2106 evdns_nameserver_add(unsigned long int address) {
2107 return _evdns_nameserver_add_impl(address, 53);
2108 }
2109
2110 /* exported function */
2111 int
2112 evdns_nameserver_ip_add(const char *ip_as_string) {
2113 struct in_addr ina;
2114 int port;
2115 char buf[20];
2116 const char *cp;
2117 cp = strchr(ip_as_string, ':');
2118 if (! cp) {
2119 cp = ip_as_string;
2120 port = 53;
2121 } else {
2122 port = strtoint(cp+1);
2123 if (port < 0 || port > 65535) {
2124 return 4;
2125 }
2126 if ((cp-ip_as_string) >= (int)sizeof(buf)) {
2127 return 4;
2128 }
2129 memcpy(buf, ip_as_string, cp-ip_as_string);
2130 buf[cp-ip_as_string] = '\0';
2131 cp = buf;
2132 }
2133 if (!inet_aton(cp, &ina)) {
2134 return 4;
2135 }
2136 return _evdns_nameserver_add_impl(ina.s_addr, port);
2137 }
2138
2139 /* insert into the tail of the queue */
2140 static void
2141 evdns_request_insert(struct request *req, struct request **head) {
2142 if (!*head) {
2143 *head = req;
2144 req->next = req->prev = req;
2145 return;
2146 }
2147
2148 req->prev = (*head)->prev;
2149 req->prev->next = req;
2150 req->next = *head;
2151 (*head)->prev = req;
2152 }
2153
2154 static int
2155 string_num_dots(const char *s) {
2156 int count = 0;
2157 while ((s = strchr(s, '.'))) {
2158 s++;
2159 count++;
2160 }
2161 return count;
2162 }
2163
2164 static struct request *
2165 request_new(int type, const char *name, int flags,
2166 evdns_callback_type callback, void *user_ptr) {
2167 const char issuing_now =
2168 (global_requests_inflight < global_max_requests_inflight) ? 1 : 0;
2169
2170 const int name_len = strlen(name);
2171 const int request_max_len = evdns_request_len(name_len);
2172 const u16 trans_id = issuing_now ? transaction_id_pick() : 0xffff;
2173 /* the request data is alloced in a single block with the header */
2174 struct request *const req =
2175 (struct request *) malloc(sizeof(struct request) + request_max_len);
2176 int rlen;
2177 (void) flags;
2178
2179 if (!req) return NULL;
2180 memset(req, 0, sizeof(struct request));
2181
2182 /* request data lives just after the header */
2183 req->request = ((u8 *) req) + sizeof(struct request);
2184 /* denotes that the request data shouldn't be free()ed */
2185 req->request_appended = 1;
2186 rlen = evdns_request_data_build(name, name_len, trans_id,
2187 type, CLASS_INET, req->request, request_max_len);
2188 if (rlen < 0)
2189 goto err1;
2190 req->request_len = rlen;
2191 req->trans_id = trans_id;
2192 req->tx_count = 0;
2193 req->request_type = type;
2194 req->user_pointer = user_ptr;
2195 req->user_callback = callback;
2196 req->ns = issuing_now ? nameserver_pick() : NULL;
2197 req->next = req->prev = NULL;
2198
2199 return req;
2200 err1:
2201 free(req);
2202 return NULL;
2203 }
2204
2205 static void
2206 request_submit(struct request *const req) {
2207 if (req->ns) {
2208 /* if it has a nameserver assigned then this is going */
2209 /* straight into the inflight queue */
2210 evdns_request_insert(req, &req_head);
2211 global_requests_inflight++;
2212 evdns_request_transmit(req);
2213 } else {
2214 evdns_request_insert(req, &req_waiting_head);
2215 global_requests_waiting++;
2216 }
2217 }
2218
2219 /* exported function */
2220 int evdns_resolve_ipv4(const char *name, int flags,
2221 evdns_callback_type callback, void *ptr) {
2222 log(EVDNS_LOG_DEBUG, "Resolve requested for %s", name);
2223 if (flags & DNS_QUERY_NO_SEARCH) {
2224 struct request *const req =
2225 request_new(TYPE_A, name, flags, callback, ptr);
2226 if (req == NULL)
2227 return (1);
2228 request_submit(req);
2229 return (0);
2230 } else {
2231 return (search_request_new(TYPE_A, name, flags, callback, ptr));
2232 }
2233 }
2234
2235 /* exported function */
2236 int evdns_resolve_ipv6(const char *name, int flags,
2237 evdns_callback_type callback, void *ptr) {
2238 log(EVDNS_LOG_DEBUG, "Resolve requested for %s", name);
2239 if (flags & DNS_QUERY_NO_SEARCH) {
2240 struct request *const req =
2241 request_new(TYPE_AAAA, name, flags, callback, ptr);
2242 if (req == NULL)
2243 return (1);
2244 request_submit(req);
2245 return (0);
2246 } else {
2247 return (search_request_new(TYPE_AAAA, name, flags, callback, ptr));
2248 }
2249 }
2250
2251 int evdns_resolve_reverse(struct in_addr *in, int flags, evdns_callback_type callback, void *ptr) {
2252 char buf[32];
2253 struct request *req;
2254 u32 a;
2255 assert(in);
2256 a = ntohl(in->s_addr);
2257 snprintf(buf, sizeof(buf), "%d.%d.%d.%d.in-addr.arpa",
2258 (int)(u8)((a )&0xff),
2259 (int)(u8)((a>>8 )&0xff),
2260 (int)(u8)((a>>16)&0xff),
2261 (int)(u8)((a>>24)&0xff));
2262 log(EVDNS_LOG_DEBUG, "Resolve requested for %s (reverse)", buf);
2263 req = request_new(TYPE_PTR, buf, flags, callback, ptr);
2264 if (!req) return 1;
2265 request_submit(req);
2266 return 0;
2267 }
2268
2269 int evdns_resolve_reverse_ipv6(struct in6_addr *in, int flags, evdns_callback_type callback, void *ptr) {
2270 char buf[64];
2271 char *cp;
2272 struct request *req;
2273 int i;
2274 assert(in);
2275 cp = buf;
2276 for (i=15; i >= 0; --i) {
2277 u8 byte = in->s6_addr[i];
2278 *cp++ = "0123456789abcdef"[byte & 0x0f];
2279 *cp++ = '.';
2280 *cp++ = "0123456789abcdef"[byte >> 4];
2281 *cp++ = '.';
2282 }
2283 assert(cp + strlen(".ip6.arpa") < buf+sizeof(buf));
2284 memcpy(cp, ".ip6.arpa", strlen(".ip6.arpa")+1);
2285 log(EVDNS_LOG_DEBUG, "Resolve requested for %s (reverse)", buf);
2286 req = request_new(TYPE_PTR, buf, flags, callback, ptr);
2287 if (!req) return 1;
2288 request_submit(req);
2289 return 0;
2290 }
2291
2292 /*/////////////////////////////////////////////////////////////////// */
2293 /* Search support */
2294 /* */
2295 /* the libc resolver has support for searching a number of domains */
2296 /* to find a name. If nothing else then it takes the single domain */
2297 /* from the gethostname() call. */
2298 /* */
2299 /* It can also be configured via the domain and search options in a */
2300 /* resolv.conf. */
2301 /* */
2302 /* The ndots option controls how many dots it takes for the resolver */
2303 /* to decide that a name is non-local and so try a raw lookup first. */
2304
2305 struct search_domain {
2306 int len;
2307 struct search_domain *next;
2308 /* the text string is appended to this structure */
2309 };
2310
2311 struct search_state {
2312 int refcount;
2313 int ndots;
2314 int num_domains;
2315 struct search_domain *head;
2316 };
2317
2318 static struct search_state *global_search_state = NULL;
2319
2320 static void
2321 search_state_decref(struct search_state *const state) {
2322 if (!state) return;
2323 state->refcount--;
2324 if (!state->refcount) {
2325 struct search_domain *next, *dom;
2326 for (dom = state->head; dom; dom = next) {
2327 next = dom->next;
2328 free(dom);
2329 }
2330 free(state);
2331 }
2332 }
2333
2334 static struct search_state *
2335 search_state_new(void) {
2336 struct search_state *state = (struct search_state *) malloc(sizeof(struct search_state));
2337 if (!state) return NULL;
2338 memset(state, 0, sizeof(struct search_state));
2339 state->refcount = 1;
2340 state->ndots = 1;
2341
2342 return state;
2343 }
2344
2345 static void
2346 search_postfix_clear(void) {
2347 search_state_decref(global_search_state);
2348
2349 global_search_state = search_state_new();
2350 }
2351
2352 /* exported function */
2353 void
2354 evdns_search_clear(void) {
2355 search_postfix_clear();
2356 }
2357
2358 static void
2359 search_postfix_add(const char *domain) {
2360 int domain_len;
2361 struct search_domain *sdomain;
2362 while (domain[0] == '.') domain++;
2363 domain_len = strlen(domain);
2364
2365 if (!global_search_state) global_search_state = search_state_new();
2366 if (!global_search_state) return;
2367 global_search_state->num_domains++;
2368
2369 sdomain = (struct search_domain *) malloc(sizeof(struct search_domain) + domain_len);
2370 if (!sdomain) return;
2371 memcpy( ((u8 *) sdomain) + sizeof(struct search_domain), domain, domain_len);
2372 sdomain->next = global_search_state->head;
2373 sdomain->len = domain_len;
2374
2375 global_search_state->head = sdomain;
2376 }
2377
2378 /* reverse the order of members in the postfix list. This is needed because, */
2379 /* when parsing resolv.conf we push elements in the wrong order */
2380 static void
2381 search_reverse(void) {
2382 struct search_domain *cur, *prev = NULL, *next;
2383 cur = global_search_state->head;
2384 while (cur) {
2385 next = cur->next;
2386 cur->next = prev;
2387 prev = cur;
2388 cur = next;
2389 }
2390
2391 global_search_state->head = prev;
2392 }
2393
2394 /* exported function */
2395 void
2396 evdns_search_add(const char *domain) {
2397 search_postfix_add(domain);
2398 }
2399
2400 /* exported function */
2401 void
2402 evdns_search_ndots_set(const int ndots) {
2403 if (!global_search_state) global_search_state = search_state_new();
2404 if (!global_search_state) return;
2405 global_search_state->ndots = ndots;
2406 }
2407
2408 static void
2409 search_set_from_hostname(void) {
2410 char hostname[HOST_NAME_MAX + 1], *domainname;
2411
2412 search_postfix_clear();
2413 if (gethostname(hostname, sizeof(hostname))) return;
2414 domainname = strchr(hostname, '.');
2415 if (!domainname) return;
2416 search_postfix_add(domainname);
2417 }
2418
2419 /* warning: returns malloced string */
2420 static char *
2421 search_make_new(const struct search_state *const state, int n, const char *const base_name) {
2422 const int base_len = strlen(base_name);
2423 const char need_to_append_dot = base_name[base_len - 1] == '.' ? 0 : 1;
2424 struct search_domain *dom;
2425
2426 for (dom = state->head; dom; dom = dom->next) {
2427 if (!n--) {
2428 /* this is the postfix we want */
2429 /* the actual postfix string is kept at the end of the structure */
2430 const u8 *const postfix = ((u8 *) dom) + sizeof(struct search_domain);
2431 const int postfix_len = dom->len;
2432 char *const newname = (char *) malloc(base_len + need_to_append_dot + postfix_len + 1);
2433 if (!newname) return NULL;
2434 memcpy(newname, base_name, base_len);
2435 if (need_to_append_dot) newname[base_len] = '.';
2436 memcpy(newname + base_len + need_to_append_dot, postfix, postfix_len);
2437 newname[base_len + need_to_append_dot + postfix_len] = 0;
2438 return newname;
2439 }
2440 }
2441
2442 /* we ran off the end of the list and still didn't find the requested string */
2443 abort();
2444 return NULL; /* unreachable; stops warnings in some compilers. */
2445 }
2446
2447 static int
2448 search_request_new(int type, const char *const name, int flags, evdns_callback_type user_callback, void *user_arg) {
2449 assert(type == TYPE_A || type == TYPE_AAAA);
2450 if ( ((flags & DNS_QUERY_NO_SEARCH) == 0) &&
2451 global_search_state &&
2452 global_search_state->num_domains) {
2453 /* we have some domains to search */
2454 struct request *req;
2455 if (string_num_dots(name) >= global_search_state->ndots) {
2456 req = request_new(type, name, flags, user_callback, user_arg);
2457 if (!req) return 1;
2458 req->search_index = -1;
2459 } else {
2460 char *const new_name = search_make_new(global_search_state, 0, name);
2461 if (!new_name) return 1;
2462 req = request_new(type, new_name, flags, user_callback, user_arg);
2463 free(new_name);
2464 if (!req) return 1;
2465 req->search_index = 0;
2466 }
2467 req->search_origname = strdup(name);
2468 req->search_state = global_search_state;
2469 req->search_flags = flags;
2470 global_search_state->refcount++;
2471 request_submit(req);
2472 return 0;
2473 } else {
2474 struct request *const req = request_new(type, name, flags, user_callback, user_arg);
2475 if (!req) return 1;
2476 request_submit(req);
2477 return 0;
2478 }
2479 }
2480
2481 /* this is called when a request has failed to find a name. We need to check */
2482 /* if it is part of a search and, if so, try the next name in the list */
2483 /* returns: */
2484 /* 0 another request has been submitted */
2485 /* 1 no more requests needed */
2486 static int
2487 search_try_next(struct request *const req) {
2488 if (req->search_state) {
2489 /* it is part of a search */
2490 char *new_name;
2491 struct request *newreq;
2492 req->search_index++;
2493 if (req->search_index >= req->search_state->num_domains) {
2494 /* no more postfixes to try, however we may need to try */
2495 /* this name without a postfix */
2496 if (string_num_dots(req->search_origname) < req->search_state->ndots) {
2497 /* yep, we need to try it raw */
2498 struct request *const newreq = request_new(req->request_type, req->search_origname, req->search_flags, req->user_callback, req->user_pointer);
2499 log(EVDNS_LOG_DEBUG, "Search: trying raw query %s", req->search_origname);
2500 if (newreq) {
2501 request_submit(newreq);
2502 return 0;
2503 }
2504 }
2505 return 1;
2506 }
2507
2508 new_name = search_make_new(req->search_state, req->search_index, req->search_origname);
2509 if (!new_name) return 1;
2510 log(EVDNS_LOG_DEBUG, "Search: now trying %s (%d)", new_name, req->search_index);
2511 newreq = request_new(req->request_type, new_name, req->search_flags, req->user_callback, req->user_pointer);
2512 free(new_name);
2513 if (!newreq) return 1;
2514 newreq->search_origname = req->search_origname;
2515 req->search_origname = NULL;
2516 newreq->search_state = req->search_state;
2517 newreq->search_flags = req->search_flags;
2518 newreq->search_index = req->search_index;
2519 newreq->search_state->refcount++;
2520 request_submit(newreq);
2521 return 0;
2522 }
2523 return 1;
2524 }
2525
2526 static void
2527 search_request_finished(struct request *const req) {
2528 if (req->search_state) {
2529 search_state_decref(req->search_state);
2530 req->search_state = NULL;
2531 }
2532 if (req->search_origname) {
2533 free(req->search_origname);
2534 req->search_origname = NULL;
2535 }
2536 }
2537
2538 /*/////////////////////////////////////////////////////////////////// */
2539 /* Parsing resolv.conf files */
2540
2541 static void
2542 evdns_resolv_set_defaults(int flags) {
2543 /* if the file isn't found then we assume a local resolver */
2544 if (flags & DNS_OPTION_SEARCH) search_set_from_hostname();
2545 if (flags & DNS_OPTION_NAMESERVERS) evdns_nameserver_ip_add("127.0.0.1");
2546 }
2547
2548 #ifndef HAVE_STRTOK_R
2549 static char *
2550 strtok_r(char *s, const char *delim, char **state) {
2551 return strtok(s, delim);
2552 }
2553 #endif
2554
2555 /* helper version of atoi which returns -1 on error */
2556 static int
2557 strtoint(const char *const str) {
2558 char *endptr;
2559 const int r = strtol(str, &endptr, 10);
2560 if (*endptr) return -1;
2561 return r;
2562 }
2563
2564 /* helper version of atoi that returns -1 on error and clips to bounds. */
2565 static int
2566 strtoint_clipped(const char *const str, int min, int max)
2567 {
2568 int r = strtoint(str);
2569 if (r == -1)
2570 return r;
2571 else if (r<min)
2572 return min;
2573 else if (r>max)
2574 return max;
2575 else
2576 return r;
2577 }
2578
2579 /* exported function */
2580 int
2581 evdns_set_option(const char *option, const char *val, int flags)
2582 {
2583 if (!strncmp(option, "ndots:", 6)) {
2584 const int ndots = strtoint(val);
2585 if (ndots == -1) return -1;
2586 if (!(flags & DNS_OPTION_SEARCH)) return 0;
2587 log(EVDNS_LOG_DEBUG, "Setting ndots to %d", ndots);
2588 if (!global_search_state) global_search_state = search_state_new();
2589 if (!global_search_state) return -1;
2590 global_search_state->ndots = ndots;
2591 } else if (!strncmp(option, "timeout:", 8)) {
2592 const int timeout = strtoint(val);
2593 if (timeout == -1) return -1;
2594 if (!(flags & DNS_OPTION_MISC)) return 0;
2595 log(EVDNS_LOG_DEBUG, "Setting timeout to %d", timeout);
2596 global_timeout.tv_sec = timeout;
2597 } else if (!strncmp(option, "max-timeouts:", 12)) {
2598 const int maxtimeout = strtoint_clipped(val, 1, 255);
2599 if (maxtimeout == -1) return -1;
2600 if (!(flags & DNS_OPTION_MISC)) return 0;
2601 log(EVDNS_LOG_DEBUG, "Setting maximum allowed timeouts to %d",
2602 maxtimeout);
2603 global_max_nameserver_timeout = maxtimeout;
2604 } else if (!strncmp(option, "max-inflight:", 13)) {
2605 const int maxinflight = strtoint_clipped(val, 1, 65000);
2606 if (maxinflight == -1) return -1;
2607 if (!(flags & DNS_OPTION_MISC)) return 0;
2608 log(EVDNS_LOG_DEBUG, "Setting maximum inflight requests to %d",
2609 maxinflight);
2610 global_max_requests_inflight = maxinflight;
2611 } else if (!strncmp(option, "attempts:", 9)) {
2612 int retries = strtoint(val);
2613 if (retries == -1) return -1;
2614 if (retries > 255) retries = 255;
2615 if (!(flags & DNS_OPTION_MISC)) return 0;
2616 log(EVDNS_LOG_DEBUG, "Setting retries to %d", retries);
2617 global_max_retransmits = retries;
2618 }
2619 return 0;
2620 }
2621
2622 static void
2623 resolv_conf_parse_line(char *const start, int flags) {
2624 char *strtok_state;
2625 static const char *const delims = " \t";
2626 #define NEXT_TOKEN strtok_r(NULL, delims, &strtok_state)
2627
2628 char *const first_token = strtok_r(start, delims, &strtok_state);
2629 if (!first_token) return;
2630
2631 if (!strcmp(first_token, "nameserver") && (flags & DNS_OPTION_NAMESERVERS)) {
2632 const char *const nameserver = NEXT_TOKEN;
2633 struct in_addr ina;
2634
2635 if (inet_aton(nameserver, &ina)) {
2636 /* address is valid */
2637 evdns_nameserver_add(ina.s_addr);
2638 }
2639 } else if (!strcmp(first_token, "domain") && (flags & DNS_OPTION_SEARCH)) {
2640 const char *const domain = NEXT_TOKEN;
2641 if (domain) {
2642 search_postfix_clear();
2643 search_postfix_add(domain);
2644 }
2645 } else if (!strcmp(first_token, "search") && (flags & DNS_OPTION_SEARCH)) {
2646 const char *domain;
2647 search_postfix_clear();
2648
2649 while ((domain = NEXT_TOKEN)) {
2650 search_postfix_add(domain);
2651 }
2652 search_reverse();
2653 } else if (!strcmp(first_token, "options")) {
2654 const char *option;
2655 while ((option = NEXT_TOKEN)) {
2656 const char *val = strchr(option, ':');
2657 evdns_set_option(option, val ? val+1 : "", flags);
2658 }
2659 }
2660 #undef NEXT_TOKEN
2661 }
2662
2663 /* exported function */
2664 /* returns: */
2665 /* 0 no errors */
2666 /* 1 failed to open file */
2667 /* 2 failed to stat file */
2668 /* 3 file too large */
2669 /* 4 out of memory */
2670 /* 5 short read from file */
2671 int
2672 evdns_resolv_conf_parse(int flags, const char *const filename) {
2673 struct stat st;
2674 int fd, n, r;
2675 u8 *resolv;
2676 char *start;
2677 int err = 0;
2678
2679 log(EVDNS_LOG_DEBUG, "Parsing resolv.conf file %s", filename);
2680
2681 fd = open(filename, O_RDONLY);
2682 if (fd < 0) {
2683 evdns_resolv_set_defaults(flags);
2684 return 1;
2685 }
2686
2687 if (fstat(fd, &st)) { err = 2; goto out1; }
2688 if (!st.st_size) {
2689 evdns_resolv_set_defaults(flags);
2690 err = (flags & DNS_OPTION_NAMESERVERS) ? 6 : 0;
2691 goto out1;
2692 }
2693 if (st.st_size > 65535) { err = 3; goto out1; } /* no resolv.conf should be any bigger */
2694
2695 resolv = (u8 *) malloc((size_t)st.st_size + 1);
2696 if (!resolv) { err = 4; goto out1; }
2697
2698 n = 0;
2699 while ((r = read(fd, resolv+n, (size_t)st.st_size-n)) > 0) {
2700 n += r;
2701 if (n == st.st_size)
2702 break;
2703 assert(n < st.st_size);
2704 }
2705 if (r < 0) { err = 5; goto out2; }
2706 resolv[n] = 0; /* we malloced an extra byte; this should be fine. */
2707
2708 start = (char *) resolv;
2709 for (;;) {
2710 char *const newline = strchr(start, '\n');
2711 if (!newline) {
2712 resolv_conf_parse_line(start, flags);
2713 break;
2714 } else {
2715 *newline = 0;
2716 resolv_conf_parse_line(start, flags);
2717 start = newline + 1;
2718 }
2719 }
2720
2721 if (!server_head && (flags & DNS_OPTION_NAMESERVERS)) {
2722 /* no nameservers were configured. */
2723 evdns_nameserver_ip_add("127.0.0.1");
2724 err = 6;
2725 }
2726 if (flags & DNS_OPTION_SEARCH && (!global_search_state || global_search_state->num_domains == 0)) {
2727 search_set_from_hostname();
2728 }
2729
2730 out2:
2731 free(resolv);
2732 out1:
2733 close(fd);
2734 return err;
2735 }
2736
2737 #ifdef WIN32
2738 /* Add multiple nameservers from a space-or-comma-separated list. */
2739 static int
2740 evdns_nameserver_ip_add_line(const char *ips) {
2741 const char *addr;
2742 char *buf;
2743 int r;
2744 while (*ips) {
2745 while (ISSPACE(*ips) || *ips == ',' || *ips == '\t')
2746 ++ips;
2747 addr = ips;
2748 while (ISDIGIT(*ips) || *ips == '.' || *ips == ':')
2749 ++ips;
2750 buf = malloc(ips-addr+1);
2751 if (!buf) return 4;
2752 memcpy(buf, addr, ips-addr);
2753 buf[ips-addr] = '\0';
2754 r = evdns_nameserver_ip_add(buf);
2755 free(buf);
2756 if (r) return r;
2757 }
2758 return 0;
2759 }
2760
2761 typedef DWORD(WINAPI *GetNetworkParams_fn_t)(FIXED_INFO *, DWORD*);
2762
2763 /* Use the windows GetNetworkParams interface in iphlpapi.dll to */
2764 /* figure out what our nameservers are. */
2765 static int
2766 load_nameservers_with_getnetworkparams(void)
2767 {
2768 /* Based on MSDN examples and inspection of c-ares code. */
2769 FIXED_INFO *fixed;
2770 HMODULE handle = 0;
2771 ULONG size = sizeof(FIXED_INFO);
2772 void *buf = NULL;
2773 int status = 0, r, added_any;
2774 IP_ADDR_STRING *ns;
2775 GetNetworkParams_fn_t fn;
2776
2777 if (!(handle = LoadLibrary("iphlpapi.dll"))) {
2778 log(EVDNS_LOG_WARN, "Could not open iphlpapi.dll");
2779 status = -1;
2780 goto done;
2781 }
2782 if (!(fn = (GetNetworkParams_fn_t) GetProcAddress(handle, "GetNetworkParams"))) {
2783 log(EVDNS_LOG_WARN, "Could not get address of function.");
2784 status = -1;
2785 goto done;
2786 }
2787
2788 buf = malloc(size);
2789 if (!buf) { status = 4; goto done; }
2790 fixed = buf;
2791 r = fn(fixed, &size);
2792 if (r != ERROR_SUCCESS && r != ERROR_BUFFER_OVERFLOW) {
2793 status = -1;
2794 goto done;
2795 }
2796 if (r != ERROR_SUCCESS) {
2797 free(buf);
2798 buf = malloc(size);
2799 if (!buf) { status = 4; goto done; }
2800 fixed = buf;
2801 r = fn(fixed, &size);
2802 if (r != ERROR_SUCCESS) {
2803 log(EVDNS_LOG_DEBUG, "fn() failed.");
2804 status = -1;
2805 goto done;
2806 }
2807 }
2808
2809 assert(fixed);
2810 added_any = 0;
2811 ns = &(fixed->DnsServerList);
2812 while (ns) {
2813 r = evdns_nameserver_ip_add_line(ns->IpAddress.String);
2814 if (r) {
2815 log(EVDNS_LOG_DEBUG,"Could not add nameserver %s to list,error: %d",
2816 (ns->IpAddress.String),(int)GetLastError());
2817 status = r;
2818 goto done;
2819 } else {
2820 log(EVDNS_LOG_DEBUG,"Succesfully added %s as nameserver",ns->IpAddress.String);
2821 }
2822
2823 added_any++;
2824 ns = ns->Next;
2825 }
2826
2827 if (!added_any) {
2828 log(EVDNS_LOG_DEBUG, "No nameservers added.");
2829 status = -1;
2830 }
2831
2832 done:
2833 if (buf)
2834 free(buf);
2835 if (handle)
2836 FreeLibrary(handle);
2837 return status;
2838 }
2839
2840 static int
2841 config_nameserver_from_reg_key(HKEY key, const char *subkey)
2842 {
2843 char *buf;
2844 DWORD bufsz = 0, type = 0;
2845 int status = 0;
2846
2847 if (RegQueryValueEx(key, subkey, 0, &type, NULL, &bufsz)
2848 != ERROR_MORE_DATA)
2849 return -1;
2850 if (!(buf = malloc(bufsz)))
2851 return -1;
2852
2853 if (RegQueryValueEx(key, subkey, 0, &type, (LPBYTE)buf, &bufsz)
2854 == ERROR_SUCCESS && bufsz > 1) {
2855 status = evdns_nameserver_ip_add_line(buf);
2856 }
2857
2858 free(buf);
2859 return status;
2860 }
2861
2862 #define SERVICES_KEY "System\\CurrentControlSet\\Services\\"
2863 #define WIN_NS_9X_KEY SERVICES_KEY "VxD\\MSTCP"
2864 #define WIN_NS_NT_KEY SERVICES_KEY "Tcpip\\Parameters"
2865
2866 static int
2867 load_nameservers_from_registry(void)
2868 {
2869 int found = 0;
2870 int r;
2871 #define TRY(k, name) \
2872 if (!found && config_nameserver_from_reg_key(k,name) == 0) { \
2873 log(EVDNS_LOG_DEBUG,"Found nameservers in %s/%s",#k,name); \
2874 found = 1; \
2875 } else if (!found) { \
2876 log(EVDNS_LOG_DEBUG,"Didn't find nameservers in %s/%s", \
2877 #k,#name); \
2878 }
2879
2880 if (((int)GetVersion()) > 0) { /* NT */
2881 HKEY nt_key = 0, interfaces_key = 0;
2882
2883 if (RegOpenKeyEx(HKEY_LOCAL_MACHINE, WIN_NS_NT_KEY, 0,
2884 KEY_READ, &nt_key) != ERROR_SUCCESS) {
2885 log(EVDNS_LOG_DEBUG,"Couldn't open nt key, %d",(int)GetLastError());
2886 return -1;
2887 }
2888 r = RegOpenKeyEx(nt_key, "Interfaces", 0,
2889 KEY_QUERY_VALUE|KEY_ENUMERATE_SUB_KEYS,
2890 &interfaces_key);
2891 if (r != ERROR_SUCCESS) {
2892 log(EVDNS_LOG_DEBUG,"Couldn't open interfaces key, %d",(int)GetLastError());
2893 return -1;
2894 }
2895 TRY(nt_key, "NameServer");
2896 TRY(nt_key, "DhcpNameServer");
2897 TRY(interfaces_key, "NameServer");
2898 TRY(interfaces_key, "DhcpNameServer");
2899 RegCloseKey(interfaces_key);
2900 RegCloseKey(nt_key);
2901 } else {
2902 HKEY win_key = 0;
2903 if (RegOpenKeyEx(HKEY_LOCAL_MACHINE, WIN_NS_9X_KEY, 0,
2904 KEY_READ, &win_key) != ERROR_SUCCESS) {
2905 log(EVDNS_LOG_DEBUG, "Couldn't open registry key, %d", (int)GetLastError());
2906 return -1;
2907 }
2908 TRY(win_key, "NameServer");
2909 RegCloseKey(win_key);
2910 }
2911
2912 if (found == 0) {
2913 log(EVDNS_LOG_WARN,"Didn't find any nameservers.");
2914 }
2915
2916 return found ? 0 : -1;
2917 #undef TRY
2918 }
2919
2920 int
2921 evdns_config_windows_nameservers(void)
2922 {
2923 if (load_nameservers_with_getnetworkparams() == 0)
2924 return 0;
2925 return load_nameservers_from_registry();
2926 }
2927 #endif
2928
2929 int
2930 evdns_init(void)
2931 {
2932 int res = 0;
2933 #ifdef WIN32
2934 evdns_config_windows_nameservers();
2935 #else
2936 res = evdns_resolv_conf_parse(DNS_OPTIONS_ALL, "/etc/resolv.conf");
2937 #endif
2938
2939 return (res);
2940 }
2941
2942 const char *
2943 evdns_err_to_string(int err)
2944 {
2945 switch (err) {
2946 case DNS_ERR_NONE: return "no error";
2947 case DNS_ERR_FORMAT: return "misformatted query";
2948 case DNS_ERR_SERVERFAILED: return "server failed";
2949 case DNS_ERR_NOTEXIST: return "name does not exist";
2950 case DNS_ERR_NOTIMPL: return "query not implemented";
2951 case DNS_ERR_REFUSED: return "refused";
2952
2953 case DNS_ERR_TRUNCATED: return "reply truncated or ill-formed";
2954 case DNS_ERR_UNKNOWN: return "unknown";
2955 case DNS_ERR_TIMEOUT: return "request timed out";
2956 case DNS_ERR_SHUTDOWN: return "dns subsystem shut down";
2957 default: return "[Unknown error code]";
2958 }
2959 }
2960
2961 void
2962 evdns_shutdown(int fail_requests)
2963 {
2964 struct nameserver *server, *server_next;
2965 struct search_domain *dom, *dom_next;
2966
2967 while (req_head) {
2968 if (fail_requests)
2969 reply_callback(req_head, 0, DNS_ERR_SHUTDOWN, NULL);
2970 request_finished(req_head, &req_head);
2971 }
2972 while (req_waiting_head) {
2973 if (fail_requests)
2974 reply_callback(req_waiting_head, 0, DNS_ERR_SHUTDOWN, NULL);
2975 request_finished(req_waiting_head, &req_waiting_head);
2976 }
2977 global_requests_inflight = global_requests_waiting = 0;
2978
2979 for (server = server_head; server; server = server_next) {
2980 server_next = server->next;
2981 if (server->socket >= 0)
2982 CLOSE_SOCKET(server->socket);
2983 (void) event_del(&server->event);
2984 if (server->state == 0)
2985 (void) event_del(&server->timeout_event);
2986 free(server);
2987 if (server_next == server_head)
2988 break;
2989 }
2990 server_head = NULL;
2991 global_good_nameservers = 0;
2992
2993 if (global_search_state) {
2994 for (dom = global_search_state->head; dom; dom = dom_next) {
2995 dom_next = dom->next;
2996 free(dom);
2997 }
2998 free(global_search_state);
2999 global_search_state = NULL;
3000 }
3001 evdns_log_fn = NULL;
3002 }
3003
3004 #ifdef EVDNS_MAIN
3005 void
3006 main_callback(int result, char type, int count, int ttl,
3007 void *addrs, void *orig) {
3008 char *n = (char*)orig;
3009 int i;
3010 for (i = 0; i < count; ++i) {
3011 if (type == DNS_IPv4_A) {
3012 printf("%s: %s\n", n, debug_ntoa(((u32*)addrs)[i]));
3013 } else if (type == DNS_PTR) {
3014 printf("%s: %s\n", n, ((char**)addrs)[i]);
3015 }
3016 }
3017 if (!count) {
3018 printf("%s: No answer (%d)\n", n, result);
3019 }
3020 fflush(stdout);
3021 }
3022 void
3023 evdns_server_callback(struct evdns_server_request *req, void *data)
3024 {
3025 int i, r;
3026 (void)data;
3027 /* dummy; give 192.168.11.11 as an answer for all A questions,
3028 * give foo.bar.example.com as an answer for all PTR questions. */
3029 for (i = 0; i < req->nquestions; ++i) {
3030 u32 ans = htonl(0xc0a80b0bUL);
3031 if (req->questions[i]->type == EVDNS_TYPE_A &&
3032 req->questions[i]->class == EVDNS_CLASS_INET) {
3033 printf(" -- replying for %s (A)\n", req->questions[i]->name);
3034 r = evdns_server_request_add_a_reply(req, req->questions[i]->name,
3035 1, &ans, 10);
3036 if (r<0)
3037 printf("eeep, didn't work.\n");
3038 } else if (req->questions[i]->type == EVDNS_TYPE_PTR &&
3039 req->questions[i]->class == EVDNS_CLASS_INET) {
3040 printf(" -- replying for %s (PTR)\n", req->questions[i]->name);
3041 r = evdns_server_request_add_ptr_reply(req, NULL, req->questions[i]->name,
3042 "foo.bar.example.com", 10);
3043 } else {
3044 printf(" -- skipping %s [%d %d]\n", req->questions[i]->name,
3045 req->questions[i]->type, req->questions[i]->class);
3046 }
3047 }
3048
3049 r = evdns_request_respond(req, 0);
3050 if (r<0)
3051 printf("eeek, couldn't send reply.\n");
3052 }
3053
3054 void
3055 logfn(int is_warn, const char *msg) {
3056 (void) is_warn;
3057 fprintf(stderr, "%s\n", msg);
3058 }
3059 int
3060 main(int c, char **v) {
3061 int idx;
3062 int reverse = 0, verbose = 1, servertest = 0;
3063 if (c<2) {
3064 fprintf(stderr, "syntax: %s [-x] [-v] hostname\n", v[0]);
3065 fprintf(stderr, "syntax: %s [-servertest]\n", v[0]);
3066 return 1;
3067 }
3068 idx = 1;
3069 while (idx < c && v[idx][0] == '-') {
3070 if (!strcmp(v[idx], "-x"))
3071 reverse = 1;
3072 else if (!strcmp(v[idx], "-v"))
3073 verbose = 1;
3074 else if (!strcmp(v[idx], "-servertest"))
3075 servertest = 1;
3076 else
3077 fprintf(stderr, "Unknown option %s\n", v[idx]);
3078 ++idx;
3079 }
3080 event_init();
3081 if (verbose)
3082 evdns_set_log_fn(logfn);
3083 evdns_resolv_conf_parse(DNS_OPTION_NAMESERVERS, "/etc/resolv.conf");
3084 if (servertest) {
3085 int sock;
3086 struct sockaddr_in my_addr;
3087 sock = socket(PF_INET, SOCK_DGRAM, 0);
3088 fcntl(sock, F_SETFL, O_NONBLOCK);
3089 my_addr.sin_family = AF_INET;
3090 my_addr.sin_port = htons(10053);
3091 my_addr.sin_addr.s_addr = INADDR_ANY;
3092 if (bind(sock, (struct sockaddr*)&my_addr, sizeof(my_addr))<0) {
3093 perror("bind");
3094 exit(1);
3095 }
3096 evdns_add_server_port(sock, 0, evdns_server_callback, NULL);
3097 }
3098 for (; idx < c; ++idx) {
3099 if (reverse) {
3100 struct in_addr addr;
3101 if (!inet_aton(v[idx], &addr)) {
3102 fprintf(stderr, "Skipping non-IP %s\n", v[idx]);
3103 continue;
3104 }
3105 fprintf(stderr, "resolving %s...\n",v[idx]);
3106 evdns_resolve_reverse(&addr, 0, main_callback, v[idx]);
3107 } else {
3108 fprintf(stderr, "resolving (fwd) %s...\n",v[idx]);
3109 evdns_resolve_ipv4(v[idx], 0, main_callback, v[idx]);
3110 }
3111 }
3112 fflush(stdout);
3113 event_dispatch();
3114 return 0;
3115 }
3116 #endif
DragonFly BSD