Annotation of embedaddon/libevent/evdns.c, revision 1.1.1.1.2.1
1.1.1.1.2.1! misho 1: /* $Id: evdns.c,v 1.1.1.1 2012/02/21 23:02:54 misho Exp $ */
1.1 misho 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 DNS_USE_FTIME_FOR_ID
43: #include <sys/timeb.h>
44: #endif
45:
46: #ifndef DNS_USE_CPU_CLOCK_FOR_ID
47: #ifndef DNS_USE_GETTIMEOFDAY_FOR_ID
48: #ifndef DNS_USE_OPENSSL_FOR_ID
49: #ifndef DNS_USE_FTIME_FOR_ID
50: #error Must configure at least one id generation method.
51: #error Please see the documentation.
52: #endif
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: #ifndef _FORTIFY_SOURCE
78: #define _FORTIFY_SOURCE 3
79: #endif
80:
81: #include <string.h>
82: #include <fcntl.h>
83: #ifdef HAVE_SYS_TIME_H
84: #include <sys/time.h>
85: #endif
86: #ifdef HAVE_STDINT_H
87: #include <stdint.h>
88: #endif
89: #include <stdlib.h>
90: #include <string.h>
91: #include <errno.h>
92: #include <assert.h>
93: #ifdef HAVE_UNISTD_H
94: #include <unistd.h>
95: #endif
96: #include <limits.h>
97: #include <sys/stat.h>
98: #include <ctype.h>
99: #include <stdio.h>
100: #include <stdarg.h>
101:
102: #include "evdns.h"
103: #include "evutil.h"
104: #include "log.h"
105: #ifdef WIN32
106: #include <winsock2.h>
107: #include <windows.h>
108: #include <iphlpapi.h>
109: #include <io.h>
110: #else
111: #include <sys/socket.h>
112: #include <netinet/in.h>
113: #include <arpa/inet.h>
114: #endif
115:
116: #ifdef HAVE_NETINET_IN6_H
117: #include <netinet/in6.h>
118: #endif
119:
120: #define EVDNS_LOG_DEBUG 0
121: #define EVDNS_LOG_WARN 1
122:
123: #ifndef HOST_NAME_MAX
124: #define HOST_NAME_MAX 255
125: #endif
126:
127: #include <stdio.h>
128:
129: #undef MIN
130: #define MIN(a,b) ((a)<(b)?(a):(b))
131:
132: #ifdef __USE_ISOC99B
133: /* libevent doesn't work without this */
134: typedef ev_uint8_t u_char;
135: typedef unsigned int uint;
136: #endif
137: #include <event.h>
138:
139: #define u64 ev_uint64_t
140: #define u32 ev_uint32_t
141: #define u16 ev_uint16_t
142: #define u8 ev_uint8_t
143:
144: #ifdef WIN32
145: #define open _open
146: #define read _read
147: #define close _close
148: #define strdup _strdup
149: #endif
150:
151: #define MAX_ADDRS 32 /* maximum number of addresses from a single packet */
152: /* which we bother recording */
153:
154: #define TYPE_A EVDNS_TYPE_A
155: #define TYPE_CNAME 5
156: #define TYPE_PTR EVDNS_TYPE_PTR
157: #define TYPE_AAAA EVDNS_TYPE_AAAA
158:
159: #define CLASS_INET EVDNS_CLASS_INET
160:
1.1.1.1.2.1! misho 161: #ifdef HAVE_SETFD
! 162: #define FD_CLOSEONEXEC(x) do { \
! 163: if (fcntl(x, F_SETFD, 1) == -1) \
! 164: event_warn("fcntl(%d, F_SETFD)", x); \
! 165: } while (0)
! 166: #else
! 167: #define FD_CLOSEONEXEC(x) (void)0
! 168: #endif
! 169:
1.1 misho 170: struct request {
171: u8 *request; /* the dns packet data */
172: unsigned int request_len;
173: int reissue_count;
174: int tx_count; /* the number of times that this packet has been sent */
175: unsigned int request_type; /* TYPE_PTR or TYPE_A */
176: void *user_pointer; /* the pointer given to us for this request */
177: evdns_callback_type user_callback;
178: struct nameserver *ns; /* the server which we last sent it */
179:
180: /* elements used by the searching code */
181: int search_index;
182: struct search_state *search_state;
183: char *search_origname; /* needs to be free()ed */
184: int search_flags;
185:
186: /* these objects are kept in a circular list */
187: struct request *next, *prev;
188:
189: struct event timeout_event;
190:
191: u16 trans_id; /* the transaction id */
192: char request_appended; /* true if the request pointer is data which follows this struct */
193: char transmit_me; /* needs to be transmitted */
194: };
195:
196: #ifndef HAVE_STRUCT_IN6_ADDR
197: struct in6_addr {
198: u8 s6_addr[16];
199: };
200: #endif
201:
202: struct reply {
203: unsigned int type;
204: unsigned int have_answer;
205: union {
206: struct {
207: u32 addrcount;
208: u32 addresses[MAX_ADDRS];
209: } a;
210: struct {
211: u32 addrcount;
212: struct in6_addr addresses[MAX_ADDRS];
213: } aaaa;
214: struct {
215: char name[HOST_NAME_MAX];
216: } ptr;
217: } data;
218: };
219:
220: struct nameserver {
221: int socket; /* a connected UDP socket */
222: u32 address;
223: u16 port;
224: int failed_times; /* number of times which we have given this server a chance */
225: int timedout; /* number of times in a row a request has timed out */
226: struct event event;
227: /* these objects are kept in a circular list */
228: struct nameserver *next, *prev;
229: struct event timeout_event; /* used to keep the timeout for */
230: /* when we next probe this server. */
231: /* Valid if state == 0 */
232: char state; /* zero if we think that this server is down */
233: char choked; /* true if we have an EAGAIN from this server's socket */
234: char write_waiting; /* true if we are waiting for EV_WRITE events */
235: };
236:
237: static struct request *req_head = NULL, *req_waiting_head = NULL;
238: static struct nameserver *server_head = NULL;
239:
240: /* Represents a local port where we're listening for DNS requests. Right now, */
241: /* only UDP is supported. */
242: struct evdns_server_port {
243: int socket; /* socket we use to read queries and write replies. */
244: int refcnt; /* reference count. */
245: char choked; /* Are we currently blocked from writing? */
246: char closing; /* Are we trying to close this port, pending writes? */
247: evdns_request_callback_fn_type user_callback; /* Fn to handle requests */
248: void *user_data; /* Opaque pointer passed to user_callback */
249: struct event event; /* Read/write event */
250: /* circular list of replies that we want to write. */
251: struct server_request *pending_replies;
252: };
253:
254: /* Represents part of a reply being built. (That is, a single RR.) */
255: struct server_reply_item {
256: struct server_reply_item *next; /* next item in sequence. */
257: char *name; /* name part of the RR */
258: u16 type : 16; /* The RR type */
259: u16 class : 16; /* The RR class (usually CLASS_INET) */
260: u32 ttl; /* The RR TTL */
261: char is_name; /* True iff data is a label */
262: u16 datalen; /* Length of data; -1 if data is a label */
263: void *data; /* The contents of the RR */
264: };
265:
266: /* Represents a request that we've received as a DNS server, and holds */
267: /* the components of the reply as we're constructing it. */
268: struct server_request {
269: /* Pointers to the next and previous entries on the list of replies */
270: /* that we're waiting to write. Only set if we have tried to respond */
271: /* and gotten EAGAIN. */
272: struct server_request *next_pending;
273: struct server_request *prev_pending;
274:
275: u16 trans_id; /* Transaction id. */
276: struct evdns_server_port *port; /* Which port received this request on? */
277: struct sockaddr_storage addr; /* Where to send the response */
278: socklen_t addrlen; /* length of addr */
279:
280: int n_answer; /* how many answer RRs have been set? */
281: int n_authority; /* how many authority RRs have been set? */
282: int n_additional; /* how many additional RRs have been set? */
283:
284: struct server_reply_item *answer; /* linked list of answer RRs */
285: struct server_reply_item *authority; /* linked list of authority RRs */
286: struct server_reply_item *additional; /* linked list of additional RRs */
287:
288: /* Constructed response. Only set once we're ready to send a reply. */
289: /* Once this is set, the RR fields are cleared, and no more should be set. */
290: char *response;
291: size_t response_len;
292:
293: /* Caller-visible fields: flags, questions. */
294: struct evdns_server_request base;
295: };
296:
297: /* helper macro */
298: #define OFFSET_OF(st, member) ((off_t) (((char*)&((st*)0)->member)-(char*)0))
299:
300: /* Given a pointer to an evdns_server_request, get the corresponding */
301: /* server_request. */
302: #define TO_SERVER_REQUEST(base_ptr) \
303: ((struct server_request*) \
304: (((char*)(base_ptr) - OFFSET_OF(struct server_request, base))))
305:
306: /* The number of good nameservers that we have */
307: static int global_good_nameservers = 0;
308:
309: /* inflight requests are contained in the req_head list */
310: /* and are actually going out across the network */
311: static int global_requests_inflight = 0;
312: /* requests which aren't inflight are in the waiting list */
313: /* and are counted here */
314: static int global_requests_waiting = 0;
315:
316: static int global_max_requests_inflight = 64;
317:
318: static struct timeval global_timeout = {5, 0}; /* 5 seconds */
319: static int global_max_reissues = 1; /* a reissue occurs when we get some errors from the server */
320: static int global_max_retransmits = 3; /* number of times we'll retransmit a request which timed out */
321: /* number of timeouts in a row before we consider this server to be down */
322: static int global_max_nameserver_timeout = 3;
323:
324: /* These are the timeout values for nameservers. If we find a nameserver is down */
325: /* we try to probe it at intervals as given below. Values are in seconds. */
326: static const struct timeval global_nameserver_timeouts[] = {{10, 0}, {60, 0}, {300, 0}, {900, 0}, {3600, 0}};
327: static const int global_nameserver_timeouts_length = sizeof(global_nameserver_timeouts)/sizeof(struct timeval);
328:
329: static struct nameserver *nameserver_pick(void);
330: static void evdns_request_insert(struct request *req, struct request **head);
331: static void nameserver_ready_callback(int fd, short events, void *arg);
332: static int evdns_transmit(void);
333: static int evdns_request_transmit(struct request *req);
334: static void nameserver_send_probe(struct nameserver *const ns);
335: static void search_request_finished(struct request *const);
336: static int search_try_next(struct request *const req);
337: static int search_request_new(int type, const char *const name, int flags, evdns_callback_type user_callback, void *user_arg);
338: static void evdns_requests_pump_waiting_queue(void);
339: static u16 transaction_id_pick(void);
340: static struct request *request_new(int type, const char *name, int flags, evdns_callback_type callback, void *ptr);
341: static void request_submit(struct request *const req);
342:
343: static int server_request_free(struct server_request *req);
344: static void server_request_free_answers(struct server_request *req);
345: static void server_port_free(struct evdns_server_port *port);
346: static void server_port_ready_callback(int fd, short events, void *arg);
347:
348: static int strtoint(const char *const str);
349:
350: #ifdef WIN32
351: static int
352: last_error(int sock)
353: {
354: int optval, optvallen=sizeof(optval);
355: int err = WSAGetLastError();
356: if (err == WSAEWOULDBLOCK && sock >= 0) {
357: if (getsockopt(sock, SOL_SOCKET, SO_ERROR, (void*)&optval,
358: &optvallen))
359: return err;
360: if (optval)
361: return optval;
362: }
363: return err;
364:
365: }
366: static int
367: error_is_eagain(int err)
368: {
369: return err == EAGAIN || err == WSAEWOULDBLOCK;
370: }
371: static int
372: inet_aton(const char *c, struct in_addr *addr)
373: {
374: ev_uint32_t r;
375: if (strcmp(c, "255.255.255.255") == 0) {
376: addr->s_addr = 0xffffffffu;
377: } else {
378: r = inet_addr(c);
379: if (r == INADDR_NONE)
380: return 0;
381: addr->s_addr = r;
382: }
383: return 1;
384: }
385: #else
386: #define last_error(sock) (errno)
387: #define error_is_eagain(err) ((err) == EAGAIN)
388: #endif
389: #define CLOSE_SOCKET(s) EVUTIL_CLOSESOCKET(s)
390:
391: #define ISSPACE(c) isspace((int)(unsigned char)(c))
392: #define ISDIGIT(c) isdigit((int)(unsigned char)(c))
393:
394: static const char *
395: debug_ntoa(u32 address)
396: {
397: static char buf[32];
398: u32 a = ntohl(address);
399: evutil_snprintf(buf, sizeof(buf), "%d.%d.%d.%d",
400: (int)(u8)((a>>24)&0xff),
401: (int)(u8)((a>>16)&0xff),
402: (int)(u8)((a>>8 )&0xff),
403: (int)(u8)((a )&0xff));
404: return buf;
405: }
406:
407: static evdns_debug_log_fn_type evdns_log_fn = NULL;
408:
409: void
410: evdns_set_log_fn(evdns_debug_log_fn_type fn)
411: {
412: evdns_log_fn = fn;
413: }
414:
415: #ifdef __GNUC__
416: #define EVDNS_LOG_CHECK __attribute__ ((format(printf, 2, 3)))
417: #else
418: #define EVDNS_LOG_CHECK
419: #endif
420:
421: static void _evdns_log(int warn, const char *fmt, ...) EVDNS_LOG_CHECK;
422: static void
423: _evdns_log(int warn, const char *fmt, ...)
424: {
425: va_list args;
426: static char buf[512];
427: if (!evdns_log_fn)
428: return;
429: va_start(args,fmt);
430: evutil_vsnprintf(buf, sizeof(buf), fmt, args);
431: buf[sizeof(buf)-1] = '\0';
432: evdns_log_fn(warn, buf);
433: va_end(args);
434: }
435:
436: #define log _evdns_log
437:
438: /* This walks the list of inflight requests to find the */
439: /* one with a matching transaction id. Returns NULL on */
440: /* failure */
441: static struct request *
442: request_find_from_trans_id(u16 trans_id) {
443: struct request *req = req_head, *const started_at = req_head;
444:
445: if (req) {
446: do {
447: if (req->trans_id == trans_id) return req;
448: req = req->next;
449: } while (req != started_at);
450: }
451:
452: return NULL;
453: }
454:
455: /* a libevent callback function which is called when a nameserver */
456: /* has gone down and we want to test if it has came back to life yet */
457: static void
458: nameserver_prod_callback(int fd, short events, void *arg) {
459: struct nameserver *const ns = (struct nameserver *) arg;
460: (void)fd;
461: (void)events;
462:
463: nameserver_send_probe(ns);
464: }
465:
466: /* a libevent callback which is called when a nameserver probe (to see if */
467: /* it has come back to life) times out. We increment the count of failed_times */
468: /* and wait longer to send the next probe packet. */
469: static void
470: nameserver_probe_failed(struct nameserver *const ns) {
471: const struct timeval * timeout;
472: (void) evtimer_del(&ns->timeout_event);
473: if (ns->state == 1) {
474: /* This can happen if the nameserver acts in a way which makes us mark */
475: /* it as bad and then starts sending good replies. */
476: return;
477: }
478:
479: timeout =
480: &global_nameserver_timeouts[MIN(ns->failed_times,
481: global_nameserver_timeouts_length - 1)];
482: ns->failed_times++;
483:
484: if (evtimer_add(&ns->timeout_event, (struct timeval *) timeout) < 0) {
485: log(EVDNS_LOG_WARN,
486: "Error from libevent when adding timer event for %s",
487: debug_ntoa(ns->address));
488: /* ???? Do more? */
489: }
490: }
491:
492: /* called when a nameserver has been deemed to have failed. For example, too */
493: /* many packets have timed out etc */
494: static void
495: nameserver_failed(struct nameserver *const ns, const char *msg) {
496: struct request *req, *started_at;
497: /* if this nameserver has already been marked as failed */
498: /* then don't do anything */
499: if (!ns->state) return;
500:
501: log(EVDNS_LOG_WARN, "Nameserver %s has failed: %s",
502: debug_ntoa(ns->address), msg);
503: global_good_nameservers--;
504: assert(global_good_nameservers >= 0);
505: if (global_good_nameservers == 0) {
506: log(EVDNS_LOG_WARN, "All nameservers have failed");
507: }
508:
509: ns->state = 0;
510: ns->failed_times = 1;
511:
512: if (evtimer_add(&ns->timeout_event, (struct timeval *) &global_nameserver_timeouts[0]) < 0) {
513: log(EVDNS_LOG_WARN,
514: "Error from libevent when adding timer event for %s",
515: debug_ntoa(ns->address));
516: /* ???? Do more? */
517: }
518:
519: /* walk the list of inflight requests to see if any can be reassigned to */
520: /* a different server. Requests in the waiting queue don't have a */
521: /* nameserver assigned yet */
522:
523: /* if we don't have *any* good nameservers then there's no point */
524: /* trying to reassign requests to one */
525: if (!global_good_nameservers) return;
526:
527: req = req_head;
528: started_at = req_head;
529: if (req) {
530: do {
531: if (req->tx_count == 0 && req->ns == ns) {
532: /* still waiting to go out, can be moved */
533: /* to another server */
534: req->ns = nameserver_pick();
535: }
536: req = req->next;
537: } while (req != started_at);
538: }
539: }
540:
541: static void
542: nameserver_up(struct nameserver *const ns) {
543: if (ns->state) return;
544: log(EVDNS_LOG_WARN, "Nameserver %s is back up",
545: debug_ntoa(ns->address));
546: evtimer_del(&ns->timeout_event);
547: ns->state = 1;
548: ns->failed_times = 0;
549: ns->timedout = 0;
550: global_good_nameservers++;
551: }
552:
553: static void
554: request_trans_id_set(struct request *const req, const u16 trans_id) {
555: req->trans_id = trans_id;
556: *((u16 *) req->request) = htons(trans_id);
557: }
558:
559: /* Called to remove a request from a list and dealloc it. */
560: /* head is a pointer to the head of the list it should be */
561: /* removed from or NULL if the request isn't in a list. */
562: static void
563: request_finished(struct request *const req, struct request **head) {
564: if (head) {
565: if (req->next == req) {
566: /* only item in the list */
567: *head = NULL;
568: } else {
569: req->next->prev = req->prev;
570: req->prev->next = req->next;
571: if (*head == req) *head = req->next;
572: }
573: }
574:
575: log(EVDNS_LOG_DEBUG, "Removing timeout for request %lx",
576: (unsigned long) req);
577: evtimer_del(&req->timeout_event);
578:
579: search_request_finished(req);
580: global_requests_inflight--;
581:
582: if (!req->request_appended) {
583: /* need to free the request data on it's own */
584: free(req->request);
585: } else {
586: /* the request data is appended onto the header */
587: /* so everything gets free()ed when we: */
588: }
589:
590: free(req);
591:
592: evdns_requests_pump_waiting_queue();
593: }
594:
595: /* This is called when a server returns a funny error code. */
596: /* We try the request again with another server. */
597: /* */
598: /* return: */
599: /* 0 ok */
600: /* 1 failed/reissue is pointless */
601: static int
602: request_reissue(struct request *req) {
603: const struct nameserver *const last_ns = req->ns;
604: /* the last nameserver should have been marked as failing */
605: /* by the caller of this function, therefore pick will try */
606: /* not to return it */
607: req->ns = nameserver_pick();
608: if (req->ns == last_ns) {
609: /* ... but pick did return it */
610: /* not a lot of point in trying again with the */
611: /* same server */
612: return 1;
613: }
614:
615: req->reissue_count++;
616: req->tx_count = 0;
617: req->transmit_me = 1;
618:
619: return 0;
620: }
621:
622: /* this function looks for space on the inflight queue and promotes */
623: /* requests from the waiting queue if it can. */
624: static void
625: evdns_requests_pump_waiting_queue(void) {
626: while (global_requests_inflight < global_max_requests_inflight &&
627: global_requests_waiting) {
628: struct request *req;
629: /* move a request from the waiting queue to the inflight queue */
630: assert(req_waiting_head);
631: if (req_waiting_head->next == req_waiting_head) {
632: /* only one item in the queue */
633: req = req_waiting_head;
634: req_waiting_head = NULL;
635: } else {
636: req = req_waiting_head;
637: req->next->prev = req->prev;
638: req->prev->next = req->next;
639: req_waiting_head = req->next;
640: }
641:
642: global_requests_waiting--;
643: global_requests_inflight++;
644:
645: req->ns = nameserver_pick();
646: request_trans_id_set(req, transaction_id_pick());
647:
648: evdns_request_insert(req, &req_head);
649: evdns_request_transmit(req);
650: evdns_transmit();
651: }
652: }
653:
654: static void
655: reply_callback(struct request *const req, u32 ttl, u32 err, struct reply *reply) {
656: switch (req->request_type) {
657: case TYPE_A:
658: if (reply)
659: req->user_callback(DNS_ERR_NONE, DNS_IPv4_A,
660: reply->data.a.addrcount, ttl,
661: reply->data.a.addresses,
662: req->user_pointer);
663: else
664: req->user_callback(err, 0, 0, 0, NULL, req->user_pointer);
665: return;
666: case TYPE_PTR:
667: if (reply) {
668: char *name = reply->data.ptr.name;
669: req->user_callback(DNS_ERR_NONE, DNS_PTR, 1, ttl,
670: &name, req->user_pointer);
671: } else {
672: req->user_callback(err, 0, 0, 0, NULL,
673: req->user_pointer);
674: }
675: return;
676: case TYPE_AAAA:
677: if (reply)
678: req->user_callback(DNS_ERR_NONE, DNS_IPv6_AAAA,
679: reply->data.aaaa.addrcount, ttl,
680: reply->data.aaaa.addresses,
681: req->user_pointer);
682: else
683: req->user_callback(err, 0, 0, 0, NULL, req->user_pointer);
684: return;
685: }
686: assert(0);
687: }
688:
689: /* this processes a parsed reply packet */
690: static void
691: reply_handle(struct request *const req, u16 flags, u32 ttl, struct reply *reply) {
692: int error;
693: static const int error_codes[] = {
694: DNS_ERR_FORMAT, DNS_ERR_SERVERFAILED, DNS_ERR_NOTEXIST,
695: DNS_ERR_NOTIMPL, DNS_ERR_REFUSED
696: };
697:
698: if (flags & 0x020f || !reply || !reply->have_answer) {
699: /* there was an error */
700: if (flags & 0x0200) {
701: error = DNS_ERR_TRUNCATED;
702: } else {
703: u16 error_code = (flags & 0x000f) - 1;
704: if (error_code > 4) {
705: error = DNS_ERR_UNKNOWN;
706: } else {
707: error = error_codes[error_code];
708: }
709: }
710:
711: switch(error) {
712: case DNS_ERR_NOTIMPL:
713: case DNS_ERR_REFUSED:
714: /* we regard these errors as marking a bad nameserver */
715: if (req->reissue_count < global_max_reissues) {
716: char msg[64];
717: evutil_snprintf(msg, sizeof(msg),
718: "Bad response %d (%s)",
719: error, evdns_err_to_string(error));
720: nameserver_failed(req->ns, msg);
721: if (!request_reissue(req)) return;
722: }
723: break;
724: case DNS_ERR_SERVERFAILED:
725: /* rcode 2 (servfailed) sometimes means "we
726: * are broken" and sometimes (with some binds)
727: * means "that request was very confusing."
728: * Treat this as a timeout, not a failure.
729: */
730: log(EVDNS_LOG_DEBUG, "Got a SERVERFAILED from nameserver %s; "
731: "will allow the request to time out.",
732: debug_ntoa(req->ns->address));
733: break;
734: default:
735: /* we got a good reply from the nameserver */
736: nameserver_up(req->ns);
737: }
738:
739: if (req->search_state && req->request_type != TYPE_PTR) {
740: /* if we have a list of domains to search in,
741: * try the next one */
742: if (!search_try_next(req)) {
743: /* a new request was issued so this
744: * request is finished and */
745: /* the user callback will be made when
746: * that request (or a */
747: /* child of it) finishes. */
748: request_finished(req, &req_head);
749: return;
750: }
751: }
752:
753: /* all else failed. Pass the failure up */
754: reply_callback(req, 0, error, NULL);
755: request_finished(req, &req_head);
756: } else {
757: /* all ok, tell the user */
758: reply_callback(req, ttl, 0, reply);
759: nameserver_up(req->ns);
760: request_finished(req, &req_head);
761: }
762: }
763:
764: static int
765: name_parse(u8 *packet, int length, int *idx, char *name_out, int name_out_len) {
766: int name_end = -1;
767: int j = *idx;
768: int ptr_count = 0;
769: #define GET32(x) do { if (j + 4 > length) goto err; memcpy(&_t32, packet + j, 4); j += 4; x = ntohl(_t32); } while(0)
770: #define GET16(x) do { if (j + 2 > length) goto err; memcpy(&_t, packet + j, 2); j += 2; x = ntohs(_t); } while(0)
771: #define GET8(x) do { if (j >= length) goto err; x = packet[j++]; } while(0)
772:
773: char *cp = name_out;
774: const char *const end = name_out + name_out_len;
775:
776: /* Normally, names are a series of length prefixed strings terminated */
777: /* with a length of 0 (the lengths are u8's < 63). */
778: /* However, the length can start with a pair of 1 bits and that */
779: /* means that the next 14 bits are a pointer within the current */
780: /* packet. */
781:
782: for(;;) {
783: u8 label_len;
784: if (j >= length) return -1;
785: GET8(label_len);
786: if (!label_len) break;
787: if (label_len & 0xc0) {
788: u8 ptr_low;
789: GET8(ptr_low);
790: if (name_end < 0) name_end = j;
791: j = (((int)label_len & 0x3f) << 8) + ptr_low;
792: /* Make sure that the target offset is in-bounds. */
793: if (j < 0 || j >= length) return -1;
794: /* If we've jumped more times than there are characters in the
795: * message, we must have a loop. */
796: if (++ptr_count > length) return -1;
797: continue;
798: }
799: if (label_len > 63) return -1;
800: if (cp != name_out) {
801: if (cp + 1 >= end) return -1;
802: *cp++ = '.';
803: }
804: if (cp + label_len >= end) return -1;
805: memcpy(cp, packet + j, label_len);
806: cp += label_len;
807: j += label_len;
808: }
809: if (cp >= end) return -1;
810: *cp = '\0';
811: if (name_end < 0)
812: *idx = j;
813: else
814: *idx = name_end;
815: return 0;
816: err:
817: return -1;
818: }
819:
820: /* parses a raw request from a nameserver */
821: static int
822: reply_parse(u8 *packet, int length) {
823: int j = 0, k = 0; /* index into packet */
824: u16 _t; /* used by the macros */
825: u32 _t32; /* used by the macros */
826: char tmp_name[256], cmp_name[256]; /* used by the macros */
827:
828: u16 trans_id, questions, answers, authority, additional, datalength;
829: u16 flags = 0;
830: u32 ttl, ttl_r = 0xffffffff;
831: struct reply reply;
832: struct request *req = NULL;
833: unsigned int i;
834:
835: GET16(trans_id);
836: GET16(flags);
837: GET16(questions);
838: GET16(answers);
839: GET16(authority);
840: GET16(additional);
841: (void) authority; /* suppress "unused variable" warnings. */
842: (void) additional; /* suppress "unused variable" warnings. */
843:
844: req = request_find_from_trans_id(trans_id);
845: if (!req) return -1;
846:
847: memset(&reply, 0, sizeof(reply));
848:
849: /* If it's not an answer, it doesn't correspond to any request. */
850: if (!(flags & 0x8000)) return -1; /* must be an answer */
851: if (flags & 0x020f) {
852: /* there was an error */
853: goto err;
854: }
855: /* if (!answers) return; */ /* must have an answer of some form */
856:
857: /* This macro skips a name in the DNS reply. */
858: #define SKIP_NAME \
859: do { tmp_name[0] = '\0'; \
860: if (name_parse(packet, length, &j, tmp_name, sizeof(tmp_name))<0)\
861: goto err; \
862: } while(0)
863: #define TEST_NAME \
864: do { tmp_name[0] = '\0'; \
865: cmp_name[0] = '\0'; \
866: k = j; \
867: if (name_parse(packet, length, &j, tmp_name, sizeof(tmp_name))<0)\
868: goto err; \
869: if (name_parse(req->request, req->request_len, &k, cmp_name, sizeof(cmp_name))<0) \
870: goto err; \
871: if (memcmp(tmp_name, cmp_name, strlen (tmp_name)) != 0) \
872: return (-1); /* we ignore mismatching names */ \
873: } while(0)
874:
875: reply.type = req->request_type;
876:
877: /* skip over each question in the reply */
878: for (i = 0; i < questions; ++i) {
879: /* the question looks like
880: * <label:name><u16:type><u16:class>
881: */
882: TEST_NAME;
883: j += 4;
884: if (j > length) goto err;
885: }
886:
887: /* now we have the answer section which looks like
888: * <label:name><u16:type><u16:class><u32:ttl><u16:len><data...>
889: */
890:
891: for (i = 0; i < answers; ++i) {
892: u16 type, class;
893:
894: SKIP_NAME;
895: GET16(type);
896: GET16(class);
897: GET32(ttl);
898: GET16(datalength);
899:
900: if (type == TYPE_A && class == CLASS_INET) {
901: int addrcount, addrtocopy;
902: if (req->request_type != TYPE_A) {
903: j += datalength; continue;
904: }
905: if ((datalength & 3) != 0) /* not an even number of As. */
906: goto err;
907: addrcount = datalength >> 2;
908: addrtocopy = MIN(MAX_ADDRS - reply.data.a.addrcount, (unsigned)addrcount);
909:
910: ttl_r = MIN(ttl_r, ttl);
911: /* we only bother with the first four addresses. */
912: if (j + 4*addrtocopy > length) goto err;
913: memcpy(&reply.data.a.addresses[reply.data.a.addrcount],
914: packet + j, 4*addrtocopy);
915: j += 4*addrtocopy;
916: reply.data.a.addrcount += addrtocopy;
917: reply.have_answer = 1;
918: if (reply.data.a.addrcount == MAX_ADDRS) break;
919: } else if (type == TYPE_PTR && class == CLASS_INET) {
920: if (req->request_type != TYPE_PTR) {
921: j += datalength; continue;
922: }
923: if (name_parse(packet, length, &j, reply.data.ptr.name,
924: sizeof(reply.data.ptr.name))<0)
925: goto err;
926: ttl_r = MIN(ttl_r, ttl);
927: reply.have_answer = 1;
928: break;
929: } else if (type == TYPE_AAAA && class == CLASS_INET) {
930: int addrcount, addrtocopy;
931: if (req->request_type != TYPE_AAAA) {
932: j += datalength; continue;
933: }
934: if ((datalength & 15) != 0) /* not an even number of AAAAs. */
935: goto err;
936: addrcount = datalength >> 4; /* each address is 16 bytes long */
937: addrtocopy = MIN(MAX_ADDRS - reply.data.aaaa.addrcount, (unsigned)addrcount);
938: ttl_r = MIN(ttl_r, ttl);
939:
940: /* we only bother with the first four addresses. */
941: if (j + 16*addrtocopy > length) goto err;
942: memcpy(&reply.data.aaaa.addresses[reply.data.aaaa.addrcount],
943: packet + j, 16*addrtocopy);
944: reply.data.aaaa.addrcount += addrtocopy;
945: j += 16*addrtocopy;
946: reply.have_answer = 1;
947: if (reply.data.aaaa.addrcount == MAX_ADDRS) break;
948: } else {
949: /* skip over any other type of resource */
950: j += datalength;
951: }
952: }
953:
954: reply_handle(req, flags, ttl_r, &reply);
955: return 0;
956: err:
957: if (req)
958: reply_handle(req, flags, 0, NULL);
959: return -1;
960: }
961:
962: /* Parse a raw request (packet,length) sent to a nameserver port (port) from */
963: /* a DNS client (addr,addrlen), and if it's well-formed, call the corresponding */
964: /* callback. */
965: static int
966: request_parse(u8 *packet, int length, struct evdns_server_port *port, struct sockaddr *addr, socklen_t addrlen)
967: {
968: int j = 0; /* index into packet */
969: u16 _t; /* used by the macros */
970: char tmp_name[256]; /* used by the macros */
971:
972: int i;
973: u16 trans_id, flags, questions, answers, authority, additional;
974: struct server_request *server_req = NULL;
975:
976: /* Get the header fields */
977: GET16(trans_id);
978: GET16(flags);
979: GET16(questions);
980: GET16(answers);
981: GET16(authority);
982: GET16(additional);
983:
984: if (flags & 0x8000) return -1; /* Must not be an answer. */
985: flags &= 0x0110; /* Only RD and CD get preserved. */
986:
987: server_req = malloc(sizeof(struct server_request));
988: if (server_req == NULL) return -1;
989: memset(server_req, 0, sizeof(struct server_request));
990:
991: server_req->trans_id = trans_id;
992: memcpy(&server_req->addr, addr, addrlen);
993: server_req->addrlen = addrlen;
994:
995: server_req->base.flags = flags;
996: server_req->base.nquestions = 0;
997: server_req->base.questions = malloc(sizeof(struct evdns_server_question *) * questions);
998: if (server_req->base.questions == NULL)
999: goto err;
1000:
1001: for (i = 0; i < questions; ++i) {
1002: u16 type, class;
1003: struct evdns_server_question *q;
1004: int namelen;
1005: if (name_parse(packet, length, &j, tmp_name, sizeof(tmp_name))<0)
1006: goto err;
1007: GET16(type);
1008: GET16(class);
1009: namelen = strlen(tmp_name);
1010: q = malloc(sizeof(struct evdns_server_question) + namelen);
1011: if (!q)
1012: goto err;
1013: q->type = type;
1014: q->dns_question_class = class;
1015: memcpy(q->name, tmp_name, namelen+1);
1016: server_req->base.questions[server_req->base.nquestions++] = q;
1017: }
1018:
1019: /* Ignore answers, authority, and additional. */
1020:
1021: server_req->port = port;
1022: port->refcnt++;
1023:
1024: /* Only standard queries are supported. */
1025: if (flags & 0x7800) {
1026: evdns_server_request_respond(&(server_req->base), DNS_ERR_NOTIMPL);
1027: return -1;
1028: }
1029:
1030: port->user_callback(&(server_req->base), port->user_data);
1031:
1032: return 0;
1033: err:
1034: if (server_req) {
1035: if (server_req->base.questions) {
1036: for (i = 0; i < server_req->base.nquestions; ++i)
1037: free(server_req->base.questions[i]);
1038: free(server_req->base.questions);
1039: }
1040: free(server_req);
1041: }
1042: return -1;
1043:
1044: #undef SKIP_NAME
1045: #undef GET32
1046: #undef GET16
1047: #undef GET8
1048: }
1049:
1050: static u16
1051: default_transaction_id_fn(void)
1052: {
1053: u16 trans_id;
1054: #ifdef DNS_USE_CPU_CLOCK_FOR_ID
1055: struct timespec ts;
1056: static int clkid = -1;
1057: if (clkid == -1) {
1058: clkid = CLOCK_REALTIME;
1059: #ifdef CLOCK_MONOTONIC
1060: if (clock_gettime(CLOCK_MONOTONIC, &ts) != -1)
1061: clkid = CLOCK_MONOTONIC;
1062: #endif
1063: }
1064: if (clock_gettime(clkid, &ts) == -1)
1065: event_err(1, "clock_gettime");
1066: trans_id = ts.tv_nsec & 0xffff;
1067: #endif
1068:
1069: #ifdef DNS_USE_FTIME_FOR_ID
1070: struct _timeb tb;
1071: _ftime(&tb);
1072: trans_id = tb.millitm & 0xffff;
1073: #endif
1074:
1075: #ifdef DNS_USE_GETTIMEOFDAY_FOR_ID
1076: struct timeval tv;
1077: evutil_gettimeofday(&tv, NULL);
1078: trans_id = tv.tv_usec & 0xffff;
1079: #endif
1080:
1081: #ifdef DNS_USE_OPENSSL_FOR_ID
1082: if (RAND_pseudo_bytes((u8 *) &trans_id, 2) == -1) {
1083: /* in the case that the RAND call fails we back */
1084: /* down to using gettimeofday. */
1085: /*
1086: struct timeval tv;
1087: evutil_gettimeofday(&tv, NULL);
1088: trans_id = tv.tv_usec & 0xffff;
1089: */
1090: abort();
1091: }
1092: #endif
1093: return trans_id;
1094: }
1095:
1096: static ev_uint16_t (*trans_id_function)(void) = default_transaction_id_fn;
1097:
1098: void
1099: evdns_set_transaction_id_fn(ev_uint16_t (*fn)(void))
1100: {
1101: if (fn)
1102: trans_id_function = fn;
1103: else
1104: trans_id_function = default_transaction_id_fn;
1105: }
1106:
1107: /* Try to choose a strong transaction id which isn't already in flight */
1108: static u16
1109: transaction_id_pick(void) {
1110: for (;;) {
1111: u16 trans_id = trans_id_function();
1112:
1113: if (trans_id == 0xffff) continue;
1.1.1.1.2.1! misho 1114:
! 1115: if (request_find_from_trans_id(trans_id) == NULL)
! 1116: return trans_id;
1.1 misho 1117: }
1118: }
1119:
1120: /* choose a namesever to use. This function will try to ignore */
1121: /* nameservers which we think are down and load balance across the rest */
1122: /* by updating the server_head global each time. */
1123: static struct nameserver *
1124: nameserver_pick(void) {
1125: struct nameserver *started_at = server_head, *picked;
1126: if (!server_head) return NULL;
1127:
1128: /* if we don't have any good nameservers then there's no */
1129: /* point in trying to find one. */
1130: if (!global_good_nameservers) {
1131: server_head = server_head->next;
1132: return server_head;
1133: }
1134:
1135: /* remember that nameservers are in a circular list */
1136: for (;;) {
1137: if (server_head->state) {
1138: /* we think this server is currently good */
1139: picked = server_head;
1140: server_head = server_head->next;
1141: return picked;
1142: }
1143:
1144: server_head = server_head->next;
1145: if (server_head == started_at) {
1146: /* all the nameservers seem to be down */
1147: /* so we just return this one and hope for the */
1148: /* best */
1149: assert(global_good_nameservers == 0);
1150: picked = server_head;
1151: server_head = server_head->next;
1152: return picked;
1153: }
1154: }
1155: }
1156:
1157: static int
1158: address_is_correct(struct nameserver *ns, struct sockaddr *sa, socklen_t slen)
1159: {
1160: struct sockaddr_in *sin = (struct sockaddr_in*) sa;
1161: if (sa->sa_family != AF_INET || slen != sizeof(struct sockaddr_in))
1162: return 0;
1163: if (sin->sin_addr.s_addr != ns->address)
1164: return 0;
1165: return 1;
1166: }
1167:
1168: /* this is called when a namesever socket is ready for reading */
1169: static void
1170: nameserver_read(struct nameserver *ns) {
1171: u8 packet[1500];
1172: struct sockaddr_storage ss;
1173: socklen_t addrlen = sizeof(ss);
1174:
1175: for (;;) {
1176: const int r = recvfrom(ns->socket, packet, sizeof(packet), 0,
1177: (struct sockaddr*)&ss, &addrlen);
1178: if (r < 0) {
1179: int err = last_error(ns->socket);
1180: if (error_is_eagain(err)) return;
1181: nameserver_failed(ns, strerror(err));
1182: return;
1183: }
1184: if (!address_is_correct(ns, (struct sockaddr*)&ss, addrlen)) {
1185: log(EVDNS_LOG_WARN, "Address mismatch on received "
1186: "DNS packet.");
1187: return;
1188: }
1189: ns->timedout = 0;
1190: reply_parse(packet, r);
1191: }
1192: }
1193:
1194: /* Read a packet from a DNS client on a server port s, parse it, and */
1195: /* act accordingly. */
1196: static void
1197: server_port_read(struct evdns_server_port *s) {
1198: u8 packet[1500];
1199: struct sockaddr_storage addr;
1200: socklen_t addrlen;
1201: int r;
1202:
1203: for (;;) {
1204: addrlen = sizeof(struct sockaddr_storage);
1205: r = recvfrom(s->socket, packet, sizeof(packet), 0,
1206: (struct sockaddr*) &addr, &addrlen);
1207: if (r < 0) {
1208: int err = last_error(s->socket);
1209: if (error_is_eagain(err)) return;
1210: log(EVDNS_LOG_WARN, "Error %s (%d) while reading request.",
1211: strerror(err), err);
1212: return;
1213: }
1214: request_parse(packet, r, s, (struct sockaddr*) &addr, addrlen);
1215: }
1216: }
1217:
1218: /* Try to write all pending replies on a given DNS server port. */
1219: static void
1220: server_port_flush(struct evdns_server_port *port)
1221: {
1222: while (port->pending_replies) {
1223: struct server_request *req = port->pending_replies;
1224: int r = sendto(port->socket, req->response, req->response_len, 0,
1225: (struct sockaddr*) &req->addr, req->addrlen);
1226: if (r < 0) {
1227: int err = last_error(port->socket);
1228: if (error_is_eagain(err))
1229: return;
1230: log(EVDNS_LOG_WARN, "Error %s (%d) while writing response to port; dropping", strerror(err), err);
1231: }
1232: if (server_request_free(req)) {
1233: /* we released the last reference to req->port. */
1234: return;
1235: }
1236: }
1237:
1238: /* We have no more pending requests; stop listening for 'writeable' events. */
1239: (void) event_del(&port->event);
1240: event_set(&port->event, port->socket, EV_READ | EV_PERSIST,
1241: server_port_ready_callback, port);
1242: if (event_add(&port->event, NULL) < 0) {
1243: log(EVDNS_LOG_WARN, "Error from libevent when adding event for DNS server.");
1244: /* ???? Do more? */
1245: }
1246: }
1247:
1248: /* set if we are waiting for the ability to write to this server. */
1249: /* if waiting is true then we ask libevent for EV_WRITE events, otherwise */
1250: /* we stop these events. */
1251: static void
1252: nameserver_write_waiting(struct nameserver *ns, char waiting) {
1253: if (ns->write_waiting == waiting) return;
1254:
1255: ns->write_waiting = waiting;
1256: (void) event_del(&ns->event);
1257: event_set(&ns->event, ns->socket, EV_READ | (waiting ? EV_WRITE : 0) | EV_PERSIST,
1258: nameserver_ready_callback, ns);
1259: if (event_add(&ns->event, NULL) < 0) {
1260: log(EVDNS_LOG_WARN, "Error from libevent when adding event for %s",
1261: debug_ntoa(ns->address));
1262: /* ???? Do more? */
1263: }
1264: }
1265:
1266: /* a callback function. Called by libevent when the kernel says that */
1267: /* a nameserver socket is ready for writing or reading */
1268: static void
1269: nameserver_ready_callback(int fd, short events, void *arg) {
1270: struct nameserver *ns = (struct nameserver *) arg;
1271: (void)fd;
1272:
1273: if (events & EV_WRITE) {
1274: ns->choked = 0;
1275: if (!evdns_transmit()) {
1276: nameserver_write_waiting(ns, 0);
1277: }
1278: }
1279: if (events & EV_READ) {
1280: nameserver_read(ns);
1281: }
1282: }
1283:
1284: /* a callback function. Called by libevent when the kernel says that */
1285: /* a server socket is ready for writing or reading. */
1286: static void
1287: server_port_ready_callback(int fd, short events, void *arg) {
1288: struct evdns_server_port *port = (struct evdns_server_port *) arg;
1289: (void) fd;
1290:
1291: if (events & EV_WRITE) {
1292: port->choked = 0;
1293: server_port_flush(port);
1294: }
1295: if (events & EV_READ) {
1296: server_port_read(port);
1297: }
1298: }
1299:
1300: /* This is an inefficient representation; only use it via the dnslabel_table_*
1301: * functions, so that is can be safely replaced with something smarter later. */
1302: #define MAX_LABELS 128
1303: /* Structures used to implement name compression */
1304: struct dnslabel_entry { char *v; off_t pos; };
1305: struct dnslabel_table {
1306: int n_labels; /* number of current entries */
1307: /* map from name to position in message */
1308: struct dnslabel_entry labels[MAX_LABELS];
1309: };
1310:
1311: /* Initialize dnslabel_table. */
1312: static void
1313: dnslabel_table_init(struct dnslabel_table *table)
1314: {
1315: table->n_labels = 0;
1316: }
1317:
1318: /* Free all storage held by table, but not the table itself. */
1319: static void
1320: dnslabel_clear(struct dnslabel_table *table)
1321: {
1322: int i;
1323: for (i = 0; i < table->n_labels; ++i)
1324: free(table->labels[i].v);
1325: table->n_labels = 0;
1326: }
1327:
1328: /* return the position of the label in the current message, or -1 if the label */
1329: /* hasn't been used yet. */
1330: static int
1331: dnslabel_table_get_pos(const struct dnslabel_table *table, const char *label)
1332: {
1333: int i;
1334: for (i = 0; i < table->n_labels; ++i) {
1335: if (!strcmp(label, table->labels[i].v))
1336: return table->labels[i].pos;
1337: }
1338: return -1;
1339: }
1340:
1341: /* remember that we've used the label at position pos */
1342: static int
1343: dnslabel_table_add(struct dnslabel_table *table, const char *label, off_t pos)
1344: {
1345: char *v;
1346: int p;
1347: if (table->n_labels == MAX_LABELS)
1348: return (-1);
1349: v = strdup(label);
1350: if (v == NULL)
1351: return (-1);
1352: p = table->n_labels++;
1353: table->labels[p].v = v;
1354: table->labels[p].pos = pos;
1355:
1356: return (0);
1357: }
1358:
1359: /* Converts a string to a length-prefixed set of DNS labels, starting */
1360: /* at buf[j]. name and buf must not overlap. name_len should be the length */
1361: /* of name. table is optional, and is used for compression. */
1362: /* */
1363: /* Input: abc.def */
1364: /* Output: <3>abc<3>def<0> */
1365: /* */
1366: /* Returns the first index after the encoded name, or negative on error. */
1367: /* -1 label was > 63 bytes */
1368: /* -2 name too long to fit in buffer. */
1369: /* */
1370: static off_t
1371: dnsname_to_labels(u8 *const buf, size_t buf_len, off_t j,
1372: const char *name, const int name_len,
1373: struct dnslabel_table *table) {
1374: const char *end = name + name_len;
1375: int ref = 0;
1376: u16 _t;
1377:
1378: #define APPEND16(x) do { \
1379: if (j + 2 > (off_t)buf_len) \
1380: goto overflow; \
1381: _t = htons(x); \
1382: memcpy(buf + j, &_t, 2); \
1383: j += 2; \
1384: } while (0)
1385: #define APPEND32(x) do { \
1386: if (j + 4 > (off_t)buf_len) \
1387: goto overflow; \
1388: _t32 = htonl(x); \
1389: memcpy(buf + j, &_t32, 4); \
1390: j += 4; \
1391: } while (0)
1392:
1393: if (name_len > 255) return -2;
1394:
1395: for (;;) {
1396: const char *const start = name;
1397: if (table && (ref = dnslabel_table_get_pos(table, name)) >= 0) {
1398: APPEND16(ref | 0xc000);
1399: return j;
1400: }
1401: name = strchr(name, '.');
1402: if (!name) {
1403: const unsigned int label_len = end - start;
1404: if (label_len > 63) return -1;
1405: if ((size_t)(j+label_len+1) > buf_len) return -2;
1406: if (table) dnslabel_table_add(table, start, j);
1407: buf[j++] = label_len;
1408:
1409: memcpy(buf + j, start, end - start);
1410: j += end - start;
1411: break;
1412: } else {
1413: /* append length of the label. */
1414: const unsigned int label_len = name - start;
1415: if (label_len > 63) return -1;
1416: if ((size_t)(j+label_len+1) > buf_len) return -2;
1417: if (table) dnslabel_table_add(table, start, j);
1418: buf[j++] = label_len;
1419:
1420: memcpy(buf + j, start, name - start);
1421: j += name - start;
1422: /* hop over the '.' */
1423: name++;
1424: }
1425: }
1426:
1427: /* the labels must be terminated by a 0. */
1428: /* It's possible that the name ended in a . */
1429: /* in which case the zero is already there */
1430: if (!j || buf[j-1]) buf[j++] = 0;
1431: return j;
1432: overflow:
1433: return (-2);
1434: }
1435:
1436: /* Finds the length of a dns request for a DNS name of the given */
1437: /* length. The actual request may be smaller than the value returned */
1438: /* here */
1439: static int
1440: evdns_request_len(const int name_len) {
1441: return 96 + /* length of the DNS standard header */
1442: name_len + 2 +
1443: 4; /* space for the resource type */
1444: }
1445:
1446: /* build a dns request packet into buf. buf should be at least as long */
1447: /* as evdns_request_len told you it should be. */
1448: /* */
1449: /* Returns the amount of space used. Negative on error. */
1450: static int
1451: evdns_request_data_build(const char *const name, const int name_len,
1452: const u16 trans_id, const u16 type, const u16 class,
1453: u8 *const buf, size_t buf_len) {
1454: off_t j = 0; /* current offset into buf */
1455: u16 _t; /* used by the macros */
1456:
1457: APPEND16(trans_id);
1458: APPEND16(0x0100); /* standard query, recusion needed */
1459: APPEND16(1); /* one question */
1460: APPEND16(0); /* no answers */
1461: APPEND16(0); /* no authority */
1462: APPEND16(0); /* no additional */
1463:
1464: j = dnsname_to_labels(buf, buf_len, j, name, name_len, NULL);
1465: if (j < 0) {
1466: return (int)j;
1467: }
1468:
1469: APPEND16(type);
1470: APPEND16(class);
1471:
1472: return (int)j;
1473: overflow:
1474: return (-1);
1475: }
1476:
1477: /* exported function */
1478: struct evdns_server_port *
1479: evdns_add_server_port(int socket, int is_tcp, evdns_request_callback_fn_type cb, void *user_data)
1480: {
1481: struct evdns_server_port *port;
1482: if (!(port = malloc(sizeof(struct evdns_server_port))))
1483: return NULL;
1484: memset(port, 0, sizeof(struct evdns_server_port));
1485:
1486: assert(!is_tcp); /* TCP sockets not yet implemented */
1487: port->socket = socket;
1488: port->refcnt = 1;
1489: port->choked = 0;
1490: port->closing = 0;
1491: port->user_callback = cb;
1492: port->user_data = user_data;
1493: port->pending_replies = NULL;
1494:
1495: event_set(&port->event, port->socket, EV_READ | EV_PERSIST,
1496: server_port_ready_callback, port);
1497: event_add(&port->event, NULL); /* check return. */
1498: return port;
1499: }
1500:
1501: /* exported function */
1502: void
1503: evdns_close_server_port(struct evdns_server_port *port)
1504: {
1505: if (--port->refcnt == 0)
1506: server_port_free(port);
1507: port->closing = 1;
1508: }
1509:
1510: /* exported function */
1511: int
1512: 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)
1513: {
1514: struct server_request *req = TO_SERVER_REQUEST(_req);
1515: struct server_reply_item **itemp, *item;
1516: int *countp;
1517:
1518: if (req->response) /* have we already answered? */
1519: return (-1);
1520:
1521: switch (section) {
1522: case EVDNS_ANSWER_SECTION:
1523: itemp = &req->answer;
1524: countp = &req->n_answer;
1525: break;
1526: case EVDNS_AUTHORITY_SECTION:
1527: itemp = &req->authority;
1528: countp = &req->n_authority;
1529: break;
1530: case EVDNS_ADDITIONAL_SECTION:
1531: itemp = &req->additional;
1532: countp = &req->n_additional;
1533: break;
1534: default:
1535: return (-1);
1536: }
1537: while (*itemp) {
1538: itemp = &((*itemp)->next);
1539: }
1540: item = malloc(sizeof(struct server_reply_item));
1541: if (!item)
1542: return -1;
1543: item->next = NULL;
1544: if (!(item->name = strdup(name))) {
1545: free(item);
1546: return -1;
1547: }
1548: item->type = type;
1549: item->dns_question_class = class;
1550: item->ttl = ttl;
1551: item->is_name = is_name != 0;
1552: item->datalen = 0;
1553: item->data = NULL;
1554: if (data) {
1555: if (item->is_name) {
1556: if (!(item->data = strdup(data))) {
1557: free(item->name);
1558: free(item);
1559: return -1;
1560: }
1561: item->datalen = (u16)-1;
1562: } else {
1563: if (!(item->data = malloc(datalen))) {
1564: free(item->name);
1565: free(item);
1566: return -1;
1567: }
1568: item->datalen = datalen;
1569: memcpy(item->data, data, datalen);
1570: }
1571: }
1572:
1573: *itemp = item;
1574: ++(*countp);
1575: return 0;
1576: }
1577:
1578: /* exported function */
1579: int
1580: evdns_server_request_add_a_reply(struct evdns_server_request *req, const char *name, int n, void *addrs, int ttl)
1581: {
1582: return evdns_server_request_add_reply(
1583: req, EVDNS_ANSWER_SECTION, name, TYPE_A, CLASS_INET,
1584: ttl, n*4, 0, addrs);
1585: }
1586:
1587: /* exported function */
1588: int
1589: evdns_server_request_add_aaaa_reply(struct evdns_server_request *req, const char *name, int n, void *addrs, int ttl)
1590: {
1591: return evdns_server_request_add_reply(
1592: req, EVDNS_ANSWER_SECTION, name, TYPE_AAAA, CLASS_INET,
1593: ttl, n*16, 0, addrs);
1594: }
1595:
1596: /* exported function */
1597: int
1598: evdns_server_request_add_ptr_reply(struct evdns_server_request *req, struct in_addr *in, const char *inaddr_name, const char *hostname, int ttl)
1599: {
1600: u32 a;
1601: char buf[32];
1602: assert(in || inaddr_name);
1603: assert(!(in && inaddr_name));
1604: if (in) {
1605: a = ntohl(in->s_addr);
1606: evutil_snprintf(buf, sizeof(buf), "%d.%d.%d.%d.in-addr.arpa",
1607: (int)(u8)((a )&0xff),
1608: (int)(u8)((a>>8 )&0xff),
1609: (int)(u8)((a>>16)&0xff),
1610: (int)(u8)((a>>24)&0xff));
1611: inaddr_name = buf;
1612: }
1613: return evdns_server_request_add_reply(
1614: req, EVDNS_ANSWER_SECTION, inaddr_name, TYPE_PTR, CLASS_INET,
1615: ttl, -1, 1, hostname);
1616: }
1617:
1618: /* exported function */
1619: int
1620: evdns_server_request_add_cname_reply(struct evdns_server_request *req, const char *name, const char *cname, int ttl)
1621: {
1622: return evdns_server_request_add_reply(
1623: req, EVDNS_ANSWER_SECTION, name, TYPE_CNAME, CLASS_INET,
1624: ttl, -1, 1, cname);
1625: }
1626:
1627:
1628: static int
1629: evdns_server_request_format_response(struct server_request *req, int err)
1630: {
1631: unsigned char buf[1500];
1632: size_t buf_len = sizeof(buf);
1633: off_t j = 0, r;
1634: u16 _t;
1635: u32 _t32;
1636: int i;
1637: u16 flags;
1638: struct dnslabel_table table;
1639:
1640: if (err < 0 || err > 15) return -1;
1641:
1642: /* Set response bit and error code; copy OPCODE and RD fields from
1643: * question; copy RA and AA if set by caller. */
1644: flags = req->base.flags;
1645: flags |= (0x8000 | err);
1646:
1647: dnslabel_table_init(&table);
1648: APPEND16(req->trans_id);
1649: APPEND16(flags);
1650: APPEND16(req->base.nquestions);
1651: APPEND16(req->n_answer);
1652: APPEND16(req->n_authority);
1653: APPEND16(req->n_additional);
1654:
1655: /* Add questions. */
1656: for (i=0; i < req->base.nquestions; ++i) {
1657: const char *s = req->base.questions[i]->name;
1658: j = dnsname_to_labels(buf, buf_len, j, s, strlen(s), &table);
1659: if (j < 0) {
1660: dnslabel_clear(&table);
1661: return (int) j;
1662: }
1663: APPEND16(req->base.questions[i]->type);
1664: APPEND16(req->base.questions[i]->dns_question_class);
1665: }
1666:
1667: /* Add answer, authority, and additional sections. */
1668: for (i=0; i<3; ++i) {
1669: struct server_reply_item *item;
1670: if (i==0)
1671: item = req->answer;
1672: else if (i==1)
1673: item = req->authority;
1674: else
1675: item = req->additional;
1676: while (item) {
1677: r = dnsname_to_labels(buf, buf_len, j, item->name, strlen(item->name), &table);
1678: if (r < 0)
1679: goto overflow;
1680: j = r;
1681:
1682: APPEND16(item->type);
1683: APPEND16(item->dns_question_class);
1684: APPEND32(item->ttl);
1685: if (item->is_name) {
1686: off_t len_idx = j, name_start;
1687: j += 2;
1688: name_start = j;
1689: r = dnsname_to_labels(buf, buf_len, j, item->data, strlen(item->data), &table);
1690: if (r < 0)
1691: goto overflow;
1692: j = r;
1693: _t = htons( (short) (j-name_start) );
1694: memcpy(buf+len_idx, &_t, 2);
1695: } else {
1696: APPEND16(item->datalen);
1697: if (j+item->datalen > (off_t)buf_len)
1698: goto overflow;
1699: memcpy(buf+j, item->data, item->datalen);
1700: j += item->datalen;
1701: }
1702: item = item->next;
1703: }
1704: }
1705:
1706: if (j > 512) {
1707: overflow:
1708: j = 512;
1709: buf[2] |= 0x02; /* set the truncated bit. */
1710: }
1711:
1712: req->response_len = j;
1713:
1714: if (!(req->response = malloc(req->response_len))) {
1715: server_request_free_answers(req);
1716: dnslabel_clear(&table);
1717: return (-1);
1718: }
1719: memcpy(req->response, buf, req->response_len);
1720: server_request_free_answers(req);
1721: dnslabel_clear(&table);
1722: return (0);
1723: }
1724:
1725: /* exported function */
1726: int
1727: evdns_server_request_respond(struct evdns_server_request *_req, int err)
1728: {
1729: struct server_request *req = TO_SERVER_REQUEST(_req);
1730: struct evdns_server_port *port = req->port;
1731: int r;
1732: if (!req->response) {
1733: if ((r = evdns_server_request_format_response(req, err))<0)
1734: return r;
1735: }
1736:
1737: r = sendto(port->socket, req->response, req->response_len, 0,
1738: (struct sockaddr*) &req->addr, req->addrlen);
1739: if (r<0) {
1740: int sock_err = last_error(port->socket);
1741: if (! error_is_eagain(sock_err))
1742: return -1;
1743:
1744: if (port->pending_replies) {
1745: req->prev_pending = port->pending_replies->prev_pending;
1746: req->next_pending = port->pending_replies;
1747: req->prev_pending->next_pending =
1748: req->next_pending->prev_pending = req;
1749: } else {
1750: req->prev_pending = req->next_pending = req;
1751: port->pending_replies = req;
1752: port->choked = 1;
1753:
1754: (void) event_del(&port->event);
1755: event_set(&port->event, port->socket, (port->closing?0:EV_READ) | EV_WRITE | EV_PERSIST, server_port_ready_callback, port);
1756:
1757: if (event_add(&port->event, NULL) < 0) {
1758: log(EVDNS_LOG_WARN, "Error from libevent when adding event for DNS server");
1759: }
1760:
1761: }
1762:
1763: return 1;
1764: }
1765: if (server_request_free(req))
1766: return 0;
1767:
1768: if (port->pending_replies)
1769: server_port_flush(port);
1770:
1771: return 0;
1772: }
1773:
1774: /* Free all storage held by RRs in req. */
1775: static void
1776: server_request_free_answers(struct server_request *req)
1777: {
1778: struct server_reply_item *victim, *next, **list;
1779: int i;
1780: for (i = 0; i < 3; ++i) {
1781: if (i==0)
1782: list = &req->answer;
1783: else if (i==1)
1784: list = &req->authority;
1785: else
1786: list = &req->additional;
1787:
1788: victim = *list;
1789: while (victim) {
1790: next = victim->next;
1791: free(victim->name);
1792: if (victim->data)
1793: free(victim->data);
1794: free(victim);
1795: victim = next;
1796: }
1797: *list = NULL;
1798: }
1799: }
1800:
1801: /* Free all storage held by req, and remove links to it. */
1802: /* return true iff we just wound up freeing the server_port. */
1803: static int
1804: server_request_free(struct server_request *req)
1805: {
1806: int i, rc=1;
1807: if (req->base.questions) {
1808: for (i = 0; i < req->base.nquestions; ++i)
1809: free(req->base.questions[i]);
1810: free(req->base.questions);
1811: }
1812:
1813: if (req->port) {
1814: if (req->port->pending_replies == req) {
1815: if (req->next_pending)
1816: req->port->pending_replies = req->next_pending;
1817: else
1818: req->port->pending_replies = NULL;
1819: }
1820: rc = --req->port->refcnt;
1821: }
1822:
1823: if (req->response) {
1824: free(req->response);
1825: }
1826:
1827: server_request_free_answers(req);
1828:
1829: if (req->next_pending && req->next_pending != req) {
1830: req->next_pending->prev_pending = req->prev_pending;
1831: req->prev_pending->next_pending = req->next_pending;
1832: }
1833:
1834: if (rc == 0) {
1835: server_port_free(req->port);
1836: free(req);
1837: return (1);
1838: }
1839: free(req);
1840: return (0);
1841: }
1842:
1843: /* Free all storage held by an evdns_server_port. Only called when */
1844: static void
1845: server_port_free(struct evdns_server_port *port)
1846: {
1847: assert(port);
1848: assert(!port->refcnt);
1849: assert(!port->pending_replies);
1850: if (port->socket > 0) {
1851: CLOSE_SOCKET(port->socket);
1852: port->socket = -1;
1853: }
1854: (void) event_del(&port->event);
1855: /* XXXX actually free the port? -NM */
1856: }
1857:
1858: /* exported function */
1859: int
1860: evdns_server_request_drop(struct evdns_server_request *_req)
1861: {
1862: struct server_request *req = TO_SERVER_REQUEST(_req);
1863: server_request_free(req);
1864: return 0;
1865: }
1866:
1867: /* exported function */
1868: int
1869: evdns_server_request_get_requesting_addr(struct evdns_server_request *_req, struct sockaddr *sa, int addr_len)
1870: {
1871: struct server_request *req = TO_SERVER_REQUEST(_req);
1872: if (addr_len < (int)req->addrlen)
1873: return -1;
1874: memcpy(sa, &(req->addr), req->addrlen);
1875: return req->addrlen;
1876: }
1877:
1878: #undef APPEND16
1879: #undef APPEND32
1880:
1881: /* this is a libevent callback function which is called when a request */
1882: /* has timed out. */
1883: static void
1884: evdns_request_timeout_callback(int fd, short events, void *arg) {
1885: struct request *const req = (struct request *) arg;
1886: (void) fd;
1887: (void) events;
1888:
1889: log(EVDNS_LOG_DEBUG, "Request %lx timed out", (unsigned long) arg);
1890:
1891: req->ns->timedout++;
1892: if (req->ns->timedout > global_max_nameserver_timeout) {
1893: req->ns->timedout = 0;
1894: nameserver_failed(req->ns, "request timed out.");
1895: }
1896:
1897: (void) evtimer_del(&req->timeout_event);
1898: if (req->tx_count >= global_max_retransmits) {
1899: /* this request has failed */
1900: reply_callback(req, 0, DNS_ERR_TIMEOUT, NULL);
1901: request_finished(req, &req_head);
1902: } else {
1903: /* retransmit it */
1904: evdns_request_transmit(req);
1905: }
1906: }
1907:
1908: /* try to send a request to a given server. */
1909: /* */
1910: /* return: */
1911: /* 0 ok */
1912: /* 1 temporary failure */
1913: /* 2 other failure */
1914: static int
1915: evdns_request_transmit_to(struct request *req, struct nameserver *server) {
1916: struct sockaddr_in sin;
1917: int r;
1918: memset(&sin, 0, sizeof(sin));
1919: sin.sin_addr.s_addr = req->ns->address;
1920: sin.sin_port = req->ns->port;
1921: sin.sin_family = AF_INET;
1922:
1923: r = sendto(server->socket, req->request, req->request_len, 0,
1924: (struct sockaddr*)&sin, sizeof(sin));
1925: if (r < 0) {
1926: int err = last_error(server->socket);
1927: if (error_is_eagain(err)) return 1;
1928: nameserver_failed(req->ns, strerror(err));
1929: return 2;
1930: } else if (r != (int)req->request_len) {
1931: return 1; /* short write */
1932: } else {
1933: return 0;
1934: }
1935: }
1936:
1937: /* try to send a request, updating the fields of the request */
1938: /* as needed */
1939: /* */
1940: /* return: */
1941: /* 0 ok */
1942: /* 1 failed */
1943: static int
1944: evdns_request_transmit(struct request *req) {
1945: int retcode = 0, r;
1946:
1947: /* if we fail to send this packet then this flag marks it */
1948: /* for evdns_transmit */
1949: req->transmit_me = 1;
1950: if (req->trans_id == 0xffff) abort();
1951:
1952: if (req->ns->choked) {
1953: /* don't bother trying to write to a socket */
1954: /* which we have had EAGAIN from */
1955: return 1;
1956: }
1957:
1958: r = evdns_request_transmit_to(req, req->ns);
1959: switch (r) {
1960: case 1:
1961: /* temp failure */
1962: req->ns->choked = 1;
1963: nameserver_write_waiting(req->ns, 1);
1964: return 1;
1965: case 2:
1966: /* failed in some other way */
1967: retcode = 1;
1968: /* fall through */
1969: default:
1970: /* all ok */
1971: log(EVDNS_LOG_DEBUG,
1972: "Setting timeout for request %lx", (unsigned long) req);
1973: if (evtimer_add(&req->timeout_event, &global_timeout) < 0) {
1974: log(EVDNS_LOG_WARN,
1975: "Error from libevent when adding timer for request %lx",
1976: (unsigned long) req);
1977: /* ???? Do more? */
1978: }
1979: req->tx_count++;
1980: req->transmit_me = 0;
1981: return retcode;
1982: }
1983: }
1984:
1985: static void
1986: nameserver_probe_callback(int result, char type, int count, int ttl, void *addresses, void *arg) {
1987: struct nameserver *const ns = (struct nameserver *) arg;
1988: (void) type;
1989: (void) count;
1990: (void) ttl;
1991: (void) addresses;
1992:
1993: if (result == DNS_ERR_NONE || result == DNS_ERR_NOTEXIST) {
1994: /* this is a good reply */
1995: nameserver_up(ns);
1996: } else nameserver_probe_failed(ns);
1997: }
1998:
1999: static void
2000: nameserver_send_probe(struct nameserver *const ns) {
2001: struct request *req;
2002: /* here we need to send a probe to a given nameserver */
2003: /* in the hope that it is up now. */
2004:
2005: log(EVDNS_LOG_DEBUG, "Sending probe to %s", debug_ntoa(ns->address));
2006:
2007: req = request_new(TYPE_A, "www.google.com", DNS_QUERY_NO_SEARCH, nameserver_probe_callback, ns);
2008: if (!req) return;
2009: /* we force this into the inflight queue no matter what */
2010: request_trans_id_set(req, transaction_id_pick());
2011: req->ns = ns;
2012: request_submit(req);
2013: }
2014:
2015: /* returns: */
2016: /* 0 didn't try to transmit anything */
2017: /* 1 tried to transmit something */
2018: static int
2019: evdns_transmit(void) {
2020: char did_try_to_transmit = 0;
2021:
2022: if (req_head) {
2023: struct request *const started_at = req_head, *req = req_head;
2024: /* first transmit all the requests which are currently waiting */
2025: do {
2026: if (req->transmit_me) {
2027: did_try_to_transmit = 1;
2028: evdns_request_transmit(req);
2029: }
2030:
2031: req = req->next;
2032: } while (req != started_at);
2033: }
2034:
2035: return did_try_to_transmit;
2036: }
2037:
2038: /* exported function */
2039: int
2040: evdns_count_nameservers(void)
2041: {
2042: const struct nameserver *server = server_head;
2043: int n = 0;
2044: if (!server)
2045: return 0;
2046: do {
2047: ++n;
2048: server = server->next;
2049: } while (server != server_head);
2050: return n;
2051: }
2052:
2053: /* exported function */
2054: int
2055: evdns_clear_nameservers_and_suspend(void)
2056: {
2057: struct nameserver *server = server_head, *started_at = server_head;
2058: struct request *req = req_head, *req_started_at = req_head;
2059:
2060: if (!server)
2061: return 0;
2062: while (1) {
2063: struct nameserver *next = server->next;
2064: (void) event_del(&server->event);
2065: if (evtimer_initialized(&server->timeout_event))
2066: (void) evtimer_del(&server->timeout_event);
2067: if (server->socket >= 0)
2068: CLOSE_SOCKET(server->socket);
2069: free(server);
2070: if (next == started_at)
2071: break;
2072: server = next;
2073: }
2074: server_head = NULL;
2075: global_good_nameservers = 0;
2076:
2077: while (req) {
2078: struct request *next = req->next;
2079: req->tx_count = req->reissue_count = 0;
2080: req->ns = NULL;
2081: /* ???? What to do about searches? */
2082: (void) evtimer_del(&req->timeout_event);
2083: req->trans_id = 0;
2084: req->transmit_me = 0;
2085:
2086: global_requests_waiting++;
2087: evdns_request_insert(req, &req_waiting_head);
2088: /* We want to insert these suspended elements at the front of
2089: * the waiting queue, since they were pending before any of
2090: * the waiting entries were added. This is a circular list,
2091: * so we can just shift the start back by one.*/
2092: req_waiting_head = req_waiting_head->prev;
2093:
2094: if (next == req_started_at)
2095: break;
2096: req = next;
2097: }
2098: req_head = NULL;
2099: global_requests_inflight = 0;
2100:
2101: return 0;
2102: }
2103:
2104:
2105: /* exported function */
2106: int
2107: evdns_resume(void)
2108: {
2109: evdns_requests_pump_waiting_queue();
2110: return 0;
2111: }
2112:
2113: static int
2114: _evdns_nameserver_add_impl(unsigned long int address, int port) {
2115: /* first check to see if we already have this nameserver */
2116:
2117: const struct nameserver *server = server_head, *const started_at = server_head;
2118: struct nameserver *ns;
2119: int err = 0;
2120: if (server) {
2121: do {
2122: if (server->address == address) return 3;
2123: server = server->next;
2124: } while (server != started_at);
2125: }
2126:
2127: ns = (struct nameserver *) malloc(sizeof(struct nameserver));
2128: if (!ns) return -1;
2129:
2130: memset(ns, 0, sizeof(struct nameserver));
2131:
2132: evtimer_set(&ns->timeout_event, nameserver_prod_callback, ns);
2133:
2134: ns->socket = socket(PF_INET, SOCK_DGRAM, 0);
2135: if (ns->socket < 0) { err = 1; goto out1; }
1.1.1.1.2.1! misho 2136: FD_CLOSEONEXEC(ns->socket);
! 2137: evutil_make_socket_nonblocking(ns->socket);
1.1 misho 2138:
2139: ns->address = address;
2140: ns->port = htons(port);
2141: ns->state = 1;
2142: event_set(&ns->event, ns->socket, EV_READ | EV_PERSIST, nameserver_ready_callback, ns);
2143: if (event_add(&ns->event, NULL) < 0) {
2144: err = 2;
2145: goto out2;
2146: }
2147:
2148: log(EVDNS_LOG_DEBUG, "Added nameserver %s", debug_ntoa(address));
2149:
2150: /* insert this nameserver into the list of them */
2151: if (!server_head) {
2152: ns->next = ns->prev = ns;
2153: server_head = ns;
2154: } else {
2155: ns->next = server_head->next;
2156: ns->prev = server_head;
2157: server_head->next = ns;
2158: if (server_head->prev == server_head) {
2159: server_head->prev = ns;
2160: }
2161: }
2162:
2163: global_good_nameservers++;
2164:
2165: return 0;
2166:
2167: out2:
2168: CLOSE_SOCKET(ns->socket);
2169: out1:
2170: free(ns);
2171: log(EVDNS_LOG_WARN, "Unable to add nameserver %s: error %d", debug_ntoa(address), err);
2172: return err;
2173: }
2174:
2175: /* exported function */
2176: int
2177: evdns_nameserver_add(unsigned long int address) {
2178: return _evdns_nameserver_add_impl(address, 53);
2179: }
2180:
2181: /* exported function */
2182: int
2183: evdns_nameserver_ip_add(const char *ip_as_string) {
2184: struct in_addr ina;
2185: int port;
2186: char buf[20];
2187: const char *cp;
2188: cp = strchr(ip_as_string, ':');
2189: if (! cp) {
2190: cp = ip_as_string;
2191: port = 53;
2192: } else {
2193: port = strtoint(cp+1);
2194: if (port < 0 || port > 65535) {
2195: return 4;
2196: }
2197: if ((cp-ip_as_string) >= (int)sizeof(buf)) {
2198: return 4;
2199: }
2200: memcpy(buf, ip_as_string, cp-ip_as_string);
2201: buf[cp-ip_as_string] = '\0';
2202: cp = buf;
2203: }
2204: if (!inet_aton(cp, &ina)) {
2205: return 4;
2206: }
2207: return _evdns_nameserver_add_impl(ina.s_addr, port);
2208: }
2209:
2210: /* insert into the tail of the queue */
2211: static void
2212: evdns_request_insert(struct request *req, struct request **head) {
2213: if (!*head) {
2214: *head = req;
2215: req->next = req->prev = req;
2216: return;
2217: }
2218:
2219: req->prev = (*head)->prev;
2220: req->prev->next = req;
2221: req->next = *head;
2222: (*head)->prev = req;
2223: }
2224:
2225: static int
2226: string_num_dots(const char *s) {
2227: int count = 0;
2228: while ((s = strchr(s, '.'))) {
2229: s++;
2230: count++;
2231: }
2232: return count;
2233: }
2234:
2235: static struct request *
2236: request_new(int type, const char *name, int flags,
2237: evdns_callback_type callback, void *user_ptr) {
2238: const char issuing_now =
2239: (global_requests_inflight < global_max_requests_inflight) ? 1 : 0;
2240:
2241: const int name_len = strlen(name);
2242: const int request_max_len = evdns_request_len(name_len);
2243: const u16 trans_id = issuing_now ? transaction_id_pick() : 0xffff;
2244: /* the request data is alloced in a single block with the header */
2245: struct request *const req =
2246: (struct request *) malloc(sizeof(struct request) + request_max_len);
2247: int rlen;
2248: (void) flags;
2249:
2250: if (!req) return NULL;
2251: memset(req, 0, sizeof(struct request));
2252:
2253: evtimer_set(&req->timeout_event, evdns_request_timeout_callback, req);
2254:
2255: /* request data lives just after the header */
2256: req->request = ((u8 *) req) + sizeof(struct request);
2257: /* denotes that the request data shouldn't be free()ed */
2258: req->request_appended = 1;
2259: rlen = evdns_request_data_build(name, name_len, trans_id,
2260: type, CLASS_INET, req->request, request_max_len);
2261: if (rlen < 0)
2262: goto err1;
2263: req->request_len = rlen;
2264: req->trans_id = trans_id;
2265: req->tx_count = 0;
2266: req->request_type = type;
2267: req->user_pointer = user_ptr;
2268: req->user_callback = callback;
2269: req->ns = issuing_now ? nameserver_pick() : NULL;
2270: req->next = req->prev = NULL;
2271:
2272: return req;
2273: err1:
2274: free(req);
2275: return NULL;
2276: }
2277:
2278: static void
2279: request_submit(struct request *const req) {
2280: if (req->ns) {
2281: /* if it has a nameserver assigned then this is going */
2282: /* straight into the inflight queue */
2283: evdns_request_insert(req, &req_head);
2284: global_requests_inflight++;
2285: evdns_request_transmit(req);
2286: } else {
2287: evdns_request_insert(req, &req_waiting_head);
2288: global_requests_waiting++;
2289: }
2290: }
2291:
2292: /* exported function */
2293: int evdns_resolve_ipv4(const char *name, int flags,
2294: evdns_callback_type callback, void *ptr) {
2295: log(EVDNS_LOG_DEBUG, "Resolve requested for %s", name);
2296: if (flags & DNS_QUERY_NO_SEARCH) {
2297: struct request *const req =
2298: request_new(TYPE_A, name, flags, callback, ptr);
2299: if (req == NULL)
2300: return (1);
2301: request_submit(req);
2302: return (0);
2303: } else {
2304: return (search_request_new(TYPE_A, name, flags, callback, ptr));
2305: }
2306: }
2307:
2308: /* exported function */
2309: int evdns_resolve_ipv6(const char *name, int flags,
2310: evdns_callback_type callback, void *ptr) {
2311: log(EVDNS_LOG_DEBUG, "Resolve requested for %s", name);
2312: if (flags & DNS_QUERY_NO_SEARCH) {
2313: struct request *const req =
2314: request_new(TYPE_AAAA, name, flags, callback, ptr);
2315: if (req == NULL)
2316: return (1);
2317: request_submit(req);
2318: return (0);
2319: } else {
2320: return (search_request_new(TYPE_AAAA, name, flags, callback, ptr));
2321: }
2322: }
2323:
2324: int evdns_resolve_reverse(const struct in_addr *in, int flags, evdns_callback_type callback, void *ptr) {
2325: char buf[32];
2326: struct request *req;
2327: u32 a;
2328: assert(in);
2329: a = ntohl(in->s_addr);
2330: evutil_snprintf(buf, sizeof(buf), "%d.%d.%d.%d.in-addr.arpa",
2331: (int)(u8)((a )&0xff),
2332: (int)(u8)((a>>8 )&0xff),
2333: (int)(u8)((a>>16)&0xff),
2334: (int)(u8)((a>>24)&0xff));
2335: log(EVDNS_LOG_DEBUG, "Resolve requested for %s (reverse)", buf);
2336: req = request_new(TYPE_PTR, buf, flags, callback, ptr);
2337: if (!req) return 1;
2338: request_submit(req);
2339: return 0;
2340: }
2341:
2342: int evdns_resolve_reverse_ipv6(const struct in6_addr *in, int flags, evdns_callback_type callback, void *ptr) {
2343: /* 32 nybbles, 32 periods, "ip6.arpa", NUL. */
2344: char buf[73];
2345: char *cp;
2346: struct request *req;
2347: int i;
2348: assert(in);
2349: cp = buf;
2350: for (i=15; i >= 0; --i) {
2351: u8 byte = in->s6_addr[i];
2352: *cp++ = "0123456789abcdef"[byte & 0x0f];
2353: *cp++ = '.';
2354: *cp++ = "0123456789abcdef"[byte >> 4];
2355: *cp++ = '.';
2356: }
2357: assert(cp + strlen("ip6.arpa") < buf+sizeof(buf));
2358: memcpy(cp, "ip6.arpa", strlen("ip6.arpa")+1);
2359: log(EVDNS_LOG_DEBUG, "Resolve requested for %s (reverse)", buf);
2360: req = request_new(TYPE_PTR, buf, flags, callback, ptr);
2361: if (!req) return 1;
2362: request_submit(req);
2363: return 0;
2364: }
2365:
2366: /*/////////////////////////////////////////////////////////////////// */
2367: /* Search support */
2368: /* */
2369: /* the libc resolver has support for searching a number of domains */
2370: /* to find a name. If nothing else then it takes the single domain */
2371: /* from the gethostname() call. */
2372: /* */
2373: /* It can also be configured via the domain and search options in a */
2374: /* resolv.conf. */
2375: /* */
2376: /* The ndots option controls how many dots it takes for the resolver */
2377: /* to decide that a name is non-local and so try a raw lookup first. */
2378:
2379: struct search_domain {
2380: int len;
2381: struct search_domain *next;
2382: /* the text string is appended to this structure */
2383: };
2384:
2385: struct search_state {
2386: int refcount;
2387: int ndots;
2388: int num_domains;
2389: struct search_domain *head;
2390: };
2391:
2392: static struct search_state *global_search_state = NULL;
2393:
2394: static void
2395: search_state_decref(struct search_state *const state) {
2396: if (!state) return;
2397: state->refcount--;
2398: if (!state->refcount) {
2399: struct search_domain *next, *dom;
2400: for (dom = state->head; dom; dom = next) {
2401: next = dom->next;
2402: free(dom);
2403: }
2404: free(state);
2405: }
2406: }
2407:
2408: static struct search_state *
2409: search_state_new(void) {
2410: struct search_state *state = (struct search_state *) malloc(sizeof(struct search_state));
2411: if (!state) return NULL;
2412: memset(state, 0, sizeof(struct search_state));
2413: state->refcount = 1;
2414: state->ndots = 1;
2415:
2416: return state;
2417: }
2418:
2419: static void
2420: search_postfix_clear(void) {
2421: search_state_decref(global_search_state);
2422:
2423: global_search_state = search_state_new();
2424: }
2425:
2426: /* exported function */
2427: void
2428: evdns_search_clear(void) {
2429: search_postfix_clear();
2430: }
2431:
2432: static void
2433: search_postfix_add(const char *domain) {
2434: int domain_len;
2435: struct search_domain *sdomain;
2436: while (domain[0] == '.') domain++;
2437: domain_len = strlen(domain);
2438:
2439: if (!global_search_state) global_search_state = search_state_new();
2440: if (!global_search_state) return;
2441: global_search_state->num_domains++;
2442:
2443: sdomain = (struct search_domain *) malloc(sizeof(struct search_domain) + domain_len);
2444: if (!sdomain) return;
2445: memcpy( ((u8 *) sdomain) + sizeof(struct search_domain), domain, domain_len);
2446: sdomain->next = global_search_state->head;
2447: sdomain->len = domain_len;
2448:
2449: global_search_state->head = sdomain;
2450: }
2451:
2452: /* reverse the order of members in the postfix list. This is needed because, */
2453: /* when parsing resolv.conf we push elements in the wrong order */
2454: static void
2455: search_reverse(void) {
2456: struct search_domain *cur, *prev = NULL, *next;
2457: cur = global_search_state->head;
2458: while (cur) {
2459: next = cur->next;
2460: cur->next = prev;
2461: prev = cur;
2462: cur = next;
2463: }
2464:
2465: global_search_state->head = prev;
2466: }
2467:
2468: /* exported function */
2469: void
2470: evdns_search_add(const char *domain) {
2471: search_postfix_add(domain);
2472: }
2473:
2474: /* exported function */
2475: void
2476: evdns_search_ndots_set(const int ndots) {
2477: if (!global_search_state) global_search_state = search_state_new();
2478: if (!global_search_state) return;
2479: global_search_state->ndots = ndots;
2480: }
2481:
2482: static void
2483: search_set_from_hostname(void) {
2484: char hostname[HOST_NAME_MAX + 1], *domainname;
2485:
2486: search_postfix_clear();
2487: if (gethostname(hostname, sizeof(hostname))) return;
2488: domainname = strchr(hostname, '.');
2489: if (!domainname) return;
2490: search_postfix_add(domainname);
2491: }
2492:
2493: /* warning: returns malloced string */
2494: static char *
2495: search_make_new(const struct search_state *const state, int n, const char *const base_name) {
2496: const int base_len = strlen(base_name);
2497: const char need_to_append_dot = base_name[base_len - 1] == '.' ? 0 : 1;
2498: struct search_domain *dom;
2499:
2500: for (dom = state->head; dom; dom = dom->next) {
2501: if (!n--) {
2502: /* this is the postfix we want */
2503: /* the actual postfix string is kept at the end of the structure */
2504: const u8 *const postfix = ((u8 *) dom) + sizeof(struct search_domain);
2505: const int postfix_len = dom->len;
2506: char *const newname = (char *) malloc(base_len + need_to_append_dot + postfix_len + 1);
2507: if (!newname) return NULL;
2508: memcpy(newname, base_name, base_len);
2509: if (need_to_append_dot) newname[base_len] = '.';
2510: memcpy(newname + base_len + need_to_append_dot, postfix, postfix_len);
2511: newname[base_len + need_to_append_dot + postfix_len] = 0;
2512: return newname;
2513: }
2514: }
2515:
2516: /* we ran off the end of the list and still didn't find the requested string */
2517: abort();
2518: return NULL; /* unreachable; stops warnings in some compilers. */
2519: }
2520:
2521: static int
2522: search_request_new(int type, const char *const name, int flags, evdns_callback_type user_callback, void *user_arg) {
2523: assert(type == TYPE_A || type == TYPE_AAAA);
2524: if ( ((flags & DNS_QUERY_NO_SEARCH) == 0) &&
2525: global_search_state &&
2526: global_search_state->num_domains) {
2527: /* we have some domains to search */
2528: struct request *req;
2529: if (string_num_dots(name) >= global_search_state->ndots) {
2530: req = request_new(type, name, flags, user_callback, user_arg);
2531: if (!req) return 1;
2532: req->search_index = -1;
2533: } else {
2534: char *const new_name = search_make_new(global_search_state, 0, name);
2535: if (!new_name) return 1;
2536: req = request_new(type, new_name, flags, user_callback, user_arg);
2537: free(new_name);
2538: if (!req) return 1;
2539: req->search_index = 0;
2540: }
2541: req->search_origname = strdup(name);
2542: req->search_state = global_search_state;
2543: req->search_flags = flags;
2544: global_search_state->refcount++;
2545: request_submit(req);
2546: return 0;
2547: } else {
2548: struct request *const req = request_new(type, name, flags, user_callback, user_arg);
2549: if (!req) return 1;
2550: request_submit(req);
2551: return 0;
2552: }
2553: }
2554:
2555: /* this is called when a request has failed to find a name. We need to check */
2556: /* if it is part of a search and, if so, try the next name in the list */
2557: /* returns: */
2558: /* 0 another request has been submitted */
2559: /* 1 no more requests needed */
2560: static int
2561: search_try_next(struct request *const req) {
2562: if (req->search_state) {
2563: /* it is part of a search */
2564: char *new_name;
2565: struct request *newreq;
2566: req->search_index++;
2567: if (req->search_index >= req->search_state->num_domains) {
2568: /* no more postfixes to try, however we may need to try */
2569: /* this name without a postfix */
2570: if (string_num_dots(req->search_origname) < req->search_state->ndots) {
2571: /* yep, we need to try it raw */
2572: newreq = request_new(req->request_type, req->search_origname, req->search_flags, req->user_callback, req->user_pointer);
2573: log(EVDNS_LOG_DEBUG, "Search: trying raw query %s", req->search_origname);
2574: if (newreq) {
2575: request_submit(newreq);
2576: return 0;
2577: }
2578: }
2579: return 1;
2580: }
2581:
2582: new_name = search_make_new(req->search_state, req->search_index, req->search_origname);
2583: if (!new_name) return 1;
2584: log(EVDNS_LOG_DEBUG, "Search: now trying %s (%d)", new_name, req->search_index);
2585: newreq = request_new(req->request_type, new_name, req->search_flags, req->user_callback, req->user_pointer);
2586: free(new_name);
2587: if (!newreq) return 1;
2588: newreq->search_origname = req->search_origname;
2589: req->search_origname = NULL;
2590: newreq->search_state = req->search_state;
2591: newreq->search_flags = req->search_flags;
2592: newreq->search_index = req->search_index;
2593: newreq->search_state->refcount++;
2594: request_submit(newreq);
2595: return 0;
2596: }
2597: return 1;
2598: }
2599:
2600: static void
2601: search_request_finished(struct request *const req) {
2602: if (req->search_state) {
2603: search_state_decref(req->search_state);
2604: req->search_state = NULL;
2605: }
2606: if (req->search_origname) {
2607: free(req->search_origname);
2608: req->search_origname = NULL;
2609: }
2610: }
2611:
2612: /*/////////////////////////////////////////////////////////////////// */
2613: /* Parsing resolv.conf files */
2614:
2615: static void
2616: evdns_resolv_set_defaults(int flags) {
2617: /* if the file isn't found then we assume a local resolver */
2618: if (flags & DNS_OPTION_SEARCH) search_set_from_hostname();
2619: if (flags & DNS_OPTION_NAMESERVERS) evdns_nameserver_ip_add("127.0.0.1");
2620: }
2621:
2622: #ifndef HAVE_STRTOK_R
2623: static char *
2624: strtok_r(char *s, const char *delim, char **state) {
2625: return strtok(s, delim);
2626: }
2627: #endif
2628:
2629: /* helper version of atoi which returns -1 on error */
2630: static int
2631: strtoint(const char *const str) {
2632: char *endptr;
2633: const int r = strtol(str, &endptr, 10);
2634: if (*endptr) return -1;
2635: return r;
2636: }
2637:
2638: /* helper version of atoi that returns -1 on error and clips to bounds. */
2639: static int
2640: strtoint_clipped(const char *const str, int min, int max)
2641: {
2642: int r = strtoint(str);
2643: if (r == -1)
2644: return r;
2645: else if (r<min)
2646: return min;
2647: else if (r>max)
2648: return max;
2649: else
2650: return r;
2651: }
2652:
2653: /* exported function */
2654: int
2655: evdns_set_option(const char *option, const char *val, int flags)
2656: {
2657: if (!strncmp(option, "ndots:", 6)) {
2658: const int ndots = strtoint(val);
2659: if (ndots == -1) return -1;
2660: if (!(flags & DNS_OPTION_SEARCH)) return 0;
2661: log(EVDNS_LOG_DEBUG, "Setting ndots to %d", ndots);
2662: if (!global_search_state) global_search_state = search_state_new();
2663: if (!global_search_state) return -1;
2664: global_search_state->ndots = ndots;
2665: } else if (!strncmp(option, "timeout:", 8)) {
2666: const int timeout = strtoint(val);
2667: if (timeout == -1) return -1;
2668: if (!(flags & DNS_OPTION_MISC)) return 0;
2669: log(EVDNS_LOG_DEBUG, "Setting timeout to %d", timeout);
2670: global_timeout.tv_sec = timeout;
2671: } else if (!strncmp(option, "max-timeouts:", 12)) {
2672: const int maxtimeout = strtoint_clipped(val, 1, 255);
2673: if (maxtimeout == -1) return -1;
2674: if (!(flags & DNS_OPTION_MISC)) return 0;
2675: log(EVDNS_LOG_DEBUG, "Setting maximum allowed timeouts to %d",
2676: maxtimeout);
2677: global_max_nameserver_timeout = maxtimeout;
2678: } else if (!strncmp(option, "max-inflight:", 13)) {
2679: const int maxinflight = strtoint_clipped(val, 1, 65000);
2680: if (maxinflight == -1) return -1;
2681: if (!(flags & DNS_OPTION_MISC)) return 0;
2682: log(EVDNS_LOG_DEBUG, "Setting maximum inflight requests to %d",
2683: maxinflight);
2684: global_max_requests_inflight = maxinflight;
2685: } else if (!strncmp(option, "attempts:", 9)) {
2686: int retries = strtoint(val);
2687: if (retries == -1) return -1;
2688: if (retries > 255) retries = 255;
2689: if (!(flags & DNS_OPTION_MISC)) return 0;
2690: log(EVDNS_LOG_DEBUG, "Setting retries to %d", retries);
2691: global_max_retransmits = retries;
2692: }
2693: return 0;
2694: }
2695:
2696: static void
2697: resolv_conf_parse_line(char *const start, int flags) {
2698: char *strtok_state;
2699: static const char *const delims = " \t";
2700: #define NEXT_TOKEN strtok_r(NULL, delims, &strtok_state)
2701:
2702: char *const first_token = strtok_r(start, delims, &strtok_state);
2703: if (!first_token) return;
2704:
2705: if (!strcmp(first_token, "nameserver") && (flags & DNS_OPTION_NAMESERVERS)) {
2706: const char *const nameserver = NEXT_TOKEN;
2707: struct in_addr ina;
2708:
2709: if (nameserver && inet_aton(nameserver, &ina)) {
2710: /* address is valid */
2711: evdns_nameserver_add(ina.s_addr);
2712: }
2713: } else if (!strcmp(first_token, "domain") && (flags & DNS_OPTION_SEARCH)) {
2714: const char *const domain = NEXT_TOKEN;
2715: if (domain) {
2716: search_postfix_clear();
2717: search_postfix_add(domain);
2718: }
2719: } else if (!strcmp(first_token, "search") && (flags & DNS_OPTION_SEARCH)) {
2720: const char *domain;
2721: search_postfix_clear();
2722:
2723: while ((domain = NEXT_TOKEN)) {
2724: search_postfix_add(domain);
2725: }
2726: search_reverse();
2727: } else if (!strcmp(first_token, "options")) {
2728: const char *option;
2729: while ((option = NEXT_TOKEN)) {
2730: const char *val = strchr(option, ':');
2731: evdns_set_option(option, val ? val+1 : "", flags);
2732: }
2733: }
2734: #undef NEXT_TOKEN
2735: }
2736:
2737: /* exported function */
2738: /* returns: */
2739: /* 0 no errors */
2740: /* 1 failed to open file */
2741: /* 2 failed to stat file */
2742: /* 3 file too large */
2743: /* 4 out of memory */
2744: /* 5 short read from file */
2745: int
2746: evdns_resolv_conf_parse(int flags, const char *const filename) {
2747: struct stat st;
2748: int fd, n, r;
2749: u8 *resolv;
2750: char *start;
2751: int err = 0;
2752:
2753: log(EVDNS_LOG_DEBUG, "Parsing resolv.conf file %s", filename);
2754:
2755: fd = open(filename, O_RDONLY);
2756: if (fd < 0) {
2757: evdns_resolv_set_defaults(flags);
2758: return 1;
2759: }
2760:
2761: if (fstat(fd, &st)) { err = 2; goto out1; }
2762: if (!st.st_size) {
2763: evdns_resolv_set_defaults(flags);
2764: err = (flags & DNS_OPTION_NAMESERVERS) ? 6 : 0;
2765: goto out1;
2766: }
2767: if (st.st_size > 65535) { err = 3; goto out1; } /* no resolv.conf should be any bigger */
2768:
2769: resolv = (u8 *) malloc((size_t)st.st_size + 1);
2770: if (!resolv) { err = 4; goto out1; }
2771:
2772: n = 0;
2773: while ((r = read(fd, resolv+n, (size_t)st.st_size-n)) > 0) {
2774: n += r;
2775: if (n == st.st_size)
2776: break;
2777: assert(n < st.st_size);
2778: }
2779: if (r < 0) { err = 5; goto out2; }
2780: resolv[n] = 0; /* we malloced an extra byte; this should be fine. */
2781:
2782: start = (char *) resolv;
2783: for (;;) {
2784: char *const newline = strchr(start, '\n');
2785: if (!newline) {
2786: resolv_conf_parse_line(start, flags);
2787: break;
2788: } else {
2789: *newline = 0;
2790: resolv_conf_parse_line(start, flags);
2791: start = newline + 1;
2792: }
2793: }
2794:
2795: if (!server_head && (flags & DNS_OPTION_NAMESERVERS)) {
2796: /* no nameservers were configured. */
2797: evdns_nameserver_ip_add("127.0.0.1");
2798: err = 6;
2799: }
2800: if (flags & DNS_OPTION_SEARCH && (!global_search_state || global_search_state->num_domains == 0)) {
2801: search_set_from_hostname();
2802: }
2803:
2804: out2:
2805: free(resolv);
2806: out1:
2807: close(fd);
2808: return err;
2809: }
2810:
2811: #ifdef WIN32
2812: /* Add multiple nameservers from a space-or-comma-separated list. */
2813: static int
2814: evdns_nameserver_ip_add_line(const char *ips) {
2815: const char *addr;
2816: char *buf;
2817: int r;
2818: while (*ips) {
2819: while (ISSPACE(*ips) || *ips == ',' || *ips == '\t')
2820: ++ips;
2821: addr = ips;
2822: while (ISDIGIT(*ips) || *ips == '.' || *ips == ':')
2823: ++ips;
2824: buf = malloc(ips-addr+1);
2825: if (!buf) return 4;
2826: memcpy(buf, addr, ips-addr);
2827: buf[ips-addr] = '\0';
2828: r = evdns_nameserver_ip_add(buf);
2829: free(buf);
2830: if (r) return r;
2831: }
2832: return 0;
2833: }
2834:
2835: typedef DWORD(WINAPI *GetNetworkParams_fn_t)(FIXED_INFO *, DWORD*);
2836:
2837: /* Use the windows GetNetworkParams interface in iphlpapi.dll to */
2838: /* figure out what our nameservers are. */
2839: static int
2840: load_nameservers_with_getnetworkparams(void)
2841: {
2842: /* Based on MSDN examples and inspection of c-ares code. */
2843: FIXED_INFO *fixed;
2844: HMODULE handle = 0;
2845: ULONG size = sizeof(FIXED_INFO);
2846: void *buf = NULL;
2847: int status = 0, r, added_any;
2848: IP_ADDR_STRING *ns;
2849: GetNetworkParams_fn_t fn;
2850:
2851: if (!(handle = LoadLibraryA("iphlpapi.dll"))) {
2852: log(EVDNS_LOG_WARN, "Could not open iphlpapi.dll");
2853: status = -1;
2854: goto done;
2855: }
2856: if (!(fn = (GetNetworkParams_fn_t) GetProcAddress(handle, "GetNetworkParams"))) {
2857: log(EVDNS_LOG_WARN, "Could not get address of function.");
2858: status = -1;
2859: goto done;
2860: }
2861:
2862: buf = malloc(size);
2863: if (!buf) { status = 4; goto done; }
2864: fixed = buf;
2865: r = fn(fixed, &size);
2866: if (r != ERROR_SUCCESS && r != ERROR_BUFFER_OVERFLOW) {
2867: status = -1;
2868: goto done;
2869: }
2870: if (r != ERROR_SUCCESS) {
2871: free(buf);
2872: buf = malloc(size);
2873: if (!buf) { status = 4; goto done; }
2874: fixed = buf;
2875: r = fn(fixed, &size);
2876: if (r != ERROR_SUCCESS) {
2877: log(EVDNS_LOG_DEBUG, "fn() failed.");
2878: status = -1;
2879: goto done;
2880: }
2881: }
2882:
2883: assert(fixed);
2884: added_any = 0;
2885: ns = &(fixed->DnsServerList);
2886: while (ns) {
2887: r = evdns_nameserver_ip_add_line(ns->IpAddress.String);
2888: if (r) {
2889: log(EVDNS_LOG_DEBUG,"Could not add nameserver %s to list,error: %d",
2890: (ns->IpAddress.String),(int)GetLastError());
2891: status = r;
2892: goto done;
2893: } else {
2894: log(EVDNS_LOG_DEBUG,"Succesfully added %s as nameserver",ns->IpAddress.String);
2895: }
2896:
2897: added_any++;
2898: ns = ns->Next;
2899: }
2900:
2901: if (!added_any) {
2902: log(EVDNS_LOG_DEBUG, "No nameservers added.");
2903: status = -1;
2904: }
2905:
2906: done:
2907: if (buf)
2908: free(buf);
2909: if (handle)
2910: FreeLibrary(handle);
2911: return status;
2912: }
2913:
2914: static int
2915: config_nameserver_from_reg_key(HKEY key, const char *subkey)
2916: {
2917: char *buf;
2918: DWORD bufsz = 0, type = 0;
2919: int status = 0;
2920:
2921: if (RegQueryValueExA(key, subkey, 0, &type, NULL, &bufsz)
2922: != ERROR_MORE_DATA)
2923: return -1;
2924: if (!(buf = malloc(bufsz)))
2925: return -1;
2926:
2927: if (RegQueryValueExA(key, subkey, 0, &type, (LPBYTE)buf, &bufsz)
2928: == ERROR_SUCCESS && bufsz > 1) {
2929: status = evdns_nameserver_ip_add_line(buf);
2930: }
2931:
2932: free(buf);
2933: return status;
2934: }
2935:
2936: #define SERVICES_KEY "System\\CurrentControlSet\\Services\\"
2937: #define WIN_NS_9X_KEY SERVICES_KEY "VxD\\MSTCP"
2938: #define WIN_NS_NT_KEY SERVICES_KEY "Tcpip\\Parameters"
2939:
2940: static int
2941: load_nameservers_from_registry(void)
2942: {
2943: int found = 0;
2944: int r;
2945: #define TRY(k, name) \
2946: if (!found && config_nameserver_from_reg_key(k,name) == 0) { \
2947: log(EVDNS_LOG_DEBUG,"Found nameservers in %s/%s",#k,name); \
2948: found = 1; \
2949: } else if (!found) { \
2950: log(EVDNS_LOG_DEBUG,"Didn't find nameservers in %s/%s", \
2951: #k,#name); \
2952: }
2953:
2954: if (((int)GetVersion()) > 0) { /* NT */
2955: HKEY nt_key = 0, interfaces_key = 0;
2956:
2957: if (RegOpenKeyExA(HKEY_LOCAL_MACHINE, WIN_NS_NT_KEY, 0,
2958: KEY_READ, &nt_key) != ERROR_SUCCESS) {
2959: log(EVDNS_LOG_DEBUG,"Couldn't open nt key, %d",(int)GetLastError());
2960: return -1;
2961: }
2962: r = RegOpenKeyExA(nt_key, "Interfaces", 0,
2963: KEY_QUERY_VALUE|KEY_ENUMERATE_SUB_KEYS,
2964: &interfaces_key);
2965: if (r != ERROR_SUCCESS) {
2966: log(EVDNS_LOG_DEBUG,"Couldn't open interfaces key, %d",(int)GetLastError());
2967: return -1;
2968: }
2969: TRY(nt_key, "NameServer");
2970: TRY(nt_key, "DhcpNameServer");
2971: TRY(interfaces_key, "NameServer");
2972: TRY(interfaces_key, "DhcpNameServer");
2973: RegCloseKey(interfaces_key);
2974: RegCloseKey(nt_key);
2975: } else {
2976: HKEY win_key = 0;
2977: if (RegOpenKeyExA(HKEY_LOCAL_MACHINE, WIN_NS_9X_KEY, 0,
2978: KEY_READ, &win_key) != ERROR_SUCCESS) {
2979: log(EVDNS_LOG_DEBUG, "Couldn't open registry key, %d", (int)GetLastError());
2980: return -1;
2981: }
2982: TRY(win_key, "NameServer");
2983: RegCloseKey(win_key);
2984: }
2985:
2986: if (found == 0) {
2987: log(EVDNS_LOG_WARN,"Didn't find any nameservers.");
2988: }
2989:
2990: return found ? 0 : -1;
2991: #undef TRY
2992: }
2993:
2994: int
2995: evdns_config_windows_nameservers(void)
2996: {
2997: if (load_nameservers_with_getnetworkparams() == 0)
2998: return 0;
2999: return load_nameservers_from_registry();
3000: }
3001: #endif
3002:
3003: int
3004: evdns_init(void)
3005: {
3006: int res = 0;
3007: #ifdef WIN32
3008: res = evdns_config_windows_nameservers();
3009: #else
3010: res = evdns_resolv_conf_parse(DNS_OPTIONS_ALL, "/etc/resolv.conf");
3011: #endif
3012:
3013: return (res);
3014: }
3015:
3016: const char *
3017: evdns_err_to_string(int err)
3018: {
3019: switch (err) {
3020: case DNS_ERR_NONE: return "no error";
3021: case DNS_ERR_FORMAT: return "misformatted query";
3022: case DNS_ERR_SERVERFAILED: return "server failed";
3023: case DNS_ERR_NOTEXIST: return "name does not exist";
3024: case DNS_ERR_NOTIMPL: return "query not implemented";
3025: case DNS_ERR_REFUSED: return "refused";
3026:
3027: case DNS_ERR_TRUNCATED: return "reply truncated or ill-formed";
3028: case DNS_ERR_UNKNOWN: return "unknown";
3029: case DNS_ERR_TIMEOUT: return "request timed out";
3030: case DNS_ERR_SHUTDOWN: return "dns subsystem shut down";
3031: default: return "[Unknown error code]";
3032: }
3033: }
3034:
3035: void
3036: evdns_shutdown(int fail_requests)
3037: {
3038: struct nameserver *server, *server_next;
3039: struct search_domain *dom, *dom_next;
3040:
3041: while (req_head) {
3042: if (fail_requests)
3043: reply_callback(req_head, 0, DNS_ERR_SHUTDOWN, NULL);
3044: request_finished(req_head, &req_head);
3045: }
3046: while (req_waiting_head) {
3047: if (fail_requests)
3048: reply_callback(req_waiting_head, 0, DNS_ERR_SHUTDOWN, NULL);
3049: request_finished(req_waiting_head, &req_waiting_head);
3050: }
3051: global_requests_inflight = global_requests_waiting = 0;
3052:
3053: for (server = server_head; server; server = server_next) {
3054: server_next = server->next;
3055: if (server->socket >= 0)
3056: CLOSE_SOCKET(server->socket);
3057: (void) event_del(&server->event);
3058: if (server->state == 0)
3059: (void) event_del(&server->timeout_event);
3060: free(server);
3061: if (server_next == server_head)
3062: break;
3063: }
3064: server_head = NULL;
3065: global_good_nameservers = 0;
3066:
3067: if (global_search_state) {
3068: for (dom = global_search_state->head; dom; dom = dom_next) {
3069: dom_next = dom->next;
3070: free(dom);
3071: }
3072: free(global_search_state);
3073: global_search_state = NULL;
3074: }
3075: evdns_log_fn = NULL;
3076: }
3077:
3078: #ifdef EVDNS_MAIN
3079: void
3080: main_callback(int result, char type, int count, int ttl,
3081: void *addrs, void *orig) {
3082: char *n = (char*)orig;
3083: int i;
3084: for (i = 0; i < count; ++i) {
3085: if (type == DNS_IPv4_A) {
3086: printf("%s: %s\n", n, debug_ntoa(((u32*)addrs)[i]));
3087: } else if (type == DNS_PTR) {
3088: printf("%s: %s\n", n, ((char**)addrs)[i]);
3089: }
3090: }
3091: if (!count) {
3092: printf("%s: No answer (%d)\n", n, result);
3093: }
3094: fflush(stdout);
3095: }
3096: void
3097: evdns_server_callback(struct evdns_server_request *req, void *data)
3098: {
3099: int i, r;
3100: (void)data;
3101: /* dummy; give 192.168.11.11 as an answer for all A questions,
3102: * give foo.bar.example.com as an answer for all PTR questions. */
3103: for (i = 0; i < req->nquestions; ++i) {
3104: u32 ans = htonl(0xc0a80b0bUL);
3105: if (req->questions[i]->type == EVDNS_TYPE_A &&
3106: req->questions[i]->dns_question_class == EVDNS_CLASS_INET) {
3107: printf(" -- replying for %s (A)\n", req->questions[i]->name);
3108: r = evdns_server_request_add_a_reply(req, req->questions[i]->name,
3109: 1, &ans, 10);
3110: if (r<0)
3111: printf("eeep, didn't work.\n");
3112: } else if (req->questions[i]->type == EVDNS_TYPE_PTR &&
3113: req->questions[i]->dns_question_class == EVDNS_CLASS_INET) {
3114: printf(" -- replying for %s (PTR)\n", req->questions[i]->name);
3115: r = evdns_server_request_add_ptr_reply(req, NULL, req->questions[i]->name,
3116: "foo.bar.example.com", 10);
3117: } else {
3118: printf(" -- skipping %s [%d %d]\n", req->questions[i]->name,
3119: req->questions[i]->type, req->questions[i]->dns_question_class);
3120: }
3121: }
3122:
3123: r = evdns_request_respond(req, 0);
3124: if (r<0)
3125: printf("eeek, couldn't send reply.\n");
3126: }
3127:
3128: void
3129: logfn(int is_warn, const char *msg) {
3130: (void) is_warn;
3131: fprintf(stderr, "%s\n", msg);
3132: }
3133: int
3134: main(int c, char **v) {
3135: int idx;
3136: int reverse = 0, verbose = 1, servertest = 0;
3137: if (c<2) {
3138: fprintf(stderr, "syntax: %s [-x] [-v] hostname\n", v[0]);
3139: fprintf(stderr, "syntax: %s [-servertest]\n", v[0]);
3140: return 1;
3141: }
3142: idx = 1;
3143: while (idx < c && v[idx][0] == '-') {
3144: if (!strcmp(v[idx], "-x"))
3145: reverse = 1;
3146: else if (!strcmp(v[idx], "-v"))
3147: verbose = 1;
3148: else if (!strcmp(v[idx], "-servertest"))
3149: servertest = 1;
3150: else
3151: fprintf(stderr, "Unknown option %s\n", v[idx]);
3152: ++idx;
3153: }
3154: event_init();
3155: if (verbose)
3156: evdns_set_log_fn(logfn);
3157: evdns_resolv_conf_parse(DNS_OPTION_NAMESERVERS, "/etc/resolv.conf");
3158: if (servertest) {
3159: int sock;
3160: struct sockaddr_in my_addr;
3161: sock = socket(PF_INET, SOCK_DGRAM, 0);
3162: evutil_make_socket_nonblocking(sock);
3163: my_addr.sin_family = AF_INET;
3164: my_addr.sin_port = htons(10053);
3165: my_addr.sin_addr.s_addr = INADDR_ANY;
3166: if (bind(sock, (struct sockaddr*)&my_addr, sizeof(my_addr))<0) {
3167: perror("bind");
3168: exit(1);
3169: }
3170: evdns_add_server_port(sock, 0, evdns_server_callback, NULL);
3171: }
3172: for (; idx < c; ++idx) {
3173: if (reverse) {
3174: struct in_addr addr;
3175: if (!inet_aton(v[idx], &addr)) {
3176: fprintf(stderr, "Skipping non-IP %s\n", v[idx]);
3177: continue;
3178: }
3179: fprintf(stderr, "resolving %s...\n",v[idx]);
3180: evdns_resolve_reverse(&addr, 0, main_callback, v[idx]);
3181: } else {
3182: fprintf(stderr, "resolving (fwd) %s...\n",v[idx]);
3183: evdns_resolve_ipv4(v[idx], 0, main_callback, v[idx]);
3184: }
3185: }
3186: fflush(stdout);
3187: event_dispatch();
3188: return 0;
3189: }
3190: #endif
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