1 /* Copyright 2006-2007 Niels Provos 2 * Copyright 2007-2012 Nick Mathewson and Niels Provos 3 * 4 * Redistribution and use in source and binary forms, with or without 5 * modification, are permitted provided that the following conditions 6 * are met: 7 * 1. Redistributions of source code must retain the above copyright 8 * notice, this list of conditions and the following disclaimer. 9 * 2. Redistributions in binary form must reproduce the above copyright 10 * notice, this list of conditions and the following disclaimer in the 11 * documentation and/or other materials provided with the distribution. 12 * 3. The name of the author may not be used to endorse or promote products 13 * derived from this software without specific prior written permission. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25 */ 26 27 /* Based on software by Adam Langly. Adam's original message: 28 * 29 * Async DNS Library 30 * Adam Langley <agl@imperialviolet.org> 31 * http://www.imperialviolet.org/eventdns.html 32 * Public Domain code 33 * 34 * This software is Public Domain. To view a copy of the public domain dedication, 35 * visit http://creativecommons.org/licenses/publicdomain/ or send a letter to 36 * Creative Commons, 559 Nathan Abbott Way, Stanford, California 94305, USA. 37 * 38 * I ask and expect, but do not require, that all derivative works contain an 39 * attribution similar to: 40 * Parts developed by Adam Langley <agl@imperialviolet.org> 41 * 42 * You may wish to replace the word "Parts" with something else depending on 43 * the amount of original code. 44 * 45 * (Derivative works does not include programs which link against, run or include 46 * the source verbatim in their source distributions) 47 * 48 * Version: 0.1b 49 */ 50 51 #include "event2/event-config.h" 52 #include "evconfig-private.h" 53 54 #include <sys/types.h> 55 56 #ifndef _FORTIFY_SOURCE 57 #define _FORTIFY_SOURCE 3 58 #endif 59 60 #include <string.h> 61 #include <fcntl.h> 62 #ifdef EVENT__HAVE_SYS_TIME_H 63 #include <sys/time.h> 64 #endif 65 #ifdef EVENT__HAVE_STDINT_H 66 #include <stdint.h> 67 #endif 68 #include <stdlib.h> 69 #include <string.h> 70 #include <errno.h> 71 #ifdef EVENT__HAVE_UNISTD_H 72 #include <unistd.h> 73 #endif 74 #include <limits.h> 75 #include <sys/stat.h> 76 #include <stdio.h> 77 #include <stdarg.h> 78 #ifdef _WIN32 79 #include <winsock2.h> 80 #include <ws2tcpip.h> 81 #ifndef _WIN32_IE 82 #define _WIN32_IE 0x400 83 #endif 84 #include <shlobj.h> 85 #endif 86 87 #include "event2/dns.h" 88 #include "event2/dns_struct.h" 89 #include "event2/dns_compat.h" 90 #include "event2/util.h" 91 #include "event2/event.h" 92 #include "event2/event_struct.h" 93 #include "event2/thread.h" 94 95 #include "defer-internal.h" 96 #include "log-internal.h" 97 #include "mm-internal.h" 98 #include "strlcpy-internal.h" 99 #include "ipv6-internal.h" 100 #include "util-internal.h" 101 #include "evthread-internal.h" 102 #ifdef _WIN32 103 #include <ctype.h> 104 #include <winsock2.h> 105 #include <windows.h> 106 #include <iphlpapi.h> 107 #include <io.h> 108 #else 109 #include <sys/socket.h> 110 #include <netinet/in.h> 111 #include <arpa/inet.h> 112 #endif 113 114 #ifdef EVENT__HAVE_NETINET_IN6_H 115 #include <netinet/in6.h> 116 #endif 117 118 #define EVDNS_LOG_DEBUG EVENT_LOG_DEBUG 119 #define EVDNS_LOG_WARN EVENT_LOG_WARN 120 #define EVDNS_LOG_MSG EVENT_LOG_MSG 121 122 #ifndef HOST_NAME_MAX 123 #define HOST_NAME_MAX 255 124 #endif 125 126 #include <stdio.h> 127 128 #undef MIN 129 #define MIN(a,b) ((a)<(b)?(a):(b)) 130 131 #define ASSERT_VALID_REQUEST(req) \ 132 EVUTIL_ASSERT((req)->handle && (req)->handle->current_req == (req)) 133 134 #define u64 ev_uint64_t 135 #define u32 ev_uint32_t 136 #define u16 ev_uint16_t 137 #define u8 ev_uint8_t 138 139 /* maximum number of addresses from a single packet */ 140 /* that we bother recording */ 141 #define MAX_V4_ADDRS 32 142 #define MAX_V6_ADDRS 32 143 144 145 #define TYPE_A EVDNS_TYPE_A 146 #define TYPE_CNAME 5 147 #define TYPE_PTR EVDNS_TYPE_PTR 148 #define TYPE_SOA EVDNS_TYPE_SOA 149 #define TYPE_AAAA EVDNS_TYPE_AAAA 150 151 #define CLASS_INET EVDNS_CLASS_INET 152 153 /* Persistent handle. We keep this separate from 'struct request' since we 154 * need some object to last for as long as an evdns_request is outstanding so 155 * that it can be canceled, whereas a search request can lead to multiple 156 * 'struct request' instances being created over its lifetime. */ 157 struct evdns_request { 158 struct request *current_req; 159 struct evdns_base *base; 160 161 int pending_cb; /* Waiting for its callback to be invoked; not 162 * owned by event base any more. */ 163 164 /* elements used by the searching code */ 165 int search_index; 166 struct search_state *search_state; 167 char *search_origname; /* needs to be free()ed */ 168 int search_flags; 169 }; 170 171 struct request { 172 u8 *request; /* the dns packet data */ 173 u8 request_type; /* TYPE_PTR or TYPE_A or TYPE_AAAA */ 174 unsigned int request_len; 175 int reissue_count; 176 int tx_count; /* the number of times that this packet has been sent */ 177 void *user_pointer; /* the pointer given to us for this request */ 178 evdns_callback_type user_callback; 179 struct nameserver *ns; /* the server which we last sent it */ 180 181 /* these objects are kept in a circular list */ 182 /* XXX We could turn this into a CIRCLEQ. */ 183 struct request *next, *prev; 184 185 struct event timeout_event; 186 187 u16 trans_id; /* the transaction id */ 188 unsigned request_appended :1; /* true if the request pointer is data which follows this struct */ 189 unsigned transmit_me :1; /* needs to be transmitted */ 190 191 /* XXXX This is a horrible hack. */ 192 char **put_cname_in_ptr; /* store the cname here if we get one. */ 193 194 struct evdns_base *base; 195 196 struct evdns_request *handle; 197 }; 198 199 struct reply { 200 unsigned int type; 201 unsigned int have_answer : 1; 202 union { 203 struct { 204 u32 addrcount; 205 u32 addresses[MAX_V4_ADDRS]; 206 } a; 207 struct { 208 u32 addrcount; 209 struct in6_addr addresses[MAX_V6_ADDRS]; 210 } aaaa; 211 struct { 212 char name[HOST_NAME_MAX]; 213 } ptr; 214 } data; 215 }; 216 217 struct nameserver { 218 evutil_socket_t socket; /* a connected UDP socket */ 219 struct sockaddr_storage address; 220 ev_socklen_t addrlen; 221 int failed_times; /* number of times which we have given this server a chance */ 222 int timedout; /* number of times in a row a request has timed out */ 223 struct event event; 224 /* these objects are kept in a circular list */ 225 struct nameserver *next, *prev; 226 struct event timeout_event; /* used to keep the timeout for */ 227 /* when we next probe this server. */ 228 /* Valid if state == 0 */ 229 /* Outstanding probe request for this nameserver, if any */ 230 struct evdns_request *probe_request; 231 char state; /* zero if we think that this server is down */ 232 char choked; /* true if we have an EAGAIN from this server's socket */ 233 char write_waiting; /* true if we are waiting for EV_WRITE events */ 234 struct evdns_base *base; 235 236 /* Number of currently inflight requests: used 237 * to track when we should add/del the event. */ 238 int requests_inflight; 239 }; 240 241 242 /* Represents a local port where we're listening for DNS requests. Right now, */ 243 /* only UDP is supported. */ 244 struct evdns_server_port { 245 evutil_socket_t socket; /* socket we use to read queries and write replies. */ 246 int refcnt; /* reference count. */ 247 char choked; /* Are we currently blocked from writing? */ 248 char closing; /* Are we trying to close this port, pending writes? */ 249 evdns_request_callback_fn_type user_callback; /* Fn to handle requests */ 250 void *user_data; /* Opaque pointer passed to user_callback */ 251 struct event event; /* Read/write event */ 252 /* circular list of replies that we want to write. */ 253 struct server_request *pending_replies; 254 struct event_base *event_base; 255 256 #ifndef EVENT__DISABLE_THREAD_SUPPORT 257 void *lock; 258 #endif 259 }; 260 261 /* Represents part of a reply being built. (That is, a single RR.) */ 262 struct server_reply_item { 263 struct server_reply_item *next; /* next item in sequence. */ 264 char *name; /* name part of the RR */ 265 u16 type; /* The RR type */ 266 u16 class; /* The RR class (usually CLASS_INET) */ 267 u32 ttl; /* The RR TTL */ 268 char is_name; /* True iff data is a label */ 269 u16 datalen; /* Length of data; -1 if data is a label */ 270 void *data; /* The contents of the RR */ 271 }; 272 273 /* Represents a request that we've received as a DNS server, and holds */ 274 /* the components of the reply as we're constructing it. */ 275 struct server_request { 276 /* Pointers to the next and previous entries on the list of replies */ 277 /* that we're waiting to write. Only set if we have tried to respond */ 278 /* and gotten EAGAIN. */ 279 struct server_request *next_pending; 280 struct server_request *prev_pending; 281 282 u16 trans_id; /* Transaction id. */ 283 struct evdns_server_port *port; /* Which port received this request on? */ 284 struct sockaddr_storage addr; /* Where to send the response */ 285 ev_socklen_t addrlen; /* length of addr */ 286 287 int n_answer; /* how many answer RRs have been set? */ 288 int n_authority; /* how many authority RRs have been set? */ 289 int n_additional; /* how many additional RRs have been set? */ 290 291 struct server_reply_item *answer; /* linked list of answer RRs */ 292 struct server_reply_item *authority; /* linked list of authority RRs */ 293 struct server_reply_item *additional; /* linked list of additional RRs */ 294 295 /* Constructed response. Only set once we're ready to send a reply. */ 296 /* Once this is set, the RR fields are cleared, and no more should be set. */ 297 char *response; 298 size_t response_len; 299 300 /* Caller-visible fields: flags, questions. */ 301 struct evdns_server_request base; 302 }; 303 304 struct evdns_base { 305 /* An array of n_req_heads circular lists for inflight requests. 306 * Each inflight request req is in req_heads[req->trans_id % n_req_heads]. 307 */ 308 struct request **req_heads; 309 /* A circular list of requests that we're waiting to send, but haven't 310 * sent yet because there are too many requests inflight */ 311 struct request *req_waiting_head; 312 /* A circular list of nameservers. */ 313 struct nameserver *server_head; 314 int n_req_heads; 315 316 struct event_base *event_base; 317 318 /* The number of good nameservers that we have */ 319 int global_good_nameservers; 320 321 /* inflight requests are contained in the req_head list */ 322 /* and are actually going out across the network */ 323 int global_requests_inflight; 324 /* requests which aren't inflight are in the waiting list */ 325 /* and are counted here */ 326 int global_requests_waiting; 327 328 int global_max_requests_inflight; 329 330 struct timeval global_timeout; /* 5 seconds by default */ 331 int global_max_reissues; /* a reissue occurs when we get some errors from the server */ 332 int global_max_retransmits; /* number of times we'll retransmit a request which timed out */ 333 /* number of timeouts in a row before we consider this server to be down */ 334 int global_max_nameserver_timeout; 335 /* true iff we will use the 0x20 hack to prevent poisoning attacks. */ 336 int global_randomize_case; 337 338 /* The first time that a nameserver fails, how long do we wait before 339 * probing to see if it has returned? */ 340 struct timeval global_nameserver_probe_initial_timeout; 341 342 /** Port to bind to for outgoing DNS packets. */ 343 struct sockaddr_storage global_outgoing_address; 344 /** ev_socklen_t for global_outgoing_address. 0 if it isn't set. */ 345 ev_socklen_t global_outgoing_addrlen; 346 347 struct timeval global_getaddrinfo_allow_skew; 348 349 int getaddrinfo_ipv4_timeouts; 350 int getaddrinfo_ipv6_timeouts; 351 int getaddrinfo_ipv4_answered; 352 int getaddrinfo_ipv6_answered; 353 354 struct search_state *global_search_state; 355 356 TAILQ_HEAD(hosts_list, hosts_entry) hostsdb; 357 358 #ifndef EVENT__DISABLE_THREAD_SUPPORT 359 void *lock; 360 #endif 361 362 int disable_when_inactive; 363 }; 364 365 struct hosts_entry { 366 TAILQ_ENTRY(hosts_entry) next; 367 union { 368 struct sockaddr sa; 369 struct sockaddr_in sin; 370 struct sockaddr_in6 sin6; 371 } addr; 372 int addrlen; 373 char hostname[1]; 374 }; 375 376 static struct evdns_base *current_base = NULL; 377 378 struct evdns_base * 379 evdns_get_global_base(void) 380 { 381 return current_base; 382 } 383 384 /* Given a pointer to an evdns_server_request, get the corresponding */ 385 /* server_request. */ 386 #define TO_SERVER_REQUEST(base_ptr) \ 387 ((struct server_request*) \ 388 (((char*)(base_ptr) - evutil_offsetof(struct server_request, base)))) 389 390 #define REQ_HEAD(base, id) ((base)->req_heads[id % (base)->n_req_heads]) 391 392 static struct nameserver *nameserver_pick(struct evdns_base *base); 393 static void evdns_request_insert(struct request *req, struct request **head); 394 static void evdns_request_remove(struct request *req, struct request **head); 395 static void nameserver_ready_callback(evutil_socket_t fd, short events, void *arg); 396 static int evdns_transmit(struct evdns_base *base); 397 static int evdns_request_transmit(struct request *req); 398 static void nameserver_send_probe(struct nameserver *const ns); 399 static void search_request_finished(struct evdns_request *const); 400 static int search_try_next(struct evdns_request *const req); 401 static struct request *search_request_new(struct evdns_base *base, struct evdns_request *handle, int type, const char *const name, int flags, evdns_callback_type user_callback, void *user_arg); 402 static void evdns_requests_pump_waiting_queue(struct evdns_base *base); 403 static u16 transaction_id_pick(struct evdns_base *base); 404 static struct request *request_new(struct evdns_base *base, struct evdns_request *handle, int type, const char *name, int flags, evdns_callback_type callback, void *ptr); 405 static void request_submit(struct request *const req); 406 407 static int server_request_free(struct server_request *req); 408 static void server_request_free_answers(struct server_request *req); 409 static void server_port_free(struct evdns_server_port *port); 410 static void server_port_ready_callback(evutil_socket_t fd, short events, void *arg); 411 static int evdns_base_resolv_conf_parse_impl(struct evdns_base *base, int flags, const char *const filename); 412 static int evdns_base_set_option_impl(struct evdns_base *base, 413 const char *option, const char *val, int flags); 414 static void evdns_base_free_and_unlock(struct evdns_base *base, int fail_requests); 415 static void evdns_request_timeout_callback(evutil_socket_t fd, short events, void *arg); 416 417 static int strtoint(const char *const str); 418 419 #ifdef EVENT__DISABLE_THREAD_SUPPORT 420 #define EVDNS_LOCK(base) EVUTIL_NIL_STMT_ 421 #define EVDNS_UNLOCK(base) EVUTIL_NIL_STMT_ 422 #define ASSERT_LOCKED(base) EVUTIL_NIL_STMT_ 423 #else 424 #define EVDNS_LOCK(base) \ 425 EVLOCK_LOCK((base)->lock, 0) 426 #define EVDNS_UNLOCK(base) \ 427 EVLOCK_UNLOCK((base)->lock, 0) 428 #define ASSERT_LOCKED(base) \ 429 EVLOCK_ASSERT_LOCKED((base)->lock) 430 #endif 431 432 static evdns_debug_log_fn_type evdns_log_fn = NULL; 433 434 void 435 evdns_set_log_fn(evdns_debug_log_fn_type fn) 436 { 437 evdns_log_fn = fn; 438 } 439 440 #ifdef __GNUC__ 441 #define EVDNS_LOG_CHECK __attribute__ ((format(printf, 2, 3))) 442 #else 443 #define EVDNS_LOG_CHECK 444 #endif 445 446 static void evdns_log_(int severity, const char *fmt, ...) EVDNS_LOG_CHECK; 447 static void 448 evdns_log_(int severity, const char *fmt, ...) 449 { 450 va_list args; 451 va_start(args,fmt); 452 if (evdns_log_fn) { 453 char buf[512]; 454 int is_warn = (severity == EVDNS_LOG_WARN); 455 evutil_vsnprintf(buf, sizeof(buf), fmt, args); 456 evdns_log_fn(is_warn, buf); 457 } else { 458 event_logv_(severity, NULL, fmt, args); 459 } 460 va_end(args); 461 } 462 463 #define log evdns_log_ 464 465 /* This walks the list of inflight requests to find the */ 466 /* one with a matching transaction id. Returns NULL on */ 467 /* failure */ 468 static struct request * 469 request_find_from_trans_id(struct evdns_base *base, u16 trans_id) { 470 struct request *req = REQ_HEAD(base, trans_id); 471 struct request *const started_at = req; 472 473 ASSERT_LOCKED(base); 474 475 if (req) { 476 do { 477 if (req->trans_id == trans_id) return req; 478 req = req->next; 479 } while (req != started_at); 480 } 481 482 return NULL; 483 } 484 485 /* a libevent callback function which is called when a nameserver */ 486 /* has gone down and we want to test if it has came back to life yet */ 487 static void 488 nameserver_prod_callback(evutil_socket_t fd, short events, void *arg) { 489 struct nameserver *const ns = (struct nameserver *) arg; 490 (void)fd; 491 (void)events; 492 493 EVDNS_LOCK(ns->base); 494 nameserver_send_probe(ns); 495 EVDNS_UNLOCK(ns->base); 496 } 497 498 /* a libevent callback which is called when a nameserver probe (to see if */ 499 /* it has come back to life) times out. We increment the count of failed_times */ 500 /* and wait longer to send the next probe packet. */ 501 static void 502 nameserver_probe_failed(struct nameserver *const ns) { 503 struct timeval timeout; 504 int i; 505 506 ASSERT_LOCKED(ns->base); 507 (void) evtimer_del(&ns->timeout_event); 508 if (ns->state == 1) { 509 /* This can happen if the nameserver acts in a way which makes us mark */ 510 /* it as bad and then starts sending good replies. */ 511 return; 512 } 513 514 #define MAX_PROBE_TIMEOUT 3600 515 #define TIMEOUT_BACKOFF_FACTOR 3 516 517 memcpy(&timeout, &ns->base->global_nameserver_probe_initial_timeout, 518 sizeof(struct timeval)); 519 for (i=ns->failed_times; i > 0 && timeout.tv_sec < MAX_PROBE_TIMEOUT; --i) { 520 timeout.tv_sec *= TIMEOUT_BACKOFF_FACTOR; 521 timeout.tv_usec *= TIMEOUT_BACKOFF_FACTOR; 522 if (timeout.tv_usec > 1000000) { 523 timeout.tv_sec += timeout.tv_usec / 1000000; 524 timeout.tv_usec %= 1000000; 525 } 526 } 527 if (timeout.tv_sec > MAX_PROBE_TIMEOUT) { 528 timeout.tv_sec = MAX_PROBE_TIMEOUT; 529 timeout.tv_usec = 0; 530 } 531 532 ns->failed_times++; 533 534 if (evtimer_add(&ns->timeout_event, &timeout) < 0) { 535 char addrbuf[128]; 536 log(EVDNS_LOG_WARN, 537 "Error from libevent when adding timer event for %s", 538 evutil_format_sockaddr_port_( 539 (struct sockaddr *)&ns->address, 540 addrbuf, sizeof(addrbuf))); 541 } 542 } 543 544 static void 545 request_swap_ns(struct request *req, struct nameserver *ns) { 546 if (ns && req->ns != ns) { 547 EVUTIL_ASSERT(req->ns->requests_inflight > 0); 548 req->ns->requests_inflight--; 549 ns->requests_inflight++; 550 551 req->ns = ns; 552 } 553 } 554 555 /* called when a nameserver has been deemed to have failed. For example, too */ 556 /* many packets have timed out etc */ 557 static void 558 nameserver_failed(struct nameserver *const ns, const char *msg) { 559 struct request *req, *started_at; 560 struct evdns_base *base = ns->base; 561 int i; 562 char addrbuf[128]; 563 564 ASSERT_LOCKED(base); 565 /* if this nameserver has already been marked as failed */ 566 /* then don't do anything */ 567 if (!ns->state) return; 568 569 log(EVDNS_LOG_MSG, "Nameserver %s has failed: %s", 570 evutil_format_sockaddr_port_( 571 (struct sockaddr *)&ns->address, 572 addrbuf, sizeof(addrbuf)), 573 msg); 574 575 base->global_good_nameservers--; 576 EVUTIL_ASSERT(base->global_good_nameservers >= 0); 577 if (base->global_good_nameservers == 0) { 578 log(EVDNS_LOG_MSG, "All nameservers have failed"); 579 } 580 581 ns->state = 0; 582 ns->failed_times = 1; 583 584 if (evtimer_add(&ns->timeout_event, 585 &base->global_nameserver_probe_initial_timeout) < 0) { 586 log(EVDNS_LOG_WARN, 587 "Error from libevent when adding timer event for %s", 588 evutil_format_sockaddr_port_( 589 (struct sockaddr *)&ns->address, 590 addrbuf, sizeof(addrbuf))); 591 /* ???? Do more? */ 592 } 593 594 /* walk the list of inflight requests to see if any can be reassigned to */ 595 /* a different server. Requests in the waiting queue don't have a */ 596 /* nameserver assigned yet */ 597 598 /* if we don't have *any* good nameservers then there's no point */ 599 /* trying to reassign requests to one */ 600 if (!base->global_good_nameservers) return; 601 602 for (i = 0; i < base->n_req_heads; ++i) { 603 req = started_at = base->req_heads[i]; 604 if (req) { 605 do { 606 if (req->tx_count == 0 && req->ns == ns) { 607 /* still waiting to go out, can be moved */ 608 /* to another server */ 609 request_swap_ns(req, nameserver_pick(base)); 610 } 611 req = req->next; 612 } while (req != started_at); 613 } 614 } 615 } 616 617 static void 618 nameserver_up(struct nameserver *const ns) 619 { 620 char addrbuf[128]; 621 ASSERT_LOCKED(ns->base); 622 if (ns->state) return; 623 log(EVDNS_LOG_MSG, "Nameserver %s is back up", 624 evutil_format_sockaddr_port_( 625 (struct sockaddr *)&ns->address, 626 addrbuf, sizeof(addrbuf))); 627 evtimer_del(&ns->timeout_event); 628 if (ns->probe_request) { 629 evdns_cancel_request(ns->base, ns->probe_request); 630 ns->probe_request = NULL; 631 } 632 ns->state = 1; 633 ns->failed_times = 0; 634 ns->timedout = 0; 635 ns->base->global_good_nameservers++; 636 } 637 638 static void 639 request_trans_id_set(struct request *const req, const u16 trans_id) { 640 req->trans_id = trans_id; 641 *((u16 *) req->request) = htons(trans_id); 642 } 643 644 /* Called to remove a request from a list and dealloc it. */ 645 /* head is a pointer to the head of the list it should be */ 646 /* removed from or NULL if the request isn't in a list. */ 647 /* when free_handle is one, free the handle as well. */ 648 static void 649 request_finished(struct request *const req, struct request **head, int free_handle) { 650 struct evdns_base *base = req->base; 651 int was_inflight = (head != &base->req_waiting_head); 652 EVDNS_LOCK(base); 653 ASSERT_VALID_REQUEST(req); 654 655 if (head) 656 evdns_request_remove(req, head); 657 658 log(EVDNS_LOG_DEBUG, "Removing timeout for request %p", req); 659 if (was_inflight) { 660 evtimer_del(&req->timeout_event); 661 base->global_requests_inflight--; 662 req->ns->requests_inflight--; 663 } else { 664 base->global_requests_waiting--; 665 } 666 /* it was initialized during request_new / evtimer_assign */ 667 event_debug_unassign(&req->timeout_event); 668 669 if (req->ns && 670 req->ns->requests_inflight == 0 && 671 req->base->disable_when_inactive) { 672 event_del(&req->ns->event); 673 evtimer_del(&req->ns->timeout_event); 674 } 675 676 if (!req->request_appended) { 677 /* need to free the request data on it's own */ 678 mm_free(req->request); 679 } else { 680 /* the request data is appended onto the header */ 681 /* so everything gets free()ed when we: */ 682 } 683 684 if (req->handle) { 685 EVUTIL_ASSERT(req->handle->current_req == req); 686 687 if (free_handle) { 688 search_request_finished(req->handle); 689 req->handle->current_req = NULL; 690 if (! req->handle->pending_cb) { 691 /* If we're planning to run the callback, 692 * don't free the handle until later. */ 693 mm_free(req->handle); 694 } 695 req->handle = NULL; /* If we have a bug, let's crash 696 * early */ 697 } else { 698 req->handle->current_req = NULL; 699 } 700 } 701 702 mm_free(req); 703 704 evdns_requests_pump_waiting_queue(base); 705 EVDNS_UNLOCK(base); 706 } 707 708 /* This is called when a server returns a funny error code. */ 709 /* We try the request again with another server. */ 710 /* */ 711 /* return: */ 712 /* 0 ok */ 713 /* 1 failed/reissue is pointless */ 714 static int 715 request_reissue(struct request *req) { 716 const struct nameserver *const last_ns = req->ns; 717 ASSERT_LOCKED(req->base); 718 ASSERT_VALID_REQUEST(req); 719 /* the last nameserver should have been marked as failing */ 720 /* by the caller of this function, therefore pick will try */ 721 /* not to return it */ 722 request_swap_ns(req, nameserver_pick(req->base)); 723 if (req->ns == last_ns) { 724 /* ... but pick did return it */ 725 /* not a lot of point in trying again with the */ 726 /* same server */ 727 return 1; 728 } 729 730 req->reissue_count++; 731 req->tx_count = 0; 732 req->transmit_me = 1; 733 734 return 0; 735 } 736 737 /* this function looks for space on the inflight queue and promotes */ 738 /* requests from the waiting queue if it can. */ 739 /* */ 740 /* TODO: */ 741 /* add return code, see at nameserver_pick() and other functions. */ 742 static void 743 evdns_requests_pump_waiting_queue(struct evdns_base *base) { 744 ASSERT_LOCKED(base); 745 while (base->global_requests_inflight < base->global_max_requests_inflight && 746 base->global_requests_waiting) { 747 struct request *req; 748 749 EVUTIL_ASSERT(base->req_waiting_head); 750 req = base->req_waiting_head; 751 752 req->ns = nameserver_pick(base); 753 if (!req->ns) 754 return; 755 756 /* move a request from the waiting queue to the inflight queue */ 757 req->ns->requests_inflight++; 758 759 evdns_request_remove(req, &base->req_waiting_head); 760 761 base->global_requests_waiting--; 762 base->global_requests_inflight++; 763 764 request_trans_id_set(req, transaction_id_pick(base)); 765 766 evdns_request_insert(req, &REQ_HEAD(base, req->trans_id)); 767 evdns_request_transmit(req); 768 evdns_transmit(base); 769 } 770 } 771 772 /* TODO(nickm) document */ 773 struct deferred_reply_callback { 774 struct event_callback deferred; 775 struct evdns_request *handle; 776 u8 request_type; 777 u8 have_reply; 778 u32 ttl; 779 u32 err; 780 evdns_callback_type user_callback; 781 struct reply reply; 782 }; 783 784 static void 785 reply_run_callback(struct event_callback *d, void *user_pointer) 786 { 787 struct deferred_reply_callback *cb = 788 EVUTIL_UPCAST(d, struct deferred_reply_callback, deferred); 789 790 switch (cb->request_type) { 791 case TYPE_A: 792 if (cb->have_reply) 793 cb->user_callback(DNS_ERR_NONE, DNS_IPv4_A, 794 cb->reply.data.a.addrcount, cb->ttl, 795 cb->reply.data.a.addresses, 796 user_pointer); 797 else 798 cb->user_callback(cb->err, 0, 0, cb->ttl, NULL, user_pointer); 799 break; 800 case TYPE_PTR: 801 if (cb->have_reply) { 802 char *name = cb->reply.data.ptr.name; 803 cb->user_callback(DNS_ERR_NONE, DNS_PTR, 1, cb->ttl, 804 &name, user_pointer); 805 } else { 806 cb->user_callback(cb->err, 0, 0, cb->ttl, NULL, user_pointer); 807 } 808 break; 809 case TYPE_AAAA: 810 if (cb->have_reply) 811 cb->user_callback(DNS_ERR_NONE, DNS_IPv6_AAAA, 812 cb->reply.data.aaaa.addrcount, cb->ttl, 813 cb->reply.data.aaaa.addresses, 814 user_pointer); 815 else 816 cb->user_callback(cb->err, 0, 0, cb->ttl, NULL, user_pointer); 817 break; 818 default: 819 EVUTIL_ASSERT(0); 820 } 821 822 if (cb->handle && cb->handle->pending_cb) { 823 mm_free(cb->handle); 824 } 825 826 mm_free(cb); 827 } 828 829 static void 830 reply_schedule_callback(struct request *const req, u32 ttl, u32 err, struct reply *reply) 831 { 832 struct deferred_reply_callback *d = mm_calloc(1, sizeof(*d)); 833 834 if (!d) { 835 event_warn("%s: Couldn't allocate space for deferred callback.", 836 __func__); 837 return; 838 } 839 840 ASSERT_LOCKED(req->base); 841 842 d->request_type = req->request_type; 843 d->user_callback = req->user_callback; 844 d->ttl = ttl; 845 d->err = err; 846 if (reply) { 847 d->have_reply = 1; 848 memcpy(&d->reply, reply, sizeof(struct reply)); 849 } 850 851 if (req->handle) { 852 req->handle->pending_cb = 1; 853 d->handle = req->handle; 854 } 855 856 event_deferred_cb_init_( 857 &d->deferred, 858 event_get_priority(&req->timeout_event), 859 reply_run_callback, 860 req->user_pointer); 861 event_deferred_cb_schedule_( 862 req->base->event_base, 863 &d->deferred); 864 } 865 866 /* this processes a parsed reply packet */ 867 static void 868 reply_handle(struct request *const req, u16 flags, u32 ttl, struct reply *reply) { 869 int error; 870 char addrbuf[128]; 871 static const int error_codes[] = { 872 DNS_ERR_FORMAT, DNS_ERR_SERVERFAILED, DNS_ERR_NOTEXIST, 873 DNS_ERR_NOTIMPL, DNS_ERR_REFUSED 874 }; 875 876 ASSERT_LOCKED(req->base); 877 ASSERT_VALID_REQUEST(req); 878 879 if (flags & 0x020f || !reply || !reply->have_answer) { 880 /* there was an error */ 881 if (flags & 0x0200) { 882 error = DNS_ERR_TRUNCATED; 883 } else if (flags & 0x000f) { 884 u16 error_code = (flags & 0x000f) - 1; 885 if (error_code > 4) { 886 error = DNS_ERR_UNKNOWN; 887 } else { 888 error = error_codes[error_code]; 889 } 890 } else if (reply && !reply->have_answer) { 891 error = DNS_ERR_NODATA; 892 } else { 893 error = DNS_ERR_UNKNOWN; 894 } 895 896 switch (error) { 897 case DNS_ERR_NOTIMPL: 898 case DNS_ERR_REFUSED: 899 /* we regard these errors as marking a bad nameserver */ 900 if (req->reissue_count < req->base->global_max_reissues) { 901 char msg[64]; 902 evutil_snprintf(msg, sizeof(msg), "Bad response %d (%s)", 903 error, evdns_err_to_string(error)); 904 nameserver_failed(req->ns, msg); 905 if (!request_reissue(req)) return; 906 } 907 break; 908 case DNS_ERR_SERVERFAILED: 909 /* rcode 2 (servfailed) sometimes means "we 910 * are broken" and sometimes (with some binds) 911 * means "that request was very confusing." 912 * Treat this as a timeout, not a failure. 913 */ 914 log(EVDNS_LOG_DEBUG, "Got a SERVERFAILED from nameserver" 915 "at %s; will allow the request to time out.", 916 evutil_format_sockaddr_port_( 917 (struct sockaddr *)&req->ns->address, 918 addrbuf, sizeof(addrbuf))); 919 /* Call the timeout function */ 920 evdns_request_timeout_callback(0, 0, req); 921 return; 922 default: 923 /* we got a good reply from the nameserver: it is up. */ 924 if (req->handle == req->ns->probe_request) { 925 /* Avoid double-free */ 926 req->ns->probe_request = NULL; 927 } 928 929 nameserver_up(req->ns); 930 } 931 932 if (req->handle->search_state && 933 req->request_type != TYPE_PTR) { 934 /* if we have a list of domains to search in, 935 * try the next one */ 936 if (!search_try_next(req->handle)) { 937 /* a new request was issued so this 938 * request is finished and */ 939 /* the user callback will be made when 940 * that request (or a */ 941 /* child of it) finishes. */ 942 return; 943 } 944 } 945 946 /* all else failed. Pass the failure up */ 947 reply_schedule_callback(req, ttl, error, NULL); 948 request_finished(req, &REQ_HEAD(req->base, req->trans_id), 1); 949 } else { 950 /* all ok, tell the user */ 951 reply_schedule_callback(req, ttl, 0, reply); 952 if (req->handle == req->ns->probe_request) 953 req->ns->probe_request = NULL; /* Avoid double-free */ 954 nameserver_up(req->ns); 955 request_finished(req, &REQ_HEAD(req->base, req->trans_id), 1); 956 } 957 } 958 959 static int 960 name_parse(u8 *packet, int length, int *idx, char *name_out, int name_out_len) { 961 int name_end = -1; 962 int j = *idx; 963 int ptr_count = 0; 964 #define GET32(x) do { if (j + 4 > length) goto err; memcpy(&t32_, packet + j, 4); j += 4; x = ntohl(t32_); } while (0) 965 #define GET16(x) do { if (j + 2 > length) goto err; memcpy(&t_, packet + j, 2); j += 2; x = ntohs(t_); } while (0) 966 #define GET8(x) do { if (j >= length) goto err; x = packet[j++]; } while (0) 967 968 char *cp = name_out; 969 const char *const end = name_out + name_out_len; 970 971 /* Normally, names are a series of length prefixed strings terminated */ 972 /* with a length of 0 (the lengths are u8's < 63). */ 973 /* However, the length can start with a pair of 1 bits and that */ 974 /* means that the next 14 bits are a pointer within the current */ 975 /* packet. */ 976 977 for (;;) { 978 u8 label_len; 979 GET8(label_len); 980 if (!label_len) break; 981 if (label_len & 0xc0) { 982 u8 ptr_low; 983 GET8(ptr_low); 984 if (name_end < 0) name_end = j; 985 j = (((int)label_len & 0x3f) << 8) + ptr_low; 986 /* Make sure that the target offset is in-bounds. */ 987 if (j < 0 || j >= length) return -1; 988 /* If we've jumped more times than there are characters in the 989 * message, we must have a loop. */ 990 if (++ptr_count > length) return -1; 991 continue; 992 } 993 if (label_len > 63) return -1; 994 if (cp != name_out) { 995 if (cp + 1 >= end) return -1; 996 *cp++ = '.'; 997 } 998 if (cp + label_len >= end) return -1; 999 if (j + label_len > length) return -1; 1000 memcpy(cp, packet + j, label_len); 1001 cp += label_len; 1002 j += label_len; 1003 } 1004 if (cp >= end) return -1; 1005 *cp = '\0'; 1006 if (name_end < 0) 1007 *idx = j; 1008 else 1009 *idx = name_end; 1010 return 0; 1011 err: 1012 return -1; 1013 } 1014 1015 /* parses a raw request from a nameserver */ 1016 static int 1017 reply_parse(struct evdns_base *base, u8 *packet, int length) { 1018 int j = 0, k = 0; /* index into packet */ 1019 u16 t_; /* used by the macros */ 1020 u32 t32_; /* used by the macros */ 1021 char tmp_name[256], cmp_name[256]; /* used by the macros */ 1022 int name_matches = 0; 1023 1024 u16 trans_id, questions, answers, authority, additional, datalength; 1025 u16 flags = 0; 1026 u32 ttl, ttl_r = 0xffffffff; 1027 struct reply reply; 1028 struct request *req = NULL; 1029 unsigned int i; 1030 1031 ASSERT_LOCKED(base); 1032 1033 GET16(trans_id); 1034 GET16(flags); 1035 GET16(questions); 1036 GET16(answers); 1037 GET16(authority); 1038 GET16(additional); 1039 (void) authority; /* suppress "unused variable" warnings. */ 1040 (void) additional; /* suppress "unused variable" warnings. */ 1041 1042 req = request_find_from_trans_id(base, trans_id); 1043 if (!req) return -1; 1044 EVUTIL_ASSERT(req->base == base); 1045 1046 memset(&reply, 0, sizeof(reply)); 1047 1048 /* If it's not an answer, it doesn't correspond to any request. */ 1049 if (!(flags & 0x8000)) return -1; /* must be an answer */ 1050 if ((flags & 0x020f) && (flags & 0x020f) != DNS_ERR_NOTEXIST) { 1051 /* there was an error and it's not NXDOMAIN */ 1052 goto err; 1053 } 1054 /* if (!answers) return; */ /* must have an answer of some form */ 1055 1056 /* This macro skips a name in the DNS reply. */ 1057 #define SKIP_NAME \ 1058 do { tmp_name[0] = '\0'; \ 1059 if (name_parse(packet, length, &j, tmp_name, \ 1060 sizeof(tmp_name))<0) \ 1061 goto err; \ 1062 } while (0) 1063 1064 reply.type = req->request_type; 1065 1066 /* skip over each question in the reply */ 1067 for (i = 0; i < questions; ++i) { 1068 /* the question looks like 1069 * <label:name><u16:type><u16:class> 1070 */ 1071 tmp_name[0] = '\0'; 1072 cmp_name[0] = '\0'; 1073 k = j; 1074 if (name_parse(packet, length, &j, tmp_name, sizeof(tmp_name)) < 0) 1075 goto err; 1076 if (name_parse(req->request, req->request_len, &k, 1077 cmp_name, sizeof(cmp_name))<0) 1078 goto err; 1079 if (!base->global_randomize_case) { 1080 if (strcmp(tmp_name, cmp_name) == 0) 1081 name_matches = 1; 1082 } else { 1083 if (evutil_ascii_strcasecmp(tmp_name, cmp_name) == 0) 1084 name_matches = 1; 1085 } 1086 1087 j += 4; 1088 if (j > length) 1089 goto err; 1090 } 1091 1092 if (!name_matches) 1093 goto err; 1094 1095 /* now we have the answer section which looks like 1096 * <label:name><u16:type><u16:class><u32:ttl><u16:len><data...> 1097 */ 1098 1099 for (i = 0; i < answers; ++i) { 1100 u16 type, class; 1101 1102 SKIP_NAME; 1103 GET16(type); 1104 GET16(class); 1105 GET32(ttl); 1106 GET16(datalength); 1107 1108 if (type == TYPE_A && class == CLASS_INET) { 1109 int addrcount, addrtocopy; 1110 if (req->request_type != TYPE_A) { 1111 j += datalength; continue; 1112 } 1113 if ((datalength & 3) != 0) /* not an even number of As. */ 1114 goto err; 1115 addrcount = datalength >> 2; 1116 addrtocopy = MIN(MAX_V4_ADDRS - reply.data.a.addrcount, (unsigned)addrcount); 1117 1118 ttl_r = MIN(ttl_r, ttl); 1119 /* we only bother with the first four addresses. */ 1120 if (j + 4*addrtocopy > length) goto err; 1121 memcpy(&reply.data.a.addresses[reply.data.a.addrcount], 1122 packet + j, 4*addrtocopy); 1123 j += 4*addrtocopy; 1124 reply.data.a.addrcount += addrtocopy; 1125 reply.have_answer = 1; 1126 if (reply.data.a.addrcount == MAX_V4_ADDRS) break; 1127 } else if (type == TYPE_PTR && class == CLASS_INET) { 1128 if (req->request_type != TYPE_PTR) { 1129 j += datalength; continue; 1130 } 1131 if (name_parse(packet, length, &j, reply.data.ptr.name, 1132 sizeof(reply.data.ptr.name))<0) 1133 goto err; 1134 ttl_r = MIN(ttl_r, ttl); 1135 reply.have_answer = 1; 1136 break; 1137 } else if (type == TYPE_CNAME) { 1138 char cname[HOST_NAME_MAX]; 1139 if (!req->put_cname_in_ptr || *req->put_cname_in_ptr) { 1140 j += datalength; continue; 1141 } 1142 if (name_parse(packet, length, &j, cname, 1143 sizeof(cname))<0) 1144 goto err; 1145 *req->put_cname_in_ptr = mm_strdup(cname); 1146 } else if (type == TYPE_AAAA && class == CLASS_INET) { 1147 int addrcount, addrtocopy; 1148 if (req->request_type != TYPE_AAAA) { 1149 j += datalength; continue; 1150 } 1151 if ((datalength & 15) != 0) /* not an even number of AAAAs. */ 1152 goto err; 1153 addrcount = datalength >> 4; /* each address is 16 bytes long */ 1154 addrtocopy = MIN(MAX_V6_ADDRS - reply.data.aaaa.addrcount, (unsigned)addrcount); 1155 ttl_r = MIN(ttl_r, ttl); 1156 1157 /* we only bother with the first four addresses. */ 1158 if (j + 16*addrtocopy > length) goto err; 1159 memcpy(&reply.data.aaaa.addresses[reply.data.aaaa.addrcount], 1160 packet + j, 16*addrtocopy); 1161 reply.data.aaaa.addrcount += addrtocopy; 1162 j += 16*addrtocopy; 1163 reply.have_answer = 1; 1164 if (reply.data.aaaa.addrcount == MAX_V6_ADDRS) break; 1165 } else { 1166 /* skip over any other type of resource */ 1167 j += datalength; 1168 } 1169 } 1170 1171 if (!reply.have_answer) { 1172 for (i = 0; i < authority; ++i) { 1173 u16 type, class; 1174 SKIP_NAME; 1175 GET16(type); 1176 GET16(class); 1177 GET32(ttl); 1178 GET16(datalength); 1179 if (type == TYPE_SOA && class == CLASS_INET) { 1180 u32 serial, refresh, retry, expire, minimum; 1181 SKIP_NAME; 1182 SKIP_NAME; 1183 GET32(serial); 1184 GET32(refresh); 1185 GET32(retry); 1186 GET32(expire); 1187 GET32(minimum); 1188 (void)expire; 1189 (void)retry; 1190 (void)refresh; 1191 (void)serial; 1192 ttl_r = MIN(ttl_r, ttl); 1193 ttl_r = MIN(ttl_r, minimum); 1194 } else { 1195 /* skip over any other type of resource */ 1196 j += datalength; 1197 } 1198 } 1199 } 1200 1201 if (ttl_r == 0xffffffff) 1202 ttl_r = 0; 1203 1204 reply_handle(req, flags, ttl_r, &reply); 1205 return 0; 1206 err: 1207 if (req) 1208 reply_handle(req, flags, 0, NULL); 1209 return -1; 1210 } 1211 1212 /* Parse a raw request (packet,length) sent to a nameserver port (port) from */ 1213 /* a DNS client (addr,addrlen), and if it's well-formed, call the corresponding */ 1214 /* callback. */ 1215 static int 1216 request_parse(u8 *packet, int length, struct evdns_server_port *port, struct sockaddr *addr, ev_socklen_t addrlen) 1217 { 1218 int j = 0; /* index into packet */ 1219 u16 t_; /* used by the macros */ 1220 char tmp_name[256]; /* used by the macros */ 1221 1222 int i; 1223 u16 trans_id, flags, questions, answers, authority, additional; 1224 struct server_request *server_req = NULL; 1225 1226 ASSERT_LOCKED(port); 1227 1228 /* Get the header fields */ 1229 GET16(trans_id); 1230 GET16(flags); 1231 GET16(questions); 1232 GET16(answers); 1233 GET16(authority); 1234 GET16(additional); 1235 (void)answers; 1236 (void)additional; 1237 (void)authority; 1238 1239 if (flags & 0x8000) return -1; /* Must not be an answer. */ 1240 flags &= 0x0110; /* Only RD and CD get preserved. */ 1241 1242 server_req = mm_malloc(sizeof(struct server_request)); 1243 if (server_req == NULL) return -1; 1244 memset(server_req, 0, sizeof(struct server_request)); 1245 1246 server_req->trans_id = trans_id; 1247 memcpy(&server_req->addr, addr, addrlen); 1248 server_req->addrlen = addrlen; 1249 1250 server_req->base.flags = flags; 1251 server_req->base.nquestions = 0; 1252 server_req->base.questions = mm_calloc(sizeof(struct evdns_server_question *), questions); 1253 if (server_req->base.questions == NULL) 1254 goto err; 1255 1256 for (i = 0; i < questions; ++i) { 1257 u16 type, class; 1258 struct evdns_server_question *q; 1259 int namelen; 1260 if (name_parse(packet, length, &j, tmp_name, sizeof(tmp_name))<0) 1261 goto err; 1262 GET16(type); 1263 GET16(class); 1264 namelen = (int)strlen(tmp_name); 1265 q = mm_malloc(sizeof(struct evdns_server_question) + namelen); 1266 if (!q) 1267 goto err; 1268 q->type = type; 1269 q->dns_question_class = class; 1270 memcpy(q->name, tmp_name, namelen+1); 1271 server_req->base.questions[server_req->base.nquestions++] = q; 1272 } 1273 1274 /* Ignore answers, authority, and additional. */ 1275 1276 server_req->port = port; 1277 port->refcnt++; 1278 1279 /* Only standard queries are supported. */ 1280 if (flags & 0x7800) { 1281 evdns_server_request_respond(&(server_req->base), DNS_ERR_NOTIMPL); 1282 return -1; 1283 } 1284 1285 port->user_callback(&(server_req->base), port->user_data); 1286 1287 return 0; 1288 err: 1289 if (server_req) { 1290 if (server_req->base.questions) { 1291 for (i = 0; i < server_req->base.nquestions; ++i) 1292 mm_free(server_req->base.questions[i]); 1293 mm_free(server_req->base.questions); 1294 } 1295 mm_free(server_req); 1296 } 1297 return -1; 1298 1299 #undef SKIP_NAME 1300 #undef GET32 1301 #undef GET16 1302 #undef GET8 1303 } 1304 1305 1306 void 1307 evdns_set_transaction_id_fn(ev_uint16_t (*fn)(void)) 1308 { 1309 } 1310 1311 void 1312 evdns_set_random_bytes_fn(void (*fn)(char *, size_t)) 1313 { 1314 } 1315 1316 /* Try to choose a strong transaction id which isn't already in flight */ 1317 static u16 1318 transaction_id_pick(struct evdns_base *base) { 1319 ASSERT_LOCKED(base); 1320 for (;;) { 1321 u16 trans_id; 1322 evutil_secure_rng_get_bytes(&trans_id, sizeof(trans_id)); 1323 1324 if (trans_id == 0xffff) continue; 1325 /* now check to see if that id is already inflight */ 1326 if (request_find_from_trans_id(base, trans_id) == NULL) 1327 return trans_id; 1328 } 1329 } 1330 1331 /* choose a namesever to use. This function will try to ignore */ 1332 /* nameservers which we think are down and load balance across the rest */ 1333 /* by updating the server_head global each time. */ 1334 static struct nameserver * 1335 nameserver_pick(struct evdns_base *base) { 1336 struct nameserver *started_at = base->server_head, *picked; 1337 ASSERT_LOCKED(base); 1338 if (!base->server_head) return NULL; 1339 1340 /* if we don't have any good nameservers then there's no */ 1341 /* point in trying to find one. */ 1342 if (!base->global_good_nameservers) { 1343 base->server_head = base->server_head->next; 1344 return base->server_head; 1345 } 1346 1347 /* remember that nameservers are in a circular list */ 1348 for (;;) { 1349 if (base->server_head->state) { 1350 /* we think this server is currently good */ 1351 picked = base->server_head; 1352 base->server_head = base->server_head->next; 1353 return picked; 1354 } 1355 1356 base->server_head = base->server_head->next; 1357 if (base->server_head == started_at) { 1358 /* all the nameservers seem to be down */ 1359 /* so we just return this one and hope for the */ 1360 /* best */ 1361 EVUTIL_ASSERT(base->global_good_nameservers == 0); 1362 picked = base->server_head; 1363 base->server_head = base->server_head->next; 1364 return picked; 1365 } 1366 } 1367 } 1368 1369 /* this is called when a namesever socket is ready for reading */ 1370 static void 1371 nameserver_read(struct nameserver *ns) { 1372 struct sockaddr_storage ss; 1373 ev_socklen_t addrlen = sizeof(ss); 1374 u8 packet[1500]; 1375 char addrbuf[128]; 1376 ASSERT_LOCKED(ns->base); 1377 1378 for (;;) { 1379 const int r = recvfrom(ns->socket, (void*)packet, 1380 sizeof(packet), 0, 1381 (struct sockaddr*)&ss, &addrlen); 1382 if (r < 0) { 1383 int err = evutil_socket_geterror(ns->socket); 1384 if (EVUTIL_ERR_RW_RETRIABLE(err)) 1385 return; 1386 nameserver_failed(ns, 1387 evutil_socket_error_to_string(err)); 1388 return; 1389 } 1390 if (evutil_sockaddr_cmp((struct sockaddr*)&ss, 1391 (struct sockaddr*)&ns->address, 0)) { 1392 log(EVDNS_LOG_WARN, "Address mismatch on received " 1393 "DNS packet. Apparent source was %s", 1394 evutil_format_sockaddr_port_( 1395 (struct sockaddr *)&ss, 1396 addrbuf, sizeof(addrbuf))); 1397 return; 1398 } 1399 1400 ns->timedout = 0; 1401 reply_parse(ns->base, packet, r); 1402 } 1403 } 1404 1405 /* Read a packet from a DNS client on a server port s, parse it, and */ 1406 /* act accordingly. */ 1407 static void 1408 server_port_read(struct evdns_server_port *s) { 1409 u8 packet[1500]; 1410 struct sockaddr_storage addr; 1411 ev_socklen_t addrlen; 1412 int r; 1413 ASSERT_LOCKED(s); 1414 1415 for (;;) { 1416 addrlen = sizeof(struct sockaddr_storage); 1417 r = recvfrom(s->socket, (void*)packet, sizeof(packet), 0, 1418 (struct sockaddr*) &addr, &addrlen); 1419 if (r < 0) { 1420 int err = evutil_socket_geterror(s->socket); 1421 if (EVUTIL_ERR_RW_RETRIABLE(err)) 1422 return; 1423 log(EVDNS_LOG_WARN, 1424 "Error %s (%d) while reading request.", 1425 evutil_socket_error_to_string(err), err); 1426 return; 1427 } 1428 request_parse(packet, r, s, (struct sockaddr*) &addr, addrlen); 1429 } 1430 } 1431 1432 /* Try to write all pending replies on a given DNS server port. */ 1433 static void 1434 server_port_flush(struct evdns_server_port *port) 1435 { 1436 struct server_request *req = port->pending_replies; 1437 ASSERT_LOCKED(port); 1438 while (req) { 1439 int r = sendto(port->socket, req->response, (int)req->response_len, 0, 1440 (struct sockaddr*) &req->addr, (ev_socklen_t)req->addrlen); 1441 if (r < 0) { 1442 int err = evutil_socket_geterror(port->socket); 1443 if (EVUTIL_ERR_RW_RETRIABLE(err)) 1444 return; 1445 log(EVDNS_LOG_WARN, "Error %s (%d) while writing response to port; dropping", evutil_socket_error_to_string(err), err); 1446 } 1447 if (server_request_free(req)) { 1448 /* we released the last reference to req->port. */ 1449 return; 1450 } else { 1451 EVUTIL_ASSERT(req != port->pending_replies); 1452 req = port->pending_replies; 1453 } 1454 } 1455 1456 /* We have no more pending requests; stop listening for 'writeable' events. */ 1457 (void) event_del(&port->event); 1458 event_assign(&port->event, port->event_base, 1459 port->socket, EV_READ | EV_PERSIST, 1460 server_port_ready_callback, port); 1461 1462 if (event_add(&port->event, NULL) < 0) { 1463 log(EVDNS_LOG_WARN, "Error from libevent when adding event for DNS server."); 1464 /* ???? Do more? */ 1465 } 1466 } 1467 1468 /* set if we are waiting for the ability to write to this server. */ 1469 /* if waiting is true then we ask libevent for EV_WRITE events, otherwise */ 1470 /* we stop these events. */ 1471 static void 1472 nameserver_write_waiting(struct nameserver *ns, char waiting) { 1473 ASSERT_LOCKED(ns->base); 1474 if (ns->write_waiting == waiting) return; 1475 1476 ns->write_waiting = waiting; 1477 (void) event_del(&ns->event); 1478 event_assign(&ns->event, ns->base->event_base, 1479 ns->socket, EV_READ | (waiting ? EV_WRITE : 0) | EV_PERSIST, 1480 nameserver_ready_callback, ns); 1481 if (event_add(&ns->event, NULL) < 0) { 1482 char addrbuf[128]; 1483 log(EVDNS_LOG_WARN, "Error from libevent when adding event for %s", 1484 evutil_format_sockaddr_port_( 1485 (struct sockaddr *)&ns->address, 1486 addrbuf, sizeof(addrbuf))); 1487 /* ???? Do more? */ 1488 } 1489 } 1490 1491 /* a callback function. Called by libevent when the kernel says that */ 1492 /* a nameserver socket is ready for writing or reading */ 1493 static void 1494 nameserver_ready_callback(evutil_socket_t fd, short events, void *arg) { 1495 struct nameserver *ns = (struct nameserver *) arg; 1496 (void)fd; 1497 1498 EVDNS_LOCK(ns->base); 1499 if (events & EV_WRITE) { 1500 ns->choked = 0; 1501 if (!evdns_transmit(ns->base)) { 1502 nameserver_write_waiting(ns, 0); 1503 } 1504 } 1505 if (events & EV_READ) { 1506 nameserver_read(ns); 1507 } 1508 EVDNS_UNLOCK(ns->base); 1509 } 1510 1511 /* a callback function. Called by libevent when the kernel says that */ 1512 /* a server socket is ready for writing or reading. */ 1513 static void 1514 server_port_ready_callback(evutil_socket_t fd, short events, void *arg) { 1515 struct evdns_server_port *port = (struct evdns_server_port *) arg; 1516 (void) fd; 1517 1518 EVDNS_LOCK(port); 1519 if (events & EV_WRITE) { 1520 port->choked = 0; 1521 server_port_flush(port); 1522 } 1523 if (events & EV_READ) { 1524 server_port_read(port); 1525 } 1526 EVDNS_UNLOCK(port); 1527 } 1528 1529 /* This is an inefficient representation; only use it via the dnslabel_table_* 1530 * functions, so that is can be safely replaced with something smarter later. */ 1531 #define MAX_LABELS 128 1532 /* Structures used to implement name compression */ 1533 struct dnslabel_entry { char *v; off_t pos; }; 1534 struct dnslabel_table { 1535 int n_labels; /* number of current entries */ 1536 /* map from name to position in message */ 1537 struct dnslabel_entry labels[MAX_LABELS]; 1538 }; 1539 1540 /* Initialize dnslabel_table. */ 1541 static void 1542 dnslabel_table_init(struct dnslabel_table *table) 1543 { 1544 table->n_labels = 0; 1545 } 1546 1547 /* Free all storage held by table, but not the table itself. */ 1548 static void 1549 dnslabel_clear(struct dnslabel_table *table) 1550 { 1551 int i; 1552 for (i = 0; i < table->n_labels; ++i) 1553 mm_free(table->labels[i].v); 1554 table->n_labels = 0; 1555 } 1556 1557 /* return the position of the label in the current message, or -1 if the label */ 1558 /* hasn't been used yet. */ 1559 static int 1560 dnslabel_table_get_pos(const struct dnslabel_table *table, const char *label) 1561 { 1562 int i; 1563 for (i = 0; i < table->n_labels; ++i) { 1564 if (!strcmp(label, table->labels[i].v)) 1565 return table->labels[i].pos; 1566 } 1567 return -1; 1568 } 1569 1570 /* remember that we've used the label at position pos */ 1571 static int 1572 dnslabel_table_add(struct dnslabel_table *table, const char *label, off_t pos) 1573 { 1574 char *v; 1575 int p; 1576 if (table->n_labels == MAX_LABELS) 1577 return (-1); 1578 v = mm_strdup(label); 1579 if (v == NULL) 1580 return (-1); 1581 p = table->n_labels++; 1582 table->labels[p].v = v; 1583 table->labels[p].pos = pos; 1584 1585 return (0); 1586 } 1587 1588 /* Converts a string to a length-prefixed set of DNS labels, starting */ 1589 /* at buf[j]. name and buf must not overlap. name_len should be the length */ 1590 /* of name. table is optional, and is used for compression. */ 1591 /* */ 1592 /* Input: abc.def */ 1593 /* Output: <3>abc<3>def<0> */ 1594 /* */ 1595 /* Returns the first index after the encoded name, or negative on error. */ 1596 /* -1 label was > 63 bytes */ 1597 /* -2 name too long to fit in buffer. */ 1598 /* */ 1599 static off_t 1600 dnsname_to_labels(u8 *const buf, size_t buf_len, off_t j, 1601 const char *name, const size_t name_len, 1602 struct dnslabel_table *table) { 1603 const char *end = name + name_len; 1604 int ref = 0; 1605 u16 t_; 1606 1607 #define APPEND16(x) do { \ 1608 if (j + 2 > (off_t)buf_len) \ 1609 goto overflow; \ 1610 t_ = htons(x); \ 1611 memcpy(buf + j, &t_, 2); \ 1612 j += 2; \ 1613 } while (0) 1614 #define APPEND32(x) do { \ 1615 if (j + 4 > (off_t)buf_len) \ 1616 goto overflow; \ 1617 t32_ = htonl(x); \ 1618 memcpy(buf + j, &t32_, 4); \ 1619 j += 4; \ 1620 } while (0) 1621 1622 if (name_len > 255) return -2; 1623 1624 for (;;) { 1625 const char *const start = name; 1626 if (table && (ref = dnslabel_table_get_pos(table, name)) >= 0) { 1627 APPEND16(ref | 0xc000); 1628 return j; 1629 } 1630 name = strchr(name, '.'); 1631 if (!name) { 1632 const size_t label_len = end - start; 1633 if (label_len > 63) return -1; 1634 if ((size_t)(j+label_len+1) > buf_len) return -2; 1635 if (table) dnslabel_table_add(table, start, j); 1636 buf[j++] = (ev_uint8_t)label_len; 1637 1638 memcpy(buf + j, start, label_len); 1639 j += (int) label_len; 1640 break; 1641 } else { 1642 /* append length of the label. */ 1643 const size_t label_len = name - start; 1644 if (label_len > 63) return -1; 1645 if ((size_t)(j+label_len+1) > buf_len) return -2; 1646 if (table) dnslabel_table_add(table, start, j); 1647 buf[j++] = (ev_uint8_t)label_len; 1648 1649 memcpy(buf + j, start, label_len); 1650 j += (int) label_len; 1651 /* hop over the '.' */ 1652 name++; 1653 } 1654 } 1655 1656 /* the labels must be terminated by a 0. */ 1657 /* It's possible that the name ended in a . */ 1658 /* in which case the zero is already there */ 1659 if (!j || buf[j-1]) buf[j++] = 0; 1660 return j; 1661 overflow: 1662 return (-2); 1663 } 1664 1665 /* Finds the length of a dns request for a DNS name of the given */ 1666 /* length. The actual request may be smaller than the value returned */ 1667 /* here */ 1668 static size_t 1669 evdns_request_len(const size_t name_len) { 1670 return 96 + /* length of the DNS standard header */ 1671 name_len + 2 + 1672 4; /* space for the resource type */ 1673 } 1674 1675 /* build a dns request packet into buf. buf should be at least as long */ 1676 /* as evdns_request_len told you it should be. */ 1677 /* */ 1678 /* Returns the amount of space used. Negative on error. */ 1679 static int 1680 evdns_request_data_build(const char *const name, const size_t name_len, 1681 const u16 trans_id, const u16 type, const u16 class, 1682 u8 *const buf, size_t buf_len) { 1683 off_t j = 0; /* current offset into buf */ 1684 u16 t_; /* used by the macros */ 1685 1686 APPEND16(trans_id); 1687 APPEND16(0x0100); /* standard query, recusion needed */ 1688 APPEND16(1); /* one question */ 1689 APPEND16(0); /* no answers */ 1690 APPEND16(0); /* no authority */ 1691 APPEND16(0); /* no additional */ 1692 1693 j = dnsname_to_labels(buf, buf_len, j, name, name_len, NULL); 1694 if (j < 0) { 1695 return (int)j; 1696 } 1697 1698 APPEND16(type); 1699 APPEND16(class); 1700 1701 return (int)j; 1702 overflow: 1703 return (-1); 1704 } 1705 1706 /* exported function */ 1707 struct evdns_server_port * 1708 evdns_add_server_port_with_base(struct event_base *base, evutil_socket_t socket, int flags, evdns_request_callback_fn_type cb, void *user_data) 1709 { 1710 struct evdns_server_port *port; 1711 if (flags) 1712 return NULL; /* flags not yet implemented */ 1713 if (!(port = mm_malloc(sizeof(struct evdns_server_port)))) 1714 return NULL; 1715 memset(port, 0, sizeof(struct evdns_server_port)); 1716 1717 1718 port->socket = socket; 1719 port->refcnt = 1; 1720 port->choked = 0; 1721 port->closing = 0; 1722 port->user_callback = cb; 1723 port->user_data = user_data; 1724 port->pending_replies = NULL; 1725 port->event_base = base; 1726 1727 event_assign(&port->event, port->event_base, 1728 port->socket, EV_READ | EV_PERSIST, 1729 server_port_ready_callback, port); 1730 if (event_add(&port->event, NULL) < 0) { 1731 mm_free(port); 1732 return NULL; 1733 } 1734 EVTHREAD_ALLOC_LOCK(port->lock, EVTHREAD_LOCKTYPE_RECURSIVE); 1735 return port; 1736 } 1737 1738 struct evdns_server_port * 1739 evdns_add_server_port(evutil_socket_t socket, int flags, evdns_request_callback_fn_type cb, void *user_data) 1740 { 1741 return evdns_add_server_port_with_base(NULL, socket, flags, cb, user_data); 1742 } 1743 1744 /* exported function */ 1745 void 1746 evdns_close_server_port(struct evdns_server_port *port) 1747 { 1748 EVDNS_LOCK(port); 1749 if (--port->refcnt == 0) { 1750 EVDNS_UNLOCK(port); 1751 server_port_free(port); 1752 } else { 1753 port->closing = 1; 1754 } 1755 } 1756 1757 /* exported function */ 1758 int 1759 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) 1760 { 1761 struct server_request *req = TO_SERVER_REQUEST(req_); 1762 struct server_reply_item **itemp, *item; 1763 int *countp; 1764 int result = -1; 1765 1766 EVDNS_LOCK(req->port); 1767 if (req->response) /* have we already answered? */ 1768 goto done; 1769 1770 switch (section) { 1771 case EVDNS_ANSWER_SECTION: 1772 itemp = &req->answer; 1773 countp = &req->n_answer; 1774 break; 1775 case EVDNS_AUTHORITY_SECTION: 1776 itemp = &req->authority; 1777 countp = &req->n_authority; 1778 break; 1779 case EVDNS_ADDITIONAL_SECTION: 1780 itemp = &req->additional; 1781 countp = &req->n_additional; 1782 break; 1783 default: 1784 goto done; 1785 } 1786 while (*itemp) { 1787 itemp = &((*itemp)->next); 1788 } 1789 item = mm_malloc(sizeof(struct server_reply_item)); 1790 if (!item) 1791 goto done; 1792 item->next = NULL; 1793 if (!(item->name = mm_strdup(name))) { 1794 mm_free(item); 1795 goto done; 1796 } 1797 item->type = type; 1798 item->dns_question_class = class; 1799 item->ttl = ttl; 1800 item->is_name = is_name != 0; 1801 item->datalen = 0; 1802 item->data = NULL; 1803 if (data) { 1804 if (item->is_name) { 1805 if (!(item->data = mm_strdup(data))) { 1806 mm_free(item->name); 1807 mm_free(item); 1808 goto done; 1809 } 1810 item->datalen = (u16)-1; 1811 } else { 1812 if (!(item->data = mm_malloc(datalen))) { 1813 mm_free(item->name); 1814 mm_free(item); 1815 goto done; 1816 } 1817 item->datalen = datalen; 1818 memcpy(item->data, data, datalen); 1819 } 1820 } 1821 1822 *itemp = item; 1823 ++(*countp); 1824 result = 0; 1825 done: 1826 EVDNS_UNLOCK(req->port); 1827 return result; 1828 } 1829 1830 /* exported function */ 1831 int 1832 evdns_server_request_add_a_reply(struct evdns_server_request *req, const char *name, int n, const void *addrs, int ttl) 1833 { 1834 return evdns_server_request_add_reply( 1835 req, EVDNS_ANSWER_SECTION, name, TYPE_A, CLASS_INET, 1836 ttl, n*4, 0, addrs); 1837 } 1838 1839 /* exported function */ 1840 int 1841 evdns_server_request_add_aaaa_reply(struct evdns_server_request *req, const char *name, int n, const void *addrs, int ttl) 1842 { 1843 return evdns_server_request_add_reply( 1844 req, EVDNS_ANSWER_SECTION, name, TYPE_AAAA, CLASS_INET, 1845 ttl, n*16, 0, addrs); 1846 } 1847 1848 /* exported function */ 1849 int 1850 evdns_server_request_add_ptr_reply(struct evdns_server_request *req, struct in_addr *in, const char *inaddr_name, const char *hostname, int ttl) 1851 { 1852 u32 a; 1853 char buf[32]; 1854 if (in && inaddr_name) 1855 return -1; 1856 else if (!in && !inaddr_name) 1857 return -1; 1858 if (in) { 1859 a = ntohl(in->s_addr); 1860 evutil_snprintf(buf, sizeof(buf), "%d.%d.%d.%d.in-addr.arpa", 1861 (int)(u8)((a )&0xff), 1862 (int)(u8)((a>>8 )&0xff), 1863 (int)(u8)((a>>16)&0xff), 1864 (int)(u8)((a>>24)&0xff)); 1865 inaddr_name = buf; 1866 } 1867 return evdns_server_request_add_reply( 1868 req, EVDNS_ANSWER_SECTION, inaddr_name, TYPE_PTR, CLASS_INET, 1869 ttl, -1, 1, hostname); 1870 } 1871 1872 /* exported function */ 1873 int 1874 evdns_server_request_add_cname_reply(struct evdns_server_request *req, const char *name, const char *cname, int ttl) 1875 { 1876 return evdns_server_request_add_reply( 1877 req, EVDNS_ANSWER_SECTION, name, TYPE_CNAME, CLASS_INET, 1878 ttl, -1, 1, cname); 1879 } 1880 1881 /* exported function */ 1882 void 1883 evdns_server_request_set_flags(struct evdns_server_request *exreq, int flags) 1884 { 1885 struct server_request *req = TO_SERVER_REQUEST(exreq); 1886 req->base.flags &= ~(EVDNS_FLAGS_AA|EVDNS_FLAGS_RD); 1887 req->base.flags |= flags; 1888 } 1889 1890 static int 1891 evdns_server_request_format_response(struct server_request *req, int err) 1892 { 1893 unsigned char buf[1500]; 1894 size_t buf_len = sizeof(buf); 1895 off_t j = 0, r; 1896 u16 t_; 1897 u32 t32_; 1898 int i; 1899 u16 flags; 1900 struct dnslabel_table table; 1901 1902 if (err < 0 || err > 15) return -1; 1903 1904 /* Set response bit and error code; copy OPCODE and RD fields from 1905 * question; copy RA and AA if set by caller. */ 1906 flags = req->base.flags; 1907 flags |= (0x8000 | err); 1908 1909 dnslabel_table_init(&table); 1910 APPEND16(req->trans_id); 1911 APPEND16(flags); 1912 APPEND16(req->base.nquestions); 1913 APPEND16(req->n_answer); 1914 APPEND16(req->n_authority); 1915 APPEND16(req->n_additional); 1916 1917 /* Add questions. */ 1918 for (i=0; i < req->base.nquestions; ++i) { 1919 const char *s = req->base.questions[i]->name; 1920 j = dnsname_to_labels(buf, buf_len, j, s, strlen(s), &table); 1921 if (j < 0) { 1922 dnslabel_clear(&table); 1923 return (int) j; 1924 } 1925 APPEND16(req->base.questions[i]->type); 1926 APPEND16(req->base.questions[i]->dns_question_class); 1927 } 1928 1929 /* Add answer, authority, and additional sections. */ 1930 for (i=0; i<3; ++i) { 1931 struct server_reply_item *item; 1932 if (i==0) 1933 item = req->answer; 1934 else if (i==1) 1935 item = req->authority; 1936 else 1937 item = req->additional; 1938 while (item) { 1939 r = dnsname_to_labels(buf, buf_len, j, item->name, strlen(item->name), &table); 1940 if (r < 0) 1941 goto overflow; 1942 j = r; 1943 1944 APPEND16(item->type); 1945 APPEND16(item->dns_question_class); 1946 APPEND32(item->ttl); 1947 if (item->is_name) { 1948 off_t len_idx = j, name_start; 1949 j += 2; 1950 name_start = j; 1951 r = dnsname_to_labels(buf, buf_len, j, item->data, strlen(item->data), &table); 1952 if (r < 0) 1953 goto overflow; 1954 j = r; 1955 t_ = htons( (short) (j-name_start) ); 1956 memcpy(buf+len_idx, &t_, 2); 1957 } else { 1958 APPEND16(item->datalen); 1959 if (j+item->datalen > (off_t)buf_len) 1960 goto overflow; 1961 memcpy(buf+j, item->data, item->datalen); 1962 j += item->datalen; 1963 } 1964 item = item->next; 1965 } 1966 } 1967 1968 if (j > 512) { 1969 overflow: 1970 j = 512; 1971 buf[2] |= 0x02; /* set the truncated bit. */ 1972 } 1973 1974 req->response_len = j; 1975 1976 if (!(req->response = mm_malloc(req->response_len))) { 1977 server_request_free_answers(req); 1978 dnslabel_clear(&table); 1979 return (-1); 1980 } 1981 memcpy(req->response, buf, req->response_len); 1982 server_request_free_answers(req); 1983 dnslabel_clear(&table); 1984 return (0); 1985 } 1986 1987 /* exported function */ 1988 int 1989 evdns_server_request_respond(struct evdns_server_request *req_, int err) 1990 { 1991 struct server_request *req = TO_SERVER_REQUEST(req_); 1992 struct evdns_server_port *port = req->port; 1993 int r = -1; 1994 1995 EVDNS_LOCK(port); 1996 if (!req->response) { 1997 if ((r = evdns_server_request_format_response(req, err))<0) 1998 goto done; 1999 } 2000 2001 r = sendto(port->socket, req->response, (int)req->response_len, 0, 2002 (struct sockaddr*) &req->addr, (ev_socklen_t)req->addrlen); 2003 if (r<0) { 2004 int sock_err = evutil_socket_geterror(port->socket); 2005 if (EVUTIL_ERR_RW_RETRIABLE(sock_err)) 2006 goto done; 2007 2008 if (port->pending_replies) { 2009 req->prev_pending = port->pending_replies->prev_pending; 2010 req->next_pending = port->pending_replies; 2011 req->prev_pending->next_pending = 2012 req->next_pending->prev_pending = req; 2013 } else { 2014 req->prev_pending = req->next_pending = req; 2015 port->pending_replies = req; 2016 port->choked = 1; 2017 2018 (void) event_del(&port->event); 2019 event_assign(&port->event, port->event_base, port->socket, (port->closing?0:EV_READ) | EV_WRITE | EV_PERSIST, server_port_ready_callback, port); 2020 2021 if (event_add(&port->event, NULL) < 0) { 2022 log(EVDNS_LOG_WARN, "Error from libevent when adding event for DNS server"); 2023 } 2024 2025 } 2026 2027 r = 1; 2028 goto done; 2029 } 2030 if (server_request_free(req)) { 2031 r = 0; 2032 goto done; 2033 } 2034 2035 if (port->pending_replies) 2036 server_port_flush(port); 2037 2038 r = 0; 2039 done: 2040 EVDNS_UNLOCK(port); 2041 return r; 2042 } 2043 2044 /* Free all storage held by RRs in req. */ 2045 static void 2046 server_request_free_answers(struct server_request *req) 2047 { 2048 struct server_reply_item *victim, *next, **list; 2049 int i; 2050 for (i = 0; i < 3; ++i) { 2051 if (i==0) 2052 list = &req->answer; 2053 else if (i==1) 2054 list = &req->authority; 2055 else 2056 list = &req->additional; 2057 2058 victim = *list; 2059 while (victim) { 2060 next = victim->next; 2061 mm_free(victim->name); 2062 if (victim->data) 2063 mm_free(victim->data); 2064 mm_free(victim); 2065 victim = next; 2066 } 2067 *list = NULL; 2068 } 2069 } 2070 2071 /* Free all storage held by req, and remove links to it. */ 2072 /* return true iff we just wound up freeing the server_port. */ 2073 static int 2074 server_request_free(struct server_request *req) 2075 { 2076 int i, rc=1, lock=0; 2077 if (req->base.questions) { 2078 for (i = 0; i < req->base.nquestions; ++i) 2079 mm_free(req->base.questions[i]); 2080 mm_free(req->base.questions); 2081 } 2082 2083 if (req->port) { 2084 EVDNS_LOCK(req->port); 2085 lock=1; 2086 if (req->port->pending_replies == req) { 2087 if (req->next_pending && req->next_pending != req) 2088 req->port->pending_replies = req->next_pending; 2089 else 2090 req->port->pending_replies = NULL; 2091 } 2092 rc = --req->port->refcnt; 2093 } 2094 2095 if (req->response) { 2096 mm_free(req->response); 2097 } 2098 2099 server_request_free_answers(req); 2100 2101 if (req->next_pending && req->next_pending != req) { 2102 req->next_pending->prev_pending = req->prev_pending; 2103 req->prev_pending->next_pending = req->next_pending; 2104 } 2105 2106 if (rc == 0) { 2107 EVDNS_UNLOCK(req->port); /* ????? nickm */ 2108 server_port_free(req->port); 2109 mm_free(req); 2110 return (1); 2111 } 2112 if (lock) 2113 EVDNS_UNLOCK(req->port); 2114 mm_free(req); 2115 return (0); 2116 } 2117 2118 /* Free all storage held by an evdns_server_port. Only called when */ 2119 static void 2120 server_port_free(struct evdns_server_port *port) 2121 { 2122 EVUTIL_ASSERT(port); 2123 EVUTIL_ASSERT(!port->refcnt); 2124 EVUTIL_ASSERT(!port->pending_replies); 2125 if (port->socket > 0) { 2126 evutil_closesocket(port->socket); 2127 port->socket = -1; 2128 } 2129 (void) event_del(&port->event); 2130 event_debug_unassign(&port->event); 2131 EVTHREAD_FREE_LOCK(port->lock, EVTHREAD_LOCKTYPE_RECURSIVE); 2132 mm_free(port); 2133 } 2134 2135 /* exported function */ 2136 int 2137 evdns_server_request_drop(struct evdns_server_request *req_) 2138 { 2139 struct server_request *req = TO_SERVER_REQUEST(req_); 2140 server_request_free(req); 2141 return 0; 2142 } 2143 2144 /* exported function */ 2145 int 2146 evdns_server_request_get_requesting_addr(struct evdns_server_request *req_, struct sockaddr *sa, int addr_len) 2147 { 2148 struct server_request *req = TO_SERVER_REQUEST(req_); 2149 if (addr_len < (int)req->addrlen) 2150 return -1; 2151 memcpy(sa, &(req->addr), req->addrlen); 2152 return req->addrlen; 2153 } 2154 2155 #undef APPEND16 2156 #undef APPEND32 2157 2158 /* this is a libevent callback function which is called when a request */ 2159 /* has timed out. */ 2160 static void 2161 evdns_request_timeout_callback(evutil_socket_t fd, short events, void *arg) { 2162 struct request *const req = (struct request *) arg; 2163 struct evdns_base *base = req->base; 2164 2165 (void) fd; 2166 (void) events; 2167 2168 log(EVDNS_LOG_DEBUG, "Request %p timed out", arg); 2169 EVDNS_LOCK(base); 2170 2171 if (req->tx_count >= req->base->global_max_retransmits) { 2172 struct nameserver *ns = req->ns; 2173 /* this request has failed */ 2174 log(EVDNS_LOG_DEBUG, "Giving up on request %p; tx_count==%d", 2175 arg, req->tx_count); 2176 reply_schedule_callback(req, 0, DNS_ERR_TIMEOUT, NULL); 2177 2178 request_finished(req, &REQ_HEAD(req->base, req->trans_id), 1); 2179 nameserver_failed(ns, "request timed out."); 2180 } else { 2181 /* retransmit it */ 2182 log(EVDNS_LOG_DEBUG, "Retransmitting request %p; tx_count==%d", 2183 arg, req->tx_count); 2184 (void) evtimer_del(&req->timeout_event); 2185 request_swap_ns(req, nameserver_pick(base)); 2186 evdns_request_transmit(req); 2187 2188 req->ns->timedout++; 2189 if (req->ns->timedout > req->base->global_max_nameserver_timeout) { 2190 req->ns->timedout = 0; 2191 nameserver_failed(req->ns, "request timed out."); 2192 } 2193 } 2194 2195 EVDNS_UNLOCK(base); 2196 } 2197 2198 /* try to send a request to a given server. */ 2199 /* */ 2200 /* return: */ 2201 /* 0 ok */ 2202 /* 1 temporary failure */ 2203 /* 2 other failure */ 2204 static int 2205 evdns_request_transmit_to(struct request *req, struct nameserver *server) { 2206 int r; 2207 ASSERT_LOCKED(req->base); 2208 ASSERT_VALID_REQUEST(req); 2209 2210 if (server->requests_inflight == 1 && 2211 req->base->disable_when_inactive && 2212 event_add(&server->event, NULL) < 0) { 2213 return 1; 2214 } 2215 2216 r = sendto(server->socket, (void*)req->request, req->request_len, 0, 2217 (struct sockaddr *)&server->address, server->addrlen); 2218 if (r < 0) { 2219 int err = evutil_socket_geterror(server->socket); 2220 if (EVUTIL_ERR_RW_RETRIABLE(err)) 2221 return 1; 2222 nameserver_failed(req->ns, evutil_socket_error_to_string(err)); 2223 return 2; 2224 } else if (r != (int)req->request_len) { 2225 return 1; /* short write */ 2226 } else { 2227 return 0; 2228 } 2229 } 2230 2231 /* try to send a request, updating the fields of the request */ 2232 /* as needed */ 2233 /* */ 2234 /* return: */ 2235 /* 0 ok */ 2236 /* 1 failed */ 2237 static int 2238 evdns_request_transmit(struct request *req) { 2239 int retcode = 0, r; 2240 2241 ASSERT_LOCKED(req->base); 2242 ASSERT_VALID_REQUEST(req); 2243 /* if we fail to send this packet then this flag marks it */ 2244 /* for evdns_transmit */ 2245 req->transmit_me = 1; 2246 EVUTIL_ASSERT(req->trans_id != 0xffff); 2247 2248 if (!req->ns) 2249 { 2250 /* unable to transmit request if no nameservers */ 2251 return 1; 2252 } 2253 2254 if (req->ns->choked) { 2255 /* don't bother trying to write to a socket */ 2256 /* which we have had EAGAIN from */ 2257 return 1; 2258 } 2259 2260 r = evdns_request_transmit_to(req, req->ns); 2261 switch (r) { 2262 case 1: 2263 /* temp failure */ 2264 req->ns->choked = 1; 2265 nameserver_write_waiting(req->ns, 1); 2266 return 1; 2267 case 2: 2268 /* failed to transmit the request entirely. */ 2269 retcode = 1; 2270 /* fall through: we'll set a timeout, which will time out, 2271 * and make us retransmit the request anyway. */ 2272 default: 2273 /* all ok */ 2274 log(EVDNS_LOG_DEBUG, 2275 "Setting timeout for request %p, sent to nameserver %p", req, req->ns); 2276 if (evtimer_add(&req->timeout_event, &req->base->global_timeout) < 0) { 2277 log(EVDNS_LOG_WARN, 2278 "Error from libevent when adding timer for request %p", 2279 req); 2280 /* ???? Do more? */ 2281 } 2282 req->tx_count++; 2283 req->transmit_me = 0; 2284 return retcode; 2285 } 2286 } 2287 2288 static void 2289 nameserver_probe_callback(int result, char type, int count, int ttl, void *addresses, void *arg) { 2290 struct nameserver *const ns = (struct nameserver *) arg; 2291 (void) type; 2292 (void) count; 2293 (void) ttl; 2294 (void) addresses; 2295 2296 if (result == DNS_ERR_CANCEL) { 2297 /* We canceled this request because the nameserver came up 2298 * for some other reason. Do not change our opinion about 2299 * the nameserver. */ 2300 return; 2301 } 2302 2303 EVDNS_LOCK(ns->base); 2304 ns->probe_request = NULL; 2305 if (result == DNS_ERR_NONE || result == DNS_ERR_NOTEXIST) { 2306 /* this is a good reply */ 2307 nameserver_up(ns); 2308 } else { 2309 nameserver_probe_failed(ns); 2310 } 2311 EVDNS_UNLOCK(ns->base); 2312 } 2313 2314 static void 2315 nameserver_send_probe(struct nameserver *const ns) { 2316 struct evdns_request *handle; 2317 struct request *req; 2318 char addrbuf[128]; 2319 /* here we need to send a probe to a given nameserver */ 2320 /* in the hope that it is up now. */ 2321 2322 ASSERT_LOCKED(ns->base); 2323 log(EVDNS_LOG_DEBUG, "Sending probe to %s", 2324 evutil_format_sockaddr_port_( 2325 (struct sockaddr *)&ns->address, 2326 addrbuf, sizeof(addrbuf))); 2327 handle = mm_calloc(1, sizeof(*handle)); 2328 if (!handle) return; 2329 req = request_new(ns->base, handle, TYPE_A, "google.com", DNS_QUERY_NO_SEARCH, nameserver_probe_callback, ns); 2330 if (!req) { 2331 mm_free(handle); 2332 return; 2333 } 2334 ns->probe_request = handle; 2335 /* we force this into the inflight queue no matter what */ 2336 request_trans_id_set(req, transaction_id_pick(ns->base)); 2337 req->ns = ns; 2338 request_submit(req); 2339 } 2340 2341 /* returns: */ 2342 /* 0 didn't try to transmit anything */ 2343 /* 1 tried to transmit something */ 2344 static int 2345 evdns_transmit(struct evdns_base *base) { 2346 char did_try_to_transmit = 0; 2347 int i; 2348 2349 ASSERT_LOCKED(base); 2350 for (i = 0; i < base->n_req_heads; ++i) { 2351 if (base->req_heads[i]) { 2352 struct request *const started_at = base->req_heads[i], *req = started_at; 2353 /* first transmit all the requests which are currently waiting */ 2354 do { 2355 if (req->transmit_me) { 2356 did_try_to_transmit = 1; 2357 evdns_request_transmit(req); 2358 } 2359 2360 req = req->next; 2361 } while (req != started_at); 2362 } 2363 } 2364 2365 return did_try_to_transmit; 2366 } 2367 2368 /* exported function */ 2369 int 2370 evdns_base_count_nameservers(struct evdns_base *base) 2371 { 2372 const struct nameserver *server; 2373 int n = 0; 2374 2375 EVDNS_LOCK(base); 2376 server = base->server_head; 2377 if (!server) 2378 goto done; 2379 do { 2380 ++n; 2381 server = server->next; 2382 } while (server != base->server_head); 2383 done: 2384 EVDNS_UNLOCK(base); 2385 return n; 2386 } 2387 2388 int 2389 evdns_count_nameservers(void) 2390 { 2391 return evdns_base_count_nameservers(current_base); 2392 } 2393 2394 /* exported function */ 2395 int 2396 evdns_base_clear_nameservers_and_suspend(struct evdns_base *base) 2397 { 2398 struct nameserver *server, *started_at; 2399 int i; 2400 2401 EVDNS_LOCK(base); 2402 server = base->server_head; 2403 started_at = base->server_head; 2404 if (!server) { 2405 EVDNS_UNLOCK(base); 2406 return 0; 2407 } 2408 while (1) { 2409 struct nameserver *next = server->next; 2410 (void) event_del(&server->event); 2411 if (evtimer_initialized(&server->timeout_event)) 2412 (void) evtimer_del(&server->timeout_event); 2413 if (server->probe_request) { 2414 evdns_cancel_request(server->base, server->probe_request); 2415 server->probe_request = NULL; 2416 } 2417 if (server->socket >= 0) 2418 evutil_closesocket(server->socket); 2419 mm_free(server); 2420 if (next == started_at) 2421 break; 2422 server = next; 2423 } 2424 base->server_head = NULL; 2425 base->global_good_nameservers = 0; 2426 2427 for (i = 0; i < base->n_req_heads; ++i) { 2428 struct request *req, *req_started_at; 2429 req = req_started_at = base->req_heads[i]; 2430 while (req) { 2431 struct request *next = req->next; 2432 req->tx_count = req->reissue_count = 0; 2433 req->ns = NULL; 2434 /* ???? What to do about searches? */ 2435 (void) evtimer_del(&req->timeout_event); 2436 req->trans_id = 0; 2437 req->transmit_me = 0; 2438 2439 base->global_requests_waiting++; 2440 evdns_request_insert(req, &base->req_waiting_head); 2441 /* We want to insert these suspended elements at the front of 2442 * the waiting queue, since they were pending before any of 2443 * the waiting entries were added. This is a circular list, 2444 * so we can just shift the start back by one.*/ 2445 base->req_waiting_head = base->req_waiting_head->prev; 2446 2447 if (next == req_started_at) 2448 break; 2449 req = next; 2450 } 2451 base->req_heads[i] = NULL; 2452 } 2453 2454 base->global_requests_inflight = 0; 2455 2456 EVDNS_UNLOCK(base); 2457 return 0; 2458 } 2459 2460 int 2461 evdns_clear_nameservers_and_suspend(void) 2462 { 2463 return evdns_base_clear_nameservers_and_suspend(current_base); 2464 } 2465 2466 2467 /* exported function */ 2468 int 2469 evdns_base_resume(struct evdns_base *base) 2470 { 2471 EVDNS_LOCK(base); 2472 evdns_requests_pump_waiting_queue(base); 2473 EVDNS_UNLOCK(base); 2474 2475 return 0; 2476 } 2477 2478 int 2479 evdns_resume(void) 2480 { 2481 return evdns_base_resume(current_base); 2482 } 2483 2484 static int 2485 evdns_nameserver_add_impl_(struct evdns_base *base, const struct sockaddr *address, int addrlen) { 2486 /* first check to see if we already have this nameserver */ 2487 2488 const struct nameserver *server = base->server_head, *const started_at = base->server_head; 2489 struct nameserver *ns; 2490 int err = 0; 2491 char addrbuf[128]; 2492 2493 ASSERT_LOCKED(base); 2494 if (server) { 2495 do { 2496 if (!evutil_sockaddr_cmp((struct sockaddr*)&server->address, address, 1)) return 3; 2497 server = server->next; 2498 } while (server != started_at); 2499 } 2500 if (addrlen > (int)sizeof(ns->address)) { 2501 log(EVDNS_LOG_DEBUG, "Addrlen %d too long.", (int)addrlen); 2502 return 2; 2503 } 2504 2505 ns = (struct nameserver *) mm_malloc(sizeof(struct nameserver)); 2506 if (!ns) return -1; 2507 2508 memset(ns, 0, sizeof(struct nameserver)); 2509 ns->base = base; 2510 2511 evtimer_assign(&ns->timeout_event, ns->base->event_base, nameserver_prod_callback, ns); 2512 2513 ns->socket = evutil_socket_(address->sa_family, 2514 SOCK_DGRAM|EVUTIL_SOCK_NONBLOCK|EVUTIL_SOCK_CLOEXEC, 0); 2515 if (ns->socket < 0) { err = 1; goto out1; } 2516 2517 if (base->global_outgoing_addrlen && 2518 !evutil_sockaddr_is_loopback_(address)) { 2519 if (bind(ns->socket, 2520 (struct sockaddr*)&base->global_outgoing_address, 2521 base->global_outgoing_addrlen) < 0) { 2522 log(EVDNS_LOG_WARN,"Couldn't bind to outgoing address"); 2523 err = 2; 2524 goto out2; 2525 } 2526 } 2527 2528 memcpy(&ns->address, address, addrlen); 2529 ns->addrlen = addrlen; 2530 ns->state = 1; 2531 event_assign(&ns->event, ns->base->event_base, ns->socket, 2532 EV_READ | EV_PERSIST, nameserver_ready_callback, ns); 2533 if (!base->disable_when_inactive && event_add(&ns->event, NULL) < 0) { 2534 err = 2; 2535 goto out2; 2536 } 2537 2538 log(EVDNS_LOG_DEBUG, "Added nameserver %s as %p", 2539 evutil_format_sockaddr_port_(address, addrbuf, sizeof(addrbuf)), ns); 2540 2541 /* insert this nameserver into the list of them */ 2542 if (!base->server_head) { 2543 ns->next = ns->prev = ns; 2544 base->server_head = ns; 2545 } else { 2546 ns->next = base->server_head->next; 2547 ns->prev = base->server_head; 2548 base->server_head->next = ns; 2549 ns->next->prev = ns; 2550 } 2551 2552 base->global_good_nameservers++; 2553 2554 return 0; 2555 2556 out2: 2557 evutil_closesocket(ns->socket); 2558 out1: 2559 event_debug_unassign(&ns->event); 2560 mm_free(ns); 2561 log(EVDNS_LOG_WARN, "Unable to add nameserver %s: error %d", 2562 evutil_format_sockaddr_port_(address, addrbuf, sizeof(addrbuf)), err); 2563 return err; 2564 } 2565 2566 /* exported function */ 2567 int 2568 evdns_base_nameserver_add(struct evdns_base *base, unsigned long int address) 2569 { 2570 struct sockaddr_in sin; 2571 int res; 2572 memset(&sin, 0, sizeof(sin)); 2573 sin.sin_addr.s_addr = address; 2574 sin.sin_port = htons(53); 2575 sin.sin_family = AF_INET; 2576 EVDNS_LOCK(base); 2577 res = evdns_nameserver_add_impl_(base, (struct sockaddr*)&sin, sizeof(sin)); 2578 EVDNS_UNLOCK(base); 2579 return res; 2580 } 2581 2582 int 2583 evdns_nameserver_add(unsigned long int address) { 2584 if (!current_base) 2585 current_base = evdns_base_new(NULL, 0); 2586 return evdns_base_nameserver_add(current_base, address); 2587 } 2588 2589 static void 2590 sockaddr_setport(struct sockaddr *sa, ev_uint16_t port) 2591 { 2592 if (sa->sa_family == AF_INET) { 2593 ((struct sockaddr_in *)sa)->sin_port = htons(port); 2594 } else if (sa->sa_family == AF_INET6) { 2595 ((struct sockaddr_in6 *)sa)->sin6_port = htons(port); 2596 } 2597 } 2598 2599 static ev_uint16_t 2600 sockaddr_getport(struct sockaddr *sa) 2601 { 2602 if (sa->sa_family == AF_INET) { 2603 return ntohs(((struct sockaddr_in *)sa)->sin_port); 2604 } else if (sa->sa_family == AF_INET6) { 2605 return ntohs(((struct sockaddr_in6 *)sa)->sin6_port); 2606 } else { 2607 return 0; 2608 } 2609 } 2610 2611 /* exported function */ 2612 int 2613 evdns_base_nameserver_ip_add(struct evdns_base *base, const char *ip_as_string) { 2614 struct sockaddr_storage ss; 2615 struct sockaddr *sa; 2616 int len = sizeof(ss); 2617 int res; 2618 if (evutil_parse_sockaddr_port(ip_as_string, (struct sockaddr *)&ss, 2619 &len)) { 2620 log(EVDNS_LOG_WARN, "Unable to parse nameserver address %s", 2621 ip_as_string); 2622 return 4; 2623 } 2624 sa = (struct sockaddr *) &ss; 2625 if (sockaddr_getport(sa) == 0) 2626 sockaddr_setport(sa, 53); 2627 2628 EVDNS_LOCK(base); 2629 res = evdns_nameserver_add_impl_(base, sa, len); 2630 EVDNS_UNLOCK(base); 2631 return res; 2632 } 2633 2634 int 2635 evdns_nameserver_ip_add(const char *ip_as_string) { 2636 if (!current_base) 2637 current_base = evdns_base_new(NULL, 0); 2638 return evdns_base_nameserver_ip_add(current_base, ip_as_string); 2639 } 2640 2641 int 2642 evdns_base_nameserver_sockaddr_add(struct evdns_base *base, 2643 const struct sockaddr *sa, ev_socklen_t len, unsigned flags) 2644 { 2645 int res; 2646 EVUTIL_ASSERT(base); 2647 EVDNS_LOCK(base); 2648 res = evdns_nameserver_add_impl_(base, sa, len); 2649 EVDNS_UNLOCK(base); 2650 return res; 2651 } 2652 2653 int 2654 evdns_base_get_nameserver_addr(struct evdns_base *base, int idx, 2655 struct sockaddr *sa, ev_socklen_t len) 2656 { 2657 int result = -1; 2658 int i; 2659 struct nameserver *server; 2660 EVDNS_LOCK(base); 2661 server = base->server_head; 2662 for (i = 0; i < idx && server; ++i, server = server->next) { 2663 if (server->next == base->server_head) 2664 goto done; 2665 } 2666 if (! server) 2667 goto done; 2668 2669 if (server->addrlen > len) { 2670 result = (int) server->addrlen; 2671 goto done; 2672 } 2673 2674 memcpy(sa, &server->address, server->addrlen); 2675 result = (int) server->addrlen; 2676 done: 2677 EVDNS_UNLOCK(base); 2678 return result; 2679 } 2680 2681 /* remove from the queue */ 2682 static void 2683 evdns_request_remove(struct request *req, struct request **head) 2684 { 2685 ASSERT_LOCKED(req->base); 2686 ASSERT_VALID_REQUEST(req); 2687 2688 #if 0 2689 { 2690 struct request *ptr; 2691 int found = 0; 2692 EVUTIL_ASSERT(*head != NULL); 2693 2694 ptr = *head; 2695 do { 2696 if (ptr == req) { 2697 found = 1; 2698 break; 2699 } 2700 ptr = ptr->next; 2701 } while (ptr != *head); 2702 EVUTIL_ASSERT(found); 2703 2704 EVUTIL_ASSERT(req->next); 2705 } 2706 #endif 2707 2708 if (req->next == req) { 2709 /* only item in the list */ 2710 *head = NULL; 2711 } else { 2712 req->next->prev = req->prev; 2713 req->prev->next = req->next; 2714 if (*head == req) *head = req->next; 2715 } 2716 req->next = req->prev = NULL; 2717 } 2718 2719 /* insert into the tail of the queue */ 2720 static void 2721 evdns_request_insert(struct request *req, struct request **head) { 2722 ASSERT_LOCKED(req->base); 2723 ASSERT_VALID_REQUEST(req); 2724 if (!*head) { 2725 *head = req; 2726 req->next = req->prev = req; 2727 return; 2728 } 2729 2730 req->prev = (*head)->prev; 2731 req->prev->next = req; 2732 req->next = *head; 2733 (*head)->prev = req; 2734 } 2735 2736 static int 2737 string_num_dots(const char *s) { 2738 int count = 0; 2739 while ((s = strchr(s, '.'))) { 2740 s++; 2741 count++; 2742 } 2743 return count; 2744 } 2745 2746 static struct request * 2747 request_new(struct evdns_base *base, struct evdns_request *handle, int type, 2748 const char *name, int flags, evdns_callback_type callback, 2749 void *user_ptr) { 2750 2751 const char issuing_now = 2752 (base->global_requests_inflight < base->global_max_requests_inflight) ? 1 : 0; 2753 2754 const size_t name_len = strlen(name); 2755 const size_t request_max_len = evdns_request_len(name_len); 2756 const u16 trans_id = issuing_now ? transaction_id_pick(base) : 0xffff; 2757 /* the request data is alloced in a single block with the header */ 2758 struct request *const req = 2759 mm_malloc(sizeof(struct request) + request_max_len); 2760 int rlen; 2761 char namebuf[256]; 2762 (void) flags; 2763 2764 ASSERT_LOCKED(base); 2765 2766 if (!req) return NULL; 2767 2768 if (name_len >= sizeof(namebuf)) { 2769 mm_free(req); 2770 return NULL; 2771 } 2772 2773 memset(req, 0, sizeof(struct request)); 2774 req->base = base; 2775 2776 evtimer_assign(&req->timeout_event, req->base->event_base, evdns_request_timeout_callback, req); 2777 2778 if (base->global_randomize_case) { 2779 unsigned i; 2780 char randbits[(sizeof(namebuf)+7)/8]; 2781 strlcpy(namebuf, name, sizeof(namebuf)); 2782 evutil_secure_rng_get_bytes(randbits, (name_len+7)/8); 2783 for (i = 0; i < name_len; ++i) { 2784 if (EVUTIL_ISALPHA_(namebuf[i])) { 2785 if ((randbits[i >> 3] & (1<<(i & 7)))) 2786 namebuf[i] |= 0x20; 2787 else 2788 namebuf[i] &= ~0x20; 2789 } 2790 } 2791 name = namebuf; 2792 } 2793 2794 /* request data lives just after the header */ 2795 req->request = ((u8 *) req) + sizeof(struct request); 2796 /* denotes that the request data shouldn't be free()ed */ 2797 req->request_appended = 1; 2798 rlen = evdns_request_data_build(name, name_len, trans_id, 2799 type, CLASS_INET, req->request, request_max_len); 2800 if (rlen < 0) 2801 goto err1; 2802 2803 req->request_len = rlen; 2804 req->trans_id = trans_id; 2805 req->tx_count = 0; 2806 req->request_type = type; 2807 req->user_pointer = user_ptr; 2808 req->user_callback = callback; 2809 req->ns = issuing_now ? nameserver_pick(base) : NULL; 2810 req->next = req->prev = NULL; 2811 req->handle = handle; 2812 if (handle) { 2813 handle->current_req = req; 2814 handle->base = base; 2815 } 2816 2817 return req; 2818 err1: 2819 mm_free(req); 2820 return NULL; 2821 } 2822 2823 static void 2824 request_submit(struct request *const req) { 2825 struct evdns_base *base = req->base; 2826 ASSERT_LOCKED(base); 2827 ASSERT_VALID_REQUEST(req); 2828 if (req->ns) { 2829 /* if it has a nameserver assigned then this is going */ 2830 /* straight into the inflight queue */ 2831 evdns_request_insert(req, &REQ_HEAD(base, req->trans_id)); 2832 2833 base->global_requests_inflight++; 2834 req->ns->requests_inflight++; 2835 2836 evdns_request_transmit(req); 2837 } else { 2838 evdns_request_insert(req, &base->req_waiting_head); 2839 base->global_requests_waiting++; 2840 } 2841 } 2842 2843 /* exported function */ 2844 void 2845 evdns_cancel_request(struct evdns_base *base, struct evdns_request *handle) 2846 { 2847 struct request *req; 2848 2849 if (!handle->current_req) 2850 return; 2851 2852 if (!base) { 2853 /* This redundancy is silly; can we fix it? (Not for 2.0) XXXX */ 2854 base = handle->base; 2855 if (!base) 2856 base = handle->current_req->base; 2857 } 2858 2859 EVDNS_LOCK(base); 2860 if (handle->pending_cb) { 2861 EVDNS_UNLOCK(base); 2862 return; 2863 } 2864 2865 req = handle->current_req; 2866 ASSERT_VALID_REQUEST(req); 2867 2868 reply_schedule_callback(req, 0, DNS_ERR_CANCEL, NULL); 2869 if (req->ns) { 2870 /* remove from inflight queue */ 2871 request_finished(req, &REQ_HEAD(base, req->trans_id), 1); 2872 } else { 2873 /* remove from global_waiting head */ 2874 request_finished(req, &base->req_waiting_head, 1); 2875 } 2876 EVDNS_UNLOCK(base); 2877 } 2878 2879 /* exported function */ 2880 struct evdns_request * 2881 evdns_base_resolve_ipv4(struct evdns_base *base, const char *name, int flags, 2882 evdns_callback_type callback, void *ptr) { 2883 struct evdns_request *handle; 2884 struct request *req; 2885 log(EVDNS_LOG_DEBUG, "Resolve requested for %s", name); 2886 handle = mm_calloc(1, sizeof(*handle)); 2887 if (handle == NULL) 2888 return NULL; 2889 EVDNS_LOCK(base); 2890 if (flags & DNS_QUERY_NO_SEARCH) { 2891 req = 2892 request_new(base, handle, TYPE_A, name, flags, 2893 callback, ptr); 2894 if (req) 2895 request_submit(req); 2896 } else { 2897 search_request_new(base, handle, TYPE_A, name, flags, 2898 callback, ptr); 2899 } 2900 if (handle->current_req == NULL) { 2901 mm_free(handle); 2902 handle = NULL; 2903 } 2904 EVDNS_UNLOCK(base); 2905 return handle; 2906 } 2907 2908 int evdns_resolve_ipv4(const char *name, int flags, 2909 evdns_callback_type callback, void *ptr) 2910 { 2911 return evdns_base_resolve_ipv4(current_base, name, flags, callback, ptr) 2912 ? 0 : -1; 2913 } 2914 2915 2916 /* exported function */ 2917 struct evdns_request * 2918 evdns_base_resolve_ipv6(struct evdns_base *base, 2919 const char *name, int flags, 2920 evdns_callback_type callback, void *ptr) 2921 { 2922 struct evdns_request *handle; 2923 struct request *req; 2924 log(EVDNS_LOG_DEBUG, "Resolve requested for %s", name); 2925 handle = mm_calloc(1, sizeof(*handle)); 2926 if (handle == NULL) 2927 return NULL; 2928 EVDNS_LOCK(base); 2929 if (flags & DNS_QUERY_NO_SEARCH) { 2930 req = request_new(base, handle, TYPE_AAAA, name, flags, 2931 callback, ptr); 2932 if (req) 2933 request_submit(req); 2934 } else { 2935 search_request_new(base, handle, TYPE_AAAA, name, flags, 2936 callback, ptr); 2937 } 2938 if (handle->current_req == NULL) { 2939 mm_free(handle); 2940 handle = NULL; 2941 } 2942 EVDNS_UNLOCK(base); 2943 return handle; 2944 } 2945 2946 int evdns_resolve_ipv6(const char *name, int flags, 2947 evdns_callback_type callback, void *ptr) { 2948 return evdns_base_resolve_ipv6(current_base, name, flags, callback, ptr) 2949 ? 0 : -1; 2950 } 2951 2952 struct evdns_request * 2953 evdns_base_resolve_reverse(struct evdns_base *base, const struct in_addr *in, int flags, evdns_callback_type callback, void *ptr) { 2954 char buf[32]; 2955 struct evdns_request *handle; 2956 struct request *req; 2957 u32 a; 2958 EVUTIL_ASSERT(in); 2959 a = ntohl(in->s_addr); 2960 evutil_snprintf(buf, sizeof(buf), "%d.%d.%d.%d.in-addr.arpa", 2961 (int)(u8)((a )&0xff), 2962 (int)(u8)((a>>8 )&0xff), 2963 (int)(u8)((a>>16)&0xff), 2964 (int)(u8)((a>>24)&0xff)); 2965 handle = mm_calloc(1, sizeof(*handle)); 2966 if (handle == NULL) 2967 return NULL; 2968 log(EVDNS_LOG_DEBUG, "Resolve requested for %s (reverse)", buf); 2969 EVDNS_LOCK(base); 2970 req = request_new(base, handle, TYPE_PTR, buf, flags, callback, ptr); 2971 if (req) 2972 request_submit(req); 2973 if (handle->current_req == NULL) { 2974 mm_free(handle); 2975 handle = NULL; 2976 } 2977 EVDNS_UNLOCK(base); 2978 return (handle); 2979 } 2980 2981 int evdns_resolve_reverse(const struct in_addr *in, int flags, evdns_callback_type callback, void *ptr) { 2982 return evdns_base_resolve_reverse(current_base, in, flags, callback, ptr) 2983 ? 0 : -1; 2984 } 2985 2986 struct evdns_request * 2987 evdns_base_resolve_reverse_ipv6(struct evdns_base *base, const struct in6_addr *in, int flags, evdns_callback_type callback, void *ptr) { 2988 /* 32 nybbles, 32 periods, "ip6.arpa", NUL. */ 2989 char buf[73]; 2990 char *cp; 2991 struct evdns_request *handle; 2992 struct request *req; 2993 int i; 2994 EVUTIL_ASSERT(in); 2995 cp = buf; 2996 for (i=15; i >= 0; --i) { 2997 u8 byte = in->s6_addr[i]; 2998 *cp++ = "0123456789abcdef"[byte & 0x0f]; 2999 *cp++ = '.'; 3000 *cp++ = "0123456789abcdef"[byte >> 4]; 3001 *cp++ = '.'; 3002 } 3003 EVUTIL_ASSERT(cp + strlen("ip6.arpa") < buf+sizeof(buf)); 3004 memcpy(cp, "ip6.arpa", strlen("ip6.arpa")+1); 3005 handle = mm_calloc(1, sizeof(*handle)); 3006 if (handle == NULL) 3007 return NULL; 3008 log(EVDNS_LOG_DEBUG, "Resolve requested for %s (reverse)", buf); 3009 EVDNS_LOCK(base); 3010 req = request_new(base, handle, TYPE_PTR, buf, flags, callback, ptr); 3011 if (req) 3012 request_submit(req); 3013 if (handle->current_req == NULL) { 3014 mm_free(handle); 3015 handle = NULL; 3016 } 3017 EVDNS_UNLOCK(base); 3018 return (handle); 3019 } 3020 3021 int evdns_resolve_reverse_ipv6(const struct in6_addr *in, int flags, evdns_callback_type callback, void *ptr) { 3022 return evdns_base_resolve_reverse_ipv6(current_base, in, flags, callback, ptr) 3023 ? 0 : -1; 3024 } 3025 3026 /* ================================================================= */ 3027 /* Search support */ 3028 /* */ 3029 /* the libc resolver has support for searching a number of domains */ 3030 /* to find a name. If nothing else then it takes the single domain */ 3031 /* from the gethostname() call. */ 3032 /* */ 3033 /* It can also be configured via the domain and search options in a */ 3034 /* resolv.conf. */ 3035 /* */ 3036 /* The ndots option controls how many dots it takes for the resolver */ 3037 /* to decide that a name is non-local and so try a raw lookup first. */ 3038 3039 struct search_domain { 3040 int len; 3041 struct search_domain *next; 3042 /* the text string is appended to this structure */ 3043 }; 3044 3045 struct search_state { 3046 int refcount; 3047 int ndots; 3048 int num_domains; 3049 struct search_domain *head; 3050 }; 3051 3052 static void 3053 search_state_decref(struct search_state *const state) { 3054 if (!state) return; 3055 state->refcount--; 3056 if (!state->refcount) { 3057 struct search_domain *next, *dom; 3058 for (dom = state->head; dom; dom = next) { 3059 next = dom->next; 3060 mm_free(dom); 3061 } 3062 mm_free(state); 3063 } 3064 } 3065 3066 static struct search_state * 3067 search_state_new(void) { 3068 struct search_state *state = (struct search_state *) mm_malloc(sizeof(struct search_state)); 3069 if (!state) return NULL; 3070 memset(state, 0, sizeof(struct search_state)); 3071 state->refcount = 1; 3072 state->ndots = 1; 3073 3074 return state; 3075 } 3076 3077 static void 3078 search_postfix_clear(struct evdns_base *base) { 3079 search_state_decref(base->global_search_state); 3080 3081 base->global_search_state = search_state_new(); 3082 } 3083 3084 /* exported function */ 3085 void 3086 evdns_base_search_clear(struct evdns_base *base) 3087 { 3088 EVDNS_LOCK(base); 3089 search_postfix_clear(base); 3090 EVDNS_UNLOCK(base); 3091 } 3092 3093 void 3094 evdns_search_clear(void) { 3095 evdns_base_search_clear(current_base); 3096 } 3097 3098 static void 3099 search_postfix_add(struct evdns_base *base, const char *domain) { 3100 size_t domain_len; 3101 struct search_domain *sdomain; 3102 while (domain[0] == '.') domain++; 3103 domain_len = strlen(domain); 3104 3105 ASSERT_LOCKED(base); 3106 if (!base->global_search_state) base->global_search_state = search_state_new(); 3107 if (!base->global_search_state) return; 3108 base->global_search_state->num_domains++; 3109 3110 sdomain = (struct search_domain *) mm_malloc(sizeof(struct search_domain) + domain_len); 3111 if (!sdomain) return; 3112 memcpy( ((u8 *) sdomain) + sizeof(struct search_domain), domain, domain_len); 3113 sdomain->next = base->global_search_state->head; 3114 sdomain->len = (int) domain_len; 3115 3116 base->global_search_state->head = sdomain; 3117 } 3118 3119 /* reverse the order of members in the postfix list. This is needed because, */ 3120 /* when parsing resolv.conf we push elements in the wrong order */ 3121 static void 3122 search_reverse(struct evdns_base *base) { 3123 struct search_domain *cur, *prev = NULL, *next; 3124 ASSERT_LOCKED(base); 3125 cur = base->global_search_state->head; 3126 while (cur) { 3127 next = cur->next; 3128 cur->next = prev; 3129 prev = cur; 3130 cur = next; 3131 } 3132 3133 base->global_search_state->head = prev; 3134 } 3135 3136 /* exported function */ 3137 void 3138 evdns_base_search_add(struct evdns_base *base, const char *domain) { 3139 EVDNS_LOCK(base); 3140 search_postfix_add(base, domain); 3141 EVDNS_UNLOCK(base); 3142 } 3143 void 3144 evdns_search_add(const char *domain) { 3145 evdns_base_search_add(current_base, domain); 3146 } 3147 3148 /* exported function */ 3149 void 3150 evdns_base_search_ndots_set(struct evdns_base *base, const int ndots) { 3151 EVDNS_LOCK(base); 3152 if (!base->global_search_state) base->global_search_state = search_state_new(); 3153 if (base->global_search_state) 3154 base->global_search_state->ndots = ndots; 3155 EVDNS_UNLOCK(base); 3156 } 3157 void 3158 evdns_search_ndots_set(const int ndots) { 3159 evdns_base_search_ndots_set(current_base, ndots); 3160 } 3161 3162 static void 3163 search_set_from_hostname(struct evdns_base *base) { 3164 char hostname[HOST_NAME_MAX + 1], *domainname; 3165 3166 ASSERT_LOCKED(base); 3167 search_postfix_clear(base); 3168 if (gethostname(hostname, sizeof(hostname))) return; 3169 domainname = strchr(hostname, '.'); 3170 if (!domainname) return; 3171 search_postfix_add(base, domainname); 3172 } 3173 3174 /* warning: returns malloced string */ 3175 static char * 3176 search_make_new(const struct search_state *const state, int n, const char *const base_name) { 3177 const size_t base_len = strlen(base_name); 3178 char need_to_append_dot; 3179 struct search_domain *dom; 3180 3181 if (!base_len) return NULL; 3182 need_to_append_dot = base_name[base_len - 1] == '.' ? 0 : 1; 3183 3184 for (dom = state->head; dom; dom = dom->next) { 3185 if (!n--) { 3186 /* this is the postfix we want */ 3187 /* the actual postfix string is kept at the end of the structure */ 3188 const u8 *const postfix = ((u8 *) dom) + sizeof(struct search_domain); 3189 const int postfix_len = dom->len; 3190 char *const newname = (char *) mm_malloc(base_len + need_to_append_dot + postfix_len + 1); 3191 if (!newname) return NULL; 3192 memcpy(newname, base_name, base_len); 3193 if (need_to_append_dot) newname[base_len] = '.'; 3194 memcpy(newname + base_len + need_to_append_dot, postfix, postfix_len); 3195 newname[base_len + need_to_append_dot + postfix_len] = 0; 3196 return newname; 3197 } 3198 } 3199 3200 /* we ran off the end of the list and still didn't find the requested string */ 3201 EVUTIL_ASSERT(0); 3202 return NULL; /* unreachable; stops warnings in some compilers. */ 3203 } 3204 3205 static struct request * 3206 search_request_new(struct evdns_base *base, struct evdns_request *handle, 3207 int type, const char *const name, int flags, 3208 evdns_callback_type user_callback, void *user_arg) { 3209 ASSERT_LOCKED(base); 3210 EVUTIL_ASSERT(type == TYPE_A || type == TYPE_AAAA); 3211 EVUTIL_ASSERT(handle->current_req == NULL); 3212 if ( ((flags & DNS_QUERY_NO_SEARCH) == 0) && 3213 base->global_search_state && 3214 base->global_search_state->num_domains) { 3215 /* we have some domains to search */ 3216 struct request *req; 3217 if (string_num_dots(name) >= base->global_search_state->ndots) { 3218 req = request_new(base, handle, type, name, flags, user_callback, user_arg); 3219 if (!req) return NULL; 3220 handle->search_index = -1; 3221 } else { 3222 char *const new_name = search_make_new(base->global_search_state, 0, name); 3223 if (!new_name) return NULL; 3224 req = request_new(base, handle, type, new_name, flags, user_callback, user_arg); 3225 mm_free(new_name); 3226 if (!req) return NULL; 3227 handle->search_index = 0; 3228 } 3229 EVUTIL_ASSERT(handle->search_origname == NULL); 3230 handle->search_origname = mm_strdup(name); 3231 if (handle->search_origname == NULL) { 3232 /* XXX Should we dealloc req? If yes, how? */ 3233 if (req) 3234 mm_free(req); 3235 return NULL; 3236 } 3237 handle->search_state = base->global_search_state; 3238 handle->search_flags = flags; 3239 base->global_search_state->refcount++; 3240 request_submit(req); 3241 return req; 3242 } else { 3243 struct request *const req = request_new(base, handle, type, name, flags, user_callback, user_arg); 3244 if (!req) return NULL; 3245 request_submit(req); 3246 return req; 3247 } 3248 } 3249 3250 /* this is called when a request has failed to find a name. We need to check */ 3251 /* if it is part of a search and, if so, try the next name in the list */ 3252 /* returns: */ 3253 /* 0 another request has been submitted */ 3254 /* 1 no more requests needed */ 3255 static int 3256 search_try_next(struct evdns_request *const handle) { 3257 struct request *req = handle->current_req; 3258 struct evdns_base *base = req->base; 3259 struct request *newreq; 3260 ASSERT_LOCKED(base); 3261 if (handle->search_state) { 3262 /* it is part of a search */ 3263 char *new_name; 3264 handle->search_index++; 3265 if (handle->search_index >= handle->search_state->num_domains) { 3266 /* no more postfixes to try, however we may need to try */ 3267 /* this name without a postfix */ 3268 if (string_num_dots(handle->search_origname) < handle->search_state->ndots) { 3269 /* yep, we need to try it raw */ 3270 newreq = request_new(base, NULL, req->request_type, handle->search_origname, handle->search_flags, req->user_callback, req->user_pointer); 3271 log(EVDNS_LOG_DEBUG, "Search: trying raw query %s", handle->search_origname); 3272 if (newreq) { 3273 search_request_finished(handle); 3274 goto submit_next; 3275 } 3276 } 3277 return 1; 3278 } 3279 3280 new_name = search_make_new(handle->search_state, handle->search_index, handle->search_origname); 3281 if (!new_name) return 1; 3282 log(EVDNS_LOG_DEBUG, "Search: now trying %s (%d)", new_name, handle->search_index); 3283 newreq = request_new(base, NULL, req->request_type, new_name, handle->search_flags, req->user_callback, req->user_pointer); 3284 mm_free(new_name); 3285 if (!newreq) return 1; 3286 goto submit_next; 3287 } 3288 return 1; 3289 3290 submit_next: 3291 request_finished(req, &REQ_HEAD(req->base, req->trans_id), 0); 3292 handle->current_req = newreq; 3293 newreq->handle = handle; 3294 request_submit(newreq); 3295 return 0; 3296 } 3297 3298 static void 3299 search_request_finished(struct evdns_request *const handle) { 3300 ASSERT_LOCKED(handle->current_req->base); 3301 if (handle->search_state) { 3302 search_state_decref(handle->search_state); 3303 handle->search_state = NULL; 3304 } 3305 if (handle->search_origname) { 3306 mm_free(handle->search_origname); 3307 handle->search_origname = NULL; 3308 } 3309 } 3310 3311 /* ================================================================= */ 3312 /* Parsing resolv.conf files */ 3313 3314 static void 3315 evdns_resolv_set_defaults(struct evdns_base *base, int flags) { 3316 /* if the file isn't found then we assume a local resolver */ 3317 ASSERT_LOCKED(base); 3318 if (flags & DNS_OPTION_SEARCH) search_set_from_hostname(base); 3319 if (flags & DNS_OPTION_NAMESERVERS) evdns_base_nameserver_ip_add(base,"127.0.0.1"); 3320 } 3321 3322 #ifndef EVENT__HAVE_STRTOK_R 3323 static char * 3324 strtok_r(char *s, const char *delim, char **state) { 3325 char *cp, *start; 3326 start = cp = s ? s : *state; 3327 if (!cp) 3328 return NULL; 3329 while (*cp && !strchr(delim, *cp)) 3330 ++cp; 3331 if (!*cp) { 3332 if (cp == start) 3333 return NULL; 3334 *state = NULL; 3335 return start; 3336 } else { 3337 *cp++ = '\0'; 3338 *state = cp; 3339 return start; 3340 } 3341 } 3342 #endif 3343 3344 /* helper version of atoi which returns -1 on error */ 3345 static int 3346 strtoint(const char *const str) 3347 { 3348 char *endptr; 3349 const int r = strtol(str, &endptr, 10); 3350 if (*endptr) return -1; 3351 return r; 3352 } 3353 3354 /* Parse a number of seconds into a timeval; return -1 on error. */ 3355 static int 3356 evdns_strtotimeval(const char *const str, struct timeval *out) 3357 { 3358 double d; 3359 char *endptr; 3360 d = strtod(str, &endptr); 3361 if (*endptr) return -1; 3362 if (d < 0) return -1; 3363 out->tv_sec = (int) d; 3364 out->tv_usec = (int) ((d - (int) d)*1000000); 3365 if (out->tv_sec == 0 && out->tv_usec < 1000) /* less than 1 msec */ 3366 return -1; 3367 return 0; 3368 } 3369 3370 /* helper version of atoi that returns -1 on error and clips to bounds. */ 3371 static int 3372 strtoint_clipped(const char *const str, int min, int max) 3373 { 3374 int r = strtoint(str); 3375 if (r == -1) 3376 return r; 3377 else if (r<min) 3378 return min; 3379 else if (r>max) 3380 return max; 3381 else 3382 return r; 3383 } 3384 3385 static int 3386 evdns_base_set_max_requests_inflight(struct evdns_base *base, int maxinflight) 3387 { 3388 int old_n_heads = base->n_req_heads, n_heads; 3389 struct request **old_heads = base->req_heads, **new_heads, *req; 3390 int i; 3391 3392 ASSERT_LOCKED(base); 3393 if (maxinflight < 1) 3394 maxinflight = 1; 3395 n_heads = (maxinflight+4) / 5; 3396 EVUTIL_ASSERT(n_heads > 0); 3397 new_heads = mm_calloc(n_heads, sizeof(struct request*)); 3398 if (!new_heads) 3399 return (-1); 3400 if (old_heads) { 3401 for (i = 0; i < old_n_heads; ++i) { 3402 while (old_heads[i]) { 3403 req = old_heads[i]; 3404 evdns_request_remove(req, &old_heads[i]); 3405 evdns_request_insert(req, &new_heads[req->trans_id % n_heads]); 3406 } 3407 } 3408 mm_free(old_heads); 3409 } 3410 base->req_heads = new_heads; 3411 base->n_req_heads = n_heads; 3412 base->global_max_requests_inflight = maxinflight; 3413 return (0); 3414 } 3415 3416 /* exported function */ 3417 int 3418 evdns_base_set_option(struct evdns_base *base, 3419 const char *option, const char *val) 3420 { 3421 int res; 3422 EVDNS_LOCK(base); 3423 res = evdns_base_set_option_impl(base, option, val, DNS_OPTIONS_ALL); 3424 EVDNS_UNLOCK(base); 3425 return res; 3426 } 3427 3428 static inline int 3429 str_matches_option(const char *s1, const char *optionname) 3430 { 3431 /* Option names are given as "option:" We accept either 'option' in 3432 * s1, or 'option:randomjunk'. The latter form is to implement the 3433 * resolv.conf parser. */ 3434 size_t optlen = strlen(optionname); 3435 size_t slen = strlen(s1); 3436 if (slen == optlen || slen == optlen - 1) 3437 return !strncmp(s1, optionname, slen); 3438 else if (slen > optlen) 3439 return !strncmp(s1, optionname, optlen); 3440 else 3441 return 0; 3442 } 3443 3444 static int 3445 evdns_base_set_option_impl(struct evdns_base *base, 3446 const char *option, const char *val, int flags) 3447 { 3448 ASSERT_LOCKED(base); 3449 if (str_matches_option(option, "ndots:")) { 3450 const int ndots = strtoint(val); 3451 if (ndots == -1) return -1; 3452 if (!(flags & DNS_OPTION_SEARCH)) return 0; 3453 log(EVDNS_LOG_DEBUG, "Setting ndots to %d", ndots); 3454 if (!base->global_search_state) base->global_search_state = search_state_new(); 3455 if (!base->global_search_state) return -1; 3456 base->global_search_state->ndots = ndots; 3457 } else if (str_matches_option(option, "timeout:")) { 3458 struct timeval tv; 3459 if (evdns_strtotimeval(val, &tv) == -1) return -1; 3460 if (!(flags & DNS_OPTION_MISC)) return 0; 3461 log(EVDNS_LOG_DEBUG, "Setting timeout to %s", val); 3462 memcpy(&base->global_timeout, &tv, sizeof(struct timeval)); 3463 } else if (str_matches_option(option, "getaddrinfo-allow-skew:")) { 3464 struct timeval tv; 3465 if (evdns_strtotimeval(val, &tv) == -1) return -1; 3466 if (!(flags & DNS_OPTION_MISC)) return 0; 3467 log(EVDNS_LOG_DEBUG, "Setting getaddrinfo-allow-skew to %s", 3468 val); 3469 memcpy(&base->global_getaddrinfo_allow_skew, &tv, 3470 sizeof(struct timeval)); 3471 } else if (str_matches_option(option, "max-timeouts:")) { 3472 const int maxtimeout = strtoint_clipped(val, 1, 255); 3473 if (maxtimeout == -1) return -1; 3474 if (!(flags & DNS_OPTION_MISC)) return 0; 3475 log(EVDNS_LOG_DEBUG, "Setting maximum allowed timeouts to %d", 3476 maxtimeout); 3477 base->global_max_nameserver_timeout = maxtimeout; 3478 } else if (str_matches_option(option, "max-inflight:")) { 3479 const int maxinflight = strtoint_clipped(val, 1, 65000); 3480 if (maxinflight == -1) return -1; 3481 if (!(flags & DNS_OPTION_MISC)) return 0; 3482 log(EVDNS_LOG_DEBUG, "Setting maximum inflight requests to %d", 3483 maxinflight); 3484 evdns_base_set_max_requests_inflight(base, maxinflight); 3485 } else if (str_matches_option(option, "attempts:")) { 3486 int retries = strtoint(val); 3487 if (retries == -1) return -1; 3488 if (retries > 255) retries = 255; 3489 if (!(flags & DNS_OPTION_MISC)) return 0; 3490 log(EVDNS_LOG_DEBUG, "Setting retries to %d", retries); 3491 base->global_max_retransmits = retries; 3492 } else if (str_matches_option(option, "randomize-case:")) { 3493 int randcase = strtoint(val); 3494 if (!(flags & DNS_OPTION_MISC)) return 0; 3495 base->global_randomize_case = randcase; 3496 } else if (str_matches_option(option, "bind-to:")) { 3497 /* XXX This only applies to successive nameservers, not 3498 * to already-configured ones. We might want to fix that. */ 3499 int len = sizeof(base->global_outgoing_address); 3500 if (!(flags & DNS_OPTION_NAMESERVERS)) return 0; 3501 if (evutil_parse_sockaddr_port(val, 3502 (struct sockaddr*)&base->global_outgoing_address, &len)) 3503 return -1; 3504 base->global_outgoing_addrlen = len; 3505 } else if (str_matches_option(option, "initial-probe-timeout:")) { 3506 struct timeval tv; 3507 if (evdns_strtotimeval(val, &tv) == -1) return -1; 3508 if (tv.tv_sec > 3600) 3509 tv.tv_sec = 3600; 3510 if (!(flags & DNS_OPTION_MISC)) return 0; 3511 log(EVDNS_LOG_DEBUG, "Setting initial probe timeout to %s", 3512 val); 3513 memcpy(&base->global_nameserver_probe_initial_timeout, &tv, 3514 sizeof(tv)); 3515 } 3516 return 0; 3517 } 3518 3519 int 3520 evdns_set_option(const char *option, const char *val, int flags) 3521 { 3522 if (!current_base) 3523 current_base = evdns_base_new(NULL, 0); 3524 return evdns_base_set_option(current_base, option, val); 3525 } 3526 3527 static void 3528 resolv_conf_parse_line(struct evdns_base *base, char *const start, int flags) { 3529 char *strtok_state; 3530 static const char *const delims = " \t"; 3531 #define NEXT_TOKEN strtok_r(NULL, delims, &strtok_state) 3532 3533 3534 char *const first_token = strtok_r(start, delims, &strtok_state); 3535 ASSERT_LOCKED(base); 3536 if (!first_token) return; 3537 3538 if (!strcmp(first_token, "nameserver") && (flags & DNS_OPTION_NAMESERVERS)) { 3539 const char *const nameserver = NEXT_TOKEN; 3540 3541 if (nameserver) 3542 evdns_base_nameserver_ip_add(base, nameserver); 3543 } else if (!strcmp(first_token, "domain") && (flags & DNS_OPTION_SEARCH)) { 3544 const char *const domain = NEXT_TOKEN; 3545 if (domain) { 3546 search_postfix_clear(base); 3547 search_postfix_add(base, domain); 3548 } 3549 } else if (!strcmp(first_token, "search") && (flags & DNS_OPTION_SEARCH)) { 3550 const char *domain; 3551 search_postfix_clear(base); 3552 3553 while ((domain = NEXT_TOKEN)) { 3554 search_postfix_add(base, domain); 3555 } 3556 search_reverse(base); 3557 } else if (!strcmp(first_token, "options")) { 3558 const char *option; 3559 while ((option = NEXT_TOKEN)) { 3560 const char *val = strchr(option, ':'); 3561 evdns_base_set_option_impl(base, option, val ? val+1 : "", flags); 3562 } 3563 } 3564 #undef NEXT_TOKEN 3565 } 3566 3567 /* exported function */ 3568 /* returns: */ 3569 /* 0 no errors */ 3570 /* 1 failed to open file */ 3571 /* 2 failed to stat file */ 3572 /* 3 file too large */ 3573 /* 4 out of memory */ 3574 /* 5 short read from file */ 3575 int 3576 evdns_base_resolv_conf_parse(struct evdns_base *base, int flags, const char *const filename) { 3577 int res; 3578 EVDNS_LOCK(base); 3579 res = evdns_base_resolv_conf_parse_impl(base, flags, filename); 3580 EVDNS_UNLOCK(base); 3581 return res; 3582 } 3583 3584 static char * 3585 evdns_get_default_hosts_filename(void) 3586 { 3587 #ifdef _WIN32 3588 /* Windows is a little coy about where it puts its configuration 3589 * files. Sure, they're _usually_ in C:\windows\system32, but 3590 * there's no reason in principle they couldn't be in 3591 * W:\hoboken chicken emergency\ 3592 */ 3593 char path[MAX_PATH+1]; 3594 static const char hostfile[] = "\\drivers\\etc\\hosts"; 3595 char *path_out; 3596 size_t len_out; 3597 3598 if (! SHGetSpecialFolderPathA(NULL, path, CSIDL_SYSTEM, 0)) 3599 return NULL; 3600 len_out = strlen(path)+strlen(hostfile)+1; 3601 path_out = mm_malloc(len_out); 3602 evutil_snprintf(path_out, len_out, "%s%s", path, hostfile); 3603 return path_out; 3604 #else 3605 return mm_strdup("/etc/hosts"); 3606 #endif 3607 } 3608 3609 static int 3610 evdns_base_resolv_conf_parse_impl(struct evdns_base *base, int flags, const char *const filename) { 3611 size_t n; 3612 char *resolv; 3613 char *start; 3614 int err = 0; 3615 3616 log(EVDNS_LOG_DEBUG, "Parsing resolv.conf file %s", filename); 3617 3618 if (flags & DNS_OPTION_HOSTSFILE) { 3619 char *fname = evdns_get_default_hosts_filename(); 3620 evdns_base_load_hosts(base, fname); 3621 if (fname) 3622 mm_free(fname); 3623 } 3624 3625 if ((err = evutil_read_file_(filename, &resolv, &n, 0)) < 0) { 3626 if (err == -1) { 3627 /* No file. */ 3628 evdns_resolv_set_defaults(base, flags); 3629 return 1; 3630 } else { 3631 return 2; 3632 } 3633 } 3634 3635 start = resolv; 3636 for (;;) { 3637 char *const newline = strchr(start, '\n'); 3638 if (!newline) { 3639 resolv_conf_parse_line(base, start, flags); 3640 break; 3641 } else { 3642 *newline = 0; 3643 resolv_conf_parse_line(base, start, flags); 3644 start = newline + 1; 3645 } 3646 } 3647 3648 if (!base->server_head && (flags & DNS_OPTION_NAMESERVERS)) { 3649 /* no nameservers were configured. */ 3650 evdns_base_nameserver_ip_add(base, "127.0.0.1"); 3651 err = 6; 3652 } 3653 if (flags & DNS_OPTION_SEARCH && (!base->global_search_state || base->global_search_state->num_domains == 0)) { 3654 search_set_from_hostname(base); 3655 } 3656 3657 mm_free(resolv); 3658 return err; 3659 } 3660 3661 int 3662 evdns_resolv_conf_parse(int flags, const char *const filename) { 3663 if (!current_base) 3664 current_base = evdns_base_new(NULL, 0); 3665 return evdns_base_resolv_conf_parse(current_base, flags, filename); 3666 } 3667 3668 3669 #ifdef _WIN32 3670 /* Add multiple nameservers from a space-or-comma-separated list. */ 3671 static int 3672 evdns_nameserver_ip_add_line(struct evdns_base *base, const char *ips) { 3673 const char *addr; 3674 char *buf; 3675 int r; 3676 ASSERT_LOCKED(base); 3677 while (*ips) { 3678 while (isspace(*ips) || *ips == ',' || *ips == '\t') 3679 ++ips; 3680 addr = ips; 3681 while (isdigit(*ips) || *ips == '.' || *ips == ':' || 3682 *ips=='[' || *ips==']') 3683 ++ips; 3684 buf = mm_malloc(ips-addr+1); 3685 if (!buf) return 4; 3686 memcpy(buf, addr, ips-addr); 3687 buf[ips-addr] = '\0'; 3688 r = evdns_base_nameserver_ip_add(base, buf); 3689 mm_free(buf); 3690 if (r) return r; 3691 } 3692 return 0; 3693 } 3694 3695 typedef DWORD(WINAPI *GetNetworkParams_fn_t)(FIXED_INFO *, DWORD*); 3696 3697 /* Use the windows GetNetworkParams interface in iphlpapi.dll to */ 3698 /* figure out what our nameservers are. */ 3699 static int 3700 load_nameservers_with_getnetworkparams(struct evdns_base *base) 3701 { 3702 /* Based on MSDN examples and inspection of c-ares code. */ 3703 FIXED_INFO *fixed; 3704 HMODULE handle = 0; 3705 ULONG size = sizeof(FIXED_INFO); 3706 void *buf = NULL; 3707 int status = 0, r, added_any; 3708 IP_ADDR_STRING *ns; 3709 GetNetworkParams_fn_t fn; 3710 3711 ASSERT_LOCKED(base); 3712 if (!(handle = evutil_load_windows_system_library_( 3713 TEXT("iphlpapi.dll")))) { 3714 log(EVDNS_LOG_WARN, "Could not open iphlpapi.dll"); 3715 status = -1; 3716 goto done; 3717 } 3718 if (!(fn = (GetNetworkParams_fn_t) GetProcAddress(handle, "GetNetworkParams"))) { 3719 log(EVDNS_LOG_WARN, "Could not get address of function."); 3720 status = -1; 3721 goto done; 3722 } 3723 3724 buf = mm_malloc(size); 3725 if (!buf) { status = 4; goto done; } 3726 fixed = buf; 3727 r = fn(fixed, &size); 3728 if (r != ERROR_SUCCESS && r != ERROR_BUFFER_OVERFLOW) { 3729 status = -1; 3730 goto done; 3731 } 3732 if (r != ERROR_SUCCESS) { 3733 mm_free(buf); 3734 buf = mm_malloc(size); 3735 if (!buf) { status = 4; goto done; } 3736 fixed = buf; 3737 r = fn(fixed, &size); 3738 if (r != ERROR_SUCCESS) { 3739 log(EVDNS_LOG_DEBUG, "fn() failed."); 3740 status = -1; 3741 goto done; 3742 } 3743 } 3744 3745 EVUTIL_ASSERT(fixed); 3746 added_any = 0; 3747 ns = &(fixed->DnsServerList); 3748 while (ns) { 3749 r = evdns_nameserver_ip_add_line(base, ns->IpAddress.String); 3750 if (r) { 3751 log(EVDNS_LOG_DEBUG,"Could not add nameserver %s to list,error: %d", 3752 (ns->IpAddress.String),(int)GetLastError()); 3753 status = r; 3754 } else { 3755 ++added_any; 3756 log(EVDNS_LOG_DEBUG,"Successfully added %s as nameserver",ns->IpAddress.String); 3757 } 3758 3759 ns = ns->Next; 3760 } 3761 3762 if (!added_any) { 3763 log(EVDNS_LOG_DEBUG, "No nameservers added."); 3764 if (status == 0) 3765 status = -1; 3766 } else { 3767 status = 0; 3768 } 3769 3770 done: 3771 if (buf) 3772 mm_free(buf); 3773 if (handle) 3774 FreeLibrary(handle); 3775 return status; 3776 } 3777 3778 static int 3779 config_nameserver_from_reg_key(struct evdns_base *base, HKEY key, const TCHAR *subkey) 3780 { 3781 char *buf; 3782 DWORD bufsz = 0, type = 0; 3783 int status = 0; 3784 3785 ASSERT_LOCKED(base); 3786 if (RegQueryValueEx(key, subkey, 0, &type, NULL, &bufsz) 3787 != ERROR_MORE_DATA) 3788 return -1; 3789 if (!(buf = mm_malloc(bufsz))) 3790 return -1; 3791 3792 if (RegQueryValueEx(key, subkey, 0, &type, (LPBYTE)buf, &bufsz) 3793 == ERROR_SUCCESS && bufsz > 1) { 3794 status = evdns_nameserver_ip_add_line(base,buf); 3795 } 3796 3797 mm_free(buf); 3798 return status; 3799 } 3800 3801 #define SERVICES_KEY TEXT("System\\CurrentControlSet\\Services\\") 3802 #define WIN_NS_9X_KEY SERVICES_KEY TEXT("VxD\\MSTCP") 3803 #define WIN_NS_NT_KEY SERVICES_KEY TEXT("Tcpip\\Parameters") 3804 3805 static int 3806 load_nameservers_from_registry(struct evdns_base *base) 3807 { 3808 int found = 0; 3809 int r; 3810 #define TRY(k, name) \ 3811 if (!found && config_nameserver_from_reg_key(base,k,TEXT(name)) == 0) { \ 3812 log(EVDNS_LOG_DEBUG,"Found nameservers in %s/%s",#k,name); \ 3813 found = 1; \ 3814 } else if (!found) { \ 3815 log(EVDNS_LOG_DEBUG,"Didn't find nameservers in %s/%s", \ 3816 #k,#name); \ 3817 } 3818 3819 ASSERT_LOCKED(base); 3820 3821 if (((int)GetVersion()) > 0) { /* NT */ 3822 HKEY nt_key = 0, interfaces_key = 0; 3823 3824 if (RegOpenKeyEx(HKEY_LOCAL_MACHINE, WIN_NS_NT_KEY, 0, 3825 KEY_READ, &nt_key) != ERROR_SUCCESS) { 3826 log(EVDNS_LOG_DEBUG,"Couldn't open nt key, %d",(int)GetLastError()); 3827 return -1; 3828 } 3829 r = RegOpenKeyEx(nt_key, TEXT("Interfaces"), 0, 3830 KEY_QUERY_VALUE|KEY_ENUMERATE_SUB_KEYS, 3831 &interfaces_key); 3832 if (r != ERROR_SUCCESS) { 3833 log(EVDNS_LOG_DEBUG,"Couldn't open interfaces key, %d",(int)GetLastError()); 3834 return -1; 3835 } 3836 TRY(nt_key, "NameServer"); 3837 TRY(nt_key, "DhcpNameServer"); 3838 TRY(interfaces_key, "NameServer"); 3839 TRY(interfaces_key, "DhcpNameServer"); 3840 RegCloseKey(interfaces_key); 3841 RegCloseKey(nt_key); 3842 } else { 3843 HKEY win_key = 0; 3844 if (RegOpenKeyEx(HKEY_LOCAL_MACHINE, WIN_NS_9X_KEY, 0, 3845 KEY_READ, &win_key) != ERROR_SUCCESS) { 3846 log(EVDNS_LOG_DEBUG, "Couldn't open registry key, %d", (int)GetLastError()); 3847 return -1; 3848 } 3849 TRY(win_key, "NameServer"); 3850 RegCloseKey(win_key); 3851 } 3852 3853 if (found == 0) { 3854 log(EVDNS_LOG_WARN,"Didn't find any nameservers."); 3855 } 3856 3857 return found ? 0 : -1; 3858 #undef TRY 3859 } 3860 3861 int 3862 evdns_base_config_windows_nameservers(struct evdns_base *base) 3863 { 3864 int r; 3865 char *fname; 3866 if (base == NULL) 3867 base = current_base; 3868 if (base == NULL) 3869 return -1; 3870 EVDNS_LOCK(base); 3871 fname = evdns_get_default_hosts_filename(); 3872 log(EVDNS_LOG_DEBUG, "Loading hosts entries from %s", fname); 3873 evdns_base_load_hosts(base, fname); 3874 if (fname) 3875 mm_free(fname); 3876 3877 if (load_nameservers_with_getnetworkparams(base) == 0) { 3878 EVDNS_UNLOCK(base); 3879 return 0; 3880 } 3881 r = load_nameservers_from_registry(base); 3882 3883 EVDNS_UNLOCK(base); 3884 return r; 3885 } 3886 3887 int 3888 evdns_config_windows_nameservers(void) 3889 { 3890 if (!current_base) { 3891 current_base = evdns_base_new(NULL, 1); 3892 return current_base == NULL ? -1 : 0; 3893 } else { 3894 return evdns_base_config_windows_nameservers(current_base); 3895 } 3896 } 3897 #endif 3898 3899 struct evdns_base * 3900 evdns_base_new(struct event_base *event_base, int flags) 3901 { 3902 struct evdns_base *base; 3903 3904 if (evutil_secure_rng_init() < 0) { 3905 log(EVDNS_LOG_WARN, "Unable to seed random number generator; " 3906 "DNS can't run."); 3907 return NULL; 3908 } 3909 3910 /* Give the evutil library a hook into its evdns-enabled 3911 * functionality. We can't just call evdns_getaddrinfo directly or 3912 * else libevent-core will depend on libevent-extras. */ 3913 evutil_set_evdns_getaddrinfo_fn_(evdns_getaddrinfo); 3914 evutil_set_evdns_getaddrinfo_cancel_fn_(evdns_getaddrinfo_cancel); 3915 3916 base = mm_malloc(sizeof(struct evdns_base)); 3917 if (base == NULL) 3918 return (NULL); 3919 memset(base, 0, sizeof(struct evdns_base)); 3920 base->req_waiting_head = NULL; 3921 3922 EVTHREAD_ALLOC_LOCK(base->lock, EVTHREAD_LOCKTYPE_RECURSIVE); 3923 EVDNS_LOCK(base); 3924 3925 /* Set max requests inflight and allocate req_heads. */ 3926 base->req_heads = NULL; 3927 3928 evdns_base_set_max_requests_inflight(base, 64); 3929 3930 base->server_head = NULL; 3931 base->event_base = event_base; 3932 base->global_good_nameservers = base->global_requests_inflight = 3933 base->global_requests_waiting = 0; 3934 3935 base->global_timeout.tv_sec = 5; 3936 base->global_timeout.tv_usec = 0; 3937 base->global_max_reissues = 1; 3938 base->global_max_retransmits = 3; 3939 base->global_max_nameserver_timeout = 3; 3940 base->global_search_state = NULL; 3941 base->global_randomize_case = 1; 3942 base->global_getaddrinfo_allow_skew.tv_sec = 3; 3943 base->global_getaddrinfo_allow_skew.tv_usec = 0; 3944 base->global_nameserver_probe_initial_timeout.tv_sec = 10; 3945 base->global_nameserver_probe_initial_timeout.tv_usec = 0; 3946 3947 TAILQ_INIT(&base->hostsdb); 3948 3949 #define EVDNS_BASE_ALL_FLAGS (0x8001) 3950 if (flags & ~EVDNS_BASE_ALL_FLAGS) { 3951 flags = EVDNS_BASE_INITIALIZE_NAMESERVERS; 3952 log(EVDNS_LOG_WARN, 3953 "Unrecognized flag passed to evdns_base_new(). Assuming " 3954 "you meant EVDNS_BASE_INITIALIZE_NAMESERVERS."); 3955 } 3956 #undef EVDNS_BASE_ALL_FLAGS 3957 3958 if (flags & EVDNS_BASE_INITIALIZE_NAMESERVERS) { 3959 int r; 3960 #ifdef _WIN32 3961 r = evdns_base_config_windows_nameservers(base); 3962 #else 3963 r = evdns_base_resolv_conf_parse(base, DNS_OPTIONS_ALL, "/etc/resolv.conf"); 3964 #endif 3965 if (r == -1) { 3966 evdns_base_free_and_unlock(base, 0); 3967 return NULL; 3968 } 3969 } 3970 if (flags & EVDNS_BASE_DISABLE_WHEN_INACTIVE) { 3971 base->disable_when_inactive = 1; 3972 } 3973 3974 EVDNS_UNLOCK(base); 3975 return base; 3976 } 3977 3978 int 3979 evdns_init(void) 3980 { 3981 struct evdns_base *base = evdns_base_new(NULL, 1); 3982 if (base) { 3983 current_base = base; 3984 return 0; 3985 } else { 3986 return -1; 3987 } 3988 } 3989 3990 const char * 3991 evdns_err_to_string(int err) 3992 { 3993 switch (err) { 3994 case DNS_ERR_NONE: return "no error"; 3995 case DNS_ERR_FORMAT: return "misformatted query"; 3996 case DNS_ERR_SERVERFAILED: return "server failed"; 3997 case DNS_ERR_NOTEXIST: return "name does not exist"; 3998 case DNS_ERR_NOTIMPL: return "query not implemented"; 3999 case DNS_ERR_REFUSED: return "refused"; 4000 4001 case DNS_ERR_TRUNCATED: return "reply truncated or ill-formed"; 4002 case DNS_ERR_UNKNOWN: return "unknown"; 4003 case DNS_ERR_TIMEOUT: return "request timed out"; 4004 case DNS_ERR_SHUTDOWN: return "dns subsystem shut down"; 4005 case DNS_ERR_CANCEL: return "dns request canceled"; 4006 case DNS_ERR_NODATA: return "no records in the reply"; 4007 default: return "[Unknown error code]"; 4008 } 4009 } 4010 4011 static void 4012 evdns_nameserver_free(struct nameserver *server) 4013 { 4014 if (server->socket >= 0) 4015 evutil_closesocket(server->socket); 4016 (void) event_del(&server->event); 4017 event_debug_unassign(&server->event); 4018 if (server->state == 0) 4019 (void) event_del(&server->timeout_event); 4020 if (server->probe_request) { 4021 evdns_cancel_request(server->base, server->probe_request); 4022 server->probe_request = NULL; 4023 } 4024 event_debug_unassign(&server->timeout_event); 4025 mm_free(server); 4026 } 4027 4028 static void 4029 evdns_base_free_and_unlock(struct evdns_base *base, int fail_requests) 4030 { 4031 struct nameserver *server, *server_next; 4032 struct search_domain *dom, *dom_next; 4033 int i; 4034 4035 /* Requires that we hold the lock. */ 4036 4037 /* TODO(nickm) we might need to refcount here. */ 4038 4039 for (i = 0; i < base->n_req_heads; ++i) { 4040 while (base->req_heads[i]) { 4041 if (fail_requests) 4042 reply_schedule_callback(base->req_heads[i], 0, DNS_ERR_SHUTDOWN, NULL); 4043 request_finished(base->req_heads[i], &REQ_HEAD(base, base->req_heads[i]->trans_id), 1); 4044 } 4045 } 4046 while (base->req_waiting_head) { 4047 if (fail_requests) 4048 reply_schedule_callback(base->req_waiting_head, 0, DNS_ERR_SHUTDOWN, NULL); 4049 request_finished(base->req_waiting_head, &base->req_waiting_head, 1); 4050 } 4051 base->global_requests_inflight = base->global_requests_waiting = 0; 4052 4053 for (server = base->server_head; server; server = server_next) { 4054 server_next = server->next; 4055 /** already done something before */ 4056 server->probe_request = NULL; 4057 evdns_nameserver_free(server); 4058 if (server_next == base->server_head) 4059 break; 4060 } 4061 base->server_head = NULL; 4062 base->global_good_nameservers = 0; 4063 4064 if (base->global_search_state) { 4065 for (dom = base->global_search_state->head; dom; dom = dom_next) { 4066 dom_next = dom->next; 4067 mm_free(dom); 4068 } 4069 mm_free(base->global_search_state); 4070 base->global_search_state = NULL; 4071 } 4072 4073 { 4074 struct hosts_entry *victim; 4075 while ((victim = TAILQ_FIRST(&base->hostsdb))) { 4076 TAILQ_REMOVE(&base->hostsdb, victim, next); 4077 mm_free(victim); 4078 } 4079 } 4080 4081 mm_free(base->req_heads); 4082 4083 EVDNS_UNLOCK(base); 4084 EVTHREAD_FREE_LOCK(base->lock, EVTHREAD_LOCKTYPE_RECURSIVE); 4085 4086 mm_free(base); 4087 } 4088 4089 void 4090 evdns_base_free(struct evdns_base *base, int fail_requests) 4091 { 4092 EVDNS_LOCK(base); 4093 evdns_base_free_and_unlock(base, fail_requests); 4094 } 4095 4096 void 4097 evdns_base_clear_host_addresses(struct evdns_base *base) 4098 { 4099 struct hosts_entry *victim; 4100 EVDNS_LOCK(base); 4101 while ((victim = TAILQ_FIRST(&base->hostsdb))) { 4102 TAILQ_REMOVE(&base->hostsdb, victim, next); 4103 mm_free(victim); 4104 } 4105 EVDNS_UNLOCK(base); 4106 } 4107 4108 void 4109 evdns_shutdown(int fail_requests) 4110 { 4111 if (current_base) { 4112 struct evdns_base *b = current_base; 4113 current_base = NULL; 4114 evdns_base_free(b, fail_requests); 4115 } 4116 evdns_log_fn = NULL; 4117 } 4118 4119 static int 4120 evdns_base_parse_hosts_line(struct evdns_base *base, char *line) 4121 { 4122 char *strtok_state; 4123 static const char *const delims = " \t"; 4124 char *const addr = strtok_r(line, delims, &strtok_state); 4125 char *hostname, *hash; 4126 struct sockaddr_storage ss; 4127 int socklen = sizeof(ss); 4128 ASSERT_LOCKED(base); 4129 4130 #define NEXT_TOKEN strtok_r(NULL, delims, &strtok_state) 4131 4132 if (!addr || *addr == '#') 4133 return 0; 4134 4135 memset(&ss, 0, sizeof(ss)); 4136 if (evutil_parse_sockaddr_port(addr, (struct sockaddr*)&ss, &socklen)<0) 4137 return -1; 4138 if (socklen > (int)sizeof(struct sockaddr_in6)) 4139 return -1; 4140 4141 if (sockaddr_getport((struct sockaddr*)&ss)) 4142 return -1; 4143 4144 while ((hostname = NEXT_TOKEN)) { 4145 struct hosts_entry *he; 4146 size_t namelen; 4147 if ((hash = strchr(hostname, '#'))) { 4148 if (hash == hostname) 4149 return 0; 4150 *hash = '\0'; 4151 } 4152 4153 namelen = strlen(hostname); 4154 4155 he = mm_calloc(1, sizeof(struct hosts_entry)+namelen); 4156 if (!he) 4157 return -1; 4158 EVUTIL_ASSERT(socklen <= (int)sizeof(he->addr)); 4159 memcpy(&he->addr, &ss, socklen); 4160 memcpy(he->hostname, hostname, namelen+1); 4161 he->addrlen = socklen; 4162 4163 TAILQ_INSERT_TAIL(&base->hostsdb, he, next); 4164 4165 if (hash) 4166 return 0; 4167 } 4168 4169 return 0; 4170 #undef NEXT_TOKEN 4171 } 4172 4173 static int 4174 evdns_base_load_hosts_impl(struct evdns_base *base, const char *hosts_fname) 4175 { 4176 char *str=NULL, *cp, *eol; 4177 size_t len; 4178 int err=0; 4179 4180 ASSERT_LOCKED(base); 4181 4182 if (hosts_fname == NULL || 4183 (err = evutil_read_file_(hosts_fname, &str, &len, 0)) < 0) { 4184 char tmp[64]; 4185 strlcpy(tmp, "127.0.0.1 localhost", sizeof(tmp)); 4186 evdns_base_parse_hosts_line(base, tmp); 4187 strlcpy(tmp, "::1 localhost", sizeof(tmp)); 4188 evdns_base_parse_hosts_line(base, tmp); 4189 return err ? -1 : 0; 4190 } 4191 4192 /* This will break early if there is a NUL in the hosts file. 4193 * Probably not a problem.*/ 4194 cp = str; 4195 for (;;) { 4196 eol = strchr(cp, '\n'); 4197 4198 if (eol) { 4199 *eol = '\0'; 4200 evdns_base_parse_hosts_line(base, cp); 4201 cp = eol+1; 4202 } else { 4203 evdns_base_parse_hosts_line(base, cp); 4204 break; 4205 } 4206 } 4207 4208 mm_free(str); 4209 return 0; 4210 } 4211 4212 int 4213 evdns_base_load_hosts(struct evdns_base *base, const char *hosts_fname) 4214 { 4215 int res; 4216 if (!base) 4217 base = current_base; 4218 EVDNS_LOCK(base); 4219 res = evdns_base_load_hosts_impl(base, hosts_fname); 4220 EVDNS_UNLOCK(base); 4221 return res; 4222 } 4223 4224 /* A single request for a getaddrinfo, either v4 or v6. */ 4225 struct getaddrinfo_subrequest { 4226 struct evdns_request *r; 4227 ev_uint32_t type; 4228 }; 4229 4230 /* State data used to implement an in-progress getaddrinfo. */ 4231 struct evdns_getaddrinfo_request { 4232 struct evdns_base *evdns_base; 4233 /* Copy of the modified 'hints' data that we'll use to build 4234 * answers. */ 4235 struct evutil_addrinfo hints; 4236 /* The callback to invoke when we're done */ 4237 evdns_getaddrinfo_cb user_cb; 4238 /* User-supplied data to give to the callback. */ 4239 void *user_data; 4240 /* The port to use when building sockaddrs. */ 4241 ev_uint16_t port; 4242 /* The sub_request for an A record (if any) */ 4243 struct getaddrinfo_subrequest ipv4_request; 4244 /* The sub_request for an AAAA record (if any) */ 4245 struct getaddrinfo_subrequest ipv6_request; 4246 4247 /* The cname result that we were told (if any) */ 4248 char *cname_result; 4249 4250 /* If we have one request answered and one request still inflight, 4251 * then this field holds the answer from the first request... */ 4252 struct evutil_addrinfo *pending_result; 4253 /* And this event is a timeout that will tell us to cancel the second 4254 * request if it's taking a long time. */ 4255 struct event timeout; 4256 4257 /* And this field holds the error code from the first request... */ 4258 int pending_error; 4259 /* If this is set, the user canceled this request. */ 4260 unsigned user_canceled : 1; 4261 /* If this is set, the user can no longer cancel this request; we're 4262 * just waiting for the free. */ 4263 unsigned request_done : 1; 4264 }; 4265 4266 /* Convert an evdns errors to the equivalent getaddrinfo error. */ 4267 static int 4268 evdns_err_to_getaddrinfo_err(int e1) 4269 { 4270 /* XXX Do this better! */ 4271 if (e1 == DNS_ERR_NONE) 4272 return 0; 4273 else if (e1 == DNS_ERR_NOTEXIST) 4274 return EVUTIL_EAI_NONAME; 4275 else 4276 return EVUTIL_EAI_FAIL; 4277 } 4278 4279 /* Return the more informative of two getaddrinfo errors. */ 4280 static int 4281 getaddrinfo_merge_err(int e1, int e2) 4282 { 4283 /* XXXX be cleverer here. */ 4284 if (e1 == 0) 4285 return e2; 4286 else 4287 return e1; 4288 } 4289 4290 static void 4291 free_getaddrinfo_request(struct evdns_getaddrinfo_request *data) 4292 { 4293 /* DO NOT CALL this if either of the requests is pending. Only once 4294 * both callbacks have been invoked is it safe to free the request */ 4295 if (data->pending_result) 4296 evutil_freeaddrinfo(data->pending_result); 4297 if (data->cname_result) 4298 mm_free(data->cname_result); 4299 event_del(&data->timeout); 4300 mm_free(data); 4301 return; 4302 } 4303 4304 static void 4305 add_cname_to_reply(struct evdns_getaddrinfo_request *data, 4306 struct evutil_addrinfo *ai) 4307 { 4308 if (data->cname_result && ai) { 4309 ai->ai_canonname = data->cname_result; 4310 data->cname_result = NULL; 4311 } 4312 } 4313 4314 /* Callback: invoked when one request in a mixed-format A/AAAA getaddrinfo 4315 * request has finished, but the other one took too long to answer. Pass 4316 * along the answer we got, and cancel the other request. 4317 */ 4318 static void 4319 evdns_getaddrinfo_timeout_cb(evutil_socket_t fd, short what, void *ptr) 4320 { 4321 int v4_timedout = 0, v6_timedout = 0; 4322 struct evdns_getaddrinfo_request *data = ptr; 4323 4324 /* Cancel any pending requests, and note which one */ 4325 if (data->ipv4_request.r) { 4326 /* XXXX This does nothing if the request's callback is already 4327 * running (pending_cb is set). */ 4328 evdns_cancel_request(NULL, data->ipv4_request.r); 4329 v4_timedout = 1; 4330 EVDNS_LOCK(data->evdns_base); 4331 ++data->evdns_base->getaddrinfo_ipv4_timeouts; 4332 EVDNS_UNLOCK(data->evdns_base); 4333 } 4334 if (data->ipv6_request.r) { 4335 /* XXXX This does nothing if the request's callback is already 4336 * running (pending_cb is set). */ 4337 evdns_cancel_request(NULL, data->ipv6_request.r); 4338 v6_timedout = 1; 4339 EVDNS_LOCK(data->evdns_base); 4340 ++data->evdns_base->getaddrinfo_ipv6_timeouts; 4341 EVDNS_UNLOCK(data->evdns_base); 4342 } 4343 4344 /* We only use this timeout callback when we have an answer for 4345 * one address. */ 4346 EVUTIL_ASSERT(!v4_timedout || !v6_timedout); 4347 4348 /* Report the outcome of the other request that didn't time out. */ 4349 if (data->pending_result) { 4350 add_cname_to_reply(data, data->pending_result); 4351 data->user_cb(0, data->pending_result, data->user_data); 4352 data->pending_result = NULL; 4353 } else { 4354 int e = data->pending_error; 4355 if (!e) 4356 e = EVUTIL_EAI_AGAIN; 4357 data->user_cb(e, NULL, data->user_data); 4358 } 4359 4360 data->user_cb = NULL; /* prevent double-call if evdns callbacks are 4361 * in-progress. XXXX It would be better if this 4362 * weren't necessary. */ 4363 4364 if (!v4_timedout && !v6_timedout) { 4365 /* should be impossible? XXXX */ 4366 free_getaddrinfo_request(data); 4367 } 4368 } 4369 4370 static int 4371 evdns_getaddrinfo_set_timeout(struct evdns_base *evdns_base, 4372 struct evdns_getaddrinfo_request *data) 4373 { 4374 return event_add(&data->timeout, &evdns_base->global_getaddrinfo_allow_skew); 4375 } 4376 4377 static inline int 4378 evdns_result_is_answer(int result) 4379 { 4380 return (result != DNS_ERR_NOTIMPL && result != DNS_ERR_REFUSED && 4381 result != DNS_ERR_SERVERFAILED && result != DNS_ERR_CANCEL); 4382 } 4383 4384 static void 4385 evdns_getaddrinfo_gotresolve(int result, char type, int count, 4386 int ttl, void *addresses, void *arg) 4387 { 4388 int i; 4389 struct getaddrinfo_subrequest *req = arg; 4390 struct getaddrinfo_subrequest *other_req; 4391 struct evdns_getaddrinfo_request *data; 4392 4393 struct evutil_addrinfo *res; 4394 4395 struct sockaddr_in sin; 4396 struct sockaddr_in6 sin6; 4397 struct sockaddr *sa; 4398 int socklen, addrlen; 4399 void *addrp; 4400 int err; 4401 int user_canceled; 4402 4403 EVUTIL_ASSERT(req->type == DNS_IPv4_A || req->type == DNS_IPv6_AAAA); 4404 if (req->type == DNS_IPv4_A) { 4405 data = EVUTIL_UPCAST(req, struct evdns_getaddrinfo_request, ipv4_request); 4406 other_req = &data->ipv6_request; 4407 } else { 4408 data = EVUTIL_UPCAST(req, struct evdns_getaddrinfo_request, ipv6_request); 4409 other_req = &data->ipv4_request; 4410 } 4411 4412 /** Called from evdns_base_free() with @fail_requests == 1 */ 4413 if (result != DNS_ERR_SHUTDOWN) { 4414 EVDNS_LOCK(data->evdns_base); 4415 if (evdns_result_is_answer(result)) { 4416 if (req->type == DNS_IPv4_A) 4417 ++data->evdns_base->getaddrinfo_ipv4_answered; 4418 else 4419 ++data->evdns_base->getaddrinfo_ipv6_answered; 4420 } 4421 user_canceled = data->user_canceled; 4422 if (other_req->r == NULL) 4423 data->request_done = 1; 4424 EVDNS_UNLOCK(data->evdns_base); 4425 } else { 4426 data->evdns_base = NULL; 4427 user_canceled = data->user_canceled; 4428 } 4429 4430 req->r = NULL; 4431 4432 if (result == DNS_ERR_CANCEL && ! user_canceled) { 4433 /* Internal cancel request from timeout or internal error. 4434 * we already answered the user. */ 4435 if (other_req->r == NULL) 4436 free_getaddrinfo_request(data); 4437 return; 4438 } 4439 4440 if (data->user_cb == NULL) { 4441 /* We already answered. XXXX This shouldn't be needed; see 4442 * comments in evdns_getaddrinfo_timeout_cb */ 4443 free_getaddrinfo_request(data); 4444 return; 4445 } 4446 4447 if (result == DNS_ERR_NONE) { 4448 if (count == 0) 4449 err = EVUTIL_EAI_NODATA; 4450 else 4451 err = 0; 4452 } else { 4453 err = evdns_err_to_getaddrinfo_err(result); 4454 } 4455 4456 if (err) { 4457 /* Looks like we got an error. */ 4458 if (other_req->r) { 4459 /* The other request is still working; maybe it will 4460 * succeed. */ 4461 /* XXXX handle failure from set_timeout */ 4462 if (result != DNS_ERR_SHUTDOWN) { 4463 evdns_getaddrinfo_set_timeout(data->evdns_base, data); 4464 } 4465 data->pending_error = err; 4466 return; 4467 } 4468 4469 if (user_canceled) { 4470 data->user_cb(EVUTIL_EAI_CANCEL, NULL, data->user_data); 4471 } else if (data->pending_result) { 4472 /* If we have an answer waiting, and we weren't 4473 * canceled, ignore this error. */ 4474 add_cname_to_reply(data, data->pending_result); 4475 data->user_cb(0, data->pending_result, data->user_data); 4476 data->pending_result = NULL; 4477 } else { 4478 if (data->pending_error) 4479 err = getaddrinfo_merge_err(err, 4480 data->pending_error); 4481 data->user_cb(err, NULL, data->user_data); 4482 } 4483 free_getaddrinfo_request(data); 4484 return; 4485 } else if (user_canceled) { 4486 if (other_req->r) { 4487 /* The other request is still working; let it hit this 4488 * callback with EVUTIL_EAI_CANCEL callback and report 4489 * the failure. */ 4490 return; 4491 } 4492 data->user_cb(EVUTIL_EAI_CANCEL, NULL, data->user_data); 4493 free_getaddrinfo_request(data); 4494 return; 4495 } 4496 4497 /* Looks like we got some answers. We should turn them into addrinfos 4498 * and then either queue those or return them all. */ 4499 EVUTIL_ASSERT(type == DNS_IPv4_A || type == DNS_IPv6_AAAA); 4500 4501 if (type == DNS_IPv4_A) { 4502 memset(&sin, 0, sizeof(sin)); 4503 sin.sin_family = AF_INET; 4504 sin.sin_port = htons(data->port); 4505 4506 sa = (struct sockaddr *)&sin; 4507 socklen = sizeof(sin); 4508 addrlen = 4; 4509 addrp = &sin.sin_addr.s_addr; 4510 } else { 4511 memset(&sin6, 0, sizeof(sin6)); 4512 sin6.sin6_family = AF_INET6; 4513 sin6.sin6_port = htons(data->port); 4514 4515 sa = (struct sockaddr *)&sin6; 4516 socklen = sizeof(sin6); 4517 addrlen = 16; 4518 addrp = &sin6.sin6_addr.s6_addr; 4519 } 4520 4521 res = NULL; 4522 for (i=0; i < count; ++i) { 4523 struct evutil_addrinfo *ai; 4524 memcpy(addrp, ((char*)addresses)+i*addrlen, addrlen); 4525 ai = evutil_new_addrinfo_(sa, socklen, &data->hints); 4526 if (!ai) { 4527 if (other_req->r) { 4528 evdns_cancel_request(NULL, other_req->r); 4529 } 4530 data->user_cb(EVUTIL_EAI_MEMORY, NULL, data->user_data); 4531 if (res) 4532 evutil_freeaddrinfo(res); 4533 4534 if (other_req->r == NULL) 4535 free_getaddrinfo_request(data); 4536 return; 4537 } 4538 res = evutil_addrinfo_append_(res, ai); 4539 } 4540 4541 if (other_req->r) { 4542 /* The other request is still in progress; wait for it */ 4543 /* XXXX handle failure from set_timeout */ 4544 evdns_getaddrinfo_set_timeout(data->evdns_base, data); 4545 data->pending_result = res; 4546 return; 4547 } else { 4548 /* The other request is done or never started; append its 4549 * results (if any) and return them. */ 4550 if (data->pending_result) { 4551 if (req->type == DNS_IPv4_A) 4552 res = evutil_addrinfo_append_(res, 4553 data->pending_result); 4554 else 4555 res = evutil_addrinfo_append_( 4556 data->pending_result, res); 4557 data->pending_result = NULL; 4558 } 4559 4560 /* Call the user callback. */ 4561 add_cname_to_reply(data, res); 4562 data->user_cb(0, res, data->user_data); 4563 4564 /* Free data. */ 4565 free_getaddrinfo_request(data); 4566 } 4567 } 4568 4569 static struct hosts_entry * 4570 find_hosts_entry(struct evdns_base *base, const char *hostname, 4571 struct hosts_entry *find_after) 4572 { 4573 struct hosts_entry *e; 4574 4575 if (find_after) 4576 e = TAILQ_NEXT(find_after, next); 4577 else 4578 e = TAILQ_FIRST(&base->hostsdb); 4579 4580 for (; e; e = TAILQ_NEXT(e, next)) { 4581 if (!evutil_ascii_strcasecmp(e->hostname, hostname)) 4582 return e; 4583 } 4584 return NULL; 4585 } 4586 4587 static int 4588 evdns_getaddrinfo_fromhosts(struct evdns_base *base, 4589 const char *nodename, struct evutil_addrinfo *hints, ev_uint16_t port, 4590 struct evutil_addrinfo **res) 4591 { 4592 int n_found = 0; 4593 struct hosts_entry *e; 4594 struct evutil_addrinfo *ai=NULL; 4595 int f = hints->ai_family; 4596 4597 EVDNS_LOCK(base); 4598 for (e = find_hosts_entry(base, nodename, NULL); e; 4599 e = find_hosts_entry(base, nodename, e)) { 4600 struct evutil_addrinfo *ai_new; 4601 ++n_found; 4602 if ((e->addr.sa.sa_family == AF_INET && f == PF_INET6) || 4603 (e->addr.sa.sa_family == AF_INET6 && f == PF_INET)) 4604 continue; 4605 ai_new = evutil_new_addrinfo_(&e->addr.sa, e->addrlen, hints); 4606 if (!ai_new) { 4607 n_found = 0; 4608 goto out; 4609 } 4610 sockaddr_setport(ai_new->ai_addr, port); 4611 ai = evutil_addrinfo_append_(ai, ai_new); 4612 } 4613 EVDNS_UNLOCK(base); 4614 out: 4615 if (n_found) { 4616 /* Note that we return an empty answer if we found entries for 4617 * this hostname but none were of the right address type. */ 4618 *res = ai; 4619 return 0; 4620 } else { 4621 if (ai) 4622 evutil_freeaddrinfo(ai); 4623 return -1; 4624 } 4625 } 4626 4627 struct evdns_getaddrinfo_request * 4628 evdns_getaddrinfo(struct evdns_base *dns_base, 4629 const char *nodename, const char *servname, 4630 const struct evutil_addrinfo *hints_in, 4631 evdns_getaddrinfo_cb cb, void *arg) 4632 { 4633 struct evdns_getaddrinfo_request *data; 4634 struct evutil_addrinfo hints; 4635 struct evutil_addrinfo *res = NULL; 4636 int err; 4637 int port = 0; 4638 int want_cname = 0; 4639 4640 if (!dns_base) { 4641 dns_base = current_base; 4642 if (!dns_base) { 4643 log(EVDNS_LOG_WARN, 4644 "Call to getaddrinfo_async with no " 4645 "evdns_base configured."); 4646 cb(EVUTIL_EAI_FAIL, NULL, arg); /* ??? better error? */ 4647 return NULL; 4648 } 4649 } 4650 4651 /* If we _must_ answer this immediately, do so. */ 4652 if ((hints_in && (hints_in->ai_flags & EVUTIL_AI_NUMERICHOST))) { 4653 res = NULL; 4654 err = evutil_getaddrinfo(nodename, servname, hints_in, &res); 4655 cb(err, res, arg); 4656 return NULL; 4657 } 4658 4659 if (hints_in) { 4660 memcpy(&hints, hints_in, sizeof(hints)); 4661 } else { 4662 memset(&hints, 0, sizeof(hints)); 4663 hints.ai_family = PF_UNSPEC; 4664 } 4665 4666 evutil_adjust_hints_for_addrconfig_(&hints); 4667 4668 /* Now try to see if we _can_ answer immediately. */ 4669 /* (It would be nice to do this by calling getaddrinfo directly, with 4670 * AI_NUMERICHOST, on plaforms that have it, but we can't: there isn't 4671 * a reliable way to distinguish the "that wasn't a numeric host!" case 4672 * from any other EAI_NONAME cases.) */ 4673 err = evutil_getaddrinfo_common_(nodename, servname, &hints, &res, &port); 4674 if (err != EVUTIL_EAI_NEED_RESOLVE) { 4675 cb(err, res, arg); 4676 return NULL; 4677 } 4678 4679 /* If there is an entry in the hosts file, we should give it now. */ 4680 if (!evdns_getaddrinfo_fromhosts(dns_base, nodename, &hints, port, &res)) { 4681 cb(0, res, arg); 4682 return NULL; 4683 } 4684 4685 /* Okay, things are serious now. We're going to need to actually 4686 * launch a request. 4687 */ 4688 data = mm_calloc(1,sizeof(struct evdns_getaddrinfo_request)); 4689 if (!data) { 4690 cb(EVUTIL_EAI_MEMORY, NULL, arg); 4691 return NULL; 4692 } 4693 4694 memcpy(&data->hints, &hints, sizeof(data->hints)); 4695 data->port = (ev_uint16_t)port; 4696 data->ipv4_request.type = DNS_IPv4_A; 4697 data->ipv6_request.type = DNS_IPv6_AAAA; 4698 data->user_cb = cb; 4699 data->user_data = arg; 4700 data->evdns_base = dns_base; 4701 4702 want_cname = (hints.ai_flags & EVUTIL_AI_CANONNAME); 4703 4704 /* If we are asked for a PF_UNSPEC address, we launch two requests in 4705 * parallel: one for an A address and one for an AAAA address. We 4706 * can't send just one request, since many servers only answer one 4707 * question per DNS request. 4708 * 4709 * Once we have the answer to one request, we allow for a short 4710 * timeout before we report it, to see if the other one arrives. If 4711 * they both show up in time, then we report both the answers. 4712 * 4713 * If too many addresses of one type time out or fail, we should stop 4714 * launching those requests. (XXX we don't do that yet.) 4715 */ 4716 4717 if (hints.ai_family != PF_INET6) { 4718 log(EVDNS_LOG_DEBUG, "Sending request for %s on ipv4 as %p", 4719 nodename, &data->ipv4_request); 4720 4721 data->ipv4_request.r = evdns_base_resolve_ipv4(dns_base, 4722 nodename, 0, evdns_getaddrinfo_gotresolve, 4723 &data->ipv4_request); 4724 if (want_cname && data->ipv4_request.r) 4725 data->ipv4_request.r->current_req->put_cname_in_ptr = 4726 &data->cname_result; 4727 } 4728 if (hints.ai_family != PF_INET) { 4729 log(EVDNS_LOG_DEBUG, "Sending request for %s on ipv6 as %p", 4730 nodename, &data->ipv6_request); 4731 4732 data->ipv6_request.r = evdns_base_resolve_ipv6(dns_base, 4733 nodename, 0, evdns_getaddrinfo_gotresolve, 4734 &data->ipv6_request); 4735 if (want_cname && data->ipv6_request.r) 4736 data->ipv6_request.r->current_req->put_cname_in_ptr = 4737 &data->cname_result; 4738 } 4739 4740 evtimer_assign(&data->timeout, dns_base->event_base, 4741 evdns_getaddrinfo_timeout_cb, data); 4742 4743 if (data->ipv4_request.r || data->ipv6_request.r) { 4744 return data; 4745 } else { 4746 mm_free(data); 4747 cb(EVUTIL_EAI_FAIL, NULL, arg); 4748 return NULL; 4749 } 4750 } 4751 4752 void 4753 evdns_getaddrinfo_cancel(struct evdns_getaddrinfo_request *data) 4754 { 4755 EVDNS_LOCK(data->evdns_base); 4756 if (data->request_done) { 4757 EVDNS_UNLOCK(data->evdns_base); 4758 return; 4759 } 4760 event_del(&data->timeout); 4761 data->user_canceled = 1; 4762 if (data->ipv4_request.r) 4763 evdns_cancel_request(data->evdns_base, data->ipv4_request.r); 4764 if (data->ipv6_request.r) 4765 evdns_cancel_request(data->evdns_base, data->ipv6_request.r); 4766 EVDNS_UNLOCK(data->evdns_base); 4767 } 4768