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 if (j >= length) return -1; 980 GET8(label_len); 981 if (!label_len) break; 982 if (label_len & 0xc0) { 983 u8 ptr_low; 984 GET8(ptr_low); 985 if (name_end < 0) name_end = j; 986 j = (((int)label_len & 0x3f) << 8) + ptr_low; 987 /* Make sure that the target offset is in-bounds. */ 988 if (j < 0 || j >= length) return -1; 989 /* If we've jumped more times than there are characters in the 990 * message, we must have a loop. */ 991 if (++ptr_count > length) return -1; 992 continue; 993 } 994 if (label_len > 63) return -1; 995 if (cp != name_out) { 996 if (cp + 1 >= end) return -1; 997 *cp++ = '.'; 998 } 999 if (cp + label_len >= end) 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 #define TEST_NAME \ 1064 do { tmp_name[0] = '\0'; \ 1065 cmp_name[0] = '\0'; \ 1066 k = j; \ 1067 if (name_parse(packet, length, &j, tmp_name, \ 1068 sizeof(tmp_name))<0) \ 1069 goto err; \ 1070 if (name_parse(req->request, req->request_len, &k, \ 1071 cmp_name, sizeof(cmp_name))<0) \ 1072 goto err; \ 1073 if (base->global_randomize_case) { \ 1074 if (strcmp(tmp_name, cmp_name) == 0) \ 1075 name_matches = 1; \ 1076 } else { \ 1077 if (evutil_ascii_strcasecmp(tmp_name, cmp_name) == 0) \ 1078 name_matches = 1; \ 1079 } \ 1080 } while (0) 1081 1082 reply.type = req->request_type; 1083 1084 /* skip over each question in the reply */ 1085 for (i = 0; i < questions; ++i) { 1086 /* the question looks like 1087 * <label:name><u16:type><u16:class> 1088 */ 1089 TEST_NAME; 1090 j += 4; 1091 if (j > length) goto err; 1092 } 1093 1094 if (!name_matches) 1095 goto err; 1096 1097 /* now we have the answer section which looks like 1098 * <label:name><u16:type><u16:class><u32:ttl><u16:len><data...> 1099 */ 1100 1101 for (i = 0; i < answers; ++i) { 1102 u16 type, class; 1103 1104 SKIP_NAME; 1105 GET16(type); 1106 GET16(class); 1107 GET32(ttl); 1108 GET16(datalength); 1109 1110 if (type == TYPE_A && class == CLASS_INET) { 1111 int addrcount, addrtocopy; 1112 if (req->request_type != TYPE_A) { 1113 j += datalength; continue; 1114 } 1115 if ((datalength & 3) != 0) /* not an even number of As. */ 1116 goto err; 1117 addrcount = datalength >> 2; 1118 addrtocopy = MIN(MAX_V4_ADDRS - reply.data.a.addrcount, (unsigned)addrcount); 1119 1120 ttl_r = MIN(ttl_r, ttl); 1121 /* we only bother with the first four addresses. */ 1122 if (j + 4*addrtocopy > length) goto err; 1123 memcpy(&reply.data.a.addresses[reply.data.a.addrcount], 1124 packet + j, 4*addrtocopy); 1125 j += 4*addrtocopy; 1126 reply.data.a.addrcount += addrtocopy; 1127 reply.have_answer = 1; 1128 if (reply.data.a.addrcount == MAX_V4_ADDRS) break; 1129 } else if (type == TYPE_PTR && class == CLASS_INET) { 1130 if (req->request_type != TYPE_PTR) { 1131 j += datalength; continue; 1132 } 1133 if (name_parse(packet, length, &j, reply.data.ptr.name, 1134 sizeof(reply.data.ptr.name))<0) 1135 goto err; 1136 ttl_r = MIN(ttl_r, ttl); 1137 reply.have_answer = 1; 1138 break; 1139 } else if (type == TYPE_CNAME) { 1140 char cname[HOST_NAME_MAX]; 1141 if (!req->put_cname_in_ptr || *req->put_cname_in_ptr) { 1142 j += datalength; continue; 1143 } 1144 if (name_parse(packet, length, &j, cname, 1145 sizeof(cname))<0) 1146 goto err; 1147 *req->put_cname_in_ptr = mm_strdup(cname); 1148 } else if (type == TYPE_AAAA && class == CLASS_INET) { 1149 int addrcount, addrtocopy; 1150 if (req->request_type != TYPE_AAAA) { 1151 j += datalength; continue; 1152 } 1153 if ((datalength & 15) != 0) /* not an even number of AAAAs. */ 1154 goto err; 1155 addrcount = datalength >> 4; /* each address is 16 bytes long */ 1156 addrtocopy = MIN(MAX_V6_ADDRS - reply.data.aaaa.addrcount, (unsigned)addrcount); 1157 ttl_r = MIN(ttl_r, ttl); 1158 1159 /* we only bother with the first four addresses. */ 1160 if (j + 16*addrtocopy > length) goto err; 1161 memcpy(&reply.data.aaaa.addresses[reply.data.aaaa.addrcount], 1162 packet + j, 16*addrtocopy); 1163 reply.data.aaaa.addrcount += addrtocopy; 1164 j += 16*addrtocopy; 1165 reply.have_answer = 1; 1166 if (reply.data.aaaa.addrcount == MAX_V6_ADDRS) break; 1167 } else { 1168 /* skip over any other type of resource */ 1169 j += datalength; 1170 } 1171 } 1172 1173 if (!reply.have_answer) { 1174 for (i = 0; i < authority; ++i) { 1175 u16 type, class; 1176 SKIP_NAME; 1177 GET16(type); 1178 GET16(class); 1179 GET32(ttl); 1180 GET16(datalength); 1181 if (type == TYPE_SOA && class == CLASS_INET) { 1182 u32 serial, refresh, retry, expire, minimum; 1183 SKIP_NAME; 1184 SKIP_NAME; 1185 GET32(serial); 1186 GET32(refresh); 1187 GET32(retry); 1188 GET32(expire); 1189 GET32(minimum); 1190 (void)expire; 1191 (void)retry; 1192 (void)refresh; 1193 (void)serial; 1194 ttl_r = MIN(ttl_r, ttl); 1195 ttl_r = MIN(ttl_r, minimum); 1196 } else { 1197 /* skip over any other type of resource */ 1198 j += datalength; 1199 } 1200 } 1201 } 1202 1203 if (ttl_r == 0xffffffff) 1204 ttl_r = 0; 1205 1206 reply_handle(req, flags, ttl_r, &reply); 1207 return 0; 1208 err: 1209 if (req) 1210 reply_handle(req, flags, 0, NULL); 1211 return -1; 1212 } 1213 1214 /* Parse a raw request (packet,length) sent to a nameserver port (port) from */ 1215 /* a DNS client (addr,addrlen), and if it's well-formed, call the corresponding */ 1216 /* callback. */ 1217 static int 1218 request_parse(u8 *packet, int length, struct evdns_server_port *port, struct sockaddr *addr, ev_socklen_t addrlen) 1219 { 1220 int j = 0; /* index into packet */ 1221 u16 t_; /* used by the macros */ 1222 char tmp_name[256]; /* used by the macros */ 1223 1224 int i; 1225 u16 trans_id, flags, questions, answers, authority, additional; 1226 struct server_request *server_req = NULL; 1227 1228 ASSERT_LOCKED(port); 1229 1230 /* Get the header fields */ 1231 GET16(trans_id); 1232 GET16(flags); 1233 GET16(questions); 1234 GET16(answers); 1235 GET16(authority); 1236 GET16(additional); 1237 (void)answers; 1238 (void)additional; 1239 (void)authority; 1240 1241 if (flags & 0x8000) return -1; /* Must not be an answer. */ 1242 flags &= 0x0110; /* Only RD and CD get preserved. */ 1243 1244 server_req = mm_malloc(sizeof(struct server_request)); 1245 if (server_req == NULL) return -1; 1246 memset(server_req, 0, sizeof(struct server_request)); 1247 1248 server_req->trans_id = trans_id; 1249 memcpy(&server_req->addr, addr, addrlen); 1250 server_req->addrlen = addrlen; 1251 1252 server_req->base.flags = flags; 1253 server_req->base.nquestions = 0; 1254 server_req->base.questions = mm_calloc(sizeof(struct evdns_server_question *), questions); 1255 if (server_req->base.questions == NULL) 1256 goto err; 1257 1258 for (i = 0; i < questions; ++i) { 1259 u16 type, class; 1260 struct evdns_server_question *q; 1261 int namelen; 1262 if (name_parse(packet, length, &j, tmp_name, sizeof(tmp_name))<0) 1263 goto err; 1264 GET16(type); 1265 GET16(class); 1266 namelen = (int)strlen(tmp_name); 1267 q = mm_malloc(sizeof(struct evdns_server_question) + namelen); 1268 if (!q) 1269 goto err; 1270 q->type = type; 1271 q->dns_question_class = class; 1272 memcpy(q->name, tmp_name, namelen+1); 1273 server_req->base.questions[server_req->base.nquestions++] = q; 1274 } 1275 1276 /* Ignore answers, authority, and additional. */ 1277 1278 server_req->port = port; 1279 port->refcnt++; 1280 1281 /* Only standard queries are supported. */ 1282 if (flags & 0x7800) { 1283 evdns_server_request_respond(&(server_req->base), DNS_ERR_NOTIMPL); 1284 return -1; 1285 } 1286 1287 port->user_callback(&(server_req->base), port->user_data); 1288 1289 return 0; 1290 err: 1291 if (server_req) { 1292 if (server_req->base.questions) { 1293 for (i = 0; i < server_req->base.nquestions; ++i) 1294 mm_free(server_req->base.questions[i]); 1295 mm_free(server_req->base.questions); 1296 } 1297 mm_free(server_req); 1298 } 1299 return -1; 1300 1301 #undef SKIP_NAME 1302 #undef GET32 1303 #undef GET16 1304 #undef GET8 1305 } 1306 1307 1308 void 1309 evdns_set_transaction_id_fn(ev_uint16_t (*fn)(void)) 1310 { 1311 } 1312 1313 void 1314 evdns_set_random_bytes_fn(void (*fn)(char *, size_t)) 1315 { 1316 } 1317 1318 /* Try to choose a strong transaction id which isn't already in flight */ 1319 static u16 1320 transaction_id_pick(struct evdns_base *base) { 1321 ASSERT_LOCKED(base); 1322 for (;;) { 1323 u16 trans_id; 1324 evutil_secure_rng_get_bytes(&trans_id, sizeof(trans_id)); 1325 1326 if (trans_id == 0xffff) continue; 1327 /* now check to see if that id is already inflight */ 1328 if (request_find_from_trans_id(base, trans_id) == NULL) 1329 return trans_id; 1330 } 1331 } 1332 1333 /* choose a namesever to use. This function will try to ignore */ 1334 /* nameservers which we think are down and load balance across the rest */ 1335 /* by updating the server_head global each time. */ 1336 static struct nameserver * 1337 nameserver_pick(struct evdns_base *base) { 1338 struct nameserver *started_at = base->server_head, *picked; 1339 ASSERT_LOCKED(base); 1340 if (!base->server_head) return NULL; 1341 1342 /* if we don't have any good nameservers then there's no */ 1343 /* point in trying to find one. */ 1344 if (!base->global_good_nameservers) { 1345 base->server_head = base->server_head->next; 1346 return base->server_head; 1347 } 1348 1349 /* remember that nameservers are in a circular list */ 1350 for (;;) { 1351 if (base->server_head->state) { 1352 /* we think this server is currently good */ 1353 picked = base->server_head; 1354 base->server_head = base->server_head->next; 1355 return picked; 1356 } 1357 1358 base->server_head = base->server_head->next; 1359 if (base->server_head == started_at) { 1360 /* all the nameservers seem to be down */ 1361 /* so we just return this one and hope for the */ 1362 /* best */ 1363 EVUTIL_ASSERT(base->global_good_nameservers == 0); 1364 picked = base->server_head; 1365 base->server_head = base->server_head->next; 1366 return picked; 1367 } 1368 } 1369 } 1370 1371 /* this is called when a namesever socket is ready for reading */ 1372 static void 1373 nameserver_read(struct nameserver *ns) { 1374 struct sockaddr_storage ss; 1375 ev_socklen_t addrlen = sizeof(ss); 1376 u8 packet[1500]; 1377 char addrbuf[128]; 1378 ASSERT_LOCKED(ns->base); 1379 1380 for (;;) { 1381 const int r = recvfrom(ns->socket, (void*)packet, 1382 sizeof(packet), 0, 1383 (struct sockaddr*)&ss, &addrlen); 1384 if (r < 0) { 1385 int err = evutil_socket_geterror(ns->socket); 1386 if (EVUTIL_ERR_RW_RETRIABLE(err)) 1387 return; 1388 nameserver_failed(ns, 1389 evutil_socket_error_to_string(err)); 1390 return; 1391 } 1392 if (evutil_sockaddr_cmp((struct sockaddr*)&ss, 1393 (struct sockaddr*)&ns->address, 0)) { 1394 log(EVDNS_LOG_WARN, "Address mismatch on received " 1395 "DNS packet. Apparent source was %s", 1396 evutil_format_sockaddr_port_( 1397 (struct sockaddr *)&ss, 1398 addrbuf, sizeof(addrbuf))); 1399 return; 1400 } 1401 1402 ns->timedout = 0; 1403 reply_parse(ns->base, packet, r); 1404 } 1405 } 1406 1407 /* Read a packet from a DNS client on a server port s, parse it, and */ 1408 /* act accordingly. */ 1409 static void 1410 server_port_read(struct evdns_server_port *s) { 1411 u8 packet[1500]; 1412 struct sockaddr_storage addr; 1413 ev_socklen_t addrlen; 1414 int r; 1415 ASSERT_LOCKED(s); 1416 1417 for (;;) { 1418 addrlen = sizeof(struct sockaddr_storage); 1419 r = recvfrom(s->socket, (void*)packet, sizeof(packet), 0, 1420 (struct sockaddr*) &addr, &addrlen); 1421 if (r < 0) { 1422 int err = evutil_socket_geterror(s->socket); 1423 if (EVUTIL_ERR_RW_RETRIABLE(err)) 1424 return; 1425 log(EVDNS_LOG_WARN, 1426 "Error %s (%d) while reading request.", 1427 evutil_socket_error_to_string(err), err); 1428 return; 1429 } 1430 request_parse(packet, r, s, (struct sockaddr*) &addr, addrlen); 1431 } 1432 } 1433 1434 /* Try to write all pending replies on a given DNS server port. */ 1435 static void 1436 server_port_flush(struct evdns_server_port *port) 1437 { 1438 struct server_request *req = port->pending_replies; 1439 ASSERT_LOCKED(port); 1440 while (req) { 1441 int r = sendto(port->socket, req->response, (int)req->response_len, 0, 1442 (struct sockaddr*) &req->addr, (ev_socklen_t)req->addrlen); 1443 if (r < 0) { 1444 int err = evutil_socket_geterror(port->socket); 1445 if (EVUTIL_ERR_RW_RETRIABLE(err)) 1446 return; 1447 log(EVDNS_LOG_WARN, "Error %s (%d) while writing response to port; dropping", evutil_socket_error_to_string(err), err); 1448 } 1449 if (server_request_free(req)) { 1450 /* we released the last reference to req->port. */ 1451 return; 1452 } else { 1453 EVUTIL_ASSERT(req != port->pending_replies); 1454 req = port->pending_replies; 1455 } 1456 } 1457 1458 /* We have no more pending requests; stop listening for 'writeable' events. */ 1459 (void) event_del(&port->event); 1460 event_assign(&port->event, port->event_base, 1461 port->socket, EV_READ | EV_PERSIST, 1462 server_port_ready_callback, port); 1463 1464 if (event_add(&port->event, NULL) < 0) { 1465 log(EVDNS_LOG_WARN, "Error from libevent when adding event for DNS server."); 1466 /* ???? Do more? */ 1467 } 1468 } 1469 1470 /* set if we are waiting for the ability to write to this server. */ 1471 /* if waiting is true then we ask libevent for EV_WRITE events, otherwise */ 1472 /* we stop these events. */ 1473 static void 1474 nameserver_write_waiting(struct nameserver *ns, char waiting) { 1475 ASSERT_LOCKED(ns->base); 1476 if (ns->write_waiting == waiting) return; 1477 1478 ns->write_waiting = waiting; 1479 (void) event_del(&ns->event); 1480 event_assign(&ns->event, ns->base->event_base, 1481 ns->socket, EV_READ | (waiting ? EV_WRITE : 0) | EV_PERSIST, 1482 nameserver_ready_callback, ns); 1483 if (event_add(&ns->event, NULL) < 0) { 1484 char addrbuf[128]; 1485 log(EVDNS_LOG_WARN, "Error from libevent when adding event for %s", 1486 evutil_format_sockaddr_port_( 1487 (struct sockaddr *)&ns->address, 1488 addrbuf, sizeof(addrbuf))); 1489 /* ???? Do more? */ 1490 } 1491 } 1492 1493 /* a callback function. Called by libevent when the kernel says that */ 1494 /* a nameserver socket is ready for writing or reading */ 1495 static void 1496 nameserver_ready_callback(evutil_socket_t fd, short events, void *arg) { 1497 struct nameserver *ns = (struct nameserver *) arg; 1498 (void)fd; 1499 1500 EVDNS_LOCK(ns->base); 1501 if (events & EV_WRITE) { 1502 ns->choked = 0; 1503 if (!evdns_transmit(ns->base)) { 1504 nameserver_write_waiting(ns, 0); 1505 } 1506 } 1507 if (events & EV_READ) { 1508 nameserver_read(ns); 1509 } 1510 EVDNS_UNLOCK(ns->base); 1511 } 1512 1513 /* a callback function. Called by libevent when the kernel says that */ 1514 /* a server socket is ready for writing or reading. */ 1515 static void 1516 server_port_ready_callback(evutil_socket_t fd, short events, void *arg) { 1517 struct evdns_server_port *port = (struct evdns_server_port *) arg; 1518 (void) fd; 1519 1520 EVDNS_LOCK(port); 1521 if (events & EV_WRITE) { 1522 port->choked = 0; 1523 server_port_flush(port); 1524 } 1525 if (events & EV_READ) { 1526 server_port_read(port); 1527 } 1528 EVDNS_UNLOCK(port); 1529 } 1530 1531 /* This is an inefficient representation; only use it via the dnslabel_table_* 1532 * functions, so that is can be safely replaced with something smarter later. */ 1533 #define MAX_LABELS 128 1534 /* Structures used to implement name compression */ 1535 struct dnslabel_entry { char *v; off_t pos; }; 1536 struct dnslabel_table { 1537 int n_labels; /* number of current entries */ 1538 /* map from name to position in message */ 1539 struct dnslabel_entry labels[MAX_LABELS]; 1540 }; 1541 1542 /* Initialize dnslabel_table. */ 1543 static void 1544 dnslabel_table_init(struct dnslabel_table *table) 1545 { 1546 table->n_labels = 0; 1547 } 1548 1549 /* Free all storage held by table, but not the table itself. */ 1550 static void 1551 dnslabel_clear(struct dnslabel_table *table) 1552 { 1553 int i; 1554 for (i = 0; i < table->n_labels; ++i) 1555 mm_free(table->labels[i].v); 1556 table->n_labels = 0; 1557 } 1558 1559 /* return the position of the label in the current message, or -1 if the label */ 1560 /* hasn't been used yet. */ 1561 static int 1562 dnslabel_table_get_pos(const struct dnslabel_table *table, const char *label) 1563 { 1564 int i; 1565 for (i = 0; i < table->n_labels; ++i) { 1566 if (!strcmp(label, table->labels[i].v)) 1567 return table->labels[i].pos; 1568 } 1569 return -1; 1570 } 1571 1572 /* remember that we've used the label at position pos */ 1573 static int 1574 dnslabel_table_add(struct dnslabel_table *table, const char *label, off_t pos) 1575 { 1576 char *v; 1577 int p; 1578 if (table->n_labels == MAX_LABELS) 1579 return (-1); 1580 v = mm_strdup(label); 1581 if (v == NULL) 1582 return (-1); 1583 p = table->n_labels++; 1584 table->labels[p].v = v; 1585 table->labels[p].pos = pos; 1586 1587 return (0); 1588 } 1589 1590 /* Converts a string to a length-prefixed set of DNS labels, starting */ 1591 /* at buf[j]. name and buf must not overlap. name_len should be the length */ 1592 /* of name. table is optional, and is used for compression. */ 1593 /* */ 1594 /* Input: abc.def */ 1595 /* Output: <3>abc<3>def<0> */ 1596 /* */ 1597 /* Returns the first index after the encoded name, or negative on error. */ 1598 /* -1 label was > 63 bytes */ 1599 /* -2 name too long to fit in buffer. */ 1600 /* */ 1601 static off_t 1602 dnsname_to_labels(u8 *const buf, size_t buf_len, off_t j, 1603 const char *name, const size_t name_len, 1604 struct dnslabel_table *table) { 1605 const char *end = name + name_len; 1606 int ref = 0; 1607 u16 t_; 1608 1609 #define APPEND16(x) do { \ 1610 if (j + 2 > (off_t)buf_len) \ 1611 goto overflow; \ 1612 t_ = htons(x); \ 1613 memcpy(buf + j, &t_, 2); \ 1614 j += 2; \ 1615 } while (0) 1616 #define APPEND32(x) do { \ 1617 if (j + 4 > (off_t)buf_len) \ 1618 goto overflow; \ 1619 t32_ = htonl(x); \ 1620 memcpy(buf + j, &t32_, 4); \ 1621 j += 4; \ 1622 } while (0) 1623 1624 if (name_len > 255) return -2; 1625 1626 for (;;) { 1627 const char *const start = name; 1628 if (table && (ref = dnslabel_table_get_pos(table, name)) >= 0) { 1629 APPEND16(ref | 0xc000); 1630 return j; 1631 } 1632 name = strchr(name, '.'); 1633 if (!name) { 1634 const size_t label_len = end - start; 1635 if (label_len > 63) return -1; 1636 if ((size_t)(j+label_len+1) > buf_len) return -2; 1637 if (table) dnslabel_table_add(table, start, j); 1638 buf[j++] = (ev_uint8_t)label_len; 1639 1640 memcpy(buf + j, start, label_len); 1641 j += (int) label_len; 1642 break; 1643 } else { 1644 /* append length of the label. */ 1645 const size_t label_len = name - start; 1646 if (label_len > 63) return -1; 1647 if ((size_t)(j+label_len+1) > buf_len) return -2; 1648 if (table) dnslabel_table_add(table, start, j); 1649 buf[j++] = (ev_uint8_t)label_len; 1650 1651 memcpy(buf + j, start, label_len); 1652 j += (int) label_len; 1653 /* hop over the '.' */ 1654 name++; 1655 } 1656 } 1657 1658 /* the labels must be terminated by a 0. */ 1659 /* It's possible that the name ended in a . */ 1660 /* in which case the zero is already there */ 1661 if (!j || buf[j-1]) buf[j++] = 0; 1662 return j; 1663 overflow: 1664 return (-2); 1665 } 1666 1667 /* Finds the length of a dns request for a DNS name of the given */ 1668 /* length. The actual request may be smaller than the value returned */ 1669 /* here */ 1670 static size_t 1671 evdns_request_len(const size_t name_len) { 1672 return 96 + /* length of the DNS standard header */ 1673 name_len + 2 + 1674 4; /* space for the resource type */ 1675 } 1676 1677 /* build a dns request packet into buf. buf should be at least as long */ 1678 /* as evdns_request_len told you it should be. */ 1679 /* */ 1680 /* Returns the amount of space used. Negative on error. */ 1681 static int 1682 evdns_request_data_build(const char *const name, const size_t name_len, 1683 const u16 trans_id, const u16 type, const u16 class, 1684 u8 *const buf, size_t buf_len) { 1685 off_t j = 0; /* current offset into buf */ 1686 u16 t_; /* used by the macros */ 1687 1688 APPEND16(trans_id); 1689 APPEND16(0x0100); /* standard query, recusion needed */ 1690 APPEND16(1); /* one question */ 1691 APPEND16(0); /* no answers */ 1692 APPEND16(0); /* no authority */ 1693 APPEND16(0); /* no additional */ 1694 1695 j = dnsname_to_labels(buf, buf_len, j, name, name_len, NULL); 1696 if (j < 0) { 1697 return (int)j; 1698 } 1699 1700 APPEND16(type); 1701 APPEND16(class); 1702 1703 return (int)j; 1704 overflow: 1705 return (-1); 1706 } 1707 1708 /* exported function */ 1709 struct evdns_server_port * 1710 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) 1711 { 1712 struct evdns_server_port *port; 1713 if (flags) 1714 return NULL; /* flags not yet implemented */ 1715 if (!(port = mm_malloc(sizeof(struct evdns_server_port)))) 1716 return NULL; 1717 memset(port, 0, sizeof(struct evdns_server_port)); 1718 1719 1720 port->socket = socket; 1721 port->refcnt = 1; 1722 port->choked = 0; 1723 port->closing = 0; 1724 port->user_callback = cb; 1725 port->user_data = user_data; 1726 port->pending_replies = NULL; 1727 port->event_base = base; 1728 1729 event_assign(&port->event, port->event_base, 1730 port->socket, EV_READ | EV_PERSIST, 1731 server_port_ready_callback, port); 1732 if (event_add(&port->event, NULL) < 0) { 1733 mm_free(port); 1734 return NULL; 1735 } 1736 EVTHREAD_ALLOC_LOCK(port->lock, EVTHREAD_LOCKTYPE_RECURSIVE); 1737 return port; 1738 } 1739 1740 struct evdns_server_port * 1741 evdns_add_server_port(evutil_socket_t socket, int flags, evdns_request_callback_fn_type cb, void *user_data) 1742 { 1743 return evdns_add_server_port_with_base(NULL, socket, flags, cb, user_data); 1744 } 1745 1746 /* exported function */ 1747 void 1748 evdns_close_server_port(struct evdns_server_port *port) 1749 { 1750 EVDNS_LOCK(port); 1751 if (--port->refcnt == 0) { 1752 EVDNS_UNLOCK(port); 1753 server_port_free(port); 1754 } else { 1755 port->closing = 1; 1756 } 1757 } 1758 1759 /* exported function */ 1760 int 1761 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) 1762 { 1763 struct server_request *req = TO_SERVER_REQUEST(req_); 1764 struct server_reply_item **itemp, *item; 1765 int *countp; 1766 int result = -1; 1767 1768 EVDNS_LOCK(req->port); 1769 if (req->response) /* have we already answered? */ 1770 goto done; 1771 1772 switch (section) { 1773 case EVDNS_ANSWER_SECTION: 1774 itemp = &req->answer; 1775 countp = &req->n_answer; 1776 break; 1777 case EVDNS_AUTHORITY_SECTION: 1778 itemp = &req->authority; 1779 countp = &req->n_authority; 1780 break; 1781 case EVDNS_ADDITIONAL_SECTION: 1782 itemp = &req->additional; 1783 countp = &req->n_additional; 1784 break; 1785 default: 1786 goto done; 1787 } 1788 while (*itemp) { 1789 itemp = &((*itemp)->next); 1790 } 1791 item = mm_malloc(sizeof(struct server_reply_item)); 1792 if (!item) 1793 goto done; 1794 item->next = NULL; 1795 if (!(item->name = mm_strdup(name))) { 1796 mm_free(item); 1797 goto done; 1798 } 1799 item->type = type; 1800 item->dns_question_class = class; 1801 item->ttl = ttl; 1802 item->is_name = is_name != 0; 1803 item->datalen = 0; 1804 item->data = NULL; 1805 if (data) { 1806 if (item->is_name) { 1807 if (!(item->data = mm_strdup(data))) { 1808 mm_free(item->name); 1809 mm_free(item); 1810 goto done; 1811 } 1812 item->datalen = (u16)-1; 1813 } else { 1814 if (!(item->data = mm_malloc(datalen))) { 1815 mm_free(item->name); 1816 mm_free(item); 1817 goto done; 1818 } 1819 item->datalen = datalen; 1820 memcpy(item->data, data, datalen); 1821 } 1822 } 1823 1824 *itemp = item; 1825 ++(*countp); 1826 result = 0; 1827 done: 1828 EVDNS_UNLOCK(req->port); 1829 return result; 1830 } 1831 1832 /* exported function */ 1833 int 1834 evdns_server_request_add_a_reply(struct evdns_server_request *req, const char *name, int n, const void *addrs, int ttl) 1835 { 1836 return evdns_server_request_add_reply( 1837 req, EVDNS_ANSWER_SECTION, name, TYPE_A, CLASS_INET, 1838 ttl, n*4, 0, addrs); 1839 } 1840 1841 /* exported function */ 1842 int 1843 evdns_server_request_add_aaaa_reply(struct evdns_server_request *req, const char *name, int n, const void *addrs, int ttl) 1844 { 1845 return evdns_server_request_add_reply( 1846 req, EVDNS_ANSWER_SECTION, name, TYPE_AAAA, CLASS_INET, 1847 ttl, n*16, 0, addrs); 1848 } 1849 1850 /* exported function */ 1851 int 1852 evdns_server_request_add_ptr_reply(struct evdns_server_request *req, struct in_addr *in, const char *inaddr_name, const char *hostname, int ttl) 1853 { 1854 u32 a; 1855 char buf[32]; 1856 if (in && inaddr_name) 1857 return -1; 1858 else if (!in && !inaddr_name) 1859 return -1; 1860 if (in) { 1861 a = ntohl(in->s_addr); 1862 evutil_snprintf(buf, sizeof(buf), "%d.%d.%d.%d.in-addr.arpa", 1863 (int)(u8)((a )&0xff), 1864 (int)(u8)((a>>8 )&0xff), 1865 (int)(u8)((a>>16)&0xff), 1866 (int)(u8)((a>>24)&0xff)); 1867 inaddr_name = buf; 1868 } 1869 return evdns_server_request_add_reply( 1870 req, EVDNS_ANSWER_SECTION, inaddr_name, TYPE_PTR, CLASS_INET, 1871 ttl, -1, 1, hostname); 1872 } 1873 1874 /* exported function */ 1875 int 1876 evdns_server_request_add_cname_reply(struct evdns_server_request *req, const char *name, const char *cname, int ttl) 1877 { 1878 return evdns_server_request_add_reply( 1879 req, EVDNS_ANSWER_SECTION, name, TYPE_CNAME, CLASS_INET, 1880 ttl, -1, 1, cname); 1881 } 1882 1883 /* exported function */ 1884 void 1885 evdns_server_request_set_flags(struct evdns_server_request *exreq, int flags) 1886 { 1887 struct server_request *req = TO_SERVER_REQUEST(exreq); 1888 req->base.flags &= ~(EVDNS_FLAGS_AA|EVDNS_FLAGS_RD); 1889 req->base.flags |= flags; 1890 } 1891 1892 static int 1893 evdns_server_request_format_response(struct server_request *req, int err) 1894 { 1895 unsigned char buf[1500]; 1896 size_t buf_len = sizeof(buf); 1897 off_t j = 0, r; 1898 u16 t_; 1899 u32 t32_; 1900 int i; 1901 u16 flags; 1902 struct dnslabel_table table; 1903 1904 if (err < 0 || err > 15) return -1; 1905 1906 /* Set response bit and error code; copy OPCODE and RD fields from 1907 * question; copy RA and AA if set by caller. */ 1908 flags = req->base.flags; 1909 flags |= (0x8000 | err); 1910 1911 dnslabel_table_init(&table); 1912 APPEND16(req->trans_id); 1913 APPEND16(flags); 1914 APPEND16(req->base.nquestions); 1915 APPEND16(req->n_answer); 1916 APPEND16(req->n_authority); 1917 APPEND16(req->n_additional); 1918 1919 /* Add questions. */ 1920 for (i=0; i < req->base.nquestions; ++i) { 1921 const char *s = req->base.questions[i]->name; 1922 j = dnsname_to_labels(buf, buf_len, j, s, strlen(s), &table); 1923 if (j < 0) { 1924 dnslabel_clear(&table); 1925 return (int) j; 1926 } 1927 APPEND16(req->base.questions[i]->type); 1928 APPEND16(req->base.questions[i]->dns_question_class); 1929 } 1930 1931 /* Add answer, authority, and additional sections. */ 1932 for (i=0; i<3; ++i) { 1933 struct server_reply_item *item; 1934 if (i==0) 1935 item = req->answer; 1936 else if (i==1) 1937 item = req->authority; 1938 else 1939 item = req->additional; 1940 while (item) { 1941 r = dnsname_to_labels(buf, buf_len, j, item->name, strlen(item->name), &table); 1942 if (r < 0) 1943 goto overflow; 1944 j = r; 1945 1946 APPEND16(item->type); 1947 APPEND16(item->dns_question_class); 1948 APPEND32(item->ttl); 1949 if (item->is_name) { 1950 off_t len_idx = j, name_start; 1951 j += 2; 1952 name_start = j; 1953 r = dnsname_to_labels(buf, buf_len, j, item->data, strlen(item->data), &table); 1954 if (r < 0) 1955 goto overflow; 1956 j = r; 1957 t_ = htons( (short) (j-name_start) ); 1958 memcpy(buf+len_idx, &t_, 2); 1959 } else { 1960 APPEND16(item->datalen); 1961 if (j+item->datalen > (off_t)buf_len) 1962 goto overflow; 1963 memcpy(buf+j, item->data, item->datalen); 1964 j += item->datalen; 1965 } 1966 item = item->next; 1967 } 1968 } 1969 1970 if (j > 512) { 1971 overflow: 1972 j = 512; 1973 buf[2] |= 0x02; /* set the truncated bit. */ 1974 } 1975 1976 req->response_len = j; 1977 1978 if (!(req->response = mm_malloc(req->response_len))) { 1979 server_request_free_answers(req); 1980 dnslabel_clear(&table); 1981 return (-1); 1982 } 1983 memcpy(req->response, buf, req->response_len); 1984 server_request_free_answers(req); 1985 dnslabel_clear(&table); 1986 return (0); 1987 } 1988 1989 /* exported function */ 1990 int 1991 evdns_server_request_respond(struct evdns_server_request *req_, int err) 1992 { 1993 struct server_request *req = TO_SERVER_REQUEST(req_); 1994 struct evdns_server_port *port = req->port; 1995 int r = -1; 1996 1997 EVDNS_LOCK(port); 1998 if (!req->response) { 1999 if ((r = evdns_server_request_format_response(req, err))<0) 2000 goto done; 2001 } 2002 2003 r = sendto(port->socket, req->response, (int)req->response_len, 0, 2004 (struct sockaddr*) &req->addr, (ev_socklen_t)req->addrlen); 2005 if (r<0) { 2006 int sock_err = evutil_socket_geterror(port->socket); 2007 if (EVUTIL_ERR_RW_RETRIABLE(sock_err)) 2008 goto done; 2009 2010 if (port->pending_replies) { 2011 req->prev_pending = port->pending_replies->prev_pending; 2012 req->next_pending = port->pending_replies; 2013 req->prev_pending->next_pending = 2014 req->next_pending->prev_pending = req; 2015 } else { 2016 req->prev_pending = req->next_pending = req; 2017 port->pending_replies = req; 2018 port->choked = 1; 2019 2020 (void) event_del(&port->event); 2021 event_assign(&port->event, port->event_base, port->socket, (port->closing?0:EV_READ) | EV_WRITE | EV_PERSIST, server_port_ready_callback, port); 2022 2023 if (event_add(&port->event, NULL) < 0) { 2024 log(EVDNS_LOG_WARN, "Error from libevent when adding event for DNS server"); 2025 } 2026 2027 } 2028 2029 r = 1; 2030 goto done; 2031 } 2032 if (server_request_free(req)) { 2033 r = 0; 2034 goto done; 2035 } 2036 2037 if (port->pending_replies) 2038 server_port_flush(port); 2039 2040 r = 0; 2041 done: 2042 EVDNS_UNLOCK(port); 2043 return r; 2044 } 2045 2046 /* Free all storage held by RRs in req. */ 2047 static void 2048 server_request_free_answers(struct server_request *req) 2049 { 2050 struct server_reply_item *victim, *next, **list; 2051 int i; 2052 for (i = 0; i < 3; ++i) { 2053 if (i==0) 2054 list = &req->answer; 2055 else if (i==1) 2056 list = &req->authority; 2057 else 2058 list = &req->additional; 2059 2060 victim = *list; 2061 while (victim) { 2062 next = victim->next; 2063 mm_free(victim->name); 2064 if (victim->data) 2065 mm_free(victim->data); 2066 mm_free(victim); 2067 victim = next; 2068 } 2069 *list = NULL; 2070 } 2071 } 2072 2073 /* Free all storage held by req, and remove links to it. */ 2074 /* return true iff we just wound up freeing the server_port. */ 2075 static int 2076 server_request_free(struct server_request *req) 2077 { 2078 int i, rc=1, lock=0; 2079 if (req->base.questions) { 2080 for (i = 0; i < req->base.nquestions; ++i) 2081 mm_free(req->base.questions[i]); 2082 mm_free(req->base.questions); 2083 } 2084 2085 if (req->port) { 2086 EVDNS_LOCK(req->port); 2087 lock=1; 2088 if (req->port->pending_replies == req) { 2089 if (req->next_pending && req->next_pending != req) 2090 req->port->pending_replies = req->next_pending; 2091 else 2092 req->port->pending_replies = NULL; 2093 } 2094 rc = --req->port->refcnt; 2095 } 2096 2097 if (req->response) { 2098 mm_free(req->response); 2099 } 2100 2101 server_request_free_answers(req); 2102 2103 if (req->next_pending && req->next_pending != req) { 2104 req->next_pending->prev_pending = req->prev_pending; 2105 req->prev_pending->next_pending = req->next_pending; 2106 } 2107 2108 if (rc == 0) { 2109 EVDNS_UNLOCK(req->port); /* ????? nickm */ 2110 server_port_free(req->port); 2111 mm_free(req); 2112 return (1); 2113 } 2114 if (lock) 2115 EVDNS_UNLOCK(req->port); 2116 mm_free(req); 2117 return (0); 2118 } 2119 2120 /* Free all storage held by an evdns_server_port. Only called when */ 2121 static void 2122 server_port_free(struct evdns_server_port *port) 2123 { 2124 EVUTIL_ASSERT(port); 2125 EVUTIL_ASSERT(!port->refcnt); 2126 EVUTIL_ASSERT(!port->pending_replies); 2127 if (port->socket > 0) { 2128 evutil_closesocket(port->socket); 2129 port->socket = -1; 2130 } 2131 (void) event_del(&port->event); 2132 event_debug_unassign(&port->event); 2133 EVTHREAD_FREE_LOCK(port->lock, EVTHREAD_LOCKTYPE_RECURSIVE); 2134 mm_free(port); 2135 } 2136 2137 /* exported function */ 2138 int 2139 evdns_server_request_drop(struct evdns_server_request *req_) 2140 { 2141 struct server_request *req = TO_SERVER_REQUEST(req_); 2142 server_request_free(req); 2143 return 0; 2144 } 2145 2146 /* exported function */ 2147 int 2148 evdns_server_request_get_requesting_addr(struct evdns_server_request *req_, struct sockaddr *sa, int addr_len) 2149 { 2150 struct server_request *req = TO_SERVER_REQUEST(req_); 2151 if (addr_len < (int)req->addrlen) 2152 return -1; 2153 memcpy(sa, &(req->addr), req->addrlen); 2154 return req->addrlen; 2155 } 2156 2157 #undef APPEND16 2158 #undef APPEND32 2159 2160 /* this is a libevent callback function which is called when a request */ 2161 /* has timed out. */ 2162 static void 2163 evdns_request_timeout_callback(evutil_socket_t fd, short events, void *arg) { 2164 struct request *const req = (struct request *) arg; 2165 struct evdns_base *base = req->base; 2166 2167 (void) fd; 2168 (void) events; 2169 2170 log(EVDNS_LOG_DEBUG, "Request %p timed out", arg); 2171 EVDNS_LOCK(base); 2172 2173 if (req->tx_count >= req->base->global_max_retransmits) { 2174 struct nameserver *ns = req->ns; 2175 /* this request has failed */ 2176 log(EVDNS_LOG_DEBUG, "Giving up on request %p; tx_count==%d", 2177 arg, req->tx_count); 2178 reply_schedule_callback(req, 0, DNS_ERR_TIMEOUT, NULL); 2179 2180 request_finished(req, &REQ_HEAD(req->base, req->trans_id), 1); 2181 nameserver_failed(ns, "request timed out."); 2182 } else { 2183 /* retransmit it */ 2184 log(EVDNS_LOG_DEBUG, "Retransmitting request %p; tx_count==%d", 2185 arg, req->tx_count); 2186 (void) evtimer_del(&req->timeout_event); 2187 request_swap_ns(req, nameserver_pick(base)); 2188 evdns_request_transmit(req); 2189 2190 req->ns->timedout++; 2191 if (req->ns->timedout > req->base->global_max_nameserver_timeout) { 2192 req->ns->timedout = 0; 2193 nameserver_failed(req->ns, "request timed out."); 2194 } 2195 } 2196 2197 EVDNS_UNLOCK(base); 2198 } 2199 2200 /* try to send a request to a given server. */ 2201 /* */ 2202 /* return: */ 2203 /* 0 ok */ 2204 /* 1 temporary failure */ 2205 /* 2 other failure */ 2206 static int 2207 evdns_request_transmit_to(struct request *req, struct nameserver *server) { 2208 int r; 2209 ASSERT_LOCKED(req->base); 2210 ASSERT_VALID_REQUEST(req); 2211 2212 if (server->requests_inflight == 1 && 2213 req->base->disable_when_inactive && 2214 event_add(&server->event, NULL) < 0) { 2215 return 1; 2216 } 2217 2218 r = sendto(server->socket, (void*)req->request, req->request_len, 0, 2219 (struct sockaddr *)&server->address, server->addrlen); 2220 if (r < 0) { 2221 int err = evutil_socket_geterror(server->socket); 2222 if (EVUTIL_ERR_RW_RETRIABLE(err)) 2223 return 1; 2224 nameserver_failed(req->ns, evutil_socket_error_to_string(err)); 2225 return 2; 2226 } else if (r != (int)req->request_len) { 2227 return 1; /* short write */ 2228 } else { 2229 return 0; 2230 } 2231 } 2232 2233 /* try to send a request, updating the fields of the request */ 2234 /* as needed */ 2235 /* */ 2236 /* return: */ 2237 /* 0 ok */ 2238 /* 1 failed */ 2239 static int 2240 evdns_request_transmit(struct request *req) { 2241 int retcode = 0, r; 2242 2243 ASSERT_LOCKED(req->base); 2244 ASSERT_VALID_REQUEST(req); 2245 /* if we fail to send this packet then this flag marks it */ 2246 /* for evdns_transmit */ 2247 req->transmit_me = 1; 2248 EVUTIL_ASSERT(req->trans_id != 0xffff); 2249 2250 if (!req->ns) 2251 { 2252 /* unable to transmit request if no nameservers */ 2253 return 1; 2254 } 2255 2256 if (req->ns->choked) { 2257 /* don't bother trying to write to a socket */ 2258 /* which we have had EAGAIN from */ 2259 return 1; 2260 } 2261 2262 r = evdns_request_transmit_to(req, req->ns); 2263 switch (r) { 2264 case 1: 2265 /* temp failure */ 2266 req->ns->choked = 1; 2267 nameserver_write_waiting(req->ns, 1); 2268 return 1; 2269 case 2: 2270 /* failed to transmit the request entirely. */ 2271 retcode = 1; 2272 /* fall through: we'll set a timeout, which will time out, 2273 * and make us retransmit the request anyway. */ 2274 default: 2275 /* all ok */ 2276 log(EVDNS_LOG_DEBUG, 2277 "Setting timeout for request %p, sent to nameserver %p", req, req->ns); 2278 if (evtimer_add(&req->timeout_event, &req->base->global_timeout) < 0) { 2279 log(EVDNS_LOG_WARN, 2280 "Error from libevent when adding timer for request %p", 2281 req); 2282 /* ???? Do more? */ 2283 } 2284 req->tx_count++; 2285 req->transmit_me = 0; 2286 return retcode; 2287 } 2288 } 2289 2290 static void 2291 nameserver_probe_callback(int result, char type, int count, int ttl, void *addresses, void *arg) { 2292 struct nameserver *const ns = (struct nameserver *) arg; 2293 (void) type; 2294 (void) count; 2295 (void) ttl; 2296 (void) addresses; 2297 2298 if (result == DNS_ERR_CANCEL) { 2299 /* We canceled this request because the nameserver came up 2300 * for some other reason. Do not change our opinion about 2301 * the nameserver. */ 2302 return; 2303 } 2304 2305 EVDNS_LOCK(ns->base); 2306 ns->probe_request = NULL; 2307 if (result == DNS_ERR_NONE || result == DNS_ERR_NOTEXIST) { 2308 /* this is a good reply */ 2309 nameserver_up(ns); 2310 } else { 2311 nameserver_probe_failed(ns); 2312 } 2313 EVDNS_UNLOCK(ns->base); 2314 } 2315 2316 static void 2317 nameserver_send_probe(struct nameserver *const ns) { 2318 struct evdns_request *handle; 2319 struct request *req; 2320 char addrbuf[128]; 2321 /* here we need to send a probe to a given nameserver */ 2322 /* in the hope that it is up now. */ 2323 2324 ASSERT_LOCKED(ns->base); 2325 log(EVDNS_LOG_DEBUG, "Sending probe to %s", 2326 evutil_format_sockaddr_port_( 2327 (struct sockaddr *)&ns->address, 2328 addrbuf, sizeof(addrbuf))); 2329 handle = mm_calloc(1, sizeof(*handle)); 2330 if (!handle) return; 2331 req = request_new(ns->base, handle, TYPE_A, "google.com", DNS_QUERY_NO_SEARCH, nameserver_probe_callback, ns); 2332 if (!req) { 2333 mm_free(handle); 2334 return; 2335 } 2336 ns->probe_request = handle; 2337 /* we force this into the inflight queue no matter what */ 2338 request_trans_id_set(req, transaction_id_pick(ns->base)); 2339 req->ns = ns; 2340 request_submit(req); 2341 } 2342 2343 /* returns: */ 2344 /* 0 didn't try to transmit anything */ 2345 /* 1 tried to transmit something */ 2346 static int 2347 evdns_transmit(struct evdns_base *base) { 2348 char did_try_to_transmit = 0; 2349 int i; 2350 2351 ASSERT_LOCKED(base); 2352 for (i = 0; i < base->n_req_heads; ++i) { 2353 if (base->req_heads[i]) { 2354 struct request *const started_at = base->req_heads[i], *req = started_at; 2355 /* first transmit all the requests which are currently waiting */ 2356 do { 2357 if (req->transmit_me) { 2358 did_try_to_transmit = 1; 2359 evdns_request_transmit(req); 2360 } 2361 2362 req = req->next; 2363 } while (req != started_at); 2364 } 2365 } 2366 2367 return did_try_to_transmit; 2368 } 2369 2370 /* exported function */ 2371 int 2372 evdns_base_count_nameservers(struct evdns_base *base) 2373 { 2374 const struct nameserver *server; 2375 int n = 0; 2376 2377 EVDNS_LOCK(base); 2378 server = base->server_head; 2379 if (!server) 2380 goto done; 2381 do { 2382 ++n; 2383 server = server->next; 2384 } while (server != base->server_head); 2385 done: 2386 EVDNS_UNLOCK(base); 2387 return n; 2388 } 2389 2390 int 2391 evdns_count_nameservers(void) 2392 { 2393 return evdns_base_count_nameservers(current_base); 2394 } 2395 2396 /* exported function */ 2397 int 2398 evdns_base_clear_nameservers_and_suspend(struct evdns_base *base) 2399 { 2400 struct nameserver *server, *started_at; 2401 int i; 2402 2403 EVDNS_LOCK(base); 2404 server = base->server_head; 2405 started_at = base->server_head; 2406 if (!server) { 2407 EVDNS_UNLOCK(base); 2408 return 0; 2409 } 2410 while (1) { 2411 struct nameserver *next = server->next; 2412 (void) event_del(&server->event); 2413 if (evtimer_initialized(&server->timeout_event)) 2414 (void) evtimer_del(&server->timeout_event); 2415 if (server->probe_request) { 2416 evdns_cancel_request(server->base, server->probe_request); 2417 server->probe_request = NULL; 2418 } 2419 if (server->socket >= 0) 2420 evutil_closesocket(server->socket); 2421 mm_free(server); 2422 if (next == started_at) 2423 break; 2424 server = next; 2425 } 2426 base->server_head = NULL; 2427 base->global_good_nameservers = 0; 2428 2429 for (i = 0; i < base->n_req_heads; ++i) { 2430 struct request *req, *req_started_at; 2431 req = req_started_at = base->req_heads[i]; 2432 while (req) { 2433 struct request *next = req->next; 2434 req->tx_count = req->reissue_count = 0; 2435 req->ns = NULL; 2436 /* ???? What to do about searches? */ 2437 (void) evtimer_del(&req->timeout_event); 2438 req->trans_id = 0; 2439 req->transmit_me = 0; 2440 2441 base->global_requests_waiting++; 2442 evdns_request_insert(req, &base->req_waiting_head); 2443 /* We want to insert these suspended elements at the front of 2444 * the waiting queue, since they were pending before any of 2445 * the waiting entries were added. This is a circular list, 2446 * so we can just shift the start back by one.*/ 2447 base->req_waiting_head = base->req_waiting_head->prev; 2448 2449 if (next == req_started_at) 2450 break; 2451 req = next; 2452 } 2453 base->req_heads[i] = NULL; 2454 } 2455 2456 base->global_requests_inflight = 0; 2457 2458 EVDNS_UNLOCK(base); 2459 return 0; 2460 } 2461 2462 int 2463 evdns_clear_nameservers_and_suspend(void) 2464 { 2465 return evdns_base_clear_nameservers_and_suspend(current_base); 2466 } 2467 2468 2469 /* exported function */ 2470 int 2471 evdns_base_resume(struct evdns_base *base) 2472 { 2473 EVDNS_LOCK(base); 2474 evdns_requests_pump_waiting_queue(base); 2475 EVDNS_UNLOCK(base); 2476 2477 return 0; 2478 } 2479 2480 int 2481 evdns_resume(void) 2482 { 2483 return evdns_base_resume(current_base); 2484 } 2485 2486 static int 2487 evdns_nameserver_add_impl_(struct evdns_base *base, const struct sockaddr *address, int addrlen) { 2488 /* first check to see if we already have this nameserver */ 2489 2490 const struct nameserver *server = base->server_head, *const started_at = base->server_head; 2491 struct nameserver *ns; 2492 int err = 0; 2493 char addrbuf[128]; 2494 2495 ASSERT_LOCKED(base); 2496 if (server) { 2497 do { 2498 if (!evutil_sockaddr_cmp((struct sockaddr*)&server->address, address, 1)) return 3; 2499 server = server->next; 2500 } while (server != started_at); 2501 } 2502 if (addrlen > (int)sizeof(ns->address)) { 2503 log(EVDNS_LOG_DEBUG, "Addrlen %d too long.", (int)addrlen); 2504 return 2; 2505 } 2506 2507 ns = (struct nameserver *) mm_malloc(sizeof(struct nameserver)); 2508 if (!ns) return -1; 2509 2510 memset(ns, 0, sizeof(struct nameserver)); 2511 ns->base = base; 2512 2513 evtimer_assign(&ns->timeout_event, ns->base->event_base, nameserver_prod_callback, ns); 2514 2515 ns->socket = evutil_socket_(address->sa_family, 2516 SOCK_DGRAM|EVUTIL_SOCK_NONBLOCK|EVUTIL_SOCK_CLOEXEC, 0); 2517 if (ns->socket < 0) { err = 1; goto out1; } 2518 2519 if (base->global_outgoing_addrlen && 2520 !evutil_sockaddr_is_loopback_(address)) { 2521 if (bind(ns->socket, 2522 (struct sockaddr*)&base->global_outgoing_address, 2523 base->global_outgoing_addrlen) < 0) { 2524 log(EVDNS_LOG_WARN,"Couldn't bind to outgoing address"); 2525 err = 2; 2526 goto out2; 2527 } 2528 } 2529 2530 memcpy(&ns->address, address, addrlen); 2531 ns->addrlen = addrlen; 2532 ns->state = 1; 2533 event_assign(&ns->event, ns->base->event_base, ns->socket, 2534 EV_READ | EV_PERSIST, nameserver_ready_callback, ns); 2535 if (!base->disable_when_inactive && event_add(&ns->event, NULL) < 0) { 2536 err = 2; 2537 goto out2; 2538 } 2539 2540 log(EVDNS_LOG_DEBUG, "Added nameserver %s as %p", 2541 evutil_format_sockaddr_port_(address, addrbuf, sizeof(addrbuf)), ns); 2542 2543 /* insert this nameserver into the list of them */ 2544 if (!base->server_head) { 2545 ns->next = ns->prev = ns; 2546 base->server_head = ns; 2547 } else { 2548 ns->next = base->server_head->next; 2549 ns->prev = base->server_head; 2550 base->server_head->next = ns; 2551 ns->next->prev = ns; 2552 } 2553 2554 base->global_good_nameservers++; 2555 2556 return 0; 2557 2558 out2: 2559 evutil_closesocket(ns->socket); 2560 out1: 2561 event_debug_unassign(&ns->event); 2562 mm_free(ns); 2563 log(EVDNS_LOG_WARN, "Unable to add nameserver %s: error %d", 2564 evutil_format_sockaddr_port_(address, addrbuf, sizeof(addrbuf)), err); 2565 return err; 2566 } 2567 2568 /* exported function */ 2569 int 2570 evdns_base_nameserver_add(struct evdns_base *base, unsigned long int address) 2571 { 2572 struct sockaddr_in sin; 2573 int res; 2574 memset(&sin, 0, sizeof(sin)); 2575 sin.sin_addr.s_addr = address; 2576 sin.sin_port = htons(53); 2577 sin.sin_family = AF_INET; 2578 EVDNS_LOCK(base); 2579 res = evdns_nameserver_add_impl_(base, (struct sockaddr*)&sin, sizeof(sin)); 2580 EVDNS_UNLOCK(base); 2581 return res; 2582 } 2583 2584 int 2585 evdns_nameserver_add(unsigned long int address) { 2586 if (!current_base) 2587 current_base = evdns_base_new(NULL, 0); 2588 return evdns_base_nameserver_add(current_base, address); 2589 } 2590 2591 static void 2592 sockaddr_setport(struct sockaddr *sa, ev_uint16_t port) 2593 { 2594 if (sa->sa_family == AF_INET) { 2595 ((struct sockaddr_in *)sa)->sin_port = htons(port); 2596 } else if (sa->sa_family == AF_INET6) { 2597 ((struct sockaddr_in6 *)sa)->sin6_port = htons(port); 2598 } 2599 } 2600 2601 static ev_uint16_t 2602 sockaddr_getport(struct sockaddr *sa) 2603 { 2604 if (sa->sa_family == AF_INET) { 2605 return ntohs(((struct sockaddr_in *)sa)->sin_port); 2606 } else if (sa->sa_family == AF_INET6) { 2607 return ntohs(((struct sockaddr_in6 *)sa)->sin6_port); 2608 } else { 2609 return 0; 2610 } 2611 } 2612 2613 /* exported function */ 2614 int 2615 evdns_base_nameserver_ip_add(struct evdns_base *base, const char *ip_as_string) { 2616 struct sockaddr_storage ss; 2617 struct sockaddr *sa; 2618 int len = sizeof(ss); 2619 int res; 2620 if (evutil_parse_sockaddr_port(ip_as_string, (struct sockaddr *)&ss, 2621 &len)) { 2622 log(EVDNS_LOG_WARN, "Unable to parse nameserver address %s", 2623 ip_as_string); 2624 return 4; 2625 } 2626 sa = (struct sockaddr *) &ss; 2627 if (sockaddr_getport(sa) == 0) 2628 sockaddr_setport(sa, 53); 2629 2630 EVDNS_LOCK(base); 2631 res = evdns_nameserver_add_impl_(base, sa, len); 2632 EVDNS_UNLOCK(base); 2633 return res; 2634 } 2635 2636 int 2637 evdns_nameserver_ip_add(const char *ip_as_string) { 2638 if (!current_base) 2639 current_base = evdns_base_new(NULL, 0); 2640 return evdns_base_nameserver_ip_add(current_base, ip_as_string); 2641 } 2642 2643 int 2644 evdns_base_nameserver_sockaddr_add(struct evdns_base *base, 2645 const struct sockaddr *sa, ev_socklen_t len, unsigned flags) 2646 { 2647 int res; 2648 EVUTIL_ASSERT(base); 2649 EVDNS_LOCK(base); 2650 res = evdns_nameserver_add_impl_(base, sa, len); 2651 EVDNS_UNLOCK(base); 2652 return res; 2653 } 2654 2655 int 2656 evdns_base_get_nameserver_addr(struct evdns_base *base, int idx, 2657 struct sockaddr *sa, ev_socklen_t len) 2658 { 2659 int result = -1; 2660 int i; 2661 struct nameserver *server; 2662 EVDNS_LOCK(base); 2663 server = base->server_head; 2664 for (i = 0; i < idx && server; ++i, server = server->next) { 2665 if (server->next == base->server_head) 2666 goto done; 2667 } 2668 if (! server) 2669 goto done; 2670 2671 if (server->addrlen > len) { 2672 result = (int) server->addrlen; 2673 goto done; 2674 } 2675 2676 memcpy(sa, &server->address, server->addrlen); 2677 result = (int) server->addrlen; 2678 done: 2679 EVDNS_UNLOCK(base); 2680 return result; 2681 } 2682 2683 /* remove from the queue */ 2684 static void 2685 evdns_request_remove(struct request *req, struct request **head) 2686 { 2687 ASSERT_LOCKED(req->base); 2688 ASSERT_VALID_REQUEST(req); 2689 2690 #if 0 2691 { 2692 struct request *ptr; 2693 int found = 0; 2694 EVUTIL_ASSERT(*head != NULL); 2695 2696 ptr = *head; 2697 do { 2698 if (ptr == req) { 2699 found = 1; 2700 break; 2701 } 2702 ptr = ptr->next; 2703 } while (ptr != *head); 2704 EVUTIL_ASSERT(found); 2705 2706 EVUTIL_ASSERT(req->next); 2707 } 2708 #endif 2709 2710 if (req->next == req) { 2711 /* only item in the list */ 2712 *head = NULL; 2713 } else { 2714 req->next->prev = req->prev; 2715 req->prev->next = req->next; 2716 if (*head == req) *head = req->next; 2717 } 2718 req->next = req->prev = NULL; 2719 } 2720 2721 /* insert into the tail of the queue */ 2722 static void 2723 evdns_request_insert(struct request *req, struct request **head) { 2724 ASSERT_LOCKED(req->base); 2725 ASSERT_VALID_REQUEST(req); 2726 if (!*head) { 2727 *head = req; 2728 req->next = req->prev = req; 2729 return; 2730 } 2731 2732 req->prev = (*head)->prev; 2733 req->prev->next = req; 2734 req->next = *head; 2735 (*head)->prev = req; 2736 } 2737 2738 static int 2739 string_num_dots(const char *s) { 2740 int count = 0; 2741 while ((s = strchr(s, '.'))) { 2742 s++; 2743 count++; 2744 } 2745 return count; 2746 } 2747 2748 static struct request * 2749 request_new(struct evdns_base *base, struct evdns_request *handle, int type, 2750 const char *name, int flags, evdns_callback_type callback, 2751 void *user_ptr) { 2752 2753 const char issuing_now = 2754 (base->global_requests_inflight < base->global_max_requests_inflight) ? 1 : 0; 2755 2756 const size_t name_len = strlen(name); 2757 const size_t request_max_len = evdns_request_len(name_len); 2758 const u16 trans_id = issuing_now ? transaction_id_pick(base) : 0xffff; 2759 /* the request data is alloced in a single block with the header */ 2760 struct request *const req = 2761 mm_malloc(sizeof(struct request) + request_max_len); 2762 int rlen; 2763 char namebuf[256]; 2764 (void) flags; 2765 2766 ASSERT_LOCKED(base); 2767 2768 if (!req) return NULL; 2769 2770 if (name_len >= sizeof(namebuf)) { 2771 mm_free(req); 2772 return NULL; 2773 } 2774 2775 memset(req, 0, sizeof(struct request)); 2776 req->base = base; 2777 2778 evtimer_assign(&req->timeout_event, req->base->event_base, evdns_request_timeout_callback, req); 2779 2780 if (base->global_randomize_case) { 2781 unsigned i; 2782 char randbits[(sizeof(namebuf)+7)/8]; 2783 strlcpy(namebuf, name, sizeof(namebuf)); 2784 evutil_secure_rng_get_bytes(randbits, (name_len+7)/8); 2785 for (i = 0; i < name_len; ++i) { 2786 if (EVUTIL_ISALPHA_(namebuf[i])) { 2787 if ((randbits[i >> 3] & (1<<(i & 7)))) 2788 namebuf[i] |= 0x20; 2789 else 2790 namebuf[i] &= ~0x20; 2791 } 2792 } 2793 name = namebuf; 2794 } 2795 2796 /* request data lives just after the header */ 2797 req->request = ((u8 *) req) + sizeof(struct request); 2798 /* denotes that the request data shouldn't be free()ed */ 2799 req->request_appended = 1; 2800 rlen = evdns_request_data_build(name, name_len, trans_id, 2801 type, CLASS_INET, req->request, request_max_len); 2802 if (rlen < 0) 2803 goto err1; 2804 2805 req->request_len = rlen; 2806 req->trans_id = trans_id; 2807 req->tx_count = 0; 2808 req->request_type = type; 2809 req->user_pointer = user_ptr; 2810 req->user_callback = callback; 2811 req->ns = issuing_now ? nameserver_pick(base) : NULL; 2812 req->next = req->prev = NULL; 2813 req->handle = handle; 2814 if (handle) { 2815 handle->current_req = req; 2816 handle->base = base; 2817 } 2818 2819 return req; 2820 err1: 2821 mm_free(req); 2822 return NULL; 2823 } 2824 2825 static void 2826 request_submit(struct request *const req) { 2827 struct evdns_base *base = req->base; 2828 ASSERT_LOCKED(base); 2829 ASSERT_VALID_REQUEST(req); 2830 if (req->ns) { 2831 /* if it has a nameserver assigned then this is going */ 2832 /* straight into the inflight queue */ 2833 evdns_request_insert(req, &REQ_HEAD(base, req->trans_id)); 2834 2835 base->global_requests_inflight++; 2836 req->ns->requests_inflight++; 2837 2838 evdns_request_transmit(req); 2839 } else { 2840 evdns_request_insert(req, &base->req_waiting_head); 2841 base->global_requests_waiting++; 2842 } 2843 } 2844 2845 /* exported function */ 2846 void 2847 evdns_cancel_request(struct evdns_base *base, struct evdns_request *handle) 2848 { 2849 struct request *req; 2850 2851 if (!handle->current_req) 2852 return; 2853 2854 if (!base) { 2855 /* This redundancy is silly; can we fix it? (Not for 2.0) XXXX */ 2856 base = handle->base; 2857 if (!base) 2858 base = handle->current_req->base; 2859 } 2860 2861 EVDNS_LOCK(base); 2862 if (handle->pending_cb) { 2863 EVDNS_UNLOCK(base); 2864 return; 2865 } 2866 2867 req = handle->current_req; 2868 ASSERT_VALID_REQUEST(req); 2869 2870 reply_schedule_callback(req, 0, DNS_ERR_CANCEL, NULL); 2871 if (req->ns) { 2872 /* remove from inflight queue */ 2873 request_finished(req, &REQ_HEAD(base, req->trans_id), 1); 2874 } else { 2875 /* remove from global_waiting head */ 2876 request_finished(req, &base->req_waiting_head, 1); 2877 } 2878 EVDNS_UNLOCK(base); 2879 } 2880 2881 /* exported function */ 2882 struct evdns_request * 2883 evdns_base_resolve_ipv4(struct evdns_base *base, const char *name, int flags, 2884 evdns_callback_type callback, void *ptr) { 2885 struct evdns_request *handle; 2886 struct request *req; 2887 log(EVDNS_LOG_DEBUG, "Resolve requested for %s", name); 2888 handle = mm_calloc(1, sizeof(*handle)); 2889 if (handle == NULL) 2890 return NULL; 2891 EVDNS_LOCK(base); 2892 if (flags & DNS_QUERY_NO_SEARCH) { 2893 req = 2894 request_new(base, handle, TYPE_A, name, flags, 2895 callback, ptr); 2896 if (req) 2897 request_submit(req); 2898 } else { 2899 search_request_new(base, handle, TYPE_A, name, flags, 2900 callback, ptr); 2901 } 2902 if (handle->current_req == NULL) { 2903 mm_free(handle); 2904 handle = NULL; 2905 } 2906 EVDNS_UNLOCK(base); 2907 return handle; 2908 } 2909 2910 int evdns_resolve_ipv4(const char *name, int flags, 2911 evdns_callback_type callback, void *ptr) 2912 { 2913 return evdns_base_resolve_ipv4(current_base, name, flags, callback, ptr) 2914 ? 0 : -1; 2915 } 2916 2917 2918 /* exported function */ 2919 struct evdns_request * 2920 evdns_base_resolve_ipv6(struct evdns_base *base, 2921 const char *name, int flags, 2922 evdns_callback_type callback, void *ptr) 2923 { 2924 struct evdns_request *handle; 2925 struct request *req; 2926 log(EVDNS_LOG_DEBUG, "Resolve requested for %s", name); 2927 handle = mm_calloc(1, sizeof(*handle)); 2928 if (handle == NULL) 2929 return NULL; 2930 EVDNS_LOCK(base); 2931 if (flags & DNS_QUERY_NO_SEARCH) { 2932 req = request_new(base, handle, TYPE_AAAA, name, flags, 2933 callback, ptr); 2934 if (req) 2935 request_submit(req); 2936 } else { 2937 search_request_new(base, handle, TYPE_AAAA, name, flags, 2938 callback, ptr); 2939 } 2940 if (handle->current_req == NULL) { 2941 mm_free(handle); 2942 handle = NULL; 2943 } 2944 EVDNS_UNLOCK(base); 2945 return handle; 2946 } 2947 2948 int evdns_resolve_ipv6(const char *name, int flags, 2949 evdns_callback_type callback, void *ptr) { 2950 return evdns_base_resolve_ipv6(current_base, name, flags, callback, ptr) 2951 ? 0 : -1; 2952 } 2953 2954 struct evdns_request * 2955 evdns_base_resolve_reverse(struct evdns_base *base, const struct in_addr *in, int flags, evdns_callback_type callback, void *ptr) { 2956 char buf[32]; 2957 struct evdns_request *handle; 2958 struct request *req; 2959 u32 a; 2960 EVUTIL_ASSERT(in); 2961 a = ntohl(in->s_addr); 2962 evutil_snprintf(buf, sizeof(buf), "%d.%d.%d.%d.in-addr.arpa", 2963 (int)(u8)((a )&0xff), 2964 (int)(u8)((a>>8 )&0xff), 2965 (int)(u8)((a>>16)&0xff), 2966 (int)(u8)((a>>24)&0xff)); 2967 handle = mm_calloc(1, sizeof(*handle)); 2968 if (handle == NULL) 2969 return NULL; 2970 log(EVDNS_LOG_DEBUG, "Resolve requested for %s (reverse)", buf); 2971 EVDNS_LOCK(base); 2972 req = request_new(base, handle, TYPE_PTR, buf, flags, callback, ptr); 2973 if (req) 2974 request_submit(req); 2975 if (handle->current_req == NULL) { 2976 mm_free(handle); 2977 handle = NULL; 2978 } 2979 EVDNS_UNLOCK(base); 2980 return (handle); 2981 } 2982 2983 int evdns_resolve_reverse(const struct in_addr *in, int flags, evdns_callback_type callback, void *ptr) { 2984 return evdns_base_resolve_reverse(current_base, in, flags, callback, ptr) 2985 ? 0 : -1; 2986 } 2987 2988 struct evdns_request * 2989 evdns_base_resolve_reverse_ipv6(struct evdns_base *base, const struct in6_addr *in, int flags, evdns_callback_type callback, void *ptr) { 2990 /* 32 nybbles, 32 periods, "ip6.arpa", NUL. */ 2991 char buf[73]; 2992 char *cp; 2993 struct evdns_request *handle; 2994 struct request *req; 2995 int i; 2996 EVUTIL_ASSERT(in); 2997 cp = buf; 2998 for (i=15; i >= 0; --i) { 2999 u8 byte = in->s6_addr[i]; 3000 *cp++ = "0123456789abcdef"[byte & 0x0f]; 3001 *cp++ = '.'; 3002 *cp++ = "0123456789abcdef"[byte >> 4]; 3003 *cp++ = '.'; 3004 } 3005 EVUTIL_ASSERT(cp + strlen("ip6.arpa") < buf+sizeof(buf)); 3006 memcpy(cp, "ip6.arpa", strlen("ip6.arpa")+1); 3007 handle = mm_calloc(1, sizeof(*handle)); 3008 if (handle == NULL) 3009 return NULL; 3010 log(EVDNS_LOG_DEBUG, "Resolve requested for %s (reverse)", buf); 3011 EVDNS_LOCK(base); 3012 req = request_new(base, handle, TYPE_PTR, buf, flags, callback, ptr); 3013 if (req) 3014 request_submit(req); 3015 if (handle->current_req == NULL) { 3016 mm_free(handle); 3017 handle = NULL; 3018 } 3019 EVDNS_UNLOCK(base); 3020 return (handle); 3021 } 3022 3023 int evdns_resolve_reverse_ipv6(const struct in6_addr *in, int flags, evdns_callback_type callback, void *ptr) { 3024 return evdns_base_resolve_reverse_ipv6(current_base, in, flags, callback, ptr) 3025 ? 0 : -1; 3026 } 3027 3028 /* ================================================================= */ 3029 /* Search support */ 3030 /* */ 3031 /* the libc resolver has support for searching a number of domains */ 3032 /* to find a name. If nothing else then it takes the single domain */ 3033 /* from the gethostname() call. */ 3034 /* */ 3035 /* It can also be configured via the domain and search options in a */ 3036 /* resolv.conf. */ 3037 /* */ 3038 /* The ndots option controls how many dots it takes for the resolver */ 3039 /* to decide that a name is non-local and so try a raw lookup first. */ 3040 3041 struct search_domain { 3042 int len; 3043 struct search_domain *next; 3044 /* the text string is appended to this structure */ 3045 }; 3046 3047 struct search_state { 3048 int refcount; 3049 int ndots; 3050 int num_domains; 3051 struct search_domain *head; 3052 }; 3053 3054 static void 3055 search_state_decref(struct search_state *const state) { 3056 if (!state) return; 3057 state->refcount--; 3058 if (!state->refcount) { 3059 struct search_domain *next, *dom; 3060 for (dom = state->head; dom; dom = next) { 3061 next = dom->next; 3062 mm_free(dom); 3063 } 3064 mm_free(state); 3065 } 3066 } 3067 3068 static struct search_state * 3069 search_state_new(void) { 3070 struct search_state *state = (struct search_state *) mm_malloc(sizeof(struct search_state)); 3071 if (!state) return NULL; 3072 memset(state, 0, sizeof(struct search_state)); 3073 state->refcount = 1; 3074 state->ndots = 1; 3075 3076 return state; 3077 } 3078 3079 static void 3080 search_postfix_clear(struct evdns_base *base) { 3081 search_state_decref(base->global_search_state); 3082 3083 base->global_search_state = search_state_new(); 3084 } 3085 3086 /* exported function */ 3087 void 3088 evdns_base_search_clear(struct evdns_base *base) 3089 { 3090 EVDNS_LOCK(base); 3091 search_postfix_clear(base); 3092 EVDNS_UNLOCK(base); 3093 } 3094 3095 void 3096 evdns_search_clear(void) { 3097 evdns_base_search_clear(current_base); 3098 } 3099 3100 static void 3101 search_postfix_add(struct evdns_base *base, const char *domain) { 3102 size_t domain_len; 3103 struct search_domain *sdomain; 3104 while (domain[0] == '.') domain++; 3105 domain_len = strlen(domain); 3106 3107 ASSERT_LOCKED(base); 3108 if (!base->global_search_state) base->global_search_state = search_state_new(); 3109 if (!base->global_search_state) return; 3110 base->global_search_state->num_domains++; 3111 3112 sdomain = (struct search_domain *) mm_malloc(sizeof(struct search_domain) + domain_len); 3113 if (!sdomain) return; 3114 memcpy( ((u8 *) sdomain) + sizeof(struct search_domain), domain, domain_len); 3115 sdomain->next = base->global_search_state->head; 3116 sdomain->len = (int) domain_len; 3117 3118 base->global_search_state->head = sdomain; 3119 } 3120 3121 /* reverse the order of members in the postfix list. This is needed because, */ 3122 /* when parsing resolv.conf we push elements in the wrong order */ 3123 static void 3124 search_reverse(struct evdns_base *base) { 3125 struct search_domain *cur, *prev = NULL, *next; 3126 ASSERT_LOCKED(base); 3127 cur = base->global_search_state->head; 3128 while (cur) { 3129 next = cur->next; 3130 cur->next = prev; 3131 prev = cur; 3132 cur = next; 3133 } 3134 3135 base->global_search_state->head = prev; 3136 } 3137 3138 /* exported function */ 3139 void 3140 evdns_base_search_add(struct evdns_base *base, const char *domain) { 3141 EVDNS_LOCK(base); 3142 search_postfix_add(base, domain); 3143 EVDNS_UNLOCK(base); 3144 } 3145 void 3146 evdns_search_add(const char *domain) { 3147 evdns_base_search_add(current_base, domain); 3148 } 3149 3150 /* exported function */ 3151 void 3152 evdns_base_search_ndots_set(struct evdns_base *base, const int ndots) { 3153 EVDNS_LOCK(base); 3154 if (!base->global_search_state) base->global_search_state = search_state_new(); 3155 if (base->global_search_state) 3156 base->global_search_state->ndots = ndots; 3157 EVDNS_UNLOCK(base); 3158 } 3159 void 3160 evdns_search_ndots_set(const int ndots) { 3161 evdns_base_search_ndots_set(current_base, ndots); 3162 } 3163 3164 static void 3165 search_set_from_hostname(struct evdns_base *base) { 3166 char hostname[HOST_NAME_MAX + 1], *domainname; 3167 3168 ASSERT_LOCKED(base); 3169 search_postfix_clear(base); 3170 if (gethostname(hostname, sizeof(hostname))) return; 3171 domainname = strchr(hostname, '.'); 3172 if (!domainname) return; 3173 search_postfix_add(base, domainname); 3174 } 3175 3176 /* warning: returns malloced string */ 3177 static char * 3178 search_make_new(const struct search_state *const state, int n, const char *const base_name) { 3179 const size_t base_len = strlen(base_name); 3180 const char need_to_append_dot = base_name[base_len - 1] == '.' ? 0 : 1; 3181 struct search_domain *dom; 3182 3183 for (dom = state->head; dom; dom = dom->next) { 3184 if (!n--) { 3185 /* this is the postfix we want */ 3186 /* the actual postfix string is kept at the end of the structure */ 3187 const u8 *const postfix = ((u8 *) dom) + sizeof(struct search_domain); 3188 const int postfix_len = dom->len; 3189 char *const newname = (char *) mm_malloc(base_len + need_to_append_dot + postfix_len + 1); 3190 if (!newname) return NULL; 3191 memcpy(newname, base_name, base_len); 3192 if (need_to_append_dot) newname[base_len] = '.'; 3193 memcpy(newname + base_len + need_to_append_dot, postfix, postfix_len); 3194 newname[base_len + need_to_append_dot + postfix_len] = 0; 3195 return newname; 3196 } 3197 } 3198 3199 /* we ran off the end of the list and still didn't find the requested string */ 3200 EVUTIL_ASSERT(0); 3201 return NULL; /* unreachable; stops warnings in some compilers. */ 3202 } 3203 3204 static struct request * 3205 search_request_new(struct evdns_base *base, struct evdns_request *handle, 3206 int type, const char *const name, int flags, 3207 evdns_callback_type user_callback, void *user_arg) { 3208 ASSERT_LOCKED(base); 3209 EVUTIL_ASSERT(type == TYPE_A || type == TYPE_AAAA); 3210 EVUTIL_ASSERT(handle->current_req == NULL); 3211 if ( ((flags & DNS_QUERY_NO_SEARCH) == 0) && 3212 base->global_search_state && 3213 base->global_search_state->num_domains) { 3214 /* we have some domains to search */ 3215 struct request *req; 3216 if (string_num_dots(name) >= base->global_search_state->ndots) { 3217 req = request_new(base, handle, type, name, flags, user_callback, user_arg); 3218 if (!req) return NULL; 3219 handle->search_index = -1; 3220 } else { 3221 char *const new_name = search_make_new(base->global_search_state, 0, name); 3222 if (!new_name) return NULL; 3223 req = request_new(base, handle, type, new_name, flags, user_callback, user_arg); 3224 mm_free(new_name); 3225 if (!req) return NULL; 3226 handle->search_index = 0; 3227 } 3228 EVUTIL_ASSERT(handle->search_origname == NULL); 3229 handle->search_origname = mm_strdup(name); 3230 if (handle->search_origname == NULL) { 3231 /* XXX Should we dealloc req? If yes, how? */ 3232 if (req) 3233 mm_free(req); 3234 return NULL; 3235 } 3236 handle->search_state = base->global_search_state; 3237 handle->search_flags = flags; 3238 base->global_search_state->refcount++; 3239 request_submit(req); 3240 return req; 3241 } else { 3242 struct request *const req = request_new(base, handle, type, name, flags, user_callback, user_arg); 3243 if (!req) return NULL; 3244 request_submit(req); 3245 return req; 3246 } 3247 } 3248 3249 /* this is called when a request has failed to find a name. We need to check */ 3250 /* if it is part of a search and, if so, try the next name in the list */ 3251 /* returns: */ 3252 /* 0 another request has been submitted */ 3253 /* 1 no more requests needed */ 3254 static int 3255 search_try_next(struct evdns_request *const handle) { 3256 struct request *req = handle->current_req; 3257 struct evdns_base *base = req->base; 3258 struct request *newreq; 3259 ASSERT_LOCKED(base); 3260 if (handle->search_state) { 3261 /* it is part of a search */ 3262 char *new_name; 3263 handle->search_index++; 3264 if (handle->search_index >= handle->search_state->num_domains) { 3265 /* no more postfixes to try, however we may need to try */ 3266 /* this name without a postfix */ 3267 if (string_num_dots(handle->search_origname) < handle->search_state->ndots) { 3268 /* yep, we need to try it raw */ 3269 newreq = request_new(base, NULL, req->request_type, handle->search_origname, handle->search_flags, req->user_callback, req->user_pointer); 3270 log(EVDNS_LOG_DEBUG, "Search: trying raw query %s", handle->search_origname); 3271 if (newreq) { 3272 search_request_finished(handle); 3273 goto submit_next; 3274 } 3275 } 3276 return 1; 3277 } 3278 3279 new_name = search_make_new(handle->search_state, handle->search_index, handle->search_origname); 3280 if (!new_name) return 1; 3281 log(EVDNS_LOG_DEBUG, "Search: now trying %s (%d)", new_name, handle->search_index); 3282 newreq = request_new(base, NULL, req->request_type, new_name, handle->search_flags, req->user_callback, req->user_pointer); 3283 mm_free(new_name); 3284 if (!newreq) return 1; 3285 goto submit_next; 3286 } 3287 return 1; 3288 3289 submit_next: 3290 request_finished(req, &REQ_HEAD(req->base, req->trans_id), 0); 3291 handle->current_req = newreq; 3292 newreq->handle = handle; 3293 request_submit(newreq); 3294 return 0; 3295 } 3296 3297 static void 3298 search_request_finished(struct evdns_request *const handle) { 3299 ASSERT_LOCKED(handle->current_req->base); 3300 if (handle->search_state) { 3301 search_state_decref(handle->search_state); 3302 handle->search_state = NULL; 3303 } 3304 if (handle->search_origname) { 3305 mm_free(handle->search_origname); 3306 handle->search_origname = NULL; 3307 } 3308 } 3309 3310 /* ================================================================= */ 3311 /* Parsing resolv.conf files */ 3312 3313 static void 3314 evdns_resolv_set_defaults(struct evdns_base *base, int flags) { 3315 /* if the file isn't found then we assume a local resolver */ 3316 ASSERT_LOCKED(base); 3317 if (flags & DNS_OPTION_SEARCH) search_set_from_hostname(base); 3318 if (flags & DNS_OPTION_NAMESERVERS) evdns_base_nameserver_ip_add(base,"127.0.0.1"); 3319 } 3320 3321 #ifndef EVENT__HAVE_STRTOK_R 3322 static char * 3323 strtok_r(char *s, const char *delim, char **state) { 3324 char *cp, *start; 3325 start = cp = s ? s : *state; 3326 if (!cp) 3327 return NULL; 3328 while (*cp && !strchr(delim, *cp)) 3329 ++cp; 3330 if (!*cp) { 3331 if (cp == start) 3332 return NULL; 3333 *state = NULL; 3334 return start; 3335 } else { 3336 *cp++ = '\0'; 3337 *state = cp; 3338 return start; 3339 } 3340 } 3341 #endif 3342 3343 /* helper version of atoi which returns -1 on error */ 3344 static int 3345 strtoint(const char *const str) 3346 { 3347 char *endptr; 3348 const int r = strtol(str, &endptr, 10); 3349 if (*endptr) return -1; 3350 return r; 3351 } 3352 3353 /* Parse a number of seconds into a timeval; return -1 on error. */ 3354 static int 3355 evdns_strtotimeval(const char *const str, struct timeval *out) 3356 { 3357 double d; 3358 char *endptr; 3359 d = strtod(str, &endptr); 3360 if (*endptr) return -1; 3361 if (d < 0) return -1; 3362 out->tv_sec = (int) d; 3363 out->tv_usec = (int) ((d - (int) d)*1000000); 3364 if (out->tv_sec == 0 && out->tv_usec < 1000) /* less than 1 msec */ 3365 return -1; 3366 return 0; 3367 } 3368 3369 /* helper version of atoi that returns -1 on error and clips to bounds. */ 3370 static int 3371 strtoint_clipped(const char *const str, int min, int max) 3372 { 3373 int r = strtoint(str); 3374 if (r == -1) 3375 return r; 3376 else if (r<min) 3377 return min; 3378 else if (r>max) 3379 return max; 3380 else 3381 return r; 3382 } 3383 3384 static int 3385 evdns_base_set_max_requests_inflight(struct evdns_base *base, int maxinflight) 3386 { 3387 int old_n_heads = base->n_req_heads, n_heads; 3388 struct request **old_heads = base->req_heads, **new_heads, *req; 3389 int i; 3390 3391 ASSERT_LOCKED(base); 3392 if (maxinflight < 1) 3393 maxinflight = 1; 3394 n_heads = (maxinflight+4) / 5; 3395 EVUTIL_ASSERT(n_heads > 0); 3396 new_heads = mm_calloc(n_heads, sizeof(struct request*)); 3397 if (!new_heads) 3398 return (-1); 3399 if (old_heads) { 3400 for (i = 0; i < old_n_heads; ++i) { 3401 while (old_heads[i]) { 3402 req = old_heads[i]; 3403 evdns_request_remove(req, &old_heads[i]); 3404 evdns_request_insert(req, &new_heads[req->trans_id % n_heads]); 3405 } 3406 } 3407 mm_free(old_heads); 3408 } 3409 base->req_heads = new_heads; 3410 base->n_req_heads = n_heads; 3411 base->global_max_requests_inflight = maxinflight; 3412 return (0); 3413 } 3414 3415 /* exported function */ 3416 int 3417 evdns_base_set_option(struct evdns_base *base, 3418 const char *option, const char *val) 3419 { 3420 int res; 3421 EVDNS_LOCK(base); 3422 res = evdns_base_set_option_impl(base, option, val, DNS_OPTIONS_ALL); 3423 EVDNS_UNLOCK(base); 3424 return res; 3425 } 3426 3427 static inline int 3428 str_matches_option(const char *s1, const char *optionname) 3429 { 3430 /* Option names are given as "option:" We accept either 'option' in 3431 * s1, or 'option:randomjunk'. The latter form is to implement the 3432 * resolv.conf parser. */ 3433 size_t optlen = strlen(optionname); 3434 size_t slen = strlen(s1); 3435 if (slen == optlen || slen == optlen - 1) 3436 return !strncmp(s1, optionname, slen); 3437 else if (slen > optlen) 3438 return !strncmp(s1, optionname, optlen); 3439 else 3440 return 0; 3441 } 3442 3443 static int 3444 evdns_base_set_option_impl(struct evdns_base *base, 3445 const char *option, const char *val, int flags) 3446 { 3447 ASSERT_LOCKED(base); 3448 if (str_matches_option(option, "ndots:")) { 3449 const int ndots = strtoint(val); 3450 if (ndots == -1) return -1; 3451 if (!(flags & DNS_OPTION_SEARCH)) return 0; 3452 log(EVDNS_LOG_DEBUG, "Setting ndots to %d", ndots); 3453 if (!base->global_search_state) base->global_search_state = search_state_new(); 3454 if (!base->global_search_state) return -1; 3455 base->global_search_state->ndots = ndots; 3456 } else if (str_matches_option(option, "timeout:")) { 3457 struct timeval tv; 3458 if (evdns_strtotimeval(val, &tv) == -1) return -1; 3459 if (!(flags & DNS_OPTION_MISC)) return 0; 3460 log(EVDNS_LOG_DEBUG, "Setting timeout to %s", val); 3461 memcpy(&base->global_timeout, &tv, sizeof(struct timeval)); 3462 } else if (str_matches_option(option, "getaddrinfo-allow-skew:")) { 3463 struct timeval tv; 3464 if (evdns_strtotimeval(val, &tv) == -1) return -1; 3465 if (!(flags & DNS_OPTION_MISC)) return 0; 3466 log(EVDNS_LOG_DEBUG, "Setting getaddrinfo-allow-skew to %s", 3467 val); 3468 memcpy(&base->global_getaddrinfo_allow_skew, &tv, 3469 sizeof(struct timeval)); 3470 } else if (str_matches_option(option, "max-timeouts:")) { 3471 const int maxtimeout = strtoint_clipped(val, 1, 255); 3472 if (maxtimeout == -1) return -1; 3473 if (!(flags & DNS_OPTION_MISC)) return 0; 3474 log(EVDNS_LOG_DEBUG, "Setting maximum allowed timeouts to %d", 3475 maxtimeout); 3476 base->global_max_nameserver_timeout = maxtimeout; 3477 } else if (str_matches_option(option, "max-inflight:")) { 3478 const int maxinflight = strtoint_clipped(val, 1, 65000); 3479 if (maxinflight == -1) return -1; 3480 if (!(flags & DNS_OPTION_MISC)) return 0; 3481 log(EVDNS_LOG_DEBUG, "Setting maximum inflight requests to %d", 3482 maxinflight); 3483 evdns_base_set_max_requests_inflight(base, maxinflight); 3484 } else if (str_matches_option(option, "attempts:")) { 3485 int retries = strtoint(val); 3486 if (retries == -1) return -1; 3487 if (retries > 255) retries = 255; 3488 if (!(flags & DNS_OPTION_MISC)) return 0; 3489 log(EVDNS_LOG_DEBUG, "Setting retries to %d", retries); 3490 base->global_max_retransmits = retries; 3491 } else if (str_matches_option(option, "randomize-case:")) { 3492 int randcase = strtoint(val); 3493 if (!(flags & DNS_OPTION_MISC)) return 0; 3494 base->global_randomize_case = randcase; 3495 } else if (str_matches_option(option, "bind-to:")) { 3496 /* XXX This only applies to successive nameservers, not 3497 * to already-configured ones. We might want to fix that. */ 3498 int len = sizeof(base->global_outgoing_address); 3499 if (!(flags & DNS_OPTION_NAMESERVERS)) return 0; 3500 if (evutil_parse_sockaddr_port(val, 3501 (struct sockaddr*)&base->global_outgoing_address, &len)) 3502 return -1; 3503 base->global_outgoing_addrlen = len; 3504 } else if (str_matches_option(option, "initial-probe-timeout:")) { 3505 struct timeval tv; 3506 if (evdns_strtotimeval(val, &tv) == -1) return -1; 3507 if (tv.tv_sec > 3600) 3508 tv.tv_sec = 3600; 3509 if (!(flags & DNS_OPTION_MISC)) return 0; 3510 log(EVDNS_LOG_DEBUG, "Setting initial probe timeout to %s", 3511 val); 3512 memcpy(&base->global_nameserver_probe_initial_timeout, &tv, 3513 sizeof(tv)); 3514 } 3515 return 0; 3516 } 3517 3518 int 3519 evdns_set_option(const char *option, const char *val, int flags) 3520 { 3521 if (!current_base) 3522 current_base = evdns_base_new(NULL, 0); 3523 return evdns_base_set_option(current_base, option, val); 3524 } 3525 3526 static void 3527 resolv_conf_parse_line(struct evdns_base *base, char *const start, int flags) { 3528 char *strtok_state; 3529 static const char *const delims = " \t"; 3530 #define NEXT_TOKEN strtok_r(NULL, delims, &strtok_state) 3531 3532 3533 char *const first_token = strtok_r(start, delims, &strtok_state); 3534 ASSERT_LOCKED(base); 3535 if (!first_token) return; 3536 3537 if (!strcmp(first_token, "nameserver") && (flags & DNS_OPTION_NAMESERVERS)) { 3538 const char *const nameserver = NEXT_TOKEN; 3539 3540 if (nameserver) 3541 evdns_base_nameserver_ip_add(base, nameserver); 3542 } else if (!strcmp(first_token, "domain") && (flags & DNS_OPTION_SEARCH)) { 3543 const char *const domain = NEXT_TOKEN; 3544 if (domain) { 3545 search_postfix_clear(base); 3546 search_postfix_add(base, domain); 3547 } 3548 } else if (!strcmp(first_token, "search") && (flags & DNS_OPTION_SEARCH)) { 3549 const char *domain; 3550 search_postfix_clear(base); 3551 3552 while ((domain = NEXT_TOKEN)) { 3553 search_postfix_add(base, domain); 3554 } 3555 search_reverse(base); 3556 } else if (!strcmp(first_token, "options")) { 3557 const char *option; 3558 while ((option = NEXT_TOKEN)) { 3559 const char *val = strchr(option, ':'); 3560 evdns_base_set_option_impl(base, option, val ? val+1 : "", flags); 3561 } 3562 } 3563 #undef NEXT_TOKEN 3564 } 3565 3566 /* exported function */ 3567 /* returns: */ 3568 /* 0 no errors */ 3569 /* 1 failed to open file */ 3570 /* 2 failed to stat file */ 3571 /* 3 file too large */ 3572 /* 4 out of memory */ 3573 /* 5 short read from file */ 3574 int 3575 evdns_base_resolv_conf_parse(struct evdns_base *base, int flags, const char *const filename) { 3576 int res; 3577 EVDNS_LOCK(base); 3578 res = evdns_base_resolv_conf_parse_impl(base, flags, filename); 3579 EVDNS_UNLOCK(base); 3580 return res; 3581 } 3582 3583 static char * 3584 evdns_get_default_hosts_filename(void) 3585 { 3586 #ifdef _WIN32 3587 /* Windows is a little coy about where it puts its configuration 3588 * files. Sure, they're _usually_ in C:\windows\system32, but 3589 * there's no reason in principle they couldn't be in 3590 * W:\hoboken chicken emergency\ 3591 */ 3592 char path[MAX_PATH+1]; 3593 static const char hostfile[] = "\\drivers\\etc\\hosts"; 3594 char *path_out; 3595 size_t len_out; 3596 3597 if (! SHGetSpecialFolderPathA(NULL, path, CSIDL_SYSTEM, 0)) 3598 return NULL; 3599 len_out = strlen(path)+strlen(hostfile)+1; 3600 path_out = mm_malloc(len_out); 3601 evutil_snprintf(path_out, len_out, "%s%s", path, hostfile); 3602 return path_out; 3603 #else 3604 return mm_strdup("/etc/hosts"); 3605 #endif 3606 } 3607 3608 static int 3609 evdns_base_resolv_conf_parse_impl(struct evdns_base *base, int flags, const char *const filename) { 3610 size_t n; 3611 char *resolv; 3612 char *start; 3613 int err = 0; 3614 3615 log(EVDNS_LOG_DEBUG, "Parsing resolv.conf file %s", filename); 3616 3617 if (flags & DNS_OPTION_HOSTSFILE) { 3618 char *fname = evdns_get_default_hosts_filename(); 3619 evdns_base_load_hosts(base, fname); 3620 if (fname) 3621 mm_free(fname); 3622 } 3623 3624 if ((err = evutil_read_file_(filename, &resolv, &n, 0)) < 0) { 3625 if (err == -1) { 3626 /* No file. */ 3627 evdns_resolv_set_defaults(base, flags); 3628 return 1; 3629 } else { 3630 return 2; 3631 } 3632 } 3633 3634 start = resolv; 3635 for (;;) { 3636 char *const newline = strchr(start, '\n'); 3637 if (!newline) { 3638 resolv_conf_parse_line(base, start, flags); 3639 break; 3640 } else { 3641 *newline = 0; 3642 resolv_conf_parse_line(base, start, flags); 3643 start = newline + 1; 3644 } 3645 } 3646 3647 if (!base->server_head && (flags & DNS_OPTION_NAMESERVERS)) { 3648 /* no nameservers were configured. */ 3649 evdns_base_nameserver_ip_add(base, "127.0.0.1"); 3650 err = 6; 3651 } 3652 if (flags & DNS_OPTION_SEARCH && (!base->global_search_state || base->global_search_state->num_domains == 0)) { 3653 search_set_from_hostname(base); 3654 } 3655 3656 mm_free(resolv); 3657 return err; 3658 } 3659 3660 int 3661 evdns_resolv_conf_parse(int flags, const char *const filename) { 3662 if (!current_base) 3663 current_base = evdns_base_new(NULL, 0); 3664 return evdns_base_resolv_conf_parse(current_base, flags, filename); 3665 } 3666 3667 3668 #ifdef _WIN32 3669 /* Add multiple nameservers from a space-or-comma-separated list. */ 3670 static int 3671 evdns_nameserver_ip_add_line(struct evdns_base *base, const char *ips) { 3672 const char *addr; 3673 char *buf; 3674 int r; 3675 ASSERT_LOCKED(base); 3676 while (*ips) { 3677 while (isspace(*ips) || *ips == ',' || *ips == '\t') 3678 ++ips; 3679 addr = ips; 3680 while (isdigit(*ips) || *ips == '.' || *ips == ':' || 3681 *ips=='[' || *ips==']') 3682 ++ips; 3683 buf = mm_malloc(ips-addr+1); 3684 if (!buf) return 4; 3685 memcpy(buf, addr, ips-addr); 3686 buf[ips-addr] = '\0'; 3687 r = evdns_base_nameserver_ip_add(base, buf); 3688 mm_free(buf); 3689 if (r) return r; 3690 } 3691 return 0; 3692 } 3693 3694 typedef DWORD(WINAPI *GetNetworkParams_fn_t)(FIXED_INFO *, DWORD*); 3695 3696 /* Use the windows GetNetworkParams interface in iphlpapi.dll to */ 3697 /* figure out what our nameservers are. */ 3698 static int 3699 load_nameservers_with_getnetworkparams(struct evdns_base *base) 3700 { 3701 /* Based on MSDN examples and inspection of c-ares code. */ 3702 FIXED_INFO *fixed; 3703 HMODULE handle = 0; 3704 ULONG size = sizeof(FIXED_INFO); 3705 void *buf = NULL; 3706 int status = 0, r, added_any; 3707 IP_ADDR_STRING *ns; 3708 GetNetworkParams_fn_t fn; 3709 3710 ASSERT_LOCKED(base); 3711 if (!(handle = evutil_load_windows_system_library_( 3712 TEXT("iphlpapi.dll")))) { 3713 log(EVDNS_LOG_WARN, "Could not open iphlpapi.dll"); 3714 status = -1; 3715 goto done; 3716 } 3717 if (!(fn = (GetNetworkParams_fn_t) GetProcAddress(handle, "GetNetworkParams"))) { 3718 log(EVDNS_LOG_WARN, "Could not get address of function."); 3719 status = -1; 3720 goto done; 3721 } 3722 3723 buf = mm_malloc(size); 3724 if (!buf) { status = 4; goto done; } 3725 fixed = buf; 3726 r = fn(fixed, &size); 3727 if (r != ERROR_SUCCESS && r != ERROR_BUFFER_OVERFLOW) { 3728 status = -1; 3729 goto done; 3730 } 3731 if (r != ERROR_SUCCESS) { 3732 mm_free(buf); 3733 buf = mm_malloc(size); 3734 if (!buf) { status = 4; goto done; } 3735 fixed = buf; 3736 r = fn(fixed, &size); 3737 if (r != ERROR_SUCCESS) { 3738 log(EVDNS_LOG_DEBUG, "fn() failed."); 3739 status = -1; 3740 goto done; 3741 } 3742 } 3743 3744 EVUTIL_ASSERT(fixed); 3745 added_any = 0; 3746 ns = &(fixed->DnsServerList); 3747 while (ns) { 3748 r = evdns_nameserver_ip_add_line(base, ns->IpAddress.String); 3749 if (r) { 3750 log(EVDNS_LOG_DEBUG,"Could not add nameserver %s to list,error: %d", 3751 (ns->IpAddress.String),(int)GetLastError()); 3752 status = r; 3753 } else { 3754 ++added_any; 3755 log(EVDNS_LOG_DEBUG,"Successfully added %s as nameserver",ns->IpAddress.String); 3756 } 3757 3758 ns = ns->Next; 3759 } 3760 3761 if (!added_any) { 3762 log(EVDNS_LOG_DEBUG, "No nameservers added."); 3763 if (status == 0) 3764 status = -1; 3765 } else { 3766 status = 0; 3767 } 3768 3769 done: 3770 if (buf) 3771 mm_free(buf); 3772 if (handle) 3773 FreeLibrary(handle); 3774 return status; 3775 } 3776 3777 static int 3778 config_nameserver_from_reg_key(struct evdns_base *base, HKEY key, const TCHAR *subkey) 3779 { 3780 char *buf; 3781 DWORD bufsz = 0, type = 0; 3782 int status = 0; 3783 3784 ASSERT_LOCKED(base); 3785 if (RegQueryValueEx(key, subkey, 0, &type, NULL, &bufsz) 3786 != ERROR_MORE_DATA) 3787 return -1; 3788 if (!(buf = mm_malloc(bufsz))) 3789 return -1; 3790 3791 if (RegQueryValueEx(key, subkey, 0, &type, (LPBYTE)buf, &bufsz) 3792 == ERROR_SUCCESS && bufsz > 1) { 3793 status = evdns_nameserver_ip_add_line(base,buf); 3794 } 3795 3796 mm_free(buf); 3797 return status; 3798 } 3799 3800 #define SERVICES_KEY TEXT("System\\CurrentControlSet\\Services\\") 3801 #define WIN_NS_9X_KEY SERVICES_KEY TEXT("VxD\\MSTCP") 3802 #define WIN_NS_NT_KEY SERVICES_KEY TEXT("Tcpip\\Parameters") 3803 3804 static int 3805 load_nameservers_from_registry(struct evdns_base *base) 3806 { 3807 int found = 0; 3808 int r; 3809 #define TRY(k, name) \ 3810 if (!found && config_nameserver_from_reg_key(base,k,TEXT(name)) == 0) { \ 3811 log(EVDNS_LOG_DEBUG,"Found nameservers in %s/%s",#k,name); \ 3812 found = 1; \ 3813 } else if (!found) { \ 3814 log(EVDNS_LOG_DEBUG,"Didn't find nameservers in %s/%s", \ 3815 #k,#name); \ 3816 } 3817 3818 ASSERT_LOCKED(base); 3819 3820 if (((int)GetVersion()) > 0) { /* NT */ 3821 HKEY nt_key = 0, interfaces_key = 0; 3822 3823 if (RegOpenKeyEx(HKEY_LOCAL_MACHINE, WIN_NS_NT_KEY, 0, 3824 KEY_READ, &nt_key) != ERROR_SUCCESS) { 3825 log(EVDNS_LOG_DEBUG,"Couldn't open nt key, %d",(int)GetLastError()); 3826 return -1; 3827 } 3828 r = RegOpenKeyEx(nt_key, TEXT("Interfaces"), 0, 3829 KEY_QUERY_VALUE|KEY_ENUMERATE_SUB_KEYS, 3830 &interfaces_key); 3831 if (r != ERROR_SUCCESS) { 3832 log(EVDNS_LOG_DEBUG,"Couldn't open interfaces key, %d",(int)GetLastError()); 3833 return -1; 3834 } 3835 TRY(nt_key, "NameServer"); 3836 TRY(nt_key, "DhcpNameServer"); 3837 TRY(interfaces_key, "NameServer"); 3838 TRY(interfaces_key, "DhcpNameServer"); 3839 RegCloseKey(interfaces_key); 3840 RegCloseKey(nt_key); 3841 } else { 3842 HKEY win_key = 0; 3843 if (RegOpenKeyEx(HKEY_LOCAL_MACHINE, WIN_NS_9X_KEY, 0, 3844 KEY_READ, &win_key) != ERROR_SUCCESS) { 3845 log(EVDNS_LOG_DEBUG, "Couldn't open registry key, %d", (int)GetLastError()); 3846 return -1; 3847 } 3848 TRY(win_key, "NameServer"); 3849 RegCloseKey(win_key); 3850 } 3851 3852 if (found == 0) { 3853 log(EVDNS_LOG_WARN,"Didn't find any nameservers."); 3854 } 3855 3856 return found ? 0 : -1; 3857 #undef TRY 3858 } 3859 3860 int 3861 evdns_base_config_windows_nameservers(struct evdns_base *base) 3862 { 3863 int r; 3864 char *fname; 3865 if (base == NULL) 3866 base = current_base; 3867 if (base == NULL) 3868 return -1; 3869 EVDNS_LOCK(base); 3870 fname = evdns_get_default_hosts_filename(); 3871 log(EVDNS_LOG_DEBUG, "Loading hosts entries from %s", fname); 3872 evdns_base_load_hosts(base, fname); 3873 if (fname) 3874 mm_free(fname); 3875 3876 if (load_nameservers_with_getnetworkparams(base) == 0) { 3877 EVDNS_UNLOCK(base); 3878 return 0; 3879 } 3880 r = load_nameservers_from_registry(base); 3881 3882 EVDNS_UNLOCK(base); 3883 return r; 3884 } 3885 3886 int 3887 evdns_config_windows_nameservers(void) 3888 { 3889 if (!current_base) { 3890 current_base = evdns_base_new(NULL, 1); 3891 return current_base == NULL ? -1 : 0; 3892 } else { 3893 return evdns_base_config_windows_nameservers(current_base); 3894 } 3895 } 3896 #endif 3897 3898 struct evdns_base * 3899 evdns_base_new(struct event_base *event_base, int flags) 3900 { 3901 struct evdns_base *base; 3902 3903 if (evutil_secure_rng_init() < 0) { 3904 log(EVDNS_LOG_WARN, "Unable to seed random number generator; " 3905 "DNS can't run."); 3906 return NULL; 3907 } 3908 3909 /* Give the evutil library a hook into its evdns-enabled 3910 * functionality. We can't just call evdns_getaddrinfo directly or 3911 * else libevent-core will depend on libevent-extras. */ 3912 evutil_set_evdns_getaddrinfo_fn_(evdns_getaddrinfo); 3913 3914 base = mm_malloc(sizeof(struct evdns_base)); 3915 if (base == NULL) 3916 return (NULL); 3917 memset(base, 0, sizeof(struct evdns_base)); 3918 base->req_waiting_head = NULL; 3919 3920 EVTHREAD_ALLOC_LOCK(base->lock, EVTHREAD_LOCKTYPE_RECURSIVE); 3921 EVDNS_LOCK(base); 3922 3923 /* Set max requests inflight and allocate req_heads. */ 3924 base->req_heads = NULL; 3925 3926 evdns_base_set_max_requests_inflight(base, 64); 3927 3928 base->server_head = NULL; 3929 base->event_base = event_base; 3930 base->global_good_nameservers = base->global_requests_inflight = 3931 base->global_requests_waiting = 0; 3932 3933 base->global_timeout.tv_sec = 5; 3934 base->global_timeout.tv_usec = 0; 3935 base->global_max_reissues = 1; 3936 base->global_max_retransmits = 3; 3937 base->global_max_nameserver_timeout = 3; 3938 base->global_search_state = NULL; 3939 base->global_randomize_case = 1; 3940 base->global_getaddrinfo_allow_skew.tv_sec = 3; 3941 base->global_getaddrinfo_allow_skew.tv_usec = 0; 3942 base->global_nameserver_probe_initial_timeout.tv_sec = 10; 3943 base->global_nameserver_probe_initial_timeout.tv_usec = 0; 3944 3945 TAILQ_INIT(&base->hostsdb); 3946 3947 #define EVDNS_BASE_ALL_FLAGS (0x8001) 3948 if (flags & ~EVDNS_BASE_ALL_FLAGS) { 3949 flags = EVDNS_BASE_INITIALIZE_NAMESERVERS; 3950 log(EVDNS_LOG_WARN, 3951 "Unrecognized flag passed to evdns_base_new(). Assuming " 3952 "you meant EVDNS_BASE_INITIALIZE_NAMESERVERS."); 3953 } 3954 #undef EVDNS_BASE_ALL_FLAGS 3955 3956 if (flags & EVDNS_BASE_INITIALIZE_NAMESERVERS) { 3957 int r; 3958 #ifdef _WIN32 3959 r = evdns_base_config_windows_nameservers(base); 3960 #else 3961 r = evdns_base_resolv_conf_parse(base, DNS_OPTIONS_ALL, "/etc/resolv.conf"); 3962 #endif 3963 if (r == -1) { 3964 evdns_base_free_and_unlock(base, 0); 3965 return NULL; 3966 } 3967 } 3968 if (flags & EVDNS_BASE_DISABLE_WHEN_INACTIVE) { 3969 base->disable_when_inactive = 1; 3970 } 3971 3972 EVDNS_UNLOCK(base); 3973 return base; 3974 } 3975 3976 int 3977 evdns_init(void) 3978 { 3979 struct evdns_base *base = evdns_base_new(NULL, 1); 3980 if (base) { 3981 current_base = base; 3982 return 0; 3983 } else { 3984 return -1; 3985 } 3986 } 3987 3988 const char * 3989 evdns_err_to_string(int err) 3990 { 3991 switch (err) { 3992 case DNS_ERR_NONE: return "no error"; 3993 case DNS_ERR_FORMAT: return "misformatted query"; 3994 case DNS_ERR_SERVERFAILED: return "server failed"; 3995 case DNS_ERR_NOTEXIST: return "name does not exist"; 3996 case DNS_ERR_NOTIMPL: return "query not implemented"; 3997 case DNS_ERR_REFUSED: return "refused"; 3998 3999 case DNS_ERR_TRUNCATED: return "reply truncated or ill-formed"; 4000 case DNS_ERR_UNKNOWN: return "unknown"; 4001 case DNS_ERR_TIMEOUT: return "request timed out"; 4002 case DNS_ERR_SHUTDOWN: return "dns subsystem shut down"; 4003 case DNS_ERR_CANCEL: return "dns request canceled"; 4004 case DNS_ERR_NODATA: return "no records in the reply"; 4005 default: return "[Unknown error code]"; 4006 } 4007 } 4008 4009 static void 4010 evdns_nameserver_free(struct nameserver *server) 4011 { 4012 if (server->socket >= 0) 4013 evutil_closesocket(server->socket); 4014 (void) event_del(&server->event); 4015 event_debug_unassign(&server->event); 4016 if (server->state == 0) 4017 (void) event_del(&server->timeout_event); 4018 if (server->probe_request) { 4019 evdns_cancel_request(server->base, server->probe_request); 4020 server->probe_request = NULL; 4021 } 4022 event_debug_unassign(&server->timeout_event); 4023 mm_free(server); 4024 } 4025 4026 static void 4027 evdns_base_free_and_unlock(struct evdns_base *base, int fail_requests) 4028 { 4029 struct nameserver *server, *server_next; 4030 struct search_domain *dom, *dom_next; 4031 int i; 4032 4033 /* Requires that we hold the lock. */ 4034 4035 /* TODO(nickm) we might need to refcount here. */ 4036 4037 for (server = base->server_head; server; server = server_next) { 4038 server_next = server->next; 4039 evdns_nameserver_free(server); 4040 if (server_next == base->server_head) 4041 break; 4042 } 4043 base->server_head = NULL; 4044 base->global_good_nameservers = 0; 4045 4046 for (i = 0; i < base->n_req_heads; ++i) { 4047 while (base->req_heads[i]) { 4048 if (fail_requests) 4049 reply_schedule_callback(base->req_heads[i], 0, DNS_ERR_SHUTDOWN, NULL); 4050 request_finished(base->req_heads[i], &REQ_HEAD(base, base->req_heads[i]->trans_id), 1); 4051 } 4052 } 4053 while (base->req_waiting_head) { 4054 if (fail_requests) 4055 reply_schedule_callback(base->req_waiting_head, 0, DNS_ERR_SHUTDOWN, NULL); 4056 request_finished(base->req_waiting_head, &base->req_waiting_head, 1); 4057 } 4058 base->global_requests_inflight = base->global_requests_waiting = 0; 4059 4060 4061 if (base->global_search_state) { 4062 for (dom = base->global_search_state->head; dom; dom = dom_next) { 4063 dom_next = dom->next; 4064 mm_free(dom); 4065 } 4066 mm_free(base->global_search_state); 4067 base->global_search_state = NULL; 4068 } 4069 4070 { 4071 struct hosts_entry *victim; 4072 while ((victim = TAILQ_FIRST(&base->hostsdb))) { 4073 TAILQ_REMOVE(&base->hostsdb, victim, next); 4074 mm_free(victim); 4075 } 4076 } 4077 4078 mm_free(base->req_heads); 4079 4080 EVDNS_UNLOCK(base); 4081 EVTHREAD_FREE_LOCK(base->lock, EVTHREAD_LOCKTYPE_RECURSIVE); 4082 4083 mm_free(base); 4084 } 4085 4086 void 4087 evdns_base_free(struct evdns_base *base, int fail_requests) 4088 { 4089 EVDNS_LOCK(base); 4090 evdns_base_free_and_unlock(base, fail_requests); 4091 } 4092 4093 void 4094 evdns_base_clear_host_addresses(struct evdns_base *base) 4095 { 4096 struct hosts_entry *victim; 4097 EVDNS_LOCK(base); 4098 while ((victim = TAILQ_FIRST(&base->hostsdb))) { 4099 TAILQ_REMOVE(&base->hostsdb, victim, next); 4100 mm_free(victim); 4101 } 4102 EVDNS_UNLOCK(base); 4103 } 4104 4105 void 4106 evdns_shutdown(int fail_requests) 4107 { 4108 if (current_base) { 4109 struct evdns_base *b = current_base; 4110 current_base = NULL; 4111 evdns_base_free(b, fail_requests); 4112 } 4113 evdns_log_fn = NULL; 4114 } 4115 4116 static int 4117 evdns_base_parse_hosts_line(struct evdns_base *base, char *line) 4118 { 4119 char *strtok_state; 4120 static const char *const delims = " \t"; 4121 char *const addr = strtok_r(line, delims, &strtok_state); 4122 char *hostname, *hash; 4123 struct sockaddr_storage ss; 4124 int socklen = sizeof(ss); 4125 ASSERT_LOCKED(base); 4126 4127 #define NEXT_TOKEN strtok_r(NULL, delims, &strtok_state) 4128 4129 if (!addr || *addr == '#') 4130 return 0; 4131 4132 memset(&ss, 0, sizeof(ss)); 4133 if (evutil_parse_sockaddr_port(addr, (struct sockaddr*)&ss, &socklen)<0) 4134 return -1; 4135 if (socklen > (int)sizeof(struct sockaddr_in6)) 4136 return -1; 4137 4138 if (sockaddr_getport((struct sockaddr*)&ss)) 4139 return -1; 4140 4141 while ((hostname = NEXT_TOKEN)) { 4142 struct hosts_entry *he; 4143 size_t namelen; 4144 if ((hash = strchr(hostname, '#'))) { 4145 if (hash == hostname) 4146 return 0; 4147 *hash = '\0'; 4148 } 4149 4150 namelen = strlen(hostname); 4151 4152 he = mm_calloc(1, sizeof(struct hosts_entry)+namelen); 4153 if (!he) 4154 return -1; 4155 EVUTIL_ASSERT(socklen <= (int)sizeof(he->addr)); 4156 memcpy(&he->addr, &ss, socklen); 4157 memcpy(he->hostname, hostname, namelen+1); 4158 he->addrlen = socklen; 4159 4160 TAILQ_INSERT_TAIL(&base->hostsdb, he, next); 4161 4162 if (hash) 4163 return 0; 4164 } 4165 4166 return 0; 4167 #undef NEXT_TOKEN 4168 } 4169 4170 static int 4171 evdns_base_load_hosts_impl(struct evdns_base *base, const char *hosts_fname) 4172 { 4173 char *str=NULL, *cp, *eol; 4174 size_t len; 4175 int err=0; 4176 4177 ASSERT_LOCKED(base); 4178 4179 if (hosts_fname == NULL || 4180 (err = evutil_read_file_(hosts_fname, &str, &len, 0)) < 0) { 4181 char tmp[64]; 4182 strlcpy(tmp, "127.0.0.1 localhost", sizeof(tmp)); 4183 evdns_base_parse_hosts_line(base, tmp); 4184 strlcpy(tmp, "::1 localhost", sizeof(tmp)); 4185 evdns_base_parse_hosts_line(base, tmp); 4186 return err ? -1 : 0; 4187 } 4188 4189 /* This will break early if there is a NUL in the hosts file. 4190 * Probably not a problem.*/ 4191 cp = str; 4192 for (;;) { 4193 eol = strchr(cp, '\n'); 4194 4195 if (eol) { 4196 *eol = '\0'; 4197 evdns_base_parse_hosts_line(base, cp); 4198 cp = eol+1; 4199 } else { 4200 evdns_base_parse_hosts_line(base, cp); 4201 break; 4202 } 4203 } 4204 4205 mm_free(str); 4206 return 0; 4207 } 4208 4209 int 4210 evdns_base_load_hosts(struct evdns_base *base, const char *hosts_fname) 4211 { 4212 int res; 4213 if (!base) 4214 base = current_base; 4215 EVDNS_LOCK(base); 4216 res = evdns_base_load_hosts_impl(base, hosts_fname); 4217 EVDNS_UNLOCK(base); 4218 return res; 4219 } 4220 4221 /* A single request for a getaddrinfo, either v4 or v6. */ 4222 struct getaddrinfo_subrequest { 4223 struct evdns_request *r; 4224 ev_uint32_t type; 4225 }; 4226 4227 /* State data used to implement an in-progress getaddrinfo. */ 4228 struct evdns_getaddrinfo_request { 4229 struct evdns_base *evdns_base; 4230 /* Copy of the modified 'hints' data that we'll use to build 4231 * answers. */ 4232 struct evutil_addrinfo hints; 4233 /* The callback to invoke when we're done */ 4234 evdns_getaddrinfo_cb user_cb; 4235 /* User-supplied data to give to the callback. */ 4236 void *user_data; 4237 /* The port to use when building sockaddrs. */ 4238 ev_uint16_t port; 4239 /* The sub_request for an A record (if any) */ 4240 struct getaddrinfo_subrequest ipv4_request; 4241 /* The sub_request for an AAAA record (if any) */ 4242 struct getaddrinfo_subrequest ipv6_request; 4243 4244 /* The cname result that we were told (if any) */ 4245 char *cname_result; 4246 4247 /* If we have one request answered and one request still inflight, 4248 * then this field holds the answer from the first request... */ 4249 struct evutil_addrinfo *pending_result; 4250 /* And this event is a timeout that will tell us to cancel the second 4251 * request if it's taking a long time. */ 4252 struct event timeout; 4253 4254 /* And this field holds the error code from the first request... */ 4255 int pending_error; 4256 /* If this is set, the user canceled this request. */ 4257 unsigned user_canceled : 1; 4258 /* If this is set, the user can no longer cancel this request; we're 4259 * just waiting for the free. */ 4260 unsigned request_done : 1; 4261 }; 4262 4263 /* Convert an evdns errors to the equivalent getaddrinfo error. */ 4264 static int 4265 evdns_err_to_getaddrinfo_err(int e1) 4266 { 4267 /* XXX Do this better! */ 4268 if (e1 == DNS_ERR_NONE) 4269 return 0; 4270 else if (e1 == DNS_ERR_NOTEXIST) 4271 return EVUTIL_EAI_NONAME; 4272 else 4273 return EVUTIL_EAI_FAIL; 4274 } 4275 4276 /* Return the more informative of two getaddrinfo errors. */ 4277 static int 4278 getaddrinfo_merge_err(int e1, int e2) 4279 { 4280 /* XXXX be cleverer here. */ 4281 if (e1 == 0) 4282 return e2; 4283 else 4284 return e1; 4285 } 4286 4287 static void 4288 free_getaddrinfo_request(struct evdns_getaddrinfo_request *data) 4289 { 4290 /* DO NOT CALL this if either of the requests is pending. Only once 4291 * both callbacks have been invoked is it safe to free the request */ 4292 if (data->pending_result) 4293 evutil_freeaddrinfo(data->pending_result); 4294 if (data->cname_result) 4295 mm_free(data->cname_result); 4296 event_del(&data->timeout); 4297 mm_free(data); 4298 return; 4299 } 4300 4301 static void 4302 add_cname_to_reply(struct evdns_getaddrinfo_request *data, 4303 struct evutil_addrinfo *ai) 4304 { 4305 if (data->cname_result && ai) { 4306 ai->ai_canonname = data->cname_result; 4307 data->cname_result = NULL; 4308 } 4309 } 4310 4311 /* Callback: invoked when one request in a mixed-format A/AAAA getaddrinfo 4312 * request has finished, but the other one took too long to answer. Pass 4313 * along the answer we got, and cancel the other request. 4314 */ 4315 static void 4316 evdns_getaddrinfo_timeout_cb(evutil_socket_t fd, short what, void *ptr) 4317 { 4318 int v4_timedout = 0, v6_timedout = 0; 4319 struct evdns_getaddrinfo_request *data = ptr; 4320 4321 /* Cancel any pending requests, and note which one */ 4322 if (data->ipv4_request.r) { 4323 /* XXXX This does nothing if the request's callback is already 4324 * running (pending_cb is set). */ 4325 evdns_cancel_request(NULL, data->ipv4_request.r); 4326 v4_timedout = 1; 4327 EVDNS_LOCK(data->evdns_base); 4328 ++data->evdns_base->getaddrinfo_ipv4_timeouts; 4329 EVDNS_UNLOCK(data->evdns_base); 4330 } 4331 if (data->ipv6_request.r) { 4332 /* XXXX This does nothing if the request's callback is already 4333 * running (pending_cb is set). */ 4334 evdns_cancel_request(NULL, data->ipv6_request.r); 4335 v6_timedout = 1; 4336 EVDNS_LOCK(data->evdns_base); 4337 ++data->evdns_base->getaddrinfo_ipv6_timeouts; 4338 EVDNS_UNLOCK(data->evdns_base); 4339 } 4340 4341 /* We only use this timeout callback when we have an answer for 4342 * one address. */ 4343 EVUTIL_ASSERT(!v4_timedout || !v6_timedout); 4344 4345 /* Report the outcome of the other request that didn't time out. */ 4346 if (data->pending_result) { 4347 add_cname_to_reply(data, data->pending_result); 4348 data->user_cb(0, data->pending_result, data->user_data); 4349 data->pending_result = NULL; 4350 } else { 4351 int e = data->pending_error; 4352 if (!e) 4353 e = EVUTIL_EAI_AGAIN; 4354 data->user_cb(e, NULL, data->user_data); 4355 } 4356 4357 data->user_cb = NULL; /* prevent double-call if evdns callbacks are 4358 * in-progress. XXXX It would be better if this 4359 * weren't necessary. */ 4360 4361 if (!v4_timedout && !v6_timedout) { 4362 /* should be impossible? XXXX */ 4363 free_getaddrinfo_request(data); 4364 } 4365 } 4366 4367 static int 4368 evdns_getaddrinfo_set_timeout(struct evdns_base *evdns_base, 4369 struct evdns_getaddrinfo_request *data) 4370 { 4371 return event_add(&data->timeout, &evdns_base->global_getaddrinfo_allow_skew); 4372 } 4373 4374 static inline int 4375 evdns_result_is_answer(int result) 4376 { 4377 return (result != DNS_ERR_NOTIMPL && result != DNS_ERR_REFUSED && 4378 result != DNS_ERR_SERVERFAILED && result != DNS_ERR_CANCEL); 4379 } 4380 4381 static void 4382 evdns_getaddrinfo_gotresolve(int result, char type, int count, 4383 int ttl, void *addresses, void *arg) 4384 { 4385 int i; 4386 struct getaddrinfo_subrequest *req = arg; 4387 struct getaddrinfo_subrequest *other_req; 4388 struct evdns_getaddrinfo_request *data; 4389 4390 struct evutil_addrinfo *res; 4391 4392 struct sockaddr_in sin; 4393 struct sockaddr_in6 sin6; 4394 struct sockaddr *sa; 4395 int socklen, addrlen; 4396 void *addrp; 4397 int err; 4398 int user_canceled; 4399 4400 EVUTIL_ASSERT(req->type == DNS_IPv4_A || req->type == DNS_IPv6_AAAA); 4401 if (req->type == DNS_IPv4_A) { 4402 data = EVUTIL_UPCAST(req, struct evdns_getaddrinfo_request, ipv4_request); 4403 other_req = &data->ipv6_request; 4404 } else { 4405 data = EVUTIL_UPCAST(req, struct evdns_getaddrinfo_request, ipv6_request); 4406 other_req = &data->ipv4_request; 4407 } 4408 4409 EVDNS_LOCK(data->evdns_base); 4410 if (evdns_result_is_answer(result)) { 4411 if (req->type == DNS_IPv4_A) 4412 ++data->evdns_base->getaddrinfo_ipv4_answered; 4413 else 4414 ++data->evdns_base->getaddrinfo_ipv6_answered; 4415 } 4416 user_canceled = data->user_canceled; 4417 if (other_req->r == NULL) 4418 data->request_done = 1; 4419 EVDNS_UNLOCK(data->evdns_base); 4420 4421 req->r = NULL; 4422 4423 if (result == DNS_ERR_CANCEL && ! user_canceled) { 4424 /* Internal cancel request from timeout or internal error. 4425 * we already answered the user. */ 4426 if (other_req->r == NULL) 4427 free_getaddrinfo_request(data); 4428 return; 4429 } 4430 4431 if (data->user_cb == NULL) { 4432 /* We already answered. XXXX This shouldn't be needed; see 4433 * comments in evdns_getaddrinfo_timeout_cb */ 4434 free_getaddrinfo_request(data); 4435 return; 4436 } 4437 4438 if (result == DNS_ERR_NONE) { 4439 if (count == 0) 4440 err = EVUTIL_EAI_NODATA; 4441 else 4442 err = 0; 4443 } else { 4444 err = evdns_err_to_getaddrinfo_err(result); 4445 } 4446 4447 if (err) { 4448 /* Looks like we got an error. */ 4449 if (other_req->r) { 4450 /* The other request is still working; maybe it will 4451 * succeed. */ 4452 /* XXXX handle failure from set_timeout */ 4453 evdns_getaddrinfo_set_timeout(data->evdns_base, data); 4454 data->pending_error = err; 4455 return; 4456 } 4457 4458 if (user_canceled) { 4459 data->user_cb(EVUTIL_EAI_CANCEL, NULL, data->user_data); 4460 } else if (data->pending_result) { 4461 /* If we have an answer waiting, and we weren't 4462 * canceled, ignore this error. */ 4463 add_cname_to_reply(data, data->pending_result); 4464 data->user_cb(0, data->pending_result, data->user_data); 4465 data->pending_result = NULL; 4466 } else { 4467 if (data->pending_error) 4468 err = getaddrinfo_merge_err(err, 4469 data->pending_error); 4470 data->user_cb(err, NULL, data->user_data); 4471 } 4472 free_getaddrinfo_request(data); 4473 return; 4474 } else if (user_canceled) { 4475 if (other_req->r) { 4476 /* The other request is still working; let it hit this 4477 * callback with EVUTIL_EAI_CANCEL callback and report 4478 * the failure. */ 4479 return; 4480 } 4481 data->user_cb(EVUTIL_EAI_CANCEL, NULL, data->user_data); 4482 free_getaddrinfo_request(data); 4483 return; 4484 } 4485 4486 /* Looks like we got some answers. We should turn them into addrinfos 4487 * and then either queue those or return them all. */ 4488 EVUTIL_ASSERT(type == DNS_IPv4_A || type == DNS_IPv6_AAAA); 4489 4490 if (type == DNS_IPv4_A) { 4491 memset(&sin, 0, sizeof(sin)); 4492 sin.sin_family = AF_INET; 4493 sin.sin_port = htons(data->port); 4494 4495 sa = (struct sockaddr *)&sin; 4496 socklen = sizeof(sin); 4497 addrlen = 4; 4498 addrp = &sin.sin_addr.s_addr; 4499 } else { 4500 memset(&sin6, 0, sizeof(sin6)); 4501 sin6.sin6_family = AF_INET6; 4502 sin6.sin6_port = htons(data->port); 4503 4504 sa = (struct sockaddr *)&sin6; 4505 socklen = sizeof(sin6); 4506 addrlen = 16; 4507 addrp = &sin6.sin6_addr.s6_addr; 4508 } 4509 4510 res = NULL; 4511 for (i=0; i < count; ++i) { 4512 struct evutil_addrinfo *ai; 4513 memcpy(addrp, ((char*)addresses)+i*addrlen, addrlen); 4514 ai = evutil_new_addrinfo_(sa, socklen, &data->hints); 4515 if (!ai) { 4516 if (other_req->r) { 4517 evdns_cancel_request(NULL, other_req->r); 4518 } 4519 data->user_cb(EVUTIL_EAI_MEMORY, NULL, data->user_data); 4520 if (res) 4521 evutil_freeaddrinfo(res); 4522 4523 if (other_req->r == NULL) 4524 free_getaddrinfo_request(data); 4525 return; 4526 } 4527 res = evutil_addrinfo_append_(res, ai); 4528 } 4529 4530 if (other_req->r) { 4531 /* The other request is still in progress; wait for it */ 4532 /* XXXX handle failure from set_timeout */ 4533 evdns_getaddrinfo_set_timeout(data->evdns_base, data); 4534 data->pending_result = res; 4535 return; 4536 } else { 4537 /* The other request is done or never started; append its 4538 * results (if any) and return them. */ 4539 if (data->pending_result) { 4540 if (req->type == DNS_IPv4_A) 4541 res = evutil_addrinfo_append_(res, 4542 data->pending_result); 4543 else 4544 res = evutil_addrinfo_append_( 4545 data->pending_result, res); 4546 data->pending_result = NULL; 4547 } 4548 4549 /* Call the user callback. */ 4550 add_cname_to_reply(data, res); 4551 data->user_cb(0, res, data->user_data); 4552 4553 /* Free data. */ 4554 free_getaddrinfo_request(data); 4555 } 4556 } 4557 4558 static struct hosts_entry * 4559 find_hosts_entry(struct evdns_base *base, const char *hostname, 4560 struct hosts_entry *find_after) 4561 { 4562 struct hosts_entry *e; 4563 4564 if (find_after) 4565 e = TAILQ_NEXT(find_after, next); 4566 else 4567 e = TAILQ_FIRST(&base->hostsdb); 4568 4569 for (; e; e = TAILQ_NEXT(e, next)) { 4570 if (!evutil_ascii_strcasecmp(e->hostname, hostname)) 4571 return e; 4572 } 4573 return NULL; 4574 } 4575 4576 static int 4577 evdns_getaddrinfo_fromhosts(struct evdns_base *base, 4578 const char *nodename, struct evutil_addrinfo *hints, ev_uint16_t port, 4579 struct evutil_addrinfo **res) 4580 { 4581 int n_found = 0; 4582 struct hosts_entry *e; 4583 struct evutil_addrinfo *ai=NULL; 4584 int f = hints->ai_family; 4585 4586 EVDNS_LOCK(base); 4587 for (e = find_hosts_entry(base, nodename, NULL); e; 4588 e = find_hosts_entry(base, nodename, e)) { 4589 struct evutil_addrinfo *ai_new; 4590 ++n_found; 4591 if ((e->addr.sa.sa_family == AF_INET && f == PF_INET6) || 4592 (e->addr.sa.sa_family == AF_INET6 && f == PF_INET)) 4593 continue; 4594 ai_new = evutil_new_addrinfo_(&e->addr.sa, e->addrlen, hints); 4595 if (!ai_new) { 4596 n_found = 0; 4597 goto out; 4598 } 4599 sockaddr_setport(ai_new->ai_addr, port); 4600 ai = evutil_addrinfo_append_(ai, ai_new); 4601 } 4602 EVDNS_UNLOCK(base); 4603 out: 4604 if (n_found) { 4605 /* Note that we return an empty answer if we found entries for 4606 * this hostname but none were of the right address type. */ 4607 *res = ai; 4608 return 0; 4609 } else { 4610 if (ai) 4611 evutil_freeaddrinfo(ai); 4612 return -1; 4613 } 4614 } 4615 4616 struct evdns_getaddrinfo_request * 4617 evdns_getaddrinfo(struct evdns_base *dns_base, 4618 const char *nodename, const char *servname, 4619 const struct evutil_addrinfo *hints_in, 4620 evdns_getaddrinfo_cb cb, void *arg) 4621 { 4622 struct evdns_getaddrinfo_request *data; 4623 struct evutil_addrinfo hints; 4624 struct evutil_addrinfo *res = NULL; 4625 int err; 4626 int port = 0; 4627 int want_cname = 0; 4628 4629 if (!dns_base) { 4630 dns_base = current_base; 4631 if (!dns_base) { 4632 log(EVDNS_LOG_WARN, 4633 "Call to getaddrinfo_async with no " 4634 "evdns_base configured."); 4635 cb(EVUTIL_EAI_FAIL, NULL, arg); /* ??? better error? */ 4636 return NULL; 4637 } 4638 } 4639 4640 /* If we _must_ answer this immediately, do so. */ 4641 if ((hints_in && (hints_in->ai_flags & EVUTIL_AI_NUMERICHOST))) { 4642 res = NULL; 4643 err = evutil_getaddrinfo(nodename, servname, hints_in, &res); 4644 cb(err, res, arg); 4645 return NULL; 4646 } 4647 4648 if (hints_in) { 4649 memcpy(&hints, hints_in, sizeof(hints)); 4650 } else { 4651 memset(&hints, 0, sizeof(hints)); 4652 hints.ai_family = PF_UNSPEC; 4653 } 4654 4655 evutil_adjust_hints_for_addrconfig_(&hints); 4656 4657 /* Now try to see if we _can_ answer immediately. */ 4658 /* (It would be nice to do this by calling getaddrinfo directly, with 4659 * AI_NUMERICHOST, on plaforms that have it, but we can't: there isn't 4660 * a reliable way to distinguish the "that wasn't a numeric host!" case 4661 * from any other EAI_NONAME cases.) */ 4662 err = evutil_getaddrinfo_common_(nodename, servname, &hints, &res, &port); 4663 if (err != EVUTIL_EAI_NEED_RESOLVE) { 4664 cb(err, res, arg); 4665 return NULL; 4666 } 4667 4668 /* If there is an entry in the hosts file, we should give it now. */ 4669 if (!evdns_getaddrinfo_fromhosts(dns_base, nodename, &hints, port, &res)) { 4670 cb(0, res, arg); 4671 return NULL; 4672 } 4673 4674 /* Okay, things are serious now. We're going to need to actually 4675 * launch a request. 4676 */ 4677 data = mm_calloc(1,sizeof(struct evdns_getaddrinfo_request)); 4678 if (!data) { 4679 cb(EVUTIL_EAI_MEMORY, NULL, arg); 4680 return NULL; 4681 } 4682 4683 memcpy(&data->hints, &hints, sizeof(data->hints)); 4684 data->port = (ev_uint16_t)port; 4685 data->ipv4_request.type = DNS_IPv4_A; 4686 data->ipv6_request.type = DNS_IPv6_AAAA; 4687 data->user_cb = cb; 4688 data->user_data = arg; 4689 data->evdns_base = dns_base; 4690 4691 want_cname = (hints.ai_flags & EVUTIL_AI_CANONNAME); 4692 4693 /* If we are asked for a PF_UNSPEC address, we launch two requests in 4694 * parallel: one for an A address and one for an AAAA address. We 4695 * can't send just one request, since many servers only answer one 4696 * question per DNS request. 4697 * 4698 * Once we have the answer to one request, we allow for a short 4699 * timeout before we report it, to see if the other one arrives. If 4700 * they both show up in time, then we report both the answers. 4701 * 4702 * If too many addresses of one type time out or fail, we should stop 4703 * launching those requests. (XXX we don't do that yet.) 4704 */ 4705 4706 if (hints.ai_family != PF_INET6) { 4707 log(EVDNS_LOG_DEBUG, "Sending request for %s on ipv4 as %p", 4708 nodename, &data->ipv4_request); 4709 4710 data->ipv4_request.r = evdns_base_resolve_ipv4(dns_base, 4711 nodename, 0, evdns_getaddrinfo_gotresolve, 4712 &data->ipv4_request); 4713 if (want_cname && data->ipv4_request.r) 4714 data->ipv4_request.r->current_req->put_cname_in_ptr = 4715 &data->cname_result; 4716 } 4717 if (hints.ai_family != PF_INET) { 4718 log(EVDNS_LOG_DEBUG, "Sending request for %s on ipv6 as %p", 4719 nodename, &data->ipv6_request); 4720 4721 data->ipv6_request.r = evdns_base_resolve_ipv6(dns_base, 4722 nodename, 0, evdns_getaddrinfo_gotresolve, 4723 &data->ipv6_request); 4724 if (want_cname && data->ipv6_request.r) 4725 data->ipv6_request.r->current_req->put_cname_in_ptr = 4726 &data->cname_result; 4727 } 4728 4729 evtimer_assign(&data->timeout, dns_base->event_base, 4730 evdns_getaddrinfo_timeout_cb, data); 4731 4732 if (data->ipv4_request.r || data->ipv6_request.r) { 4733 return data; 4734 } else { 4735 mm_free(data); 4736 cb(EVUTIL_EAI_FAIL, NULL, arg); 4737 return NULL; 4738 } 4739 } 4740 4741 void 4742 evdns_getaddrinfo_cancel(struct evdns_getaddrinfo_request *data) 4743 { 4744 EVDNS_LOCK(data->evdns_base); 4745 if (data->request_done) { 4746 EVDNS_UNLOCK(data->evdns_base); 4747 return; 4748 } 4749 event_del(&data->timeout); 4750 data->user_canceled = 1; 4751 if (data->ipv4_request.r) 4752 evdns_cancel_request(data->evdns_base, data->ipv4_request.r); 4753 if (data->ipv6_request.r) 4754 evdns_cancel_request(data->evdns_base, data->ipv6_request.r); 4755 EVDNS_UNLOCK(data->evdns_base); 4756 } 4757