1 /* $NetBSD: evdns.c,v 1.5 2016/01/08 21:35:40 christos Exp $ */ 2 3 /* Copyright 2006-2007 Niels Provos 4 * Copyright 2007-2012 Nick Mathewson and Niels Provos 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 3. The name of the author may not be used to endorse or promote products 15 * derived from this software without specific prior written permission. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 18 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 19 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 20 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 21 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 22 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 27 */ 28 29 /* Based on software by Adam Langly. Adam's original message: 30 * 31 * Async DNS Library 32 * Adam Langley <agl@imperialviolet.org> 33 * http://www.imperialviolet.org/eventdns.html 34 * Public Domain code 35 * 36 * This software is Public Domain. To view a copy of the public domain dedication, 37 * visit http://creativecommons.org/licenses/publicdomain/ or send a letter to 38 * Creative Commons, 559 Nathan Abbott Way, Stanford, California 94305, USA. 39 * 40 * I ask and expect, but do not require, that all derivative works contain an 41 * attribution similar to: 42 * Parts developed by Adam Langley <agl@imperialviolet.org> 43 * 44 * You may wish to replace the word "Parts" with something else depending on 45 * the amount of original code. 46 * 47 * (Derivative works does not include programs which link against, run or include 48 * the source verbatim in their source distributions) 49 * 50 * Version: 0.1b 51 */ 52 53 #include "event2/event-config.h" 54 #include "evconfig-private.h" 55 56 #include <sys/types.h> 57 58 #ifndef _FORTIFY_SOURCE 59 #define _FORTIFY_SOURCE 3 60 #endif 61 62 #include <string.h> 63 #include <fcntl.h> 64 #ifdef EVENT__HAVE_SYS_TIME_H 65 #include <sys/time.h> 66 #endif 67 #ifdef EVENT__HAVE_STDINT_H 68 #include <stdint.h> 69 #endif 70 #include <stdlib.h> 71 #include <string.h> 72 #include <errno.h> 73 #ifdef EVENT__HAVE_UNISTD_H 74 #include <unistd.h> 75 #endif 76 #include <limits.h> 77 #include <sys/stat.h> 78 #include <stdio.h> 79 #include <stdarg.h> 80 #ifdef _WIN32 81 #include <winsock2.h> 82 #include <ws2tcpip.h> 83 #ifndef _WIN32_IE 84 #define _WIN32_IE 0x400 85 #endif 86 #include <shlobj.h> 87 #endif 88 89 #include "event2/dns.h" 90 #include "event2/dns_struct.h" 91 #include "event2/dns_compat.h" 92 #include "event2/util.h" 93 #include "event2/event.h" 94 #include "event2/event_struct.h" 95 #include "event2/thread.h" 96 97 #include "defer-internal.h" 98 #include "log-internal.h" 99 #include "mm-internal.h" 100 #include "strlcpy-internal.h" 101 #include "ipv6-internal.h" 102 #include "util-internal.h" 103 #include "evthread-internal.h" 104 #ifdef _WIN32 105 #include <ctype.h> 106 #include <winsock2.h> 107 #include <windows.h> 108 #include <iphlpapi.h> 109 #include <io.h> 110 #else 111 #include <sys/socket.h> 112 #include <netinet/in.h> 113 #include <arpa/inet.h> 114 #endif 115 116 #ifdef EVENT__HAVE_NETINET_IN6_H 117 #include <netinet/in6.h> 118 #endif 119 120 #define EVDNS_LOG_DEBUG EVENT_LOG_DEBUG 121 #define EVDNS_LOG_WARN EVENT_LOG_WARN 122 #define EVDNS_LOG_MSG EVENT_LOG_MSG 123 124 #ifndef HOST_NAME_MAX 125 #define HOST_NAME_MAX 255 126 #endif 127 128 #include <stdio.h> 129 130 #undef MIN 131 #define MIN(a,b) ((a)<(b)?(a):(b)) 132 133 #define ASSERT_VALID_REQUEST(req) \ 134 EVUTIL_ASSERT((req)->handle && (req)->handle->current_req == (req)) 135 136 #define u64 ev_uint64_t 137 #define u32 ev_uint32_t 138 #define u16 ev_uint16_t 139 #define u8 ev_uint8_t 140 141 /* maximum number of addresses from a single packet */ 142 /* that we bother recording */ 143 #define MAX_V4_ADDRS 32 144 #define MAX_V6_ADDRS 32 145 146 147 #define TYPE_A EVDNS_TYPE_A 148 #define TYPE_CNAME 5 149 #define TYPE_PTR EVDNS_TYPE_PTR 150 #define TYPE_SOA EVDNS_TYPE_SOA 151 #define TYPE_AAAA EVDNS_TYPE_AAAA 152 153 #define CLASS_INET EVDNS_CLASS_INET 154 155 /* Persistent handle. We keep this separate from 'struct request' since we 156 * need some object to last for as long as an evdns_request is outstanding so 157 * that it can be canceled, whereas a search request can lead to multiple 158 * 'struct request' instances being created over its lifetime. */ 159 struct evdns_request { 160 struct request *current_req; 161 struct evdns_base *base; 162 163 int pending_cb; /* Waiting for its callback to be invoked; not 164 * owned by event base any more. */ 165 166 /* elements used by the searching code */ 167 int search_index; 168 struct search_state *search_state; 169 char *search_origname; /* needs to be free()ed */ 170 int search_flags; 171 }; 172 173 struct request { 174 u8 *request; /* the dns packet data */ 175 u8 request_type; /* TYPE_PTR or TYPE_A or TYPE_AAAA */ 176 unsigned int request_len; 177 int reissue_count; 178 int tx_count; /* the number of times that this packet has been sent */ 179 void *user_pointer; /* the pointer given to us for this request */ 180 evdns_callback_type user_callback; 181 struct nameserver *ns; /* the server which we last sent it */ 182 183 /* these objects are kept in a circular list */ 184 /* XXX We could turn this into a CIRCLEQ. */ 185 struct request *next, *prev; 186 187 struct event timeout_event; 188 189 u16 trans_id; /* the transaction id */ 190 unsigned request_appended :1; /* true if the request pointer is data which follows this struct */ 191 unsigned transmit_me :1; /* needs to be transmitted */ 192 193 /* XXXX This is a horrible hack. */ 194 char **put_cname_in_ptr; /* store the cname here if we get one. */ 195 196 struct evdns_base *base; 197 198 struct evdns_request *handle; 199 }; 200 201 struct reply { 202 unsigned int type; 203 unsigned int have_answer : 1; 204 union { 205 struct { 206 u32 addrcount; 207 u32 addresses[MAX_V4_ADDRS]; 208 } a; 209 struct { 210 u32 addrcount; 211 struct in6_addr addresses[MAX_V6_ADDRS]; 212 } aaaa; 213 struct { 214 char name[HOST_NAME_MAX]; 215 } ptr; 216 } data; 217 }; 218 219 struct nameserver { 220 evutil_socket_t socket; /* a connected UDP socket */ 221 struct sockaddr_storage address; 222 ev_socklen_t addrlen; 223 int failed_times; /* number of times which we have given this server a chance */ 224 int timedout; /* number of times in a row a request has timed out */ 225 struct event event; 226 /* these objects are kept in a circular list */ 227 struct nameserver *next, *prev; 228 struct event timeout_event; /* used to keep the timeout for */ 229 /* when we next probe this server. */ 230 /* Valid if state == 0 */ 231 /* Outstanding probe request for this nameserver, if any */ 232 struct evdns_request *probe_request; 233 char state; /* zero if we think that this server is down */ 234 char choked; /* true if we have an EAGAIN from this server's socket */ 235 char write_waiting; /* true if we are waiting for EV_WRITE events */ 236 struct evdns_base *base; 237 238 /* Number of currently inflight requests: used 239 * to track when we should add/del the event. */ 240 int requests_inflight; 241 }; 242 243 244 /* Represents a local port where we're listening for DNS requests. Right now, */ 245 /* only UDP is supported. */ 246 struct evdns_server_port { 247 evutil_socket_t socket; /* socket we use to read queries and write replies. */ 248 int refcnt; /* reference count. */ 249 char choked; /* Are we currently blocked from writing? */ 250 char closing; /* Are we trying to close this port, pending writes? */ 251 evdns_request_callback_fn_type user_callback; /* Fn to handle requests */ 252 void *user_data; /* Opaque pointer passed to user_callback */ 253 struct event event; /* Read/write event */ 254 /* circular list of replies that we want to write. */ 255 struct server_request *pending_replies; 256 struct event_base *event_base; 257 258 #ifndef EVENT__DISABLE_THREAD_SUPPORT 259 void *lock; 260 #endif 261 }; 262 263 /* Represents part of a reply being built. (That is, a single RR.) */ 264 struct server_reply_item { 265 struct server_reply_item *next; /* next item in sequence. */ 266 char *name; /* name part of the RR */ 267 u16 type; /* The RR type */ 268 u16 class; /* The RR class (usually CLASS_INET) */ 269 u32 ttl; /* The RR TTL */ 270 char is_name; /* True iff data is a label */ 271 u16 datalen; /* Length of data; -1 if data is a label */ 272 void *data; /* The contents of the RR */ 273 }; 274 275 /* Represents a request that we've received as a DNS server, and holds */ 276 /* the components of the reply as we're constructing it. */ 277 struct server_request { 278 /* Pointers to the next and previous entries on the list of replies */ 279 /* that we're waiting to write. Only set if we have tried to respond */ 280 /* and gotten EAGAIN. */ 281 struct server_request *next_pending; 282 struct server_request *prev_pending; 283 284 u16 trans_id; /* Transaction id. */ 285 struct evdns_server_port *port; /* Which port received this request on? */ 286 struct sockaddr_storage addr; /* Where to send the response */ 287 ev_socklen_t addrlen; /* length of addr */ 288 289 int n_answer; /* how many answer RRs have been set? */ 290 int n_authority; /* how many authority RRs have been set? */ 291 int n_additional; /* how many additional RRs have been set? */ 292 293 struct server_reply_item *answer; /* linked list of answer RRs */ 294 struct server_reply_item *authority; /* linked list of authority RRs */ 295 struct server_reply_item *additional; /* linked list of additional RRs */ 296 297 /* Constructed response. Only set once we're ready to send a reply. */ 298 /* Once this is set, the RR fields are cleared, and no more should be set. */ 299 char *response; 300 size_t response_len; 301 302 /* Caller-visible fields: flags, questions. */ 303 struct evdns_server_request base; 304 }; 305 306 struct evdns_base { 307 /* An array of n_req_heads circular lists for inflight requests. 308 * Each inflight request req is in req_heads[req->trans_id % n_req_heads]. 309 */ 310 struct request **req_heads; 311 /* A circular list of requests that we're waiting to send, but haven't 312 * sent yet because there are too many requests inflight */ 313 struct request *req_waiting_head; 314 /* A circular list of nameservers. */ 315 struct nameserver *server_head; 316 int n_req_heads; 317 318 struct event_base *event_base; 319 320 /* The number of good nameservers that we have */ 321 int global_good_nameservers; 322 323 /* inflight requests are contained in the req_head list */ 324 /* and are actually going out across the network */ 325 int global_requests_inflight; 326 /* requests which aren't inflight are in the waiting list */ 327 /* and are counted here */ 328 int global_requests_waiting; 329 330 int global_max_requests_inflight; 331 332 struct timeval global_timeout; /* 5 seconds by default */ 333 int global_max_reissues; /* a reissue occurs when we get some errors from the server */ 334 int global_max_retransmits; /* number of times we'll retransmit a request which timed out */ 335 /* number of timeouts in a row before we consider this server to be down */ 336 int global_max_nameserver_timeout; 337 /* true iff we will use the 0x20 hack to prevent poisoning attacks. */ 338 int global_randomize_case; 339 340 /* The first time that a nameserver fails, how long do we wait before 341 * probing to see if it has returned? */ 342 struct timeval global_nameserver_probe_initial_timeout; 343 344 /** Port to bind to for outgoing DNS packets. */ 345 struct sockaddr_storage global_outgoing_address; 346 /** ev_socklen_t for global_outgoing_address. 0 if it isn't set. */ 347 ev_socklen_t global_outgoing_addrlen; 348 349 struct timeval global_getaddrinfo_allow_skew; 350 351 int getaddrinfo_ipv4_timeouts; 352 int getaddrinfo_ipv6_timeouts; 353 int getaddrinfo_ipv4_answered; 354 int getaddrinfo_ipv6_answered; 355 356 struct search_state *global_search_state; 357 358 TAILQ_HEAD(hosts_list, hosts_entry) hostsdb; 359 360 #ifndef EVENT__DISABLE_THREAD_SUPPORT 361 void *lock; 362 #endif 363 364 int disable_when_inactive; 365 }; 366 367 struct hosts_entry { 368 TAILQ_ENTRY(hosts_entry) next; 369 union { 370 struct sockaddr sa; 371 struct sockaddr_in sin; 372 struct sockaddr_in6 sin6; 373 } addr; 374 int addrlen; 375 char hostname[1]; 376 }; 377 378 static struct evdns_base *current_base = NULL; 379 380 struct evdns_base * 381 evdns_get_global_base(void) 382 { 383 return current_base; 384 } 385 386 /* Given a pointer to an evdns_server_request, get the corresponding */ 387 /* server_request. */ 388 #define TO_SERVER_REQUEST(base_ptr) \ 389 ((struct server_request*) \ 390 (((char*)(base_ptr) - evutil_offsetof(struct server_request, base)))) 391 392 #define REQ_HEAD(base, id) ((base)->req_heads[id % (base)->n_req_heads]) 393 394 static struct nameserver *nameserver_pick(struct evdns_base *base); 395 static void evdns_request_insert(struct request *req, struct request **head); 396 static void evdns_request_remove(struct request *req, struct request **head); 397 static void nameserver_ready_callback(evutil_socket_t fd, short events, void *arg); 398 static int evdns_transmit(struct evdns_base *base); 399 static int evdns_request_transmit(struct request *req); 400 static void nameserver_send_probe(struct nameserver *const ns); 401 static void search_request_finished(struct evdns_request *const); 402 static int search_try_next(struct evdns_request *const req); 403 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); 404 static void evdns_requests_pump_waiting_queue(struct evdns_base *base); 405 static u16 transaction_id_pick(struct evdns_base *base); 406 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); 407 static void request_submit(struct request *const req); 408 409 static int server_request_free(struct server_request *req); 410 static void server_request_free_answers(struct server_request *req); 411 static void server_port_free(struct evdns_server_port *port); 412 static void server_port_ready_callback(evutil_socket_t fd, short events, void *arg); 413 static int evdns_base_resolv_conf_parse_impl(struct evdns_base *base, int flags, const char *const filename); 414 static int evdns_base_set_option_impl(struct evdns_base *base, 415 const char *option, const char *val, int flags); 416 static void evdns_base_free_and_unlock(struct evdns_base *base, int fail_requests); 417 static void evdns_request_timeout_callback(evutil_socket_t fd, short events, void *arg); 418 419 static int strtoint(const char *const str); 420 421 #ifdef EVENT__DISABLE_THREAD_SUPPORT 422 #define EVDNS_LOCK(base) EVUTIL_NIL_STMT_ 423 #define EVDNS_UNLOCK(base) EVUTIL_NIL_STMT_ 424 #define ASSERT_LOCKED(base) EVUTIL_NIL_STMT_ 425 #else 426 #define EVDNS_LOCK(base) \ 427 EVLOCK_LOCK((base)->lock, 0) 428 #define EVDNS_UNLOCK(base) \ 429 EVLOCK_UNLOCK((base)->lock, 0) 430 #define ASSERT_LOCKED(base) \ 431 EVLOCK_ASSERT_LOCKED((base)->lock) 432 #endif 433 434 static evdns_debug_log_fn_type evdns_log_fn = NULL; 435 436 void 437 evdns_set_log_fn(evdns_debug_log_fn_type fn) 438 { 439 evdns_log_fn = fn; 440 } 441 442 #ifdef __GNUC__ 443 #define EVDNS_LOG_CHECK __attribute__ ((format(printf, 2, 3))) 444 #else 445 #define EVDNS_LOG_CHECK 446 #endif 447 448 static void evdns_log_(int severity, const char *fmt, ...) EVDNS_LOG_CHECK; 449 static void 450 evdns_log_(int severity, const char *fmt, ...) 451 { 452 va_list args; 453 va_start(args,fmt); 454 if (evdns_log_fn) { 455 char buf[512]; 456 int is_warn = (severity == EVDNS_LOG_WARN); 457 evutil_vsnprintf(buf, sizeof(buf), fmt, args); 458 evdns_log_fn(is_warn, buf); 459 } else { 460 event_logv_(severity, NULL, fmt, args); 461 } 462 va_end(args); 463 } 464 465 #define log evdns_log_ 466 467 /* This walks the list of inflight requests to find the */ 468 /* one with a matching transaction id. Returns NULL on */ 469 /* failure */ 470 static struct request * 471 request_find_from_trans_id(struct evdns_base *base, u16 trans_id) { 472 struct request *req = REQ_HEAD(base, trans_id); 473 struct request *const started_at = req; 474 475 ASSERT_LOCKED(base); 476 477 if (req) { 478 do { 479 if (req->trans_id == trans_id) return req; 480 req = req->next; 481 } while (req != started_at); 482 } 483 484 return NULL; 485 } 486 487 /* a libevent callback function which is called when a nameserver */ 488 /* has gone down and we want to test if it has came back to life yet */ 489 static void 490 nameserver_prod_callback(evutil_socket_t fd, short events, void *arg) { 491 struct nameserver *const ns = (struct nameserver *) arg; 492 (void)fd; 493 (void)events; 494 495 EVDNS_LOCK(ns->base); 496 nameserver_send_probe(ns); 497 EVDNS_UNLOCK(ns->base); 498 } 499 500 /* a libevent callback which is called when a nameserver probe (to see if */ 501 /* it has come back to life) times out. We increment the count of failed_times */ 502 /* and wait longer to send the next probe packet. */ 503 static void 504 nameserver_probe_failed(struct nameserver *const ns) { 505 struct timeval timeout; 506 int i; 507 508 ASSERT_LOCKED(ns->base); 509 (void) evtimer_del(&ns->timeout_event); 510 if (ns->state == 1) { 511 /* This can happen if the nameserver acts in a way which makes us mark */ 512 /* it as bad and then starts sending good replies. */ 513 return; 514 } 515 516 #define MAX_PROBE_TIMEOUT 3600 517 #define TIMEOUT_BACKOFF_FACTOR 3 518 519 memcpy(&timeout, &ns->base->global_nameserver_probe_initial_timeout, 520 sizeof(struct timeval)); 521 for (i=ns->failed_times; i > 0 && timeout.tv_sec < MAX_PROBE_TIMEOUT; --i) { 522 timeout.tv_sec *= TIMEOUT_BACKOFF_FACTOR; 523 timeout.tv_usec *= TIMEOUT_BACKOFF_FACTOR; 524 if (timeout.tv_usec > 1000000) { 525 timeout.tv_sec += timeout.tv_usec / 1000000; 526 timeout.tv_usec %= 1000000; 527 } 528 } 529 if (timeout.tv_sec > MAX_PROBE_TIMEOUT) { 530 timeout.tv_sec = MAX_PROBE_TIMEOUT; 531 timeout.tv_usec = 0; 532 } 533 534 ns->failed_times++; 535 536 if (evtimer_add(&ns->timeout_event, &timeout) < 0) { 537 char addrbuf[128]; 538 log(EVDNS_LOG_WARN, 539 "Error from libevent when adding timer event for %s", 540 evutil_format_sockaddr_port_( 541 (struct sockaddr *)&ns->address, 542 addrbuf, sizeof(addrbuf))); 543 } 544 } 545 546 static void 547 request_swap_ns(struct request *req, struct nameserver *ns) { 548 if (ns && req->ns != ns) { 549 EVUTIL_ASSERT(req->ns->requests_inflight > 0); 550 req->ns->requests_inflight--; 551 ns->requests_inflight++; 552 553 req->ns = ns; 554 } 555 } 556 557 /* called when a nameserver has been deemed to have failed. For example, too */ 558 /* many packets have timed out etc */ 559 static void 560 nameserver_failed(struct nameserver *const ns, const char *msg) { 561 struct request *req, *started_at; 562 struct evdns_base *base = ns->base; 563 int i; 564 char addrbuf[128]; 565 566 ASSERT_LOCKED(base); 567 /* if this nameserver has already been marked as failed */ 568 /* then don't do anything */ 569 if (!ns->state) return; 570 571 log(EVDNS_LOG_MSG, "Nameserver %s has failed: %s", 572 evutil_format_sockaddr_port_( 573 (struct sockaddr *)&ns->address, 574 addrbuf, sizeof(addrbuf)), 575 msg); 576 577 base->global_good_nameservers--; 578 EVUTIL_ASSERT(base->global_good_nameservers >= 0); 579 if (base->global_good_nameservers == 0) { 580 log(EVDNS_LOG_MSG, "All nameservers have failed"); 581 } 582 583 ns->state = 0; 584 ns->failed_times = 1; 585 586 if (evtimer_add(&ns->timeout_event, 587 &base->global_nameserver_probe_initial_timeout) < 0) { 588 log(EVDNS_LOG_WARN, 589 "Error from libevent when adding timer event for %s", 590 evutil_format_sockaddr_port_( 591 (struct sockaddr *)&ns->address, 592 addrbuf, sizeof(addrbuf))); 593 /* ???? Do more? */ 594 } 595 596 /* walk the list of inflight requests to see if any can be reassigned to */ 597 /* a different server. Requests in the waiting queue don't have a */ 598 /* nameserver assigned yet */ 599 600 /* if we don't have *any* good nameservers then there's no point */ 601 /* trying to reassign requests to one */ 602 if (!base->global_good_nameservers) return; 603 604 for (i = 0; i < base->n_req_heads; ++i) { 605 req = started_at = base->req_heads[i]; 606 if (req) { 607 do { 608 if (req->tx_count == 0 && req->ns == ns) { 609 /* still waiting to go out, can be moved */ 610 /* to another server */ 611 request_swap_ns(req, nameserver_pick(base)); 612 } 613 req = req->next; 614 } while (req != started_at); 615 } 616 } 617 } 618 619 static void 620 nameserver_up(struct nameserver *const ns) 621 { 622 char addrbuf[128]; 623 ASSERT_LOCKED(ns->base); 624 if (ns->state) return; 625 log(EVDNS_LOG_MSG, "Nameserver %s is back up", 626 evutil_format_sockaddr_port_( 627 (struct sockaddr *)&ns->address, 628 addrbuf, sizeof(addrbuf))); 629 evtimer_del(&ns->timeout_event); 630 if (ns->probe_request) { 631 evdns_cancel_request(ns->base, ns->probe_request); 632 ns->probe_request = NULL; 633 } 634 ns->state = 1; 635 ns->failed_times = 0; 636 ns->timedout = 0; 637 ns->base->global_good_nameservers++; 638 } 639 640 static void 641 request_trans_id_set(struct request *const req, const u16 trans_id) { 642 req->trans_id = trans_id; 643 *((u16 *) req->request) = htons(trans_id); 644 } 645 646 /* Called to remove a request from a list and dealloc it. */ 647 /* head is a pointer to the head of the list it should be */ 648 /* removed from or NULL if the request isn't in a list. */ 649 /* when free_handle is one, free the handle as well. */ 650 static void 651 request_finished(struct request *const req, struct request **head, int free_handle) { 652 struct evdns_base *base = req->base; 653 int was_inflight = (head != &base->req_waiting_head); 654 EVDNS_LOCK(base); 655 ASSERT_VALID_REQUEST(req); 656 657 if (head) 658 evdns_request_remove(req, head); 659 660 log(EVDNS_LOG_DEBUG, "Removing timeout for request %p", req); 661 if (was_inflight) { 662 evtimer_del(&req->timeout_event); 663 base->global_requests_inflight--; 664 req->ns->requests_inflight--; 665 } else { 666 base->global_requests_waiting--; 667 } 668 /* it was initialized during request_new / evtimer_assign */ 669 event_debug_unassign(&req->timeout_event); 670 671 if (req->ns && 672 req->ns->requests_inflight == 0 && 673 req->base->disable_when_inactive) { 674 event_del(&req->ns->event); 675 evtimer_del(&req->ns->timeout_event); 676 } 677 678 if (!req->request_appended) { 679 /* need to free the request data on it's own */ 680 mm_free(req->request); 681 } else { 682 /* the request data is appended onto the header */ 683 /* so everything gets free()ed when we: */ 684 } 685 686 if (req->handle) { 687 EVUTIL_ASSERT(req->handle->current_req == req); 688 689 if (free_handle) { 690 search_request_finished(req->handle); 691 req->handle->current_req = NULL; 692 if (! req->handle->pending_cb) { 693 /* If we're planning to run the callback, 694 * don't free the handle until later. */ 695 mm_free(req->handle); 696 } 697 req->handle = NULL; /* If we have a bug, let's crash 698 * early */ 699 } else { 700 req->handle->current_req = NULL; 701 } 702 } 703 704 mm_free(req); 705 706 evdns_requests_pump_waiting_queue(base); 707 EVDNS_UNLOCK(base); 708 } 709 710 /* This is called when a server returns a funny error code. */ 711 /* We try the request again with another server. */ 712 /* */ 713 /* return: */ 714 /* 0 ok */ 715 /* 1 failed/reissue is pointless */ 716 static int 717 request_reissue(struct request *req) { 718 const struct nameserver *const last_ns = req->ns; 719 ASSERT_LOCKED(req->base); 720 ASSERT_VALID_REQUEST(req); 721 /* the last nameserver should have been marked as failing */ 722 /* by the caller of this function, therefore pick will try */ 723 /* not to return it */ 724 request_swap_ns(req, nameserver_pick(req->base)); 725 if (req->ns == last_ns) { 726 /* ... but pick did return it */ 727 /* not a lot of point in trying again with the */ 728 /* same server */ 729 return 1; 730 } 731 732 req->reissue_count++; 733 req->tx_count = 0; 734 req->transmit_me = 1; 735 736 return 0; 737 } 738 739 /* this function looks for space on the inflight queue and promotes */ 740 /* requests from the waiting queue if it can. */ 741 /* */ 742 /* TODO: */ 743 /* add return code, see at nameserver_pick() and other functions. */ 744 static void 745 evdns_requests_pump_waiting_queue(struct evdns_base *base) { 746 ASSERT_LOCKED(base); 747 while (base->global_requests_inflight < base->global_max_requests_inflight && 748 base->global_requests_waiting) { 749 struct request *req; 750 751 EVUTIL_ASSERT(base->req_waiting_head); 752 req = base->req_waiting_head; 753 754 req->ns = nameserver_pick(base); 755 if (!req->ns) 756 return; 757 758 /* move a request from the waiting queue to the inflight queue */ 759 req->ns->requests_inflight++; 760 761 evdns_request_remove(req, &base->req_waiting_head); 762 763 base->global_requests_waiting--; 764 base->global_requests_inflight++; 765 766 request_trans_id_set(req, transaction_id_pick(base)); 767 768 evdns_request_insert(req, &REQ_HEAD(base, req->trans_id)); 769 evdns_request_transmit(req); 770 evdns_transmit(base); 771 } 772 } 773 774 /* TODO(nickm) document */ 775 struct deferred_reply_callback { 776 struct event_callback deferred; 777 struct evdns_request *handle; 778 u8 request_type; 779 u8 have_reply; 780 u32 ttl; 781 u32 err; 782 evdns_callback_type user_callback; 783 struct reply reply; 784 }; 785 786 static void 787 reply_run_callback(struct event_callback *d, void *user_pointer) 788 { 789 struct deferred_reply_callback *cb = 790 EVUTIL_UPCAST(d, struct deferred_reply_callback, deferred); 791 792 switch (cb->request_type) { 793 case TYPE_A: 794 if (cb->have_reply) 795 cb->user_callback(DNS_ERR_NONE, DNS_IPv4_A, 796 cb->reply.data.a.addrcount, cb->ttl, 797 cb->reply.data.a.addresses, 798 user_pointer); 799 else 800 cb->user_callback(cb->err, 0, 0, cb->ttl, NULL, user_pointer); 801 break; 802 case TYPE_PTR: 803 if (cb->have_reply) { 804 char *name = cb->reply.data.ptr.name; 805 cb->user_callback(DNS_ERR_NONE, DNS_PTR, 1, cb->ttl, 806 &name, user_pointer); 807 } else { 808 cb->user_callback(cb->err, 0, 0, cb->ttl, NULL, user_pointer); 809 } 810 break; 811 case TYPE_AAAA: 812 if (cb->have_reply) 813 cb->user_callback(DNS_ERR_NONE, DNS_IPv6_AAAA, 814 cb->reply.data.aaaa.addrcount, cb->ttl, 815 cb->reply.data.aaaa.addresses, 816 user_pointer); 817 else 818 cb->user_callback(cb->err, 0, 0, cb->ttl, NULL, user_pointer); 819 break; 820 default: 821 EVUTIL_ASSERT(0); 822 } 823 824 if (cb->handle && cb->handle->pending_cb) { 825 mm_free(cb->handle); 826 } 827 828 mm_free(cb); 829 } 830 831 static void 832 reply_schedule_callback(struct request *const req, u32 ttl, u32 err, struct reply *reply) 833 { 834 struct deferred_reply_callback *d = mm_calloc(1, sizeof(*d)); 835 836 if (!d) { 837 event_warn("%s: Couldn't allocate space for deferred callback.", 838 __func__); 839 return; 840 } 841 842 ASSERT_LOCKED(req->base); 843 844 d->request_type = req->request_type; 845 d->user_callback = req->user_callback; 846 d->ttl = ttl; 847 d->err = err; 848 if (reply) { 849 d->have_reply = 1; 850 memcpy(&d->reply, reply, sizeof(struct reply)); 851 } 852 853 if (req->handle) { 854 req->handle->pending_cb = 1; 855 d->handle = req->handle; 856 } 857 858 event_deferred_cb_init_( 859 &d->deferred, 860 event_get_priority(&req->timeout_event), 861 reply_run_callback, 862 req->user_pointer); 863 event_deferred_cb_schedule_( 864 req->base->event_base, 865 &d->deferred); 866 } 867 868 /* this processes a parsed reply packet */ 869 static void 870 reply_handle(struct request *const req, u16 flags, u32 ttl, struct reply *reply) { 871 int error; 872 char addrbuf[128]; 873 static const int error_codes[] = { 874 DNS_ERR_FORMAT, DNS_ERR_SERVERFAILED, DNS_ERR_NOTEXIST, 875 DNS_ERR_NOTIMPL, DNS_ERR_REFUSED 876 }; 877 878 ASSERT_LOCKED(req->base); 879 ASSERT_VALID_REQUEST(req); 880 881 if (flags & 0x020f || !reply || !reply->have_answer) { 882 /* there was an error */ 883 if (flags & 0x0200) { 884 error = DNS_ERR_TRUNCATED; 885 } else if (flags & 0x000f) { 886 u16 error_code = (flags & 0x000f) - 1; 887 if (error_code > 4) { 888 error = DNS_ERR_UNKNOWN; 889 } else { 890 error = error_codes[error_code]; 891 } 892 } else if (reply && !reply->have_answer) { 893 error = DNS_ERR_NODATA; 894 } else { 895 error = DNS_ERR_UNKNOWN; 896 } 897 898 switch (error) { 899 case DNS_ERR_NOTIMPL: 900 case DNS_ERR_REFUSED: 901 /* we regard these errors as marking a bad nameserver */ 902 if (req->reissue_count < req->base->global_max_reissues) { 903 char msg[64]; 904 evutil_snprintf(msg, sizeof(msg), "Bad response %d (%s)", 905 error, evdns_err_to_string(error)); 906 nameserver_failed(req->ns, msg); 907 if (!request_reissue(req)) return; 908 } 909 break; 910 case DNS_ERR_SERVERFAILED: 911 /* rcode 2 (servfailed) sometimes means "we 912 * are broken" and sometimes (with some binds) 913 * means "that request was very confusing." 914 * Treat this as a timeout, not a failure. 915 */ 916 log(EVDNS_LOG_DEBUG, "Got a SERVERFAILED from nameserver" 917 "at %s; will allow the request to time out.", 918 evutil_format_sockaddr_port_( 919 (struct sockaddr *)&req->ns->address, 920 addrbuf, sizeof(addrbuf))); 921 /* Call the timeout function */ 922 evdns_request_timeout_callback(0, 0, req); 923 return; 924 default: 925 /* we got a good reply from the nameserver: it is up. */ 926 if (req->handle == req->ns->probe_request) { 927 /* Avoid double-free */ 928 req->ns->probe_request = NULL; 929 } 930 931 nameserver_up(req->ns); 932 } 933 934 if (req->handle->search_state && 935 req->request_type != TYPE_PTR) { 936 /* if we have a list of domains to search in, 937 * try the next one */ 938 if (!search_try_next(req->handle)) { 939 /* a new request was issued so this 940 * request is finished and */ 941 /* the user callback will be made when 942 * that request (or a */ 943 /* child of it) finishes. */ 944 return; 945 } 946 } 947 948 /* all else failed. Pass the failure up */ 949 reply_schedule_callback(req, ttl, error, NULL); 950 request_finished(req, &REQ_HEAD(req->base, req->trans_id), 1); 951 } else { 952 /* all ok, tell the user */ 953 reply_schedule_callback(req, ttl, 0, reply); 954 if (req->handle == req->ns->probe_request) 955 req->ns->probe_request = NULL; /* Avoid double-free */ 956 nameserver_up(req->ns); 957 request_finished(req, &REQ_HEAD(req->base, req->trans_id), 1); 958 } 959 } 960 961 static int 962 name_parse(u8 *packet, int length, int *idx, char *name_out, int name_out_len) { 963 int name_end = -1; 964 int j = *idx; 965 int ptr_count = 0; 966 #define GET32(x) do { if (j + 4 > length) goto err; memcpy(&t32_, packet + j, 4); j += 4; x = ntohl(t32_); } while (0) 967 #define GET16(x) do { if (j + 2 > length) goto err; memcpy(&t_, packet + j, 2); j += 2; x = ntohs(t_); } while (0) 968 #define GET8(x) do { if (j >= length) goto err; x = packet[j++]; } while (0) 969 970 char *cp = name_out; 971 const char *const end = name_out + name_out_len; 972 973 /* Normally, names are a series of length prefixed strings terminated */ 974 /* with a length of 0 (the lengths are u8's < 63). */ 975 /* However, the length can start with a pair of 1 bits and that */ 976 /* means that the next 14 bits are a pointer within the current */ 977 /* packet. */ 978 979 for (;;) { 980 u8 label_len; 981 if (j >= length) return -1; 982 GET8(label_len); 983 if (!label_len) break; 984 if (label_len & 0xc0) { 985 u8 ptr_low; 986 GET8(ptr_low); 987 if (name_end < 0) name_end = j; 988 j = (((int)label_len & 0x3f) << 8) + ptr_low; 989 /* Make sure that the target offset is in-bounds. */ 990 if (j < 0 || j >= length) return -1; 991 /* If we've jumped more times than there are characters in the 992 * message, we must have a loop. */ 993 if (++ptr_count > length) return -1; 994 continue; 995 } 996 if (label_len > 63) return -1; 997 if (cp != name_out) { 998 if (cp + 1 >= end) return -1; 999 *cp++ = '.'; 1000 } 1001 if (cp + label_len >= end) return -1; 1002 memcpy(cp, packet + j, label_len); 1003 cp += label_len; 1004 j += label_len; 1005 } 1006 if (cp >= end) return -1; 1007 *cp = '\0'; 1008 if (name_end < 0) 1009 *idx = j; 1010 else 1011 *idx = name_end; 1012 return 0; 1013 err: 1014 return -1; 1015 } 1016 1017 /* parses a raw request from a nameserver */ 1018 static int 1019 reply_parse(struct evdns_base *base, u8 *packet, int length) { 1020 int j = 0, k = 0; /* index into packet */ 1021 u16 t_; /* used by the macros */ 1022 u32 t32_; /* used by the macros */ 1023 char tmp_name[256], cmp_name[256]; /* used by the macros */ 1024 int name_matches = 0; 1025 1026 u16 trans_id, questions, answers, authority, additional, datalength; 1027 u16 flags = 0; 1028 u32 ttl, ttl_r = 0xffffffff; 1029 struct reply reply; 1030 struct request *req = NULL; 1031 unsigned int i; 1032 1033 ASSERT_LOCKED(base); 1034 1035 GET16(trans_id); 1036 GET16(flags); 1037 GET16(questions); 1038 GET16(answers); 1039 GET16(authority); 1040 GET16(additional); 1041 (void) authority; /* suppress "unused variable" warnings. */ 1042 (void) additional; /* suppress "unused variable" warnings. */ 1043 1044 req = request_find_from_trans_id(base, trans_id); 1045 if (!req) return -1; 1046 EVUTIL_ASSERT(req->base == base); 1047 1048 memset(&reply, 0, sizeof(reply)); 1049 1050 /* If it's not an answer, it doesn't correspond to any request. */ 1051 if (!(flags & 0x8000)) return -1; /* must be an answer */ 1052 if ((flags & 0x020f) && (flags & 0x020f) != DNS_ERR_NOTEXIST) { 1053 /* there was an error and it's not NXDOMAIN */ 1054 goto err; 1055 } 1056 /* if (!answers) return; */ /* must have an answer of some form */ 1057 1058 /* This macro skips a name in the DNS reply. */ 1059 #define SKIP_NAME \ 1060 do { tmp_name[0] = '\0'; \ 1061 if (name_parse(packet, length, &j, tmp_name, \ 1062 sizeof(tmp_name))<0) \ 1063 goto err; \ 1064 } while (0) 1065 #define TEST_NAME \ 1066 do { tmp_name[0] = '\0'; \ 1067 cmp_name[0] = '\0'; \ 1068 k = j; \ 1069 if (name_parse(packet, length, &j, tmp_name, \ 1070 sizeof(tmp_name))<0) \ 1071 goto err; \ 1072 if (name_parse(req->request, req->request_len, &k, \ 1073 cmp_name, sizeof(cmp_name))<0) \ 1074 goto err; \ 1075 if (base->global_randomize_case) { \ 1076 if (strcmp(tmp_name, cmp_name) == 0) \ 1077 name_matches = 1; \ 1078 } else { \ 1079 if (evutil_ascii_strcasecmp(tmp_name, cmp_name) == 0) \ 1080 name_matches = 1; \ 1081 } \ 1082 } while (0) 1083 1084 reply.type = req->request_type; 1085 1086 /* skip over each question in the reply */ 1087 for (i = 0; i < questions; ++i) { 1088 /* the question looks like 1089 * <label:name><u16:type><u16:class> 1090 */ 1091 TEST_NAME; 1092 j += 4; 1093 if (j > length) goto err; 1094 } 1095 1096 if (!name_matches) 1097 goto err; 1098 1099 /* now we have the answer section which looks like 1100 * <label:name><u16:type><u16:class><u32:ttl><u16:len><data...> 1101 */ 1102 1103 for (i = 0; i < answers; ++i) { 1104 u16 type, class; 1105 1106 SKIP_NAME; 1107 GET16(type); 1108 GET16(class); 1109 GET32(ttl); 1110 GET16(datalength); 1111 1112 if (type == TYPE_A && class == CLASS_INET) { 1113 int addrcount, addrtocopy; 1114 if (req->request_type != TYPE_A) { 1115 j += datalength; continue; 1116 } 1117 if ((datalength & 3) != 0) /* not an even number of As. */ 1118 goto err; 1119 addrcount = datalength >> 2; 1120 addrtocopy = MIN(MAX_V4_ADDRS - reply.data.a.addrcount, (unsigned)addrcount); 1121 1122 ttl_r = MIN(ttl_r, ttl); 1123 /* we only bother with the first four addresses. */ 1124 if (j + 4*addrtocopy > length) goto err; 1125 memcpy(&reply.data.a.addresses[reply.data.a.addrcount], 1126 packet + j, 4*addrtocopy); 1127 j += 4*addrtocopy; 1128 reply.data.a.addrcount += addrtocopy; 1129 reply.have_answer = 1; 1130 if (reply.data.a.addrcount == MAX_V4_ADDRS) break; 1131 } else if (type == TYPE_PTR && class == CLASS_INET) { 1132 if (req->request_type != TYPE_PTR) { 1133 j += datalength; continue; 1134 } 1135 if (name_parse(packet, length, &j, reply.data.ptr.name, 1136 sizeof(reply.data.ptr.name))<0) 1137 goto err; 1138 ttl_r = MIN(ttl_r, ttl); 1139 reply.have_answer = 1; 1140 break; 1141 } else if (type == TYPE_CNAME) { 1142 char cname[HOST_NAME_MAX]; 1143 if (!req->put_cname_in_ptr || *req->put_cname_in_ptr) { 1144 j += datalength; continue; 1145 } 1146 if (name_parse(packet, length, &j, cname, 1147 sizeof(cname))<0) 1148 goto err; 1149 *req->put_cname_in_ptr = mm_strdup(cname); 1150 } else if (type == TYPE_AAAA && class == CLASS_INET) { 1151 int addrcount, addrtocopy; 1152 if (req->request_type != TYPE_AAAA) { 1153 j += datalength; continue; 1154 } 1155 if ((datalength & 15) != 0) /* not an even number of AAAAs. */ 1156 goto err; 1157 addrcount = datalength >> 4; /* each address is 16 bytes long */ 1158 addrtocopy = MIN(MAX_V6_ADDRS - reply.data.aaaa.addrcount, (unsigned)addrcount); 1159 ttl_r = MIN(ttl_r, ttl); 1160 1161 /* we only bother with the first four addresses. */ 1162 if (j + 16*addrtocopy > length) goto err; 1163 memcpy(&reply.data.aaaa.addresses[reply.data.aaaa.addrcount], 1164 packet + j, 16*addrtocopy); 1165 reply.data.aaaa.addrcount += addrtocopy; 1166 j += 16*addrtocopy; 1167 reply.have_answer = 1; 1168 if (reply.data.aaaa.addrcount == MAX_V6_ADDRS) break; 1169 } else { 1170 /* skip over any other type of resource */ 1171 j += datalength; 1172 } 1173 } 1174 1175 if (!reply.have_answer) { 1176 for (i = 0; i < authority; ++i) { 1177 u16 type, class; 1178 SKIP_NAME; 1179 GET16(type); 1180 GET16(class); 1181 GET32(ttl); 1182 GET16(datalength); 1183 if (type == TYPE_SOA && class == CLASS_INET) { 1184 u32 serial, refresh, retry, expire, minimum; 1185 SKIP_NAME; 1186 SKIP_NAME; 1187 GET32(serial); 1188 GET32(refresh); 1189 GET32(retry); 1190 GET32(expire); 1191 GET32(minimum); 1192 (void)expire; 1193 (void)retry; 1194 (void)refresh; 1195 (void)serial; 1196 ttl_r = MIN(ttl_r, ttl); 1197 ttl_r = MIN(ttl_r, minimum); 1198 } else { 1199 /* skip over any other type of resource */ 1200 j += datalength; 1201 } 1202 } 1203 } 1204 1205 if (ttl_r == 0xffffffff) 1206 ttl_r = 0; 1207 1208 reply_handle(req, flags, ttl_r, &reply); 1209 return 0; 1210 err: 1211 if (req) 1212 reply_handle(req, flags, 0, NULL); 1213 return -1; 1214 } 1215 1216 /* Parse a raw request (packet,length) sent to a nameserver port (port) from */ 1217 /* a DNS client (addr,addrlen), and if it's well-formed, call the corresponding */ 1218 /* callback. */ 1219 static int 1220 request_parse(u8 *packet, int length, struct evdns_server_port *port, struct sockaddr *addr, ev_socklen_t addrlen) 1221 { 1222 int j = 0; /* index into packet */ 1223 u16 t_; /* used by the macros */ 1224 char tmp_name[256]; /* used by the macros */ 1225 1226 int i; 1227 u16 trans_id, flags, questions, answers, authority, additional; 1228 struct server_request *server_req = NULL; 1229 1230 ASSERT_LOCKED(port); 1231 1232 /* Get the header fields */ 1233 GET16(trans_id); 1234 GET16(flags); 1235 GET16(questions); 1236 GET16(answers); 1237 GET16(authority); 1238 GET16(additional); 1239 (void)answers; 1240 (void)additional; 1241 (void)authority; 1242 1243 if (flags & 0x8000) return -1; /* Must not be an answer. */ 1244 flags &= 0x0110; /* Only RD and CD get preserved. */ 1245 1246 server_req = mm_malloc(sizeof(struct server_request)); 1247 if (server_req == NULL) return -1; 1248 memset(server_req, 0, sizeof(struct server_request)); 1249 1250 server_req->trans_id = trans_id; 1251 memcpy(&server_req->addr, addr, addrlen); 1252 server_req->addrlen = addrlen; 1253 1254 server_req->base.flags = flags; 1255 server_req->base.nquestions = 0; 1256 server_req->base.questions = mm_calloc(sizeof(struct evdns_server_question *), questions); 1257 if (server_req->base.questions == NULL) 1258 goto err; 1259 1260 for (i = 0; i < questions; ++i) { 1261 u16 type, class; 1262 struct evdns_server_question *q; 1263 int namelen; 1264 if (name_parse(packet, length, &j, tmp_name, sizeof(tmp_name))<0) 1265 goto err; 1266 GET16(type); 1267 GET16(class); 1268 namelen = (int)strlen(tmp_name); 1269 q = mm_malloc(sizeof(struct evdns_server_question) + namelen); 1270 if (!q) 1271 goto err; 1272 q->type = type; 1273 q->dns_question_class = class; 1274 memcpy(q->name, tmp_name, namelen+1); 1275 server_req->base.questions[server_req->base.nquestions++] = q; 1276 } 1277 1278 /* Ignore answers, authority, and additional. */ 1279 1280 server_req->port = port; 1281 port->refcnt++; 1282 1283 /* Only standard queries are supported. */ 1284 if (flags & 0x7800) { 1285 evdns_server_request_respond(&(server_req->base), DNS_ERR_NOTIMPL); 1286 return -1; 1287 } 1288 1289 port->user_callback(&(server_req->base), port->user_data); 1290 1291 return 0; 1292 err: 1293 if (server_req) { 1294 if (server_req->base.questions) { 1295 for (i = 0; i < server_req->base.nquestions; ++i) 1296 mm_free(server_req->base.questions[i]); 1297 mm_free(server_req->base.questions); 1298 } 1299 mm_free(server_req); 1300 } 1301 return -1; 1302 1303 #undef SKIP_NAME 1304 #undef GET32 1305 #undef GET16 1306 #undef GET8 1307 } 1308 1309 1310 void 1311 evdns_set_transaction_id_fn(ev_uint16_t (*fn)(void)) 1312 { 1313 } 1314 1315 void 1316 evdns_set_random_bytes_fn(void (*fn)(char *, size_t)) 1317 { 1318 } 1319 1320 /* Try to choose a strong transaction id which isn't already in flight */ 1321 static u16 1322 transaction_id_pick(struct evdns_base *base) { 1323 ASSERT_LOCKED(base); 1324 for (;;) { 1325 u16 trans_id; 1326 evutil_secure_rng_get_bytes(&trans_id, sizeof(trans_id)); 1327 1328 if (trans_id == 0xffff) continue; 1329 /* now check to see if that id is already inflight */ 1330 if (request_find_from_trans_id(base, trans_id) == NULL) 1331 return trans_id; 1332 } 1333 } 1334 1335 /* choose a namesever to use. This function will try to ignore */ 1336 /* nameservers which we think are down and load balance across the rest */ 1337 /* by updating the server_head global each time. */ 1338 static struct nameserver * 1339 nameserver_pick(struct evdns_base *base) { 1340 struct nameserver *started_at = base->server_head, *picked; 1341 ASSERT_LOCKED(base); 1342 if (!base->server_head) return NULL; 1343 1344 /* if we don't have any good nameservers then there's no */ 1345 /* point in trying to find one. */ 1346 if (!base->global_good_nameservers) { 1347 base->server_head = base->server_head->next; 1348 return base->server_head; 1349 } 1350 1351 /* remember that nameservers are in a circular list */ 1352 for (;;) { 1353 if (base->server_head->state) { 1354 /* we think this server is currently good */ 1355 picked = base->server_head; 1356 base->server_head = base->server_head->next; 1357 return picked; 1358 } 1359 1360 base->server_head = base->server_head->next; 1361 if (base->server_head == started_at) { 1362 /* all the nameservers seem to be down */ 1363 /* so we just return this one and hope for the */ 1364 /* best */ 1365 EVUTIL_ASSERT(base->global_good_nameservers == 0); 1366 picked = base->server_head; 1367 base->server_head = base->server_head->next; 1368 return picked; 1369 } 1370 } 1371 } 1372 1373 /* this is called when a namesever socket is ready for reading */ 1374 static void 1375 nameserver_read(struct nameserver *ns) { 1376 struct sockaddr_storage ss; 1377 ev_socklen_t addrlen = sizeof(ss); 1378 u8 packet[1500]; 1379 char addrbuf[128]; 1380 ASSERT_LOCKED(ns->base); 1381 1382 for (;;) { 1383 const int r = recvfrom(ns->socket, (void*)packet, 1384 sizeof(packet), 0, 1385 (struct sockaddr*)&ss, &addrlen); 1386 if (r < 0) { 1387 int err = evutil_socket_geterror(ns->socket); 1388 if (EVUTIL_ERR_RW_RETRIABLE(err)) 1389 return; 1390 nameserver_failed(ns, 1391 evutil_socket_error_to_string(err)); 1392 return; 1393 } 1394 if (evutil_sockaddr_cmp((struct sockaddr*)&ss, 1395 (struct sockaddr*)&ns->address, 0)) { 1396 log(EVDNS_LOG_WARN, "Address mismatch on received " 1397 "DNS packet. Apparent source was %s", 1398 evutil_format_sockaddr_port_( 1399 (struct sockaddr *)&ss, 1400 addrbuf, sizeof(addrbuf))); 1401 return; 1402 } 1403 1404 ns->timedout = 0; 1405 reply_parse(ns->base, packet, r); 1406 } 1407 } 1408 1409 /* Read a packet from a DNS client on a server port s, parse it, and */ 1410 /* act accordingly. */ 1411 static void 1412 server_port_read(struct evdns_server_port *s) { 1413 u8 packet[1500]; 1414 struct sockaddr_storage addr; 1415 ev_socklen_t addrlen; 1416 int r; 1417 ASSERT_LOCKED(s); 1418 1419 for (;;) { 1420 addrlen = sizeof(struct sockaddr_storage); 1421 r = recvfrom(s->socket, (void*)packet, sizeof(packet), 0, 1422 (struct sockaddr*) &addr, &addrlen); 1423 if (r < 0) { 1424 int err = evutil_socket_geterror(s->socket); 1425 if (EVUTIL_ERR_RW_RETRIABLE(err)) 1426 return; 1427 log(EVDNS_LOG_WARN, 1428 "Error %s (%d) while reading request.", 1429 evutil_socket_error_to_string(err), err); 1430 return; 1431 } 1432 request_parse(packet, r, s, (struct sockaddr*) &addr, addrlen); 1433 } 1434 } 1435 1436 /* Try to write all pending replies on a given DNS server port. */ 1437 static void 1438 server_port_flush(struct evdns_server_port *port) 1439 { 1440 struct server_request *req = port->pending_replies; 1441 ASSERT_LOCKED(port); 1442 while (req) { 1443 int r = sendto(port->socket, req->response, (int)req->response_len, 0, 1444 (struct sockaddr*) &req->addr, (ev_socklen_t)req->addrlen); 1445 if (r < 0) { 1446 int err = evutil_socket_geterror(port->socket); 1447 if (EVUTIL_ERR_RW_RETRIABLE(err)) 1448 return; 1449 log(EVDNS_LOG_WARN, "Error %s (%d) while writing response to port; dropping", evutil_socket_error_to_string(err), err); 1450 } 1451 if (server_request_free(req)) { 1452 /* we released the last reference to req->port. */ 1453 return; 1454 } else { 1455 EVUTIL_ASSERT(req != port->pending_replies); 1456 req = port->pending_replies; 1457 } 1458 } 1459 1460 /* We have no more pending requests; stop listening for 'writeable' events. */ 1461 (void) event_del(&port->event); 1462 event_assign(&port->event, port->event_base, 1463 port->socket, EV_READ | EV_PERSIST, 1464 server_port_ready_callback, port); 1465 1466 if (event_add(&port->event, NULL) < 0) { 1467 log(EVDNS_LOG_WARN, "Error from libevent when adding event for DNS server."); 1468 /* ???? Do more? */ 1469 } 1470 } 1471 1472 /* set if we are waiting for the ability to write to this server. */ 1473 /* if waiting is true then we ask libevent for EV_WRITE events, otherwise */ 1474 /* we stop these events. */ 1475 static void 1476 nameserver_write_waiting(struct nameserver *ns, char waiting) { 1477 ASSERT_LOCKED(ns->base); 1478 if (ns->write_waiting == waiting) return; 1479 1480 ns->write_waiting = waiting; 1481 (void) event_del(&ns->event); 1482 event_assign(&ns->event, ns->base->event_base, 1483 ns->socket, EV_READ | (waiting ? EV_WRITE : 0) | EV_PERSIST, 1484 nameserver_ready_callback, ns); 1485 if (event_add(&ns->event, NULL) < 0) { 1486 char addrbuf[128]; 1487 log(EVDNS_LOG_WARN, "Error from libevent when adding event for %s", 1488 evutil_format_sockaddr_port_( 1489 (struct sockaddr *)&ns->address, 1490 addrbuf, sizeof(addrbuf))); 1491 /* ???? Do more? */ 1492 } 1493 } 1494 1495 /* a callback function. Called by libevent when the kernel says that */ 1496 /* a nameserver socket is ready for writing or reading */ 1497 static void 1498 nameserver_ready_callback(evutil_socket_t fd, short events, void *arg) { 1499 struct nameserver *ns = (struct nameserver *) arg; 1500 (void)fd; 1501 1502 EVDNS_LOCK(ns->base); 1503 if (events & EV_WRITE) { 1504 ns->choked = 0; 1505 if (!evdns_transmit(ns->base)) { 1506 nameserver_write_waiting(ns, 0); 1507 } 1508 } 1509 if (events & EV_READ) { 1510 nameserver_read(ns); 1511 } 1512 EVDNS_UNLOCK(ns->base); 1513 } 1514 1515 /* a callback function. Called by libevent when the kernel says that */ 1516 /* a server socket is ready for writing or reading. */ 1517 static void 1518 server_port_ready_callback(evutil_socket_t fd, short events, void *arg) { 1519 struct evdns_server_port *port = (struct evdns_server_port *) arg; 1520 (void) fd; 1521 1522 EVDNS_LOCK(port); 1523 if (events & EV_WRITE) { 1524 port->choked = 0; 1525 server_port_flush(port); 1526 } 1527 if (events & EV_READ) { 1528 server_port_read(port); 1529 } 1530 EVDNS_UNLOCK(port); 1531 } 1532 1533 /* This is an inefficient representation; only use it via the dnslabel_table_* 1534 * functions, so that is can be safely replaced with something smarter later. */ 1535 #define MAX_LABELS 128 1536 /* Structures used to implement name compression */ 1537 struct dnslabel_entry { char *v; off_t pos; }; 1538 struct dnslabel_table { 1539 int n_labels; /* number of current entries */ 1540 /* map from name to position in message */ 1541 struct dnslabel_entry labels[MAX_LABELS]; 1542 }; 1543 1544 /* Initialize dnslabel_table. */ 1545 static void 1546 dnslabel_table_init(struct dnslabel_table *table) 1547 { 1548 table->n_labels = 0; 1549 } 1550 1551 /* Free all storage held by table, but not the table itself. */ 1552 static void 1553 dnslabel_clear(struct dnslabel_table *table) 1554 { 1555 int i; 1556 for (i = 0; i < table->n_labels; ++i) 1557 mm_free(table->labels[i].v); 1558 table->n_labels = 0; 1559 } 1560 1561 /* return the position of the label in the current message, or -1 if the label */ 1562 /* hasn't been used yet. */ 1563 static int 1564 dnslabel_table_get_pos(const struct dnslabel_table *table, const char *label) 1565 { 1566 int i; 1567 for (i = 0; i < table->n_labels; ++i) { 1568 if (!strcmp(label, table->labels[i].v)) 1569 return table->labels[i].pos; 1570 } 1571 return -1; 1572 } 1573 1574 /* remember that we've used the label at position pos */ 1575 static int 1576 dnslabel_table_add(struct dnslabel_table *table, const char *label, off_t pos) 1577 { 1578 char *v; 1579 int p; 1580 if (table->n_labels == MAX_LABELS) 1581 return (-1); 1582 v = mm_strdup(label); 1583 if (v == NULL) 1584 return (-1); 1585 p = table->n_labels++; 1586 table->labels[p].v = v; 1587 table->labels[p].pos = pos; 1588 1589 return (0); 1590 } 1591 1592 /* Converts a string to a length-prefixed set of DNS labels, starting */ 1593 /* at buf[j]. name and buf must not overlap. name_len should be the length */ 1594 /* of name. table is optional, and is used for compression. */ 1595 /* */ 1596 /* Input: abc.def */ 1597 /* Output: <3>abc<3>def<0> */ 1598 /* */ 1599 /* Returns the first index after the encoded name, or negative on error. */ 1600 /* -1 label was > 63 bytes */ 1601 /* -2 name too long to fit in buffer. */ 1602 /* */ 1603 static off_t 1604 dnsname_to_labels(u8 *const buf, size_t buf_len, off_t j, 1605 const char *name, const size_t name_len, 1606 struct dnslabel_table *table) { 1607 const char *end = name + name_len; 1608 int ref = 0; 1609 u16 t_; 1610 1611 #define APPEND16(x) do { \ 1612 if (j + 2 > (off_t)buf_len) \ 1613 goto overflow; \ 1614 t_ = htons(x); \ 1615 memcpy(buf + j, &t_, 2); \ 1616 j += 2; \ 1617 } while (0) 1618 #define APPEND32(x) do { \ 1619 if (j + 4 > (off_t)buf_len) \ 1620 goto overflow; \ 1621 t32_ = htonl(x); \ 1622 memcpy(buf + j, &t32_, 4); \ 1623 j += 4; \ 1624 } while (0) 1625 1626 if (name_len > 255) return -2; 1627 1628 for (;;) { 1629 const char *const start = name; 1630 if (table && (ref = dnslabel_table_get_pos(table, name)) >= 0) { 1631 APPEND16(ref | 0xc000); 1632 return j; 1633 } 1634 name = strchr(name, '.'); 1635 if (!name) { 1636 const size_t label_len = end - start; 1637 if (label_len > 63) return -1; 1638 if ((size_t)(j+label_len+1) > buf_len) return -2; 1639 if (table) dnslabel_table_add(table, start, j); 1640 buf[j++] = (ev_uint8_t)label_len; 1641 1642 memcpy(buf + j, start, label_len); 1643 j += (int) label_len; 1644 break; 1645 } else { 1646 /* append length of the label. */ 1647 const size_t label_len = name - start; 1648 if (label_len > 63) return -1; 1649 if ((size_t)(j+label_len+1) > buf_len) return -2; 1650 if (table) dnslabel_table_add(table, start, j); 1651 buf[j++] = (ev_uint8_t)label_len; 1652 1653 memcpy(buf + j, start, label_len); 1654 j += (int) label_len; 1655 /* hop over the '.' */ 1656 name++; 1657 } 1658 } 1659 1660 /* the labels must be terminated by a 0. */ 1661 /* It's possible that the name ended in a . */ 1662 /* in which case the zero is already there */ 1663 if (!j || buf[j-1]) buf[j++] = 0; 1664 return j; 1665 overflow: 1666 return (-2); 1667 } 1668 1669 /* Finds the length of a dns request for a DNS name of the given */ 1670 /* length. The actual request may be smaller than the value returned */ 1671 /* here */ 1672 static size_t 1673 evdns_request_len(const size_t name_len) { 1674 return 96 + /* length of the DNS standard header */ 1675 name_len + 2 + 1676 4; /* space for the resource type */ 1677 } 1678 1679 /* build a dns request packet into buf. buf should be at least as long */ 1680 /* as evdns_request_len told you it should be. */ 1681 /* */ 1682 /* Returns the amount of space used. Negative on error. */ 1683 static int 1684 evdns_request_data_build(const char *const name, const size_t name_len, 1685 const u16 trans_id, const u16 type, const u16 class, 1686 u8 *const buf, size_t buf_len) { 1687 off_t j = 0; /* current offset into buf */ 1688 u16 t_; /* used by the macros */ 1689 1690 APPEND16(trans_id); 1691 APPEND16(0x0100); /* standard query, recusion needed */ 1692 APPEND16(1); /* one question */ 1693 APPEND16(0); /* no answers */ 1694 APPEND16(0); /* no authority */ 1695 APPEND16(0); /* no additional */ 1696 1697 j = dnsname_to_labels(buf, buf_len, j, name, name_len, NULL); 1698 if (j < 0) { 1699 return (int)j; 1700 } 1701 1702 APPEND16(type); 1703 APPEND16(class); 1704 1705 return (int)j; 1706 overflow: 1707 return (-1); 1708 } 1709 1710 /* exported function */ 1711 struct evdns_server_port * 1712 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) 1713 { 1714 struct evdns_server_port *port; 1715 if (flags) 1716 return NULL; /* flags not yet implemented */ 1717 if (!(port = mm_malloc(sizeof(struct evdns_server_port)))) 1718 return NULL; 1719 memset(port, 0, sizeof(struct evdns_server_port)); 1720 1721 1722 port->socket = socket; 1723 port->refcnt = 1; 1724 port->choked = 0; 1725 port->closing = 0; 1726 port->user_callback = cb; 1727 port->user_data = user_data; 1728 port->pending_replies = NULL; 1729 port->event_base = base; 1730 1731 event_assign(&port->event, port->event_base, 1732 port->socket, EV_READ | EV_PERSIST, 1733 server_port_ready_callback, port); 1734 if (event_add(&port->event, NULL) < 0) { 1735 mm_free(port); 1736 return NULL; 1737 } 1738 EVTHREAD_ALLOC_LOCK(port->lock, EVTHREAD_LOCKTYPE_RECURSIVE); 1739 return port; 1740 } 1741 1742 struct evdns_server_port * 1743 evdns_add_server_port(evutil_socket_t socket, int flags, evdns_request_callback_fn_type cb, void *user_data) 1744 { 1745 return evdns_add_server_port_with_base(NULL, socket, flags, cb, user_data); 1746 } 1747 1748 /* exported function */ 1749 void 1750 evdns_close_server_port(struct evdns_server_port *port) 1751 { 1752 EVDNS_LOCK(port); 1753 if (--port->refcnt == 0) { 1754 EVDNS_UNLOCK(port); 1755 server_port_free(port); 1756 } else { 1757 port->closing = 1; 1758 } 1759 } 1760 1761 /* exported function */ 1762 int 1763 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) 1764 { 1765 struct server_request *req = TO_SERVER_REQUEST(req_); 1766 struct server_reply_item **itemp, *item; 1767 int *countp; 1768 int result = -1; 1769 1770 EVDNS_LOCK(req->port); 1771 if (req->response) /* have we already answered? */ 1772 goto done; 1773 1774 switch (section) { 1775 case EVDNS_ANSWER_SECTION: 1776 itemp = &req->answer; 1777 countp = &req->n_answer; 1778 break; 1779 case EVDNS_AUTHORITY_SECTION: 1780 itemp = &req->authority; 1781 countp = &req->n_authority; 1782 break; 1783 case EVDNS_ADDITIONAL_SECTION: 1784 itemp = &req->additional; 1785 countp = &req->n_additional; 1786 break; 1787 default: 1788 goto done; 1789 } 1790 while (*itemp) { 1791 itemp = &((*itemp)->next); 1792 } 1793 item = mm_malloc(sizeof(struct server_reply_item)); 1794 if (!item) 1795 goto done; 1796 item->next = NULL; 1797 if (!(item->name = mm_strdup(name))) { 1798 mm_free(item); 1799 goto done; 1800 } 1801 item->type = type; 1802 item->dns_question_class = class; 1803 item->ttl = ttl; 1804 item->is_name = is_name != 0; 1805 item->datalen = 0; 1806 item->data = NULL; 1807 if (data) { 1808 if (item->is_name) { 1809 if (!(item->data = mm_strdup(data))) { 1810 mm_free(item->name); 1811 mm_free(item); 1812 goto done; 1813 } 1814 item->datalen = (u16)-1; 1815 } else { 1816 if (!(item->data = mm_malloc(datalen))) { 1817 mm_free(item->name); 1818 mm_free(item); 1819 goto done; 1820 } 1821 item->datalen = datalen; 1822 memcpy(item->data, data, datalen); 1823 } 1824 } 1825 1826 *itemp = item; 1827 ++(*countp); 1828 result = 0; 1829 done: 1830 EVDNS_UNLOCK(req->port); 1831 return result; 1832 } 1833 1834 /* exported function */ 1835 int 1836 evdns_server_request_add_a_reply(struct evdns_server_request *req, const char *name, int n, const void *addrs, int ttl) 1837 { 1838 return evdns_server_request_add_reply( 1839 req, EVDNS_ANSWER_SECTION, name, TYPE_A, CLASS_INET, 1840 ttl, n*4, 0, addrs); 1841 } 1842 1843 /* exported function */ 1844 int 1845 evdns_server_request_add_aaaa_reply(struct evdns_server_request *req, const char *name, int n, const void *addrs, int ttl) 1846 { 1847 return evdns_server_request_add_reply( 1848 req, EVDNS_ANSWER_SECTION, name, TYPE_AAAA, CLASS_INET, 1849 ttl, n*16, 0, addrs); 1850 } 1851 1852 /* exported function */ 1853 int 1854 evdns_server_request_add_ptr_reply(struct evdns_server_request *req, struct in_addr *in, const char *inaddr_name, const char *hostname, int ttl) 1855 { 1856 u32 a; 1857 char buf[32]; 1858 if (in && inaddr_name) 1859 return -1; 1860 else if (!in && !inaddr_name) 1861 return -1; 1862 if (in) { 1863 a = ntohl(in->s_addr); 1864 evutil_snprintf(buf, sizeof(buf), "%d.%d.%d.%d.in-addr.arpa", 1865 (int)(u8)((a )&0xff), 1866 (int)(u8)((a>>8 )&0xff), 1867 (int)(u8)((a>>16)&0xff), 1868 (int)(u8)((a>>24)&0xff)); 1869 inaddr_name = buf; 1870 } 1871 return evdns_server_request_add_reply( 1872 req, EVDNS_ANSWER_SECTION, inaddr_name, TYPE_PTR, CLASS_INET, 1873 ttl, -1, 1, hostname); 1874 } 1875 1876 /* exported function */ 1877 int 1878 evdns_server_request_add_cname_reply(struct evdns_server_request *req, const char *name, const char *cname, int ttl) 1879 { 1880 return evdns_server_request_add_reply( 1881 req, EVDNS_ANSWER_SECTION, name, TYPE_CNAME, CLASS_INET, 1882 ttl, -1, 1, cname); 1883 } 1884 1885 /* exported function */ 1886 void 1887 evdns_server_request_set_flags(struct evdns_server_request *exreq, int flags) 1888 { 1889 struct server_request *req = TO_SERVER_REQUEST(exreq); 1890 req->base.flags &= ~(EVDNS_FLAGS_AA|EVDNS_FLAGS_RD); 1891 req->base.flags |= flags; 1892 } 1893 1894 static int 1895 evdns_server_request_format_response(struct server_request *req, int err) 1896 { 1897 unsigned char buf[1500]; 1898 size_t buf_len = sizeof(buf); 1899 off_t j = 0, r; 1900 u16 t_; 1901 u32 t32_; 1902 int i; 1903 u16 flags; 1904 struct dnslabel_table table; 1905 1906 if (err < 0 || err > 15) return -1; 1907 1908 /* Set response bit and error code; copy OPCODE and RD fields from 1909 * question; copy RA and AA if set by caller. */ 1910 flags = req->base.flags; 1911 flags |= (0x8000 | err); 1912 1913 dnslabel_table_init(&table); 1914 APPEND16(req->trans_id); 1915 APPEND16(flags); 1916 APPEND16(req->base.nquestions); 1917 APPEND16(req->n_answer); 1918 APPEND16(req->n_authority); 1919 APPEND16(req->n_additional); 1920 1921 /* Add questions. */ 1922 for (i=0; i < req->base.nquestions; ++i) { 1923 const char *s = req->base.questions[i]->name; 1924 j = dnsname_to_labels(buf, buf_len, j, s, strlen(s), &table); 1925 if (j < 0) { 1926 dnslabel_clear(&table); 1927 return (int) j; 1928 } 1929 APPEND16(req->base.questions[i]->type); 1930 APPEND16(req->base.questions[i]->dns_question_class); 1931 } 1932 1933 /* Add answer, authority, and additional sections. */ 1934 for (i=0; i<3; ++i) { 1935 struct server_reply_item *item; 1936 if (i==0) 1937 item = req->answer; 1938 else if (i==1) 1939 item = req->authority; 1940 else 1941 item = req->additional; 1942 while (item) { 1943 r = dnsname_to_labels(buf, buf_len, j, item->name, strlen(item->name), &table); 1944 if (r < 0) 1945 goto overflow; 1946 j = r; 1947 1948 APPEND16(item->type); 1949 APPEND16(item->dns_question_class); 1950 APPEND32(item->ttl); 1951 if (item->is_name) { 1952 off_t len_idx = j, name_start; 1953 j += 2; 1954 name_start = j; 1955 r = dnsname_to_labels(buf, buf_len, j, item->data, strlen(item->data), &table); 1956 if (r < 0) 1957 goto overflow; 1958 j = r; 1959 t_ = htons( (short) (j-name_start) ); 1960 memcpy(buf+len_idx, &t_, 2); 1961 } else { 1962 APPEND16(item->datalen); 1963 if (j+item->datalen > (off_t)buf_len) 1964 goto overflow; 1965 memcpy(buf+j, item->data, item->datalen); 1966 j += item->datalen; 1967 } 1968 item = item->next; 1969 } 1970 } 1971 1972 if (j > 512) { 1973 overflow: 1974 j = 512; 1975 buf[2] |= 0x02; /* set the truncated bit. */ 1976 } 1977 1978 req->response_len = j; 1979 1980 if (!(req->response = mm_malloc(req->response_len))) { 1981 server_request_free_answers(req); 1982 dnslabel_clear(&table); 1983 return (-1); 1984 } 1985 memcpy(req->response, buf, req->response_len); 1986 server_request_free_answers(req); 1987 dnslabel_clear(&table); 1988 return (0); 1989 } 1990 1991 /* exported function */ 1992 int 1993 evdns_server_request_respond(struct evdns_server_request *req_, int err) 1994 { 1995 struct server_request *req = TO_SERVER_REQUEST(req_); 1996 struct evdns_server_port *port = req->port; 1997 int r = -1; 1998 1999 EVDNS_LOCK(port); 2000 if (!req->response) { 2001 if ((r = evdns_server_request_format_response(req, err))<0) 2002 goto done; 2003 } 2004 2005 r = sendto(port->socket, req->response, (int)req->response_len, 0, 2006 (struct sockaddr*) &req->addr, (ev_socklen_t)req->addrlen); 2007 if (r<0) { 2008 int sock_err = evutil_socket_geterror(port->socket); 2009 if (EVUTIL_ERR_RW_RETRIABLE(sock_err)) 2010 goto done; 2011 2012 if (port->pending_replies) { 2013 req->prev_pending = port->pending_replies->prev_pending; 2014 req->next_pending = port->pending_replies; 2015 req->prev_pending->next_pending = 2016 req->next_pending->prev_pending = req; 2017 } else { 2018 req->prev_pending = req->next_pending = req; 2019 port->pending_replies = req; 2020 port->choked = 1; 2021 2022 (void) event_del(&port->event); 2023 event_assign(&port->event, port->event_base, port->socket, (port->closing?0:EV_READ) | EV_WRITE | EV_PERSIST, server_port_ready_callback, port); 2024 2025 if (event_add(&port->event, NULL) < 0) { 2026 log(EVDNS_LOG_WARN, "Error from libevent when adding event for DNS server"); 2027 } 2028 2029 } 2030 2031 r = 1; 2032 goto done; 2033 } 2034 if (server_request_free(req)) { 2035 r = 0; 2036 goto done; 2037 } 2038 2039 if (port->pending_replies) 2040 server_port_flush(port); 2041 2042 r = 0; 2043 done: 2044 EVDNS_UNLOCK(port); 2045 return r; 2046 } 2047 2048 /* Free all storage held by RRs in req. */ 2049 static void 2050 server_request_free_answers(struct server_request *req) 2051 { 2052 struct server_reply_item *victim, *next, **list; 2053 int i; 2054 for (i = 0; i < 3; ++i) { 2055 if (i==0) 2056 list = &req->answer; 2057 else if (i==1) 2058 list = &req->authority; 2059 else 2060 list = &req->additional; 2061 2062 victim = *list; 2063 while (victim) { 2064 next = victim->next; 2065 mm_free(victim->name); 2066 if (victim->data) 2067 mm_free(victim->data); 2068 mm_free(victim); 2069 victim = next; 2070 } 2071 *list = NULL; 2072 } 2073 } 2074 2075 /* Free all storage held by req, and remove links to it. */ 2076 /* return true iff we just wound up freeing the server_port. */ 2077 static int 2078 server_request_free(struct server_request *req) 2079 { 2080 int i, rc=1, lock=0; 2081 if (req->base.questions) { 2082 for (i = 0; i < req->base.nquestions; ++i) 2083 mm_free(req->base.questions[i]); 2084 mm_free(req->base.questions); 2085 } 2086 2087 if (req->port) { 2088 EVDNS_LOCK(req->port); 2089 lock=1; 2090 if (req->port->pending_replies == req) { 2091 if (req->next_pending && req->next_pending != req) 2092 req->port->pending_replies = req->next_pending; 2093 else 2094 req->port->pending_replies = NULL; 2095 } 2096 rc = --req->port->refcnt; 2097 } 2098 2099 if (req->response) { 2100 mm_free(req->response); 2101 } 2102 2103 server_request_free_answers(req); 2104 2105 if (req->next_pending && req->next_pending != req) { 2106 req->next_pending->prev_pending = req->prev_pending; 2107 req->prev_pending->next_pending = req->next_pending; 2108 } 2109 2110 if (rc == 0) { 2111 EVDNS_UNLOCK(req->port); /* ????? nickm */ 2112 server_port_free(req->port); 2113 mm_free(req); 2114 return (1); 2115 } 2116 if (lock) 2117 EVDNS_UNLOCK(req->port); 2118 mm_free(req); 2119 return (0); 2120 } 2121 2122 /* Free all storage held by an evdns_server_port. Only called when */ 2123 static void 2124 server_port_free(struct evdns_server_port *port) 2125 { 2126 EVUTIL_ASSERT(port); 2127 EVUTIL_ASSERT(!port->refcnt); 2128 EVUTIL_ASSERT(!port->pending_replies); 2129 if (port->socket > 0) { 2130 evutil_closesocket(port->socket); 2131 port->socket = -1; 2132 } 2133 (void) event_del(&port->event); 2134 event_debug_unassign(&port->event); 2135 EVTHREAD_FREE_LOCK(port->lock, EVTHREAD_LOCKTYPE_RECURSIVE); 2136 mm_free(port); 2137 } 2138 2139 /* exported function */ 2140 int 2141 evdns_server_request_drop(struct evdns_server_request *req_) 2142 { 2143 struct server_request *req = TO_SERVER_REQUEST(req_); 2144 server_request_free(req); 2145 return 0; 2146 } 2147 2148 /* exported function */ 2149 int 2150 evdns_server_request_get_requesting_addr(struct evdns_server_request *req_, struct sockaddr *sa, int addr_len) 2151 { 2152 struct server_request *req = TO_SERVER_REQUEST(req_); 2153 if (addr_len < (int)req->addrlen) 2154 return -1; 2155 memcpy(sa, &(req->addr), req->addrlen); 2156 return req->addrlen; 2157 } 2158 2159 #undef APPEND16 2160 #undef APPEND32 2161 2162 /* this is a libevent callback function which is called when a request */ 2163 /* has timed out. */ 2164 static void 2165 evdns_request_timeout_callback(evutil_socket_t fd, short events, void *arg) { 2166 struct request *const req = (struct request *) arg; 2167 struct evdns_base *base = req->base; 2168 2169 (void) fd; 2170 (void) events; 2171 2172 log(EVDNS_LOG_DEBUG, "Request %p timed out", arg); 2173 EVDNS_LOCK(base); 2174 2175 if (req->tx_count >= req->base->global_max_retransmits) { 2176 struct nameserver *ns = req->ns; 2177 /* this request has failed */ 2178 log(EVDNS_LOG_DEBUG, "Giving up on request %p; tx_count==%d", 2179 arg, req->tx_count); 2180 reply_schedule_callback(req, 0, DNS_ERR_TIMEOUT, NULL); 2181 2182 request_finished(req, &REQ_HEAD(req->base, req->trans_id), 1); 2183 nameserver_failed(ns, "request timed out."); 2184 } else { 2185 /* retransmit it */ 2186 log(EVDNS_LOG_DEBUG, "Retransmitting request %p; tx_count==%d", 2187 arg, req->tx_count); 2188 (void) evtimer_del(&req->timeout_event); 2189 request_swap_ns(req, nameserver_pick(base)); 2190 evdns_request_transmit(req); 2191 2192 req->ns->timedout++; 2193 if (req->ns->timedout > req->base->global_max_nameserver_timeout) { 2194 req->ns->timedout = 0; 2195 nameserver_failed(req->ns, "request timed out."); 2196 } 2197 } 2198 2199 EVDNS_UNLOCK(base); 2200 } 2201 2202 /* try to send a request to a given server. */ 2203 /* */ 2204 /* return: */ 2205 /* 0 ok */ 2206 /* 1 temporary failure */ 2207 /* 2 other failure */ 2208 static int 2209 evdns_request_transmit_to(struct request *req, struct nameserver *server) { 2210 int r; 2211 ASSERT_LOCKED(req->base); 2212 ASSERT_VALID_REQUEST(req); 2213 2214 if (server->requests_inflight == 1 && 2215 req->base->disable_when_inactive && 2216 event_add(&server->event, NULL) < 0) { 2217 return 1; 2218 } 2219 2220 r = sendto(server->socket, (void*)req->request, req->request_len, 0, 2221 (struct sockaddr *)&server->address, server->addrlen); 2222 if (r < 0) { 2223 int err = evutil_socket_geterror(server->socket); 2224 if (EVUTIL_ERR_RW_RETRIABLE(err)) 2225 return 1; 2226 nameserver_failed(req->ns, evutil_socket_error_to_string(err)); 2227 return 2; 2228 } else if (r != (int)req->request_len) { 2229 return 1; /* short write */ 2230 } else { 2231 return 0; 2232 } 2233 } 2234 2235 /* try to send a request, updating the fields of the request */ 2236 /* as needed */ 2237 /* */ 2238 /* return: */ 2239 /* 0 ok */ 2240 /* 1 failed */ 2241 static int 2242 evdns_request_transmit(struct request *req) { 2243 int retcode = 0, r; 2244 2245 ASSERT_LOCKED(req->base); 2246 ASSERT_VALID_REQUEST(req); 2247 /* if we fail to send this packet then this flag marks it */ 2248 /* for evdns_transmit */ 2249 req->transmit_me = 1; 2250 EVUTIL_ASSERT(req->trans_id != 0xffff); 2251 2252 if (!req->ns) 2253 { 2254 /* unable to transmit request if no nameservers */ 2255 return 1; 2256 } 2257 2258 if (req->ns->choked) { 2259 /* don't bother trying to write to a socket */ 2260 /* which we have had EAGAIN from */ 2261 return 1; 2262 } 2263 2264 r = evdns_request_transmit_to(req, req->ns); 2265 switch (r) { 2266 case 1: 2267 /* temp failure */ 2268 req->ns->choked = 1; 2269 nameserver_write_waiting(req->ns, 1); 2270 return 1; 2271 case 2: 2272 /* failed to transmit the request entirely. */ 2273 retcode = 1; 2274 /* fall through: we'll set a timeout, which will time out, 2275 * and make us retransmit the request anyway. */ 2276 default: 2277 /* all ok */ 2278 log(EVDNS_LOG_DEBUG, 2279 "Setting timeout for request %p, sent to nameserver %p", req, req->ns); 2280 if (evtimer_add(&req->timeout_event, &req->base->global_timeout) < 0) { 2281 log(EVDNS_LOG_WARN, 2282 "Error from libevent when adding timer for request %p", 2283 req); 2284 /* ???? Do more? */ 2285 } 2286 req->tx_count++; 2287 req->transmit_me = 0; 2288 return retcode; 2289 } 2290 } 2291 2292 static void 2293 nameserver_probe_callback(int result, char type, int count, int ttl, void *addresses, void *arg) { 2294 struct nameserver *const ns = (struct nameserver *) arg; 2295 (void) type; 2296 (void) count; 2297 (void) ttl; 2298 (void) addresses; 2299 2300 if (result == DNS_ERR_CANCEL) { 2301 /* We canceled this request because the nameserver came up 2302 * for some other reason. Do not change our opinion about 2303 * the nameserver. */ 2304 return; 2305 } 2306 2307 EVDNS_LOCK(ns->base); 2308 ns->probe_request = NULL; 2309 if (result == DNS_ERR_NONE || result == DNS_ERR_NOTEXIST) { 2310 /* this is a good reply */ 2311 nameserver_up(ns); 2312 } else { 2313 nameserver_probe_failed(ns); 2314 } 2315 EVDNS_UNLOCK(ns->base); 2316 } 2317 2318 static void 2319 nameserver_send_probe(struct nameserver *const ns) { 2320 struct evdns_request *handle; 2321 struct request *req; 2322 char addrbuf[128]; 2323 /* here we need to send a probe to a given nameserver */ 2324 /* in the hope that it is up now. */ 2325 2326 ASSERT_LOCKED(ns->base); 2327 log(EVDNS_LOG_DEBUG, "Sending probe to %s", 2328 evutil_format_sockaddr_port_( 2329 (struct sockaddr *)&ns->address, 2330 addrbuf, sizeof(addrbuf))); 2331 handle = mm_calloc(1, sizeof(*handle)); 2332 if (!handle) return; 2333 req = request_new(ns->base, handle, TYPE_A, "google.com", DNS_QUERY_NO_SEARCH, nameserver_probe_callback, ns); 2334 if (!req) { 2335 mm_free(handle); 2336 return; 2337 } 2338 ns->probe_request = handle; 2339 /* we force this into the inflight queue no matter what */ 2340 request_trans_id_set(req, transaction_id_pick(ns->base)); 2341 req->ns = ns; 2342 request_submit(req); 2343 } 2344 2345 /* returns: */ 2346 /* 0 didn't try to transmit anything */ 2347 /* 1 tried to transmit something */ 2348 static int 2349 evdns_transmit(struct evdns_base *base) { 2350 char did_try_to_transmit = 0; 2351 int i; 2352 2353 ASSERT_LOCKED(base); 2354 for (i = 0; i < base->n_req_heads; ++i) { 2355 if (base->req_heads[i]) { 2356 struct request *const started_at = base->req_heads[i], *req = started_at; 2357 /* first transmit all the requests which are currently waiting */ 2358 do { 2359 if (req->transmit_me) { 2360 did_try_to_transmit = 1; 2361 evdns_request_transmit(req); 2362 } 2363 2364 req = req->next; 2365 } while (req != started_at); 2366 } 2367 } 2368 2369 return did_try_to_transmit; 2370 } 2371 2372 /* exported function */ 2373 int 2374 evdns_base_count_nameservers(struct evdns_base *base) 2375 { 2376 const struct nameserver *server; 2377 int n = 0; 2378 2379 EVDNS_LOCK(base); 2380 server = base->server_head; 2381 if (!server) 2382 goto done; 2383 do { 2384 ++n; 2385 server = server->next; 2386 } while (server != base->server_head); 2387 done: 2388 EVDNS_UNLOCK(base); 2389 return n; 2390 } 2391 2392 int 2393 evdns_count_nameservers(void) 2394 { 2395 return evdns_base_count_nameservers(current_base); 2396 } 2397 2398 /* exported function */ 2399 int 2400 evdns_base_clear_nameservers_and_suspend(struct evdns_base *base) 2401 { 2402 struct nameserver *server, *started_at; 2403 int i; 2404 2405 EVDNS_LOCK(base); 2406 server = base->server_head; 2407 started_at = base->server_head; 2408 if (!server) { 2409 EVDNS_UNLOCK(base); 2410 return 0; 2411 } 2412 while (1) { 2413 struct nameserver *next = server->next; 2414 (void) event_del(&server->event); 2415 if (evtimer_initialized(&server->timeout_event)) 2416 (void) evtimer_del(&server->timeout_event); 2417 if (server->probe_request) { 2418 evdns_cancel_request(server->base, server->probe_request); 2419 server->probe_request = NULL; 2420 } 2421 if (server->socket >= 0) 2422 evutil_closesocket(server->socket); 2423 mm_free(server); 2424 if (next == started_at) 2425 break; 2426 server = next; 2427 } 2428 base->server_head = NULL; 2429 base->global_good_nameservers = 0; 2430 2431 for (i = 0; i < base->n_req_heads; ++i) { 2432 struct request *req, *req_started_at; 2433 req = req_started_at = base->req_heads[i]; 2434 while (req) { 2435 struct request *next = req->next; 2436 req->tx_count = req->reissue_count = 0; 2437 req->ns = NULL; 2438 /* ???? What to do about searches? */ 2439 (void) evtimer_del(&req->timeout_event); 2440 req->trans_id = 0; 2441 req->transmit_me = 0; 2442 2443 base->global_requests_waiting++; 2444 evdns_request_insert(req, &base->req_waiting_head); 2445 /* We want to insert these suspended elements at the front of 2446 * the waiting queue, since they were pending before any of 2447 * the waiting entries were added. This is a circular list, 2448 * so we can just shift the start back by one.*/ 2449 base->req_waiting_head = base->req_waiting_head->prev; 2450 2451 if (next == req_started_at) 2452 break; 2453 req = next; 2454 } 2455 base->req_heads[i] = NULL; 2456 } 2457 2458 base->global_requests_inflight = 0; 2459 2460 EVDNS_UNLOCK(base); 2461 return 0; 2462 } 2463 2464 int 2465 evdns_clear_nameservers_and_suspend(void) 2466 { 2467 return evdns_base_clear_nameservers_and_suspend(current_base); 2468 } 2469 2470 2471 /* exported function */ 2472 int 2473 evdns_base_resume(struct evdns_base *base) 2474 { 2475 EVDNS_LOCK(base); 2476 evdns_requests_pump_waiting_queue(base); 2477 EVDNS_UNLOCK(base); 2478 2479 return 0; 2480 } 2481 2482 int 2483 evdns_resume(void) 2484 { 2485 return evdns_base_resume(current_base); 2486 } 2487 2488 static int 2489 evdns_nameserver_add_impl_(struct evdns_base *base, const struct sockaddr *address, int addrlen) { 2490 /* first check to see if we already have this nameserver */ 2491 2492 const struct nameserver *server = base->server_head, *const started_at = base->server_head; 2493 struct nameserver *ns; 2494 int err = 0; 2495 char addrbuf[128]; 2496 2497 ASSERT_LOCKED(base); 2498 if (server) { 2499 do { 2500 if (!evutil_sockaddr_cmp((struct sockaddr*)&server->address, address, 1)) return 3; 2501 server = server->next; 2502 } while (server != started_at); 2503 } 2504 if (addrlen > (int)sizeof(ns->address)) { 2505 log(EVDNS_LOG_DEBUG, "Addrlen %d too long.", (int)addrlen); 2506 return 2; 2507 } 2508 2509 ns = (struct nameserver *) mm_malloc(sizeof(struct nameserver)); 2510 if (!ns) return -1; 2511 2512 memset(ns, 0, sizeof(struct nameserver)); 2513 ns->base = base; 2514 2515 evtimer_assign(&ns->timeout_event, ns->base->event_base, nameserver_prod_callback, ns); 2516 2517 ns->socket = evutil_socket_(address->sa_family, 2518 SOCK_DGRAM|EVUTIL_SOCK_NONBLOCK|EVUTIL_SOCK_CLOEXEC, 0); 2519 if (ns->socket < 0) { err = 1; goto out1; } 2520 2521 if (base->global_outgoing_addrlen && 2522 !evutil_sockaddr_is_loopback_(address)) { 2523 if (bind(ns->socket, 2524 (struct sockaddr*)&base->global_outgoing_address, 2525 base->global_outgoing_addrlen) < 0) { 2526 log(EVDNS_LOG_WARN,"Couldn't bind to outgoing address"); 2527 err = 2; 2528 goto out2; 2529 } 2530 } 2531 2532 memcpy(&ns->address, address, addrlen); 2533 ns->addrlen = addrlen; 2534 ns->state = 1; 2535 event_assign(&ns->event, ns->base->event_base, ns->socket, 2536 EV_READ | EV_PERSIST, nameserver_ready_callback, ns); 2537 if (!base->disable_when_inactive && event_add(&ns->event, NULL) < 0) { 2538 err = 2; 2539 goto out2; 2540 } 2541 2542 log(EVDNS_LOG_DEBUG, "Added nameserver %s as %p", 2543 evutil_format_sockaddr_port_(address, addrbuf, sizeof(addrbuf)), ns); 2544 2545 /* insert this nameserver into the list of them */ 2546 if (!base->server_head) { 2547 ns->next = ns->prev = ns; 2548 base->server_head = ns; 2549 } else { 2550 ns->next = base->server_head->next; 2551 ns->prev = base->server_head; 2552 base->server_head->next = ns; 2553 ns->next->prev = ns; 2554 } 2555 2556 base->global_good_nameservers++; 2557 2558 return 0; 2559 2560 out2: 2561 evutil_closesocket(ns->socket); 2562 out1: 2563 event_debug_unassign(&ns->event); 2564 mm_free(ns); 2565 log(EVDNS_LOG_WARN, "Unable to add nameserver %s: error %d", 2566 evutil_format_sockaddr_port_(address, addrbuf, sizeof(addrbuf)), err); 2567 return err; 2568 } 2569 2570 /* exported function */ 2571 int 2572 evdns_base_nameserver_add(struct evdns_base *base, unsigned long int address) 2573 { 2574 struct sockaddr_in sin; 2575 int res; 2576 memset(&sin, 0, sizeof(sin)); 2577 sin.sin_addr.s_addr = address; 2578 sin.sin_port = htons(53); 2579 sin.sin_family = AF_INET; 2580 EVDNS_LOCK(base); 2581 res = evdns_nameserver_add_impl_(base, (struct sockaddr*)&sin, sizeof(sin)); 2582 EVDNS_UNLOCK(base); 2583 return res; 2584 } 2585 2586 int 2587 evdns_nameserver_add(unsigned long int address) { 2588 if (!current_base) 2589 current_base = evdns_base_new(NULL, 0); 2590 return evdns_base_nameserver_add(current_base, address); 2591 } 2592 2593 static void 2594 sockaddr_setport(struct sockaddr *sa, ev_uint16_t port) 2595 { 2596 if (sa->sa_family == AF_INET) { 2597 ((struct sockaddr_in *)sa)->sin_port = htons(port); 2598 } else if (sa->sa_family == AF_INET6) { 2599 ((struct sockaddr_in6 *)sa)->sin6_port = htons(port); 2600 } 2601 } 2602 2603 static ev_uint16_t 2604 sockaddr_getport(struct sockaddr *sa) 2605 { 2606 if (sa->sa_family == AF_INET) { 2607 return ntohs(((struct sockaddr_in *)sa)->sin_port); 2608 } else if (sa->sa_family == AF_INET6) { 2609 return ntohs(((struct sockaddr_in6 *)sa)->sin6_port); 2610 } else { 2611 return 0; 2612 } 2613 } 2614 2615 /* exported function */ 2616 int 2617 evdns_base_nameserver_ip_add(struct evdns_base *base, const char *ip_as_string) { 2618 struct sockaddr_storage ss; 2619 struct sockaddr *sa; 2620 int len = sizeof(ss); 2621 int res; 2622 if (evutil_parse_sockaddr_port(ip_as_string, (struct sockaddr *)&ss, 2623 &len)) { 2624 log(EVDNS_LOG_WARN, "Unable to parse nameserver address %s", 2625 ip_as_string); 2626 return 4; 2627 } 2628 sa = (struct sockaddr *) &ss; 2629 if (sockaddr_getport(sa) == 0) 2630 sockaddr_setport(sa, 53); 2631 2632 EVDNS_LOCK(base); 2633 res = evdns_nameserver_add_impl_(base, sa, len); 2634 EVDNS_UNLOCK(base); 2635 return res; 2636 } 2637 2638 int 2639 evdns_nameserver_ip_add(const char *ip_as_string) { 2640 if (!current_base) 2641 current_base = evdns_base_new(NULL, 0); 2642 return evdns_base_nameserver_ip_add(current_base, ip_as_string); 2643 } 2644 2645 int 2646 evdns_base_nameserver_sockaddr_add(struct evdns_base *base, 2647 const struct sockaddr *sa, ev_socklen_t len, unsigned flags) 2648 { 2649 int res; 2650 EVUTIL_ASSERT(base); 2651 EVDNS_LOCK(base); 2652 res = evdns_nameserver_add_impl_(base, sa, len); 2653 EVDNS_UNLOCK(base); 2654 return res; 2655 } 2656 2657 int 2658 evdns_base_get_nameserver_addr(struct evdns_base *base, int idx, 2659 struct sockaddr *sa, ev_socklen_t len) 2660 { 2661 int result = -1; 2662 int i; 2663 struct nameserver *server; 2664 EVDNS_LOCK(base); 2665 server = base->server_head; 2666 for (i = 0; i < idx && server; ++i, server = server->next) { 2667 if (server->next == base->server_head) 2668 goto done; 2669 } 2670 if (! server) 2671 goto done; 2672 2673 if (server->addrlen > len) { 2674 result = (int) server->addrlen; 2675 goto done; 2676 } 2677 2678 memcpy(sa, &server->address, server->addrlen); 2679 result = (int) server->addrlen; 2680 done: 2681 EVDNS_UNLOCK(base); 2682 return result; 2683 } 2684 2685 /* remove from the queue */ 2686 static void 2687 evdns_request_remove(struct request *req, struct request **head) 2688 { 2689 ASSERT_LOCKED(req->base); 2690 ASSERT_VALID_REQUEST(req); 2691 2692 #if 0 2693 { 2694 struct request *ptr; 2695 int found = 0; 2696 EVUTIL_ASSERT(*head != NULL); 2697 2698 ptr = *head; 2699 do { 2700 if (ptr == req) { 2701 found = 1; 2702 break; 2703 } 2704 ptr = ptr->next; 2705 } while (ptr != *head); 2706 EVUTIL_ASSERT(found); 2707 2708 EVUTIL_ASSERT(req->next); 2709 } 2710 #endif 2711 2712 if (req->next == req) { 2713 /* only item in the list */ 2714 *head = NULL; 2715 } else { 2716 req->next->prev = req->prev; 2717 req->prev->next = req->next; 2718 if (*head == req) *head = req->next; 2719 } 2720 req->next = req->prev = NULL; 2721 } 2722 2723 /* insert into the tail of the queue */ 2724 static void 2725 evdns_request_insert(struct request *req, struct request **head) { 2726 ASSERT_LOCKED(req->base); 2727 ASSERT_VALID_REQUEST(req); 2728 if (!*head) { 2729 *head = req; 2730 req->next = req->prev = req; 2731 return; 2732 } 2733 2734 req->prev = (*head)->prev; 2735 req->prev->next = req; 2736 req->next = *head; 2737 (*head)->prev = req; 2738 } 2739 2740 static int 2741 string_num_dots(const char *s) { 2742 int count = 0; 2743 while ((s = strchr(s, '.'))) { 2744 s++; 2745 count++; 2746 } 2747 return count; 2748 } 2749 2750 static struct request * 2751 request_new(struct evdns_base *base, struct evdns_request *handle, int type, 2752 const char *name, int flags, evdns_callback_type callback, 2753 void *user_ptr) { 2754 2755 const char issuing_now = 2756 (base->global_requests_inflight < base->global_max_requests_inflight) ? 1 : 0; 2757 2758 const size_t name_len = strlen(name); 2759 const size_t request_max_len = evdns_request_len(name_len); 2760 const u16 trans_id = issuing_now ? transaction_id_pick(base) : 0xffff; 2761 /* the request data is alloced in a single block with the header */ 2762 struct request *const req = 2763 mm_malloc(sizeof(struct request) + request_max_len); 2764 int rlen; 2765 char namebuf[256]; 2766 (void) flags; 2767 2768 ASSERT_LOCKED(base); 2769 2770 if (!req) return NULL; 2771 2772 if (name_len >= sizeof(namebuf)) { 2773 mm_free(req); 2774 return NULL; 2775 } 2776 2777 memset(req, 0, sizeof(struct request)); 2778 req->base = base; 2779 2780 evtimer_assign(&req->timeout_event, req->base->event_base, evdns_request_timeout_callback, req); 2781 2782 if (base->global_randomize_case) { 2783 unsigned i; 2784 char randbits[(sizeof(namebuf)+7)/8]; 2785 strlcpy(namebuf, name, sizeof(namebuf)); 2786 evutil_secure_rng_get_bytes(randbits, (name_len+7)/8); 2787 for (i = 0; i < name_len; ++i) { 2788 if (EVUTIL_ISALPHA_(namebuf[i])) { 2789 if ((randbits[i >> 3] & (1<<(i & 7)))) 2790 namebuf[i] |= 0x20; 2791 else 2792 namebuf[i] &= ~0x20; 2793 } 2794 } 2795 name = namebuf; 2796 } 2797 2798 /* request data lives just after the header */ 2799 req->request = ((u8 *) req) + sizeof(struct request); 2800 /* denotes that the request data shouldn't be free()ed */ 2801 req->request_appended = 1; 2802 rlen = evdns_request_data_build(name, name_len, trans_id, 2803 type, CLASS_INET, req->request, request_max_len); 2804 if (rlen < 0) 2805 goto err1; 2806 2807 req->request_len = rlen; 2808 req->trans_id = trans_id; 2809 req->tx_count = 0; 2810 req->request_type = type; 2811 req->user_pointer = user_ptr; 2812 req->user_callback = callback; 2813 req->ns = issuing_now ? nameserver_pick(base) : NULL; 2814 req->next = req->prev = NULL; 2815 req->handle = handle; 2816 if (handle) { 2817 handle->current_req = req; 2818 handle->base = base; 2819 } 2820 2821 return req; 2822 err1: 2823 mm_free(req); 2824 return NULL; 2825 } 2826 2827 static void 2828 request_submit(struct request *const req) { 2829 struct evdns_base *base = req->base; 2830 ASSERT_LOCKED(base); 2831 ASSERT_VALID_REQUEST(req); 2832 if (req->ns) { 2833 /* if it has a nameserver assigned then this is going */ 2834 /* straight into the inflight queue */ 2835 evdns_request_insert(req, &REQ_HEAD(base, req->trans_id)); 2836 2837 base->global_requests_inflight++; 2838 req->ns->requests_inflight++; 2839 2840 evdns_request_transmit(req); 2841 } else { 2842 evdns_request_insert(req, &base->req_waiting_head); 2843 base->global_requests_waiting++; 2844 } 2845 } 2846 2847 /* exported function */ 2848 void 2849 evdns_cancel_request(struct evdns_base *base, struct evdns_request *handle) 2850 { 2851 struct request *req; 2852 2853 if (!handle->current_req) 2854 return; 2855 2856 if (!base) { 2857 /* This redundancy is silly; can we fix it? (Not for 2.0) XXXX */ 2858 base = handle->base; 2859 if (!base) 2860 base = handle->current_req->base; 2861 } 2862 2863 EVDNS_LOCK(base); 2864 if (handle->pending_cb) { 2865 EVDNS_UNLOCK(base); 2866 return; 2867 } 2868 2869 req = handle->current_req; 2870 ASSERT_VALID_REQUEST(req); 2871 2872 reply_schedule_callback(req, 0, DNS_ERR_CANCEL, NULL); 2873 if (req->ns) { 2874 /* remove from inflight queue */ 2875 request_finished(req, &REQ_HEAD(base, req->trans_id), 1); 2876 } else { 2877 /* remove from global_waiting head */ 2878 request_finished(req, &base->req_waiting_head, 1); 2879 } 2880 EVDNS_UNLOCK(base); 2881 } 2882 2883 /* exported function */ 2884 struct evdns_request * 2885 evdns_base_resolve_ipv4(struct evdns_base *base, const char *name, int flags, 2886 evdns_callback_type callback, void *ptr) { 2887 struct evdns_request *handle; 2888 struct request *req; 2889 log(EVDNS_LOG_DEBUG, "Resolve requested for %s", name); 2890 handle = mm_calloc(1, sizeof(*handle)); 2891 if (handle == NULL) 2892 return NULL; 2893 EVDNS_LOCK(base); 2894 if (flags & DNS_QUERY_NO_SEARCH) { 2895 req = 2896 request_new(base, handle, TYPE_A, name, flags, 2897 callback, ptr); 2898 if (req) 2899 request_submit(req); 2900 } else { 2901 search_request_new(base, handle, TYPE_A, name, flags, 2902 callback, ptr); 2903 } 2904 if (handle->current_req == NULL) { 2905 mm_free(handle); 2906 handle = NULL; 2907 } 2908 EVDNS_UNLOCK(base); 2909 return handle; 2910 } 2911 2912 int evdns_resolve_ipv4(const char *name, int flags, 2913 evdns_callback_type callback, void *ptr) 2914 { 2915 return evdns_base_resolve_ipv4(current_base, name, flags, callback, ptr) 2916 ? 0 : -1; 2917 } 2918 2919 2920 /* exported function */ 2921 struct evdns_request * 2922 evdns_base_resolve_ipv6(struct evdns_base *base, 2923 const char *name, int flags, 2924 evdns_callback_type callback, void *ptr) 2925 { 2926 struct evdns_request *handle; 2927 struct request *req; 2928 log(EVDNS_LOG_DEBUG, "Resolve requested for %s", name); 2929 handle = mm_calloc(1, sizeof(*handle)); 2930 if (handle == NULL) 2931 return NULL; 2932 EVDNS_LOCK(base); 2933 if (flags & DNS_QUERY_NO_SEARCH) { 2934 req = request_new(base, handle, TYPE_AAAA, name, flags, 2935 callback, ptr); 2936 if (req) 2937 request_submit(req); 2938 } else { 2939 search_request_new(base, handle, TYPE_AAAA, name, flags, 2940 callback, ptr); 2941 } 2942 if (handle->current_req == NULL) { 2943 mm_free(handle); 2944 handle = NULL; 2945 } 2946 EVDNS_UNLOCK(base); 2947 return handle; 2948 } 2949 2950 int evdns_resolve_ipv6(const char *name, int flags, 2951 evdns_callback_type callback, void *ptr) { 2952 return evdns_base_resolve_ipv6(current_base, name, flags, callback, ptr) 2953 ? 0 : -1; 2954 } 2955 2956 struct evdns_request * 2957 evdns_base_resolve_reverse(struct evdns_base *base, const struct in_addr *in, int flags, evdns_callback_type callback, void *ptr) { 2958 char buf[32]; 2959 struct evdns_request *handle; 2960 struct request *req; 2961 u32 a; 2962 EVUTIL_ASSERT(in); 2963 a = ntohl(in->s_addr); 2964 evutil_snprintf(buf, sizeof(buf), "%d.%d.%d.%d.in-addr.arpa", 2965 (int)(u8)((a )&0xff), 2966 (int)(u8)((a>>8 )&0xff), 2967 (int)(u8)((a>>16)&0xff), 2968 (int)(u8)((a>>24)&0xff)); 2969 handle = mm_calloc(1, sizeof(*handle)); 2970 if (handle == NULL) 2971 return NULL; 2972 log(EVDNS_LOG_DEBUG, "Resolve requested for %s (reverse)", buf); 2973 EVDNS_LOCK(base); 2974 req = request_new(base, handle, TYPE_PTR, buf, flags, callback, ptr); 2975 if (req) 2976 request_submit(req); 2977 if (handle->current_req == NULL) { 2978 mm_free(handle); 2979 handle = NULL; 2980 } 2981 EVDNS_UNLOCK(base); 2982 return (handle); 2983 } 2984 2985 int evdns_resolve_reverse(const struct in_addr *in, int flags, evdns_callback_type callback, void *ptr) { 2986 return evdns_base_resolve_reverse(current_base, in, flags, callback, ptr) 2987 ? 0 : -1; 2988 } 2989 2990 struct evdns_request * 2991 evdns_base_resolve_reverse_ipv6(struct evdns_base *base, const struct in6_addr *in, int flags, evdns_callback_type callback, void *ptr) { 2992 /* 32 nybbles, 32 periods, "ip6.arpa", NUL. */ 2993 char buf[73]; 2994 char *cp; 2995 struct evdns_request *handle; 2996 struct request *req; 2997 int i; 2998 EVUTIL_ASSERT(in); 2999 cp = buf; 3000 for (i=15; i >= 0; --i) { 3001 u8 byte = in->s6_addr[i]; 3002 *cp++ = "0123456789abcdef"[byte & 0x0f]; 3003 *cp++ = '.'; 3004 *cp++ = "0123456789abcdef"[byte >> 4]; 3005 *cp++ = '.'; 3006 } 3007 EVUTIL_ASSERT(cp + strlen("ip6.arpa") < buf+sizeof(buf)); 3008 memcpy(cp, "ip6.arpa", strlen("ip6.arpa")+1); 3009 handle = mm_calloc(1, sizeof(*handle)); 3010 if (handle == NULL) 3011 return NULL; 3012 log(EVDNS_LOG_DEBUG, "Resolve requested for %s (reverse)", buf); 3013 EVDNS_LOCK(base); 3014 req = request_new(base, handle, TYPE_PTR, buf, flags, callback, ptr); 3015 if (req) 3016 request_submit(req); 3017 if (handle->current_req == NULL) { 3018 mm_free(handle); 3019 handle = NULL; 3020 } 3021 EVDNS_UNLOCK(base); 3022 return (handle); 3023 } 3024 3025 int evdns_resolve_reverse_ipv6(const struct in6_addr *in, int flags, evdns_callback_type callback, void *ptr) { 3026 return evdns_base_resolve_reverse_ipv6(current_base, in, flags, callback, ptr) 3027 ? 0 : -1; 3028 } 3029 3030 /* ================================================================= */ 3031 /* Search support */ 3032 /* */ 3033 /* the libc resolver has support for searching a number of domains */ 3034 /* to find a name. If nothing else then it takes the single domain */ 3035 /* from the gethostname() call. */ 3036 /* */ 3037 /* It can also be configured via the domain and search options in a */ 3038 /* resolv.conf. */ 3039 /* */ 3040 /* The ndots option controls how many dots it takes for the resolver */ 3041 /* to decide that a name is non-local and so try a raw lookup first. */ 3042 3043 struct search_domain { 3044 int len; 3045 struct search_domain *next; 3046 /* the text string is appended to this structure */ 3047 }; 3048 3049 struct search_state { 3050 int refcount; 3051 int ndots; 3052 int num_domains; 3053 struct search_domain *head; 3054 }; 3055 3056 static void 3057 search_state_decref(struct search_state *const state) { 3058 if (!state) return; 3059 state->refcount--; 3060 if (!state->refcount) { 3061 struct search_domain *next, *dom; 3062 for (dom = state->head; dom; dom = next) { 3063 next = dom->next; 3064 mm_free(dom); 3065 } 3066 mm_free(state); 3067 } 3068 } 3069 3070 static struct search_state * 3071 search_state_new(void) { 3072 struct search_state *state = (struct search_state *) mm_malloc(sizeof(struct search_state)); 3073 if (!state) return NULL; 3074 memset(state, 0, sizeof(struct search_state)); 3075 state->refcount = 1; 3076 state->ndots = 1; 3077 3078 return state; 3079 } 3080 3081 static void 3082 search_postfix_clear(struct evdns_base *base) { 3083 search_state_decref(base->global_search_state); 3084 3085 base->global_search_state = search_state_new(); 3086 } 3087 3088 /* exported function */ 3089 void 3090 evdns_base_search_clear(struct evdns_base *base) 3091 { 3092 EVDNS_LOCK(base); 3093 search_postfix_clear(base); 3094 EVDNS_UNLOCK(base); 3095 } 3096 3097 void 3098 evdns_search_clear(void) { 3099 evdns_base_search_clear(current_base); 3100 } 3101 3102 static void 3103 search_postfix_add(struct evdns_base *base, const char *domain) { 3104 size_t domain_len; 3105 struct search_domain *sdomain; 3106 while (domain[0] == '.') domain++; 3107 domain_len = strlen(domain); 3108 3109 ASSERT_LOCKED(base); 3110 if (!base->global_search_state) base->global_search_state = search_state_new(); 3111 if (!base->global_search_state) return; 3112 base->global_search_state->num_domains++; 3113 3114 sdomain = (struct search_domain *) mm_malloc(sizeof(struct search_domain) + domain_len); 3115 if (!sdomain) return; 3116 memcpy( ((u8 *) sdomain) + sizeof(struct search_domain), domain, domain_len); 3117 sdomain->next = base->global_search_state->head; 3118 sdomain->len = (int) domain_len; 3119 3120 base->global_search_state->head = sdomain; 3121 } 3122 3123 /* reverse the order of members in the postfix list. This is needed because, */ 3124 /* when parsing resolv.conf we push elements in the wrong order */ 3125 static void 3126 search_reverse(struct evdns_base *base) { 3127 struct search_domain *cur, *prev = NULL, *next; 3128 ASSERT_LOCKED(base); 3129 cur = base->global_search_state->head; 3130 while (cur) { 3131 next = cur->next; 3132 cur->next = prev; 3133 prev = cur; 3134 cur = next; 3135 } 3136 3137 base->global_search_state->head = prev; 3138 } 3139 3140 /* exported function */ 3141 void 3142 evdns_base_search_add(struct evdns_base *base, const char *domain) { 3143 EVDNS_LOCK(base); 3144 search_postfix_add(base, domain); 3145 EVDNS_UNLOCK(base); 3146 } 3147 void 3148 evdns_search_add(const char *domain) { 3149 evdns_base_search_add(current_base, domain); 3150 } 3151 3152 /* exported function */ 3153 void 3154 evdns_base_search_ndots_set(struct evdns_base *base, const int ndots) { 3155 EVDNS_LOCK(base); 3156 if (!base->global_search_state) base->global_search_state = search_state_new(); 3157 if (base->global_search_state) 3158 base->global_search_state->ndots = ndots; 3159 EVDNS_UNLOCK(base); 3160 } 3161 void 3162 evdns_search_ndots_set(const int ndots) { 3163 evdns_base_search_ndots_set(current_base, ndots); 3164 } 3165 3166 static void 3167 search_set_from_hostname(struct evdns_base *base) { 3168 char hostname[HOST_NAME_MAX + 1], *domainname; 3169 3170 ASSERT_LOCKED(base); 3171 search_postfix_clear(base); 3172 if (gethostname(hostname, sizeof(hostname))) return; 3173 domainname = strchr(hostname, '.'); 3174 if (!domainname) return; 3175 search_postfix_add(base, domainname); 3176 } 3177 3178 /* warning: returns malloced string */ 3179 static char * 3180 search_make_new(const struct search_state *const state, int n, const char *const base_name) { 3181 const size_t base_len = strlen(base_name); 3182 const char need_to_append_dot = base_name[base_len - 1] == '.' ? 0 : 1; 3183 struct search_domain *dom; 3184 3185 for (dom = state->head; dom; dom = dom->next) { 3186 if (!n--) { 3187 /* this is the postfix we want */ 3188 /* the actual postfix string is kept at the end of the structure */ 3189 const u8 *const postfix = ((u8 *) dom) + sizeof(struct search_domain); 3190 const int postfix_len = dom->len; 3191 char *const newname = (char *) mm_malloc(base_len + need_to_append_dot + postfix_len + 1); 3192 if (!newname) return NULL; 3193 memcpy(newname, base_name, base_len); 3194 if (need_to_append_dot) newname[base_len] = '.'; 3195 memcpy(newname + base_len + need_to_append_dot, postfix, postfix_len); 3196 newname[base_len + need_to_append_dot + postfix_len] = 0; 3197 return newname; 3198 } 3199 } 3200 3201 /* we ran off the end of the list and still didn't find the requested string */ 3202 EVUTIL_ASSERT(0); 3203 return NULL; /* unreachable; stops warnings in some compilers. */ 3204 } 3205 3206 static struct request * 3207 search_request_new(struct evdns_base *base, struct evdns_request *handle, 3208 int type, const char *const name, int flags, 3209 evdns_callback_type user_callback, void *user_arg) { 3210 ASSERT_LOCKED(base); 3211 EVUTIL_ASSERT(type == TYPE_A || type == TYPE_AAAA); 3212 EVUTIL_ASSERT(handle->current_req == NULL); 3213 if ( ((flags & DNS_QUERY_NO_SEARCH) == 0) && 3214 base->global_search_state && 3215 base->global_search_state->num_domains) { 3216 /* we have some domains to search */ 3217 struct request *req; 3218 if (string_num_dots(name) >= base->global_search_state->ndots) { 3219 req = request_new(base, handle, type, name, flags, user_callback, user_arg); 3220 if (!req) return NULL; 3221 handle->search_index = -1; 3222 } else { 3223 char *const new_name = search_make_new(base->global_search_state, 0, name); 3224 if (!new_name) return NULL; 3225 req = request_new(base, handle, type, new_name, flags, user_callback, user_arg); 3226 mm_free(new_name); 3227 if (!req) return NULL; 3228 handle->search_index = 0; 3229 } 3230 EVUTIL_ASSERT(handle->search_origname == NULL); 3231 handle->search_origname = mm_strdup(name); 3232 if (handle->search_origname == NULL) { 3233 /* XXX Should we dealloc req? If yes, how? */ 3234 if (req) 3235 mm_free(req); 3236 return NULL; 3237 } 3238 handle->search_state = base->global_search_state; 3239 handle->search_flags = flags; 3240 base->global_search_state->refcount++; 3241 request_submit(req); 3242 return req; 3243 } else { 3244 struct request *const req = request_new(base, handle, type, name, flags, user_callback, user_arg); 3245 if (!req) return NULL; 3246 request_submit(req); 3247 return req; 3248 } 3249 } 3250 3251 /* this is called when a request has failed to find a name. We need to check */ 3252 /* if it is part of a search and, if so, try the next name in the list */ 3253 /* returns: */ 3254 /* 0 another request has been submitted */ 3255 /* 1 no more requests needed */ 3256 static int 3257 search_try_next(struct evdns_request *const handle) { 3258 struct request *req = handle->current_req; 3259 struct evdns_base *base = req->base; 3260 struct request *newreq; 3261 ASSERT_LOCKED(base); 3262 if (handle->search_state) { 3263 /* it is part of a search */ 3264 char *new_name; 3265 handle->search_index++; 3266 if (handle->search_index >= handle->search_state->num_domains) { 3267 /* no more postfixes to try, however we may need to try */ 3268 /* this name without a postfix */ 3269 if (string_num_dots(handle->search_origname) < handle->search_state->ndots) { 3270 /* yep, we need to try it raw */ 3271 newreq = request_new(base, NULL, req->request_type, handle->search_origname, handle->search_flags, req->user_callback, req->user_pointer); 3272 log(EVDNS_LOG_DEBUG, "Search: trying raw query %s", handle->search_origname); 3273 if (newreq) { 3274 search_request_finished(handle); 3275 goto submit_next; 3276 } 3277 } 3278 return 1; 3279 } 3280 3281 new_name = search_make_new(handle->search_state, handle->search_index, handle->search_origname); 3282 if (!new_name) return 1; 3283 log(EVDNS_LOG_DEBUG, "Search: now trying %s (%d)", new_name, handle->search_index); 3284 newreq = request_new(base, NULL, req->request_type, new_name, handle->search_flags, req->user_callback, req->user_pointer); 3285 mm_free(new_name); 3286 if (!newreq) return 1; 3287 goto submit_next; 3288 } 3289 return 1; 3290 3291 submit_next: 3292 request_finished(req, &REQ_HEAD(req->base, req->trans_id), 0); 3293 handle->current_req = newreq; 3294 newreq->handle = handle; 3295 request_submit(newreq); 3296 return 0; 3297 } 3298 3299 static void 3300 search_request_finished(struct evdns_request *const handle) { 3301 ASSERT_LOCKED(handle->current_req->base); 3302 if (handle->search_state) { 3303 search_state_decref(handle->search_state); 3304 handle->search_state = NULL; 3305 } 3306 if (handle->search_origname) { 3307 mm_free(handle->search_origname); 3308 handle->search_origname = NULL; 3309 } 3310 } 3311 3312 /* ================================================================= */ 3313 /* Parsing resolv.conf files */ 3314 3315 static void 3316 evdns_resolv_set_defaults(struct evdns_base *base, int flags) { 3317 /* if the file isn't found then we assume a local resolver */ 3318 ASSERT_LOCKED(base); 3319 if (flags & DNS_OPTION_SEARCH) search_set_from_hostname(base); 3320 if (flags & DNS_OPTION_NAMESERVERS) evdns_base_nameserver_ip_add(base,"127.0.0.1"); 3321 } 3322 3323 #ifndef EVENT__HAVE_STRTOK_R 3324 static char * 3325 strtok_r(char *s, const char *delim, char **state) { 3326 char *cp, *start; 3327 start = cp = s ? s : *state; 3328 if (!cp) 3329 return NULL; 3330 while (*cp && !strchr(delim, *cp)) 3331 ++cp; 3332 if (!*cp) { 3333 if (cp == start) 3334 return NULL; 3335 *state = NULL; 3336 return start; 3337 } else { 3338 *cp++ = '\0'; 3339 *state = cp; 3340 return start; 3341 } 3342 } 3343 #endif 3344 3345 /* helper version of atoi which returns -1 on error */ 3346 static int 3347 strtoint(const char *const str) 3348 { 3349 char *endptr; 3350 const int r = strtol(str, &endptr, 10); 3351 if (*endptr) return -1; 3352 return r; 3353 } 3354 3355 /* Parse a number of seconds into a timeval; return -1 on error. */ 3356 static int 3357 evdns_strtotimeval(const char *const str, struct timeval *out) 3358 { 3359 double d; 3360 char *endptr; 3361 d = strtod(str, &endptr); 3362 if (*endptr) return -1; 3363 if (d < 0) return -1; 3364 out->tv_sec = (int) d; 3365 out->tv_usec = (int) ((d - (int) d)*1000000); 3366 if (out->tv_sec == 0 && out->tv_usec < 1000) /* less than 1 msec */ 3367 return -1; 3368 return 0; 3369 } 3370 3371 /* helper version of atoi that returns -1 on error and clips to bounds. */ 3372 static int 3373 strtoint_clipped(const char *const str, int min, int max) 3374 { 3375 int r = strtoint(str); 3376 if (r == -1) 3377 return r; 3378 else if (r<min) 3379 return min; 3380 else if (r>max) 3381 return max; 3382 else 3383 return r; 3384 } 3385 3386 static int 3387 evdns_base_set_max_requests_inflight(struct evdns_base *base, int maxinflight) 3388 { 3389 int old_n_heads = base->n_req_heads, n_heads; 3390 struct request **old_heads = base->req_heads, **new_heads, *req; 3391 int i; 3392 3393 ASSERT_LOCKED(base); 3394 if (maxinflight < 1) 3395 maxinflight = 1; 3396 n_heads = (maxinflight+4) / 5; 3397 EVUTIL_ASSERT(n_heads > 0); 3398 new_heads = mm_calloc(n_heads, sizeof(struct request*)); 3399 if (!new_heads) 3400 return (-1); 3401 if (old_heads) { 3402 for (i = 0; i < old_n_heads; ++i) { 3403 while (old_heads[i]) { 3404 req = old_heads[i]; 3405 evdns_request_remove(req, &old_heads[i]); 3406 evdns_request_insert(req, &new_heads[req->trans_id % n_heads]); 3407 } 3408 } 3409 mm_free(old_heads); 3410 } 3411 base->req_heads = new_heads; 3412 base->n_req_heads = n_heads; 3413 base->global_max_requests_inflight = maxinflight; 3414 return (0); 3415 } 3416 3417 /* exported function */ 3418 int 3419 evdns_base_set_option(struct evdns_base *base, 3420 const char *option, const char *val) 3421 { 3422 int res; 3423 EVDNS_LOCK(base); 3424 res = evdns_base_set_option_impl(base, option, val, DNS_OPTIONS_ALL); 3425 EVDNS_UNLOCK(base); 3426 return res; 3427 } 3428 3429 static inline int 3430 str_matches_option(const char *s1, const char *optionname) 3431 { 3432 /* Option names are given as "option:" We accept either 'option' in 3433 * s1, or 'option:randomjunk'. The latter form is to implement the 3434 * resolv.conf parser. */ 3435 size_t optlen = strlen(optionname); 3436 size_t slen = strlen(s1); 3437 if (slen == optlen || slen == optlen - 1) 3438 return !strncmp(s1, optionname, slen); 3439 else if (slen > optlen) 3440 return !strncmp(s1, optionname, optlen); 3441 else 3442 return 0; 3443 } 3444 3445 static int 3446 evdns_base_set_option_impl(struct evdns_base *base, 3447 const char *option, const char *val, int flags) 3448 { 3449 ASSERT_LOCKED(base); 3450 if (str_matches_option(option, "ndots:")) { 3451 const int ndots = strtoint(val); 3452 if (ndots == -1) return -1; 3453 if (!(flags & DNS_OPTION_SEARCH)) return 0; 3454 log(EVDNS_LOG_DEBUG, "Setting ndots to %d", ndots); 3455 if (!base->global_search_state) base->global_search_state = search_state_new(); 3456 if (!base->global_search_state) return -1; 3457 base->global_search_state->ndots = ndots; 3458 } else if (str_matches_option(option, "timeout:")) { 3459 struct timeval tv; 3460 if (evdns_strtotimeval(val, &tv) == -1) return -1; 3461 if (!(flags & DNS_OPTION_MISC)) return 0; 3462 log(EVDNS_LOG_DEBUG, "Setting timeout to %s", val); 3463 memcpy(&base->global_timeout, &tv, sizeof(struct timeval)); 3464 } else if (str_matches_option(option, "getaddrinfo-allow-skew:")) { 3465 struct timeval tv; 3466 if (evdns_strtotimeval(val, &tv) == -1) return -1; 3467 if (!(flags & DNS_OPTION_MISC)) return 0; 3468 log(EVDNS_LOG_DEBUG, "Setting getaddrinfo-allow-skew to %s", 3469 val); 3470 memcpy(&base->global_getaddrinfo_allow_skew, &tv, 3471 sizeof(struct timeval)); 3472 } else if (str_matches_option(option, "max-timeouts:")) { 3473 const int maxtimeout = strtoint_clipped(val, 1, 255); 3474 if (maxtimeout == -1) return -1; 3475 if (!(flags & DNS_OPTION_MISC)) return 0; 3476 log(EVDNS_LOG_DEBUG, "Setting maximum allowed timeouts to %d", 3477 maxtimeout); 3478 base->global_max_nameserver_timeout = maxtimeout; 3479 } else if (str_matches_option(option, "max-inflight:")) { 3480 const int maxinflight = strtoint_clipped(val, 1, 65000); 3481 if (maxinflight == -1) return -1; 3482 if (!(flags & DNS_OPTION_MISC)) return 0; 3483 log(EVDNS_LOG_DEBUG, "Setting maximum inflight requests to %d", 3484 maxinflight); 3485 evdns_base_set_max_requests_inflight(base, maxinflight); 3486 } else if (str_matches_option(option, "attempts:")) { 3487 int retries = strtoint(val); 3488 if (retries == -1) return -1; 3489 if (retries > 255) retries = 255; 3490 if (!(flags & DNS_OPTION_MISC)) return 0; 3491 log(EVDNS_LOG_DEBUG, "Setting retries to %d", retries); 3492 base->global_max_retransmits = retries; 3493 } else if (str_matches_option(option, "randomize-case:")) { 3494 int randcase = strtoint(val); 3495 if (!(flags & DNS_OPTION_MISC)) return 0; 3496 base->global_randomize_case = randcase; 3497 } else if (str_matches_option(option, "bind-to:")) { 3498 /* XXX This only applies to successive nameservers, not 3499 * to already-configured ones. We might want to fix that. */ 3500 int len = sizeof(base->global_outgoing_address); 3501 if (!(flags & DNS_OPTION_NAMESERVERS)) return 0; 3502 if (evutil_parse_sockaddr_port(val, 3503 (struct sockaddr*)&base->global_outgoing_address, &len)) 3504 return -1; 3505 base->global_outgoing_addrlen = len; 3506 } else if (str_matches_option(option, "initial-probe-timeout:")) { 3507 struct timeval tv; 3508 if (evdns_strtotimeval(val, &tv) == -1) return -1; 3509 if (tv.tv_sec > 3600) 3510 tv.tv_sec = 3600; 3511 if (!(flags & DNS_OPTION_MISC)) return 0; 3512 log(EVDNS_LOG_DEBUG, "Setting initial probe timeout to %s", 3513 val); 3514 memcpy(&base->global_nameserver_probe_initial_timeout, &tv, 3515 sizeof(tv)); 3516 } 3517 return 0; 3518 } 3519 3520 int 3521 evdns_set_option(const char *option, const char *val, int flags) 3522 { 3523 if (!current_base) 3524 current_base = evdns_base_new(NULL, 0); 3525 return evdns_base_set_option(current_base, option, val); 3526 } 3527 3528 static void 3529 resolv_conf_parse_line(struct evdns_base *base, char *const start, int flags) { 3530 char *strtok_state; 3531 static const char *const delims = " \t"; 3532 #define NEXT_TOKEN strtok_r(NULL, delims, &strtok_state) 3533 3534 3535 char *const first_token = strtok_r(start, delims, &strtok_state); 3536 ASSERT_LOCKED(base); 3537 if (!first_token) return; 3538 3539 if (!strcmp(first_token, "nameserver") && (flags & DNS_OPTION_NAMESERVERS)) { 3540 const char *const nameserver = NEXT_TOKEN; 3541 3542 if (nameserver) 3543 evdns_base_nameserver_ip_add(base, nameserver); 3544 } else if (!strcmp(first_token, "domain") && (flags & DNS_OPTION_SEARCH)) { 3545 const char *const domain = NEXT_TOKEN; 3546 if (domain) { 3547 search_postfix_clear(base); 3548 search_postfix_add(base, domain); 3549 } 3550 } else if (!strcmp(first_token, "search") && (flags & DNS_OPTION_SEARCH)) { 3551 const char *domain; 3552 search_postfix_clear(base); 3553 3554 while ((domain = NEXT_TOKEN)) { 3555 search_postfix_add(base, domain); 3556 } 3557 search_reverse(base); 3558 } else if (!strcmp(first_token, "options")) { 3559 const char *option; 3560 while ((option = NEXT_TOKEN)) { 3561 const char *val = strchr(option, ':'); 3562 evdns_base_set_option_impl(base, option, val ? val+1 : "", flags); 3563 } 3564 } 3565 #undef NEXT_TOKEN 3566 } 3567 3568 /* exported function */ 3569 /* returns: */ 3570 /* 0 no errors */ 3571 /* 1 failed to open file */ 3572 /* 2 failed to stat file */ 3573 /* 3 file too large */ 3574 /* 4 out of memory */ 3575 /* 5 short read from file */ 3576 int 3577 evdns_base_resolv_conf_parse(struct evdns_base *base, int flags, const char *const filename) { 3578 int res; 3579 EVDNS_LOCK(base); 3580 res = evdns_base_resolv_conf_parse_impl(base, flags, filename); 3581 EVDNS_UNLOCK(base); 3582 return res; 3583 } 3584 3585 static char * 3586 evdns_get_default_hosts_filename(void) 3587 { 3588 #ifdef _WIN32 3589 /* Windows is a little coy about where it puts its configuration 3590 * files. Sure, they're _usually_ in C:\windows\system32, but 3591 * there's no reason in principle they couldn't be in 3592 * W:\hoboken chicken emergency\ 3593 */ 3594 char path[MAX_PATH+1]; 3595 static const char hostfile[] = "\\drivers\\etc\\hosts"; 3596 char *path_out; 3597 size_t len_out; 3598 3599 if (! SHGetSpecialFolderPathA(NULL, path, CSIDL_SYSTEM, 0)) 3600 return NULL; 3601 len_out = strlen(path)+strlen(hostfile)+1; 3602 path_out = mm_malloc(len_out); 3603 evutil_snprintf(path_out, len_out, "%s%s", path, hostfile); 3604 return path_out; 3605 #else 3606 return mm_strdup("/etc/hosts"); 3607 #endif 3608 } 3609 3610 static int 3611 evdns_base_resolv_conf_parse_impl(struct evdns_base *base, int flags, const char *const filename) { 3612 size_t n; 3613 char *resolv; 3614 char *start; 3615 int err = 0; 3616 3617 log(EVDNS_LOG_DEBUG, "Parsing resolv.conf file %s", filename); 3618 3619 if (flags & DNS_OPTION_HOSTSFILE) { 3620 char *fname = evdns_get_default_hosts_filename(); 3621 evdns_base_load_hosts(base, fname); 3622 if (fname) 3623 mm_free(fname); 3624 } 3625 3626 if ((err = evutil_read_file_(filename, &resolv, &n, 0)) < 0) { 3627 if (err == -1) { 3628 /* No file. */ 3629 evdns_resolv_set_defaults(base, flags); 3630 return 1; 3631 } else { 3632 return 2; 3633 } 3634 } 3635 3636 start = resolv; 3637 for (;;) { 3638 char *const newline = strchr(start, '\n'); 3639 if (!newline) { 3640 resolv_conf_parse_line(base, start, flags); 3641 break; 3642 } else { 3643 *newline = 0; 3644 resolv_conf_parse_line(base, start, flags); 3645 start = newline + 1; 3646 } 3647 } 3648 3649 if (!base->server_head && (flags & DNS_OPTION_NAMESERVERS)) { 3650 /* no nameservers were configured. */ 3651 evdns_base_nameserver_ip_add(base, "127.0.0.1"); 3652 err = 6; 3653 } 3654 if (flags & DNS_OPTION_SEARCH && (!base->global_search_state || base->global_search_state->num_domains == 0)) { 3655 search_set_from_hostname(base); 3656 } 3657 3658 mm_free(resolv); 3659 return err; 3660 } 3661 3662 int 3663 evdns_resolv_conf_parse(int flags, const char *const filename) { 3664 if (!current_base) 3665 current_base = evdns_base_new(NULL, 0); 3666 return evdns_base_resolv_conf_parse(current_base, flags, filename); 3667 } 3668 3669 3670 #ifdef _WIN32 3671 /* Add multiple nameservers from a space-or-comma-separated list. */ 3672 static int 3673 evdns_nameserver_ip_add_line(struct evdns_base *base, const char *ips) { 3674 const char *addr; 3675 char *buf; 3676 int r; 3677 ASSERT_LOCKED(base); 3678 while (*ips) { 3679 while (isspace(*ips) || *ips == ',' || *ips == '\t') 3680 ++ips; 3681 addr = ips; 3682 while (isdigit(*ips) || *ips == '.' || *ips == ':' || 3683 *ips=='[' || *ips==']') 3684 ++ips; 3685 buf = mm_malloc(ips-addr+1); 3686 if (!buf) return 4; 3687 memcpy(buf, addr, ips-addr); 3688 buf[ips-addr] = '\0'; 3689 r = evdns_base_nameserver_ip_add(base, buf); 3690 mm_free(buf); 3691 if (r) return r; 3692 } 3693 return 0; 3694 } 3695 3696 typedef DWORD(WINAPI *GetNetworkParams_fn_t)(FIXED_INFO *, DWORD*); 3697 3698 /* Use the windows GetNetworkParams interface in iphlpapi.dll to */ 3699 /* figure out what our nameservers are. */ 3700 static int 3701 load_nameservers_with_getnetworkparams(struct evdns_base *base) 3702 { 3703 /* Based on MSDN examples and inspection of c-ares code. */ 3704 FIXED_INFO *fixed; 3705 HMODULE handle = 0; 3706 ULONG size = sizeof(FIXED_INFO); 3707 void *buf = NULL; 3708 int status = 0, r, added_any; 3709 IP_ADDR_STRING *ns; 3710 GetNetworkParams_fn_t fn; 3711 3712 ASSERT_LOCKED(base); 3713 if (!(handle = evutil_load_windows_system_library_( 3714 TEXT("iphlpapi.dll")))) { 3715 log(EVDNS_LOG_WARN, "Could not open iphlpapi.dll"); 3716 status = -1; 3717 goto done; 3718 } 3719 if (!(fn = (GetNetworkParams_fn_t) GetProcAddress(handle, "GetNetworkParams"))) { 3720 log(EVDNS_LOG_WARN, "Could not get address of function."); 3721 status = -1; 3722 goto done; 3723 } 3724 3725 buf = mm_malloc(size); 3726 if (!buf) { status = 4; goto done; } 3727 fixed = buf; 3728 r = fn(fixed, &size); 3729 if (r != ERROR_SUCCESS && r != ERROR_BUFFER_OVERFLOW) { 3730 status = -1; 3731 goto done; 3732 } 3733 if (r != ERROR_SUCCESS) { 3734 mm_free(buf); 3735 buf = mm_malloc(size); 3736 if (!buf) { status = 4; goto done; } 3737 fixed = buf; 3738 r = fn(fixed, &size); 3739 if (r != ERROR_SUCCESS) { 3740 log(EVDNS_LOG_DEBUG, "fn() failed."); 3741 status = -1; 3742 goto done; 3743 } 3744 } 3745 3746 EVUTIL_ASSERT(fixed); 3747 added_any = 0; 3748 ns = &(fixed->DnsServerList); 3749 while (ns) { 3750 r = evdns_nameserver_ip_add_line(base, ns->IpAddress.String); 3751 if (r) { 3752 log(EVDNS_LOG_DEBUG,"Could not add nameserver %s to list,error: %d", 3753 (ns->IpAddress.String),(int)GetLastError()); 3754 status = r; 3755 } else { 3756 ++added_any; 3757 log(EVDNS_LOG_DEBUG,"Successfully added %s as nameserver",ns->IpAddress.String); 3758 } 3759 3760 ns = ns->Next; 3761 } 3762 3763 if (!added_any) { 3764 log(EVDNS_LOG_DEBUG, "No nameservers added."); 3765 if (status == 0) 3766 status = -1; 3767 } else { 3768 status = 0; 3769 } 3770 3771 done: 3772 if (buf) 3773 mm_free(buf); 3774 if (handle) 3775 FreeLibrary(handle); 3776 return status; 3777 } 3778 3779 static int 3780 config_nameserver_from_reg_key(struct evdns_base *base, HKEY key, const TCHAR *subkey) 3781 { 3782 char *buf; 3783 DWORD bufsz = 0, type = 0; 3784 int status = 0; 3785 3786 ASSERT_LOCKED(base); 3787 if (RegQueryValueEx(key, subkey, 0, &type, NULL, &bufsz) 3788 != ERROR_MORE_DATA) 3789 return -1; 3790 if (!(buf = mm_malloc(bufsz))) 3791 return -1; 3792 3793 if (RegQueryValueEx(key, subkey, 0, &type, (LPBYTE)buf, &bufsz) 3794 == ERROR_SUCCESS && bufsz > 1) { 3795 status = evdns_nameserver_ip_add_line(base,buf); 3796 } 3797 3798 mm_free(buf); 3799 return status; 3800 } 3801 3802 #define SERVICES_KEY TEXT("System\\CurrentControlSet\\Services\\") 3803 #define WIN_NS_9X_KEY SERVICES_KEY TEXT("VxD\\MSTCP") 3804 #define WIN_NS_NT_KEY SERVICES_KEY TEXT("Tcpip\\Parameters") 3805 3806 static int 3807 load_nameservers_from_registry(struct evdns_base *base) 3808 { 3809 int found = 0; 3810 int r; 3811 #define TRY(k, name) \ 3812 if (!found && config_nameserver_from_reg_key(base,k,TEXT(name)) == 0) { \ 3813 log(EVDNS_LOG_DEBUG,"Found nameservers in %s/%s",#k,name); \ 3814 found = 1; \ 3815 } else if (!found) { \ 3816 log(EVDNS_LOG_DEBUG,"Didn't find nameservers in %s/%s", \ 3817 #k,#name); \ 3818 } 3819 3820 ASSERT_LOCKED(base); 3821 3822 if (((int)GetVersion()) > 0) { /* NT */ 3823 HKEY nt_key = 0, interfaces_key = 0; 3824 3825 if (RegOpenKeyEx(HKEY_LOCAL_MACHINE, WIN_NS_NT_KEY, 0, 3826 KEY_READ, &nt_key) != ERROR_SUCCESS) { 3827 log(EVDNS_LOG_DEBUG,"Couldn't open nt key, %d",(int)GetLastError()); 3828 return -1; 3829 } 3830 r = RegOpenKeyEx(nt_key, TEXT("Interfaces"), 0, 3831 KEY_QUERY_VALUE|KEY_ENUMERATE_SUB_KEYS, 3832 &interfaces_key); 3833 if (r != ERROR_SUCCESS) { 3834 log(EVDNS_LOG_DEBUG,"Couldn't open interfaces key, %d",(int)GetLastError()); 3835 return -1; 3836 } 3837 TRY(nt_key, "NameServer"); 3838 TRY(nt_key, "DhcpNameServer"); 3839 TRY(interfaces_key, "NameServer"); 3840 TRY(interfaces_key, "DhcpNameServer"); 3841 RegCloseKey(interfaces_key); 3842 RegCloseKey(nt_key); 3843 } else { 3844 HKEY win_key = 0; 3845 if (RegOpenKeyEx(HKEY_LOCAL_MACHINE, WIN_NS_9X_KEY, 0, 3846 KEY_READ, &win_key) != ERROR_SUCCESS) { 3847 log(EVDNS_LOG_DEBUG, "Couldn't open registry key, %d", (int)GetLastError()); 3848 return -1; 3849 } 3850 TRY(win_key, "NameServer"); 3851 RegCloseKey(win_key); 3852 } 3853 3854 if (found == 0) { 3855 log(EVDNS_LOG_WARN,"Didn't find any nameservers."); 3856 } 3857 3858 return found ? 0 : -1; 3859 #undef TRY 3860 } 3861 3862 int 3863 evdns_base_config_windows_nameservers(struct evdns_base *base) 3864 { 3865 int r; 3866 char *fname; 3867 if (base == NULL) 3868 base = current_base; 3869 if (base == NULL) 3870 return -1; 3871 EVDNS_LOCK(base); 3872 fname = evdns_get_default_hosts_filename(); 3873 log(EVDNS_LOG_DEBUG, "Loading hosts entries from %s", fname); 3874 evdns_base_load_hosts(base, fname); 3875 if (fname) 3876 mm_free(fname); 3877 3878 if (load_nameservers_with_getnetworkparams(base) == 0) { 3879 EVDNS_UNLOCK(base); 3880 return 0; 3881 } 3882 r = load_nameservers_from_registry(base); 3883 3884 EVDNS_UNLOCK(base); 3885 return r; 3886 } 3887 3888 int 3889 evdns_config_windows_nameservers(void) 3890 { 3891 if (!current_base) { 3892 current_base = evdns_base_new(NULL, 1); 3893 return current_base == NULL ? -1 : 0; 3894 } else { 3895 return evdns_base_config_windows_nameservers(current_base); 3896 } 3897 } 3898 #endif 3899 3900 struct evdns_base * 3901 evdns_base_new(struct event_base *event_base, int flags) 3902 { 3903 struct evdns_base *base; 3904 3905 if (evutil_secure_rng_init() < 0) { 3906 log(EVDNS_LOG_WARN, "Unable to seed random number generator; " 3907 "DNS can't run."); 3908 return NULL; 3909 } 3910 3911 /* Give the evutil library a hook into its evdns-enabled 3912 * functionality. We can't just call evdns_getaddrinfo directly or 3913 * else libevent-core will depend on libevent-extras. */ 3914 evutil_set_evdns_getaddrinfo_fn_(evdns_getaddrinfo); 3915 3916 base = mm_malloc(sizeof(struct evdns_base)); 3917 if (base == NULL) 3918 return (NULL); 3919 memset(base, 0, sizeof(struct evdns_base)); 3920 base->req_waiting_head = NULL; 3921 3922 EVTHREAD_ALLOC_LOCK(base->lock, EVTHREAD_LOCKTYPE_RECURSIVE); 3923 EVDNS_LOCK(base); 3924 3925 /* Set max requests inflight and allocate req_heads. */ 3926 base->req_heads = NULL; 3927 3928 evdns_base_set_max_requests_inflight(base, 64); 3929 3930 base->server_head = NULL; 3931 base->event_base = event_base; 3932 base->global_good_nameservers = base->global_requests_inflight = 3933 base->global_requests_waiting = 0; 3934 3935 base->global_timeout.tv_sec = 5; 3936 base->global_timeout.tv_usec = 0; 3937 base->global_max_reissues = 1; 3938 base->global_max_retransmits = 3; 3939 base->global_max_nameserver_timeout = 3; 3940 base->global_search_state = NULL; 3941 base->global_randomize_case = 1; 3942 base->global_getaddrinfo_allow_skew.tv_sec = 3; 3943 base->global_getaddrinfo_allow_skew.tv_usec = 0; 3944 base->global_nameserver_probe_initial_timeout.tv_sec = 10; 3945 base->global_nameserver_probe_initial_timeout.tv_usec = 0; 3946 3947 TAILQ_INIT(&base->hostsdb); 3948 3949 #define EVDNS_BASE_ALL_FLAGS (0x8001) 3950 if (flags & ~EVDNS_BASE_ALL_FLAGS) { 3951 flags = EVDNS_BASE_INITIALIZE_NAMESERVERS; 3952 log(EVDNS_LOG_WARN, 3953 "Unrecognized flag passed to evdns_base_new(). Assuming " 3954 "you meant EVDNS_BASE_INITIALIZE_NAMESERVERS."); 3955 } 3956 #undef EVDNS_BASE_ALL_FLAGS 3957 3958 if (flags & EVDNS_BASE_INITIALIZE_NAMESERVERS) { 3959 int r; 3960 #ifdef _WIN32 3961 r = evdns_base_config_windows_nameservers(base); 3962 #else 3963 r = evdns_base_resolv_conf_parse(base, DNS_OPTIONS_ALL, "/etc/resolv.conf"); 3964 #endif 3965 if (r == -1) { 3966 evdns_base_free_and_unlock(base, 0); 3967 return NULL; 3968 } 3969 } 3970 if (flags & EVDNS_BASE_DISABLE_WHEN_INACTIVE) { 3971 base->disable_when_inactive = 1; 3972 } 3973 3974 EVDNS_UNLOCK(base); 3975 return base; 3976 } 3977 3978 int 3979 evdns_init(void) 3980 { 3981 struct evdns_base *base = evdns_base_new(NULL, 1); 3982 if (base) { 3983 current_base = base; 3984 return 0; 3985 } else { 3986 return -1; 3987 } 3988 } 3989 3990 const char * 3991 evdns_err_to_string(int err) 3992 { 3993 switch (err) { 3994 case DNS_ERR_NONE: return "no error"; 3995 case DNS_ERR_FORMAT: return "misformatted query"; 3996 case DNS_ERR_SERVERFAILED: return "server failed"; 3997 case DNS_ERR_NOTEXIST: return "name does not exist"; 3998 case DNS_ERR_NOTIMPL: return "query not implemented"; 3999 case DNS_ERR_REFUSED: return "refused"; 4000 4001 case DNS_ERR_TRUNCATED: return "reply truncated or ill-formed"; 4002 case DNS_ERR_UNKNOWN: return "unknown"; 4003 case DNS_ERR_TIMEOUT: return "request timed out"; 4004 case DNS_ERR_SHUTDOWN: return "dns subsystem shut down"; 4005 case DNS_ERR_CANCEL: return "dns request canceled"; 4006 case DNS_ERR_NODATA: return "no records in the reply"; 4007 default: return "[Unknown error code]"; 4008 } 4009 } 4010 4011 static void 4012 evdns_nameserver_free(struct nameserver *server) 4013 { 4014 if (server->socket >= 0) 4015 evutil_closesocket(server->socket); 4016 (void) event_del(&server->event); 4017 event_debug_unassign(&server->event); 4018 if (server->state == 0) 4019 (void) event_del(&server->timeout_event); 4020 if (server->probe_request) { 4021 evdns_cancel_request(server->base, server->probe_request); 4022 server->probe_request = NULL; 4023 } 4024 event_debug_unassign(&server->timeout_event); 4025 mm_free(server); 4026 } 4027 4028 static void 4029 evdns_base_free_and_unlock(struct evdns_base *base, int fail_requests) 4030 { 4031 struct nameserver *server, *server_next; 4032 struct search_domain *dom, *dom_next; 4033 int i; 4034 4035 /* Requires that we hold the lock. */ 4036 4037 /* TODO(nickm) we might need to refcount here. */ 4038 4039 for (server = base->server_head; server; server = server_next) { 4040 server_next = server->next; 4041 evdns_nameserver_free(server); 4042 if (server_next == base->server_head) 4043 break; 4044 } 4045 base->server_head = NULL; 4046 base->global_good_nameservers = 0; 4047 4048 for (i = 0; i < base->n_req_heads; ++i) { 4049 while (base->req_heads[i]) { 4050 if (fail_requests) 4051 reply_schedule_callback(base->req_heads[i], 0, DNS_ERR_SHUTDOWN, NULL); 4052 request_finished(base->req_heads[i], &REQ_HEAD(base, base->req_heads[i]->trans_id), 1); 4053 } 4054 } 4055 while (base->req_waiting_head) { 4056 if (fail_requests) 4057 reply_schedule_callback(base->req_waiting_head, 0, DNS_ERR_SHUTDOWN, NULL); 4058 request_finished(base->req_waiting_head, &base->req_waiting_head, 1); 4059 } 4060 base->global_requests_inflight = base->global_requests_waiting = 0; 4061 4062 4063 if (base->global_search_state) { 4064 for (dom = base->global_search_state->head; dom; dom = dom_next) { 4065 dom_next = dom->next; 4066 mm_free(dom); 4067 } 4068 mm_free(base->global_search_state); 4069 base->global_search_state = NULL; 4070 } 4071 4072 { 4073 struct hosts_entry *victim; 4074 while ((victim = TAILQ_FIRST(&base->hostsdb))) { 4075 TAILQ_REMOVE(&base->hostsdb, victim, next); 4076 mm_free(victim); 4077 } 4078 } 4079 4080 mm_free(base->req_heads); 4081 4082 EVDNS_UNLOCK(base); 4083 EVTHREAD_FREE_LOCK(base->lock, EVTHREAD_LOCKTYPE_RECURSIVE); 4084 4085 mm_free(base); 4086 } 4087 4088 void 4089 evdns_base_free(struct evdns_base *base, int fail_requests) 4090 { 4091 EVDNS_LOCK(base); 4092 evdns_base_free_and_unlock(base, fail_requests); 4093 } 4094 4095 void 4096 evdns_base_clear_host_addresses(struct evdns_base *base) 4097 { 4098 struct hosts_entry *victim; 4099 EVDNS_LOCK(base); 4100 while ((victim = TAILQ_FIRST(&base->hostsdb))) { 4101 TAILQ_REMOVE(&base->hostsdb, victim, next); 4102 mm_free(victim); 4103 } 4104 EVDNS_UNLOCK(base); 4105 } 4106 4107 void 4108 evdns_shutdown(int fail_requests) 4109 { 4110 if (current_base) { 4111 struct evdns_base *b = current_base; 4112 current_base = NULL; 4113 evdns_base_free(b, fail_requests); 4114 } 4115 evdns_log_fn = NULL; 4116 } 4117 4118 static int 4119 evdns_base_parse_hosts_line(struct evdns_base *base, char *line) 4120 { 4121 char *strtok_state; 4122 static const char *const delims = " \t"; 4123 char *const addr = strtok_r(line, delims, &strtok_state); 4124 char *hostname, *hash; 4125 struct sockaddr_storage ss; 4126 int socklen = sizeof(ss); 4127 ASSERT_LOCKED(base); 4128 4129 #define NEXT_TOKEN strtok_r(NULL, delims, &strtok_state) 4130 4131 if (!addr || *addr == '#') 4132 return 0; 4133 4134 memset(&ss, 0, sizeof(ss)); 4135 if (evutil_parse_sockaddr_port(addr, (struct sockaddr*)&ss, &socklen)<0) 4136 return -1; 4137 if (socklen > (int)sizeof(struct sockaddr_in6)) 4138 return -1; 4139 4140 if (sockaddr_getport((struct sockaddr*)&ss)) 4141 return -1; 4142 4143 while ((hostname = NEXT_TOKEN)) { 4144 struct hosts_entry *he; 4145 size_t namelen; 4146 if ((hash = strchr(hostname, '#'))) { 4147 if (hash == hostname) 4148 return 0; 4149 *hash = '\0'; 4150 } 4151 4152 namelen = strlen(hostname); 4153 4154 he = mm_calloc(1, sizeof(struct hosts_entry)+namelen); 4155 if (!he) 4156 return -1; 4157 EVUTIL_ASSERT(socklen <= (int)sizeof(he->addr)); 4158 memcpy(&he->addr, &ss, socklen); 4159 memcpy(he->hostname, hostname, namelen+1); 4160 he->addrlen = socklen; 4161 4162 TAILQ_INSERT_TAIL(&base->hostsdb, he, next); 4163 4164 if (hash) 4165 return 0; 4166 } 4167 4168 return 0; 4169 #undef NEXT_TOKEN 4170 } 4171 4172 static int 4173 evdns_base_load_hosts_impl(struct evdns_base *base, const char *hosts_fname) 4174 { 4175 char *str=NULL, *cp, *eol; 4176 size_t len; 4177 int err=0; 4178 4179 ASSERT_LOCKED(base); 4180 4181 if (hosts_fname == NULL || 4182 (err = evutil_read_file_(hosts_fname, &str, &len, 0)) < 0) { 4183 char tmp[64]; 4184 strlcpy(tmp, "127.0.0.1 localhost", sizeof(tmp)); 4185 evdns_base_parse_hosts_line(base, tmp); 4186 strlcpy(tmp, "::1 localhost", sizeof(tmp)); 4187 evdns_base_parse_hosts_line(base, tmp); 4188 return err ? -1 : 0; 4189 } 4190 4191 /* This will break early if there is a NUL in the hosts file. 4192 * Probably not a problem.*/ 4193 cp = str; 4194 for (;;) { 4195 eol = strchr(cp, '\n'); 4196 4197 if (eol) { 4198 *eol = '\0'; 4199 evdns_base_parse_hosts_line(base, cp); 4200 cp = eol+1; 4201 } else { 4202 evdns_base_parse_hosts_line(base, cp); 4203 break; 4204 } 4205 } 4206 4207 mm_free(str); 4208 return 0; 4209 } 4210 4211 int 4212 evdns_base_load_hosts(struct evdns_base *base, const char *hosts_fname) 4213 { 4214 int res; 4215 if (!base) 4216 base = current_base; 4217 EVDNS_LOCK(base); 4218 res = evdns_base_load_hosts_impl(base, hosts_fname); 4219 EVDNS_UNLOCK(base); 4220 return res; 4221 } 4222 4223 /* A single request for a getaddrinfo, either v4 or v6. */ 4224 struct getaddrinfo_subrequest { 4225 struct evdns_request *r; 4226 ev_uint32_t type; 4227 }; 4228 4229 /* State data used to implement an in-progress getaddrinfo. */ 4230 struct evdns_getaddrinfo_request { 4231 struct evdns_base *evdns_base; 4232 /* Copy of the modified 'hints' data that we'll use to build 4233 * answers. */ 4234 struct evutil_addrinfo hints; 4235 /* The callback to invoke when we're done */ 4236 evdns_getaddrinfo_cb user_cb; 4237 /* User-supplied data to give to the callback. */ 4238 void *user_data; 4239 /* The port to use when building sockaddrs. */ 4240 ev_uint16_t port; 4241 /* The sub_request for an A record (if any) */ 4242 struct getaddrinfo_subrequest ipv4_request; 4243 /* The sub_request for an AAAA record (if any) */ 4244 struct getaddrinfo_subrequest ipv6_request; 4245 4246 /* The cname result that we were told (if any) */ 4247 char *cname_result; 4248 4249 /* If we have one request answered and one request still inflight, 4250 * then this field holds the answer from the first request... */ 4251 struct evutil_addrinfo *pending_result; 4252 /* And this event is a timeout that will tell us to cancel the second 4253 * request if it's taking a long time. */ 4254 struct event timeout; 4255 4256 /* And this field holds the error code from the first request... */ 4257 int pending_error; 4258 /* If this is set, the user canceled this request. */ 4259 unsigned user_canceled : 1; 4260 /* If this is set, the user can no longer cancel this request; we're 4261 * just waiting for the free. */ 4262 unsigned request_done : 1; 4263 }; 4264 4265 /* Convert an evdns errors to the equivalent getaddrinfo error. */ 4266 static int 4267 evdns_err_to_getaddrinfo_err(int e1) 4268 { 4269 /* XXX Do this better! */ 4270 if (e1 == DNS_ERR_NONE) 4271 return 0; 4272 else if (e1 == DNS_ERR_NOTEXIST) 4273 return EVUTIL_EAI_NONAME; 4274 else 4275 return EVUTIL_EAI_FAIL; 4276 } 4277 4278 /* Return the more informative of two getaddrinfo errors. */ 4279 static int 4280 getaddrinfo_merge_err(int e1, int e2) 4281 { 4282 /* XXXX be cleverer here. */ 4283 if (e1 == 0) 4284 return e2; 4285 else 4286 return e1; 4287 } 4288 4289 static void 4290 free_getaddrinfo_request(struct evdns_getaddrinfo_request *data) 4291 { 4292 /* DO NOT CALL this if either of the requests is pending. Only once 4293 * both callbacks have been invoked is it safe to free the request */ 4294 if (data->pending_result) 4295 evutil_freeaddrinfo(data->pending_result); 4296 if (data->cname_result) 4297 mm_free(data->cname_result); 4298 event_del(&data->timeout); 4299 mm_free(data); 4300 return; 4301 } 4302 4303 static void 4304 add_cname_to_reply(struct evdns_getaddrinfo_request *data, 4305 struct evutil_addrinfo *ai) 4306 { 4307 if (data->cname_result && ai) { 4308 ai->ai_canonname = data->cname_result; 4309 data->cname_result = NULL; 4310 } 4311 } 4312 4313 /* Callback: invoked when one request in a mixed-format A/AAAA getaddrinfo 4314 * request has finished, but the other one took too long to answer. Pass 4315 * along the answer we got, and cancel the other request. 4316 */ 4317 static void 4318 evdns_getaddrinfo_timeout_cb(evutil_socket_t fd, short what, void *ptr) 4319 { 4320 int v4_timedout = 0, v6_timedout = 0; 4321 struct evdns_getaddrinfo_request *data = ptr; 4322 4323 /* Cancel any pending requests, and note which one */ 4324 if (data->ipv4_request.r) { 4325 /* XXXX This does nothing if the request's callback is already 4326 * running (pending_cb is set). */ 4327 evdns_cancel_request(NULL, data->ipv4_request.r); 4328 v4_timedout = 1; 4329 EVDNS_LOCK(data->evdns_base); 4330 ++data->evdns_base->getaddrinfo_ipv4_timeouts; 4331 EVDNS_UNLOCK(data->evdns_base); 4332 } 4333 if (data->ipv6_request.r) { 4334 /* XXXX This does nothing if the request's callback is already 4335 * running (pending_cb is set). */ 4336 evdns_cancel_request(NULL, data->ipv6_request.r); 4337 v6_timedout = 1; 4338 EVDNS_LOCK(data->evdns_base); 4339 ++data->evdns_base->getaddrinfo_ipv6_timeouts; 4340 EVDNS_UNLOCK(data->evdns_base); 4341 } 4342 4343 /* We only use this timeout callback when we have an answer for 4344 * one address. */ 4345 EVUTIL_ASSERT(!v4_timedout || !v6_timedout); 4346 4347 /* Report the outcome of the other request that didn't time out. */ 4348 if (data->pending_result) { 4349 add_cname_to_reply(data, data->pending_result); 4350 data->user_cb(0, data->pending_result, data->user_data); 4351 data->pending_result = NULL; 4352 } else { 4353 int e = data->pending_error; 4354 if (!e) 4355 e = EVUTIL_EAI_AGAIN; 4356 data->user_cb(e, NULL, data->user_data); 4357 } 4358 4359 data->user_cb = NULL; /* prevent double-call if evdns callbacks are 4360 * in-progress. XXXX It would be better if this 4361 * weren't necessary. */ 4362 4363 if (!v4_timedout && !v6_timedout) { 4364 /* should be impossible? XXXX */ 4365 free_getaddrinfo_request(data); 4366 } 4367 } 4368 4369 static int 4370 evdns_getaddrinfo_set_timeout(struct evdns_base *evdns_base, 4371 struct evdns_getaddrinfo_request *data) 4372 { 4373 return event_add(&data->timeout, &evdns_base->global_getaddrinfo_allow_skew); 4374 } 4375 4376 static inline int 4377 evdns_result_is_answer(int result) 4378 { 4379 return (result != DNS_ERR_NOTIMPL && result != DNS_ERR_REFUSED && 4380 result != DNS_ERR_SERVERFAILED && result != DNS_ERR_CANCEL); 4381 } 4382 4383 static void 4384 evdns_getaddrinfo_gotresolve(int result, char type, int count, 4385 int ttl, void *addresses, void *arg) 4386 { 4387 int i; 4388 struct getaddrinfo_subrequest *req = arg; 4389 struct getaddrinfo_subrequest *other_req; 4390 struct evdns_getaddrinfo_request *data; 4391 4392 struct evutil_addrinfo *res; 4393 4394 struct sockaddr_in sin; 4395 struct sockaddr_in6 sin6; 4396 struct sockaddr *sa; 4397 int socklen, addrlen; 4398 void *addrp; 4399 int err; 4400 int user_canceled; 4401 4402 EVUTIL_ASSERT(req->type == DNS_IPv4_A || req->type == DNS_IPv6_AAAA); 4403 if (req->type == DNS_IPv4_A) { 4404 data = EVUTIL_UPCAST(req, struct evdns_getaddrinfo_request, ipv4_request); 4405 other_req = &data->ipv6_request; 4406 } else { 4407 data = EVUTIL_UPCAST(req, struct evdns_getaddrinfo_request, ipv6_request); 4408 other_req = &data->ipv4_request; 4409 } 4410 4411 EVDNS_LOCK(data->evdns_base); 4412 if (evdns_result_is_answer(result)) { 4413 if (req->type == DNS_IPv4_A) 4414 ++data->evdns_base->getaddrinfo_ipv4_answered; 4415 else 4416 ++data->evdns_base->getaddrinfo_ipv6_answered; 4417 } 4418 user_canceled = data->user_canceled; 4419 if (other_req->r == NULL) 4420 data->request_done = 1; 4421 EVDNS_UNLOCK(data->evdns_base); 4422 4423 req->r = NULL; 4424 4425 if (result == DNS_ERR_CANCEL && ! user_canceled) { 4426 /* Internal cancel request from timeout or internal error. 4427 * we already answered the user. */ 4428 if (other_req->r == NULL) 4429 free_getaddrinfo_request(data); 4430 return; 4431 } 4432 4433 if (data->user_cb == NULL) { 4434 /* We already answered. XXXX This shouldn't be needed; see 4435 * comments in evdns_getaddrinfo_timeout_cb */ 4436 free_getaddrinfo_request(data); 4437 return; 4438 } 4439 4440 if (result == DNS_ERR_NONE) { 4441 if (count == 0) 4442 err = EVUTIL_EAI_NODATA; 4443 else 4444 err = 0; 4445 } else { 4446 err = evdns_err_to_getaddrinfo_err(result); 4447 } 4448 4449 if (err) { 4450 /* Looks like we got an error. */ 4451 if (other_req->r) { 4452 /* The other request is still working; maybe it will 4453 * succeed. */ 4454 /* XXXX handle failure from set_timeout */ 4455 evdns_getaddrinfo_set_timeout(data->evdns_base, data); 4456 data->pending_error = err; 4457 return; 4458 } 4459 4460 if (user_canceled) { 4461 data->user_cb(EVUTIL_EAI_CANCEL, NULL, data->user_data); 4462 } else if (data->pending_result) { 4463 /* If we have an answer waiting, and we weren't 4464 * canceled, ignore this error. */ 4465 add_cname_to_reply(data, data->pending_result); 4466 data->user_cb(0, data->pending_result, data->user_data); 4467 data->pending_result = NULL; 4468 } else { 4469 if (data->pending_error) 4470 err = getaddrinfo_merge_err(err, 4471 data->pending_error); 4472 data->user_cb(err, NULL, data->user_data); 4473 } 4474 free_getaddrinfo_request(data); 4475 return; 4476 } else if (user_canceled) { 4477 if (other_req->r) { 4478 /* The other request is still working; let it hit this 4479 * callback with EVUTIL_EAI_CANCEL callback and report 4480 * the failure. */ 4481 return; 4482 } 4483 data->user_cb(EVUTIL_EAI_CANCEL, NULL, data->user_data); 4484 free_getaddrinfo_request(data); 4485 return; 4486 } 4487 4488 /* Looks like we got some answers. We should turn them into addrinfos 4489 * and then either queue those or return them all. */ 4490 EVUTIL_ASSERT(type == DNS_IPv4_A || type == DNS_IPv6_AAAA); 4491 4492 if (type == DNS_IPv4_A) { 4493 memset(&sin, 0, sizeof(sin)); 4494 sin.sin_family = AF_INET; 4495 sin.sin_port = htons(data->port); 4496 4497 sa = (struct sockaddr *)&sin; 4498 socklen = sizeof(sin); 4499 addrlen = 4; 4500 addrp = &sin.sin_addr.s_addr; 4501 } else { 4502 memset(&sin6, 0, sizeof(sin6)); 4503 sin6.sin6_family = AF_INET6; 4504 sin6.sin6_port = htons(data->port); 4505 4506 sa = (struct sockaddr *)&sin6; 4507 socklen = sizeof(sin6); 4508 addrlen = 16; 4509 addrp = &sin6.sin6_addr.s6_addr; 4510 } 4511 4512 res = NULL; 4513 for (i=0; i < count; ++i) { 4514 struct evutil_addrinfo *ai; 4515 memcpy(addrp, ((char*)addresses)+i*addrlen, addrlen); 4516 ai = evutil_new_addrinfo_(sa, socklen, &data->hints); 4517 if (!ai) { 4518 if (other_req->r) { 4519 evdns_cancel_request(NULL, other_req->r); 4520 } 4521 data->user_cb(EVUTIL_EAI_MEMORY, NULL, data->user_data); 4522 if (res) 4523 evutil_freeaddrinfo(res); 4524 4525 if (other_req->r == NULL) 4526 free_getaddrinfo_request(data); 4527 return; 4528 } 4529 res = evutil_addrinfo_append_(res, ai); 4530 } 4531 4532 if (other_req->r) { 4533 /* The other request is still in progress; wait for it */ 4534 /* XXXX handle failure from set_timeout */ 4535 evdns_getaddrinfo_set_timeout(data->evdns_base, data); 4536 data->pending_result = res; 4537 return; 4538 } else { 4539 /* The other request is done or never started; append its 4540 * results (if any) and return them. */ 4541 if (data->pending_result) { 4542 if (req->type == DNS_IPv4_A) 4543 res = evutil_addrinfo_append_(res, 4544 data->pending_result); 4545 else 4546 res = evutil_addrinfo_append_( 4547 data->pending_result, res); 4548 data->pending_result = NULL; 4549 } 4550 4551 /* Call the user callback. */ 4552 add_cname_to_reply(data, res); 4553 data->user_cb(0, res, data->user_data); 4554 4555 /* Free data. */ 4556 free_getaddrinfo_request(data); 4557 } 4558 } 4559 4560 static struct hosts_entry * 4561 find_hosts_entry(struct evdns_base *base, const char *hostname, 4562 struct hosts_entry *find_after) 4563 { 4564 struct hosts_entry *e; 4565 4566 if (find_after) 4567 e = TAILQ_NEXT(find_after, next); 4568 else 4569 e = TAILQ_FIRST(&base->hostsdb); 4570 4571 for (; e; e = TAILQ_NEXT(e, next)) { 4572 if (!evutil_ascii_strcasecmp(e->hostname, hostname)) 4573 return e; 4574 } 4575 return NULL; 4576 } 4577 4578 static int 4579 evdns_getaddrinfo_fromhosts(struct evdns_base *base, 4580 const char *nodename, struct evutil_addrinfo *hints, ev_uint16_t port, 4581 struct evutil_addrinfo **res) 4582 { 4583 int n_found = 0; 4584 struct hosts_entry *e; 4585 struct evutil_addrinfo *ai=NULL; 4586 int f = hints->ai_family; 4587 4588 EVDNS_LOCK(base); 4589 for (e = find_hosts_entry(base, nodename, NULL); e; 4590 e = find_hosts_entry(base, nodename, e)) { 4591 struct evutil_addrinfo *ai_new; 4592 ++n_found; 4593 if ((e->addr.sa.sa_family == AF_INET && f == PF_INET6) || 4594 (e->addr.sa.sa_family == AF_INET6 && f == PF_INET)) 4595 continue; 4596 ai_new = evutil_new_addrinfo_(&e->addr.sa, e->addrlen, hints); 4597 if (!ai_new) { 4598 n_found = 0; 4599 goto out; 4600 } 4601 sockaddr_setport(ai_new->ai_addr, port); 4602 ai = evutil_addrinfo_append_(ai, ai_new); 4603 } 4604 EVDNS_UNLOCK(base); 4605 out: 4606 if (n_found) { 4607 /* Note that we return an empty answer if we found entries for 4608 * this hostname but none were of the right address type. */ 4609 *res = ai; 4610 return 0; 4611 } else { 4612 if (ai) 4613 evutil_freeaddrinfo(ai); 4614 return -1; 4615 } 4616 } 4617 4618 struct evdns_getaddrinfo_request * 4619 evdns_getaddrinfo(struct evdns_base *dns_base, 4620 const char *nodename, const char *servname, 4621 const struct evutil_addrinfo *hints_in, 4622 evdns_getaddrinfo_cb cb, void *arg) 4623 { 4624 struct evdns_getaddrinfo_request *data; 4625 struct evutil_addrinfo hints; 4626 struct evutil_addrinfo *res = NULL; 4627 int err; 4628 int port = 0; 4629 int want_cname = 0; 4630 4631 if (!dns_base) { 4632 dns_base = current_base; 4633 if (!dns_base) { 4634 log(EVDNS_LOG_WARN, 4635 "Call to getaddrinfo_async with no " 4636 "evdns_base configured."); 4637 cb(EVUTIL_EAI_FAIL, NULL, arg); /* ??? better error? */ 4638 return NULL; 4639 } 4640 } 4641 4642 /* If we _must_ answer this immediately, do so. */ 4643 if ((hints_in && (hints_in->ai_flags & EVUTIL_AI_NUMERICHOST))) { 4644 res = NULL; 4645 err = evutil_getaddrinfo(nodename, servname, hints_in, &res); 4646 cb(err, res, arg); 4647 return NULL; 4648 } 4649 4650 if (hints_in) { 4651 memcpy(&hints, hints_in, sizeof(hints)); 4652 } else { 4653 memset(&hints, 0, sizeof(hints)); 4654 hints.ai_family = PF_UNSPEC; 4655 } 4656 4657 evutil_adjust_hints_for_addrconfig_(&hints); 4658 4659 /* Now try to see if we _can_ answer immediately. */ 4660 /* (It would be nice to do this by calling getaddrinfo directly, with 4661 * AI_NUMERICHOST, on plaforms that have it, but we can't: there isn't 4662 * a reliable way to distinguish the "that wasn't a numeric host!" case 4663 * from any other EAI_NONAME cases.) */ 4664 err = evutil_getaddrinfo_common_(nodename, servname, &hints, &res, &port); 4665 if (err != EVUTIL_EAI_NEED_RESOLVE) { 4666 cb(err, res, arg); 4667 return NULL; 4668 } 4669 4670 /* If there is an entry in the hosts file, we should give it now. */ 4671 if (!evdns_getaddrinfo_fromhosts(dns_base, nodename, &hints, port, &res)) { 4672 cb(0, res, arg); 4673 return NULL; 4674 } 4675 4676 /* Okay, things are serious now. We're going to need to actually 4677 * launch a request. 4678 */ 4679 data = mm_calloc(1,sizeof(struct evdns_getaddrinfo_request)); 4680 if (!data) { 4681 cb(EVUTIL_EAI_MEMORY, NULL, arg); 4682 return NULL; 4683 } 4684 4685 memcpy(&data->hints, &hints, sizeof(data->hints)); 4686 data->port = (ev_uint16_t)port; 4687 data->ipv4_request.type = DNS_IPv4_A; 4688 data->ipv6_request.type = DNS_IPv6_AAAA; 4689 data->user_cb = cb; 4690 data->user_data = arg; 4691 data->evdns_base = dns_base; 4692 4693 want_cname = (hints.ai_flags & EVUTIL_AI_CANONNAME); 4694 4695 /* If we are asked for a PF_UNSPEC address, we launch two requests in 4696 * parallel: one for an A address and one for an AAAA address. We 4697 * can't send just one request, since many servers only answer one 4698 * question per DNS request. 4699 * 4700 * Once we have the answer to one request, we allow for a short 4701 * timeout before we report it, to see if the other one arrives. If 4702 * they both show up in time, then we report both the answers. 4703 * 4704 * If too many addresses of one type time out or fail, we should stop 4705 * launching those requests. (XXX we don't do that yet.) 4706 */ 4707 4708 if (hints.ai_family != PF_INET6) { 4709 log(EVDNS_LOG_DEBUG, "Sending request for %s on ipv4 as %p", 4710 nodename, &data->ipv4_request); 4711 4712 data->ipv4_request.r = evdns_base_resolve_ipv4(dns_base, 4713 nodename, 0, evdns_getaddrinfo_gotresolve, 4714 &data->ipv4_request); 4715 if (want_cname && data->ipv4_request.r) 4716 data->ipv4_request.r->current_req->put_cname_in_ptr = 4717 &data->cname_result; 4718 } 4719 if (hints.ai_family != PF_INET) { 4720 log(EVDNS_LOG_DEBUG, "Sending request for %s on ipv6 as %p", 4721 nodename, &data->ipv6_request); 4722 4723 data->ipv6_request.r = evdns_base_resolve_ipv6(dns_base, 4724 nodename, 0, evdns_getaddrinfo_gotresolve, 4725 &data->ipv6_request); 4726 if (want_cname && data->ipv6_request.r) 4727 data->ipv6_request.r->current_req->put_cname_in_ptr = 4728 &data->cname_result; 4729 } 4730 4731 evtimer_assign(&data->timeout, dns_base->event_base, 4732 evdns_getaddrinfo_timeout_cb, data); 4733 4734 if (data->ipv4_request.r || data->ipv6_request.r) { 4735 return data; 4736 } else { 4737 mm_free(data); 4738 cb(EVUTIL_EAI_FAIL, NULL, arg); 4739 return NULL; 4740 } 4741 } 4742 4743 void 4744 evdns_getaddrinfo_cancel(struct evdns_getaddrinfo_request *data) 4745 { 4746 EVDNS_LOCK(data->evdns_base); 4747 if (data->request_done) { 4748 EVDNS_UNLOCK(data->evdns_base); 4749 return; 4750 } 4751 event_del(&data->timeout); 4752 data->user_canceled = 1; 4753 if (data->ipv4_request.r) 4754 evdns_cancel_request(data->evdns_base, data->ipv4_request.r); 4755 if (data->ipv6_request.r) 4756 evdns_cancel_request(data->evdns_base, data->ipv6_request.r); 4757 EVDNS_UNLOCK(data->evdns_base); 4758 } 4759