1 /* Copyright 2006-2007 Niels Provos 2 * Copyright 2007-2012 Nick Mathewson and Niels Provos 3 * 4 * Redistribution and use in source and binary forms, with or without 5 * modification, are permitted provided that the following conditions 6 * are met: 7 * 1. Redistributions of source code must retain the above copyright 8 * notice, this list of conditions and the following disclaimer. 9 * 2. Redistributions in binary form must reproduce the above copyright 10 * notice, this list of conditions and the following disclaimer in the 11 * documentation and/or other materials provided with the distribution. 12 * 3. The name of the author may not be used to endorse or promote products 13 * derived from this software without specific prior written permission. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25 */ 26 27 /* Based on software by Adam Langly. Adam's original message: 28 * 29 * Async DNS Library 30 * Adam Langley <agl@imperialviolet.org> 31 * http://www.imperialviolet.org/eventdns.html 32 * Public Domain code 33 * 34 * This software is Public Domain. To view a copy of the public domain dedication, 35 * visit http://creativecommons.org/licenses/publicdomain/ or send a letter to 36 * Creative Commons, 559 Nathan Abbott Way, Stanford, California 94305, USA. 37 * 38 * I ask and expect, but do not require, that all derivative works contain an 39 * attribution similar to: 40 * Parts developed by Adam Langley <agl@imperialviolet.org> 41 * 42 * You may wish to replace the word "Parts" with something else depending on 43 * the amount of original code. 44 * 45 * (Derivative works does not include programs which link against, run or include 46 * the source verbatim in their source distributions) 47 * 48 * Version: 0.1b 49 */ 50 51 #include "event2/event-config.h" 52 #include "evconfig-private.h" 53 54 #include <sys/types.h> 55 56 #ifndef _FORTIFY_SOURCE 57 #define _FORTIFY_SOURCE 3 58 #endif 59 60 #include <string.h> 61 #include <fcntl.h> 62 #ifdef EVENT__HAVE_SYS_TIME_H 63 #include <sys/time.h> 64 #endif 65 #ifdef EVENT__HAVE_STDINT_H 66 #include <stdint.h> 67 #endif 68 #include <stdlib.h> 69 #include <string.h> 70 #include <errno.h> 71 #ifdef EVENT__HAVE_UNISTD_H 72 #include <unistd.h> 73 #endif 74 #include <limits.h> 75 #include <sys/stat.h> 76 #include <stdio.h> 77 #include <stdarg.h> 78 #ifdef _WIN32 79 #include <winsock2.h> 80 #include <winerror.h> 81 #include <ws2tcpip.h> 82 #ifndef _WIN32_IE 83 #define _WIN32_IE 0x400 84 #endif 85 #include <shlobj.h> 86 #endif 87 88 #include "event2/dns.h" 89 #include "event2/dns_struct.h" 90 #include "event2/dns_compat.h" 91 #include "event2/util.h" 92 #include "event2/event.h" 93 #include "event2/event_struct.h" 94 #include "event2/thread.h" 95 96 #include "defer-internal.h" 97 #include "log-internal.h" 98 #include "mm-internal.h" 99 #include "strlcpy-internal.h" 100 #include "ipv6-internal.h" 101 #include "util-internal.h" 102 #include "evthread-internal.h" 103 #ifdef _WIN32 104 #include <ctype.h> 105 #include <winsock2.h> 106 #include <windows.h> 107 #include <iphlpapi.h> 108 #include <io.h> 109 #else 110 #include <sys/socket.h> 111 #include <netinet/in.h> 112 #include <arpa/inet.h> 113 #endif 114 115 #ifdef EVENT__HAVE_NETINET_IN6_H 116 #include <netinet/in6.h> 117 #endif 118 119 #define EVDNS_LOG_DEBUG EVENT_LOG_DEBUG 120 #define EVDNS_LOG_WARN EVENT_LOG_WARN 121 #define EVDNS_LOG_MSG EVENT_LOG_MSG 122 123 #ifndef HOST_NAME_MAX 124 #define HOST_NAME_MAX 255 125 #endif 126 127 #include <stdio.h> 128 129 #undef MIN 130 #define MIN(a,b) ((a)<(b)?(a):(b)) 131 132 #define ASSERT_VALID_REQUEST(req) \ 133 EVUTIL_ASSERT((req)->handle && (req)->handle->current_req == (req)) 134 135 #define u64 ev_uint64_t 136 #define u32 ev_uint32_t 137 #define u16 ev_uint16_t 138 #define u8 ev_uint8_t 139 140 /* maximum number of addresses from a single packet */ 141 /* that we bother recording */ 142 #define MAX_V4_ADDRS 32 143 #define MAX_V6_ADDRS 32 144 145 146 #define TYPE_A EVDNS_TYPE_A 147 #define TYPE_CNAME 5 148 #define TYPE_PTR EVDNS_TYPE_PTR 149 #define TYPE_SOA EVDNS_TYPE_SOA 150 #define TYPE_AAAA EVDNS_TYPE_AAAA 151 152 #define CLASS_INET EVDNS_CLASS_INET 153 154 /* Persistent handle. We keep this separate from 'struct request' since we 155 * need some object to last for as long as an evdns_request is outstanding so 156 * that it can be canceled, whereas a search request can lead to multiple 157 * 'struct request' instances being created over its lifetime. */ 158 struct evdns_request { 159 struct request *current_req; 160 struct evdns_base *base; 161 162 int pending_cb; /* Waiting for its callback to be invoked; not 163 * owned by event base any more. */ 164 165 /* elements used by the searching code */ 166 int search_index; 167 struct search_state *search_state; 168 char *search_origname; /* needs to be free()ed */ 169 int search_flags; 170 }; 171 172 struct request { 173 u8 *request; /* the dns packet data */ 174 u8 request_type; /* TYPE_PTR or TYPE_A or TYPE_AAAA */ 175 unsigned int request_len; 176 int reissue_count; 177 int tx_count; /* the number of times that this packet has been sent */ 178 void *user_pointer; /* the pointer given to us for this request */ 179 evdns_callback_type user_callback; 180 struct nameserver *ns; /* the server which we last sent it */ 181 182 /* these objects are kept in a circular list */ 183 /* XXX We could turn this into a CIRCLEQ. */ 184 struct request *next, *prev; 185 186 struct event timeout_event; 187 188 u16 trans_id; /* the transaction id */ 189 unsigned request_appended :1; /* true if the request pointer is data which follows this struct */ 190 unsigned transmit_me :1; /* needs to be transmitted */ 191 192 /* XXXX This is a horrible hack. */ 193 char **put_cname_in_ptr; /* store the cname here if we get one. */ 194 195 struct evdns_base *base; 196 197 struct evdns_request *handle; 198 }; 199 200 struct reply { 201 unsigned int type; 202 unsigned int have_answer : 1; 203 union { 204 struct { 205 u32 addrcount; 206 u32 addresses[MAX_V4_ADDRS]; 207 } a; 208 struct { 209 u32 addrcount; 210 struct in6_addr addresses[MAX_V6_ADDRS]; 211 } aaaa; 212 struct { 213 char name[HOST_NAME_MAX]; 214 } ptr; 215 } data; 216 }; 217 218 struct nameserver { 219 evutil_socket_t socket; /* a connected UDP socket */ 220 struct sockaddr_storage address; 221 ev_socklen_t addrlen; 222 int failed_times; /* number of times which we have given this server a chance */ 223 int timedout; /* number of times in a row a request has timed out */ 224 struct event event; 225 /* these objects are kept in a circular list */ 226 struct nameserver *next, *prev; 227 struct event timeout_event; /* used to keep the timeout for */ 228 /* when we next probe this server. */ 229 /* Valid if state == 0 */ 230 /* Outstanding probe request for this nameserver, if any */ 231 struct evdns_request *probe_request; 232 char state; /* zero if we think that this server is down */ 233 char choked; /* true if we have an EAGAIN from this server's socket */ 234 char write_waiting; /* true if we are waiting for EV_WRITE events */ 235 struct evdns_base *base; 236 237 /* Number of currently inflight requests: used 238 * to track when we should add/del the event. */ 239 int requests_inflight; 240 }; 241 242 243 /* Represents a local port where we're listening for DNS requests. Right now, */ 244 /* only UDP is supported. */ 245 struct evdns_server_port { 246 evutil_socket_t socket; /* socket we use to read queries and write replies. */ 247 int refcnt; /* reference count. */ 248 char choked; /* Are we currently blocked from writing? */ 249 char closing; /* Are we trying to close this port, pending writes? */ 250 evdns_request_callback_fn_type user_callback; /* Fn to handle requests */ 251 void *user_data; /* Opaque pointer passed to user_callback */ 252 struct event event; /* Read/write event */ 253 /* circular list of replies that we want to write. */ 254 struct server_request *pending_replies; 255 struct event_base *event_base; 256 257 #ifndef EVENT__DISABLE_THREAD_SUPPORT 258 void *lock; 259 #endif 260 }; 261 262 /* Represents part of a reply being built. (That is, a single RR.) */ 263 struct server_reply_item { 264 struct server_reply_item *next; /* next item in sequence. */ 265 char *name; /* name part of the RR */ 266 u16 type; /* The RR type */ 267 u16 class; /* The RR class (usually CLASS_INET) */ 268 u32 ttl; /* The RR TTL */ 269 char is_name; /* True iff data is a label */ 270 u16 datalen; /* Length of data; -1 if data is a label */ 271 void *data; /* The contents of the RR */ 272 }; 273 274 /* Represents a request that we've received as a DNS server, and holds */ 275 /* the components of the reply as we're constructing it. */ 276 struct server_request { 277 /* Pointers to the next and previous entries on the list of replies */ 278 /* that we're waiting to write. Only set if we have tried to respond */ 279 /* and gotten EAGAIN. */ 280 struct server_request *next_pending; 281 struct server_request *prev_pending; 282 283 u16 trans_id; /* Transaction id. */ 284 struct evdns_server_port *port; /* Which port received this request on? */ 285 struct sockaddr_storage addr; /* Where to send the response */ 286 ev_socklen_t addrlen; /* length of addr */ 287 288 int n_answer; /* how many answer RRs have been set? */ 289 int n_authority; /* how many authority RRs have been set? */ 290 int n_additional; /* how many additional RRs have been set? */ 291 292 struct server_reply_item *answer; /* linked list of answer RRs */ 293 struct server_reply_item *authority; /* linked list of authority RRs */ 294 struct server_reply_item *additional; /* linked list of additional RRs */ 295 296 /* Constructed response. Only set once we're ready to send a reply. */ 297 /* Once this is set, the RR fields are cleared, and no more should be set. */ 298 char *response; 299 size_t response_len; 300 301 /* Caller-visible fields: flags, questions. */ 302 struct evdns_server_request base; 303 }; 304 305 struct evdns_base { 306 /* An array of n_req_heads circular lists for inflight requests. 307 * Each inflight request req is in req_heads[req->trans_id % n_req_heads]. 308 */ 309 struct request **req_heads; 310 /* A circular list of requests that we're waiting to send, but haven't 311 * sent yet because there are too many requests inflight */ 312 struct request *req_waiting_head; 313 /* A circular list of nameservers. */ 314 struct nameserver *server_head; 315 int n_req_heads; 316 317 struct event_base *event_base; 318 319 /* The number of good nameservers that we have */ 320 int global_good_nameservers; 321 322 /* inflight requests are contained in the req_head list */ 323 /* and are actually going out across the network */ 324 int global_requests_inflight; 325 /* requests which aren't inflight are in the waiting list */ 326 /* and are counted here */ 327 int global_requests_waiting; 328 329 int global_max_requests_inflight; 330 331 struct timeval global_timeout; /* 5 seconds by default */ 332 int global_max_reissues; /* a reissue occurs when we get some errors from the server */ 333 int global_max_retransmits; /* number of times we'll retransmit a request which timed out */ 334 /* number of timeouts in a row before we consider this server to be down */ 335 int global_max_nameserver_timeout; 336 /* true iff we will use the 0x20 hack to prevent poisoning attacks. */ 337 int global_randomize_case; 338 339 /* The first time that a nameserver fails, how long do we wait before 340 * probing to see if it has returned? */ 341 struct timeval global_nameserver_probe_initial_timeout; 342 343 /** Port to bind to for outgoing DNS packets. */ 344 struct sockaddr_storage global_outgoing_address; 345 /** ev_socklen_t for global_outgoing_address. 0 if it isn't set. */ 346 ev_socklen_t global_outgoing_addrlen; 347 348 struct timeval global_getaddrinfo_allow_skew; 349 350 int so_rcvbuf; 351 int so_sndbuf; 352 353 int getaddrinfo_ipv4_timeouts; 354 int getaddrinfo_ipv6_timeouts; 355 int getaddrinfo_ipv4_answered; 356 int getaddrinfo_ipv6_answered; 357 358 struct search_state *global_search_state; 359 360 TAILQ_HEAD(hosts_list, hosts_entry) hostsdb; 361 362 #ifndef EVENT__DISABLE_THREAD_SUPPORT 363 void *lock; 364 #endif 365 366 int disable_when_inactive; 367 }; 368 369 struct hosts_entry { 370 TAILQ_ENTRY(hosts_entry) next; 371 union { 372 struct sockaddr sa; 373 struct sockaddr_in sin; 374 struct sockaddr_in6 sin6; 375 } addr; 376 int addrlen; 377 char hostname[1]; 378 }; 379 380 static struct evdns_base *current_base = NULL; 381 382 struct evdns_base * 383 evdns_get_global_base(void) 384 { 385 return current_base; 386 } 387 388 /* Given a pointer to an evdns_server_request, get the corresponding */ 389 /* server_request. */ 390 #define TO_SERVER_REQUEST(base_ptr) \ 391 ((struct server_request*) \ 392 (((char*)(base_ptr) - evutil_offsetof(struct server_request, base)))) 393 394 #define REQ_HEAD(base, id) ((base)->req_heads[id % (base)->n_req_heads]) 395 396 static struct nameserver *nameserver_pick(struct evdns_base *base); 397 static void evdns_request_insert(struct request *req, struct request **head); 398 static void evdns_request_remove(struct request *req, struct request **head); 399 static void nameserver_ready_callback(evutil_socket_t fd, short events, void *arg); 400 static int evdns_transmit(struct evdns_base *base); 401 static int evdns_request_transmit(struct request *req); 402 static void nameserver_send_probe(struct nameserver *const ns); 403 static void search_request_finished(struct evdns_request *const); 404 static int search_try_next(struct evdns_request *const req); 405 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); 406 static void evdns_requests_pump_waiting_queue(struct evdns_base *base); 407 static u16 transaction_id_pick(struct evdns_base *base); 408 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); 409 static void request_submit(struct request *const req); 410 411 static int server_request_free(struct server_request *req); 412 static void server_request_free_answers(struct server_request *req); 413 static void server_port_free(struct evdns_server_port *port); 414 static void server_port_ready_callback(evutil_socket_t fd, short events, void *arg); 415 static int evdns_base_resolv_conf_parse_impl(struct evdns_base *base, int flags, const char *const filename); 416 static int evdns_base_set_option_impl(struct evdns_base *base, 417 const char *option, const char *val, int flags); 418 static void evdns_base_free_and_unlock(struct evdns_base *base, int fail_requests); 419 static void evdns_request_timeout_callback(evutil_socket_t fd, short events, void *arg); 420 421 static int strtoint(const char *const str); 422 423 #ifdef EVENT__DISABLE_THREAD_SUPPORT 424 #define EVDNS_LOCK(base) EVUTIL_NIL_STMT_ 425 #define EVDNS_UNLOCK(base) EVUTIL_NIL_STMT_ 426 #define ASSERT_LOCKED(base) EVUTIL_NIL_STMT_ 427 #else 428 #define EVDNS_LOCK(base) \ 429 EVLOCK_LOCK((base)->lock, 0) 430 #define EVDNS_UNLOCK(base) \ 431 EVLOCK_UNLOCK((base)->lock, 0) 432 #define ASSERT_LOCKED(base) \ 433 EVLOCK_ASSERT_LOCKED((base)->lock) 434 #endif 435 436 static evdns_debug_log_fn_type evdns_log_fn = NULL; 437 438 void 439 evdns_set_log_fn(evdns_debug_log_fn_type fn) 440 { 441 evdns_log_fn = fn; 442 } 443 444 #ifdef __GNUC__ 445 #define EVDNS_LOG_CHECK __attribute__ ((format(printf, 2, 3))) 446 #else 447 #define EVDNS_LOG_CHECK 448 #endif 449 450 static void evdns_log_(int severity, const char *fmt, ...) EVDNS_LOG_CHECK; 451 static void 452 evdns_log_(int severity, const char *fmt, ...) 453 { 454 va_list args; 455 va_start(args,fmt); 456 if (evdns_log_fn) { 457 char buf[512]; 458 int is_warn = (severity == EVDNS_LOG_WARN); 459 evutil_vsnprintf(buf, sizeof(buf), fmt, args); 460 evdns_log_fn(is_warn, buf); 461 } else { 462 event_logv_(severity, NULL, fmt, args); 463 } 464 va_end(args); 465 } 466 467 #define log evdns_log_ 468 469 /* This walks the list of inflight requests to find the */ 470 /* one with a matching transaction id. Returns NULL on */ 471 /* failure */ 472 static struct request * 473 request_find_from_trans_id(struct evdns_base *base, u16 trans_id) { 474 struct request *req = REQ_HEAD(base, trans_id); 475 struct request *const started_at = req; 476 477 ASSERT_LOCKED(base); 478 479 if (req) { 480 do { 481 if (req->trans_id == trans_id) return req; 482 req = req->next; 483 } while (req != started_at); 484 } 485 486 return NULL; 487 } 488 489 /* a libevent callback function which is called when a nameserver */ 490 /* has gone down and we want to test if it has came back to life yet */ 491 static void 492 nameserver_prod_callback(evutil_socket_t fd, short events, void *arg) { 493 struct nameserver *const ns = (struct nameserver *) arg; 494 (void)fd; 495 (void)events; 496 497 EVDNS_LOCK(ns->base); 498 nameserver_send_probe(ns); 499 EVDNS_UNLOCK(ns->base); 500 } 501 502 /* a libevent callback which is called when a nameserver probe (to see if */ 503 /* it has come back to life) times out. We increment the count of failed_times */ 504 /* and wait longer to send the next probe packet. */ 505 static void 506 nameserver_probe_failed(struct nameserver *const ns) { 507 struct timeval timeout; 508 int i; 509 510 ASSERT_LOCKED(ns->base); 511 (void) evtimer_del(&ns->timeout_event); 512 if (ns->state == 1) { 513 /* This can happen if the nameserver acts in a way which makes us mark */ 514 /* it as bad and then starts sending good replies. */ 515 return; 516 } 517 518 #define MAX_PROBE_TIMEOUT 3600 519 #define TIMEOUT_BACKOFF_FACTOR 3 520 521 memcpy(&timeout, &ns->base->global_nameserver_probe_initial_timeout, 522 sizeof(struct timeval)); 523 for (i=ns->failed_times; i > 0 && timeout.tv_sec < MAX_PROBE_TIMEOUT; --i) { 524 timeout.tv_sec *= TIMEOUT_BACKOFF_FACTOR; 525 timeout.tv_usec *= TIMEOUT_BACKOFF_FACTOR; 526 if (timeout.tv_usec > 1000000) { 527 timeout.tv_sec += timeout.tv_usec / 1000000; 528 timeout.tv_usec %= 1000000; 529 } 530 } 531 if (timeout.tv_sec > MAX_PROBE_TIMEOUT) { 532 timeout.tv_sec = MAX_PROBE_TIMEOUT; 533 timeout.tv_usec = 0; 534 } 535 536 ns->failed_times++; 537 538 if (evtimer_add(&ns->timeout_event, &timeout) < 0) { 539 char addrbuf[128]; 540 log(EVDNS_LOG_WARN, 541 "Error from libevent when adding timer event for %s", 542 evutil_format_sockaddr_port_( 543 (struct sockaddr *)&ns->address, 544 addrbuf, sizeof(addrbuf))); 545 } 546 } 547 548 static void 549 request_swap_ns(struct request *req, struct nameserver *ns) { 550 if (ns && req->ns != ns) { 551 EVUTIL_ASSERT(req->ns->requests_inflight > 0); 552 req->ns->requests_inflight--; 553 ns->requests_inflight++; 554 555 req->ns = ns; 556 } 557 } 558 559 /* called when a nameserver has been deemed to have failed. For example, too */ 560 /* many packets have timed out etc */ 561 static void 562 nameserver_failed(struct nameserver *const ns, const char *msg) { 563 struct request *req, *started_at; 564 struct evdns_base *base = ns->base; 565 int i; 566 char addrbuf[128]; 567 568 ASSERT_LOCKED(base); 569 /* if this nameserver has already been marked as failed */ 570 /* then don't do anything */ 571 if (!ns->state) return; 572 573 log(EVDNS_LOG_MSG, "Nameserver %s has failed: %s", 574 evutil_format_sockaddr_port_( 575 (struct sockaddr *)&ns->address, 576 addrbuf, sizeof(addrbuf)), 577 msg); 578 579 base->global_good_nameservers--; 580 EVUTIL_ASSERT(base->global_good_nameservers >= 0); 581 if (base->global_good_nameservers == 0) { 582 log(EVDNS_LOG_MSG, "All nameservers have failed"); 583 } 584 585 ns->state = 0; 586 ns->failed_times = 1; 587 588 if (evtimer_add(&ns->timeout_event, 589 &base->global_nameserver_probe_initial_timeout) < 0) { 590 log(EVDNS_LOG_WARN, 591 "Error from libevent when adding timer event for %s", 592 evutil_format_sockaddr_port_( 593 (struct sockaddr *)&ns->address, 594 addrbuf, sizeof(addrbuf))); 595 /* ???? Do more? */ 596 } 597 598 /* walk the list of inflight requests to see if any can be reassigned to */ 599 /* a different server. Requests in the waiting queue don't have a */ 600 /* nameserver assigned yet */ 601 602 /* if we don't have *any* good nameservers then there's no point */ 603 /* trying to reassign requests to one */ 604 if (!base->global_good_nameservers) return; 605 606 for (i = 0; i < base->n_req_heads; ++i) { 607 req = started_at = base->req_heads[i]; 608 if (req) { 609 do { 610 if (req->tx_count == 0 && req->ns == ns) { 611 /* still waiting to go out, can be moved */ 612 /* to another server */ 613 request_swap_ns(req, nameserver_pick(base)); 614 } 615 req = req->next; 616 } while (req != started_at); 617 } 618 } 619 } 620 621 static void 622 nameserver_up(struct nameserver *const ns) 623 { 624 char addrbuf[128]; 625 ASSERT_LOCKED(ns->base); 626 if (ns->state) return; 627 log(EVDNS_LOG_MSG, "Nameserver %s is back up", 628 evutil_format_sockaddr_port_( 629 (struct sockaddr *)&ns->address, 630 addrbuf, sizeof(addrbuf))); 631 evtimer_del(&ns->timeout_event); 632 if (ns->probe_request) { 633 evdns_cancel_request(ns->base, ns->probe_request); 634 ns->probe_request = NULL; 635 } 636 ns->state = 1; 637 ns->failed_times = 0; 638 ns->timedout = 0; 639 ns->base->global_good_nameservers++; 640 } 641 642 static void 643 request_trans_id_set(struct request *const req, const u16 trans_id) { 644 req->trans_id = trans_id; 645 *((u16 *) req->request) = htons(trans_id); 646 } 647 648 /* Called to remove a request from a list and dealloc it. */ 649 /* head is a pointer to the head of the list it should be */ 650 /* removed from or NULL if the request isn't in a list. */ 651 /* when free_handle is one, free the handle as well. */ 652 static void 653 request_finished(struct request *const req, struct request **head, int free_handle) { 654 struct evdns_base *base = req->base; 655 int was_inflight = (head != &base->req_waiting_head); 656 EVDNS_LOCK(base); 657 ASSERT_VALID_REQUEST(req); 658 659 if (head) 660 evdns_request_remove(req, head); 661 662 log(EVDNS_LOG_DEBUG, "Removing timeout for request %p", req); 663 if (was_inflight) { 664 evtimer_del(&req->timeout_event); 665 base->global_requests_inflight--; 666 req->ns->requests_inflight--; 667 } else { 668 base->global_requests_waiting--; 669 } 670 /* it was initialized during request_new / evtimer_assign */ 671 event_debug_unassign(&req->timeout_event); 672 673 if (req->ns && 674 req->ns->requests_inflight == 0 && 675 req->base->disable_when_inactive) { 676 event_del(&req->ns->event); 677 evtimer_del(&req->ns->timeout_event); 678 } 679 680 if (!req->request_appended) { 681 /* need to free the request data on it's own */ 682 mm_free(req->request); 683 } else { 684 /* the request data is appended onto the header */ 685 /* so everything gets free()ed when we: */ 686 } 687 688 if (req->handle) { 689 EVUTIL_ASSERT(req->handle->current_req == req); 690 691 if (free_handle) { 692 search_request_finished(req->handle); 693 req->handle->current_req = NULL; 694 if (! req->handle->pending_cb) { 695 /* If we're planning to run the callback, 696 * don't free the handle until later. */ 697 mm_free(req->handle); 698 } 699 req->handle = NULL; /* If we have a bug, let's crash 700 * early */ 701 } else { 702 req->handle->current_req = NULL; 703 } 704 } 705 706 mm_free(req); 707 708 evdns_requests_pump_waiting_queue(base); 709 EVDNS_UNLOCK(base); 710 } 711 712 /* This is called when a server returns a funny error code. */ 713 /* We try the request again with another server. */ 714 /* */ 715 /* return: */ 716 /* 0 ok */ 717 /* 1 failed/reissue is pointless */ 718 static int 719 request_reissue(struct request *req) { 720 const struct nameserver *const last_ns = req->ns; 721 ASSERT_LOCKED(req->base); 722 ASSERT_VALID_REQUEST(req); 723 /* the last nameserver should have been marked as failing */ 724 /* by the caller of this function, therefore pick will try */ 725 /* not to return it */ 726 request_swap_ns(req, nameserver_pick(req->base)); 727 if (req->ns == last_ns) { 728 /* ... but pick did return it */ 729 /* not a lot of point in trying again with the */ 730 /* same server */ 731 return 1; 732 } 733 734 req->reissue_count++; 735 req->tx_count = 0; 736 req->transmit_me = 1; 737 738 return 0; 739 } 740 741 /* this function looks for space on the inflight queue and promotes */ 742 /* requests from the waiting queue if it can. */ 743 /* */ 744 /* TODO: */ 745 /* add return code, see at nameserver_pick() and other functions. */ 746 static void 747 evdns_requests_pump_waiting_queue(struct evdns_base *base) { 748 ASSERT_LOCKED(base); 749 while (base->global_requests_inflight < base->global_max_requests_inflight && 750 base->global_requests_waiting) { 751 struct request *req; 752 753 EVUTIL_ASSERT(base->req_waiting_head); 754 req = base->req_waiting_head; 755 756 req->ns = nameserver_pick(base); 757 if (!req->ns) 758 return; 759 760 /* move a request from the waiting queue to the inflight queue */ 761 req->ns->requests_inflight++; 762 763 evdns_request_remove(req, &base->req_waiting_head); 764 765 base->global_requests_waiting--; 766 base->global_requests_inflight++; 767 768 request_trans_id_set(req, transaction_id_pick(base)); 769 770 evdns_request_insert(req, &REQ_HEAD(base, req->trans_id)); 771 evdns_request_transmit(req); 772 evdns_transmit(base); 773 } 774 } 775 776 /* TODO(nickm) document */ 777 struct deferred_reply_callback { 778 struct event_callback deferred; 779 struct evdns_request *handle; 780 u8 request_type; 781 u8 have_reply; 782 u32 ttl; 783 u32 err; 784 evdns_callback_type user_callback; 785 struct reply reply; 786 }; 787 788 static void 789 reply_run_callback(struct event_callback *d, void *user_pointer) 790 { 791 struct deferred_reply_callback *cb = 792 EVUTIL_UPCAST(d, struct deferred_reply_callback, deferred); 793 794 switch (cb->request_type) { 795 case TYPE_A: 796 if (cb->have_reply) 797 cb->user_callback(DNS_ERR_NONE, DNS_IPv4_A, 798 cb->reply.data.a.addrcount, cb->ttl, 799 cb->reply.data.a.addresses, 800 user_pointer); 801 else 802 cb->user_callback(cb->err, 0, 0, cb->ttl, NULL, user_pointer); 803 break; 804 case TYPE_PTR: 805 if (cb->have_reply) { 806 char *name = cb->reply.data.ptr.name; 807 cb->user_callback(DNS_ERR_NONE, DNS_PTR, 1, cb->ttl, 808 &name, user_pointer); 809 } else { 810 cb->user_callback(cb->err, 0, 0, cb->ttl, NULL, user_pointer); 811 } 812 break; 813 case TYPE_AAAA: 814 if (cb->have_reply) 815 cb->user_callback(DNS_ERR_NONE, DNS_IPv6_AAAA, 816 cb->reply.data.aaaa.addrcount, cb->ttl, 817 cb->reply.data.aaaa.addresses, 818 user_pointer); 819 else 820 cb->user_callback(cb->err, 0, 0, cb->ttl, NULL, user_pointer); 821 break; 822 default: 823 EVUTIL_ASSERT(0); 824 } 825 826 if (cb->handle && cb->handle->pending_cb) { 827 mm_free(cb->handle); 828 } 829 830 mm_free(cb); 831 } 832 833 static void 834 reply_schedule_callback(struct request *const req, u32 ttl, u32 err, struct reply *reply) 835 { 836 struct deferred_reply_callback *d = mm_calloc(1, sizeof(*d)); 837 838 if (!d) { 839 event_warn("%s: Couldn't allocate space for deferred callback.", 840 __func__); 841 return; 842 } 843 844 ASSERT_LOCKED(req->base); 845 846 d->request_type = req->request_type; 847 d->user_callback = req->user_callback; 848 d->ttl = ttl; 849 d->err = err; 850 if (reply) { 851 d->have_reply = 1; 852 memcpy(&d->reply, reply, sizeof(struct reply)); 853 } 854 855 if (req->handle) { 856 req->handle->pending_cb = 1; 857 d->handle = req->handle; 858 } 859 860 event_deferred_cb_init_( 861 &d->deferred, 862 event_get_priority(&req->timeout_event), 863 reply_run_callback, 864 req->user_pointer); 865 event_deferred_cb_schedule_( 866 req->base->event_base, 867 &d->deferred); 868 } 869 870 871 #define _QR_MASK 0x8000U 872 #define _OP_MASK 0x7800U 873 #define _AA_MASK 0x0400U 874 #define _TC_MASK 0x0200U 875 #define _RD_MASK 0x0100U 876 #define _RA_MASK 0x0080U 877 #define _Z_MASK 0x0040U 878 #define _AD_MASK 0x0020U 879 #define _CD_MASK 0x0010U 880 #define _RCODE_MASK 0x000fU 881 #define _Z_MASK_DEPRECATED 0x0070U 882 883 /* this processes a parsed reply packet */ 884 static void 885 reply_handle(struct request *const req, u16 flags, u32 ttl, struct reply *reply) { 886 int error; 887 char addrbuf[128]; 888 static const int error_codes[] = { 889 DNS_ERR_FORMAT, DNS_ERR_SERVERFAILED, DNS_ERR_NOTEXIST, 890 DNS_ERR_NOTIMPL, DNS_ERR_REFUSED 891 }; 892 893 ASSERT_LOCKED(req->base); 894 ASSERT_VALID_REQUEST(req); 895 896 if (flags & (_RCODE_MASK | _TC_MASK) || !reply || !reply->have_answer) { 897 /* there was an error */ 898 if (flags & _TC_MASK) { 899 error = DNS_ERR_TRUNCATED; 900 } else if (flags & _RCODE_MASK) { 901 u16 error_code = (flags & _RCODE_MASK) - 1; 902 if (error_code > 4) { 903 error = DNS_ERR_UNKNOWN; 904 } else { 905 error = error_codes[error_code]; 906 } 907 } else if (reply && !reply->have_answer) { 908 error = DNS_ERR_NODATA; 909 } else { 910 error = DNS_ERR_UNKNOWN; 911 } 912 913 switch (error) { 914 case DNS_ERR_NOTIMPL: 915 case DNS_ERR_REFUSED: 916 /* we regard these errors as marking a bad nameserver */ 917 if (req->reissue_count < req->base->global_max_reissues) { 918 char msg[64]; 919 evutil_snprintf(msg, sizeof(msg), "Bad response %d (%s)", 920 error, evdns_err_to_string(error)); 921 nameserver_failed(req->ns, msg); 922 if (!request_reissue(req)) return; 923 } 924 break; 925 case DNS_ERR_SERVERFAILED: 926 /* rcode 2 (servfailed) sometimes means "we 927 * are broken" and sometimes (with some binds) 928 * means "that request was very confusing." 929 * Treat this as a timeout, not a failure. 930 */ 931 log(EVDNS_LOG_DEBUG, "Got a SERVERFAILED from nameserver" 932 "at %s; will allow the request to time out.", 933 evutil_format_sockaddr_port_( 934 (struct sockaddr *)&req->ns->address, 935 addrbuf, sizeof(addrbuf))); 936 /* Call the timeout function */ 937 evdns_request_timeout_callback(0, 0, req); 938 return; 939 default: 940 /* we got a good reply from the nameserver: it is up. */ 941 if (req->handle == req->ns->probe_request) { 942 /* Avoid double-free */ 943 req->ns->probe_request = NULL; 944 } 945 946 nameserver_up(req->ns); 947 } 948 949 if (req->handle->search_state && 950 req->request_type != TYPE_PTR) { 951 /* if we have a list of domains to search in, 952 * try the next one */ 953 if (!search_try_next(req->handle)) { 954 /* a new request was issued so this 955 * request is finished and */ 956 /* the user callback will be made when 957 * that request (or a */ 958 /* child of it) finishes. */ 959 return; 960 } 961 } 962 963 /* all else failed. Pass the failure up */ 964 reply_schedule_callback(req, ttl, error, NULL); 965 request_finished(req, &REQ_HEAD(req->base, req->trans_id), 1); 966 } else { 967 /* all ok, tell the user */ 968 reply_schedule_callback(req, ttl, 0, reply); 969 if (req->handle == req->ns->probe_request) 970 req->ns->probe_request = NULL; /* Avoid double-free */ 971 nameserver_up(req->ns); 972 request_finished(req, &REQ_HEAD(req->base, req->trans_id), 1); 973 } 974 } 975 976 static int 977 name_parse(u8 *packet, int length, int *idx, char *name_out, int name_out_len) { 978 int name_end = -1; 979 int j = *idx; 980 int ptr_count = 0; 981 #define GET32(x) do { if (j + 4 > length) goto err; memcpy(&t32_, packet + j, 4); j += 4; x = ntohl(t32_); } while (0) 982 #define GET16(x) do { if (j + 2 > length) goto err; memcpy(&t_, packet + j, 2); j += 2; x = ntohs(t_); } while (0) 983 #define GET8(x) do { if (j >= length) goto err; x = packet[j++]; } while (0) 984 985 char *cp = name_out; 986 const char *const end = name_out + name_out_len; 987 988 /* Normally, names are a series of length prefixed strings terminated */ 989 /* with a length of 0 (the lengths are u8's < 63). */ 990 /* However, the length can start with a pair of 1 bits and that */ 991 /* means that the next 14 bits are a pointer within the current */ 992 /* packet. */ 993 994 for (;;) { 995 u8 label_len; 996 GET8(label_len); 997 if (!label_len) break; 998 if (label_len & 0xc0) { 999 u8 ptr_low; 1000 GET8(ptr_low); 1001 if (name_end < 0) name_end = j; 1002 j = (((int)label_len & 0x3f) << 8) + ptr_low; 1003 /* Make sure that the target offset is in-bounds. */ 1004 if (j < 0 || j >= length) return -1; 1005 /* If we've jumped more times than there are characters in the 1006 * message, we must have a loop. */ 1007 if (++ptr_count > length) return -1; 1008 continue; 1009 } 1010 if (label_len > 63) return -1; 1011 if (cp != name_out) { 1012 if (cp + 1 >= end) return -1; 1013 *cp++ = '.'; 1014 } 1015 if (cp + label_len >= end) return -1; 1016 if (j + label_len > length) return -1; 1017 memcpy(cp, packet + j, label_len); 1018 cp += label_len; 1019 j += label_len; 1020 } 1021 if (cp >= end) return -1; 1022 *cp = '\0'; 1023 if (name_end < 0) 1024 *idx = j; 1025 else 1026 *idx = name_end; 1027 return 0; 1028 err: 1029 return -1; 1030 } 1031 1032 /* parses a raw request from a nameserver */ 1033 static int 1034 reply_parse(struct evdns_base *base, u8 *packet, int length) { 1035 int j = 0, k = 0; /* index into packet */ 1036 u16 t_; /* used by the macros */ 1037 u32 t32_; /* used by the macros */ 1038 char tmp_name[256], cmp_name[256]; /* used by the macros */ 1039 int name_matches = 0; 1040 1041 u16 trans_id, questions, answers, authority, additional, datalength; 1042 u16 flags = 0; 1043 u32 ttl, ttl_r = 0xffffffff; 1044 struct reply reply; 1045 struct request *req = NULL; 1046 unsigned int i; 1047 1048 ASSERT_LOCKED(base); 1049 1050 GET16(trans_id); 1051 GET16(flags); 1052 GET16(questions); 1053 GET16(answers); 1054 GET16(authority); 1055 GET16(additional); 1056 (void) authority; /* suppress "unused variable" warnings. */ 1057 (void) additional; /* suppress "unused variable" warnings. */ 1058 1059 req = request_find_from_trans_id(base, trans_id); 1060 if (!req) return -1; 1061 EVUTIL_ASSERT(req->base == base); 1062 1063 memset(&reply, 0, sizeof(reply)); 1064 1065 /* If it's not an answer, it doesn't correspond to any request. */ 1066 if (!(flags & _QR_MASK)) return -1; /* must be an answer */ 1067 if ((flags & (_RCODE_MASK|_TC_MASK)) && (flags & (_RCODE_MASK|_TC_MASK)) != DNS_ERR_NOTEXIST) { 1068 /* there was an error and it's not NXDOMAIN */ 1069 goto err; 1070 } 1071 /* if (!answers) return; */ /* must have an answer of some form */ 1072 1073 /* This macro skips a name in the DNS reply. */ 1074 #define SKIP_NAME \ 1075 do { tmp_name[0] = '\0'; \ 1076 if (name_parse(packet, length, &j, tmp_name, \ 1077 sizeof(tmp_name))<0) \ 1078 goto err; \ 1079 } while (0) 1080 1081 reply.type = req->request_type; 1082 1083 /* skip over each question in the reply */ 1084 for (i = 0; i < questions; ++i) { 1085 /* the question looks like 1086 * <label:name><u16:type><u16:class> 1087 */ 1088 tmp_name[0] = '\0'; 1089 cmp_name[0] = '\0'; 1090 k = j; 1091 if (name_parse(packet, length, &j, tmp_name, sizeof(tmp_name)) < 0) 1092 goto err; 1093 if (name_parse(req->request, req->request_len, &k, 1094 cmp_name, sizeof(cmp_name))<0) 1095 goto err; 1096 if (!base->global_randomize_case) { 1097 if (strcmp(tmp_name, cmp_name) == 0) 1098 name_matches = 1; 1099 } else { 1100 if (evutil_ascii_strcasecmp(tmp_name, cmp_name) == 0) 1101 name_matches = 1; 1102 } 1103 1104 j += 4; 1105 if (j > length) 1106 goto err; 1107 } 1108 1109 if (!name_matches) 1110 goto err; 1111 1112 /* now we have the answer section which looks like 1113 * <label:name><u16:type><u16:class><u32:ttl><u16:len><data...> 1114 */ 1115 1116 for (i = 0; i < answers; ++i) { 1117 u16 type, class; 1118 1119 SKIP_NAME; 1120 GET16(type); 1121 GET16(class); 1122 GET32(ttl); 1123 GET16(datalength); 1124 1125 if (type == TYPE_A && class == CLASS_INET) { 1126 int addrcount, addrtocopy; 1127 if (req->request_type != TYPE_A) { 1128 j += datalength; continue; 1129 } 1130 if ((datalength & 3) != 0) /* not an even number of As. */ 1131 goto err; 1132 addrcount = datalength >> 2; 1133 addrtocopy = MIN(MAX_V4_ADDRS - reply.data.a.addrcount, (unsigned)addrcount); 1134 1135 ttl_r = MIN(ttl_r, ttl); 1136 /* we only bother with the first four addresses. */ 1137 if (j + 4*addrtocopy > length) goto err; 1138 memcpy(&reply.data.a.addresses[reply.data.a.addrcount], 1139 packet + j, 4*addrtocopy); 1140 j += 4*addrtocopy; 1141 reply.data.a.addrcount += addrtocopy; 1142 reply.have_answer = 1; 1143 if (reply.data.a.addrcount == MAX_V4_ADDRS) break; 1144 } else if (type == TYPE_PTR && class == CLASS_INET) { 1145 if (req->request_type != TYPE_PTR) { 1146 j += datalength; continue; 1147 } 1148 if (name_parse(packet, length, &j, reply.data.ptr.name, 1149 sizeof(reply.data.ptr.name))<0) 1150 goto err; 1151 ttl_r = MIN(ttl_r, ttl); 1152 reply.have_answer = 1; 1153 break; 1154 } else if (type == TYPE_CNAME) { 1155 char cname[HOST_NAME_MAX]; 1156 if (!req->put_cname_in_ptr || *req->put_cname_in_ptr) { 1157 j += datalength; continue; 1158 } 1159 if (name_parse(packet, length, &j, cname, 1160 sizeof(cname))<0) 1161 goto err; 1162 *req->put_cname_in_ptr = mm_strdup(cname); 1163 } else if (type == TYPE_AAAA && class == CLASS_INET) { 1164 int addrcount, addrtocopy; 1165 if (req->request_type != TYPE_AAAA) { 1166 j += datalength; continue; 1167 } 1168 if ((datalength & 15) != 0) /* not an even number of AAAAs. */ 1169 goto err; 1170 addrcount = datalength >> 4; /* each address is 16 bytes long */ 1171 addrtocopy = MIN(MAX_V6_ADDRS - reply.data.aaaa.addrcount, (unsigned)addrcount); 1172 ttl_r = MIN(ttl_r, ttl); 1173 1174 /* we only bother with the first four addresses. */ 1175 if (j + 16*addrtocopy > length) goto err; 1176 memcpy(&reply.data.aaaa.addresses[reply.data.aaaa.addrcount], 1177 packet + j, 16*addrtocopy); 1178 reply.data.aaaa.addrcount += addrtocopy; 1179 j += 16*addrtocopy; 1180 reply.have_answer = 1; 1181 if (reply.data.aaaa.addrcount == MAX_V6_ADDRS) break; 1182 } else { 1183 /* skip over any other type of resource */ 1184 j += datalength; 1185 } 1186 } 1187 1188 if (!reply.have_answer) { 1189 for (i = 0; i < authority; ++i) { 1190 u16 type, class; 1191 SKIP_NAME; 1192 GET16(type); 1193 GET16(class); 1194 GET32(ttl); 1195 GET16(datalength); 1196 if (type == TYPE_SOA && class == CLASS_INET) { 1197 u32 serial, refresh, retry, expire, minimum; 1198 SKIP_NAME; 1199 SKIP_NAME; 1200 GET32(serial); 1201 GET32(refresh); 1202 GET32(retry); 1203 GET32(expire); 1204 GET32(minimum); 1205 (void)expire; 1206 (void)retry; 1207 (void)refresh; 1208 (void)serial; 1209 ttl_r = MIN(ttl_r, ttl); 1210 ttl_r = MIN(ttl_r, minimum); 1211 } else { 1212 /* skip over any other type of resource */ 1213 j += datalength; 1214 } 1215 } 1216 } 1217 1218 if (ttl_r == 0xffffffff) 1219 ttl_r = 0; 1220 1221 reply_handle(req, flags, ttl_r, &reply); 1222 return 0; 1223 err: 1224 if (req) 1225 reply_handle(req, flags, 0, NULL); 1226 return -1; 1227 } 1228 1229 /* Parse a raw request (packet,length) sent to a nameserver port (port) from */ 1230 /* a DNS client (addr,addrlen), and if it's well-formed, call the corresponding */ 1231 /* callback. */ 1232 static int 1233 request_parse(u8 *packet, int length, struct evdns_server_port *port, struct sockaddr *addr, ev_socklen_t addrlen) 1234 { 1235 int j = 0; /* index into packet */ 1236 u16 t_; /* used by the macros */ 1237 char tmp_name[256]; /* used by the macros */ 1238 1239 int i; 1240 u16 trans_id, flags, questions, answers, authority, additional; 1241 struct server_request *server_req = NULL; 1242 1243 ASSERT_LOCKED(port); 1244 1245 /* Get the header fields */ 1246 GET16(trans_id); 1247 GET16(flags); 1248 GET16(questions); 1249 GET16(answers); 1250 GET16(authority); 1251 GET16(additional); 1252 (void)answers; 1253 (void)additional; 1254 (void)authority; 1255 1256 if (flags & _QR_MASK) return -1; /* Must not be an answer. */ 1257 flags &= (_RD_MASK|_CD_MASK); /* Only RD and CD get preserved. */ 1258 1259 server_req = mm_malloc(sizeof(struct server_request)); 1260 if (server_req == NULL) return -1; 1261 memset(server_req, 0, sizeof(struct server_request)); 1262 1263 server_req->trans_id = trans_id; 1264 memcpy(&server_req->addr, addr, addrlen); 1265 server_req->addrlen = addrlen; 1266 1267 server_req->base.flags = flags; 1268 server_req->base.nquestions = 0; 1269 server_req->base.questions = mm_calloc(sizeof(struct evdns_server_question *), questions); 1270 if (server_req->base.questions == NULL) 1271 goto err; 1272 1273 for (i = 0; i < questions; ++i) { 1274 u16 type, class; 1275 struct evdns_server_question *q; 1276 int namelen; 1277 if (name_parse(packet, length, &j, tmp_name, sizeof(tmp_name))<0) 1278 goto err; 1279 GET16(type); 1280 GET16(class); 1281 namelen = (int)strlen(tmp_name); 1282 q = mm_malloc(sizeof(struct evdns_server_question) + namelen); 1283 if (!q) 1284 goto err; 1285 q->type = type; 1286 q->dns_question_class = class; 1287 memcpy(q->name, tmp_name, namelen+1); 1288 server_req->base.questions[server_req->base.nquestions++] = q; 1289 } 1290 1291 /* Ignore answers, authority, and additional. */ 1292 1293 server_req->port = port; 1294 port->refcnt++; 1295 1296 /* Only standard queries are supported. */ 1297 if (flags & _OP_MASK) { 1298 evdns_server_request_respond(&(server_req->base), DNS_ERR_NOTIMPL); 1299 return -1; 1300 } 1301 1302 port->user_callback(&(server_req->base), port->user_data); 1303 1304 return 0; 1305 err: 1306 if (server_req->base.questions) { 1307 for (i = 0; i < server_req->base.nquestions; ++i) 1308 mm_free(server_req->base.questions[i]); 1309 mm_free(server_req->base.questions); 1310 } 1311 mm_free(server_req); 1312 return -1; 1313 1314 #undef SKIP_NAME 1315 #undef GET32 1316 #undef GET16 1317 #undef GET8 1318 } 1319 1320 1321 void 1322 evdns_set_transaction_id_fn(ev_uint16_t (*fn)(void)) 1323 { 1324 } 1325 1326 void 1327 evdns_set_random_bytes_fn(void (*fn)(char *, size_t)) 1328 { 1329 } 1330 1331 /* Try to choose a strong transaction id which isn't already in flight */ 1332 static u16 1333 transaction_id_pick(struct evdns_base *base) { 1334 ASSERT_LOCKED(base); 1335 for (;;) { 1336 u16 trans_id; 1337 evutil_secure_rng_get_bytes(&trans_id, sizeof(trans_id)); 1338 1339 if (trans_id == 0xffff) continue; 1340 /* now check to see if that id is already inflight */ 1341 if (request_find_from_trans_id(base, trans_id) == NULL) 1342 return trans_id; 1343 } 1344 } 1345 1346 /* choose a namesever to use. This function will try to ignore */ 1347 /* nameservers which we think are down and load balance across the rest */ 1348 /* by updating the server_head global each time. */ 1349 static struct nameserver * 1350 nameserver_pick(struct evdns_base *base) { 1351 struct nameserver *started_at = base->server_head, *picked; 1352 ASSERT_LOCKED(base); 1353 if (!base->server_head) return NULL; 1354 1355 /* if we don't have any good nameservers then there's no */ 1356 /* point in trying to find one. */ 1357 if (!base->global_good_nameservers) { 1358 base->server_head = base->server_head->next; 1359 return base->server_head; 1360 } 1361 1362 /* remember that nameservers are in a circular list */ 1363 for (;;) { 1364 if (base->server_head->state) { 1365 /* we think this server is currently good */ 1366 picked = base->server_head; 1367 base->server_head = base->server_head->next; 1368 return picked; 1369 } 1370 1371 base->server_head = base->server_head->next; 1372 if (base->server_head == started_at) { 1373 /* all the nameservers seem to be down */ 1374 /* so we just return this one and hope for the */ 1375 /* best */ 1376 EVUTIL_ASSERT(base->global_good_nameservers == 0); 1377 picked = base->server_head; 1378 base->server_head = base->server_head->next; 1379 return picked; 1380 } 1381 } 1382 } 1383 1384 /* this is called when a namesever socket is ready for reading */ 1385 static void 1386 nameserver_read(struct nameserver *ns) { 1387 struct sockaddr_storage ss; 1388 ev_socklen_t addrlen = sizeof(ss); 1389 u8 packet[1500]; 1390 char addrbuf[128]; 1391 ASSERT_LOCKED(ns->base); 1392 1393 for (;;) { 1394 const int r = recvfrom(ns->socket, (void*)packet, 1395 sizeof(packet), 0, 1396 (struct sockaddr*)&ss, &addrlen); 1397 if (r < 0) { 1398 int err = evutil_socket_geterror(ns->socket); 1399 if (EVUTIL_ERR_RW_RETRIABLE(err)) 1400 return; 1401 nameserver_failed(ns, 1402 evutil_socket_error_to_string(err)); 1403 return; 1404 } 1405 if (evutil_sockaddr_cmp((struct sockaddr*)&ss, 1406 (struct sockaddr*)&ns->address, 0)) { 1407 log(EVDNS_LOG_WARN, "Address mismatch on received " 1408 "DNS packet. Apparent source was %s", 1409 evutil_format_sockaddr_port_( 1410 (struct sockaddr *)&ss, 1411 addrbuf, sizeof(addrbuf))); 1412 return; 1413 } 1414 1415 ns->timedout = 0; 1416 reply_parse(ns->base, packet, r); 1417 } 1418 } 1419 1420 /* Read a packet from a DNS client on a server port s, parse it, and */ 1421 /* act accordingly. */ 1422 static void 1423 server_port_read(struct evdns_server_port *s) { 1424 u8 packet[1500]; 1425 struct sockaddr_storage addr; 1426 ev_socklen_t addrlen; 1427 int r; 1428 ASSERT_LOCKED(s); 1429 1430 for (;;) { 1431 addrlen = sizeof(struct sockaddr_storage); 1432 r = recvfrom(s->socket, (void*)packet, sizeof(packet), 0, 1433 (struct sockaddr*) &addr, &addrlen); 1434 if (r < 0) { 1435 int err = evutil_socket_geterror(s->socket); 1436 if (EVUTIL_ERR_RW_RETRIABLE(err)) 1437 return; 1438 log(EVDNS_LOG_WARN, 1439 "Error %s (%d) while reading request.", 1440 evutil_socket_error_to_string(err), err); 1441 return; 1442 } 1443 request_parse(packet, r, s, (struct sockaddr*) &addr, addrlen); 1444 } 1445 } 1446 1447 /* Try to write all pending replies on a given DNS server port. */ 1448 static void 1449 server_port_flush(struct evdns_server_port *port) 1450 { 1451 struct server_request *req = port->pending_replies; 1452 ASSERT_LOCKED(port); 1453 while (req) { 1454 int r = sendto(port->socket, req->response, (int)req->response_len, 0, 1455 (struct sockaddr*) &req->addr, (ev_socklen_t)req->addrlen); 1456 if (r < 0) { 1457 int err = evutil_socket_geterror(port->socket); 1458 if (EVUTIL_ERR_RW_RETRIABLE(err)) 1459 return; 1460 log(EVDNS_LOG_WARN, "Error %s (%d) while writing response to port; dropping", evutil_socket_error_to_string(err), err); 1461 } 1462 if (server_request_free(req)) { 1463 /* we released the last reference to req->port. */ 1464 return; 1465 } else { 1466 EVUTIL_ASSERT(req != port->pending_replies); 1467 req = port->pending_replies; 1468 } 1469 } 1470 1471 /* We have no more pending requests; stop listening for 'writeable' events. */ 1472 (void) event_del(&port->event); 1473 event_assign(&port->event, port->event_base, 1474 port->socket, EV_READ | EV_PERSIST, 1475 server_port_ready_callback, port); 1476 1477 if (event_add(&port->event, NULL) < 0) { 1478 log(EVDNS_LOG_WARN, "Error from libevent when adding event for DNS server."); 1479 /* ???? Do more? */ 1480 } 1481 } 1482 1483 /* set if we are waiting for the ability to write to this server. */ 1484 /* if waiting is true then we ask libevent for EV_WRITE events, otherwise */ 1485 /* we stop these events. */ 1486 static void 1487 nameserver_write_waiting(struct nameserver *ns, char waiting) { 1488 ASSERT_LOCKED(ns->base); 1489 if (ns->write_waiting == waiting) return; 1490 1491 ns->write_waiting = waiting; 1492 (void) event_del(&ns->event); 1493 event_assign(&ns->event, ns->base->event_base, 1494 ns->socket, EV_READ | (waiting ? EV_WRITE : 0) | EV_PERSIST, 1495 nameserver_ready_callback, ns); 1496 if (event_add(&ns->event, NULL) < 0) { 1497 char addrbuf[128]; 1498 log(EVDNS_LOG_WARN, "Error from libevent when adding event for %s", 1499 evutil_format_sockaddr_port_( 1500 (struct sockaddr *)&ns->address, 1501 addrbuf, sizeof(addrbuf))); 1502 /* ???? Do more? */ 1503 } 1504 } 1505 1506 /* a callback function. Called by libevent when the kernel says that */ 1507 /* a nameserver socket is ready for writing or reading */ 1508 static void 1509 nameserver_ready_callback(evutil_socket_t fd, short events, void *arg) { 1510 struct nameserver *ns = (struct nameserver *) arg; 1511 (void)fd; 1512 1513 EVDNS_LOCK(ns->base); 1514 if (events & EV_WRITE) { 1515 ns->choked = 0; 1516 if (!evdns_transmit(ns->base)) { 1517 nameserver_write_waiting(ns, 0); 1518 } 1519 } 1520 if (events & EV_READ) { 1521 nameserver_read(ns); 1522 } 1523 EVDNS_UNLOCK(ns->base); 1524 } 1525 1526 /* a callback function. Called by libevent when the kernel says that */ 1527 /* a server socket is ready for writing or reading. */ 1528 static void 1529 server_port_ready_callback(evutil_socket_t fd, short events, void *arg) { 1530 struct evdns_server_port *port = (struct evdns_server_port *) arg; 1531 (void) fd; 1532 1533 EVDNS_LOCK(port); 1534 if (events & EV_WRITE) { 1535 port->choked = 0; 1536 server_port_flush(port); 1537 } 1538 if (events & EV_READ) { 1539 server_port_read(port); 1540 } 1541 EVDNS_UNLOCK(port); 1542 } 1543 1544 /* This is an inefficient representation; only use it via the dnslabel_table_* 1545 * functions, so that is can be safely replaced with something smarter later. */ 1546 #define MAX_LABELS 128 1547 /* Structures used to implement name compression */ 1548 struct dnslabel_entry { char *v; off_t pos; }; 1549 struct dnslabel_table { 1550 int n_labels; /* number of current entries */ 1551 /* map from name to position in message */ 1552 struct dnslabel_entry labels[MAX_LABELS]; 1553 }; 1554 1555 /* Initialize dnslabel_table. */ 1556 static void 1557 dnslabel_table_init(struct dnslabel_table *table) 1558 { 1559 table->n_labels = 0; 1560 } 1561 1562 /* Free all storage held by table, but not the table itself. */ 1563 static void 1564 dnslabel_clear(struct dnslabel_table *table) 1565 { 1566 int i; 1567 for (i = 0; i < table->n_labels; ++i) 1568 mm_free(table->labels[i].v); 1569 table->n_labels = 0; 1570 } 1571 1572 /* return the position of the label in the current message, or -1 if the label */ 1573 /* hasn't been used yet. */ 1574 static int 1575 dnslabel_table_get_pos(const struct dnslabel_table *table, const char *label) 1576 { 1577 int i; 1578 for (i = 0; i < table->n_labels; ++i) { 1579 if (!strcmp(label, table->labels[i].v)) 1580 return table->labels[i].pos; 1581 } 1582 return -1; 1583 } 1584 1585 /* remember that we've used the label at position pos */ 1586 static int 1587 dnslabel_table_add(struct dnslabel_table *table, const char *label, off_t pos) 1588 { 1589 char *v; 1590 int p; 1591 if (table->n_labels == MAX_LABELS) 1592 return (-1); 1593 v = mm_strdup(label); 1594 if (v == NULL) 1595 return (-1); 1596 p = table->n_labels++; 1597 table->labels[p].v = v; 1598 table->labels[p].pos = pos; 1599 1600 return (0); 1601 } 1602 1603 /* Converts a string to a length-prefixed set of DNS labels, starting */ 1604 /* at buf[j]. name and buf must not overlap. name_len should be the length */ 1605 /* of name. table is optional, and is used for compression. */ 1606 /* */ 1607 /* Input: abc.def */ 1608 /* Output: <3>abc<3>def<0> */ 1609 /* */ 1610 /* Returns the first index after the encoded name, or negative on error. */ 1611 /* -1 label was > 63 bytes */ 1612 /* -2 name too long to fit in buffer. */ 1613 /* */ 1614 static off_t 1615 dnsname_to_labels(u8 *const buf, size_t buf_len, off_t j, 1616 const char *name, const size_t name_len, 1617 struct dnslabel_table *table) { 1618 const char *end = name + name_len; 1619 int ref = 0; 1620 u16 t_; 1621 1622 #define APPEND16(x) do { \ 1623 if (j + 2 > (off_t)buf_len) \ 1624 goto overflow; \ 1625 t_ = htons(x); \ 1626 memcpy(buf + j, &t_, 2); \ 1627 j += 2; \ 1628 } while (0) 1629 #define APPEND32(x) do { \ 1630 if (j + 4 > (off_t)buf_len) \ 1631 goto overflow; \ 1632 t32_ = htonl(x); \ 1633 memcpy(buf + j, &t32_, 4); \ 1634 j += 4; \ 1635 } while (0) 1636 1637 if (name_len > 255) return -2; 1638 1639 for (;;) { 1640 const char *const start = name; 1641 if (table && (ref = dnslabel_table_get_pos(table, name)) >= 0) { 1642 APPEND16(ref | 0xc000); 1643 return j; 1644 } 1645 name = strchr(name, '.'); 1646 if (!name) { 1647 const size_t label_len = end - 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 break; 1656 } else { 1657 /* append length of the label. */ 1658 const size_t label_len = name - start; 1659 if (label_len > 63) return -1; 1660 if ((size_t)(j+label_len+1) > buf_len) return -2; 1661 if (table) dnslabel_table_add(table, start, j); 1662 buf[j++] = (ev_uint8_t)label_len; 1663 1664 memcpy(buf + j, start, label_len); 1665 j += (int) label_len; 1666 /* hop over the '.' */ 1667 name++; 1668 } 1669 } 1670 1671 /* the labels must be terminated by a 0. */ 1672 /* It's possible that the name ended in a . */ 1673 /* in which case the zero is already there */ 1674 if (!j || buf[j-1]) buf[j++] = 0; 1675 return j; 1676 overflow: 1677 return (-2); 1678 } 1679 1680 /* Finds the length of a dns request for a DNS name of the given */ 1681 /* length. The actual request may be smaller than the value returned */ 1682 /* here */ 1683 static size_t 1684 evdns_request_len(const size_t name_len) { 1685 return 96 + /* length of the DNS standard header */ 1686 name_len + 2 + 1687 4; /* space for the resource type */ 1688 } 1689 1690 /* build a dns request packet into buf. buf should be at least as long */ 1691 /* as evdns_request_len told you it should be. */ 1692 /* */ 1693 /* Returns the amount of space used. Negative on error. */ 1694 static int 1695 evdns_request_data_build(const char *const name, const size_t name_len, 1696 const u16 trans_id, const u16 type, const u16 class, 1697 u8 *const buf, size_t buf_len) { 1698 off_t j = 0; /* current offset into buf */ 1699 u16 t_; /* used by the macros */ 1700 1701 APPEND16(trans_id); 1702 APPEND16(0x0100); /* standard query, recusion needed */ 1703 APPEND16(1); /* one question */ 1704 APPEND16(0); /* no answers */ 1705 APPEND16(0); /* no authority */ 1706 APPEND16(0); /* no additional */ 1707 1708 j = dnsname_to_labels(buf, buf_len, j, name, name_len, NULL); 1709 if (j < 0) { 1710 return (int)j; 1711 } 1712 1713 APPEND16(type); 1714 APPEND16(class); 1715 1716 return (int)j; 1717 overflow: 1718 return (-1); 1719 } 1720 1721 /* exported function */ 1722 struct evdns_server_port * 1723 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) 1724 { 1725 struct evdns_server_port *port; 1726 if (flags) 1727 return NULL; /* flags not yet implemented */ 1728 if (!(port = mm_malloc(sizeof(struct evdns_server_port)))) 1729 return NULL; 1730 memset(port, 0, sizeof(struct evdns_server_port)); 1731 1732 1733 port->socket = socket; 1734 port->refcnt = 1; 1735 port->choked = 0; 1736 port->closing = 0; 1737 port->user_callback = cb; 1738 port->user_data = user_data; 1739 port->pending_replies = NULL; 1740 port->event_base = base; 1741 1742 event_assign(&port->event, port->event_base, 1743 port->socket, EV_READ | EV_PERSIST, 1744 server_port_ready_callback, port); 1745 if (event_add(&port->event, NULL) < 0) { 1746 mm_free(port); 1747 return NULL; 1748 } 1749 EVTHREAD_ALLOC_LOCK(port->lock, EVTHREAD_LOCKTYPE_RECURSIVE); 1750 return port; 1751 } 1752 1753 struct evdns_server_port * 1754 evdns_add_server_port(evutil_socket_t socket, int flags, evdns_request_callback_fn_type cb, void *user_data) 1755 { 1756 return evdns_add_server_port_with_base(NULL, socket, flags, cb, user_data); 1757 } 1758 1759 /* exported function */ 1760 void 1761 evdns_close_server_port(struct evdns_server_port *port) 1762 { 1763 EVDNS_LOCK(port); 1764 if (--port->refcnt == 0) { 1765 EVDNS_UNLOCK(port); 1766 server_port_free(port); 1767 } else { 1768 port->closing = 1; 1769 EVDNS_UNLOCK(port); 1770 } 1771 } 1772 1773 /* exported function */ 1774 int 1775 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) 1776 { 1777 struct server_request *req = TO_SERVER_REQUEST(req_); 1778 struct server_reply_item **itemp, *item; 1779 int *countp; 1780 int result = -1; 1781 1782 EVDNS_LOCK(req->port); 1783 if (req->response) /* have we already answered? */ 1784 goto done; 1785 1786 switch (section) { 1787 case EVDNS_ANSWER_SECTION: 1788 itemp = &req->answer; 1789 countp = &req->n_answer; 1790 break; 1791 case EVDNS_AUTHORITY_SECTION: 1792 itemp = &req->authority; 1793 countp = &req->n_authority; 1794 break; 1795 case EVDNS_ADDITIONAL_SECTION: 1796 itemp = &req->additional; 1797 countp = &req->n_additional; 1798 break; 1799 default: 1800 goto done; 1801 } 1802 while (*itemp) { 1803 itemp = &((*itemp)->next); 1804 } 1805 item = mm_malloc(sizeof(struct server_reply_item)); 1806 if (!item) 1807 goto done; 1808 item->next = NULL; 1809 if (!(item->name = mm_strdup(name))) { 1810 mm_free(item); 1811 goto done; 1812 } 1813 item->type = type; 1814 item->dns_question_class = class; 1815 item->ttl = ttl; 1816 item->is_name = is_name != 0; 1817 item->datalen = 0; 1818 item->data = NULL; 1819 if (data) { 1820 if (item->is_name) { 1821 if (!(item->data = mm_strdup(data))) { 1822 mm_free(item->name); 1823 mm_free(item); 1824 goto done; 1825 } 1826 item->datalen = (u16)-1; 1827 } else { 1828 if (!(item->data = mm_malloc(datalen))) { 1829 mm_free(item->name); 1830 mm_free(item); 1831 goto done; 1832 } 1833 item->datalen = datalen; 1834 memcpy(item->data, data, datalen); 1835 } 1836 } 1837 1838 *itemp = item; 1839 ++(*countp); 1840 result = 0; 1841 done: 1842 EVDNS_UNLOCK(req->port); 1843 return result; 1844 } 1845 1846 /* exported function */ 1847 int 1848 evdns_server_request_add_a_reply(struct evdns_server_request *req, const char *name, int n, const void *addrs, int ttl) 1849 { 1850 return evdns_server_request_add_reply( 1851 req, EVDNS_ANSWER_SECTION, name, TYPE_A, CLASS_INET, 1852 ttl, n*4, 0, addrs); 1853 } 1854 1855 /* exported function */ 1856 int 1857 evdns_server_request_add_aaaa_reply(struct evdns_server_request *req, const char *name, int n, const void *addrs, int ttl) 1858 { 1859 return evdns_server_request_add_reply( 1860 req, EVDNS_ANSWER_SECTION, name, TYPE_AAAA, CLASS_INET, 1861 ttl, n*16, 0, addrs); 1862 } 1863 1864 /* exported function */ 1865 int 1866 evdns_server_request_add_ptr_reply(struct evdns_server_request *req, struct in_addr *in, const char *inaddr_name, const char *hostname, int ttl) 1867 { 1868 u32 a; 1869 char buf[32]; 1870 if (in && inaddr_name) 1871 return -1; 1872 else if (!in && !inaddr_name) 1873 return -1; 1874 if (in) { 1875 a = ntohl(in->s_addr); 1876 evutil_snprintf(buf, sizeof(buf), "%d.%d.%d.%d.in-addr.arpa", 1877 (int)(u8)((a )&0xff), 1878 (int)(u8)((a>>8 )&0xff), 1879 (int)(u8)((a>>16)&0xff), 1880 (int)(u8)((a>>24)&0xff)); 1881 inaddr_name = buf; 1882 } 1883 return evdns_server_request_add_reply( 1884 req, EVDNS_ANSWER_SECTION, inaddr_name, TYPE_PTR, CLASS_INET, 1885 ttl, -1, 1, hostname); 1886 } 1887 1888 /* exported function */ 1889 int 1890 evdns_server_request_add_cname_reply(struct evdns_server_request *req, const char *name, const char *cname, int ttl) 1891 { 1892 return evdns_server_request_add_reply( 1893 req, EVDNS_ANSWER_SECTION, name, TYPE_CNAME, CLASS_INET, 1894 ttl, -1, 1, cname); 1895 } 1896 1897 /* exported function */ 1898 void 1899 evdns_server_request_set_flags(struct evdns_server_request *exreq, int flags) 1900 { 1901 struct server_request *req = TO_SERVER_REQUEST(exreq); 1902 req->base.flags &= ~(EVDNS_FLAGS_AA|EVDNS_FLAGS_RD); 1903 req->base.flags |= flags; 1904 } 1905 1906 static int 1907 evdns_server_request_format_response(struct server_request *req, int err) 1908 { 1909 unsigned char buf[1500]; 1910 size_t buf_len = sizeof(buf); 1911 off_t j = 0, r; 1912 u16 t_; 1913 u32 t32_; 1914 int i; 1915 u16 flags; 1916 struct dnslabel_table table; 1917 1918 if (err < 0 || err > 15) return -1; 1919 1920 /* Set response bit and error code; copy OPCODE and RD fields from 1921 * question; copy RA and AA if set by caller. */ 1922 flags = req->base.flags; 1923 flags |= (_QR_MASK | err); 1924 1925 dnslabel_table_init(&table); 1926 APPEND16(req->trans_id); 1927 APPEND16(flags); 1928 APPEND16(req->base.nquestions); 1929 APPEND16(req->n_answer); 1930 APPEND16(req->n_authority); 1931 APPEND16(req->n_additional); 1932 1933 /* Add questions. */ 1934 for (i=0; i < req->base.nquestions; ++i) { 1935 const char *s = req->base.questions[i]->name; 1936 j = dnsname_to_labels(buf, buf_len, j, s, strlen(s), &table); 1937 if (j < 0) { 1938 dnslabel_clear(&table); 1939 return (int) j; 1940 } 1941 APPEND16(req->base.questions[i]->type); 1942 APPEND16(req->base.questions[i]->dns_question_class); 1943 } 1944 1945 /* Add answer, authority, and additional sections. */ 1946 for (i=0; i<3; ++i) { 1947 struct server_reply_item *item; 1948 if (i==0) 1949 item = req->answer; 1950 else if (i==1) 1951 item = req->authority; 1952 else 1953 item = req->additional; 1954 while (item) { 1955 r = dnsname_to_labels(buf, buf_len, j, item->name, strlen(item->name), &table); 1956 if (r < 0) 1957 goto overflow; 1958 j = r; 1959 1960 APPEND16(item->type); 1961 APPEND16(item->dns_question_class); 1962 APPEND32(item->ttl); 1963 if (item->is_name) { 1964 off_t len_idx = j, name_start; 1965 j += 2; 1966 name_start = j; 1967 r = dnsname_to_labels(buf, buf_len, j, item->data, strlen(item->data), &table); 1968 if (r < 0) 1969 goto overflow; 1970 j = r; 1971 t_ = htons( (short) (j-name_start) ); 1972 memcpy(buf+len_idx, &t_, 2); 1973 } else { 1974 APPEND16(item->datalen); 1975 if (j+item->datalen > (off_t)buf_len) 1976 goto overflow; 1977 memcpy(buf+j, item->data, item->datalen); 1978 j += item->datalen; 1979 } 1980 item = item->next; 1981 } 1982 } 1983 1984 if (j > 512) { 1985 overflow: 1986 j = 512; 1987 buf[2] |= 0x02; /* set the truncated bit. */ 1988 } 1989 1990 req->response_len = j; 1991 1992 if (!(req->response = mm_malloc(req->response_len))) { 1993 server_request_free_answers(req); 1994 dnslabel_clear(&table); 1995 return (-1); 1996 } 1997 memcpy(req->response, buf, req->response_len); 1998 server_request_free_answers(req); 1999 dnslabel_clear(&table); 2000 return (0); 2001 } 2002 2003 /* exported function */ 2004 int 2005 evdns_server_request_respond(struct evdns_server_request *req_, int err) 2006 { 2007 struct server_request *req = TO_SERVER_REQUEST(req_); 2008 struct evdns_server_port *port = req->port; 2009 int r = -1; 2010 2011 EVDNS_LOCK(port); 2012 if (!req->response) { 2013 if ((r = evdns_server_request_format_response(req, err))<0) 2014 goto done; 2015 } 2016 2017 r = sendto(port->socket, req->response, (int)req->response_len, 0, 2018 (struct sockaddr*) &req->addr, (ev_socklen_t)req->addrlen); 2019 if (r<0) { 2020 int sock_err = evutil_socket_geterror(port->socket); 2021 if (EVUTIL_ERR_RW_RETRIABLE(sock_err)) 2022 goto done; 2023 2024 if (port->pending_replies) { 2025 req->prev_pending = port->pending_replies->prev_pending; 2026 req->next_pending = port->pending_replies; 2027 req->prev_pending->next_pending = 2028 req->next_pending->prev_pending = req; 2029 } else { 2030 req->prev_pending = req->next_pending = req; 2031 port->pending_replies = req; 2032 port->choked = 1; 2033 2034 (void) event_del(&port->event); 2035 event_assign(&port->event, port->event_base, port->socket, (port->closing?0:EV_READ) | EV_WRITE | EV_PERSIST, server_port_ready_callback, port); 2036 2037 if (event_add(&port->event, NULL) < 0) { 2038 log(EVDNS_LOG_WARN, "Error from libevent when adding event for DNS server"); 2039 } 2040 2041 } 2042 2043 r = 1; 2044 goto done; 2045 } 2046 if (server_request_free(req)) { 2047 r = 0; 2048 goto done; 2049 } 2050 2051 if (port->pending_replies) 2052 server_port_flush(port); 2053 2054 r = 0; 2055 done: 2056 EVDNS_UNLOCK(port); 2057 return r; 2058 } 2059 2060 /* Free all storage held by RRs in req. */ 2061 static void 2062 server_request_free_answers(struct server_request *req) 2063 { 2064 struct server_reply_item *victim, *next, **list; 2065 int i; 2066 for (i = 0; i < 3; ++i) { 2067 if (i==0) 2068 list = &req->answer; 2069 else if (i==1) 2070 list = &req->authority; 2071 else 2072 list = &req->additional; 2073 2074 victim = *list; 2075 while (victim) { 2076 next = victim->next; 2077 mm_free(victim->name); 2078 if (victim->data) 2079 mm_free(victim->data); 2080 mm_free(victim); 2081 victim = next; 2082 } 2083 *list = NULL; 2084 } 2085 } 2086 2087 /* Free all storage held by req, and remove links to it. */ 2088 /* return true iff we just wound up freeing the server_port. */ 2089 static int 2090 server_request_free(struct server_request *req) 2091 { 2092 int i, rc=1, lock=0; 2093 if (req->base.questions) { 2094 for (i = 0; i < req->base.nquestions; ++i) 2095 mm_free(req->base.questions[i]); 2096 mm_free(req->base.questions); 2097 } 2098 2099 if (req->port) { 2100 EVDNS_LOCK(req->port); 2101 lock=1; 2102 if (req->port->pending_replies == req) { 2103 if (req->next_pending && req->next_pending != req) 2104 req->port->pending_replies = req->next_pending; 2105 else 2106 req->port->pending_replies = NULL; 2107 } 2108 rc = --req->port->refcnt; 2109 } 2110 2111 if (req->response) { 2112 mm_free(req->response); 2113 } 2114 2115 server_request_free_answers(req); 2116 2117 if (req->next_pending && req->next_pending != req) { 2118 req->next_pending->prev_pending = req->prev_pending; 2119 req->prev_pending->next_pending = req->next_pending; 2120 } 2121 2122 if (rc == 0) { 2123 EVDNS_UNLOCK(req->port); /* ????? nickm */ 2124 server_port_free(req->port); 2125 mm_free(req); 2126 return (1); 2127 } 2128 if (lock) 2129 EVDNS_UNLOCK(req->port); 2130 mm_free(req); 2131 return (0); 2132 } 2133 2134 /* Free all storage held by an evdns_server_port. Only called when */ 2135 static void 2136 server_port_free(struct evdns_server_port *port) 2137 { 2138 EVUTIL_ASSERT(port); 2139 EVUTIL_ASSERT(!port->refcnt); 2140 EVUTIL_ASSERT(!port->pending_replies); 2141 if (port->socket > 0) { 2142 evutil_closesocket(port->socket); 2143 port->socket = -1; 2144 } 2145 (void) event_del(&port->event); 2146 event_debug_unassign(&port->event); 2147 EVTHREAD_FREE_LOCK(port->lock, EVTHREAD_LOCKTYPE_RECURSIVE); 2148 mm_free(port); 2149 } 2150 2151 /* exported function */ 2152 int 2153 evdns_server_request_drop(struct evdns_server_request *req_) 2154 { 2155 struct server_request *req = TO_SERVER_REQUEST(req_); 2156 server_request_free(req); 2157 return 0; 2158 } 2159 2160 /* exported function */ 2161 int 2162 evdns_server_request_get_requesting_addr(struct evdns_server_request *req_, struct sockaddr *sa, int addr_len) 2163 { 2164 struct server_request *req = TO_SERVER_REQUEST(req_); 2165 if (addr_len < (int)req->addrlen) 2166 return -1; 2167 memcpy(sa, &(req->addr), req->addrlen); 2168 return req->addrlen; 2169 } 2170 2171 #undef APPEND16 2172 #undef APPEND32 2173 2174 /* this is a libevent callback function which is called when a request */ 2175 /* has timed out. */ 2176 static void 2177 evdns_request_timeout_callback(evutil_socket_t fd, short events, void *arg) { 2178 struct request *const req = (struct request *) arg; 2179 struct evdns_base *base = req->base; 2180 2181 (void) fd; 2182 (void) events; 2183 2184 log(EVDNS_LOG_DEBUG, "Request %p timed out", arg); 2185 EVDNS_LOCK(base); 2186 2187 if (req->tx_count >= req->base->global_max_retransmits) { 2188 struct nameserver *ns = req->ns; 2189 /* this request has failed */ 2190 log(EVDNS_LOG_DEBUG, "Giving up on request %p; tx_count==%d", 2191 arg, req->tx_count); 2192 reply_schedule_callback(req, 0, DNS_ERR_TIMEOUT, NULL); 2193 2194 request_finished(req, &REQ_HEAD(req->base, req->trans_id), 1); 2195 nameserver_failed(ns, "request timed out."); 2196 } else { 2197 /* retransmit it */ 2198 log(EVDNS_LOG_DEBUG, "Retransmitting request %p; tx_count==%d", 2199 arg, req->tx_count); 2200 (void) evtimer_del(&req->timeout_event); 2201 request_swap_ns(req, nameserver_pick(base)); 2202 evdns_request_transmit(req); 2203 2204 req->ns->timedout++; 2205 if (req->ns->timedout > req->base->global_max_nameserver_timeout) { 2206 req->ns->timedout = 0; 2207 nameserver_failed(req->ns, "request timed out."); 2208 } 2209 } 2210 2211 EVDNS_UNLOCK(base); 2212 } 2213 2214 /* try to send a request to a given server. */ 2215 /* */ 2216 /* return: */ 2217 /* 0 ok */ 2218 /* 1 temporary failure */ 2219 /* 2 other failure */ 2220 static int 2221 evdns_request_transmit_to(struct request *req, struct nameserver *server) { 2222 int r; 2223 ASSERT_LOCKED(req->base); 2224 ASSERT_VALID_REQUEST(req); 2225 2226 if (server->requests_inflight == 1 && 2227 req->base->disable_when_inactive && 2228 event_add(&server->event, NULL) < 0) { 2229 return 1; 2230 } 2231 2232 r = sendto(server->socket, (void*)req->request, req->request_len, 0, 2233 (struct sockaddr *)&server->address, server->addrlen); 2234 if (r < 0) { 2235 int err = evutil_socket_geterror(server->socket); 2236 if (EVUTIL_ERR_RW_RETRIABLE(err)) 2237 return 1; 2238 nameserver_failed(req->ns, evutil_socket_error_to_string(err)); 2239 return 2; 2240 } else if (r != (int)req->request_len) { 2241 return 1; /* short write */ 2242 } else { 2243 return 0; 2244 } 2245 } 2246 2247 /* try to send a request, updating the fields of the request */ 2248 /* as needed */ 2249 /* */ 2250 /* return: */ 2251 /* 0 ok */ 2252 /* 1 failed */ 2253 static int 2254 evdns_request_transmit(struct request *req) { 2255 int retcode = 0, r; 2256 2257 ASSERT_LOCKED(req->base); 2258 ASSERT_VALID_REQUEST(req); 2259 /* if we fail to send this packet then this flag marks it */ 2260 /* for evdns_transmit */ 2261 req->transmit_me = 1; 2262 EVUTIL_ASSERT(req->trans_id != 0xffff); 2263 2264 if (!req->ns) 2265 { 2266 /* unable to transmit request if no nameservers */ 2267 return 1; 2268 } 2269 2270 if (req->ns->choked) { 2271 /* don't bother trying to write to a socket */ 2272 /* which we have had EAGAIN from */ 2273 return 1; 2274 } 2275 2276 r = evdns_request_transmit_to(req, req->ns); 2277 switch (r) { 2278 case 1: 2279 /* temp failure */ 2280 req->ns->choked = 1; 2281 nameserver_write_waiting(req->ns, 1); 2282 return 1; 2283 case 2: 2284 /* failed to transmit the request entirely. we can fallthrough since 2285 * we'll set a timeout, which will time out, and make us retransmit the 2286 * request anyway. */ 2287 retcode = 1; 2288 EVUTIL_FALLTHROUGH; 2289 default: 2290 /* all ok */ 2291 log(EVDNS_LOG_DEBUG, 2292 "Setting timeout for request %p, sent to nameserver %p", req, req->ns); 2293 if (evtimer_add(&req->timeout_event, &req->base->global_timeout) < 0) { 2294 log(EVDNS_LOG_WARN, 2295 "Error from libevent when adding timer for request %p", 2296 req); 2297 /* ???? Do more? */ 2298 } 2299 req->tx_count++; 2300 req->transmit_me = 0; 2301 return retcode; 2302 } 2303 } 2304 2305 static void 2306 nameserver_probe_callback(int result, char type, int count, int ttl, void *addresses, void *arg) { 2307 struct nameserver *const ns = (struct nameserver *) arg; 2308 (void) type; 2309 (void) count; 2310 (void) ttl; 2311 (void) addresses; 2312 2313 if (result == DNS_ERR_CANCEL) { 2314 /* We canceled this request because the nameserver came up 2315 * for some other reason. Do not change our opinion about 2316 * the nameserver. */ 2317 return; 2318 } 2319 2320 EVDNS_LOCK(ns->base); 2321 ns->probe_request = NULL; 2322 if (result == DNS_ERR_NONE || result == DNS_ERR_NOTEXIST) { 2323 /* this is a good reply */ 2324 nameserver_up(ns); 2325 } else { 2326 nameserver_probe_failed(ns); 2327 } 2328 EVDNS_UNLOCK(ns->base); 2329 } 2330 2331 static void 2332 nameserver_send_probe(struct nameserver *const ns) { 2333 struct evdns_request *handle; 2334 struct request *req; 2335 char addrbuf[128]; 2336 /* here we need to send a probe to a given nameserver */ 2337 /* in the hope that it is up now. */ 2338 2339 ASSERT_LOCKED(ns->base); 2340 log(EVDNS_LOG_DEBUG, "Sending probe to %s", 2341 evutil_format_sockaddr_port_( 2342 (struct sockaddr *)&ns->address, 2343 addrbuf, sizeof(addrbuf))); 2344 handle = mm_calloc(1, sizeof(*handle)); 2345 if (!handle) return; 2346 req = request_new(ns->base, handle, TYPE_A, "google.com", DNS_QUERY_NO_SEARCH, nameserver_probe_callback, ns); 2347 if (!req) { 2348 mm_free(handle); 2349 return; 2350 } 2351 ns->probe_request = handle; 2352 /* we force this into the inflight queue no matter what */ 2353 request_trans_id_set(req, transaction_id_pick(ns->base)); 2354 req->ns = ns; 2355 request_submit(req); 2356 } 2357 2358 /* returns: */ 2359 /* 0 didn't try to transmit anything */ 2360 /* 1 tried to transmit something */ 2361 static int 2362 evdns_transmit(struct evdns_base *base) { 2363 char did_try_to_transmit = 0; 2364 int i; 2365 2366 ASSERT_LOCKED(base); 2367 for (i = 0; i < base->n_req_heads; ++i) { 2368 if (base->req_heads[i]) { 2369 struct request *const started_at = base->req_heads[i], *req = started_at; 2370 /* first transmit all the requests which are currently waiting */ 2371 do { 2372 if (req->transmit_me) { 2373 did_try_to_transmit = 1; 2374 evdns_request_transmit(req); 2375 } 2376 2377 req = req->next; 2378 } while (req != started_at); 2379 } 2380 } 2381 2382 return did_try_to_transmit; 2383 } 2384 2385 /* exported function */ 2386 int 2387 evdns_base_count_nameservers(struct evdns_base *base) 2388 { 2389 const struct nameserver *server; 2390 int n = 0; 2391 2392 EVDNS_LOCK(base); 2393 server = base->server_head; 2394 if (!server) 2395 goto done; 2396 do { 2397 ++n; 2398 server = server->next; 2399 } while (server != base->server_head); 2400 done: 2401 EVDNS_UNLOCK(base); 2402 return n; 2403 } 2404 2405 int 2406 evdns_count_nameservers(void) 2407 { 2408 return evdns_base_count_nameservers(current_base); 2409 } 2410 2411 /* exported function */ 2412 int 2413 evdns_base_clear_nameservers_and_suspend(struct evdns_base *base) 2414 { 2415 struct nameserver *server, *started_at; 2416 int i; 2417 2418 EVDNS_LOCK(base); 2419 server = base->server_head; 2420 started_at = base->server_head; 2421 if (!server) { 2422 EVDNS_UNLOCK(base); 2423 return 0; 2424 } 2425 while (1) { 2426 struct nameserver *next = server->next; 2427 (void) event_del(&server->event); 2428 if (evtimer_initialized(&server->timeout_event)) 2429 (void) evtimer_del(&server->timeout_event); 2430 if (server->probe_request) { 2431 evdns_cancel_request(server->base, server->probe_request); 2432 server->probe_request = NULL; 2433 } 2434 if (server->socket >= 0) 2435 evutil_closesocket(server->socket); 2436 mm_free(server); 2437 if (next == started_at) 2438 break; 2439 server = next; 2440 } 2441 base->server_head = NULL; 2442 base->global_good_nameservers = 0; 2443 2444 for (i = 0; i < base->n_req_heads; ++i) { 2445 struct request *req, *req_started_at; 2446 req = req_started_at = base->req_heads[i]; 2447 while (req) { 2448 struct request *next = req->next; 2449 req->tx_count = req->reissue_count = 0; 2450 req->ns = NULL; 2451 /* ???? What to do about searches? */ 2452 (void) evtimer_del(&req->timeout_event); 2453 req->trans_id = 0; 2454 req->transmit_me = 0; 2455 2456 base->global_requests_waiting++; 2457 evdns_request_insert(req, &base->req_waiting_head); 2458 /* We want to insert these suspended elements at the front of 2459 * the waiting queue, since they were pending before any of 2460 * the waiting entries were added. This is a circular list, 2461 * so we can just shift the start back by one.*/ 2462 base->req_waiting_head = base->req_waiting_head->prev; 2463 2464 if (next == req_started_at) 2465 break; 2466 req = next; 2467 } 2468 base->req_heads[i] = NULL; 2469 } 2470 2471 base->global_requests_inflight = 0; 2472 2473 EVDNS_UNLOCK(base); 2474 return 0; 2475 } 2476 2477 int 2478 evdns_clear_nameservers_and_suspend(void) 2479 { 2480 return evdns_base_clear_nameservers_and_suspend(current_base); 2481 } 2482 2483 2484 /* exported function */ 2485 int 2486 evdns_base_resume(struct evdns_base *base) 2487 { 2488 EVDNS_LOCK(base); 2489 evdns_requests_pump_waiting_queue(base); 2490 EVDNS_UNLOCK(base); 2491 2492 return 0; 2493 } 2494 2495 int 2496 evdns_resume(void) 2497 { 2498 return evdns_base_resume(current_base); 2499 } 2500 2501 static int 2502 evdns_nameserver_add_impl_(struct evdns_base *base, const struct sockaddr *address, int addrlen) { 2503 /* first check to see if we already have this nameserver */ 2504 2505 const struct nameserver *server = base->server_head, *const started_at = base->server_head; 2506 struct nameserver *ns; 2507 int err = 0; 2508 char addrbuf[128]; 2509 2510 ASSERT_LOCKED(base); 2511 if (server) { 2512 do { 2513 if (!evutil_sockaddr_cmp((struct sockaddr*)&server->address, address, 1)) return 3; 2514 server = server->next; 2515 } while (server != started_at); 2516 } 2517 if (addrlen > (int)sizeof(ns->address)) { 2518 log(EVDNS_LOG_DEBUG, "Addrlen %d too long.", (int)addrlen); 2519 return 2; 2520 } 2521 2522 ns = (struct nameserver *) mm_malloc(sizeof(struct nameserver)); 2523 if (!ns) return -1; 2524 2525 memset(ns, 0, sizeof(struct nameserver)); 2526 ns->base = base; 2527 2528 evtimer_assign(&ns->timeout_event, ns->base->event_base, nameserver_prod_callback, ns); 2529 2530 ns->socket = evutil_socket_(address->sa_family, 2531 SOCK_DGRAM|EVUTIL_SOCK_NONBLOCK|EVUTIL_SOCK_CLOEXEC, 0); 2532 if (ns->socket < 0) { err = 1; goto out1; } 2533 2534 if (base->global_outgoing_addrlen && 2535 !evutil_sockaddr_is_loopback_(address)) { 2536 if (bind(ns->socket, 2537 (struct sockaddr*)&base->global_outgoing_address, 2538 base->global_outgoing_addrlen) < 0) { 2539 log(EVDNS_LOG_WARN,"Couldn't bind to outgoing address"); 2540 err = 2; 2541 goto out2; 2542 } 2543 } 2544 2545 if (base->so_rcvbuf) { 2546 if (setsockopt(ns->socket, SOL_SOCKET, SO_RCVBUF, 2547 (void *)&base->so_rcvbuf, sizeof(base->so_rcvbuf))) { 2548 log(EVDNS_LOG_WARN, "Couldn't set SO_RCVBUF to %i", base->so_rcvbuf); 2549 err = -SO_RCVBUF; 2550 goto out2; 2551 } 2552 } 2553 if (base->so_sndbuf) { 2554 if (setsockopt(ns->socket, SOL_SOCKET, SO_SNDBUF, 2555 (void *)&base->so_sndbuf, sizeof(base->so_sndbuf))) { 2556 log(EVDNS_LOG_WARN, "Couldn't set SO_SNDBUF to %i", base->so_sndbuf); 2557 err = -SO_SNDBUF; 2558 goto out2; 2559 } 2560 } 2561 2562 memcpy(&ns->address, address, addrlen); 2563 ns->addrlen = addrlen; 2564 ns->state = 1; 2565 event_assign(&ns->event, ns->base->event_base, ns->socket, 2566 EV_READ | EV_PERSIST, nameserver_ready_callback, ns); 2567 if (!base->disable_when_inactive && event_add(&ns->event, NULL) < 0) { 2568 err = 2; 2569 goto out2; 2570 } 2571 2572 log(EVDNS_LOG_DEBUG, "Added nameserver %s as %p", 2573 evutil_format_sockaddr_port_(address, addrbuf, sizeof(addrbuf)), ns); 2574 2575 /* insert this nameserver into the list of them */ 2576 if (!base->server_head) { 2577 ns->next = ns->prev = ns; 2578 base->server_head = ns; 2579 } else { 2580 ns->next = base->server_head->next; 2581 ns->prev = base->server_head; 2582 base->server_head->next = ns; 2583 ns->next->prev = ns; 2584 } 2585 2586 base->global_good_nameservers++; 2587 2588 return 0; 2589 2590 out2: 2591 evutil_closesocket(ns->socket); 2592 out1: 2593 event_debug_unassign(&ns->event); 2594 mm_free(ns); 2595 log(EVDNS_LOG_WARN, "Unable to add nameserver %s: error %d", 2596 evutil_format_sockaddr_port_(address, addrbuf, sizeof(addrbuf)), err); 2597 return err; 2598 } 2599 2600 /* exported function */ 2601 int 2602 evdns_base_nameserver_add(struct evdns_base *base, unsigned long int address) 2603 { 2604 struct sockaddr_in sin; 2605 int res; 2606 memset(&sin, 0, sizeof(sin)); 2607 sin.sin_addr.s_addr = address; 2608 sin.sin_port = htons(53); 2609 sin.sin_family = AF_INET; 2610 EVDNS_LOCK(base); 2611 res = evdns_nameserver_add_impl_(base, (struct sockaddr*)&sin, sizeof(sin)); 2612 EVDNS_UNLOCK(base); 2613 return res; 2614 } 2615 2616 int 2617 evdns_nameserver_add(unsigned long int address) { 2618 if (!current_base) 2619 current_base = evdns_base_new(NULL, 0); 2620 return evdns_base_nameserver_add(current_base, address); 2621 } 2622 2623 static void 2624 sockaddr_setport(struct sockaddr *sa, ev_uint16_t port) 2625 { 2626 if (sa->sa_family == AF_INET) { 2627 ((struct sockaddr_in *)sa)->sin_port = htons(port); 2628 } else if (sa->sa_family == AF_INET6) { 2629 ((struct sockaddr_in6 *)sa)->sin6_port = htons(port); 2630 } 2631 } 2632 2633 static ev_uint16_t 2634 sockaddr_getport(struct sockaddr *sa) 2635 { 2636 if (sa->sa_family == AF_INET) { 2637 return ntohs(((struct sockaddr_in *)sa)->sin_port); 2638 } else if (sa->sa_family == AF_INET6) { 2639 return ntohs(((struct sockaddr_in6 *)sa)->sin6_port); 2640 } else { 2641 return 0; 2642 } 2643 } 2644 2645 /* exported function */ 2646 int 2647 evdns_base_nameserver_ip_add(struct evdns_base *base, const char *ip_as_string) { 2648 struct sockaddr_storage ss; 2649 struct sockaddr *sa; 2650 int len = sizeof(ss); 2651 int res; 2652 if (evutil_parse_sockaddr_port(ip_as_string, (struct sockaddr *)&ss, 2653 &len)) { 2654 log(EVDNS_LOG_WARN, "Unable to parse nameserver address %s", 2655 ip_as_string); 2656 return 4; 2657 } 2658 sa = (struct sockaddr *) &ss; 2659 if (sockaddr_getport(sa) == 0) 2660 sockaddr_setport(sa, 53); 2661 2662 EVDNS_LOCK(base); 2663 res = evdns_nameserver_add_impl_(base, sa, len); 2664 EVDNS_UNLOCK(base); 2665 return res; 2666 } 2667 2668 int 2669 evdns_nameserver_ip_add(const char *ip_as_string) { 2670 if (!current_base) 2671 current_base = evdns_base_new(NULL, 0); 2672 return evdns_base_nameserver_ip_add(current_base, ip_as_string); 2673 } 2674 2675 int 2676 evdns_base_nameserver_sockaddr_add(struct evdns_base *base, 2677 const struct sockaddr *sa, ev_socklen_t len, unsigned flags) 2678 { 2679 int res; 2680 EVUTIL_ASSERT(base); 2681 EVDNS_LOCK(base); 2682 res = evdns_nameserver_add_impl_(base, sa, len); 2683 EVDNS_UNLOCK(base); 2684 return res; 2685 } 2686 2687 int 2688 evdns_base_get_nameserver_addr(struct evdns_base *base, int idx, 2689 struct sockaddr *sa, ev_socklen_t len) 2690 { 2691 int result = -1; 2692 int i; 2693 struct nameserver *server; 2694 EVDNS_LOCK(base); 2695 server = base->server_head; 2696 for (i = 0; i < idx && server; ++i, server = server->next) { 2697 if (server->next == base->server_head) 2698 goto done; 2699 } 2700 if (! server) 2701 goto done; 2702 2703 if (server->addrlen > len) { 2704 result = (int) server->addrlen; 2705 goto done; 2706 } 2707 2708 memcpy(sa, &server->address, server->addrlen); 2709 result = (int) server->addrlen; 2710 done: 2711 EVDNS_UNLOCK(base); 2712 return result; 2713 } 2714 2715 /* remove from the queue */ 2716 static void 2717 evdns_request_remove(struct request *req, struct request **head) 2718 { 2719 ASSERT_LOCKED(req->base); 2720 ASSERT_VALID_REQUEST(req); 2721 2722 #if 0 2723 { 2724 struct request *ptr; 2725 int found = 0; 2726 EVUTIL_ASSERT(*head != NULL); 2727 2728 ptr = *head; 2729 do { 2730 if (ptr == req) { 2731 found = 1; 2732 break; 2733 } 2734 ptr = ptr->next; 2735 } while (ptr != *head); 2736 EVUTIL_ASSERT(found); 2737 2738 EVUTIL_ASSERT(req->next); 2739 } 2740 #endif 2741 2742 if (req->next == req) { 2743 /* only item in the list */ 2744 *head = NULL; 2745 } else { 2746 req->next->prev = req->prev; 2747 req->prev->next = req->next; 2748 if (*head == req) *head = req->next; 2749 } 2750 req->next = req->prev = NULL; 2751 } 2752 2753 /* insert into the tail of the queue */ 2754 static void 2755 evdns_request_insert(struct request *req, struct request **head) { 2756 ASSERT_LOCKED(req->base); 2757 ASSERT_VALID_REQUEST(req); 2758 if (!*head) { 2759 *head = req; 2760 req->next = req->prev = req; 2761 return; 2762 } 2763 2764 req->prev = (*head)->prev; 2765 req->prev->next = req; 2766 req->next = *head; 2767 (*head)->prev = req; 2768 } 2769 2770 static int 2771 string_num_dots(const char *s) { 2772 int count = 0; 2773 while ((s = strchr(s, '.'))) { 2774 s++; 2775 count++; 2776 } 2777 return count; 2778 } 2779 2780 static struct request * 2781 request_new(struct evdns_base *base, struct evdns_request *handle, int type, 2782 const char *name, int flags, evdns_callback_type callback, 2783 void *user_ptr) { 2784 2785 const char issuing_now = 2786 (base->global_requests_inflight < base->global_max_requests_inflight) ? 1 : 0; 2787 2788 const size_t name_len = strlen(name); 2789 const size_t request_max_len = evdns_request_len(name_len); 2790 const u16 trans_id = issuing_now ? transaction_id_pick(base) : 0xffff; 2791 /* the request data is alloced in a single block with the header */ 2792 struct request *const req = 2793 mm_malloc(sizeof(struct request) + request_max_len); 2794 int rlen; 2795 char namebuf[256]; 2796 (void) flags; 2797 2798 ASSERT_LOCKED(base); 2799 2800 if (!req) return NULL; 2801 2802 if (name_len >= sizeof(namebuf)) { 2803 mm_free(req); 2804 return NULL; 2805 } 2806 2807 memset(req, 0, sizeof(struct request)); 2808 req->base = base; 2809 2810 evtimer_assign(&req->timeout_event, req->base->event_base, evdns_request_timeout_callback, req); 2811 2812 if (base->global_randomize_case) { 2813 unsigned i; 2814 char randbits[(sizeof(namebuf)+7)/8]; 2815 strlcpy(namebuf, name, sizeof(namebuf)); 2816 evutil_secure_rng_get_bytes(randbits, (name_len+7)/8); 2817 for (i = 0; i < name_len; ++i) { 2818 if (EVUTIL_ISALPHA_(namebuf[i])) { 2819 if ((randbits[i >> 3] & (1<<(i & 7)))) 2820 namebuf[i] |= 0x20; 2821 else 2822 namebuf[i] &= ~0x20; 2823 } 2824 } 2825 name = namebuf; 2826 } 2827 2828 /* request data lives just after the header */ 2829 req->request = ((u8 *) req) + sizeof(struct request); 2830 /* denotes that the request data shouldn't be free()ed */ 2831 req->request_appended = 1; 2832 rlen = evdns_request_data_build(name, name_len, trans_id, 2833 type, CLASS_INET, req->request, request_max_len); 2834 if (rlen < 0) 2835 goto err1; 2836 2837 req->request_len = rlen; 2838 req->trans_id = trans_id; 2839 req->tx_count = 0; 2840 req->request_type = type; 2841 req->user_pointer = user_ptr; 2842 req->user_callback = callback; 2843 req->ns = issuing_now ? nameserver_pick(base) : NULL; 2844 req->next = req->prev = NULL; 2845 req->handle = handle; 2846 if (handle) { 2847 handle->current_req = req; 2848 handle->base = base; 2849 } 2850 2851 return req; 2852 err1: 2853 mm_free(req); 2854 return NULL; 2855 } 2856 2857 static void 2858 request_submit(struct request *const req) { 2859 struct evdns_base *base = req->base; 2860 ASSERT_LOCKED(base); 2861 ASSERT_VALID_REQUEST(req); 2862 if (req->ns) { 2863 /* if it has a nameserver assigned then this is going */ 2864 /* straight into the inflight queue */ 2865 evdns_request_insert(req, &REQ_HEAD(base, req->trans_id)); 2866 2867 base->global_requests_inflight++; 2868 req->ns->requests_inflight++; 2869 2870 evdns_request_transmit(req); 2871 } else { 2872 evdns_request_insert(req, &base->req_waiting_head); 2873 base->global_requests_waiting++; 2874 } 2875 } 2876 2877 /* exported function */ 2878 void 2879 evdns_cancel_request(struct evdns_base *base, struct evdns_request *handle) 2880 { 2881 struct request *req; 2882 2883 if (!handle->current_req) 2884 return; 2885 2886 if (!base) { 2887 /* This redundancy is silly; can we fix it? (Not for 2.0) XXXX */ 2888 base = handle->base; 2889 if (!base) 2890 base = handle->current_req->base; 2891 } 2892 2893 EVDNS_LOCK(base); 2894 if (handle->pending_cb) { 2895 EVDNS_UNLOCK(base); 2896 return; 2897 } 2898 2899 req = handle->current_req; 2900 ASSERT_VALID_REQUEST(req); 2901 2902 reply_schedule_callback(req, 0, DNS_ERR_CANCEL, NULL); 2903 if (req->ns) { 2904 /* remove from inflight queue */ 2905 request_finished(req, &REQ_HEAD(base, req->trans_id), 1); 2906 } else { 2907 /* remove from global_waiting head */ 2908 request_finished(req, &base->req_waiting_head, 1); 2909 } 2910 EVDNS_UNLOCK(base); 2911 } 2912 2913 /* exported function */ 2914 struct evdns_request * 2915 evdns_base_resolve_ipv4(struct evdns_base *base, const char *name, int flags, 2916 evdns_callback_type callback, void *ptr) { 2917 struct evdns_request *handle; 2918 struct request *req; 2919 log(EVDNS_LOG_DEBUG, "Resolve requested for %s", name); 2920 handle = mm_calloc(1, sizeof(*handle)); 2921 if (handle == NULL) 2922 return NULL; 2923 EVDNS_LOCK(base); 2924 if (flags & DNS_QUERY_NO_SEARCH) { 2925 req = 2926 request_new(base, handle, TYPE_A, name, flags, 2927 callback, ptr); 2928 if (req) 2929 request_submit(req); 2930 } else { 2931 search_request_new(base, handle, TYPE_A, name, flags, 2932 callback, ptr); 2933 } 2934 if (handle->current_req == NULL) { 2935 mm_free(handle); 2936 handle = NULL; 2937 } 2938 EVDNS_UNLOCK(base); 2939 return handle; 2940 } 2941 2942 int evdns_resolve_ipv4(const char *name, int flags, 2943 evdns_callback_type callback, void *ptr) 2944 { 2945 return evdns_base_resolve_ipv4(current_base, name, flags, callback, ptr) 2946 ? 0 : -1; 2947 } 2948 2949 2950 /* exported function */ 2951 struct evdns_request * 2952 evdns_base_resolve_ipv6(struct evdns_base *base, 2953 const char *name, int flags, 2954 evdns_callback_type callback, void *ptr) 2955 { 2956 struct evdns_request *handle; 2957 struct request *req; 2958 log(EVDNS_LOG_DEBUG, "Resolve requested for %s", name); 2959 handle = mm_calloc(1, sizeof(*handle)); 2960 if (handle == NULL) 2961 return NULL; 2962 EVDNS_LOCK(base); 2963 if (flags & DNS_QUERY_NO_SEARCH) { 2964 req = request_new(base, handle, TYPE_AAAA, name, flags, 2965 callback, ptr); 2966 if (req) 2967 request_submit(req); 2968 } else { 2969 search_request_new(base, handle, TYPE_AAAA, name, flags, 2970 callback, ptr); 2971 } 2972 if (handle->current_req == NULL) { 2973 mm_free(handle); 2974 handle = NULL; 2975 } 2976 EVDNS_UNLOCK(base); 2977 return handle; 2978 } 2979 2980 int evdns_resolve_ipv6(const char *name, int flags, 2981 evdns_callback_type callback, void *ptr) { 2982 return evdns_base_resolve_ipv6(current_base, name, flags, callback, ptr) 2983 ? 0 : -1; 2984 } 2985 2986 struct evdns_request * 2987 evdns_base_resolve_reverse(struct evdns_base *base, const struct in_addr *in, int flags, evdns_callback_type callback, void *ptr) { 2988 char buf[32]; 2989 struct evdns_request *handle; 2990 struct request *req; 2991 u32 a; 2992 EVUTIL_ASSERT(in); 2993 a = ntohl(in->s_addr); 2994 evutil_snprintf(buf, sizeof(buf), "%d.%d.%d.%d.in-addr.arpa", 2995 (int)(u8)((a )&0xff), 2996 (int)(u8)((a>>8 )&0xff), 2997 (int)(u8)((a>>16)&0xff), 2998 (int)(u8)((a>>24)&0xff)); 2999 handle = mm_calloc(1, sizeof(*handle)); 3000 if (handle == NULL) 3001 return NULL; 3002 log(EVDNS_LOG_DEBUG, "Resolve requested for %s (reverse)", buf); 3003 EVDNS_LOCK(base); 3004 req = request_new(base, handle, TYPE_PTR, buf, flags, callback, ptr); 3005 if (req) 3006 request_submit(req); 3007 if (handle->current_req == NULL) { 3008 mm_free(handle); 3009 handle = NULL; 3010 } 3011 EVDNS_UNLOCK(base); 3012 return (handle); 3013 } 3014 3015 int evdns_resolve_reverse(const struct in_addr *in, int flags, evdns_callback_type callback, void *ptr) { 3016 return evdns_base_resolve_reverse(current_base, in, flags, callback, ptr) 3017 ? 0 : -1; 3018 } 3019 3020 struct evdns_request * 3021 evdns_base_resolve_reverse_ipv6(struct evdns_base *base, const struct in6_addr *in, int flags, evdns_callback_type callback, void *ptr) { 3022 /* 32 nybbles, 32 periods, "ip6.arpa", NUL. */ 3023 char buf[73]; 3024 char *cp; 3025 struct evdns_request *handle; 3026 struct request *req; 3027 int i; 3028 EVUTIL_ASSERT(in); 3029 cp = buf; 3030 for (i=15; i >= 0; --i) { 3031 u8 byte = in->s6_addr[i]; 3032 *cp++ = "0123456789abcdef"[byte & 0x0f]; 3033 *cp++ = '.'; 3034 *cp++ = "0123456789abcdef"[byte >> 4]; 3035 *cp++ = '.'; 3036 } 3037 EVUTIL_ASSERT(cp + strlen("ip6.arpa") < buf+sizeof(buf)); 3038 memcpy(cp, "ip6.arpa", strlen("ip6.arpa")+1); 3039 handle = mm_calloc(1, sizeof(*handle)); 3040 if (handle == NULL) 3041 return NULL; 3042 log(EVDNS_LOG_DEBUG, "Resolve requested for %s (reverse)", buf); 3043 EVDNS_LOCK(base); 3044 req = request_new(base, handle, TYPE_PTR, buf, flags, callback, ptr); 3045 if (req) 3046 request_submit(req); 3047 if (handle->current_req == NULL) { 3048 mm_free(handle); 3049 handle = NULL; 3050 } 3051 EVDNS_UNLOCK(base); 3052 return (handle); 3053 } 3054 3055 int evdns_resolve_reverse_ipv6(const struct in6_addr *in, int flags, evdns_callback_type callback, void *ptr) { 3056 return evdns_base_resolve_reverse_ipv6(current_base, in, flags, callback, ptr) 3057 ? 0 : -1; 3058 } 3059 3060 /* ================================================================= */ 3061 /* Search support */ 3062 /* */ 3063 /* the libc resolver has support for searching a number of domains */ 3064 /* to find a name. If nothing else then it takes the single domain */ 3065 /* from the gethostname() call. */ 3066 /* */ 3067 /* It can also be configured via the domain and search options in a */ 3068 /* resolv.conf. */ 3069 /* */ 3070 /* The ndots option controls how many dots it takes for the resolver */ 3071 /* to decide that a name is non-local and so try a raw lookup first. */ 3072 3073 struct search_domain { 3074 int len; 3075 struct search_domain *next; 3076 /* the text string is appended to this structure */ 3077 }; 3078 3079 struct search_state { 3080 int refcount; 3081 int ndots; 3082 int num_domains; 3083 struct search_domain *head; 3084 }; 3085 3086 static void 3087 search_state_decref(struct search_state *const state) { 3088 if (!state) return; 3089 state->refcount--; 3090 if (!state->refcount) { 3091 struct search_domain *next, *dom; 3092 for (dom = state->head; dom; dom = next) { 3093 next = dom->next; 3094 mm_free(dom); 3095 } 3096 mm_free(state); 3097 } 3098 } 3099 3100 static struct search_state * 3101 search_state_new(void) { 3102 struct search_state *state = (struct search_state *) mm_malloc(sizeof(struct search_state)); 3103 if (!state) return NULL; 3104 memset(state, 0, sizeof(struct search_state)); 3105 state->refcount = 1; 3106 state->ndots = 1; 3107 3108 return state; 3109 } 3110 3111 static void 3112 search_postfix_clear(struct evdns_base *base) { 3113 search_state_decref(base->global_search_state); 3114 3115 base->global_search_state = search_state_new(); 3116 } 3117 3118 /* exported function */ 3119 void 3120 evdns_base_search_clear(struct evdns_base *base) 3121 { 3122 EVDNS_LOCK(base); 3123 search_postfix_clear(base); 3124 EVDNS_UNLOCK(base); 3125 } 3126 3127 void 3128 evdns_search_clear(void) { 3129 evdns_base_search_clear(current_base); 3130 } 3131 3132 static void 3133 search_postfix_add(struct evdns_base *base, const char *domain) { 3134 size_t domain_len; 3135 struct search_domain *sdomain; 3136 while (domain[0] == '.') domain++; 3137 domain_len = strlen(domain); 3138 3139 ASSERT_LOCKED(base); 3140 if (!base->global_search_state) base->global_search_state = search_state_new(); 3141 if (!base->global_search_state) return; 3142 base->global_search_state->num_domains++; 3143 3144 sdomain = (struct search_domain *) mm_malloc(sizeof(struct search_domain) + domain_len); 3145 if (!sdomain) return; 3146 memcpy( ((u8 *) sdomain) + sizeof(struct search_domain), domain, domain_len); 3147 sdomain->next = base->global_search_state->head; 3148 sdomain->len = (int) domain_len; 3149 3150 base->global_search_state->head = sdomain; 3151 } 3152 3153 /* reverse the order of members in the postfix list. This is needed because, */ 3154 /* when parsing resolv.conf we push elements in the wrong order */ 3155 static void 3156 search_reverse(struct evdns_base *base) { 3157 struct search_domain *cur, *prev = NULL, *next; 3158 ASSERT_LOCKED(base); 3159 cur = base->global_search_state->head; 3160 while (cur) { 3161 next = cur->next; 3162 cur->next = prev; 3163 prev = cur; 3164 cur = next; 3165 } 3166 3167 base->global_search_state->head = prev; 3168 } 3169 3170 /* exported function */ 3171 void 3172 evdns_base_search_add(struct evdns_base *base, const char *domain) { 3173 EVDNS_LOCK(base); 3174 search_postfix_add(base, domain); 3175 EVDNS_UNLOCK(base); 3176 } 3177 void 3178 evdns_search_add(const char *domain) { 3179 evdns_base_search_add(current_base, domain); 3180 } 3181 3182 /* exported function */ 3183 void 3184 evdns_base_search_ndots_set(struct evdns_base *base, const int ndots) { 3185 EVDNS_LOCK(base); 3186 if (!base->global_search_state) base->global_search_state = search_state_new(); 3187 if (base->global_search_state) 3188 base->global_search_state->ndots = ndots; 3189 EVDNS_UNLOCK(base); 3190 } 3191 void 3192 evdns_search_ndots_set(const int ndots) { 3193 evdns_base_search_ndots_set(current_base, ndots); 3194 } 3195 3196 static void 3197 search_set_from_hostname(struct evdns_base *base) { 3198 char hostname[HOST_NAME_MAX + 1], *domainname; 3199 3200 ASSERT_LOCKED(base); 3201 search_postfix_clear(base); 3202 if (gethostname(hostname, sizeof(hostname))) return; 3203 domainname = strchr(hostname, '.'); 3204 if (!domainname) return; 3205 search_postfix_add(base, domainname); 3206 } 3207 3208 /* warning: returns malloced string */ 3209 static char * 3210 search_make_new(const struct search_state *const state, int n, const char *const base_name) { 3211 const size_t base_len = strlen(base_name); 3212 char need_to_append_dot; 3213 struct search_domain *dom; 3214 3215 if (!base_len) return NULL; 3216 need_to_append_dot = base_name[base_len - 1] == '.' ? 0 : 1; 3217 3218 for (dom = state->head; dom; dom = dom->next) { 3219 if (!n--) { 3220 /* this is the postfix we want */ 3221 /* the actual postfix string is kept at the end of the structure */ 3222 const u8 *const postfix = ((u8 *) dom) + sizeof(struct search_domain); 3223 const int postfix_len = dom->len; 3224 char *const newname = (char *) mm_malloc(base_len + need_to_append_dot + postfix_len + 1); 3225 if (!newname) return NULL; 3226 memcpy(newname, base_name, base_len); 3227 if (need_to_append_dot) newname[base_len] = '.'; 3228 memcpy(newname + base_len + need_to_append_dot, postfix, postfix_len); 3229 newname[base_len + need_to_append_dot + postfix_len] = 0; 3230 return newname; 3231 } 3232 } 3233 3234 /* we ran off the end of the list and still didn't find the requested string */ 3235 EVUTIL_ASSERT(0); 3236 return NULL; /* unreachable; stops warnings in some compilers. */ 3237 } 3238 3239 static struct request * 3240 search_request_new(struct evdns_base *base, struct evdns_request *handle, 3241 int type, const char *const name, int flags, 3242 evdns_callback_type user_callback, void *user_arg) { 3243 ASSERT_LOCKED(base); 3244 EVUTIL_ASSERT(type == TYPE_A || type == TYPE_AAAA); 3245 EVUTIL_ASSERT(handle->current_req == NULL); 3246 if ( ((flags & DNS_QUERY_NO_SEARCH) == 0) && 3247 base->global_search_state && 3248 base->global_search_state->num_domains) { 3249 /* we have some domains to search */ 3250 struct request *req; 3251 if (string_num_dots(name) >= base->global_search_state->ndots) { 3252 req = request_new(base, handle, type, name, flags, user_callback, user_arg); 3253 if (!req) return NULL; 3254 handle->search_index = -1; 3255 } else { 3256 char *const new_name = search_make_new(base->global_search_state, 0, name); 3257 if (!new_name) return NULL; 3258 req = request_new(base, handle, type, new_name, flags, user_callback, user_arg); 3259 mm_free(new_name); 3260 if (!req) return NULL; 3261 handle->search_index = 0; 3262 } 3263 EVUTIL_ASSERT(handle->search_origname == NULL); 3264 handle->search_origname = mm_strdup(name); 3265 if (handle->search_origname == NULL) { 3266 /* XXX Should we dealloc req? If yes, how? */ 3267 if (req) 3268 mm_free(req); 3269 return NULL; 3270 } 3271 handle->search_state = base->global_search_state; 3272 handle->search_flags = flags; 3273 base->global_search_state->refcount++; 3274 request_submit(req); 3275 return req; 3276 } else { 3277 struct request *const req = request_new(base, handle, type, name, flags, user_callback, user_arg); 3278 if (!req) return NULL; 3279 request_submit(req); 3280 return req; 3281 } 3282 } 3283 3284 /* this is called when a request has failed to find a name. We need to check */ 3285 /* if it is part of a search and, if so, try the next name in the list */ 3286 /* returns: */ 3287 /* 0 another request has been submitted */ 3288 /* 1 no more requests needed */ 3289 static int 3290 search_try_next(struct evdns_request *const handle) { 3291 struct request *req = handle->current_req; 3292 struct evdns_base *base = req->base; 3293 struct request *newreq; 3294 ASSERT_LOCKED(base); 3295 if (handle->search_state) { 3296 /* it is part of a search */ 3297 char *new_name; 3298 handle->search_index++; 3299 if (handle->search_index >= handle->search_state->num_domains) { 3300 /* no more postfixes to try, however we may need to try */ 3301 /* this name without a postfix */ 3302 if (string_num_dots(handle->search_origname) < handle->search_state->ndots) { 3303 /* yep, we need to try it raw */ 3304 newreq = request_new(base, NULL, req->request_type, handle->search_origname, handle->search_flags, req->user_callback, req->user_pointer); 3305 log(EVDNS_LOG_DEBUG, "Search: trying raw query %s", handle->search_origname); 3306 if (newreq) { 3307 search_request_finished(handle); 3308 goto submit_next; 3309 } 3310 } 3311 return 1; 3312 } 3313 3314 new_name = search_make_new(handle->search_state, handle->search_index, handle->search_origname); 3315 if (!new_name) return 1; 3316 log(EVDNS_LOG_DEBUG, "Search: now trying %s (%d)", new_name, handle->search_index); 3317 newreq = request_new(base, NULL, req->request_type, new_name, handle->search_flags, req->user_callback, req->user_pointer); 3318 mm_free(new_name); 3319 if (!newreq) return 1; 3320 goto submit_next; 3321 } 3322 return 1; 3323 3324 submit_next: 3325 request_finished(req, &REQ_HEAD(req->base, req->trans_id), 0); 3326 handle->current_req = newreq; 3327 newreq->handle = handle; 3328 request_submit(newreq); 3329 return 0; 3330 } 3331 3332 static void 3333 search_request_finished(struct evdns_request *const handle) { 3334 ASSERT_LOCKED(handle->current_req->base); 3335 if (handle->search_state) { 3336 search_state_decref(handle->search_state); 3337 handle->search_state = NULL; 3338 } 3339 if (handle->search_origname) { 3340 mm_free(handle->search_origname); 3341 handle->search_origname = NULL; 3342 } 3343 } 3344 3345 /* ================================================================= */ 3346 /* Parsing resolv.conf files */ 3347 3348 static void 3349 evdns_resolv_set_defaults(struct evdns_base *base, int flags) { 3350 int add_default = flags & DNS_OPTION_NAMESERVERS; 3351 if (flags & DNS_OPTION_NAMESERVERS_NO_DEFAULT) 3352 add_default = 0; 3353 3354 /* if the file isn't found then we assume a local resolver */ 3355 ASSERT_LOCKED(base); 3356 if (flags & DNS_OPTION_SEARCH) 3357 search_set_from_hostname(base); 3358 if (add_default) 3359 evdns_base_nameserver_ip_add(base, "127.0.0.1"); 3360 } 3361 3362 #ifndef EVENT__HAVE_STRTOK_R 3363 static char * 3364 strtok_r(char *s, const char *delim, char **state) { 3365 char *cp, *start; 3366 start = cp = s ? s : *state; 3367 if (!cp) 3368 return NULL; 3369 while (*cp && !strchr(delim, *cp)) 3370 ++cp; 3371 if (!*cp) { 3372 if (cp == start) 3373 return NULL; 3374 *state = NULL; 3375 return start; 3376 } else { 3377 *cp++ = '\0'; 3378 *state = cp; 3379 return start; 3380 } 3381 } 3382 #endif 3383 3384 /* helper version of atoi which returns -1 on error */ 3385 static int 3386 strtoint(const char *const str) 3387 { 3388 char *endptr; 3389 const int r = strtol(str, &endptr, 10); 3390 if (*endptr) return -1; 3391 return r; 3392 } 3393 3394 /* Parse a number of seconds into a timeval; return -1 on error. */ 3395 static int 3396 evdns_strtotimeval(const char *const str, struct timeval *out) 3397 { 3398 double d; 3399 char *endptr; 3400 d = strtod(str, &endptr); 3401 if (*endptr) return -1; 3402 if (d < 0) return -1; 3403 out->tv_sec = (int) d; 3404 out->tv_usec = (int) ((d - (int) d)*1000000); 3405 if (out->tv_sec == 0 && out->tv_usec < 1000) /* less than 1 msec */ 3406 return -1; 3407 return 0; 3408 } 3409 3410 /* helper version of atoi that returns -1 on error and clips to bounds. */ 3411 static int 3412 strtoint_clipped(const char *const str, int min, int max) 3413 { 3414 int r = strtoint(str); 3415 if (r == -1) 3416 return r; 3417 else if (r<min) 3418 return min; 3419 else if (r>max) 3420 return max; 3421 else 3422 return r; 3423 } 3424 3425 static int 3426 evdns_base_set_max_requests_inflight(struct evdns_base *base, int maxinflight) 3427 { 3428 int old_n_heads = base->n_req_heads, n_heads; 3429 struct request **old_heads = base->req_heads, **new_heads, *req; 3430 int i; 3431 3432 ASSERT_LOCKED(base); 3433 if (maxinflight < 1) 3434 maxinflight = 1; 3435 n_heads = (maxinflight+4) / 5; 3436 EVUTIL_ASSERT(n_heads > 0); 3437 new_heads = mm_calloc(n_heads, sizeof(struct request*)); 3438 if (!new_heads) 3439 return (-1); 3440 if (old_heads) { 3441 for (i = 0; i < old_n_heads; ++i) { 3442 while (old_heads[i]) { 3443 req = old_heads[i]; 3444 evdns_request_remove(req, &old_heads[i]); 3445 evdns_request_insert(req, &new_heads[req->trans_id % n_heads]); 3446 } 3447 } 3448 mm_free(old_heads); 3449 } 3450 base->req_heads = new_heads; 3451 base->n_req_heads = n_heads; 3452 base->global_max_requests_inflight = maxinflight; 3453 return (0); 3454 } 3455 3456 /* exported function */ 3457 int 3458 evdns_base_set_option(struct evdns_base *base, 3459 const char *option, const char *val) 3460 { 3461 int res; 3462 EVDNS_LOCK(base); 3463 res = evdns_base_set_option_impl(base, option, val, DNS_OPTIONS_ALL); 3464 EVDNS_UNLOCK(base); 3465 return res; 3466 } 3467 3468 static inline int 3469 str_matches_option(const char *s1, const char *optionname) 3470 { 3471 /* Option names are given as "option:" We accept either 'option' in 3472 * s1, or 'option:randomjunk'. The latter form is to implement the 3473 * resolv.conf parser. */ 3474 size_t optlen = strlen(optionname); 3475 size_t slen = strlen(s1); 3476 if (slen == optlen || slen == optlen - 1) 3477 return !strncmp(s1, optionname, slen); 3478 else if (slen > optlen) 3479 return !strncmp(s1, optionname, optlen); 3480 else 3481 return 0; 3482 } 3483 3484 static int 3485 evdns_base_set_option_impl(struct evdns_base *base, 3486 const char *option, const char *val, int flags) 3487 { 3488 ASSERT_LOCKED(base); 3489 if (str_matches_option(option, "ndots:")) { 3490 const int ndots = strtoint(val); 3491 if (ndots == -1) return -1; 3492 if (!(flags & DNS_OPTION_SEARCH)) return 0; 3493 log(EVDNS_LOG_DEBUG, "Setting ndots to %d", ndots); 3494 if (!base->global_search_state) base->global_search_state = search_state_new(); 3495 if (!base->global_search_state) return -1; 3496 base->global_search_state->ndots = ndots; 3497 } else if (str_matches_option(option, "timeout:")) { 3498 struct timeval tv; 3499 if (evdns_strtotimeval(val, &tv) == -1) return -1; 3500 if (!(flags & DNS_OPTION_MISC)) return 0; 3501 log(EVDNS_LOG_DEBUG, "Setting timeout to %s", val); 3502 memcpy(&base->global_timeout, &tv, sizeof(struct timeval)); 3503 } else if (str_matches_option(option, "getaddrinfo-allow-skew:")) { 3504 struct timeval tv; 3505 if (evdns_strtotimeval(val, &tv) == -1) return -1; 3506 if (!(flags & DNS_OPTION_MISC)) return 0; 3507 log(EVDNS_LOG_DEBUG, "Setting getaddrinfo-allow-skew to %s", 3508 val); 3509 memcpy(&base->global_getaddrinfo_allow_skew, &tv, 3510 sizeof(struct timeval)); 3511 } else if (str_matches_option(option, "max-timeouts:")) { 3512 const int maxtimeout = strtoint_clipped(val, 1, 255); 3513 if (maxtimeout == -1) return -1; 3514 if (!(flags & DNS_OPTION_MISC)) return 0; 3515 log(EVDNS_LOG_DEBUG, "Setting maximum allowed timeouts to %d", 3516 maxtimeout); 3517 base->global_max_nameserver_timeout = maxtimeout; 3518 } else if (str_matches_option(option, "max-inflight:")) { 3519 const int maxinflight = strtoint_clipped(val, 1, 65000); 3520 if (maxinflight == -1) return -1; 3521 if (!(flags & DNS_OPTION_MISC)) return 0; 3522 log(EVDNS_LOG_DEBUG, "Setting maximum inflight requests to %d", 3523 maxinflight); 3524 evdns_base_set_max_requests_inflight(base, maxinflight); 3525 } else if (str_matches_option(option, "attempts:")) { 3526 int retries = strtoint(val); 3527 if (retries == -1) return -1; 3528 if (retries > 255) retries = 255; 3529 if (!(flags & DNS_OPTION_MISC)) return 0; 3530 log(EVDNS_LOG_DEBUG, "Setting retries to %d", retries); 3531 base->global_max_retransmits = retries; 3532 } else if (str_matches_option(option, "randomize-case:")) { 3533 int randcase = strtoint(val); 3534 if (randcase == -1) return -1; 3535 if (!(flags & DNS_OPTION_MISC)) return 0; 3536 base->global_randomize_case = randcase; 3537 } else if (str_matches_option(option, "bind-to:")) { 3538 /* XXX This only applies to successive nameservers, not 3539 * to already-configured ones. We might want to fix that. */ 3540 int len = sizeof(base->global_outgoing_address); 3541 if (!(flags & DNS_OPTION_NAMESERVERS)) return 0; 3542 if (evutil_parse_sockaddr_port(val, 3543 (struct sockaddr*)&base->global_outgoing_address, &len)) 3544 return -1; 3545 base->global_outgoing_addrlen = len; 3546 } else if (str_matches_option(option, "initial-probe-timeout:")) { 3547 struct timeval tv; 3548 if (evdns_strtotimeval(val, &tv) == -1) return -1; 3549 if (tv.tv_sec > 3600) 3550 tv.tv_sec = 3600; 3551 if (!(flags & DNS_OPTION_MISC)) return 0; 3552 log(EVDNS_LOG_DEBUG, "Setting initial probe timeout to %s", 3553 val); 3554 memcpy(&base->global_nameserver_probe_initial_timeout, &tv, 3555 sizeof(tv)); 3556 } else if (str_matches_option(option, "so-rcvbuf:")) { 3557 int buf = strtoint(val); 3558 if (buf == -1) return -1; 3559 if (!(flags & DNS_OPTION_MISC)) return 0; 3560 log(EVDNS_LOG_DEBUG, "Setting SO_RCVBUF to %s", val); 3561 base->so_rcvbuf = buf; 3562 } else if (str_matches_option(option, "so-sndbuf:")) { 3563 int buf = strtoint(val); 3564 if (buf == -1) return -1; 3565 if (!(flags & DNS_OPTION_MISC)) return 0; 3566 log(EVDNS_LOG_DEBUG, "Setting SO_SNDBUF to %s", val); 3567 base->so_sndbuf = buf; 3568 } 3569 return 0; 3570 } 3571 3572 int 3573 evdns_set_option(const char *option, const char *val, int flags) 3574 { 3575 if (!current_base) 3576 current_base = evdns_base_new(NULL, 0); 3577 return evdns_base_set_option(current_base, option, val); 3578 } 3579 3580 static void 3581 resolv_conf_parse_line(struct evdns_base *base, char *const start, int flags) { 3582 char *strtok_state; 3583 static const char *const delims = " \t"; 3584 #define NEXT_TOKEN strtok_r(NULL, delims, &strtok_state) 3585 3586 3587 char *const first_token = strtok_r(start, delims, &strtok_state); 3588 ASSERT_LOCKED(base); 3589 if (!first_token) return; 3590 3591 if (!strcmp(first_token, "nameserver") && (flags & DNS_OPTION_NAMESERVERS)) { 3592 const char *const nameserver = NEXT_TOKEN; 3593 3594 if (nameserver) 3595 evdns_base_nameserver_ip_add(base, nameserver); 3596 } else if (!strcmp(first_token, "domain") && (flags & DNS_OPTION_SEARCH)) { 3597 const char *const domain = NEXT_TOKEN; 3598 if (domain) { 3599 search_postfix_clear(base); 3600 search_postfix_add(base, domain); 3601 } 3602 } else if (!strcmp(first_token, "search") && (flags & DNS_OPTION_SEARCH)) { 3603 const char *domain; 3604 search_postfix_clear(base); 3605 3606 while ((domain = NEXT_TOKEN)) { 3607 search_postfix_add(base, domain); 3608 } 3609 search_reverse(base); 3610 } else if (!strcmp(first_token, "options")) { 3611 const char *option; 3612 while ((option = NEXT_TOKEN)) { 3613 const char *val = strchr(option, ':'); 3614 evdns_base_set_option_impl(base, option, val ? val+1 : "", flags); 3615 } 3616 } 3617 #undef NEXT_TOKEN 3618 } 3619 3620 /* exported function */ 3621 /* returns: */ 3622 /* 0 no errors */ 3623 /* 1 failed to open file */ 3624 /* 2 failed to stat file */ 3625 /* 3 file too large */ 3626 /* 4 out of memory */ 3627 /* 5 short read from file */ 3628 int 3629 evdns_base_resolv_conf_parse(struct evdns_base *base, int flags, const char *const filename) { 3630 int res; 3631 EVDNS_LOCK(base); 3632 res = evdns_base_resolv_conf_parse_impl(base, flags, filename); 3633 EVDNS_UNLOCK(base); 3634 return res; 3635 } 3636 3637 static char * 3638 evdns_get_default_hosts_filename(void) 3639 { 3640 #ifdef _WIN32 3641 /* Windows is a little coy about where it puts its configuration 3642 * files. Sure, they're _usually_ in C:\windows\system32, but 3643 * there's no reason in principle they couldn't be in 3644 * W:\hoboken chicken emergency\ 3645 */ 3646 char path[MAX_PATH+1]; 3647 static const char hostfile[] = "\\drivers\\etc\\hosts"; 3648 char *path_out; 3649 size_t len_out; 3650 3651 if (! SHGetSpecialFolderPathA(NULL, path, CSIDL_SYSTEM, 0)) 3652 return NULL; 3653 len_out = strlen(path)+strlen(hostfile)+1; 3654 path_out = mm_malloc(len_out); 3655 evutil_snprintf(path_out, len_out, "%s%s", path, hostfile); 3656 return path_out; 3657 #else 3658 return mm_strdup("/etc/hosts"); 3659 #endif 3660 } 3661 3662 static int 3663 evdns_base_resolv_conf_parse_impl(struct evdns_base *base, int flags, const char *const filename) { 3664 size_t n; 3665 char *resolv; 3666 char *start; 3667 int err = 0; 3668 int add_default; 3669 3670 log(EVDNS_LOG_DEBUG, "Parsing resolv.conf file %s", filename); 3671 3672 add_default = flags & DNS_OPTION_NAMESERVERS; 3673 if (flags & DNS_OPTION_NAMESERVERS_NO_DEFAULT) 3674 add_default = 0; 3675 3676 if (flags & DNS_OPTION_HOSTSFILE) { 3677 char *fname = evdns_get_default_hosts_filename(); 3678 evdns_base_load_hosts(base, fname); 3679 if (fname) 3680 mm_free(fname); 3681 } 3682 3683 if (!filename) { 3684 evdns_resolv_set_defaults(base, flags); 3685 return 1; 3686 } 3687 3688 if ((err = evutil_read_file_(filename, &resolv, &n, 0)) < 0) { 3689 if (err == -1) { 3690 /* No file. */ 3691 evdns_resolv_set_defaults(base, flags); 3692 return 1; 3693 } else { 3694 return 2; 3695 } 3696 } 3697 3698 start = resolv; 3699 for (;;) { 3700 char *const newline = strchr(start, '\n'); 3701 if (!newline) { 3702 resolv_conf_parse_line(base, start, flags); 3703 break; 3704 } else { 3705 *newline = 0; 3706 resolv_conf_parse_line(base, start, flags); 3707 start = newline + 1; 3708 } 3709 } 3710 3711 if (!base->server_head && add_default) { 3712 /* no nameservers were configured. */ 3713 evdns_base_nameserver_ip_add(base, "127.0.0.1"); 3714 err = 6; 3715 } 3716 if (flags & DNS_OPTION_SEARCH && (!base->global_search_state || base->global_search_state->num_domains == 0)) { 3717 search_set_from_hostname(base); 3718 } 3719 3720 mm_free(resolv); 3721 return err; 3722 } 3723 3724 int 3725 evdns_resolv_conf_parse(int flags, const char *const filename) { 3726 if (!current_base) 3727 current_base = evdns_base_new(NULL, 0); 3728 return evdns_base_resolv_conf_parse(current_base, flags, filename); 3729 } 3730 3731 3732 #ifdef _WIN32 3733 /* Add multiple nameservers from a space-or-comma-separated list. */ 3734 static int 3735 evdns_nameserver_ip_add_line(struct evdns_base *base, const char *ips) { 3736 const char *addr; 3737 char *buf; 3738 int r; 3739 ASSERT_LOCKED(base); 3740 while (*ips) { 3741 while (isspace(*ips) || *ips == ',' || *ips == '\t') 3742 ++ips; 3743 addr = ips; 3744 while (isdigit(*ips) || *ips == '.' || *ips == ':' || 3745 *ips=='[' || *ips==']') 3746 ++ips; 3747 buf = mm_malloc(ips-addr+1); 3748 if (!buf) return 4; 3749 memcpy(buf, addr, ips-addr); 3750 buf[ips-addr] = '\0'; 3751 r = evdns_base_nameserver_ip_add(base, buf); 3752 mm_free(buf); 3753 if (r) return r; 3754 } 3755 return 0; 3756 } 3757 3758 typedef DWORD(WINAPI *GetNetworkParams_fn_t)(FIXED_INFO *, DWORD*); 3759 3760 /* Use the windows GetNetworkParams interface in iphlpapi.dll to */ 3761 /* figure out what our nameservers are. */ 3762 static int 3763 load_nameservers_with_getnetworkparams(struct evdns_base *base) 3764 { 3765 /* Based on MSDN examples and inspection of c-ares code. */ 3766 FIXED_INFO *fixed; 3767 HMODULE handle = 0; 3768 ULONG size = sizeof(FIXED_INFO); 3769 void *buf = NULL; 3770 int status = 0, r, added_any; 3771 IP_ADDR_STRING *ns; 3772 GetNetworkParams_fn_t fn; 3773 3774 ASSERT_LOCKED(base); 3775 if (!(handle = evutil_load_windows_system_library_( 3776 TEXT("iphlpapi.dll")))) { 3777 log(EVDNS_LOG_WARN, "Could not open iphlpapi.dll"); 3778 status = -1; 3779 goto done; 3780 } 3781 if (!(fn = (GetNetworkParams_fn_t) GetProcAddress(handle, "GetNetworkParams"))) { 3782 log(EVDNS_LOG_WARN, "Could not get address of function."); 3783 status = -1; 3784 goto done; 3785 } 3786 3787 buf = mm_malloc(size); 3788 if (!buf) { status = 4; goto done; } 3789 fixed = buf; 3790 r = fn(fixed, &size); 3791 if (r != ERROR_SUCCESS && r != ERROR_BUFFER_OVERFLOW) { 3792 status = -1; 3793 goto done; 3794 } 3795 if (r != ERROR_SUCCESS) { 3796 mm_free(buf); 3797 buf = mm_malloc(size); 3798 if (!buf) { status = 4; goto done; } 3799 fixed = buf; 3800 r = fn(fixed, &size); 3801 if (r != ERROR_SUCCESS) { 3802 log(EVDNS_LOG_DEBUG, "fn() failed."); 3803 status = -1; 3804 goto done; 3805 } 3806 } 3807 3808 EVUTIL_ASSERT(fixed); 3809 added_any = 0; 3810 ns = &(fixed->DnsServerList); 3811 while (ns) { 3812 r = evdns_nameserver_ip_add_line(base, ns->IpAddress.String); 3813 if (r) { 3814 log(EVDNS_LOG_DEBUG,"Could not add nameserver %s to list,error: %d", 3815 (ns->IpAddress.String),(int)GetLastError()); 3816 status = r; 3817 } else { 3818 ++added_any; 3819 log(EVDNS_LOG_DEBUG,"Successfully added %s as nameserver",ns->IpAddress.String); 3820 } 3821 3822 ns = ns->Next; 3823 } 3824 3825 if (!added_any) { 3826 log(EVDNS_LOG_DEBUG, "No nameservers added."); 3827 if (status == 0) 3828 status = -1; 3829 } else { 3830 status = 0; 3831 } 3832 3833 done: 3834 if (buf) 3835 mm_free(buf); 3836 if (handle) 3837 FreeLibrary(handle); 3838 return status; 3839 } 3840 3841 static int 3842 config_nameserver_from_reg_key(struct evdns_base *base, HKEY key, const TCHAR *subkey) 3843 { 3844 char *buf; 3845 DWORD bufsz = 0, type = 0; 3846 int status = 0; 3847 3848 ASSERT_LOCKED(base); 3849 if (RegQueryValueEx(key, subkey, 0, &type, NULL, &bufsz) 3850 != ERROR_MORE_DATA) 3851 return -1; 3852 if (!(buf = mm_malloc(bufsz))) 3853 return -1; 3854 3855 if (RegQueryValueEx(key, subkey, 0, &type, (LPBYTE)buf, &bufsz) 3856 == ERROR_SUCCESS && bufsz > 1) { 3857 status = evdns_nameserver_ip_add_line(base,buf); 3858 } 3859 3860 mm_free(buf); 3861 return status; 3862 } 3863 3864 #define SERVICES_KEY TEXT("System\\CurrentControlSet\\Services\\") 3865 #define WIN_NS_9X_KEY SERVICES_KEY TEXT("VxD\\MSTCP") 3866 #define WIN_NS_NT_KEY SERVICES_KEY TEXT("Tcpip\\Parameters") 3867 3868 static int 3869 load_nameservers_from_registry(struct evdns_base *base) 3870 { 3871 int found = 0; 3872 int r; 3873 #define TRY(k, name) \ 3874 if (!found && config_nameserver_from_reg_key(base,k,TEXT(name)) == 0) { \ 3875 log(EVDNS_LOG_DEBUG,"Found nameservers in %s/%s",#k,name); \ 3876 found = 1; \ 3877 } else if (!found) { \ 3878 log(EVDNS_LOG_DEBUG,"Didn't find nameservers in %s/%s", \ 3879 #k,#name); \ 3880 } 3881 3882 ASSERT_LOCKED(base); 3883 3884 if (((int)GetVersion()) > 0) { /* NT */ 3885 HKEY nt_key = 0, interfaces_key = 0; 3886 3887 if (RegOpenKeyEx(HKEY_LOCAL_MACHINE, WIN_NS_NT_KEY, 0, 3888 KEY_READ, &nt_key) != ERROR_SUCCESS) { 3889 log(EVDNS_LOG_DEBUG,"Couldn't open nt key, %d",(int)GetLastError()); 3890 return -1; 3891 } 3892 r = RegOpenKeyEx(nt_key, TEXT("Interfaces"), 0, 3893 KEY_QUERY_VALUE|KEY_ENUMERATE_SUB_KEYS, 3894 &interfaces_key); 3895 if (r != ERROR_SUCCESS) { 3896 log(EVDNS_LOG_DEBUG,"Couldn't open interfaces key, %d",(int)GetLastError()); 3897 return -1; 3898 } 3899 TRY(nt_key, "NameServer"); 3900 TRY(nt_key, "DhcpNameServer"); 3901 TRY(interfaces_key, "NameServer"); 3902 TRY(interfaces_key, "DhcpNameServer"); 3903 RegCloseKey(interfaces_key); 3904 RegCloseKey(nt_key); 3905 } else { 3906 HKEY win_key = 0; 3907 if (RegOpenKeyEx(HKEY_LOCAL_MACHINE, WIN_NS_9X_KEY, 0, 3908 KEY_READ, &win_key) != ERROR_SUCCESS) { 3909 log(EVDNS_LOG_DEBUG, "Couldn't open registry key, %d", (int)GetLastError()); 3910 return -1; 3911 } 3912 TRY(win_key, "NameServer"); 3913 RegCloseKey(win_key); 3914 } 3915 3916 if (found == 0) { 3917 log(EVDNS_LOG_WARN,"Didn't find any nameservers."); 3918 } 3919 3920 return found ? 0 : -1; 3921 #undef TRY 3922 } 3923 3924 int 3925 evdns_base_config_windows_nameservers(struct evdns_base *base) 3926 { 3927 int r; 3928 char *fname; 3929 if (base == NULL) 3930 base = current_base; 3931 if (base == NULL) 3932 return -1; 3933 EVDNS_LOCK(base); 3934 fname = evdns_get_default_hosts_filename(); 3935 log(EVDNS_LOG_DEBUG, "Loading hosts entries from %s", fname); 3936 evdns_base_load_hosts(base, fname); 3937 if (fname) 3938 mm_free(fname); 3939 3940 if (load_nameservers_with_getnetworkparams(base) == 0) { 3941 EVDNS_UNLOCK(base); 3942 return 0; 3943 } 3944 r = load_nameservers_from_registry(base); 3945 3946 EVDNS_UNLOCK(base); 3947 return r; 3948 } 3949 3950 int 3951 evdns_config_windows_nameservers(void) 3952 { 3953 if (!current_base) { 3954 current_base = evdns_base_new(NULL, 1); 3955 return current_base == NULL ? -1 : 0; 3956 } else { 3957 return evdns_base_config_windows_nameservers(current_base); 3958 } 3959 } 3960 #endif 3961 3962 struct evdns_base * 3963 evdns_base_new(struct event_base *event_base, int flags) 3964 { 3965 struct evdns_base *base; 3966 3967 if (evutil_secure_rng_init() < 0) { 3968 log(EVDNS_LOG_WARN, "Unable to seed random number generator; " 3969 "DNS can't run."); 3970 return NULL; 3971 } 3972 3973 /* Give the evutil library a hook into its evdns-enabled 3974 * functionality. We can't just call evdns_getaddrinfo directly or 3975 * else libevent-core will depend on libevent-extras. */ 3976 evutil_set_evdns_getaddrinfo_fn_(evdns_getaddrinfo); 3977 evutil_set_evdns_getaddrinfo_cancel_fn_(evdns_getaddrinfo_cancel); 3978 3979 base = mm_malloc(sizeof(struct evdns_base)); 3980 if (base == NULL) 3981 return (NULL); 3982 memset(base, 0, sizeof(struct evdns_base)); 3983 base->req_waiting_head = NULL; 3984 3985 EVTHREAD_ALLOC_LOCK(base->lock, EVTHREAD_LOCKTYPE_RECURSIVE); 3986 EVDNS_LOCK(base); 3987 3988 /* Set max requests inflight and allocate req_heads. */ 3989 base->req_heads = NULL; 3990 3991 evdns_base_set_max_requests_inflight(base, 64); 3992 3993 base->server_head = NULL; 3994 base->event_base = event_base; 3995 base->global_good_nameservers = base->global_requests_inflight = 3996 base->global_requests_waiting = 0; 3997 3998 base->global_timeout.tv_sec = 5; 3999 base->global_timeout.tv_usec = 0; 4000 base->global_max_reissues = 1; 4001 base->global_max_retransmits = 3; 4002 base->global_max_nameserver_timeout = 3; 4003 base->global_search_state = NULL; 4004 base->global_randomize_case = 1; 4005 base->global_getaddrinfo_allow_skew.tv_sec = 3; 4006 base->global_getaddrinfo_allow_skew.tv_usec = 0; 4007 base->global_nameserver_probe_initial_timeout.tv_sec = 10; 4008 base->global_nameserver_probe_initial_timeout.tv_usec = 0; 4009 4010 TAILQ_INIT(&base->hostsdb); 4011 4012 #define EVDNS_BASE_ALL_FLAGS ( \ 4013 EVDNS_BASE_INITIALIZE_NAMESERVERS | \ 4014 EVDNS_BASE_DISABLE_WHEN_INACTIVE | \ 4015 EVDNS_BASE_NAMESERVERS_NO_DEFAULT | \ 4016 0) 4017 4018 if (flags & ~EVDNS_BASE_ALL_FLAGS) { 4019 flags = EVDNS_BASE_INITIALIZE_NAMESERVERS; 4020 log(EVDNS_LOG_WARN, 4021 "Unrecognized flag passed to evdns_base_new(). Assuming " 4022 "you meant EVDNS_BASE_INITIALIZE_NAMESERVERS."); 4023 } 4024 #undef EVDNS_BASE_ALL_FLAGS 4025 4026 if (flags & EVDNS_BASE_INITIALIZE_NAMESERVERS) { 4027 int r; 4028 int opts = DNS_OPTIONS_ALL; 4029 if (flags & EVDNS_BASE_NAMESERVERS_NO_DEFAULT) { 4030 opts |= DNS_OPTION_NAMESERVERS_NO_DEFAULT; 4031 } 4032 4033 #ifdef _WIN32 4034 r = evdns_base_config_windows_nameservers(base); 4035 #else 4036 r = evdns_base_resolv_conf_parse(base, opts, "/etc/resolv.conf"); 4037 #endif 4038 if (r) { 4039 evdns_base_free_and_unlock(base, 0); 4040 return NULL; 4041 } 4042 } 4043 if (flags & EVDNS_BASE_DISABLE_WHEN_INACTIVE) { 4044 base->disable_when_inactive = 1; 4045 } 4046 4047 EVDNS_UNLOCK(base); 4048 return base; 4049 } 4050 4051 int 4052 evdns_init(void) 4053 { 4054 struct evdns_base *base = evdns_base_new(NULL, 1); 4055 if (base) { 4056 current_base = base; 4057 return 0; 4058 } else { 4059 return -1; 4060 } 4061 } 4062 4063 const char * 4064 evdns_err_to_string(int err) 4065 { 4066 switch (err) { 4067 case DNS_ERR_NONE: return "no error"; 4068 case DNS_ERR_FORMAT: return "misformatted query"; 4069 case DNS_ERR_SERVERFAILED: return "server failed"; 4070 case DNS_ERR_NOTEXIST: return "name does not exist"; 4071 case DNS_ERR_NOTIMPL: return "query not implemented"; 4072 case DNS_ERR_REFUSED: return "refused"; 4073 4074 case DNS_ERR_TRUNCATED: return "reply truncated or ill-formed"; 4075 case DNS_ERR_UNKNOWN: return "unknown"; 4076 case DNS_ERR_TIMEOUT: return "request timed out"; 4077 case DNS_ERR_SHUTDOWN: return "dns subsystem shut down"; 4078 case DNS_ERR_CANCEL: return "dns request canceled"; 4079 case DNS_ERR_NODATA: return "no records in the reply"; 4080 default: return "[Unknown error code]"; 4081 } 4082 } 4083 4084 static void 4085 evdns_nameserver_free(struct nameserver *server) 4086 { 4087 if (server->socket >= 0) 4088 evutil_closesocket(server->socket); 4089 (void) event_del(&server->event); 4090 event_debug_unassign(&server->event); 4091 if (server->state == 0) 4092 (void) event_del(&server->timeout_event); 4093 if (server->probe_request) { 4094 evdns_cancel_request(server->base, server->probe_request); 4095 server->probe_request = NULL; 4096 } 4097 event_debug_unassign(&server->timeout_event); 4098 mm_free(server); 4099 } 4100 4101 static void 4102 evdns_base_free_and_unlock(struct evdns_base *base, int fail_requests) 4103 { 4104 struct nameserver *server, *server_next; 4105 struct search_domain *dom, *dom_next; 4106 int i; 4107 4108 /* Requires that we hold the lock. */ 4109 4110 /* TODO(nickm) we might need to refcount here. */ 4111 4112 while (base->req_waiting_head) { 4113 if (fail_requests) 4114 reply_schedule_callback(base->req_waiting_head, 0, DNS_ERR_SHUTDOWN, NULL); 4115 request_finished(base->req_waiting_head, &base->req_waiting_head, 1); 4116 } 4117 for (i = 0; i < base->n_req_heads; ++i) { 4118 while (base->req_heads[i]) { 4119 if (fail_requests) 4120 reply_schedule_callback(base->req_heads[i], 0, DNS_ERR_SHUTDOWN, NULL); 4121 request_finished(base->req_heads[i], &REQ_HEAD(base, base->req_heads[i]->trans_id), 1); 4122 } 4123 } 4124 base->global_requests_inflight = base->global_requests_waiting = 0; 4125 4126 for (server = base->server_head; server; server = server_next) { 4127 server_next = server->next; 4128 /** already done something before */ 4129 server->probe_request = NULL; 4130 evdns_nameserver_free(server); 4131 if (server_next == base->server_head) 4132 break; 4133 } 4134 base->server_head = NULL; 4135 base->global_good_nameservers = 0; 4136 4137 if (base->global_search_state) { 4138 for (dom = base->global_search_state->head; dom; dom = dom_next) { 4139 dom_next = dom->next; 4140 mm_free(dom); 4141 } 4142 mm_free(base->global_search_state); 4143 base->global_search_state = NULL; 4144 } 4145 4146 { 4147 struct hosts_entry *victim; 4148 while ((victim = TAILQ_FIRST(&base->hostsdb))) { 4149 TAILQ_REMOVE(&base->hostsdb, victim, next); 4150 mm_free(victim); 4151 } 4152 } 4153 4154 mm_free(base->req_heads); 4155 4156 EVDNS_UNLOCK(base); 4157 EVTHREAD_FREE_LOCK(base->lock, EVTHREAD_LOCKTYPE_RECURSIVE); 4158 4159 mm_free(base); 4160 } 4161 4162 void 4163 evdns_base_free(struct evdns_base *base, int fail_requests) 4164 { 4165 EVDNS_LOCK(base); 4166 evdns_base_free_and_unlock(base, fail_requests); 4167 } 4168 4169 void 4170 evdns_base_clear_host_addresses(struct evdns_base *base) 4171 { 4172 struct hosts_entry *victim; 4173 EVDNS_LOCK(base); 4174 while ((victim = TAILQ_FIRST(&base->hostsdb))) { 4175 TAILQ_REMOVE(&base->hostsdb, victim, next); 4176 mm_free(victim); 4177 } 4178 EVDNS_UNLOCK(base); 4179 } 4180 4181 void 4182 evdns_shutdown(int fail_requests) 4183 { 4184 if (current_base) { 4185 struct evdns_base *b = current_base; 4186 current_base = NULL; 4187 evdns_base_free(b, fail_requests); 4188 } 4189 evdns_log_fn = NULL; 4190 } 4191 4192 static int 4193 evdns_base_parse_hosts_line(struct evdns_base *base, char *line) 4194 { 4195 char *strtok_state; 4196 static const char *const delims = " \t"; 4197 char *const addr = strtok_r(line, delims, &strtok_state); 4198 char *hostname, *hash; 4199 struct sockaddr_storage ss; 4200 int socklen = sizeof(ss); 4201 ASSERT_LOCKED(base); 4202 4203 #define NEXT_TOKEN strtok_r(NULL, delims, &strtok_state) 4204 4205 if (!addr || *addr == '#') 4206 return 0; 4207 4208 memset(&ss, 0, sizeof(ss)); 4209 if (evutil_parse_sockaddr_port(addr, (struct sockaddr*)&ss, &socklen)<0) 4210 return -1; 4211 if (socklen > (int)sizeof(struct sockaddr_in6)) 4212 return -1; 4213 4214 if (sockaddr_getport((struct sockaddr*)&ss)) 4215 return -1; 4216 4217 while ((hostname = NEXT_TOKEN)) { 4218 struct hosts_entry *he; 4219 size_t namelen; 4220 if ((hash = strchr(hostname, '#'))) { 4221 if (hash == hostname) 4222 return 0; 4223 *hash = '\0'; 4224 } 4225 4226 namelen = strlen(hostname); 4227 4228 he = mm_calloc(1, sizeof(struct hosts_entry)+namelen); 4229 if (!he) 4230 return -1; 4231 EVUTIL_ASSERT(socklen <= (int)sizeof(he->addr)); 4232 memcpy(&he->addr, &ss, socklen); 4233 memcpy(he->hostname, hostname, namelen+1); 4234 he->addrlen = socklen; 4235 4236 TAILQ_INSERT_TAIL(&base->hostsdb, he, next); 4237 4238 if (hash) 4239 return 0; 4240 } 4241 4242 return 0; 4243 #undef NEXT_TOKEN 4244 } 4245 4246 static int 4247 evdns_base_load_hosts_impl(struct evdns_base *base, const char *hosts_fname) 4248 { 4249 char *str=NULL, *cp, *eol; 4250 size_t len; 4251 int err=0; 4252 4253 ASSERT_LOCKED(base); 4254 4255 if (hosts_fname == NULL || 4256 (err = evutil_read_file_(hosts_fname, &str, &len, 0)) < 0) { 4257 char tmp[64]; 4258 strlcpy(tmp, "127.0.0.1 localhost", sizeof(tmp)); 4259 evdns_base_parse_hosts_line(base, tmp); 4260 strlcpy(tmp, "::1 localhost", sizeof(tmp)); 4261 evdns_base_parse_hosts_line(base, tmp); 4262 return err ? -1 : 0; 4263 } 4264 4265 /* This will break early if there is a NUL in the hosts file. 4266 * Probably not a problem.*/ 4267 cp = str; 4268 for (;;) { 4269 eol = strchr(cp, '\n'); 4270 4271 if (eol) { 4272 *eol = '\0'; 4273 evdns_base_parse_hosts_line(base, cp); 4274 cp = eol+1; 4275 } else { 4276 evdns_base_parse_hosts_line(base, cp); 4277 break; 4278 } 4279 } 4280 4281 mm_free(str); 4282 return 0; 4283 } 4284 4285 int 4286 evdns_base_load_hosts(struct evdns_base *base, const char *hosts_fname) 4287 { 4288 int res; 4289 if (!base) 4290 base = current_base; 4291 EVDNS_LOCK(base); 4292 res = evdns_base_load_hosts_impl(base, hosts_fname); 4293 EVDNS_UNLOCK(base); 4294 return res; 4295 } 4296 4297 /* A single request for a getaddrinfo, either v4 or v6. */ 4298 struct getaddrinfo_subrequest { 4299 struct evdns_request *r; 4300 ev_uint32_t type; 4301 }; 4302 4303 /* State data used to implement an in-progress getaddrinfo. */ 4304 struct evdns_getaddrinfo_request { 4305 struct evdns_base *evdns_base; 4306 /* Copy of the modified 'hints' data that we'll use to build 4307 * answers. */ 4308 struct evutil_addrinfo hints; 4309 /* The callback to invoke when we're done */ 4310 evdns_getaddrinfo_cb user_cb; 4311 /* User-supplied data to give to the callback. */ 4312 void *user_data; 4313 /* The port to use when building sockaddrs. */ 4314 ev_uint16_t port; 4315 /* The sub_request for an A record (if any) */ 4316 struct getaddrinfo_subrequest ipv4_request; 4317 /* The sub_request for an AAAA record (if any) */ 4318 struct getaddrinfo_subrequest ipv6_request; 4319 4320 /* The cname result that we were told (if any) */ 4321 char *cname_result; 4322 4323 /* If we have one request answered and one request still inflight, 4324 * then this field holds the answer from the first request... */ 4325 struct evutil_addrinfo *pending_result; 4326 /* And this event is a timeout that will tell us to cancel the second 4327 * request if it's taking a long time. */ 4328 struct event timeout; 4329 4330 /* And this field holds the error code from the first request... */ 4331 int pending_error; 4332 /* If this is set, the user canceled this request. */ 4333 unsigned user_canceled : 1; 4334 /* If this is set, the user can no longer cancel this request; we're 4335 * just waiting for the free. */ 4336 unsigned request_done : 1; 4337 }; 4338 4339 /* Convert an evdns errors to the equivalent getaddrinfo error. */ 4340 static int 4341 evdns_err_to_getaddrinfo_err(int e1) 4342 { 4343 /* XXX Do this better! */ 4344 if (e1 == DNS_ERR_NONE) 4345 return 0; 4346 else if (e1 == DNS_ERR_NOTEXIST) 4347 return EVUTIL_EAI_NONAME; 4348 else 4349 return EVUTIL_EAI_FAIL; 4350 } 4351 4352 /* Return the more informative of two getaddrinfo errors. */ 4353 static int 4354 getaddrinfo_merge_err(int e1, int e2) 4355 { 4356 /* XXXX be cleverer here. */ 4357 if (e1 == 0) 4358 return e2; 4359 else 4360 return e1; 4361 } 4362 4363 static void 4364 free_getaddrinfo_request(struct evdns_getaddrinfo_request *data) 4365 { 4366 /* DO NOT CALL this if either of the requests is pending. Only once 4367 * both callbacks have been invoked is it safe to free the request */ 4368 if (data->pending_result) 4369 evutil_freeaddrinfo(data->pending_result); 4370 if (data->cname_result) 4371 mm_free(data->cname_result); 4372 event_del(&data->timeout); 4373 mm_free(data); 4374 return; 4375 } 4376 4377 static void 4378 add_cname_to_reply(struct evdns_getaddrinfo_request *data, 4379 struct evutil_addrinfo *ai) 4380 { 4381 if (data->cname_result && ai) { 4382 ai->ai_canonname = data->cname_result; 4383 data->cname_result = NULL; 4384 } 4385 } 4386 4387 /* Callback: invoked when one request in a mixed-format A/AAAA getaddrinfo 4388 * request has finished, but the other one took too long to answer. Pass 4389 * along the answer we got, and cancel the other request. 4390 */ 4391 static void 4392 evdns_getaddrinfo_timeout_cb(evutil_socket_t fd, short what, void *ptr) 4393 { 4394 int v4_timedout = 0, v6_timedout = 0; 4395 struct evdns_getaddrinfo_request *data = ptr; 4396 4397 /* Cancel any pending requests, and note which one */ 4398 if (data->ipv4_request.r) { 4399 /* XXXX This does nothing if the request's callback is already 4400 * running (pending_cb is set). */ 4401 evdns_cancel_request(NULL, data->ipv4_request.r); 4402 v4_timedout = 1; 4403 EVDNS_LOCK(data->evdns_base); 4404 ++data->evdns_base->getaddrinfo_ipv4_timeouts; 4405 EVDNS_UNLOCK(data->evdns_base); 4406 } 4407 if (data->ipv6_request.r) { 4408 /* XXXX This does nothing if the request's callback is already 4409 * running (pending_cb is set). */ 4410 evdns_cancel_request(NULL, data->ipv6_request.r); 4411 v6_timedout = 1; 4412 EVDNS_LOCK(data->evdns_base); 4413 ++data->evdns_base->getaddrinfo_ipv6_timeouts; 4414 EVDNS_UNLOCK(data->evdns_base); 4415 } 4416 4417 /* We only use this timeout callback when we have an answer for 4418 * one address. */ 4419 EVUTIL_ASSERT(!v4_timedout || !v6_timedout); 4420 4421 /* Report the outcome of the other request that didn't time out. */ 4422 if (data->pending_result) { 4423 add_cname_to_reply(data, data->pending_result); 4424 data->user_cb(0, data->pending_result, data->user_data); 4425 data->pending_result = NULL; 4426 } else { 4427 int e = data->pending_error; 4428 if (!e) 4429 e = EVUTIL_EAI_AGAIN; 4430 data->user_cb(e, NULL, data->user_data); 4431 } 4432 4433 data->user_cb = NULL; /* prevent double-call if evdns callbacks are 4434 * in-progress. XXXX It would be better if this 4435 * weren't necessary. */ 4436 4437 if (!v4_timedout && !v6_timedout) { 4438 /* should be impossible? XXXX */ 4439 free_getaddrinfo_request(data); 4440 } 4441 } 4442 4443 static int 4444 evdns_getaddrinfo_set_timeout(struct evdns_base *evdns_base, 4445 struct evdns_getaddrinfo_request *data) 4446 { 4447 return event_add(&data->timeout, &evdns_base->global_getaddrinfo_allow_skew); 4448 } 4449 4450 static inline int 4451 evdns_result_is_answer(int result) 4452 { 4453 return (result != DNS_ERR_NOTIMPL && result != DNS_ERR_REFUSED && 4454 result != DNS_ERR_SERVERFAILED && result != DNS_ERR_CANCEL); 4455 } 4456 4457 static void 4458 evdns_getaddrinfo_gotresolve(int result, char type, int count, 4459 int ttl, void *addresses, void *arg) 4460 { 4461 int i; 4462 struct getaddrinfo_subrequest *req = arg; 4463 struct getaddrinfo_subrequest *other_req; 4464 struct evdns_getaddrinfo_request *data; 4465 4466 struct evutil_addrinfo *res; 4467 4468 struct sockaddr_in sin; 4469 struct sockaddr_in6 sin6; 4470 struct sockaddr *sa; 4471 int socklen, addrlen; 4472 void *addrp; 4473 int err; 4474 int user_canceled; 4475 4476 EVUTIL_ASSERT(req->type == DNS_IPv4_A || req->type == DNS_IPv6_AAAA); 4477 if (req->type == DNS_IPv4_A) { 4478 data = EVUTIL_UPCAST(req, struct evdns_getaddrinfo_request, ipv4_request); 4479 other_req = &data->ipv6_request; 4480 } else { 4481 data = EVUTIL_UPCAST(req, struct evdns_getaddrinfo_request, ipv6_request); 4482 other_req = &data->ipv4_request; 4483 } 4484 4485 /** Called from evdns_base_free() with @fail_requests == 1 */ 4486 if (result != DNS_ERR_SHUTDOWN) { 4487 EVDNS_LOCK(data->evdns_base); 4488 if (evdns_result_is_answer(result)) { 4489 if (req->type == DNS_IPv4_A) 4490 ++data->evdns_base->getaddrinfo_ipv4_answered; 4491 else 4492 ++data->evdns_base->getaddrinfo_ipv6_answered; 4493 } 4494 user_canceled = data->user_canceled; 4495 if (other_req->r == NULL) 4496 data->request_done = 1; 4497 EVDNS_UNLOCK(data->evdns_base); 4498 } else { 4499 data->evdns_base = NULL; 4500 user_canceled = data->user_canceled; 4501 } 4502 4503 req->r = NULL; 4504 4505 if (result == DNS_ERR_CANCEL && ! user_canceled) { 4506 /* Internal cancel request from timeout or internal error. 4507 * we already answered the user. */ 4508 if (other_req->r == NULL) 4509 free_getaddrinfo_request(data); 4510 return; 4511 } 4512 4513 if (data->user_cb == NULL) { 4514 /* We already answered. XXXX This shouldn't be needed; see 4515 * comments in evdns_getaddrinfo_timeout_cb */ 4516 free_getaddrinfo_request(data); 4517 return; 4518 } 4519 4520 if (result == DNS_ERR_NONE) { 4521 if (count == 0) 4522 err = EVUTIL_EAI_NODATA; 4523 else 4524 err = 0; 4525 } else { 4526 err = evdns_err_to_getaddrinfo_err(result); 4527 } 4528 4529 if (err) { 4530 /* Looks like we got an error. */ 4531 if (other_req->r) { 4532 /* The other request is still working; maybe it will 4533 * succeed. */ 4534 /* XXXX handle failure from set_timeout */ 4535 if (result != DNS_ERR_SHUTDOWN) { 4536 evdns_getaddrinfo_set_timeout(data->evdns_base, data); 4537 } 4538 data->pending_error = err; 4539 return; 4540 } 4541 4542 if (user_canceled) { 4543 data->user_cb(EVUTIL_EAI_CANCEL, NULL, data->user_data); 4544 } else if (data->pending_result) { 4545 /* If we have an answer waiting, and we weren't 4546 * canceled, ignore this error. */ 4547 add_cname_to_reply(data, data->pending_result); 4548 data->user_cb(0, data->pending_result, data->user_data); 4549 data->pending_result = NULL; 4550 } else { 4551 if (data->pending_error) 4552 err = getaddrinfo_merge_err(err, 4553 data->pending_error); 4554 data->user_cb(err, NULL, data->user_data); 4555 } 4556 free_getaddrinfo_request(data); 4557 return; 4558 } else if (user_canceled) { 4559 if (other_req->r) { 4560 /* The other request is still working; let it hit this 4561 * callback with EVUTIL_EAI_CANCEL callback and report 4562 * the failure. */ 4563 return; 4564 } 4565 data->user_cb(EVUTIL_EAI_CANCEL, NULL, data->user_data); 4566 free_getaddrinfo_request(data); 4567 return; 4568 } 4569 4570 /* Looks like we got some answers. We should turn them into addrinfos 4571 * and then either queue those or return them all. */ 4572 EVUTIL_ASSERT(type == DNS_IPv4_A || type == DNS_IPv6_AAAA); 4573 4574 if (type == DNS_IPv4_A) { 4575 memset(&sin, 0, sizeof(sin)); 4576 sin.sin_family = AF_INET; 4577 sin.sin_port = htons(data->port); 4578 4579 sa = (struct sockaddr *)&sin; 4580 socklen = sizeof(sin); 4581 addrlen = 4; 4582 addrp = &sin.sin_addr.s_addr; 4583 } else { 4584 memset(&sin6, 0, sizeof(sin6)); 4585 sin6.sin6_family = AF_INET6; 4586 sin6.sin6_port = htons(data->port); 4587 4588 sa = (struct sockaddr *)&sin6; 4589 socklen = sizeof(sin6); 4590 addrlen = 16; 4591 addrp = &sin6.sin6_addr.s6_addr; 4592 } 4593 4594 res = NULL; 4595 for (i=0; i < count; ++i) { 4596 struct evutil_addrinfo *ai; 4597 memcpy(addrp, ((char*)addresses)+i*addrlen, addrlen); 4598 ai = evutil_new_addrinfo_(sa, socklen, &data->hints); 4599 if (!ai) { 4600 if (other_req->r) { 4601 evdns_cancel_request(NULL, other_req->r); 4602 } 4603 data->user_cb(EVUTIL_EAI_MEMORY, NULL, data->user_data); 4604 if (res) 4605 evutil_freeaddrinfo(res); 4606 4607 if (other_req->r == NULL) 4608 free_getaddrinfo_request(data); 4609 return; 4610 } 4611 res = evutil_addrinfo_append_(res, ai); 4612 } 4613 4614 if (other_req->r) { 4615 /* The other request is still in progress; wait for it */ 4616 /* XXXX handle failure from set_timeout */ 4617 evdns_getaddrinfo_set_timeout(data->evdns_base, data); 4618 data->pending_result = res; 4619 return; 4620 } else { 4621 /* The other request is done or never started; append its 4622 * results (if any) and return them. */ 4623 if (data->pending_result) { 4624 if (req->type == DNS_IPv4_A) 4625 res = evutil_addrinfo_append_(res, 4626 data->pending_result); 4627 else 4628 res = evutil_addrinfo_append_( 4629 data->pending_result, res); 4630 data->pending_result = NULL; 4631 } 4632 4633 /* Call the user callback. */ 4634 add_cname_to_reply(data, res); 4635 data->user_cb(0, res, data->user_data); 4636 4637 /* Free data. */ 4638 free_getaddrinfo_request(data); 4639 } 4640 } 4641 4642 static struct hosts_entry * 4643 find_hosts_entry(struct evdns_base *base, const char *hostname, 4644 struct hosts_entry *find_after) 4645 { 4646 struct hosts_entry *e; 4647 4648 if (find_after) 4649 e = TAILQ_NEXT(find_after, next); 4650 else 4651 e = TAILQ_FIRST(&base->hostsdb); 4652 4653 for (; e; e = TAILQ_NEXT(e, next)) { 4654 if (!evutil_ascii_strcasecmp(e->hostname, hostname)) 4655 return e; 4656 } 4657 return NULL; 4658 } 4659 4660 static int 4661 evdns_getaddrinfo_fromhosts(struct evdns_base *base, 4662 const char *nodename, struct evutil_addrinfo *hints, ev_uint16_t port, 4663 struct evutil_addrinfo **res) 4664 { 4665 int n_found = 0; 4666 struct hosts_entry *e; 4667 struct evutil_addrinfo *ai=NULL; 4668 int f = hints->ai_family; 4669 4670 EVDNS_LOCK(base); 4671 for (e = find_hosts_entry(base, nodename, NULL); e; 4672 e = find_hosts_entry(base, nodename, e)) { 4673 struct evutil_addrinfo *ai_new; 4674 ++n_found; 4675 if ((e->addr.sa.sa_family == AF_INET && f == PF_INET6) || 4676 (e->addr.sa.sa_family == AF_INET6 && f == PF_INET)) 4677 continue; 4678 ai_new = evutil_new_addrinfo_(&e->addr.sa, e->addrlen, hints); 4679 if (!ai_new) { 4680 n_found = 0; 4681 goto out; 4682 } 4683 sockaddr_setport(ai_new->ai_addr, port); 4684 ai = evutil_addrinfo_append_(ai, ai_new); 4685 } 4686 EVDNS_UNLOCK(base); 4687 out: 4688 if (n_found) { 4689 /* Note that we return an empty answer if we found entries for 4690 * this hostname but none were of the right address type. */ 4691 *res = ai; 4692 return 0; 4693 } else { 4694 if (ai) 4695 evutil_freeaddrinfo(ai); 4696 return -1; 4697 } 4698 } 4699 4700 struct evdns_getaddrinfo_request * 4701 evdns_getaddrinfo(struct evdns_base *dns_base, 4702 const char *nodename, const char *servname, 4703 const struct evutil_addrinfo *hints_in, 4704 evdns_getaddrinfo_cb cb, void *arg) 4705 { 4706 struct evdns_getaddrinfo_request *data; 4707 struct evutil_addrinfo hints; 4708 struct evutil_addrinfo *res = NULL; 4709 int err; 4710 int port = 0; 4711 int want_cname = 0; 4712 int started = 0; 4713 4714 if (!dns_base) { 4715 dns_base = current_base; 4716 if (!dns_base) { 4717 log(EVDNS_LOG_WARN, 4718 "Call to getaddrinfo_async with no " 4719 "evdns_base configured."); 4720 cb(EVUTIL_EAI_FAIL, NULL, arg); /* ??? better error? */ 4721 return NULL; 4722 } 4723 } 4724 4725 /* If we _must_ answer this immediately, do so. */ 4726 if ((hints_in && (hints_in->ai_flags & EVUTIL_AI_NUMERICHOST))) { 4727 res = NULL; 4728 err = evutil_getaddrinfo(nodename, servname, hints_in, &res); 4729 cb(err, res, arg); 4730 return NULL; 4731 } 4732 4733 if (hints_in) { 4734 memcpy(&hints, hints_in, sizeof(hints)); 4735 } else { 4736 memset(&hints, 0, sizeof(hints)); 4737 hints.ai_family = PF_UNSPEC; 4738 } 4739 4740 evutil_adjust_hints_for_addrconfig_(&hints); 4741 4742 /* Now try to see if we _can_ answer immediately. */ 4743 /* (It would be nice to do this by calling getaddrinfo directly, with 4744 * AI_NUMERICHOST, on plaforms that have it, but we can't: there isn't 4745 * a reliable way to distinguish the "that wasn't a numeric host!" case 4746 * from any other EAI_NONAME cases.) */ 4747 err = evutil_getaddrinfo_common_(nodename, servname, &hints, &res, &port); 4748 if (err != EVUTIL_EAI_NEED_RESOLVE) { 4749 cb(err, res, arg); 4750 return NULL; 4751 } 4752 4753 /* If there is an entry in the hosts file, we should give it now. */ 4754 if (!evdns_getaddrinfo_fromhosts(dns_base, nodename, &hints, port, &res)) { 4755 cb(0, res, arg); 4756 return NULL; 4757 } 4758 4759 /* Okay, things are serious now. We're going to need to actually 4760 * launch a request. 4761 */ 4762 data = mm_calloc(1,sizeof(struct evdns_getaddrinfo_request)); 4763 if (!data) { 4764 cb(EVUTIL_EAI_MEMORY, NULL, arg); 4765 return NULL; 4766 } 4767 4768 memcpy(&data->hints, &hints, sizeof(data->hints)); 4769 data->port = (ev_uint16_t)port; 4770 data->ipv4_request.type = DNS_IPv4_A; 4771 data->ipv6_request.type = DNS_IPv6_AAAA; 4772 data->user_cb = cb; 4773 data->user_data = arg; 4774 data->evdns_base = dns_base; 4775 4776 want_cname = (hints.ai_flags & EVUTIL_AI_CANONNAME); 4777 4778 /* If we are asked for a PF_UNSPEC address, we launch two requests in 4779 * parallel: one for an A address and one for an AAAA address. We 4780 * can't send just one request, since many servers only answer one 4781 * question per DNS request. 4782 * 4783 * Once we have the answer to one request, we allow for a short 4784 * timeout before we report it, to see if the other one arrives. If 4785 * they both show up in time, then we report both the answers. 4786 * 4787 * If too many addresses of one type time out or fail, we should stop 4788 * launching those requests. (XXX we don't do that yet.) 4789 */ 4790 4791 EVDNS_LOCK(dns_base); 4792 4793 if (hints.ai_family != PF_INET6) { 4794 log(EVDNS_LOG_DEBUG, "Sending request for %s on ipv4 as %p", 4795 nodename, &data->ipv4_request); 4796 4797 data->ipv4_request.r = evdns_base_resolve_ipv4(dns_base, 4798 nodename, 0, evdns_getaddrinfo_gotresolve, 4799 &data->ipv4_request); 4800 if (want_cname && data->ipv4_request.r) 4801 data->ipv4_request.r->current_req->put_cname_in_ptr = 4802 &data->cname_result; 4803 } 4804 if (hints.ai_family != PF_INET) { 4805 log(EVDNS_LOG_DEBUG, "Sending request for %s on ipv6 as %p", 4806 nodename, &data->ipv6_request); 4807 4808 data->ipv6_request.r = evdns_base_resolve_ipv6(dns_base, 4809 nodename, 0, evdns_getaddrinfo_gotresolve, 4810 &data->ipv6_request); 4811 if (want_cname && data->ipv6_request.r) 4812 data->ipv6_request.r->current_req->put_cname_in_ptr = 4813 &data->cname_result; 4814 } 4815 4816 evtimer_assign(&data->timeout, dns_base->event_base, 4817 evdns_getaddrinfo_timeout_cb, data); 4818 4819 started = (data->ipv4_request.r || data->ipv6_request.r); 4820 4821 EVDNS_UNLOCK(dns_base); 4822 4823 if (started) { 4824 return data; 4825 } else { 4826 mm_free(data); 4827 cb(EVUTIL_EAI_FAIL, NULL, arg); 4828 return NULL; 4829 } 4830 } 4831 4832 void 4833 evdns_getaddrinfo_cancel(struct evdns_getaddrinfo_request *data) 4834 { 4835 EVDNS_LOCK(data->evdns_base); 4836 if (data->request_done) { 4837 EVDNS_UNLOCK(data->evdns_base); 4838 return; 4839 } 4840 event_del(&data->timeout); 4841 data->user_canceled = 1; 4842 if (data->ipv4_request.r) 4843 evdns_cancel_request(data->evdns_base, data->ipv4_request.r); 4844 if (data->ipv6_request.r) 4845 evdns_cancel_request(data->evdns_base, data->ipv6_request.r); 4846 EVDNS_UNLOCK(data->evdns_base); 4847 } 4848