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