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| 1 /* $Id: evdns.c 6979 2006-08-04 18:31:13Z nickm $ */ | |
| 2 | |
| 3 /* The original version of this module was written by Adam Langley; for | |
| 4 * a history of modifications, check out the subversion logs. | |
| 5 * | |
| 6 * When editing this module, try to keep it re-mergeable by Adam. Don't | |
| 7 * reformat the whitespace, add Tor dependencies, or so on. | |
| 8 * | |
| 9 * TODO: | |
| 10 * - Support IPv6 and PTR records. | |
| 11 * - Replace all externally visible magic numbers with #defined constants. | |
| 12 * - Write doccumentation for APIs of all external functions. | |
| 13 */ | |
| 14 | |
| 15 /* Async DNS Library | |
| 16 * Adam Langley <agl@imperialviolet.org> | |
| 17 * http://www.imperialviolet.org/eventdns.html | |
| 18 * Public Domain code | |
| 19 * | |
| 20 * This software is Public Domain. To view a copy of the public domain dedicatio
n, | |
| 21 * visit http://creativecommons.org/licenses/publicdomain/ or send a letter to | |
| 22 * Creative Commons, 559 Nathan Abbott Way, Stanford, California 94305, USA. | |
| 23 * | |
| 24 * I ask and expect, but do not require, that all derivative works contain an | |
| 25 * attribution similar to: | |
| 26 * Parts developed by Adam Langley <agl@imperialviolet.org> | |
| 27 * | |
| 28 * You may wish to replace the word "Parts" with something else depending on | |
| 29 * the amount of original code. | |
| 30 * | |
| 31 * (Derivative works does not include programs which link against, run or includ
e | |
| 32 * the source verbatim in their source distributions) | |
| 33 * | |
| 34 * Version: 0.1b | |
| 35 */ | |
| 36 | |
| 37 #include <sys/types.h> | |
| 38 #ifdef HAVE_CONFIG_H | |
| 39 #include "config.h" | |
| 40 #endif | |
| 41 | |
| 42 #ifdef DNS_USE_FTIME_FOR_ID | |
| 43 #include <sys/timeb.h> | |
| 44 #endif | |
| 45 | |
| 46 #ifndef DNS_USE_CPU_CLOCK_FOR_ID | |
| 47 #ifndef DNS_USE_GETTIMEOFDAY_FOR_ID | |
| 48 #ifndef DNS_USE_OPENSSL_FOR_ID | |
| 49 #ifndef DNS_USE_FTIME_FOR_ID | |
| 50 #error Must configure at least one id generation method. | |
| 51 #error Please see the documentation. | |
| 52 #endif | |
| 53 #endif | |
| 54 #endif | |
| 55 #endif | |
| 56 | |
| 57 /* #define _POSIX_C_SOURCE 200507 */ | |
| 58 #ifndef _GNU_SOURCE | |
| 59 #define _GNU_SOURCE | |
| 60 #endif | |
| 61 | |
| 62 #ifdef DNS_USE_CPU_CLOCK_FOR_ID | |
| 63 #ifdef DNS_USE_OPENSSL_FOR_ID | |
| 64 #error Multiple id options selected | |
| 65 #endif | |
| 66 #ifdef DNS_USE_GETTIMEOFDAY_FOR_ID | |
| 67 #error Multiple id options selected | |
| 68 #endif | |
| 69 #include <time.h> | |
| 70 #endif | |
| 71 | |
| 72 #ifdef DNS_USE_OPENSSL_FOR_ID | |
| 73 #ifdef DNS_USE_GETTIMEOFDAY_FOR_ID | |
| 74 #error Multiple id options selected | |
| 75 #endif | |
| 76 #include <openssl/rand.h> | |
| 77 #endif | |
| 78 | |
| 79 #ifndef _FORTIFY_SOURCE | |
| 80 #define _FORTIFY_SOURCE 3 | |
| 81 #endif | |
| 82 | |
| 83 #include <string.h> | |
| 84 #include <fcntl.h> | |
| 85 #ifdef HAVE_SYS_TIME_H | |
| 86 #include <sys/time.h> | |
| 87 #endif | |
| 88 #ifdef HAVE_STDINT_H | |
| 89 #include <stdint.h> | |
| 90 #endif | |
| 91 #include <stdlib.h> | |
| 92 #include <string.h> | |
| 93 #include <errno.h> | |
| 94 #include <assert.h> | |
| 95 #ifdef HAVE_UNISTD_H | |
| 96 #include <unistd.h> | |
| 97 #endif | |
| 98 #include <limits.h> | |
| 99 #include <sys/stat.h> | |
| 100 #include <ctype.h> | |
| 101 #include <stdio.h> | |
| 102 #include <stdarg.h> | |
| 103 | |
| 104 #include "evdns.h" | |
| 105 #include "evutil.h" | |
| 106 #include "log.h" | |
| 107 #ifdef WIN32 | |
| 108 #include <winsock2.h> | |
| 109 #include <windows.h> | |
| 110 #include <iphlpapi.h> | |
| 111 #include <io.h> | |
| 112 #else | |
| 113 #include <sys/socket.h> | |
| 114 #include <netinet/in.h> | |
| 115 #include <arpa/inet.h> | |
| 116 #endif | |
| 117 | |
| 118 #ifdef HAVE_NETINET_IN6_H | |
| 119 #include <netinet/in6.h> | |
| 120 #endif | |
| 121 | |
| 122 #define EVDNS_LOG_DEBUG 0 | |
| 123 #define EVDNS_LOG_WARN 1 | |
| 124 | |
| 125 #ifndef HOST_NAME_MAX | |
| 126 #define HOST_NAME_MAX 255 | |
| 127 #endif | |
| 128 | |
| 129 #include <stdio.h> | |
| 130 | |
| 131 #undef MIN | |
| 132 #define MIN(a,b) ((a)<(b)?(a):(b)) | |
| 133 | |
| 134 #ifdef __USE_ISOC99B | |
| 135 /* libevent doesn't work without this */ | |
| 136 typedef ev_uint8_t u_char; | |
| 137 typedef unsigned int uint; | |
| 138 #endif | |
| 139 #include "event.h" | |
| 140 | |
| 141 #define u64 ev_uint64_t | |
| 142 #define u32 ev_uint32_t | |
| 143 #define u16 ev_uint16_t | |
| 144 #define u8 ev_uint8_t | |
| 145 | |
| 146 #ifdef WIN32 | |
| 147 #define open _open | |
| 148 #define read _read | |
| 149 #define close _close | |
| 150 #define strdup _strdup | |
| 151 #endif | |
| 152 | |
| 153 #define MAX_ADDRS 32 /* maximum number of addresses from a single packet */ | |
| 154 /* which we bother recording */ | |
| 155 | |
| 156 #define TYPE_A EVDNS_TYPE_A | |
| 157 #define TYPE_CNAME 5 | |
| 158 #define TYPE_PTR EVDNS_TYPE_PTR | |
| 159 #define TYPE_AAAA EVDNS_TYPE_AAAA | |
| 160 | |
| 161 #define CLASS_INET EVDNS_CLASS_INET | |
| 162 | |
| 163 #ifdef HAVE_SETFD | |
| 164 #define FD_CLOSEONEXEC(x) do { \ | |
| 165 if (fcntl(x, F_SETFD, 1) == -1) \ | |
| 166 event_warn("fcntl(%d, F_SETFD)", x); \ | |
| 167 } while (0) | |
| 168 #else | |
| 169 #define FD_CLOSEONEXEC(x) (void)0 | |
| 170 #endif | |
| 171 | |
| 172 struct request { | |
| 173 u8 *request; /* the dns packet data */ | |
| 174 unsigned int request_len; | |
| 175 int reissue_count; | |
| 176 int tx_count; /* the number of times that this packet has been sent */ | |
| 177 unsigned int request_type; /* TYPE_PTR or TYPE_A */ | |
| 178 void *user_pointer; /* the pointer given to us for this request */ | |
| 179 evdns_callback_type user_callback; | |
| 180 struct nameserver *ns; /* the server which we last sent it */ | |
| 181 | |
| 182 /* elements used by the searching code */ | |
| 183 int search_index; | |
| 184 struct search_state *search_state; | |
| 185 char *search_origname; /* needs to be free()ed */ | |
| 186 int search_flags; | |
| 187 | |
| 188 /* these objects are kept in a circular list */ | |
| 189 struct request *next, *prev; | |
| 190 | |
| 191 struct event timeout_event; | |
| 192 | |
| 193 u16 trans_id; /* the transaction id */ | |
| 194 char request_appended; /* true if the request pointer is data which fol
lows this struct */ | |
| 195 char transmit_me; /* needs to be transmitted */ | |
| 196 }; | |
| 197 | |
| 198 #ifndef HAVE_STRUCT_IN6_ADDR | |
| 199 struct in6_addr { | |
| 200 u8 s6_addr[16]; | |
| 201 }; | |
| 202 #endif | |
| 203 | |
| 204 struct reply { | |
| 205 unsigned int type; | |
| 206 unsigned int have_answer; | |
| 207 union { | |
| 208 struct { | |
| 209 u32 addrcount; | |
| 210 u32 addresses[MAX_ADDRS]; | |
| 211 } a; | |
| 212 struct { | |
| 213 u32 addrcount; | |
| 214 struct in6_addr addresses[MAX_ADDRS]; | |
| 215 } aaaa; | |
| 216 struct { | |
| 217 char name[HOST_NAME_MAX]; | |
| 218 } ptr; | |
| 219 } data; | |
| 220 }; | |
| 221 | |
| 222 struct nameserver { | |
| 223 int socket; /* a connected UDP socket */ | |
| 224 u32 address; | |
| 225 u16 port; | |
| 226 int failed_times; /* number of times which we have given this server a
chance */ | |
| 227 int timedout; /* number of times in a row a request has timed out */ | |
| 228 struct event event; | |
| 229 /* these objects are kept in a circular list */ | |
| 230 struct nameserver *next, *prev; | |
| 231 struct event timeout_event; /* used to keep the timeout for */ | |
| 232 /* when we next probe this server. */ | |
| 233 /* Valid if state == 0 */ | |
| 234 char state; /* zero if we think that this server is down */ | |
| 235 char choked; /* true if we have an EAGAIN from this server's socket */ | |
| 236 char write_waiting; /* true if we are waiting for EV_WRITE events */ | |
| 237 }; | |
| 238 | |
| 239 static struct request *req_head = NULL, *req_waiting_head = NULL; | |
| 240 static struct nameserver *server_head = NULL; | |
| 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 int 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 }; | |
| 255 | |
| 256 /* Represents part of a reply being built. (That is, a single RR.) */ | |
| 257 struct server_reply_item { | |
| 258 struct server_reply_item *next; /* next item in sequence. */ | |
| 259 char *name; /* name part of the RR */ | |
| 260 u16 type : 16; /* The RR type */ | |
| 261 u16 class : 16; /* The RR class (usually CLASS_INET) */ | |
| 262 u32 ttl; /* The RR TTL */ | |
| 263 char is_name; /* True iff data is a label */ | |
| 264 u16 datalen; /* Length of data; -1 if data is a label */ | |
| 265 void *data; /* The contents of the RR */ | |
| 266 }; | |
| 267 | |
| 268 /* Represents a request that we've received as a DNS server, and holds */ | |
| 269 /* the components of the reply as we're constructing it. */ | |
| 270 struct server_request { | |
| 271 /* Pointers to the next and previous entries on the list of replies */ | |
| 272 /* that we're waiting to write. Only set if we have tried to respond */ | |
| 273 /* and gotten EAGAIN. */ | |
| 274 struct server_request *next_pending; | |
| 275 struct server_request *prev_pending; | |
| 276 | |
| 277 u16 trans_id; /* Transaction id. */ | |
| 278 struct evdns_server_port *port; /* Which port received this request on?
*/ | |
| 279 struct sockaddr_storage addr; /* Where to send the response */ | |
| 280 socklen_t addrlen; /* length of addr */ | |
| 281 | |
| 282 int n_answer; /* how many answer RRs have been set? */ | |
| 283 int n_authority; /* how many authority RRs have been set? */ | |
| 284 int n_additional; /* how many additional RRs have been set? */ | |
| 285 | |
| 286 struct server_reply_item *answer; /* linked list of answer RRs */ | |
| 287 struct server_reply_item *authority; /* linked list of authority RRs */ | |
| 288 struct server_reply_item *additional; /* linked list of additional RRs *
/ | |
| 289 | |
| 290 /* Constructed response. Only set once we're ready to send a reply. */ | |
| 291 /* Once this is set, the RR fields are cleared, and no more should be se
t. */ | |
| 292 char *response; | |
| 293 size_t response_len; | |
| 294 | |
| 295 /* Caller-visible fields: flags, questions. */ | |
| 296 struct evdns_server_request base; | |
| 297 }; | |
| 298 | |
| 299 /* helper macro */ | |
| 300 #define OFFSET_OF(st, member) ((off_t) (((char*)&((st*)0)->member)-(char*)0)) | |
| 301 | |
| 302 /* Given a pointer to an evdns_server_request, get the corresponding */ | |
| 303 /* server_request. */ | |
| 304 #define TO_SERVER_REQUEST(base_ptr)
\ | |
| 305 ((struct server_request*)
\ | |
| 306 (((char*)(base_ptr) - OFFSET_OF(struct server_request, base)))) | |
| 307 | |
| 308 /* The number of good nameservers that we have */ | |
| 309 static int global_good_nameservers = 0; | |
| 310 | |
| 311 /* inflight requests are contained in the req_head list */ | |
| 312 /* and are actually going out across the network */ | |
| 313 static int global_requests_inflight = 0; | |
| 314 /* requests which aren't inflight are in the waiting list */ | |
| 315 /* and are counted here */ | |
| 316 static int global_requests_waiting = 0; | |
| 317 | |
| 318 static int global_max_requests_inflight = 64; | |
| 319 | |
| 320 static struct timeval global_timeout = {5, 0}; /* 5 seconds */ | |
| 321 static int global_max_reissues = 1; /* a reissue occurs when we get some errors
from the server */ | |
| 322 static int global_max_retransmits = 3; /* number of times we'll retransmit a re
quest which timed out */ | |
| 323 /* number of timeouts in a row before we consider this server to be down */ | |
| 324 static int global_max_nameserver_timeout = 3; | |
| 325 | |
| 326 /* These are the timeout values for nameservers. If we find a nameserver is down
*/ | |
| 327 /* we try to probe it at intervals as given below. Values are in seconds. */ | |
| 328 static const struct timeval global_nameserver_timeouts[] = {{10, 0}, {60, 0}, {3
00, 0}, {900, 0}, {3600, 0}}; | |
| 329 static const int global_nameserver_timeouts_length = sizeof(global_nameserver_ti
meouts)/sizeof(struct timeval); | |
| 330 | |
| 331 static struct nameserver *nameserver_pick(void); | |
| 332 static void evdns_request_insert(struct request *req, struct request **head); | |
| 333 static void nameserver_ready_callback(int fd, short events, void *arg); | |
| 334 static int evdns_transmit(void); | |
| 335 static int evdns_request_transmit(struct request *req); | |
| 336 static void nameserver_send_probe(struct nameserver *const ns); | |
| 337 static void search_request_finished(struct request *const); | |
| 338 static int search_try_next(struct request *const req); | |
| 339 static int search_request_new(int type, const char *const name, int flags, evdns
_callback_type user_callback, void *user_arg); | |
| 340 static void evdns_requests_pump_waiting_queue(void); | |
| 341 static u16 transaction_id_pick(void); | |
| 342 static struct request *request_new(int type, const char *name, int flags, evdns_
callback_type callback, void *ptr); | |
| 343 static void request_submit(struct request *const req); | |
| 344 | |
| 345 static int server_request_free(struct server_request *req); | |
| 346 static void server_request_free_answers(struct server_request *req); | |
| 347 static void server_port_free(struct evdns_server_port *port); | |
| 348 static void server_port_ready_callback(int fd, short events, void *arg); | |
| 349 | |
| 350 static int strtoint(const char *const str); | |
| 351 | |
| 352 #ifdef WIN32 | |
| 353 static int | |
| 354 last_error(int sock) | |
| 355 { | |
| 356 int optval, optvallen=sizeof(optval); | |
| 357 int err = WSAGetLastError(); | |
| 358 if (err == WSAEWOULDBLOCK && sock >= 0) { | |
| 359 if (getsockopt(sock, SOL_SOCKET, SO_ERROR, (void*)&optval, | |
| 360 &optvallen)) | |
| 361 return err; | |
| 362 if (optval) | |
| 363 return optval; | |
| 364 } | |
| 365 return err; | |
| 366 | |
| 367 } | |
| 368 static int | |
| 369 error_is_eagain(int err) | |
| 370 { | |
| 371 return err == EAGAIN || err == WSAEWOULDBLOCK; | |
| 372 } | |
| 373 static int | |
| 374 inet_aton(const char *c, struct in_addr *addr) | |
| 375 { | |
| 376 ev_uint32_t r; | |
| 377 if (strcmp(c, "255.255.255.255") == 0) { | |
| 378 addr->s_addr = 0xffffffffu; | |
| 379 } else { | |
| 380 r = inet_addr(c); | |
| 381 if (r == INADDR_NONE) | |
| 382 return 0; | |
| 383 addr->s_addr = r; | |
| 384 } | |
| 385 return 1; | |
| 386 } | |
| 387 #else | |
| 388 #define last_error(sock) (errno) | |
| 389 #define error_is_eagain(err) ((err) == EAGAIN) | |
| 390 #endif | |
| 391 #define CLOSE_SOCKET(s) EVUTIL_CLOSESOCKET(s) | |
| 392 | |
| 393 #define ISSPACE(c) isspace((int)(unsigned char)(c)) | |
| 394 #define ISDIGIT(c) isdigit((int)(unsigned char)(c)) | |
| 395 | |
| 396 static const char * | |
| 397 debug_ntoa(u32 address) | |
| 398 { | |
| 399 static char buf[32]; | |
| 400 u32 a = ntohl(address); | |
| 401 evutil_snprintf(buf, sizeof(buf), "%d.%d.%d.%d", | |
| 402 (int)(u8)((a>>24)&0xff), | |
| 403 (int)(u8)((a>>16)&0xff), | |
| 404 (int)(u8)((a>>8 )&0xff), | |
| 405 (int)(u8)((a )&0xff)); | |
| 406 return buf; | |
| 407 } | |
| 408 | |
| 409 static evdns_debug_log_fn_type evdns_log_fn = NULL; | |
| 410 | |
| 411 void | |
| 412 evdns_set_log_fn(evdns_debug_log_fn_type fn) | |
| 413 { | |
| 414 evdns_log_fn = fn; | |
| 415 } | |
| 416 | |
| 417 #ifdef __GNUC__ | |
| 418 #define EVDNS_LOG_CHECK __attribute__ ((format(printf, 2, 3))) | |
| 419 #else | |
| 420 #define EVDNS_LOG_CHECK | |
| 421 #endif | |
| 422 | |
| 423 static void _evdns_log(int warn, const char *fmt, ...) EVDNS_LOG_CHECK; | |
| 424 static void | |
| 425 _evdns_log(int warn, const char *fmt, ...) | |
| 426 { | |
| 427 va_list args; | |
| 428 static char buf[512]; | |
| 429 if (!evdns_log_fn) | |
| 430 return; | |
| 431 va_start(args,fmt); | |
| 432 evutil_vsnprintf(buf, sizeof(buf), fmt, args); | |
| 433 buf[sizeof(buf)-1] = '\0'; | |
| 434 evdns_log_fn(warn, buf); | |
| 435 va_end(args); | |
| 436 } | |
| 437 | |
| 438 #define log _evdns_log | |
| 439 | |
| 440 /* This walks the list of inflight requests to find the */ | |
| 441 /* one with a matching transaction id. Returns NULL on */ | |
| 442 /* failure */ | |
| 443 static struct request * | |
| 444 request_find_from_trans_id(u16 trans_id) { | |
| 445 struct request *req = req_head, *const started_at = req_head; | |
| 446 | |
| 447 if (req) { | |
| 448 do { | |
| 449 if (req->trans_id == trans_id) return req; | |
| 450 req = req->next; | |
| 451 } while (req != started_at); | |
| 452 } | |
| 453 | |
| 454 return NULL; | |
| 455 } | |
| 456 | |
| 457 /* a libevent callback function which is called when a nameserver */ | |
| 458 /* has gone down and we want to test if it has came back to life yet */ | |
| 459 static void | |
| 460 nameserver_prod_callback(int fd, short events, void *arg) { | |
| 461 struct nameserver *const ns = (struct nameserver *) arg; | |
| 462 (void)fd; | |
| 463 (void)events; | |
| 464 | |
| 465 nameserver_send_probe(ns); | |
| 466 } | |
| 467 | |
| 468 /* a libevent callback which is called when a nameserver probe (to see if */ | |
| 469 /* it has come back to life) times out. We increment the count of failed_times *
/ | |
| 470 /* and wait longer to send the next probe packet. */ | |
| 471 static void | |
| 472 nameserver_probe_failed(struct nameserver *const ns) { | |
| 473 const struct timeval * timeout; | |
| 474 (void) evtimer_del(&ns->timeout_event); | |
| 475 if (ns->state == 1) { | |
| 476 /* This can happen if the nameserver acts in a way which makes u
s mark */ | |
| 477 /* it as bad and then starts sending good replies. */ | |
| 478 return; | |
| 479 } | |
| 480 | |
| 481 timeout = | |
| 482 &global_nameserver_timeouts[MIN(ns->failed_times, | |
| 483 global_nameserver_timeouts_length - 1)
]; | |
| 484 ns->failed_times++; | |
| 485 | |
| 486 if (evtimer_add(&ns->timeout_event, (struct timeval *) timeout) < 0) { | |
| 487 log(EVDNS_LOG_WARN, | |
| 488 "Error from libevent when adding timer event for %s", | |
| 489 debug_ntoa(ns->address)); | |
| 490 /* ???? Do more? */ | |
| 491 } | |
| 492 } | |
| 493 | |
| 494 /* called when a nameserver has been deemed to have failed. For example, too */ | |
| 495 /* many packets have timed out etc */ | |
| 496 static void | |
| 497 nameserver_failed(struct nameserver *const ns, const char *msg) { | |
| 498 struct request *req, *started_at; | |
| 499 /* if this nameserver has already been marked as failed */ | |
| 500 /* then don't do anything */ | |
| 501 if (!ns->state) return; | |
| 502 | |
| 503 log(EVDNS_LOG_WARN, "Nameserver %s has failed: %s", | |
| 504 debug_ntoa(ns->address), msg); | |
| 505 global_good_nameservers--; | |
| 506 assert(global_good_nameservers >= 0); | |
| 507 if (global_good_nameservers == 0) { | |
| 508 log(EVDNS_LOG_WARN, "All nameservers have failed"); | |
| 509 } | |
| 510 | |
| 511 ns->state = 0; | |
| 512 ns->failed_times = 1; | |
| 513 | |
| 514 if (evtimer_add(&ns->timeout_event, (struct timeval *) &global_nameserve
r_timeouts[0]) < 0) { | |
| 515 log(EVDNS_LOG_WARN, | |
| 516 "Error from libevent when adding timer event for %s", | |
| 517 debug_ntoa(ns->address)); | |
| 518 /* ???? Do more? */ | |
| 519 } | |
| 520 | |
| 521 /* walk the list of inflight requests to see if any can be reassigned to
*/ | |
| 522 /* a different server. Requests in the waiting queue don't have a */ | |
| 523 /* nameserver assigned yet */ | |
| 524 | |
| 525 /* if we don't have *any* good nameservers then there's no point */ | |
| 526 /* trying to reassign requests to one */ | |
| 527 if (!global_good_nameservers) return; | |
| 528 | |
| 529 req = req_head; | |
| 530 started_at = req_head; | |
| 531 if (req) { | |
| 532 do { | |
| 533 if (req->tx_count == 0 && req->ns == ns) { | |
| 534 /* still waiting to go out, can be moved */ | |
| 535 /* to another server */ | |
| 536 req->ns = nameserver_pick(); | |
| 537 } | |
| 538 req = req->next; | |
| 539 } while (req != started_at); | |
| 540 } | |
| 541 } | |
| 542 | |
| 543 static void | |
| 544 nameserver_up(struct nameserver *const ns) { | |
| 545 if (ns->state) return; | |
| 546 log(EVDNS_LOG_WARN, "Nameserver %s is back up", | |
| 547 debug_ntoa(ns->address)); | |
| 548 evtimer_del(&ns->timeout_event); | |
| 549 ns->state = 1; | |
| 550 ns->failed_times = 0; | |
| 551 ns->timedout = 0; | |
| 552 global_good_nameservers++; | |
| 553 } | |
| 554 | |
| 555 static void | |
| 556 request_trans_id_set(struct request *const req, const u16 trans_id) { | |
| 557 req->trans_id = trans_id; | |
| 558 *((u16 *) req->request) = htons(trans_id); | |
| 559 } | |
| 560 | |
| 561 /* Called to remove a request from a list and dealloc it. */ | |
| 562 /* head is a pointer to the head of the list it should be */ | |
| 563 /* removed from or NULL if the request isn't in a list. */ | |
| 564 static void | |
| 565 request_finished(struct request *const req, struct request **head) { | |
| 566 if (head) { | |
| 567 if (req->next == req) { | |
| 568 /* only item in the list */ | |
| 569 *head = NULL; | |
| 570 } else { | |
| 571 req->next->prev = req->prev; | |
| 572 req->prev->next = req->next; | |
| 573 if (*head == req) *head = req->next; | |
| 574 } | |
| 575 } | |
| 576 | |
| 577 log(EVDNS_LOG_DEBUG, "Removing timeout for request %lx", | |
| 578 (unsigned long) req); | |
| 579 evtimer_del(&req->timeout_event); | |
| 580 | |
| 581 search_request_finished(req); | |
| 582 global_requests_inflight--; | |
| 583 | |
| 584 if (!req->request_appended) { | |
| 585 /* need to free the request data on it's own */ | |
| 586 free(req->request); | |
| 587 } else { | |
| 588 /* the request data is appended onto the header */ | |
| 589 /* so everything gets free()ed when we: */ | |
| 590 } | |
| 591 | |
| 592 free(req); | |
| 593 | |
| 594 evdns_requests_pump_waiting_queue(); | |
| 595 } | |
| 596 | |
| 597 /* This is called when a server returns a funny error code. */ | |
| 598 /* We try the request again with another server. */ | |
| 599 /* */ | |
| 600 /* return: */ | |
| 601 /* 0 ok */ | |
| 602 /* 1 failed/reissue is pointless */ | |
| 603 static int | |
| 604 request_reissue(struct request *req) { | |
| 605 const struct nameserver *const last_ns = req->ns; | |
| 606 /* the last nameserver should have been marked as failing */ | |
| 607 /* by the caller of this function, therefore pick will try */ | |
| 608 /* not to return it */ | |
| 609 req->ns = nameserver_pick(); | |
| 610 if (req->ns == last_ns) { | |
| 611 /* ... but pick did return it */ | |
| 612 /* not a lot of point in trying again with the */ | |
| 613 /* same server */ | |
| 614 return 1; | |
| 615 } | |
| 616 | |
| 617 req->reissue_count++; | |
| 618 req->tx_count = 0; | |
| 619 req->transmit_me = 1; | |
| 620 | |
| 621 return 0; | |
| 622 } | |
| 623 | |
| 624 /* this function looks for space on the inflight queue and promotes */ | |
| 625 /* requests from the waiting queue if it can. */ | |
| 626 static void | |
| 627 evdns_requests_pump_waiting_queue(void) { | |
| 628 while (global_requests_inflight < global_max_requests_inflight && | |
| 629 global_requests_waiting) { | |
| 630 struct request *req; | |
| 631 /* move a request from the waiting queue to the inflight queue *
/ | |
| 632 assert(req_waiting_head); | |
| 633 if (req_waiting_head->next == req_waiting_head) { | |
| 634 /* only one item in the queue */ | |
| 635 req = req_waiting_head; | |
| 636 req_waiting_head = NULL; | |
| 637 } else { | |
| 638 req = req_waiting_head; | |
| 639 req->next->prev = req->prev; | |
| 640 req->prev->next = req->next; | |
| 641 req_waiting_head = req->next; | |
| 642 } | |
| 643 | |
| 644 global_requests_waiting--; | |
| 645 global_requests_inflight++; | |
| 646 | |
| 647 req->ns = nameserver_pick(); | |
| 648 request_trans_id_set(req, transaction_id_pick()); | |
| 649 | |
| 650 evdns_request_insert(req, &req_head); | |
| 651 evdns_request_transmit(req); | |
| 652 evdns_transmit(); | |
| 653 } | |
| 654 } | |
| 655 | |
| 656 static void | |
| 657 reply_callback(struct request *const req, u32 ttl, u32 err, struct reply *reply)
{ | |
| 658 switch (req->request_type) { | |
| 659 case TYPE_A: | |
| 660 if (reply) | |
| 661 req->user_callback(DNS_ERR_NONE, DNS_IPv4_A, | |
| 662 reply->data.a.addrcou
nt, ttl, | |
| 663 reply->data.a.addresses, | |
| 664 req->user_pointer); | |
| 665 else | |
| 666 req->user_callback(err, 0, 0, 0, NULL, req->user_pointer
); | |
| 667 return; | |
| 668 case TYPE_PTR: | |
| 669 if (reply) { | |
| 670 char *name = reply->data.ptr.name; | |
| 671 req->user_callback(DNS_ERR_NONE, DNS_PTR, 1, ttl, | |
| 672 &name, req->user_poin
ter); | |
| 673 } else { | |
| 674 req->user_callback(err, 0, 0, 0, NULL, | |
| 675 req->user_pointer); | |
| 676 } | |
| 677 return; | |
| 678 case TYPE_AAAA: | |
| 679 if (reply) | |
| 680 req->user_callback(DNS_ERR_NONE, DNS_IPv6_AAAA, | |
| 681 reply->data.aaaa.addr
count, ttl, | |
| 682 reply->data.aaaa.addr
esses, | |
| 683 req->user_pointer); | |
| 684 else | |
| 685 req->user_callback(err, 0, 0, 0, NULL, req->user_pointer
); | |
| 686 return; | |
| 687 } | |
| 688 assert(0); | |
| 689 } | |
| 690 | |
| 691 /* this processes a parsed reply packet */ | |
| 692 static void | |
| 693 reply_handle(struct request *const req, u16 flags, u32 ttl, struct reply *reply)
{ | |
| 694 int error; | |
| 695 static const int error_codes[] = { | |
| 696 DNS_ERR_FORMAT, DNS_ERR_SERVERFAILED, DNS_ERR_NOTEXIST, | |
| 697 DNS_ERR_NOTIMPL, DNS_ERR_REFUSED | |
| 698 }; | |
| 699 | |
| 700 if (flags & 0x020f || !reply || !reply->have_answer) { | |
| 701 /* there was an error */ | |
| 702 if (flags & 0x0200) { | |
| 703 error = DNS_ERR_TRUNCATED; | |
| 704 } else { | |
| 705 u16 error_code = (flags & 0x000f) - 1; | |
| 706 if (error_code > 4) { | |
| 707 error = DNS_ERR_UNKNOWN; | |
| 708 } else { | |
| 709 error = error_codes[error_code]; | |
| 710 } | |
| 711 } | |
| 712 | |
| 713 switch(error) { | |
| 714 case DNS_ERR_NOTIMPL: | |
| 715 case DNS_ERR_REFUSED: | |
| 716 /* we regard these errors as marking a bad nameserver */ | |
| 717 if (req->reissue_count < global_max_reissues) { | |
| 718 char msg[64]; | |
| 719 evutil_snprintf(msg, sizeof(msg), | |
| 720 "Bad response %d (%s)", | |
| 721 error, evdns_err_to_string(error)); | |
| 722 nameserver_failed(req->ns, msg); | |
| 723 if (!request_reissue(req)) return; | |
| 724 } | |
| 725 break; | |
| 726 case DNS_ERR_SERVERFAILED: | |
| 727 /* rcode 2 (servfailed) sometimes means "we | |
| 728 * are broken" and sometimes (with some binds) | |
| 729 * means "that request was very confusing." | |
| 730 * Treat this as a timeout, not a failure. | |
| 731 */ | |
| 732 log(EVDNS_LOG_DEBUG, "Got a SERVERFAILED from nameserver
%s; " | |
| 733 "will allow the request to time out.", | |
| 734 debug_ntoa(req->ns->address)); | |
| 735 break; | |
| 736 default: | |
| 737 /* we got a good reply from the nameserver */ | |
| 738 nameserver_up(req->ns); | |
| 739 } | |
| 740 | |
| 741 if (req->search_state && req->request_type != TYPE_PTR) { | |
| 742 /* if we have a list of domains to search in, | |
| 743 * try the next one */ | |
| 744 if (!search_try_next(req)) { | |
| 745 /* a new request was issued so this | |
| 746 * request is finished and */ | |
| 747 /* the user callback will be made when | |
| 748 * that request (or a */ | |
| 749 /* child of it) finishes. */ | |
| 750 request_finished(req, &req_head); | |
| 751 return; | |
| 752 } | |
| 753 } | |
| 754 | |
| 755 /* all else failed. Pass the failure up */ | |
| 756 reply_callback(req, 0, error, NULL); | |
| 757 request_finished(req, &req_head); | |
| 758 } else { | |
| 759 /* all ok, tell the user */ | |
| 760 reply_callback(req, ttl, 0, reply); | |
| 761 nameserver_up(req->ns); | |
| 762 request_finished(req, &req_head); | |
| 763 } | |
| 764 } | |
| 765 | |
| 766 static int | |
| 767 name_parse(u8 *packet, int length, int *idx, char *name_out, int name_out_len) { | |
| 768 int name_end = -1; | |
| 769 int j = *idx; | |
| 770 int ptr_count = 0; | |
| 771 #define GET32(x) do { if (j + 4 > length) goto err; memcpy(&_t32, packet + j, 4)
; j += 4; x = ntohl(_t32); } while(0) | |
| 772 #define GET16(x) do { if (j + 2 > length) goto err; memcpy(&_t, packet + j, 2);
j += 2; x = ntohs(_t); } while(0) | |
| 773 #define GET8(x) do { if (j >= length) goto err; x = packet[j++]; } while(0) | |
| 774 | |
| 775 char *cp = name_out; | |
| 776 const char *const end = name_out + name_out_len; | |
| 777 | |
| 778 /* Normally, names are a series of length prefixed strings terminated */ | |
| 779 /* with a length of 0 (the lengths are u8's < 63). */ | |
| 780 /* However, the length can start with a pair of 1 bits and that */ | |
| 781 /* means that the next 14 bits are a pointer within the current */ | |
| 782 /* packet. */ | |
| 783 | |
| 784 for(;;) { | |
| 785 u8 label_len; | |
| 786 if (j >= length) return -1; | |
| 787 GET8(label_len); | |
| 788 if (!label_len) break; | |
| 789 if (label_len & 0xc0) { | |
| 790 u8 ptr_low; | |
| 791 GET8(ptr_low); | |
| 792 if (name_end < 0) name_end = j; | |
| 793 j = (((int)label_len & 0x3f) << 8) + ptr_low; | |
| 794 /* Make sure that the target offset is in-bounds. */ | |
| 795 if (j < 0 || j >= length) return -1; | |
| 796 /* If we've jumped more times than there are characters
in the | |
| 797 * message, we must have a loop. */ | |
| 798 if (++ptr_count > length) return -1; | |
| 799 continue; | |
| 800 } | |
| 801 if (label_len > 63) return -1; | |
| 802 if (cp != name_out) { | |
| 803 if (cp + 1 >= end) return -1; | |
| 804 *cp++ = '.'; | |
| 805 } | |
| 806 if (cp + label_len >= end) return -1; | |
| 807 memcpy(cp, packet + j, label_len); | |
| 808 cp += label_len; | |
| 809 j += label_len; | |
| 810 } | |
| 811 if (cp >= end) return -1; | |
| 812 *cp = '\0'; | |
| 813 if (name_end < 0) | |
| 814 *idx = j; | |
| 815 else | |
| 816 *idx = name_end; | |
| 817 return 0; | |
| 818 err: | |
| 819 return -1; | |
| 820 } | |
| 821 | |
| 822 /* parses a raw request from a nameserver */ | |
| 823 static int | |
| 824 reply_parse(u8 *packet, int length) { | |
| 825 int j = 0, k = 0; /* index into packet */ | |
| 826 u16 _t; /* used by the macros */ | |
| 827 u32 _t32; /* used by the macros */ | |
| 828 char tmp_name[256], cmp_name[256]; /* used by the macros */ | |
| 829 | |
| 830 u16 trans_id, questions, answers, authority, additional, datalength; | |
| 831 u16 flags = 0; | |
| 832 u32 ttl, ttl_r = 0xffffffff; | |
| 833 struct reply reply; | |
| 834 struct request *req = NULL; | |
| 835 unsigned int i; | |
| 836 | |
| 837 GET16(trans_id); | |
| 838 GET16(flags); | |
| 839 GET16(questions); | |
| 840 GET16(answers); | |
| 841 GET16(authority); | |
| 842 GET16(additional); | |
| 843 (void) authority; /* suppress "unused variable" warnings. */ | |
| 844 (void) additional; /* suppress "unused variable" warnings. */ | |
| 845 | |
| 846 req = request_find_from_trans_id(trans_id); | |
| 847 if (!req) return -1; | |
| 848 | |
| 849 memset(&reply, 0, sizeof(reply)); | |
| 850 | |
| 851 /* If it's not an answer, it doesn't correspond to any request. */ | |
| 852 if (!(flags & 0x8000)) return -1; /* must be an answer */ | |
| 853 if (flags & 0x020f) { | |
| 854 /* there was an error */ | |
| 855 goto err; | |
| 856 } | |
| 857 /* if (!answers) return; */ /* must have an answer of some form */ | |
| 858 | |
| 859 /* This macro skips a name in the DNS reply. */ | |
| 860 #define SKIP_NAME \ | |
| 861 do { tmp_name[0] = '\0'; \ | |
| 862 if (name_parse(packet, length, &j, tmp_name, sizeof(tmp_name))<0
)\ | |
| 863 goto err; \ | |
| 864 } while(0) | |
| 865 #define TEST_NAME \ | |
| 866 do { tmp_name[0] = '\0'; \ | |
| 867 cmp_name[0] = '\0'; \ | |
| 868 k = j; \ | |
| 869 if (name_parse(packet, length, &j, tmp_name, sizeof(tmp_name))<0
)\ | |
| 870 goto err; \ | |
| 871 if (name_parse(req->request, req->request_len, &k, cmp_name, siz
eof(cmp_name))<0) \ | |
| 872 goto err; \ | |
| 873 if (memcmp(tmp_name, cmp_name, strlen (tmp_name)) != 0) \ | |
| 874 return (-1); /* we ignore mismatching names */ \ | |
| 875 } while(0) | |
| 876 | |
| 877 reply.type = req->request_type; | |
| 878 | |
| 879 /* skip over each question in the reply */ | |
| 880 for (i = 0; i < questions; ++i) { | |
| 881 /* the question looks like | |
| 882 * <label:name><u16:type><u16:class> | |
| 883 */ | |
| 884 TEST_NAME; | |
| 885 j += 4; | |
| 886 if (j > length) goto err; | |
| 887 } | |
| 888 | |
| 889 /* now we have the answer section which looks like | |
| 890 * <label:name><u16:type><u16:class><u32:ttl><u16:len><data...> | |
| 891 */ | |
| 892 | |
| 893 for (i = 0; i < answers; ++i) { | |
| 894 u16 type, class; | |
| 895 | |
| 896 SKIP_NAME; | |
| 897 GET16(type); | |
| 898 GET16(class); | |
| 899 GET32(ttl); | |
| 900 GET16(datalength); | |
| 901 | |
| 902 if (type == TYPE_A && class == CLASS_INET) { | |
| 903 int addrcount, addrtocopy; | |
| 904 if (req->request_type != TYPE_A) { | |
| 905 j += datalength; continue; | |
| 906 } | |
| 907 if ((datalength & 3) != 0) /* not an even number of As.
*/ | |
| 908 goto err; | |
| 909 addrcount = datalength >> 2; | |
| 910 addrtocopy = MIN(MAX_ADDRS - reply.data.a.addrcount, (un
signed)addrcount); | |
| 911 | |
| 912 ttl_r = MIN(ttl_r, ttl); | |
| 913 /* we only bother with the first four addresses. */ | |
| 914 if (j + 4*addrtocopy > length) goto err; | |
| 915 memcpy(&reply.data.a.addresses[reply.data.a.addrcount], | |
| 916 packet + j, 4*addrtocopy); | |
| 917 j += 4*addrtocopy; | |
| 918 reply.data.a.addrcount += addrtocopy; | |
| 919 reply.have_answer = 1; | |
| 920 if (reply.data.a.addrcount == MAX_ADDRS) break; | |
| 921 } else if (type == TYPE_PTR && class == CLASS_INET) { | |
| 922 if (req->request_type != TYPE_PTR) { | |
| 923 j += datalength; continue; | |
| 924 } | |
| 925 if (name_parse(packet, length, &j, reply.data.ptr.name, | |
| 926 sizeof(reply.data.ptr.name))<
0) | |
| 927 goto err; | |
| 928 ttl_r = MIN(ttl_r, ttl); | |
| 929 reply.have_answer = 1; | |
| 930 break; | |
| 931 } else if (type == TYPE_AAAA && class == CLASS_INET) { | |
| 932 int addrcount, addrtocopy; | |
| 933 if (req->request_type != TYPE_AAAA) { | |
| 934 j += datalength; continue; | |
| 935 } | |
| 936 if ((datalength & 15) != 0) /* not an even number of AAA
As. */ | |
| 937 goto err; | |
| 938 addrcount = datalength >> 4; /* each address is 16 byte
s long */ | |
| 939 addrtocopy = MIN(MAX_ADDRS - reply.data.aaaa.addrcount,
(unsigned)addrcount); | |
| 940 ttl_r = MIN(ttl_r, ttl); | |
| 941 | |
| 942 /* we only bother with the first four addresses. */ | |
| 943 if (j + 16*addrtocopy > length) goto err; | |
| 944 memcpy(&reply.data.aaaa.addresses[reply.data.aaaa.addrco
unt], | |
| 945 packet + j, 16*addrtocopy); | |
| 946 reply.data.aaaa.addrcount += addrtocopy; | |
| 947 j += 16*addrtocopy; | |
| 948 reply.have_answer = 1; | |
| 949 if (reply.data.aaaa.addrcount == MAX_ADDRS) break; | |
| 950 } else { | |
| 951 /* skip over any other type of resource */ | |
| 952 j += datalength; | |
| 953 } | |
| 954 } | |
| 955 | |
| 956 reply_handle(req, flags, ttl_r, &reply); | |
| 957 return 0; | |
| 958 err: | |
| 959 if (req) | |
| 960 reply_handle(req, flags, 0, NULL); | |
| 961 return -1; | |
| 962 } | |
| 963 | |
| 964 /* Parse a raw request (packet,length) sent to a nameserver port (port) from */ | |
| 965 /* a DNS client (addr,addrlen), and if it's well-formed, call the corresponding
*/ | |
| 966 /* callback. */ | |
| 967 static int | |
| 968 request_parse(u8 *packet, int length, struct evdns_server_port *port, struct soc
kaddr *addr, socklen_t addrlen) | |
| 969 { | |
| 970 int j = 0; /* index into packet */ | |
| 971 u16 _t; /* used by the macros */ | |
| 972 char tmp_name[256]; /* used by the macros */ | |
| 973 | |
| 974 int i; | |
| 975 u16 trans_id, flags, questions, answers, authority, additional; | |
| 976 struct server_request *server_req = NULL; | |
| 977 | |
| 978 /* Get the header fields */ | |
| 979 GET16(trans_id); | |
| 980 GET16(flags); | |
| 981 GET16(questions); | |
| 982 GET16(answers); | |
| 983 GET16(authority); | |
| 984 GET16(additional); | |
| 985 | |
| 986 if (flags & 0x8000) return -1; /* Must not be an answer. */ | |
| 987 flags &= 0x0110; /* Only RD and CD get preserved. */ | |
| 988 | |
| 989 server_req = malloc(sizeof(struct server_request)); | |
| 990 if (server_req == NULL) return -1; | |
| 991 memset(server_req, 0, sizeof(struct server_request)); | |
| 992 | |
| 993 server_req->trans_id = trans_id; | |
| 994 memcpy(&server_req->addr, addr, addrlen); | |
| 995 server_req->addrlen = addrlen; | |
| 996 | |
| 997 server_req->base.flags = flags; | |
| 998 server_req->base.nquestions = 0; | |
| 999 server_req->base.questions = malloc(sizeof(struct evdns_server_question
*) * questions); | |
| 1000 if (server_req->base.questions == NULL) | |
| 1001 goto err; | |
| 1002 | |
| 1003 for (i = 0; i < questions; ++i) { | |
| 1004 u16 type, class; | |
| 1005 struct evdns_server_question *q; | |
| 1006 int namelen; | |
| 1007 if (name_parse(packet, length, &j, tmp_name, sizeof(tmp_name))<0
) | |
| 1008 goto err; | |
| 1009 GET16(type); | |
| 1010 GET16(class); | |
| 1011 namelen = strlen(tmp_name); | |
| 1012 q = malloc(sizeof(struct evdns_server_question) + namelen); | |
| 1013 if (!q) | |
| 1014 goto err; | |
| 1015 q->type = type; | |
| 1016 q->dns_question_class = class; | |
| 1017 memcpy(q->name, tmp_name, namelen+1); | |
| 1018 server_req->base.questions[server_req->base.nquestions++] = q; | |
| 1019 } | |
| 1020 | |
| 1021 /* Ignore answers, authority, and additional. */ | |
| 1022 | |
| 1023 server_req->port = port; | |
| 1024 port->refcnt++; | |
| 1025 | |
| 1026 /* Only standard queries are supported. */ | |
| 1027 if (flags & 0x7800) { | |
| 1028 evdns_server_request_respond(&(server_req->base), DNS_ERR_NOTIMP
L); | |
| 1029 return -1; | |
| 1030 } | |
| 1031 | |
| 1032 port->user_callback(&(server_req->base), port->user_data); | |
| 1033 | |
| 1034 return 0; | |
| 1035 err: | |
| 1036 if (server_req) { | |
| 1037 if (server_req->base.questions) { | |
| 1038 for (i = 0; i < server_req->base.nquestions; ++i) | |
| 1039 free(server_req->base.questions[i]); | |
| 1040 free(server_req->base.questions); | |
| 1041 } | |
| 1042 free(server_req); | |
| 1043 } | |
| 1044 return -1; | |
| 1045 | |
| 1046 #undef SKIP_NAME | |
| 1047 #undef GET32 | |
| 1048 #undef GET16 | |
| 1049 #undef GET8 | |
| 1050 } | |
| 1051 | |
| 1052 static u16 | |
| 1053 default_transaction_id_fn(void) | |
| 1054 { | |
| 1055 u16 trans_id; | |
| 1056 #ifdef DNS_USE_CPU_CLOCK_FOR_ID | |
| 1057 struct timespec ts; | |
| 1058 static int clkid = -1; | |
| 1059 if (clkid == -1) { | |
| 1060 clkid = CLOCK_REALTIME; | |
| 1061 #ifdef CLOCK_MONOTONIC | |
| 1062 if (clock_gettime(CLOCK_MONOTONIC, &ts) != -1) | |
| 1063 clkid = CLOCK_MONOTONIC; | |
| 1064 #endif | |
| 1065 } | |
| 1066 if (clock_gettime(clkid, &ts) == -1) | |
| 1067 event_err(1, "clock_gettime"); | |
| 1068 trans_id = ts.tv_nsec & 0xffff; | |
| 1069 #endif | |
| 1070 | |
| 1071 #ifdef DNS_USE_FTIME_FOR_ID | |
| 1072 struct _timeb tb; | |
| 1073 _ftime(&tb); | |
| 1074 trans_id = tb.millitm & 0xffff; | |
| 1075 #endif | |
| 1076 | |
| 1077 #ifdef DNS_USE_GETTIMEOFDAY_FOR_ID | |
| 1078 struct timeval tv; | |
| 1079 evutil_gettimeofday(&tv, NULL); | |
| 1080 trans_id = tv.tv_usec & 0xffff; | |
| 1081 #endif | |
| 1082 | |
| 1083 #ifdef DNS_USE_OPENSSL_FOR_ID | |
| 1084 if (RAND_pseudo_bytes((u8 *) &trans_id, 2) == -1) { | |
| 1085 /* in the case that the RAND call fails we back */ | |
| 1086 /* down to using gettimeofday. */ | |
| 1087 /* | |
| 1088 struct timeval tv; | |
| 1089 evutil_gettimeofday(&tv, NULL); | |
| 1090 trans_id = tv.tv_usec & 0xffff; | |
| 1091 */ | |
| 1092 abort(); | |
| 1093 } | |
| 1094 #endif | |
| 1095 return trans_id; | |
| 1096 } | |
| 1097 | |
| 1098 static ev_uint16_t (*trans_id_function)(void) = default_transaction_id_fn; | |
| 1099 | |
| 1100 void | |
| 1101 evdns_set_transaction_id_fn(ev_uint16_t (*fn)(void)) | |
| 1102 { | |
| 1103 if (fn) | |
| 1104 trans_id_function = fn; | |
| 1105 else | |
| 1106 trans_id_function = default_transaction_id_fn; | |
| 1107 } | |
| 1108 | |
| 1109 /* Try to choose a strong transaction id which isn't already in flight */ | |
| 1110 static u16 | |
| 1111 transaction_id_pick(void) { | |
| 1112 for (;;) { | |
| 1113 u16 trans_id = trans_id_function(); | |
| 1114 | |
| 1115 if (trans_id == 0xffff) continue; | |
| 1116 | |
| 1117 if (request_find_from_trans_id(trans_id) == NULL) | |
| 1118 return trans_id; | |
| 1119 } | |
| 1120 } | |
| 1121 | |
| 1122 /* choose a namesever to use. This function will try to ignore */ | |
| 1123 /* nameservers which we think are down and load balance across the rest */ | |
| 1124 /* by updating the server_head global each time. */ | |
| 1125 static struct nameserver * | |
| 1126 nameserver_pick(void) { | |
| 1127 struct nameserver *started_at = server_head, *picked; | |
| 1128 if (!server_head) return NULL; | |
| 1129 | |
| 1130 /* if we don't have any good nameservers then there's no */ | |
| 1131 /* point in trying to find one. */ | |
| 1132 if (!global_good_nameservers) { | |
| 1133 server_head = server_head->next; | |
| 1134 return server_head; | |
| 1135 } | |
| 1136 | |
| 1137 /* remember that nameservers are in a circular list */ | |
| 1138 for (;;) { | |
| 1139 if (server_head->state) { | |
| 1140 /* we think this server is currently good */ | |
| 1141 picked = server_head; | |
| 1142 server_head = server_head->next; | |
| 1143 return picked; | |
| 1144 } | |
| 1145 | |
| 1146 server_head = server_head->next; | |
| 1147 if (server_head == started_at) { | |
| 1148 /* all the nameservers seem to be down */ | |
| 1149 /* so we just return this one and hope for the */ | |
| 1150 /* best */ | |
| 1151 assert(global_good_nameservers == 0); | |
| 1152 picked = server_head; | |
| 1153 server_head = server_head->next; | |
| 1154 return picked; | |
| 1155 } | |
| 1156 } | |
| 1157 } | |
| 1158 | |
| 1159 static int | |
| 1160 address_is_correct(struct nameserver *ns, struct sockaddr *sa, socklen_t slen) | |
| 1161 { | |
| 1162 struct sockaddr_in *sin = (struct sockaddr_in*) sa; | |
| 1163 if (sa->sa_family != AF_INET || slen != sizeof(struct sockaddr_in)) | |
| 1164 return 0; | |
| 1165 if (sin->sin_addr.s_addr != ns->address) | |
| 1166 return 0; | |
| 1167 return 1; | |
| 1168 } | |
| 1169 | |
| 1170 /* this is called when a namesever socket is ready for reading */ | |
| 1171 static void | |
| 1172 nameserver_read(struct nameserver *ns) { | |
| 1173 u8 packet[1500]; | |
| 1174 struct sockaddr_storage ss; | |
| 1175 socklen_t addrlen = sizeof(ss); | |
| 1176 | |
| 1177 for (;;) { | |
| 1178 const int r = recvfrom(ns->socket, packet, sizeof(packet), 0, | |
| 1179 (struct sockaddr*)&ss, &addrlen); | |
| 1180 if (r < 0) { | |
| 1181 int err = last_error(ns->socket); | |
| 1182 if (error_is_eagain(err)) return; | |
| 1183 nameserver_failed(ns, strerror(err)); | |
| 1184 return; | |
| 1185 } | |
| 1186 if (!address_is_correct(ns, (struct sockaddr*)&ss, addrlen)) { | |
| 1187 log(EVDNS_LOG_WARN, "Address mismatch on received " | |
| 1188 "DNS packet."); | |
| 1189 return; | |
| 1190 } | |
| 1191 ns->timedout = 0; | |
| 1192 reply_parse(packet, r); | |
| 1193 } | |
| 1194 } | |
| 1195 | |
| 1196 /* Read a packet from a DNS client on a server port s, parse it, and */ | |
| 1197 /* act accordingly. */ | |
| 1198 static void | |
| 1199 server_port_read(struct evdns_server_port *s) { | |
| 1200 u8 packet[1500]; | |
| 1201 struct sockaddr_storage addr; | |
| 1202 socklen_t addrlen; | |
| 1203 int r; | |
| 1204 | |
| 1205 for (;;) { | |
| 1206 addrlen = sizeof(struct sockaddr_storage); | |
| 1207 r = recvfrom(s->socket, packet, sizeof(packet), 0, | |
| 1208 (struct sockaddr*) &addr, &addrlen); | |
| 1209 if (r < 0) { | |
| 1210 int err = last_error(s->socket); | |
| 1211 if (error_is_eagain(err)) return; | |
| 1212 log(EVDNS_LOG_WARN, "Error %s (%d) while reading request
.", | |
| 1213 strerror(err), err); | |
| 1214 return; | |
| 1215 } | |
| 1216 request_parse(packet, r, s, (struct sockaddr*) &addr, addrlen); | |
| 1217 } | |
| 1218 } | |
| 1219 | |
| 1220 /* Try to write all pending replies on a given DNS server port. */ | |
| 1221 static void | |
| 1222 server_port_flush(struct evdns_server_port *port) | |
| 1223 { | |
| 1224 while (port->pending_replies) { | |
| 1225 struct server_request *req = port->pending_replies; | |
| 1226 int r = sendto(port->socket, req->response, req->response_len, 0
, | |
| 1227 (struct sockaddr*) &req->addr, req->addrlen); | |
| 1228 if (r < 0) { | |
| 1229 int err = last_error(port->socket); | |
| 1230 if (error_is_eagain(err)) | |
| 1231 return; | |
| 1232 log(EVDNS_LOG_WARN, "Error %s (%d) while writing respons
e to port; dropping", strerror(err), err); | |
| 1233 } | |
| 1234 if (server_request_free(req)) { | |
| 1235 /* we released the last reference to req->port. */ | |
| 1236 return; | |
| 1237 } | |
| 1238 } | |
| 1239 | |
| 1240 /* We have no more pending requests; stop listening for 'writeable' even
ts. */ | |
| 1241 (void) event_del(&port->event); | |
| 1242 event_set(&port->event, port->socket, EV_READ | EV_PERSIST, | |
| 1243 server_port_ready_callback, port); | |
| 1244 if (event_add(&port->event, NULL) < 0) { | |
| 1245 log(EVDNS_LOG_WARN, "Error from libevent when adding event for D
NS server."); | |
| 1246 /* ???? Do more? */ | |
| 1247 } | |
| 1248 } | |
| 1249 | |
| 1250 /* set if we are waiting for the ability to write to this server. */ | |
| 1251 /* if waiting is true then we ask libevent for EV_WRITE events, otherwise */ | |
| 1252 /* we stop these events. */ | |
| 1253 static void | |
| 1254 nameserver_write_waiting(struct nameserver *ns, char waiting) { | |
| 1255 if (ns->write_waiting == waiting) return; | |
| 1256 | |
| 1257 ns->write_waiting = waiting; | |
| 1258 (void) event_del(&ns->event); | |
| 1259 event_set(&ns->event, ns->socket, EV_READ | (waiting ? EV_WRITE : 0) | E
V_PERSIST, | |
| 1260 nameserver_ready_callback, ns); | |
| 1261 if (event_add(&ns->event, NULL) < 0) { | |
| 1262 log(EVDNS_LOG_WARN, "Error from libevent when adding event for %s", | |
| 1263 debug_ntoa(ns->address)); | |
| 1264 /* ???? Do more? */ | |
| 1265 } | |
| 1266 } | |
| 1267 | |
| 1268 /* a callback function. Called by libevent when the kernel says that */ | |
| 1269 /* a nameserver socket is ready for writing or reading */ | |
| 1270 static void | |
| 1271 nameserver_ready_callback(int fd, short events, void *arg) { | |
| 1272 struct nameserver *ns = (struct nameserver *) arg; | |
| 1273 (void)fd; | |
| 1274 | |
| 1275 if (events & EV_WRITE) { | |
| 1276 ns->choked = 0; | |
| 1277 if (!evdns_transmit()) { | |
| 1278 nameserver_write_waiting(ns, 0); | |
| 1279 } | |
| 1280 } | |
| 1281 if (events & EV_READ) { | |
| 1282 nameserver_read(ns); | |
| 1283 } | |
| 1284 } | |
| 1285 | |
| 1286 /* a callback function. Called by libevent when the kernel says that */ | |
| 1287 /* a server socket is ready for writing or reading. */ | |
| 1288 static void | |
| 1289 server_port_ready_callback(int fd, short events, void *arg) { | |
| 1290 struct evdns_server_port *port = (struct evdns_server_port *) arg; | |
| 1291 (void) fd; | |
| 1292 | |
| 1293 if (events & EV_WRITE) { | |
| 1294 port->choked = 0; | |
| 1295 server_port_flush(port); | |
| 1296 } | |
| 1297 if (events & EV_READ) { | |
| 1298 server_port_read(port); | |
| 1299 } | |
| 1300 } | |
| 1301 | |
| 1302 /* This is an inefficient representation; only use it via the dnslabel_table_* | |
| 1303 * functions, so that is can be safely replaced with something smarter later. */ | |
| 1304 #define MAX_LABELS 128 | |
| 1305 /* Structures used to implement name compression */ | |
| 1306 struct dnslabel_entry { char *v; off_t pos; }; | |
| 1307 struct dnslabel_table { | |
| 1308 int n_labels; /* number of current entries */ | |
| 1309 /* map from name to position in message */ | |
| 1310 struct dnslabel_entry labels[MAX_LABELS]; | |
| 1311 }; | |
| 1312 | |
| 1313 /* Initialize dnslabel_table. */ | |
| 1314 static void | |
| 1315 dnslabel_table_init(struct dnslabel_table *table) | |
| 1316 { | |
| 1317 table->n_labels = 0; | |
| 1318 } | |
| 1319 | |
| 1320 /* Free all storage held by table, but not the table itself. */ | |
| 1321 static void | |
| 1322 dnslabel_clear(struct dnslabel_table *table) | |
| 1323 { | |
| 1324 int i; | |
| 1325 for (i = 0; i < table->n_labels; ++i) | |
| 1326 free(table->labels[i].v); | |
| 1327 table->n_labels = 0; | |
| 1328 } | |
| 1329 | |
| 1330 /* return the position of the label in the current message, or -1 if the label *
/ | |
| 1331 /* hasn't been used yet. */ | |
| 1332 static int | |
| 1333 dnslabel_table_get_pos(const struct dnslabel_table *table, const char *label) | |
| 1334 { | |
| 1335 int i; | |
| 1336 for (i = 0; i < table->n_labels; ++i) { | |
| 1337 if (!strcmp(label, table->labels[i].v)) | |
| 1338 return table->labels[i].pos; | |
| 1339 } | |
| 1340 return -1; | |
| 1341 } | |
| 1342 | |
| 1343 /* remember that we've used the label at position pos */ | |
| 1344 static int | |
| 1345 dnslabel_table_add(struct dnslabel_table *table, const char *label, off_t pos) | |
| 1346 { | |
| 1347 char *v; | |
| 1348 int p; | |
| 1349 if (table->n_labels == MAX_LABELS) | |
| 1350 return (-1); | |
| 1351 v = strdup(label); | |
| 1352 if (v == NULL) | |
| 1353 return (-1); | |
| 1354 p = table->n_labels++; | |
| 1355 table->labels[p].v = v; | |
| 1356 table->labels[p].pos = pos; | |
| 1357 | |
| 1358 return (0); | |
| 1359 } | |
| 1360 | |
| 1361 /* Converts a string to a length-prefixed set of DNS labels, starting */ | |
| 1362 /* at buf[j]. name and buf must not overlap. name_len should be the length */ | |
| 1363 /* of name. table is optional, and is used for compression. */ | |
| 1364 /* */ | |
| 1365 /* Input: abc.def */ | |
| 1366 /* Output: <3>abc<3>def<0> */ | |
| 1367 /* */ | |
| 1368 /* Returns the first index after the encoded name, or negative on error. */ | |
| 1369 /* -1 label was > 63 bytes */ | |
| 1370 /* -2 name too long to fit in buffer. */ | |
| 1371 /* */ | |
| 1372 static off_t | |
| 1373 dnsname_to_labels(u8 *const buf, size_t buf_len, off_t j, | |
| 1374 const char *name, const int name_len, | |
| 1375 struct dnslabel_table *table) { | |
| 1376 const char *end = name + name_len; | |
| 1377 int ref = 0; | |
| 1378 u16 _t; | |
| 1379 | |
| 1380 #define APPEND16(x) do { \ | |
| 1381 if (j + 2 > (off_t)buf_len) \ | |
| 1382 goto overflow;
\ | |
| 1383 _t = htons(x);
\ | |
| 1384 memcpy(buf + j, &_t, 2); \ | |
| 1385 j += 2;
\ | |
| 1386 } while (0) | |
| 1387 #define APPEND32(x) do { \ | |
| 1388 if (j + 4 > (off_t)buf_len) \ | |
| 1389 goto overflow;
\ | |
| 1390 _t32 = htonl(x);
\ | |
| 1391 memcpy(buf + j, &_t32, 4); \ | |
| 1392 j += 4;
\ | |
| 1393 } while (0) | |
| 1394 | |
| 1395 if (name_len > 255) return -2; | |
| 1396 | |
| 1397 for (;;) { | |
| 1398 const char *const start = name; | |
| 1399 if (table && (ref = dnslabel_table_get_pos(table, name)) >= 0) { | |
| 1400 APPEND16(ref | 0xc000); | |
| 1401 return j; | |
| 1402 } | |
| 1403 name = strchr(name, '.'); | |
| 1404 if (!name) { | |
| 1405 const unsigned int label_len = end - start; | |
| 1406 if (label_len > 63) return -1; | |
| 1407 if ((size_t)(j+label_len+1) > buf_len) return -2; | |
| 1408 if (table) dnslabel_table_add(table, start, j); | |
| 1409 buf[j++] = label_len; | |
| 1410 | |
| 1411 memcpy(buf + j, start, end - start); | |
| 1412 j += end - start; | |
| 1413 break; | |
| 1414 } else { | |
| 1415 /* append length of the label. */ | |
| 1416 const unsigned int label_len = name - start; | |
| 1417 if (label_len > 63) return -1; | |
| 1418 if ((size_t)(j+label_len+1) > buf_len) return -2; | |
| 1419 if (table) dnslabel_table_add(table, start, j); | |
| 1420 buf[j++] = label_len; | |
| 1421 | |
| 1422 memcpy(buf + j, start, name - start); | |
| 1423 j += name - start; | |
| 1424 /* hop over the '.' */ | |
| 1425 name++; | |
| 1426 } | |
| 1427 } | |
| 1428 | |
| 1429 /* the labels must be terminated by a 0. */ | |
| 1430 /* It's possible that the name ended in a . */ | |
| 1431 /* in which case the zero is already there */ | |
| 1432 if (!j || buf[j-1]) buf[j++] = 0; | |
| 1433 return j; | |
| 1434 overflow: | |
| 1435 return (-2); | |
| 1436 } | |
| 1437 | |
| 1438 /* Finds the length of a dns request for a DNS name of the given */ | |
| 1439 /* length. The actual request may be smaller than the value returned */ | |
| 1440 /* here */ | |
| 1441 static int | |
| 1442 evdns_request_len(const int name_len) { | |
| 1443 return 96 + /* length of the DNS standard header */ | |
| 1444 name_len + 2 + | |
| 1445 4; /* space for the resource type */ | |
| 1446 } | |
| 1447 | |
| 1448 /* build a dns request packet into buf. buf should be at least as long */ | |
| 1449 /* as evdns_request_len told you it should be. */ | |
| 1450 /* */ | |
| 1451 /* Returns the amount of space used. Negative on error. */ | |
| 1452 static int | |
| 1453 evdns_request_data_build(const char *const name, const int name_len, | |
| 1454 const u16 trans_id, const u16 type, const u16 class, | |
| 1455 u8 *const buf, size_t buf_len) { | |
| 1456 off_t j = 0; /* current offset into buf */ | |
| 1457 u16 _t; /* used by the macros */ | |
| 1458 | |
| 1459 APPEND16(trans_id); | |
| 1460 APPEND16(0x0100); /* standard query, recusion needed */ | |
| 1461 APPEND16(1); /* one question */ | |
| 1462 APPEND16(0); /* no answers */ | |
| 1463 APPEND16(0); /* no authority */ | |
| 1464 APPEND16(0); /* no additional */ | |
| 1465 | |
| 1466 j = dnsname_to_labels(buf, buf_len, j, name, name_len, NULL); | |
| 1467 if (j < 0) { | |
| 1468 return (int)j; | |
| 1469 } | |
| 1470 | |
| 1471 APPEND16(type); | |
| 1472 APPEND16(class); | |
| 1473 | |
| 1474 return (int)j; | |
| 1475 overflow: | |
| 1476 return (-1); | |
| 1477 } | |
| 1478 | |
| 1479 /* exported function */ | |
| 1480 struct evdns_server_port * | |
| 1481 evdns_add_server_port(int socket, int is_tcp, evdns_request_callback_fn_type cb,
void *user_data) | |
| 1482 { | |
| 1483 struct evdns_server_port *port; | |
| 1484 if (!(port = malloc(sizeof(struct evdns_server_port)))) | |
| 1485 return NULL; | |
| 1486 memset(port, 0, sizeof(struct evdns_server_port)); | |
| 1487 | |
| 1488 assert(!is_tcp); /* TCP sockets not yet implemented */ | |
| 1489 port->socket = socket; | |
| 1490 port->refcnt = 1; | |
| 1491 port->choked = 0; | |
| 1492 port->closing = 0; | |
| 1493 port->user_callback = cb; | |
| 1494 port->user_data = user_data; | |
| 1495 port->pending_replies = NULL; | |
| 1496 | |
| 1497 event_set(&port->event, port->socket, EV_READ | EV_PERSIST, | |
| 1498 server_port_ready_callback, port); | |
| 1499 event_add(&port->event, NULL); /* check return. */ | |
| 1500 return port; | |
| 1501 } | |
| 1502 | |
| 1503 /* exported function */ | |
| 1504 void | |
| 1505 evdns_close_server_port(struct evdns_server_port *port) | |
| 1506 { | |
| 1507 if (--port->refcnt == 0) | |
| 1508 server_port_free(port); | |
| 1509 port->closing = 1; | |
| 1510 } | |
| 1511 | |
| 1512 /* exported function */ | |
| 1513 int | |
| 1514 evdns_server_request_add_reply(struct evdns_server_request *_req, int section, c
onst char *name, int type, int class, int ttl, int datalen, int is_name, const c
har *data) | |
| 1515 { | |
| 1516 struct server_request *req = TO_SERVER_REQUEST(_req); | |
| 1517 struct server_reply_item **itemp, *item; | |
| 1518 int *countp; | |
| 1519 | |
| 1520 if (req->response) /* have we already answered? */ | |
| 1521 return (-1); | |
| 1522 | |
| 1523 switch (section) { | |
| 1524 case EVDNS_ANSWER_SECTION: | |
| 1525 itemp = &req->answer; | |
| 1526 countp = &req->n_answer; | |
| 1527 break; | |
| 1528 case EVDNS_AUTHORITY_SECTION: | |
| 1529 itemp = &req->authority; | |
| 1530 countp = &req->n_authority; | |
| 1531 break; | |
| 1532 case EVDNS_ADDITIONAL_SECTION: | |
| 1533 itemp = &req->additional; | |
| 1534 countp = &req->n_additional; | |
| 1535 break; | |
| 1536 default: | |
| 1537 return (-1); | |
| 1538 } | |
| 1539 while (*itemp) { | |
| 1540 itemp = &((*itemp)->next); | |
| 1541 } | |
| 1542 item = malloc(sizeof(struct server_reply_item)); | |
| 1543 if (!item) | |
| 1544 return -1; | |
| 1545 item->next = NULL; | |
| 1546 if (!(item->name = strdup(name))) { | |
| 1547 free(item); | |
| 1548 return -1; | |
| 1549 } | |
| 1550 item->type = type; | |
| 1551 item->dns_question_class = class; | |
| 1552 item->ttl = ttl; | |
| 1553 item->is_name = is_name != 0; | |
| 1554 item->datalen = 0; | |
| 1555 item->data = NULL; | |
| 1556 if (data) { | |
| 1557 if (item->is_name) { | |
| 1558 if (!(item->data = strdup(data))) { | |
| 1559 free(item->name); | |
| 1560 free(item); | |
| 1561 return -1; | |
| 1562 } | |
| 1563 item->datalen = (u16)-1; | |
| 1564 } else { | |
| 1565 if (!(item->data = malloc(datalen))) { | |
| 1566 free(item->name); | |
| 1567 free(item); | |
| 1568 return -1; | |
| 1569 } | |
| 1570 item->datalen = datalen; | |
| 1571 memcpy(item->data, data, datalen); | |
| 1572 } | |
| 1573 } | |
| 1574 | |
| 1575 *itemp = item; | |
| 1576 ++(*countp); | |
| 1577 return 0; | |
| 1578 } | |
| 1579 | |
| 1580 /* exported function */ | |
| 1581 int | |
| 1582 evdns_server_request_add_a_reply(struct evdns_server_request *req, const char *n
ame, int n, void *addrs, int ttl) | |
| 1583 { | |
| 1584 return evdns_server_request_add_reply( | |
| 1585 req, EVDNS_ANSWER_SECTION, name, TYPE_A, CLASS_INET, | |
| 1586 ttl, n*4, 0, addrs); | |
| 1587 } | |
| 1588 | |
| 1589 /* exported function */ | |
| 1590 int | |
| 1591 evdns_server_request_add_aaaa_reply(struct evdns_server_request *req, const char
*name, int n, void *addrs, int ttl) | |
| 1592 { | |
| 1593 return evdns_server_request_add_reply( | |
| 1594 req, EVDNS_ANSWER_SECTION, name, TYPE_AAAA, CLASS_INET, | |
| 1595 ttl, n*16, 0, addrs); | |
| 1596 } | |
| 1597 | |
| 1598 /* exported function */ | |
| 1599 int | |
| 1600 evdns_server_request_add_ptr_reply(struct evdns_server_request *req, struct in_a
ddr *in, const char *inaddr_name, const char *hostname, int ttl) | |
| 1601 { | |
| 1602 u32 a; | |
| 1603 char buf[32]; | |
| 1604 assert(in || inaddr_name); | |
| 1605 assert(!(in && inaddr_name)); | |
| 1606 if (in) { | |
| 1607 a = ntohl(in->s_addr); | |
| 1608 evutil_snprintf(buf, sizeof(buf), "%d.%d.%d.%d.in-addr.arpa", | |
| 1609 (int)(u8)((a )&0xff), | |
| 1610 (int)(u8)((a>>8 )&0xff), | |
| 1611 (int)(u8)((a>>16)&0xff), | |
| 1612 (int)(u8)((a>>24)&0xff)); | |
| 1613 inaddr_name = buf; | |
| 1614 } | |
| 1615 return evdns_server_request_add_reply( | |
| 1616 req, EVDNS_ANSWER_SECTION, inaddr_name, TYPE_PTR, CLASS_INET, | |
| 1617 ttl, -1, 1, hostname); | |
| 1618 } | |
| 1619 | |
| 1620 /* exported function */ | |
| 1621 int | |
| 1622 evdns_server_request_add_cname_reply(struct evdns_server_request *req, const cha
r *name, const char *cname, int ttl) | |
| 1623 { | |
| 1624 return evdns_server_request_add_reply( | |
| 1625 req, EVDNS_ANSWER_SECTION, name, TYPE_CNAME, CLASS_INET, | |
| 1626 ttl, -1, 1, cname); | |
| 1627 } | |
| 1628 | |
| 1629 | |
| 1630 static int | |
| 1631 evdns_server_request_format_response(struct server_request *req, int err) | |
| 1632 { | |
| 1633 unsigned char buf[1500]; | |
| 1634 size_t buf_len = sizeof(buf); | |
| 1635 off_t j = 0, r; | |
| 1636 u16 _t; | |
| 1637 u32 _t32; | |
| 1638 int i; | |
| 1639 u16 flags; | |
| 1640 struct dnslabel_table table; | |
| 1641 | |
| 1642 if (err < 0 || err > 15) return -1; | |
| 1643 | |
| 1644 /* Set response bit and error code; copy OPCODE and RD fields from | |
| 1645 * question; copy RA and AA if set by caller. */ | |
| 1646 flags = req->base.flags; | |
| 1647 flags |= (0x8000 | err); | |
| 1648 | |
| 1649 dnslabel_table_init(&table); | |
| 1650 APPEND16(req->trans_id); | |
| 1651 APPEND16(flags); | |
| 1652 APPEND16(req->base.nquestions); | |
| 1653 APPEND16(req->n_answer); | |
| 1654 APPEND16(req->n_authority); | |
| 1655 APPEND16(req->n_additional); | |
| 1656 | |
| 1657 /* Add questions. */ | |
| 1658 for (i=0; i < req->base.nquestions; ++i) { | |
| 1659 const char *s = req->base.questions[i]->name; | |
| 1660 j = dnsname_to_labels(buf, buf_len, j, s, strlen(s), &table); | |
| 1661 if (j < 0) { | |
| 1662 dnslabel_clear(&table); | |
| 1663 return (int) j; | |
| 1664 } | |
| 1665 APPEND16(req->base.questions[i]->type); | |
| 1666 APPEND16(req->base.questions[i]->dns_question_class); | |
| 1667 } | |
| 1668 | |
| 1669 /* Add answer, authority, and additional sections. */ | |
| 1670 for (i=0; i<3; ++i) { | |
| 1671 struct server_reply_item *item; | |
| 1672 if (i==0) | |
| 1673 item = req->answer; | |
| 1674 else if (i==1) | |
| 1675 item = req->authority; | |
| 1676 else | |
| 1677 item = req->additional; | |
| 1678 while (item) { | |
| 1679 r = dnsname_to_labels(buf, buf_len, j, item->name, strle
n(item->name), &table); | |
| 1680 if (r < 0) | |
| 1681 goto overflow; | |
| 1682 j = r; | |
| 1683 | |
| 1684 APPEND16(item->type); | |
| 1685 APPEND16(item->dns_question_class); | |
| 1686 APPEND32(item->ttl); | |
| 1687 if (item->is_name) { | |
| 1688 off_t len_idx = j, name_start; | |
| 1689 j += 2; | |
| 1690 name_start = j; | |
| 1691 r = dnsname_to_labels(buf, buf_len, j, item->dat
a, strlen(item->data), &table); | |
| 1692 if (r < 0) | |
| 1693 goto overflow; | |
| 1694 j = r; | |
| 1695 _t = htons( (short) (j-name_start) ); | |
| 1696 memcpy(buf+len_idx, &_t, 2); | |
| 1697 } else { | |
| 1698 APPEND16(item->datalen); | |
| 1699 if (j+item->datalen > (off_t)buf_len) | |
| 1700 goto overflow; | |
| 1701 memcpy(buf+j, item->data, item->datalen); | |
| 1702 j += item->datalen; | |
| 1703 } | |
| 1704 item = item->next; | |
| 1705 } | |
| 1706 } | |
| 1707 | |
| 1708 if (j > 512) { | |
| 1709 overflow: | |
| 1710 j = 512; | |
| 1711 buf[2] |= 0x02; /* set the truncated bit. */ | |
| 1712 } | |
| 1713 | |
| 1714 req->response_len = j; | |
| 1715 | |
| 1716 if (!(req->response = malloc(req->response_len))) { | |
| 1717 server_request_free_answers(req); | |
| 1718 dnslabel_clear(&table); | |
| 1719 return (-1); | |
| 1720 } | |
| 1721 memcpy(req->response, buf, req->response_len); | |
| 1722 server_request_free_answers(req); | |
| 1723 dnslabel_clear(&table); | |
| 1724 return (0); | |
| 1725 } | |
| 1726 | |
| 1727 /* exported function */ | |
| 1728 int | |
| 1729 evdns_server_request_respond(struct evdns_server_request *_req, int err) | |
| 1730 { | |
| 1731 struct server_request *req = TO_SERVER_REQUEST(_req); | |
| 1732 struct evdns_server_port *port = req->port; | |
| 1733 int r; | |
| 1734 if (!req->response) { | |
| 1735 if ((r = evdns_server_request_format_response(req, err))<0) | |
| 1736 return r; | |
| 1737 } | |
| 1738 | |
| 1739 r = sendto(port->socket, req->response, req->response_len, 0, | |
| 1740 (struct sockaddr*) &req->addr, req->addrlen); | |
| 1741 if (r<0) { | |
| 1742 int sock_err = last_error(port->socket); | |
| 1743 if (! error_is_eagain(sock_err)) | |
| 1744 return -1; | |
| 1745 | |
| 1746 if (port->pending_replies) { | |
| 1747 req->prev_pending = port->pending_replies->prev_pending; | |
| 1748 req->next_pending = port->pending_replies; | |
| 1749 req->prev_pending->next_pending = | |
| 1750 req->next_pending->prev_pending = req; | |
| 1751 } else { | |
| 1752 req->prev_pending = req->next_pending = req; | |
| 1753 port->pending_replies = req; | |
| 1754 port->choked = 1; | |
| 1755 | |
| 1756 (void) event_del(&port->event); | |
| 1757 event_set(&port->event, port->socket, (port->closing?0:E
V_READ) | EV_WRITE | EV_PERSIST, server_port_ready_callback, port); | |
| 1758 | |
| 1759 if (event_add(&port->event, NULL) < 0) { | |
| 1760 log(EVDNS_LOG_WARN, "Error from libevent when ad
ding event for DNS server"); | |
| 1761 } | |
| 1762 | |
| 1763 } | |
| 1764 | |
| 1765 return 1; | |
| 1766 } | |
| 1767 if (server_request_free(req)) | |
| 1768 return 0; | |
| 1769 | |
| 1770 if (port->pending_replies) | |
| 1771 server_port_flush(port); | |
| 1772 | |
| 1773 return 0; | |
| 1774 } | |
| 1775 | |
| 1776 /* Free all storage held by RRs in req. */ | |
| 1777 static void | |
| 1778 server_request_free_answers(struct server_request *req) | |
| 1779 { | |
| 1780 struct server_reply_item *victim, *next, **list; | |
| 1781 int i; | |
| 1782 for (i = 0; i < 3; ++i) { | |
| 1783 if (i==0) | |
| 1784 list = &req->answer; | |
| 1785 else if (i==1) | |
| 1786 list = &req->authority; | |
| 1787 else | |
| 1788 list = &req->additional; | |
| 1789 | |
| 1790 victim = *list; | |
| 1791 while (victim) { | |
| 1792 next = victim->next; | |
| 1793 free(victim->name); | |
| 1794 if (victim->data) | |
| 1795 free(victim->data); | |
| 1796 free(victim); | |
| 1797 victim = next; | |
| 1798 } | |
| 1799 *list = NULL; | |
| 1800 } | |
| 1801 } | |
| 1802 | |
| 1803 /* Free all storage held by req, and remove links to it. */ | |
| 1804 /* return true iff we just wound up freeing the server_port. */ | |
| 1805 static int | |
| 1806 server_request_free(struct server_request *req) | |
| 1807 { | |
| 1808 int i, rc=1; | |
| 1809 if (req->base.questions) { | |
| 1810 for (i = 0; i < req->base.nquestions; ++i) | |
| 1811 free(req->base.questions[i]); | |
| 1812 free(req->base.questions); | |
| 1813 } | |
| 1814 | |
| 1815 if (req->port) { | |
| 1816 if (req->port->pending_replies == req) { | |
| 1817 if (req->next_pending) | |
| 1818 req->port->pending_replies = req->next_pending; | |
| 1819 else | |
| 1820 req->port->pending_replies = NULL; | |
| 1821 } | |
| 1822 rc = --req->port->refcnt; | |
| 1823 } | |
| 1824 | |
| 1825 if (req->response) { | |
| 1826 free(req->response); | |
| 1827 } | |
| 1828 | |
| 1829 server_request_free_answers(req); | |
| 1830 | |
| 1831 if (req->next_pending && req->next_pending != req) { | |
| 1832 req->next_pending->prev_pending = req->prev_pending; | |
| 1833 req->prev_pending->next_pending = req->next_pending; | |
| 1834 } | |
| 1835 | |
| 1836 if (rc == 0) { | |
| 1837 server_port_free(req->port); | |
| 1838 free(req); | |
| 1839 return (1); | |
| 1840 } | |
| 1841 free(req); | |
| 1842 return (0); | |
| 1843 } | |
| 1844 | |
| 1845 /* Free all storage held by an evdns_server_port. Only called when */ | |
| 1846 static void | |
| 1847 server_port_free(struct evdns_server_port *port) | |
| 1848 { | |
| 1849 assert(port); | |
| 1850 assert(!port->refcnt); | |
| 1851 assert(!port->pending_replies); | |
| 1852 if (port->socket > 0) { | |
| 1853 CLOSE_SOCKET(port->socket); | |
| 1854 port->socket = -1; | |
| 1855 } | |
| 1856 (void) event_del(&port->event); | |
| 1857 /* XXXX actually free the port? -NM */ | |
| 1858 } | |
| 1859 | |
| 1860 /* exported function */ | |
| 1861 int | |
| 1862 evdns_server_request_drop(struct evdns_server_request *_req) | |
| 1863 { | |
| 1864 struct server_request *req = TO_SERVER_REQUEST(_req); | |
| 1865 server_request_free(req); | |
| 1866 return 0; | |
| 1867 } | |
| 1868 | |
| 1869 /* exported function */ | |
| 1870 int | |
| 1871 evdns_server_request_get_requesting_addr(struct evdns_server_request *_req, stru
ct sockaddr *sa, int addr_len) | |
| 1872 { | |
| 1873 struct server_request *req = TO_SERVER_REQUEST(_req); | |
| 1874 if (addr_len < (int)req->addrlen) | |
| 1875 return -1; | |
| 1876 memcpy(sa, &(req->addr), req->addrlen); | |
| 1877 return req->addrlen; | |
| 1878 } | |
| 1879 | |
| 1880 #undef APPEND16 | |
| 1881 #undef APPEND32 | |
| 1882 | |
| 1883 /* this is a libevent callback function which is called when a request */ | |
| 1884 /* has timed out. */ | |
| 1885 static void | |
| 1886 evdns_request_timeout_callback(int fd, short events, void *arg) { | |
| 1887 struct request *const req = (struct request *) arg; | |
| 1888 (void) fd; | |
| 1889 (void) events; | |
| 1890 | |
| 1891 log(EVDNS_LOG_DEBUG, "Request %lx timed out", (unsigned long) arg); | |
| 1892 | |
| 1893 req->ns->timedout++; | |
| 1894 if (req->ns->timedout > global_max_nameserver_timeout) { | |
| 1895 req->ns->timedout = 0; | |
| 1896 nameserver_failed(req->ns, "request timed out."); | |
| 1897 } | |
| 1898 | |
| 1899 (void) evtimer_del(&req->timeout_event); | |
| 1900 if (req->tx_count >= global_max_retransmits) { | |
| 1901 /* this request has failed */ | |
| 1902 reply_callback(req, 0, DNS_ERR_TIMEOUT, NULL); | |
| 1903 request_finished(req, &req_head); | |
| 1904 } else { | |
| 1905 /* retransmit it */ | |
| 1906 evdns_request_transmit(req); | |
| 1907 } | |
| 1908 } | |
| 1909 | |
| 1910 /* try to send a request to a given server. */ | |
| 1911 /* */ | |
| 1912 /* return: */ | |
| 1913 /* 0 ok */ | |
| 1914 /* 1 temporary failure */ | |
| 1915 /* 2 other failure */ | |
| 1916 static int | |
| 1917 evdns_request_transmit_to(struct request *req, struct nameserver *server) { | |
| 1918 struct sockaddr_in sin; | |
| 1919 int r; | |
| 1920 memset(&sin, 0, sizeof(sin)); | |
| 1921 sin.sin_addr.s_addr = req->ns->address; | |
| 1922 sin.sin_port = req->ns->port; | |
| 1923 sin.sin_family = AF_INET; | |
| 1924 | |
| 1925 r = sendto(server->socket, req->request, req->request_len, 0, | |
| 1926 (struct sockaddr*)&sin, sizeof(sin)); | |
| 1927 if (r < 0) { | |
| 1928 int err = last_error(server->socket); | |
| 1929 if (error_is_eagain(err)) return 1; | |
| 1930 nameserver_failed(req->ns, strerror(err)); | |
| 1931 return 2; | |
| 1932 } else if (r != (int)req->request_len) { | |
| 1933 return 1; /* short write */ | |
| 1934 } else { | |
| 1935 return 0; | |
| 1936 } | |
| 1937 } | |
| 1938 | |
| 1939 /* try to send a request, updating the fields of the request */ | |
| 1940 /* as needed */ | |
| 1941 /* */ | |
| 1942 /* return: */ | |
| 1943 /* 0 ok */ | |
| 1944 /* 1 failed */ | |
| 1945 static int | |
| 1946 evdns_request_transmit(struct request *req) { | |
| 1947 int retcode = 0, r; | |
| 1948 | |
| 1949 /* if we fail to send this packet then this flag marks it */ | |
| 1950 /* for evdns_transmit */ | |
| 1951 req->transmit_me = 1; | |
| 1952 if (req->trans_id == 0xffff) abort(); | |
| 1953 | |
| 1954 if (req->ns->choked) { | |
| 1955 /* don't bother trying to write to a socket */ | |
| 1956 /* which we have had EAGAIN from */ | |
| 1957 return 1; | |
| 1958 } | |
| 1959 | |
| 1960 r = evdns_request_transmit_to(req, req->ns); | |
| 1961 switch (r) { | |
| 1962 case 1: | |
| 1963 /* temp failure */ | |
| 1964 req->ns->choked = 1; | |
| 1965 nameserver_write_waiting(req->ns, 1); | |
| 1966 return 1; | |
| 1967 case 2: | |
| 1968 /* failed in some other way */ | |
| 1969 retcode = 1; | |
| 1970 /* fall through */ | |
| 1971 default: | |
| 1972 /* all ok */ | |
| 1973 log(EVDNS_LOG_DEBUG, | |
| 1974 "Setting timeout for request %lx", (unsigned long) req); | |
| 1975 if (evtimer_add(&req->timeout_event, &global_timeout) < 0) { | |
| 1976 log(EVDNS_LOG_WARN, | |
| 1977 "Error from libevent when adding timer for request %lx", | |
| 1978 (unsigned long) req); | |
| 1979 /* ???? Do more? */ | |
| 1980 } | |
| 1981 req->tx_count++; | |
| 1982 req->transmit_me = 0; | |
| 1983 return retcode; | |
| 1984 } | |
| 1985 } | |
| 1986 | |
| 1987 static void | |
| 1988 nameserver_probe_callback(int result, char type, int count, int ttl, void *addre
sses, void *arg) { | |
| 1989 struct nameserver *const ns = (struct nameserver *) arg; | |
| 1990 (void) type; | |
| 1991 (void) count; | |
| 1992 (void) ttl; | |
| 1993 (void) addresses; | |
| 1994 | |
| 1995 if (result == DNS_ERR_NONE || result == DNS_ERR_NOTEXIST) { | |
| 1996 /* this is a good reply */ | |
| 1997 nameserver_up(ns); | |
| 1998 } else nameserver_probe_failed(ns); | |
| 1999 } | |
| 2000 | |
| 2001 static void | |
| 2002 nameserver_send_probe(struct nameserver *const ns) { | |
| 2003 struct request *req; | |
| 2004 /* here we need to send a probe to a given nameserver */ | |
| 2005 /* in the hope that it is up now. */ | |
| 2006 | |
| 2007 log(EVDNS_LOG_DEBUG, "Sending probe to %s", debug_ntoa(ns->address)); | |
| 2008 | |
| 2009 req = request_new(TYPE_A, "www.google.com", DNS_QUERY_NO_SEARCH, nameser
ver_probe_callback, ns); | |
| 2010 if (!req) return; | |
| 2011 /* we force this into the inflight queue no matter what */ | |
| 2012 request_trans_id_set(req, transaction_id_pick()); | |
| 2013 req->ns = ns; | |
| 2014 request_submit(req); | |
| 2015 } | |
| 2016 | |
| 2017 /* returns: */ | |
| 2018 /* 0 didn't try to transmit anything */ | |
| 2019 /* 1 tried to transmit something */ | |
| 2020 static int | |
| 2021 evdns_transmit(void) { | |
| 2022 char did_try_to_transmit = 0; | |
| 2023 | |
| 2024 if (req_head) { | |
| 2025 struct request *const started_at = req_head, *req = req_head; | |
| 2026 /* first transmit all the requests which are currently waiting *
/ | |
| 2027 do { | |
| 2028 if (req->transmit_me) { | |
| 2029 did_try_to_transmit = 1; | |
| 2030 evdns_request_transmit(req); | |
| 2031 } | |
| 2032 | |
| 2033 req = req->next; | |
| 2034 } while (req != started_at); | |
| 2035 } | |
| 2036 | |
| 2037 return did_try_to_transmit; | |
| 2038 } | |
| 2039 | |
| 2040 /* exported function */ | |
| 2041 int | |
| 2042 evdns_count_nameservers(void) | |
| 2043 { | |
| 2044 const struct nameserver *server = server_head; | |
| 2045 int n = 0; | |
| 2046 if (!server) | |
| 2047 return 0; | |
| 2048 do { | |
| 2049 ++n; | |
| 2050 server = server->next; | |
| 2051 } while (server != server_head); | |
| 2052 return n; | |
| 2053 } | |
| 2054 | |
| 2055 /* exported function */ | |
| 2056 int | |
| 2057 evdns_clear_nameservers_and_suspend(void) | |
| 2058 { | |
| 2059 struct nameserver *server = server_head, *started_at = server_head; | |
| 2060 struct request *req = req_head, *req_started_at = req_head; | |
| 2061 | |
| 2062 if (!server) | |
| 2063 return 0; | |
| 2064 while (1) { | |
| 2065 struct nameserver *next = server->next; | |
| 2066 (void) event_del(&server->event); | |
| 2067 if (evtimer_initialized(&server->timeout_event)) | |
| 2068 (void) evtimer_del(&server->timeout_event); | |
| 2069 if (server->socket >= 0) | |
| 2070 CLOSE_SOCKET(server->socket); | |
| 2071 free(server); | |
| 2072 if (next == started_at) | |
| 2073 break; | |
| 2074 server = next; | |
| 2075 } | |
| 2076 server_head = NULL; | |
| 2077 global_good_nameservers = 0; | |
| 2078 | |
| 2079 while (req) { | |
| 2080 struct request *next = req->next; | |
| 2081 req->tx_count = req->reissue_count = 0; | |
| 2082 req->ns = NULL; | |
| 2083 /* ???? What to do about searches? */ | |
| 2084 (void) evtimer_del(&req->timeout_event); | |
| 2085 req->trans_id = 0; | |
| 2086 req->transmit_me = 0; | |
| 2087 | |
| 2088 global_requests_waiting++; | |
| 2089 evdns_request_insert(req, &req_waiting_head); | |
| 2090 /* We want to insert these suspended elements at the front of | |
| 2091 * the waiting queue, since they were pending before any of | |
| 2092 * the waiting entries were added. This is a circular list, | |
| 2093 * so we can just shift the start back by one.*/ | |
| 2094 req_waiting_head = req_waiting_head->prev; | |
| 2095 | |
| 2096 if (next == req_started_at) | |
| 2097 break; | |
| 2098 req = next; | |
| 2099 } | |
| 2100 req_head = NULL; | |
| 2101 global_requests_inflight = 0; | |
| 2102 | |
| 2103 return 0; | |
| 2104 } | |
| 2105 | |
| 2106 | |
| 2107 /* exported function */ | |
| 2108 int | |
| 2109 evdns_resume(void) | |
| 2110 { | |
| 2111 evdns_requests_pump_waiting_queue(); | |
| 2112 return 0; | |
| 2113 } | |
| 2114 | |
| 2115 static int | |
| 2116 _evdns_nameserver_add_impl(unsigned long int address, int port) { | |
| 2117 /* first check to see if we already have this nameserver */ | |
| 2118 | |
| 2119 const struct nameserver *server = server_head, *const started_at = serve
r_head; | |
| 2120 struct nameserver *ns; | |
| 2121 int err = 0; | |
| 2122 if (server) { | |
| 2123 do { | |
| 2124 if (server->address == address) return 3; | |
| 2125 server = server->next; | |
| 2126 } while (server != started_at); | |
| 2127 } | |
| 2128 | |
| 2129 ns = (struct nameserver *) malloc(sizeof(struct nameserver)); | |
| 2130 if (!ns) return -1; | |
| 2131 | |
| 2132 memset(ns, 0, sizeof(struct nameserver)); | |
| 2133 | |
| 2134 evtimer_set(&ns->timeout_event, nameserver_prod_callback, ns); | |
| 2135 | |
| 2136 ns->socket = socket(PF_INET, SOCK_DGRAM, 0); | |
| 2137 if (ns->socket < 0) { err = 1; goto out1; } | |
| 2138 FD_CLOSEONEXEC(ns->socket); | |
| 2139 evutil_make_socket_nonblocking(ns->socket); | |
| 2140 | |
| 2141 ns->address = address; | |
| 2142 ns->port = htons(port); | |
| 2143 ns->state = 1; | |
| 2144 event_set(&ns->event, ns->socket, EV_READ | EV_PERSIST, nameserver_ready
_callback, ns); | |
| 2145 if (event_add(&ns->event, NULL) < 0) { | |
| 2146 err = 2; | |
| 2147 goto out2; | |
| 2148 } | |
| 2149 | |
| 2150 log(EVDNS_LOG_DEBUG, "Added nameserver %s", debug_ntoa(address)); | |
| 2151 | |
| 2152 /* insert this nameserver into the list of them */ | |
| 2153 if (!server_head) { | |
| 2154 ns->next = ns->prev = ns; | |
| 2155 server_head = ns; | |
| 2156 } else { | |
| 2157 ns->next = server_head->next; | |
| 2158 ns->prev = server_head; | |
| 2159 server_head->next = ns; | |
| 2160 if (server_head->prev == server_head) { | |
| 2161 server_head->prev = ns; | |
| 2162 } | |
| 2163 } | |
| 2164 | |
| 2165 global_good_nameservers++; | |
| 2166 | |
| 2167 return 0; | |
| 2168 | |
| 2169 out2: | |
| 2170 CLOSE_SOCKET(ns->socket); | |
| 2171 out1: | |
| 2172 free(ns); | |
| 2173 log(EVDNS_LOG_WARN, "Unable to add nameserver %s: error %d", debug_ntoa(
address), err); | |
| 2174 return err; | |
| 2175 } | |
| 2176 | |
| 2177 /* exported function */ | |
| 2178 int | |
| 2179 evdns_nameserver_add(unsigned long int address) { | |
| 2180 return _evdns_nameserver_add_impl(address, 53); | |
| 2181 } | |
| 2182 | |
| 2183 /* exported function */ | |
| 2184 int | |
| 2185 evdns_nameserver_ip_add(const char *ip_as_string) { | |
| 2186 struct in_addr ina; | |
| 2187 int port; | |
| 2188 char buf[20]; | |
| 2189 const char *cp; | |
| 2190 cp = strchr(ip_as_string, ':'); | |
| 2191 if (! cp) { | |
| 2192 cp = ip_as_string; | |
| 2193 port = 53; | |
| 2194 } else { | |
| 2195 port = strtoint(cp+1); | |
| 2196 if (port < 0 || port > 65535) { | |
| 2197 return 4; | |
| 2198 } | |
| 2199 if ((cp-ip_as_string) >= (int)sizeof(buf)) { | |
| 2200 return 4; | |
| 2201 } | |
| 2202 memcpy(buf, ip_as_string, cp-ip_as_string); | |
| 2203 buf[cp-ip_as_string] = '\0'; | |
| 2204 cp = buf; | |
| 2205 } | |
| 2206 if (!inet_aton(cp, &ina)) { | |
| 2207 return 4; | |
| 2208 } | |
| 2209 return _evdns_nameserver_add_impl(ina.s_addr, port); | |
| 2210 } | |
| 2211 | |
| 2212 /* insert into the tail of the queue */ | |
| 2213 static void | |
| 2214 evdns_request_insert(struct request *req, struct request **head) { | |
| 2215 if (!*head) { | |
| 2216 *head = req; | |
| 2217 req->next = req->prev = req; | |
| 2218 return; | |
| 2219 } | |
| 2220 | |
| 2221 req->prev = (*head)->prev; | |
| 2222 req->prev->next = req; | |
| 2223 req->next = *head; | |
| 2224 (*head)->prev = req; | |
| 2225 } | |
| 2226 | |
| 2227 static int | |
| 2228 string_num_dots(const char *s) { | |
| 2229 int count = 0; | |
| 2230 while ((s = strchr(s, '.'))) { | |
| 2231 s++; | |
| 2232 count++; | |
| 2233 } | |
| 2234 return count; | |
| 2235 } | |
| 2236 | |
| 2237 static struct request * | |
| 2238 request_new(int type, const char *name, int flags, | |
| 2239 evdns_callback_type callback, void *user_ptr) { | |
| 2240 const char issuing_now = | |
| 2241 (global_requests_inflight < global_max_requests_inflight) ? 1 : 0; | |
| 2242 | |
| 2243 const int name_len = strlen(name); | |
| 2244 const int request_max_len = evdns_request_len(name_len); | |
| 2245 const u16 trans_id = issuing_now ? transaction_id_pick() : 0xffff; | |
| 2246 /* the request data is alloced in a single block with the header */ | |
| 2247 struct request *const req = | |
| 2248 (struct request *) malloc(sizeof(struct request) + request_max_len); | |
| 2249 int rlen; | |
| 2250 (void) flags; | |
| 2251 | |
| 2252 if (!req) return NULL; | |
| 2253 memset(req, 0, sizeof(struct request)); | |
| 2254 | |
| 2255 evtimer_set(&req->timeout_event, evdns_request_timeout_callback, req); | |
| 2256 | |
| 2257 /* request data lives just after the header */ | |
| 2258 req->request = ((u8 *) req) + sizeof(struct request); | |
| 2259 /* denotes that the request data shouldn't be free()ed */ | |
| 2260 req->request_appended = 1; | |
| 2261 rlen = evdns_request_data_build(name, name_len, trans_id, | |
| 2262 type, CLASS_INET, req->request, request_max_len); | |
| 2263 if (rlen < 0) | |
| 2264 goto err1; | |
| 2265 req->request_len = rlen; | |
| 2266 req->trans_id = trans_id; | |
| 2267 req->tx_count = 0; | |
| 2268 req->request_type = type; | |
| 2269 req->user_pointer = user_ptr; | |
| 2270 req->user_callback = callback; | |
| 2271 req->ns = issuing_now ? nameserver_pick() : NULL; | |
| 2272 req->next = req->prev = NULL; | |
| 2273 | |
| 2274 return req; | |
| 2275 err1: | |
| 2276 free(req); | |
| 2277 return NULL; | |
| 2278 } | |
| 2279 | |
| 2280 static void | |
| 2281 request_submit(struct request *const req) { | |
| 2282 if (req->ns) { | |
| 2283 /* if it has a nameserver assigned then this is going */ | |
| 2284 /* straight into the inflight queue */ | |
| 2285 evdns_request_insert(req, &req_head); | |
| 2286 global_requests_inflight++; | |
| 2287 evdns_request_transmit(req); | |
| 2288 } else { | |
| 2289 evdns_request_insert(req, &req_waiting_head); | |
| 2290 global_requests_waiting++; | |
| 2291 } | |
| 2292 } | |
| 2293 | |
| 2294 /* exported function */ | |
| 2295 int evdns_resolve_ipv4(const char *name, int flags, | |
| 2296 evdns_callback_type callback, void *ptr) { | |
| 2297 log(EVDNS_LOG_DEBUG, "Resolve requested for %s", name); | |
| 2298 if (flags & DNS_QUERY_NO_SEARCH) { | |
| 2299 struct request *const req = | |
| 2300 request_new(TYPE_A, name, flags, callback, ptr); | |
| 2301 if (req == NULL) | |
| 2302 return (1); | |
| 2303 request_submit(req); | |
| 2304 return (0); | |
| 2305 } else { | |
| 2306 return (search_request_new(TYPE_A, name, flags, callback, ptr)); | |
| 2307 } | |
| 2308 } | |
| 2309 | |
| 2310 /* exported function */ | |
| 2311 int evdns_resolve_ipv6(const char *name, int flags, | |
| 2312 evdns_callback_type callback, void *p
tr) { | |
| 2313 log(EVDNS_LOG_DEBUG, "Resolve requested for %s", name); | |
| 2314 if (flags & DNS_QUERY_NO_SEARCH) { | |
| 2315 struct request *const req = | |
| 2316 request_new(TYPE_AAAA, name, flags, callback, ptr); | |
| 2317 if (req == NULL) | |
| 2318 return (1); | |
| 2319 request_submit(req); | |
| 2320 return (0); | |
| 2321 } else { | |
| 2322 return (search_request_new(TYPE_AAAA, name, flags, callback, ptr
)); | |
| 2323 } | |
| 2324 } | |
| 2325 | |
| 2326 int evdns_resolve_reverse(const struct in_addr *in, int flags, evdns_callback_ty
pe callback, void *ptr) { | |
| 2327 char buf[32]; | |
| 2328 struct request *req; | |
| 2329 u32 a; | |
| 2330 assert(in); | |
| 2331 a = ntohl(in->s_addr); | |
| 2332 evutil_snprintf(buf, sizeof(buf), "%d.%d.%d.%d.in-addr.arpa", | |
| 2333 (int)(u8)((a )&0xff), | |
| 2334 (int)(u8)((a>>8 )&0xff), | |
| 2335 (int)(u8)((a>>16)&0xff), | |
| 2336 (int)(u8)((a>>24)&0xff)); | |
| 2337 log(EVDNS_LOG_DEBUG, "Resolve requested for %s (reverse)", buf); | |
| 2338 req = request_new(TYPE_PTR, buf, flags, callback, ptr); | |
| 2339 if (!req) return 1; | |
| 2340 request_submit(req); | |
| 2341 return 0; | |
| 2342 } | |
| 2343 | |
| 2344 int evdns_resolve_reverse_ipv6(const struct in6_addr *in, int flags, evdns_callb
ack_type callback, void *ptr) { | |
| 2345 /* 32 nybbles, 32 periods, "ip6.arpa", NUL. */ | |
| 2346 char buf[73]; | |
| 2347 char *cp; | |
| 2348 struct request *req; | |
| 2349 int i; | |
| 2350 assert(in); | |
| 2351 cp = buf; | |
| 2352 for (i=15; i >= 0; --i) { | |
| 2353 u8 byte = in->s6_addr[i]; | |
| 2354 *cp++ = "0123456789abcdef"[byte & 0x0f]; | |
| 2355 *cp++ = '.'; | |
| 2356 *cp++ = "0123456789abcdef"[byte >> 4]; | |
| 2357 *cp++ = '.'; | |
| 2358 } | |
| 2359 assert(cp + strlen("ip6.arpa") < buf+sizeof(buf)); | |
| 2360 memcpy(cp, "ip6.arpa", strlen("ip6.arpa")+1); | |
| 2361 log(EVDNS_LOG_DEBUG, "Resolve requested for %s (reverse)", buf); | |
| 2362 req = request_new(TYPE_PTR, buf, flags, callback, ptr); | |
| 2363 if (!req) return 1; | |
| 2364 request_submit(req); | |
| 2365 return 0; | |
| 2366 } | |
| 2367 | |
| 2368 /*/////////////////////////////////////////////////////////////////// */ | |
| 2369 /* Search support */ | |
| 2370 /* */ | |
| 2371 /* the libc resolver has support for searching a number of domains */ | |
| 2372 /* to find a name. If nothing else then it takes the single domain */ | |
| 2373 /* from the gethostname() call. */ | |
| 2374 /* */ | |
| 2375 /* It can also be configured via the domain and search options in a */ | |
| 2376 /* resolv.conf. */ | |
| 2377 /* */ | |
| 2378 /* The ndots option controls how many dots it takes for the resolver */ | |
| 2379 /* to decide that a name is non-local and so try a raw lookup first. */ | |
| 2380 | |
| 2381 struct search_domain { | |
| 2382 int len; | |
| 2383 struct search_domain *next; | |
| 2384 /* the text string is appended to this structure */ | |
| 2385 }; | |
| 2386 | |
| 2387 struct search_state { | |
| 2388 int refcount; | |
| 2389 int ndots; | |
| 2390 int num_domains; | |
| 2391 struct search_domain *head; | |
| 2392 }; | |
| 2393 | |
| 2394 static struct search_state *global_search_state = NULL; | |
| 2395 | |
| 2396 static void | |
| 2397 search_state_decref(struct search_state *const state) { | |
| 2398 if (!state) return; | |
| 2399 state->refcount--; | |
| 2400 if (!state->refcount) { | |
| 2401 struct search_domain *next, *dom; | |
| 2402 for (dom = state->head; dom; dom = next) { | |
| 2403 next = dom->next; | |
| 2404 free(dom); | |
| 2405 } | |
| 2406 free(state); | |
| 2407 } | |
| 2408 } | |
| 2409 | |
| 2410 static struct search_state * | |
| 2411 search_state_new(void) { | |
| 2412 struct search_state *state = (struct search_state *) malloc(sizeof(struc
t search_state)); | |
| 2413 if (!state) return NULL; | |
| 2414 memset(state, 0, sizeof(struct search_state)); | |
| 2415 state->refcount = 1; | |
| 2416 state->ndots = 1; | |
| 2417 | |
| 2418 return state; | |
| 2419 } | |
| 2420 | |
| 2421 static void | |
| 2422 search_postfix_clear(void) { | |
| 2423 search_state_decref(global_search_state); | |
| 2424 | |
| 2425 global_search_state = search_state_new(); | |
| 2426 } | |
| 2427 | |
| 2428 /* exported function */ | |
| 2429 void | |
| 2430 evdns_search_clear(void) { | |
| 2431 search_postfix_clear(); | |
| 2432 } | |
| 2433 | |
| 2434 static void | |
| 2435 search_postfix_add(const char *domain) { | |
| 2436 int domain_len; | |
| 2437 struct search_domain *sdomain; | |
| 2438 while (domain[0] == '.') domain++; | |
| 2439 domain_len = strlen(domain); | |
| 2440 | |
| 2441 if (!global_search_state) global_search_state = search_state_new(); | |
| 2442 if (!global_search_state) return; | |
| 2443 global_search_state->num_domains++; | |
| 2444 | |
| 2445 sdomain = (struct search_domain *) malloc(sizeof(struct search_domain) +
domain_len); | |
| 2446 if (!sdomain) return; | |
| 2447 memcpy( ((u8 *) sdomain) + sizeof(struct search_domain), domain, domain_
len); | |
| 2448 sdomain->next = global_search_state->head; | |
| 2449 sdomain->len = domain_len; | |
| 2450 | |
| 2451 global_search_state->head = sdomain; | |
| 2452 } | |
| 2453 | |
| 2454 /* reverse the order of members in the postfix list. This is needed because, */ | |
| 2455 /* when parsing resolv.conf we push elements in the wrong order */ | |
| 2456 static void | |
| 2457 search_reverse(void) { | |
| 2458 struct search_domain *cur, *prev = NULL, *next; | |
| 2459 cur = global_search_state->head; | |
| 2460 while (cur) { | |
| 2461 next = cur->next; | |
| 2462 cur->next = prev; | |
| 2463 prev = cur; | |
| 2464 cur = next; | |
| 2465 } | |
| 2466 | |
| 2467 global_search_state->head = prev; | |
| 2468 } | |
| 2469 | |
| 2470 /* exported function */ | |
| 2471 void | |
| 2472 evdns_search_add(const char *domain) { | |
| 2473 search_postfix_add(domain); | |
| 2474 } | |
| 2475 | |
| 2476 /* exported function */ | |
| 2477 void | |
| 2478 evdns_search_ndots_set(const int ndots) { | |
| 2479 if (!global_search_state) global_search_state = search_state_new(); | |
| 2480 if (!global_search_state) return; | |
| 2481 global_search_state->ndots = ndots; | |
| 2482 } | |
| 2483 | |
| 2484 static void | |
| 2485 search_set_from_hostname(void) { | |
| 2486 char hostname[HOST_NAME_MAX + 1], *domainname; | |
| 2487 | |
| 2488 search_postfix_clear(); | |
| 2489 if (gethostname(hostname, sizeof(hostname))) return; | |
| 2490 domainname = strchr(hostname, '.'); | |
| 2491 if (!domainname) return; | |
| 2492 search_postfix_add(domainname); | |
| 2493 } | |
| 2494 | |
| 2495 /* warning: returns malloced string */ | |
| 2496 static char * | |
| 2497 search_make_new(const struct search_state *const state, int n, const char *const
base_name) { | |
| 2498 const int base_len = strlen(base_name); | |
| 2499 const char need_to_append_dot = base_name[base_len - 1] == '.' ? 0 : 1; | |
| 2500 struct search_domain *dom; | |
| 2501 | |
| 2502 for (dom = state->head; dom; dom = dom->next) { | |
| 2503 if (!n--) { | |
| 2504 /* this is the postfix we want */ | |
| 2505 /* the actual postfix string is kept at the end of the s
tructure */ | |
| 2506 const u8 *const postfix = ((u8 *) dom) + sizeof(struct s
earch_domain); | |
| 2507 const int postfix_len = dom->len; | |
| 2508 char *const newname = (char *) malloc(base_len + need_to
_append_dot + postfix_len + 1); | |
| 2509 if (!newname) return NULL; | |
| 2510 memcpy(newname, base_name, base_len); | |
| 2511 if (need_to_append_dot) newname[base_len] = '.'; | |
| 2512 memcpy(newname + base_len + need_to_append_dot, postfix,
postfix_len); | |
| 2513 newname[base_len + need_to_append_dot + postfix_len] = 0
; | |
| 2514 return newname; | |
| 2515 } | |
| 2516 } | |
| 2517 | |
| 2518 /* we ran off the end of the list and still didn't find the requested st
ring */ | |
| 2519 abort(); | |
| 2520 return NULL; /* unreachable; stops warnings in some compilers. */ | |
| 2521 } | |
| 2522 | |
| 2523 static int | |
| 2524 search_request_new(int type, const char *const name, int flags, evdns_callback_t
ype user_callback, void *user_arg) { | |
| 2525 assert(type == TYPE_A || type == TYPE_AAAA); | |
| 2526 if ( ((flags & DNS_QUERY_NO_SEARCH) == 0) && | |
| 2527 global_search_state && | |
| 2528 global_search_state->num_domains) { | |
| 2529 /* we have some domains to search */ | |
| 2530 struct request *req; | |
| 2531 if (string_num_dots(name) >= global_search_state->ndots) { | |
| 2532 req = request_new(type, name, flags, user_callback, user
_arg); | |
| 2533 if (!req) return 1; | |
| 2534 req->search_index = -1; | |
| 2535 } else { | |
| 2536 char *const new_name = search_make_new(global_search_sta
te, 0, name); | |
| 2537 if (!new_name) return 1; | |
| 2538 req = request_new(type, new_name, flags, user_callback,
user_arg); | |
| 2539 free(new_name); | |
| 2540 if (!req) return 1; | |
| 2541 req->search_index = 0; | |
| 2542 } | |
| 2543 req->search_origname = strdup(name); | |
| 2544 req->search_state = global_search_state; | |
| 2545 req->search_flags = flags; | |
| 2546 global_search_state->refcount++; | |
| 2547 request_submit(req); | |
| 2548 return 0; | |
| 2549 } else { | |
| 2550 struct request *const req = request_new(type, name, flags, user_
callback, user_arg); | |
| 2551 if (!req) return 1; | |
| 2552 request_submit(req); | |
| 2553 return 0; | |
| 2554 } | |
| 2555 } | |
| 2556 | |
| 2557 /* this is called when a request has failed to find a name. We need to check */ | |
| 2558 /* if it is part of a search and, if so, try the next name in the list */ | |
| 2559 /* returns: */ | |
| 2560 /* 0 another request has been submitted */ | |
| 2561 /* 1 no more requests needed */ | |
| 2562 static int | |
| 2563 search_try_next(struct request *const req) { | |
| 2564 if (req->search_state) { | |
| 2565 /* it is part of a search */ | |
| 2566 char *new_name; | |
| 2567 struct request *newreq; | |
| 2568 req->search_index++; | |
| 2569 if (req->search_index >= req->search_state->num_domains) { | |
| 2570 /* no more postfixes to try, however we may need to try
*/ | |
| 2571 /* this name without a postfix */ | |
| 2572 if (string_num_dots(req->search_origname) < req->search_
state->ndots) { | |
| 2573 /* yep, we need to try it raw */ | |
| 2574 newreq = request_new(req->request_type, req->sea
rch_origname, req->search_flags, req->user_callback, req->user_pointer); | |
| 2575 log(EVDNS_LOG_DEBUG, "Search: trying raw query %
s", req->search_origname); | |
| 2576 if (newreq) { | |
| 2577 request_submit(newreq); | |
| 2578 return 0; | |
| 2579 } | |
| 2580 } | |
| 2581 return 1; | |
| 2582 } | |
| 2583 | |
| 2584 new_name = search_make_new(req->search_state, req->search_index,
req->search_origname); | |
| 2585 if (!new_name) return 1; | |
| 2586 log(EVDNS_LOG_DEBUG, "Search: now trying %s (%d)", new_name, req
->search_index); | |
| 2587 newreq = request_new(req->request_type, new_name, req->search_fl
ags, req->user_callback, req->user_pointer); | |
| 2588 free(new_name); | |
| 2589 if (!newreq) return 1; | |
| 2590 newreq->search_origname = req->search_origname; | |
| 2591 req->search_origname = NULL; | |
| 2592 newreq->search_state = req->search_state; | |
| 2593 newreq->search_flags = req->search_flags; | |
| 2594 newreq->search_index = req->search_index; | |
| 2595 newreq->search_state->refcount++; | |
| 2596 request_submit(newreq); | |
| 2597 return 0; | |
| 2598 } | |
| 2599 return 1; | |
| 2600 } | |
| 2601 | |
| 2602 static void | |
| 2603 search_request_finished(struct request *const req) { | |
| 2604 if (req->search_state) { | |
| 2605 search_state_decref(req->search_state); | |
| 2606 req->search_state = NULL; | |
| 2607 } | |
| 2608 if (req->search_origname) { | |
| 2609 free(req->search_origname); | |
| 2610 req->search_origname = NULL; | |
| 2611 } | |
| 2612 } | |
| 2613 | |
| 2614 /*/////////////////////////////////////////////////////////////////// */ | |
| 2615 /* Parsing resolv.conf files */ | |
| 2616 | |
| 2617 static void | |
| 2618 evdns_resolv_set_defaults(int flags) { | |
| 2619 /* if the file isn't found then we assume a local resolver */ | |
| 2620 if (flags & DNS_OPTION_SEARCH) search_set_from_hostname(); | |
| 2621 if (flags & DNS_OPTION_NAMESERVERS) evdns_nameserver_ip_add("127.0.0.1")
; | |
| 2622 } | |
| 2623 | |
| 2624 #ifndef HAVE_STRTOK_R | |
| 2625 static char * | |
| 2626 strtok_r(char *s, const char *delim, char **state) { | |
| 2627 return strtok(s, delim); | |
| 2628 } | |
| 2629 #endif | |
| 2630 | |
| 2631 /* helper version of atoi which returns -1 on error */ | |
| 2632 static int | |
| 2633 strtoint(const char *const str) { | |
| 2634 char *endptr; | |
| 2635 const int r = strtol(str, &endptr, 10); | |
| 2636 if (*endptr) return -1; | |
| 2637 return r; | |
| 2638 } | |
| 2639 | |
| 2640 /* helper version of atoi that returns -1 on error and clips to bounds. */ | |
| 2641 static int | |
| 2642 strtoint_clipped(const char *const str, int min, int max) | |
| 2643 { | |
| 2644 int r = strtoint(str); | |
| 2645 if (r == -1) | |
| 2646 return r; | |
| 2647 else if (r<min) | |
| 2648 return min; | |
| 2649 else if (r>max) | |
| 2650 return max; | |
| 2651 else | |
| 2652 return r; | |
| 2653 } | |
| 2654 | |
| 2655 /* exported function */ | |
| 2656 int | |
| 2657 evdns_set_option(const char *option, const char *val, int flags) | |
| 2658 { | |
| 2659 if (!strncmp(option, "ndots:", 6)) { | |
| 2660 const int ndots = strtoint(val); | |
| 2661 if (ndots == -1) return -1; | |
| 2662 if (!(flags & DNS_OPTION_SEARCH)) return 0; | |
| 2663 log(EVDNS_LOG_DEBUG, "Setting ndots to %d", ndots); | |
| 2664 if (!global_search_state) global_search_state = search_state_new
(); | |
| 2665 if (!global_search_state) return -1; | |
| 2666 global_search_state->ndots = ndots; | |
| 2667 } else if (!strncmp(option, "timeout:", 8)) { | |
| 2668 const int timeout = strtoint(val); | |
| 2669 if (timeout == -1) return -1; | |
| 2670 if (!(flags & DNS_OPTION_MISC)) return 0; | |
| 2671 log(EVDNS_LOG_DEBUG, "Setting timeout to %d", timeout); | |
| 2672 global_timeout.tv_sec = timeout; | |
| 2673 } else if (!strncmp(option, "max-timeouts:", 12)) { | |
| 2674 const int maxtimeout = strtoint_clipped(val, 1, 255); | |
| 2675 if (maxtimeout == -1) return -1; | |
| 2676 if (!(flags & DNS_OPTION_MISC)) return 0; | |
| 2677 log(EVDNS_LOG_DEBUG, "Setting maximum allowed timeouts to %d", | |
| 2678 maxtimeout); | |
| 2679 global_max_nameserver_timeout = maxtimeout; | |
| 2680 } else if (!strncmp(option, "max-inflight:", 13)) { | |
| 2681 const int maxinflight = strtoint_clipped(val, 1, 65000); | |
| 2682 if (maxinflight == -1) return -1; | |
| 2683 if (!(flags & DNS_OPTION_MISC)) return 0; | |
| 2684 log(EVDNS_LOG_DEBUG, "Setting maximum inflight requests to %d", | |
| 2685 maxinflight); | |
| 2686 global_max_requests_inflight = maxinflight; | |
| 2687 } else if (!strncmp(option, "attempts:", 9)) { | |
| 2688 int retries = strtoint(val); | |
| 2689 if (retries == -1) return -1; | |
| 2690 if (retries > 255) retries = 255; | |
| 2691 if (!(flags & DNS_OPTION_MISC)) return 0; | |
| 2692 log(EVDNS_LOG_DEBUG, "Setting retries to %d", retries); | |
| 2693 global_max_retransmits = retries; | |
| 2694 } | |
| 2695 return 0; | |
| 2696 } | |
| 2697 | |
| 2698 static void | |
| 2699 resolv_conf_parse_line(char *const start, int flags) { | |
| 2700 char *strtok_state; | |
| 2701 static const char *const delims = " \t"; | |
| 2702 #define NEXT_TOKEN strtok_r(NULL, delims, &strtok_state) | |
| 2703 | |
| 2704 char *const first_token = strtok_r(start, delims, &strtok_state); | |
| 2705 if (!first_token) return; | |
| 2706 | |
| 2707 if (!strcmp(first_token, "nameserver") && (flags & DNS_OPTION_NAMESERVER
S)) { | |
| 2708 const char *const nameserver = NEXT_TOKEN; | |
| 2709 struct in_addr ina; | |
| 2710 | |
| 2711 if (nameserver && inet_aton(nameserver, &ina)) { | |
| 2712 /* address is valid */ | |
| 2713 evdns_nameserver_add(ina.s_addr); | |
| 2714 } | |
| 2715 } else if (!strcmp(first_token, "domain") && (flags & DNS_OPTION_SEARCH)
) { | |
| 2716 const char *const domain = NEXT_TOKEN; | |
| 2717 if (domain) { | |
| 2718 search_postfix_clear(); | |
| 2719 search_postfix_add(domain); | |
| 2720 } | |
| 2721 } else if (!strcmp(first_token, "search") && (flags & DNS_OPTION_SEARCH)
) { | |
| 2722 const char *domain; | |
| 2723 search_postfix_clear(); | |
| 2724 | |
| 2725 while ((domain = NEXT_TOKEN)) { | |
| 2726 search_postfix_add(domain); | |
| 2727 } | |
| 2728 search_reverse(); | |
| 2729 } else if (!strcmp(first_token, "options")) { | |
| 2730 const char *option; | |
| 2731 while ((option = NEXT_TOKEN)) { | |
| 2732 const char *val = strchr(option, ':'); | |
| 2733 evdns_set_option(option, val ? val+1 : "", flags); | |
| 2734 } | |
| 2735 } | |
| 2736 #undef NEXT_TOKEN | |
| 2737 } | |
| 2738 | |
| 2739 /* exported function */ | |
| 2740 /* returns: */ | |
| 2741 /* 0 no errors */ | |
| 2742 /* 1 failed to open file */ | |
| 2743 /* 2 failed to stat file */ | |
| 2744 /* 3 file too large */ | |
| 2745 /* 4 out of memory */ | |
| 2746 /* 5 short read from file */ | |
| 2747 int | |
| 2748 evdns_resolv_conf_parse(int flags, const char *const filename) { | |
| 2749 struct stat st; | |
| 2750 int fd, n, r; | |
| 2751 u8 *resolv; | |
| 2752 char *start; | |
| 2753 int err = 0; | |
| 2754 | |
| 2755 log(EVDNS_LOG_DEBUG, "Parsing resolv.conf file %s", filename); | |
| 2756 | |
| 2757 fd = open(filename, O_RDONLY); | |
| 2758 if (fd < 0) { | |
| 2759 evdns_resolv_set_defaults(flags); | |
| 2760 return 1; | |
| 2761 } | |
| 2762 | |
| 2763 if (fstat(fd, &st)) { err = 2; goto out1; } | |
| 2764 if (!st.st_size) { | |
| 2765 evdns_resolv_set_defaults(flags); | |
| 2766 err = (flags & DNS_OPTION_NAMESERVERS) ? 6 : 0; | |
| 2767 goto out1; | |
| 2768 } | |
| 2769 if (st.st_size > 65535) { err = 3; goto out1; } /* no resolv.conf shoul
d be any bigger */ | |
| 2770 | |
| 2771 resolv = (u8 *) malloc((size_t)st.st_size + 1); | |
| 2772 if (!resolv) { err = 4; goto out1; } | |
| 2773 | |
| 2774 n = 0; | |
| 2775 while ((r = read(fd, resolv+n, (size_t)st.st_size-n)) > 0) { | |
| 2776 n += r; | |
| 2777 if (n == st.st_size) | |
| 2778 break; | |
| 2779 assert(n < st.st_size); | |
| 2780 } | |
| 2781 if (r < 0) { err = 5; goto out2; } | |
| 2782 resolv[n] = 0; /* we malloced an extra byte; this should be fine. */ | |
| 2783 | |
| 2784 start = (char *) resolv; | |
| 2785 for (;;) { | |
| 2786 char *const newline = strchr(start, '\n'); | |
| 2787 if (!newline) { | |
| 2788 resolv_conf_parse_line(start, flags); | |
| 2789 break; | |
| 2790 } else { | |
| 2791 *newline = 0; | |
| 2792 resolv_conf_parse_line(start, flags); | |
| 2793 start = newline + 1; | |
| 2794 } | |
| 2795 } | |
| 2796 | |
| 2797 if (!server_head && (flags & DNS_OPTION_NAMESERVERS)) { | |
| 2798 /* no nameservers were configured. */ | |
| 2799 evdns_nameserver_ip_add("127.0.0.1"); | |
| 2800 err = 6; | |
| 2801 } | |
| 2802 if (flags & DNS_OPTION_SEARCH && (!global_search_state || global_search_
state->num_domains == 0)) { | |
| 2803 search_set_from_hostname(); | |
| 2804 } | |
| 2805 | |
| 2806 out2: | |
| 2807 free(resolv); | |
| 2808 out1: | |
| 2809 close(fd); | |
| 2810 return err; | |
| 2811 } | |
| 2812 | |
| 2813 #ifdef WIN32 | |
| 2814 /* Add multiple nameservers from a space-or-comma-separated list. */ | |
| 2815 static int | |
| 2816 evdns_nameserver_ip_add_line(const char *ips) { | |
| 2817 const char *addr; | |
| 2818 char *buf; | |
| 2819 int r; | |
| 2820 while (*ips) { | |
| 2821 while (ISSPACE(*ips) || *ips == ',' || *ips == '\t') | |
| 2822 ++ips; | |
| 2823 addr = ips; | |
| 2824 while (ISDIGIT(*ips) || *ips == '.' || *ips == ':') | |
| 2825 ++ips; | |
| 2826 buf = malloc(ips-addr+1); | |
| 2827 if (!buf) return 4; | |
| 2828 memcpy(buf, addr, ips-addr); | |
| 2829 buf[ips-addr] = '\0'; | |
| 2830 r = evdns_nameserver_ip_add(buf); | |
| 2831 free(buf); | |
| 2832 if (r) return r; | |
| 2833 } | |
| 2834 return 0; | |
| 2835 } | |
| 2836 | |
| 2837 typedef DWORD(WINAPI *GetNetworkParams_fn_t)(FIXED_INFO *, DWORD*); | |
| 2838 | |
| 2839 /* Use the windows GetNetworkParams interface in iphlpapi.dll to */ | |
| 2840 /* figure out what our nameservers are. */ | |
| 2841 static int | |
| 2842 load_nameservers_with_getnetworkparams(void) | |
| 2843 { | |
| 2844 /* Based on MSDN examples and inspection of c-ares code. */ | |
| 2845 FIXED_INFO *fixed; | |
| 2846 HMODULE handle = 0; | |
| 2847 ULONG size = sizeof(FIXED_INFO); | |
| 2848 void *buf = NULL; | |
| 2849 int status = 0, r, added_any; | |
| 2850 IP_ADDR_STRING *ns; | |
| 2851 GetNetworkParams_fn_t fn; | |
| 2852 | |
| 2853 if (!(handle = LoadLibraryA("iphlpapi.dll"))) { | |
| 2854 log(EVDNS_LOG_WARN, "Could not open iphlpapi.dll"); | |
| 2855 status = -1; | |
| 2856 goto done; | |
| 2857 } | |
| 2858 if (!(fn = (GetNetworkParams_fn_t) GetProcAddress(handle, "GetNetworkPar
ams"))) { | |
| 2859 log(EVDNS_LOG_WARN, "Could not get address of function."); | |
| 2860 status = -1; | |
| 2861 goto done; | |
| 2862 } | |
| 2863 | |
| 2864 buf = malloc(size); | |
| 2865 if (!buf) { status = 4; goto done; } | |
| 2866 fixed = buf; | |
| 2867 r = fn(fixed, &size); | |
| 2868 if (r != ERROR_SUCCESS && r != ERROR_BUFFER_OVERFLOW) { | |
| 2869 status = -1; | |
| 2870 goto done; | |
| 2871 } | |
| 2872 if (r != ERROR_SUCCESS) { | |
| 2873 free(buf); | |
| 2874 buf = malloc(size); | |
| 2875 if (!buf) { status = 4; goto done; } | |
| 2876 fixed = buf; | |
| 2877 r = fn(fixed, &size); | |
| 2878 if (r != ERROR_SUCCESS) { | |
| 2879 log(EVDNS_LOG_DEBUG, "fn() failed."); | |
| 2880 status = -1; | |
| 2881 goto done; | |
| 2882 } | |
| 2883 } | |
| 2884 | |
| 2885 assert(fixed); | |
| 2886 added_any = 0; | |
| 2887 ns = &(fixed->DnsServerList); | |
| 2888 while (ns) { | |
| 2889 r = evdns_nameserver_ip_add_line(ns->IpAddress.String); | |
| 2890 if (r) { | |
| 2891 log(EVDNS_LOG_DEBUG,"Could not add nameserver %s to list
,error: %d", | |
| 2892 (ns->IpAddress.String),(int)GetLastError()); | |
| 2893 status = r; | |
| 2894 goto done; | |
| 2895 } else { | |
| 2896 log(EVDNS_LOG_DEBUG,"Succesfully added %s as nameserver"
,ns->IpAddress.String); | |
| 2897 } | |
| 2898 | |
| 2899 added_any++; | |
| 2900 ns = ns->Next; | |
| 2901 } | |
| 2902 | |
| 2903 if (!added_any) { | |
| 2904 log(EVDNS_LOG_DEBUG, "No nameservers added."); | |
| 2905 status = -1; | |
| 2906 } | |
| 2907 | |
| 2908 done: | |
| 2909 if (buf) | |
| 2910 free(buf); | |
| 2911 if (handle) | |
| 2912 FreeLibrary(handle); | |
| 2913 return status; | |
| 2914 } | |
| 2915 | |
| 2916 static int | |
| 2917 config_nameserver_from_reg_key(HKEY key, const char *subkey) | |
| 2918 { | |
| 2919 char *buf; | |
| 2920 DWORD bufsz = 0, type = 0; | |
| 2921 int status = 0; | |
| 2922 | |
| 2923 if (RegQueryValueExA(key, subkey, 0, &type, NULL, &bufsz) | |
| 2924 != ERROR_MORE_DATA) | |
| 2925 return -1; | |
| 2926 if (!(buf = malloc(bufsz))) | |
| 2927 return -1; | |
| 2928 | |
| 2929 if (RegQueryValueExA(key, subkey, 0, &type, (LPBYTE)buf, &bufsz) | |
| 2930 == ERROR_SUCCESS && bufsz > 1) { | |
| 2931 status = evdns_nameserver_ip_add_line(buf); | |
| 2932 } | |
| 2933 | |
| 2934 free(buf); | |
| 2935 return status; | |
| 2936 } | |
| 2937 | |
| 2938 #define SERVICES_KEY "System\\CurrentControlSet\\Services\\" | |
| 2939 #define WIN_NS_9X_KEY SERVICES_KEY "VxD\\MSTCP" | |
| 2940 #define WIN_NS_NT_KEY SERVICES_KEY "Tcpip\\Parameters" | |
| 2941 | |
| 2942 static int | |
| 2943 load_nameservers_from_registry(void) | |
| 2944 { | |
| 2945 int found = 0; | |
| 2946 int r; | |
| 2947 #define TRY(k, name) \ | |
| 2948 if (!found && config_nameserver_from_reg_key(k,name) == 0) { \ | |
| 2949 log(EVDNS_LOG_DEBUG,"Found nameservers in %s/%s",#k,name); \ | |
| 2950 found = 1; \ | |
| 2951 } else if (!found) { \ | |
| 2952 log(EVDNS_LOG_DEBUG,"Didn't find nameservers in %s/%s", \ | |
| 2953 #k,#name); \ | |
| 2954 } | |
| 2955 | |
| 2956 if (((int)GetVersion()) > 0) { /* NT */ | |
| 2957 HKEY nt_key = 0, interfaces_key = 0; | |
| 2958 | |
| 2959 if (RegOpenKeyExA(HKEY_LOCAL_MACHINE, WIN_NS_NT_KEY, 0, | |
| 2960 KEY_READ, &nt_key) != ERROR_SUCCESS) { | |
| 2961 log(EVDNS_LOG_DEBUG,"Couldn't open nt key, %d",(int)GetL
astError()); | |
| 2962 return -1; | |
| 2963 } | |
| 2964 r = RegOpenKeyExA(nt_key, "Interfaces", 0, | |
| 2965 KEY_QUERY_VALUE|KEY_ENUMERATE_SUB_KEYS, | |
| 2966 &interfaces_key); | |
| 2967 if (r != ERROR_SUCCESS) { | |
| 2968 log(EVDNS_LOG_DEBUG,"Couldn't open interfaces key, %d",(
int)GetLastError()); | |
| 2969 return -1; | |
| 2970 } | |
| 2971 TRY(nt_key, "NameServer"); | |
| 2972 TRY(nt_key, "DhcpNameServer"); | |
| 2973 TRY(interfaces_key, "NameServer"); | |
| 2974 TRY(interfaces_key, "DhcpNameServer"); | |
| 2975 RegCloseKey(interfaces_key); | |
| 2976 RegCloseKey(nt_key); | |
| 2977 } else { | |
| 2978 HKEY win_key = 0; | |
| 2979 if (RegOpenKeyExA(HKEY_LOCAL_MACHINE, WIN_NS_9X_KEY, 0, | |
| 2980 KEY_READ, &win_key) != ERROR_SUCCESS) { | |
| 2981 log(EVDNS_LOG_DEBUG, "Couldn't open registry key, %d", (
int)GetLastError()); | |
| 2982 return -1; | |
| 2983 } | |
| 2984 TRY(win_key, "NameServer"); | |
| 2985 RegCloseKey(win_key); | |
| 2986 } | |
| 2987 | |
| 2988 if (found == 0) { | |
| 2989 log(EVDNS_LOG_WARN,"Didn't find any nameservers."); | |
| 2990 } | |
| 2991 | |
| 2992 return found ? 0 : -1; | |
| 2993 #undef TRY | |
| 2994 } | |
| 2995 | |
| 2996 int | |
| 2997 evdns_config_windows_nameservers(void) | |
| 2998 { | |
| 2999 if (load_nameservers_with_getnetworkparams() == 0) | |
| 3000 return 0; | |
| 3001 return load_nameservers_from_registry(); | |
| 3002 } | |
| 3003 #endif | |
| 3004 | |
| 3005 int | |
| 3006 evdns_init(void) | |
| 3007 { | |
| 3008 int res = 0; | |
| 3009 #ifdef WIN32 | |
| 3010 res = evdns_config_windows_nameservers(); | |
| 3011 #else | |
| 3012 res = evdns_resolv_conf_parse(DNS_OPTIONS_ALL, "/etc/resolv.conf"); | |
| 3013 #endif | |
| 3014 | |
| 3015 return (res); | |
| 3016 } | |
| 3017 | |
| 3018 const char * | |
| 3019 evdns_err_to_string(int err) | |
| 3020 { | |
| 3021 switch (err) { | |
| 3022 case DNS_ERR_NONE: return "no error"; | |
| 3023 case DNS_ERR_FORMAT: return "misformatted query"; | |
| 3024 case DNS_ERR_SERVERFAILED: return "server failed"; | |
| 3025 case DNS_ERR_NOTEXIST: return "name does not exist"; | |
| 3026 case DNS_ERR_NOTIMPL: return "query not implemented"; | |
| 3027 case DNS_ERR_REFUSED: return "refused"; | |
| 3028 | |
| 3029 case DNS_ERR_TRUNCATED: return "reply truncated or ill-formed"; | |
| 3030 case DNS_ERR_UNKNOWN: return "unknown"; | |
| 3031 case DNS_ERR_TIMEOUT: return "request timed out"; | |
| 3032 case DNS_ERR_SHUTDOWN: return "dns subsystem shut down"; | |
| 3033 default: return "[Unknown error code]"; | |
| 3034 } | |
| 3035 } | |
| 3036 | |
| 3037 void | |
| 3038 evdns_shutdown(int fail_requests) | |
| 3039 { | |
| 3040 struct nameserver *server, *server_next; | |
| 3041 struct search_domain *dom, *dom_next; | |
| 3042 | |
| 3043 while (req_head) { | |
| 3044 if (fail_requests) | |
| 3045 reply_callback(req_head, 0, DNS_ERR_SHUTDOWN, NULL); | |
| 3046 request_finished(req_head, &req_head); | |
| 3047 } | |
| 3048 while (req_waiting_head) { | |
| 3049 if (fail_requests) | |
| 3050 reply_callback(req_waiting_head, 0, DNS_ERR_SHUTDOWN, NU
LL); | |
| 3051 request_finished(req_waiting_head, &req_waiting_head); | |
| 3052 } | |
| 3053 global_requests_inflight = global_requests_waiting = 0; | |
| 3054 | |
| 3055 for (server = server_head; server; server = server_next) { | |
| 3056 server_next = server->next; | |
| 3057 if (server->socket >= 0) | |
| 3058 CLOSE_SOCKET(server->socket); | |
| 3059 (void) event_del(&server->event); | |
| 3060 if (server->state == 0) | |
| 3061 (void) event_del(&server->timeout_event); | |
| 3062 free(server); | |
| 3063 if (server_next == server_head) | |
| 3064 break; | |
| 3065 } | |
| 3066 server_head = NULL; | |
| 3067 global_good_nameservers = 0; | |
| 3068 | |
| 3069 if (global_search_state) { | |
| 3070 for (dom = global_search_state->head; dom; dom = dom_next) { | |
| 3071 dom_next = dom->next; | |
| 3072 free(dom); | |
| 3073 } | |
| 3074 free(global_search_state); | |
| 3075 global_search_state = NULL; | |
| 3076 } | |
| 3077 evdns_log_fn = NULL; | |
| 3078 } | |
| 3079 | |
| 3080 #ifdef EVDNS_MAIN | |
| 3081 void | |
| 3082 main_callback(int result, char type, int count, int ttl, | |
| 3083 void *addrs, void *orig) { | |
| 3084 char *n = (char*)orig; | |
| 3085 int i; | |
| 3086 for (i = 0; i < count; ++i) { | |
| 3087 if (type == DNS_IPv4_A) { | |
| 3088 printf("%s: %s\n", n, debug_ntoa(((u32*)addrs)[i])); | |
| 3089 } else if (type == DNS_PTR) { | |
| 3090 printf("%s: %s\n", n, ((char**)addrs)[i]); | |
| 3091 } | |
| 3092 } | |
| 3093 if (!count) { | |
| 3094 printf("%s: No answer (%d)\n", n, result); | |
| 3095 } | |
| 3096 fflush(stdout); | |
| 3097 } | |
| 3098 void | |
| 3099 evdns_server_callback(struct evdns_server_request *req, void *data) | |
| 3100 { | |
| 3101 int i, r; | |
| 3102 (void)data; | |
| 3103 /* dummy; give 192.168.11.11 as an answer for all A questions, | |
| 3104 * give foo.bar.example.com as an answer for all PTR questions. */ | |
| 3105 for (i = 0; i < req->nquestions; ++i) { | |
| 3106 u32 ans = htonl(0xc0a80b0bUL); | |
| 3107 if (req->questions[i]->type == EVDNS_TYPE_A && | |
| 3108 req->questions[i]->dns_question_class == EVDNS_CLASS_INE
T) { | |
| 3109 printf(" -- replying for %s (A)\n", req->questions[i]->n
ame); | |
| 3110 r = evdns_server_request_add_a_reply(req, req->questions
[i]->name, | |
| 3111
1, &ans, 10); | |
| 3112 if (r<0) | |
| 3113 printf("eeep, didn't work.\n"); | |
| 3114 } else if (req->questions[i]->type == EVDNS_TYPE_PTR && | |
| 3115 req->questions[i]->dns_question_class == EVDN
S_CLASS_INET) { | |
| 3116 printf(" -- replying for %s (PTR)\n", req->questions[i]-
>name); | |
| 3117 r = evdns_server_request_add_ptr_reply(req, NULL, req->q
uestions[i]->name, | |
| 3118
"foo.bar.example.com", 10); | |
| 3119 } else { | |
| 3120 printf(" -- skipping %s [%d %d]\n", req->questions[i]->n
ame, | |
| 3121 req->questions[i]->type, req->questions[i]->d
ns_question_class); | |
| 3122 } | |
| 3123 } | |
| 3124 | |
| 3125 r = evdns_request_respond(req, 0); | |
| 3126 if (r<0) | |
| 3127 printf("eeek, couldn't send reply.\n"); | |
| 3128 } | |
| 3129 | |
| 3130 void | |
| 3131 logfn(int is_warn, const char *msg) { | |
| 3132 (void) is_warn; | |
| 3133 fprintf(stderr, "%s\n", msg); | |
| 3134 } | |
| 3135 int | |
| 3136 main(int c, char **v) { | |
| 3137 int idx; | |
| 3138 int reverse = 0, verbose = 1, servertest = 0; | |
| 3139 if (c<2) { | |
| 3140 fprintf(stderr, "syntax: %s [-x] [-v] hostname\n", v[0]); | |
| 3141 fprintf(stderr, "syntax: %s [-servertest]\n", v[0]); | |
| 3142 return 1; | |
| 3143 } | |
| 3144 idx = 1; | |
| 3145 while (idx < c && v[idx][0] == '-') { | |
| 3146 if (!strcmp(v[idx], "-x")) | |
| 3147 reverse = 1; | |
| 3148 else if (!strcmp(v[idx], "-v")) | |
| 3149 verbose = 1; | |
| 3150 else if (!strcmp(v[idx], "-servertest")) | |
| 3151 servertest = 1; | |
| 3152 else | |
| 3153 fprintf(stderr, "Unknown option %s\n", v[idx]); | |
| 3154 ++idx; | |
| 3155 } | |
| 3156 event_init(); | |
| 3157 if (verbose) | |
| 3158 evdns_set_log_fn(logfn); | |
| 3159 evdns_resolv_conf_parse(DNS_OPTION_NAMESERVERS, "/etc/resolv.conf"); | |
| 3160 if (servertest) { | |
| 3161 int sock; | |
| 3162 struct sockaddr_in my_addr; | |
| 3163 sock = socket(PF_INET, SOCK_DGRAM, 0); | |
| 3164 evutil_make_socket_nonblocking(sock); | |
| 3165 my_addr.sin_family = AF_INET; | |
| 3166 my_addr.sin_port = htons(10053); | |
| 3167 my_addr.sin_addr.s_addr = INADDR_ANY; | |
| 3168 if (bind(sock, (struct sockaddr*)&my_addr, sizeof(my_addr))<0) { | |
| 3169 perror("bind"); | |
| 3170 exit(1); | |
| 3171 } | |
| 3172 evdns_add_server_port(sock, 0, evdns_server_callback, NULL); | |
| 3173 } | |
| 3174 for (; idx < c; ++idx) { | |
| 3175 if (reverse) { | |
| 3176 struct in_addr addr; | |
| 3177 if (!inet_aton(v[idx], &addr)) { | |
| 3178 fprintf(stderr, "Skipping non-IP %s\n", v[idx]); | |
| 3179 continue; | |
| 3180 } | |
| 3181 fprintf(stderr, "resolving %s...\n",v[idx]); | |
| 3182 evdns_resolve_reverse(&addr, 0, main_callback, v[idx]); | |
| 3183 } else { | |
| 3184 fprintf(stderr, "resolving (fwd) %s...\n",v[idx]); | |
| 3185 evdns_resolve_ipv4(v[idx], 0, main_callback, v[idx]); | |
| 3186 } | |
| 3187 } | |
| 3188 fflush(stdout); | |
| 3189 event_dispatch(); | |
| 3190 return 0; | |
| 3191 } | |
| 3192 #endif | |
| OLD | NEW |
|---|
Chromium Code Reviews
Issue 1531573008:
move libevent into base (Closed)
Base URL: https://chromium.googlesource.com/chromium/src.git@master