From: Niels Provos Date: Thu, 5 Oct 2006 22:59:44 +0000 (+0000) Subject: sync evdns changes with tor - from Nick Mathewson X-Git-Tag: release-2.0.1-alpha~714 X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=fe1dfe0f40776ef18f5318149f981387d386b962;p=libevent sync evdns changes with tor - from Nick Mathewson svn:r238 --- diff --git a/evdns.c b/evdns.c index 7866e2ed..60f0bcf6 100644 --- a/evdns.c +++ b/evdns.c @@ -3,7 +3,7 @@ /* The original version of this module was written by Adam Langley; for * a history of modifications, check out the subversion logs. * - * When editiing this module, try to keep it re-mergeable by Adam. Don't + * When editing this module, try to keep it re-mergeable by Adam. Don't * reformat the whitespace, add Tor dependencies, or so on. * * TODO: @@ -15,7 +15,7 @@ /* Async DNS Library * Adam Langley * http://www.imperialviolet.org/eventdns.html - * Public Domain codenext + * Public Domain code * * This software is Public Domain. To view a copy of the public domain dedication, * visit http://creativecommons.org/licenses/publicdomain/ or send a letter to @@ -39,11 +39,9 @@ * Async DNS lookups are really a whole lot harder than they should be, * mostly stemming from the fact that the libc resolver has never been * very good at them. Before you use this library you should see if libc - * can do the job for you with the modern async call getaddrinfo_r - * (Google for it). Otherwise, please continue. - * - * [I googled for getaddrinfo_r and got only two hits, one of which was this - * code. Did you mean something different? -NM] + * can do the job for you with the modern async call getaddrinfo_a + * (see http://www.imperialviolet.org/page25.html#e498). Otherwise, + * please continue. * * This code is based on libevent and you must call event_init before * any of the APIs in this file. You must also seed the OpenSSL random @@ -105,9 +103,9 @@ * evdns_search_add then no searching will occur. * * 2. If you do call evdns_resolv_conf_parse then don't pass - * DNS_OPTION_SEARCH (or DNS_OPTIONS_ALL, which implies it) + * DNS_OPTION_SEARCH (or DNS_OPTIONS_ALL, which implies it). * - * 3. When calling evdns_resolve, pass the DNS_QUERY_NO_SEARCH flag + * 3. When calling evdns_resolve, pass the DNS_QUERY_NO_SEARCH flag. * * The order of searches depends on the number of dots in the name. If the * number is greater than the ndots setting then the names is first tried @@ -215,7 +213,7 @@ * queue and so bounding its size keeps thing going nicely under huge * (many thousands of requests) loads. * - * If a nameserver looses too many requests it is considered down and we + * If a nameserver loses too many requests it is considered down and we * try not to use it. After a while we send a probe to that nameserver * (a lookup for google.com) and, if it replies, we consider it working * again. If the nameserver fails a probe we wait longer to try again @@ -233,7 +231,7 @@ #ifndef DNS_USE_GETTIMEOFDAY_FOR_ID #ifndef DNS_USE_OPENSSL_FOR_ID #error Must configure at least one id generation method. -#error Please see the documentation +#error Please see the documentation. #endif #endif #endif @@ -262,15 +260,12 @@ #include #include -#include #include #include #include #include #include #include -#include -#include #include #include #include @@ -280,6 +275,18 @@ #include "evdns.h" #include "log.h" +#ifdef WIN32 +#include +#include +#include +#else +#include +#include +#include +#endif + +#define EVDNS_LOG_DEBUG 0 +#define EVDNS_LOG_WARN 1 #ifndef HOST_NAME_MAX #define HOST_NAME_MAX 255 @@ -316,9 +323,10 @@ typedef unsigned int uint; struct request { u8 *request; // the dns packet data - uint request_len; + unsigned int request_len; int reissue_count; int tx_count; // the number of times that this packet has been sent + unsigned int request_type; // TYPE_PTR or TYPE_A void *user_pointer; // the pointer given to us for this request evdns_callback_type user_callback; struct nameserver *ns; // the server which we last sent it @@ -339,6 +347,20 @@ struct request { char transmit_me; // needs to be transmitted }; +struct reply { + unsigned int type; + unsigned int have_answer; + union { + struct { + u32 addrcount; + u32 addresses[MAX_ADDRS]; + } a; + struct { + char name[HOST_NAME_MAX]; + } ptr; + } data; +}; + struct nameserver { int socket; // a connected UDP socket u32 address; @@ -391,10 +413,10 @@ static int evdns_request_transmit(struct request *req); static void nameserver_send_probe(struct nameserver *const ns); static void search_request_finished(struct request *const); static int search_try_next(struct request *const req); -static int search_request_new(const char *const name, int flags, evdns_callback_type user_callback, void *user_arg); +static int search_request_new(int type, const char *const name, int flags, evdns_callback_type user_callback, void *user_arg); static void evdns_requests_pump_waiting_queue(void); static u16 transaction_id_pick(void); -static struct request *request_new(const char *name, int flags, evdns_callback_type callback, void *ptr); +static struct request *request_new(int type, const char *name, int flags, evdns_callback_type callback, void *ptr); static void request_submit(struct request *req); #ifdef MS_WINDOWS @@ -418,6 +440,20 @@ error_is_eagain(int err) { return err == EAGAIN || err == WSAEWOULDBLOCK; } +static int +inet_aton(const char *c, struct in_addr *addr) +{ + uint32_t r; + if (strcmp(c, "255.255.255.255") == 0) { + addr->s_addr = 0xffffffffu; + } else { + r = inet_addr(c); + if (r == INADDR_NONE) + return 0; + addr->s_addr = r; + } + return 1; +} #define CLOSE_SOCKET(x) closesocket(x) #else #define last_error(sock) (errno) @@ -452,14 +488,14 @@ evdns_set_log_fn(evdns_debug_log_fn_type fn) } #ifdef __GNUC__ -#define EVENTDNS_LOG_CHECK __attribute__ ((format(printf, 1, 2))) +#define EVDNS_LOG_CHECK __attribute__ ((format(printf, 2, 3))) #else -#define EVENTDNS_LOG_CHECK +#define EVDNS_LOG_CHECK #endif -static void _evdns_log(const char *fmt, ...) EVENTDNS_LOG_CHECK; +static void _evdns_log(int warn, const char *fmt, ...) EVDNS_LOG_CHECK; static void -_evdns_log(const char *fmt, ...) +_evdns_log(int warn, const char *fmt, ...) { va_list args; static char buf[512]; @@ -472,7 +508,7 @@ _evdns_log(const char *fmt, ...) vsnprintf(buf, sizeof(buf), fmt, args); #endif buf[sizeof(buf)-1] = '\0'; - evdns_log_fn(buf); + evdns_log_fn(warn, buf); va_end(args); } @@ -512,8 +548,13 @@ nameserver_prod_callback(int fd, short events, void *arg) { static void nameserver_probe_failed(struct nameserver *const ns) { const struct timeval * timeout; - assert(ns->state == 0); (void) evtimer_del(&ns->timeout_event); + if (ns->state == 1) { + // This can happen if the nameserver acts in a way which makes us mark + // it as bad and then starts sending good replies. + return; + } + timeout = &global_nameserver_timeouts[MIN(ns->failed_times, global_nameserver_timeouts_length - 1)]; @@ -521,7 +562,8 @@ nameserver_probe_failed(struct nameserver *const ns) { evtimer_set(&ns->timeout_event, nameserver_prod_callback, ns); if (evtimer_add(&ns->timeout_event, (struct timeval *) timeout) < 0) { - log("Error from libevent when adding timer event for %s", + log(EVDNS_LOG_WARN, + "Error from libevent when adding timer event for %s", debug_ntoa(ns->address)); // ???? Do more? } @@ -536,11 +578,12 @@ nameserver_failed(struct nameserver *const ns, const char *msg) { // then don't do anything if (!ns->state) return; - log("Nameserver %s has failed: %s", debug_ntoa(ns->address), msg); + log(EVDNS_LOG_WARN, "Nameserver %s has failed: %s", + debug_ntoa(ns->address), msg); global_good_nameservers--; assert(global_good_nameservers >= 0); if (global_good_nameservers == 0) { - log("All nameservers have failed"); + log(EVDNS_LOG_WARN, "All nameservers have failed"); } ns->state = 0; @@ -548,9 +591,10 @@ nameserver_failed(struct nameserver *const ns, const char *msg) { evtimer_set(&ns->timeout_event, nameserver_prod_callback, ns); if (evtimer_add(&ns->timeout_event, (struct timeval *) &global_nameserver_timeouts[0]) < 0) { - log("Error from libevent when adding timer event for %s", - debug_ntoa(ns->address)); - // ???? Do more? + log(EVDNS_LOG_WARN, + "Error from libevent when adding timer event for %s", + debug_ntoa(ns->address)); + // ???? Do more? } // walk the list of inflight requests to see if any can be reassigned to @@ -578,7 +622,8 @@ nameserver_failed(struct nameserver *const ns, const char *msg) { static void nameserver_up(struct nameserver *const ns) { if (ns->state) return; - log("Nameserver %s is back up", debug_ntoa(ns->address)); + log(EVDNS_LOG_WARN, "Nameserver %s is back up", + debug_ntoa(ns->address)); evtimer_del(&ns->timeout_event); ns->state = 1; ns->failed_times = 0; @@ -607,7 +652,8 @@ request_finished(struct request *const req, struct request **head) { } } - log("Removing timeout for request %lx", (unsigned long) req); + log(EVDNS_LOG_DEBUG, "Removing timeout for request %lx", + (unsigned long) req); evtimer_del(&req->timeout_event); search_request_finished(req); @@ -685,16 +731,39 @@ evdns_requests_pump_waiting_queue(void) { } } +static void +reply_callback(struct request *const req, u32 ttl, u32 err, struct reply *reply) { + switch (req->request_type) { + case TYPE_A: + if (reply) + req->user_callback(DNS_ERR_NONE, DNS_IPv4_A, + reply->data.a.addrcount, ttl, + reply->data.a.addresses, + req->user_pointer); + else + req->user_callback(err, 0, 0, 0, NULL, req->user_pointer); + return; + case TYPE_PTR: + if (reply) { + char *name = reply->data.ptr.name; + req->user_callback(DNS_ERR_NONE, DNS_PTR, 1, ttl, + &name, req->user_pointer); + } else { + req->user_callback(err, 0, 0, 0, NULL, + req->user_pointer); + } + return; + } + assert(0); +} + // this processes a parsed reply packet static void -reply_handle(u16 trans_id, u16 flags, u32 ttl, u32 addrcount, u32 *addresses) { +reply_handle(struct request *const req, u16 flags, u32 ttl, struct reply *reply) { int error; static const int error_codes[] = {DNS_ERR_FORMAT, DNS_ERR_SERVERFAILED, DNS_ERR_NOTEXIST, DNS_ERR_NOTIMPL, DNS_ERR_REFUSED}; - struct request *const req = request_find_from_trans_id(trans_id); - if (!req) return; - - if (flags & 0x020f || !addrcount) { + if (flags & 0x020f || !reply || !reply->have_answer) { // there was an error if (flags & 0x0200) { error = DNS_ERR_TRUNCATED; @@ -714,8 +783,8 @@ reply_handle(u16 trans_id, u16 flags, u32 ttl, u32 addrcount, u32 *addresses) { // we regard these errors as marking a bad nameserver if (req->reissue_count < global_max_reissues) { char msg[64]; - snprintf(msg, sizeof(msg), "Bad response %d", - error); + snprintf(msg, sizeof(msg), "Bad response %d (%s)", + error, evdns_err_to_string(error)); nameserver_failed(req->ns, msg); if (!request_reissue(req)) return; } @@ -725,7 +794,7 @@ reply_handle(u16 trans_id, u16 flags, u32 ttl, u32 addrcount, u32 *addresses) { nameserver_up(req->ns); } - if (req->search_state) { + if (req->search_state && req->request_type != TYPE_PTR) { // if we have a list of domains to search in, try the next one if (!search_try_next(req)) { // a new request was issued so this request is finished and @@ -737,31 +806,78 @@ reply_handle(u16 trans_id, u16 flags, u32 ttl, u32 addrcount, u32 *addresses) { } // all else failed. Pass the failure up - req->user_callback(error, 0, 0, 0, NULL, req->user_pointer); + reply_callback(req, 0, error, NULL); request_finished(req, &req_head); } else { // all ok, tell the user - req->user_callback(DNS_ERR_NONE, DNS_IPv4_A, addrcount, ttl, addresses, req->user_pointer); + reply_callback(req, ttl, 0, reply); nameserver_up(req->ns); request_finished(req, &req_head); } } +static inline int +name_parse(u8 *packet, int length, int *idx, char *name_out, int name_out_len) { + int name_end = -1; + int j = *idx; +#define GET32(x) do { if (j + 4 > length) return -1; memcpy(&_t32, packet + j, 4); j += 4; x = ntohl(_t32); } while(0); +#define GET16(x) do { if (j + 2 > length) return -1; memcpy(&_t, packet + j, 2); j += 2; x = ntohs(_t); } while(0); +#define GET8(x) do { if (j >= length) return -1; x = packet[j++]; } while(0); + + char *cp = name_out; + const char *const end = name_out + name_out_len; + + // Normally, names are a series of length prefixed strings terminated + // with a length of 0 (the lengths are u8's < 63). + // However, the length can start with a pair of 1 bits and that + // means that the next 14 bits are a pointer within the current + // packet. + + for(;;) { + u8 label_len; + if (j >= length) return -1; + GET8(label_len); + if (!label_len) break; + if (label_len & 0xc0) { + u8 ptr_low; + GET8(ptr_low); + if (name_end < 0) name_end = j; + j = (((int)label_len & 0x3f) << 8) + ptr_low; + if (j < 0 || j >= length) return -1; + continue; + } + if (label_len > 63) return -1; + if (cp != name_out) { + if (cp + 1 >= end) return -1; + *cp++ = '.'; + } + if (cp + label_len >= end) return -1; + memcpy(cp, packet + j, label_len); + cp += label_len; + j += label_len; + } + if (cp >= end) return -1; + *cp = '\0'; + if (name_end < 0) + *idx = j; + else + *idx = name_end; + return 0; +} + // parses a raw packet from the wire -static void +static int reply_parse(u8 *packet, int length) { int j = 0; // index into packet u16 _t; // used by the macros u32 _t32; // used by the macros + char tmp_name[256]; // used by the macros -#define GET32(x) do { if (j + 4 > length) return; memcpy(&_t32, packet + j, 4); j += 4; x = ntohl(_t32); } while(0); -#define GET16(x) do { if (j + 2 > length) return; memcpy(&_t, packet + j, 2); j += 2; x = ntohs(_t); } while(0); -#define GET8(x) do { if (j >= length) return; x = packet[j++]; } while(0); u16 trans_id, flags, questions, answers, authority, additional, datalength; u32 ttl, ttl_r = 0xffffffff; - u32 addresses[MAX_ADDRS]; - int addresses_done = 0; - uint i; + struct reply reply; + struct request *req; + unsigned int i; GET16(trans_id); GET16(flags); @@ -770,32 +886,28 @@ reply_parse(u8 *packet, int length) { GET16(authority); GET16(additional); - if (!(flags & 0x8000)) return; // must be an answer + req = request_find_from_trans_id(trans_id); + if (!req) return -1; + // XXXX should the other return points also call reply_handle? -NM + + memset(&reply, 0, sizeof(reply)); + + if (!(flags & 0x8000)) return -1; // must be an answer if (flags & 0x020f) { // there was an error - reply_handle(trans_id, flags, 0, 0, NULL); - return; + reply_handle(req, flags, 0, NULL); + return -1; } // if (!answers) return; // must have an answer of some form - // This macro skips a name in the DNS reply. Normally the - // names are a series of length prefixed strings terminated with - // a length of 0 (the lengths are u8's < 63). - // However, the length can start with a pair of 1 bits and that - // means that the next 14 bits are a pointer within the current - // packet. The name stops after a pointer like that. + // This macro skips a name in the DNS reply. #define SKIP_NAME \ - for(;;) { \ - u8 label_len; \ - GET8(label_len); \ - if (!label_len) break; \ - if (label_len & 0xc0) { \ - GET8(label_len); \ - break; \ - } \ - if (label_len > 63) return; \ - j += label_len; \ - } + do { tmp_name[0] = '\0'; \ + if (name_parse(packet, length, &j, tmp_name, sizeof(tmp_name))<0) \ + return -1; \ + } while(0); + + reply.type = req->request_type; // skip over each question in the reply for (i = 0; i < questions; ++i) { @@ -803,6 +915,7 @@ reply_parse(u8 *packet, int length) { // SKIP_NAME; j += 4; + if (j >= length) return -1; } // now we have the answer section which looks like @@ -818,24 +931,40 @@ reply_parse(u8 *packet, int length) { GET16(datalength); if (type == TYPE_A && class == CLASS_INET) { - const int addrcount = datalength >> 2; // each IP address is 4 bytes + int addrcount, addrtocopy; + if (req->request_type != TYPE_A) { + j += datalength; continue; + } // XXXX do something sane with malformed A answers. - const int addrtocopy = MIN(MAX_ADDRS - addresses_done, addrcount); + addrcount = datalength >> 2; + addrtocopy = MIN(MAX_ADDRS - reply.data.a.addrcount, (unsigned)addrcount); ttl_r = MIN(ttl_r, ttl); // we only bother with the first four addresses. - if (j + 4*addrtocopy > length) return; - memcpy(&addresses[addresses_done], packet + j, 4*addrtocopy); + if (j + 4*addrtocopy > length) return -1; + memcpy(&reply.data.a.addresses[reply.data.a.addrcount], + packet + j, 4*addrtocopy); j += 4*addrtocopy; - addresses_done += addrtocopy; - if (addresses_done == MAX_ADDRS) break; + reply.data.a.addrcount += addrtocopy; + reply.have_answer = 1; + if (reply.data.a.addrcount == MAX_ADDRS) break; + } else if (type == TYPE_PTR && class == CLASS_INET) { + if (req->request_type != TYPE_PTR) { + j += datalength; continue; + } + if (name_parse(packet, length, &j, reply.data.ptr.name, + sizeof(reply.data.ptr.name))<0) + return -1; + reply.have_answer = 1; + break; } else { // skip over any other type of resource j += datalength; } } - reply_handle(trans_id, flags, ttl_r, addresses_done, addresses); + reply_handle(req, flags, ttl_r, &reply); + return 0; #undef SKIP_NAME #undef GET32 #undef GET16 @@ -931,7 +1060,7 @@ nameserver_read(struct nameserver *ns) { for (;;) { const int r = recv(ns->socket, packet, sizeof(packet), 0); if (r < 0) { - int err = last_error(ns_socket); + int err = last_error(ns->socket); if (error_is_eagain(err)) return; nameserver_failed(ns, strerror(err)); return; @@ -952,7 +1081,7 @@ nameserver_write_waiting(struct nameserver *ns, char waiting) { event_set(&ns->event, ns->socket, EV_READ | (waiting ? EV_WRITE : 0) | EV_PERSIST, nameserver_ready_callback, ns); if (event_add(&ns->event, NULL) < 0) { - log("Error from libevent when adding event for %s", + log(EVDNS_LOG_WARN, "Error from libevent when adding event for %s", debug_ntoa(ns->address)); // ???? Do more? } @@ -987,8 +1116,8 @@ nameserver_ready_callback(int fd, short events, void *arg) { // -1 label was > 63 bytes // -2 name was > 255 bytes static int -dnsname_to_labels(u8 *const buf, const char *name, const int name_len) { \ - const char *end = name + name_len; \ +dnsname_to_labels(u8 *const buf, const char *name, const int name_len) { + const char *end = name + name_len; int j = 0; // current offset into buf if (name_len > 255) return -2; @@ -997,7 +1126,7 @@ dnsname_to_labels(u8 *const buf, const char *name, const int name_len) { \ const char *const start = name; name = strchr(name, '.'); if (!name) { - const uint label_len = end - start; + const unsigned int label_len = end - start; if (label_len > 63) return -1; buf[j++] = label_len; @@ -1006,7 +1135,7 @@ dnsname_to_labels(u8 *const buf, const char *name, const int name_len) { \ break; } else { // append length of the label. - const uint label_len = name - start; + const unsigned int label_len = name - start; if (label_len > 63) return -1; buf[j++] = label_len; @@ -1040,7 +1169,7 @@ evdns_request_len(const int name_len) { // Returns the amount of space used. Negative on error. static int evdns_request_data_build(const char *const name, const int name_len, - const u16 trans_id, const u16 type, const u16 class, + const u16 trans_id, const u16 type, const u16 class, u8 *const buf, size_t buf_len) { int j = 0; // current offset into buf u16 _t; // used by the macros @@ -1069,7 +1198,7 @@ evdns_request_data_build(const char *const name, const int name_len, free(labels); return (labels_len); } - if (j + labels_len > buf_len) { + if ((size_t)(j + labels_len) > buf_len) { free(labels); return (-1); } @@ -1092,7 +1221,7 @@ evdns_request_timeout_callback(int fd, short events, void *arg) { (void) fd; (void) events; - log("Request %lx timed out", (unsigned long) arg); + log(EVDNS_LOG_DEBUG, "Request %lx timed out", (unsigned long) arg); req->ns->timedout++; if (req->ns->timedout > global_max_nameserver_timeout) { @@ -1102,7 +1231,7 @@ evdns_request_timeout_callback(int fd, short events, void *arg) { (void) evtimer_del(&req->timeout_event); if (req->tx_count >= global_max_retransmits) { // this request has failed - req->user_callback(DNS_ERR_TIMEOUT, 0, 0, 0, NULL, req->user_pointer); + reply_callback(req, 0, DNS_ERR_TIMEOUT, NULL); request_finished(req, &req_head); } else { // retransmit it @@ -1165,10 +1294,12 @@ evdns_request_transmit(struct request *req) { // fall through default: // all ok - log("Setting timeout for request %lx", (unsigned long) req); + log(EVDNS_LOG_DEBUG, + "Setting timeout for request %lx", (unsigned long) req); evtimer_set(&req->timeout_event, evdns_request_timeout_callback, req); if (evtimer_add(&req->timeout_event, &global_timeout) < 0) { - log("Error from libevent when adding timer for request %lx", + log(EVDNS_LOG_WARN, + "Error from libevent when adding timer for request %lx", (unsigned long) req); // ???? Do more? } @@ -1198,9 +1329,9 @@ nameserver_send_probe(struct nameserver *const ns) { // here we need to send a probe to a given nameserver // in the hope that it is up now. - log("Sending probe to %s", debug_ntoa(ns->address)); + log(EVDNS_LOG_DEBUG, "Sending probe to %s", debug_ntoa(ns->address)); - req = request_new("www.google.com", DNS_QUERY_NO_SEARCH, nameserver_probe_callback, ns); + req = request_new(TYPE_A, "www.google.com", DNS_QUERY_NO_SEARCH, nameserver_probe_callback, ns); if (!req) return; // we force this into the inflight queue no matter what request_trans_id_set(req, transaction_id_pick()); @@ -1352,7 +1483,7 @@ evdns_nameserver_add(unsigned long int address) { goto out2; } - log("Added nameserver %s", debug_ntoa(address)); + log(EVDNS_LOG_DEBUG, "Added nameserver %s", debug_ntoa(address)); // insert this nameserver into the list of them if (!server_head) { @@ -1375,7 +1506,7 @@ out2: CLOSE_SOCKET(ns->socket); out1: free(ns); - log("Unable to add nameserver %s: error %d", debug_ntoa(address), err); + log(EVDNS_LOG_WARN, "Unable to add nameserver %s: error %d", debug_ntoa(address), err); return err; } @@ -1413,8 +1544,8 @@ string_num_dots(const char *s) { } static struct request * -request_new(const char *name, int flags, - evdns_callback_type callback, void *ptr) { +request_new(int type, const char *name, int flags, + evdns_callback_type callback, void *user_ptr) { const char issuing_now = (global_requests_inflight < global_max_requests_inflight) ? 1 : 0; @@ -1435,20 +1566,21 @@ request_new(const char *name, int flags, // denotes that the request data shouldn't be free()ed req->request_appended = 1; rlen = evdns_request_data_build(name, name_len, trans_id, - TYPE_A, CLASS_INET, req->request, request_max_len); + type, CLASS_INET, req->request, request_max_len); if (rlen < 0) goto err1; req->request_len = rlen; req->trans_id = trans_id; req->tx_count = 0; - req->user_pointer = ptr; + req->request_type = type; + req->user_pointer = user_ptr; req->user_callback = callback; req->ns = issuing_now ? nameserver_pick() : NULL; req->next = req->prev = NULL; return req; err1: - free(req->request); + free(req); return NULL; } @@ -1467,21 +1599,39 @@ request_submit(struct request *const req) { } // exported function -int evdns_resolve(const char *name, int flags, +int evdns_resolve_ipv4(const char *name, int flags, evdns_callback_type callback, void *ptr) { - log("Resolve requested for %s", name); + log(EVDNS_LOG_DEBUG, "Resolve requested for %s", name); if (flags & DNS_QUERY_NO_SEARCH) { struct request *const req = - request_new(name, flags, callback, ptr); + request_new(TYPE_A, name, flags, callback, ptr); if (req == NULL) return (1); request_submit(req); return (0); } else { - return (search_request_new(name, flags, callback, ptr)); + return (search_request_new(TYPE_A, name, flags, callback, ptr)); } } +int evdns_resolve_reverse(struct in_addr *in, int flags, evdns_callback_type callback, void *ptr) { + char buf[32]; + struct request *req; + u32 a; + assert(in); + a = ntohl(in->s_addr); + sprintf(buf, "%d.%d.%d.%d.in-addr.arpa", + (int)(u8)((a )&0xff), + (int)(u8)((a>>8 )&0xff), + (int)(u8)((a>>16)&0xff), + (int)(u8)((a>>24)&0xff)); + log(EVDNS_LOG_DEBUG, "Resolve requested for %s (reverse)", buf); + req = request_new(TYPE_PTR, buf, flags, callback, ptr); + if (!req) return 1; + request_submit(req); + return 0; +} + ///////////////////////////////////////////////////////////////////// // Search support // @@ -1522,7 +1672,7 @@ search_state_decref(struct search_state *const state) { } free(state); } -}; +} static struct search_state * search_state_new(void) { @@ -1637,20 +1787,21 @@ search_make_new(const struct search_state *const state, int n, const char *const } static int -search_request_new(const char *const name, int flags, evdns_callback_type user_callback, void *user_arg) { +search_request_new(int type, const char *const name, int flags, evdns_callback_type user_callback, void *user_arg) { + assert(type == TYPE_A); if ( ((flags & DNS_QUERY_NO_SEARCH) == 0) && global_search_state && global_search_state->num_domains) { // we have some domains to search struct request *req; if (string_num_dots(name) >= global_search_state->ndots) { - req = request_new(name, flags, user_callback, user_arg); + req = request_new(type, name, flags, user_callback, user_arg); if (!req) return 1; req->search_index = -1; } else { char *const new_name = search_make_new(global_search_state, 0, name); if (!new_name) return 1; - req = request_new(new_name, flags, user_callback, user_arg); + req = request_new(type, new_name, flags, user_callback, user_arg); free(new_name); if (!req) return 1; req->search_index = 0; @@ -1662,7 +1813,7 @@ search_request_new(const char *const name, int flags, evdns_callback_type user_c request_submit(req); return 0; } else { - struct request *const req = request_new(name, flags, user_callback, user_arg); + struct request *const req = request_new(type, name, flags, user_callback, user_arg); if (!req) return 1; request_submit(req); return 0; @@ -1686,8 +1837,8 @@ search_try_next(struct request *const req) { // this name without a postfix if (string_num_dots(req->search_origname) < req->search_state->ndots) { // yep, we need to try it raw - struct request *const newreq = request_new(req->search_origname, req->search_flags, req->user_callback, req->user_pointer); - log("Search: trying raw query %s", req->search_origname); + struct request *const newreq = request_new(req->request_type, req->search_origname, req->search_flags, req->user_callback, req->user_pointer); + log(EVDNS_LOG_DEBUG, "Search: trying raw query %s", req->search_origname); if (newreq) { request_submit(newreq); return 0; @@ -1698,8 +1849,8 @@ search_try_next(struct request *const req) { new_name = search_make_new(req->search_state, req->search_index, req->search_origname); if (!new_name) return 1; - log("Search: now trying %s (%d)", new_name, req->search_index); - newreq = request_new(new_name, req->search_flags, req->user_callback, req->user_pointer); + log(EVDNS_LOG_DEBUG, "Search: now trying %s (%d)", new_name, req->search_index); + newreq = request_new(req->request_type, new_name, req->search_flags, req->user_callback, req->user_pointer); free(new_name); if (!newreq) return 1; newreq->search_origname = req->search_origname; @@ -1791,7 +1942,7 @@ resolv_conf_parse_line(char *const start, int flags) { const int ndots = strtoint(&option[6]); if (ndots == -1) continue; if (!(flags & DNS_OPTION_SEARCH)) continue; - log("Setting ndots to %d", ndots); + log(EVDNS_LOG_DEBUG, "Setting ndots to %d", ndots); if (!global_search_state) global_search_state = search_state_new(); if (!global_search_state) return; global_search_state->ndots = ndots; @@ -1799,13 +1950,14 @@ resolv_conf_parse_line(char *const start, int flags) { const int timeout = strtoint(&option[8]); if (timeout == -1) continue; if (!(flags & DNS_OPTION_MISC)) continue; - log("Setting timeout to %d", timeout); + log(EVDNS_LOG_DEBUG, "Setting timeout to %d", timeout); global_timeout.tv_sec = timeout; } else if (!strncmp(option, "attempts:", 9)) { - const int retries = strtoint(&option[9]); + int retries = strtoint(&option[9]); if (retries == -1) continue; + if (retries > 255) retries = 255; if (!(flags & DNS_OPTION_MISC)) continue; - log("Setting retries to %d", retries); + log(EVDNS_LOG_DEBUG, "Setting retries to %d", retries); global_max_retransmits = retries; } } @@ -1829,7 +1981,7 @@ evdns_resolv_conf_parse(int flags, const char *const filename) { char *start; int err = 0; - log("Parsing resolve.conf file %s", filename); + log(EVDNS_LOG_DEBUG, "Parsing resolv.conf file %s", filename); fd = open(filename, O_RDONLY); if (fd < 0) { @@ -1903,6 +2055,8 @@ evdns_nameserver_ip_add_line(const char *ips) { return 0; } +typedef DWORD(WINAPI *GetNetworkParams_fn_t)(FIXED_INFO *, DWORD*); + // Use the windows GetNetworkParams interface in iphlpapi.dll to // figure out what our nameservers are. static int @@ -1915,12 +2069,18 @@ load_nameservers_with_getnetworkparams(void) void *buf = NULL; int status = 0, r, added_any; IP_ADDR_STRING *ns; - DWORD (WINAPI *fn)(FIXED_INFO*, DWORD*); + GetNetworkParams_fn_t fn; - if (!(handle = LoadLibrary("iphlpapi.dll"))) + if (!(handle = LoadLibrary("iphlpapi.dll"))) { + log(EVDNS_LOG_WARN, "Could not open iphlpapi.dll"); + status = -1; goto done; - if (!(fn = GetProcAddress(handle, "GetNetworkParams"))) + } + if (!(fn = (GetNetworkParams_fn_t) GetProcAddress(handle, "GetNetworkParams"))) { + log(EVDNS_LOG_WARN, "Could not get address of function."); + status = -1; goto done; + } buf = malloc(size); if (!buf) { status = 4; goto done; } @@ -1936,21 +2096,35 @@ load_nameservers_with_getnetworkparams(void) if (!buf) { status = 4; goto done; } fixed = buf; r = fn(fixed, &size); - if (r != ERROR_SUCCESS) { status = -1; goto done; } + if (r != ERROR_SUCCESS) { + log(EVDNS_LOG_DEBUG, "fn() failed."); + status = -1; + goto done; + } } assert(fixed); added_any = 0; - ns = fixed->DnsServerList; + ns = &(fixed->DnsServerList); while (ns) { r = evdns_nameserver_ip_add_line(ns->IpAddress.String); - if (r) { status = r; goto done; } - added_any = 0; - ns = ns->next; + if (r) { + log(EVDNS_LOG_DEBUG,"Could not add nameserver %s to list,error: %d", + (ns->IpAddress.String),(int)GetLastError()); + status = r; + goto done; + } else { + log(EVDNS_LOG_DEBUG,"Succesfully added %s as nameserver",ns->IpAddress.String); + } + + added_any++; + ns = ns->Next; } - if (!added_any) + if (!added_any) { + log(EVDNS_LOG_DEBUG, "No nameservers added."); status = -1; + } done: if (buf) @@ -1982,39 +2156,60 @@ config_nameserver_from_reg_key(HKEY key, const char *subkey) return status; } +#define SERVICES_KEY "System\\CurrentControlSet\\Services\\" +#define WIN_NS_9X_KEY SERVICES_KEY "VxD\\MSTCP" +#define WIN_NS_NT_KEY SERVICES_KEY "Tcpip\\Parameters" + static int load_nameservers_from_registry(void) { int found = 0; + int r; #define TRY(k, name) \ if (!found && config_nameserver_from_reg_key(k,name) == 0) { \ - log("Found nameservers in %s/%s",#k,name); \ + log(EVDNS_LOG_DEBUG,"Found nameservers in %s/%s",#k,name); \ found = 1; \ + } else if (!found) { \ + log(EVDNS_LOG_DEBUG,"Didn't find nameservers in %s/%s", \ + #k,#name); \ } - if (IS_NT()) { + if (((int)GetVersion()) > 0) { /* NT */ HKEY nt_key = 0, interfaces_key = 0; if (RegOpenKeyEx(HKEY_LOCAL_MACHINE, WIN_NS_NT_KEY, 0, - KEY_READ, &nt_key) != ERROR_SUCCESS) + KEY_READ, &nt_key) != ERROR_SUCCESS) { + log(EVDNS_LOG_DEBUG,"Couldn't open nt key, %d",(int)GetLastError()); return -1; - RegOpenKeyEx(nt_key, "Interfaces", 0, - KEY_QUERY_VALUE|KEY_ENUMERATE_SUBKEYS, + } + r = RegOpenKeyEx(nt_key, "Interfaces", 0, + KEY_QUERY_VALUE|KEY_ENUMERATE_SUB_KEYS, &interfaces_key); - TRY(nt_key, NAMESERVER); - TRY(nt_key, DHCPNAMESERVER); - TRY(interfaces_key, NAMESERVER); - TRY(interfaces_key, DHCPNAMESERVER); + if (r != ERROR_SUCCESS) { + log(EVDNS_LOG_DEBUG,"Couldn't open interfaces key, %d",(int)GetLastError()); + return -1; + } + TRY(nt_key, "NameServer"); + TRY(nt_key, "DhcpNameServer"); + TRY(interfaces_key, "NameServer"); + TRY(interfaces_key, "DhcpNameServer"); RegCloseKey(interfaces_key); RegCloseKey(nt_key); } else { HKEY win_key = 0; - if (RegOpenKeyEx(HKEY_LOCAL_MACHINE, WIN_NS_9X, 0, - KEY_READ, &win_key) != ERROR_SUCCESS) + if (RegOpenKeyEx(HKEY_LOCAL_MACHINE, WIN_NS_9X_KEY, 0, + KEY_READ, &win_key) != ERROR_SUCCESS) { + log(EVDNS_LOG_DEBUG, "Couldn't open registry key, %d", (int)GetLastError()); return -1; - TRY(win_key, NAMESERVER); + } + TRY(win_key, "NameServer"); RegCloseKey(win_key); } + + if (found == 0) { + log(EVDNS_LOG_WARN,"Didn't find any nameservers."); + } + return found ? 0 : -1; #undef TRY } @@ -2040,3 +2235,128 @@ evdns_init() return (res); } + +const char * +evdns_err_to_string(int err) +{ + switch (err) { + case DNS_ERR_NONE: return "no error"; + case DNS_ERR_FORMAT: return "misformatted query"; + case DNS_ERR_SERVERFAILED: return "server failed"; + case DNS_ERR_NOTEXIST: return "name does not exist"; + case DNS_ERR_NOTIMPL: return "query not implemented"; + case DNS_ERR_REFUSED: return "refused"; + + case DNS_ERR_TRUNCATED: return "reply truncated or ill-formed"; + case DNS_ERR_UNKNOWN: return "unknown"; + case DNS_ERR_TIMEOUT: return "request timed out"; + case DNS_ERR_SHUTDOWN: return "dns subsystem shut down"; + default: return "[Unknown error code]"; + } +} + +void +evdns_shutdown(int fail_requests) +{ + struct nameserver *server, *server_next; + struct search_domain *dom, *dom_next; + + while (req_head) { + if (fail_requests) + reply_callback(req_head, 0, DNS_ERR_SHUTDOWN, NULL); + request_finished(req_head, &req_head); + } + while (req_waiting_head) { + if (fail_requests) + reply_callback(req_waiting_head, 0, DNS_ERR_SHUTDOWN, NULL); + request_finished(req_waiting_head, &req_waiting_head); + } + global_requests_inflight = global_requests_waiting = 0; + + for (server = server_head; server; server = server_next) { + server_next = server->next; + if (server->socket >= 0) + CLOSE_SOCKET(server->socket); + (void) event_del(&server->event); + free(server); + if (server_next == server_head) + break; + } + server_head = NULL; + global_good_nameservers = 0; + + if (global_search_state) { + for (dom = global_search_state->head; dom; dom = dom_next) { + dom_next = dom->next; + free(dom); + } + free(global_search_state); + global_search_state = NULL; + } + evdns_log_fn = NULL; +} + +#ifdef EVDNS_MAIN +void +main_callback(int result, char type, int count, int ttl, + void *addrs, void *orig) { + char *n = (char*)orig; + int i; + for (i = 0; i < count; ++i) { + if (type == DNS_IPv4_A) { + printf("%s: %s\n", n, debug_ntoa(((u32*)addrs)[i])); + } else if (type == DNS_PTR) { + printf("%s: %s\n", n, ((char**)addrs)[i]); + } + } + if (!count) { + printf("%s: No answer (%d)\n", n, result); + } + fflush(stdout); +} + +void +logfn(const char *msg) { + fprintf(stderr, "%s\n", msg); +} +int +main(int c, char **v) { + int idx; + int reverse = 0, verbose = 1; + if (c<2) { + fprintf(stderr, "syntax: %s [-x] [-v] hostname\n", v[0]); + return 1; + } + idx = 1; + while (idx < c && v[idx][0] == '-') { + if (!strcmp(v[idx], "-x")) + reverse = 1; + else if (!strcmp(v[idx], "-v")) + verbose = 1; + else + fprintf(stderr, "Unknown option %s\n", v[idx]); + ++idx; + } + event_init(); + if (verbose) + evdns_set_log_fn(logfn); + evdns_resolv_conf_parse(DNS_OPTION_NAMESERVERS, "/etc/resolv.conf"); + for (; idx < c; ++idx) { + if (reverse) { + struct in_addr addr; + if (!inet_aton(v[idx], &addr)) { + fprintf(stderr, "Skipping non-IP %s\n", v[idx]); + continue; + } + fprintf(stderr, "resolving %s...\n",v[idx]); + evdns_resolve_reverse(&addr, 0, main_callback, v[idx]); + } else { + fprintf(stderr, "resolving (fwd) %s...\n",v[idx]); + evdns_resolve_ipv4(v[idx], 0, main_callback, v[idx]); + } + } + fflush(stdout); + event_dispatch(); + return 0; +} +#endif diff --git a/evdns.h b/evdns.h index ff620e6e..f631d545 100644 --- a/evdns.h +++ b/evdns.h @@ -36,8 +36,11 @@ #define DNS_ERR_UNKNOWN 66 /* Communication with the server timed out */ #define DNS_ERR_TIMEOUT 67 +/* The request was canceled because the DNS subsystem was shut down. */ +#define DNS_ERR_SHUTDOWN 68 #define DNS_IPv4_A 1 +#define DNS_PTR 2 #define DNS_QUERY_NO_SEARCH 1 @@ -48,13 +51,17 @@ typedef void (*evdns_callback_type) (int result, char type, int count, int ttl, void *addresses, void *arg); -int evdns_init(); +int evdns_init(void); +void evdns_shutdown(int fail_requests); +const char *evdns_err_to_string(int err); int evdns_nameserver_add(unsigned long int address); int evdns_count_nameservers(void); int evdns_clear_nameservers_and_suspend(void); int evdns_resume(void); int evdns_nameserver_ip_add(const char *ip_as_string); -int evdns_resolve(const char *name, int flags, evdns_callback_type callback, void *ptr); +int evdns_resolve_ipv4(const char *name, int flags, evdns_callback_type callback, void *ptr); +struct in_addr; +int evdns_resolve_reverse(struct in_addr *in, int flags, evdns_callback_type callback, void *ptr); int evdns_resolv_conf_parse(int flags, const char *); #ifdef MS_WINDOWS int evdns_config_windows_nameservers(void); @@ -63,7 +70,7 @@ void evdns_search_clear(void); void evdns_search_add(const char *domain); void evdns_search_ndots_set(const int ndots); -typedef void (*evdns_debug_log_fn_type)(const char *msg); +typedef void (*evdns_debug_log_fn_type)(int is_warning, const char *msg); void evdns_set_log_fn(evdns_debug_log_fn_type fn); #define DNS_NO_SEARCH 1 diff --git a/test/regress_dns.c b/test/regress_dns.c index 0b3382e1..370592cf 100644 --- a/test/regress_dns.c +++ b/test/regress_dns.c @@ -43,6 +43,7 @@ #ifndef WIN32 #include #include +#include #include #endif #include @@ -71,7 +72,26 @@ void dns_gethostbyname() { fprintf(stdout, "Simple DNS resolve: "); - evdns_resolve("www.monkey.org", 0, dns_gethostbyname_cb, NULL); + dns_ok = 0; + evdns_resolve_ipv4("www.monkey.org", 0, dns_gethostbyname_cb, NULL); + event_dispatch(); + + if (dns_ok) { + fprintf(stdout, "OK\n"); + } else { + fprintf(stdout, "FAILED\n"); + exit(1); + } +} + +void +dns_gethostbyaddr() +{ + struct in_addr in; + in.s_addr = htonl(0x7f000001ul); /* 127.0.0.1 */ + fprintf(stdout, "Simple reverse DNS resolve: "); + dns_ok = 0; + evdns_resolve_reverse(&in, 0, dns_gethostbyname_cb, NULL); event_dispatch(); if (dns_ok) { @@ -87,6 +107,7 @@ dns_suite(void) { evdns_init(); dns_gethostbyname(); + dns_gethostbyaddr(); - evdns_clear_nameservers_and_suspend(); + evdns_shutdown(0); }