diff options
Diffstat (limited to 'evdns.c')
| -rw-r--r-- | evdns.c | 3115 |
1 files changed, 0 insertions, 3115 deletions
@@ -1,3115 +0,0 @@ -/* $Id: evdns.c,v 1.16 2007-11-06 16:09:37 root Exp $ */ - -/* The original version of this module was written by Adam Langley; for - * a history of modifications, check out the subversion logs. - * - * When editing this module, try to keep it re-mergeable by Adam. Don't - * reformat the whitespace, add Tor dependencies, or so on. - * - * TODO: - * - Support IPv6 and PTR records. - * - Replace all externally visible magic numbers with #defined constants. - * - Write doccumentation for APIs of all external functions. - */ - -/* Async DNS Library - * Adam Langley <agl@imperialviolet.org> - * http://www.imperialviolet.org/eventdns.html - * 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 - * Creative Commons, 559 Nathan Abbott Way, Stanford, California 94305, USA. - * - * I ask and expect, but do not require, that all derivative works contain an - * attribution similar to: - * Parts developed by Adam Langley <agl@imperialviolet.org> - * - * You may wish to replace the word "Parts" with something else depending on - * the amount of original code. - * - * (Derivative works does not include programs which link against, run or include - * the source verbatim in their source distributions) - * - * Version: 0.1b - */ - -#include <sys/types.h> -#ifdef HAVE_CONFIG_H -#include "config.h" -#endif - -#ifdef WIN32 -#ifndef EV_STANDALONE -#include "misc.h" -#endif -#endif - -/* #define NDEBUG */ - -#ifndef DNS_USE_CPU_CLOCK_FOR_ID -#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. -#endif -#endif -#endif - -/* #define _POSIX_C_SOURCE 200507 */ -#define _GNU_SOURCE - -#ifdef DNS_USE_CPU_CLOCK_FOR_ID -#ifdef DNS_USE_OPENSSL_FOR_ID -#error Multiple id options selected -#endif -#ifdef DNS_USE_GETTIMEOFDAY_FOR_ID -#error Multiple id options selected -#endif -#include <time.h> -#endif - -#ifdef DNS_USE_OPENSSL_FOR_ID -#ifdef DNS_USE_GETTIMEOFDAY_FOR_ID -#error Multiple id options selected -#endif -#include <openssl/rand.h> -#endif - -#define _FORTIFY_SOURCE 3 - -#include <string.h> -#include <fcntl.h> -#ifdef HAVE_STDINT_H -#include <stdint.h> -#endif -#include <stdlib.h> -#include <string.h> -#include <errno.h> -#include <assert.h> -#include <limits.h> -#include <sys/stat.h> -#include <ctype.h> -#include <stdio.h> -#include <stdarg.h> - -#include "evdns.h" -#ifdef WIN32 -#include <windows.h> -#include <winsock2.h> -#include <iphlpapi.h> -#else -#include <sys/socket.h> -#include <netinet/in.h> -#include <arpa/inet.h> -#endif - -#ifdef HAVE_NETINET_IN6_H -#include <netinet/in6.h> -#endif - -#ifdef WIN32 -typedef int socklen_t; -#endif - -#define EVDNS_LOG_DEBUG 0 -#define EVDNS_LOG_WARN 1 - -#ifndef HOST_NAME_MAX -#define HOST_NAME_MAX 255 -#endif - -#ifndef NDEBUG -#include <stdio.h> -#endif - -#undef MIN -#define MIN(a,b) ((a)<(b)?(a):(b)) - -#ifdef __USE_ISOC99B -/* libevent doesn't work without this */ -typedef uint8_t u_char; -typedef unsigned int uint; -#endif -#include <event.h> - -#define u64 uint64_t -#define u32 uint32_t -#define u16 uint16_t -#define u8 uint8_t - -#define MAX_ADDRS 4 /* maximum number of addresses from a single packet */ -/* which we bother recording */ - -#define TYPE_A EVDNS_TYPE_A -#define TYPE_CNAME 5 -#define TYPE_PTR EVDNS_TYPE_PTR -#define TYPE_AAAA EVDNS_TYPE_AAAA - -#define CLASS_INET EVDNS_CLASS_INET - -struct request { - u8 *request; /* the dns packet data */ - 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 */ - - /* elements used by the searching code */ - int search_index; - struct search_state *search_state; - char *search_origname; /* needs to be free()ed */ - int search_flags; - - /* these objects are kept in a circular list */ - struct request *next, *prev; - - struct event timeout_event; - - u16 trans_id; /* the transaction id */ - char request_appended; /* true if the request pointer is data which follows this struct */ - char transmit_me; /* needs to be transmitted */ -}; - -#ifndef HAVE_STRUCT_IN6_ADDR -struct in6_addr { - u8 s6_addr[16]; -}; -#endif - -struct reply { - unsigned int type; - unsigned int have_answer; - union { - struct { - u32 addrcount; - u32 addresses[MAX_ADDRS]; - } a; - struct { - u32 addrcount; - struct in6_addr addresses[MAX_ADDRS]; - } aaaa; - struct { - char name[HOST_NAME_MAX]; - } ptr; - } data; -}; - -struct nameserver { - int socket; /* a connected UDP socket */ - u32 address; - int failed_times; /* number of times which we have given this server a chance */ - int timedout; /* number of times in a row a request has timed out */ - struct event event; - /* these objects are kept in a circular list */ - struct nameserver *next, *prev; - struct event timeout_event; /* used to keep the timeout for */ - /* when we next probe this server. */ - /* Valid if state == 0 */ - char state; /* zero if we think that this server is down */ - char choked; /* true if we have an EAGAIN from this server's socket */ - char write_waiting; /* true if we are waiting for EV_WRITE events */ -}; - -static struct request *req_head = NULL, *req_waiting_head = NULL; -static struct nameserver *server_head = NULL; - -/* Represents a local port where we're listening for DNS requests. Right now, */ -/* only UDP is supported. */ -struct evdns_server_port { - int socket; /* socket we use to read queries and write replies. */ - int refcnt; /* reference count. */ - char choked; /* Are we currently blocked from writing? */ - char closing; /* Are we trying to close this port, pending writes? */ - evdns_request_callback_fn_type user_callback; /* Fn to handle requests */ - void *user_data; /* Opaque pointer passed to user_callback */ - struct event event; /* Read/write event */ - /* circular list of replies that we want to write. */ - struct server_request *pending_replies; -}; - -/* Represents part of a reply being built. (That is, a single RR.) */ -struct server_reply_item { - struct server_reply_item *next; /* next item in sequence. */ - char *name; /* name part of the RR */ - u16 type : 16; /* The RR type */ - u16 class : 16; /* The RR class (usually CLASS_INET) */ - u32 ttl; /* The RR TTL */ - char is_name; /* True iff data is a label */ - u16 datalen; /* Length of data; -1 if data is a label */ - void *data; /* The contents of the RR */ -}; - -/* Represents a request that we've received as a DNS server, and holds */ -/* the components of the reply as we're constructing it. */ -struct server_request { - /* Pointers to the next and previous entries on the list of replies */ - /* that we're waiting to write. Only set if we have tried to respond */ - /* and gotten EAGAIN. */ - struct server_request *next_pending; - struct server_request *prev_pending; - - u16 trans_id; /* Transaction id. */ - struct evdns_server_port *port; /* Which port received this request on? */ - struct sockaddr_storage addr; /* Where to send the response */ - socklen_t addrlen; /* length of addr */ - - int n_answer; /* how many answer RRs have been set? */ - int n_authority; /* how many authority RRs have been set? */ - int n_additional; /* how many additional RRs have been set? */ - - struct server_reply_item *answer; /* linked list of answer RRs */ - struct server_reply_item *authority; /* linked list of authority RRs */ - struct server_reply_item *additional; /* linked list of additional RRs */ - - /* Constructed response. Only set once we're ready to send a reply. */ - /* Once this is set, the RR fields are cleared, and no more should be set. */ - char *response; - size_t response_len; - - /* Caller-visible fields: flags, questions. */ - struct evdns_server_request base; -}; - -/* helper macro */ -#define OFFSET_OF(st, member) ((off_t) (((char*)&((st*)0)->member)-(char*)0)) - -/* Given a pointer to an evdns_server_request, get the corresponding */ -/* server_request. */ -#define TO_SERVER_REQUEST(base_ptr) \ - ((struct server_request*) \ - (((char*)(base_ptr) - OFFSET_OF(struct server_request, base)))) - -/* The number of good nameservers that we have */ -static int global_good_nameservers = 0; - -/* inflight requests are contained in the req_head list */ -/* and are actually going out across the network */ -static int global_requests_inflight = 0; -/* requests which aren't inflight are in the waiting list */ -/* and are counted here */ -static int global_requests_waiting = 0; - -static int global_max_requests_inflight = 64; - -static struct timeval global_timeout = {5, 0}; /* 5 seconds */ -static int global_max_reissues = 1; /* a reissue occurs when we get some errors from the server */ -static int global_max_retransmits = 3; /* number of times we'll retransmit a request which timed out */ -/* number of timeouts in a row before we consider this server to be down */ -static int global_max_nameserver_timeout = 3; - -/* These are the timeout values for nameservers. If we find a nameserver is down */ -/* we try to probe it at intervals as given below. Values are in seconds. */ -static const struct timeval global_nameserver_timeouts[] = {{10, 0}, {60, 0}, {300, 0}, {900, 0}, {3600, 0}}; -static const int global_nameserver_timeouts_length = sizeof(global_nameserver_timeouts)/sizeof(struct timeval); - -static struct nameserver *nameserver_pick(void); -static void evdns_request_insert(struct request *req, struct request **head); -static void nameserver_ready_callback(int fd, short events, void *arg); -static int evdns_transmit(void); -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(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(int type, const char *name, int flags, evdns_callback_type callback, void *ptr); -static void request_submit(struct request *req); - -static int server_request_free(struct server_request *req); -static void server_request_free_answers(struct server_request *req); -static void server_port_free(struct evdns_server_port *port); -static void server_port_ready_callback(int fd, short events, void *arg); - -static int strtoint(const char *const str); - -#ifdef WIN32 -static int -last_error(int sock) -{ - int optval, optvallen=sizeof(optval); - int err = WSAGetLastError(); - if (err == WSAEWOULDBLOCK && sock >= 0) { - if (getsockopt(sock, SOL_SOCKET, SO_ERROR, (void*)&optval, - &optvallen)) - return err; - if (optval) - return optval; - } - return err; - -} -static int -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) -#define error_is_eagain(err) ((err) == EAGAIN) -#define CLOSE_SOCKET(x) close(x) -#endif - -#define ISSPACE(c) isspace((int)(unsigned char)(c)) -#define ISDIGIT(c) isdigit((int)(unsigned char)(c)) - -#ifndef NDEBUG -static const char * -debug_ntoa(u32 address) -{ - static char buf[32]; - u32 a = ntohl(address); - snprintf(buf, sizeof(buf), "%d.%d.%d.%d", - (int)(u8)((a>>24)&0xff), - (int)(u8)((a>>16)&0xff), - (int)(u8)((a>>8 )&0xff), - (int)(u8)((a )&0xff)); - return buf; -} -#endif - -static evdns_debug_log_fn_type evdns_log_fn = NULL; - -void -evdns_set_log_fn(evdns_debug_log_fn_type fn) -{ - evdns_log_fn = fn; -} - -#ifdef __GNUC__ -#define EVDNS_LOG_CHECK __attribute__ ((format(printf, 2, 3))) -#else -#define EVDNS_LOG_CHECK -#endif - -static void _evdns_log(int warn, const char *fmt, ...) EVDNS_LOG_CHECK; -static void -_evdns_log(int warn, const char *fmt, ...) -{ - va_list args; - static char buf[512]; - if (!evdns_log_fn) - return; - va_start(args,fmt); -#ifdef WIN32 - _vsnprintf(buf, sizeof(buf), fmt, args); -#else - vsnprintf(buf, sizeof(buf), fmt, args); -#endif - buf[sizeof(buf)-1] = '\0'; - evdns_log_fn(warn, buf); - va_end(args); -} - -#define log _evdns_log - -/* This walks the list of inflight requests to find the */ -/* one with a matching transaction id. Returns NULL on */ -/* failure */ -static struct request * -request_find_from_trans_id(u16 trans_id) { - struct request *req = req_head, *const started_at = req_head; - - if (req) { - do { - if (req->trans_id == trans_id) return req; - req = req->next; - } while (req != started_at); - } - - return NULL; -} - -/* a libevent callback function which is called when a nameserver */ -/* has gone down and we want to test if it has came back to life yet */ -static void -nameserver_prod_callback(int fd, short events, void *arg) { - struct nameserver *const ns = (struct nameserver *) arg; - (void)fd; - (void)events; - - nameserver_send_probe(ns); -} - -/* a libevent callback which is called when a nameserver probe (to see if */ -/* it has come back to life) times out. We increment the count of failed_times */ -/* and wait longer to send the next probe packet. */ -static void -nameserver_probe_failed(struct nameserver *const ns) { - const struct timeval * timeout; - (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)]; - ns->failed_times++; - - evtimer_set(&ns->timeout_event, nameserver_prod_callback, ns); - if (evtimer_add(&ns->timeout_event, (struct timeval *) timeout) < 0) { - log(EVDNS_LOG_WARN, - "Error from libevent when adding timer event for %s", - debug_ntoa(ns->address)); - /* ???? Do more? */ - } -} - -/* called when a nameserver has been deemed to have failed. For example, too */ -/* many packets have timed out etc */ -static void -nameserver_failed(struct nameserver *const ns, const char *msg) { - struct request *req, *started_at; - /* if this nameserver has already been marked as failed */ - /* then don't do anything */ - if (!ns->state) return; - - 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(EVDNS_LOG_WARN, "All nameservers have failed"); - } - - ns->state = 0; - ns->failed_times = 1; - - evtimer_set(&ns->timeout_event, nameserver_prod_callback, ns); - if (evtimer_add(&ns->timeout_event, (struct timeval *) &global_nameserver_timeouts[0]) < 0) { - 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 */ - /* a different server. Requests in the waiting queue don't have a */ - /* nameserver assigned yet */ - - /* if we don't have *any* good nameservers then there's no point */ - /* trying to reassign requests to one */ - if (!global_good_nameservers) return; - - req = req_head; - started_at = req_head; - if (req) { - do { - if (req->tx_count == 0 && req->ns == ns) { - /* still waiting to go out, can be moved */ - /* to another server */ - req->ns = nameserver_pick(); - } - req = req->next; - } while (req != started_at); - } -} - -static void -nameserver_up(struct nameserver *const ns) { - if (ns->state) return; - 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; - ns->timedout = 0; - global_good_nameservers++; -} - -static void -request_trans_id_set(struct request *const req, const u16 trans_id) { - req->trans_id = trans_id; - *((u16 *) req->request) = htons(trans_id); -} - -/* Called to remove a request from a list and dealloc it. */ -/* head is a pointer to the head of the list it should be */ -/* removed from or NULL if the request isn't in a list. */ -static void -request_finished(struct request *const req, struct request **head) { - if (head) { - if (req->next == req) { - /* only item in the list */ - *head = NULL; - } else { - req->next->prev = req->prev; - req->prev->next = req->next; - if (*head == req) *head = req->next; - } - } - - log(EVDNS_LOG_DEBUG, "Removing timeout for request %lx", - (unsigned long) req); - evtimer_del(&req->timeout_event); - - search_request_finished(req); - global_requests_inflight--; - - if (!req->request_appended) { - /* need to free the request data on it's own */ - free(req->request); - } else { - /* the request data is appended onto the header */ - /* so everything gets free()ed when we: */ - } - - free(req); - - evdns_requests_pump_waiting_queue(); -} - -/* This is called when a server returns a funny error code. */ -/* We try the request again with another server. */ -/* */ -/* return: */ -/* 0 ok */ -/* 1 failed/reissue is pointless */ -static int -request_reissue(struct request *req) { - const struct nameserver *const last_ns = req->ns; - /* the last nameserver should have been marked as failing */ - /* by the caller of this function, therefore pick will try */ - /* not to return it */ - req->ns = nameserver_pick(); - if (req->ns == last_ns) { - /* ... but pick did return it */ - /* not a lot of point in trying again with the */ - /* same server */ - return 1; - } - - req->reissue_count++; - req->tx_count = 0; - req->transmit_me = 1; - - return 0; -} - -/* this function looks for space on the inflight queue and promotes */ -/* requests from the waiting queue if it can. */ -static void -evdns_requests_pump_waiting_queue(void) { - while (global_requests_inflight < global_max_requests_inflight && - global_requests_waiting) { - struct request *req; - /* move a request from the waiting queue to the inflight queue */ - assert(req_waiting_head); - if (req_waiting_head->next == req_waiting_head) { - /* only one item in the queue */ - req = req_waiting_head; - req_waiting_head = NULL; - } else { - req = req_waiting_head; - req->next->prev = req->prev; - req->prev->next = req->next; - req_waiting_head = req->next; - } - - global_requests_waiting--; - global_requests_inflight++; - - req->ns = nameserver_pick(); - request_trans_id_set(req, transaction_id_pick()); - - evdns_request_insert(req, &req_head); - evdns_request_transmit(req); - evdns_transmit(); - } -} - -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; - case TYPE_AAAA: - if (reply) - req->user_callback(DNS_ERR_NONE, DNS_IPv6_AAAA, - reply->data.aaaa.addrcount, ttl, - reply->data.aaaa.addresses, - 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(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}; - - if (flags & 0x020f || !reply || !reply->have_answer) { - /* there was an error */ - if (flags & 0x0200) { - error = DNS_ERR_TRUNCATED; - } else { - u16 error_code = (flags & 0x000f) - 1; - if (error_code > 4) { - error = DNS_ERR_UNKNOWN; - } else { - error = error_codes[error_code]; - } - } - - switch(error) { - case DNS_ERR_NOTIMPL: - case DNS_ERR_REFUSED: - /* 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 (%s)", - error, evdns_err_to_string(error)); - nameserver_failed(req->ns, msg); - if (!request_reissue(req)) return; - } - break; - case DNS_ERR_SERVERFAILED: - /* rcode 2 (servfailed) sometimes means "we are broken" and - * sometimes (with some binds) means "that request was very - * confusing." Treat this as a timeout, not a failure. - */ - log(EVDNS_LOG_DEBUG, "Got a SERVERFAILED from nameserver %s; " - "will allow the request to time out.", - debug_ntoa(req->ns->address)); - break; - default: - /* we got a good reply from the nameserver */ - nameserver_up(req->ns); - } - - 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 */ - /* the user callback will be made when that request (or a */ - /* child of it) finishes. */ - request_finished(req, &req_head); - return; - } - } - - /* all else failed. Pass the failure up */ - reply_callback(req, 0, error, NULL); - request_finished(req, &req_head); - } else { - /* all ok, tell the user */ - reply_callback(req, ttl, 0, reply); - nameserver_up(req->ns); - request_finished(req, &req_head); - } -} - -static int -name_parse(u8 *packet, int length, int *idx, char *name_out, int name_out_len) { - int name_end = -1; - int j = *idx; - int ptr_count = 0; -#define GET32(x) do { if (j + 4 > length) goto err; memcpy(&_t32, packet + j, 4); j += 4; x = ntohl(_t32); } while(0) -#define GET16(x) do { if (j + 2 > length) goto err; memcpy(&_t, packet + j, 2); j += 2; x = ntohs(_t); } while(0) -#define GET8(x) do { if (j >= length) goto err; 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; - /* Make sure that the target offset is in-bounds. */ - if (j < 0 || j >= length) return -1; - /* If we've jumped more times than there are characters in the - * message, we must have a loop. */ - if (++ptr_count > 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; - err: - return -1; -} - -/* parses a raw request from a nameserver */ -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 */ - - u16 trans_id, questions, answers, authority, additional, datalength; - u16 flags = 0; - u32 ttl, ttl_r = 0xffffffff; - struct reply reply; - struct request *req = NULL; - unsigned int i; - - GET16(trans_id); - GET16(flags); - GET16(questions); - GET16(answers); - GET16(authority); - GET16(additional); - (void) authority; /* suppress "unused variable" warnings. */ - (void) additional; /* suppress "unused variable" warnings. */ - - req = request_find_from_trans_id(trans_id); - if (!req) return -1; - - memset(&reply, 0, sizeof(reply)); - - /* If it's not an answer, it doesn't correspond to any request. */ - if (!(flags & 0x8000)) return -1; /* must be an answer */ - if (flags & 0x020f) { - /* there was an error */ - goto err; - } - /* if (!answers) return; */ /* must have an answer of some form */ - - /* This macro skips a name in the DNS reply. */ -#define SKIP_NAME \ - do { tmp_name[0] = '\0'; \ - if (name_parse(packet, length, &j, tmp_name, sizeof(tmp_name))<0) \ - goto err; \ - } while(0); - - reply.type = req->request_type; - - /* skip over each question in the reply */ - for (i = 0; i < questions; ++i) { - /* the question looks like - * <label:name><u16:type><u16:class> - */ - SKIP_NAME; - j += 4; - if (j >= length) goto err; - } - - /* now we have the answer section which looks like - * <label:name><u16:type><u16:class><u32:ttl><u16:len><data...> - */ - - for (i = 0; i < answers; ++i) { - u16 type, class; - - SKIP_NAME; - GET16(type); - GET16(class); - GET32(ttl); - GET16(datalength); - - if (type == TYPE_A && class == CLASS_INET) { - int addrcount, addrtocopy; - if (req->request_type != TYPE_A) { - j += datalength; continue; - } - if ((datalength & 3) != 0) /* not an even number of As. */ - goto err; - 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) goto err; - memcpy(&reply.data.a.addresses[reply.data.a.addrcount], - packet + j, 4*addrtocopy); - j += 4*addrtocopy; - 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) - goto err; - ttl_r = MIN(ttl_r, ttl); - reply.have_answer = 1; - break; - } else if (type == TYPE_AAAA && class == CLASS_INET) { - int addrcount, addrtocopy; - if (req->request_type != TYPE_AAAA) { - j += datalength; continue; - } - if ((datalength & 15) != 0) /* not an even number of AAAAs. */ - goto err; - addrcount = datalength >> 4; /* each address is 16 bytes long */ - addrtocopy = MIN(MAX_ADDRS - reply.data.aaaa.addrcount, (unsigned)addrcount); - ttl_r = MIN(ttl_r, ttl); - - /* we only bother with the first four addresses. */ - if (j + 16*addrtocopy > length) goto err; - memcpy(&reply.data.aaaa.addresses[reply.data.aaaa.addrcount], - packet + j, 16*addrtocopy); - reply.data.aaaa.addrcount += addrtocopy; - j += 16*addrtocopy; - reply.have_answer = 1; - if (reply.data.aaaa.addrcount == MAX_ADDRS) break; - } else { - /* skip over any other type of resource */ - j += datalength; - } - } - - reply_handle(req, flags, ttl_r, &reply); - return 0; - err: - if (req) - reply_handle(req, flags, 0, NULL); - return -1; -} - -/* Parse a raw request (packet,length) sent to a nameserver port (port) from */ -/* a DNS client (addr,addrlen), and if it's well-formed, call the corresponding */ -/* callback. */ -static int -request_parse(u8 *packet, int length, struct evdns_server_port *port, struct sockaddr *addr, socklen_t addrlen) -{ - int j = 0; /* index into packet */ - u16 _t; /* used by the macros */ - char tmp_name[256]; /* used by the macros */ - - int i; - u16 trans_id, flags, questions, answers, authority, additional; - struct server_request *server_req = NULL; - - /* Get the header fields */ - GET16(trans_id); - GET16(flags); - GET16(questions); - GET16(answers); - GET16(authority); - GET16(additional); - - if (flags & 0x8000) return -1; /* Must not be an answer. */ - if (flags & 0x7800) return -1; /* only standard queries are supported */ - flags &= 0x0300; /* Only TC and RD get preserved. */ - - server_req = malloc(sizeof(struct server_request)); - if (server_req == NULL) return -1; - memset(server_req, 0, sizeof(struct server_request)); - - server_req->trans_id = trans_id; - memcpy(&server_req->addr, addr, addrlen); - server_req->addrlen = addrlen; - - server_req->base.flags = flags; - server_req->base.nquestions = 0; - server_req->base.questions = malloc(sizeof(struct evdns_server_question *) * questions); - if (server_req->base.questions == NULL) - goto err; - - for (i = 0; i < questions; ++i) { - u16 type, class; - struct evdns_server_question *q; - int namelen; - if (name_parse(packet, length, &j, tmp_name, sizeof(tmp_name))<0) - goto err; - GET16(type); - GET16(class); - namelen = strlen(tmp_name); - q = malloc(sizeof(struct evdns_server_question) + namelen); - if (!q) - goto err; - q->type = type; - q->class = class; - memcpy(q->name, tmp_name, namelen+1); - server_req->base.questions[server_req->base.nquestions++] = q; - } - - /* Ignore answers, authority, and additional. */ - - server_req->port = port; - port->refcnt++; - port->user_callback(&(server_req->base), port->user_data); - - return 0; -err: - if (server_req) { - if (server_req->base.questions) { - for (i = 0; i < server_req->base.nquestions; ++i) - free(server_req->base.questions[i]); - free(server_req->base.questions); - } - free(server_req); - } - return -1; - -#undef SKIP_NAME -#undef GET32 -#undef GET16 -#undef GET8 -} - -/* Try to choose a strong transaction id which isn't already in flight */ -static u16 -transaction_id_pick(void) { - for (;;) { - const struct request *req = req_head, *started_at; -#ifdef DNS_USE_CPU_CLOCK_FOR_ID - struct timespec ts; - u16 trans_id; -#ifdef CLOCK_MONOTONIC - if (clock_gettime(CLOCK_MONOTONIC, &ts) == -1) -#else - if (clock_gettime(CLOCK_REALTIME, &ts) == -1) -#endif - event_err(1, "clock_gettime"); - trans_id = ts.tv_nsec & 0xffff; -#endif - -#ifdef DNS_USE_GETTIMEOFDAY_FOR_ID - struct timeval tv; - u16 trans_id; - gettimeofday(&tv, NULL); - trans_id = tv.tv_usec & 0xffff; -#endif - -#ifdef DNS_USE_OPENSSL_FOR_ID - u16 trans_id; - if (RAND_pseudo_bytes((u8 *) &trans_id, 2) == -1) { - /* in the case that the RAND call fails we back */ - /* down to using gettimeofday. */ - struct timeval tv; - gettimeofday(&tv, NULL); - trans_id = tv.tv_usec & 0xffff; */ - abort(); - } -#endif - - if (trans_id == 0xffff) continue; - /* now check to see if that id is already inflight */ - req = started_at = req_head; - if (req) { - do { - if (req->trans_id == trans_id) break; - req = req->next; - } while (req != started_at); - } - /* we didn't find it, so this is a good id */ - if (req == started_at) return trans_id; - } -} - -/* choose a namesever to use. This function will try to ignore */ -/* nameservers which we think are down and load balance across the rest */ -/* by updating the server_head global each time. */ -static struct nameserver * -nameserver_pick(void) { - struct nameserver *started_at = server_head, *picked; - if (!server_head) return NULL; - - /* if we don't have any good nameservers then there's no */ - /* point in trying to find one. */ - if (!global_good_nameservers) { - server_head = server_head->next; - return server_head; - } - - /* remember that nameservers are in a circular list */ - for (;;) { - if (server_head->state) { - /* we think this server is currently good */ - picked = server_head; - server_head = server_head->next; - return picked; - } - - server_head = server_head->next; - if (server_head == started_at) { - /* all the nameservers seem to be down */ - /* so we just return this one and hope for the */ - /* best */ - assert(global_good_nameservers == 0); - picked = server_head; - server_head = server_head->next; - return picked; - } - } -} - -/* this is called when a namesever socket is ready for reading */ -static void -nameserver_read(struct nameserver *ns) { - u8 packet[1500]; - - for (;;) { - const int r = recv(ns->socket, packet, sizeof(packet), 0); - if (r < 0) { - int err = last_error(ns->socket); - if (error_is_eagain(err)) return; - nameserver_failed(ns, strerror(err)); - return; - } - ns->timedout = 0; - reply_parse(packet, r); - } -} - -/* Read a packet from a DNS client on a server port s, parse it, and */ -/* act accordingly. */ -static void -server_port_read(struct evdns_server_port *s) { - u8 packet[1500]; - struct sockaddr_storage addr; - socklen_t addrlen; - int r; - - for (;;) { - addrlen = sizeof(struct sockaddr_storage); - r = recvfrom(s->socket, packet, sizeof(packet), 0, - (struct sockaddr*) &addr, &addrlen); - if (r < 0) { - int err = last_error(s->socket); - if (error_is_eagain(err)) return; - log(EVDNS_LOG_WARN, "Error %s (%d) while reading request.", - strerror(err), err); - return; - } - request_parse(packet, r, s, (struct sockaddr*) &addr, addrlen); - } -} - -/* Try to write all pending replies on a given DNS server port. */ -static void -server_port_flush(struct evdns_server_port *port) -{ - while (port->pending_replies) { - struct server_request *req = port->pending_replies; - int r = sendto(port->socket, req->response, req->response_len, 0, - (struct sockaddr*) &req->addr, req->addrlen); - if (r < 0) { - int err = last_error(port->socket); - if (error_is_eagain(err)) - return; - log(EVDNS_LOG_WARN, "Error %s (%d) while writing response to port; dropping", strerror(err), err); - } - if (server_request_free(req)) { - /* we released the last reference to req->port. */ - return; - } - } - - /* We have no more pending requests; stop listening for 'writeable' events. */ - (void) event_del(&port->event); - event_set(&port->event, port->socket, EV_READ | EV_PERSIST, - server_port_ready_callback, port); - if (event_add(&port->event, NULL) < 0) { - log(EVDNS_LOG_WARN, "Error from libevent when adding event for DNS server."); - /* ???? Do more? */ - } -} - -/* set if we are waiting for the ability to write to this server. */ -/* if waiting is true then we ask libevent for EV_WRITE events, otherwise */ -/* we stop these events. */ -static void -nameserver_write_waiting(struct nameserver *ns, char waiting) { - if (ns->write_waiting == waiting) return; - - ns->write_waiting = waiting; - (void) event_del(&ns->event); - 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(EVDNS_LOG_WARN, "Error from libevent when adding event for %s", - debug_ntoa(ns->address)); - /* ???? Do more? */ - } -} - -/* a callback function. Called by libevent when the kernel says that */ -/* a nameserver socket is ready for writing or reading */ -static void -nameserver_ready_callback(int fd, short events, void *arg) { - struct nameserver *ns = (struct nameserver *) arg; - (void)fd; - - if (events & EV_WRITE) { - ns->choked = 0; - if (!evdns_transmit()) { - nameserver_write_waiting(ns, 0); - } - } - if (events & EV_READ) { - nameserver_read(ns); - } -} - -/* a callback function. Called by libevent when the kernel says that */ -/* a server socket is ready for writing or reading. */ -static void -server_port_ready_callback(int fd, short events, void *arg) { - struct evdns_server_port *port = (struct evdns_server_port *) arg; - (void) fd; - - if (events & EV_WRITE) { - port->choked = 0; - server_port_flush(port); - } - if (events & EV_READ) { - server_port_read(port); - } -} - -/* This is an inefficient representation; only use it via the dnslabel_table_* - * functions, so that is can be safely replaced with something smarter later. */ -#define MAX_LABELS 128 -/* Structures used to implement name compression */ -struct dnslabel_entry { char *v; off_t pos; }; -struct dnslabel_table { - int n_labels; /* number of current entries */ - /* map from name to position in message */ - struct dnslabel_entry labels[MAX_LABELS]; -}; - -/* Initialize dnslabel_table. */ -static void -dnslabel_table_init(struct dnslabel_table *table) -{ - table->n_labels = 0; -} - -/* Free all storage held by table, but not the table itself. */ -static void -dnslabel_clear(struct dnslabel_table *table) -{ - int i; - for (i = 0; i < table->n_labels; ++i) - free(table->labels[i].v); - table->n_labels = 0; -} - -/* return the position of the label in the current message, or -1 if the label */ -/* hasn't been used yet. */ -static int -dnslabel_table_get_pos(const struct dnslabel_table *table, const char *label) -{ - int i; - for (i = 0; i < table->n_labels; ++i) { - if (!strcmp(label, table->labels[i].v)) - return table->labels[i].pos; - } - return -1; -} - -/* remember that we've used the label at position pos */ -static int -dnslabel_table_add(struct dnslabel_table *table, const char *label, off_t pos) -{ - char *v; - int p; - if (table->n_labels == MAX_LABELS) - return (-1); - v = strdup(label); - if (v == NULL) - return (-1); - p = table->n_labels++; - table->labels[p].v = v; - table->labels[p].pos = pos; - - return (0); -} - -/* Converts a string to a length-prefixed set of DNS labels, starting */ -/* at buf[j]. name and buf must not overlap. name_len should be the length */ -/* of name. table is optional, and is used for compression. */ -/* */ -/* Input: abc.def */ -/* Output: <3>abc<3>def<0> */ -/* */ -/* Returns the first index after the encoded name, or negative on error. */ -/* -1 label was > 63 bytes */ -/* -2 name too long to fit in buffer. */ -/* */ -static off_t -dnsname_to_labels(u8 *const buf, size_t buf_len, off_t j, - const char *name, const int name_len, - struct dnslabel_table *table) { - const char *end = name + name_len; - int ref = 0; - u16 _t; - -#define APPEND16(x) do { \ - if (j + 2 > (off_t)buf_len) \ - goto overflow; \ - _t = htons(x); \ - memcpy(buf + j, &_t, 2); \ - j += 2; \ - } while (0) -#define APPEND32(x) do { \ - if (j + 4 > (off_t)buf_len) \ - goto overflow; \ - _t32 = htonl(x); \ - memcpy(buf + j, &_t32, 4); \ - j += 4; \ - } while (0) - - if (name_len > 255) return -2; - - for (;;) { - const char *const start = name; - if (table && (ref = dnslabel_table_get_pos(table, name)) >= 0) { - APPEND16(ref | 0xc000); - return j; - } - name = strchr(name, '.'); - if (!name) { - const unsigned int label_len = end - start; - if (label_len > 63) return -1; - if ((size_t)(j+label_len+1) > buf_len) return -2; - if (table) dnslabel_table_add(table, start, j); - buf[j++] = label_len; - - memcpy(buf + j, start, end - start); - j += end - start; - break; - } else { - /* append length of the label. */ - const unsigned int label_len = name - start; - if (label_len > 63) return -1; - if ((size_t)(j+label_len+1) > buf_len) return -2; - if (table) dnslabel_table_add(table, start, j); - buf[j++] = label_len; - - memcpy(buf + j, start, name - start); - j += name - start; - /* hop over the '.' */ - name++; - } - } - - /* the labels must be terminated by a 0. */ - /* It's possible that the name ended in a . */ - /* in which case the zero is already there */ - if (!j || buf[j-1]) buf[j++] = 0; - return j; - overflow: - return (-2); -} - -/* Finds the length of a dns request for a DNS name of the given */ -/* length. The actual request may be smaller than the value returned */ -/* here */ -static int -evdns_request_len(const int name_len) { - return 96 + /* length of the DNS standard header */ - name_len + 2 + - 4; /* space for the resource type */ -} - -/* build a dns request packet into buf. buf should be at least as long */ -/* as evdns_request_len told you it should be. */ -/* */ -/* 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, - u8 *const buf, size_t buf_len) { - off_t j = 0; /* current offset into buf */ - u16 _t; /* used by the macros */ - - APPEND16(trans_id); - APPEND16(0x0100); /* standard query, recusion needed */ - APPEND16(1); /* one question */ - APPEND16(0); /* no answers */ - APPEND16(0); /* no authority */ - APPEND16(0); /* no additional */ - - j = dnsname_to_labels(buf, buf_len, j, name, name_len, NULL); - if (j < 0) { - return (int)j; - } - - APPEND16(type); - APPEND16(class); - - return (int)j; - overflow: - return (-1); -} - -/* exported function */ -struct evdns_server_port * -evdns_add_server_port(int socket, int is_tcp, evdns_request_callback_fn_type cb, void *user_data) -{ - struct evdns_server_port *port; - if (!(port = malloc(sizeof(struct evdns_server_port)))) - return NULL; - memset(port, 0, sizeof(struct evdns_server_port)); - - assert(!is_tcp); /* TCP sockets not yet implemented */ - port->socket = socket; - port->refcnt = 1; - port->choked = 0; - port->closing = 0; - port->user_callback = cb; - port->user_data = user_data; - port->pending_replies = NULL; - - event_set(&port->event, port->socket, EV_READ | EV_PERSIST, - server_port_ready_callback, port); - event_add(&port->event, NULL); /* check return. */ - return port; -} - -/* exported function */ -void -evdns_close_server_port(struct evdns_server_port *port) -{ - if (--port->refcnt == 0) - server_port_free(port); - port->closing = 1; -} - -/* exported function */ -int -evdns_server_request_add_reply(struct evdns_server_request *_req, int section, const char *name, int type, int class, int ttl, int datalen, int is_name, const char *data) -{ - struct server_request *req = TO_SERVER_REQUEST(_req); - struct server_reply_item **itemp, *item; - int *countp; - - if (req->response) /* have we already answered? */ - return (-1); - - switch (section) { - case EVDNS_ANSWER_SECTION: - itemp = &req->answer; - countp = &req->n_answer; - break; - case EVDNS_AUTHORITY_SECTION: - itemp = &req->authority; - countp = &req->n_authority; - break; - case EVDNS_ADDITIONAL_SECTION: - itemp = &req->additional; - countp = &req->n_additional; - break; - default: - return (-1); - } - while (*itemp) { - itemp = &((*itemp)->next); - } - item = malloc(sizeof(struct server_reply_item)); - if (!item) - return -1; - item->next = NULL; - if (!(item->name = strdup(name))) { - free(item); - return -1; - } - item->type = type; - item->class = class; - item->ttl = ttl; - item->is_name = is_name != 0; - item->datalen = 0; - item->data = NULL; - if (data) { - if (item->is_name) { - if (!(item->data = strdup(data))) { - free(item->name); - free(item); - return -1; - } - item->datalen = (u16)-1; - } else { - if (!(item->data = malloc(datalen))) { - free(item->name); - free(item); - return -1; - } - item->datalen = datalen; - memcpy(item->data, data, datalen); - } - } - - *itemp = item; - ++(*countp); - return 0; -} - -/* exported function */ -int -evdns_server_request_add_a_reply(struct evdns_server_request *req, const char *name, int n, void *addrs, int ttl) -{ - return evdns_server_request_add_reply( - req, EVDNS_ANSWER_SECTION, name, TYPE_A, CLASS_INET, - ttl, n*4, 0, addrs); -} - -/* exported function */ -int -evdns_server_request_add_aaaa_reply(struct evdns_server_request *req, const char *name, int n, void *addrs, int ttl) -{ - return evdns_server_request_add_reply( - req, EVDNS_ANSWER_SECTION, name, TYPE_AAAA, CLASS_INET, - ttl, n*16, 0, addrs); -} - -/* exported function */ -int -evdns_server_request_add_ptr_reply(struct evdns_server_request *req, struct in_addr *in, const char *inaddr_name, const char *hostname, int ttl) -{ - u32 a; - char buf[32]; - assert(in || inaddr_name); - assert(!(in && inaddr_name)); - if (in) { - a = ntohl(in->s_addr); - snprintf(buf, sizeof(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)); - inaddr_name = buf; - } - return evdns_server_request_add_reply( - req, EVDNS_ANSWER_SECTION, inaddr_name, TYPE_PTR, CLASS_INET, - ttl, -1, 1, hostname); -} - -/* exported function */ -int -evdns_server_request_add_cname_reply(struct evdns_server_request *req, const char *name, const char *cname, int ttl) -{ - return evdns_server_request_add_reply( - req, EVDNS_ANSWER_SECTION, name, TYPE_A, CLASS_INET, - ttl, -1, 1, cname); -} - - -static int -evdns_server_request_format_response(struct server_request *req, int err) -{ - unsigned char buf[1500]; - size_t buf_len = sizeof(buf); - off_t j = 0, r; - u16 _t; - u32 _t32; - int i; - u16 flags; - struct dnslabel_table table; - - if (err < 0 || err > 15) return -1; - - /* Set response bit and error code; copy OPCODE and RD fields from - * question; copy RA and AA if set by caller. */ - flags = req->base.flags; - flags |= (0x8000 | err); - - dnslabel_table_init(&table); - APPEND16(req->trans_id); - APPEND16(flags); - APPEND16(req->base.nquestions); - APPEND16(req->n_answer); - APPEND16(req->n_authority); - APPEND16(req->n_additional); - - /* Add questions. */ - for (i=0; i < req->base.nquestions; ++i) { - const char *s = req->base.questions[i]->name; - j = dnsname_to_labels(buf, buf_len, j, s, strlen(s), &table); - if (j < 0) { - dnslabel_clear(&table); - return (int) j; - } - APPEND16(req->base.questions[i]->type); - APPEND16(req->base.questions[i]->class); - } - - /* Add answer, authority, and additional sections. */ - for (i=0; i<3; ++i) { - struct server_reply_item *item; - if (i==0) - item = req->answer; - else if (i==1) - item = req->authority; - else - item = req->additional; - while (item) { - r = dnsname_to_labels(buf, buf_len, j, item->name, strlen(item->name), &table); - if (r < 0) - goto overflow; - j = r; - - APPEND16(item->type); - APPEND16(item->class); - APPEND32(item->ttl); - if (item->is_name) { - off_t len_idx = j, name_start; - j += 2; - name_start = j; - r = dnsname_to_labels(buf, buf_len, j, item->data, strlen(item->data), &table); - if (r < 0) - goto overflow; - j = r; - _t = htons( (j-name_start) ); - memcpy(buf+len_idx, &_t, 2); - } else { - APPEND16(item->datalen); - if (j+item->datalen > (off_t)buf_len) - goto overflow; - memcpy(buf+j, item->data, item->datalen); - j += item->datalen; - } - item = item->next; - } - } - - if (j > 512) { -overflow: - j = 512; - buf[3] |= 0x02; /* set the truncated bit. */ - } - - req->response_len = j; - - if (!(req->response = malloc(req->response_len))) { - server_request_free_answers(req); - dnslabel_clear(&table); - return (-1); - } - memcpy(req->response, buf, req->response_len); - server_request_free_answers(req); - dnslabel_clear(&table); - return (0); -} - -/* exported function */ -int -evdns_server_request_respond(struct evdns_server_request *_req, int err) -{ - struct server_request *req = TO_SERVER_REQUEST(_req); - struct evdns_server_port *port = req->port; - int r; - if (!req->response) { - if ((r = evdns_server_request_format_response(req, err))<0) - return r; - } - - r = sendto(port->socket, req->response, req->response_len, 0, - (struct sockaddr*) &req->addr, req->addrlen); - if (r<0) { - int err = last_error(port->socket); - if (! error_is_eagain(err)) - return -1; - - if (port->pending_replies) { - req->prev_pending = port->pending_replies->prev_pending; - req->next_pending = port->pending_replies; - req->prev_pending->next_pending = - req->next_pending->prev_pending = req; - } else { - req->prev_pending = req->next_pending = req; - port->pending_replies = req; - port->choked = 1; - - (void) event_del(&port->event); - event_set(&port->event, port->socket, (port->closing?0:EV_READ) | EV_WRITE | EV_PERSIST, server_port_ready_callback, port); - - if (event_add(&port->event, NULL) < 0) { - log(EVDNS_LOG_WARN, "Error from libevent when adding event for DNS server"); - } - - } - - return 1; - } - if (server_request_free(req)) - return 0; - - if (port->pending_replies) - server_port_flush(port); - - return 0; -} - -/* Free all storage held by RRs in req. */ -static void -server_request_free_answers(struct server_request *req) -{ - struct server_reply_item *victim, *next, **list; - int i; - for (i = 0; i < 3; ++i) { - if (i==0) - list = &req->answer; - else if (i==1) - list = &req->authority; - else - list = &req->additional; - - victim = *list; - while (victim) { - next = victim->next; - free(victim->name); - if (victim->data) - free(victim->data); - free(victim); - victim = next; - } - *list = NULL; - } -} - -/* Free all storage held by req, and remove links to it. */ -/* return true iff we just wound up freeing the server_port. */ -static int -server_request_free(struct server_request *req) -{ - int i, rc=1; - if (req->base.questions) { - for (i = 0; i < req->base.nquestions; ++i) - free(req->base.questions[i]); - free(req->base.questions); - } - - if (req->port) { - if (req->port->pending_replies == req) { - if (req->next_pending) - req->port->pending_replies = req->next_pending; - else - req->port->pending_replies = NULL; - } - rc = --req->port->refcnt; - } - - if (req->response) { - free(req->response); - } - - server_request_free_answers(req); - - if (req->next_pending && req->next_pending != req) { - req->next_pending->prev_pending = req->prev_pending; - req->prev_pending->next_pending = req->next_pending; - } - - if (rc == 0) { - server_port_free(req->port); - free(req); - return (1); - } - free(req); - return (0); -} - -/* Free all storage held by an evdns_server_port. Only called when */ -static void -server_port_free(struct evdns_server_port *port) -{ - assert(port); - assert(!port->refcnt); - assert(!port->pending_replies); - if (port->socket > 0) { - CLOSE_SOCKET(port->socket); - port->socket = -1; - } - (void) event_del(&port->event); - /* XXXX actually free the port? -NM */ -} - -/* exported function */ -int -evdns_server_request_drop(struct evdns_server_request *_req) -{ - struct server_request *req = TO_SERVER_REQUEST(_req); - server_request_free(req); - return 0; -} - -/* exported function */ -int -evdns_server_request_get_requesting_addr(struct evdns_server_request *_req, struct sockaddr *sa, int addr_len) -{ - struct server_request *req = TO_SERVER_REQUEST(_req); - if (addr_len < (int)req->addrlen) - return -1; - memcpy(sa, &(req->addr), req->addrlen); - return req->addrlen; -} - -#undef APPEND16 -#undef APPEND32 - -/* this is a libevent callback function which is called when a request */ -/* has timed out. */ -static void -evdns_request_timeout_callback(int fd, short events, void *arg) { - struct request *const req = (struct request *) arg; - (void) fd; - (void) events; - - log(EVDNS_LOG_DEBUG, "Request %lx timed out", (unsigned long) arg); - - req->ns->timedout++; - if (req->ns->timedout > global_max_nameserver_timeout) { - req->ns->timedout = 0; - nameserver_failed(req->ns, "request timed out."); - } - - (void) evtimer_del(&req->timeout_event); - if (req->tx_count >= global_max_retransmits) { - /* this request has failed */ - reply_callback(req, 0, DNS_ERR_TIMEOUT, NULL); - request_finished(req, &req_head); - } else { - /* retransmit it */ - evdns_request_transmit(req); - } -} - -/* try to send a request to a given server. */ -/* */ -/* return: */ -/* 0 ok */ -/* 1 temporary failure */ -/* 2 other failure */ -static int -evdns_request_transmit_to(struct request *req, struct nameserver *server) { - const int r = send(server->socket, req->request, req->request_len, 0); - if (r < 0) { - int err = last_error(server->socket); - if (error_is_eagain(err)) return 1; - nameserver_failed(req->ns, strerror(err)); - return 2; - } else if (r != (int)req->request_len) { - return 1; /* short write */ - } else { - return 0; - } -} - -/* try to send a request, updating the fields of the request */ -/* as needed */ -/* */ -/* return: */ -/* 0 ok */ -/* 1 failed */ -static int -evdns_request_transmit(struct request *req) { - int retcode = 0, r; - - /* if we fail to send this packet then this flag marks it */ - /* for evdns_transmit */ - req->transmit_me = 1; - if (req->trans_id == 0xffff) abort(); - - if (req->ns->choked) { - /* don't bother trying to write to a socket */ - /* which we have had EAGAIN from */ - return 1; - } - - r = evdns_request_transmit_to(req, req->ns); - switch (r) { - case 1: - /* temp failure */ - req->ns->choked = 1; - nameserver_write_waiting(req->ns, 1); - return 1; - case 2: - /* failed in some other way */ - retcode = 1; - /* fall through */ - default: - /* all ok */ - 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(EVDNS_LOG_WARN, - "Error from libevent when adding timer for request %lx", - (unsigned long) req); - /* ???? Do more? */ - } - req->tx_count++; - req->transmit_me = 0; - return retcode; - } -} - -static void -nameserver_probe_callback(int result, char type, int count, int ttl, void *addresses, void *arg) { - struct nameserver *const ns = (struct nameserver *) arg; - (void) type; - (void) count; - (void) ttl; - (void) addresses; - - if (result == DNS_ERR_NONE || result == DNS_ERR_NOTEXIST) { - /* this is a good reply */ - nameserver_up(ns); - } else nameserver_probe_failed(ns); -} - -static void -nameserver_send_probe(struct nameserver *const ns) { - struct request *req; - /* here we need to send a probe to a given nameserver */ - /* in the hope that it is up now. */ - - log(EVDNS_LOG_DEBUG, "Sending probe to %s", debug_ntoa(ns->address)); - - 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()); - req->ns = ns; - request_submit(req); -} - -/* returns: */ -/* 0 didn't try to transmit anything */ -/* 1 tried to transmit something */ -static int -evdns_transmit(void) { - char did_try_to_transmit = 0; - - if (req_head) { - struct request *const started_at = req_head, *req = req_head; - /* first transmit all the requests which are currently waiting */ - do { - if (req->transmit_me) { - did_try_to_transmit = 1; - evdns_request_transmit(req); - } - - req = req->next; - } while (req != started_at); - } - - return did_try_to_transmit; -} - -/* exported function */ -int -evdns_count_nameservers(void) -{ - const struct nameserver *server = server_head; - int n = 0; - if (!server) - return 0; - do { - ++n; - server = server->next; - } while (server != server_head); - return n; -} - -/* exported function */ -int -evdns_clear_nameservers_and_suspend(void) -{ - struct nameserver *server = server_head, *started_at = server_head; - struct request *req = req_head, *req_started_at = req_head; - - if (!server) - return 0; - while (1) { - struct nameserver *next = server->next; - (void) event_del(&server->event); - (void) evtimer_del(&server->timeout_event); - if (server->socket >= 0) - CLOSE_SOCKET(server->socket); - free(server); - if (next == started_at) - break; - server = next; - } - server_head = NULL; - global_good_nameservers = 0; - - while (req) { - struct request *next = req->next; - req->tx_count = req->reissue_count = 0; - req->ns = NULL; - /* ???? What to do about searches? */ - (void) evtimer_del(&req->timeout_event); - req->trans_id = 0; - req->transmit_me = 0; - - global_requests_waiting++; - evdns_request_insert(req, &req_waiting_head); - /* We want to insert these suspended elements at the front of - * the waiting queue, since they were pending before any of - * the waiting entries were added. This is a circular list, - * so we can just shift the start back by one.*/ - req_waiting_head = req_waiting_head->prev; - - if (next == req_started_at) - break; - req = next; - } - req_head = NULL; - global_requests_inflight = 0; - - return 0; -} - - -/* exported function */ -int -evdns_resume(void) -{ - evdns_requests_pump_waiting_queue(); - return 0; -} - -static int -_evdns_nameserver_add_impl(unsigned long int address, int port) { - /* first check to see if we already have this nameserver */ - - const struct nameserver *server = server_head, *const started_at = server_head; - struct nameserver *ns; - struct sockaddr_in sin; - int err = 0; - if (server) { - do { - if (server->address == address) return 3; - server = server->next; - } while (server != started_at); - } - - ns = (struct nameserver *) malloc(sizeof(struct nameserver)); - if (!ns) return -1; - - memset(ns, 0, sizeof(struct nameserver)); - - ns->socket = socket(PF_INET, SOCK_DGRAM, 0); - if (ns->socket < 0) { err = 1; goto out1; } -#ifdef WIN32 - { - u_long nonblocking = 1; - ioctlsocket(ns->socket, FIONBIO, &nonblocking); - } -#else - fcntl(ns->socket, F_SETFL, O_NONBLOCK); -#endif - sin.sin_addr.s_addr = address; - sin.sin_port = htons(port); - sin.sin_family = AF_INET; - if (connect(ns->socket, (struct sockaddr *) &sin, sizeof(sin)) != 0) { - err = 2; - goto out2; - } - - ns->address = address; - ns->state = 1; - event_set(&ns->event, ns->socket, EV_READ | EV_PERSIST, nameserver_ready_callback, ns); - if (event_add(&ns->event, NULL) < 0) { - err = 2; - goto out2; - } - - log(EVDNS_LOG_DEBUG, "Added nameserver %s", debug_ntoa(address)); - - /* insert this nameserver into the list of them */ - if (!server_head) { - ns->next = ns->prev = ns; - server_head = ns; - } else { - ns->next = server_head->next; - ns->prev = server_head; - server_head->next = ns; - if (server_head->prev == server_head) { - server_head->prev = ns; - } - } - - global_good_nameservers++; - - return 0; - -out2: - CLOSE_SOCKET(ns->socket); -out1: - free(ns); - log(EVDNS_LOG_WARN, "Unable to add nameserver %s: error %d", debug_ntoa(address), err); - return err; -} - -/* exported function */ -int -evdns_nameserver_add(unsigned long int address) { - return _evdns_nameserver_add_impl(address, 53); -} - -/* exported function */ -int -evdns_nameserver_ip_add(const char *ip_as_string) { - struct in_addr ina; - int port; - char buf[20]; - const char *cp; - cp = strchr(ip_as_string, ':'); - if (! cp) { - cp = ip_as_string; - port = 53; - } else { - port = strtoint(cp+1); - if (port < 0 || port > 65535) { - return 4; - } - if ((cp-ip_as_string) >= (int)sizeof(buf)) { - return 4; - } - memcpy(buf, ip_as_string, cp-ip_as_string); - buf[cp-ip_as_string] = '\0'; - cp = buf; - } - if (!inet_aton(cp, &ina)) { - return 4; - } - return _evdns_nameserver_add_impl(ina.s_addr, port); -} - -/* insert into the tail of the queue */ -static void -evdns_request_insert(struct request *req, struct request **head) { - if (!*head) { - *head = req; - req->next = req->prev = req; - return; - } - - req->prev = (*head)->prev; - req->prev->next = req; - req->next = *head; - (*head)->prev = req; -} - -static int -string_num_dots(const char *s) { - int count = 0; - while ((s = strchr(s, '.'))) { - s++; - count++; - } - return count; -} - -static struct request * -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; - - const int name_len = strlen(name); - const int request_max_len = evdns_request_len(name_len); - const u16 trans_id = issuing_now ? transaction_id_pick() : 0xffff; - /* the request data is alloced in a single block with the header */ - struct request *const req = - (struct request *) malloc(sizeof(struct request) + request_max_len); - int rlen; - (void) flags; - - if (!req) return NULL; - memset(req, 0, sizeof(struct request)); - - /* request data lives just after the header */ - req->request = ((u8 *) req) + sizeof(struct request); - /* 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, 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->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); - return NULL; -} - -static void -request_submit(struct request *const req) { - if (req->ns) { - /* if it has a nameserver assigned then this is going */ - /* straight into the inflight queue */ - evdns_request_insert(req, &req_head); - global_requests_inflight++; - evdns_request_transmit(req); - } else { - evdns_request_insert(req, &req_waiting_head); - global_requests_waiting++; - } -} - -/* exported function */ -int evdns_resolve_ipv4(const char *name, int flags, - evdns_callback_type callback, void *ptr) { - log(EVDNS_LOG_DEBUG, "Resolve requested for %s", name); - if (flags & DNS_QUERY_NO_SEARCH) { - struct request *const req = - request_new(TYPE_A, name, flags, callback, ptr); - if (req == NULL) - return (1); - request_submit(req); - return (0); - } else { - return (search_request_new(TYPE_A, name, flags, callback, ptr)); - } -} - -/* exported function */ -int evdns_resolve_ipv6(const char *name, int flags, - evdns_callback_type callback, void *ptr) { - log(EVDNS_LOG_DEBUG, "Resolve requested for %s", name); - if (flags & DNS_QUERY_NO_SEARCH) { - struct request *const req = - request_new(TYPE_AAAA, name, flags, callback, ptr); - if (req == NULL) - return (1); - request_submit(req); - return (0); - } else { - return (search_request_new(TYPE_AAAA, 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); - snprintf(buf, sizeof(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; -} - -int evdns_resolve_reverse_ipv6(struct in6_addr *in, int flags, evdns_callback_type callback, void *ptr) { - char buf[96]; - char *cp; - struct request *req; - int i; - assert(in); - cp = buf; - for (i=15; i >= 0; --i) { - u8 byte = in->s6_addr[i]; - *cp++ = "0123456789abcdef"[byte & 0x0f]; - *cp++ = '.'; - *cp++ = "0123456789abcdef"[byte >> 4]; - *cp++ = '.'; - } - assert(cp + strlen(".ip6.arpa") < buf+sizeof(buf)); - memcpy(cp, ".ip6.arpa", strlen(".ip6.arpa")+1); - 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 */ -/* */ -/* the libc resolver has support for searching a number of domains */ -/* to find a name. If nothing else then it takes the single domain */ -/* from the gethostname() call. */ -/* */ -/* It can also be configured via the domain and search options in a */ -/* resolv.conf. */ -/* */ -/* The ndots option controls how many dots it takes for the resolver */ -/* to decide that a name is non-local and so try a raw lookup first. */ - -struct search_domain { - int len; - struct search_domain *next; - /* the text string is appended to this structure */ -}; - -struct search_state { - int refcount; - int ndots; - int num_domains; - struct search_domain *head; -}; - -static struct search_state *global_search_state = NULL; - -static void -search_state_decref(struct search_state *const state) { - if (!state) return; - state->refcount--; - if (!state->refcount) { - struct search_domain *next, *dom; - for (dom = state->head; dom; dom = next) { - next = dom->next; - free(dom); - } - free(state); - } -} - -static struct search_state * -search_state_new(void) { - struct search_state *state = (struct search_state *) malloc(sizeof(struct search_state)); - if (!state) return NULL; - memset(state, 0, sizeof(struct search_state)); - state->refcount = 1; - state->ndots = 1; - - return state; -} - -static void -search_postfix_clear(void) { - search_state_decref(global_search_state); - - global_search_state = search_state_new(); -} - -/* exported function */ -void -evdns_search_clear(void) { - search_postfix_clear(); -} - -static void -search_postfix_add(const char *domain) { - int domain_len; - struct search_domain *sdomain; - while (domain[0] == '.') domain++; - domain_len = strlen(domain); - - if (!global_search_state) global_search_state = search_state_new(); - if (!global_search_state) return; - global_search_state->num_domains++; - - sdomain = (struct search_domain *) malloc(sizeof(struct search_domain) + domain_len); - if (!sdomain) return; - memcpy( ((u8 *) sdomain) + sizeof(struct search_domain), domain, domain_len); - sdomain->next = global_search_state->head; - sdomain->len = domain_len; - - global_search_state->head = sdomain; -} - -/* reverse the order of members in the postfix list. This is needed because, */ -/* when parsing resolv.conf we push elements in the wrong order */ -static void -search_reverse(void) { - struct search_domain *cur, *prev = NULL, *next; - cur = global_search_state->head; - while (cur) { - next = cur->next; - cur->next = prev; - prev = cur; - cur = next; - } - - global_search_state->head = prev; -} - -/* exported function */ -void -evdns_search_add(const char *domain) { - search_postfix_add(domain); -} - -/* exported function */ -void -evdns_search_ndots_set(const int ndots) { - if (!global_search_state) global_search_state = search_state_new(); - if (!global_search_state) return; - global_search_state->ndots = ndots; -} - -static void -search_set_from_hostname(void) { - char hostname[HOST_NAME_MAX + 1], *domainname; - - search_postfix_clear(); - if (gethostname(hostname, sizeof(hostname))) return; - domainname = strchr(hostname, '.'); - if (!domainname) return; - search_postfix_add(domainname); -} - -/* warning: returns malloced string */ -static char * -search_make_new(const struct search_state *const state, int n, const char *const base_name) { - const int base_len = strlen(base_name); - const char need_to_append_dot = base_name[base_len - 1] == '.' ? 0 : 1; - struct search_domain *dom; - - for (dom = state->head; dom; dom = dom->next) { - if (!n--) { - /* this is the postfix we want */ - /* the actual postfix string is kept at the end of the structure */ - const u8 *const postfix = ((u8 *) dom) + sizeof(struct search_domain); - const int postfix_len = dom->len; - char *const newname = (char *) malloc(base_len + need_to_append_dot + postfix_len + 1); - if (!newname) return NULL; - memcpy(newname, base_name, base_len); - if (need_to_append_dot) newname[base_len] = '.'; - memcpy(newname + base_len + need_to_append_dot, postfix, postfix_len); - newname[base_len + need_to_append_dot + postfix_len] = 0; - return newname; - } - } - - /* we ran off the end of the list and still didn't find the requested string */ - abort(); - return NULL; /* unreachable; stops warnings in some compilers. */ -} - -static int -search_request_new(int type, const char *const name, int flags, evdns_callback_type user_callback, void *user_arg) { - assert(type == TYPE_A || type == TYPE_AAAA); - 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(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(type, new_name, flags, user_callback, user_arg); - free(new_name); - if (!req) return 1; - req->search_index = 0; - } - req->search_origname = strdup(name); - req->search_state = global_search_state; - req->search_flags = flags; - global_search_state->refcount++; - request_submit(req); - return 0; - } else { - struct request *const req = request_new(type, name, flags, user_callback, user_arg); - if (!req) return 1; - request_submit(req); - return 0; - } -} - -/* this is called when a request has failed to find a name. We need to check */ -/* if it is part of a search and, if so, try the next name in the list */ -/* returns: */ -/* 0 another request has been submitted */ -/* 1 no more requests needed */ -static int -search_try_next(struct request *const req) { - if (req->search_state) { - /* it is part of a search */ - char *new_name; - struct request *newreq; - req->search_index++; - if (req->search_index >= req->search_state->num_domains) { - /* no more postfixes to try, however we may need to try */ - /* 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->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; - } - } - return 1; - } - - new_name = search_make_new(req->search_state, req->search_index, req->search_origname); - if (!new_name) return 1; - 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; - req->search_origname = NULL; - newreq->search_state = req->search_state; - newreq->search_flags = req->search_flags; - newreq->search_index = req->search_index; - newreq->search_state->refcount++; - request_submit(newreq); - return 0; - } - return 1; -} - -static void -search_request_finished(struct request *const req) { - if (req->search_state) { - search_state_decref(req->search_state); - req->search_state = NULL; - } - if (req->search_origname) { - free(req->search_origname); - req->search_origname = NULL; - } -} - -/*/////////////////////////////////////////////////////////////////// */ -/* Parsing resolv.conf files */ - -static void -evdns_resolv_set_defaults(int flags) { - /* if the file isn't found then we assume a local resolver */ - if (flags & DNS_OPTION_SEARCH) search_set_from_hostname(); - if (flags & DNS_OPTION_NAMESERVERS) evdns_nameserver_ip_add("127.0.0.1"); -} - -#ifndef HAVE_STRTOK_R -static char * -strtok_r(char *s, const char *delim, char **state) { - return strtok(s, delim); -} -#endif - -/* helper version of atoi which returns -1 on error */ -static int -strtoint(const char *const str) { - char *endptr; - const int r = strtol(str, &endptr, 10); - if (*endptr) return -1; - return r; -} - -/* helper version of atoi that returns -1 on error and clips to bounds. */ -static int -strtoint_clipped(const char *const str, int min, int max) -{ - int r = strtoint(str); - if (r == -1) - return r; - else if (r<min) - return min; - else if (r>max) - return max; - else - return r; -} - -/* exported function */ -int -evdns_set_option(const char *option, const char *val, int flags) -{ - if (!strncmp(option, "ndots:", 6)) { - const int ndots = strtoint(val); - if (ndots == -1) return -1; - if (!(flags & DNS_OPTION_SEARCH)) return 0; - log(EVDNS_LOG_DEBUG, "Setting ndots to %d", ndots); - if (!global_search_state) global_search_state = search_state_new(); - if (!global_search_state) return -1; - global_search_state->ndots = ndots; - } else if (!strncmp(option, "timeout:", 8)) { - const int timeout = strtoint(val); - if (timeout == -1) return -1; - if (!(flags & DNS_OPTION_MISC)) return 0; - log(EVDNS_LOG_DEBUG, "Setting timeout to %d", timeout); - global_timeout.tv_sec = timeout; - } else if (!strncmp(option, "max-timeouts:", 12)) { - const int maxtimeout = strtoint_clipped(val, 1, 255); - if (maxtimeout == -1) return -1; - if (!(flags & DNS_OPTION_MISC)) return 0; - log(EVDNS_LOG_DEBUG, "Setting maximum allowed timeouts to %d", - maxtimeout); - global_max_nameserver_timeout = maxtimeout; - } else if (!strncmp(option, "max-inflight:", 13)) { - const int maxinflight = strtoint_clipped(val, 1, 65000); - if (maxinflight == -1) return -1; - if (!(flags & DNS_OPTION_MISC)) return 0; - log(EVDNS_LOG_DEBUG, "Setting maximum inflight requests to %d", - maxinflight); - global_max_requests_inflight = maxinflight; - } else if (!strncmp(option, "attempts:", 9)) { - int retries = strtoint(val); - if (retries == -1) return -1; - if (retries > 255) retries = 255; - if (!(flags & DNS_OPTION_MISC)) return 0; - log(EVDNS_LOG_DEBUG, "Setting retries to %d", retries); - global_max_retransmits = retries; - } - return 0; -} - -static void -resolv_conf_parse_line(char *const start, int flags) { - char *strtok_state; - static const char *const delims = " \t"; -#define NEXT_TOKEN strtok_r(NULL, delims, &strtok_state) - - char *const first_token = strtok_r(start, delims, &strtok_state); - if (!first_token) return; - - if (!strcmp(first_token, "nameserver") && (flags & DNS_OPTION_NAMESERVERS)) { - const char *const nameserver = NEXT_TOKEN; - struct in_addr ina; - - if (inet_aton(nameserver, &ina)) { - /* address is valid */ - evdns_nameserver_add(ina.s_addr); - } - } else if (!strcmp(first_token, "domain") && (flags & DNS_OPTION_SEARCH)) { - const char *const domain = NEXT_TOKEN; - if (domain) { - search_postfix_clear(); - search_postfix_add(domain); - } - } else if (!strcmp(first_token, "search") && (flags & DNS_OPTION_SEARCH)) { - const char *domain; - search_postfix_clear(); - - while ((domain = NEXT_TOKEN)) { - search_postfix_add(domain); - } - search_reverse(); - } else if (!strcmp(first_token, "options")) { - const char *option; - while ((option = NEXT_TOKEN)) { - const char *val = strchr(option, ':'); - evdns_set_option(option, val ? val+1 : "", flags); - } - } -#undef NEXT_TOKEN -} - -/* exported function */ -/* returns: */ -/* 0 no errors */ -/* 1 failed to open file */ -/* 2 failed to stat file */ -/* 3 file too large */ -/* 4 out of memory */ -/* 5 short read from file */ -int -evdns_resolv_conf_parse(int flags, const char *const filename) { - struct stat st; - int fd, n, r; - u8 *resolv; - char *start; - int err = 0; - - log(EVDNS_LOG_DEBUG, "Parsing resolv.conf file %s", filename); - - fd = open(filename, O_RDONLY); - if (fd < 0) { - evdns_resolv_set_defaults(flags); - return 1; - } - - if (fstat(fd, &st)) { err = 2; goto out1; } - if (!st.st_size) { - evdns_resolv_set_defaults(flags); - err = (flags & DNS_OPTION_NAMESERVERS) ? 6 : 0; - goto out1; - } - if (st.st_size > 65535) { err = 3; goto out1; } /* no resolv.conf should be any bigger */ - - resolv = (u8 *) malloc((size_t)st.st_size + 1); - if (!resolv) { err = 4; goto out1; } - - n = 0; - while ((r = read(fd, resolv+n, (size_t)st.st_size-n)) > 0) { - n += r; - if (n == st.st_size) - break; - assert(n < st.st_size); - } - if (r < 0) { err = 5; goto out2; } - resolv[n] = 0; /* we malloced an extra byte; this should be fine. */ - - start = (char *) resolv; - for (;;) { - char *const newline = strchr(start, '\n'); - if (!newline) { - resolv_conf_parse_line(start, flags); - break; - } else { - *newline = 0; - resolv_conf_parse_line(start, flags); - start = newline + 1; - } - } - - if (!server_head && (flags & DNS_OPTION_NAMESERVERS)) { - /* no nameservers were configured. */ - evdns_nameserver_ip_add("127.0.0.1"); - err = 6; - } - if (flags & DNS_OPTION_SEARCH && (!global_search_state || global_search_state->num_domains == 0)) { - search_set_from_hostname(); - } - -out2: - free(resolv); -out1: - close(fd); - return err; -} - -#ifdef WIN32 -/* Add multiple nameservers from a space-or-comma-separated list. */ -static int -evdns_nameserver_ip_add_line(const char *ips) { - const char *addr; - char *buf; - int r; - while (*ips) { - while (ISSPACE(*ips) || *ips == ',' || *ips == '\t') - ++ips; - addr = ips; - while (ISDIGIT(*ips) || *ips == '.' || *ips == ':') - ++ips; - buf = malloc(ips-addr+1); - if (!buf) return 4; - memcpy(buf, addr, ips-addr); - buf[ips-addr] = '\0'; - r = evdns_nameserver_ip_add(buf); - free(buf); - if (r) return r; - } - 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 -load_nameservers_with_getnetworkparams(void) -{ - /* Based on MSDN examples and inspection of c-ares code. */ - FIXED_INFO *fixed; - HMODULE handle = 0; - ULONG size = sizeof(FIXED_INFO); - void *buf = NULL; - int status = 0, r, added_any; - IP_ADDR_STRING *ns; - GetNetworkParams_fn_t fn; - - if (!(handle = LoadLibrary("iphlpapi.dll"))) { - log(EVDNS_LOG_WARN, "Could not open iphlpapi.dll"); - status = -1; - goto done; - } - 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; } - fixed = buf; - r = fn(fixed, &size); - if (r != ERROR_SUCCESS && r != ERROR_BUFFER_OVERFLOW) { - status = -1; - goto done; - } - if (r != ERROR_SUCCESS) { - free(buf); - buf = malloc(size); - if (!buf) { status = 4; goto done; } - fixed = buf; - r = fn(fixed, &size); - if (r != ERROR_SUCCESS) { - log(EVDNS_LOG_DEBUG, "fn() failed."); - status = -1; - goto done; - } - } - - assert(fixed); - added_any = 0; - ns = &(fixed->DnsServerList); - while (ns) { - r = evdns_nameserver_ip_add_line(ns->IpAddress.String); - 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) { - log(EVDNS_LOG_DEBUG, "No nameservers added."); - status = -1; - } - - done: - if (buf) - free(buf); - if (handle) - FreeLibrary(handle); - return status; -} - -static int -config_nameserver_from_reg_key(HKEY key, const char *subkey) -{ - char *buf; - DWORD bufsz = 0, type = 0; - int status = 0; - - if (RegQueryValueEx(key, subkey, 0, &type, NULL, &bufsz) - != ERROR_MORE_DATA) - return -1; - if (!(buf = malloc(bufsz))) - return -1; - - if (RegQueryValueEx(key, subkey, 0, &type, (LPBYTE)buf, &bufsz) - == ERROR_SUCCESS && bufsz > 1) { - status = evdns_nameserver_ip_add_line(buf); - } - - free(buf); - 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(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 (((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) { - log(EVDNS_LOG_DEBUG,"Couldn't open nt key, %d",(int)GetLastError()); - return -1; - } - r = RegOpenKeyEx(nt_key, "Interfaces", 0, - KEY_QUERY_VALUE|KEY_ENUMERATE_SUB_KEYS, - &interfaces_key); - 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_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"); - RegCloseKey(win_key); - } - - if (found == 0) { - log(EVDNS_LOG_WARN,"Didn't find any nameservers."); - } - - return found ? 0 : -1; -#undef TRY -} - -int -evdns_config_windows_nameservers(void) -{ - if (load_nameservers_with_getnetworkparams() == 0) - return 0; - return load_nameservers_from_registry(); -} -#endif - -int -evdns_init(void) -{ - int res = 0; -#ifdef WIN32 - evdns_config_windows_nameservers(); -#else - res = evdns_resolv_conf_parse(DNS_OPTIONS_ALL, "/etc/resolv.conf"); -#endif - - 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); - if (server->state == 0) - (void) event_del(&server->timeout_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 -evdns_server_callback(struct evdns_server_request *req, void *data) -{ - int i, r; - (void)data; - /* dummy; give 192.168.11.11 as an answer for all A questions, - * give foo.bar.example.com as an answer for all PTR questions. */ - for (i = 0; i < req->nquestions; ++i) { - u32 ans = htonl(0xc0a80b0bUL); - if (req->questions[i]->type == EVDNS_TYPE_A && - req->questions[i]->class == EVDNS_CLASS_INET) { - printf(" -- replying for %s (A)\n", req->questions[i]->name); - r = evdns_server_request_add_a_reply(req, req->questions[i]->name, - 1, &ans, 10); - if (r<0) - printf("eeep, didn't work.\n"); - } else if (req->questions[i]->type == EVDNS_TYPE_PTR && - req->questions[i]->class == EVDNS_CLASS_INET) { - printf(" -- replying for %s (PTR)\n", req->questions[i]->name); - r = evdns_server_request_add_ptr_reply(req, NULL, req->questions[i]->name, - "foo.bar.example.com", 10); - } else { - printf(" -- skipping %s [%d %d]\n", req->questions[i]->name, - req->questions[i]->type, req->questions[i]->class); - } - } - - r = evdns_request_respond(req, 0); - if (r<0) - printf("eeek, couldn't send reply.\n"); -} - -void -logfn(int is_warn, const char *msg) { - (void) is_warn; - fprintf(stderr, "%s\n", msg); -} -int -main(int c, char **v) { - int idx; - int reverse = 0, verbose = 1, servertest = 0; - if (c<2) { - fprintf(stderr, "syntax: %s [-x] [-v] hostname\n", v[0]); - fprintf(stderr, "syntax: %s [-servertest]\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 if (!strcmp(v[idx], "-servertest")) - servertest = 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"); - if (servertest) { - int sock; - struct sockaddr_in my_addr; - sock = socket(PF_INET, SOCK_DGRAM, 0); - fcntl(sock, F_SETFL, O_NONBLOCK); - my_addr.sin_family = AF_INET; - my_addr.sin_port = htons(10053); - my_addr.sin_addr.s_addr = INADDR_ANY; - if (bind(sock, (struct sockaddr*)&my_addr, sizeof(my_addr))<0) { - perror("bind"); - exit(1); - } - evdns_add_server_port(sock, 0, evdns_server_callback, NULL); - } - 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 |