diff options
Diffstat (limited to 'libs/libevent/src/evdns.c')
| -rw-r--r-- | libs/libevent/src/evdns.c | 4761 |
1 files changed, 0 insertions, 4761 deletions
diff --git a/libs/libevent/src/evdns.c b/libs/libevent/src/evdns.c deleted file mode 100644 index f087962336..0000000000 --- a/libs/libevent/src/evdns.c +++ /dev/null @@ -1,4761 +0,0 @@ -/* Copyright 2006-2007 Niels Provos - * Copyright 2007-2012 Nick Mathewson and Niels Provos - * - * Redistribution and use in source and binary forms, with or without - * modification, are permitted provided that the following conditions - * are met: - * 1. Redistributions of source code must retain the above copyright - * notice, this list of conditions and the following disclaimer. - * 2. Redistributions in binary form must reproduce the above copyright - * notice, this list of conditions and the following disclaimer in the - * documentation and/or other materials provided with the distribution. - * 3. The name of the author may not be used to endorse or promote products - * derived from this software without specific prior written permission. - * - * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR - * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES - * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. - * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, - * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT - * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, - * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY - * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT - * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF - * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. - */ - -/* Based on software by Adam Langly. Adam's original message: - * - * 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 "event2/event-config.h" -#include "evconfig-private.h" - -#include <sys/types.h> - -#ifndef _FORTIFY_SOURCE -#define _FORTIFY_SOURCE 3 -#endif - -#include <string.h> -#include <fcntl.h> -#ifdef EVENT__HAVE_SYS_TIME_H -#include <sys/time.h> -#endif -#ifdef EVENT__HAVE_STDINT_H -#include <stdint.h> -#endif -#include <stdlib.h> -#include <string.h> -#include <errno.h> -#ifdef EVENT__HAVE_UNISTD_H -#include <unistd.h> -#endif -#include <limits.h> -#include <sys/stat.h> -#include <stdio.h> -#include <stdarg.h> -#ifdef _WIN32 -#include <winsock2.h> -#include <ws2tcpip.h> -#ifndef _WIN32_IE -#define _WIN32_IE 0x400 -#endif -#include <shlobj.h> -#endif - -#include "event2/dns.h" -#include "event2/dns_struct.h" -#include "event2/dns_compat.h" -#include "event2/util.h" -#include "event2/event.h" -#include "event2/event_struct.h" -#include "event2/thread.h" - -#include "defer-internal.h" -#include "log-internal.h" -#include "mm-internal.h" -#include "strlcpy-internal.h" -#include "ipv6-internal.h" -#include "util-internal.h" -#include "evthread-internal.h" -#ifdef _WIN32 -#include <ctype.h> -#include <winsock2.h> -#include <windows.h> -#include <iphlpapi.h> -#include <io.h> -#else -#include <sys/socket.h> -#include <netinet/in.h> -#include <arpa/inet.h> -#endif - -#ifdef EVENT__HAVE_NETINET_IN6_H -#include <netinet/in6.h> -#endif - -#define EVDNS_LOG_DEBUG EVENT_LOG_DEBUG -#define EVDNS_LOG_WARN EVENT_LOG_WARN -#define EVDNS_LOG_MSG EVENT_LOG_MSG - -#ifndef HOST_NAME_MAX -#define HOST_NAME_MAX 255 -#endif - -#include <stdio.h> - -#undef MIN -#define MIN(a,b) ((a)<(b)?(a):(b)) - -#define ASSERT_VALID_REQUEST(req) \ - EVUTIL_ASSERT((req)->handle && (req)->handle->current_req == (req)) - -#define u64 ev_uint64_t -#define u32 ev_uint32_t -#define u16 ev_uint16_t -#define u8 ev_uint8_t - -/* maximum number of addresses from a single packet */ -/* that we bother recording */ -#define MAX_V4_ADDRS 32 -#define MAX_V6_ADDRS 32 - - -#define TYPE_A EVDNS_TYPE_A -#define TYPE_CNAME 5 -#define TYPE_PTR EVDNS_TYPE_PTR -#define TYPE_SOA EVDNS_TYPE_SOA -#define TYPE_AAAA EVDNS_TYPE_AAAA - -#define CLASS_INET EVDNS_CLASS_INET - -/* Persistent handle. We keep this separate from 'struct request' since we - * need some object to last for as long as an evdns_request is outstanding so - * that it can be canceled, whereas a search request can lead to multiple - * 'struct request' instances being created over its lifetime. */ -struct evdns_request { - struct request *current_req; - struct evdns_base *base; - - int pending_cb; /* Waiting for its callback to be invoked; not - * owned by event base any more. */ - - /* 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; -}; - -struct request { - u8 *request; /* the dns packet data */ - u8 request_type; /* TYPE_PTR or TYPE_A or TYPE_AAAA */ - unsigned int request_len; - int reissue_count; - int tx_count; /* the number of times that this packet has been sent */ - 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 */ - - /* these objects are kept in a circular list */ - /* XXX We could turn this into a CIRCLEQ. */ - struct request *next, *prev; - - struct event timeout_event; - - u16 trans_id; /* the transaction id */ - unsigned request_appended :1; /* true if the request pointer is data which follows this struct */ - unsigned transmit_me :1; /* needs to be transmitted */ - - /* XXXX This is a horrible hack. */ - char **put_cname_in_ptr; /* store the cname here if we get one. */ - - struct evdns_base *base; - - struct evdns_request *handle; -}; - -struct reply { - unsigned int type; - unsigned int have_answer : 1; - union { - struct { - u32 addrcount; - u32 addresses[MAX_V4_ADDRS]; - } a; - struct { - u32 addrcount; - struct in6_addr addresses[MAX_V6_ADDRS]; - } aaaa; - struct { - char name[HOST_NAME_MAX]; - } ptr; - } data; -}; - -struct nameserver { - evutil_socket_t socket; /* a connected UDP socket */ - struct sockaddr_storage address; - ev_socklen_t addrlen; - 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 */ - /* Outstanding probe request for this nameserver, if any */ - struct evdns_request *probe_request; - 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 */ - struct evdns_base *base; - - /* Number of currently inflight requests: used - * to track when we should add/del the event. */ - int requests_inflight; -}; - - -/* Represents a local port where we're listening for DNS requests. Right now, */ -/* only UDP is supported. */ -struct evdns_server_port { - evutil_socket_t 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; - struct event_base *event_base; - -#ifndef EVENT__DISABLE_THREAD_SUPPORT - void *lock; -#endif -}; - -/* 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; /* The RR type */ - u16 class; /* 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 */ - ev_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; -}; - -struct evdns_base { - /* An array of n_req_heads circular lists for inflight requests. - * Each inflight request req is in req_heads[req->trans_id % n_req_heads]. - */ - struct request **req_heads; - /* A circular list of requests that we're waiting to send, but haven't - * sent yet because there are too many requests inflight */ - struct request *req_waiting_head; - /* A circular list of nameservers. */ - struct nameserver *server_head; - int n_req_heads; - - struct event_base *event_base; - - /* The number of good nameservers that we have */ - int global_good_nameservers; - - /* inflight requests are contained in the req_head list */ - /* and are actually going out across the network */ - int global_requests_inflight; - /* requests which aren't inflight are in the waiting list */ - /* and are counted here */ - int global_requests_waiting; - - int global_max_requests_inflight; - - struct timeval global_timeout; /* 5 seconds by default */ - int global_max_reissues; /* a reissue occurs when we get some errors from the server */ - int global_max_retransmits; /* 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 */ - int global_max_nameserver_timeout; - /* true iff we will use the 0x20 hack to prevent poisoning attacks. */ - int global_randomize_case; - - /* The first time that a nameserver fails, how long do we wait before - * probing to see if it has returned? */ - struct timeval global_nameserver_probe_initial_timeout; - - /** Port to bind to for outgoing DNS packets. */ - struct sockaddr_storage global_outgoing_address; - /** ev_socklen_t for global_outgoing_address. 0 if it isn't set. */ - ev_socklen_t global_outgoing_addrlen; - - struct timeval global_getaddrinfo_allow_skew; - - int getaddrinfo_ipv4_timeouts; - int getaddrinfo_ipv6_timeouts; - int getaddrinfo_ipv4_answered; - int getaddrinfo_ipv6_answered; - - struct search_state *global_search_state; - - TAILQ_HEAD(hosts_list, hosts_entry) hostsdb; - -#ifndef EVENT__DISABLE_THREAD_SUPPORT - void *lock; -#endif - - int disable_when_inactive; -}; - -struct hosts_entry { - TAILQ_ENTRY(hosts_entry) next; - union { - struct sockaddr sa; - struct sockaddr_in sin; - struct sockaddr_in6 sin6; - } addr; - int addrlen; - char hostname[1]; -}; - -static struct evdns_base *current_base = NULL; - -struct evdns_base * -evdns_get_global_base(void) -{ - return current_base; -} - -/* 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) - evutil_offsetof(struct server_request, base)))) - -#define REQ_HEAD(base, id) ((base)->req_heads[id % (base)->n_req_heads]) - -static struct nameserver *nameserver_pick(struct evdns_base *base); -static void evdns_request_insert(struct request *req, struct request **head); -static void evdns_request_remove(struct request *req, struct request **head); -static void nameserver_ready_callback(evutil_socket_t fd, short events, void *arg); -static int evdns_transmit(struct evdns_base *base); -static int evdns_request_transmit(struct request *req); -static void nameserver_send_probe(struct nameserver *const ns); -static void search_request_finished(struct evdns_request *const); -static int search_try_next(struct evdns_request *const req); -static struct request *search_request_new(struct evdns_base *base, struct evdns_request *handle, int type, const char *const name, int flags, evdns_callback_type user_callback, void *user_arg); -static void evdns_requests_pump_waiting_queue(struct evdns_base *base); -static u16 transaction_id_pick(struct evdns_base *base); -static struct request *request_new(struct evdns_base *base, struct evdns_request *handle, int type, const char *name, int flags, evdns_callback_type callback, void *ptr); -static void request_submit(struct request *const 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(evutil_socket_t fd, short events, void *arg); -static int evdns_base_resolv_conf_parse_impl(struct evdns_base *base, int flags, const char *const filename); -static int evdns_base_set_option_impl(struct evdns_base *base, - const char *option, const char *val, int flags); -static void evdns_base_free_and_unlock(struct evdns_base *base, int fail_requests); -static void evdns_request_timeout_callback(evutil_socket_t fd, short events, void *arg); - -static int strtoint(const char *const str); - -#ifdef EVENT__DISABLE_THREAD_SUPPORT -#define EVDNS_LOCK(base) EVUTIL_NIL_STMT_ -#define EVDNS_UNLOCK(base) EVUTIL_NIL_STMT_ -#define ASSERT_LOCKED(base) EVUTIL_NIL_STMT_ -#else -#define EVDNS_LOCK(base) \ - EVLOCK_LOCK((base)->lock, 0) -#define EVDNS_UNLOCK(base) \ - EVLOCK_UNLOCK((base)->lock, 0) -#define ASSERT_LOCKED(base) \ - EVLOCK_ASSERT_LOCKED((base)->lock) -#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 severity, const char *fmt, ...) EVDNS_LOG_CHECK; -static void -evdns_log_(int severity, const char *fmt, ...) -{ - va_list args; - va_start(args,fmt); - if (evdns_log_fn) { - char buf[512]; - int is_warn = (severity == EVDNS_LOG_WARN); - evutil_vsnprintf(buf, sizeof(buf), fmt, args); - evdns_log_fn(is_warn, buf); - } else { - event_logv_(severity, NULL, fmt, args); - } - 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(struct evdns_base *base, u16 trans_id) { - struct request *req = REQ_HEAD(base, trans_id); - struct request *const started_at = req; - - ASSERT_LOCKED(base); - - 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(evutil_socket_t fd, short events, void *arg) { - struct nameserver *const ns = (struct nameserver *) arg; - (void)fd; - (void)events; - - EVDNS_LOCK(ns->base); - nameserver_send_probe(ns); - EVDNS_UNLOCK(ns->base); -} - -/* 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) { - struct timeval timeout; - int i; - - ASSERT_LOCKED(ns->base); - (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; - } - -#define MAX_PROBE_TIMEOUT 3600 -#define TIMEOUT_BACKOFF_FACTOR 3 - - memcpy(&timeout, &ns->base->global_nameserver_probe_initial_timeout, - sizeof(struct timeval)); - for (i=ns->failed_times; i > 0 && timeout.tv_sec < MAX_PROBE_TIMEOUT; --i) { - timeout.tv_sec *= TIMEOUT_BACKOFF_FACTOR; - timeout.tv_usec *= TIMEOUT_BACKOFF_FACTOR; - if (timeout.tv_usec > 1000000) { - timeout.tv_sec += timeout.tv_usec / 1000000; - timeout.tv_usec %= 1000000; - } - } - if (timeout.tv_sec > MAX_PROBE_TIMEOUT) { - timeout.tv_sec = MAX_PROBE_TIMEOUT; - timeout.tv_usec = 0; - } - - ns->failed_times++; - - if (evtimer_add(&ns->timeout_event, &timeout) < 0) { - char addrbuf[128]; - log(EVDNS_LOG_WARN, - "Error from libevent when adding timer event for %s", - evutil_format_sockaddr_port_( - (struct sockaddr *)&ns->address, - addrbuf, sizeof(addrbuf))); - } -} - -static void -request_swap_ns(struct request *req, struct nameserver *ns) { - if (ns && req->ns != ns) { - EVUTIL_ASSERT(req->ns->requests_inflight > 0); - req->ns->requests_inflight--; - ns->requests_inflight++; - - req->ns = ns; - } -} - -/* 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; - struct evdns_base *base = ns->base; - int i; - char addrbuf[128]; - - ASSERT_LOCKED(base); - /* if this nameserver has already been marked as failed */ - /* then don't do anything */ - if (!ns->state) return; - - log(EVDNS_LOG_MSG, "Nameserver %s has failed: %s", - evutil_format_sockaddr_port_( - (struct sockaddr *)&ns->address, - addrbuf, sizeof(addrbuf)), - msg); - - base->global_good_nameservers--; - EVUTIL_ASSERT(base->global_good_nameservers >= 0); - if (base->global_good_nameservers == 0) { - log(EVDNS_LOG_MSG, "All nameservers have failed"); - } - - ns->state = 0; - ns->failed_times = 1; - - if (evtimer_add(&ns->timeout_event, - &base->global_nameserver_probe_initial_timeout) < 0) { - log(EVDNS_LOG_WARN, - "Error from libevent when adding timer event for %s", - evutil_format_sockaddr_port_( - (struct sockaddr *)&ns->address, - addrbuf, sizeof(addrbuf))); - /* ???? 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 (!base->global_good_nameservers) return; - - for (i = 0; i < base->n_req_heads; ++i) { - req = started_at = base->req_heads[i]; - if (req) { - do { - if (req->tx_count == 0 && req->ns == ns) { - /* still waiting to go out, can be moved */ - /* to another server */ - request_swap_ns(req, nameserver_pick(base)); - } - req = req->next; - } while (req != started_at); - } - } -} - -static void -nameserver_up(struct nameserver *const ns) -{ - char addrbuf[128]; - ASSERT_LOCKED(ns->base); - if (ns->state) return; - log(EVDNS_LOG_MSG, "Nameserver %s is back up", - evutil_format_sockaddr_port_( - (struct sockaddr *)&ns->address, - addrbuf, sizeof(addrbuf))); - evtimer_del(&ns->timeout_event); - if (ns->probe_request) { - evdns_cancel_request(ns->base, ns->probe_request); - ns->probe_request = NULL; - } - ns->state = 1; - ns->failed_times = 0; - ns->timedout = 0; - ns->base->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. */ -/* when free_handle is one, free the handle as well. */ -static void -request_finished(struct request *const req, struct request **head, int free_handle) { - struct evdns_base *base = req->base; - int was_inflight = (head != &base->req_waiting_head); - EVDNS_LOCK(base); - ASSERT_VALID_REQUEST(req); - - if (head) - evdns_request_remove(req, head); - - log(EVDNS_LOG_DEBUG, "Removing timeout for request %p", req); - if (was_inflight) { - evtimer_del(&req->timeout_event); - base->global_requests_inflight--; - req->ns->requests_inflight--; - } else { - base->global_requests_waiting--; - } - /* it was initialized during request_new / evtimer_assign */ - event_debug_unassign(&req->timeout_event); - - if (req->ns && - req->ns->requests_inflight == 0 && - req->base->disable_when_inactive) { - event_del(&req->ns->event); - evtimer_del(&req->ns->timeout_event); - } - - if (!req->request_appended) { - /* need to free the request data on it's own */ - mm_free(req->request); - } else { - /* the request data is appended onto the header */ - /* so everything gets free()ed when we: */ - } - - if (req->handle) { - EVUTIL_ASSERT(req->handle->current_req == req); - - if (free_handle) { - search_request_finished(req->handle); - req->handle->current_req = NULL; - if (! req->handle->pending_cb) { - /* If we're planning to run the callback, - * don't free the handle until later. */ - mm_free(req->handle); - } - req->handle = NULL; /* If we have a bug, let's crash - * early */ - } else { - req->handle->current_req = NULL; - } - } - - mm_free(req); - - evdns_requests_pump_waiting_queue(base); - EVDNS_UNLOCK(base); -} - -/* 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; - ASSERT_LOCKED(req->base); - ASSERT_VALID_REQUEST(req); - /* the last nameserver should have been marked as failing */ - /* by the caller of this function, therefore pick will try */ - /* not to return it */ - request_swap_ns(req, nameserver_pick(req->base)); - 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. */ -/* */ -/* TODO: */ -/* add return code, see at nameserver_pick() and other functions. */ -static void -evdns_requests_pump_waiting_queue(struct evdns_base *base) { - ASSERT_LOCKED(base); - while (base->global_requests_inflight < base->global_max_requests_inflight && - base->global_requests_waiting) { - struct request *req; - - EVUTIL_ASSERT(base->req_waiting_head); - req = base->req_waiting_head; - - req->ns = nameserver_pick(base); - if (!req->ns) - return; - - /* move a request from the waiting queue to the inflight queue */ - req->ns->requests_inflight++; - - evdns_request_remove(req, &base->req_waiting_head); - - base->global_requests_waiting--; - base->global_requests_inflight++; - - request_trans_id_set(req, transaction_id_pick(base)); - - evdns_request_insert(req, &REQ_HEAD(base, req->trans_id)); - evdns_request_transmit(req); - evdns_transmit(base); - } -} - -/* TODO(nickm) document */ -struct deferred_reply_callback { - struct event_callback deferred; - struct evdns_request *handle; - u8 request_type; - u8 have_reply; - u32 ttl; - u32 err; - evdns_callback_type user_callback; - struct reply reply; -}; - -static void -reply_run_callback(struct event_callback *d, void *user_pointer) -{ - struct deferred_reply_callback *cb = - EVUTIL_UPCAST(d, struct deferred_reply_callback, deferred); - - switch (cb->request_type) { - case TYPE_A: - if (cb->have_reply) - cb->user_callback(DNS_ERR_NONE, DNS_IPv4_A, - cb->reply.data.a.addrcount, cb->ttl, - cb->reply.data.a.addresses, - user_pointer); - else - cb->user_callback(cb->err, 0, 0, cb->ttl, NULL, user_pointer); - break; - case TYPE_PTR: - if (cb->have_reply) { - char *name = cb->reply.data.ptr.name; - cb->user_callback(DNS_ERR_NONE, DNS_PTR, 1, cb->ttl, - &name, user_pointer); - } else { - cb->user_callback(cb->err, 0, 0, cb->ttl, NULL, user_pointer); - } - break; - case TYPE_AAAA: - if (cb->have_reply) - cb->user_callback(DNS_ERR_NONE, DNS_IPv6_AAAA, - cb->reply.data.aaaa.addrcount, cb->ttl, - cb->reply.data.aaaa.addresses, - user_pointer); - else - cb->user_callback(cb->err, 0, 0, cb->ttl, NULL, user_pointer); - break; - default: - EVUTIL_ASSERT(0); - } - - if (cb->handle && cb->handle->pending_cb) { - mm_free(cb->handle); - } - - mm_free(cb); -} - -static void -reply_schedule_callback(struct request *const req, u32 ttl, u32 err, struct reply *reply) -{ - struct deferred_reply_callback *d = mm_calloc(1, sizeof(*d)); - - if (!d) { - event_warn("%s: Couldn't allocate space for deferred callback.", - __func__); - return; - } - - ASSERT_LOCKED(req->base); - - d->request_type = req->request_type; - d->user_callback = req->user_callback; - d->ttl = ttl; - d->err = err; - if (reply) { - d->have_reply = 1; - memcpy(&d->reply, reply, sizeof(struct reply)); - } - - if (req->handle) { - req->handle->pending_cb = 1; - d->handle = req->handle; - } - - event_deferred_cb_init_( - &d->deferred, - event_get_priority(&req->timeout_event), - reply_run_callback, - req->user_pointer); - event_deferred_cb_schedule_( - req->base->event_base, - &d->deferred); -} - -/* this processes a parsed reply packet */ -static void -reply_handle(struct request *const req, u16 flags, u32 ttl, struct reply *reply) { - int error; - char addrbuf[128]; - static const int error_codes[] = { - DNS_ERR_FORMAT, DNS_ERR_SERVERFAILED, DNS_ERR_NOTEXIST, - DNS_ERR_NOTIMPL, DNS_ERR_REFUSED - }; - - ASSERT_LOCKED(req->base); - ASSERT_VALID_REQUEST(req); - - if (flags & 0x020f || !reply || !reply->have_answer) { - /* there was an error */ - if (flags & 0x0200) { - error = DNS_ERR_TRUNCATED; - } else if (flags & 0x000f) { - u16 error_code = (flags & 0x000f) - 1; - if (error_code > 4) { - error = DNS_ERR_UNKNOWN; - } else { - error = error_codes[error_code]; - } - } else if (reply && !reply->have_answer) { - error = DNS_ERR_NODATA; - } else { - error = DNS_ERR_UNKNOWN; - } - - switch (error) { - case DNS_ERR_NOTIMPL: - case DNS_ERR_REFUSED: - /* we regard these errors as marking a bad nameserver */ - if (req->reissue_count < req->base->global_max_reissues) { - char msg[64]; - evutil_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" - "at %s; will allow the request to time out.", - evutil_format_sockaddr_port_( - (struct sockaddr *)&req->ns->address, - addrbuf, sizeof(addrbuf))); - /* Call the timeout function */ - evdns_request_timeout_callback(0, 0, req); - return; - default: - /* we got a good reply from the nameserver: it is up. */ - if (req->handle == req->ns->probe_request) { - /* Avoid double-free */ - req->ns->probe_request = NULL; - } - - nameserver_up(req->ns); - } - - if (req->handle->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->handle)) { - /* 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. */ - return; - } - } - - /* all else failed. Pass the failure up */ - reply_schedule_callback(req, ttl, error, NULL); - request_finished(req, &REQ_HEAD(req->base, req->trans_id), 1); - } else { - /* all ok, tell the user */ - reply_schedule_callback(req, ttl, 0, reply); - if (req->handle == req->ns->probe_request) - req->ns->probe_request = NULL; /* Avoid double-free */ - nameserver_up(req->ns); - request_finished(req, &REQ_HEAD(req->base, req->trans_id), 1); - } -} - -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; - 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; - if (j + label_len > length) 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(struct evdns_base *base, u8 *packet, int length) { - int j = 0, k = 0; /* index into packet */ - u16 t_; /* used by the macros */ - u32 t32_; /* used by the macros */ - char tmp_name[256], cmp_name[256]; /* used by the macros */ - int name_matches = 0; - - 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; - - ASSERT_LOCKED(base); - - 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(base, trans_id); - if (!req) return -1; - EVUTIL_ASSERT(req->base == base); - - 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) && (flags & 0x020f) != DNS_ERR_NOTEXIST) { - /* there was an error and it's not NXDOMAIN */ - 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> - */ - tmp_name[0] = '\0'; - cmp_name[0] = '\0'; - k = j; - if (name_parse(packet, length, &j, tmp_name, sizeof(tmp_name)) < 0) - goto err; - if (name_parse(req->request, req->request_len, &k, - cmp_name, sizeof(cmp_name))<0) - goto err; - if (!base->global_randomize_case) { - if (strcmp(tmp_name, cmp_name) == 0) - name_matches = 1; - } else { - if (evutil_ascii_strcasecmp(tmp_name, cmp_name) == 0) - name_matches = 1; - } - - j += 4; - if (j > length) - goto err; - } - - if (!name_matches) - 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_V4_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_V4_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_CNAME) { - char cname[HOST_NAME_MAX]; - if (!req->put_cname_in_ptr || *req->put_cname_in_ptr) { - j += datalength; continue; - } - if (name_parse(packet, length, &j, cname, - sizeof(cname))<0) - goto err; - *req->put_cname_in_ptr = mm_strdup(cname); - } 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_V6_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_V6_ADDRS) break; - } else { - /* skip over any other type of resource */ - j += datalength; - } - } - - if (!reply.have_answer) { - for (i = 0; i < authority; ++i) { - u16 type, class; - SKIP_NAME; - GET16(type); - GET16(class); - GET32(ttl); - GET16(datalength); - if (type == TYPE_SOA && class == CLASS_INET) { - u32 serial, refresh, retry, expire, minimum; - SKIP_NAME; - SKIP_NAME; - GET32(serial); - GET32(refresh); - GET32(retry); - GET32(expire); - GET32(minimum); - (void)expire; - (void)retry; - (void)refresh; - (void)serial; - ttl_r = MIN(ttl_r, ttl); - ttl_r = MIN(ttl_r, minimum); - } else { - /* skip over any other type of resource */ - j += datalength; - } - } - } - - if (ttl_r == 0xffffffff) - ttl_r = 0; - - 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, ev_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; - - ASSERT_LOCKED(port); - - /* Get the header fields */ - GET16(trans_id); - GET16(flags); - GET16(questions); - GET16(answers); - GET16(authority); - GET16(additional); - (void)answers; - (void)additional; - (void)authority; - - if (flags & 0x8000) return -1; /* Must not be an answer. */ - flags &= 0x0110; /* Only RD and CD get preserved. */ - - server_req = mm_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 = mm_calloc(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 = (int)strlen(tmp_name); - q = mm_malloc(sizeof(struct evdns_server_question) + namelen); - if (!q) - goto err; - q->type = type; - q->dns_question_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++; - - /* Only standard queries are supported. */ - if (flags & 0x7800) { - evdns_server_request_respond(&(server_req->base), DNS_ERR_NOTIMPL); - return -1; - } - - 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) - mm_free(server_req->base.questions[i]); - mm_free(server_req->base.questions); - } - mm_free(server_req); - } - return -1; - -#undef SKIP_NAME -#undef GET32 -#undef GET16 -#undef GET8 -} - - -void -evdns_set_transaction_id_fn(ev_uint16_t (*fn)(void)) -{ -} - -void -evdns_set_random_bytes_fn(void (*fn)(char *, size_t)) -{ -} - -/* Try to choose a strong transaction id which isn't already in flight */ -static u16 -transaction_id_pick(struct evdns_base *base) { - ASSERT_LOCKED(base); - for (;;) { - u16 trans_id; - evutil_secure_rng_get_bytes(&trans_id, sizeof(trans_id)); - - if (trans_id == 0xffff) continue; - /* now check to see if that id is already inflight */ - if (request_find_from_trans_id(base, trans_id) == NULL) - 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(struct evdns_base *base) { - struct nameserver *started_at = base->server_head, *picked; - ASSERT_LOCKED(base); - if (!base->server_head) return NULL; - - /* if we don't have any good nameservers then there's no */ - /* point in trying to find one. */ - if (!base->global_good_nameservers) { - base->server_head = base->server_head->next; - return base->server_head; - } - - /* remember that nameservers are in a circular list */ - for (;;) { - if (base->server_head->state) { - /* we think this server is currently good */ - picked = base->server_head; - base->server_head = base->server_head->next; - return picked; - } - - base->server_head = base->server_head->next; - if (base->server_head == started_at) { - /* all the nameservers seem to be down */ - /* so we just return this one and hope for the */ - /* best */ - EVUTIL_ASSERT(base->global_good_nameservers == 0); - picked = base->server_head; - base->server_head = base->server_head->next; - return picked; - } - } -} - -/* this is called when a namesever socket is ready for reading */ -static void -nameserver_read(struct nameserver *ns) { - struct sockaddr_storage ss; - ev_socklen_t addrlen = sizeof(ss); - u8 packet[1500]; - char addrbuf[128]; - ASSERT_LOCKED(ns->base); - - for (;;) { - const int r = recvfrom(ns->socket, (void*)packet, - sizeof(packet), 0, - (struct sockaddr*)&ss, &addrlen); - if (r < 0) { - int err = evutil_socket_geterror(ns->socket); - if (EVUTIL_ERR_RW_RETRIABLE(err)) - return; - nameserver_failed(ns, - evutil_socket_error_to_string(err)); - return; - } - if (evutil_sockaddr_cmp((struct sockaddr*)&ss, - (struct sockaddr*)&ns->address, 0)) { - log(EVDNS_LOG_WARN, "Address mismatch on received " - "DNS packet. Apparent source was %s", - evutil_format_sockaddr_port_( - (struct sockaddr *)&ss, - addrbuf, sizeof(addrbuf))); - return; - } - - ns->timedout = 0; - reply_parse(ns->base, 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; - ev_socklen_t addrlen; - int r; - ASSERT_LOCKED(s); - - for (;;) { - addrlen = sizeof(struct sockaddr_storage); - r = recvfrom(s->socket, (void*)packet, sizeof(packet), 0, - (struct sockaddr*) &addr, &addrlen); - if (r < 0) { - int err = evutil_socket_geterror(s->socket); - if (EVUTIL_ERR_RW_RETRIABLE(err)) - return; - log(EVDNS_LOG_WARN, - "Error %s (%d) while reading request.", - evutil_socket_error_to_string(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) -{ - struct server_request *req = port->pending_replies; - ASSERT_LOCKED(port); - while (req) { - int r = sendto(port->socket, req->response, (int)req->response_len, 0, - (struct sockaddr*) &req->addr, (ev_socklen_t)req->addrlen); - if (r < 0) { - int err = evutil_socket_geterror(port->socket); - if (EVUTIL_ERR_RW_RETRIABLE(err)) - return; - log(EVDNS_LOG_WARN, "Error %s (%d) while writing response to port; dropping", evutil_socket_error_to_string(err), err); - } - if (server_request_free(req)) { - /* we released the last reference to req->port. */ - return; - } else { - EVUTIL_ASSERT(req != port->pending_replies); - req = port->pending_replies; - } - } - - /* We have no more pending requests; stop listening for 'writeable' events. */ - (void) event_del(&port->event); - event_assign(&port->event, port->event_base, - 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) { - ASSERT_LOCKED(ns->base); - if (ns->write_waiting == waiting) return; - - ns->write_waiting = waiting; - (void) event_del(&ns->event); - event_assign(&ns->event, ns->base->event_base, - ns->socket, EV_READ | (waiting ? EV_WRITE : 0) | EV_PERSIST, - nameserver_ready_callback, ns); - if (event_add(&ns->event, NULL) < 0) { - char addrbuf[128]; - log(EVDNS_LOG_WARN, "Error from libevent when adding event for %s", - evutil_format_sockaddr_port_( - (struct sockaddr *)&ns->address, - addrbuf, sizeof(addrbuf))); - /* ???? 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(evutil_socket_t fd, short events, void *arg) { - struct nameserver *ns = (struct nameserver *) arg; - (void)fd; - - EVDNS_LOCK(ns->base); - if (events & EV_WRITE) { - ns->choked = 0; - if (!evdns_transmit(ns->base)) { - nameserver_write_waiting(ns, 0); - } - } - if (events & EV_READ) { - nameserver_read(ns); - } - EVDNS_UNLOCK(ns->base); -} - -/* 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(evutil_socket_t fd, short events, void *arg) { - struct evdns_server_port *port = (struct evdns_server_port *) arg; - (void) fd; - - EVDNS_LOCK(port); - if (events & EV_WRITE) { - port->choked = 0; - server_port_flush(port); - } - if (events & EV_READ) { - server_port_read(port); - } - EVDNS_UNLOCK(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) - mm_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 = mm_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 size_t 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 size_t 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++] = (ev_uint8_t)label_len; - - memcpy(buf + j, start, label_len); - j += (int) label_len; - break; - } else { - /* append length of the label. */ - const size_t 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++] = (ev_uint8_t)label_len; - - memcpy(buf + j, start, label_len); - j += (int) label_len; - /* 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 size_t -evdns_request_len(const size_t 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 size_t 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_with_base(struct event_base *base, evutil_socket_t socket, int flags, evdns_request_callback_fn_type cb, void *user_data) -{ - struct evdns_server_port *port; - if (flags) - return NULL; /* flags not yet implemented */ - if (!(port = mm_malloc(sizeof(struct evdns_server_port)))) - return NULL; - memset(port, 0, sizeof(struct evdns_server_port)); - - - 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; - port->event_base = base; - - event_assign(&port->event, port->event_base, - port->socket, EV_READ | EV_PERSIST, - server_port_ready_callback, port); - if (event_add(&port->event, NULL) < 0) { - mm_free(port); - return NULL; - } - EVTHREAD_ALLOC_LOCK(port->lock, EVTHREAD_LOCKTYPE_RECURSIVE); - return port; -} - -struct evdns_server_port * -evdns_add_server_port(evutil_socket_t socket, int flags, evdns_request_callback_fn_type cb, void *user_data) -{ - return evdns_add_server_port_with_base(NULL, socket, flags, cb, user_data); -} - -/* exported function */ -void -evdns_close_server_port(struct evdns_server_port *port) -{ - EVDNS_LOCK(port); - if (--port->refcnt == 0) { - EVDNS_UNLOCK(port); - server_port_free(port); - } else { - 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; - int result = -1; - - EVDNS_LOCK(req->port); - if (req->response) /* have we already answered? */ - goto done; - - 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: - goto done; - } - while (*itemp) { - itemp = &((*itemp)->next); - } - item = mm_malloc(sizeof(struct server_reply_item)); - if (!item) - goto done; - item->next = NULL; - if (!(item->name = mm_strdup(name))) { - mm_free(item); - goto done; - } - item->type = type; - item->dns_question_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 = mm_strdup(data))) { - mm_free(item->name); - mm_free(item); - goto done; - } - item->datalen = (u16)-1; - } else { - if (!(item->data = mm_malloc(datalen))) { - mm_free(item->name); - mm_free(item); - goto done; - } - item->datalen = datalen; - memcpy(item->data, data, datalen); - } - } - - *itemp = item; - ++(*countp); - result = 0; -done: - EVDNS_UNLOCK(req->port); - return result; -} - -/* exported function */ -int -evdns_server_request_add_a_reply(struct evdns_server_request *req, const char *name, int n, const 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, const 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]; - if (in && inaddr_name) - return -1; - else if (!in && !inaddr_name) - return -1; - if (in) { - a = ntohl(in->s_addr); - evutil_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_CNAME, CLASS_INET, - ttl, -1, 1, cname); -} - -/* exported function */ -void -evdns_server_request_set_flags(struct evdns_server_request *exreq, int flags) -{ - struct server_request *req = TO_SERVER_REQUEST(exreq); - req->base.flags &= ~(EVDNS_FLAGS_AA|EVDNS_FLAGS_RD); - req->base.flags |= flags; -} - -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]->dns_question_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->dns_question_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( (short) (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[2] |= 0x02; /* set the truncated bit. */ - } - - req->response_len = j; - - if (!(req->response = mm_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 = -1; - - EVDNS_LOCK(port); - if (!req->response) { - if ((r = evdns_server_request_format_response(req, err))<0) - goto done; - } - - r = sendto(port->socket, req->response, (int)req->response_len, 0, - (struct sockaddr*) &req->addr, (ev_socklen_t)req->addrlen); - if (r<0) { - int sock_err = evutil_socket_geterror(port->socket); - if (EVUTIL_ERR_RW_RETRIABLE(sock_err)) - goto done; - - 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_assign(&port->event, port->event_base, 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"); - } - - } - - r = 1; - goto done; - } - if (server_request_free(req)) { - r = 0; - goto done; - } - - if (port->pending_replies) - server_port_flush(port); - - r = 0; -done: - EVDNS_UNLOCK(port); - return r; -} - -/* 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; - mm_free(victim->name); - if (victim->data) - mm_free(victim->data); - mm_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, lock=0; - if (req->base.questions) { - for (i = 0; i < req->base.nquestions; ++i) - mm_free(req->base.questions[i]); - mm_free(req->base.questions); - } - - if (req->port) { - EVDNS_LOCK(req->port); - lock=1; - if (req->port->pending_replies == req) { - if (req->next_pending && req->next_pending != req) - req->port->pending_replies = req->next_pending; - else - req->port->pending_replies = NULL; - } - rc = --req->port->refcnt; - } - - if (req->response) { - mm_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) { - EVDNS_UNLOCK(req->port); /* ????? nickm */ - server_port_free(req->port); - mm_free(req); - return (1); - } - if (lock) - EVDNS_UNLOCK(req->port); - mm_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) -{ - EVUTIL_ASSERT(port); - EVUTIL_ASSERT(!port->refcnt); - EVUTIL_ASSERT(!port->pending_replies); - if (port->socket > 0) { - evutil_closesocket(port->socket); - port->socket = -1; - } - (void) event_del(&port->event); - event_debug_unassign(&port->event); - EVTHREAD_FREE_LOCK(port->lock, EVTHREAD_LOCKTYPE_RECURSIVE); - mm_free(port); -} - -/* 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(evutil_socket_t fd, short events, void *arg) { - struct request *const req = (struct request *) arg; - struct evdns_base *base = req->base; - - (void) fd; - (void) events; - - log(EVDNS_LOG_DEBUG, "Request %p timed out", arg); - EVDNS_LOCK(base); - - if (req->tx_count >= req->base->global_max_retransmits) { - struct nameserver *ns = req->ns; - /* this request has failed */ - log(EVDNS_LOG_DEBUG, "Giving up on request %p; tx_count==%d", - arg, req->tx_count); - reply_schedule_callback(req, 0, DNS_ERR_TIMEOUT, NULL); - - request_finished(req, &REQ_HEAD(req->base, req->trans_id), 1); - nameserver_failed(ns, "request timed out."); - } else { - /* retransmit it */ - log(EVDNS_LOG_DEBUG, "Retransmitting request %p; tx_count==%d", - arg, req->tx_count); - (void) evtimer_del(&req->timeout_event); - request_swap_ns(req, nameserver_pick(base)); - evdns_request_transmit(req); - - req->ns->timedout++; - if (req->ns->timedout > req->base->global_max_nameserver_timeout) { - req->ns->timedout = 0; - nameserver_failed(req->ns, "request timed out."); - } - } - - EVDNS_UNLOCK(base); -} - -/* 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) { - int r; - ASSERT_LOCKED(req->base); - ASSERT_VALID_REQUEST(req); - - if (server->requests_inflight == 1 && - req->base->disable_when_inactive && - event_add(&server->event, NULL) < 0) { - return 1; - } - - r = sendto(server->socket, (void*)req->request, req->request_len, 0, - (struct sockaddr *)&server->address, server->addrlen); - if (r < 0) { - int err = evutil_socket_geterror(server->socket); - if (EVUTIL_ERR_RW_RETRIABLE(err)) - return 1; - nameserver_failed(req->ns, evutil_socket_error_to_string(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; - - ASSERT_LOCKED(req->base); - ASSERT_VALID_REQUEST(req); - /* if we fail to send this packet then this flag marks it */ - /* for evdns_transmit */ - req->transmit_me = 1; - EVUTIL_ASSERT(req->trans_id != 0xffff); - - if (!req->ns) - { - /* unable to transmit request if no nameservers */ - return 1; - } - - 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 to transmit the request entirely. */ - retcode = 1; - /* fall through: we'll set a timeout, which will time out, - * and make us retransmit the request anyway. */ - default: - /* all ok */ - log(EVDNS_LOG_DEBUG, - "Setting timeout for request %p, sent to nameserver %p", req, req->ns); - if (evtimer_add(&req->timeout_event, &req->base->global_timeout) < 0) { - log(EVDNS_LOG_WARN, - "Error from libevent when adding timer for request %p", - 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_CANCEL) { - /* We canceled this request because the nameserver came up - * for some other reason. Do not change our opinion about - * the nameserver. */ - return; - } - - EVDNS_LOCK(ns->base); - ns->probe_request = NULL; - if (result == DNS_ERR_NONE || result == DNS_ERR_NOTEXIST) { - /* this is a good reply */ - nameserver_up(ns); - } else { - nameserver_probe_failed(ns); - } - EVDNS_UNLOCK(ns->base); -} - -static void -nameserver_send_probe(struct nameserver *const ns) { - struct evdns_request *handle; - struct request *req; - char addrbuf[128]; - /* here we need to send a probe to a given nameserver */ - /* in the hope that it is up now. */ - - ASSERT_LOCKED(ns->base); - log(EVDNS_LOG_DEBUG, "Sending probe to %s", - evutil_format_sockaddr_port_( - (struct sockaddr *)&ns->address, - addrbuf, sizeof(addrbuf))); - handle = mm_calloc(1, sizeof(*handle)); - if (!handle) return; - req = request_new(ns->base, handle, TYPE_A, "google.com", DNS_QUERY_NO_SEARCH, nameserver_probe_callback, ns); - if (!req) { - mm_free(handle); - return; - } - ns->probe_request = handle; - /* we force this into the inflight queue no matter what */ - request_trans_id_set(req, transaction_id_pick(ns->base)); - req->ns = ns; - request_submit(req); -} - -/* returns: */ -/* 0 didn't try to transmit anything */ -/* 1 tried to transmit something */ -static int -evdns_transmit(struct evdns_base *base) { - char did_try_to_transmit = 0; - int i; - - ASSERT_LOCKED(base); - for (i = 0; i < base->n_req_heads; ++i) { - if (base->req_heads[i]) { - struct request *const started_at = base->req_heads[i], *req = started_at; - /* 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_base_count_nameservers(struct evdns_base *base) -{ - const struct nameserver *server; - int n = 0; - - EVDNS_LOCK(base); - server = base->server_head; - if (!server) - goto done; - do { - ++n; - server = server->next; - } while (server != base->server_head); -done: - EVDNS_UNLOCK(base); - return n; -} - -int -evdns_count_nameservers(void) -{ - return evdns_base_count_nameservers(current_base); -} - -/* exported function */ -int -evdns_base_clear_nameservers_and_suspend(struct evdns_base *base) -{ - struct nameserver *server, *started_at; - int i; - - EVDNS_LOCK(base); - server = base->server_head; - started_at = base->server_head; - if (!server) { - EVDNS_UNLOCK(base); - return 0; - } - while (1) { - struct nameserver *next = server->next; - (void) event_del(&server->event); - if (evtimer_initialized(&server->timeout_event)) - (void) evtimer_del(&server->timeout_event); - if (server->probe_request) { - evdns_cancel_request(server->base, server->probe_request); - server->probe_request = NULL; - } - if (server->socket >= 0) - evutil_closesocket(server->socket); - mm_free(server); - if (next == started_at) - break; - server = next; - } - base->server_head = NULL; - base->global_good_nameservers = 0; - - for (i = 0; i < base->n_req_heads; ++i) { - struct request *req, *req_started_at; - req = req_started_at = base->req_heads[i]; - 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; - - base->global_requests_waiting++; - evdns_request_insert(req, &base->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.*/ - base->req_waiting_head = base->req_waiting_head->prev; - - if (next == req_started_at) - break; - req = next; - } - base->req_heads[i] = NULL; - } - - base->global_requests_inflight = 0; - - EVDNS_UNLOCK(base); - return 0; -} - -int -evdns_clear_nameservers_and_suspend(void) -{ - return evdns_base_clear_nameservers_and_suspend(current_base); -} - - -/* exported function */ -int -evdns_base_resume(struct evdns_base *base) -{ - EVDNS_LOCK(base); - evdns_requests_pump_waiting_queue(base); - EVDNS_UNLOCK(base); - - return 0; -} - -int -evdns_resume(void) -{ - return evdns_base_resume(current_base); -} - -static int -evdns_nameserver_add_impl_(struct evdns_base *base, const struct sockaddr *address, int addrlen) { - /* first check to see if we already have this nameserver */ - - const struct nameserver *server = base->server_head, *const started_at = base->server_head; - struct nameserver *ns; - int err = 0; - char addrbuf[128]; - - ASSERT_LOCKED(base); - if (server) { - do { - if (!evutil_sockaddr_cmp((struct sockaddr*)&server->address, address, 1)) return 3; - server = server->next; - } while (server != started_at); - } - if (addrlen > (int)sizeof(ns->address)) { - log(EVDNS_LOG_DEBUG, "Addrlen %d too long.", (int)addrlen); - return 2; - } - - ns = (struct nameserver *) mm_malloc(sizeof(struct nameserver)); - if (!ns) return -1; - - memset(ns, 0, sizeof(struct nameserver)); - ns->base = base; - - evtimer_assign(&ns->timeout_event, ns->base->event_base, nameserver_prod_callback, ns); - - ns->socket = evutil_socket_(address->sa_family, - SOCK_DGRAM|EVUTIL_SOCK_NONBLOCK|EVUTIL_SOCK_CLOEXEC, 0); - if (ns->socket < 0) { err = 1; goto out1; } - - if (base->global_outgoing_addrlen && - !evutil_sockaddr_is_loopback_(address)) { - if (bind(ns->socket, - (struct sockaddr*)&base->global_outgoing_address, - base->global_outgoing_addrlen) < 0) { - log(EVDNS_LOG_WARN,"Couldn't bind to outgoing address"); - err = 2; - goto out2; - } - } - - memcpy(&ns->address, address, addrlen); - ns->addrlen = addrlen; - ns->state = 1; - event_assign(&ns->event, ns->base->event_base, ns->socket, - EV_READ | EV_PERSIST, nameserver_ready_callback, ns); - if (!base->disable_when_inactive && event_add(&ns->event, NULL) < 0) { - err = 2; - goto out2; - } - - log(EVDNS_LOG_DEBUG, "Added nameserver %s as %p", - evutil_format_sockaddr_port_(address, addrbuf, sizeof(addrbuf)), ns); - - /* insert this nameserver into the list of them */ - if (!base->server_head) { - ns->next = ns->prev = ns; - base->server_head = ns; - } else { - ns->next = base->server_head->next; - ns->prev = base->server_head; - base->server_head->next = ns; - ns->next->prev = ns; - } - - base->global_good_nameservers++; - - return 0; - -out2: - evutil_closesocket(ns->socket); -out1: - event_debug_unassign(&ns->event); - mm_free(ns); - log(EVDNS_LOG_WARN, "Unable to add nameserver %s: error %d", - evutil_format_sockaddr_port_(address, addrbuf, sizeof(addrbuf)), err); - return err; -} - -/* exported function */ -int -evdns_base_nameserver_add(struct evdns_base *base, unsigned long int address) -{ - struct sockaddr_in sin; - int res; - memset(&sin, 0, sizeof(sin)); - sin.sin_addr.s_addr = address; - sin.sin_port = htons(53); - sin.sin_family = AF_INET; - EVDNS_LOCK(base); - res = evdns_nameserver_add_impl_(base, (struct sockaddr*)&sin, sizeof(sin)); - EVDNS_UNLOCK(base); - return res; -} - -int -evdns_nameserver_add(unsigned long int address) { - if (!current_base) - current_base = evdns_base_new(NULL, 0); - return evdns_base_nameserver_add(current_base, address); -} - -static void -sockaddr_setport(struct sockaddr *sa, ev_uint16_t port) -{ - if (sa->sa_family == AF_INET) { - ((struct sockaddr_in *)sa)->sin_port = htons(port); - } else if (sa->sa_family == AF_INET6) { - ((struct sockaddr_in6 *)sa)->sin6_port = htons(port); - } -} - -static ev_uint16_t -sockaddr_getport(struct sockaddr *sa) -{ - if (sa->sa_family == AF_INET) { - return ntohs(((struct sockaddr_in *)sa)->sin_port); - } else if (sa->sa_family == AF_INET6) { - return ntohs(((struct sockaddr_in6 *)sa)->sin6_port); - } else { - return 0; - } -} - -/* exported function */ -int -evdns_base_nameserver_ip_add(struct evdns_base *base, const char *ip_as_string) { - struct sockaddr_storage ss; - struct sockaddr *sa; - int len = sizeof(ss); - int res; - if (evutil_parse_sockaddr_port(ip_as_string, (struct sockaddr *)&ss, - &len)) { - log(EVDNS_LOG_WARN, "Unable to parse nameserver address %s", - ip_as_string); - return 4; - } - sa = (struct sockaddr *) &ss; - if (sockaddr_getport(sa) == 0) - sockaddr_setport(sa, 53); - - EVDNS_LOCK(base); - res = evdns_nameserver_add_impl_(base, sa, len); - EVDNS_UNLOCK(base); - return res; -} - -int -evdns_nameserver_ip_add(const char *ip_as_string) { - if (!current_base) - current_base = evdns_base_new(NULL, 0); - return evdns_base_nameserver_ip_add(current_base, ip_as_string); -} - -int -evdns_base_nameserver_sockaddr_add(struct evdns_base *base, - const struct sockaddr *sa, ev_socklen_t len, unsigned flags) -{ - int res; - EVUTIL_ASSERT(base); - EVDNS_LOCK(base); - res = evdns_nameserver_add_impl_(base, sa, len); - EVDNS_UNLOCK(base); - return res; -} - -int -evdns_base_get_nameserver_addr(struct evdns_base *base, int idx, - struct sockaddr *sa, ev_socklen_t len) -{ - int result = -1; - int i; - struct nameserver *server; - EVDNS_LOCK(base); - server = base->server_head; - for (i = 0; i < idx && server; ++i, server = server->next) { - if (server->next == base->server_head) - goto done; - } - if (! server) - goto done; - - if (server->addrlen > len) { - result = (int) server->addrlen; - goto done; - } - - memcpy(sa, &server->address, server->addrlen); - result = (int) server->addrlen; -done: - EVDNS_UNLOCK(base); - return result; -} - -/* remove from the queue */ -static void -evdns_request_remove(struct request *req, struct request **head) -{ - ASSERT_LOCKED(req->base); - ASSERT_VALID_REQUEST(req); - -#if 0 - { - struct request *ptr; - int found = 0; - EVUTIL_ASSERT(*head != NULL); - - ptr = *head; - do { - if (ptr == req) { - found = 1; - break; - } - ptr = ptr->next; - } while (ptr != *head); - EVUTIL_ASSERT(found); - - EVUTIL_ASSERT(req->next); - } -#endif - - 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; - } - req->next = req->prev = NULL; -} - -/* insert into the tail of the queue */ -static void -evdns_request_insert(struct request *req, struct request **head) { - ASSERT_LOCKED(req->base); - ASSERT_VALID_REQUEST(req); - 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(struct evdns_base *base, struct evdns_request *handle, int type, - const char *name, int flags, evdns_callback_type callback, - void *user_ptr) { - - const char issuing_now = - (base->global_requests_inflight < base->global_max_requests_inflight) ? 1 : 0; - - const size_t name_len = strlen(name); - const size_t request_max_len = evdns_request_len(name_len); - const u16 trans_id = issuing_now ? transaction_id_pick(base) : 0xffff; - /* the request data is alloced in a single block with the header */ - struct request *const req = - mm_malloc(sizeof(struct request) + request_max_len); - int rlen; - char namebuf[256]; - (void) flags; - - ASSERT_LOCKED(base); - - if (!req) return NULL; - - if (name_len >= sizeof(namebuf)) { - mm_free(req); - return NULL; - } - - memset(req, 0, sizeof(struct request)); - req->base = base; - - evtimer_assign(&req->timeout_event, req->base->event_base, evdns_request_timeout_callback, req); - - if (base->global_randomize_case) { - unsigned i; - char randbits[(sizeof(namebuf)+7)/8]; - strlcpy(namebuf, name, sizeof(namebuf)); - evutil_secure_rng_get_bytes(randbits, (name_len+7)/8); - for (i = 0; i < name_len; ++i) { - if (EVUTIL_ISALPHA_(namebuf[i])) { - if ((randbits[i >> 3] & (1<<(i & 7)))) - namebuf[i] |= 0x20; - else - namebuf[i] &= ~0x20; - } - } - name = namebuf; - } - - /* 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(base) : NULL; - req->next = req->prev = NULL; - req->handle = handle; - if (handle) { - handle->current_req = req; - handle->base = base; - } - - return req; -err1: - mm_free(req); - return NULL; -} - -static void -request_submit(struct request *const req) { - struct evdns_base *base = req->base; - ASSERT_LOCKED(base); - ASSERT_VALID_REQUEST(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(base, req->trans_id)); - - base->global_requests_inflight++; - req->ns->requests_inflight++; - - evdns_request_transmit(req); - } else { - evdns_request_insert(req, &base->req_waiting_head); - base->global_requests_waiting++; - } -} - -/* exported function */ -void -evdns_cancel_request(struct evdns_base *base, struct evdns_request *handle) -{ - struct request *req; - - if (!handle->current_req) - return; - - if (!base) { - /* This redundancy is silly; can we fix it? (Not for 2.0) XXXX */ - base = handle->base; - if (!base) - base = handle->current_req->base; - } - - EVDNS_LOCK(base); - if (handle->pending_cb) { - EVDNS_UNLOCK(base); - return; - } - - req = handle->current_req; - ASSERT_VALID_REQUEST(req); - - reply_schedule_callback(req, 0, DNS_ERR_CANCEL, NULL); - if (req->ns) { - /* remove from inflight queue */ - request_finished(req, &REQ_HEAD(base, req->trans_id), 1); - } else { - /* remove from global_waiting head */ - request_finished(req, &base->req_waiting_head, 1); - } - EVDNS_UNLOCK(base); -} - -/* exported function */ -struct evdns_request * -evdns_base_resolve_ipv4(struct evdns_base *base, const char *name, int flags, - evdns_callback_type callback, void *ptr) { - struct evdns_request *handle; - struct request *req; - log(EVDNS_LOG_DEBUG, "Resolve requested for %s", name); - handle = mm_calloc(1, sizeof(*handle)); - if (handle == NULL) - return NULL; - EVDNS_LOCK(base); - if (flags & DNS_QUERY_NO_SEARCH) { - req = - request_new(base, handle, TYPE_A, name, flags, - callback, ptr); - if (req) - request_submit(req); - } else { - search_request_new(base, handle, TYPE_A, name, flags, - callback, ptr); - } - if (handle->current_req == NULL) { - mm_free(handle); - handle = NULL; - } - EVDNS_UNLOCK(base); - return handle; -} - -int evdns_resolve_ipv4(const char *name, int flags, - evdns_callback_type callback, void *ptr) -{ - return evdns_base_resolve_ipv4(current_base, name, flags, callback, ptr) - ? 0 : -1; -} - - -/* exported function */ -struct evdns_request * -evdns_base_resolve_ipv6(struct evdns_base *base, - const char *name, int flags, - evdns_callback_type callback, void *ptr) -{ - struct evdns_request *handle; - struct request *req; - log(EVDNS_LOG_DEBUG, "Resolve requested for %s", name); - handle = mm_calloc(1, sizeof(*handle)); - if (handle == NULL) - return NULL; - EVDNS_LOCK(base); - if (flags & DNS_QUERY_NO_SEARCH) { - req = request_new(base, handle, TYPE_AAAA, name, flags, - callback, ptr); - if (req) - request_submit(req); - } else { - search_request_new(base, handle, TYPE_AAAA, name, flags, - callback, ptr); - } - if (handle->current_req == NULL) { - mm_free(handle); - handle = NULL; - } - EVDNS_UNLOCK(base); - return handle; -} - -int evdns_resolve_ipv6(const char *name, int flags, - evdns_callback_type callback, void *ptr) { - return evdns_base_resolve_ipv6(current_base, name, flags, callback, ptr) - ? 0 : -1; -} - -struct evdns_request * -evdns_base_resolve_reverse(struct evdns_base *base, const struct in_addr *in, int flags, evdns_callback_type callback, void *ptr) { - char buf[32]; - struct evdns_request *handle; - struct request *req; - u32 a; - EVUTIL_ASSERT(in); - a = ntohl(in->s_addr); - evutil_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)); - handle = mm_calloc(1, sizeof(*handle)); - if (handle == NULL) - return NULL; - log(EVDNS_LOG_DEBUG, "Resolve requested for %s (reverse)", buf); - EVDNS_LOCK(base); - req = request_new(base, handle, TYPE_PTR, buf, flags, callback, ptr); - if (req) - request_submit(req); - if (handle->current_req == NULL) { - mm_free(handle); - handle = NULL; - } - EVDNS_UNLOCK(base); - return (handle); -} - -int evdns_resolve_reverse(const struct in_addr *in, int flags, evdns_callback_type callback, void *ptr) { - return evdns_base_resolve_reverse(current_base, in, flags, callback, ptr) - ? 0 : -1; -} - -struct evdns_request * -evdns_base_resolve_reverse_ipv6(struct evdns_base *base, const struct in6_addr *in, int flags, evdns_callback_type callback, void *ptr) { - /* 32 nybbles, 32 periods, "ip6.arpa", NUL. */ - char buf[73]; - char *cp; - struct evdns_request *handle; - struct request *req; - int i; - EVUTIL_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++ = '.'; - } - EVUTIL_ASSERT(cp + strlen("ip6.arpa") < buf+sizeof(buf)); - memcpy(cp, "ip6.arpa", strlen("ip6.arpa")+1); - handle = mm_calloc(1, sizeof(*handle)); - if (handle == NULL) - return NULL; - log(EVDNS_LOG_DEBUG, "Resolve requested for %s (reverse)", buf); - EVDNS_LOCK(base); - req = request_new(base, handle, TYPE_PTR, buf, flags, callback, ptr); - if (req) - request_submit(req); - if (handle->current_req == NULL) { - mm_free(handle); - handle = NULL; - } - EVDNS_UNLOCK(base); - return (handle); -} - -int evdns_resolve_reverse_ipv6(const struct in6_addr *in, int flags, evdns_callback_type callback, void *ptr) { - return evdns_base_resolve_reverse_ipv6(current_base, in, flags, callback, ptr) - ? 0 : -1; -} - -/* ================================================================= */ -/* 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 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; - mm_free(dom); - } - mm_free(state); - } -} - -static struct search_state * -search_state_new(void) { - struct search_state *state = (struct search_state *) mm_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(struct evdns_base *base) { - search_state_decref(base->global_search_state); - - base->global_search_state = search_state_new(); -} - -/* exported function */ -void -evdns_base_search_clear(struct evdns_base *base) -{ - EVDNS_LOCK(base); - search_postfix_clear(base); - EVDNS_UNLOCK(base); -} - -void -evdns_search_clear(void) { - evdns_base_search_clear(current_base); -} - -static void -search_postfix_add(struct evdns_base *base, const char *domain) { - size_t domain_len; - struct search_domain *sdomain; - while (domain[0] == '.') domain++; - domain_len = strlen(domain); - - ASSERT_LOCKED(base); - if (!base->global_search_state) base->global_search_state = search_state_new(); - if (!base->global_search_state) return; - base->global_search_state->num_domains++; - - sdomain = (struct search_domain *) mm_malloc(sizeof(struct search_domain) + domain_len); - if (!sdomain) return; - memcpy( ((u8 *) sdomain) + sizeof(struct search_domain), domain, domain_len); - sdomain->next = base->global_search_state->head; - sdomain->len = (int) domain_len; - - base->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(struct evdns_base *base) { - struct search_domain *cur, *prev = NULL, *next; - ASSERT_LOCKED(base); - cur = base->global_search_state->head; - while (cur) { - next = cur->next; - cur->next = prev; - prev = cur; - cur = next; - } - - base->global_search_state->head = prev; -} - -/* exported function */ -void -evdns_base_search_add(struct evdns_base *base, const char *domain) { - EVDNS_LOCK(base); - search_postfix_add(base, domain); - EVDNS_UNLOCK(base); -} -void -evdns_search_add(const char *domain) { - evdns_base_search_add(current_base, domain); -} - -/* exported function */ -void -evdns_base_search_ndots_set(struct evdns_base *base, const int ndots) { - EVDNS_LOCK(base); - if (!base->global_search_state) base->global_search_state = search_state_new(); - if (base->global_search_state) - base->global_search_state->ndots = ndots; - EVDNS_UNLOCK(base); -} -void -evdns_search_ndots_set(const int ndots) { - evdns_base_search_ndots_set(current_base, ndots); -} - -static void -search_set_from_hostname(struct evdns_base *base) { - char hostname[HOST_NAME_MAX + 1], *domainname; - - ASSERT_LOCKED(base); - search_postfix_clear(base); - if (gethostname(hostname, sizeof(hostname))) return; - domainname = strchr(hostname, '.'); - if (!domainname) return; - search_postfix_add(base, domainname); -} - -/* warning: returns malloced string */ -static char * -search_make_new(const struct search_state *const state, int n, const char *const base_name) { - const size_t 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 *) mm_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 */ - EVUTIL_ASSERT(0); - return NULL; /* unreachable; stops warnings in some compilers. */ -} - -static struct request * -search_request_new(struct evdns_base *base, struct evdns_request *handle, - int type, const char *const name, int flags, - evdns_callback_type user_callback, void *user_arg) { - ASSERT_LOCKED(base); - EVUTIL_ASSERT(type == TYPE_A || type == TYPE_AAAA); - EVUTIL_ASSERT(handle->current_req == NULL); - if ( ((flags & DNS_QUERY_NO_SEARCH) == 0) && - base->global_search_state && - base->global_search_state->num_domains) { - /* we have some domains to search */ - struct request *req; - if (string_num_dots(name) >= base->global_search_state->ndots) { - req = request_new(base, handle, type, name, flags, user_callback, user_arg); - if (!req) return NULL; - handle->search_index = -1; - } else { - char *const new_name = search_make_new(base->global_search_state, 0, name); - if (!new_name) return NULL; - req = request_new(base, handle, type, new_name, flags, user_callback, user_arg); - mm_free(new_name); - if (!req) return NULL; - handle->search_index = 0; - } - EVUTIL_ASSERT(handle->search_origname == NULL); - handle->search_origname = mm_strdup(name); - if (handle->search_origname == NULL) { - /* XXX Should we dealloc req? If yes, how? */ - if (req) - mm_free(req); - return NULL; - } - handle->search_state = base->global_search_state; - handle->search_flags = flags; - base->global_search_state->refcount++; - request_submit(req); - return req; - } else { - struct request *const req = request_new(base, handle, type, name, flags, user_callback, user_arg); - if (!req) return NULL; - request_submit(req); - return req; - } -} - -/* 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 evdns_request *const handle) { - struct request *req = handle->current_req; - struct evdns_base *base = req->base; - struct request *newreq; - ASSERT_LOCKED(base); - if (handle->search_state) { - /* it is part of a search */ - char *new_name; - handle->search_index++; - if (handle->search_index >= handle->search_state->num_domains) { - /* no more postfixes to try, however we may need to try */ - /* this name without a postfix */ - if (string_num_dots(handle->search_origname) < handle->search_state->ndots) { - /* yep, we need to try it raw */ - newreq = request_new(base, NULL, req->request_type, handle->search_origname, handle->search_flags, req->user_callback, req->user_pointer); - log(EVDNS_LOG_DEBUG, "Search: trying raw query %s", handle->search_origname); - if (newreq) { - search_request_finished(handle); - goto submit_next; - } - } - return 1; - } - - new_name = search_make_new(handle->search_state, handle->search_index, handle->search_origname); - if (!new_name) return 1; - log(EVDNS_LOG_DEBUG, "Search: now trying %s (%d)", new_name, handle->search_index); - newreq = request_new(base, NULL, req->request_type, new_name, handle->search_flags, req->user_callback, req->user_pointer); - mm_free(new_name); - if (!newreq) return 1; - goto submit_next; - } - return 1; - -submit_next: - request_finished(req, &REQ_HEAD(req->base, req->trans_id), 0); - handle->current_req = newreq; - newreq->handle = handle; - request_submit(newreq); - return 0; -} - -static void -search_request_finished(struct evdns_request *const handle) { - ASSERT_LOCKED(handle->current_req->base); - if (handle->search_state) { - search_state_decref(handle->search_state); - handle->search_state = NULL; - } - if (handle->search_origname) { - mm_free(handle->search_origname); - handle->search_origname = NULL; - } -} - -/* ================================================================= */ -/* Parsing resolv.conf files */ - -static void -evdns_resolv_set_defaults(struct evdns_base *base, int flags) { - /* if the file isn't found then we assume a local resolver */ - ASSERT_LOCKED(base); - if (flags & DNS_OPTION_SEARCH) search_set_from_hostname(base); - if (flags & DNS_OPTION_NAMESERVERS) evdns_base_nameserver_ip_add(base,"127.0.0.1"); -} - -#ifndef EVENT__HAVE_STRTOK_R -static char * -strtok_r(char *s, const char *delim, char **state) { - char *cp, *start; - start = cp = s ? s : *state; - if (!cp) - return NULL; - while (*cp && !strchr(delim, *cp)) - ++cp; - if (!*cp) { - if (cp == start) - return NULL; - *state = NULL; - return start; - } else { - *cp++ = '\0'; - *state = cp; - return start; - } -} -#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; -} - -/* Parse a number of seconds into a timeval; return -1 on error. */ -static int -evdns_strtotimeval(const char *const str, struct timeval *out) -{ - double d; - char *endptr; - d = strtod(str, &endptr); - if (*endptr) return -1; - if (d < 0) return -1; - out->tv_sec = (int) d; - out->tv_usec = (int) ((d - (int) d)*1000000); - if (out->tv_sec == 0 && out->tv_usec < 1000) /* less than 1 msec */ - return -1; - return 0; -} - -/* 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; -} - -static int -evdns_base_set_max_requests_inflight(struct evdns_base *base, int maxinflight) -{ - int old_n_heads = base->n_req_heads, n_heads; - struct request **old_heads = base->req_heads, **new_heads, *req; - int i; - - ASSERT_LOCKED(base); - if (maxinflight < 1) - maxinflight = 1; - n_heads = (maxinflight+4) / 5; - EVUTIL_ASSERT(n_heads > 0); - new_heads = mm_calloc(n_heads, sizeof(struct request*)); - if (!new_heads) - return (-1); - if (old_heads) { - for (i = 0; i < old_n_heads; ++i) { - while (old_heads[i]) { - req = old_heads[i]; - evdns_request_remove(req, &old_heads[i]); - evdns_request_insert(req, &new_heads[req->trans_id % n_heads]); - } - } - mm_free(old_heads); - } - base->req_heads = new_heads; - base->n_req_heads = n_heads; - base->global_max_requests_inflight = maxinflight; - return (0); -} - -/* exported function */ -int -evdns_base_set_option(struct evdns_base *base, - const char *option, const char *val) -{ - int res; - EVDNS_LOCK(base); - res = evdns_base_set_option_impl(base, option, val, DNS_OPTIONS_ALL); - EVDNS_UNLOCK(base); - return res; -} - -static inline int -str_matches_option(const char *s1, const char *optionname) -{ - /* Option names are given as "option:" We accept either 'option' in - * s1, or 'option:randomjunk'. The latter form is to implement the - * resolv.conf parser. */ - size_t optlen = strlen(optionname); - size_t slen = strlen(s1); - if (slen == optlen || slen == optlen - 1) - return !strncmp(s1, optionname, slen); - else if (slen > optlen) - return !strncmp(s1, optionname, optlen); - else - return 0; -} - -static int -evdns_base_set_option_impl(struct evdns_base *base, - const char *option, const char *val, int flags) -{ - ASSERT_LOCKED(base); - if (str_matches_option(option, "ndots:")) { - 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 (!base->global_search_state) base->global_search_state = search_state_new(); - if (!base->global_search_state) return -1; - base->global_search_state->ndots = ndots; - } else if (str_matches_option(option, "timeout:")) { - struct timeval tv; - if (evdns_strtotimeval(val, &tv) == -1) return -1; - if (!(flags & DNS_OPTION_MISC)) return 0; - log(EVDNS_LOG_DEBUG, "Setting timeout to %s", val); - memcpy(&base->global_timeout, &tv, sizeof(struct timeval)); - } else if (str_matches_option(option, "getaddrinfo-allow-skew:")) { - struct timeval tv; - if (evdns_strtotimeval(val, &tv) == -1) return -1; - if (!(flags & DNS_OPTION_MISC)) return 0; - log(EVDNS_LOG_DEBUG, "Setting getaddrinfo-allow-skew to %s", - val); - memcpy(&base->global_getaddrinfo_allow_skew, &tv, - sizeof(struct timeval)); - } else if (str_matches_option(option, "max-timeouts:")) { - 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); - base->global_max_nameserver_timeout = maxtimeout; - } else if (str_matches_option(option, "max-inflight:")) { - 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); - evdns_base_set_max_requests_inflight(base, maxinflight); - } else if (str_matches_option(option, "attempts:")) { - 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); - base->global_max_retransmits = retries; - } else if (str_matches_option(option, "randomize-case:")) { - int randcase = strtoint(val); - if (!(flags & DNS_OPTION_MISC)) return 0; - base->global_randomize_case = randcase; - } else if (str_matches_option(option, "bind-to:")) { - /* XXX This only applies to successive nameservers, not - * to already-configured ones. We might want to fix that. */ - int len = sizeof(base->global_outgoing_address); - if (!(flags & DNS_OPTION_NAMESERVERS)) return 0; - if (evutil_parse_sockaddr_port(val, - (struct sockaddr*)&base->global_outgoing_address, &len)) - return -1; - base->global_outgoing_addrlen = len; - } else if (str_matches_option(option, "initial-probe-timeout:")) { - struct timeval tv; - if (evdns_strtotimeval(val, &tv) == -1) return -1; - if (tv.tv_sec > 3600) - tv.tv_sec = 3600; - if (!(flags & DNS_OPTION_MISC)) return 0; - log(EVDNS_LOG_DEBUG, "Setting initial probe timeout to %s", - val); - memcpy(&base->global_nameserver_probe_initial_timeout, &tv, - sizeof(tv)); - } - return 0; -} - -int -evdns_set_option(const char *option, const char *val, int flags) -{ - if (!current_base) - current_base = evdns_base_new(NULL, 0); - return evdns_base_set_option(current_base, option, val); -} - -static void -resolv_conf_parse_line(struct evdns_base *base, 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); - ASSERT_LOCKED(base); - if (!first_token) return; - - if (!strcmp(first_token, "nameserver") && (flags & DNS_OPTION_NAMESERVERS)) { - const char *const nameserver = NEXT_TOKEN; - - if (nameserver) - evdns_base_nameserver_ip_add(base, nameserver); - } else if (!strcmp(first_token, "domain") && (flags & DNS_OPTION_SEARCH)) { - const char *const domain = NEXT_TOKEN; - if (domain) { - search_postfix_clear(base); - search_postfix_add(base, domain); - } - } else if (!strcmp(first_token, "search") && (flags & DNS_OPTION_SEARCH)) { - const char *domain; - search_postfix_clear(base); - - while ((domain = NEXT_TOKEN)) { - search_postfix_add(base, domain); - } - search_reverse(base); - } else if (!strcmp(first_token, "options")) { - const char *option; - while ((option = NEXT_TOKEN)) { - const char *val = strchr(option, ':'); - evdns_base_set_option_impl(base, 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_base_resolv_conf_parse(struct evdns_base *base, int flags, const char *const filename) { - int res; - EVDNS_LOCK(base); - res = evdns_base_resolv_conf_parse_impl(base, flags, filename); - EVDNS_UNLOCK(base); - return res; -} - -static char * -evdns_get_default_hosts_filename(void) -{ -#ifdef _WIN32 - /* Windows is a little coy about where it puts its configuration - * files. Sure, they're _usually_ in C:\windows\system32, but - * there's no reason in principle they couldn't be in - * W:\hoboken chicken emergency\ - */ - char path[MAX_PATH+1]; - static const char hostfile[] = "\\drivers\\etc\\hosts"; - char *path_out; - size_t len_out; - - if (! SHGetSpecialFolderPathA(NULL, path, CSIDL_SYSTEM, 0)) - return NULL; - len_out = strlen(path)+strlen(hostfile)+1; - path_out = mm_malloc(len_out); - evutil_snprintf(path_out, len_out, "%s%s", path, hostfile); - return path_out; -#else - return mm_strdup("/etc/hosts"); -#endif -} - -static int -evdns_base_resolv_conf_parse_impl(struct evdns_base *base, int flags, const char *const filename) { - size_t n; - char *resolv; - char *start; - int err = 0; - - log(EVDNS_LOG_DEBUG, "Parsing resolv.conf file %s", filename); - - if (flags & DNS_OPTION_HOSTSFILE) { - char *fname = evdns_get_default_hosts_filename(); - evdns_base_load_hosts(base, fname); - if (fname) - mm_free(fname); - } - - if ((err = evutil_read_file_(filename, &resolv, &n, 0)) < 0) { - if (err == -1) { - /* No file. */ - evdns_resolv_set_defaults(base, flags); - return 1; - } else { - return 2; - } - } - - start = resolv; - for (;;) { - char *const newline = strchr(start, '\n'); - if (!newline) { - resolv_conf_parse_line(base, start, flags); - break; - } else { - *newline = 0; - resolv_conf_parse_line(base, start, flags); - start = newline + 1; - } - } - - if (!base->server_head && (flags & DNS_OPTION_NAMESERVERS)) { - /* no nameservers were configured. */ - evdns_base_nameserver_ip_add(base, "127.0.0.1"); - err = 6; - } - if (flags & DNS_OPTION_SEARCH && (!base->global_search_state || base->global_search_state->num_domains == 0)) { - search_set_from_hostname(base); - } - - mm_free(resolv); - return err; -} - -int -evdns_resolv_conf_parse(int flags, const char *const filename) { - if (!current_base) - current_base = evdns_base_new(NULL, 0); - return evdns_base_resolv_conf_parse(current_base, flags, filename); -} - - -#ifdef _WIN32 -/* Add multiple nameservers from a space-or-comma-separated list. */ -static int -evdns_nameserver_ip_add_line(struct evdns_base *base, const char *ips) { - const char *addr; - char *buf; - int r; - ASSERT_LOCKED(base); - while (*ips) { - while (isspace(*ips) || *ips == ',' || *ips == '\t') - ++ips; - addr = ips; - while (isdigit(*ips) || *ips == '.' || *ips == ':' || - *ips=='[' || *ips==']') - ++ips; - buf = mm_malloc(ips-addr+1); - if (!buf) return 4; - memcpy(buf, addr, ips-addr); - buf[ips-addr] = '\0'; - r = evdns_base_nameserver_ip_add(base, buf); - mm_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(struct evdns_base *base) -{ - /* 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; - - ASSERT_LOCKED(base); - if (!(handle = evutil_load_windows_system_library_( - TEXT("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 = mm_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) { - mm_free(buf); - buf = mm_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; - } - } - - EVUTIL_ASSERT(fixed); - added_any = 0; - ns = &(fixed->DnsServerList); - while (ns) { - r = evdns_nameserver_ip_add_line(base, 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; - } else { - ++added_any; - log(EVDNS_LOG_DEBUG,"Successfully added %s as nameserver",ns->IpAddress.String); - } - - ns = ns->Next; - } - - if (!added_any) { - log(EVDNS_LOG_DEBUG, "No nameservers added."); - if (status == 0) - status = -1; - } else { - status = 0; - } - - done: - if (buf) - mm_free(buf); - if (handle) - FreeLibrary(handle); - return status; -} - -static int -config_nameserver_from_reg_key(struct evdns_base *base, HKEY key, const wchar_t *subkey) -{ - char *buf; - DWORD bufsz = 0, type = 0; - int status = 0; - - ASSERT_LOCKED(base); - if (RegQueryValueEx(key, subkey, 0, &type, NULL, &bufsz) - != ERROR_MORE_DATA) - return -1; - if (!(buf = mm_malloc(bufsz))) - return -1; - - if (RegQueryValueEx(key, subkey, 0, &type, (LPBYTE)buf, &bufsz) - == ERROR_SUCCESS && bufsz > 1) { - status = evdns_nameserver_ip_add_line(base,buf); - } - - mm_free(buf); - return status; -} - -#define SERVICES_KEY TEXT("System\\CurrentControlSet\\Services\\") -#define WIN_NS_9X_KEY SERVICES_KEY TEXT("VxD\\MSTCP") -#define WIN_NS_NT_KEY SERVICES_KEY TEXT("Tcpip\\Parameters") - -static int -load_nameservers_from_registry(struct evdns_base *base) -{ - int found = 0; - int r; -#define TRY(k, name) \ - if (!found && config_nameserver_from_reg_key(base,k,TEXT(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); \ - } - - ASSERT_LOCKED(base); - - 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, TEXT("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_base_config_windows_nameservers(struct evdns_base *base) -{ - int r; - char *fname; - if (base == NULL) - base = current_base; - if (base == NULL) - return -1; - EVDNS_LOCK(base); - fname = evdns_get_default_hosts_filename(); - log(EVDNS_LOG_DEBUG, "Loading hosts entries from %s", fname); - evdns_base_load_hosts(base, fname); - if (fname) - mm_free(fname); - - if (load_nameservers_with_getnetworkparams(base) == 0) { - EVDNS_UNLOCK(base); - return 0; - } - r = load_nameservers_from_registry(base); - - EVDNS_UNLOCK(base); - return r; -} - -int -evdns_config_windows_nameservers(void) -{ - if (!current_base) { - current_base = evdns_base_new(NULL, 1); - return current_base == NULL ? -1 : 0; - } else { - return evdns_base_config_windows_nameservers(current_base); - } -} -#endif - -struct evdns_base * -evdns_base_new(struct event_base *event_base, int flags) -{ - struct evdns_base *base; - - if (evutil_secure_rng_init() < 0) { - log(EVDNS_LOG_WARN, "Unable to seed random number generator; " - "DNS can't run."); - return NULL; - } - - /* Give the evutil library a hook into its evdns-enabled - * functionality. We can't just call evdns_getaddrinfo directly or - * else libevent-core will depend on libevent-extras. */ - evutil_set_evdns_getaddrinfo_fn_(evdns_getaddrinfo); - - base = mm_malloc(sizeof(struct evdns_base)); - if (base == NULL) - return (NULL); - memset(base, 0, sizeof(struct evdns_base)); - base->req_waiting_head = NULL; - - EVTHREAD_ALLOC_LOCK(base->lock, EVTHREAD_LOCKTYPE_RECURSIVE); - EVDNS_LOCK(base); - - /* Set max requests inflight and allocate req_heads. */ - base->req_heads = NULL; - - evdns_base_set_max_requests_inflight(base, 64); - - base->server_head = NULL; - base->event_base = event_base; - base->global_good_nameservers = base->global_requests_inflight = - base->global_requests_waiting = 0; - - base->global_timeout.tv_sec = 5; - base->global_timeout.tv_usec = 0; - base->global_max_reissues = 1; - base->global_max_retransmits = 3; - base->global_max_nameserver_timeout = 3; - base->global_search_state = NULL; - base->global_randomize_case = 1; - base->global_getaddrinfo_allow_skew.tv_sec = 3; - base->global_getaddrinfo_allow_skew.tv_usec = 0; - base->global_nameserver_probe_initial_timeout.tv_sec = 10; - base->global_nameserver_probe_initial_timeout.tv_usec = 0; - - TAILQ_INIT(&base->hostsdb); - -#define EVDNS_BASE_ALL_FLAGS (0x8001) - if (flags & ~EVDNS_BASE_ALL_FLAGS) { - flags = EVDNS_BASE_INITIALIZE_NAMESERVERS; - log(EVDNS_LOG_WARN, - "Unrecognized flag passed to evdns_base_new(). Assuming " - "you meant EVDNS_BASE_INITIALIZE_NAMESERVERS."); - } -#undef EVDNS_BASE_ALL_FLAGS - - if (flags & EVDNS_BASE_INITIALIZE_NAMESERVERS) { - int r; -#ifdef _WIN32 - r = evdns_base_config_windows_nameservers(base); -#else - r = evdns_base_resolv_conf_parse(base, DNS_OPTIONS_ALL, "/etc/resolv.conf"); -#endif - if (r == -1) { - evdns_base_free_and_unlock(base, 0); - return NULL; - } - } - if (flags & EVDNS_BASE_DISABLE_WHEN_INACTIVE) { - base->disable_when_inactive = 1; - } - - EVDNS_UNLOCK(base); - return base; -} - -int -evdns_init(void) -{ - struct evdns_base *base = evdns_base_new(NULL, 1); - if (base) { - current_base = base; - return 0; - } else { - return -1; - } -} - -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"; - case DNS_ERR_CANCEL: return "dns request canceled"; - case DNS_ERR_NODATA: return "no records in the reply"; - default: return "[Unknown error code]"; - } -} - -static void -evdns_nameserver_free(struct nameserver *server) -{ - if (server->socket >= 0) - evutil_closesocket(server->socket); - (void) event_del(&server->event); - event_debug_unassign(&server->event); - if (server->state == 0) - (void) event_del(&server->timeout_event); - if (server->probe_request) { - evdns_cancel_request(server->base, server->probe_request); - server->probe_request = NULL; - } - event_debug_unassign(&server->timeout_event); - mm_free(server); -} - -static void -evdns_base_free_and_unlock(struct evdns_base *base, int fail_requests) -{ - struct nameserver *server, *server_next; - struct search_domain *dom, *dom_next; - int i; - - /* Requires that we hold the lock. */ - - /* TODO(nickm) we might need to refcount here. */ - - for (i = 0; i < base->n_req_heads; ++i) { - while (base->req_heads[i]) { - if (fail_requests) - reply_schedule_callback(base->req_heads[i], 0, DNS_ERR_SHUTDOWN, NULL); - request_finished(base->req_heads[i], &REQ_HEAD(base, base->req_heads[i]->trans_id), 1); - } - } - while (base->req_waiting_head) { - if (fail_requests) - reply_schedule_callback(base->req_waiting_head, 0, DNS_ERR_SHUTDOWN, NULL); - request_finished(base->req_waiting_head, &base->req_waiting_head, 1); - } - base->global_requests_inflight = base->global_requests_waiting = 0; - - for (server = base->server_head; server; server = server_next) { - server_next = server->next; - evdns_nameserver_free(server); - if (server_next == base->server_head) - break; - } - base->server_head = NULL; - base->global_good_nameservers = 0; - - if (base->global_search_state) { - for (dom = base->global_search_state->head; dom; dom = dom_next) { - dom_next = dom->next; - mm_free(dom); - } - mm_free(base->global_search_state); - base->global_search_state = NULL; - } - - { - struct hosts_entry *victim; - while ((victim = TAILQ_FIRST(&base->hostsdb))) { - TAILQ_REMOVE(&base->hostsdb, victim, next); - mm_free(victim); - } - } - - mm_free(base->req_heads); - - EVDNS_UNLOCK(base); - EVTHREAD_FREE_LOCK(base->lock, EVTHREAD_LOCKTYPE_RECURSIVE); - - mm_free(base); -} - -void -evdns_base_free(struct evdns_base *base, int fail_requests) -{ - EVDNS_LOCK(base); - evdns_base_free_and_unlock(base, fail_requests); -} - -void -evdns_base_clear_host_addresses(struct evdns_base *base) -{ - struct hosts_entry *victim; - EVDNS_LOCK(base); - while ((victim = TAILQ_FIRST(&base->hostsdb))) { - TAILQ_REMOVE(&base->hostsdb, victim, next); - mm_free(victim); - } - EVDNS_UNLOCK(base); -} - -void -evdns_shutdown(int fail_requests) -{ - if (current_base) { - struct evdns_base *b = current_base; - current_base = NULL; - evdns_base_free(b, fail_requests); - } - evdns_log_fn = NULL; -} - -static int -evdns_base_parse_hosts_line(struct evdns_base *base, char *line) -{ - char *strtok_state; - static const char *const delims = " \t"; - char *const addr = strtok_r(line, delims, &strtok_state); - char *hostname, *hash; - struct sockaddr_storage ss; - int socklen = sizeof(ss); - ASSERT_LOCKED(base); - -#define NEXT_TOKEN strtok_r(NULL, delims, &strtok_state) - - if (!addr || *addr == '#') - return 0; - - memset(&ss, 0, sizeof(ss)); - if (evutil_parse_sockaddr_port(addr, (struct sockaddr*)&ss, &socklen)<0) - return -1; - if (socklen > (int)sizeof(struct sockaddr_in6)) - return -1; - - if (sockaddr_getport((struct sockaddr*)&ss)) - return -1; - - while ((hostname = NEXT_TOKEN)) { - struct hosts_entry *he; - size_t namelen; - if ((hash = strchr(hostname, '#'))) { - if (hash == hostname) - return 0; - *hash = '\0'; - } - - namelen = strlen(hostname); - - he = mm_calloc(1, sizeof(struct hosts_entry)+namelen); - if (!he) - return -1; - EVUTIL_ASSERT(socklen <= (int)sizeof(he->addr)); - memcpy(&he->addr, &ss, socklen); - memcpy(he->hostname, hostname, namelen+1); - he->addrlen = socklen; - - TAILQ_INSERT_TAIL(&base->hostsdb, he, next); - - if (hash) - return 0; - } - - return 0; -#undef NEXT_TOKEN -} - -static int -evdns_base_load_hosts_impl(struct evdns_base *base, const char *hosts_fname) -{ - char *str=NULL, *cp, *eol; - size_t len; - int err=0; - - ASSERT_LOCKED(base); - - if (hosts_fname == NULL || - (err = evutil_read_file_(hosts_fname, &str, &len, 0)) < 0) { - char tmp[64]; - strlcpy(tmp, "127.0.0.1 localhost", sizeof(tmp)); - evdns_base_parse_hosts_line(base, tmp); - strlcpy(tmp, "::1 localhost", sizeof(tmp)); - evdns_base_parse_hosts_line(base, tmp); - return err ? -1 : 0; - } - - /* This will break early if there is a NUL in the hosts file. - * Probably not a problem.*/ - cp = str; - for (;;) { - eol = strchr(cp, '\n'); - - if (eol) { - *eol = '\0'; - evdns_base_parse_hosts_line(base, cp); - cp = eol+1; - } else { - evdns_base_parse_hosts_line(base, cp); - break; - } - } - - mm_free(str); - return 0; -} - -int -evdns_base_load_hosts(struct evdns_base *base, const char *hosts_fname) -{ - int res; - if (!base) - base = current_base; - EVDNS_LOCK(base); - res = evdns_base_load_hosts_impl(base, hosts_fname); - EVDNS_UNLOCK(base); - return res; -} - -/* A single request for a getaddrinfo, either v4 or v6. */ -struct getaddrinfo_subrequest { - struct evdns_request *r; - ev_uint32_t type; -}; - -/* State data used to implement an in-progress getaddrinfo. */ -struct evdns_getaddrinfo_request { - struct evdns_base *evdns_base; - /* Copy of the modified 'hints' data that we'll use to build - * answers. */ - struct evutil_addrinfo hints; - /* The callback to invoke when we're done */ - evdns_getaddrinfo_cb user_cb; - /* User-supplied data to give to the callback. */ - void *user_data; - /* The port to use when building sockaddrs. */ - ev_uint16_t port; - /* The sub_request for an A record (if any) */ - struct getaddrinfo_subrequest ipv4_request; - /* The sub_request for an AAAA record (if any) */ - struct getaddrinfo_subrequest ipv6_request; - - /* The cname result that we were told (if any) */ - char *cname_result; - - /* If we have one request answered and one request still inflight, - * then this field holds the answer from the first request... */ - struct evutil_addrinfo *pending_result; - /* And this event is a timeout that will tell us to cancel the second - * request if it's taking a long time. */ - struct event timeout; - - /* And this field holds the error code from the first request... */ - int pending_error; - /* If this is set, the user canceled this request. */ - unsigned user_canceled : 1; - /* If this is set, the user can no longer cancel this request; we're - * just waiting for the free. */ - unsigned request_done : 1; -}; - -/* Convert an evdns errors to the equivalent getaddrinfo error. */ -static int -evdns_err_to_getaddrinfo_err(int e1) -{ - /* XXX Do this better! */ - if (e1 == DNS_ERR_NONE) - return 0; - else if (e1 == DNS_ERR_NOTEXIST) - return EVUTIL_EAI_NONAME; - else - return EVUTIL_EAI_FAIL; -} - -/* Return the more informative of two getaddrinfo errors. */ -static int -getaddrinfo_merge_err(int e1, int e2) -{ - /* XXXX be cleverer here. */ - if (e1 == 0) - return e2; - else - return e1; -} - -static void -free_getaddrinfo_request(struct evdns_getaddrinfo_request *data) -{ - /* DO NOT CALL this if either of the requests is pending. Only once - * both callbacks have been invoked is it safe to free the request */ - if (data->pending_result) - evutil_freeaddrinfo(data->pending_result); - if (data->cname_result) - mm_free(data->cname_result); - event_del(&data->timeout); - mm_free(data); - return; -} - -static void -add_cname_to_reply(struct evdns_getaddrinfo_request *data, - struct evutil_addrinfo *ai) -{ - if (data->cname_result && ai) { - ai->ai_canonname = data->cname_result; - data->cname_result = NULL; - } -} - -/* Callback: invoked when one request in a mixed-format A/AAAA getaddrinfo - * request has finished, but the other one took too long to answer. Pass - * along the answer we got, and cancel the other request. - */ -static void -evdns_getaddrinfo_timeout_cb(evutil_socket_t fd, short what, void *ptr) -{ - int v4_timedout = 0, v6_timedout = 0; - struct evdns_getaddrinfo_request *data = ptr; - - /* Cancel any pending requests, and note which one */ - if (data->ipv4_request.r) { - /* XXXX This does nothing if the request's callback is already - * running (pending_cb is set). */ - evdns_cancel_request(NULL, data->ipv4_request.r); - v4_timedout = 1; - EVDNS_LOCK(data->evdns_base); - ++data->evdns_base->getaddrinfo_ipv4_timeouts; - EVDNS_UNLOCK(data->evdns_base); - } - if (data->ipv6_request.r) { - /* XXXX This does nothing if the request's callback is already - * running (pending_cb is set). */ - evdns_cancel_request(NULL, data->ipv6_request.r); - v6_timedout = 1; - EVDNS_LOCK(data->evdns_base); - ++data->evdns_base->getaddrinfo_ipv6_timeouts; - EVDNS_UNLOCK(data->evdns_base); - } - - /* We only use this timeout callback when we have an answer for - * one address. */ - EVUTIL_ASSERT(!v4_timedout || !v6_timedout); - - /* Report the outcome of the other request that didn't time out. */ - if (data->pending_result) { - add_cname_to_reply(data, data->pending_result); - data->user_cb(0, data->pending_result, data->user_data); - data->pending_result = NULL; - } else { - int e = data->pending_error; - if (!e) - e = EVUTIL_EAI_AGAIN; - data->user_cb(e, NULL, data->user_data); - } - - data->user_cb = NULL; /* prevent double-call if evdns callbacks are - * in-progress. XXXX It would be better if this - * weren't necessary. */ - - if (!v4_timedout && !v6_timedout) { - /* should be impossible? XXXX */ - free_getaddrinfo_request(data); - } -} - -static int -evdns_getaddrinfo_set_timeout(struct evdns_base *evdns_base, - struct evdns_getaddrinfo_request *data) -{ - return event_add(&data->timeout, &evdns_base->global_getaddrinfo_allow_skew); -} - -static inline int -evdns_result_is_answer(int result) -{ - return (result != DNS_ERR_NOTIMPL && result != DNS_ERR_REFUSED && - result != DNS_ERR_SERVERFAILED && result != DNS_ERR_CANCEL); -} - -static void -evdns_getaddrinfo_gotresolve(int result, char type, int count, - int ttl, void *addresses, void *arg) -{ - int i; - struct getaddrinfo_subrequest *req = arg; - struct getaddrinfo_subrequest *other_req; - struct evdns_getaddrinfo_request *data; - - struct evutil_addrinfo *res; - - struct sockaddr_in sin; - struct sockaddr_in6 sin6; - struct sockaddr *sa; - int socklen, addrlen; - void *addrp; - int err; - int user_canceled; - - EVUTIL_ASSERT(req->type == DNS_IPv4_A || req->type == DNS_IPv6_AAAA); - if (req->type == DNS_IPv4_A) { - data = EVUTIL_UPCAST(req, struct evdns_getaddrinfo_request, ipv4_request); - other_req = &data->ipv6_request; - } else { - data = EVUTIL_UPCAST(req, struct evdns_getaddrinfo_request, ipv6_request); - other_req = &data->ipv4_request; - } - - /** Called from evdns_base_free() with @fail_requests == 1 */ - if (result != DNS_ERR_SHUTDOWN) { - EVDNS_LOCK(data->evdns_base); - if (evdns_result_is_answer(result)) { - if (req->type == DNS_IPv4_A) - ++data->evdns_base->getaddrinfo_ipv4_answered; - else - ++data->evdns_base->getaddrinfo_ipv6_answered; - } - user_canceled = data->user_canceled; - if (other_req->r == NULL) - data->request_done = 1; - EVDNS_UNLOCK(data->evdns_base); - } else { - data->evdns_base = NULL; - user_canceled = data->user_canceled; - } - - req->r = NULL; - - if (result == DNS_ERR_CANCEL && ! user_canceled) { - /* Internal cancel request from timeout or internal error. - * we already answered the user. */ - if (other_req->r == NULL) - free_getaddrinfo_request(data); - return; - } - - if (data->user_cb == NULL) { - /* We already answered. XXXX This shouldn't be needed; see - * comments in evdns_getaddrinfo_timeout_cb */ - free_getaddrinfo_request(data); - return; - } - - if (result == DNS_ERR_NONE) { - if (count == 0) - err = EVUTIL_EAI_NODATA; - else - err = 0; - } else { - err = evdns_err_to_getaddrinfo_err(result); - } - - if (err) { - /* Looks like we got an error. */ - if (other_req->r) { - /* The other request is still working; maybe it will - * succeed. */ - /* XXXX handle failure from set_timeout */ - if (result != DNS_ERR_SHUTDOWN) { - evdns_getaddrinfo_set_timeout(data->evdns_base, data); - } - data->pending_error = err; - return; - } - - if (user_canceled) { - data->user_cb(EVUTIL_EAI_CANCEL, NULL, data->user_data); - } else if (data->pending_result) { - /* If we have an answer waiting, and we weren't - * canceled, ignore this error. */ - add_cname_to_reply(data, data->pending_result); - data->user_cb(0, data->pending_result, data->user_data); - data->pending_result = NULL; - } else { - if (data->pending_error) - err = getaddrinfo_merge_err(err, - data->pending_error); - data->user_cb(err, NULL, data->user_data); - } - free_getaddrinfo_request(data); - return; - } else if (user_canceled) { - if (other_req->r) { - /* The other request is still working; let it hit this - * callback with EVUTIL_EAI_CANCEL callback and report - * the failure. */ - return; - } - data->user_cb(EVUTIL_EAI_CANCEL, NULL, data->user_data); - free_getaddrinfo_request(data); - return; - } - - /* Looks like we got some answers. We should turn them into addrinfos - * and then either queue those or return them all. */ - EVUTIL_ASSERT(type == DNS_IPv4_A || type == DNS_IPv6_AAAA); - - if (type == DNS_IPv4_A) { - memset(&sin, 0, sizeof(sin)); - sin.sin_family = AF_INET; - sin.sin_port = htons(data->port); - - sa = (struct sockaddr *)&sin; - socklen = sizeof(sin); - addrlen = 4; - addrp = &sin.sin_addr.s_addr; - } else { - memset(&sin6, 0, sizeof(sin6)); - sin6.sin6_family = AF_INET6; - sin6.sin6_port = htons(data->port); - - sa = (struct sockaddr *)&sin6; - socklen = sizeof(sin6); - addrlen = 16; - addrp = &sin6.sin6_addr.s6_addr; - } - - res = NULL; - for (i=0; i < count; ++i) { - struct evutil_addrinfo *ai; - memcpy(addrp, ((char*)addresses)+i*addrlen, addrlen); - ai = evutil_new_addrinfo_(sa, socklen, &data->hints); - if (!ai) { - if (other_req->r) { - evdns_cancel_request(NULL, other_req->r); - } - data->user_cb(EVUTIL_EAI_MEMORY, NULL, data->user_data); - if (res) - evutil_freeaddrinfo(res); - - if (other_req->r == NULL) - free_getaddrinfo_request(data); - return; - } - res = evutil_addrinfo_append_(res, ai); - } - - if (other_req->r) { - /* The other request is still in progress; wait for it */ - /* XXXX handle failure from set_timeout */ - evdns_getaddrinfo_set_timeout(data->evdns_base, data); - data->pending_result = res; - return; - } else { - /* The other request is done or never started; append its - * results (if any) and return them. */ - if (data->pending_result) { - if (req->type == DNS_IPv4_A) - res = evutil_addrinfo_append_(res, - data->pending_result); - else - res = evutil_addrinfo_append_( - data->pending_result, res); - data->pending_result = NULL; - } - - /* Call the user callback. */ - add_cname_to_reply(data, res); - data->user_cb(0, res, data->user_data); - - /* Free data. */ - free_getaddrinfo_request(data); - } -} - -static struct hosts_entry * -find_hosts_entry(struct evdns_base *base, const char *hostname, - struct hosts_entry *find_after) -{ - struct hosts_entry *e; - - if (find_after) - e = TAILQ_NEXT(find_after, next); - else - e = TAILQ_FIRST(&base->hostsdb); - - for (; e; e = TAILQ_NEXT(e, next)) { - if (!evutil_ascii_strcasecmp(e->hostname, hostname)) - return e; - } - return NULL; -} - -static int -evdns_getaddrinfo_fromhosts(struct evdns_base *base, - const char *nodename, struct evutil_addrinfo *hints, ev_uint16_t port, - struct evutil_addrinfo **res) -{ - int n_found = 0; - struct hosts_entry *e; - struct evutil_addrinfo *ai=NULL; - int f = hints->ai_family; - - EVDNS_LOCK(base); - for (e = find_hosts_entry(base, nodename, NULL); e; - e = find_hosts_entry(base, nodename, e)) { - struct evutil_addrinfo *ai_new; - ++n_found; - if ((e->addr.sa.sa_family == AF_INET && f == PF_INET6) || - (e->addr.sa.sa_family == AF_INET6 && f == PF_INET)) - continue; - ai_new = evutil_new_addrinfo_(&e->addr.sa, e->addrlen, hints); - if (!ai_new) { - n_found = 0; - goto out; - } - sockaddr_setport(ai_new->ai_addr, port); - ai = evutil_addrinfo_append_(ai, ai_new); - } - EVDNS_UNLOCK(base); -out: - if (n_found) { - /* Note that we return an empty answer if we found entries for - * this hostname but none were of the right address type. */ - *res = ai; - return 0; - } else { - if (ai) - evutil_freeaddrinfo(ai); - return -1; - } -} - -struct evdns_getaddrinfo_request * -evdns_getaddrinfo(struct evdns_base *dns_base, - const char *nodename, const char *servname, - const struct evutil_addrinfo *hints_in, - evdns_getaddrinfo_cb cb, void *arg) -{ - struct evdns_getaddrinfo_request *data; - struct evutil_addrinfo hints; - struct evutil_addrinfo *res = NULL; - int err; - int port = 0; - int want_cname = 0; - - if (!dns_base) { - dns_base = current_base; - if (!dns_base) { - log(EVDNS_LOG_WARN, - "Call to getaddrinfo_async with no " - "evdns_base configured."); - cb(EVUTIL_EAI_FAIL, NULL, arg); /* ??? better error? */ - return NULL; - } - } - - /* If we _must_ answer this immediately, do so. */ - if ((hints_in && (hints_in->ai_flags & EVUTIL_AI_NUMERICHOST))) { - res = NULL; - err = evutil_getaddrinfo(nodename, servname, hints_in, &res); - cb(err, res, arg); - return NULL; - } - - if (hints_in) { - memcpy(&hints, hints_in, sizeof(hints)); - } else { - memset(&hints, 0, sizeof(hints)); - hints.ai_family = PF_UNSPEC; - } - - evutil_adjust_hints_for_addrconfig_(&hints); - - /* Now try to see if we _can_ answer immediately. */ - /* (It would be nice to do this by calling getaddrinfo directly, with - * AI_NUMERICHOST, on plaforms that have it, but we can't: there isn't - * a reliable way to distinguish the "that wasn't a numeric host!" case - * from any other EAI_NONAME cases.) */ - err = evutil_getaddrinfo_common_(nodename, servname, &hints, &res, &port); - if (err != EVUTIL_EAI_NEED_RESOLVE) { - cb(err, res, arg); - return NULL; - } - - /* If there is an entry in the hosts file, we should give it now. */ - if (!evdns_getaddrinfo_fromhosts(dns_base, nodename, &hints, port, &res)) { - cb(0, res, arg); - return NULL; - } - - /* Okay, things are serious now. We're going to need to actually - * launch a request. - */ - data = mm_calloc(1,sizeof(struct evdns_getaddrinfo_request)); - if (!data) { - cb(EVUTIL_EAI_MEMORY, NULL, arg); - return NULL; - } - - memcpy(&data->hints, &hints, sizeof(data->hints)); - data->port = (ev_uint16_t)port; - data->ipv4_request.type = DNS_IPv4_A; - data->ipv6_request.type = DNS_IPv6_AAAA; - data->user_cb = cb; - data->user_data = arg; - data->evdns_base = dns_base; - - want_cname = (hints.ai_flags & EVUTIL_AI_CANONNAME); - - /* If we are asked for a PF_UNSPEC address, we launch two requests in - * parallel: one for an A address and one for an AAAA address. We - * can't send just one request, since many servers only answer one - * question per DNS request. - * - * Once we have the answer to one request, we allow for a short - * timeout before we report it, to see if the other one arrives. If - * they both show up in time, then we report both the answers. - * - * If too many addresses of one type time out or fail, we should stop - * launching those requests. (XXX we don't do that yet.) - */ - - if (hints.ai_family != PF_INET6) { - log(EVDNS_LOG_DEBUG, "Sending request for %s on ipv4 as %p", - nodename, &data->ipv4_request); - - data->ipv4_request.r = evdns_base_resolve_ipv4(dns_base, - nodename, 0, evdns_getaddrinfo_gotresolve, - &data->ipv4_request); - if (want_cname && data->ipv4_request.r) - data->ipv4_request.r->current_req->put_cname_in_ptr = - &data->cname_result; - } - if (hints.ai_family != PF_INET) { - log(EVDNS_LOG_DEBUG, "Sending request for %s on ipv6 as %p", - nodename, &data->ipv6_request); - - data->ipv6_request.r = evdns_base_resolve_ipv6(dns_base, - nodename, 0, evdns_getaddrinfo_gotresolve, - &data->ipv6_request); - if (want_cname && data->ipv6_request.r) - data->ipv6_request.r->current_req->put_cname_in_ptr = - &data->cname_result; - } - - evtimer_assign(&data->timeout, dns_base->event_base, - evdns_getaddrinfo_timeout_cb, data); - - if (data->ipv4_request.r || data->ipv6_request.r) { - return data; - } else { - mm_free(data); - cb(EVUTIL_EAI_FAIL, NULL, arg); - return NULL; - } -} - -void -evdns_getaddrinfo_cancel(struct evdns_getaddrinfo_request *data) -{ - EVDNS_LOCK(data->evdns_base); - if (data->request_done) { - EVDNS_UNLOCK(data->evdns_base); - return; - } - event_del(&data->timeout); - data->user_canceled = 1; - if (data->ipv4_request.r) - evdns_cancel_request(data->evdns_base, data->ipv4_request.r); - if (data->ipv6_request.r) - evdns_cancel_request(data->evdns_base, data->ipv6_request.r); - EVDNS_UNLOCK(data->evdns_base); -} |