dighost.c

来自「非常好的dns解析软件」· C语言 代码 · 共 2,368 行 · 第 1/5 页

	}
	dns_name_format(lookup->name, store, sizeof(store));
	trying(store, lookup);
	INSIST(dns_name_isabsolute(lookup->name));

	isc_random_get(&id);
	lookup->sendmsg->id = (unsigned short)id & 0xFFFF;
	lookup->sendmsg->opcode = dns_opcode_query;
	lookup->msgcounter = 0;
	/*
	 * If this is a trace request, completely disallow recursion, since
	 * it's meaningless for traces.
	 */
	if (lookup->trace || (lookup->ns_search_only && !lookup->trace_root))
		lookup->recurse = ISC_FALSE;

	if (lookup->recurse &&
	    lookup->rdtype != dns_rdatatype_axfr &&
	    lookup->rdtype != dns_rdatatype_ixfr) {
		debug("recursive query");
		lookup->sendmsg->flags |= DNS_MESSAGEFLAG_RD;
	}

	/* XXX aaflag */
	if (lookup->aaonly) {
		debug("AA query");
		lookup->sendmsg->flags |= DNS_MESSAGEFLAG_AA;
	}

	if (lookup->adflag) {
		debug("AD query");
		lookup->sendmsg->flags |= DNS_MESSAGEFLAG_AD;
	}

	if (lookup->cdflag) {
		debug("CD query");
		lookup->sendmsg->flags |= DNS_MESSAGEFLAG_CD;
	}

	dns_message_addname(lookup->sendmsg, lookup->name,
			    DNS_SECTION_QUESTION);

	if (lookup->trace && lookup->trace_root) {
		lookup->qrdtype = lookup->rdtype;
		lookup->rdtype = dns_rdatatype_ns;
	}

	if ((lookup->rdtype == dns_rdatatype_axfr) ||
	    (lookup->rdtype == dns_rdatatype_ixfr)) {
		lookup->doing_xfr = ISC_TRUE;
		/*
		 * Force TCP mode if we're doing an xfr.
		 * XXX UDP ixfr's would be useful
		 */
		lookup->tcp_mode = ISC_TRUE;
	}

	add_question(lookup->sendmsg, lookup->name, lookup->rdclass,
		     lookup->rdtype);

	/* add_soa */
	if (lookup->rdtype == dns_rdatatype_ixfr)
		insert_soa(lookup);

	/* XXX Insist this? */
	lookup->tsigctx = NULL;
	lookup->querysig = NULL;
	if (key != NULL) {
		debug("initializing keys");
		result = dns_message_settsigkey(lookup->sendmsg, key);
		check_result(result, "dns_message_settsigkey");
	}

	lookup->sendspace = isc_mempool_get(commctx);
	if (lookup->sendspace == NULL)
		fatal("memory allocation failure");

	result = dns_compress_init(&cctx, -1, mctx);
	check_result(result, "dns_compress_init");

	debug("starting to render the message");
	isc_buffer_init(&lookup->renderbuf, lookup->sendspace, COMMSIZE);
	result = dns_message_renderbegin(lookup->sendmsg, &cctx,
					 &lookup->renderbuf);
	check_result(result, "dns_message_renderbegin");
	if (lookup->udpsize > 0 || lookup->dnssec || lookup->edns > -1) {
		if (lookup->udpsize == 0)
			lookup->udpsize = 4096;
		if (lookup->edns < 0)
			lookup->edns = 0;
		add_opt(lookup->sendmsg, lookup->udpsize,
			lookup->edns, lookup->dnssec);
	}

	result = dns_message_rendersection(lookup->sendmsg,
					   DNS_SECTION_QUESTION, 0);
	check_result(result, "dns_message_rendersection");
	result = dns_message_rendersection(lookup->sendmsg,
					   DNS_SECTION_AUTHORITY, 0);
	check_result(result, "dns_message_rendersection");
	result = dns_message_renderend(lookup->sendmsg);
	check_result(result, "dns_message_renderend");
	debug("done rendering");

	dns_compress_invalidate(&cctx);

	/*
	 * Force TCP mode if the request is larger than 512 bytes.
	 */
	if (isc_buffer_usedlength(&lookup->renderbuf) > 512)
		lookup->tcp_mode = ISC_TRUE;

	lookup->pending = ISC_FALSE;

	for (serv = ISC_LIST_HEAD(lookup->my_server_list);
	     serv != NULL;
	     serv = ISC_LIST_NEXT(serv, link)) {
		query = isc_mem_allocate(mctx, sizeof(dig_query_t));
		if (query == NULL)
			fatal("memory allocation failure in %s:%d",
			      __FILE__, __LINE__);
		debug("create query %p linked to lookup %p",
		       query, lookup);
		query->lookup = lookup;
		query->waiting_connect = ISC_FALSE;
		query->waiting_senddone = ISC_FALSE;
		query->pending_free = ISC_FALSE;
		query->recv_made = ISC_FALSE;
		query->first_pass = ISC_TRUE;
		query->first_soa_rcvd = ISC_FALSE;
		query->second_rr_rcvd = ISC_FALSE;
		query->first_repeat_rcvd = ISC_FALSE;
		query->warn_id = ISC_TRUE;
		query->first_rr_serial = 0;
		query->second_rr_serial = 0;
		query->servname = serv->servername;
		query->userarg = serv->userarg;
		query->rr_count = 0;
		query->msg_count = 0;
		query->byte_count = 0;
		ISC_LINK_INIT(query, link);
		ISC_LIST_INIT(query->recvlist);
		ISC_LIST_INIT(query->lengthlist);
		query->sock = NULL;
		query->recvspace = isc_mempool_get(commctx);
		if (query->recvspace == NULL)
			fatal("memory allocation failure");

		isc_buffer_init(&query->recvbuf, query->recvspace, COMMSIZE);
		isc_buffer_init(&query->lengthbuf, query->lengthspace, 2);
		isc_buffer_init(&query->slbuf, query->slspace, 2);
		query->sendbuf = lookup->renderbuf;

		ISC_LINK_INIT(query, link);
		ISC_LIST_ENQUEUE(lookup->q, query, link);
	}
	/* XXX qrflag, print_query, etc... */
	if (!ISC_LIST_EMPTY(lookup->q) && qr) {
		extrabytes = 0;
		printmessage(ISC_LIST_HEAD(lookup->q), lookup->sendmsg,
			     ISC_TRUE);
	}
}

/*%
 * Event handler for send completion.  Track send counter, and clear out
 * the query if the send was canceled.
 */
static void
send_done(isc_task_t *_task, isc_event_t *event) {
	isc_socketevent_t *sevent = (isc_socketevent_t *)event;
	isc_buffer_t *b = NULL;
	dig_query_t *query, *next;
	dig_lookup_t *l;

	REQUIRE(event->ev_type == ISC_SOCKEVENT_SENDDONE);

	UNUSED(_task);

	LOCK_LOOKUP;

	debug("send_done()");
	sendcount--;
	debug("sendcount=%d", sendcount);
	INSIST(sendcount >= 0);

	for  (b = ISC_LIST_HEAD(sevent->bufferlist);
	      b != NULL;
	      b = ISC_LIST_HEAD(sevent->bufferlist)) 
		ISC_LIST_DEQUEUE(sevent->bufferlist, b, link);

	query = event->ev_arg;
	query->waiting_senddone = ISC_FALSE;
	l = query->lookup;

	if (l->ns_search_only && !l->trace_root) {
		debug("sending next, since searching");
		next = ISC_LIST_NEXT(query, link);
		if (next != NULL)
			send_udp(next);
	}

	isc_event_free(&event);

	if (query->pending_free)
		isc_mem_free(mctx, query);

	check_if_done();
	UNLOCK_LOOKUP;
}

/*%
 * Cancel a lookup, sending isc_socket_cancel() requests to all outstanding
 * IO sockets.  The cancel handlers should take care of cleaning up the
 * query and lookup structures
 */
static void
cancel_lookup(dig_lookup_t *lookup) {
	dig_query_t *query, *next;

	debug("cancel_lookup()");
	query = ISC_LIST_HEAD(lookup->q);
	while (query != NULL) {
		next = ISC_LIST_NEXT(query, link);
		if (query->sock != NULL) {
			isc_socket_cancel(query->sock, global_task,
					  ISC_SOCKCANCEL_ALL);
			check_if_done();
		} else {
			clear_query(query);
		}
		query = next;
	}
	if (lookup->timer != NULL)
		isc_timer_detach(&lookup->timer);
	lookup->pending = ISC_FALSE;
	lookup->retries = 0;
}

static void
bringup_timer(dig_query_t *query, unsigned int default_timeout) {
	dig_lookup_t *l;
	unsigned int local_timeout;
	isc_result_t result;

	debug("bringup_timer()");
	/*
	 * If the timer already exists, that means we're calling this
	 * a second time (for a retry).  Don't need to recreate it,
	 * just reset it.
	 */
	l = query->lookup;
	if (ISC_LIST_NEXT(query, link) != NULL)
		local_timeout = SERVER_TIMEOUT;
	else {
		if (timeout == 0)
			local_timeout = default_timeout;
		else
			local_timeout = timeout;
	}
	debug("have local timeout of %d", local_timeout);
	isc_interval_set(&l->interval, local_timeout, 0);
	if (l->timer != NULL)
		isc_timer_detach(&l->timer);
	result = isc_timer_create(timermgr, isc_timertype_once, NULL,
				  &l->interval, global_task, connect_timeout,
				  l, &l->timer);
	check_result(result, "isc_timer_create");
}	

static void
connect_done(isc_task_t *task, isc_event_t *event);

/*%
 * Unlike send_udp, this can't be called multiple times with the same
 * query.  When we retry TCP, we requeue the whole lookup, which should
 * start anew.
 */
static void
send_tcp_connect(dig_query_t *query) {
	isc_result_t result;
	dig_query_t *next;
	dig_lookup_t *l;

	debug("send_tcp_connect(%p)", query);

	l = query->lookup;
	query->waiting_connect = ISC_TRUE;
	query->lookup->current_query = query;
	get_address(query->servname, port, &query->sockaddr);
	
	if (specified_source &&
	    (isc_sockaddr_pf(&query->sockaddr) !=
	     isc_sockaddr_pf(&bind_address))) {
		printf(";; Skipping server %s, incompatible "
		       "address family\n", query->servname);
		query->waiting_connect = ISC_FALSE;
		next = ISC_LIST_NEXT(query, link);
		l = query->lookup;
		clear_query(query);
		if (next == NULL) {
			printf(";; No acceptable nameservers\n");
			check_next_lookup(l);
			return;
		}
		send_tcp_connect(next);
		return;
	}
	INSIST(query->sock == NULL);
	result = isc_socket_create(socketmgr,
				   isc_sockaddr_pf(&query->sockaddr),
				   isc_sockettype_tcp, &query->sock);
	check_result(result, "isc_socket_create");
	sockcount++;
	debug("sockcount=%d", sockcount);
	if (specified_source)
		result = isc_socket_bind(query->sock, &bind_address);
	else {
		if ((isc_sockaddr_pf(&query->sockaddr) == AF_INET) &&
		    have_ipv4)
			isc_sockaddr_any(&bind_any);
		else
			isc_sockaddr_any6(&bind_any);
		result = isc_socket_bind(query->sock, &bind_any);
	}
	check_result(result, "isc_socket_bind");
	bringup_timer(query, TCP_TIMEOUT);
	result = isc_socket_connect(query->sock, &query->sockaddr,
				    global_task, connect_done, query);
	check_result(result, "isc_socket_connect");
	/*
	 * If we're at the endgame of a nameserver search, we need to
	 * immediately bring up all the queries.  Do it here.
	 */
	if (l->ns_search_only && !l->trace_root) {
		debug("sending next, since searching");
		next = ISC_LIST_NEXT(query, link);
		if (next != NULL)
			send_tcp_connect(next);
	}
}

/*%
 * Send a UDP packet to the remote nameserver, possible starting the
 * recv action as well.  Also make sure that the timer is running and
 * is properly reset.
 */
static void
send_udp(dig_query_t *query) {
	dig_lookup_t *l = NULL;
	isc_result_t result;

	debug("send_udp(%p)", query);

	l = query->lookup;
	bringup_timer(query, UDP_TIMEOUT);
	l->current_query = query;
	debug("working on lookup %p, query %p", query->lookup, query);
	if (!query->recv_made) {
		/* XXX Check the sense of this, need assertion? */
		query->waiting_connect = ISC_FALSE;
		get_address(query->servname, port, &query->sockaddr);

		result = isc_socket_create(socketmgr,
					   isc_sockaddr_pf(&query->sockaddr),
					   isc_sockettype_udp, &query->sock);
		check_result(result, "isc_socket_create");
		sockcount++;
		debug("sockcount=%d", sockcount);
		if (specified_source) {
			result = isc_socket_bind(query->sock, &bind_address);
		} else {
			isc_sockaddr_anyofpf(&bind_any,
					isc_sockaddr_pf(&query->sockaddr));
			result = isc_socket_bind(query->sock, &bind_any);
		}
		check_result(result, "isc_socket_bind");

		query->recv_made = ISC_TRUE;
		ISC_LINK_INIT(&query->recvbuf, link);
		ISC_LIST_ENQUEUE(query->recvlist, &query->recvbuf,
				 link);
		debug("recving with lookup=%p, query=%p, sock=%p",
		      query->lookup, query, query->sock);
		result = isc_socket_recvv(query->sock, &query->recvlist, 1,
					  global_task, recv_done, query);
		check_result(result, "isc_socket_recvv");
		recvcount++;
		debug("recvcount=%d", recvcount);
	}
	ISC_LIST_INIT(query->sendlist);
	ISC_LIST_ENQUEUE(query->sendlist, &query->sendbuf, link);
	debug("sending a request");
	TIME_NOW(&query->time_sent);
	INSIST(query->sock != NULL);
	query->waiting_senddone = ISC_TRUE;
	result = isc_socket_sendtov(query->sock, &query->sendlist,
				    global_task, send_done, query,
				    &query->sockaddr, NULL);
	check_result(result, "isc_socket_sendtov");
	sendcount++;
}

/*%
 * IO timeout handler, used for both connect and recv timeouts.  If
 * retries are still allowed, either resend the UDP packet or queue a
 * new TCP lookup.  Otherwise, cancel the lookup.
 */
static void
connect_timeout(isc_task_t *task, isc_event_t *event) {
	dig_lookup_t *l = NULL;
	dig_query_t *query = NULL, *cq;

	UNUSED(task);
	REQUIRE(event->ev_type == ISC_TIMEREVENT_IDLE);

	debug("connect_timeout()");

	LOCK_LOOKUP;
	l = event->ev_arg;
	query = l->current_query;
	isc_event_free(&event);

	INSIST(!free_now);

	if ((query != NULL) && (query->lookup->current_query != NULL) &&
	    (ISC_LIST_NEXT(query->lookup->current_query, link) != NULL)) {
		debug("trying next server...");
		cq = query->lookup->current_query;
		if (!l->tcp_mode)
			send_udp(ISC_LIST_NEXT(cq, link));
		else
			send_tcp_connect(ISC_LIST_NEXT(cq, link));
		UNLOCK_LOOKUP;
		return;
	}

	if (l->retries > 1) {
		if (!l->tcp_mode) {
			l->retries--;
			debug("resending UDP request to first server");
			send_udp(ISC_LIST_HEAD(l->q));
		} else {
			debug("making new TCP request, %d tries left",
			      l->retries);
			l->retries--;
			requeue_lookup(l, ISC_TRUE);
			cancel_lookup(l);
			check_next_lookup(l);
		}
	} else {
		fputs(l->cmdline, stdout);
		printf(";; connection timed out; no servers could be "
		       "reached\n");
		cancel_lookup(l);
		check_next_lookup(l);
		if (exitcode < 9)
			exitcode = 9;
	}
	UNLOCK_LOOKUP;
}

/*%
 * Event handler for the TCP recv which gets the length header of TCP
 * packets.  Start the next recv of length bytes.
 */
static void
tcp_length_done(isc_task_t *task, isc_event_t *event) {
	isc_socketevent_t *sevent;
	isc_buffer_t *b = NULL;
	isc_result_t result;
	dig_query_t *que