client.c

来自「非常好的dns解析软件」· C语言 代码 · 共 2,439 行 · 第 1/5 页

	}

	client->message->rcode = dns_rcode_noerror;

	/* RFC1123 section 6.1.3.2 */
	if ((client->attributes & NS_CLIENTATTR_MULTICAST) != 0)
		client->message->flags &= ~DNS_MESSAGEFLAG_RD;

	/*
	 * Deal with EDNS.
	 */
	opt = dns_message_getopt(client->message);
	if (opt != NULL) {
		/*
		 * Set the client's UDP buffer size.
		 */
		client->udpsize = opt->rdclass;

		/*
		 * If the requested UDP buffer size is less than 512,
		 * ignore it and use 512.
		 */
		if (client->udpsize < 512)
			client->udpsize = 512;

		/*
		 * Get the flags out of the OPT record.
		 */
		client->extflags = (isc_uint16_t)(opt->ttl & 0xFFFF);

		/*
		 * Do we understand this version of EDNS?
		 *
		 * XXXRTH need library support for this!
		 */
		client->ednsversion = (opt->ttl & 0x00FF0000) >> 16;
		if (client->ednsversion > 0) {
			result = client_addopt(client);
			if (result == ISC_R_SUCCESS)
				result = DNS_R_BADVERS;
			ns_client_error(client, result);
			goto cleanup;
		}
		/*
		 * Create an OPT for our reply.
		 */
		result = client_addopt(client);
		if (result != ISC_R_SUCCESS) {
			ns_client_error(client, result);
			goto cleanup;
		}
	}

	if (client->message->rdclass == 0) {
		ns_client_log(client, NS_LOGCATEGORY_CLIENT,
			      NS_LOGMODULE_CLIENT, ISC_LOG_DEBUG(1),
			      "message class could not be determined");
		ns_client_dumpmessage(client,
				      "message class could not be determined");
		ns_client_error(client, notimp ? DNS_R_NOTIMP : DNS_R_FORMERR);
		goto cleanup;
	}

	/*
	 * Determine the destination address.  If the receiving interface is
	 * bound to a specific address, we simply use it regardless of the
	 * address family.  All IPv4 queries should fall into this case.
	 * Otherwise, if this is a TCP query, get the address from the
	 * receiving socket (this needs a system call and can be heavy).
	 * For IPv6 UDP queries, we get this from the pktinfo structure (if
	 * supported).
	 * If all the attempts fail (this can happen due to memory shortage,
	 * etc), we regard this as an error for safety. 
	 */
	if ((client->interface->flags & NS_INTERFACEFLAG_ANYADDR) == 0)
		isc_netaddr_fromsockaddr(&destaddr, &client->interface->addr);
	else {
		result = ISC_R_FAILURE;

		if (TCP_CLIENT(client)) {
			isc_sockaddr_t destsockaddr;

			result = isc_socket_getsockname(client->tcpsocket,
							&destsockaddr);
			if (result == ISC_R_SUCCESS)
				isc_netaddr_fromsockaddr(&destaddr,
							 &destsockaddr);
		}
		if (result != ISC_R_SUCCESS &&
		    client->interface->addr.type.sa.sa_family == AF_INET6 &&
		    (client->attributes & NS_CLIENTATTR_PKTINFO) != 0) {
			isc_uint32_t zone = 0;

			/*
			 * XXXJT technically, we should convert the receiving
			 * interface ID to a proper scope zone ID.  However,
			 * due to the fact there is no standard API for this,
			 * we only handle link-local addresses and use the
			 * interface index as link ID.  Despite the assumption,
			 * it should cover most typical cases.
			 */
			if (IN6_IS_ADDR_LINKLOCAL(&client->pktinfo.ipi6_addr))
				zone = (isc_uint32_t)client->pktinfo.ipi6_ifindex;

			isc_netaddr_fromin6(&destaddr,
					    &client->pktinfo.ipi6_addr);
			isc_netaddr_setzone(&destaddr, zone);
			result = ISC_R_SUCCESS;
		}
		if (result != ISC_R_SUCCESS) {
			UNEXPECTED_ERROR(__FILE__, __LINE__,
					 "failed to get request's "
					 "destination: %s",
					 isc_result_totext(result));
			goto cleanup;
		}
	}

	/*
	 * Find a view that matches the client's source address.
	 */
	for (view = ISC_LIST_HEAD(ns_g_server->viewlist);
	     view != NULL;
	     view = ISC_LIST_NEXT(view, link)) {
		if (client->message->rdclass == view->rdclass ||
		    client->message->rdclass == dns_rdataclass_any)
		{
			dns_name_t *tsig = NULL;
			sigresult = dns_message_rechecksig(client->message,
							   view);
			if (sigresult == ISC_R_SUCCESS)
				tsig = client->message->tsigname;
				
			if (allowed(&netaddr, tsig, view->matchclients) &&
			    allowed(&destaddr, tsig, view->matchdestinations) &&
			    !((client->message->flags & DNS_MESSAGEFLAG_RD)
			      == 0 && view->matchrecursiveonly))
			{
				dns_view_attach(view, &client->view);
				break;
			}
		}
	}

	if (view == NULL) {
		char classname[DNS_RDATACLASS_FORMATSIZE];

		/*
		 * Do a dummy TSIG verification attempt so that the
		 * response will have a TSIG if the query did, as
		 * required by RFC2845.
		 */
		isc_buffer_t b;
		isc_region_t *r;

		dns_message_resetsig(client->message);

		r = dns_message_getrawmessage(client->message);
		isc_buffer_init(&b, r->base, r->length);
		isc_buffer_add(&b, r->length);
		(void)dns_tsig_verify(&b, client->message, NULL, NULL);

		dns_rdataclass_format(client->message->rdclass, classname,
				      sizeof(classname));
		ns_client_log(client, NS_LOGCATEGORY_CLIENT,
			      NS_LOGMODULE_CLIENT, ISC_LOG_DEBUG(1),
			      "no matching view in class '%s'", classname);
		ns_client_dumpmessage(client, "no matching view in class");
		ns_client_error(client, notimp ? DNS_R_NOTIMP : DNS_R_REFUSED);
		goto cleanup;
	}

	ns_client_log(client, NS_LOGCATEGORY_CLIENT,
		      NS_LOGMODULE_CLIENT, ISC_LOG_DEBUG(5),
		      "using view '%s'", view->name);

	/*
	 * Check for a signature.  We log bad signatures regardless of
	 * whether they ultimately cause the request to be rejected or
	 * not.  We do not log the lack of a signature unless we are
	 * debugging.
	 */
	client->signer = NULL;
	dns_name_init(&client->signername, NULL);
	result = dns_message_signer(client->message, &client->signername);
	if (result == ISC_R_SUCCESS) {
		ns_client_log(client, DNS_LOGCATEGORY_SECURITY,
			      NS_LOGMODULE_CLIENT, ISC_LOG_DEBUG(3),
			      "request has valid signature");
		client->signer = &client->signername;
	} else if (result == ISC_R_NOTFOUND) {
		ns_client_log(client, DNS_LOGCATEGORY_SECURITY,
			      NS_LOGMODULE_CLIENT, ISC_LOG_DEBUG(3),
			      "request is not signed");
	} else if (result == DNS_R_NOIDENTITY) {
		ns_client_log(client, DNS_LOGCATEGORY_SECURITY,
			      NS_LOGMODULE_CLIENT, ISC_LOG_DEBUG(3),
			      "request is signed by a nonauthoritative key");
	} else {
		char tsigrcode[64];
		isc_buffer_t b;
		dns_name_t *name = NULL;

		isc_buffer_init(&b, tsigrcode, sizeof(tsigrcode) - 1);
		RUNTIME_CHECK(dns_tsigrcode_totext(client->message->tsigstatus,
						   &b) == ISC_R_SUCCESS);
		tsigrcode[isc_buffer_usedlength(&b)] = '\0';
		/* There is a signature, but it is bad. */
		if (dns_message_gettsig(client->message, &name) != NULL) {
			char namebuf[DNS_NAME_FORMATSIZE];
			dns_name_format(name, namebuf, sizeof(namebuf));
			ns_client_log(client, DNS_LOGCATEGORY_SECURITY,
				      NS_LOGMODULE_CLIENT, ISC_LOG_ERROR,
				      "request has invalid signature: "
				      "TSIG %s: %s (%s)", namebuf,
				      isc_result_totext(result), tsigrcode);
		} else {
			ns_client_log(client, DNS_LOGCATEGORY_SECURITY,
				      NS_LOGMODULE_CLIENT, ISC_LOG_ERROR,
				      "request has invalid signature: %s (%s)",
				      isc_result_totext(result), tsigrcode);
		}
		/*
		 * Accept update messages signed by unknown keys so that
		 * update forwarding works transparently through slaves
		 * that don't have all the same keys as the master.
		 */
		if (!(client->message->tsigstatus == dns_tsigerror_badkey &&
		      client->message->opcode == dns_opcode_update)) {
			ns_client_error(client, sigresult);
			goto cleanup;
		}
	}

	/*
	 * Decide whether recursive service is available to this client.
	 * We do this here rather than in the query code so that we can
	 * set the RA bit correctly on all kinds of responses, not just
	 * responses to ordinary queries.  Note if you can't query the
	 * cache there is no point in setting RA.
	 */
	ra = ISC_FALSE;
	if (client->view->resolver != NULL &&
	    client->view->recursion == ISC_TRUE &&
	    ns_client_checkaclsilent(client, client->view->recursionacl,
				     ISC_TRUE) == ISC_R_SUCCESS &&
	    ns_client_checkaclsilent(client, client->view->queryacl,
				     ISC_TRUE) == ISC_R_SUCCESS)
		ra = ISC_TRUE;

	if (ra == ISC_TRUE)
		client->attributes |= NS_CLIENTATTR_RA;

	ns_client_log(client, DNS_LOGCATEGORY_SECURITY, NS_LOGMODULE_CLIENT,
		      ISC_LOG_DEBUG(3), ra ? "recursion available" :
		      			     "recursion not available");

	/*
	 * Adjust maximum UDP response size for this client.
	 */
	if (client->udpsize > 512) {
		dns_peer_t *peer = NULL;
		isc_uint16_t udpsize = view->maxudp;
		(void) dns_peerlist_peerbyaddr(view->peers, &netaddr, &peer);
		if (peer != NULL)
			dns_peer_getmaxudp(peer, &udpsize);
		if (client->udpsize > udpsize)
			client->udpsize = udpsize;
	}

	/*
	 * Dispatch the request.
	 */
	switch (client->message->opcode) {
	case dns_opcode_query:
		CTRACE("query");
		ns_query_start(client);
		break;
	case dns_opcode_update:
		CTRACE("update");
		ns_client_settimeout(client, 60);
		ns_update_start(client, sigresult);
		break;
	case dns_opcode_notify:
		CTRACE("notify");
		ns_client_settimeout(client, 60);
		ns_notify_start(client);
		break;
	case dns_opcode_iquery:
		CTRACE("iquery");
		ns_client_error(client, DNS_R_NOTIMP);
		break;
	default:
		CTRACE("unknown opcode");
		ns_client_error(client, DNS_R_NOTIMP);
	}

 cleanup:
	return;
}

static void
client_timeout(isc_task_t *task, isc_event_t *event) {
	ns_client_t *client;

	REQUIRE(event != NULL);
	REQUIRE(event->ev_type == ISC_TIMEREVENT_LIFE ||
		event->ev_type == ISC_TIMEREVENT_IDLE);
	client = event->ev_arg;
	REQUIRE(NS_CLIENT_VALID(client));
	REQUIRE(task == client->task);
	REQUIRE(client->timer != NULL);

	UNUSED(task);

	CTRACE("timeout");

	isc_event_free(&event);

	if (client->shutdown != NULL) {
		(client->shutdown)(client->shutdown_arg, ISC_R_TIMEDOUT);
		client->shutdown = NULL;
		client->shutdown_arg = NULL;
	}

	if (client->newstate > NS_CLIENTSTATE_READY)
		client->newstate = NS_CLIENTSTATE_READY;
	(void)exit_check(client);
}

static isc_result_t
get_clientmctx(ns_clientmgr_t *manager, isc_mem_t **mctxp) {
	isc_mem_t *clientmctx;
#if NMCTXS > 0
	isc_result_t result;
#endif

	/*
	 * Caller must be holding the manager lock.
	 */
#if NMCTXS > 0
	INSIST(manager->nextmctx < NMCTXS);
	clientmctx = manager->mctxpool[manager->nextmctx];
	if (clientmctx == NULL) {
		result = isc_mem_create(0, 0, &clientmctx);
		if (result != ISC_R_SUCCESS)
			return (result);

		manager->mctxpool[manager->nextmctx] = clientmctx;
		manager->nextmctx++;
		if (manager->nextmctx == NMCTXS)
			manager->nextmctx = 0;
	}
#else
	clientmctx = manager->mctx;
#endif

	isc_mem_attach(clientmctx, mctxp);

	return (ISC_R_SUCCESS);
}

static isc_result_t
client_create(ns_clientmgr_t *manager, ns_client_t **clientp) {
	ns_client_t *client;
	isc_result_t result;
	isc_mem_t *mctx = NULL;

	/*
	 * Caller must be holding the manager lock.
	 *
	 * Note: creating a client does not add the client to the
	 * manager's client list or set the client's manager pointer.
	 * The caller is responsible for that.
	 */

	REQUIRE(clientp != NULL && *clientp == NULL);

	result = get_clientmctx(manager, &mctx);
	if (result != ISC_R_SUCCESS)
		return (result);

	client = isc_mem_get(mctx, sizeof(*client));
	if (client == NULL) {
		isc_mem_detach(&mctx);
		return (ISC_R_NOMEMORY);
	}
	client->mctx = mctx;

	client->task = NULL;
	result = isc_task_create(manager->taskmgr, 0, &client->task);
	if (result != ISC_R_SUCCESS)
		goto cleanup_client;
	isc_task_setname(client->task, "client", client);

	client->timer = NULL;
	result = isc_timer_create(manager->timermgr, isc_timertype_inactive,
				  NULL, NULL, client->task, client_timeout,
				  client, &client->timer);
	if (result != ISC_R_SUCCESS)
		goto cleanup_task;
	client->timerset = ISC_FALSE;

	client->message = NULL;
	result = dns_message_create(client->mctx, DNS_MESSAGE_INTENTPARSE,
				    &client->message);
	if (result != ISC_R_SUCCESS)
		goto cleanup_timer;

	/* XXXRTH  Hardwired constants */

	client->sendevent = (isc_socketevent_t *)
			    isc_event_allocate(client->mctx, client,
					       ISC_SOCKEVENT_SENDDONE,
					       client_senddone, client,
					       sizeof(isc_socketevent_t));
	if (client->sendevent == NULL) {
		result = ISC_R_NOMEMORY;
		goto cleanup_message;
	}

	client->recvbuf = isc_mem_get(client->mctx, RECV_BUFFER_SIZE);
	if  (client->recvbuf == NULL) {
		result = ISC_R_NOMEMORY;
		goto cleanup_sendevent;
	}

	client->recvevent = (isc_socketevent_t *)
			    isc_event_allocate(client->mctx, client,
					       ISC_SOCKEVENT_RECVDONE,
					       client_request, client,
					       sizeof(isc_socketevent_t));
	if (client->recvevent == NULL) {
		result = ISC_R_NOMEMORY;
		goto cleanup_recvbuf;
	}

	client->magic = NS_CLIENT_MAGIC;
	client->manager = NULL;
	client->state = NS_CLIENTSTATE_INACTIVE;
	client->newstate = NS_CLIENTSTATE_MAX;
	client->naccepts = 0;
	client->nreads = 0;
	client->nsends = 0;
	client->nrecvs = 0;
	client->nupdates = 0;
	client->nctls = 0;
	client->references = 0;
	client->attributes = 0;
	client->view = NULL;
	client->dispatch = NULL;
	client->udpsocket = NULL;
	client->tcplistener = NULL;
	client->tcpsocket = NULL;
	client->tcpmsg_valid = ISC_FALSE;
	client->tcpbuf = NULL;
	client->opt = NULL;
	client->udpsize = 512;
	client->extflags = 0;
	client->ednsversion = -1;
	client->next = NULL;
	client->shutdown = NULL;
	client->shutdown_arg = NULL;
	dns_name_init(&client->signername, NULL);
	client->mortal = ISC_FALSE;
	client->tcpquota = NULL;
	client->recursionquota = NULL;
	client->interface = NULL;
	client->peeraddr_valid = ISC_FALSE;
	ISC_EVENT_INIT(&client->ctlevent, sizeof(client->ctlevent), 0, NULL,
		       NS_EVENT_CLIENTCONTROL, client_start, client, client,
		       NULL, NULL);
	/*
	 * Initialize FORMERR cache to sentinel value that will not match
	 * any actual FORMERR response.
	 */
	isc_sockaddr_any(&client->formerrcache.addr);
	client->formerrcache.time = 0;
	client->formerrcache.id = 0;
	ISC_LINK_INIT(client, link);
	client->list = NULL;

	/*
	 * We call the init routines for the various kinds of client here,
	 * after we have created an otherwise valid client, because some
	 * of them call routines that REQUIRE(NS_CLIENT_VALID(client)).
	 */
	result = ns_query_init(client);