Adding upstream version 1:9.18.19.upstream/1%9.18.19upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1216 insertions, 0 deletions

diff --git a/lib/dns/request.c b/lib/dns/request.c
new file mode 100644
index 0000000..b2b7b11
--- /dev/null
+++ b/lib/dns/request.c
@@ -0,0 +1,1216 @@
+/*
+ * Copyright (C) Internet Systems Consortium, Inc. ("ISC")
+ *
+ * SPDX-License-Identifier: MPL-2.0
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, you can obtain one at https://mozilla.org/MPL/2.0/.
+ *
+ * See the COPYRIGHT file distributed with this work for additional
+ * information regarding copyright ownership.
+ */
+
+/*! \file */
+
+#include <inttypes.h>
+#include <stdbool.h>
+
+#include <isc/magic.h>
+#include <isc/mem.h>
+#include <isc/netmgr.h>
+#include <isc/result.h>
+#include <isc/task.h>
+#include <isc/thread.h>
+#include <isc/util.h>
+
+#include <dns/acl.h>
+#include <dns/compress.h>
+#include <dns/dispatch.h>
+#include <dns/events.h>
+#include <dns/log.h>
+#include <dns/message.h>
+#include <dns/rdata.h>
+#include <dns/rdatastruct.h>
+#include <dns/request.h>
+#include <dns/tsig.h>
+
+#define REQUESTMGR_MAGIC      ISC_MAGIC('R', 'q', 'u', 'M')
+#define VALID_REQUESTMGR(mgr) ISC_MAGIC_VALID(mgr, REQUESTMGR_MAGIC)
+
+#define REQUEST_MAGIC	       ISC_MAGIC('R', 'q', 'u', '!')
+#define VALID_REQUEST(request) ISC_MAGIC_VALID(request, REQUEST_MAGIC)
+
+typedef ISC_LIST(dns_request_t) dns_requestlist_t;
+
+#define DNS_REQUEST_NLOCKS 7
+
+struct dns_requestmgr {
+	unsigned int magic;
+	isc_refcount_t references;
+
+	isc_mutex_t lock;
+	isc_mem_t *mctx;
+
+	/* locked */
+	isc_taskmgr_t *taskmgr;
+	dns_dispatchmgr_t *dispatchmgr;
+	dns_dispatch_t *dispatchv4;
+	dns_dispatch_t *dispatchv6;
+	atomic_bool exiting;
+	isc_eventlist_t whenshutdown;
+	unsigned int hash;
+	isc_mutex_t locks[DNS_REQUEST_NLOCKS];
+	dns_requestlist_t requests;
+};
+
+struct dns_request {
+	unsigned int magic;
+	isc_refcount_t references;
+
+	unsigned int hash;
+	isc_mem_t *mctx;
+	int32_t flags;
+	ISC_LINK(dns_request_t) link;
+	isc_buffer_t *query;
+	isc_buffer_t *answer;
+	dns_requestevent_t *event;
+	dns_dispatch_t *dispatch;
+	dns_dispentry_t *dispentry;
+	dns_requestmgr_t *requestmgr;
+	isc_buffer_t *tsig;
+	dns_tsigkey_t *tsigkey;
+	isc_sockaddr_t destaddr;
+	unsigned int timeout;
+	unsigned int udpcount;
+};
+
+#define DNS_REQUEST_F_CONNECTING 0x0001
+#define DNS_REQUEST_F_SENDING	 0x0002
+#define DNS_REQUEST_F_CANCELED	 0x0004
+#define DNS_REQUEST_F_TCP	 0x0010
+
+#define DNS_REQUEST_CANCELED(r)	  (((r)->flags & DNS_REQUEST_F_CANCELED) != 0)
+#define DNS_REQUEST_CONNECTING(r) (((r)->flags & DNS_REQUEST_F_CONNECTING) != 0)
+#define DNS_REQUEST_SENDING(r)	  (((r)->flags & DNS_REQUEST_F_SENDING) != 0)
+
+/***
+ *** Forward
+ ***/
+
+static void
+mgr_destroy(dns_requestmgr_t *requestmgr);
+static unsigned int
+mgr_gethash(dns_requestmgr_t *requestmgr);
+static void
+send_shutdown_events(dns_requestmgr_t *requestmgr);
+
+static isc_result_t
+req_render(dns_message_t *message, isc_buffer_t **buffer, unsigned int options,
+	   isc_mem_t *mctx);
+static void
+req_response(isc_result_t result, isc_region_t *region, void *arg);
+static void
+req_senddone(isc_result_t eresult, isc_region_t *region, void *arg);
+static void
+req_sendevent(dns_request_t *request, isc_result_t result);
+static void
+req_connected(isc_result_t eresult, isc_region_t *region, void *arg);
+static void
+req_attach(dns_request_t *source, dns_request_t **targetp);
+static void
+req_detach(dns_request_t **requestp);
+static void
+req_destroy(dns_request_t *request);
+static void
+req_log(int level, const char *fmt, ...) ISC_FORMAT_PRINTF(2, 3);
+void
+request_cancel(dns_request_t *request);
+
+/***
+ *** Public
+ ***/
+
+isc_result_t
+dns_requestmgr_create(isc_mem_t *mctx, isc_taskmgr_t *taskmgr,
+		      dns_dispatchmgr_t *dispatchmgr,
+		      dns_dispatch_t *dispatchv4, dns_dispatch_t *dispatchv6,
+		      dns_requestmgr_t **requestmgrp) {
+	dns_requestmgr_t *requestmgr;
+	int i;
+
+	req_log(ISC_LOG_DEBUG(3), "dns_requestmgr_create");
+
+	REQUIRE(requestmgrp != NULL && *requestmgrp == NULL);
+	REQUIRE(taskmgr != NULL);
+	REQUIRE(dispatchmgr != NULL);
+
+	requestmgr = isc_mem_get(mctx, sizeof(*requestmgr));
+	*requestmgr = (dns_requestmgr_t){ 0 };
+
+	isc_taskmgr_attach(taskmgr, &requestmgr->taskmgr);
+	dns_dispatchmgr_attach(dispatchmgr, &requestmgr->dispatchmgr);
+	isc_mutex_init(&requestmgr->lock);
+
+	for (i = 0; i < DNS_REQUEST_NLOCKS; i++) {
+		isc_mutex_init(&requestmgr->locks[i]);
+	}
+	if (dispatchv4 != NULL) {
+		dns_dispatch_attach(dispatchv4, &requestmgr->dispatchv4);
+	}
+	if (dispatchv6 != NULL) {
+		dns_dispatch_attach(dispatchv6, &requestmgr->dispatchv6);
+	}
+	isc_mem_attach(mctx, &requestmgr->mctx);
+
+	isc_refcount_init(&requestmgr->references, 1);
+
+	ISC_LIST_INIT(requestmgr->whenshutdown);
+	ISC_LIST_INIT(requestmgr->requests);
+
+	atomic_init(&requestmgr->exiting, false);
+
+	requestmgr->magic = REQUESTMGR_MAGIC;
+
+	req_log(ISC_LOG_DEBUG(3), "dns_requestmgr_create: %p", requestmgr);
+
+	*requestmgrp = requestmgr;
+	return (ISC_R_SUCCESS);
+}
+
+void
+dns_requestmgr_whenshutdown(dns_requestmgr_t *requestmgr, isc_task_t *task,
+			    isc_event_t **eventp) {
+	isc_task_t *tclone;
+	isc_event_t *event;
+
+	req_log(ISC_LOG_DEBUG(3), "dns_requestmgr_whenshutdown");
+
+	REQUIRE(VALID_REQUESTMGR(requestmgr));
+	REQUIRE(eventp != NULL);
+
+	event = *eventp;
+	*eventp = NULL;
+
+	LOCK(&requestmgr->lock);
+
+	if (atomic_load_acquire(&requestmgr->exiting)) {
+		/*
+		 * We're already shutdown.  Send the event.
+		 */
+		event->ev_sender = requestmgr;
+		isc_task_send(task, &event);
+	} else {
+		tclone = NULL;
+		isc_task_attach(task, &tclone);
+		event->ev_sender = tclone;
+		ISC_LIST_APPEND(requestmgr->whenshutdown, event, ev_link);
+	}
+	UNLOCK(&requestmgr->lock);
+}
+
+void
+dns_requestmgr_shutdown(dns_requestmgr_t *requestmgr) {
+	dns_request_t *request;
+
+	REQUIRE(VALID_REQUESTMGR(requestmgr));
+
+	req_log(ISC_LOG_DEBUG(3), "dns_requestmgr_shutdown: %p", requestmgr);
+
+	if (!atomic_compare_exchange_strong(&requestmgr->exiting,
+					    &(bool){ false }, true))
+	{
+		return;
+	}
+
+	LOCK(&requestmgr->lock);
+	for (request = ISC_LIST_HEAD(requestmgr->requests); request != NULL;
+	     request = ISC_LIST_NEXT(request, link))
+	{
+		dns_request_cancel(request);
+	}
+
+	if (ISC_LIST_EMPTY(requestmgr->requests)) {
+		send_shutdown_events(requestmgr);
+	}
+
+	UNLOCK(&requestmgr->lock);
+}
+
+void
+dns_requestmgr_attach(dns_requestmgr_t *source, dns_requestmgr_t **targetp) {
+	uint_fast32_t ref;
+
+	REQUIRE(VALID_REQUESTMGR(source));
+	REQUIRE(targetp != NULL && *targetp == NULL);
+
+	REQUIRE(!atomic_load_acquire(&source->exiting));
+
+	ref = isc_refcount_increment(&source->references);
+
+	req_log(ISC_LOG_DEBUG(3),
+		"dns_requestmgr_attach: %p: references = %" PRIuFAST32, source,
+		ref + 1);
+
+	*targetp = source;
+}
+
+void
+dns_requestmgr_detach(dns_requestmgr_t **requestmgrp) {
+	dns_requestmgr_t *requestmgr = NULL;
+	uint_fast32_t ref;
+
+	REQUIRE(requestmgrp != NULL && VALID_REQUESTMGR(*requestmgrp));
+
+	requestmgr = *requestmgrp;
+	*requestmgrp = NULL;
+
+	ref = isc_refcount_decrement(&requestmgr->references);
+
+	req_log(ISC_LOG_DEBUG(3),
+		"dns_requestmgr_detach: %p: references = %" PRIuFAST32,
+		requestmgr, ref - 1);
+
+	if (ref == 1) {
+		INSIST(ISC_LIST_EMPTY(requestmgr->requests));
+		mgr_destroy(requestmgr);
+	}
+}
+
+/* FIXME */
+static void
+send_shutdown_events(dns_requestmgr_t *requestmgr) {
+	isc_event_t *event, *next_event;
+	isc_task_t *etask;
+
+	req_log(ISC_LOG_DEBUG(3), "send_shutdown_events: %p", requestmgr);
+
+	/*
+	 * Caller must be holding the manager lock.
+	 */
+	for (event = ISC_LIST_HEAD(requestmgr->whenshutdown); event != NULL;
+	     event = next_event)
+	{
+		next_event = ISC_LIST_NEXT(event, ev_link);
+		ISC_LIST_UNLINK(requestmgr->whenshutdown, event, ev_link);
+		etask = event->ev_sender;
+		event->ev_sender = requestmgr;
+		isc_task_sendanddetach(&etask, &event);
+	}
+}
+
+static void
+mgr_destroy(dns_requestmgr_t *requestmgr) {
+	int i;
+
+	req_log(ISC_LOG_DEBUG(3), "mgr_destroy");
+
+	isc_refcount_destroy(&requestmgr->references);
+
+	isc_mutex_destroy(&requestmgr->lock);
+	for (i = 0; i < DNS_REQUEST_NLOCKS; i++) {
+		isc_mutex_destroy(&requestmgr->locks[i]);
+	}
+	if (requestmgr->dispatchv4 != NULL) {
+		dns_dispatch_detach(&requestmgr->dispatchv4);
+	}
+	if (requestmgr->dispatchv6 != NULL) {
+		dns_dispatch_detach(&requestmgr->dispatchv6);
+	}
+	if (requestmgr->dispatchmgr != NULL) {
+		dns_dispatchmgr_detach(&requestmgr->dispatchmgr);
+	}
+	if (requestmgr->taskmgr != NULL) {
+		isc_taskmgr_detach(&requestmgr->taskmgr);
+	}
+	requestmgr->magic = 0;
+	isc_mem_putanddetach(&requestmgr->mctx, requestmgr,
+			     sizeof(*requestmgr));
+}
+
+static unsigned int
+mgr_gethash(dns_requestmgr_t *requestmgr) {
+	req_log(ISC_LOG_DEBUG(3), "mgr_gethash");
+	/*
+	 * Locked by caller.
+	 */
+	requestmgr->hash++;
+	return (requestmgr->hash % DNS_REQUEST_NLOCKS);
+}
+
+static void
+req_send(dns_request_t *request) {
+	isc_region_t r;
+
+	req_log(ISC_LOG_DEBUG(3), "req_send: request %p", request);
+
+	REQUIRE(VALID_REQUEST(request));
+
+	isc_buffer_usedregion(request->query, &r);
+
+	request->flags |= DNS_REQUEST_F_SENDING;
+
+	/* detached in req_senddone() */
+	req_attach(request, &(dns_request_t *){ NULL });
+	dns_dispatch_send(request->dispentry, &r);
+}
+
+static isc_result_t
+new_request(isc_mem_t *mctx, dns_request_t **requestp) {
+	dns_request_t *request = NULL;
+
+	request = isc_mem_get(mctx, sizeof(*request));
+	*request = (dns_request_t){ 0 };
+	ISC_LINK_INIT(request, link);
+
+	isc_refcount_init(&request->references, 1);
+	isc_mem_attach(mctx, &request->mctx);
+
+	request->magic = REQUEST_MAGIC;
+	*requestp = request;
+	return (ISC_R_SUCCESS);
+}
+
+static bool
+isblackholed(dns_dispatchmgr_t *dispatchmgr, const isc_sockaddr_t *destaddr) {
+	dns_acl_t *blackhole;
+	isc_netaddr_t netaddr;
+	char netaddrstr[ISC_NETADDR_FORMATSIZE];
+	int match;
+	isc_result_t result;
+
+	blackhole = dns_dispatchmgr_getblackhole(dispatchmgr);
+	if (blackhole == NULL) {
+		return (false);
+	}
+
+	isc_netaddr_fromsockaddr(&netaddr, destaddr);
+	result = dns_acl_match(&netaddr, NULL, blackhole, NULL, &match, NULL);
+	if (result != ISC_R_SUCCESS || match <= 0) {
+		return (false);
+	}
+
+	isc_netaddr_format(&netaddr, netaddrstr, sizeof(netaddrstr));
+	req_log(ISC_LOG_DEBUG(10), "blackholed address %s", netaddrstr);
+
+	return (true);
+}
+
+static isc_result_t
+tcp_dispatch(bool newtcp, dns_requestmgr_t *requestmgr,
+	     const isc_sockaddr_t *srcaddr, const isc_sockaddr_t *destaddr,
+	     dns_dispatch_t **dispatchp) {
+	isc_result_t result;
+
+	if (!newtcp) {
+		result = dns_dispatch_gettcp(requestmgr->dispatchmgr, destaddr,
+					     srcaddr, dispatchp);
+		if (result == ISC_R_SUCCESS) {
+			char peer[ISC_SOCKADDR_FORMATSIZE];
+
+			isc_sockaddr_format(destaddr, peer, sizeof(peer));
+			req_log(ISC_LOG_DEBUG(1),
+				"attached to TCP connection to %s", peer);
+			return (result);
+		}
+	}
+
+	result = dns_dispatch_createtcp(requestmgr->dispatchmgr, srcaddr,
+					destaddr, dispatchp);
+	return (result);
+}
+
+static isc_result_t
+udp_dispatch(dns_requestmgr_t *requestmgr, const isc_sockaddr_t *srcaddr,
+	     const isc_sockaddr_t *destaddr, dns_dispatch_t **dispatchp) {
+	dns_dispatch_t *disp = NULL;
+
+	if (srcaddr == NULL) {
+		switch (isc_sockaddr_pf(destaddr)) {
+		case PF_INET:
+			disp = requestmgr->dispatchv4;
+			break;
+
+		case PF_INET6:
+			disp = requestmgr->dispatchv6;
+			break;
+
+		default:
+			return (ISC_R_NOTIMPLEMENTED);
+		}
+		if (disp == NULL) {
+			return (ISC_R_FAMILYNOSUPPORT);
+		}
+		dns_dispatch_attach(disp, dispatchp);
+		return (ISC_R_SUCCESS);
+	}
+
+	return (dns_dispatch_createudp(requestmgr->dispatchmgr, srcaddr,
+				       dispatchp));
+}
+
+static isc_result_t
+get_dispatch(bool tcp, bool newtcp, dns_requestmgr_t *requestmgr,
+	     const isc_sockaddr_t *srcaddr, const isc_sockaddr_t *destaddr,
+	     dns_dispatch_t **dispatchp) {
+	isc_result_t result;
+
+	if (tcp) {
+		result = tcp_dispatch(newtcp, requestmgr, srcaddr, destaddr,
+				      dispatchp);
+	} else {
+		result = udp_dispatch(requestmgr, srcaddr, destaddr, dispatchp);
+	}
+	return (result);
+}
+
+isc_result_t
+dns_request_createraw(dns_requestmgr_t *requestmgr, isc_buffer_t *msgbuf,
+		      const isc_sockaddr_t *srcaddr,
+		      const isc_sockaddr_t *destaddr, unsigned int options,
+		      unsigned int timeout, unsigned int udptimeout,
+		      unsigned int udpretries, isc_task_t *task,
+		      isc_taskaction_t action, void *arg,
+		      dns_request_t **requestp) {
+	dns_request_t *request = NULL;
+	isc_result_t result;
+	isc_mem_t *mctx = NULL;
+	dns_messageid_t id;
+	bool tcp = false;
+	bool newtcp = false;
+	isc_region_t r;
+	unsigned int dispopt = 0;
+
+	REQUIRE(VALID_REQUESTMGR(requestmgr));
+	REQUIRE(msgbuf != NULL);
+	REQUIRE(destaddr != NULL);
+	REQUIRE(task != NULL);
+	REQUIRE(action != NULL);
+	REQUIRE(requestp != NULL && *requestp == NULL);
+	REQUIRE(timeout > 0);
+	REQUIRE(udpretries != UINT_MAX);
+
+	if (srcaddr != NULL) {
+		REQUIRE(isc_sockaddr_pf(srcaddr) == isc_sockaddr_pf(destaddr));
+	}
+
+	mctx = requestmgr->mctx;
+
+	req_log(ISC_LOG_DEBUG(3), "dns_request_createraw");
+
+	if (atomic_load_acquire(&requestmgr->exiting)) {
+		return (ISC_R_SHUTTINGDOWN);
+	}
+
+	if (isblackholed(requestmgr->dispatchmgr, destaddr)) {
+		return (DNS_R_BLACKHOLED);
+	}
+
+	/* detached in dns_request_destroy() */
+	result = new_request(mctx, &request);
+	if (result != ISC_R_SUCCESS) {
+		return (result);
+	}
+
+	request->udpcount = udpretries + 1;
+
+	request->event = (dns_requestevent_t *)isc_event_allocate(
+		mctx, task, DNS_EVENT_REQUESTDONE, action, arg,
+		sizeof(dns_requestevent_t));
+	isc_task_attach(task, &(isc_task_t *){ NULL });
+	request->event->ev_sender = task;
+	request->event->request = request;
+	request->event->result = ISC_R_FAILURE;
+
+	isc_buffer_usedregion(msgbuf, &r);
+	if (r.length < DNS_MESSAGE_HEADERLEN || r.length > 65535) {
+		result = DNS_R_FORMERR;
+		goto cleanup;
+	}
+
+	if ((options & DNS_REQUESTOPT_TCP) != 0 || r.length > 512) {
+		tcp = true;
+		request->timeout = timeout * 1000;
+	} else {
+		if (udptimeout == 0) {
+			udptimeout = timeout / request->udpcount;
+		}
+		if (udptimeout == 0) {
+			udptimeout = 1;
+		}
+		request->timeout = udptimeout * 1000;
+	}
+
+	isc_buffer_allocate(mctx, &request->query, r.length + (tcp ? 2 : 0));
+	result = isc_buffer_copyregion(request->query, &r);
+	if (result != ISC_R_SUCCESS) {
+		goto cleanup;
+	}
+
+	/* detached in req_connected() */
+	req_attach(request, &(dns_request_t *){ NULL });
+
+again:
+
+	result = get_dispatch(tcp, newtcp, requestmgr, srcaddr, destaddr,
+			      &request->dispatch);
+	if (result != ISC_R_SUCCESS) {
+		goto detach;
+	}
+
+	if ((options & DNS_REQUESTOPT_FIXEDID) != 0) {
+		id = (r.base[0] << 8) | r.base[1];
+		dispopt |= DNS_DISPATCHOPT_FIXEDID;
+	}
+
+	result = dns_dispatch_add(request->dispatch, dispopt, request->timeout,
+				  destaddr, req_connected, req_senddone,
+				  req_response, request, &id,
+				  &request->dispentry);
+	if (result != ISC_R_SUCCESS) {
+		if ((options & DNS_REQUESTOPT_FIXEDID) != 0 && !newtcp) {
+			newtcp = true;
+			dns_dispatch_detach(&request->dispatch);
+			goto again;
+		}
+
+		goto detach;
+	}
+
+	/* Add message ID. */
+	isc_buffer_usedregion(request->query, &r);
+	r.base[0] = (id >> 8) & 0xff;
+	r.base[1] = id & 0xff;
+
+	LOCK(&requestmgr->lock);
+	dns_requestmgr_attach(requestmgr, &request->requestmgr);
+	request->hash = mgr_gethash(requestmgr);
+	ISC_LIST_APPEND(requestmgr->requests, request, link);
+	UNLOCK(&requestmgr->lock);
+
+	request->destaddr = *destaddr;
+
+	request->flags |= DNS_REQUEST_F_CONNECTING;
+	if (tcp) {
+		request->flags |= DNS_REQUEST_F_TCP;
+	}
+
+	result = dns_dispatch_connect(request->dispentry);
+	if (result != ISC_R_SUCCESS) {
+		goto unlink;
+	}
+
+	req_log(ISC_LOG_DEBUG(3), "dns_request_createraw: request %p", request);
+	*requestp = request;
+	return (ISC_R_SUCCESS);
+
+unlink:
+	LOCK(&requestmgr->lock);
+	ISC_LIST_UNLINK(requestmgr->requests, request, link);
+	UNLOCK(&requestmgr->lock);
+
+detach:
+	/* connect failed, detach here */
+	req_detach(&(dns_request_t *){ request });
+
+cleanup:
+	isc_task_detach(&(isc_task_t *){ task });
+	/* final detach to shut down request */
+	req_detach(&request);
+	req_log(ISC_LOG_DEBUG(3), "dns_request_createraw: failed %s",
+		isc_result_totext(result));
+	return (result);
+}
+
+isc_result_t
+dns_request_create(dns_requestmgr_t *requestmgr, dns_message_t *message,
+		   const isc_sockaddr_t *srcaddr,
+		   const isc_sockaddr_t *destaddr, unsigned int options,
+		   dns_tsigkey_t *key, unsigned int timeout,
+		   unsigned int udptimeout, unsigned int udpretries,
+		   isc_task_t *task, isc_taskaction_t action, void *arg,
+		   dns_request_t **requestp) {
+	dns_request_t *request = NULL;
+	isc_result_t result;
+	isc_mem_t *mctx = NULL;
+	dns_messageid_t id;
+	bool tcp = false;
+	bool connected = false;
+
+	REQUIRE(VALID_REQUESTMGR(requestmgr));
+	REQUIRE(message != NULL);
+	REQUIRE(destaddr != NULL);
+	REQUIRE(task != NULL);
+	REQUIRE(action != NULL);
+	REQUIRE(requestp != NULL && *requestp == NULL);
+	REQUIRE(timeout > 0);
+	REQUIRE(udpretries != UINT_MAX);
+
+	mctx = requestmgr->mctx;
+
+	req_log(ISC_LOG_DEBUG(3), "dns_request_create");
+
+	if (atomic_load_acquire(&requestmgr->exiting)) {
+		return (ISC_R_SHUTTINGDOWN);
+	}
+
+	if (srcaddr != NULL &&
+	    isc_sockaddr_pf(srcaddr) != isc_sockaddr_pf(destaddr))
+	{
+		return (ISC_R_FAMILYMISMATCH);
+	}
+
+	if (isblackholed(requestmgr->dispatchmgr, destaddr)) {
+		return (DNS_R_BLACKHOLED);
+	}
+
+	/* detached in dns_request_destroy() */
+	result = new_request(mctx, &request);
+	if (result != ISC_R_SUCCESS) {
+		return (result);
+	}
+
+	request->udpcount = udpretries + 1;
+
+	request->event = (dns_requestevent_t *)isc_event_allocate(
+		mctx, task, DNS_EVENT_REQUESTDONE, action, arg,
+		sizeof(dns_requestevent_t));
+	isc_task_attach(task, &(isc_task_t *){ NULL });
+	request->event->ev_sender = task;
+	request->event->request = request;
+	request->event->result = ISC_R_FAILURE;
+
+	if (key != NULL) {
+		dns_tsigkey_attach(key, &request->tsigkey);
+	}
+
+	result = dns_message_settsigkey(message, request->tsigkey);
+	if (result != ISC_R_SUCCESS) {
+		goto cleanup;
+	}
+
+	if ((options & DNS_REQUESTOPT_TCP) != 0) {
+		tcp = true;
+		request->timeout = timeout * 1000;
+	} else {
+		if (udptimeout == 0) {
+			udptimeout = timeout / request->udpcount;
+		}
+		if (udptimeout == 0) {
+			udptimeout = 1;
+		}
+		request->timeout = udptimeout * 1000;
+	}
+
+	/* detached in req_connected() */
+	req_attach(request, &(dns_request_t *){ NULL });
+
+again:
+	result = get_dispatch(tcp, false, requestmgr, srcaddr, destaddr,
+			      &request->dispatch);
+	if (result != ISC_R_SUCCESS) {
+		goto detach;
+	}
+
+	result = dns_dispatch_add(
+		request->dispatch, 0, request->timeout, destaddr, req_connected,
+		req_senddone, req_response, request, &id, &request->dispentry);
+	if (result != ISC_R_SUCCESS) {
+		goto detach;
+	}
+
+	message->id = id;
+	result = req_render(message, &request->query, options, mctx);
+	if (result == DNS_R_USETCP && !tcp) {
+		/*
+		 * Try again using TCP.
+		 */
+		dns_message_renderreset(message);
+		dns_dispatch_done(&request->dispentry);
+		dns_dispatch_detach(&request->dispatch);
+		options |= DNS_REQUESTOPT_TCP;
+		tcp = true;
+		goto again;
+	}
+	if (result != ISC_R_SUCCESS) {
+		goto detach;
+	}
+
+	result = dns_message_getquerytsig(message, mctx, &request->tsig);
+	if (result != ISC_R_SUCCESS) {
+		goto detach;
+	}
+
+	LOCK(&requestmgr->lock);
+	dns_requestmgr_attach(requestmgr, &request->requestmgr);
+	request->hash = mgr_gethash(requestmgr);
+	ISC_LIST_APPEND(requestmgr->requests, request, link);
+	UNLOCK(&requestmgr->lock);
+
+	request->destaddr = *destaddr;
+	if (tcp && connected) {
+		req_send(request);
+
+		/* no need to call req_connected(), detach here */
+		req_detach(&(dns_request_t *){ request });
+	} else {
+		request->flags |= DNS_REQUEST_F_CONNECTING;
+		if (tcp) {
+			request->flags |= DNS_REQUEST_F_TCP;
+		}
+
+		result = dns_dispatch_connect(request->dispentry);
+		if (result != ISC_R_SUCCESS) {
+			goto unlink;
+		}
+	}
+
+	req_log(ISC_LOG_DEBUG(3), "dns_request_create: request %p", request);
+	*requestp = request;
+	return (ISC_R_SUCCESS);
+
+unlink:
+	LOCK(&requestmgr->lock);
+	ISC_LIST_UNLINK(requestmgr->requests, request, link);
+	UNLOCK(&requestmgr->lock);
+
+detach:
+	/* connect failed, detach here */
+	req_detach(&(dns_request_t *){ request });
+
+cleanup:
+	isc_task_detach(&(isc_task_t *){ task });
+	/* final detach to shut down request */
+	req_detach(&request);
+	req_log(ISC_LOG_DEBUG(3), "dns_request_create: failed %s",
+		isc_result_totext(result));
+	return (result);
+}
+
+static isc_result_t
+req_render(dns_message_t *message, isc_buffer_t **bufferp, unsigned int options,
+	   isc_mem_t *mctx) {
+	isc_buffer_t *buf1 = NULL;
+	isc_buffer_t *buf2 = NULL;
+	isc_result_t result;
+	isc_region_t r;
+	dns_compress_t cctx;
+	bool cleanup_cctx = false;
+
+	REQUIRE(bufferp != NULL && *bufferp == NULL);
+
+	req_log(ISC_LOG_DEBUG(3), "request_render");
+
+	/*
+	 * Create buffer able to hold largest possible message.
+	 */
+	isc_buffer_allocate(mctx, &buf1, 65535);
+
+	result = dns_compress_init(&cctx, -1, mctx);
+	if (result != ISC_R_SUCCESS) {
+		return (result);
+	}
+	cleanup_cctx = true;
+
+	if ((options & DNS_REQUESTOPT_CASE) != 0) {
+		dns_compress_setsensitive(&cctx, true);
+	}
+
+	/*
+	 * Render message.
+	 */
+	result = dns_message_renderbegin(message, &cctx, buf1);
+	if (result != ISC_R_SUCCESS) {
+		goto cleanup;
+	}
+	result = dns_message_rendersection(message, DNS_SECTION_QUESTION, 0);
+	if (result != ISC_R_SUCCESS) {
+		goto cleanup;
+	}
+	result = dns_message_rendersection(message, DNS_SECTION_ANSWER, 0);
+	if (result != ISC_R_SUCCESS) {
+		goto cleanup;
+	}
+	result = dns_message_rendersection(message, DNS_SECTION_AUTHORITY, 0);
+	if (result != ISC_R_SUCCESS) {
+		goto cleanup;
+	}
+	result = dns_message_rendersection(message, DNS_SECTION_ADDITIONAL, 0);
+	if (result != ISC_R_SUCCESS) {
+		goto cleanup;
+	}
+	result = dns_message_renderend(message);
+	if (result != ISC_R_SUCCESS) {
+		goto cleanup;
+	}
+
+	dns_compress_invalidate(&cctx);
+	cleanup_cctx = false;
+
+	/*
+	 * Copy rendered message to exact sized buffer.
+	 */
+	isc_buffer_usedregion(buf1, &r);
+	if ((options & DNS_REQUESTOPT_TCP) == 0 && r.length > 512) {
+		result = DNS_R_USETCP;
+		goto cleanup;
+	}
+	isc_buffer_allocate(mctx, &buf2, r.length);
+	result = isc_buffer_copyregion(buf2, &r);
+	if (result != ISC_R_SUCCESS) {
+		goto cleanup;
+	}
+
+	/*
+	 * Cleanup and return.
+	 */
+	isc_buffer_free(&buf1);
+	*bufferp = buf2;
+	return (ISC_R_SUCCESS);
+
+cleanup:
+	dns_message_renderreset(message);
+	if (buf1 != NULL) {
+		isc_buffer_free(&buf1);
+	}
+	if (buf2 != NULL) {
+		isc_buffer_free(&buf2);
+	}
+	if (cleanup_cctx) {
+		dns_compress_invalidate(&cctx);
+	}
+	return (result);
+}
+
+void
+request_cancel(dns_request_t *request) {
+	if (!DNS_REQUEST_CANCELED(request)) {
+		req_log(ISC_LOG_DEBUG(3), "request_cancel: request %p",
+			request);
+
+		request->flags |= DNS_REQUEST_F_CANCELED;
+		request->flags &= ~DNS_REQUEST_F_CONNECTING;
+
+		if (request->dispentry != NULL) {
+			dns_dispatch_done(&request->dispentry);
+		}
+
+		dns_dispatch_detach(&request->dispatch);
+	}
+}
+
+void
+dns_request_cancel(dns_request_t *request) {
+	REQUIRE(VALID_REQUEST(request));
+
+	req_log(ISC_LOG_DEBUG(3), "dns_request_cancel: request %p", request);
+	LOCK(&request->requestmgr->locks[request->hash]);
+	request_cancel(request);
+	req_sendevent(request, ISC_R_CANCELED);
+	UNLOCK(&request->requestmgr->locks[request->hash]);
+}
+
+isc_result_t
+dns_request_getresponse(dns_request_t *request, dns_message_t *message,
+			unsigned int options) {
+	isc_result_t result;
+
+	REQUIRE(VALID_REQUEST(request));
+	REQUIRE(request->answer != NULL);
+
+	req_log(ISC_LOG_DEBUG(3), "dns_request_getresponse: request %p",
+		request);
+
+	result = dns_message_setquerytsig(message, request->tsig);
+	if (result != ISC_R_SUCCESS) {
+		return (result);
+	}
+	result = dns_message_settsigkey(message, request->tsigkey);
+	if (result != ISC_R_SUCCESS) {
+		return (result);
+	}
+	result = dns_message_parse(message, request->answer, options);
+	if (result != ISC_R_SUCCESS) {
+		return (result);
+	}
+	if (request->tsigkey != NULL) {
+		result = dns_tsig_verify(request->answer, message, NULL, NULL);
+	}
+	return (result);
+}
+
+isc_buffer_t *
+dns_request_getanswer(dns_request_t *request) {
+	REQUIRE(VALID_REQUEST(request));
+
+	return (request->answer);
+}
+
+bool
+dns_request_usedtcp(dns_request_t *request) {
+	REQUIRE(VALID_REQUEST(request));
+
+	return ((request->flags & DNS_REQUEST_F_TCP) != 0);
+}
+
+void
+dns_request_destroy(dns_request_t **requestp) {
+	dns_request_t *request;
+
+	REQUIRE(requestp != NULL && VALID_REQUEST(*requestp));
+
+	request = *requestp;
+	*requestp = NULL;
+
+	req_log(ISC_LOG_DEBUG(3), "dns_request_destroy: request %p", request);
+
+	LOCK(&request->requestmgr->lock);
+	LOCK(&request->requestmgr->locks[request->hash]);
+	ISC_LIST_UNLINK(request->requestmgr->requests, request, link);
+	UNLOCK(&request->requestmgr->locks[request->hash]);
+	UNLOCK(&request->requestmgr->lock);
+
+	/*
+	 * These should have been cleaned up before the completion
+	 * event was sent.
+	 */
+	INSIST(request->dispentry == NULL);
+	INSIST(request->dispatch == NULL);
+
+	/* final detach to shut down request */
+	req_detach(&request);
+}
+
+static void
+req_connected(isc_result_t eresult, isc_region_t *region, void *arg) {
+	dns_request_t *request = (dns_request_t *)arg;
+
+	UNUSED(region);
+
+	req_log(ISC_LOG_DEBUG(3), "req_connected: request %p: %s", request,
+		isc_result_totext(eresult));
+
+	REQUIRE(VALID_REQUEST(request));
+	REQUIRE(DNS_REQUEST_CONNECTING(request) ||
+		DNS_REQUEST_CANCELED(request));
+
+	LOCK(&request->requestmgr->locks[request->hash]);
+	request->flags &= ~DNS_REQUEST_F_CONNECTING;
+
+	if (eresult == ISC_R_TIMEDOUT) {
+		dns_dispatch_done(&request->dispentry);
+		dns_dispatch_detach(&request->dispatch);
+		req_sendevent(request, eresult);
+	} else if (DNS_REQUEST_CANCELED(request)) {
+		req_sendevent(request, ISC_R_CANCELED);
+	} else if (eresult == ISC_R_SUCCESS) {
+		req_send(request);
+	} else {
+		request_cancel(request);
+		req_sendevent(request, ISC_R_CANCELED);
+	}
+	UNLOCK(&request->requestmgr->locks[request->hash]);
+
+	/* attached in dns_request_create/_createraw() */
+	req_detach(&(dns_request_t *){ request });
+}
+
+static void
+req_senddone(isc_result_t eresult, isc_region_t *region, void *arg) {
+	dns_request_t *request = (dns_request_t *)arg;
+
+	REQUIRE(VALID_REQUEST(request));
+	REQUIRE(DNS_REQUEST_SENDING(request));
+
+	UNUSED(region);
+
+	req_log(ISC_LOG_DEBUG(3), "req_senddone: request %p", request);
+
+	LOCK(&request->requestmgr->locks[request->hash]);
+	request->flags &= ~DNS_REQUEST_F_SENDING;
+
+	if (DNS_REQUEST_CANCELED(request)) {
+		if (eresult == ISC_R_TIMEDOUT) {
+			req_sendevent(request, eresult);
+		} else {
+			req_sendevent(request, ISC_R_CANCELED);
+		}
+	} else if (eresult != ISC_R_SUCCESS) {
+		request_cancel(request);
+		req_sendevent(request, ISC_R_CANCELED);
+	}
+
+	UNLOCK(&request->requestmgr->locks[request->hash]);
+
+	/* attached in req_send() */
+	req_detach(&request);
+}
+
+static void
+req_response(isc_result_t result, isc_region_t *region, void *arg) {
+	dns_request_t *request = (dns_request_t *)arg;
+
+	if (result == ISC_R_CANCELED) {
+		return;
+	}
+
+	req_log(ISC_LOG_DEBUG(3), "req_response: request %p: %s", request,
+		isc_result_totext(result));
+
+	REQUIRE(VALID_REQUEST(request));
+
+	if (result == ISC_R_TIMEDOUT) {
+		LOCK(&request->requestmgr->locks[request->hash]);
+		if (request->udpcount > 1 &&
+		    (request->flags & DNS_REQUEST_F_TCP) == 0)
+		{
+			request->udpcount -= 1;
+			dns_dispatch_resume(request->dispentry,
+					    request->timeout);
+			if (!DNS_REQUEST_SENDING(request)) {
+				req_send(request);
+			}
+			UNLOCK(&request->requestmgr->locks[request->hash]);
+			return;
+		}
+
+		/* The lock is unlocked below */
+		goto done;
+	}
+
+	LOCK(&request->requestmgr->locks[request->hash]);
+
+	if (result != ISC_R_SUCCESS) {
+		goto done;
+	}
+
+	/*
+	 * Copy region to request.
+	 */
+	isc_buffer_allocate(request->mctx, &request->answer, region->length);
+	result = isc_buffer_copyregion(request->answer, region);
+	if (result != ISC_R_SUCCESS) {
+		isc_buffer_free(&request->answer);
+	}
+
+done:
+	/*
+	 * Cleanup.
+	 */
+	if (request->dispentry != NULL) {
+		dns_dispatch_done(&request->dispentry);
+	}
+	request_cancel(request);
+
+	/*
+	 * Send completion event.
+	 */
+	req_sendevent(request, result);
+	UNLOCK(&request->requestmgr->locks[request->hash]);
+}
+
+static void
+req_sendevent(dns_request_t *request, isc_result_t result) {
+	isc_task_t *task = NULL;
+
+	REQUIRE(VALID_REQUEST(request));
+
+	if (request->event == NULL) {
+		return;
+	}
+
+	req_log(ISC_LOG_DEBUG(3), "req_sendevent: request %p", request);
+
+	/*
+	 * Lock held by caller.
+	 */
+	task = request->event->ev_sender;
+	request->event->ev_sender = request;
+	request->event->result = result;
+
+	isc_task_sendanddetach(&task, (isc_event_t **)&request->event);
+}
+
+static void
+req_attach(dns_request_t *source, dns_request_t **targetp) {
+	REQUIRE(VALID_REQUEST(source));
+	REQUIRE(targetp != NULL && *targetp == NULL);
+
+	isc_refcount_increment(&source->references);
+
+	*targetp = source;
+}
+
+static void
+req_detach(dns_request_t **requestp) {
+	dns_request_t *request = NULL;
+	uint_fast32_t ref;
+
+	REQUIRE(requestp != NULL && VALID_REQUEST(*requestp));
+
+	request = *requestp;
+	*requestp = NULL;
+
+	ref = isc_refcount_decrement(&request->references);
+
+	if (request->requestmgr != NULL &&
+	    atomic_load_acquire(&request->requestmgr->exiting))
+	{
+		/* We are shutting down and this was last request */
+		LOCK(&request->requestmgr->lock);
+		if (ISC_LIST_EMPTY(request->requestmgr->requests)) {
+			send_shutdown_events(request->requestmgr);
+		}
+		UNLOCK(&request->requestmgr->lock);
+	}
+
+	if (ref == 1) {
+		req_destroy(request);
+	}
+}
+
+static void
+req_destroy(dns_request_t *request) {
+	REQUIRE(VALID_REQUEST(request));
+
+	req_log(ISC_LOG_DEBUG(3), "req_destroy: request %p", request);
+
+	isc_refcount_destroy(&request->references);
+
+	request->magic = 0;
+	if (request->query != NULL) {
+		isc_buffer_free(&request->query);
+	}
+	if (request->answer != NULL) {
+		isc_buffer_free(&request->answer);
+	}
+	if (request->event != NULL) {
+		isc_event_free((isc_event_t **)&request->event);
+	}
+	if (request->dispentry != NULL) {
+		dns_dispatch_done(&request->dispentry);
+	}
+	if (request->dispatch != NULL) {
+		dns_dispatch_detach(&request->dispatch);
+	}
+	if (request->tsig != NULL) {
+		isc_buffer_free(&request->tsig);
+	}
+	if (request->tsigkey != NULL) {
+		dns_tsigkey_detach(&request->tsigkey);
+	}
+	if (request->requestmgr != NULL) {
+		dns_requestmgr_detach(&request->requestmgr);
+	}
+	isc_mem_putanddetach(&request->mctx, request, sizeof(*request));
+}
+
+static void
+req_log(int level, const char *fmt, ...) {
+	va_list ap;
+
+	va_start(ap, fmt);
+	isc_log_vwrite(dns_lctx, DNS_LOGCATEGORY_GENERAL, DNS_LOGMODULE_REQUEST,
+		       level, fmt, ap);
+	va_end(ap);
+}