Flatten bind9 vendor work area

1 files changed, 2674 insertions, 0 deletions

diff --git a/lib/dns/dispatch.c b/lib/dns/dispatch.c
new file mode 100644
index 0000000..f3ef091
--- /dev/null
+++ b/lib/dns/dispatch.c
@@ -0,0 +1,2674 @@
+/*
+ * Copyright (C) 2004-2007  Internet Systems Consortium, Inc. ("ISC")
+ * Copyright (C) 1999-2003  Internet Software Consortium.
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
+ * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+ * AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
+ * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
+ * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
+ * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+ * PERFORMANCE OF THIS SOFTWARE.
+ */
+
+/* $Id: dispatch.c,v 1.116.18.19 2007/08/28 07:20:04 tbox Exp $ */
+
+/*! \file */
+
+#include <config.h>
+
+#include <stdlib.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#include <isc/entropy.h>
+#include <isc/mem.h>
+#include <isc/mutex.h>
+#include <isc/print.h>
+#include <isc/string.h>
+#include <isc/task.h>
+#include <isc/time.h>
+#include <isc/util.h>
+
+#include <dns/acl.h>
+#include <dns/dispatch.h>
+#include <dns/events.h>
+#include <dns/log.h>
+#include <dns/message.h>
+#include <dns/portlist.h>
+#include <dns/tcpmsg.h>
+#include <dns/types.h>
+
+typedef ISC_LIST(dns_dispentry_t)	dns_displist_t;
+
+typedef struct dns_nsid {
+	isc_uint16_t	nsid_state;
+	isc_uint16_t	*nsid_vtable;
+	isc_uint16_t	*nsid_pool;
+	isc_uint16_t	nsid_a1, nsid_a2, nsid_a3;
+	isc_uint16_t	nsid_c1, nsid_c2, nsid_c3;
+	isc_uint16_t	nsid_state2;
+	isc_boolean_t	nsid_usepool;
+} dns_nsid_t;
+
+typedef struct dns_qid {
+	unsigned int	magic;
+	unsigned int	qid_nbuckets;	/*%< hash table size */
+	unsigned int	qid_increment;	/*%< id increment on collision */
+	isc_mutex_t	lock;
+	dns_nsid_t      nsid;
+	dns_displist_t	*qid_table;	/*%< the table itself */
+} dns_qid_t;
+
+struct dns_dispatchmgr {
+	/* Unlocked. */
+	unsigned int			magic;
+	isc_mem_t		       *mctx;
+	dns_acl_t		       *blackhole;
+	dns_portlist_t		       *portlist;
+
+	/* Locked by "lock". */
+	isc_mutex_t			lock;
+	unsigned int			state;
+	ISC_LIST(dns_dispatch_t)	list;
+
+	/* locked by buffer lock */
+	dns_qid_t			*qid;
+	isc_mutex_t			buffer_lock;
+	unsigned int			buffers;    /*%< allocated buffers */
+	unsigned int			buffersize; /*%< size of each buffer */
+	unsigned int			maxbuffers; /*%< max buffers */
+
+	/* Locked internally. */
+	isc_mutex_t			pool_lock;
+	isc_mempool_t		       *epool;	/*%< memory pool for events */
+	isc_mempool_t		       *rpool;	/*%< memory pool for replies */
+	isc_mempool_t		       *dpool;  /*%< dispatch allocations */
+	isc_mempool_t		       *bpool;	/*%< memory pool for buffers */
+
+	isc_entropy_t		       *entropy; /*%< entropy source */
+};
+
+#define MGR_SHUTTINGDOWN		0x00000001U
+#define MGR_IS_SHUTTINGDOWN(l)	(((l)->state & MGR_SHUTTINGDOWN) != 0)
+
+#define IS_PRIVATE(d)	(((d)->attributes & DNS_DISPATCHATTR_PRIVATE) != 0)
+
+struct dns_dispentry {
+	unsigned int			magic;
+	dns_dispatch_t		       *disp;
+	dns_messageid_t			id;
+	unsigned int			bucket;
+	isc_sockaddr_t			host;
+	isc_task_t		       *task;
+	isc_taskaction_t		action;
+	void			       *arg;
+	isc_boolean_t			item_out;
+	ISC_LIST(dns_dispatchevent_t)	items;
+	ISC_LINK(dns_dispentry_t)	link;
+};
+
+#define INVALID_BUCKET		(0xffffdead)
+
+struct dns_dispatch {
+	/* Unlocked. */
+	unsigned int		magic;		/*%< magic */
+	dns_dispatchmgr_t      *mgr;		/*%< dispatch manager */
+	isc_task_t	       *task;		/*%< internal task */
+	isc_socket_t	       *socket;		/*%< isc socket attached to */
+	isc_sockaddr_t		local;		/*%< local address */
+	unsigned int		maxrequests;	/*%< max requests */
+	isc_event_t	       *ctlevent;
+
+	/*% Locked by mgr->lock. */
+	ISC_LINK(dns_dispatch_t) link;
+
+	/* Locked by "lock". */
+	isc_mutex_t		lock;		/*%< locks all below */
+	isc_sockettype_t	socktype;
+	unsigned int		attributes;
+	unsigned int		refcount;	/*%< number of users */
+	dns_dispatchevent_t    *failsafe_ev;	/*%< failsafe cancel event */
+	unsigned int		shutting_down : 1,
+				shutdown_out : 1,
+				connected : 1,
+				tcpmsg_valid : 1,
+				recv_pending : 1; /*%< is a recv() pending? */
+	isc_result_t		shutdown_why;
+	unsigned int		requests;	/*%< how many requests we have */
+	unsigned int		tcpbuffers;	/*%< allocated buffers */
+	dns_tcpmsg_t		tcpmsg;		/*%< for tcp streams */
+	dns_qid_t		*qid;
+};
+
+#define QID_MAGIC		ISC_MAGIC('Q', 'i', 'd', ' ')
+#define VALID_QID(e)		ISC_MAGIC_VALID((e), QID_MAGIC)
+
+#define RESPONSE_MAGIC		ISC_MAGIC('D', 'r', 's', 'p')
+#define VALID_RESPONSE(e)	ISC_MAGIC_VALID((e), RESPONSE_MAGIC)
+
+#define DISPATCH_MAGIC		ISC_MAGIC('D', 'i', 's', 'p')
+#define VALID_DISPATCH(e)	ISC_MAGIC_VALID((e), DISPATCH_MAGIC)
+
+#define DNS_DISPATCHMGR_MAGIC	ISC_MAGIC('D', 'M', 'g', 'r')
+#define VALID_DISPATCHMGR(e)	ISC_MAGIC_VALID((e), DNS_DISPATCHMGR_MAGIC)
+
+#define DNS_QID(disp) ((disp)->socktype == isc_sockettype_tcp) ? \
+		       (disp)->qid : (disp)->mgr->qid
+/*
+ * Statics.
+ */
+static dns_dispentry_t *bucket_search(dns_qid_t *, isc_sockaddr_t *,
+				      dns_messageid_t, unsigned int);
+static isc_boolean_t destroy_disp_ok(dns_dispatch_t *);
+static void destroy_disp(isc_task_t *task, isc_event_t *event);
+static void udp_recv(isc_task_t *, isc_event_t *);
+static void tcp_recv(isc_task_t *, isc_event_t *);
+static void startrecv(dns_dispatch_t *);
+static dns_messageid_t dns_randomid(dns_nsid_t *);
+static isc_uint32_t dns_hash(dns_qid_t *, isc_sockaddr_t *, dns_messageid_t);
+static void free_buffer(dns_dispatch_t *disp, void *buf, unsigned int len);
+static void *allocate_udp_buffer(dns_dispatch_t *disp);
+static inline void free_event(dns_dispatch_t *disp, dns_dispatchevent_t *ev);
+static inline dns_dispatchevent_t *allocate_event(dns_dispatch_t *disp);
+static void do_cancel(dns_dispatch_t *disp);
+static dns_dispentry_t *linear_first(dns_qid_t *disp);
+static dns_dispentry_t *linear_next(dns_qid_t *disp,
+				    dns_dispentry_t *resp);
+static void dispatch_free(dns_dispatch_t **dispp);
+static isc_result_t dispatch_createudp(dns_dispatchmgr_t *mgr,
+				       isc_socketmgr_t *sockmgr,
+				       isc_taskmgr_t *taskmgr,
+				       isc_sockaddr_t *localaddr,
+				       unsigned int maxrequests,
+				       unsigned int attributes,
+				       dns_dispatch_t **dispp);
+static isc_boolean_t destroy_mgr_ok(dns_dispatchmgr_t *mgr);
+static void destroy_mgr(dns_dispatchmgr_t **mgrp);
+static isc_result_t qid_allocate(dns_dispatchmgr_t *mgr, unsigned int buckets,
+				 unsigned int increment, isc_boolean_t usepool,
+				 dns_qid_t **qidp);
+static void qid_destroy(isc_mem_t *mctx, dns_qid_t **qidp);
+static isc_uint16_t nsid_next(dns_nsid_t *nsid);
+static isc_result_t nsid_init(isc_mem_t *mctx, dns_nsid_t *nsid, isc_boolean_t usepool);
+static void nsid_destroy(isc_mem_t *mctx, dns_nsid_t *nsid);
+
+#define LVL(x) ISC_LOG_DEBUG(x)
+
+static void
+mgr_log(dns_dispatchmgr_t *mgr, int level, const char *fmt, ...)
+     ISC_FORMAT_PRINTF(3, 4);
+
+static void
+mgr_log(dns_dispatchmgr_t *mgr, int level, const char *fmt, ...) {
+	char msgbuf[2048];
+	va_list ap;
+
+	if (! isc_log_wouldlog(dns_lctx, level))
+		return;
+
+	va_start(ap, fmt);
+	vsnprintf(msgbuf, sizeof(msgbuf), fmt, ap);
+	va_end(ap);
+
+	isc_log_write(dns_lctx,
+		      DNS_LOGCATEGORY_DISPATCH, DNS_LOGMODULE_DISPATCH,
+		      level, "dispatchmgr %p: %s", mgr, msgbuf);
+}
+
+static void
+dispatch_log(dns_dispatch_t *disp, int level, const char *fmt, ...)
+     ISC_FORMAT_PRINTF(3, 4);
+
+static void
+dispatch_log(dns_dispatch_t *disp, int level, const char *fmt, ...) {
+	char msgbuf[2048];
+	va_list ap;
+
+	if (! isc_log_wouldlog(dns_lctx, level))
+		return;
+
+	va_start(ap, fmt);
+	vsnprintf(msgbuf, sizeof(msgbuf), fmt, ap);
+	va_end(ap);
+
+	isc_log_write(dns_lctx,
+		      DNS_LOGCATEGORY_DISPATCH, DNS_LOGMODULE_DISPATCH,
+		      level, "dispatch %p: %s", disp, msgbuf);
+}
+
+static void
+request_log(dns_dispatch_t *disp, dns_dispentry_t *resp,
+	    int level, const char *fmt, ...)
+     ISC_FORMAT_PRINTF(4, 5);
+
+static void
+request_log(dns_dispatch_t *disp, dns_dispentry_t *resp,
+	    int level, const char *fmt, ...)
+{
+	char msgbuf[2048];
+	char peerbuf[256];
+	va_list ap;
+
+	if (! isc_log_wouldlog(dns_lctx, level))
+		return;
+
+	va_start(ap, fmt);
+	vsnprintf(msgbuf, sizeof(msgbuf), fmt, ap);
+	va_end(ap);
+
+	if (VALID_RESPONSE(resp)) {
+		isc_sockaddr_format(&resp->host, peerbuf, sizeof(peerbuf));
+		isc_log_write(dns_lctx, DNS_LOGCATEGORY_DISPATCH,
+			      DNS_LOGMODULE_DISPATCH, level,
+			      "dispatch %p response %p %s: %s", disp, resp,
+			      peerbuf, msgbuf);
+	} else {
+		isc_log_write(dns_lctx, DNS_LOGCATEGORY_DISPATCH,
+			      DNS_LOGMODULE_DISPATCH, level,
+			      "dispatch %p req/resp %p: %s", disp, resp,
+			      msgbuf);
+	}
+}
+
+/*
+ * Return an unpredictable message ID.
+ */
+static dns_messageid_t
+dns_randomid(dns_nsid_t *nsid) {
+	isc_uint32_t id;
+
+	id = nsid_next(nsid);
+
+	return ((dns_messageid_t)id);
+}
+
+/*
+ * Return a hash of the destination and message id.
+ */
+static isc_uint32_t
+dns_hash(dns_qid_t *qid, isc_sockaddr_t *dest, dns_messageid_t id) {
+	unsigned int ret;
+
+	ret = isc_sockaddr_hash(dest, ISC_TRUE);
+	ret ^= id;
+	ret %= qid->qid_nbuckets;
+
+	INSIST(ret < qid->qid_nbuckets);
+
+	return (ret);
+}
+
+/*
+ * Find the first entry in 'qid'.  Returns NULL if there are no entries.
+ */
+static dns_dispentry_t *
+linear_first(dns_qid_t *qid) {
+	dns_dispentry_t *ret;
+	unsigned int bucket;
+
+	bucket = 0;
+
+	while (bucket < qid->qid_nbuckets) {
+		ret = ISC_LIST_HEAD(qid->qid_table[bucket]);
+		if (ret != NULL)
+			return (ret);
+		bucket++;
+	}
+
+	return (NULL);
+}
+
+/*
+ * Find the next entry after 'resp' in 'qid'.  Return NULL if there are
+ * no more entries.
+ */
+static dns_dispentry_t *
+linear_next(dns_qid_t *qid, dns_dispentry_t *resp) {
+	dns_dispentry_t *ret;
+	unsigned int bucket;
+
+	ret = ISC_LIST_NEXT(resp, link);
+	if (ret != NULL)
+		return (ret);
+
+	bucket = resp->bucket;
+	bucket++;
+	while (bucket < qid->qid_nbuckets) {
+		ret = ISC_LIST_HEAD(qid->qid_table[bucket]);
+		if (ret != NULL)
+			return (ret);
+		bucket++;
+	}
+
+	return (NULL);
+}
+
+/*
+ * The dispatch must be locked.
+ */
+static isc_boolean_t
+destroy_disp_ok(dns_dispatch_t *disp)
+{
+	if (disp->refcount != 0)
+		return (ISC_FALSE);
+
+	if (disp->recv_pending != 0)
+		return (ISC_FALSE);
+
+	if (disp->shutting_down == 0)
+		return (ISC_FALSE);
+
+	return (ISC_TRUE);
+}
+
+
+/*
+ * Called when refcount reaches 0 (and safe to destroy).
+ *
+ * The dispatcher must not be locked.
+ * The manager must be locked.
+ */
+static void
+destroy_disp(isc_task_t *task, isc_event_t *event) {
+	dns_dispatch_t *disp;
+	dns_dispatchmgr_t *mgr;
+	isc_boolean_t killmgr;
+
+	INSIST(event->ev_type == DNS_EVENT_DISPATCHCONTROL);
+
+	UNUSED(task);
+
+	disp = event->ev_arg;
+	mgr = disp->mgr;
+
+	LOCK(&mgr->lock);
+	ISC_LIST_UNLINK(mgr->list, disp, link);
+
+	dispatch_log(disp, LVL(90),
+		     "shutting down; detaching from sock %p, task %p",
+		     disp->socket, disp->task);
+
+	isc_socket_detach(&disp->socket);
+	isc_task_detach(&disp->task);
+	isc_event_free(&event);
+
+	dispatch_free(&disp);
+
+	killmgr = destroy_mgr_ok(mgr);
+	UNLOCK(&mgr->lock);
+	if (killmgr)
+		destroy_mgr(&mgr);
+}
+
+
+/*
+ * Find an entry for query ID 'id' and socket address 'dest' in 'qid'.
+ * Return NULL if no such entry exists.
+ */
+static dns_dispentry_t *
+bucket_search(dns_qid_t *qid, isc_sockaddr_t *dest, dns_messageid_t id,
+	      unsigned int bucket)
+{
+	dns_dispentry_t *res;
+
+	REQUIRE(bucket < qid->qid_nbuckets);
+
+	res = ISC_LIST_HEAD(qid->qid_table[bucket]);
+
+	while (res != NULL) {
+		if ((res->id == id) && isc_sockaddr_equal(dest, &res->host))
+			return (res);
+		res = ISC_LIST_NEXT(res, link);
+	}
+
+	return (NULL);
+}
+
+static void
+free_buffer(dns_dispatch_t *disp, void *buf, unsigned int len) {
+	INSIST(buf != NULL && len != 0);
+
+
+	switch (disp->socktype) {
+	case isc_sockettype_tcp:
+		INSIST(disp->tcpbuffers > 0);
+		disp->tcpbuffers--;
+		isc_mem_put(disp->mgr->mctx, buf, len);
+		break;
+	case isc_sockettype_udp:
+		LOCK(&disp->mgr->buffer_lock);
+		INSIST(disp->mgr->buffers > 0);
+		INSIST(len == disp->mgr->buffersize);
+		disp->mgr->buffers--;
+		isc_mempool_put(disp->mgr->bpool, buf);
+		UNLOCK(&disp->mgr->buffer_lock);
+		break;
+	default:
+		INSIST(0);
+		break;
+	}
+}
+
+static void *
+allocate_udp_buffer(dns_dispatch_t *disp) {
+	void *temp;
+
+	LOCK(&disp->mgr->buffer_lock);
+	temp = isc_mempool_get(disp->mgr->bpool);
+
+	if (temp != NULL)
+		disp->mgr->buffers++;
+	UNLOCK(&disp->mgr->buffer_lock);
+
+	return (temp);
+}
+
+static inline void
+free_event(dns_dispatch_t *disp, dns_dispatchevent_t *ev) {
+	if (disp->failsafe_ev == ev) {
+		INSIST(disp->shutdown_out == 1);
+		disp->shutdown_out = 0;
+
+		return;
+	}
+
+	isc_mempool_put(disp->mgr->epool, ev);
+}
+
+static inline dns_dispatchevent_t *
+allocate_event(dns_dispatch_t *disp) {
+	dns_dispatchevent_t *ev;
+
+	ev = isc_mempool_get(disp->mgr->epool);
+	if (ev == NULL)
+		return (NULL);
+	ISC_EVENT_INIT(ev, sizeof(*ev), 0, NULL, 0,
+		       NULL, NULL, NULL, NULL, NULL);
+
+	return (ev);
+}
+
+/*
+ * General flow:
+ *
+ * If I/O result == CANCELED or error, free the buffer.
+ *
+ * If query, free the buffer, restart.
+ *
+ * If response:
+ *	Allocate event, fill in details.
+ *		If cannot allocate, free buffer, restart.
+ *	find target.  If not found, free buffer, restart.
+ *	if event queue is not empty, queue.  else, send.
+ *	restart.
+ */
+static void
+udp_recv(isc_task_t *task, isc_event_t *ev_in) {
+	isc_socketevent_t *ev = (isc_socketevent_t *)ev_in;
+	dns_dispatch_t *disp = ev_in->ev_arg;
+	dns_messageid_t id;
+	isc_result_t dres;
+	isc_buffer_t source;
+	unsigned int flags;
+	dns_dispentry_t *resp;
+	dns_dispatchevent_t *rev;
+	unsigned int bucket;
+	isc_boolean_t killit;
+	isc_boolean_t queue_response;
+	dns_dispatchmgr_t *mgr;
+	dns_qid_t *qid;
+	isc_netaddr_t netaddr;
+	int match;
+
+	UNUSED(task);
+
+	LOCK(&disp->lock);
+
+	mgr = disp->mgr;
+	qid = mgr->qid;
+
+	dispatch_log(disp, LVL(90),
+		     "got packet: requests %d, buffers %d, recvs %d",
+		     disp->requests, disp->mgr->buffers, disp->recv_pending);
+
+	if (ev->ev_type == ISC_SOCKEVENT_RECVDONE) {
+		/*
+		 * Unless the receive event was imported from a listening
+		 * interface, in which case the event type is
+		 * DNS_EVENT_IMPORTRECVDONE, receive operation must be pending.
+		 */
+		INSIST(disp->recv_pending != 0);
+		disp->recv_pending = 0;
+	}
+
+	if (disp->shutting_down) {
+		/*
+		 * This dispatcher is shutting down.
+		 */
+		free_buffer(disp, ev->region.base, ev->region.length);
+
+		isc_event_free(&ev_in);
+		ev = NULL;
+
+		killit = destroy_disp_ok(disp);
+		UNLOCK(&disp->lock);
+		if (killit)
+			isc_task_send(disp->task, &disp->ctlevent);
+
+		return;
+	}
+
+	if (ev->result != ISC_R_SUCCESS) {
+		free_buffer(disp, ev->region.base, ev->region.length);
+
+		if (ev->result != ISC_R_CANCELED)
+			dispatch_log(disp, ISC_LOG_ERROR,
+				     "odd socket result in udp_recv(): %s",
+				     isc_result_totext(ev->result));
+
+		UNLOCK(&disp->lock);
+		isc_event_free(&ev_in);
+		return;
+	}
+
+	/*
+	 * If this is from a blackholed address, drop it.
+	 */
+	isc_netaddr_fromsockaddr(&netaddr, &ev->address);
+	if (disp->mgr->blackhole != NULL &&
+	    dns_acl_match(&netaddr, NULL, disp->mgr->blackhole,
+		    	  NULL, &match, NULL) == ISC_R_SUCCESS &&
+	    match > 0)
+	{
+		if (isc_log_wouldlog(dns_lctx, LVL(10))) {
+			char netaddrstr[ISC_NETADDR_FORMATSIZE];
+			isc_netaddr_format(&netaddr, netaddrstr,
+					   sizeof(netaddrstr));
+			dispatch_log(disp, LVL(10),
+				     "blackholed packet from %s",
+				     netaddrstr);
+		}
+		free_buffer(disp, ev->region.base, ev->region.length);
+		goto restart;
+	}
+
+	/*
+	 * Peek into the buffer to see what we can see.
+	 */
+	isc_buffer_init(&source, ev->region.base, ev->region.length);
+	isc_buffer_add(&source, ev->n);
+	dres = dns_message_peekheader(&source, &id, &flags);
+	if (dres != ISC_R_SUCCESS) {
+		free_buffer(disp, ev->region.base, ev->region.length);
+		dispatch_log(disp, LVL(10), "got garbage packet");
+		goto restart;
+	}
+
+	dispatch_log(disp, LVL(92),
+		     "got valid DNS message header, /QR %c, id %u",
+		     ((flags & DNS_MESSAGEFLAG_QR) ? '1' : '0'), id);
+
+	/*
+	 * Look at flags.  If query, drop it. If response,
+	 * look to see where it goes.
+	 */
+	queue_response = ISC_FALSE;
+	if ((flags & DNS_MESSAGEFLAG_QR) == 0) {
+		/* query */
+		free_buffer(disp, ev->region.base, ev->region.length);
+		goto restart;
+	}
+
+	dns_dispatch_hash(&ev->timestamp, sizeof(&ev->timestamp));
+	dns_dispatch_hash(ev->region.base, ev->region.length);
+
+	/* response */
+	bucket = dns_hash(qid, &ev->address, id);
+	LOCK(&qid->lock);
+	resp = bucket_search(qid, &ev->address, id, bucket);
+	dispatch_log(disp, LVL(90),
+		     "search for response in bucket %d: %s",
+		     bucket, (resp == NULL ? "not found" : "found"));
+
+	if (resp == NULL) {
+		free_buffer(disp, ev->region.base, ev->region.length);
+		goto unlock;
+	} 
+
+	/*
+	 * Now that we have the original dispatch the query was sent
+	 * from check that the address and port the response was
+	 * sent to make sense.
+	 */
+	if (disp != resp->disp) {
+		isc_sockaddr_t a1;
+		isc_sockaddr_t a2;
+		
+		/*
+		 * Check that the socket types and ports match.
+		 */
+		if (disp->socktype != resp->disp->socktype ||
+		    isc_sockaddr_getport(&disp->local) !=
+		    isc_sockaddr_getport(&resp->disp->local)) {
+			free_buffer(disp, ev->region.base, ev->region.length);
+			goto unlock;
+		}
+
+		/*
+		 * If both dispatches are bound to an address then fail as
+		 * the addresses can't be equal (enforced by the IP stack).  
+		 *
+		 * Note under Linux a packet can be sent out via IPv4 socket
+		 * and the response be received via a IPv6 socket.
+		 * 
+		 * Requests sent out via IPv6 should always come back in
+		 * via IPv6.
+		 */
+		if (isc_sockaddr_pf(&resp->disp->local) == PF_INET6 &&
+		    isc_sockaddr_pf(&disp->local) != PF_INET6) {
+			free_buffer(disp, ev->region.base, ev->region.length);
+			goto unlock;
+		}
+		isc_sockaddr_anyofpf(&a1, isc_sockaddr_pf(&resp->disp->local));
+		isc_sockaddr_anyofpf(&a2, isc_sockaddr_pf(&disp->local));
+		if (!isc_sockaddr_eqaddr(&a1, &resp->disp->local) &&
+		    !isc_sockaddr_eqaddr(&a2, &disp->local)) {
+			free_buffer(disp, ev->region.base, ev->region.length);
+			goto unlock;
+		}
+	}
+
+	queue_response = resp->item_out;
+	rev = allocate_event(resp->disp);
+	if (rev == NULL) {
+		free_buffer(disp, ev->region.base, ev->region.length);
+		goto unlock;
+	}
+
+	/*
+	 * At this point, rev contains the event we want to fill in, and
+	 * resp contains the information on the place to send it to.
+	 * Send the event off.
+	 */
+	isc_buffer_init(&rev->buffer, ev->region.base, ev->region.length);
+	isc_buffer_add(&rev->buffer, ev->n);
+	rev->result = ISC_R_SUCCESS;
+	rev->id = id;
+	rev->addr = ev->address;
+	rev->pktinfo = ev->pktinfo;
+	rev->attributes = ev->attributes;
+	if (queue_response) {
+		ISC_LIST_APPEND(resp->items, rev, ev_link);
+	} else {
+		ISC_EVENT_INIT(rev, sizeof(*rev), 0, NULL,
+			       DNS_EVENT_DISPATCH,
+			       resp->action, resp->arg, resp, NULL, NULL);
+		request_log(disp, resp, LVL(90),
+			    "[a] Sent event %p buffer %p len %d to task %p",
+			    rev, rev->buffer.base, rev->buffer.length,
+			    resp->task);
+		resp->item_out = ISC_TRUE;
+		isc_task_send(resp->task, ISC_EVENT_PTR(&rev));
+	}
+ unlock:
+	UNLOCK(&qid->lock);
+
+	/*
+	 * Restart recv() to get the next packet.
+	 */
+ restart:
+	startrecv(disp);
+
+	UNLOCK(&disp->lock);
+
+	isc_event_free(&ev_in);
+}
+
+/*
+ * General flow:
+ *
+ * If I/O result == CANCELED, EOF, or error, notify everyone as the
+ * various queues drain.
+ *
+ * If query, restart.
+ *
+ * If response:
+ *	Allocate event, fill in details.
+ *		If cannot allocate, restart.
+ *	find target.  If not found, restart.
+ *	if event queue is not empty, queue.  else, send.
+ *	restart.
+ */
+static void
+tcp_recv(isc_task_t *task, isc_event_t *ev_in) {
+	dns_dispatch_t *disp = ev_in->ev_arg;
+	dns_tcpmsg_t *tcpmsg = &disp->tcpmsg;
+	dns_messageid_t id;
+	isc_result_t dres;
+	unsigned int flags;
+	dns_dispentry_t *resp;
+	dns_dispatchevent_t *rev;
+	unsigned int bucket;
+	isc_boolean_t killit;
+	isc_boolean_t queue_response;
+	dns_qid_t *qid;
+	int level;
+	char buf[ISC_SOCKADDR_FORMATSIZE];
+
+	UNUSED(task);
+
+	REQUIRE(VALID_DISPATCH(disp));
+
+	qid = disp->qid;
+
+	dispatch_log(disp, LVL(90),
+		     "got TCP packet: requests %d, buffers %d, recvs %d",
+		     disp->requests, disp->tcpbuffers, disp->recv_pending);
+
+	LOCK(&disp->lock);
+
+	INSIST(disp->recv_pending != 0);
+	disp->recv_pending = 0;
+
+	if (disp->refcount == 0) {
+		/*
+		 * This dispatcher is shutting down.  Force cancelation.
+		 */
+		tcpmsg->result = ISC_R_CANCELED;
+	}
+
+	if (tcpmsg->result != ISC_R_SUCCESS) {
+		switch (tcpmsg->result) {
+		case ISC_R_CANCELED:
+			break;
+			
+		case ISC_R_EOF:
+			dispatch_log(disp, LVL(90), "shutting down on EOF");
+			do_cancel(disp);
+			break;
+
+		case ISC_R_CONNECTIONRESET:
+			level = ISC_LOG_INFO;
+			goto logit;
+
+		default:
+			level = ISC_LOG_ERROR;
+		logit:
+			isc_sockaddr_format(&tcpmsg->address, buf, sizeof(buf));
+			dispatch_log(disp, level, "shutting down due to TCP "
+				     "receive error: %s: %s", buf,
+				     isc_result_totext(tcpmsg->result));
+			do_cancel(disp);
+			break;
+		}
+
+		/*
+		 * The event is statically allocated in the tcpmsg
+		 * structure, and destroy_disp() frees the tcpmsg, so we must
+		 * free the event *before* calling destroy_disp().
+		 */
+		isc_event_free(&ev_in);
+
+		disp->shutting_down = 1;
+		disp->shutdown_why = tcpmsg->result;
+
+		/*
+		 * If the recv() was canceled pass the word on.
+		 */
+		killit = destroy_disp_ok(disp);
+		UNLOCK(&disp->lock);
+		if (killit)
+			isc_task_send(disp->task, &disp->ctlevent);
+		return;
+	}
+
+	dispatch_log(disp, LVL(90), "result %d, length == %d, addr = %p",
+		     tcpmsg->result,
+		     tcpmsg->buffer.length, tcpmsg->buffer.base);
+
+	/*
+	 * Peek into the buffer to see what we can see.
+	 */
+	dres = dns_message_peekheader(&tcpmsg->buffer, &id, &flags);
+	if (dres != ISC_R_SUCCESS) {
+		dispatch_log(disp, LVL(10), "got garbage packet");
+		goto restart;
+	}
+
+	dispatch_log(disp, LVL(92),
+		     "got valid DNS message header, /QR %c, id %u",
+		     ((flags & DNS_MESSAGEFLAG_QR) ? '1' : '0'), id);
+
+	/*
+	 * Allocate an event to send to the query or response client, and
+	 * allocate a new buffer for our use.
+	 */
+
+	/*
+	 * Look at flags.  If query, drop it. If response,
+	 * look to see where it goes.
+	 */
+	queue_response = ISC_FALSE;
+	if ((flags & DNS_MESSAGEFLAG_QR) == 0) {
+		/*
+		 * Query.
+		 */
+		goto restart;
+	}
+
+	dns_dispatch_hash(tcpmsg->buffer.base, tcpmsg->buffer.length);
+
+	/*
+	 * Response.
+	 */
+	bucket = dns_hash(qid, &tcpmsg->address, id);
+	LOCK(&qid->lock);
+	resp = bucket_search(qid, &tcpmsg->address, id, bucket);
+	dispatch_log(disp, LVL(90),
+		     "search for response in bucket %d: %s",
+		     bucket, (resp == NULL ? "not found" : "found"));
+
+	if (resp == NULL)
+		goto unlock;
+	queue_response = resp->item_out;
+	rev = allocate_event(disp);
+	if (rev == NULL)
+		goto unlock;
+
+	/*
+	 * At this point, rev contains the event we want to fill in, and
+	 * resp contains the information on the place to send it to.
+	 * Send the event off.
+	 */
+	dns_tcpmsg_keepbuffer(tcpmsg, &rev->buffer);
+	disp->tcpbuffers++;
+	rev->result = ISC_R_SUCCESS;
+	rev->id = id;
+	rev->addr = tcpmsg->address;
+	if (queue_response) {
+		ISC_LIST_APPEND(resp->items, rev, ev_link);
+	} else {
+		ISC_EVENT_INIT(rev, sizeof(*rev), 0, NULL, DNS_EVENT_DISPATCH,
+			       resp->action, resp->arg, resp, NULL, NULL);
+		request_log(disp, resp, LVL(90),
+			    "[b] Sent event %p buffer %p len %d to task %p",
+			    rev, rev->buffer.base, rev->buffer.length,
+			    resp->task);
+		resp->item_out = ISC_TRUE;
+		isc_task_send(resp->task, ISC_EVENT_PTR(&rev));
+	}
+ unlock:
+	UNLOCK(&qid->lock);
+
+	/*
+	 * Restart recv() to get the next packet.
+	 */
+ restart:
+	startrecv(disp);
+
+	UNLOCK(&disp->lock);
+
+	isc_event_free(&ev_in);
+}
+
+/*
+ * disp must be locked.
+ */
+static void
+startrecv(dns_dispatch_t *disp) {
+	isc_result_t res;
+	isc_region_t region;
+
+	if (disp->shutting_down == 1)
+		return;
+
+	if ((disp->attributes & DNS_DISPATCHATTR_NOLISTEN) != 0)
+		return;
+
+	if (disp->recv_pending != 0)
+		return;
+
+	if (disp->mgr->buffers >= disp->mgr->maxbuffers)
+		return;
+
+	switch (disp->socktype) {
+		/*
+		 * UDP reads are always maximal.
+		 */
+	case isc_sockettype_udp:
+		region.length = disp->mgr->buffersize;
+		region.base = allocate_udp_buffer(disp);
+		if (region.base == NULL)
+			return;
+		res = isc_socket_recv(disp->socket, &region, 1,
+				      disp->task, udp_recv, disp);
+		if (res != ISC_R_SUCCESS) {
+			free_buffer(disp, region.base, region.length);
+			disp->shutdown_why = res;
+			disp->shutting_down = 1;
+			do_cancel(disp);
+			return;
+		}
+		INSIST(disp->recv_pending == 0);
+		disp->recv_pending = 1;
+		break;
+
+	case isc_sockettype_tcp:
+		res = dns_tcpmsg_readmessage(&disp->tcpmsg, disp->task,
+					     tcp_recv, disp);
+		if (res != ISC_R_SUCCESS) {
+			disp->shutdown_why = res;
+			disp->shutting_down = 1;
+			do_cancel(disp);
+			return;
+		}
+		INSIST(disp->recv_pending == 0);
+		disp->recv_pending = 1;
+		break;
+	default:
+		INSIST(0);
+		break;
+	}
+}
+
+/*
+ * Mgr must be locked when calling this function.
+ */
+static isc_boolean_t
+destroy_mgr_ok(dns_dispatchmgr_t *mgr) {
+	mgr_log(mgr, LVL(90),
+		"destroy_mgr_ok: shuttingdown=%d, listnonempty=%d, "
+		"epool=%d, rpool=%d, dpool=%d",
+		MGR_IS_SHUTTINGDOWN(mgr), !ISC_LIST_EMPTY(mgr->list),
+		isc_mempool_getallocated(mgr->epool),
+		isc_mempool_getallocated(mgr->rpool),
+		isc_mempool_getallocated(mgr->dpool));
+	if (!MGR_IS_SHUTTINGDOWN(mgr))
+		return (ISC_FALSE);
+	if (!ISC_LIST_EMPTY(mgr->list))
+		return (ISC_FALSE);
+	if (isc_mempool_getallocated(mgr->epool) != 0)
+		return (ISC_FALSE);
+	if (isc_mempool_getallocated(mgr->rpool) != 0)
+		return (ISC_FALSE);
+	if (isc_mempool_getallocated(mgr->dpool) != 0)
+		return (ISC_FALSE);
+
+	return (ISC_TRUE);
+}
+
+/*
+ * Mgr must be unlocked when calling this function.
+ */
+static void
+destroy_mgr(dns_dispatchmgr_t **mgrp) {
+	isc_mem_t *mctx;
+	dns_dispatchmgr_t *mgr;
+
+	mgr = *mgrp;
+	*mgrp = NULL;
+
+	mctx = mgr->mctx;
+
+	mgr->magic = 0;
+	mgr->mctx = NULL;
+	DESTROYLOCK(&mgr->lock);
+	mgr->state = 0;
+
+	isc_mempool_destroy(&mgr->epool);
+	isc_mempool_destroy(&mgr->rpool);
+	isc_mempool_destroy(&mgr->dpool);
+	isc_mempool_destroy(&mgr->bpool);
+
+	DESTROYLOCK(&mgr->pool_lock);
+
+	if (mgr->entropy != NULL)
+		isc_entropy_detach(&mgr->entropy);
+	if (mgr->qid != NULL)
+		qid_destroy(mctx, &mgr->qid);
+
+	DESTROYLOCK(&mgr->buffer_lock);
+
+	if (mgr->blackhole != NULL)
+		dns_acl_detach(&mgr->blackhole);
+
+	if (mgr->portlist != NULL)
+		dns_portlist_detach(&mgr->portlist);
+
+	isc_mem_put(mctx, mgr, sizeof(dns_dispatchmgr_t));
+	isc_mem_detach(&mctx);
+}
+
+static isc_result_t
+create_socket(isc_socketmgr_t *mgr, isc_sockaddr_t *local,
+	      isc_socket_t **sockp)
+{
+	isc_socket_t *sock;
+	isc_result_t result;
+
+	sock = NULL;
+	result = isc_socket_create(mgr, isc_sockaddr_pf(local),
+				   isc_sockettype_udp, &sock);
+	if (result != ISC_R_SUCCESS)
+		return (result);
+
+#ifndef ISC_ALLOW_MAPPED
+	isc_socket_ipv6only(sock, ISC_TRUE);
+#endif
+	result = isc_socket_bind(sock, local);
+	if (result != ISC_R_SUCCESS) {
+		isc_socket_detach(&sock);
+		return (result);
+	}
+
+	*sockp = sock;
+	return (ISC_R_SUCCESS);
+}
+
+/*
+ * Publics.
+ */
+
+isc_result_t
+dns_dispatchmgr_create(isc_mem_t *mctx, isc_entropy_t *entropy,
+		       dns_dispatchmgr_t **mgrp)
+{
+	dns_dispatchmgr_t *mgr;
+	isc_result_t result;
+
+	REQUIRE(mctx != NULL);
+	REQUIRE(mgrp != NULL && *mgrp == NULL);
+
+	mgr = isc_mem_get(mctx, sizeof(dns_dispatchmgr_t));
+	if (mgr == NULL)
+		return (ISC_R_NOMEMORY);
+
+	mgr->mctx = NULL;
+	isc_mem_attach(mctx, &mgr->mctx);
+
+	mgr->blackhole = NULL;
+	mgr->portlist = NULL;
+
+	result = isc_mutex_init(&mgr->lock);
+	if (result != ISC_R_SUCCESS)
+		goto deallocate;
+
+	result = isc_mutex_init(&mgr->buffer_lock);
+	if (result != ISC_R_SUCCESS)
+		goto kill_lock;
+
+	result = isc_mutex_init(&mgr->pool_lock);
+	if (result != ISC_R_SUCCESS)
+		goto kill_buffer_lock;
+
+	mgr->epool = NULL;
+	if (isc_mempool_create(mgr->mctx, sizeof(dns_dispatchevent_t),
+			       &mgr->epool) != ISC_R_SUCCESS) {
+		result = ISC_R_NOMEMORY;
+		goto kill_pool_lock;
+	}
+
+	mgr->rpool = NULL;
+	if (isc_mempool_create(mgr->mctx, sizeof(dns_dispentry_t),
+			       &mgr->rpool) != ISC_R_SUCCESS) {
+		result = ISC_R_NOMEMORY;
+		goto kill_epool;
+	}
+
+	mgr->dpool = NULL;
+	if (isc_mempool_create(mgr->mctx, sizeof(dns_dispatch_t),
+			       &mgr->dpool) != ISC_R_SUCCESS) {
+		result = ISC_R_NOMEMORY;
+		goto kill_rpool;
+	}
+
+	isc_mempool_setname(mgr->epool, "dispmgr_epool");
+	isc_mempool_setfreemax(mgr->epool, 1024);
+	isc_mempool_associatelock(mgr->epool, &mgr->pool_lock);
+
+	isc_mempool_setname(mgr->rpool, "dispmgr_rpool");
+	isc_mempool_setfreemax(mgr->rpool, 1024);
+	isc_mempool_associatelock(mgr->rpool, &mgr->pool_lock);
+
+	isc_mempool_setname(mgr->dpool, "dispmgr_dpool");
+	isc_mempool_setfreemax(mgr->dpool, 1024);
+	isc_mempool_associatelock(mgr->dpool, &mgr->pool_lock);
+
+	mgr->buffers = 0;
+	mgr->buffersize = 0;
+	mgr->maxbuffers = 0;
+	mgr->bpool = NULL;
+	mgr->entropy = NULL;
+	mgr->qid = NULL;
+	mgr->state = 0;
+	ISC_LIST_INIT(mgr->list);
+	mgr->magic = DNS_DISPATCHMGR_MAGIC;
+
+	if (entropy != NULL)
+		isc_entropy_attach(entropy, &mgr->entropy);
+
+	*mgrp = mgr;
+	return (ISC_R_SUCCESS);
+
+ kill_rpool:
+	isc_mempool_destroy(&mgr->rpool);
+ kill_epool:
+	isc_mempool_destroy(&mgr->epool);
+ kill_pool_lock:
+	DESTROYLOCK(&mgr->pool_lock);
+ kill_buffer_lock:
+	DESTROYLOCK(&mgr->buffer_lock);
+ kill_lock:
+	DESTROYLOCK(&mgr->lock);
+ deallocate:
+	isc_mem_put(mctx, mgr, sizeof(dns_dispatchmgr_t));
+	isc_mem_detach(&mctx);
+
+	return (result);
+}
+
+void
+dns_dispatchmgr_setblackhole(dns_dispatchmgr_t *mgr, dns_acl_t *blackhole) {
+	REQUIRE(VALID_DISPATCHMGR(mgr));
+	if (mgr->blackhole != NULL)
+		dns_acl_detach(&mgr->blackhole);
+	dns_acl_attach(blackhole, &mgr->blackhole);
+}
+
+dns_acl_t *
+dns_dispatchmgr_getblackhole(dns_dispatchmgr_t *mgr) {
+	REQUIRE(VALID_DISPATCHMGR(mgr));
+	return (mgr->blackhole);
+}
+
+void
+dns_dispatchmgr_setblackportlist(dns_dispatchmgr_t *mgr,
+				 dns_portlist_t *portlist)
+{
+	REQUIRE(VALID_DISPATCHMGR(mgr));
+	if (mgr->portlist != NULL)
+		dns_portlist_detach(&mgr->portlist);
+	if (portlist != NULL)
+		dns_portlist_attach(portlist, &mgr->portlist);
+}
+
+dns_portlist_t *
+dns_dispatchmgr_getblackportlist(dns_dispatchmgr_t *mgr) {
+	REQUIRE(VALID_DISPATCHMGR(mgr));
+	return (mgr->portlist);
+}
+
+static isc_result_t
+dns_dispatchmgr_setudp(dns_dispatchmgr_t *mgr,
+			unsigned int buffersize, unsigned int maxbuffers,
+			unsigned int buckets, unsigned int increment)
+{
+	isc_result_t result;
+
+	REQUIRE(VALID_DISPATCHMGR(mgr));
+	REQUIRE(buffersize >= 512 && buffersize < (64 * 1024));
+	REQUIRE(maxbuffers > 0);
+	REQUIRE(buckets < 2097169);  /* next prime > 65536 * 32 */
+	REQUIRE(increment > buckets);
+
+	/*
+	 * Keep some number of items around.  This should be a config
+	 * option.  For now, keep 8, but later keep at least two even
+	 * if the caller wants less.  This allows us to ensure certain
+	 * things, like an event can be "freed" and the next allocation
+	 * will always succeed.
+	 *
+	 * Note that if limits are placed on anything here, we use one
+	 * event internally, so the actual limit should be "wanted + 1."
+	 *
+	 * XXXMLG
+	 */
+
+	if (maxbuffers < 8)
+		maxbuffers = 8;
+
+	LOCK(&mgr->buffer_lock);
+	if (mgr->bpool != NULL) {
+		isc_mempool_setmaxalloc(mgr->bpool, maxbuffers);
+		mgr->maxbuffers = maxbuffers;
+		UNLOCK(&mgr->buffer_lock);
+		return (ISC_R_SUCCESS);
+	}
+
+	if (isc_mempool_create(mgr->mctx, buffersize,
+			       &mgr->bpool) != ISC_R_SUCCESS) {
+		UNLOCK(&mgr->buffer_lock);
+		return (ISC_R_NOMEMORY);
+	}
+
+	isc_mempool_setname(mgr->bpool, "dispmgr_bpool");
+	isc_mempool_setmaxalloc(mgr->bpool, maxbuffers);
+	isc_mempool_associatelock(mgr->bpool, &mgr->pool_lock);
+
+	result = qid_allocate(mgr, buckets, increment, ISC_TRUE, &mgr->qid);
+	if (result != ISC_R_SUCCESS)
+		goto cleanup;
+
+	mgr->buffersize = buffersize;
+	mgr->maxbuffers = maxbuffers;
+	UNLOCK(&mgr->buffer_lock);
+	return (ISC_R_SUCCESS);
+
+ cleanup:
+	isc_mempool_destroy(&mgr->bpool);
+	UNLOCK(&mgr->buffer_lock);
+	return (ISC_R_NOMEMORY);
+}
+
+void
+dns_dispatchmgr_destroy(dns_dispatchmgr_t **mgrp) {
+	dns_dispatchmgr_t *mgr;
+	isc_boolean_t killit;
+
+	REQUIRE(mgrp != NULL);
+	REQUIRE(VALID_DISPATCHMGR(*mgrp));
+
+	mgr = *mgrp;
+	*mgrp = NULL;
+
+	LOCK(&mgr->lock);
+	mgr->state |= MGR_SHUTTINGDOWN;
+
+	killit = destroy_mgr_ok(mgr);
+	UNLOCK(&mgr->lock);
+
+	mgr_log(mgr, LVL(90), "destroy: killit=%d", killit);
+
+	if (killit)
+		destroy_mgr(&mgr);
+}
+
+static isc_boolean_t
+blacklisted(dns_dispatchmgr_t *mgr, isc_socket_t *sock) {
+	isc_sockaddr_t sockaddr;
+	isc_result_t result;
+
+	if (mgr->portlist == NULL)
+		return (ISC_FALSE);
+
+	result = isc_socket_getsockname(sock, &sockaddr);
+	if (result != ISC_R_SUCCESS)
+		return (ISC_FALSE);
+
+	if (mgr->portlist != NULL &&
+	    dns_portlist_match(mgr->portlist, isc_sockaddr_pf(&sockaddr),
+			       isc_sockaddr_getport(&sockaddr)))
+		return (ISC_TRUE);
+	return (ISC_FALSE);
+}
+
+#define ATTRMATCH(_a1, _a2, _mask) (((_a1) & (_mask)) == ((_a2) & (_mask)))
+
+static isc_boolean_t
+local_addr_match(dns_dispatch_t *disp, isc_sockaddr_t *addr) {
+	isc_sockaddr_t sockaddr;
+	isc_result_t result;
+
+	if (addr == NULL)
+		return (ISC_TRUE);
+
+	/*
+	 * Don't match wildcard ports against newly blacklisted ports.
+	 */
+	if (disp->mgr->portlist != NULL &&
+	    isc_sockaddr_getport(addr) == 0 &&
+	    isc_sockaddr_getport(&disp->local) == 0 &&
+	    blacklisted(disp->mgr, disp->socket))
+		return (ISC_FALSE);
+
+	/*
+	 * Check if we match the binding <address,port>.
+	 * Wildcard ports match/fail here.
+	 */
+	if (isc_sockaddr_equal(&disp->local, addr))
+		return (ISC_TRUE);
+	if (isc_sockaddr_getport(addr) == 0)
+		return (ISC_FALSE);
+
+	/*
+	 * Check if we match a bound wildcard port <address,port>.
+	 */
+	if (!isc_sockaddr_eqaddr(&disp->local, addr))
+		return (ISC_FALSE);
+	result = isc_socket_getsockname(disp->socket, &sockaddr);
+	if (result != ISC_R_SUCCESS)
+		return (ISC_FALSE);
+
+	return (isc_sockaddr_equal(&sockaddr, addr));
+}
+
+/*
+ * Requires mgr be locked.
+ *
+ * No dispatcher can be locked by this thread when calling this function.
+ *
+ *
+ * NOTE:
+ *	If a matching dispatcher is found, it is locked after this function
+ *	returns, and must be unlocked by the caller.
+ */
+static isc_result_t
+dispatch_find(dns_dispatchmgr_t *mgr, isc_sockaddr_t *local,
+	      unsigned int attributes, unsigned int mask,
+	      dns_dispatch_t **dispp)
+{
+	dns_dispatch_t *disp;
+	isc_result_t result;
+
+	/*
+	 * Make certain that we will not match a private dispatch.
+	 */
+	attributes &= ~DNS_DISPATCHATTR_PRIVATE;
+	mask |= DNS_DISPATCHATTR_PRIVATE;
+
+	disp = ISC_LIST_HEAD(mgr->list);
+	while (disp != NULL) {
+		LOCK(&disp->lock);
+		if ((disp->shutting_down == 0)
+		    && ATTRMATCH(disp->attributes, attributes, mask)
+		    && local_addr_match(disp, local))
+			break;
+		UNLOCK(&disp->lock);
+		disp = ISC_LIST_NEXT(disp, link);
+	}
+
+	if (disp == NULL) {
+		result = ISC_R_NOTFOUND;
+		goto out;
+	}
+
+	*dispp = disp;
+	result = ISC_R_SUCCESS;
+ out:
+
+	return (result);
+}
+
+static isc_result_t
+qid_allocate(dns_dispatchmgr_t *mgr, unsigned int buckets,
+	     unsigned int increment, isc_boolean_t usepool, dns_qid_t **qidp)
+{
+	dns_qid_t *qid;
+	unsigned int i;
+	isc_result_t result;
+
+	REQUIRE(VALID_DISPATCHMGR(mgr));
+	REQUIRE(buckets < 2097169);  /* next prime > 65536 * 32 */
+	REQUIRE(increment > buckets);
+	REQUIRE(qidp != NULL && *qidp == NULL);
+
+	qid = isc_mem_get(mgr->mctx, sizeof(*qid));
+	if (qid == NULL)
+		return (ISC_R_NOMEMORY);
+
+	qid->qid_table = isc_mem_get(mgr->mctx,
+				     buckets * sizeof(dns_displist_t));
+	if (qid->qid_table == NULL) {
+		isc_mem_put(mgr->mctx, qid, sizeof(*qid));
+		return (ISC_R_NOMEMORY);
+	}
+
+	result = nsid_init(mgr->mctx, &qid->nsid, usepool);
+	if (result != ISC_R_SUCCESS) {
+		isc_mem_put(mgr->mctx, qid->qid_table,
+			    buckets * sizeof(dns_displist_t));
+		isc_mem_put(mgr->mctx, qid, sizeof(*qid));
+		return (ISC_R_NOMEMORY);
+	}
+
+	result = isc_mutex_init(&qid->lock);
+	if (result != ISC_R_SUCCESS) {
+		nsid_destroy(mgr->mctx, &qid->nsid);
+		isc_mem_put(mgr->mctx, qid->qid_table,
+			    buckets * sizeof(dns_displist_t));
+		isc_mem_put(mgr->mctx, qid, sizeof(*qid));
+		return (result);
+	}
+
+	for (i = 0; i < buckets; i++)
+		ISC_LIST_INIT(qid->qid_table[i]);
+
+	qid->qid_nbuckets = buckets;
+	qid->qid_increment = increment;
+	qid->magic = QID_MAGIC;
+	*qidp = qid;
+	return (ISC_R_SUCCESS);
+}
+
+static void
+qid_destroy(isc_mem_t *mctx, dns_qid_t **qidp) {
+	dns_qid_t *qid;
+
+	REQUIRE(qidp != NULL);
+	qid = *qidp;
+
+	REQUIRE(VALID_QID(qid));
+
+	*qidp = NULL;
+	qid->magic = 0;
+	nsid_destroy(mctx, &qid->nsid);
+	isc_mem_put(mctx, qid->qid_table,
+		    qid->qid_nbuckets * sizeof(dns_displist_t));
+	DESTROYLOCK(&qid->lock);
+	isc_mem_put(mctx, qid, sizeof(*qid));
+}
+
+/*
+ * Allocate and set important limits.
+ */
+static isc_result_t
+dispatch_allocate(dns_dispatchmgr_t *mgr, unsigned int maxrequests,
+		  dns_dispatch_t **dispp)
+{
+	dns_dispatch_t *disp;
+	isc_result_t result;
+
+	REQUIRE(VALID_DISPATCHMGR(mgr));
+	REQUIRE(dispp != NULL && *dispp == NULL);
+
+	/*
+	 * Set up the dispatcher, mostly.  Don't bother setting some of
+	 * the options that are controlled by tcp vs. udp, etc.
+	 */
+
+	disp = isc_mempool_get(mgr->dpool);
+	if (disp == NULL)
+		return (ISC_R_NOMEMORY);
+
+	disp->magic = 0;
+	disp->mgr = mgr;
+	disp->maxrequests = maxrequests;
+	disp->attributes = 0;
+	ISC_LINK_INIT(disp, link);
+	disp->refcount = 1;
+	disp->recv_pending = 0;
+	memset(&disp->local, 0, sizeof(disp->local));
+	disp->shutting_down = 0;
+	disp->shutdown_out = 0;
+	disp->connected = 0;
+	disp->tcpmsg_valid = 0;
+	disp->shutdown_why = ISC_R_UNEXPECTED;
+	disp->requests = 0;
+	disp->tcpbuffers = 0;
+	disp->qid = NULL;
+
+	result = isc_mutex_init(&disp->lock);
+	if (result != ISC_R_SUCCESS)
+		goto deallocate;
+
+	disp->failsafe_ev = allocate_event(disp);
+	if (disp->failsafe_ev == NULL) {
+		result = ISC_R_NOMEMORY;
+		goto kill_lock;
+	}
+
+	disp->magic = DISPATCH_MAGIC;
+
+	*dispp = disp;
+	return (ISC_R_SUCCESS);
+
+	/*
+	 * error returns
+	 */
+ kill_lock:
+	DESTROYLOCK(&disp->lock);
+ deallocate:
+	isc_mempool_put(mgr->dpool, disp);
+
+	return (result);
+}
+
+
+/*
+ * MUST be unlocked, and not used by anthing.
+ */
+static void
+dispatch_free(dns_dispatch_t **dispp)
+{
+	dns_dispatch_t *disp;
+	dns_dispatchmgr_t *mgr;
+
+	REQUIRE(VALID_DISPATCH(*dispp));
+	disp = *dispp;
+	*dispp = NULL;
+
+	mgr = disp->mgr;
+	REQUIRE(VALID_DISPATCHMGR(mgr));
+
+	if (disp->tcpmsg_valid) {
+		dns_tcpmsg_invalidate(&disp->tcpmsg);
+		disp->tcpmsg_valid = 0;
+	}
+
+	INSIST(disp->tcpbuffers == 0);
+	INSIST(disp->requests == 0);
+	INSIST(disp->recv_pending == 0);
+
+	isc_mempool_put(mgr->epool, disp->failsafe_ev);
+	disp->failsafe_ev = NULL;
+
+	if (disp->qid != NULL)
+		qid_destroy(mgr->mctx, &disp->qid);
+	disp->mgr = NULL;
+	DESTROYLOCK(&disp->lock);
+	disp->magic = 0;
+	isc_mempool_put(mgr->dpool, disp);
+}
+
+isc_result_t
+dns_dispatch_createtcp(dns_dispatchmgr_t *mgr, isc_socket_t *sock,
+		       isc_taskmgr_t *taskmgr, unsigned int buffersize,
+		       unsigned int maxbuffers, unsigned int maxrequests,
+		       unsigned int buckets, unsigned int increment,
+		       unsigned int attributes, dns_dispatch_t **dispp)
+{
+	isc_result_t result;
+	dns_dispatch_t *disp;
+
+	UNUSED(maxbuffers);
+	UNUSED(buffersize);
+
+	REQUIRE(VALID_DISPATCHMGR(mgr));
+	REQUIRE(isc_socket_gettype(sock) == isc_sockettype_tcp);
+	REQUIRE((attributes & DNS_DISPATCHATTR_TCP) != 0);
+	REQUIRE((attributes & DNS_DISPATCHATTR_UDP) == 0);
+
+	attributes |= DNS_DISPATCHATTR_PRIVATE;  /* XXXMLG */
+
+	LOCK(&mgr->lock);
+
+	/*
+	 * dispatch_allocate() checks mgr for us.
+	 * qid_allocate() checks buckets and increment for us.
+	 */
+	disp = NULL;
+	result = dispatch_allocate(mgr, maxrequests, &disp);
+	if (result != ISC_R_SUCCESS) {
+		UNLOCK(&mgr->lock);
+		return (result);
+	}
+
+	result = qid_allocate(mgr, buckets, increment, ISC_FALSE, &disp->qid);
+	if (result != ISC_R_SUCCESS)
+		goto deallocate_dispatch;
+
+	disp->socktype = isc_sockettype_tcp;
+	disp->socket = NULL;
+	isc_socket_attach(sock, &disp->socket);
+
+	disp->task = NULL;
+	result = isc_task_create(taskmgr, 0, &disp->task);
+	if (result != ISC_R_SUCCESS)
+		goto kill_socket;
+
+	disp->ctlevent = isc_event_allocate(mgr->mctx, disp,
+					    DNS_EVENT_DISPATCHCONTROL,
+					    destroy_disp, disp,
+					    sizeof(isc_event_t));
+	if (disp->ctlevent == NULL) {
+		result = ISC_R_NOMEMORY;
+		goto kill_task;
+	}
+
+	isc_task_setname(disp->task, "tcpdispatch", disp);
+
+	dns_tcpmsg_init(mgr->mctx, disp->socket, &disp->tcpmsg);
+	disp->tcpmsg_valid = 1;
+
+	disp->attributes = attributes;
+
+	/*
+	 * Append it to the dispatcher list.
+	 */
+	ISC_LIST_APPEND(mgr->list, disp, link);
+	UNLOCK(&mgr->lock);
+
+	mgr_log(mgr, LVL(90), "created TCP dispatcher %p", disp);
+	dispatch_log(disp, LVL(90), "created task %p", disp->task);
+
+	*dispp = disp;
+
+	return (ISC_R_SUCCESS);
+
+	/*
+	 * Error returns.
+	 */
+ kill_task:
+	isc_task_detach(&disp->task);
+ kill_socket:
+	isc_socket_detach(&disp->socket);
+ deallocate_dispatch:
+	dispatch_free(&disp);
+
+	UNLOCK(&mgr->lock);
+
+	return (result);
+}
+
+isc_result_t
+dns_dispatch_getudp(dns_dispatchmgr_t *mgr, isc_socketmgr_t *sockmgr,
+		    isc_taskmgr_t *taskmgr, isc_sockaddr_t *localaddr,
+		    unsigned int buffersize,
+		    unsigned int maxbuffers, unsigned int maxrequests,
+		    unsigned int buckets, unsigned int increment,
+		    unsigned int attributes, unsigned int mask,
+		    dns_dispatch_t **dispp)
+{
+	isc_result_t result;
+	dns_dispatch_t *disp;
+
+	REQUIRE(VALID_DISPATCHMGR(mgr));
+	REQUIRE(sockmgr != NULL);
+	REQUIRE(localaddr != NULL);
+	REQUIRE(taskmgr != NULL);
+	REQUIRE(buffersize >= 512 && buffersize < (64 * 1024));
+	REQUIRE(maxbuffers > 0);
+	REQUIRE(buckets < 2097169);  /* next prime > 65536 * 32 */
+	REQUIRE(increment > buckets);
+	REQUIRE(dispp != NULL && *dispp == NULL);
+	REQUIRE((attributes & DNS_DISPATCHATTR_TCP) == 0);
+
+	result = dns_dispatchmgr_setudp(mgr, buffersize, maxbuffers,
+					buckets, increment);
+	if (result != ISC_R_SUCCESS)
+		return (result);
+
+	LOCK(&mgr->lock);
+
+	/*
+	 * First, see if we have a dispatcher that matches.
+	 */
+	disp = NULL;
+	result = dispatch_find(mgr, localaddr, attributes, mask, &disp);
+	if (result == ISC_R_SUCCESS) {
+		disp->refcount++;
+
+		if (disp->maxrequests < maxrequests)
+			disp->maxrequests = maxrequests;
+
+		if ((disp->attributes & DNS_DISPATCHATTR_NOLISTEN) == 0 &&
+		    (attributes & DNS_DISPATCHATTR_NOLISTEN) != 0)
+		{
+			disp->attributes |= DNS_DISPATCHATTR_NOLISTEN;
+			if (disp->recv_pending != 0)
+				isc_socket_cancel(disp->socket, disp->task,
+						  ISC_SOCKCANCEL_RECV);
+		}
+
+		UNLOCK(&disp->lock);
+		UNLOCK(&mgr->lock);
+
+		*dispp = disp;
+
+		return (ISC_R_SUCCESS);
+	}
+
+	/*
+	 * Nope, create one.
+	 */
+	result = dispatch_createudp(mgr, sockmgr, taskmgr, localaddr,
+				    maxrequests, attributes, &disp);
+	if (result != ISC_R_SUCCESS) {
+		UNLOCK(&mgr->lock);
+		return (result);
+	}
+
+	UNLOCK(&mgr->lock);
+	*dispp = disp;
+	return (ISC_R_SUCCESS);
+}
+
+/*
+ * mgr should be locked.
+ */
+
+#ifndef DNS_DISPATCH_HELD
+#define DNS_DISPATCH_HELD 20U
+#endif
+
+static isc_result_t
+dispatch_createudp(dns_dispatchmgr_t *mgr, isc_socketmgr_t *sockmgr,
+		   isc_taskmgr_t *taskmgr,
+		   isc_sockaddr_t *localaddr,
+		   unsigned int maxrequests,
+		   unsigned int attributes,
+		   dns_dispatch_t **dispp)
+{
+	isc_result_t result;
+	dns_dispatch_t *disp;
+	isc_socket_t *sock = NULL;
+	isc_socket_t *held[DNS_DISPATCH_HELD];
+	unsigned int i = 0, j = 0;
+
+	/*
+	 * dispatch_allocate() checks mgr for us.
+	 */
+	disp = NULL;
+	result = dispatch_allocate(mgr, maxrequests, &disp);
+	if (result != ISC_R_SUCCESS)
+		return (result);
+
+	/*
+	 * Try to allocate a socket that is not on the blacklist.
+	 * Hold up to DNS_DISPATCH_HELD sockets to prevent the OS
+	 * from returning the same port to us too quickly.
+	 */
+	memset(held, 0, sizeof(held));
+ getsocket:
+	result = create_socket(sockmgr, localaddr, &sock);
+	if (result != ISC_R_SUCCESS)
+		goto deallocate_dispatch;
+	if (isc_sockaddr_getport(localaddr) == 0 && blacklisted(mgr, sock)) {
+		if (held[i] != NULL)
+			isc_socket_detach(&held[i]);
+		held[i++] = sock;
+		sock = NULL;
+		if (i == DNS_DISPATCH_HELD)
+			i = 0;
+		if (j++ == 0xffffU) {
+			mgr_log(mgr, ISC_LOG_ERROR, "avoid-v%s-udp-ports: "
+				"unable to allocate a non-blacklisted port",
+				isc_sockaddr_pf(localaddr) == AF_INET ?
+					"4" : "6");
+			result = ISC_R_FAILURE;
+			goto deallocate_dispatch;
+		}
+		goto getsocket;
+	}
+
+	disp->socktype = isc_sockettype_udp;
+	disp->socket = sock;
+	disp->local = *localaddr;
+
+	disp->task = NULL;
+	result = isc_task_create(taskmgr, 0, &disp->task);
+	if (result != ISC_R_SUCCESS)
+		goto kill_socket;
+
+	disp->ctlevent = isc_event_allocate(mgr->mctx, disp,
+					    DNS_EVENT_DISPATCHCONTROL,
+					    destroy_disp, disp,
+					    sizeof(isc_event_t));
+	if (disp->ctlevent == NULL) {
+		result = ISC_R_NOMEMORY;
+		goto kill_task;
+	}
+
+	isc_task_setname(disp->task, "udpdispatch", disp);
+
+	attributes &= ~DNS_DISPATCHATTR_TCP;
+	attributes |= DNS_DISPATCHATTR_UDP;
+	disp->attributes = attributes;
+
+	/*
+	 * Append it to the dispatcher list.
+	 */
+	ISC_LIST_APPEND(mgr->list, disp, link);
+
+	mgr_log(mgr, LVL(90), "created UDP dispatcher %p", disp);
+	dispatch_log(disp, LVL(90), "created task %p", disp->task);
+	dispatch_log(disp, LVL(90), "created socket %p", disp->socket);
+
+	*dispp = disp;
+
+	goto cleanheld;
+
+	/*
+	 * Error returns.
+	 */
+ kill_task:
+	isc_task_detach(&disp->task);
+ kill_socket:
+	isc_socket_detach(&disp->socket);
+ deallocate_dispatch:
+	dispatch_free(&disp);
+ cleanheld:
+	for (i = 0; i < DNS_DISPATCH_HELD; i++)
+		if (held[i] != NULL)
+			isc_socket_detach(&held[i]);
+	return (result);
+}
+
+void
+dns_dispatch_attach(dns_dispatch_t *disp, dns_dispatch_t **dispp) {
+	REQUIRE(VALID_DISPATCH(disp));
+	REQUIRE(dispp != NULL && *dispp == NULL);
+
+	LOCK(&disp->lock);
+	disp->refcount++;
+	UNLOCK(&disp->lock);
+
+	*dispp = disp;
+}
+
+/*
+ * It is important to lock the manager while we are deleting the dispatch,
+ * since dns_dispatch_getudp will call dispatch_find, which returns to
+ * the caller a dispatch but does not attach to it until later.  _getudp
+ * locks the manager, however, so locking it here will keep us from attaching
+ * to a dispatcher that is in the process of going away.
+ */
+void
+dns_dispatch_detach(dns_dispatch_t **dispp) {
+	dns_dispatch_t *disp;
+	isc_boolean_t killit;
+
+	REQUIRE(dispp != NULL && VALID_DISPATCH(*dispp));
+
+	disp = *dispp;
+	*dispp = NULL;
+
+	LOCK(&disp->lock);
+
+	INSIST(disp->refcount > 0);
+	disp->refcount--;
+	killit = ISC_FALSE;
+	if (disp->refcount == 0) {
+		if (disp->recv_pending > 0)
+			isc_socket_cancel(disp->socket, disp->task,
+					  ISC_SOCKCANCEL_RECV);
+		disp->shutting_down = 1;
+	}
+
+	dispatch_log(disp, LVL(90), "detach: refcount %d", disp->refcount);
+
+	killit = destroy_disp_ok(disp);
+	UNLOCK(&disp->lock);
+	if (killit)
+		isc_task_send(disp->task, &disp->ctlevent);
+}
+
+isc_result_t
+dns_dispatch_addresponse(dns_dispatch_t *disp, isc_sockaddr_t *dest,
+			 isc_task_t *task, isc_taskaction_t action, void *arg,
+			 dns_messageid_t *idp, dns_dispentry_t **resp)
+{
+	dns_dispentry_t *res;
+	unsigned int bucket;
+	dns_messageid_t id;
+	int i;
+	isc_boolean_t ok;
+	dns_qid_t *qid;
+
+	REQUIRE(VALID_DISPATCH(disp));
+	REQUIRE(task != NULL);
+	REQUIRE(dest != NULL);
+	REQUIRE(resp != NULL && *resp == NULL);
+	REQUIRE(idp != NULL);
+
+	LOCK(&disp->lock);
+
+	if (disp->shutting_down == 1) {
+		UNLOCK(&disp->lock);
+		return (ISC_R_SHUTTINGDOWN);
+	}
+
+	if (disp->requests >= disp->maxrequests) {
+		UNLOCK(&disp->lock);
+		return (ISC_R_QUOTA);
+	}
+
+	/*
+	 * Try somewhat hard to find an unique ID.
+	 */
+	qid = DNS_QID(disp);
+	LOCK(&qid->lock);
+	id = dns_randomid(&qid->nsid);
+	bucket = dns_hash(qid, dest, id);
+	ok = ISC_FALSE;
+	for (i = 0; i < 64; i++) {
+		if (bucket_search(qid, dest, id, bucket) == NULL) {
+			ok = ISC_TRUE;
+			break;
+		}
+		id += qid->qid_increment;
+		id &= 0x0000ffff;
+		bucket = dns_hash(qid, dest, id);
+	}
+
+	if (!ok) {
+		UNLOCK(&qid->lock);
+		UNLOCK(&disp->lock);
+		return (ISC_R_NOMORE);
+	}
+
+	res = isc_mempool_get(disp->mgr->rpool);
+	if (res == NULL) {
+		UNLOCK(&qid->lock);
+		UNLOCK(&disp->lock);
+		return (ISC_R_NOMEMORY);
+	}
+
+	disp->refcount++;
+	disp->requests++;
+	res->task = NULL;
+	isc_task_attach(task, &res->task);
+	res->disp = disp;
+	res->id = id;
+	res->bucket = bucket;
+	res->host = *dest;
+	res->action = action;
+	res->arg = arg;
+	res->item_out = ISC_FALSE;
+	ISC_LIST_INIT(res->items);
+	ISC_LINK_INIT(res, link);
+	res->magic = RESPONSE_MAGIC;
+	ISC_LIST_APPEND(qid->qid_table[bucket], res, link);
+	UNLOCK(&qid->lock);
+
+	request_log(disp, res, LVL(90),
+		    "attached to task %p", res->task);
+
+	if (((disp->attributes & DNS_DISPATCHATTR_UDP) != 0) ||
+	    ((disp->attributes & DNS_DISPATCHATTR_CONNECTED) != 0))
+		startrecv(disp);
+
+	UNLOCK(&disp->lock);
+
+	*idp = id;
+	*resp = res;
+
+	return (ISC_R_SUCCESS);
+}
+
+void
+dns_dispatch_starttcp(dns_dispatch_t *disp) {
+
+	REQUIRE(VALID_DISPATCH(disp));
+
+	dispatch_log(disp, LVL(90), "starttcp %p", disp->task);
+
+	LOCK(&disp->lock);
+	disp->attributes |= DNS_DISPATCHATTR_CONNECTED;
+	startrecv(disp);
+	UNLOCK(&disp->lock);
+}
+
+void
+dns_dispatch_removeresponse(dns_dispentry_t **resp,
+			    dns_dispatchevent_t **sockevent)
+{
+	dns_dispatchmgr_t *mgr;
+	dns_dispatch_t *disp;
+	dns_dispentry_t *res;
+	dns_dispatchevent_t *ev;
+	unsigned int bucket;
+	isc_boolean_t killit;
+	unsigned int n;
+	isc_eventlist_t events;
+	dns_qid_t *qid;
+
+	REQUIRE(resp != NULL);
+	REQUIRE(VALID_RESPONSE(*resp));
+
+	res = *resp;
+	*resp = NULL;
+
+	disp = res->disp;
+	REQUIRE(VALID_DISPATCH(disp));
+	mgr = disp->mgr;
+	REQUIRE(VALID_DISPATCHMGR(mgr));
+
+	qid = DNS_QID(disp);
+
+	if (sockevent != NULL) {
+		REQUIRE(*sockevent != NULL);
+		ev = *sockevent;
+		*sockevent = NULL;
+	} else {
+		ev = NULL;
+	}
+
+	LOCK(&disp->lock);
+
+	INSIST(disp->requests > 0);
+	disp->requests--;
+	INSIST(disp->refcount > 0);
+	disp->refcount--;
+	killit = ISC_FALSE;
+	if (disp->refcount == 0) {
+		if (disp->recv_pending > 0)
+			isc_socket_cancel(disp->socket, disp->task,
+					  ISC_SOCKCANCEL_RECV);
+		disp->shutting_down = 1;
+	}
+
+	bucket = res->bucket;
+
+	LOCK(&qid->lock);
+	ISC_LIST_UNLINK(qid->qid_table[bucket], res, link);
+	UNLOCK(&qid->lock);
+
+	if (ev == NULL && res->item_out) {
+		/*
+		 * We've posted our event, but the caller hasn't gotten it
+		 * yet.  Take it back.
+		 */
+		ISC_LIST_INIT(events);
+		n = isc_task_unsend(res->task, res, DNS_EVENT_DISPATCH,
+				    NULL, &events);
+		/*
+		 * We had better have gotten it back.
+		 */
+		INSIST(n == 1);
+		ev = (dns_dispatchevent_t *)ISC_LIST_HEAD(events);
+	}
+
+	if (ev != NULL) {
+		REQUIRE(res->item_out == ISC_TRUE);
+		res->item_out = ISC_FALSE;
+		if (ev->buffer.base != NULL)
+			free_buffer(disp, ev->buffer.base, ev->buffer.length);
+		free_event(disp, ev);
+	}
+
+	request_log(disp, res, LVL(90), "detaching from task %p", res->task);
+	isc_task_detach(&res->task);
+
+	/*
+	 * Free any buffered requests as well
+	 */
+	ev = ISC_LIST_HEAD(res->items);
+	while (ev != NULL) {
+		ISC_LIST_UNLINK(res->items, ev, ev_link);
+		if (ev->buffer.base != NULL)
+			free_buffer(disp, ev->buffer.base, ev->buffer.length);
+		free_event(disp, ev);
+		ev = ISC_LIST_HEAD(res->items);
+	}
+	res->magic = 0;
+	isc_mempool_put(disp->mgr->rpool, res);
+	if (disp->shutting_down == 1)
+		do_cancel(disp);
+	else
+		startrecv(disp);
+
+	killit = destroy_disp_ok(disp);
+	UNLOCK(&disp->lock);
+	if (killit)
+		isc_task_send(disp->task, &disp->ctlevent);
+}
+
+static void
+do_cancel(dns_dispatch_t *disp) {
+	dns_dispatchevent_t *ev;
+	dns_dispentry_t *resp;
+	dns_qid_t *qid;
+
+	if (disp->shutdown_out == 1)
+		return;
+
+	qid = DNS_QID(disp);
+
+	/*
+	 * Search for the first response handler without packets outstanding.
+	 */
+	LOCK(&qid->lock);
+	for (resp = linear_first(qid);
+	     resp != NULL && resp->item_out != ISC_FALSE;
+	     /* Empty. */)
+		resp = linear_next(qid, resp);
+	/*
+	 * No one to send the cancel event to, so nothing to do.
+	 */
+	if (resp == NULL)
+		goto unlock;
+
+	/*
+	 * Send the shutdown failsafe event to this resp.
+	 */
+	ev = disp->failsafe_ev;
+	ISC_EVENT_INIT(ev, sizeof(*ev), 0, NULL, DNS_EVENT_DISPATCH,
+		       resp->action, resp->arg, resp, NULL, NULL);
+	ev->result = disp->shutdown_why;
+	ev->buffer.base = NULL;
+	ev->buffer.length = 0;
+	disp->shutdown_out = 1;
+	request_log(disp, resp, LVL(10),
+		    "cancel: failsafe event %p -> task %p",
+		    ev, resp->task);
+	resp->item_out = ISC_TRUE;
+	isc_task_send(resp->task, ISC_EVENT_PTR(&ev));
+ unlock:
+	UNLOCK(&qid->lock);
+}
+
+isc_socket_t *
+dns_dispatch_getsocket(dns_dispatch_t *disp) {
+	REQUIRE(VALID_DISPATCH(disp));
+
+	return (disp->socket);
+}
+
+isc_result_t
+dns_dispatch_getlocaladdress(dns_dispatch_t *disp, isc_sockaddr_t *addrp) {
+
+	REQUIRE(VALID_DISPATCH(disp));
+	REQUIRE(addrp != NULL);
+
+	if (disp->socktype == isc_sockettype_udp) {
+		*addrp = disp->local;
+		return (ISC_R_SUCCESS);
+	}
+	return (ISC_R_NOTIMPLEMENTED);
+}
+
+void
+dns_dispatch_cancel(dns_dispatch_t *disp) {
+	REQUIRE(VALID_DISPATCH(disp));
+
+	LOCK(&disp->lock);
+
+	if (disp->shutting_down == 1) {
+		UNLOCK(&disp->lock);
+		return;
+	}
+
+	disp->shutdown_why = ISC_R_CANCELED;
+	disp->shutting_down = 1;
+	do_cancel(disp);
+
+	UNLOCK(&disp->lock);
+
+	return;
+}
+
+void
+dns_dispatch_changeattributes(dns_dispatch_t *disp,
+			      unsigned int attributes, unsigned int mask)
+{
+	REQUIRE(VALID_DISPATCH(disp));
+
+	/* XXXMLG
+	 * Should check for valid attributes here!
+	 */
+
+	LOCK(&disp->lock);
+
+	if ((mask & DNS_DISPATCHATTR_NOLISTEN) != 0) {
+		if ((disp->attributes & DNS_DISPATCHATTR_NOLISTEN) != 0 &&
+		    (attributes & DNS_DISPATCHATTR_NOLISTEN) == 0) {
+			disp->attributes &= ~DNS_DISPATCHATTR_NOLISTEN;
+			startrecv(disp);
+		} else if ((disp->attributes & DNS_DISPATCHATTR_NOLISTEN)
+			   == 0 &&
+			   (attributes & DNS_DISPATCHATTR_NOLISTEN) != 0) {
+			disp->attributes |= DNS_DISPATCHATTR_NOLISTEN;
+			if (disp->recv_pending != 0)
+				isc_socket_cancel(disp->socket, disp->task,
+						  ISC_SOCKCANCEL_RECV);
+		}
+	}
+
+	disp->attributes &= ~mask;
+	disp->attributes |= (attributes & mask);
+	UNLOCK(&disp->lock);
+}
+
+void
+dns_dispatch_importrecv(dns_dispatch_t *disp, isc_event_t *event) {
+	void *buf;
+	isc_socketevent_t *sevent, *newsevent;
+
+	REQUIRE(VALID_DISPATCH(disp));
+	REQUIRE((disp->attributes & DNS_DISPATCHATTR_NOLISTEN) != 0);
+	REQUIRE(event != NULL);
+
+	sevent = (isc_socketevent_t *)event;
+
+	INSIST(sevent->n <= disp->mgr->buffersize);
+	newsevent = (isc_socketevent_t *)
+		    isc_event_allocate(disp->mgr->mctx, NULL,
+				      DNS_EVENT_IMPORTRECVDONE, udp_recv,
+				      disp, sizeof(isc_socketevent_t));
+	if (newsevent == NULL)
+		return;
+
+	buf = allocate_udp_buffer(disp);
+	if (buf == NULL) {
+		isc_event_free(ISC_EVENT_PTR(&newsevent));
+		return;
+	}
+	memcpy(buf, sevent->region.base, sevent->n);
+	newsevent->region.base = buf;
+	newsevent->region.length = disp->mgr->buffersize;
+	newsevent->n = sevent->n;
+	newsevent->result = sevent->result;
+	newsevent->address = sevent->address;
+	newsevent->timestamp = sevent->timestamp;
+	newsevent->pktinfo = sevent->pktinfo;
+	newsevent->attributes = sevent->attributes;
+	
+	isc_task_send(disp->task, ISC_EVENT_PTR(&newsevent));
+}
+
+#if 0
+void
+dns_dispatchmgr_dump(dns_dispatchmgr_t *mgr) {
+	dns_dispatch_t *disp;
+	char foo[1024];
+
+	disp = ISC_LIST_HEAD(mgr->list);
+	while (disp != NULL) {
+		isc_sockaddr_format(&disp->local, foo, sizeof(foo));
+		printf("\tdispatch %p, addr %s\n", disp, foo);
+		disp = ISC_LIST_NEXT(disp, link);
+	}
+}
+#endif
+
+/*
+ * Allow the user to pick one of two ID randomization algorithms.
+ *
+ * The first algorithm is an adaptation of the sequence shuffling
+ * algorithm discovered by Carter Bays and S. D. Durham [ACM Trans. Math.
+ * Software 2 (1976), 59-64], as documented as Algorithm B in Chapter
+ * 3.2.2 in Volume 2 of Knuth's "The Art of Computer Programming".  We use
+ * a randomly selected linear congruential random number generator with a
+ * modulus of 2^16, whose increment is a randomly picked odd number, and
+ * whose multiplier is picked from a set which meets the following
+ * criteria:
+ *     Is of the form 8*n+5, which ensures "high potency" according to
+ *     principle iii in the summary chapter 3.6.  This form also has a
+ *     gcd(a-1,m) of 4 which is good according to principle iv.
+ *
+ *     Is between 0.01 and 0.99 times the modulus as specified by
+ *     principle iv.
+ *
+ *     Passes the spectral test "with flying colors" (ut >= 1) in
+ *     dimensions 2 through 6 as calculated by Algorithm S in Chapter
+ *     3.3.4 and the ratings calculated by formula 35 in section E.
+ *
+ *     Of the multipliers that pass this test, pick the set that is
+ *     best according to the theoretical bounds of the serial
+ *     correlation test.  This was calculated using a simplified
+ *     version of Knuth's Theorem K in Chapter 3.3.3.
+ *
+ * These criteria may not be important for this use, but we might as well
+ * pick from the best generators since there are so many possible ones and
+ * we don't have that many random bits to do the picking.
+ *
+ * We use a modulus of 2^16 instead of something bigger so that we will
+ * tend to cycle through all the possible IDs before repeating any,
+ * however the shuffling will perturb this somewhat.  Theoretically there
+ * is no minimimum interval between two uses of the same ID, but in
+ * practice it seems to be >64000.
+ *
+ * Our adaptatation  of Algorithm B mixes the hash state which has
+ * captured various random events into the shuffler to perturb the
+ * sequence.
+ *
+ * One disadvantage of this algorithm is that if the generator parameters
+ * were to be guessed, it would be possible to mount a limited brute force
+ * attack on the ID space since the IDs are only shuffled within a limited
+ * range.
+ *
+ * The second algorithm uses the same random number generator to populate
+ * a pool of 65536 IDs.  The hash state is used to pick an ID from a window
+ * of 4096 IDs in this pool, then the chosen ID is swapped with the ID
+ * at the beginning of the window and the window position is advanced.
+ * This means that the interval between uses of the ID will be no less
+ * than 65536-4096.  The ID sequence in the pool will become more random
+ * over time.
+ *
+ * For both algorithms, two more linear congruential random number generators
+ * are selected.  The ID from the first part of algorithm is used to seed
+ * the first of these generators, and its output is used to seed the second.
+ * The strategy is use these generators as 1 to 1 hashes to obfuscate the
+ * properties of the generator used in the first part of either algorithm.
+ *
+ * The first algorithm may be suitable for use in a client resolver since
+ * its memory requirements are fairly low and it's pretty random out of
+ * the box.  It is somewhat succeptible to a limited brute force attack,
+ * so the second algorithm is probably preferable for a longer running
+ * program that issues a large number of queries and has time to randomize
+ * the pool.
+ */
+
+#define NSID_SHUFFLE_TABLE_SIZE 100 /* Suggested by Knuth */
+/*
+ * Pick one of the next 4096 IDs in the pool.
+ * There is a tradeoff here between randomness and how often and ID is reused.
+ */
+#define NSID_LOOKAHEAD 4096     /* Must be a power of 2 */
+#define NSID_SHUFFLE_ONLY 1     /* algorithm 1 */
+#define NSID_USE_POOL 2         /* algorithm 2 */
+#define NSID_HASHSHIFT       3
+#define NSID_HASHROTATE(v) \
+        (((v) << NSID_HASHSHIFT) | ((v) >> ((sizeof(v) * 8) - NSID_HASHSHIFT)))
+
+static isc_uint32_t	nsid_hash_state;
+
+/*
+ * Keep a running hash of various bits of data that we'll use to
+ * stir the ID pool or perturb the ID generator
+ */
+static void
+nsid_hash(void *data, size_t len) {
+	unsigned char *p = data;
+	/*
+	 * Hash function similar to the one we use for hashing names.
+	 * We don't fold case or toss the upper bit here, though.
+	 * This hash doesn't do much interesting when fed binary zeros,
+	 * so there may be a better hash function.
+	 * This function doesn't need to be very strong since we're
+	 * only using it to stir the pool, but it should be reasonably
+	 * fast.
+	 */
+	/*
+	 * We don't care about locking access to nsid_hash_state.
+	 * In fact races make the result even more non deteministic.
+	 */
+	while (len-- > 0U) {
+		nsid_hash_state = NSID_HASHROTATE(nsid_hash_state);
+		nsid_hash_state += *p++;
+	}
+}
+
+/*
+ * Table of good linear congruential multipliers for modulus 2^16
+ * in order of increasing serial correlation bounds (so trim from
+ * the end).
+ */
+static const isc_uint16_t nsid_multiplier_table[] = {
+	17565, 25013, 11733, 19877, 23989, 23997, 24997, 25421,
+	26781, 27413, 35901, 35917, 35973, 36229, 38317, 38437,
+	39941, 40493, 41853, 46317, 50581, 51429, 53453, 53805,
+	11317, 11789, 12045, 12413, 14277, 14821, 14917, 18989,
+	19821, 23005, 23533, 23573, 23693, 27549, 27709, 28461,
+	29365, 35605, 37693, 37757, 38309, 41285, 45261, 47061,
+	47269, 48133, 48597, 50277, 50717, 50757, 50805, 51341,
+	51413, 51581, 51597, 53445, 11493, 14229, 20365, 20653,
+	23485, 25541, 27429, 29421, 30173, 35445, 35653, 36789,
+	36797, 37109, 37157, 37669, 38661, 39773, 40397, 41837,
+	41877, 45293, 47277, 47845, 49853, 51085, 51349, 54085,
+	56933,  8877,  8973,  9885, 11365, 11813, 13581, 13589,
+	13613, 14109, 14317, 15765, 15789, 16925, 17069, 17205,
+	17621, 17941, 19077, 19381, 20245, 22845, 23733, 24869,
+	25453, 27213, 28381, 28965, 29245, 29997, 30733, 30901,
+	34877, 35485, 35613, 36133, 36661, 36917, 38597, 40285,
+	40693, 41413, 41541, 41637, 42053, 42349, 45245, 45469,
+	46493, 48205, 48613, 50861, 51861, 52877, 53933, 54397,
+	55669, 56453, 56965, 58021,  7757,  7781,  8333,  9661,
+	12229, 14373, 14453, 17549, 18141, 19085, 20773, 23701,
+	24205, 24333, 25261, 25317, 27181, 30117, 30477, 34757,
+	34885, 35565, 35885, 36541, 37957, 39733, 39813, 41157,
+	41893, 42317, 46621, 48117, 48181, 49525, 55261, 55389,
+	56845,  7045,  7749,  7965,  8469,  9133,  9549,  9789,
+	10173, 11181, 11285, 12253, 13453, 13533, 13757, 14477,
+	15053, 16901, 17213, 17269, 17525, 17629, 18605, 19013,
+	19829, 19933, 20069, 20093, 23261, 23333, 24949, 25309,
+	27613, 28453, 28709, 29301, 29541, 34165, 34413, 37301,
+	37773, 38045, 38405, 41077, 41781, 41925, 42717, 44437,
+	44525, 44613, 45933, 45941, 47077, 50077, 50893, 52117,
+	 5293, 55069, 55989, 58125, 59205,  6869, 14685, 15453,
+	16821, 17045, 17613, 18437, 21029, 22773, 22909, 25445,
+	25757, 26541, 30709, 30909, 31093, 31149, 37069, 37725,
+	37925, 38949, 39637, 39701, 40765, 40861, 42965, 44813,
+	45077, 45733, 47045, 50093, 52861, 52957, 54181, 56325,
+	56365, 56381, 56877, 57013,  5741, 58101, 58669,  8613,
+	10045, 10261, 10653, 10733, 11461, 12261, 14069, 15877,
+	17757, 21165, 23885, 24701, 26429, 26645, 27925, 28765,
+	29197, 30189, 31293, 39781, 39909, 40365, 41229, 41453,
+	41653, 42165, 42365, 47421, 48029, 48085, 52773,  5573,
+	57037, 57637, 58341, 58357, 58901,  6357,  7789,  9093,
+	10125, 10709, 10765, 11957, 12469, 13437, 13509, 14773,
+	15437, 15773, 17813, 18829, 19565, 20237, 23461, 23685,
+	23725, 23941, 24877, 25461, 26405, 29509, 30285, 35181,
+	37229, 37893, 38565, 40293, 44189, 44581, 45701, 47381,
+	47589, 48557,  4941, 51069,  5165, 52797, 53149,  5341,
+	56301, 56765, 58581, 59493, 59677,  6085,  6349,  8293,
+	 8501,  8517, 11597, 11709, 12589, 12693, 13517, 14909,
+	17397, 18085, 21101, 21269, 22717, 25237, 25661, 29189,
+	30101, 31397, 33933, 34213, 34661, 35533, 36493, 37309,
+	40037,  4189, 42909, 44309, 44357, 44389,  4541, 45461,
+	46445, 48237, 54149, 55301, 55853, 56621, 56717, 56901,
+	 5813, 58437, 12493, 15365, 15989, 17829, 18229, 19341,
+	21013, 21357, 22925, 24885, 26053, 27581, 28221, 28485,
+	30605, 30613, 30789, 35437, 36285, 37189,  3941, 41797,
+	 4269, 42901, 43293, 44645, 45221, 46893,  4893, 50301,
+	50325,  5189, 52109, 53517, 54053, 54485,  5525, 55949,
+	56973, 59069, 59421, 60733, 61253,  6421,  6701,  6709,
+	 7101,  8669, 15797, 19221, 19837, 20133, 20957, 21293,
+	21461, 22461, 29085, 29861, 30869, 34973, 36469, 37565,
+	38125, 38829, 39469, 40061, 40117, 44093, 47429, 48341,
+	50597, 51757,  5541, 57629, 58405, 59621, 59693, 59701,
+	61837,  7061, 10421, 11949, 15405, 20861, 25397, 25509,
+	25893, 26037, 28629, 28869, 29605, 30213, 34205, 35637,
+	36365, 37285,  3773, 39117,  4021, 41061, 42653, 44509,
+	 4461, 44829,  4725,  5125, 52269, 56469, 59085,  5917,
+	60973,  8349, 17725, 18637, 19773, 20293, 21453, 22533,
+	24285, 26333, 26997, 31501, 34541, 34805, 37509, 38477,
+	41333, 44125, 46285, 46997, 47637, 48173,  4925, 50253,
+	50381, 50917, 51205, 51325, 52165, 52229,  5253,  5269,
+	53509, 56253, 56341,  5821, 58373, 60301, 61653, 61973,
+	62373,  8397, 11981, 14341, 14509, 15077, 22261, 22429,
+	24261, 28165, 28685, 30661, 34021, 34445, 39149,  3917,
+	43013, 43317, 44053, 44101,  4533, 49541, 49981,  5277,
+	54477, 56357, 57261, 57765, 58573, 59061, 60197, 61197,
+	62189,  7725,  8477,  9565, 10229, 11437, 14613, 14709,
+	16813, 20029, 20677, 31445,  3165, 31957,  3229, 33541,
+	36645,  3805, 38973,  3965,  4029, 44293, 44557, 46245,
+	48917,  4909, 51749, 53709, 55733, 56445,  5925,  6093,
+	61053, 62637,  8661,  9109, 10821, 11389, 13813, 14325,
+	15501, 16149, 18845, 22669, 26437, 29869, 31837, 33709,
+	33973, 34173,  3677,  3877,  3981, 39885, 42117,  4421,
+	44221, 44245, 44693, 46157, 47309,  5005, 51461, 52037,
+	55333, 55693, 56277, 58949,  6205, 62141, 62469,  6293,
+	10101, 12509, 14029, 17997, 20469, 21149, 25221, 27109,
+	 2773,  2877, 29405, 31493, 31645,  4077, 42005, 42077,
+	42469, 42501, 44013, 48653, 49349,  4997, 50101, 55405,
+	56957, 58037, 59429, 60749, 61797, 62381, 62837,  6605,
+	10541, 23981, 24533,  2701, 27333, 27341, 31197, 33805,
+	 3621, 37381,  3749,  3829, 38533, 42613, 44381, 45901,
+	48517, 51269, 57725, 59461, 60045, 62029, 13805, 14013,
+	15461, 16069, 16157, 18573,  2309, 23501, 28645,  3077,
+	31541, 36357, 36877,  3789, 39429, 39805, 47685, 47949,
+	49413,  5485, 56757, 57549, 57805, 58317, 59549, 62213,
+	62613, 62853, 62933,  8909, 12941, 16677, 20333, 21541,
+	24429, 26077, 26421,  2885, 31269, 33381,  3661, 40925,
+	42925, 45173,  4525,  4709, 53133, 55941, 57413, 57797,
+	62125, 62237, 62733,  6773, 12317, 13197, 16533, 16933,
+	18245,  2213,  2477, 29757, 33293, 35517, 40133, 40749,
+	 4661, 49941, 62757,  7853,  8149,  8573, 11029, 13421,
+	21549, 22709, 22725, 24629,  2469, 26125,  2669, 34253,
+	36709, 41013, 45597, 46637, 52285, 52333, 54685, 59013,
+	60997, 61189, 61981, 62605, 62821,  7077,  7525,  8781,
+	10861, 15277,  2205, 22077, 28517, 28949, 32109, 33493,
+	 4661, 49941, 62757,  7853,  8149,  8573, 11029, 13421,
+	21549, 22709, 22725, 24629,  2469, 26125,  2669, 34253,
+	36709, 41013, 45597, 46637, 52285, 52333, 54685, 59013,
+	60997, 61189, 61981, 62605, 62821,  7077,  7525,  8781,
+	10861, 15277,  2205, 22077, 28517, 28949, 32109, 33493,
+	 3685, 39197, 39869, 42621, 44997, 48565,  5221, 57381,
+	61749, 62317, 63245, 63381, 23149,  2549, 28661, 31653,
+	33885, 36341, 37053, 39517, 42805, 45853, 48997, 59349,
+	60053, 62509, 63069,  6525,  1893, 20181,  2365, 24893,
+	27397, 31357, 32277, 33357, 34437, 36677, 37661, 43469,
+	43917, 50997, 53869,  5653, 13221, 16741, 17893,  2157,
+	28653, 31789, 35301, 35821, 61613, 62245, 12405, 14517,
+	17453, 18421,  3149,  3205, 40341,  4109, 43941, 46869,
+	48837, 50621, 57405, 60509, 62877,  8157, 12933, 12957,
+	16501, 19533,  3461, 36829, 52357, 58189, 58293, 63053,
+	17109,  1933, 32157, 37701, 59005, 61621, 13029, 15085,
+	16493, 32317, 35093,  5061, 51557, 62221, 20765, 24613,
+	 2629, 30861, 33197, 33749, 35365, 37933, 40317, 48045,
+	56229, 61157, 63797,  7917, 17965,  1917,  1973, 20301,
+	 2253, 33157, 58629, 59861, 61085, 63909,  8141,  9221,
+	14757,  1581, 21637, 26557, 33869, 34285, 35733, 40933,
+	42517, 43501, 53653, 61885, 63805,  7141, 21653, 54973,
+	31189, 60061, 60341, 63357, 16045,  2053, 26069, 33997,
+	43901, 54565, 63837,  8949, 17909, 18693, 32349, 33125,
+	37293, 48821, 49053, 51309, 64037,  7117,  1445, 20405,
+	23085, 26269, 26293, 27349, 32381, 33141, 34525, 36461,
+	37581, 43525,  4357, 43877,  5069, 55197, 63965,  9845,
+	12093,  2197,  2229, 32165, 33469, 40981, 42397,  8749,
+	10853,  1453, 18069, 21693, 30573, 36261, 37421, 42533
+};
+
+#define NSID_MULT_TABLE_SIZE \
+        ((sizeof nsid_multiplier_table)/(sizeof nsid_multiplier_table[0]))
+#define NSID_RANGE_MASK (NSID_LOOKAHEAD - 1)
+#define NSID_POOL_MASK 0xFFFF /* used to wrap the pool index */
+#define NSID_SHUFFLE_ONLY 1
+#define NSID_USE_POOL 2
+
+static isc_uint16_t
+nsid_next(dns_nsid_t *nsid) {
+        isc_uint16_t id, compressed_hash;
+	isc_uint16_t j;
+
+        compressed_hash = ((nsid_hash_state >> 16) ^
+			   (nsid_hash_state)) & 0xFFFF;
+
+	if (nsid->nsid_usepool) {
+	        isc_uint16_t pick;
+
+                pick = compressed_hash & NSID_RANGE_MASK;
+		pick = (nsid->nsid_state + pick) & NSID_POOL_MASK;
+                id = nsid->nsid_pool[pick];
+                if (pick != 0) {
+                        /* Swap two IDs to stir the pool */
+                        nsid->nsid_pool[pick] =
+                                nsid->nsid_pool[nsid->nsid_state];
+                        nsid->nsid_pool[nsid->nsid_state] = id;
+                }
+
+                /* increment the base pointer into the pool */
+                if (nsid->nsid_state == 65535)
+                        nsid->nsid_state = 0;
+                else
+                        nsid->nsid_state++;
+	} else {
+		/*
+		 * This is the original Algorithm B
+		 * j = ((u_long) NSID_SHUFFLE_TABLE_SIZE * nsid_state2) >> 16;
+		 *
+		 * We'll perturb it with some random stuff  ...
+		 */
+		j = ((isc_uint32_t) NSID_SHUFFLE_TABLE_SIZE *
+		     (nsid->nsid_state2 ^ compressed_hash)) >> 16;
+		nsid->nsid_state2 = id = nsid->nsid_vtable[j];
+		nsid->nsid_state = (((isc_uint32_t) nsid->nsid_a1 * nsid->nsid_state) +
+				      nsid->nsid_c1) & 0xFFFF;
+		nsid->nsid_vtable[j] = nsid->nsid_state;
+	}
+
+        /* Now lets obfuscate ... */
+        id = (((isc_uint32_t) nsid->nsid_a2 * id) + nsid->nsid_c2) & 0xFFFF;
+        id = (((isc_uint32_t) nsid->nsid_a3 * id) + nsid->nsid_c3) & 0xFFFF;
+
+        return (id);
+}
+
+static isc_result_t
+nsid_init(isc_mem_t *mctx, dns_nsid_t *nsid, isc_boolean_t usepool) {
+        isc_time_t now;
+        pid_t mypid;
+        isc_uint16_t a1ndx, a2ndx, a3ndx, c1ndx, c2ndx, c3ndx;
+        int i;
+
+	isc_time_now(&now);
+        mypid = getpid();
+
+        /* Initialize the state */
+	memset(nsid, 0, sizeof(*nsid));
+        nsid_hash(&now, sizeof now);
+        nsid_hash(&mypid, sizeof mypid);
+
+        /*
+         * Select our random number generators and initial seed.
+         * We could really use more random bits at this point,
+         * but we'll try to make a silk purse out of a sows ear ...
+         */
+        /* generator 1 */
+        a1ndx = ((isc_uint32_t) NSID_MULT_TABLE_SIZE *
+                 (nsid_hash_state & 0xFFFF)) >> 16;
+        nsid->nsid_a1 = nsid_multiplier_table[a1ndx];
+        c1ndx = (nsid_hash_state >> 9) & 0x7FFF;
+        nsid->nsid_c1 = 2 * c1ndx + 1;
+
+        /* generator 2, distinct from 1 */
+        a2ndx = ((isc_uint32_t) (NSID_MULT_TABLE_SIZE - 1) *
+                 ((nsid_hash_state >> 10) & 0xFFFF)) >> 16;
+        if (a2ndx >= a1ndx)
+                a2ndx++;
+        nsid->nsid_a2 = nsid_multiplier_table[a2ndx];
+        c2ndx = nsid_hash_state % 32767;
+        if (c2ndx >= c1ndx)
+                c2ndx++;
+        nsid->nsid_c2 = 2*c2ndx + 1;
+
+        /* generator 3, distinct from 1 and 2 */
+        a3ndx = ((isc_uint32_t) (NSID_MULT_TABLE_SIZE - 2) *
+                 ((nsid_hash_state >> 20) & 0xFFFF)) >> 16;
+        if (a3ndx >= a1ndx || a3ndx >= a2ndx)
+                a3ndx++;
+        if (a3ndx >= a1ndx && a3ndx >= a2ndx)
+                a3ndx++;
+        nsid->nsid_a3 = nsid_multiplier_table[a3ndx];
+        c3ndx = nsid_hash_state % 32766;
+        if (c3ndx >= c1ndx || c3ndx >= c2ndx)
+                c3ndx++;
+        if (c3ndx >= c1ndx && c3ndx >= c2ndx)
+                c3ndx++;
+        nsid->nsid_c3 = 2*c3ndx + 1;
+
+        nsid->nsid_state =
+		((nsid_hash_state >> 16) ^ (nsid_hash_state)) & 0xFFFF;
+
+	nsid->nsid_usepool = usepool;
+	if (nsid->nsid_usepool) {
+                nsid->nsid_pool = isc_mem_get(mctx, 0x10000 * sizeof(isc_uint16_t));
+		if (nsid->nsid_pool == NULL)
+			return (ISC_R_NOMEMORY);
+                for (i = 0; ; i++) {
+                        nsid->nsid_pool[i] = nsid->nsid_state;
+                        nsid->nsid_state =
+				 (((u_long) nsid->nsid_a1 * nsid->nsid_state) +
+				   nsid->nsid_c1) & 0xFFFF;
+                        if (i == 0xFFFF)
+                                break;
+                }
+	} else {
+		nsid->nsid_vtable = isc_mem_get(mctx, NSID_SHUFFLE_TABLE_SIZE *
+						(sizeof(isc_uint16_t)) );
+		if (nsid->nsid_vtable == NULL)
+			return (ISC_R_NOMEMORY);
+
+		for (i = 0; i < NSID_SHUFFLE_TABLE_SIZE; i++) {
+			nsid->nsid_vtable[i] = nsid->nsid_state;
+			nsid->nsid_state =
+				   (((isc_uint32_t) nsid->nsid_a1 * nsid->nsid_state) +
+					 nsid->nsid_c1) & 0xFFFF;
+		}
+		nsid->nsid_state2 = nsid->nsid_state;
+	} 
+	return (ISC_R_SUCCESS);
+}
+
+static void
+nsid_destroy(isc_mem_t *mctx, dns_nsid_t *nsid) {
+	if (nsid->nsid_usepool)
+		isc_mem_put(mctx, nsid->nsid_pool,
+			    0x10000 * sizeof(isc_uint16_t));
+	else
+		isc_mem_put(mctx, nsid->nsid_vtable,
+			    NSID_SHUFFLE_TABLE_SIZE * (sizeof(isc_uint16_t)) );
+	memset(nsid, 0, sizeof(*nsid));
+}
+
+void
+dns_dispatch_hash(void *data, size_t len) {
+	nsid_hash(data, len);
+}