/*
 * Copyright (C) 1999-2002, 2004-2009, 2011-2017  Internet Systems Consortium, Inc. ("ISC")
 *
 * 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 http://mozilla.org/MPL/2.0/.
 */

/*! \file */

#include <config.h>

#include <isc/interfaceiter.h>
#include <isc/os.h>
#include <isc/string.h>
#include <isc/task.h>
#include <isc/util.h>

#include <dns/acl.h>
#include <dns/dispatch.h>

#include <named/client.h>
#include <named/log.h>
#include <named/interfacemgr.h>
#include <named/server.h>

#ifdef HAVE_NET_ROUTE_H
#include <net/route.h>
#if defined(RTM_VERSION) && defined(RTM_NEWADDR) && defined(RTM_DELADDR)
#define USE_ROUTE_SOCKET 1
#define ROUTE_SOCKET_PROTOCOL PF_ROUTE
#define MSGHDR rt_msghdr
#define MSGTYPE rtm_type
#endif
#endif

#if defined(HAVE_LINUX_NETLINK_H) && defined(HAVE_LINUX_RTNETLINK_H)
#include <linux/netlink.h>
#include <linux/rtnetlink.h>
#if defined(RTM_NEWADDR) && defined(RTM_DELADDR)
#define USE_ROUTE_SOCKET 1
#define ROUTE_SOCKET_PROTOCOL PF_NETLINK
#define MSGHDR nlmsghdr
#define MSGTYPE nlmsg_type
#endif
#endif

#ifdef TUNE_LARGE
#define UDPBUFFERS 32768
#else
#define UDPBUFFERS 1000
#endif /* TUNE_LARGE */

#define IFMGR_MAGIC			ISC_MAGIC('I', 'F', 'M', 'G')
#define NS_INTERFACEMGR_VALID(t)	ISC_MAGIC_VALID(t, IFMGR_MAGIC)

#define IFMGR_COMMON_LOGARGS \
	ns_g_lctx, NS_LOGCATEGORY_NETWORK, NS_LOGMODULE_INTERFACEMGR

/*% nameserver interface manager structure */
struct ns_interfacemgr {
	unsigned int		magic;		/*%< Magic number. */
	int			references;
	isc_mutex_t		lock;
	isc_mem_t *		mctx;		/*%< Memory context. */
	isc_taskmgr_t *		taskmgr;	/*%< Task manager. */
	isc_socketmgr_t *	socketmgr;	/*%< Socket manager. */
	dns_dispatchmgr_t *	dispatchmgr;
	unsigned int		generation;	/*%< Current generation no. */
	ns_listenlist_t *	listenon4;
	ns_listenlist_t *	listenon6;
	dns_aclenv_t		aclenv;		/*%< Localhost/localnets ACLs */
	ISC_LIST(ns_interface_t) interfaces;	/*%< List of interfaces. */
	ISC_LIST(isc_sockaddr_t) listenon;
#ifdef USE_ROUTE_SOCKET
	isc_task_t *		task;
	isc_socket_t *		route;
	unsigned char		buf[2048];
#endif
};

static void
purge_old_interfaces(ns_interfacemgr_t *mgr);

static void
clearlistenon(ns_interfacemgr_t *mgr);

#ifdef USE_ROUTE_SOCKET
static void
route_event(isc_task_t *task, isc_event_t *event) {
	isc_socketevent_t *sevent = NULL;
	ns_interfacemgr_t *mgr = NULL;
	isc_region_t r;
	isc_result_t result;
	struct MSGHDR *rtm;
	isc_boolean_t done = ISC_TRUE;

	UNUSED(task);

	REQUIRE(event->ev_type == ISC_SOCKEVENT_RECVDONE);
	mgr = event->ev_arg;
	sevent = (isc_socketevent_t *)event;

	if (sevent->result != ISC_R_SUCCESS) {
		if (sevent->result != ISC_R_CANCELED)
			isc_log_write(IFMGR_COMMON_LOGARGS, ISC_LOG_ERROR,
				      "automatic interface scanning "
				      "terminated: %s",
				      isc_result_totext(sevent->result));
		ns_interfacemgr_detach(&mgr);
		isc_event_free(&event);
		return;
	}

	rtm = (struct MSGHDR *)mgr->buf;
#ifdef RTM_VERSION
	if (rtm->rtm_version != RTM_VERSION) {
		isc_log_write(IFMGR_COMMON_LOGARGS, ISC_LOG_ERROR,
			      "automatic interface rescanning disabled: "
			      "rtm->rtm_version mismatch (%u != %u) "
			      "recompile required", rtm->rtm_version,
			      RTM_VERSION);
		ns_interfacemgr_detach(&mgr);
		isc_event_free(&event);
		return;
	}
#endif

	switch (rtm->MSGTYPE) {
	case RTM_NEWADDR:
	case RTM_DELADDR:
		if (mgr->route != NULL && ns_g_server->interface_auto)
			ns_server_scan_interfaces(ns_g_server);
		break;
	default:
		break;
	}

	LOCK(&mgr->lock);
	if (mgr->route != NULL) {
		/*
		 * Look for next route event.
		 */
		r.base = mgr->buf;
		r.length = sizeof(mgr->buf);
		result = isc_socket_recv(mgr->route, &r, 1, mgr->task,
					 route_event, mgr);
		if (result == ISC_R_SUCCESS)
			done = ISC_FALSE;
	}
	UNLOCK(&mgr->lock);

	if (done)
		ns_interfacemgr_detach(&mgr);
	isc_event_free(&event);
	return;
}
#endif

isc_result_t
ns_interfacemgr_create(isc_mem_t *mctx, isc_taskmgr_t *taskmgr,
		       isc_socketmgr_t *socketmgr,
		       dns_dispatchmgr_t *dispatchmgr,
		       isc_task_t *task, ns_interfacemgr_t **mgrp)
{
	isc_result_t result;
	ns_interfacemgr_t *mgr;

#ifndef USE_ROUTE_SOCKET
	UNUSED(task);
#endif

	REQUIRE(mctx != NULL);
	REQUIRE(mgrp != NULL);
	REQUIRE(*mgrp == NULL);

	mgr = isc_mem_get(mctx, sizeof(*mgr));
	if (mgr == NULL)
		return (ISC_R_NOMEMORY);

	mgr->mctx = NULL;
	isc_mem_attach(mctx, &mgr->mctx);

	result = isc_mutex_init(&mgr->lock);
	if (result != ISC_R_SUCCESS)
		goto cleanup_mem;

	mgr->taskmgr = taskmgr;
	mgr->socketmgr = socketmgr;
	mgr->dispatchmgr = dispatchmgr;
	mgr->generation = 1;
	mgr->listenon4 = NULL;
	mgr->listenon6 = NULL;

	ISC_LIST_INIT(mgr->interfaces);
	ISC_LIST_INIT(mgr->listenon);

	/*
	 * The listen-on lists are initially empty.
	 */
	result = ns_listenlist_create(mctx, &mgr->listenon4);
	if (result != ISC_R_SUCCESS)
		goto cleanup_mem;
	ns_listenlist_attach(mgr->listenon4, &mgr->listenon6);

	result = dns_aclenv_init(mctx, &mgr->aclenv);
	if (result != ISC_R_SUCCESS)
		goto cleanup_listenon;
#ifdef HAVE_GEOIP
	mgr->aclenv.geoip = ns_g_geoip;
#endif

#ifdef USE_ROUTE_SOCKET
	mgr->route = NULL;
	result = isc_socket_create(mgr->socketmgr, ROUTE_SOCKET_PROTOCOL,
				   isc_sockettype_raw, &mgr->route);
	switch (result) {
	case ISC_R_NOPERM:
	case ISC_R_SUCCESS:
	case ISC_R_NOTIMPLEMENTED:
	case ISC_R_FAMILYNOSUPPORT:
	    break;
	default:
		goto cleanup_aclenv;
	}

	mgr->task = NULL;
	if (mgr->route != NULL)
		isc_task_attach(task, &mgr->task);
	mgr->references = (mgr->route != NULL) ? 2 : 1;
#else
	mgr->references = 1;
#endif
	mgr->magic = IFMGR_MAGIC;
	*mgrp = mgr;

#ifdef USE_ROUTE_SOCKET
	if (mgr->route != NULL) {
		isc_region_t r = { mgr->buf, sizeof(mgr->buf) };

		result = isc_socket_recv(mgr->route, &r, 1, mgr->task,
					 route_event, mgr);
		if (result != ISC_R_SUCCESS) {
			isc_task_detach(&mgr->task);
			isc_socket_detach(&mgr->route);
			ns_interfacemgr_detach(&mgr);
		}
	}
#endif
	return (ISC_R_SUCCESS);

#ifdef USE_ROUTE_SOCKET
 cleanup_aclenv:
	dns_aclenv_destroy(&mgr->aclenv);
#endif
 cleanup_listenon:
	ns_listenlist_detach(&mgr->listenon4);
	ns_listenlist_detach(&mgr->listenon6);
 cleanup_mem:
	isc_mem_putanddetach(&mgr->mctx, mgr, sizeof(*mgr));
	return (result);
}

static void
ns_interfacemgr_destroy(ns_interfacemgr_t *mgr) {
	REQUIRE(NS_INTERFACEMGR_VALID(mgr));

#ifdef USE_ROUTE_SOCKET
	if (mgr->route != NULL)
		isc_socket_detach(&mgr->route);
	if (mgr->task != NULL)
		isc_task_detach(&mgr->task);
#endif
	dns_aclenv_destroy(&mgr->aclenv);
	ns_listenlist_detach(&mgr->listenon4);
	ns_listenlist_detach(&mgr->listenon6);
	clearlistenon(mgr);
	DESTROYLOCK(&mgr->lock);
	mgr->magic = 0;
	isc_mem_putanddetach(&mgr->mctx, mgr, sizeof(*mgr));
}

dns_aclenv_t *
ns_interfacemgr_getaclenv(ns_interfacemgr_t *mgr) {
	return (&mgr->aclenv);
}

void
ns_interfacemgr_attach(ns_interfacemgr_t *source, ns_interfacemgr_t **target) {
	REQUIRE(NS_INTERFACEMGR_VALID(source));
	LOCK(&source->lock);
	INSIST(source->references > 0);
	source->references++;
	UNLOCK(&source->lock);
	*target = source;
}

void
ns_interfacemgr_detach(ns_interfacemgr_t **targetp) {
	isc_result_t need_destroy = ISC_FALSE;
	ns_interfacemgr_t *target = *targetp;
	REQUIRE(target != NULL);
	REQUIRE(NS_INTERFACEMGR_VALID(target));
	LOCK(&target->lock);
	REQUIRE(target->references > 0);
	target->references--;
	if (target->references == 0)
		need_destroy = ISC_TRUE;
	UNLOCK(&target->lock);
	if (need_destroy)
		ns_interfacemgr_destroy(target);
	*targetp = NULL;
}

void
ns_interfacemgr_shutdown(ns_interfacemgr_t *mgr) {
	REQUIRE(NS_INTERFACEMGR_VALID(mgr));

	/*%
	 * Shut down and detach all interfaces.
	 * By incrementing the generation count, we make purge_old_interfaces()
	 * consider all interfaces "old".
	 */
	mgr->generation++;
#ifdef USE_ROUTE_SOCKET
	LOCK(&mgr->lock);
	if (mgr->route != NULL) {
		isc_socket_cancel(mgr->route, mgr->task, ISC_SOCKCANCEL_RECV);
		isc_socket_detach(&mgr->route);
		isc_task_detach(&mgr->task);
	}
	UNLOCK(&mgr->lock);
#endif
	purge_old_interfaces(mgr);
}


static isc_result_t
ns_interface_create(ns_interfacemgr_t *mgr, isc_sockaddr_t *addr,
		    const char *name, ns_interface_t **ifpret)
{
	ns_interface_t *ifp;
	isc_result_t result;
	int disp;

	REQUIRE(NS_INTERFACEMGR_VALID(mgr));

	ifp = isc_mem_get(mgr->mctx, sizeof(*ifp));
	if (ifp == NULL)
		return (ISC_R_NOMEMORY);

	ifp->mgr = NULL;
	ifp->generation = mgr->generation;
	ifp->addr = *addr;
	ifp->flags = 0;
	strlcpy(ifp->name, name, sizeof(ifp->name));
	ifp->clientmgr = NULL;

	result = isc_mutex_init(&ifp->lock);
	if (result != ISC_R_SUCCESS)
		goto lock_create_failure;

	result = ns_clientmgr_create(mgr->mctx, mgr->taskmgr,
				     ns_g_timermgr,
				     &ifp->clientmgr);
	if (result != ISC_R_SUCCESS) {
		isc_log_write(IFMGR_COMMON_LOGARGS, ISC_LOG_ERROR,
			      "ns_clientmgr_create() failed: %s",
			      isc_result_totext(result));
		goto clientmgr_create_failure;
	}

	for (disp = 0; disp < MAX_UDP_DISPATCH; disp++)
		ifp->udpdispatch[disp] = NULL;

	ifp->tcpsocket = NULL;

	/*
	 * Create a single TCP client object.  It will replace itself
	 * with a new one as soon as it gets a connection, so the actual
	 * connections will be handled in parallel even though there is
	 * only one client initially.
	 */
	ifp->ntcptarget = 1;
	ifp->ntcpcurrent = 0;
	ifp->nudpdispatch = 0;

	ifp->dscp = -1;

	ISC_LINK_INIT(ifp, link);

	ns_interfacemgr_attach(mgr, &ifp->mgr);
	ISC_LIST_APPEND(mgr->interfaces, ifp, link);

	ifp->references = 1;
	ifp->magic = IFACE_MAGIC;
	*ifpret = ifp;

	return (ISC_R_SUCCESS);

 clientmgr_create_failure:
	DESTROYLOCK(&ifp->lock);

 lock_create_failure:
	ifp->magic = 0;
	isc_mem_put(mgr->mctx, ifp, sizeof(*ifp));

	return (ISC_R_UNEXPECTED);
}

static isc_result_t
ns_interface_listenudp(ns_interface_t *ifp) {
	isc_result_t result;
	unsigned int attrs;
	unsigned int attrmask;
	int disp, i;

	attrs = 0;
	attrs |= DNS_DISPATCHATTR_UDP;
	if (isc_sockaddr_pf(&ifp->addr) == AF_INET)
		attrs |= DNS_DISPATCHATTR_IPV4;
	else
		attrs |= DNS_DISPATCHATTR_IPV6;
	attrs |= DNS_DISPATCHATTR_NOLISTEN;
	attrmask = 0;
	attrmask |= DNS_DISPATCHATTR_UDP | DNS_DISPATCHATTR_TCP;
	attrmask |= DNS_DISPATCHATTR_IPV4 | DNS_DISPATCHATTR_IPV6;

	ifp->nudpdispatch = ISC_MIN(ns_g_udpdisp, MAX_UDP_DISPATCH);
	for (disp = 0; disp < ifp->nudpdispatch; disp++) {
		result = dns_dispatch_getudp_dup(ifp->mgr->dispatchmgr,
						 ns_g_socketmgr,
						 ns_g_taskmgr, &ifp->addr,
						 4096, UDPBUFFERS,
						 32768, 8219, 8237,
						 attrs, attrmask,
						 &ifp->udpdispatch[disp],
						 disp == 0
						    ? NULL
						    : ifp->udpdispatch[0]);
		if (result != ISC_R_SUCCESS) {
			isc_log_write(IFMGR_COMMON_LOGARGS, ISC_LOG_ERROR,
				      "could not listen on UDP socket: %s",
				      isc_result_totext(result));
			goto udp_dispatch_failure;
		}

	}

	result = ns_clientmgr_createclients(ifp->clientmgr, ifp->nudpdispatch,
					    ifp, ISC_FALSE);
	if (result != ISC_R_SUCCESS) {
		UNEXPECTED_ERROR(__FILE__, __LINE__,
				 "UDP ns_clientmgr_createclients(): %s",
				 isc_result_totext(result));
		goto addtodispatch_failure;
	}

	return (ISC_R_SUCCESS);

 addtodispatch_failure:
	for (i = disp - 1; i >= 0; i--) {
		dns_dispatch_changeattributes(ifp->udpdispatch[i], 0,
					      DNS_DISPATCHATTR_NOLISTEN);
		dns_dispatch_detach(&(ifp->udpdispatch[i]));
	}
	ifp->nudpdispatch = 0;

 udp_dispatch_failure:
	return (result);
}

static isc_result_t
ns_interface_accepttcp(ns_interface_t *ifp) {
	isc_result_t result;

	/*
	 * Open a TCP socket.
	 */
	result = isc_socket_create(ifp->mgr->socketmgr,
				   isc_sockaddr_pf(&ifp->addr),
				   isc_sockettype_tcp,
				   &ifp->tcpsocket);
	if (result != ISC_R_SUCCESS) {
		isc_log_write(IFMGR_COMMON_LOGARGS, ISC_LOG_ERROR,
				 "creating TCP socket: %s",
				 isc_result_totext(result));
		goto tcp_socket_failure;
	}
	isc_socket_setname(ifp->tcpsocket, "dispatcher", NULL);
#ifndef ISC_ALLOW_MAPPED
	isc_socket_ipv6only(ifp->tcpsocket, ISC_TRUE);
#endif
	result = isc_socket_bind(ifp->tcpsocket, &ifp->addr,
				 ISC_SOCKET_REUSEADDRESS);
	if (result != ISC_R_SUCCESS) {
		isc_log_write(IFMGR_COMMON_LOGARGS, ISC_LOG_ERROR,
				 "binding TCP socket: %s",
				 isc_result_totext(result));
		goto tcp_bind_failure;
	}

	if (ifp->dscp != -1)
		isc_socket_dscp(ifp->tcpsocket, ifp->dscp);

	result = isc_socket_listen(ifp->tcpsocket, ns_g_listen);
	if (result != ISC_R_SUCCESS) {
		isc_log_write(IFMGR_COMMON_LOGARGS, ISC_LOG_ERROR,
				 "listening on TCP socket: %s",
				 isc_result_totext(result));
		goto tcp_listen_failure;
	}

	/*
	 * If/when there a multiple filters listen to the
	 * result.
	 */
	(void)isc_socket_filter(ifp->tcpsocket, "dataready");

	result = ns_clientmgr_createclients(ifp->clientmgr,
					    ifp->ntcptarget, ifp,
					    ISC_TRUE);
	if (result != ISC_R_SUCCESS) {
		UNEXPECTED_ERROR(__FILE__, __LINE__,
				 "TCP ns_clientmgr_createclients(): %s",
				 isc_result_totext(result));
		goto accepttcp_failure;
	}
	return (ISC_R_SUCCESS);

 accepttcp_failure:
 tcp_listen_failure:
 tcp_bind_failure:
	isc_socket_detach(&ifp->tcpsocket);
 tcp_socket_failure:
	return (result);
}

static isc_result_t
ns_interface_setup(ns_interfacemgr_t *mgr, isc_sockaddr_t *addr,
		   const char *name, ns_interface_t **ifpret,
		   isc_boolean_t accept_tcp, isc_dscp_t dscp,
		   isc_boolean_t *addr_in_use)
{
	isc_result_t result;
	ns_interface_t *ifp = NULL;
	REQUIRE(ifpret != NULL && *ifpret == NULL);
	REQUIRE(addr_in_use == NULL || *addr_in_use == ISC_FALSE);

	result = ns_interface_create(mgr, addr, name, &ifp);
	if (result != ISC_R_SUCCESS)
		return (result);

	ifp->dscp = dscp;

	result = ns_interface_listenudp(ifp);
	if (result != ISC_R_SUCCESS) {
		if ((result == ISC_R_ADDRINUSE) && (addr_in_use != NULL))
			*addr_in_use = ISC_TRUE;
		goto cleanup_interface;
	}

	if (!ns_g_notcp && accept_tcp == ISC_TRUE) {
		result = ns_interface_accepttcp(ifp);
		if (result != ISC_R_SUCCESS) {
			if ((result == ISC_R_ADDRINUSE) &&
			    (addr_in_use != NULL))
				*addr_in_use = ISC_TRUE;

			/*
			 * XXXRTH We don't currently have a way to easily stop
			 * dispatch service, so we currently return
			 * ISC_R_SUCCESS (the UDP stuff will work even if TCP
			 * creation failed).  This will be fixed later.
			 */
			result = ISC_R_SUCCESS;
		}
	}
	*ifpret = ifp;
	return (result);

 cleanup_interface:
	ISC_LIST_UNLINK(ifp->mgr->interfaces, ifp, link);
	ns_interface_detach(&ifp);
	return (result);
}

void
ns_interface_shutdown(ns_interface_t *ifp) {
	if (ifp->clientmgr != NULL)
		ns_clientmgr_destroy(&ifp->clientmgr);
}

static void
ns_interface_destroy(ns_interface_t *ifp) {
	isc_mem_t *mctx = ifp->mgr->mctx;
	int disp;

	REQUIRE(NS_INTERFACE_VALID(ifp));

	ns_interface_shutdown(ifp);

	for (disp = 0; disp < ifp->nudpdispatch; disp++)
		if (ifp->udpdispatch[disp] != NULL) {
			dns_dispatch_changeattributes(ifp->udpdispatch[disp], 0,
						    DNS_DISPATCHATTR_NOLISTEN);
			dns_dispatch_detach(&(ifp->udpdispatch[disp]));
		}

	if (ifp->tcpsocket != NULL)
		isc_socket_detach(&ifp->tcpsocket);

	DESTROYLOCK(&ifp->lock);

	ns_interfacemgr_detach(&ifp->mgr);

	ifp->magic = 0;
	isc_mem_put(mctx, ifp, sizeof(*ifp));
}

void
ns_interface_attach(ns_interface_t *source, ns_interface_t **target) {
	REQUIRE(NS_INTERFACE_VALID(source));
	LOCK(&source->lock);
	INSIST(source->references > 0);
	source->references++;
	UNLOCK(&source->lock);
	*target = source;
}

void
ns_interface_detach(ns_interface_t **targetp) {
	isc_result_t need_destroy = ISC_FALSE;
	ns_interface_t *target = *targetp;
	REQUIRE(target != NULL);
	REQUIRE(NS_INTERFACE_VALID(target));
	LOCK(&target->lock);
	REQUIRE(target->references > 0);
	target->references--;
	if (target->references == 0)
		need_destroy = ISC_TRUE;
	UNLOCK(&target->lock);
	if (need_destroy)
		ns_interface_destroy(target);
	*targetp = NULL;
}

/*%
 * Search the interface list for an interface whose address and port
 * both match those of 'addr'.  Return a pointer to it, or NULL if not found.
 */
static ns_interface_t *
find_matching_interface(ns_interfacemgr_t *mgr, isc_sockaddr_t *addr) {
	ns_interface_t *ifp;
	for (ifp = ISC_LIST_HEAD(mgr->interfaces); ifp != NULL;
	     ifp = ISC_LIST_NEXT(ifp, link)) {
		if (isc_sockaddr_equal(&ifp->addr, addr))
			break;
	}
	return (ifp);
}

/*%
 * Remove any interfaces whose generation number is not the current one.
 */
static void
purge_old_interfaces(ns_interfacemgr_t *mgr) {
	ns_interface_t *ifp, *next;
	for (ifp = ISC_LIST_HEAD(mgr->interfaces); ifp != NULL; ifp = next) {
		INSIST(NS_INTERFACE_VALID(ifp));
		next = ISC_LIST_NEXT(ifp, link);
		if (ifp->generation != mgr->generation) {
			char sabuf[256];
			ISC_LIST_UNLINK(ifp->mgr->interfaces, ifp, link);
			isc_sockaddr_format(&ifp->addr, sabuf, sizeof(sabuf));
			isc_log_write(IFMGR_COMMON_LOGARGS,
				      ISC_LOG_INFO,
				      "no longer listening on %s", sabuf);
			ns_interface_shutdown(ifp);
			ns_interface_detach(&ifp);
		}
	}
}

static isc_result_t
clearacl(isc_mem_t *mctx, dns_acl_t **aclp) {
	dns_acl_t *newacl = NULL;
	isc_result_t result;
	result = dns_acl_create(mctx, 0, &newacl);
	if (result != ISC_R_SUCCESS)
		return (result);
	dns_acl_detach(aclp);
	dns_acl_attach(newacl, aclp);
	dns_acl_detach(&newacl);
	return (ISC_R_SUCCESS);
}

static isc_boolean_t
listenon_is_ip6_any(ns_listenelt_t *elt) {
	REQUIRE(elt && elt->acl);
	return dns_acl_isany(elt->acl);
}

static isc_result_t
setup_locals(ns_interfacemgr_t *mgr, isc_interface_t *interface) {
	isc_result_t result;
	unsigned int prefixlen;
	isc_netaddr_t *netaddr;

	netaddr = &interface->address;

	/* First add localhost address */
	prefixlen = (netaddr->family == AF_INET) ? 32 : 128;
	result = dns_iptable_addprefix(mgr->aclenv.localhost->iptable,
				       netaddr, prefixlen, ISC_TRUE);
	if (result != ISC_R_SUCCESS)
		return (result);

	/* Then add localnets prefix */
	result = isc_netaddr_masktoprefixlen(&interface->netmask,
					     &prefixlen);

	/* Non contiguous netmasks not allowed by IPv6 arch. */
	if (result != ISC_R_SUCCESS && netaddr->family == AF_INET6)
		return (result);

	if (result != ISC_R_SUCCESS) {
		isc_log_write(IFMGR_COMMON_LOGARGS, ISC_LOG_WARNING,
			      "omitting IPv4 interface %s from "
			      "localnets ACL: %s", interface->name,
			      isc_result_totext(result));
		return (ISC_R_SUCCESS);
	}

	if (prefixlen == 0U) {
		isc_log_write(IFMGR_COMMON_LOGARGS, ISC_LOG_WARNING,
			      "omitting %s interface %s from localnets ACL: "
			      "zero prefix length detected",
			      (netaddr->family == AF_INET) ? "IPv4" : "IPv6",
			      interface->name);
		return (ISC_R_SUCCESS);
	}

	result = dns_iptable_addprefix(mgr->aclenv.localnets->iptable,
				       netaddr, prefixlen, ISC_TRUE);
	if (result != ISC_R_SUCCESS)
		return (result);

	return (ISC_R_SUCCESS);
}

static void
setup_listenon(ns_interfacemgr_t *mgr, isc_interface_t *interface,
	       in_port_t port)
{
	isc_sockaddr_t *addr;
	isc_sockaddr_t *old;

	addr = isc_mem_get(mgr->mctx, sizeof(*addr));
	if (addr == NULL)
		return;

	isc_sockaddr_fromnetaddr(addr, &interface->address, port);

	for (old = ISC_LIST_HEAD(mgr->listenon);
	     old != NULL;
	     old = ISC_LIST_NEXT(old, link))
		if (isc_sockaddr_equal(addr, old))
			break;

	if (old != NULL)
		isc_mem_put(mgr->mctx, addr, sizeof(*addr));
	else
		ISC_LIST_APPEND(mgr->listenon, addr, link);
}

static void
clearlistenon(ns_interfacemgr_t *mgr) {
	isc_sockaddr_t *old;

	old = ISC_LIST_HEAD(mgr->listenon);
	while (old != NULL) {
		ISC_LIST_UNLINK(mgr->listenon, old, link);
		isc_mem_put(mgr->mctx, old, sizeof(*old));
		old = ISC_LIST_HEAD(mgr->listenon);
	}
}

static isc_result_t
do_scan(ns_interfacemgr_t *mgr, ns_listenlist_t *ext_listen,
	isc_boolean_t verbose)
{
	isc_interfaceiter_t *iter = NULL;
	isc_boolean_t scan_ipv4 = ISC_FALSE;
	isc_boolean_t scan_ipv6 = ISC_FALSE;
	isc_boolean_t adjusting = ISC_FALSE;
	isc_boolean_t ipv6only = ISC_TRUE;
	isc_boolean_t ipv6pktinfo = ISC_TRUE;
	isc_result_t result;
	isc_netaddr_t zero_address, zero_address6;
	ns_listenelt_t *le;
	isc_sockaddr_t listen_addr;
	ns_interface_t *ifp;
	isc_boolean_t log_explicit = ISC_FALSE;
	isc_boolean_t dolistenon;
	char sabuf[ISC_SOCKADDR_FORMATSIZE];
	isc_boolean_t tried_listening;
	isc_boolean_t all_addresses_in_use;

	if (ext_listen != NULL)
		adjusting = ISC_TRUE;

	if (isc_net_probeipv6() == ISC_R_SUCCESS)
		scan_ipv6 = ISC_TRUE;
#ifdef WANT_IPV6
	else if (!ns_g_disable6)
		isc_log_write(IFMGR_COMMON_LOGARGS,
			      verbose ? ISC_LOG_INFO : ISC_LOG_DEBUG(1),
			      "no IPv6 interfaces found");
#endif

	if (isc_net_probeipv4() == ISC_R_SUCCESS)
		scan_ipv4 = ISC_TRUE;
	else if (!ns_g_disable4)
		isc_log_write(IFMGR_COMMON_LOGARGS,
			      verbose ? ISC_LOG_INFO : ISC_LOG_DEBUG(1),
			      "no IPv4 interfaces found");

	/*
	 * A special, but typical case; listen-on-v6 { any; }.
	 * When we can make the socket IPv6-only, open a single wildcard
	 * socket for IPv6 communication.  Otherwise, make separate socket
	 * for each IPv6 address in order to avoid accepting IPv4 packets
	 * as the form of mapped addresses unintentionally unless explicitly
	 * allowed.
	 */
#ifndef ISC_ALLOW_MAPPED
	if (scan_ipv6 == ISC_TRUE &&
	    isc_net_probe_ipv6only() != ISC_R_SUCCESS) {
		ipv6only = ISC_FALSE;
		log_explicit = ISC_TRUE;
	}
#endif
	if (scan_ipv6 == ISC_TRUE &&
	    isc_net_probe_ipv6pktinfo() != ISC_R_SUCCESS) {
		ipv6pktinfo = ISC_FALSE;
		log_explicit = ISC_TRUE;
	}
	if (scan_ipv6 == ISC_TRUE && ipv6only && ipv6pktinfo) {
		for (le = ISC_LIST_HEAD(mgr->listenon6->elts);
		     le != NULL;
		     le = ISC_LIST_NEXT(le, link)) {
			struct in6_addr in6a;

			if (!listenon_is_ip6_any(le))
				continue;

			in6a = in6addr_any;
			isc_sockaddr_fromin6(&listen_addr, &in6a, le->port);

			ifp = find_matching_interface(mgr, &listen_addr);
			if (ifp != NULL) {
				ifp->generation = mgr->generation;
				if (le->dscp != -1 && ifp->dscp == -1)
					ifp->dscp = le->dscp;
				else if (le->dscp != ifp->dscp) {
					isc_sockaddr_format(&listen_addr,
							    sabuf,
							    sizeof(sabuf));
					isc_log_write(IFMGR_COMMON_LOGARGS,
						      ISC_LOG_WARNING,
						      "%s: conflicting DSCP "
						      "values, using %d",
						      sabuf, ifp->dscp);
				}
			} else {
				isc_log_write(IFMGR_COMMON_LOGARGS,
					      ISC_LOG_INFO,
					      "listening on IPv6 "
					      "interfaces, port %u",
					      le->port);
				result = ns_interface_setup(mgr, &listen_addr,
							    "<any>", &ifp,
							    ISC_TRUE,
							    le->dscp,
							    NULL);
				if (result == ISC_R_SUCCESS)
					ifp->flags |= NS_INTERFACEFLAG_ANYADDR;
				else
					isc_log_write(IFMGR_COMMON_LOGARGS,
						      ISC_LOG_ERROR,
						      "listening on all IPv6 "
						      "interfaces failed");
				/* Continue. */
			}
		}
	}

	isc_netaddr_any(&zero_address);
	isc_netaddr_any6(&zero_address6);

	result = isc_interfaceiter_create(mgr->mctx, &iter);
	if (result != ISC_R_SUCCESS)
		return (result);

	if (adjusting == ISC_FALSE) {
		result = clearacl(mgr->mctx, &mgr->aclenv.localhost);
		if (result != ISC_R_SUCCESS)
			goto cleanup_iter;
		result = clearacl(mgr->mctx, &mgr->aclenv.localnets);
		if (result != ISC_R_SUCCESS)
			goto cleanup_iter;
		clearlistenon(mgr);
	}

	tried_listening = ISC_FALSE;
	all_addresses_in_use = ISC_TRUE;
	for (result = isc_interfaceiter_first(iter);
	     result == ISC_R_SUCCESS;
	     result = isc_interfaceiter_next(iter))
	{
		isc_interface_t interface;
		ns_listenlist_t *ll;
		unsigned int family;

		result = isc_interfaceiter_current(iter, &interface);
		if (result != ISC_R_SUCCESS)
			break;

		family = interface.address.family;
		if (family != AF_INET && family != AF_INET6)
			continue;
		if (scan_ipv4 == ISC_FALSE && family == AF_INET)
			continue;
		if (scan_ipv6 == ISC_FALSE && family == AF_INET6)
			continue;

		/*
		 * Test for the address being nonzero rather than testing
		 * INTERFACE_F_UP, because on some systems the latter
		 * follows the media state and we could end up ignoring
		 * the interface for an entire rescan interval due to
		 * a temporary media glitch at rescan time.
		 */
		if (family == AF_INET &&
		    isc_netaddr_equal(&interface.address, &zero_address)) {
			continue;
		}
		if (family == AF_INET6 &&
		    isc_netaddr_equal(&interface.address, &zero_address6)) {
			continue;
		}

		if (adjusting == ISC_FALSE) {
			/*
			 * If running with -T fixedlocal, then we only
			 * want 127.0.0.1 and ::1 in the localhost ACL.
			 */
			if (ns_g_fixedlocal &&
			    !isc_netaddr_isloopback(&interface.address))
			{
				goto listenon;
			}

			result = setup_locals(mgr, &interface);
			if (result != ISC_R_SUCCESS)
				goto ignore_interface;
		}

 listenon:
		ll = (family == AF_INET) ? mgr->listenon4 : mgr->listenon6;
		dolistenon = ISC_TRUE;
		for (le = ISC_LIST_HEAD(ll->elts);
		     le != NULL;
		     le = ISC_LIST_NEXT(le, link))
		{
			int match;
			isc_boolean_t ipv6_wildcard = ISC_FALSE;
			isc_netaddr_t listen_netaddr;
			isc_sockaddr_t listen_sockaddr;

			/*
			 * Construct a socket address for this IP/port
			 * combination.
			 */
			if (family == AF_INET) {
				isc_netaddr_fromin(&listen_netaddr,
						   &interface.address.type.in);
			} else {
				isc_netaddr_fromin6(&listen_netaddr,
						    &interface.address.type.in6);
				isc_netaddr_setzone(&listen_netaddr,
						    interface.address.zone);
			}
			isc_sockaddr_fromnetaddr(&listen_sockaddr,
						 &listen_netaddr,
						 le->port);

			/*
			 * See if the address matches the listen-on statement;
			 * if not, ignore the interface.
			 */
			(void)dns_acl_match(&listen_netaddr, NULL, le->acl,
					    &mgr->aclenv, &match, NULL);
			if (match <= 0)
				continue;

			if (adjusting == ISC_FALSE && dolistenon == ISC_TRUE) {
				setup_listenon(mgr, &interface, le->port);
				dolistenon = ISC_FALSE;
			}

			/*
			 * The case of "any" IPv6 address will require
			 * special considerations later, so remember it.
			 */
			if (family == AF_INET6 && ipv6only && ipv6pktinfo &&
			    listenon_is_ip6_any(le))
				ipv6_wildcard = ISC_TRUE;

			/*
			 * When adjusting interfaces with extra a listening
			 * list, see if the address matches the extra list.
			 * If it does, and is also covered by a wildcard
			 * interface, we need to listen on the address
			 * explicitly.
			 */
			if (adjusting == ISC_TRUE) {
				ns_listenelt_t *ele;

				match = 0;
				for (ele = ISC_LIST_HEAD(ext_listen->elts);
				     ele != NULL;
				     ele = ISC_LIST_NEXT(ele, link)) {
					(void)dns_acl_match(&listen_netaddr,
							    NULL, ele->acl,
							    NULL, &match, NULL);
					if (match > 0 &&
					    (ele->port == le->port ||
					    ele->port == 0))
						break;
					else
						match = 0;
				}
				if (ipv6_wildcard == ISC_TRUE && match == 0)
					continue;
			}

			ifp = find_matching_interface(mgr, &listen_sockaddr);
			if (ifp != NULL) {
				ifp->generation = mgr->generation;
				if (le->dscp != -1 && ifp->dscp == -1)
					ifp->dscp = le->dscp;
				else if (le->dscp != ifp->dscp) {
					isc_sockaddr_format(&listen_sockaddr,
							    sabuf,
							    sizeof(sabuf));
					isc_log_write(IFMGR_COMMON_LOGARGS,
						      ISC_LOG_WARNING,
						      "%s: conflicting DSCP "
						      "values, using %d",
						      sabuf, ifp->dscp);
				}
			} else {
				isc_boolean_t addr_in_use = ISC_FALSE;

				if (adjusting == ISC_FALSE &&
				    ipv6_wildcard == ISC_TRUE)
					continue;

				if (log_explicit && family == AF_INET6 &&
				    !adjusting && listenon_is_ip6_any(le)) {
					isc_log_write(IFMGR_COMMON_LOGARGS,
						      verbose ? ISC_LOG_INFO :
							      ISC_LOG_DEBUG(1),
						      "IPv6 socket API is "
						      "incomplete; explicitly "
						      "binding to each IPv6 "
						      "address separately");
					log_explicit = ISC_FALSE;
				}
				isc_sockaddr_format(&listen_sockaddr,
						    sabuf, sizeof(sabuf));
				isc_log_write(IFMGR_COMMON_LOGARGS,
					      ISC_LOG_INFO,
					      "%s"
					      "listening on %s interface "
					      "%s, %s",
					      (adjusting == ISC_TRUE) ?
					      "additionally " : "",
					      (family == AF_INET) ?
					      "IPv4" : "IPv6",
					      interface.name, sabuf);

				result = ns_interface_setup(mgr,
						    &listen_sockaddr,
						    interface.name,
						    &ifp,
						    (adjusting == ISC_TRUE) ?
						    ISC_FALSE : ISC_TRUE,
						    le->dscp,
						    &addr_in_use);

				tried_listening = ISC_TRUE;
				if (!addr_in_use)
					all_addresses_in_use = ISC_FALSE;

				if (result != ISC_R_SUCCESS) {
					isc_log_write(IFMGR_COMMON_LOGARGS,
						      ISC_LOG_ERROR,
						      "creating %s interface "
						      "%s failed; interface "
						      "ignored",
						      (family == AF_INET) ?
						      "IPv4" : "IPv6",
						      interface.name);
				}
				/* Continue. */
			}

		}
		continue;

	ignore_interface:
		isc_log_write(IFMGR_COMMON_LOGARGS,
			      ISC_LOG_ERROR,
			      "ignoring %s interface %s: %s",
			      (family == AF_INET) ? "IPv4" : "IPv6",
			      interface.name, isc_result_totext(result));
		continue;
	}
	if (result != ISC_R_NOMORE)
		UNEXPECTED_ERROR(__FILE__, __LINE__,
				 "interface iteration failed: %s",
				 isc_result_totext(result));
	else
		result = ((tried_listening && all_addresses_in_use) ?
			  ISC_R_ADDRINUSE : ISC_R_SUCCESS);
 cleanup_iter:
	isc_interfaceiter_destroy(&iter);
	return (result);
}

static isc_result_t
ns_interfacemgr_scan0(ns_interfacemgr_t *mgr, ns_listenlist_t *ext_listen,
		      isc_boolean_t verbose)
{
	isc_result_t result;
	isc_boolean_t purge = ISC_TRUE;

	REQUIRE(NS_INTERFACEMGR_VALID(mgr));

	mgr->generation++;	/* Increment the generation count. */

	result = do_scan(mgr, ext_listen, verbose);
	if ((result != ISC_R_SUCCESS) && (result != ISC_R_ADDRINUSE))
		purge = ISC_FALSE;

	/*
	 * Now go through the interface list and delete anything that
	 * does not have the current generation number.  This is
	 * how we catch interfaces that go away or change their
	 * addresses.
	 */
	if (purge)
		purge_old_interfaces(mgr);

	/*
	 * Warn if we are not listening on any interface, unless
	 * we're in lwresd-only mode, in which case that is to
	 * be expected.
	 */
	if (ext_listen == NULL &&
	    ISC_LIST_EMPTY(mgr->interfaces) && ! ns_g_lwresdonly) {
		isc_log_write(IFMGR_COMMON_LOGARGS, ISC_LOG_WARNING,
			      "not listening on any interfaces");
	}

	return (result);
}

isc_boolean_t
ns_interfacemgr_islistening(ns_interfacemgr_t *mgr) {
	REQUIRE(NS_INTERFACEMGR_VALID(mgr));

	return (ISC_LIST_EMPTY(mgr->interfaces) ? ISC_FALSE : ISC_TRUE);
}

isc_result_t
ns_interfacemgr_scan(ns_interfacemgr_t *mgr, isc_boolean_t verbose) {
	return (ns_interfacemgr_scan0(mgr, NULL, verbose));
}

isc_result_t
ns_interfacemgr_adjust(ns_interfacemgr_t *mgr, ns_listenlist_t *list,
		       isc_boolean_t verbose)
{
	return (ns_interfacemgr_scan0(mgr, list, verbose));
}

void
ns_interfacemgr_setlistenon4(ns_interfacemgr_t *mgr, ns_listenlist_t *value) {
	LOCK(&mgr->lock);
	ns_listenlist_detach(&mgr->listenon4);
	ns_listenlist_attach(value, &mgr->listenon4);
	UNLOCK(&mgr->lock);
}

void
ns_interfacemgr_setlistenon6(ns_interfacemgr_t *mgr, ns_listenlist_t *value) {
	LOCK(&mgr->lock);
	ns_listenlist_detach(&mgr->listenon6);
	ns_listenlist_attach(value, &mgr->listenon6);
	UNLOCK(&mgr->lock);
}

void
ns_interfacemgr_dumprecursing(FILE *f, ns_interfacemgr_t *mgr) {
	ns_interface_t *interface;

	LOCK(&mgr->lock);
	interface = ISC_LIST_HEAD(mgr->interfaces);
	while (interface != NULL) {
		if (interface->clientmgr != NULL)
			ns_client_dumprecursing(f, interface->clientmgr);
		interface = ISC_LIST_NEXT(interface, link);
	}
	UNLOCK(&mgr->lock);
}

isc_boolean_t
ns_interfacemgr_listeningon(ns_interfacemgr_t *mgr, isc_sockaddr_t *addr) {
	isc_sockaddr_t *old;

	for (old = ISC_LIST_HEAD(mgr->listenon);
	     old != NULL;
	     old = ISC_LIST_NEXT(old, link))
		if (isc_sockaddr_equal(old, addr))
			return (ISC_TRUE);
	return (ISC_FALSE);
}
