bin/named/interfacemgr.c

	interfacemgr.c revision 55670a1e5517e9587171e9f41dc8f3e40b6fcfef
/*
 * Copyright (C) 2004-2009, 2011  Internet Systems Consortium, Inc. ("ISC")
 * Copyright (C) 1999-2002  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: interfacemgr.c,v 1.101 2011/11/09 18:44:03 each Exp $ */

/*! \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>

#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;
};

static void
purge_old_interfaces(ns_interfacemgr_t *mgr);

static void
clearlistenon(ns_interfacemgr_t *mgr);

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

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

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

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

    mgr->mctx = mctx;
    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;

    mgr->references = 1;
    mgr->magic = IFMGR_MAGIC;
    *mgrp = mgr;
    return (ISC_R_SUCCESS);

 cleanup_listenon:
    ns_listenlist_detach(&mgr->listenon4);
    ns_listenlist_detach(&mgr->listenon6);
 cleanup_mem:
    isc_mem_put(mctx, mgr, sizeof(*mgr));
    return (result);
}

static void
ns_interfacemgr_destroy(ns_interfacemgr_t *mgr) {
    REQUIRE(NS_INTERFACEMGR_VALID(mgr));
    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_put(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++;
    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;
    strncpy(ifp->name, name, sizeof(ifp->name));
    ifp->name[sizeof(ifp->name)-1] = '\0';
    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;

    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, 1000, 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;
    }
    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 (ISC_R_SUCCESS);
}

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_result_t result;
    ns_interface_t *ifp = NULL;
    REQUIRE(ifpret != NULL && *ifpret == NULL);

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

    result = ns_interface_listenudp(ifp);
    if (result != ISC_R_SUCCESS)
        goto cleanup_interface;

    if (accept_tcp == ISC_TRUE) {
        result = ns_interface_accepttcp(ifp);
        if (result != ISC_R_SUCCESS) {
            /*
             * 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);
    }

    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;

    if (ext_listen != NULL)
        adjusting = ISC_TRUE;

    if (isc_net_probeipv6() == ISC_R_SUCCESS)
        scan_ipv6 = ISC_TRUE;
#ifdef WANT_IPV6
    else
        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
        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;
            } 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);
                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);
    }

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

        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;
            } else {
                char sabuf[ISC_SOCKADDR_FORMATSIZE];

                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);

                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 = ISC_R_SUCCESS;
 cleanup_iter:
    isc_interfaceiter_destroy(&iter);
    return (result);
}

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

    REQUIRE(NS_INTERFACEMGR_VALID(mgr));

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

    if (do_scan(mgr, ext_listen, verbose) != ISC_R_SUCCESS)
        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");
    }
}

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

void
ns_interfacemgr_adjust(ns_interfacemgr_t *mgr, ns_listenlist_t *list,
               isc_boolean_t verbose)
{
    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);
}