bin/named/interfacemgr.c

	interfacemgr.c revision 15a44745412679c30a6d022733925af70a38b715
/*
 * Copyright (C) 1999, 2000  Internet Software Consortium.
 *
 * Permission to use, copy, modify, and 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 INTERNET SOFTWARE CONSORTIUM
 * DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL
 * INTERNET SOFTWARE CONSORTIUM 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 1.47 2000/07/27 09:36:49 tale Exp $ */

#include <config.h>

#include <isc/interfaceiter.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     0x49464D47U /* IFMG. */
#define NS_INTERFACEMGR_VALID(t) ISC_MAGIC_VALID(t, IFMGR_MAGIC)

#define IFMGR_COMMON_LOGARGS \
    ns_g_lctx, NS_LOGCATEGORY_NETWORK, NS_LOGMODULE_INTERFACEMGR

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;
    ns_clientmgr_t *    clientmgr;  /* Client manager. */
    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. */
};

static void
purge_old_interfaces(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_clientmgr_t *clientmgr, 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->clientmgr = clientmgr;
    mgr->generation = 1;
    mgr->listenon4 = NULL;
    mgr->listenon6 = NULL;
    ISC_LIST_INIT(mgr->interfaces);

    /*
     * 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);
    isc_mutex_destroy(&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;

    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;
    strncpy(ifp->name, name, sizeof(ifp->name));
    ifp->name[sizeof(ifp->name)-1] = '\0';

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

    /*
     * Create a task.
     */
    ifp->task = NULL;
    result = isc_task_create(mgr->taskmgr, 0, &ifp->task);
    if (result != ISC_R_SUCCESS) {
        isc_log_write(IFMGR_COMMON_LOGARGS, ISC_LOG_ERROR,
                 "isc_task_create() failed: %s",
                 isc_result_totext(result));
        goto task_create_failure;
    }
    isc_task_setname(ifp->task, "ifp", ifp);

    ifp->udpdispatch = 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;

    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);

 task_create_failure:
    isc_mutex_destroy(&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;

    attrs = 0;
    attrs |= DNS_DISPATCHATTR_UDP;
    if (isc_sockaddr_pf(&ifp->addr) == AF_INET)
        attrs |= DNS_DISPATCHATTR_IPV4;
    else
        attrs |= DNS_DISPATCHATTR_IPV6;
    attrmask = 0;
    attrmask |= DNS_DISPATCHATTR_UDP | DNS_DISPATCHATTR_TCP;
    attrmask |= DNS_DISPATCHATTR_IPV4 | DNS_DISPATCHATTR_IPV6;
    result = dns_dispatch_getudp(ifp->mgr->dispatchmgr, ns_g_socketmgr,
                     ns_g_taskmgr, &ifp->addr,
                     4096, 1000, 32768, 8219, 8237,
                     attrs, attrmask, &ifp->udpdispatch);
    if (result != ISC_R_SUCCESS) {
        UNEXPECTED_ERROR(__FILE__, __LINE__,
                 "UDP dns_dispatch_create(): %s",
                 isc_result_totext(result));
        goto udp_dispatch_failure;
    }

    result = ns_clientmgr_createclients(ifp->mgr->clientmgr, ns_g_cpus,
                        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:
    dns_dispatch_detach(&ifp->udpdispatch);
 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;
    }
    result = isc_socket_bind(ifp->tcpsocket, &ifp->addr);
    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, 0);
    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;
    }

    result = ns_clientmgr_createclients(ifp->mgr->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_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;

    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 return 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 (ISC_R_SUCCESS);

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

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

    if (ifp->udpdispatch != NULL)
        dns_dispatch_detach(&ifp->udpdispatch);
    if (ifp->tcpsocket != NULL) {
        isc_socket_detach(&ifp->tcpsocket);
    }

    isc_task_detach(&ifp->task);
    isc_mutex_destroy(&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_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, 10, &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 void
do_ipv4(ns_interfacemgr_t *mgr) {
    isc_interfaceiter_t *iter = NULL;
    isc_result_t result;

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

    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;

    for (result = isc_interfaceiter_first(iter);
         result == ISC_R_SUCCESS;
         result = isc_interfaceiter_next(iter))
    {
        ns_interface_t *ifp;
        isc_interface_t interface;
        ns_listenelt_t *le;
        dns_aclelement_t elt;
        unsigned int prefixlen;

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

        if (interface.address.family != AF_INET)
            continue;

        if ((interface.flags & INTERFACE_F_UP) == 0)
            continue;

        result = isc_netaddr_masktoprefixlen(&interface.netmask,
                             &prefixlen);
        if (result != ISC_R_SUCCESS)
            goto ignore_interface;
        elt.type = dns_aclelementtype_ipprefix;
        elt.negative = ISC_FALSE;
        elt.u.ip_prefix.address = interface.address;
        elt.u.ip_prefix.prefixlen = prefixlen;
        /* XXX suppress duplicates */
        result = dns_acl_appendelement(mgr->aclenv.localnets, &elt);
        if (result != ISC_R_SUCCESS)
            goto ignore_interface;
        elt.u.ip_prefix.prefixlen = 32;
        result = dns_acl_appendelement(mgr->aclenv.localhost, &elt);
        if (result != ISC_R_SUCCESS)
            goto ignore_interface;

        for (le = ISC_LIST_HEAD(mgr->listenon4->elts);
             le != NULL;
             le = ISC_LIST_NEXT(le, link))
        {
            int match;
            isc_netaddr_t listen_netaddr;
            isc_sockaddr_t listen_sockaddr;

            /*
             * Construct a socket address for this IP/port
             * combination.
             */
            isc_netaddr_fromin(&listen_netaddr,
                       &interface.address.type.in);
            isc_sockaddr_fromnetaddr(&listen_sockaddr,
                         &listen_netaddr,
                         le->port);

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

            ifp = find_matching_interface(mgr, &listen_sockaddr);
            if (ifp != NULL) {
                ifp->generation = mgr->generation;
            } else {
                char sabuf[256];
                isc_sockaddr_format(&listen_sockaddr,
                            sabuf, sizeof(sabuf));
                isc_log_write(IFMGR_COMMON_LOGARGS,
                          ISC_LOG_INFO,
                          "listening on IPv4 interface "
                          "%s, %s", interface.name, sabuf);

                result = ns_interface_setup(mgr,
                                &listen_sockaddr,
                                interface.name,
                                &ifp);
                if (result != ISC_R_SUCCESS) {
                    isc_log_write(IFMGR_COMMON_LOGARGS,
                         ISC_LOG_ERROR,
                         "creating IPv4 interface %s "
                         "failed; interface ignored",
                         interface.name);
                }
                /* Continue. */
            }

        }
        continue;

    ignore_interface:
        isc_log_write(IFMGR_COMMON_LOGARGS,
                  ISC_LOG_ERROR,
                  "ignoring IPv4 interface %s: %s",
                  interface.name, isc_result_totext(result));
        continue;
    }
    if (result != ISC_R_NOMORE)
        UNEXPECTED_ERROR(__FILE__, __LINE__,
                 "IPv4: interface iteration failed: %s",
                 isc_result_totext(result));
 cleanup_iter:
    isc_interfaceiter_destroy(&iter);
}

static isc_boolean_t
listenon_is_ip6_none(ns_listenlist_t *p) {
    ns_listenelt_t *elt;
    if (ISC_LIST_EMPTY(p->elts))
        return (ISC_TRUE); /* No listen-on-v6 statements */
    elt = ISC_LIST_HEAD(p->elts);
    if (ISC_LIST_NEXT(elt, link) != NULL)
        return (ISC_FALSE); /* More than one listen-on-v6 stmt */
    if (elt->acl->length == 0)
        return (ISC_TRUE); /* listen-on-v6 { } */
    if (elt->acl->length > 1)
        return (ISC_FALSE);  /* listen-on-v6 { ...; ...; } */
    if (elt->acl->elements[0].negative == ISC_TRUE &&
        elt->acl->elements[0].type == dns_aclelementtype_any)
        return (ISC_TRUE);  /* listen-on-v6 { none; } */
    return (ISC_FALSE); /* All others */
}

static isc_boolean_t
listenon_is_ip6_any(ns_listenlist_t *p, in_port_t *portp) {
    ns_listenelt_t *elt;
    if (ISC_LIST_EMPTY(p->elts))
        return (ISC_FALSE); /* No listen-on-v6 statements */
    elt = ISC_LIST_HEAD(p->elts);
    if (ISC_LIST_NEXT(elt, link) != NULL)
        return (ISC_FALSE); /* More than one listen-on-v6 stmt */
    if (elt->acl->length != 1)
        return (ISC_FALSE);
    if (elt->acl->elements[0].negative == ISC_FALSE &&
        elt->acl->elements[0].type == dns_aclelementtype_any) {
        *portp = elt->port;
        return (ISC_TRUE);  /* listen-on-v6 { any; } */
    }
    return (ISC_FALSE); /* All others */
}

static void
do_ipv6(ns_interfacemgr_t *mgr) {
    isc_result_t result;
    ns_interface_t *ifp;
    isc_sockaddr_t listen_addr;
    struct in6_addr in6a;
    in_port_t port;

    if (listenon_is_ip6_none(mgr->listenon6))
        return;

    if (! listenon_is_ip6_any(mgr->listenon6, &port)) {
        isc_log_write(IFMGR_COMMON_LOGARGS,
              ISC_LOG_ERROR,
              "bad IPv6 listen-on list: must be 'any' or 'none'");
        return;
    }

    in6a = in6addr_any;
    isc_sockaddr_fromin6(&listen_addr, &in6a, 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", port);
        result = ns_interface_setup(mgr, &listen_addr, "<any>", &ifp);
        if (result != ISC_R_SUCCESS) {
            isc_log_write(IFMGR_COMMON_LOGARGS,
                      ISC_LOG_ERROR,
                      "listening on IPv6 interfaces failed");
            /* Continue. */
        }
    }
}

void
ns_interfacemgr_scan(ns_interfacemgr_t *mgr, isc_boolean_t verbose) {

    REQUIRE(NS_INTERFACEMGR_VALID(mgr));

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

    if (isc_net_probeipv6() == ISC_R_SUCCESS) {
        do_ipv6(mgr);
    } else
        isc_log_write(IFMGR_COMMON_LOGARGS,
                  verbose ? ISC_LOG_INFO : ISC_LOG_DEBUG(1),
                  "no IPv6 interfaces found");
    if (isc_net_probeipv4() == ISC_R_SUCCESS)
        do_ipv4(mgr);
    else
        isc_log_write(IFMGR_COMMON_LOGARGS,
                  verbose ? ISC_LOG_INFO : ISC_LOG_DEBUG(1),
                  "no IPv4 interfaces found");

        /*
         * 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.
     */
    purge_old_interfaces(mgr);

    if (ISC_LIST_EMPTY(mgr->interfaces)) {
        isc_log_write(IFMGR_COMMON_LOGARGS, ISC_LOG_WARNING,
                  "not listening on any interfaces");
        /*
         * Continue anyway.
         */
    }
}

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);
}

isc_result_t
ns_interfacemgr_findudpdispatcher(ns_interfacemgr_t *mgr,
                  isc_sockaddr_t *address,
                  dns_dispatch_t **dispatchp)
{
    ns_interface_t *ifp;

    /*
     * Find a UDP dispatcher matching 'address', if it exists.
     */

    ifp = find_matching_interface(mgr, address);
    if (ifp == NULL || ifp->udpdispatch == NULL)
        return (ISC_R_NOTFOUND);
    dns_dispatch_attach(ifp->udpdispatch, dispatchp);

    return (ISC_R_SUCCESS);
}