bin/named/controlconf.c

	controlconf.c revision ec5347e2c775f027573ce5648b910361aa926c01
/*
 * Copyright (C) 2004-2007  Internet Systems Consortium, Inc. ("ISC")
 * Copyright (C) 2001-2003  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: controlconf.c,v 1.54 2007/06/18 23:47:18 tbox Exp $ */

/*! \file */

#include <config.h>

#include <isc/base64.h>
#include <isc/buffer.h>
#include <isc/event.h>
#include <isc/mem.h>
#include <isc/net.h>
#include <isc/netaddr.h>
#include <isc/random.h>
#include <isc/result.h>
#include <isc/stdtime.h>
#include <isc/string.h>
#include <isc/timer.h>
#include <isc/util.h>

#include <isccfg/namedconf.h>

#include <bind9/check.h>

#include <isccc/alist.h>
#include <isccc/cc.h>
#include <isccc/ccmsg.h>
#include <isccc/events.h>
#include <isccc/result.h>
#include <isccc/sexpr.h>
#include <isccc/symtab.h>
#include <isccc/util.h>

#include <dns/result.h>

#include <named/config.h>
#include <named/control.h>
#include <named/log.h>
#include <named/server.h>

/*
 * Note: Listeners and connections are not locked.  All event handlers are
 * executed by the server task, and all callers of exported routines must
 * be running under the server task.
 */

typedef struct controlkey controlkey_t;
typedef ISC_LIST(controlkey_t) controlkeylist_t;

typedef struct controlconnection controlconnection_t;
typedef ISC_LIST(controlconnection_t) controlconnectionlist_t;

typedef struct controllistener controllistener_t;
typedef ISC_LIST(controllistener_t) controllistenerlist_t;

struct controlkey {
    char *              keyname;
    isc_region_t            secret;
    ISC_LINK(controlkey_t)      link;
};

struct controlconnection {
    isc_socket_t *          sock;
    isccc_ccmsg_t           ccmsg;
    isc_boolean_t           ccmsg_valid;
    isc_boolean_t           sending;
    isc_timer_t *           timer;
    unsigned char           buffer[2048];
    controllistener_t *     listener;
    isc_uint32_t            nonce;
    ISC_LINK(controlconnection_t)   link;
};

struct controllistener {
    ns_controls_t *         controls;
    isc_mem_t *         mctx;
    isc_task_t *            task;
    isc_sockaddr_t          address;
    isc_socket_t *          sock;
    dns_acl_t *         acl;
    isc_boolean_t           listening;
    isc_boolean_t           exiting;
    controlkeylist_t        keys;
    controlconnectionlist_t     connections;
    isc_sockettype_t        type;
    isc_uint32_t            perm;
    isc_uint32_t            owner;
    isc_uint32_t            group;
    ISC_LINK(controllistener_t) link;
};

struct ns_controls {
    ns_server_t         *server;
    controllistenerlist_t       listeners;
    isc_boolean_t           shuttingdown;
    isccc_symtab_t          *symtab;
};

static void control_newconn(isc_task_t *task, isc_event_t *event);
static void control_recvmessage(isc_task_t *task, isc_event_t *event);

#define CLOCKSKEW 300

static void
free_controlkey(controlkey_t *key, isc_mem_t *mctx) {
    if (key->keyname != NULL)
        isc_mem_free(mctx, key->keyname);
    if (key->secret.base != NULL)
        isc_mem_put(mctx, key->secret.base, key->secret.length);
    isc_mem_put(mctx, key, sizeof(*key));
}

static void
free_controlkeylist(controlkeylist_t *keylist, isc_mem_t *mctx) {
    while (!ISC_LIST_EMPTY(*keylist)) {
        controlkey_t *key = ISC_LIST_HEAD(*keylist);
        ISC_LIST_UNLINK(*keylist, key, link);
        free_controlkey(key, mctx);
    }
}

static void
free_listener(controllistener_t *listener) {
    INSIST(listener->exiting);
    INSIST(!listener->listening);
    INSIST(ISC_LIST_EMPTY(listener->connections));

    if (listener->sock != NULL)
        isc_socket_detach(&listener->sock);

    free_controlkeylist(&listener->keys, listener->mctx);

    if (listener->acl != NULL)
        dns_acl_detach(&listener->acl);

    isc_mem_put(listener->mctx, listener, sizeof(*listener));
}

static void
maybe_free_listener(controllistener_t *listener) {
    if (listener->exiting &&
        !listener->listening &&
        ISC_LIST_EMPTY(listener->connections))
        free_listener(listener);
}

static void
maybe_free_connection(controlconnection_t *conn) {
    controllistener_t *listener = conn->listener;

    if (conn->timer != NULL)
        isc_timer_detach(&conn->timer);

    if (conn->ccmsg_valid) {
        isccc_ccmsg_cancelread(&conn->ccmsg);
        return;
    }

    if (conn->sending) {
        isc_socket_cancel(conn->sock, listener->task,
                  ISC_SOCKCANCEL_SEND);
        return;
    }

    ISC_LIST_UNLINK(listener->connections, conn, link);
    isc_mem_put(listener->mctx, conn, sizeof(*conn));
}

static void
shutdown_listener(controllistener_t *listener) {
    controlconnection_t *conn;
    controlconnection_t *next;

    if (!listener->exiting) {
        char socktext[ISC_SOCKADDR_FORMATSIZE];

        ISC_LIST_UNLINK(listener->controls->listeners, listener, link);

        isc_sockaddr_format(&listener->address, socktext,
                    sizeof(socktext));
        isc_log_write(ns_g_lctx, NS_LOGCATEGORY_GENERAL,
                  NS_LOGMODULE_CONTROL, ISC_LOG_NOTICE,
                  "stopping command channel on %s", socktext);
        if (listener->type == isc_sockettype_unix)
            isc_socket_cleanunix(&listener->address, ISC_TRUE);
        listener->exiting = ISC_TRUE;
    }

    for (conn = ISC_LIST_HEAD(listener->connections);
         conn != NULL;
         conn = next)
    {
        next = ISC_LIST_NEXT(conn, link);
        maybe_free_connection(conn);
    }

    if (listener->listening)
        isc_socket_cancel(listener->sock, listener->task,
                  ISC_SOCKCANCEL_ACCEPT);

    maybe_free_listener(listener);
}

static isc_boolean_t
address_ok(isc_sockaddr_t *sockaddr, dns_acl_t *acl) {
    isc_netaddr_t netaddr;
    isc_result_t result;
    int match;

    isc_netaddr_fromsockaddr(&netaddr, sockaddr);

    result = dns_acl_match(&netaddr, NULL, acl,
                   &ns_g_server->aclenv, &match, NULL);

    if (result != ISC_R_SUCCESS || match <= 0)
        return (ISC_FALSE);
    else
        return (ISC_TRUE);
}

static isc_result_t
control_accept(controllistener_t *listener) {
    isc_result_t result;
    result = isc_socket_accept(listener->sock,
                   listener->task,
                   control_newconn, listener);
    if (result != ISC_R_SUCCESS)
        UNEXPECTED_ERROR(__FILE__, __LINE__,
                 "isc_socket_accept() failed: %s",
                 isc_result_totext(result));
    else
        listener->listening = ISC_TRUE;
    return (result);
}

static isc_result_t
control_listen(controllistener_t *listener) {
    isc_result_t result;

    result = isc_socket_listen(listener->sock, 0);
    if (result != ISC_R_SUCCESS)
        UNEXPECTED_ERROR(__FILE__, __LINE__,
                 "isc_socket_listen() failed: %s",
                 isc_result_totext(result));
    return (result);
}

static void
control_next(controllistener_t *listener) {
    (void)control_accept(listener);
}

static void
control_senddone(isc_task_t *task, isc_event_t *event) {
    isc_socketevent_t *sevent = (isc_socketevent_t *) event;
    controlconnection_t *conn = event->ev_arg;
    controllistener_t *listener = conn->listener;
    isc_socket_t *sock = (isc_socket_t *)sevent->ev_sender;
    isc_result_t result;

    REQUIRE(conn->sending);

    UNUSED(task);

    conn->sending = ISC_FALSE;

    if (sevent->result != ISC_R_SUCCESS &&
        sevent->result != ISC_R_CANCELED)
    {
        char socktext[ISC_SOCKADDR_FORMATSIZE];
        isc_sockaddr_t peeraddr;

        (void)isc_socket_getpeername(sock, &peeraddr);
        isc_sockaddr_format(&peeraddr, socktext, sizeof(socktext));
        isc_log_write(ns_g_lctx, NS_LOGCATEGORY_GENERAL,
                  NS_LOGMODULE_CONTROL, ISC_LOG_WARNING,
                  "error sending command response to %s: %s",
                  socktext, isc_result_totext(sevent->result));
    }
    isc_event_free(&event);

    result = isccc_ccmsg_readmessage(&conn->ccmsg, listener->task,
                     control_recvmessage, conn);
    if (result != ISC_R_SUCCESS) {
        isc_socket_detach(&conn->sock);
        maybe_free_connection(conn);
        maybe_free_listener(listener);
    }
}

static inline void
log_invalid(isccc_ccmsg_t *ccmsg, isc_result_t result) {
    char socktext[ISC_SOCKADDR_FORMATSIZE];
    isc_sockaddr_t peeraddr;

    (void)isc_socket_getpeername(ccmsg->sock, &peeraddr);
    isc_sockaddr_format(&peeraddr, socktext, sizeof(socktext));
    isc_log_write(ns_g_lctx, NS_LOGCATEGORY_GENERAL,
              NS_LOGMODULE_CONTROL, ISC_LOG_ERROR,
              "invalid command from %s: %s",
              socktext, isc_result_totext(result));
}

static void
control_recvmessage(isc_task_t *task, isc_event_t *event) {
    controlconnection_t *conn;
    controllistener_t *listener;
    controlkey_t *key;
    isccc_sexpr_t *request = NULL;
    isccc_sexpr_t *response = NULL;
    isccc_region_t ccregion;
    isccc_region_t secret;
    isc_stdtime_t now;
    isc_buffer_t b;
    isc_region_t r;
    isc_uint32_t len;
    isc_buffer_t text;
    char textarray[1024];
    isc_result_t result;
    isc_result_t eresult;
    isccc_sexpr_t *_ctrl;
    isccc_time_t sent;
    isccc_time_t exp;
    isc_uint32_t nonce;

    REQUIRE(event->ev_type == ISCCC_EVENT_CCMSG);

    conn = event->ev_arg;
    listener = conn->listener;
    secret.rstart = NULL;

        /* Is the server shutting down? */
        if (listener->controls->shuttingdown)
                goto cleanup;

    if (conn->ccmsg.result != ISC_R_SUCCESS) {
        if (conn->ccmsg.result != ISC_R_CANCELED &&
            conn->ccmsg.result != ISC_R_EOF)
            log_invalid(&conn->ccmsg, conn->ccmsg.result);
        goto cleanup;
    }

    request = NULL;

    for (key = ISC_LIST_HEAD(listener->keys);
         key != NULL;
         key = ISC_LIST_NEXT(key, link))
    {
        ccregion.rstart = isc_buffer_base(&conn->ccmsg.buffer);
        ccregion.rend = isc_buffer_used(&conn->ccmsg.buffer);
        if (secret.rstart != NULL)
            isc_mem_put(listener->mctx, secret.rstart,
                    REGION_SIZE(secret));
        secret.rstart = isc_mem_get(listener->mctx, key->secret.length);
        if (secret.rstart == NULL)
            goto cleanup;
        memcpy(secret.rstart, key->secret.base, key->secret.length);
        secret.rend = secret.rstart + key->secret.length;
        result = isccc_cc_fromwire(&ccregion, &request, &secret);
        if (result == ISC_R_SUCCESS)
            break;
        else if (result == ISCCC_R_BADAUTH) {
            /*
             * For some reason, request is non-NULL when
             * isccc_cc_fromwire returns ISCCC_R_BADAUTH.
             */
            if (request != NULL)
                isccc_sexpr_free(&request);
        } else {
            log_invalid(&conn->ccmsg, result);
            goto cleanup;
        }
    }

    if (key == NULL) {
        log_invalid(&conn->ccmsg, ISCCC_R_BADAUTH);
        goto cleanup;
    }

    /* We shouldn't be getting a reply. */
    if (isccc_cc_isreply(request)) {
        log_invalid(&conn->ccmsg, ISC_R_FAILURE);
        goto cleanup;
    }

    isc_stdtime_get(&now);

    /*
     * Limit exposure to replay attacks.
     */
    _ctrl = isccc_alist_lookup(request, "_ctrl");
    if (_ctrl == NULL) {
        log_invalid(&conn->ccmsg, ISC_R_FAILURE);
        goto cleanup;
    }

    if (isccc_cc_lookupuint32(_ctrl, "_tim", &sent) == ISC_R_SUCCESS) {
        if ((sent + CLOCKSKEW) < now || (sent - CLOCKSKEW) > now) {
            log_invalid(&conn->ccmsg, ISCCC_R_CLOCKSKEW);
            goto cleanup;
        }
    } else {
        log_invalid(&conn->ccmsg, ISC_R_FAILURE);
        goto cleanup;
    }

    /*
     * Expire messages that are too old.
     */
    if (isccc_cc_lookupuint32(_ctrl, "_exp", &exp) == ISC_R_SUCCESS &&
        now > exp) {
        log_invalid(&conn->ccmsg, ISCCC_R_EXPIRED);
        goto cleanup;
    }

    /*
     * Duplicate suppression (required for UDP).
     */
    isccc_cc_cleansymtab(listener->controls->symtab, now);
    result = isccc_cc_checkdup(listener->controls->symtab, request, now);
    if (result != ISC_R_SUCCESS) {
        if (result == ISC_R_EXISTS)
                        result = ISCCC_R_DUPLICATE;
        log_invalid(&conn->ccmsg, result);
        goto cleanup;
    }

    if (conn->nonce != 0 &&
        (isccc_cc_lookupuint32(_ctrl, "_nonce", &nonce) != ISC_R_SUCCESS ||
         conn->nonce != nonce)) {
        log_invalid(&conn->ccmsg, ISCCC_R_BADAUTH);
        goto cleanup;
    }

    /*
     * Establish nonce.
     */
    while (conn->nonce == 0)
        isc_random_get(&conn->nonce);

    isc_buffer_init(&text, textarray, sizeof(textarray));
    eresult = ns_control_docommand(request, &text);

    result = isccc_cc_createresponse(request, now, now + 60, &response);
    if (result != ISC_R_SUCCESS)
        goto cleanup;
    if (eresult != ISC_R_SUCCESS) {
        isccc_sexpr_t *data;

        data = isccc_alist_lookup(response, "_data");
        if (data != NULL) {
            const char *estr = isc_result_totext(eresult);
            if (isccc_cc_definestring(data, "err", estr) == NULL)
                goto cleanup;
        }
    }

    if (isc_buffer_usedlength(&text) > 0) {
        isccc_sexpr_t *data;

        data = isccc_alist_lookup(response, "_data");
        if (data != NULL) {
            char *str = (char *)isc_buffer_base(&text);
            if (isccc_cc_definestring(data, "text", str) == NULL)
                goto cleanup;
        }
    }

    _ctrl = isccc_alist_lookup(response, "_ctrl");
    if (_ctrl == NULL ||
        isccc_cc_defineuint32(_ctrl, "_nonce", conn->nonce) == NULL)
        goto cleanup;

    ccregion.rstart = conn->buffer + 4;
    ccregion.rend = conn->buffer + sizeof(conn->buffer);
    result = isccc_cc_towire(response, &ccregion, &secret);
    if (result != ISC_R_SUCCESS)
        goto cleanup;
    isc_buffer_init(&b, conn->buffer, 4);
    len = sizeof(conn->buffer) - REGION_SIZE(ccregion);
    isc_buffer_putuint32(&b, len - 4);
    r.base = conn->buffer;
    r.length = len;

    result = isc_socket_send(conn->sock, &r, task, control_senddone, conn);
    if (result != ISC_R_SUCCESS)
        goto cleanup;
    conn->sending = ISC_TRUE;

    if (secret.rstart != NULL)
        isc_mem_put(listener->mctx, secret.rstart,
                REGION_SIZE(secret));
    if (request != NULL)
        isccc_sexpr_free(&request);
    if (response != NULL)
        isccc_sexpr_free(&response);
    return;

 cleanup:
    if (secret.rstart != NULL)
        isc_mem_put(listener->mctx, secret.rstart,
                REGION_SIZE(secret));
    isc_socket_detach(&conn->sock);
    isccc_ccmsg_invalidate(&conn->ccmsg);
    conn->ccmsg_valid = ISC_FALSE;
    maybe_free_connection(conn);
    maybe_free_listener(listener);
    if (request != NULL)
        isccc_sexpr_free(&request);
    if (response != NULL)
        isccc_sexpr_free(&response);
}

static void
control_timeout(isc_task_t *task, isc_event_t *event) {
    controlconnection_t *conn = event->ev_arg;

    UNUSED(task);

    isc_timer_detach(&conn->timer);
    maybe_free_connection(conn);

    isc_event_free(&event);
}

static isc_result_t
newconnection(controllistener_t *listener, isc_socket_t *sock) {
    controlconnection_t *conn;
    isc_interval_t interval;
    isc_result_t result;

    conn = isc_mem_get(listener->mctx, sizeof(*conn));
    if (conn == NULL)
        return (ISC_R_NOMEMORY);

    conn->sock = sock;
    isccc_ccmsg_init(listener->mctx, sock, &conn->ccmsg);
    conn->ccmsg_valid = ISC_TRUE;
    conn->sending = ISC_FALSE;
    conn->timer = NULL;
    isc_interval_set(&interval, 60, 0);
    result = isc_timer_create(ns_g_timermgr, isc_timertype_once,
                  NULL, &interval, listener->task,
                  control_timeout, conn, &conn->timer);
    if (result != ISC_R_SUCCESS)
        goto cleanup;

    conn->listener = listener;
    conn->nonce = 0;
    ISC_LINK_INIT(conn, link);

    result = isccc_ccmsg_readmessage(&conn->ccmsg, listener->task,
                     control_recvmessage, conn);
    if (result != ISC_R_SUCCESS)
        goto cleanup;
    isccc_ccmsg_setmaxsize(&conn->ccmsg, 2048);

    ISC_LIST_APPEND(listener->connections, conn, link);
    return (ISC_R_SUCCESS);

 cleanup:
    isccc_ccmsg_invalidate(&conn->ccmsg);
    if (conn->timer != NULL)
        isc_timer_detach(&conn->timer);
    isc_mem_put(listener->mctx, conn, sizeof(*conn));
    return (result);
}

static void
control_newconn(isc_task_t *task, isc_event_t *event) {
    isc_socket_newconnev_t *nevent = (isc_socket_newconnev_t *)event;
    controllistener_t *listener = event->ev_arg;
    isc_socket_t *sock;
    isc_sockaddr_t peeraddr;
    isc_result_t result;

    UNUSED(task);

    listener->listening = ISC_FALSE;

    if (nevent->result != ISC_R_SUCCESS) {
        if (nevent->result == ISC_R_CANCELED) {
            shutdown_listener(listener);
            goto cleanup;
        }
        goto restart;
    }

    sock = nevent->newsocket;
    isc_socket_setname(sock, "control", NULL);
    (void)isc_socket_getpeername(sock, &peeraddr);
    if (listener->type == isc_sockettype_tcp &&
        !address_ok(&peeraddr, listener->acl)) {
        char socktext[ISC_SOCKADDR_FORMATSIZE];
        isc_sockaddr_format(&peeraddr, socktext, sizeof(socktext));
        isc_log_write(ns_g_lctx, NS_LOGCATEGORY_GENERAL,
                  NS_LOGMODULE_CONTROL, ISC_LOG_WARNING,
                  "rejected command channel message from %s",
                  socktext);
        isc_socket_detach(&sock);
        goto restart;
    }

    result = newconnection(listener, sock);
    if (result != ISC_R_SUCCESS) {
        char socktext[ISC_SOCKADDR_FORMATSIZE];
        isc_sockaddr_format(&peeraddr, socktext, sizeof(socktext));
        isc_log_write(ns_g_lctx, NS_LOGCATEGORY_GENERAL,
                  NS_LOGMODULE_CONTROL, ISC_LOG_WARNING,
                  "dropped command channel from %s: %s",
                  socktext, isc_result_totext(result));
        isc_socket_detach(&sock);
        goto restart;
    }

 restart:
    control_next(listener);
 cleanup:
    isc_event_free(&event);
}

static void
controls_shutdown(ns_controls_t *controls) {
    controllistener_t *listener;
    controllistener_t *next;

    for (listener = ISC_LIST_HEAD(controls->listeners);
         listener != NULL;
         listener = next)
    {
        /*
         * This is asynchronous.  As listeners shut down, they will
         * call their callbacks.
         */
        next = ISC_LIST_NEXT(listener, link);
        shutdown_listener(listener);
    }
}

void
ns_controls_shutdown(ns_controls_t *controls) {
    controls_shutdown(controls);
    controls->shuttingdown = ISC_TRUE;
}

static isc_result_t
cfgkeylist_find(const cfg_obj_t *keylist, const char *keyname,
            const cfg_obj_t **objp)
{
    const cfg_listelt_t *element;
    const char *str;
    const cfg_obj_t *obj;

    for (element = cfg_list_first(keylist);
         element != NULL;
         element = cfg_list_next(element))
    {
        obj = cfg_listelt_value(element);
        str = cfg_obj_asstring(cfg_map_getname(obj));
        if (strcasecmp(str, keyname) == 0)
            break;
    }
    if (element == NULL)
        return (ISC_R_NOTFOUND);
    obj = cfg_listelt_value(element);
    *objp = obj;
    return (ISC_R_SUCCESS);
}

static isc_result_t
controlkeylist_fromcfg(const cfg_obj_t *keylist, isc_mem_t *mctx,
               controlkeylist_t *keyids)
{
    const cfg_listelt_t *element;
    char *newstr = NULL;
    const char *str;
    const cfg_obj_t *obj;
    controlkey_t *key;

    for (element = cfg_list_first(keylist);
         element != NULL;
         element = cfg_list_next(element))
    {
        obj = cfg_listelt_value(element);
        str = cfg_obj_asstring(obj);
        newstr = isc_mem_strdup(mctx, str);
        if (newstr == NULL)
            goto cleanup;
        key = isc_mem_get(mctx, sizeof(*key));
        if (key == NULL)
            goto cleanup;
        key->keyname = newstr;
        key->secret.base = NULL;
        key->secret.length = 0;
        ISC_LINK_INIT(key, link);
        ISC_LIST_APPEND(*keyids, key, link);
        newstr = NULL;
    }
    return (ISC_R_SUCCESS);

 cleanup:
    if (newstr != NULL)
        isc_mem_free(mctx, newstr);
    free_controlkeylist(keyids, mctx);
    return (ISC_R_NOMEMORY);
}

static void
register_keys(const cfg_obj_t *control, const cfg_obj_t *keylist,
          controlkeylist_t *keyids, isc_mem_t *mctx, const char *socktext)
{
    controlkey_t *keyid, *next;
    const cfg_obj_t *keydef;
    char secret[1024];
    isc_buffer_t b;
    isc_result_t result;

    /*
     * Find the keys corresponding to the keyids used by this listener.
     */
    for (keyid = ISC_LIST_HEAD(*keyids); keyid != NULL; keyid = next) {
        next = ISC_LIST_NEXT(keyid, link);

        result = cfgkeylist_find(keylist, keyid->keyname, &keydef);
        if (result != ISC_R_SUCCESS) {
            cfg_obj_log(control, ns_g_lctx, ISC_LOG_WARNING,
                    "couldn't find key '%s' for use with "
                    "command channel %s",
                    keyid->keyname, socktext);
            ISC_LIST_UNLINK(*keyids, keyid, link);
            free_controlkey(keyid, mctx);
        } else {
            const cfg_obj_t *algobj = NULL;
            const cfg_obj_t *secretobj = NULL;
            const char *algstr = NULL;
            const char *secretstr = NULL;

            (void)cfg_map_get(keydef, "algorithm", &algobj);
            (void)cfg_map_get(keydef, "secret", &secretobj);
            INSIST(algobj != NULL && secretobj != NULL);

            algstr = cfg_obj_asstring(algobj);
            secretstr = cfg_obj_asstring(secretobj);

            if (ns_config_getkeyalgorithm(algstr, NULL, NULL) !=
                ISC_R_SUCCESS)
            {
                cfg_obj_log(control, ns_g_lctx,
                        ISC_LOG_WARNING,
                        "unsupported algorithm '%s' in "
                        "key '%s' for use with command "
                        "channel %s",
                        algstr, keyid->keyname, socktext);
                ISC_LIST_UNLINK(*keyids, keyid, link);
                free_controlkey(keyid, mctx);
                continue;
            }

            isc_buffer_init(&b, secret, sizeof(secret));
            result = isc_base64_decodestring(secretstr, &b);

            if (result != ISC_R_SUCCESS) {
                cfg_obj_log(keydef, ns_g_lctx, ISC_LOG_WARNING,
                        "secret for key '%s' on "
                        "command channel %s: %s",
                        keyid->keyname, socktext,
                        isc_result_totext(result));
                ISC_LIST_UNLINK(*keyids, keyid, link);
                free_controlkey(keyid, mctx);
                continue;
            }

            keyid->secret.length = isc_buffer_usedlength(&b);
            keyid->secret.base = isc_mem_get(mctx,
                             keyid->secret.length);
            if (keyid->secret.base == NULL) {
                cfg_obj_log(keydef, ns_g_lctx, ISC_LOG_WARNING,
                       "couldn't register key '%s': "
                       "out of memory", keyid->keyname);
                ISC_LIST_UNLINK(*keyids, keyid, link);
                free_controlkey(keyid, mctx);
                break;
            }
            memcpy(keyid->secret.base, isc_buffer_base(&b),
                   keyid->secret.length);
        }
    }
}

#define CHECK(x) \
    do { \
         result = (x); \
         if (result != ISC_R_SUCCESS) \
            goto cleanup; \
    } while (0)

static isc_result_t
get_rndckey(isc_mem_t *mctx, controlkeylist_t *keyids) {
    isc_result_t result;
    cfg_parser_t *pctx = NULL;
    cfg_obj_t *config = NULL;
    const cfg_obj_t *key = NULL;
    const cfg_obj_t *algobj = NULL;
    const cfg_obj_t *secretobj = NULL;
    const char *algstr = NULL;
    const char *secretstr = NULL;
    controlkey_t *keyid = NULL;
    char secret[1024];
    isc_buffer_t b;

    CHECK(cfg_parser_create(mctx, ns_g_lctx, &pctx));
    CHECK(cfg_parse_file(pctx, ns_g_keyfile, &cfg_type_rndckey, &config));
    CHECK(cfg_map_get(config, "key", &key));

    keyid = isc_mem_get(mctx, sizeof(*keyid));
    if (keyid == NULL)
        CHECK(ISC_R_NOMEMORY);
    keyid->keyname = isc_mem_strdup(mctx,
                    cfg_obj_asstring(cfg_map_getname(key)));
    keyid->secret.base = NULL;
    keyid->secret.length = 0;
    ISC_LINK_INIT(keyid, link);
    if (keyid->keyname == NULL)
        CHECK(ISC_R_NOMEMORY);

    CHECK(bind9_check_key(key, ns_g_lctx));

    (void)cfg_map_get(key, "algorithm", &algobj);
    (void)cfg_map_get(key, "secret", &secretobj);
    INSIST(algobj != NULL && secretobj != NULL);

    algstr = cfg_obj_asstring(algobj);
    secretstr = cfg_obj_asstring(secretobj);

    if (ns_config_getkeyalgorithm(algstr, NULL, NULL) != ISC_R_SUCCESS) {
        cfg_obj_log(key, ns_g_lctx,
                ISC_LOG_WARNING,
                "unsupported algorithm '%s' in "
                "key '%s' for use with command "
                "channel",
                algstr, keyid->keyname);
        goto cleanup;
    }

    isc_buffer_init(&b, secret, sizeof(secret));
    result = isc_base64_decodestring(secretstr, &b);

    if (result != ISC_R_SUCCESS) {
        cfg_obj_log(key, ns_g_lctx, ISC_LOG_WARNING,
                "secret for key '%s' on command channel: %s",
                keyid->keyname, isc_result_totext(result));
        CHECK(result);
    }

    keyid->secret.length = isc_buffer_usedlength(&b);
    keyid->secret.base = isc_mem_get(mctx,
                     keyid->secret.length);
    if (keyid->secret.base == NULL) {
        cfg_obj_log(key, ns_g_lctx, ISC_LOG_WARNING,
               "couldn't register key '%s': "
               "out of memory", keyid->keyname);
        CHECK(ISC_R_NOMEMORY);
    }
    memcpy(keyid->secret.base, isc_buffer_base(&b),
           keyid->secret.length);
    ISC_LIST_APPEND(*keyids, keyid, link);
    keyid = NULL;
    result = ISC_R_SUCCESS;

  cleanup:
    if (keyid != NULL)
        free_controlkey(keyid, mctx);
    if (config != NULL)
        cfg_obj_destroy(pctx, &config);
    if (pctx != NULL)
        cfg_parser_destroy(&pctx);
    return (result);
}

/*
 * Ensures that both '*global_keylistp' and '*control_keylistp' are
 * valid or both are NULL.
 */
static void
get_key_info(const cfg_obj_t *config, const cfg_obj_t *control,
         const cfg_obj_t **global_keylistp,
         const cfg_obj_t **control_keylistp)
{
    isc_result_t result;
    const cfg_obj_t *control_keylist = NULL;
    const cfg_obj_t *global_keylist = NULL;

    REQUIRE(global_keylistp != NULL && *global_keylistp == NULL);
    REQUIRE(control_keylistp != NULL && *control_keylistp == NULL);

    control_keylist = cfg_tuple_get(control, "keys");

    if (!cfg_obj_isvoid(control_keylist) &&
        cfg_list_first(control_keylist) != NULL) {
        result = cfg_map_get(config, "key", &global_keylist);

        if (result == ISC_R_SUCCESS) {
            *global_keylistp = global_keylist;
            *control_keylistp = control_keylist;
        }
    }
}

static void
update_listener(ns_controls_t *cp, controllistener_t **listenerp,
        const cfg_obj_t *control, const cfg_obj_t *config,
        isc_sockaddr_t *addr, cfg_aclconfctx_t *aclconfctx,
            const char *socktext, isc_sockettype_t type)
{
    controllistener_t *listener;
    const cfg_obj_t *allow;
    const cfg_obj_t *global_keylist = NULL;
    const cfg_obj_t *control_keylist = NULL;
    dns_acl_t *new_acl = NULL;
    controlkeylist_t keys;
    isc_result_t result = ISC_R_SUCCESS;

    for (listener = ISC_LIST_HEAD(cp->listeners);
         listener != NULL;
         listener = ISC_LIST_NEXT(listener, link))
        if (isc_sockaddr_equal(addr, &listener->address))
            break;

    if (listener == NULL) {
        *listenerp = NULL;
        return;
    }

    /*
     * There is already a listener for this sockaddr.
     * Update the access list and key information.
     *
     * First try to deal with the key situation.  There are a few
     * possibilities:
     *  (a) It had an explicit keylist and still has an explicit keylist.
     *  (b) It had an automagic key and now has an explicit keylist.
     *  (c) It had an explicit keylist and now needs an automagic key.
     *  (d) It has an automagic key and still needs the automagic key.
     *
     * (c) and (d) are the annoying ones.  The caller needs to know
     * that it should use the automagic configuration for key information
     * in place of the named.conf configuration.
     *
     * XXXDCL There is one other hazard that has not been dealt with,
     * the problem that if a key change is being caused by a control
     * channel reload, then the response will be with the new key
     * and not able to be decrypted by the client.
     */
    if (control != NULL)
        get_key_info(config, control, &global_keylist,
                 &control_keylist);

    if (control_keylist != NULL) {
        INSIST(global_keylist != NULL);

        ISC_LIST_INIT(keys);
        result = controlkeylist_fromcfg(control_keylist,
                        listener->mctx, &keys);
        if (result == ISC_R_SUCCESS) {
            free_controlkeylist(&listener->keys, listener->mctx);
            listener->keys = keys;
            register_keys(control, global_keylist, &listener->keys,
                      listener->mctx, socktext);
        }
    } else {
        free_controlkeylist(&listener->keys, listener->mctx);
        result = get_rndckey(listener->mctx, &listener->keys);
    }

    if (result != ISC_R_SUCCESS && global_keylist != NULL) {
        /*
         * This message might be a little misleading since the
         * "new keys" might in fact be identical to the old ones,
         * but tracking whether they are identical just for the
         * sake of avoiding this message would be too much trouble.
         */
        if (control != NULL)
            cfg_obj_log(control, ns_g_lctx, ISC_LOG_WARNING,
                    "couldn't install new keys for "
                    "command channel %s: %s",
                    socktext, isc_result_totext(result));
        else
            isc_log_write(ns_g_lctx, NS_LOGCATEGORY_GENERAL,
                      NS_LOGMODULE_CONTROL, ISC_LOG_WARNING,
                      "couldn't install new keys for "
                      "command channel %s: %s",
                      socktext, isc_result_totext(result));
    }

    /*
     * Now, keep the old access list unless a new one can be made.
     */
    if (control != NULL && type == isc_sockettype_tcp) {
        allow = cfg_tuple_get(control, "allow");
        result = cfg_acl_fromconfig(allow, config, ns_g_lctx,
                        aclconfctx, listener->mctx,
                        &new_acl);
    } else {
        result = dns_acl_any(listener->mctx, &new_acl);
    }

    if (result == ISC_R_SUCCESS) {
        dns_acl_detach(&listener->acl);
        dns_acl_attach(new_acl, &listener->acl);
        dns_acl_detach(&new_acl);
        /* XXXDCL say the old acl is still used? */
    } else if (control != NULL)
        cfg_obj_log(control, ns_g_lctx, ISC_LOG_WARNING,
                "couldn't install new acl for "
                "command channel %s: %s",
                socktext, isc_result_totext(result));
    else
        isc_log_write(ns_g_lctx, NS_LOGCATEGORY_GENERAL,
                  NS_LOGMODULE_CONTROL, ISC_LOG_WARNING,
                  "couldn't install new acl for "
                  "command channel %s: %s",
                  socktext, isc_result_totext(result));

    if (result == ISC_R_SUCCESS && type == isc_sockettype_unix) {
        isc_uint32_t perm, owner, group;
        perm  = cfg_obj_asuint32(cfg_tuple_get(control, "perm"));
        owner = cfg_obj_asuint32(cfg_tuple_get(control, "owner"));
        group = cfg_obj_asuint32(cfg_tuple_get(control, "group"));
        result = ISC_R_SUCCESS;
        if (listener->perm != perm || listener->owner != owner ||
            listener->group != group)
            result = isc_socket_permunix(&listener->address, perm,
                             owner, group);
        if (result == ISC_R_SUCCESS) {
            listener->perm = perm;
            listener->owner = owner;
            listener->group = group;
        } else if (control != NULL)
            cfg_obj_log(control, ns_g_lctx, ISC_LOG_WARNING,
                    "couldn't update ownership/permission for "
                    "command channel %s", socktext);
    }

    *listenerp = listener;
}

static void
add_listener(ns_controls_t *cp, controllistener_t **listenerp,
         const cfg_obj_t *control, const cfg_obj_t *config,
         isc_sockaddr_t *addr, cfg_aclconfctx_t *aclconfctx,
         const char *socktext, isc_sockettype_t type)
{
    isc_mem_t *mctx = cp->server->mctx;
    controllistener_t *listener;
    const cfg_obj_t *allow;
    const cfg_obj_t *global_keylist = NULL;
    const cfg_obj_t *control_keylist = NULL;
    dns_acl_t *new_acl = NULL;
    isc_result_t result = ISC_R_SUCCESS;

    listener = isc_mem_get(mctx, sizeof(*listener));
    if (listener == NULL)
        result = ISC_R_NOMEMORY;

    if (result == ISC_R_SUCCESS) {
        listener->controls = cp;
        listener->mctx = mctx;
        listener->task = cp->server->task;
        listener->address = *addr;
        listener->sock = NULL;
        listener->listening = ISC_FALSE;
        listener->exiting = ISC_FALSE;
        listener->acl = NULL;
        listener->type = type;
        listener->perm = 0;
        listener->owner = 0;
        listener->group = 0;
        ISC_LINK_INIT(listener, link);
        ISC_LIST_INIT(listener->keys);
        ISC_LIST_INIT(listener->connections);

        /*
         * Make the acl.
         */
        if (control != NULL && type == isc_sockettype_tcp) {
            allow = cfg_tuple_get(control, "allow");
            result = cfg_acl_fromconfig(allow, config, ns_g_lctx,
                            aclconfctx, mctx, &new_acl);
        } else {
            result = dns_acl_any(mctx, &new_acl);
        }
    }

    if (result == ISC_R_SUCCESS) {
        dns_acl_attach(new_acl, &listener->acl);
        dns_acl_detach(&new_acl);

        if (config != NULL)
            get_key_info(config, control, &global_keylist,
                     &control_keylist);

        if (control_keylist != NULL) {
            result = controlkeylist_fromcfg(control_keylist,
                            listener->mctx,
                            &listener->keys);
            if (result == ISC_R_SUCCESS)
                register_keys(control, global_keylist,
                          &listener->keys,
                          listener->mctx, socktext);
        } else
            result = get_rndckey(mctx, &listener->keys);

        if (result != ISC_R_SUCCESS && control != NULL)
            cfg_obj_log(control, ns_g_lctx, ISC_LOG_WARNING,
                    "couldn't install keys for "
                    "command channel %s: %s",
                    socktext, isc_result_totext(result));
    }

    if (result == ISC_R_SUCCESS) {
        int pf = isc_sockaddr_pf(&listener->address);
        if ((pf == AF_INET && isc_net_probeipv4() != ISC_R_SUCCESS) ||
#ifdef ISC_PLATFORM_HAVESYSUNH
            (pf == AF_UNIX && isc_net_probeunix() != ISC_R_SUCCESS) ||
#endif
            (pf == AF_INET6 && isc_net_probeipv6() != ISC_R_SUCCESS))
            result = ISC_R_FAMILYNOSUPPORT;
    }

    if (result == ISC_R_SUCCESS && type == isc_sockettype_unix)
        isc_socket_cleanunix(&listener->address, ISC_FALSE);

    if (result == ISC_R_SUCCESS)
        result = isc_socket_create(ns_g_socketmgr,
                       isc_sockaddr_pf(&listener->address),
                       type, &listener->sock);
    if (result == ISC_R_SUCCESS)
        isc_socket_setname(listener->sock, "control", NULL);

    if (result == ISC_R_SUCCESS)
        result = isc_socket_bind(listener->sock,
                     &listener->address);

    if (result == ISC_R_SUCCESS && type == isc_sockettype_unix) {
        listener->perm = cfg_obj_asuint32(cfg_tuple_get(control,
                                "perm"));
        listener->owner = cfg_obj_asuint32(cfg_tuple_get(control,
                                 "owner"));
        listener->group = cfg_obj_asuint32(cfg_tuple_get(control,
                                 "group"));
        result = isc_socket_permunix(&listener->address, listener->perm,
                         listener->owner, listener->group);
    }
    if (result == ISC_R_SUCCESS)
        result = control_listen(listener);

    if (result == ISC_R_SUCCESS)
        result = control_accept(listener);

    if (result == ISC_R_SUCCESS) {
        isc_log_write(ns_g_lctx, NS_LOGCATEGORY_GENERAL,
                  NS_LOGMODULE_CONTROL, ISC_LOG_NOTICE,
                  "command channel listening on %s", socktext);
        *listenerp = listener;

    } else {
        if (listener != NULL) {
            listener->exiting = ISC_TRUE;
            free_listener(listener);
        }

        if (control != NULL)
            cfg_obj_log(control, ns_g_lctx, ISC_LOG_WARNING,
                    "couldn't add command channel %s: %s",
                    socktext, isc_result_totext(result));
        else
            isc_log_write(ns_g_lctx, NS_LOGCATEGORY_GENERAL,
                      NS_LOGMODULE_CONTROL, ISC_LOG_NOTICE,
                      "couldn't add command channel %s: %s",
                      socktext, isc_result_totext(result));

        *listenerp = NULL;
    }

    /* XXXDCL return error results? fail hard? */
}

isc_result_t
ns_controls_configure(ns_controls_t *cp, const cfg_obj_t *config,
              cfg_aclconfctx_t *aclconfctx)
{
    controllistener_t *listener;
    controllistenerlist_t new_listeners;
    const cfg_obj_t *controlslist = NULL;
    const cfg_listelt_t *element, *element2;
    char socktext[ISC_SOCKADDR_FORMATSIZE];

    ISC_LIST_INIT(new_listeners);

    /*
     * Get the list of named.conf 'controls' statements.
     */
    (void)cfg_map_get(config, "controls", &controlslist);

    /*
     * Run through the new control channel list, noting sockets that
     * are already being listened on and moving them to the new list.
     *
     * Identifying duplicate addr/port combinations is left to either
     * the underlying config code, or to the bind attempt getting an
     * address-in-use error.
     */
    if (controlslist != NULL) {
        for (element = cfg_list_first(controlslist);
             element != NULL;
             element = cfg_list_next(element)) {
            const cfg_obj_t *controls;
            const cfg_obj_t *inetcontrols = NULL;

            controls = cfg_listelt_value(element);
            (void)cfg_map_get(controls, "inet", &inetcontrols);
            if (inetcontrols == NULL)
                continue;

            for (element2 = cfg_list_first(inetcontrols);
                 element2 != NULL;
                 element2 = cfg_list_next(element2)) {
                const cfg_obj_t *control;
                const cfg_obj_t *obj;
                isc_sockaddr_t addr;

                /*
                 * The parser handles BIND 8 configuration file
                 * syntax, so it allows unix phrases as well
                 * inet phrases with no keys{} clause.
                 */
                control = cfg_listelt_value(element2);

                obj = cfg_tuple_get(control, "address");
                addr = *cfg_obj_assockaddr(obj);
                if (isc_sockaddr_getport(&addr) == 0)
                    isc_sockaddr_setport(&addr,
                                 NS_CONTROL_PORT);

                isc_sockaddr_format(&addr, socktext,
                            sizeof(socktext));

                isc_log_write(ns_g_lctx,
                          NS_LOGCATEGORY_GENERAL,
                          NS_LOGMODULE_CONTROL,
                          ISC_LOG_DEBUG(9),
                          "processing control channel %s",
                          socktext);

                update_listener(cp, &listener, control, config,
                        &addr, aclconfctx, socktext,
                        isc_sockettype_tcp);

                if (listener != NULL)
                    /*
                     * Remove the listener from the old
                     * list, so it won't be shut down.
                     */
                    ISC_LIST_UNLINK(cp->listeners,
                            listener, link);
                else
                    /*
                     * This is a new listener.
                     */
                    add_listener(cp, &listener, control,
                             config, &addr, aclconfctx,
                             socktext,
                             isc_sockettype_tcp);

                if (listener != NULL)
                    ISC_LIST_APPEND(new_listeners,
                            listener, link);
            }
        }
        for (element = cfg_list_first(controlslist);
             element != NULL;
             element = cfg_list_next(element)) {
            const cfg_obj_t *controls;
            const cfg_obj_t *unixcontrols = NULL;

            controls = cfg_listelt_value(element);
            (void)cfg_map_get(controls, "unix", &unixcontrols);
            if (unixcontrols == NULL)
                continue;

            for (element2 = cfg_list_first(unixcontrols);
                 element2 != NULL;
                 element2 = cfg_list_next(element2)) {
                const cfg_obj_t *control;
                const cfg_obj_t *path;
                isc_sockaddr_t addr;
                isc_result_t result;

                /*
                 * The parser handles BIND 8 configuration file
                 * syntax, so it allows unix phrases as well
                 * inet phrases with no keys{} clause.
                 */
                control = cfg_listelt_value(element2);

                path = cfg_tuple_get(control, "path");
                result = isc_sockaddr_frompath(&addr,
                              cfg_obj_asstring(path));
                if (result != ISC_R_SUCCESS) {
                    isc_log_write(ns_g_lctx,
                          NS_LOGCATEGORY_GENERAL,
                          NS_LOGMODULE_CONTROL,
                          ISC_LOG_DEBUG(9),
                          "control channel '%s': %s",
                          cfg_obj_asstring(path),
                          isc_result_totext(result));
                    continue;
                }

                isc_log_write(ns_g_lctx,
                          NS_LOGCATEGORY_GENERAL,
                          NS_LOGMODULE_CONTROL,
                          ISC_LOG_DEBUG(9),
                          "processing control channel '%s'",
                          cfg_obj_asstring(path));

                update_listener(cp, &listener, control, config,
                        &addr, aclconfctx,
                            cfg_obj_asstring(path),
                        isc_sockettype_unix);

                if (listener != NULL)
                    /*
                     * Remove the listener from the old
                     * list, so it won't be shut down.
                     */
                    ISC_LIST_UNLINK(cp->listeners,
                            listener, link);
                else
                    /*
                     * This is a new listener.
                     */
                    add_listener(cp, &listener, control,
                             config, &addr, aclconfctx,
                             cfg_obj_asstring(path),
                             isc_sockettype_unix);

                if (listener != NULL)
                    ISC_LIST_APPEND(new_listeners,
                            listener, link);
            }
        }
    } else {
        int i;

        for (i = 0; i < 2; i++) {
            isc_sockaddr_t addr;

            if (i == 0) {
                struct in_addr localhost;

                if (isc_net_probeipv4() != ISC_R_SUCCESS)
                    continue;
                localhost.s_addr = htonl(INADDR_LOOPBACK);
                isc_sockaddr_fromin(&addr, &localhost, 0);
            } else {
                if (isc_net_probeipv6() != ISC_R_SUCCESS)
                    continue;
                isc_sockaddr_fromin6(&addr,
                             &in6addr_loopback, 0);
            }
            isc_sockaddr_setport(&addr, NS_CONTROL_PORT);

            isc_sockaddr_format(&addr, socktext, sizeof(socktext));

            update_listener(cp, &listener, NULL, NULL,
                    &addr, NULL, socktext,
                        isc_sockettype_tcp);

            if (listener != NULL)
                /*
                 * Remove the listener from the old
                 * list, so it won't be shut down.
                 */
                ISC_LIST_UNLINK(cp->listeners,
                        listener, link);
            else
                /*
                 * This is a new listener.
                 */
                add_listener(cp, &listener, NULL, NULL,
                         &addr, NULL, socktext,
                         isc_sockettype_tcp);

            if (listener != NULL)
                ISC_LIST_APPEND(new_listeners,
                        listener, link);
        }
    }

    /*
     * ns_control_shutdown() will stop whatever is on the global
     * listeners list, which currently only has whatever sockaddrs
     * were in the previous configuration (if any) that do not
     * remain in the current configuration.
     */
    controls_shutdown(cp);

    /*
     * Put all of the valid listeners on the listeners list.
     * Anything already on listeners in the process of shutting
     * down will be taken care of by listen_done().
     */
    ISC_LIST_APPENDLIST(cp->listeners, new_listeners, link);
    return (ISC_R_SUCCESS);
}

isc_result_t
ns_controls_create(ns_server_t *server, ns_controls_t **ctrlsp) {
    isc_mem_t *mctx = server->mctx;
    isc_result_t result;
    ns_controls_t *controls = isc_mem_get(mctx, sizeof(*controls));

    if (controls == NULL)
        return (ISC_R_NOMEMORY);
    controls->server = server;
    ISC_LIST_INIT(controls->listeners);
    controls->shuttingdown = ISC_FALSE;
    controls->symtab = NULL;
    result = isccc_cc_createsymtab(&controls->symtab);
    if (result != ISC_R_SUCCESS) {
        isc_mem_put(server->mctx, controls, sizeof(*controls));
        return (result);
    }
    *ctrlsp = controls;
    return (ISC_R_SUCCESS);
}

void
ns_controls_destroy(ns_controls_t **ctrlsp) {
    ns_controls_t *controls = *ctrlsp;

    REQUIRE(ISC_LIST_EMPTY(controls->listeners));

    isccc_symtab_destroy(&controls->symtab);
    isc_mem_put(controls->server->mctx, controls, sizeof(*controls));
    *ctrlsp = NULL;
}