bin/named/controlconf.c

	controlconf.c revision ed3418751ebdf7de397df76753dae97851d2bdf9
/*
 * Copyright (C) 2001  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: controlconf.c,v 1.16 2001/07/05 18:39:14 bwelling Exp $ */

#include <config.h>

#include <isc/base64.h>
#include <isc/buffer.h>
#include <isc/event.h>
#include <isc/file.h>
#include <isc/fsaccess.h>
#include <isc/mem.h>
#include <isc/netaddr.h>
#include <isc/print.h>
#include <isc/random.h>
#include <isc/result.h>
#include <isc/stdio.h>
#include <isc/stdtime.h>
#include <isc/string.h>
#include <isc/timer.h>
#include <isc/util.h>

#include <isccfg/cfg.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/util.h>

#include <dns/keyvalues.h>
#include <dns/result.h>

#include <dst/dst.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_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_LINK(controllistener_t) link;
};

static struct {
    char        name[64];
    char        secret[192];
    cfg_parser_t   *parser;
    cfg_obj_t      *config;
    isc_sockaddr_t  address; /* Last channel that needed automagic. */
} automagic_key;

#define NS_AUTOKEY_BITS 128
#define NS_AUTOKEY_NAME "control_autokey"

struct ns_controls {
    ns_server_t         *server;
    controllistenerlist_t       listeners;
};

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

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) {
    isc_boolean_t destroy = ISC_TRUE;

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

        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);
        listener->exiting = ISC_TRUE;
    }

    if (!ISC_LIST_EMPTY(listener->connections)) {
        controlconnection_t *conn;
        for (conn = ISC_LIST_HEAD(listener->connections);
             conn != NULL;
             conn = ISC_LIST_NEXT(conn, link))
            maybe_free_connection(conn);
        destroy = ISC_FALSE;
    }

    if (listener->sock != NULL) {
        isc_socket_cancel(listener->sock, listener->task,
                  ISC_SOCKCANCEL_ACCEPT);
        destroy = ISC_FALSE;
    }

    if (destroy)
        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;

    REQUIRE(event->ev_type == ISCCC_EVENT_CCMSG);

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

    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;
    INSIST(!ISC_LIST_EMPTY(listener->keys));

    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);
        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);
            isc_mem_put(listener->mctx, secret.rstart,
                    REGION_SIZE(secret));
        } 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_buffer_init(&text, textarray, sizeof(textarray));
    eresult = ns_control_docommand(request, &text);

    isc_stdtime_get(&now);
    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;
        }
    }

    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;
    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);

    if (nevent->result != ISC_R_SUCCESS) {
        if (nevent->result == ISC_R_CANCELED) {
            isc_socket_detach(&listener->sock);
            listener->listening = ISC_FALSE;
            shutdown_listener(listener);
            goto cleanup;
        }
        goto restart;
    }

    sock = nevent->newsocket;
    (void)isc_socket_getpeername(sock, &peeraddr);
    if (!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);
        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));
        goto restart;
    }

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

void
ns_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);
        ISC_LIST_UNLINK(controls->listeners, listener, link);
        shutdown_listener(listener);
    }
}

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

    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);
        key = NULL;
        newstr = NULL;
    }
    return (ISC_R_SUCCESS);

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

static void
register_keys(cfg_obj_t *control, cfg_obj_t *keylist,
          controlkeylist_t *keyids, isc_mem_t *mctx, char *socktext)
{
    controlkey_t *keyid, *next;
    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 {
            cfg_obj_t *algobj = NULL;
            cfg_obj_t *secretobj = NULL;
            char *algstr = NULL;
            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 (strcasecmp(algstr, "hmac-md5") != 0) {
                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);
        }
    }
}

static isc_result_t
make_automagic_key(isc_mem_t *mctx) {
    unsigned char key_rawsecret[32];
    unsigned char key_txtsecret[32];
    isc_buffer_t key_rawbuffer;
    isc_buffer_t key_txtbuffer;
    isc_region_t key_rawregion;
    isc_uint32_t key_id;
    isc_result_t result;
    dst_key_t *key = NULL;

    /*
     * First generate a secret.  The fourth parameter non-zero means
     * that pseudorandom data is ok; good entropy is not required.
     */
    result = dst_key_generate(dns_rootname, DST_ALG_HMACMD5,
                  NS_AUTOKEY_BITS, 1, 0, DNS_KEYPROTO_ANY,
                  dns_rdataclass_in, mctx, &key);

    if (result == ISC_R_SUCCESS) {
        isc_buffer_init(&key_rawbuffer, &key_rawsecret,
                sizeof(key_rawsecret));
        result = dst_key_tobuffer(key, &key_rawbuffer);
    }

    if (result == ISC_R_SUCCESS) {
        isc_buffer_init(&key_txtbuffer, &key_txtsecret,
                sizeof(key_txtsecret));
        isc_buffer_usedregion(&key_rawbuffer, &key_rawregion);
        result = isc_base64_totext(&key_rawregion, -1, "",
                       &key_txtbuffer);
    }

    if (result == ISC_R_SUCCESS) {
        unsigned int len = isc_buffer_usedlength(&key_txtbuffer);

        INSIST(len < sizeof(automagic_key.secret));

        memcpy(automagic_key.secret, isc_buffer_base(&key_txtbuffer),
               len);
        automagic_key.secret[len] = '\0';

        /*
         * Make a random name for the key and generate the config
         * file statement for it.
         */
        isc_random_get(&key_id);
        len = snprintf(automagic_key.name, sizeof(automagic_key.name),
                   NS_AUTOKEY_NAME ".%u", key_id);
        INSIST(len < sizeof(automagic_key.name));
    }

    if (key != NULL)
        dst_key_free(&key);

    if (result != ISC_R_SUCCESS)
        isc_log_write(ns_g_lctx, NS_LOGCATEGORY_GENERAL,
                  NS_LOGMODULE_CONTROL, ISC_LOG_WARNING,
                  "could not generate control channel key: %s",
                  isc_result_totext(result));

    return (result);
}

static void
format_automagic_keycfg(isc_buffer_t *conf) {
    unsigned int len;

    len = snprintf(isc_buffer_base(conf), isc_buffer_length(conf),
               "key \"%s\" {\n"
                "\talgorithm hmac-md5;\n"
                "\tsecret \"%s\";\n"
               "};\n",
               automagic_key.name, automagic_key.secret);

    INSIST(len < isc_buffer_length(conf));

    isc_buffer_add(conf, len);
}

static isc_result_t
parse_automagic_key(isc_mem_t *mctx) {
    unsigned int len;
    char cfg_data[512];
    isc_buffer_t cfg_buffer;
    isc_result_t result = ISC_R_SUCCESS;
    cfg_obj_t *cfg = NULL;
    cfg_parser_t *parser = NULL;

    if (automagic_key.name[0] == '\0')
        result = make_automagic_key(mctx);

    if (result == ISC_R_SUCCESS) {
        /*
         * Fake up a configuration with a dummy inet control
         * to grab the keylist tuple.
         */
        isc_buffer_init(&cfg_buffer, cfg_data, sizeof(cfg_data));
        format_automagic_keycfg(&cfg_buffer);
        len = snprintf(isc_buffer_used(&cfg_buffer),
                   isc_buffer_availablelength(&cfg_buffer),
                   "controls { inet 127.0.0.1 allow { localhost; }"
                   "              keys { %s; }; };",
                   automagic_key.name);
        INSIST(len < isc_buffer_availablelength(&cfg_buffer));
        isc_buffer_add(&cfg_buffer, len);

        result = cfg_parser_create(mctx, ns_g_lctx, &parser);
    }

    if (result == ISC_R_SUCCESS)
        result = cfg_parse_buffer(parser, &cfg_buffer,
                      &cfg_type_namedconf, &cfg);

    if (result == ISC_R_SUCCESS) {
        automagic_key.parser = parser;
        automagic_key.config = cfg;
    } else {
        isc_log_write(ns_g_lctx, NS_LOGCATEGORY_GENERAL,
                  NS_LOGMODULE_CONTROL, ISC_LOG_WARNING,
                  "could not parse autogenerated "
                  "control channel key: %s",
                  isc_result_totext(result));

        if (parser != NULL)
            cfg_parser_destroy(&parser);
    }

    return (result);
}

static void
finalize_automagic_key(void) {
    unsigned int fsaccess;
    int i;
    FILE *fp;
    isc_result_t result;

    (void)isc_file_remove(ns_g_autorndckeyfile);

    if (automagic_key.parser != NULL) {
        /*
         * An automagic key was parsed, so some channel needed it.
         * Try to write the rndc.conf file.
         */
        char cfg_data[512];
        char nettext[ISC_NETADDR_FORMATSIZE];
        isc_buffer_t cfg_buffer;
        isc_netaddr_t netaddr;


        result = isc_stdio_open(ns_g_autorndckeyfile, "w", &fp);

        if (result == ISC_R_SUCCESS) {
            fsaccess = 0;
            isc_fsaccess_add(ISC_FSACCESS_OWNER, ISC_FSACCESS_READ,
                     &fsaccess);
            result = isc_fsaccess_set(ns_g_autorndckeyfile,
                          fsaccess);

            if (result != ISC_R_SUCCESS) {
                isc_log_write(ns_g_lctx,
                          NS_LOGCATEGORY_GENERAL,
                          NS_LOGMODULE_CONTROL,
                          ISC_LOG_WARNING,
                          "could not set owner-only "
                          "access on %s: %s: "
                          "server control key might be "
                          "exposed to local users",
                          ns_g_autorndckeyfile,
                          isc_result_totext(result));
            }

            isc_buffer_init(&cfg_buffer, cfg_data,
                    sizeof(cfg_data));
            format_automagic_keycfg(&cfg_buffer);

            isc_netaddr_fromsockaddr(&netaddr,
                         &automagic_key.address);
            isc_netaddr_format(&netaddr, nettext, sizeof(nettext));

            i = fputs(isc_buffer_base(&cfg_buffer), fp);

            if (i != EOF)
                i = fprintf(fp, "options {\n"
                        "\tdefault-server %s;\n"
                        "\tdefault-port %hu;\n"
                        "\tdefault-key \"%s\";\n"
                        "};\n",
                        nettext,
                        isc_sockaddr_getport(
                               &automagic_key.address),
                        automagic_key.name);

            if (i == EOF)
                isc_log_write(ns_g_lctx,
                          NS_LOGCATEGORY_GENERAL,
                          NS_LOGMODULE_CONTROL,
                          ISC_LOG_WARNING,
                          "could not write %s",
                          ns_g_autorndckeyfile);

            result = isc_stdio_close(fp);
            if (result != ISC_R_SUCCESS)
                isc_log_write(ns_g_lctx,
                          NS_LOGCATEGORY_GENERAL,
                          NS_LOGMODULE_CONTROL,
                          ISC_LOG_WARNING,
                          "error closing %s: %s",
                          ns_g_autorndckeyfile,
                          isc_result_totext(result));
        }

        cfg_obj_destroy(automagic_key.parser, &automagic_key.config);
        cfg_parser_destroy(&automagic_key.parser);
    }
}

static void
get_key_info(isc_mem_t *mctx, cfg_obj_t *config, cfg_obj_t *control,
         cfg_obj_t **global_keylistp, cfg_obj_t **control_keylistp,
         isc_boolean_t *explicit_key)
{
    cfg_obj_t *control_keylist = NULL;
    cfg_obj_t *global_keylist = NULL;
    isc_result_t result = ISC_R_SUCCESS;

    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) {
        cfg_obj_t *controls = NULL;
        cfg_obj_t *inet = NULL;

        if (automagic_key.parser == NULL)
            result = parse_automagic_key(mctx);

        if (result == ISC_R_SUCCESS) {
            config = automagic_key.config;

            /*
             * All of these should succeed.
             */
            (void)cfg_map_get(config, "key", &global_keylist);
            INSIST(global_keylist != NULL);

            (void)cfg_map_get(config, "controls", &controls);
            INSIST(controls != NULL);
            (void)cfg_map_get(cfg_listelt_value
                      (cfg_list_first(controls)),
                      "inet", &inet);
            INSIST(inet != NULL);
            control_keylist =
                cfg_tuple_get(cfg_listelt_value
                          (cfg_list_first(inet)), "keys");
            INSIST(control_keylist != NULL);
        }

        *explicit_key = ISC_FALSE;

    } else {
        result = cfg_map_get(config, "key", &global_keylist);
        *explicit_key = config != automagic_key.config
                       ? ISC_TRUE : ISC_FALSE;
    }

    if (result == ISC_R_SUCCESS) {
        *global_keylistp = global_keylist;
        *control_keylistp = control_keylist;
    } else
        cfg_obj_log(control, ns_g_lctx, ISC_LOG_WARNING,
                "no key statements for use by control channel");
}

static void
update_listener(ns_controls_t *cp,
        controllistener_t **listenerp, cfg_obj_t *control,
        cfg_obj_t *config, isc_sockaddr_t *addr,
        ns_aclconfctx_t *aclconfctx, char *socktext)
{
    controllistener_t *listener;
    cfg_obj_t *allow;
    cfg_obj_t *global_keylist = NULL;
    cfg_obj_t *control_keylist = NULL;
    dns_acl_t *new_acl = NULL;
    controlkeylist_t keys;
    isc_boolean_t explicit_key;
    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.  For this reason,
     * the automagic key is not regenerated on each reload.
     */
    get_key_info(listener->mctx, config, control,
             &global_keylist, &control_keylist, &explicit_key);

    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);

        if (! explicit_key)
            automagic_key.address = listener->address;

    } else if (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.
         */
        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));


    /*
     * Now, keep the old access list unless a new one can be made.
     */
    allow = cfg_tuple_get(control, "allow");
    result = ns_acl_fromconfig(allow, config, aclconfctx,
                   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);
    } else
        /* XXXDCL say the old acl is still used? */
        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));

    *listenerp = listener;
}

static void
add_listener(ns_controls_t *cp, controllistener_t **listenerp,
         cfg_obj_t *control, cfg_obj_t *config, isc_sockaddr_t *addr,
         ns_aclconfctx_t *aclconfctx, char *socktext)
{
    isc_mem_t *mctx = cp->server->mctx;
    controllistener_t *listener;
    cfg_obj_t *allow;
    cfg_obj_t *global_keylist = NULL;
    cfg_obj_t *control_keylist = NULL;
    dns_acl_t *new_acl = NULL;
    isc_boolean_t explicit_key;
    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;
        ISC_LINK_INIT(listener, link);
        ISC_LIST_INIT(listener->keys);
        ISC_LIST_INIT(listener->connections);

        /*
         * Make the acl.
         */
        allow = cfg_tuple_get(control, "allow");
        result = ns_acl_fromconfig(allow, config, aclconfctx, mctx,
                       &new_acl);
    }

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

        get_key_info(listener->mctx, config, control,
                 &global_keylist, &control_keylist, &explicit_key);

        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);

            if (! explicit_key)
                automagic_key.address = listener->address;

        } else
            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) ||
            (pf == AF_INET6 && isc_net_probeipv6() != ISC_R_SUCCESS))
            result = ISC_R_FAMILYNOSUPPORT;
    }

    if (result == ISC_R_SUCCESS)
        result = isc_socket_create(ns_g_socketmgr,
                       isc_sockaddr_pf(&listener->address),
                       isc_sockettype_tcp,
                       &listener->sock);

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

    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);
        }

        cfg_obj_log(control, ns_g_lctx, ISC_LOG_WARNING,
                "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, cfg_obj_t *config,
              ns_aclconfctx_t *aclconfctx)
{
    controllistener_t *listener;
    controllistenerlist_t new_listeners;
    cfg_obj_t *controlslist = NULL;
    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)) {
            cfg_obj_t *controls;
            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)) {
                cfg_obj_t *control;
                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.
                 *
                 * "unix" phrases have been reported as
                 * unsupported by the parser.
                 */
                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);

                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);

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

        finalize_automagic_key();

        /*
         * 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.
         */
        ns_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);

    } else {
        isc_result_t result;

        result = parse_automagic_key(cp->server->mctx);

        if (result == ISC_R_SUCCESS)
            ns_controls_configure(cp, automagic_key.config,
                         aclconfctx);
    }

    return (ISC_R_SUCCESS);
}

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

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