bin/named/client.c

	client.c revision 260b413740a3f1eeef333862c70767df40678404
/*
 * Copyright (C) 1999  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.
 */

#include <config.h>

#include <isc/assertions.h>
#include <isc/mem.h>
#include <isc/mutex.h>
#include <isc/result.h>
#include <isc/task.h>
#include <isc/timer.h>

#include <dns/dispatch.h>
#include <dns/events.h>
#include <dns/message.h>

#include <named/client.h>
#include <named/query.h>

#include "../../isc/util.h"     /* XXX */

#define NS_CLIENT_TRACE
#ifdef NS_CLIENT_TRACE
#include <stdio.h>
#define CTRACE(m)   printf("client %p: %s\n", client, (m))
#define MTRACE(m)   printf("clientmgr %p: %s\n", manager, (m))
#else
#define CTRACE(m)
#define MTRACE(m)
#endif

#define SEND_BUFFER_SIZE        512

struct ns_clientmgr {
    /* Unlocked. */
    unsigned int            magic;
    isc_mem_t *         mctx;
    isc_taskmgr_t *         taskmgr;
    isc_timermgr_t *        timermgr;
    isc_mutex_t         lock;
    /* Locked by lock. */
    isc_boolean_t           exiting;
    unsigned int            nclients;
    ISC_LIST(ns_client_t)       clients;
};

#define MANAGER_MAGIC           0x4E53436DU /* NSCm */
#define VALID_MANAGER(m)        ((m) != NULL && \
                     (m)->magic == MANAGER_MAGIC)


static void clientmgr_destroy(ns_clientmgr_t *manager);


/***
 *** Client
 ***/

/*
 * Important note!
 *
 * All client state changes, other than that from idle to listening, occur
 * as a result of events.  This guarantees serialization and avoids the
 * need for locking.
 *
 * If a routine is ever created that allows someone other than the client's
 * task to change the client, then the client will have to be locked.
 */

static inline void
client_free(ns_client_t *client) {
    dns_dispatchevent_t **deventp;
    isc_dynbuffer_t *dbuf, *dbuf_next;
    isc_mem_t *mctx;

    CTRACE("free");

    mctx = client->manager->mctx;
    for (dbuf = ISC_LIST_HEAD(client->namebufs);
         dbuf != NULL;
         dbuf = dbuf_next) {
        dbuf_next = ISC_LIST_NEXT(dbuf, link);
        isc_dynbuffer_free(mctx, &dbuf);
    }
    ISC_LIST_INIT(client->namebufs);
    isc_mempool_destroy(&client->sendbufs);
    dns_message_destroy(&client->message);
    isc_timer_detach(&client->timer);
    if (client->dispentry != NULL) {
        if (client->dispevent != NULL)
            deventp = &client->dispevent;
        else
            deventp = NULL;
        dns_dispatch_removerequest(client->dispatch,
                       &client->dispentry,
                       deventp);
    }
    if (client->dispatch != NULL)
        dns_dispatch_detach(&client->dispatch);
    isc_task_detach(&client->task);
    client->magic = 0;

    isc_mem_put(mctx, client, sizeof *client);
}

void
ns_client_destroy(ns_client_t *client) {
    ns_clientmgr_t *manager;
    isc_boolean_t need_clientmgr_destroy = ISC_FALSE;

    REQUIRE(NS_CLIENT_VALID(client));

    CTRACE("destroy");

    manager = client->manager;

    LOCK(&manager->lock);

    INSIST(manager->nclients > 0);
    manager->nclients--;
    if (manager->nclients == 0 && manager->exiting)
        need_clientmgr_destroy = ISC_TRUE;
    ISC_LIST_UNLINK(manager->clients, client, link);

    UNLOCK(&manager->lock);

    client_free(client);

    if (need_clientmgr_destroy)
        clientmgr_destroy(manager);
}

static void
client_shutdown(isc_task_t *task, isc_event_t *event) {
    ns_client_t *client;

    REQUIRE(event != NULL);
    REQUIRE(event->type == ISC_TASKEVENT_SHUTDOWN);
    client = event->arg;
    REQUIRE(NS_CLIENT_VALID(client));
    REQUIRE(task == client->task);

    CTRACE("shutdown");

    ns_client_destroy(client);

    isc_event_free(&event);
}

void
ns_client_next(ns_client_t *client, isc_result_t result) {
    isc_dynbuffer_t *dbuf, *dbuf_next;

    REQUIRE(NS_CLIENT_VALID(client));
    REQUIRE(client->state == ns_clientstate_listening ||
        client->state == ns_clientstate_working);

    CTRACE("next");

    /*
     * XXXRTH  If result != ISC_R_SUCCESS:
     *      Log result if there is interest in doing so.
     *      If this is a TCP client, close the connection.
     */
    (void)result;

    /*
     * Reset any changes made by answering a query.  XXXRTH  Should this
     * be in query.c?  We'll free all but one namebuf.
     */
    client->qname = NULL;
    INSIST(!ISC_LIST_EMPTY(client->namebufs));
    for (dbuf = ISC_LIST_HEAD(client->namebufs);
         dbuf != NULL;
         dbuf = dbuf_next) {
        dbuf_next = ISC_LIST_NEXT(dbuf, link);
        if (dbuf_next != NULL) {
            ISC_LIST_UNLINK(client->namebufs, dbuf, link);
            isc_dynbuffer_free(client->manager->mctx, &dbuf);
        }
    }

    dns_message_reset(client->message, DNS_MESSAGE_INTENTPARSE);
    if (client->dispevent != NULL) {
        dns_dispatch_freeevent(client->dispatch, client->dispentry,
                       &client->dispevent);
        client->state = ns_clientstate_listening;
    }
}

static void
client_senddone(isc_task_t *task, isc_event_t *event) {
    ns_client_t *client;
    isc_socketevent_t *sevent = (isc_socketevent_t *)event;

    REQUIRE(sevent != NULL);
    REQUIRE(sevent->type == ISC_SOCKEVENT_SENDDONE);
    client = sevent->arg;
    REQUIRE(NS_CLIENT_VALID(client));
    REQUIRE(task == client->task);

    CTRACE("senddone");

    INSIST(client->nsends > 0);
    client->nsends--;
    isc_mempool_put(client->sendbufs, sevent->region.base);

    isc_event_free(&event);

    /*
     * If all of its sendbufs buffers were busy, the client might be
     * waiting for one to become available.
     */
    if (client->state == ns_clientstate_waiting) {
        client->state = ns_clientstate_working;
        ns_client_send(client);
        return;
    }
    /* XXXRTH need to add exit draining mode. */
}

void
ns_client_send(ns_client_t *client) {
    isc_result_t result;
    unsigned char *data;
    isc_buffer_t buffer;
    isc_region_t r;

    REQUIRE(NS_CLIENT_VALID(client));

    CTRACE("send");

    data = isc_mempool_get(client->sendbufs);
    if (data == NULL) {
        CTRACE("no buffers available");
        if (client->nsends > 0) {
            /*
             * We couldn't get memory, but there is at least one
             * send outstanding.  We arrange to be restarted when a
             * send completes.
             */
            CTRACE("waiting");
            INSIST(client->state == ns_clientstate_working);
            client->state = ns_clientstate_waiting;
        } else
            ns_client_next(client, ISC_R_NOMEMORY);
        return;
    }

    /*
     * XXXRTH  The following doesn't deal with truncation, TSIGs,
     *         or ENDS1 more data packets.
     */
    isc_buffer_init(&buffer, data, SEND_BUFFER_SIZE,
            ISC_BUFFERTYPE_BINARY);
    result = dns_message_renderbegin(client->message, &buffer);
    if (result != ISC_R_SUCCESS)
        goto done;
    result = dns_message_rendersection(client->message,
                       DNS_SECTION_QUESTION, 0, 0);
    if (result != ISC_R_SUCCESS)
        goto done;
    result = dns_message_rendersection(client->message,
                       DNS_SECTION_ANSWER, 0, 0);
    if (result != ISC_R_SUCCESS)
        goto done;
    result = dns_message_rendersection(client->message,
                       DNS_SECTION_AUTHORITY, 0, 0);
    if (result != ISC_R_SUCCESS)
        goto done;
    result = dns_message_rendersection(client->message,
                       DNS_SECTION_ADDITIONAL, 0, 0);
    if (result != ISC_R_SUCCESS && result != ISC_R_NOSPACE)
        goto done;
    result = dns_message_renderend(client->message);
    if (result != ISC_R_SUCCESS)
        goto done;
    isc_buffer_used(&buffer, &r);
    /*
     * XXXRTH this only works for UDP clients.
     */
    CTRACE("sendto");
    result = isc_socket_sendto(dns_dispatch_getsocket(client->dispatch),
                   &r, client->task, client_senddone, client,
                   &client->dispevent->addr);
    if (result == ISC_R_SUCCESS)
        client->nsends++;

 done:
    if (result != ISC_R_SUCCESS)
        isc_mempool_put(client->sendbufs, data);

    ns_client_next(client, result);
}

void
ns_client_error(ns_client_t *client, isc_result_t result) {
    dns_rcode_t rcode;

    REQUIRE(NS_CLIENT_VALID(client));

    CTRACE("error");

    rcode = dns_result_torcode(result);

    /*
     * client->message may be an in-progress reply that we had trouble
     * with, in which case QR will be set.  We need to clear QR before
     * calling dns_message_reply() to avoid triggering an assertion.
     */
    client->message->flags &= ~DNS_MESSAGEFLAG_QR;
    result = dns_message_reply(client->message, ISC_TRUE);
    if (result != ISC_R_SUCCESS) {
        ns_client_next(client, result);
        return;
    }
    client->message->rcode = rcode;
    ns_client_send(client);
}

static void
client_recv(isc_task_t *task, isc_event_t *event) {
    ns_client_t *client;
    dns_dispatchevent_t *devent = (dns_dispatchevent_t *)event;
    isc_result_t result;

    REQUIRE(devent != NULL);
    REQUIRE(devent->type == DNS_EVENT_DISPATCH);
    client = devent->arg;
    REQUIRE(NS_CLIENT_VALID(client));
    REQUIRE(task == client->task);
    REQUIRE(client->dispentry != NULL);

    CTRACE("recv");

    client->dispevent = devent;
    if (devent->result != ISC_R_SUCCESS) {
        ns_client_destroy(client);
        return;
    }

    client->state = ns_clientstate_working;
    result = dns_message_parse(client->message, &devent->buffer);
    if (result != ISC_R_SUCCESS) {
        ns_client_error(client, result);
        return;
    }
    INSIST((client->message->flags & DNS_MESSAGEFLAG_QR) == 0);

    /* XXXRTH Find view here. */

    /*
     * Dispatch the request.
     */
    switch (client->message->opcode) {
    case dns_opcode_query:
        CTRACE("query");
        ns_query_start(client);
        break;
    case dns_opcode_iquery:
        CTRACE("iquery");
        ns_client_error(client, DNS_R_REFUSED);
    default:
        CTRACE("unknown opcode");
        ns_client_error(client, DNS_R_NOTIMP);
    }
}

static void
client_timeout(isc_task_t *task, isc_event_t *event) {
    ns_client_t *client;

    REQUIRE(event != NULL);
    REQUIRE(event->type == ISC_TIMEREVENT_LIFE ||
        event->type == ISC_TIMEREVENT_IDLE);
    client = event->arg;
    REQUIRE(NS_CLIENT_VALID(client));
    REQUIRE(task == client->task);
    REQUIRE(client->timer != NULL);

    CTRACE("timeout");

    isc_event_free(&event);

    ns_client_next(client, ISC_R_TIMEDOUT);
}

isc_result_t
ns_client_newnamebuf(ns_client_t *client) {
    isc_dynbuffer_t *dbuf;
    isc_result_t result;

    REQUIRE(NS_CLIENT_VALID(client));

    dbuf = NULL;
    result = isc_dynbuffer_allocate(client->manager->mctx, &dbuf, 1024,
                    ISC_BUFFERTYPE_BINARY);
    if (result != ISC_R_SUCCESS)
        return (result);
    ISC_LIST_APPEND(client->namebufs, dbuf, link);

    return (ISC_R_SUCCESS);
}

static isc_result_t
client_create(ns_clientmgr_t *manager, ns_clienttype_t type,
          ns_client_t **clientp)
{
    ns_client_t *client;
    isc_result_t result;
    isc_dynbuffer_t *dbuf;

    /*
     * Caller must be holding the manager lock.
     *
     * Note: creating a client does not add the client to the manager's
     * client list.  The caller is responsible for that.
     */

    REQUIRE(clientp != NULL && *clientp == NULL);

    client = isc_mem_get(manager->mctx, sizeof *client);
    if (client == NULL)
        return (ISC_R_NOMEMORY);

    client->task = NULL;
    result = isc_task_create(manager->taskmgr, manager->mctx, 0,
                 &client->task);
    if (result != ISC_R_SUCCESS)
        goto cleanup_client;
    result = isc_task_onshutdown(client->task, client_shutdown, client);
    if (result != ISC_R_SUCCESS)
        goto cleanup_task;

    client->timer = NULL;
    result = isc_timer_create(manager->timermgr, isc_timertype_inactive,
                  NULL, NULL, client->task, client_timeout,
                  client, &client->timer);
    if (result != ISC_R_SUCCESS)
        goto cleanup_task;

    client->message = NULL;
    result = dns_message_create(manager->mctx, DNS_MESSAGE_INTENTPARSE,
                    &client->message);
    if (result != ISC_R_SUCCESS)
        goto cleanup_timer;

    /* XXXRTH  Hardwired constants */
    client->sendbufs = NULL;
    result = isc_mempool_create(manager->mctx, SEND_BUFFER_SIZE,
                    &client->sendbufs);
    if (result != ISC_R_SUCCESS)
        goto cleanup_message;
    isc_mempool_setfreemax(client->sendbufs, 3);
    isc_mempool_setmaxalloc(client->sendbufs, 3);

    /*
     * We do the rest of the initialization here because the
     * ns_client_newnamebuf() call below REQUIREs a valid client.
     */
    client->magic = NS_CLIENT_MAGIC;
    client->manager = manager;
    client->type = type;
    client->state = ns_clientstate_idle;
    client->attributes = 0;
    client->dispatch = NULL;
    client->dispentry = NULL;
    client->dispevent = NULL;
    client->qname = NULL;
    client->nsends = 0;
    ISC_LIST_INIT(client->namebufs);
    ISC_LINK_INIT(client, link);

    dbuf = NULL;
    result = ns_client_newnamebuf(client);
    if (result != ISC_R_SUCCESS)
        goto cleanup_sendbufs;

    CTRACE("create");

    *clientp = client;

    return (ISC_R_SUCCESS);

 cleanup_sendbufs:
    isc_mempool_destroy(&client->sendbufs);

 cleanup_message:
    dns_message_destroy(&client->message);

 cleanup_timer:
    isc_timer_detach(&client->timer);

 cleanup_task:
    isc_task_detach(&client->task);

 cleanup_client:
    isc_mem_put(manager->mctx, client, sizeof *client);

    return (result);
}


/***
 *** Client Manager
 ***/

static void
clientmgr_destroy(ns_clientmgr_t *manager) {
    REQUIRE(manager->nclients == 0);
    REQUIRE(ISC_LIST_EMPTY(manager->clients));

    MTRACE("clientmgr_destroy");

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

isc_result_t
ns_clientmgr_create(isc_mem_t *mctx, isc_taskmgr_t *taskmgr,
            isc_timermgr_t *timermgr, ns_clientmgr_t **managerp)
{
    ns_clientmgr_t *manager;
    isc_result_t result;

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

    result = isc_mutex_init(&manager->lock);
    if (result != ISC_R_SUCCESS)
        goto cleanup_manager;

    manager->mctx = mctx;
    manager->taskmgr = taskmgr;
    manager->timermgr = timermgr;
    manager->exiting = ISC_FALSE;
    manager->nclients = 0;
    ISC_LIST_INIT(manager->clients);
    manager->magic = MANAGER_MAGIC;

    MTRACE("create");

    *managerp = manager;

    return (ISC_R_SUCCESS);

 cleanup_manager:
    isc_mem_put(manager->mctx, manager, sizeof *manager);

    return (result);
}

void
ns_clientmgr_destroy(ns_clientmgr_t **managerp) {
    ns_clientmgr_t *manager;
    ns_client_t *client;
    isc_boolean_t need_destroy = ISC_FALSE;

    REQUIRE(managerp != NULL);
    manager = *managerp;
    REQUIRE(VALID_MANAGER(manager));

    MTRACE("destroy");

    LOCK(&manager->lock);

    manager->exiting = ISC_TRUE;

    for (client = ISC_LIST_HEAD(manager->clients);
         client != NULL;
         client = ISC_LIST_NEXT(client, link))
        isc_task_shutdown(client->task);

    if (ISC_LIST_EMPTY(manager->clients))
        need_destroy = ISC_TRUE;

    UNLOCK(&manager->lock);

    if (need_destroy)
        clientmgr_destroy(manager);

    *managerp = NULL;
}

isc_result_t
ns_clientmgr_addtodispatch(ns_clientmgr_t *manager, ns_clienttype_t type,
               unsigned int n,
               dns_dispatch_t *dispatch)
{
    isc_result_t result = ISC_R_SUCCESS;
    unsigned int i;
    ns_client_t *client;

    REQUIRE(VALID_MANAGER(manager));
    REQUIRE(n > 0);

    MTRACE("addtodispatch");

    /*
     * We MUST lock the manager lock for the entire client creation
     * process.  If we didn't do this, then a client could get a
     * shutdown event and disappear out from under us.
     */

    LOCK(&manager->lock);

    for (i = 0; i < n; i++) {
        client = NULL;
        result = client_create(manager, type, &client);
        if (result != ISC_R_SUCCESS)
            break;
        dns_dispatch_attach(dispatch, &client->dispatch);
        result = dns_dispatch_addrequest(dispatch, client->task,
                         client_recv,
                         client, &client->dispentry);
        if (result != ISC_R_SUCCESS) {
            client_free(client);
            break;
        }
        client->state = ns_clientstate_listening;
        manager->nclients++;
        ISC_LIST_APPEND(manager->clients, client, link);
    }
    if (i != 0) {
        /*
         * We managed to create at least one client, so we
         * declare victory.
         */
        result = ISC_R_SUCCESS;
    }

    UNLOCK(&manager->lock);

    return (result);
}