bin/named/lwdgabn.c

/*
 * Copyright (C) 2000, 2001, 2004-2007, 2009, 2016  Internet Systems Consortium, Inc. ("ISC")
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/.
 */

/* $Id: lwdgabn.c,v 1.24 2009/09/02 23:48:01 tbox Exp $ */

/*! \file */

#include <config.h>

#include <stdlib.h>

#include <isc/netaddr.h>
#include <isc/sockaddr.h>
#include <isc/socket.h>
#include <isc/string.h>     /* Required for HP/UX (and others?) */
#include <isc/util.h>

#include <dns/adb.h>
#include <dns/events.h>
#include <dns/result.h>

#include <named/types.h>
#include <named/lwaddr.h>
#include <named/lwdclient.h>
#include <named/lwresd.h>
#include <named/lwsearch.h>
#include <named/sortlist.h>

#define NEED_V4(c)  ((((c)->find_wanted & LWRES_ADDRTYPE_V4) != 0) \
             && ((c)->v4find == NULL))
#define NEED_V6(c)  ((((c)->find_wanted & LWRES_ADDRTYPE_V6) != 0) \
             && ((c)->v6find == NULL))

static isc_result_t start_find(ns_lwdclient_t *);
static void restart_find(ns_lwdclient_t *);
static void init_gabn(ns_lwdclient_t *);

/*%
 * Destroy any finds.  This can be used to "start over from scratch" and
 * should only be called when events are _not_ being generated by the finds.
 */
static void
cleanup_gabn(ns_lwdclient_t *client) {
    ns_lwdclient_log(50, "cleaning up client %p", client);

    if (client->v6find != NULL) {
        if (client->v6find == client->v4find)
            client->v6find = NULL;
        else
            dns_adb_destroyfind(&client->v6find);
    }
    if (client->v4find != NULL)
        dns_adb_destroyfind(&client->v4find);
}

static void
setup_addresses(ns_lwdclient_t *client, dns_adbfind_t *find, unsigned int at) {
    dns_adbaddrinfo_t *ai;
    lwres_addr_t *addr;
    int af;
    const struct sockaddr *sa;
    isc_result_t result;

    if (at == DNS_ADBFIND_INET)
        af = AF_INET;
    else
        af = AF_INET6;

    ai = ISC_LIST_HEAD(find->list);
    while (ai != NULL && client->gabn.naddrs < LWRES_MAX_ADDRS) {
        sa = &ai->sockaddr.type.sa;
        if (sa->sa_family != af)
            goto next;

        addr = &client->addrs[client->gabn.naddrs];

        result = lwaddr_lwresaddr_fromsockaddr(addr, &ai->sockaddr);
        if (result != ISC_R_SUCCESS)
            goto next;

        ns_lwdclient_log(50, "adding address %p, family %d, length %d",
                 addr->address, addr->family, addr->length);

        client->gabn.naddrs++;
        REQUIRE(!LWRES_LINK_LINKED(addr, link));
        LWRES_LIST_APPEND(client->gabn.addrs, addr, link);

    next:
        ai = ISC_LIST_NEXT(ai, publink);
    }
}

typedef struct {
    isc_netaddr_t address;
    int rank;
} rankedaddress;

static int
addr_compare(const void *av, const void *bv) {
    const rankedaddress *a = (const rankedaddress *) av;
    const rankedaddress *b = (const rankedaddress *) bv;
    return (a->rank - b->rank);
}

static void
sort_addresses(ns_lwdclient_t *client) {
    unsigned int naddrs;
    rankedaddress *addrs;
    isc_netaddr_t remote;
    dns_addressorderfunc_t order;
    const void *arg;
    ns_lwresd_t *lwresd = client->clientmgr->listener->manager;
    unsigned int i;
    isc_result_t result;

    naddrs = client->gabn.naddrs;

    if (naddrs <= 1 || lwresd->view->sortlist == NULL)
        return;

    addrs = isc_mem_get(lwresd->mctx, sizeof(rankedaddress) * naddrs);
    if (addrs == NULL)
        return;

    isc_netaddr_fromsockaddr(&remote, &client->address);
    ns_sortlist_byaddrsetup(lwresd->view->sortlist,
                &remote, &order, &arg);
    if (order == NULL) {
        isc_mem_put(lwresd->mctx, addrs,
                sizeof(rankedaddress) * naddrs);
        return;
    }
    for (i = 0; i < naddrs; i++) {
        result = lwaddr_netaddr_fromlwresaddr(&addrs[i].address,
                              &client->addrs[i]);
        INSIST(result == ISC_R_SUCCESS);
        addrs[i].rank = (*order)(&addrs[i].address, arg);
    }
    qsort(addrs, naddrs, sizeof(rankedaddress), addr_compare);
    for (i = 0; i < naddrs; i++) {
        result = lwaddr_lwresaddr_fromnetaddr(&client->addrs[i],
                              &addrs[i].address);
        INSIST(result == ISC_R_SUCCESS);
    }

    isc_mem_put(lwresd->mctx, addrs, sizeof(rankedaddress) * naddrs);
}

static void
generate_reply(ns_lwdclient_t *client) {
    isc_result_t result;
    int lwres;
    isc_region_t r;
    lwres_buffer_t lwb;
    ns_lwdclientmgr_t *cm;

    cm = client->clientmgr;
    lwb.base = NULL;

    ns_lwdclient_log(50, "generating gabn reply for client %p", client);

    /*
     * We must make certain the client->find is not still active.
     * If it is either the v4 or v6 answer, just set it to NULL and
     * let the cleanup code destroy it.  Otherwise, destroy it now.
     */
    if (client->find == client->v4find || client->find == client->v6find)
        client->find = NULL;
    else
        if (client->find != NULL)
            dns_adb_destroyfind(&client->find);

    /*
     * perhaps there are some here?
     */
    if (NEED_V6(client) && client->v4find != NULL)
        client->v6find = client->v4find;

    /*
     * Run through the finds we have and wire them up to the gabn
     * structure.
     */
    LWRES_LIST_INIT(client->gabn.addrs);
    if (client->v4find != NULL)
        setup_addresses(client, client->v4find, DNS_ADBFIND_INET);
    if (client->v6find != NULL)
        setup_addresses(client, client->v6find, DNS_ADBFIND_INET6);

    /*
     * If there are no addresses, try the next element in the search
     * path, if there are any more.  Otherwise, fall through into
     * the error handling code below.
     */
    if (client->gabn.naddrs == 0) {
        do {
            result = ns_lwsearchctx_next(&client->searchctx);
            if (result == ISC_R_SUCCESS) {
                cleanup_gabn(client);
                result = start_find(client);
                if (result == ISC_R_SUCCESS)
                    return;
            }
        } while (result == ISC_R_SUCCESS);
    }

    /*
     * Render the packet.
     */
    client->pkt.recvlength = LWRES_RECVLENGTH;
    client->pkt.authtype = 0; /* XXXMLG */
    client->pkt.authlength = 0;

    /*
     * If there are no addresses, return failure.
     */
    if (client->gabn.naddrs != 0)
        client->pkt.result = LWRES_R_SUCCESS;
    else
        client->pkt.result = LWRES_R_NOTFOUND;

    sort_addresses(client);

    lwres = lwres_gabnresponse_render(cm->lwctx, &client->gabn,
                      &client->pkt, &lwb);
    if (lwres != LWRES_R_SUCCESS)
        goto out;

    r.base = lwb.base;
    r.length = lwb.used;
    client->sendbuf = r.base;
    client->sendlength = r.length;
    result = ns_lwdclient_sendreply(client, &r);
    if (result != ISC_R_SUCCESS)
        goto out;

    NS_LWDCLIENT_SETSEND(client);

    /*
     * All done!
     */
    cleanup_gabn(client);

    return;

 out:
    cleanup_gabn(client);

    if (lwb.base != NULL)
        lwres_context_freemem(client->clientmgr->lwctx,
                      lwb.base, lwb.length);

    ns_lwdclient_errorpktsend(client, LWRES_R_FAILURE);
}

/*
 * Take the current real name, move it to an alias slot (if any are
 * open) then put this new name in as the real name for the target.
 *
 * Return success if it can be rendered, otherwise failure.  Note that
 * not having enough alias slots open is NOT a failure.
 */
static isc_result_t
add_alias(ns_lwdclient_t *client) {
    isc_buffer_t b;
    isc_result_t result;
    isc_uint16_t naliases;

    b = client->recv_buffer;

    /*
     * Render the new name to the buffer.
     */
    result = dns_name_totext(dns_fixedname_name(&client->target_name),
                 ISC_TRUE, &client->recv_buffer);
    if (result != ISC_R_SUCCESS)
        return (result);

    /*
     * Are there any open slots?
     */
    naliases = client->gabn.naliases;
    if (naliases < LWRES_MAX_ALIASES) {
        client->gabn.aliases[naliases] = client->gabn.realname;
        client->gabn.aliaslen[naliases] = client->gabn.realnamelen;
        client->gabn.naliases++;
    }

    /*
     * Save this name away as the current real name.
     */
    client->gabn.realname = (char *)(b.base) + b.used;
    client->gabn.realnamelen = client->recv_buffer.used - b.used;

    return (ISC_R_SUCCESS);
}

static isc_result_t
store_realname(ns_lwdclient_t *client) {
    isc_buffer_t b;
    isc_result_t result;
    dns_name_t *tname;

    b = client->recv_buffer;

    tname = dns_fixedname_name(&client->target_name);
    result = ns_lwsearchctx_current(&client->searchctx, tname);
    if (result != ISC_R_SUCCESS)
        return (result);

    /*
     * Render the new name to the buffer.
     */
    result = dns_name_totext(tname, ISC_TRUE, &client->recv_buffer);
    if (result != ISC_R_SUCCESS)
        return (result);

    /*
     * Save this name away as the current real name.
     */
    client->gabn.realname = (char *) b.base + b.used;
    client->gabn.realnamelen = client->recv_buffer.used - b.used;

    return (ISC_R_SUCCESS);
}

static void
process_gabn_finddone(isc_task_t *task, isc_event_t *ev) {
    ns_lwdclient_t *client = ev->ev_arg;
    isc_eventtype_t evtype;
    isc_boolean_t claimed;

    ns_lwdclient_log(50, "find done for task %p, client %p", task, client);

    evtype = ev->ev_type;
    isc_event_free(&ev);

    /*
     * No more info to be had?  If so, we have all the good stuff
     * right now, so we can render things.
     */
    claimed = ISC_FALSE;
    if (evtype == DNS_EVENT_ADBNOMOREADDRESSES) {
        if (NEED_V4(client)) {
            client->v4find = client->find;
            claimed = ISC_TRUE;
        }
        if (NEED_V6(client)) {
            client->v6find = client->find;
            claimed = ISC_TRUE;
        }
        if (client->find != NULL) {
            if (claimed)
                client->find = NULL;
            else
                dns_adb_destroyfind(&client->find);

        }
        generate_reply(client);
        return;
    }

    /*
     * We probably don't need this find anymore.  We're either going to
     * reissue it, or an error occurred.  Either way, we're done with
     * it.
     */
    if ((client->find != client->v4find)
        && (client->find != client->v6find)) {
        dns_adb_destroyfind(&client->find);
    } else {
        client->find = NULL;
    }

    /*
     * We have some new information we can gather.  Run off and fetch
     * it.
     */
    if (evtype == DNS_EVENT_ADBMOREADDRESSES) {
        restart_find(client);
        return;
    }

    /*
     * An error or other strangeness happened.  Drop this query.
     */
    cleanup_gabn(client);
    ns_lwdclient_errorpktsend(client, LWRES_R_FAILURE);
}

static void
restart_find(ns_lwdclient_t *client) {
    unsigned int options;
    isc_result_t result;
    isc_boolean_t claimed;

    ns_lwdclient_log(50, "starting find for client %p", client);

    /*
     * Issue a find for the name contained in the request.  We won't
     * set the bit that says "anything is good enough" -- we want it
     * all.
     */
    options = 0;
    options |= DNS_ADBFIND_WANTEVENT;
    options |= DNS_ADBFIND_RETURNLAME;

    /*
     * Set the bits up here to mark that we want this address family
     * and that we do not currently have a find pending.  We will
     * set that bit again below if it turns out we will get an event.
     */
    if (NEED_V4(client))
        options |= DNS_ADBFIND_INET;
    if (NEED_V6(client))
        options |= DNS_ADBFIND_INET6;

 find_again:
    INSIST(client->find == NULL);
    result = dns_adb_createfind(client->clientmgr->view->adb,
                    client->clientmgr->task,
                    process_gabn_finddone, client,
                    dns_fixedname_name(&client->target_name),
                    dns_rootname, 0, options, 0,
                    dns_fixedname_name(&client->target_name),
                    client->clientmgr->view->dstport,
                    &client->find);

    /*
     * Did we get an alias?  If so, save it and re-issue the query.
     */
    if (result == DNS_R_ALIAS) {
        ns_lwdclient_log(50, "found alias, restarting query");
        dns_adb_destroyfind(&client->find);
        cleanup_gabn(client);
        result = add_alias(client);
        if (result != ISC_R_SUCCESS) {
            ns_lwdclient_log(50,
                     "out of buffer space adding alias");
            ns_lwdclient_errorpktsend(client, LWRES_R_FAILURE);
            return;
        }
        goto find_again;
    }

    ns_lwdclient_log(50, "find returned %d (%s)", result,
             isc_result_totext(result));

    /*
     * Did we get an error?
     */
    if (result != ISC_R_SUCCESS) {
        if (client->find != NULL)
            dns_adb_destroyfind(&client->find);
        cleanup_gabn(client);
        ns_lwdclient_errorpktsend(client, LWRES_R_FAILURE);
        return;
    }

    claimed = ISC_FALSE;

    /*
     * Did we get our answer to V4 addresses?
     */
    if (NEED_V4(client)
        && ((client->find->query_pending & DNS_ADBFIND_INET) == 0)) {
        ns_lwdclient_log(50, "client %p ipv4 satisfied by find %p",
                 client, client->find);
        claimed = ISC_TRUE;
        client->v4find = client->find;
    }

    /*
     * Did we get our answer to V6 addresses?
     */
    if (NEED_V6(client)
        && ((client->find->query_pending & DNS_ADBFIND_INET6) == 0)) {
        ns_lwdclient_log(50, "client %p ipv6 satisfied by find %p",
                 client, client->find);
        claimed = ISC_TRUE;
        client->v6find = client->find;
    }

    /*
     * If we're going to get an event, set our internal pending flag
     * and return.  When we get an event back we'll do the right
     * thing, basically by calling this function again, perhaps with a
     * new target name.
     *
     * If we have both v4 and v6, and we are still getting an event,
     * we have a programming error, so die hard.
     */
    if ((client->find->options & DNS_ADBFIND_WANTEVENT) != 0) {
        ns_lwdclient_log(50, "event will be sent");
        INSIST(client->v4find == NULL || client->v6find == NULL);
        return;
    }
    ns_lwdclient_log(50, "no event will be sent");
    if (claimed)
        client->find = NULL;
    else
        dns_adb_destroyfind(&client->find);

    /*
     * We seem to have everything we asked for, or at least we are
     * able to respond with things we've learned.
     */

    generate_reply(client);
}

static isc_result_t
start_find(ns_lwdclient_t *client) {
    isc_result_t result;

    /*
     * Initialize the real name and alias arrays in the reply we're
     * going to build up.
     */
    init_gabn(client);

    result = store_realname(client);
    if (result != ISC_R_SUCCESS)
        return (result);
    restart_find(client);
    return (ISC_R_SUCCESS);

}

static void
init_gabn(ns_lwdclient_t *client) {
    int i;

    /*
     * Initialize the real name and alias arrays in the reply we're
     * going to build up.
     */
    for (i = 0; i < LWRES_MAX_ALIASES; i++) {
        client->aliases[i] = NULL;
        client->aliaslen[i] = 0;
    }
    for (i = 0; i < LWRES_MAX_ADDRS; i++) {
        client->addrs[i].family = 0;
        client->addrs[i].length = 0;
        memset(client->addrs[i].address, 0, LWRES_ADDR_MAXLEN);
        LWRES_LINK_INIT(&client->addrs[i], link);
    }

    client->gabn.naliases = 0;
    client->gabn.naddrs = 0;
    client->gabn.realname = NULL;
    client->gabn.aliases = client->aliases;
    client->gabn.realnamelen = 0;
    client->gabn.aliaslen = client->aliaslen;
    LWRES_LIST_INIT(client->gabn.addrs);
    client->gabn.base = NULL;
    client->gabn.baselen = 0;

    /*
     * Set up the internal buffer to point to the receive region.
     */
    isc_buffer_init(&client->recv_buffer, client->buffer, LWRES_RECVLENGTH);
}

/*
 * When we are called, we can be assured that:
 *
 *  client->sockaddr contains the address we need to reply to,
 *
 *  client->pkt contains the packet header data,
 *
 *  the packet "checks out" overall -- any MD5 hashes or crypto
 *  bits have been verified,
 *
 *  "b" points to the remaining data after the packet header
 *  was parsed off.
 *
 *  We are in a the RECVDONE state.
 *
 * From this state we will enter the SEND state if we happen to have
 * everything we need or we need to return an error packet, or to the
 * FINDWAIT state if we need to look things up.
 */
void
ns_lwdclient_processgabn(ns_lwdclient_t *client, lwres_buffer_t *b) {
    isc_result_t result;
    lwres_gabnrequest_t *req;
    ns_lwdclientmgr_t *cm;
    isc_buffer_t namebuf;

    REQUIRE(NS_LWDCLIENT_ISRECVDONE(client));

    cm = client->clientmgr;
    req = NULL;

    result = lwres_gabnrequest_parse(client->clientmgr->lwctx,
                     b, &client->pkt, &req);
    if (result != LWRES_R_SUCCESS)
        goto out;
    if (req->name == NULL)
        goto out;

    isc_buffer_init(&namebuf, req->name, req->namelen);
    isc_buffer_add(&namebuf, req->namelen);

    dns_fixedname_init(&client->target_name);
    dns_fixedname_init(&client->query_name);
    result = dns_name_fromtext(dns_fixedname_name(&client->query_name),
                   &namebuf, NULL, 0, NULL);
    if (result != ISC_R_SUCCESS)
        goto out;
    ns_lwsearchctx_init(&client->searchctx,
                cm->listener->manager->search,
                dns_fixedname_name(&client->query_name),
                cm->listener->manager->ndots);
    ns_lwsearchctx_first(&client->searchctx);

    client->find_wanted = req->addrtypes;
    ns_lwdclient_log(50, "client %p looking for addrtypes %08x",
             client, client->find_wanted);

    /*
     * We no longer need to keep this around.
     */
    lwres_gabnrequest_free(client->clientmgr->lwctx, &req);

    /*
     * Start the find.
     */
    result = start_find(client);
    if (result != ISC_R_SUCCESS)
        goto out;

    return;

    /*
     * We're screwed.  Return an error packet to our caller.
     */
 out:
    if (req != NULL)
        lwres_gabnrequest_free(client->clientmgr->lwctx, &req);

    ns_lwdclient_errorpktsend(client, LWRES_R_FAILURE);
}