lib/dns/forward.c

/*
 * Copyright (C) 2000, 2001, 2004, 2005, 2007, 2009, 2013, 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/.
 */

/*! \file */

#include <config.h>

#include <isc/magic.h>
#include <isc/mem.h>
#include <isc/rwlock.h>
#include <isc/util.h>

#include <dns/forward.h>
#include <dns/rbt.h>
#include <dns/result.h>
#include <dns/types.h>

struct dns_fwdtable {
    /* Unlocked. */
    unsigned int        magic;
    isc_mem_t       *mctx;
    isc_rwlock_t        rwlock;
    /* Locked by lock. */
    dns_rbt_t       *table;
};

#define FWDTABLEMAGIC       ISC_MAGIC('F', 'w', 'd', 'T')
#define VALID_FWDTABLE(ft)  ISC_MAGIC_VALID(ft, FWDTABLEMAGIC)

static void
auto_detach(void *, void *);

isc_result_t
dns_fwdtable_create(isc_mem_t *mctx, dns_fwdtable_t **fwdtablep) {
    dns_fwdtable_t *fwdtable;
    isc_result_t result;

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

    fwdtable = isc_mem_get(mctx, sizeof(dns_fwdtable_t));
    if (fwdtable == NULL)
        return (ISC_R_NOMEMORY);

    fwdtable->table = NULL;
    result = dns_rbt_create(mctx, auto_detach, fwdtable, &fwdtable->table);
    if (result != ISC_R_SUCCESS)
        goto cleanup_fwdtable;

    result = isc_rwlock_init(&fwdtable->rwlock, 0, 0);
    if (result != ISC_R_SUCCESS)
        goto cleanup_rbt;

    fwdtable->mctx = NULL;
    isc_mem_attach(mctx, &fwdtable->mctx);
    fwdtable->magic = FWDTABLEMAGIC;
    *fwdtablep = fwdtable;

    return (ISC_R_SUCCESS);

   cleanup_rbt:
    dns_rbt_destroy(&fwdtable->table);

   cleanup_fwdtable:
    isc_mem_put(mctx, fwdtable, sizeof(dns_fwdtable_t));

    return (result);
}

isc_result_t
dns_fwdtable_addfwd(dns_fwdtable_t *fwdtable, dns_name_t *name,
            dns_forwarderlist_t *fwdrs, dns_fwdpolicy_t fwdpolicy)
{
    isc_result_t result;
    dns_forwarders_t *forwarders;
    dns_forwarder_t *fwd, *nfwd;

    REQUIRE(VALID_FWDTABLE(fwdtable));

    forwarders = isc_mem_get(fwdtable->mctx, sizeof(dns_forwarders_t));
    if (forwarders == NULL)
        return (ISC_R_NOMEMORY);

    ISC_LIST_INIT(forwarders->fwdrs);
    for (fwd = ISC_LIST_HEAD(*fwdrs);
         fwd != NULL;
         fwd = ISC_LIST_NEXT(fwd, link))
    {
        nfwd = isc_mem_get(fwdtable->mctx, sizeof(dns_forwarder_t));
        if (nfwd == NULL) {
            result = ISC_R_NOMEMORY;
            goto cleanup;
        }
        *nfwd = *fwd;
        ISC_LINK_INIT(nfwd, link);
        ISC_LIST_APPEND(forwarders->fwdrs, nfwd, link);
    }
    forwarders->fwdpolicy = fwdpolicy;

    RWLOCK(&fwdtable->rwlock, isc_rwlocktype_write);
    result = dns_rbt_addname(fwdtable->table, name, forwarders);
    RWUNLOCK(&fwdtable->rwlock, isc_rwlocktype_write);

    if (result != ISC_R_SUCCESS)
        goto cleanup;

    return (ISC_R_SUCCESS);

 cleanup:
    while (!ISC_LIST_EMPTY(forwarders->fwdrs)) {
        fwd = ISC_LIST_HEAD(forwarders->fwdrs);
        ISC_LIST_UNLINK(forwarders->fwdrs, fwd, link);
        isc_mem_put(fwdtable->mctx, fwd, sizeof(isc_sockaddr_t));
    }
    isc_mem_put(fwdtable->mctx, forwarders, sizeof(dns_forwarders_t));
    return (result);
}

isc_result_t
dns_fwdtable_add(dns_fwdtable_t *fwdtable, dns_name_t *name,
         isc_sockaddrlist_t *addrs, dns_fwdpolicy_t fwdpolicy)
{
    isc_result_t result;
    dns_forwarders_t *forwarders;
    dns_forwarder_t *fwd;
    isc_sockaddr_t *sa;

    REQUIRE(VALID_FWDTABLE(fwdtable));

    forwarders = isc_mem_get(fwdtable->mctx, sizeof(dns_forwarders_t));
    if (forwarders == NULL)
        return (ISC_R_NOMEMORY);

    ISC_LIST_INIT(forwarders->fwdrs);
    for (sa = ISC_LIST_HEAD(*addrs);
         sa != NULL;
         sa = ISC_LIST_NEXT(sa, link))
    {
        fwd = isc_mem_get(fwdtable->mctx, sizeof(dns_forwarder_t));
        if (fwd == NULL) {
            result = ISC_R_NOMEMORY;
            goto cleanup;
        }
        fwd->addr = *sa;
        fwd->dscp = -1;
        ISC_LINK_INIT(fwd, link);
        ISC_LIST_APPEND(forwarders->fwdrs, fwd, link);
    }
    forwarders->fwdpolicy = fwdpolicy;

    RWLOCK(&fwdtable->rwlock, isc_rwlocktype_write);
    result = dns_rbt_addname(fwdtable->table, name, forwarders);
    RWUNLOCK(&fwdtable->rwlock, isc_rwlocktype_write);

    if (result != ISC_R_SUCCESS)
        goto cleanup;

    return (ISC_R_SUCCESS);

 cleanup:
    while (!ISC_LIST_EMPTY(forwarders->fwdrs)) {
        fwd = ISC_LIST_HEAD(forwarders->fwdrs);
        ISC_LIST_UNLINK(forwarders->fwdrs, fwd, link);
        isc_mem_put(fwdtable->mctx, fwd, sizeof(dns_forwarder_t));
    }
    isc_mem_put(fwdtable->mctx, forwarders, sizeof(dns_forwarders_t));
    return (result);
}

isc_result_t
dns_fwdtable_delete(dns_fwdtable_t *fwdtable, dns_name_t *name) {
    isc_result_t result;

    REQUIRE(VALID_FWDTABLE(fwdtable));

    RWLOCK(&fwdtable->rwlock, isc_rwlocktype_write);
    result = dns_rbt_deletename(fwdtable->table, name, ISC_FALSE);
    RWUNLOCK(&fwdtable->rwlock, isc_rwlocktype_write);

    if (result == DNS_R_PARTIALMATCH)
        result = ISC_R_NOTFOUND;

    return (result);
}

isc_result_t
dns_fwdtable_find(dns_fwdtable_t *fwdtable, dns_name_t *name,
          dns_forwarders_t **forwardersp)
{
    return (dns_fwdtable_find2(fwdtable, name, NULL, forwardersp));
}

isc_result_t
dns_fwdtable_find2(dns_fwdtable_t *fwdtable, dns_name_t *name,
           dns_name_t *foundname, dns_forwarders_t **forwardersp)
{
    isc_result_t result;

    REQUIRE(VALID_FWDTABLE(fwdtable));

    RWLOCK(&fwdtable->rwlock, isc_rwlocktype_read);

    result = dns_rbt_findname(fwdtable->table, name, 0, foundname,
                  (void **)forwardersp);
    if (result == DNS_R_PARTIALMATCH)
        result = ISC_R_SUCCESS;

    RWUNLOCK(&fwdtable->rwlock, isc_rwlocktype_read);

    return (result);
}

void
dns_fwdtable_destroy(dns_fwdtable_t **fwdtablep) {
    dns_fwdtable_t *fwdtable;
    isc_mem_t *mctx;

    REQUIRE(fwdtablep != NULL && VALID_FWDTABLE(*fwdtablep));

    fwdtable = *fwdtablep;

    dns_rbt_destroy(&fwdtable->table);
    isc_rwlock_destroy(&fwdtable->rwlock);
    fwdtable->magic = 0;
    mctx = fwdtable->mctx;
    isc_mem_put(mctx, fwdtable, sizeof(dns_fwdtable_t));
    isc_mem_detach(&mctx);

    *fwdtablep = NULL;
}

/***
 *** Private
 ***/

static void
auto_detach(void *data, void *arg) {
    dns_forwarders_t *forwarders = data;
    dns_fwdtable_t *fwdtable = arg;
    dns_forwarder_t *fwd;

    UNUSED(arg);

    while (!ISC_LIST_EMPTY(forwarders->fwdrs)) {
        fwd = ISC_LIST_HEAD(forwarders->fwdrs);
        ISC_LIST_UNLINK(forwarders->fwdrs, fwd, link);
        isc_mem_put(fwdtable->mctx, fwd, sizeof(dns_forwarder_t));
    }
    isc_mem_put(fwdtable->mctx, forwarders, sizeof(dns_forwarders_t));
}