/*

 * Copyright (C) Internet Systems Consortium, Inc. ("ISC")

 *

 * SPDX-License-Identifier: MPL-2.0

 *

 * 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 https://mozilla.org/MPL/2.0/.

 *

 * See the COPYRIGHT file distributed with this work for additional

 * information regarding copyright ownership.

 */

#include <isc/buffer.h>

#include <isc/log.h>

#include <isc/mem.h>

#include <isc/mutex.h>

#include <isc/region.h>

#include <isc/result.h>

#include <isc/types.h>

#include <isc/util.h>

#include <isc/uv.h>

#include <dns/dyndb.h>

#include <dns/types.h>

#include <dns/view.h>

#include <dns/zone.h>

#include "dyndb_p.h"

typedef struct dyndb_implementation dyndb_implementation_t;

struct dyndb_implementation {

  isc_mem_t *mctx;

  uv_lib_t handle;

  dns_dyndb_register_t *register_func;

  dns_dyndb_destroy_t *destroy_func;

  char *name;

  void *inst;

  ISC_LINK(dyndb_implementation_t) link;

};

/*

 * List of dyndb implementations. Locked by dyndb_lock.

 *

 * These are stored here so they can be cleaned up on shutdown.

 * (The order in which they are stored is not important.)

 */

static ISC_LIST(dyndb_implementation_t) dyndb_implementations;

/* Locks dyndb_implementations. */

static isc_mutex_t dyndb_lock;

void

dns__dyndb_initialize(void) {

  isc_mutex_init(&dyndb_lock);

  ISC_LIST_INIT(dyndb_implementations);

}

void

dns__dyndb_shutdown(void) {

  isc_mutex_destroy(&dyndb_lock);

}

static dyndb_implementation_t *

impfind(const char *name) {

  ISC_LIST_FOREACH(dyndb_implementations, imp, link) {

    if (strcasecmp(name, imp->name) == 0) {

      return imp;

    }

  }

  return NULL;

}

static isc_result_t

load_symbol(uv_lib_t *handle, const char *filename, const char *symbol_name,

      void **symbolp) {

  void *symbol;

  int r;

  REQUIRE(handle != NULL);

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

  r = uv_dlsym(handle, symbol_name, &symbol);

  if (r != 0) {

    const char *errmsg = uv_dlerror(handle);

    if (errmsg == NULL) {

      errmsg = "returned function pointer is NULL";

    }

    isc_log_write(DNS_LOGCATEGORY_DATABASE, DNS_LOGMODULE_DYNDB,

            ISC_LOG_ERROR,

            "failed to lookup symbol %s in "

            "DynDB module '%s': %s",

            symbol_name, filename, errmsg);

    return ISC_R_FAILURE;

  }

  *symbolp = symbol;

  return ISC_R_SUCCESS;

}

static void

unload_library(dyndb_implementation_t **impp);

static isc_result_t

load_library(isc_mem_t *mctx, const char *filename, const char *instname,

       dyndb_implementation_t **impp) {

  isc_result_t result;

  dyndb_implementation_t *imp = NULL;

  dns_dyndb_version_t *version_func = NULL;

  int version;

  int r;

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

  isc_log_write(DNS_LOGCATEGORY_DATABASE, DNS_LOGMODULE_DYNDB,

          ISC_LOG_INFO, "loading DynDB instance '%s' driver '%s'",

          instname, filename);

  imp = isc_mem_get(mctx, sizeof(*imp));

  *imp = (dyndb_implementation_t){

    .name = isc_mem_strdup(mctx, instname),

  };

  isc_mem_attach(mctx, &imp->mctx);

  ISC_LINK_INIT(imp, link);

  r = uv_dlopen(filename, &imp->handle);

  if (r != 0) {

    const char *errmsg = uv_dlerror(&imp->handle);

    if (errmsg == NULL) {

      errmsg = "unknown error";

    }

    isc_log_write(DNS_LOGCATEGORY_DATABASE, DNS_LOGMODULE_DYNDB,

            ISC_LOG_ERROR,

            "failed to dlopen() DynDB instance '%s' driver "

            "'%s': %s",

            instname, filename, errmsg);

    CLEANUP(ISC_R_FAILURE);

  }

  CHECK(load_symbol(&imp->handle, filename, "dyndb_version",

        (void **)&version_func));

  version = version_func(NULL);

  if (version < (DNS_DYNDB_VERSION - DNS_DYNDB_AGE) ||

      version > DNS_DYNDB_VERSION)

  {

    isc_log_write(DNS_LOGCATEGORY_DATABASE, DNS_LOGMODULE_DYNDB,

            ISC_LOG_ERROR,

            "driver API version mismatch: %d/%d", version,

            DNS_DYNDB_VERSION);

    CLEANUP(ISC_R_FAILURE);

  }

  CHECK(load_symbol(&imp->handle, filename, "dyndb_init",

        (void **)&imp->register_func));

  CHECK(load_symbol(&imp->handle, filename, "dyndb_destroy",

        (void **)&imp->destroy_func));

  *impp = imp;

  return ISC_R_SUCCESS;

cleanup:

  isc_log_write(DNS_LOGCATEGORY_DATABASE, DNS_LOGMODULE_DYNDB,

          ISC_LOG_ERROR,

          "failed to dynamically load DynDB instance '%s' driver "

          "'%s': %s",

          instname, filename, isc_result_totext(result));

  unload_library(&imp);

  return result;

}

static void

unload_library(dyndb_implementation_t **impp) {

  dyndb_implementation_t *imp;

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

  imp = *impp;

  *impp = NULL;

  /*

   * This is a resource leak, but there is nothing we can currently do

   * about it due to how configuration loading/reloading is designed.

   */

  /* uv_dlclose(&imp->handle); */

  isc_mem_free(imp->mctx, imp->name);

  isc_mem_putanddetach(&imp->mctx, imp, sizeof(*imp));

}

isc_result_t

dns_dyndb_load(const char *libname, const char *name, const char *parameters,

         const char *file, unsigned long line, isc_mem_t *mctx,

         const dns_dyndbctx_t *dctx) {

  isc_result_t result;

  dyndb_implementation_t *implementation = NULL;

  REQUIRE(DNS_DYNDBCTX_VALID(dctx));

  REQUIRE(name != NULL);

  LOCK(&dyndb_lock);

  /* duplicate instance names are not allowed */

  if (impfind(name) != NULL) {

    CLEANUP(ISC_R_EXISTS);

  }

  CHECK(load_library(mctx, libname, name, &implementation));

  CHECK(implementation->register_func(mctx, name, parameters, file, line,

              dctx, &implementation->inst));

  ISC_LIST_APPEND(dyndb_implementations, implementation, link);

  result = ISC_R_SUCCESS;

cleanup:

  if (result != ISC_R_SUCCESS) {

    if (implementation != NULL) {

      unload_library(&implementation);

    }

  }

  UNLOCK(&dyndb_lock);

  return result;

}

void

dns_dyndb_cleanup(void) {

  dyndb_implementation_t *elem;

  dyndb_implementation_t *prev;

  LOCK(&dyndb_lock);

  elem = ISC_LIST_TAIL(dyndb_implementations);

  while (elem != NULL) {

    prev = ISC_LIST_PREV(elem, link);

    ISC_LIST_UNLINK(dyndb_implementations, elem, link);

    isc_log_write(DNS_LOGCATEGORY_DATABASE, DNS_LOGMODULE_DYNDB,

            ISC_LOG_INFO, "unloading DynDB instance '%s'",

            elem->name);

    elem->destroy_func(&elem->inst);

    ENSURE(elem->inst == NULL);

    unload_library(&elem);

    elem = prev;

  }

  UNLOCK(&dyndb_lock);

}

void

dns_dyndb_createctx(isc_mem_t *mctx, const void *hashinit, dns_view_t *view,

        dns_zonemgr_t *zmgr, dns_dyndbctx_t **dctxp) {

  dns_dyndbctx_t *dctx;

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

  dctx = isc_mem_get(mctx, sizeof(*dctx));

  *dctx = (dns_dyndbctx_t){

    .hashinit = hashinit,

  };

  if (view != NULL) {

    dns_view_attach(view, &dctx->view);

  }

  if (zmgr != NULL) {

    dns_zonemgr_attach(zmgr, &dctx->zmgr);

  }

  isc_mem_attach(mctx, &dctx->mctx);

  dctx->magic = DNS_DYNDBCTX_MAGIC;

  *dctxp = dctx;

}

void

dns_dyndb_destroyctx(dns_dyndbctx_t **dctxp) {

  dns_dyndbctx_t *dctx;

  REQUIRE(dctxp != NULL && DNS_DYNDBCTX_VALID(*dctxp));

  dctx = *dctxp;

  *dctxp = NULL;

  dctx->magic = 0;

  if (dctx->view != NULL) {

    dns_view_detach(&dctx->view);

  }

  if (dctx->zmgr != NULL) {

    dns_zonemgr_detach(&dctx->zmgr);

  }

  isc_mem_putanddetach(&dctx->mctx, dctx, sizeof(*dctx));

}