/*

 * Copyright 2001-2018 The OpenSSL Project Authors. All Rights Reserved.

 * Copyright (c) 2002, Oracle and/or its affiliates. All rights reserved

 *

 * Licensed under the OpenSSL license (the "License").  You may not use

 * this file except in compliance with the License.  You can obtain a copy

 * in the file LICENSE in the source distribution or at

 * https://www.openssl.org/source/license.html

 */

#include "eng_local.h"

/*

 * The linked-list of pointers to engine types. engine_list_head incorporates

 * an implicit structural reference but engine_list_tail does not - the

 * latter is a computational optimization and only points to something that

 * is already pointed to by its predecessor in the list (or engine_list_head

 * itself). In the same way, the use of the "prev" pointer in each ENGINE is

 * to save excessive list iteration, it doesn't correspond to an extra

 * structural reference. Hence, engine_list_head, and each non-null "next"

 * pointer account for the list itself assuming exactly 1 structural

 * reference on each list member.

 */

static ENGINE *engine_list_head = NULL;

static ENGINE *engine_list_tail = NULL;

/*

 * This cleanup function is only needed internally. If it should be called,

 * we register it with the "engine_cleanup_int()" stack to be called during

 * cleanup.

 */

static void engine_list_cleanup(void)

{

    ENGINE *iterator = engine_list_head;

    while (iterator != NULL) {

        ENGINE_remove(iterator);

        iterator = engine_list_head;

    }

    return;

}

/*

 * These static functions starting with a lower case "engine_" always take

 * place when global_engine_lock has been locked up.

 */

static int engine_list_add(ENGINE *e)

{

    int conflict = 0;

    ENGINE *iterator = NULL;

    if (e == NULL) {

        ENGINEerr(ENGINE_F_ENGINE_LIST_ADD, ERR_R_PASSED_NULL_PARAMETER);

        return 0;

    }

    iterator = engine_list_head;

    while (iterator && !conflict) {

        conflict = (strcmp(iterator->id, e->id) == 0);

        iterator = iterator->next;

    }

    if (conflict) {

        ENGINEerr(ENGINE_F_ENGINE_LIST_ADD, ENGINE_R_CONFLICTING_ENGINE_ID);

        return 0;

    }

    if (engine_list_head == NULL) {

        /* We are adding to an empty list. */

        if (engine_list_tail) {

            ENGINEerr(ENGINE_F_ENGINE_LIST_ADD, ENGINE_R_INTERNAL_LIST_ERROR);

            return 0;

        }

        engine_list_head = e;

        e->prev = NULL;

        /*

         * The first time the list allocates, we should register the cleanup.

         */

        engine_cleanup_add_last(engine_list_cleanup);

    } else {

        /* We are adding to the tail of an existing list. */

        if ((engine_list_tail == NULL) || (engine_list_tail->next != NULL)) {

            ENGINEerr(ENGINE_F_ENGINE_LIST_ADD, ENGINE_R_INTERNAL_LIST_ERROR);

            return 0;

        }

        engine_list_tail->next = e;

        e->prev = engine_list_tail;

    }

    /*

     * Having the engine in the list assumes a structural reference.

     */

    e->struct_ref++;

    engine_ref_debug(e, 0, 1);

    /* However it came to be, e is the last item in the list. */

    engine_list_tail = e;

    e->next = NULL;

    return 1;

}

static int engine_list_remove(ENGINE *e)

{

    ENGINE *iterator;

    if (e == NULL) {

        ENGINEerr(ENGINE_F_ENGINE_LIST_REMOVE, ERR_R_PASSED_NULL_PARAMETER);

        return 0;

    }

    /* We need to check that e is in our linked list! */

    iterator = engine_list_head;

    while (iterator && (iterator != e))

        iterator = iterator->next;

    if (iterator == NULL) {

        ENGINEerr(ENGINE_F_ENGINE_LIST_REMOVE,

                  ENGINE_R_ENGINE_IS_NOT_IN_LIST);

        return 0;

    }

    /* un-link e from the chain. */

    if (e->next)

        e->next->prev = e->prev;

    if (e->prev)

        e->prev->next = e->next;

    /* Correct our head/tail if necessary. */

    if (engine_list_head == e)

        engine_list_head = e->next;

    if (engine_list_tail == e)

        engine_list_tail = e->prev;

    engine_free_util(e, 0);

    return 1;

}

/* Get the first/last "ENGINE" type available. */

ENGINE *ENGINE_get_first(void)

{

    ENGINE *ret;

    if (!RUN_ONCE(&engine_lock_init, do_engine_lock_init)) {

        ENGINEerr(ENGINE_F_ENGINE_GET_FIRST, ERR_R_MALLOC_FAILURE);

        return NULL;

    }

    CRYPTO_THREAD_write_lock(global_engine_lock);

    ret = engine_list_head;

    if (ret) {

        ret->struct_ref++;

        engine_ref_debug(ret, 0, 1);

    }

    CRYPTO_THREAD_unlock(global_engine_lock);

    return ret;

}

ENGINE *ENGINE_get_last(void)

{

    ENGINE *ret;

    if (!RUN_ONCE(&engine_lock_init, do_engine_lock_init)) {

        ENGINEerr(ENGINE_F_ENGINE_GET_LAST, ERR_R_MALLOC_FAILURE);

        return NULL;

    }

    CRYPTO_THREAD_write_lock(global_engine_lock);

    ret = engine_list_tail;

    if (ret) {

        ret->struct_ref++;

        engine_ref_debug(ret, 0, 1);

    }

    CRYPTO_THREAD_unlock(global_engine_lock);

    return ret;

}

/* Iterate to the next/previous "ENGINE" type (NULL = end of the list). */

ENGINE *ENGINE_get_next(ENGINE *e)

{

    ENGINE *ret = NULL;

    if (e == NULL) {

        ENGINEerr(ENGINE_F_ENGINE_GET_NEXT, ERR_R_PASSED_NULL_PARAMETER);

        return 0;

    }

    CRYPTO_THREAD_write_lock(global_engine_lock);

    ret = e->next;

    if (ret) {

        /* Return a valid structural reference to the next ENGINE */

        ret->struct_ref++;

        engine_ref_debug(ret, 0, 1);

    }

    CRYPTO_THREAD_unlock(global_engine_lock);

    /* Release the structural reference to the previous ENGINE */

    ENGINE_free(e);

    return ret;

}

ENGINE *ENGINE_get_prev(ENGINE *e)

{

    ENGINE *ret = NULL;

    if (e == NULL) {

        ENGINEerr(ENGINE_F_ENGINE_GET_PREV, ERR_R_PASSED_NULL_PARAMETER);

        return 0;

    }

    CRYPTO_THREAD_write_lock(global_engine_lock);

    ret = e->prev;

    if (ret) {

        /* Return a valid structural reference to the next ENGINE */

        ret->struct_ref++;

        engine_ref_debug(ret, 0, 1);

    }

    CRYPTO_THREAD_unlock(global_engine_lock);

    /* Release the structural reference to the previous ENGINE */

    ENGINE_free(e);

    return ret;

}

/* Add another "ENGINE" type into the list. */

int ENGINE_add(ENGINE *e)

{

    int to_return = 1;

    if (e == NULL) {

        ENGINEerr(ENGINE_F_ENGINE_ADD, ERR_R_PASSED_NULL_PARAMETER);

        return 0;

    }

    if ((e->id == NULL) || (e->name == NULL)) {

        ENGINEerr(ENGINE_F_ENGINE_ADD, ENGINE_R_ID_OR_NAME_MISSING);

        return 0;

    }

    CRYPTO_THREAD_write_lock(global_engine_lock);

    if (!engine_list_add(e)) {

        ENGINEerr(ENGINE_F_ENGINE_ADD, ENGINE_R_INTERNAL_LIST_ERROR);

        to_return = 0;

    }

    CRYPTO_THREAD_unlock(global_engine_lock);

    return to_return;

}

/* Remove an existing "ENGINE" type from the array. */

int ENGINE_remove(ENGINE *e)

{

    int to_return = 1;

    if (e == NULL) {

        ENGINEerr(ENGINE_F_ENGINE_REMOVE, ERR_R_PASSED_NULL_PARAMETER);

        return 0;

    }

    CRYPTO_THREAD_write_lock(global_engine_lock);

    if (!engine_list_remove(e)) {

        ENGINEerr(ENGINE_F_ENGINE_REMOVE, ENGINE_R_INTERNAL_LIST_ERROR);

        to_return = 0;

    }

    CRYPTO_THREAD_unlock(global_engine_lock);

    return to_return;

}

static void engine_cpy(ENGINE *dest, const ENGINE *src)

{

    dest->id = src->id;

    dest->name = src->name;

#ifndef OPENSSL_NO_RSA

    dest->rsa_meth = src->rsa_meth;

#endif

#ifndef OPENSSL_NO_DSA

    dest->dsa_meth = src->dsa_meth;

#endif

#ifndef OPENSSL_NO_DH

    dest->dh_meth = src->dh_meth;

#endif

#ifndef OPENSSL_NO_EC

    dest->ec_meth = src->ec_meth;

#endif

    dest->rand_meth = src->rand_meth;

    dest->ciphers = src->ciphers;

    dest->digests = src->digests;

    dest->pkey_meths = src->pkey_meths;

    dest->destroy = src->destroy;

    dest->init = src->init;

    dest->finish = src->finish;

    dest->ctrl = src->ctrl;

    dest->load_privkey = src->load_privkey;

    dest->load_pubkey = src->load_pubkey;

    dest->cmd_defns = src->cmd_defns;

    dest->flags = src->flags;

}

ENGINE *ENGINE_by_id(const char *id)

{

    ENGINE *iterator;

    char *load_dir = NULL;

    if (id == NULL) {

        ENGINEerr(ENGINE_F_ENGINE_BY_ID, ERR_R_PASSED_NULL_PARAMETER);

        return NULL;

    }

    if (!RUN_ONCE(&engine_lock_init, do_engine_lock_init)) {

        ENGINEerr(ENGINE_F_ENGINE_BY_ID, ERR_R_MALLOC_FAILURE);

        return NULL;

    }

    CRYPTO_THREAD_write_lock(global_engine_lock);

    iterator = engine_list_head;

    while (iterator && (strcmp(id, iterator->id) != 0))

        iterator = iterator->next;

    if (iterator != NULL) {

        /*

         * We need to return a structural reference. If this is an ENGINE

         * type that returns copies, make a duplicate - otherwise increment

         * the existing ENGINE's reference count.

         */

        if (iterator->flags & ENGINE_FLAGS_BY_ID_COPY) {

            ENGINE *cp = ENGINE_new();

            if (cp == NULL)

                iterator = NULL;

            else {

                engine_cpy(cp, iterator);

                iterator = cp;

            }

        } else {

            iterator->struct_ref++;

            engine_ref_debug(iterator, 0, 1);

        }

    }

    CRYPTO_THREAD_unlock(global_engine_lock);

    if (iterator != NULL)

        return iterator;

    /*

     * Prevent infinite recursion if we're looking for the dynamic engine.

     */

    if (strcmp(id, "dynamic")) {

        if ((load_dir = ossl_safe_getenv("OPENSSL_ENGINES")) == NULL)

            load_dir = ENGINESDIR;

        iterator = ENGINE_by_id("dynamic");

        if (!iterator || !ENGINE_ctrl_cmd_string(iterator, "ID", id, 0) ||

            !ENGINE_ctrl_cmd_string(iterator, "DIR_LOAD", "2", 0) ||

            !ENGINE_ctrl_cmd_string(iterator, "DIR_ADD",

                                    load_dir, 0) ||

            !ENGINE_ctrl_cmd_string(iterator, "LIST_ADD", "1", 0) ||

            !ENGINE_ctrl_cmd_string(iterator, "LOAD", NULL, 0))

            goto notfound;

        return iterator;

    }

 notfound:

    ENGINE_free(iterator);

    ENGINEerr(ENGINE_F_ENGINE_BY_ID, ENGINE_R_NO_SUCH_ENGINE);

    ERR_add_error_data(2, "id=", id);

    return NULL;

    /* EEK! Experimental code ends */

}

int ENGINE_up_ref(ENGINE *e)

{

    int i;

    if (e == NULL) {

        ENGINEerr(ENGINE_F_ENGINE_UP_REF, ERR_R_PASSED_NULL_PARAMETER);

        return 0;

    }

    CRYPTO_UP_REF(&e->struct_ref, &i, global_engine_lock);

    return 1;

}