/* crypto/engine/eng_list.c */
/*
 * Written by Geoff Thorpe (geoff@geoffthorpe.net) for the OpenSSL project
 * 2000.
 */
/* ====================================================================
 * Copyright (c) 1999-2018 The OpenSSL Project.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. All advertising materials mentioning features or use of this
 *    software must display the following acknowledgment:
 *    "This product includes software developed by the OpenSSL Project
 *    for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)"
 *
 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
 *    endorse or promote products derived from this software without
 *    prior written permission. For written permission, please contact
 *    licensing@OpenSSL.org.
 *
 * 5. Products derived from this software may not be called "OpenSSL"
 *    nor may "OpenSSL" appear in their names without prior written
 *    permission of the OpenSSL Project.
 *
 * 6. Redistributions of any form whatsoever must retain the following
 *    acknowledgment:
 *    "This product includes software developed by the OpenSSL Project
 *    for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)"
 *
 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 * OF THE POSSIBILITY OF SUCH DAMAGE.
 * ====================================================================
 *
 * This product includes cryptographic software written by Eric Young
 * (eay@cryptsoft.com).  This product includes software written by Tim
 * Hudson (tjh@cryptsoft.com).
 *
 */
/* ====================================================================
 * Copyright 2002 Sun Microsystems, Inc. ALL RIGHTS RESERVED.
 * ECDH support in OpenSSL originally developed by
 * SUN MICROSYSTEMS, INC., and contributed to the OpenSSL project.
 */

#include "cryptlib.h"
#include "eng_int.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 niceity 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()" 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 CRYPTO_LOCK_ENGINE 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;

    CRYPTO_w_lock(CRYPTO_LOCK_ENGINE);
    ret = engine_list_head;
    if (ret) {
        ret->struct_ref++;
        engine_ref_debug(ret, 0, 1)
    }
    CRYPTO_w_unlock(CRYPTO_LOCK_ENGINE);
    return ret;
}

ENGINE *ENGINE_get_last(void)
{
    ENGINE *ret;

    CRYPTO_w_lock(CRYPTO_LOCK_ENGINE);
    ret = engine_list_tail;
    if (ret) {
        ret->struct_ref++;
        engine_ref_debug(ret, 0, 1)
    }
    CRYPTO_w_unlock(CRYPTO_LOCK_ENGINE);
    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_w_lock(CRYPTO_LOCK_ENGINE);
    ret = e->next;
    if (ret) {
        /* Return a valid structural refernce to the next ENGINE */
        ret->struct_ref++;
        engine_ref_debug(ret, 0, 1)
    }
    CRYPTO_w_unlock(CRYPTO_LOCK_ENGINE);
    /* 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_w_lock(CRYPTO_LOCK_ENGINE);
    ret = e->prev;
    if (ret) {
        /* Return a valid structural reference to the next ENGINE */
        ret->struct_ref++;
        engine_ref_debug(ret, 0, 1)
    }
    CRYPTO_w_unlock(CRYPTO_LOCK_ENGINE);
    /* 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_w_lock(CRYPTO_LOCK_ENGINE);
    if (!engine_list_add(e)) {
        ENGINEerr(ENGINE_F_ENGINE_ADD, ENGINE_R_INTERNAL_LIST_ERROR);
        to_return = 0;
    }
    CRYPTO_w_unlock(CRYPTO_LOCK_ENGINE);
    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_w_lock(CRYPTO_LOCK_ENGINE);
    if (!engine_list_remove(e)) {
        ENGINEerr(ENGINE_F_ENGINE_REMOVE, ENGINE_R_INTERNAL_LIST_ERROR);
        to_return = 0;
    }
    CRYPTO_w_unlock(CRYPTO_LOCK_ENGINE);
    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_ECDH
    dest->ecdh_meth = src->ecdh_meth;
#endif
#ifndef OPENSSL_NO_ECDSA
    dest->ecdsa_meth = src->ecdsa_meth;
#endif
    dest->rand_meth = src->rand_meth;
    dest->store_meth = src->store_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;
    }
    CRYPTO_w_lock(CRYPTO_LOCK_ENGINE);
    iterator = engine_list_head;
    while (iterator && (strcmp(id, iterator->id) != 0))
        iterator = iterator->next;
    if (iterator) {
        /*
         * 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)
                iterator = NULL;
            else {
                engine_cpy(cp, iterator);
                iterator = cp;
            }
        } else {
            iterator->struct_ref++;
            engine_ref_debug(iterator, 0, 1)
        }
    }
    CRYPTO_w_unlock(CRYPTO_LOCK_ENGINE);
#if 0
    if (iterator == NULL) {
        ENGINEerr(ENGINE_F_ENGINE_BY_ID, ENGINE_R_NO_SUCH_ENGINE);
        ERR_add_error_data(2, "id=", id);
    }
    return iterator;
#else
    /* EEK! Experimental code starts */
    if (iterator)
        return iterator;
    /*
     * Prevent infinite recusrion if we're looking for the dynamic engine.
     */
    if (strcmp(id, "dynamic")) {
# ifdef OPENSSL_SYS_VMS
        if ((load_dir = ossl_safe_getenv("OPENSSL_ENGINES")) == 0)
            load_dir = "SSLROOT:[ENGINES]";
# else
        if ((load_dir = ossl_safe_getenv("OPENSSL_ENGINES")) == 0)
            load_dir = ENGINESDIR;
# endif
        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 */
#endif
}

int ENGINE_up_ref(ENGINE *e)
{
    if (e == NULL) {
        ENGINEerr(ENGINE_F_ENGINE_UP_REF, ERR_R_PASSED_NULL_PARAMETER);
        return 0;
    }
    CRYPTO_add(&e->struct_ref, 1, CRYPTO_LOCK_ENGINE);
    return 1;
}
