/*

 * Copyright 2001-2024 The OpenSSL Project Authors. All Rights Reserved.

 *

 * Licensed under the Apache License 2.0 (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 "internal/cryptlib.h"

#include <openssl/evp.h>

#include <openssl/lhash.h>

#include <openssl/trace.h>

#include "eng_local.h"

/* The type of the items in the table */

struct st_engine_pile {

    /* The 'nid' of this algorithm/mode */

    int nid;

    /* ENGINEs that implement this algorithm/mode. */

    STACK_OF(ENGINE) *sk;

    /* The default ENGINE to perform this algorithm/mode. */

    ENGINE *funct;

    /*

     * Zero if 'sk' is newer than the cached 'funct', non-zero otherwise

     */

    int uptodate;

};

/* The type exposed in eng_local.h */

struct st_engine_table {

    LHASH_OF(ENGINE_PILE) piles;

};                              /* ENGINE_TABLE */

typedef struct st_engine_pile_doall {

    engine_table_doall_cb *cb;

    void *arg;

} ENGINE_PILE_DOALL;

/* Global flags (ENGINE_TABLE_FLAG_***). */

static unsigned int table_flags = 0;

/* API function manipulating 'table_flags' */

unsigned int ENGINE_get_table_flags(void)

{

    return table_flags;

}

void ENGINE_set_table_flags(unsigned int flags)

{

    table_flags = flags;

}

/* Internal functions for the "piles" hash table */

static unsigned long engine_pile_hash(const ENGINE_PILE *c)

{

    return c->nid;

}

static int engine_pile_cmp(const ENGINE_PILE *a, const ENGINE_PILE *b)

{

    return a->nid - b->nid;

}

static int int_table_check(ENGINE_TABLE **t, int create)

{

    LHASH_OF(ENGINE_PILE) *lh;

    if (*t)

        return 1;

    if (!create)

        return 0;

    if ((lh = lh_ENGINE_PILE_new(engine_pile_hash, engine_pile_cmp)) == NULL)

        return 0;

    *t = (ENGINE_TABLE *)lh;

    return 1;

}

/*

 * Privately exposed (via eng_local.h) functions for adding and/or removing

 * ENGINEs from the implementation table

 */

int engine_table_register(ENGINE_TABLE **table, ENGINE_CLEANUP_CB *cleanup,

                          ENGINE *e, const int *nids, int num_nids,

                          int setdefault)

{

    int ret = 0, added = 0;

    ENGINE_PILE tmplate, *fnd;

    if (!CRYPTO_THREAD_write_lock(global_engine_lock))

        return 0;

    if (!(*table))

        added = 1;

    if (!int_table_check(table, 1))

        goto end;

    /* The cleanup callback needs to be added */

    if (added && !engine_cleanup_add_first(cleanup)) {

        lh_ENGINE_PILE_free(&(*table)->piles);

        *table = NULL;

        goto end;

    }

    while (num_nids--) {

        tmplate.nid = *nids;

        fnd = lh_ENGINE_PILE_retrieve(&(*table)->piles, &tmplate);

        if (!fnd) {

            fnd = OPENSSL_malloc(sizeof(*fnd));

            if (fnd == NULL)

                goto end;

            fnd->uptodate = 1;

            fnd->nid = *nids;

            fnd->sk = sk_ENGINE_new_null();

            if (!fnd->sk) {

                OPENSSL_free(fnd);

                goto end;

            }

            fnd->funct = NULL;

            (void)lh_ENGINE_PILE_insert(&(*table)->piles, fnd);

            if (lh_ENGINE_PILE_retrieve(&(*table)->piles, &tmplate) != fnd) {

                sk_ENGINE_free(fnd->sk);

                OPENSSL_free(fnd);

                goto end;

            }

        }

        /* A registration shouldn't add duplicate entries */

        (void)sk_ENGINE_delete_ptr(fnd->sk, e);

        /*

         * if 'setdefault', this ENGINE goes to the head of the list

         */

        if (!sk_ENGINE_push(fnd->sk, e))

            goto end;

        /* "touch" this ENGINE_PILE */

        fnd->uptodate = 0;

        if (setdefault) {

            if (!engine_unlocked_init(e)) {

                ERR_raise(ERR_LIB_ENGINE, ENGINE_R_INIT_FAILED);

                goto end;

            }

            if (fnd->funct)

                engine_unlocked_finish(fnd->funct, 0);

            fnd->funct = e;

            fnd->uptodate = 1;

        }

        nids++;

    }

    ret = 1;

 end:

    CRYPTO_THREAD_unlock(global_engine_lock);

    return ret;

}

static void int_unregister_cb(ENGINE_PILE *pile, ENGINE *e)

{

    int n;

    /* Iterate the 'c->sk' stack removing any occurrence of 'e' */

    while ((n = sk_ENGINE_find(pile->sk, e)) >= 0) {

        (void)sk_ENGINE_delete(pile->sk, n);

        pile->uptodate = 0;

    }

    if (pile->funct == e) {

        engine_unlocked_finish(e, 0);

        pile->funct = NULL;

    }

}

IMPLEMENT_LHASH_DOALL_ARG(ENGINE_PILE, ENGINE);

void engine_table_unregister(ENGINE_TABLE **table, ENGINE *e)

{

    if (!CRYPTO_THREAD_write_lock(global_engine_lock))

        /* Can't return a value. :( */

        return;

    if (int_table_check(table, 0))

        lh_ENGINE_PILE_doall_ENGINE(&(*table)->piles, int_unregister_cb, e);

    CRYPTO_THREAD_unlock(global_engine_lock);

}

static void int_cleanup_cb_doall(ENGINE_PILE *p)

{

    if (p == NULL)

        return;

    sk_ENGINE_free(p->sk);

    if (p->funct)

        engine_unlocked_finish(p->funct, 0);

    OPENSSL_free(p);

}

void engine_table_cleanup(ENGINE_TABLE **table)

{

    if (!CRYPTO_THREAD_write_lock(global_engine_lock))

        return;

    if (*table) {

        lh_ENGINE_PILE_doall(&(*table)->piles, int_cleanup_cb_doall);

        lh_ENGINE_PILE_free(&(*table)->piles);

        *table = NULL;

    }

    CRYPTO_THREAD_unlock(global_engine_lock);

}

/* return a functional reference for a given 'nid' */

ENGINE *ossl_engine_table_select(ENGINE_TABLE **table, int nid,

                                 const char *f, int l)

{

    ENGINE *ret = NULL;

    ENGINE_PILE tmplate, *fnd = NULL;

    int initres, loop = 0;

#ifndef OPENSSL_NO_AUTOLOAD_CONFIG

    /* Load the config before trying to check if engines are available */

    OPENSSL_init_crypto(OPENSSL_INIT_LOAD_CONFIG, NULL);

#endif

    if (!(*table)) {

        OSSL_TRACE3(ENGINE_TABLE,

                   "%s:%d, nid=%d, nothing registered!\n",

                   f, l, nid);

        return NULL;

    }

    if (!CRYPTO_THREAD_write_lock(global_engine_lock))

        return NULL;

    ERR_set_mark();

    /*

     * Check again inside the lock otherwise we could race against cleanup

     * operations. But don't worry about a debug printout

     */

    if (!int_table_check(table, 0))

        goto end;

    tmplate.nid = nid;

    fnd = lh_ENGINE_PILE_retrieve(&(*table)->piles, &tmplate);

    if (!fnd)

        goto end;

    if (fnd->funct && engine_unlocked_init(fnd->funct)) {

        OSSL_TRACE4(ENGINE_TABLE,

                   "%s:%d, nid=%d, using ENGINE '%s' cached\n",

                   f, l, nid, fnd->funct->id);

        ret = fnd->funct;

        goto end;

    }

    if (fnd->uptodate) {

        ret = fnd->funct;

        goto end;

    }

 trynext:

    ret = sk_ENGINE_value(fnd->sk, loop++);

    if (!ret) {

        OSSL_TRACE3(ENGINE_TABLE,

                    "%s:%d, nid=%d, "

                    "no registered implementations would initialise\n",

                    f, l, nid);

        goto end;

    }

    /* Try to initialise the ENGINE? */

    if ((ret->funct_ref > 0) || !(table_flags & ENGINE_TABLE_FLAG_NOINIT))

        initres = engine_unlocked_init(ret);

    else

        initres = 0;

    if (initres) {

        /* Update 'funct' */

        if ((fnd->funct != ret) && engine_unlocked_init(ret)) {

            /* If there was a previous default we release it. */

            if (fnd->funct)

                engine_unlocked_finish(fnd->funct, 0);

            fnd->funct = ret;

            OSSL_TRACE4(ENGINE_TABLE,

                        "%s:%d, nid=%d, setting default to '%s'\n",

                        f, l, nid, ret->id);

        }

        OSSL_TRACE4(ENGINE_TABLE,

                    "%s:%d, nid=%d, using newly initialised '%s'\n",

                    f, l, nid, ret->id);

        goto end;

    }

    goto trynext;

 end:

    /*

     * If it failed, it is unlikely to succeed again until some future

     * registrations have taken place. In all cases, we cache.

     */

    if (fnd)

        fnd->uptodate = 1;

    if (ret)

        OSSL_TRACE4(ENGINE_TABLE,

                   "%s:%d, nid=%d, caching ENGINE '%s'\n",

                   f, l, nid, ret->id);

    else

        OSSL_TRACE3(ENGINE_TABLE,

                    "%s:%d, nid=%d, caching 'no matching ENGINE'\n",

                    f, l, nid);

    CRYPTO_THREAD_unlock(global_engine_lock);

    /*

     * Whatever happened, any failed init()s are not failures in this

     * context, so clear our error state.

     */

    ERR_pop_to_mark();

    return ret;

}

/* Table enumeration */

static void int_dall(const ENGINE_PILE *pile, ENGINE_PILE_DOALL *dall)

{

    dall->cb(pile->nid, pile->sk, pile->funct, dall->arg);

}

IMPLEMENT_LHASH_DOALL_ARG_CONST(ENGINE_PILE, ENGINE_PILE_DOALL);

void engine_table_doall(ENGINE_TABLE *table, engine_table_doall_cb *cb,

                        void *arg)

{

    ENGINE_PILE_DOALL dall;

    dall.cb = cb;

    dall.arg = arg;

    if (table)

        lh_ENGINE_PILE_doall_ENGINE_PILE_DOALL(&table->piles, int_dall, &dall);

}