/*

 * Copyright 2019 The OpenSSL Project Authors. All Rights Reserved.

 * Copyright (c) 2019, Oracle and/or its affiliates.  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 <string.h>

#include <stdio.h>

#include <stdarg.h>

#include <openssl/crypto.h>

#include "internal/property.h"

#include "crypto/ctype.h"

#include <openssl/lhash.h>

#include <openssl/rand.h>

#include "internal/thread_once.h"

#include "crypto/lhash.h"

#include "crypto/sparse_array.h"

#include "property_local.h"

/*

 * The number of elements in the query cache before we initiate a flush.

 * If reducing this, also ensure the stochastic test in test/property_test.c

 * isn't likely to fail.

 */

#define IMPL_CACHE_FLUSH_THRESHOLD  500

typedef struct {

    void *method;

    int (*up_ref)(void *);

    void (*free)(void *);

} METHOD;

typedef struct {

    const OSSL_PROVIDER *provider;

    OSSL_PROPERTY_LIST *properties;

    METHOD method;

} IMPLEMENTATION;

DEFINE_STACK_OF(IMPLEMENTATION)

typedef struct {

    const char *query;

    METHOD method;

    char body[1];

} QUERY;

DEFINE_LHASH_OF(QUERY);

typedef struct {

    int nid;

    STACK_OF(IMPLEMENTATION) *impls;

    LHASH_OF(QUERY) *cache;

} ALGORITHM;

struct ossl_method_store_st {

    OPENSSL_CTX *ctx;

    size_t nelem;

    SPARSE_ARRAY_OF(ALGORITHM) *algs;

    OSSL_PROPERTY_LIST *global_properties;

    int need_flush;

    CRYPTO_RWLOCK *lock;

};

typedef struct {

    LHASH_OF(QUERY) *cache;

    size_t nelem;

    uint32_t seed;

} IMPL_CACHE_FLUSH;

DEFINE_SPARSE_ARRAY_OF(ALGORITHM);

static void ossl_method_cache_flush(OSSL_METHOD_STORE *store, int nid);

static void ossl_method_cache_flush_all(OSSL_METHOD_STORE *c);

static int ossl_method_up_ref(METHOD *method)

{

    return (*method->up_ref)(method->method);

}

static void ossl_method_free(METHOD *method)

{

    (*method->free)(method->method);

}

int ossl_property_read_lock(OSSL_METHOD_STORE *p)

{

    return p != NULL ? CRYPTO_THREAD_read_lock(p->lock) : 0;

}

int ossl_property_write_lock(OSSL_METHOD_STORE *p)

{

    return p != NULL ? CRYPTO_THREAD_write_lock(p->lock) : 0;

}

int ossl_property_unlock(OSSL_METHOD_STORE *p)

{

    return p != 0 ? CRYPTO_THREAD_unlock(p->lock) : 0;

}

static unsigned long query_hash(const QUERY *a)

{

    return OPENSSL_LH_strhash(a->query);

}

static int query_cmp(const QUERY *a, const QUERY *b)

{

    return strcmp(a->query, b->query);

}

static void impl_free(IMPLEMENTATION *impl)

{

    if (impl != NULL) {

        ossl_method_free(&impl->method);

        OPENSSL_free(impl);

    }

}

static void impl_cache_free(QUERY *elem)

{

    if (elem != NULL) {

        ossl_method_free(&elem->method);

        OPENSSL_free(elem);

    }

}

static void alg_cleanup(ossl_uintmax_t idx, ALGORITHM *a)

{

    if (a != NULL) {

        sk_IMPLEMENTATION_pop_free(a->impls, &impl_free);

        lh_QUERY_doall(a->cache, &impl_cache_free);

        lh_QUERY_free(a->cache);

        OPENSSL_free(a);

    }

}

/*

 * The OPENSSL_CTX param here allows access to underlying property data needed

 * for computation

 */

OSSL_METHOD_STORE *ossl_method_store_new(OPENSSL_CTX *ctx)

{

    OSSL_METHOD_STORE *res;

    res = OPENSSL_zalloc(sizeof(*res));

    if (res != NULL) {

        res->ctx = ctx;

        if ((res->algs = ossl_sa_ALGORITHM_new()) == NULL) {

            OPENSSL_free(res);

            return NULL;

        }

        if ((res->lock = CRYPTO_THREAD_lock_new()) == NULL) {

            ossl_sa_ALGORITHM_free(res->algs);

            OPENSSL_free(res);

            return NULL;

        }

    }

    return res;

}

void ossl_method_store_free(OSSL_METHOD_STORE *store)

{

    if (store != NULL) {

        ossl_sa_ALGORITHM_doall(store->algs, &alg_cleanup);

        ossl_sa_ALGORITHM_free(store->algs);

        ossl_property_free(store->global_properties);

        CRYPTO_THREAD_lock_free(store->lock);

        OPENSSL_free(store);

    }

}

static ALGORITHM *ossl_method_store_retrieve(OSSL_METHOD_STORE *store, int nid)

{

    return ossl_sa_ALGORITHM_get(store->algs, nid);

}

static int ossl_method_store_insert(OSSL_METHOD_STORE *store, ALGORITHM *alg)

{

        return ossl_sa_ALGORITHM_set(store->algs, alg->nid, alg);

}

int ossl_method_store_add(OSSL_METHOD_STORE *store, const OSSL_PROVIDER *prov,

                          int nid, const char *properties, void *method,

                          int (*method_up_ref)(void *),

                          void (*method_destruct)(void *))

{

    ALGORITHM *alg = NULL;

    IMPLEMENTATION *impl;

    int ret = 0;

    int i;

    if (nid <= 0 || method == NULL || store == NULL)

        return 0;

    if (properties == NULL)

        properties = "";

    /* Create new entry */

    impl = OPENSSL_malloc(sizeof(*impl));

    if (impl == NULL)

        return 0;

    impl->method.method = method;

    impl->method.up_ref = method_up_ref;

    impl->method.free = method_destruct;

    if (!ossl_method_up_ref(&impl->method)) {

        OPENSSL_free(impl);

        return 0;

    }

    impl->provider = prov;

    /*

     * Insert into the hash table if required.

     *

     * A write lock is used unconditionally because we wend our way down to the

     * property string code which isn't locking friendly.

     */

    ossl_property_write_lock(store);

    ossl_method_cache_flush(store, nid);

    if ((impl->properties = ossl_prop_defn_get(store->ctx, properties)) == NULL) {

        impl->properties = ossl_parse_property(store->ctx, properties);

        if (impl->properties == NULL)

            goto err;

        ossl_prop_defn_set(store->ctx, properties, impl->properties);

    }

    alg = ossl_method_store_retrieve(store, nid);

    if (alg == NULL) {

        if ((alg = OPENSSL_zalloc(sizeof(*alg))) == NULL

                || (alg->impls = sk_IMPLEMENTATION_new_null()) == NULL

                || (alg->cache = lh_QUERY_new(&query_hash, &query_cmp)) == NULL)

            goto err;

        alg->nid = nid;

        if (!ossl_method_store_insert(store, alg))

            goto err;

    }

    /* Push onto stack if there isn't one there already */

    for (i = 0; i < sk_IMPLEMENTATION_num(alg->impls); i++) {

        const IMPLEMENTATION *tmpimpl = sk_IMPLEMENTATION_value(alg->impls, i);

        if (tmpimpl->provider == impl->provider

            && tmpimpl->properties == impl->properties)

            break;

    }

    if (i == sk_IMPLEMENTATION_num(alg->impls)

        && sk_IMPLEMENTATION_push(alg->impls, impl))

        ret = 1;

    ossl_property_unlock(store);

    if (ret == 0)

        impl_free(impl);

    return ret;

err:

    ossl_property_unlock(store);

    alg_cleanup(0, alg);

    impl_free(impl);

    return 0;

}

int ossl_method_store_remove(OSSL_METHOD_STORE *store, int nid,

                             const void *method)

{

    ALGORITHM *alg = NULL;

    int i;

    if (nid <= 0 || method == NULL || store == NULL)

        return 0;

    ossl_property_write_lock(store);

    ossl_method_cache_flush(store, nid);

    alg = ossl_method_store_retrieve(store, nid);

    if (alg == NULL) {

        ossl_property_unlock(store);

        return 0;

    }

    /*

     * A sorting find then a delete could be faster but these stacks should be

     * relatively small, so we avoid the overhead.  Sorting could also surprise

     * users when result orderings change (even though they are not guaranteed).

     */

    for (i = 0; i < sk_IMPLEMENTATION_num(alg->impls); i++) {

        IMPLEMENTATION *impl = sk_IMPLEMENTATION_value(alg->impls, i);

        if (impl->method.method == method) {

            impl_free(impl);

            sk_IMPLEMENTATION_delete(alg->impls, i);

            ossl_property_unlock(store);

            return 1;

        }

    }

    ossl_property_unlock(store);

    return 0;

}

int ossl_method_store_fetch(OSSL_METHOD_STORE *store, int nid,

                            const char *prop_query, void **method)

{

    ALGORITHM *alg;

    IMPLEMENTATION *impl;

    OSSL_PROPERTY_LIST *pq = NULL, *p2;

    METHOD *best_method = NULL;

    int ret = 0;

    int j, best = -1, score, optional;

#ifndef FIPS_MODE

    OPENSSL_init_crypto(OPENSSL_INIT_LOAD_CONFIG, NULL);

#endif

    if (nid <= 0 || method == NULL || store == NULL)

        return 0;

    /*

     * This only needs to be a read lock, because queries never create property

     * names or value and thus don't modify any of the property string layer.

     */

    ossl_property_read_lock(store);

    alg = ossl_method_store_retrieve(store, nid);

    if (alg == NULL) {

        ossl_property_unlock(store);

        return 0;

    }

    if (prop_query == NULL) {

        if ((impl = sk_IMPLEMENTATION_value(alg->impls, 0)) != NULL) {

            best_method = &impl->method;

            ret = 1;

        }

        goto fin;

    }

    pq = ossl_parse_query(store->ctx, prop_query);

    if (pq == NULL)

        goto fin;

    if (store->global_properties != NULL) {

        p2 = ossl_property_merge(pq, store->global_properties);

        if (p2 == NULL)

            goto fin;

        ossl_property_free(pq);

        pq = p2;

    }

    optional = ossl_property_has_optional(pq);

    for (j = 0; j < sk_IMPLEMENTATION_num(alg->impls); j++) {

        impl = sk_IMPLEMENTATION_value(alg->impls, j);

        score = ossl_property_match_count(pq, impl->properties);

        if (score > best) {

            best_method = &impl->method;

            best = score;

            ret = 1;

            if (!optional)

                goto fin;

        }

    }

fin:

    if (ret && ossl_method_up_ref(best_method))

        *method = best_method->method;

    else

        ret = 0;

    ossl_property_unlock(store);

    ossl_property_free(pq);

    return ret;

}

int ossl_method_store_set_global_properties(OSSL_METHOD_STORE *store,

                                            const char *prop_query) {

    int ret = 0;

    if (store == NULL)

        return 1;

    ossl_property_write_lock(store);

    ossl_method_cache_flush_all(store);

    if (prop_query == NULL) {

        ossl_property_free(store->global_properties);

        store->global_properties = NULL;

        ossl_property_unlock(store);

        return 1;

    }

    store->global_properties = ossl_parse_query(store->ctx, prop_query);

    ret = store->global_properties != NULL;

    ossl_property_unlock(store);

    return ret;

}

static void impl_cache_flush_alg(ossl_uintmax_t idx, ALGORITHM *alg)

{

    lh_QUERY_doall(alg->cache, &impl_cache_free);

    lh_QUERY_flush(alg->cache);

}

static void ossl_method_cache_flush(OSSL_METHOD_STORE *store, int nid)

{

    ALGORITHM *alg = ossl_method_store_retrieve(store, nid);

    if (alg != NULL) {

        store->nelem -= lh_QUERY_num_items(alg->cache);

        impl_cache_flush_alg(0, alg);

    }

}

static void ossl_method_cache_flush_all(OSSL_METHOD_STORE *store)

{

    ossl_sa_ALGORITHM_doall(store->algs, &impl_cache_flush_alg);

    store->nelem = 0;

}

IMPLEMENT_LHASH_DOALL_ARG(QUERY, IMPL_CACHE_FLUSH);

/*

 * Flush an element from the query cache (perhaps).

 *

 * In order to avoid taking a write lock or using atomic operations

 * to keep accurate least recently used (LRU) or least frequently used

 * (LFU) information, the procedure used here is to stochastically

 * flush approximately half the cache.

 *

 * This procedure isn't ideal, LRU or LFU would be better.  However,

 * in normal operation, reaching a full cache would be unexpected.

 * It means that no steady state of algorithm queries has been reached.

 * That is, it is most likely an attack of some form.  A suboptimal clearance

 * strategy that doesn't degrade performance of the normal case is

 * preferable to a more refined approach that imposes a performance

 * impact.

 */

static void impl_cache_flush_cache(QUERY *c, IMPL_CACHE_FLUSH *state)

{

    uint32_t n;

    /*

     * Implement the 32 bit xorshift as suggested by George Marsaglia in:

     *      https://doi.org/10.18637/jss.v008.i14

     *

     * This is a very fast PRNG so there is no need to extract bits one at a

     * time and use the entire value each time.

     */

    n = state->seed;

    n ^= n << 13;

    n ^= n >> 17;

    n ^= n << 5;

    state->seed = n;

    if ((n & 1) != 0)

        impl_cache_free(lh_QUERY_delete(state->cache, c));

    else

        state->nelem++;

}

static void impl_cache_flush_one_alg(ossl_uintmax_t idx, ALGORITHM *alg,

                                     void *v)

{

    IMPL_CACHE_FLUSH *state = (IMPL_CACHE_FLUSH *)v;

    state->cache = alg->cache;

    lh_QUERY_doall_IMPL_CACHE_FLUSH(state->cache, &impl_cache_flush_cache,

                                    state);

}

static void ossl_method_cache_flush_some(OSSL_METHOD_STORE *store)

{

    IMPL_CACHE_FLUSH state;

    state.nelem = 0;

    if ((state.seed = OPENSSL_rdtsc()) == 0)

        state.seed = 1;

    store->need_flush = 0;

    ossl_sa_ALGORITHM_doall_arg(store->algs, &impl_cache_flush_one_alg, &state);

    store->nelem = state.nelem;

}

int ossl_method_store_cache_get(OSSL_METHOD_STORE *store, int nid,

                                const char *prop_query, void **method)

{

    ALGORITHM *alg;

    QUERY elem, *r;

    int res = 0;

    if (nid <= 0 || store == NULL)

        return 0;

    ossl_property_read_lock(store);

    alg = ossl_method_store_retrieve(store, nid);

    if (alg == NULL)

        goto err;

    elem.query = prop_query != NULL ? prop_query : "";

    r = lh_QUERY_retrieve(alg->cache, &elem);

    if (r == NULL)

        goto err;

    if (ossl_method_up_ref(&r->method)) {

        *method = r->method.method;

        res = 1;

    }

err:

    ossl_property_unlock(store);

    return res;

}

int ossl_method_store_cache_set(OSSL_METHOD_STORE *store, int nid,

                                const char *prop_query, void *method,

                                int (*method_up_ref)(void *),

                                void (*method_destruct)(void *))

{

    QUERY elem, *old, *p = NULL;

    ALGORITHM *alg;

    size_t len;

    int res = 1;

    if (nid <= 0 || store == NULL)

        return 0;

    if (prop_query == NULL)

        return 1;

    ossl_property_write_lock(store);

    if (store->need_flush)

        ossl_method_cache_flush_some(store);

    alg = ossl_method_store_retrieve(store, nid);

    if (alg == NULL)

        goto err;

    if (method == NULL) {

        elem.query = prop_query;

        if ((old = lh_QUERY_delete(alg->cache, &elem)) != NULL) {

            impl_cache_free(old);

            store->nelem--;

        }

        goto end;

    }

    p = OPENSSL_malloc(sizeof(*p) + (len = strlen(prop_query)));

    if (p != NULL) {

        p->query = p->body;

        p->method.method = method;

        p->method.up_ref = method_up_ref;

        p->method.free = method_destruct;

        if (!ossl_method_up_ref(&p->method))

            goto err;

        memcpy((char *)p->query, prop_query, len + 1);

        if ((old = lh_QUERY_insert(alg->cache, p)) != NULL) {

            impl_cache_free(old);

            goto end;

        }

        if (!lh_QUERY_error(alg->cache)) {

            if (++store->nelem >= IMPL_CACHE_FLUSH_THRESHOLD)

                store->need_flush = 1;

            goto end;

        }

        ossl_method_free(&p->method);

    }

err:

    res = 0;

    OPENSSL_free(p);

end:

    ossl_property_unlock(store);

    return res;

}