/*
 * Copyright 2019 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 <openssl/core.h>
#include <openssl/core_numbers.h>
#include <openssl/opensslv.h>
#include "internal/cryptlib.h"
#include "internal/thread_once.h"
#include "internal/provider.h"
#include "internal/refcount.h"

/*-
 * Provider Object structure
 * =========================
 */

struct provider_store_st;        /* Forward declaration */

struct ossl_provider_st {
    /* Flag bits */
    unsigned int flag_initialized:1;

    /* OpenSSL library side data */
    CRYPTO_REF_COUNT refcnt;
#ifndef HAVE_ATOMICS
    CRYPTO_RWLOCK refcnt_lock;   /* For the ref counter */
#endif
    char *name;
    DSO *module;
    OSSL_provider_init_fn *init_function;

    /* Provider side functions */
    OSSL_provider_teardown_fn *teardown;
    OSSL_provider_get_param_types_fn *get_param_types;
    OSSL_provider_get_params_fn *get_params;
};
DEFINE_STACK_OF(OSSL_PROVIDER)

static int ossl_provider_cmp(const OSSL_PROVIDER * const *a,
                             const OSSL_PROVIDER * const *b)
{
    return strcmp((*a)->name, (*b)->name);
}

/*-
 * Provider Object store
 * =====================
 *
 * The Provider Object store is a library context object, and therefore needs
 * an index.
 */

struct provider_store_st {
    STACK_OF(OSSL_PROVIDER) *providers;
    CRYPTO_RWLOCK *lock;
};
static int provider_store_index = -1;

static void provider_store_free(void *vstore)
{
    struct provider_store_st *store = vstore;

    if (store == NULL)
        return;
    sk_OSSL_PROVIDER_pop_free(store->providers, ossl_provider_free);
    CRYPTO_THREAD_lock_free(store->lock);
    OPENSSL_free(store);
}

static void *provider_store_new(void)
{
    struct provider_store_st *store = OPENSSL_zalloc(sizeof(*store));

    if (store == NULL
        || (store->providers = sk_OSSL_PROVIDER_new(ossl_provider_cmp)) == NULL
        || (store->lock = CRYPTO_THREAD_lock_new()) == NULL) {
        provider_store_free(store);
        store = NULL;
    }
    return store;
}

static const OPENSSL_CTX_METHOD provider_store_method = {
    provider_store_new,
    provider_store_free,
};

static CRYPTO_ONCE provider_store_init_flag = CRYPTO_ONCE_STATIC_INIT;
DEFINE_RUN_ONCE_STATIC(do_provider_store_init)
{
    return OPENSSL_init_crypto(0, NULL)
        && (provider_store_index =
            openssl_ctx_new_index(&provider_store_method)) != -1;
}


static struct provider_store_st *get_provider_store(OPENSSL_CTX *libctx)
{
    struct provider_store_st *store = NULL;

    if (!RUN_ONCE(&provider_store_init_flag, do_provider_store_init))
        return NULL;

    store = openssl_ctx_get_data(libctx, provider_store_index);
    if (store == NULL)
        CRYPTOerr(CRYPTO_F_GET_PROVIDER_STORE, ERR_R_INTERNAL_ERROR);
    return store;
}

/*-
 * Provider Object methods
 * =======================
 */

int ossl_provider_upref(OSSL_PROVIDER *prov)
{
    int ref = 0;

#ifndef HAVE_ATOMICS
    CRYPTO_UP_REF(&prov->refcnt, &ref, prov->refcnt_lock);
#else
    CRYPTO_UP_REF(&prov->refcnt, &ref, NULL);
#endif
    return ref;
}

/* Finder, constructor and destructor */
OSSL_PROVIDER *ossl_provider_find(OPENSSL_CTX *libctx, const char *name)
{
    struct provider_store_st *store = NULL;
    OSSL_PROVIDER *prov = NULL;

    if ((store = get_provider_store(libctx)) != NULL) {
        OSSL_PROVIDER tmpl = { 0, };
        int i;

        tmpl.name = (char *)name;
        CRYPTO_THREAD_write_lock(store->lock);
        if ((i = sk_OSSL_PROVIDER_find(store->providers, &tmpl)) == -1
            || (prov = sk_OSSL_PROVIDER_value(store->providers, i)) == NULL
            || !ossl_provider_upref(prov))
            prov = NULL;
        CRYPTO_THREAD_unlock(store->lock);
    }

    return prov;
}

OSSL_PROVIDER *ossl_provider_new(OPENSSL_CTX *libctx, const char *name,
                                 OSSL_provider_init_fn *init_function)
{
    struct provider_store_st *store = NULL;
    OSSL_PROVIDER *prov = NULL;

    if ((store = get_provider_store(libctx)) == NULL)
        return NULL;

    if ((prov = ossl_provider_find(libctx, name)) != NULL) { /* refcount +1 */
        ossl_provider_free(prov); /* refcount -1 */
        CRYPTOerr(CRYPTO_F_OSSL_PROVIDER_NEW,
                  CRYPTO_R_PROVIDER_ALREADY_EXISTS);
        ERR_add_error_data(2, "name=", name);
        return NULL;
    }

    if ((prov = OPENSSL_zalloc(sizeof(*prov))) == NULL
        || !ossl_provider_upref(prov) /* +1 One reference to be returned */
        || (prov->name = OPENSSL_strdup(name)) == NULL) {
        ossl_provider_free(prov);
        CRYPTOerr(CRYPTO_F_OSSL_PROVIDER_NEW, ERR_R_MALLOC_FAILURE);
        return NULL;
    }

    prov->init_function = init_function;

    CRYPTO_THREAD_write_lock(store->lock);
    if (!ossl_provider_upref(prov)) { /* +1 One reference for the store */
        ossl_provider_free(prov); /* -1 Reference that was to be returned */
        prov = NULL;
    } else if (sk_OSSL_PROVIDER_push(store->providers, prov) == 0) {
        ossl_provider_free(prov); /* -1 Store reference */
        ossl_provider_free(prov); /* -1 Reference that was to be returned */
        prov = NULL;
    }
    CRYPTO_THREAD_unlock(store->lock);

    if (prov == NULL)
        CRYPTOerr(CRYPTO_F_OSSL_PROVIDER_NEW, ERR_R_MALLOC_FAILURE);

    /*
     * At this point, the provider is only partially "loaded".  To be
     * fully "loaded", ossl_provider_activate() must also be called.
     */

    return prov;
}

void ossl_provider_free(OSSL_PROVIDER *prov)
{
    if (prov != NULL) {
        int ref = 0;

#ifndef HAVE_ATOMICS
        CRYPTO_DOWN_REF(&prov->refcnt, &ref, provider_lock);
#else
        CRYPTO_DOWN_REF(&prov->refcnt, &ref, NULL);
#endif

        /*
         * When the refcount drops down to one, there is only one reference,
         * the store.
         * When that happens, the provider is inactivated.
         */
        if (ref == 1 && prov->flag_initialized) {
            if (prov->teardown != NULL)
                prov->teardown();
            prov->flag_initialized = 0;
        }

        /*
         * When the refcount drops to zero, it has been taken out of
         * the store.  All we have to do here is clean it out.
         */
        if (ref == 0) {
            DSO_free(prov->module);
            OPENSSL_free(prov->name);
            OPENSSL_free(prov);
        }
    }
}

/*
 * Provider activation.
 *
 * What "activation" means depends on the provider form; for built in
 * providers (in the library or the application alike), the provider
 * can already be considered to be loaded, all that's needed is to
 * initialize it.  However, for dynamically loadable provider modules,
 * we must first load that module.
 *
 * Built in modules are distinguished from dynamically loaded modules
 * with an already assigned init function.
 */
static const OSSL_DISPATCH *core_dispatch; /* Define further down */

int ossl_provider_activate(OSSL_PROVIDER *prov)
{
    const OSSL_DISPATCH *provider_dispatch = NULL;

    if (prov->flag_initialized)
        return 1;

    /*
     * If the init function isn't set, it indicates that this provider is
     * a loadable module.
     */
    if (prov->init_function == NULL) {
        if (prov->module == NULL) {
            char *platform_module_name = NULL;
            char *module_path = NULL;
            const char *load_dir = ossl_safe_getenv("OPENSSL_MODULES");

            if ((prov->module = DSO_new()) == NULL) {
                /* DSO_new() generates an error already */
                return 0;
            }

            if (load_dir == NULL)
                load_dir = MODULESDIR;

            DSO_ctrl(prov->module, DSO_CTRL_SET_FLAGS,
                     DSO_FLAG_NAME_TRANSLATION_EXT_ONLY, NULL);
            if ((platform_module_name =
                 DSO_convert_filename(prov->module, prov->name)) == NULL
                || (module_path =
                    DSO_merge(prov->module, platform_module_name,
                              load_dir)) == NULL
                || DSO_load(prov->module, module_path, NULL,
                            DSO_FLAG_NAME_TRANSLATION_EXT_ONLY) == NULL) {
                DSO_free(prov->module);
                prov->module = NULL;
            }

            OPENSSL_free(platform_module_name);
            OPENSSL_free(module_path);
        }

        if (prov->module != NULL)
            prov->init_function = (OSSL_provider_init_fn *)
                DSO_bind_func(prov->module, "OSSL_provider_init");
    }

    if (prov->init_function == NULL
        || !prov->init_function(prov, core_dispatch, &provider_dispatch)) {
        CRYPTOerr(CRYPTO_F_OSSL_PROVIDER_ACTIVATE, ERR_R_INIT_FAIL);
        ERR_add_error_data(2, "name=", prov->name);
        DSO_free(prov->module);
        prov->module = NULL;
        return 0;
    }

    for (; provider_dispatch->function_id != 0; provider_dispatch++) {
        switch (provider_dispatch->function_id) {
        case OSSL_FUNC_PROVIDER_TEARDOWN:
            prov->teardown =
                OSSL_get_provider_teardown(provider_dispatch);
            break;
        case OSSL_FUNC_PROVIDER_GET_PARAM_TYPES:
            prov->get_param_types =
                OSSL_get_provider_get_param_types(provider_dispatch);
            break;
        case OSSL_FUNC_PROVIDER_GET_PARAMS:
            prov->get_params =
                OSSL_get_provider_get_params(provider_dispatch);
            break;
        }
    }

    /* With this flag set, this provider has become fully "loaded". */
    prov->flag_initialized = 1;

    return 1;
}

/* Getters of Provider Object data */
const char *ossl_provider_name(OSSL_PROVIDER *prov)
{
    return prov->name;
}

const DSO *ossl_provider_dso(OSSL_PROVIDER *prov)
{
    return prov->module;
}

const char *ossl_provider_module_name(OSSL_PROVIDER *prov)
{
    return DSO_get_filename(prov->module);
}

const char *ossl_provider_module_path(OSSL_PROVIDER *prov)
{
    /* FIXME: Ensure it's a full path */
    return DSO_get_filename(prov->module);
}

/* Wrappers around calls to the provider */
void ossl_provider_teardown(const OSSL_PROVIDER *prov)
{
    if (prov->teardown != NULL)
        prov->teardown();
}

const OSSL_ITEM *ossl_provider_get_param_types(const OSSL_PROVIDER *prov)
{
    return prov->get_param_types == NULL ? NULL : prov->get_param_types(prov);
}

int ossl_provider_get_params(const OSSL_PROVIDER *prov,
                             const OSSL_PARAM params[])
{
    return prov->get_params == NULL ? 0 : prov->get_params(prov, params);
}

/*-
 * Core functions for the provider
 * ===============================
 *
 * This is the set of functions that the core makes available to the provider
 */

/*
 * This returns a list of Provider Object parameters with their types, for
 * discovery.  We do not expect that many providers will use this, but one
 * never knows.
 */
static const OSSL_ITEM param_types[] = {
    { OSSL_PARAM_UTF8_STRING_PTR, "openssl-version" },
    { OSSL_PARAM_UTF8_STRING_PTR, "provider-name" },
    { 0, NULL }
};

static const OSSL_ITEM *core_get_param_types(const OSSL_PROVIDER *prov)
{
    return param_types;
}

static int core_get_params(const OSSL_PROVIDER *prov, const OSSL_PARAM params[])
{
    int i;

    for (i = 0; params[i].key != NULL; i++) {
        if (strcmp(params[i].key, "openssl-version") == 0) {
            *(void **)params[i].data = OPENSSL_VERSION_STR;
            if (params[i].return_size)
                *params[i].return_size = sizeof(OPENSSL_VERSION_STR);
        } else if (strcmp(params[i].key, "provider-name") == 0) {
            *(void **)params[i].data = prov->name;
            if (params[i].return_size)
                *params[i].return_size = strlen(prov->name) + 1;
        }
    }

    return 1;
}

static const OSSL_DISPATCH core_dispatch_[] = {
    { OSSL_FUNC_CORE_GET_PARAM_TYPES, (void (*)(void))core_get_param_types },
    { OSSL_FUNC_CORE_GET_PARAMS, (void (*)(void))core_get_params },
    { 0, NULL }
};
static const OSSL_DISPATCH *core_dispatch = core_dispatch_;