/*
 * 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 <stddef.h>
#include <openssl/types.h>
#include <openssl/evp.h>
#include <openssl/core.h>
#include "internal/cryptlib.h"
#include "internal/thread_once.h"
#include "internal/property.h"
#include "internal/core.h"
#include "internal/provider.h"
#include "internal/namemap.h"
#include "crypto/evp.h"    /* evp_local.h needs it */
#include "evp_local.h"

static void default_method_store_free(void *vstore)
{
    ossl_method_store_free(vstore);
}

static void *default_method_store_new(OPENSSL_CTX *ctx)
{
    return ossl_method_store_new(ctx);
}


static const OPENSSL_CTX_METHOD default_method_store_method = {
    default_method_store_new,
    default_method_store_free,
};

/* Data to be passed through ossl_method_construct() */
struct method_data_st {
    OPENSSL_CTX *libctx;
    OSSL_METHOD_CONSTRUCT_METHOD *mcm;
    int operation_id;            /* For get_method_from_store() */
    int name_id;                 /* For get_method_from_store() */
    const char *name;            /* For get_method_from_store() */
    const char *propquery;       /* For get_method_from_store() */
    void *(*method_from_dispatch)(int name_id, const OSSL_DISPATCH *,
                                  OSSL_PROVIDER *, void *);
    void *method_data;
    int (*refcnt_up_method)(void *method);
    void (*destruct_method)(void *method);
};

/*
 * Generic routines to fetch / create EVP methods with ossl_method_construct()
 */
static void *alloc_tmp_method_store(OPENSSL_CTX *ctx)
{
    return ossl_method_store_new(ctx);
}

 static void dealloc_tmp_method_store(void *store)
{
    if (store != NULL)
        ossl_method_store_free(store);
}

static OSSL_METHOD_STORE *get_default_method_store(OPENSSL_CTX *libctx)
{
    return openssl_ctx_get_data(libctx, OPENSSL_CTX_DEFAULT_METHOD_STORE_INDEX,
                                &default_method_store_method);
}

/*
 * To identity the method in the method store, we mix the name identity
 * with the operation identity, with the assumption that we don't have
 * more than 2^24 names or more than 2^8 operation types.
 *
 * The resulting identity is a 32-bit integer, composed like this:
 *
 * +---------24 bits--------+-8 bits-+
 * |      name identity     | op id  |
 * +------------------------+--------+
 */
static uint32_t method_id(unsigned int operation_id, int name_id)
{
    if (!ossl_assert(name_id < (1 << 24) || operation_id < (1 << 8))
        || !ossl_assert(name_id > 0 && operation_id > 0))
        return 0;
    return ((name_id << 8) & 0xFFFFFF00) | (operation_id & 0x000000FF);
}

static void *get_method_from_store(OPENSSL_CTX *libctx, void *store,
                                   void *data)
{
    struct method_data_st *methdata = data;
    void *method = NULL;
    int name_id;
    uint32_t meth_id;

    /*
     * get_method_from_store() is only called to try and get the method
     * that evp_generic_fetch() is asking for, and the operation id as
     * well as the name or name id are passed via methdata.
     */
    if ((name_id = methdata->name_id) == 0) {
        OSSL_NAMEMAP *namemap = ossl_namemap_stored(libctx);

        if (namemap == 0)
            return NULL;
        name_id = ossl_namemap_name2num(namemap, methdata->name);
    }

    if (name_id == 0
        || (meth_id = method_id(methdata->operation_id, name_id)) == 0)
        return NULL;

    if (store == NULL
        && (store = get_default_method_store(libctx)) == NULL)
        return NULL;

    (void)ossl_method_store_fetch(store, meth_id, methdata->propquery,
                                  &method);

    if (method != NULL
        && !methdata->refcnt_up_method(method)) {
        method = NULL;
    }
    return method;
}

static int put_method_in_store(OPENSSL_CTX *libctx, void *store,
                               void *method, const OSSL_PROVIDER *prov,
                               int operation_id, const char *name,
                               const char *propdef, void *data)
{
    struct method_data_st *methdata = data;
    OSSL_NAMEMAP *namemap;
    int name_id;
    uint32_t meth_id;

    /*
     * put_method_in_store() is only called with a method that was
     * successfully created by construct_method() below, which means
     * the name should already be stored in the namemap, so just use it.
     */
    if ((namemap = ossl_namemap_stored(libctx)) == NULL
        || (name_id = ossl_namemap_name2num(namemap, name)) == 0
        || (meth_id = method_id(operation_id, name_id)) == 0)
        return 0;

    if (store == NULL
        && (store = get_default_method_store(libctx)) == NULL)
        return 0;

    return ossl_method_store_add(store, prov, meth_id, propdef, method,
                                 methdata->refcnt_up_method,
                                 methdata->destruct_method);
}

/*
 * The core fetching functionality passes the name of the implementation.
 * This function is responsible to getting an identity number for it.
 */
static void *construct_method(const char *name, const OSSL_DISPATCH *fns,
                              OSSL_PROVIDER *prov, void *data)
{
    /*
     * This function is only called if get_method_from_store() returned
     * NULL, so it's safe to say that of all the spots to create a new
     * namemap entry, this is it.  Should the name already exist there, we
     * know that ossl_namemap_add() will return its corresponding number.
     *
     * TODO(3.0): If this function gets an array of names instead of just
     * one, we need to check through all the names to see if at least one
     * of them has an associated number, and use that.  If several names
     * have associated numbers that differ from each other, it's an error.
     */
    struct method_data_st *methdata = data;
    OPENSSL_CTX *libctx = ossl_provider_library_context(prov);
    OSSL_NAMEMAP *namemap = ossl_namemap_stored(libctx);
    int name_id = ossl_namemap_add(namemap, 0, name);

    return methdata->method_from_dispatch(name_id, fns, prov,
                                          methdata->method_data);
}

static void destruct_method(void *method, void *data)
{
    struct method_data_st *methdata = data;

    methdata->destruct_method(method);
}

static void *inner_generic_fetch(OPENSSL_CTX *libctx, int operation_id,
                                 int name_id, const char *name,
                                 const char *properties,
                                 void *(*new_method)(int name_id,
                                                     const OSSL_DISPATCH *fns,
                                                     OSSL_PROVIDER *prov,
                                                     void *method_data),
                                 void *method_data,
                                 int (*up_ref_method)(void *),
                                 void (*free_method)(void *))
{
    OSSL_METHOD_STORE *store = get_default_method_store(libctx);
    OSSL_NAMEMAP *namemap = ossl_namemap_stored(libctx);
    uint32_t meth_id = 0;
    void *method = NULL;

    if (store == NULL || namemap == NULL)
        return NULL;

    /*
     * If there's ever an operation_id == 0 passed, we have an internal
     * programming error.
     */
    if (!ossl_assert(operation_id > 0))
        return NULL;

    /*
     * If we have been passed neither a name_id or a name, we have an
     * internal programming error.
     */
    if (!ossl_assert(name_id != 0 || name != NULL))
        return NULL;

    /* If we haven't received a name id yet, try to get one for the name */
    if (name_id == 0)
        name_id = ossl_namemap_name2num(namemap, name);

    /*
     * If we have a name id, calculate a method id with method_id().
     *
     * method_id returns 0 if we have too many operations (more than
     * about 2^8) or too many names (more than about 2^24).  In that
     * case, we can't create any new method.
     */
    if (name_id != 0 && (meth_id = method_id(operation_id, name_id)) == 0)
        return NULL;

    if (meth_id == 0
        || !ossl_method_store_cache_get(store, meth_id, properties, &method)) {
        OSSL_METHOD_CONSTRUCT_METHOD mcm = {
            alloc_tmp_method_store,
            dealloc_tmp_method_store,
            get_method_from_store,
            put_method_in_store,
            construct_method,
            destruct_method
        };
        struct method_data_st mcmdata;

        mcmdata.mcm = &mcm;
        mcmdata.libctx = libctx;
        mcmdata.operation_id = operation_id;
        mcmdata.name_id = name_id;
        mcmdata.name = name;
        mcmdata.propquery = properties;
        mcmdata.method_from_dispatch = new_method;
        mcmdata.destruct_method = free_method;
        mcmdata.refcnt_up_method = up_ref_method;
        mcmdata.destruct_method = free_method;
        mcmdata.method_data = method_data;
        if ((method = ossl_method_construct(libctx, operation_id,
                                            0 /* !force_cache */,
                                            &mcm, &mcmdata)) != NULL) {
            /*
             * If construction did create a method for us, we know that
             * there is a correct name_id and methodid, since those have
             * already been calculated in get_method_from_store() and
             * put_method_in_store() above.
             */
            if (name_id == 0)
                name_id = ossl_namemap_name2num(namemap, name);
            meth_id = method_id(operation_id, name_id);
            ossl_method_store_cache_set(store, meth_id, properties, method);
        }
    } else {
        up_ref_method(method);
    }

    return method;
}

void *evp_generic_fetch(OPENSSL_CTX *libctx, int operation_id,
                        const char *name, const char *properties,
                        void *(*new_method)(int name_id,
                                            const OSSL_DISPATCH *fns,
                                            OSSL_PROVIDER *prov,
                                            void *method_data),
                        void *method_data,
                        int (*up_ref_method)(void *),
                        void (*free_method)(void *))
{
    return inner_generic_fetch(libctx,
                               operation_id, 0, name, properties,
                               new_method, method_data,
                               up_ref_method, free_method);
}

/*
 * evp_generic_fetch_by_number() is special, and only returns methods for
 * already known names, i.e. it refuses to work if no name_id can be found
 * (it's considered an internal programming error).
 * This is meant to be used when one method needs to fetch an associated
 * other method.
 */
void *evp_generic_fetch_by_number(OPENSSL_CTX *libctx, int operation_id,
                                  int name_id, const char *properties,
                                  void *(*new_method)(int name_id,
                                                      const OSSL_DISPATCH *fns,
                                                      OSSL_PROVIDER *prov,
                                                      void *method_data),
                                  void *method_data,
                                  int (*up_ref_method)(void *),
                                  void (*free_method)(void *))
{
    return inner_generic_fetch(libctx,
                               operation_id, name_id, NULL, properties,
                               new_method, method_data,
                               up_ref_method, free_method);
}

int EVP_set_default_properties(OPENSSL_CTX *libctx, const char *propq)
{
    OSSL_METHOD_STORE *store = get_default_method_store(libctx);

    if (store != NULL)
        return ossl_method_store_set_global_properties(store, propq);
    EVPerr(EVP_F_EVP_SET_DEFAULT_PROPERTIES, ERR_R_INTERNAL_ERROR);
    return 0;
}

struct do_all_data_st {
    void (*user_fn)(void *method, void *arg);
    void *user_arg;
    void *(*new_method)(const int name_id, const OSSL_DISPATCH *fns,
                        OSSL_PROVIDER *prov, void *method_data);
    void (*free_method)(void *);
};

static void do_one(OSSL_PROVIDER *provider, const OSSL_ALGORITHM *algo,
                   int no_store, void *vdata)
{
    struct do_all_data_st *data = vdata;
    OPENSSL_CTX *libctx = ossl_provider_library_context(provider);
    OSSL_NAMEMAP *namemap = ossl_namemap_stored(libctx);
    int name_id = ossl_namemap_add(namemap, 0, algo->algorithm_name);
    void *method = NULL;

    if (name_id != 0)
        method = data->new_method(name_id, algo->implementation, provider,
                                  NULL);

    if (method != NULL) {
        data->user_fn(method, data->user_arg);
        data->free_method(method);
    }
}

void evp_generic_do_all(OPENSSL_CTX *libctx, int operation_id,
                        void (*user_fn)(void *method, void *arg),
                        void *user_arg,
                        void *(*new_method)(int name_id,
                                            const OSSL_DISPATCH *fns,
                                            OSSL_PROVIDER *prov,
                                            void *method_data),
                        void *method_data,
                        void (*free_method)(void *))
{
    struct do_all_data_st data;

    data.new_method = new_method;
    data.free_method = free_method;
    data.user_fn = user_fn;
    data.user_arg = user_arg;
    ossl_algorithm_do_all(libctx, operation_id, method_data, do_one, &data);
}

const char *evp_first_name(OSSL_PROVIDER *prov, int name_id)
{
    OPENSSL_CTX *libctx = ossl_provider_library_context(prov);
    OSSL_NAMEMAP *namemap = ossl_namemap_stored(libctx);

    return ossl_namemap_num2name(namemap, name_id, 0);
}

int evp_is_a(OSSL_PROVIDER *prov, int number, const char *name)
{
    OPENSSL_CTX *libctx = ossl_provider_library_context(prov);
    OSSL_NAMEMAP *namemap = ossl_namemap_stored(libctx);

    return ossl_namemap_name2num(namemap, name) == number;
}

void evp_doall_names(OSSL_PROVIDER *prov, int number,
                     void (*fn)(const char *name, void *data),
                     void *data)
{
    OPENSSL_CTX *libctx = ossl_provider_library_context(prov);
    OSSL_NAMEMAP *namemap = ossl_namemap_stored(libctx);

    ossl_namemap_doall_names(namemap, number, fn, data);
}
