/*
 * Copyright 2020 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 <stdio.h>
#include <stdlib.h>
#include <openssl/objects.h>
#include <openssl/evp.h>
#include "internal/cryptlib.h"
#include "crypto/evp.h"
#include "internal/provider.h"
#include "evp_local.h"

static int evp_kem_init(EVP_PKEY_CTX *ctx, int operation)
{
    int ret = 0;
    EVP_KEM *kem = NULL;
    EVP_KEYMGMT *tmp_keymgmt = NULL;
    void *provkey = NULL;
    const char *supported_kem = NULL;

    if (ctx == NULL || ctx->keytype == NULL) {
        ERR_raise(ERR_LIB_EVP, EVP_R_INITIALIZATION_ERROR);
        return 0;
    }

    evp_pkey_ctx_free_old_ops(ctx);
    ctx->operation = operation;

    /*
     * Ensure that the key is provided, either natively, or as a cached export.
     */
    tmp_keymgmt = ctx->keymgmt;
    provkey = evp_pkey_export_to_provider(ctx->pkey, ctx->libctx,
                                          &tmp_keymgmt, ctx->propquery);
    if (provkey == NULL
        || !EVP_KEYMGMT_up_ref(tmp_keymgmt)) {
        ERR_raise(ERR_LIB_EVP, EVP_R_INITIALIZATION_ERROR);
        goto err;
    }
    EVP_KEYMGMT_free(ctx->keymgmt);
    ctx->keymgmt = tmp_keymgmt;

    if (ctx->keymgmt->query_operation_name != NULL)
        supported_kem = ctx->keymgmt->query_operation_name(OSSL_OP_KEM);

    /*
     * If we didn't get a supported kem, assume there is one with the
     * same name as the key type.
     */
    if (supported_kem == NULL)
        supported_kem = ctx->keytype;

    kem = EVP_KEM_fetch(ctx->libctx, supported_kem, ctx->propquery);
    if (kem == NULL
        || (EVP_KEYMGMT_provider(ctx->keymgmt) != EVP_KEM_provider(kem))) {
        ERR_raise(ERR_LIB_EVP, EVP_R_OPERATION_NOT_SUPPORTED_FOR_THIS_KEYTYPE);
        ret = -2;
        goto err;
    }

    ctx->op.encap.kem = kem;
    ctx->op.encap.kemprovctx = kem->newctx(ossl_provider_ctx(kem->prov));
    if (ctx->op.encap.kemprovctx == NULL) {
        /* The provider key can stay in the cache */
        ERR_raise(ERR_LIB_EVP, EVP_R_INITIALIZATION_ERROR);
        goto err;
    }

    switch (operation) {
    case EVP_PKEY_OP_ENCAPSULATE:
        if (kem->encapsulate_init == NULL) {
            ERR_raise(ERR_LIB_EVP, EVP_R_OPERATION_NOT_SUPPORTED_FOR_THIS_KEYTYPE);
            ret = -2;
            goto err;
        }
        ret = kem->encapsulate_init(ctx->op.encap.kemprovctx, provkey);
        break;
    case EVP_PKEY_OP_DECAPSULATE:
        if (kem->decapsulate_init == NULL) {
            ERR_raise(ERR_LIB_EVP, EVP_R_OPERATION_NOT_SUPPORTED_FOR_THIS_KEYTYPE);
            ret = -2;
            goto err;
        }
        ret = kem->decapsulate_init(ctx->op.encap.kemprovctx, provkey);
        break;
    default:
        ERR_raise(ERR_LIB_EVP, EVP_R_INITIALIZATION_ERROR);
        goto err;
    }

    if (ret > 0)
        return 1;
 err:
    if (ret <= 0) {
        evp_pkey_ctx_free_old_ops(ctx);
        ctx->operation = EVP_PKEY_OP_UNDEFINED;
    }
    return ret;
}

int EVP_PKEY_encapsulate_init(EVP_PKEY_CTX *ctx)
{
    return evp_kem_init(ctx, EVP_PKEY_OP_ENCAPSULATE);
}

int EVP_PKEY_encapsulate(EVP_PKEY_CTX *ctx,
                         unsigned char *out, size_t *outlen,
                         unsigned char *secret, size_t *secretlen)
{
    if (ctx == NULL)
        return 0;

    if (ctx->operation != EVP_PKEY_OP_ENCAPSULATE) {
        EVPerr(0, EVP_R_OPERATON_NOT_INITIALIZED);
        return -1;
    }

    if (ctx->op.encap.kemprovctx == NULL) {
        EVPerr(0, EVP_R_OPERATION_NOT_SUPPORTED_FOR_THIS_KEYTYPE);
        return -2;
    }

    if (out != NULL && secret == NULL)
        return 0;

    return ctx->op.encap.kem->encapsulate(ctx->op.encap.kemprovctx,
                                          out, outlen, secret, secretlen);
}

int EVP_PKEY_decapsulate_init(EVP_PKEY_CTX *ctx)
{
    return evp_kem_init(ctx, EVP_PKEY_OP_DECAPSULATE);
}

int EVP_PKEY_decapsulate(EVP_PKEY_CTX *ctx,
                         unsigned char *secret, size_t *secretlen,
                         const unsigned char *in, size_t inlen)
{
    if (ctx == NULL
        || (in == NULL || inlen == 0)
        || (secret == NULL && secretlen == NULL))
        return 0;

    if (ctx->operation != EVP_PKEY_OP_DECAPSULATE) {
        EVPerr(0, EVP_R_OPERATON_NOT_INITIALIZED);
        return -1;
    }

    if (ctx->op.encap.kemprovctx == NULL) {
        EVPerr(0, EVP_R_OPERATION_NOT_SUPPORTED_FOR_THIS_KEYTYPE);
        return -2;
    }
    return ctx->op.encap.kem->decapsulate(ctx->op.encap.kemprovctx,
                                          secret, secretlen, in, inlen);
}

static EVP_KEM *evp_kem_new(OSSL_PROVIDER *prov)
{
    EVP_KEM *kem = OPENSSL_zalloc(sizeof(EVP_KEM));

    if (kem == NULL) {
        ERR_raise(ERR_LIB_EVP, ERR_R_MALLOC_FAILURE);
        return NULL;
    }

    kem->lock = CRYPTO_THREAD_lock_new();
    if (kem->lock == NULL) {
        ERR_raise(ERR_LIB_EVP, ERR_R_MALLOC_FAILURE);
        OPENSSL_free(kem);
        return NULL;
    }
    kem->prov = prov;
    ossl_provider_up_ref(prov);
    kem->refcnt = 1;

    return kem;
}

static void *evp_kem_from_dispatch(int name_id, const OSSL_DISPATCH *fns,
                                   OSSL_PROVIDER *prov)
{
    EVP_KEM *kem = NULL;
    int ctxfncnt = 0, encfncnt = 0, decfncnt = 0;
    int gparamfncnt = 0, sparamfncnt = 0;

    if ((kem = evp_kem_new(prov)) == NULL) {
        ERR_raise(ERR_LIB_EVP, ERR_R_MALLOC_FAILURE);
        goto err;
    }

    kem->name_id = name_id;

    for (; fns->function_id != 0; fns++) {
        switch (fns->function_id) {
        case OSSL_FUNC_KEM_NEWCTX:
            if (kem->newctx != NULL)
                break;
            kem->newctx = OSSL_FUNC_kem_newctx(fns);
            ctxfncnt++;
            break;
        case OSSL_FUNC_KEM_ENCAPSULATE_INIT:
            if (kem->encapsulate_init != NULL)
                break;
            kem->encapsulate_init = OSSL_FUNC_kem_encapsulate_init(fns);
            encfncnt++;
            break;
        case OSSL_FUNC_KEM_ENCAPSULATE:
            if (kem->encapsulate != NULL)
                break;
            kem->encapsulate = OSSL_FUNC_kem_encapsulate(fns);
            encfncnt++;
            break;
        case OSSL_FUNC_KEM_DECAPSULATE_INIT:
            if (kem->decapsulate_init != NULL)
                break;
            kem->decapsulate_init = OSSL_FUNC_kem_decapsulate_init(fns);
            decfncnt++;
            break;
        case OSSL_FUNC_KEM_DECAPSULATE:
            if (kem->decapsulate != NULL)
                break;
            kem->decapsulate = OSSL_FUNC_kem_decapsulate(fns);
            decfncnt++;
            break;
        case OSSL_FUNC_KEM_FREECTX:
            if (kem->freectx != NULL)
                break;
            kem->freectx = OSSL_FUNC_kem_freectx(fns);
            ctxfncnt++;
            break;
        case OSSL_FUNC_KEM_DUPCTX:
            if (kem->dupctx != NULL)
                break;
            kem->dupctx = OSSL_FUNC_kem_dupctx(fns);
            break;
        case OSSL_FUNC_KEM_GET_CTX_PARAMS:
            if (kem->get_ctx_params != NULL)
                break;
            kem->get_ctx_params
                = OSSL_FUNC_kem_get_ctx_params(fns);
            gparamfncnt++;
            break;
        case OSSL_FUNC_KEM_GETTABLE_CTX_PARAMS:
            if (kem->gettable_ctx_params != NULL)
                break;
            kem->gettable_ctx_params
                = OSSL_FUNC_kem_gettable_ctx_params(fns);
            gparamfncnt++;
            break;
        case OSSL_FUNC_KEM_SET_CTX_PARAMS:
            if (kem->set_ctx_params != NULL)
                break;
            kem->set_ctx_params
                = OSSL_FUNC_kem_set_ctx_params(fns);
            sparamfncnt++;
            break;
        case OSSL_FUNC_KEM_SETTABLE_CTX_PARAMS:
            if (kem->settable_ctx_params != NULL)
                break;
            kem->settable_ctx_params
                = OSSL_FUNC_kem_settable_ctx_params(fns);
            sparamfncnt++;
            break;
        }
    }
    if (ctxfncnt != 2
        || (encfncnt != 0 && encfncnt != 2)
        || (decfncnt != 0 && decfncnt != 2)
        || (encfncnt != 2 && decfncnt != 2)
        || (gparamfncnt != 0 && gparamfncnt != 2)
        || (sparamfncnt != 0 && sparamfncnt != 2)) {
        /*
         * In order to be a consistent set of functions we must have at least
         * a set of context functions (newctx and freectx) as well as a pair of
         * "kem" functions: (encapsulate_init, encapsulate) or
         * (decapsulate_init, decapsulate). set_ctx_params and settable_ctx_params are
         * optional, but if one of them is present then the other one must also
         * be present. The same applies to get_ctx_params and
         * gettable_ctx_params. The dupctx function is optional.
         */
        ERR_raise(ERR_LIB_EVP, EVP_R_INVALID_PROVIDER_FUNCTIONS);
        goto err;
    }

    return kem;
 err:
    EVP_KEM_free(kem);
    return NULL;
}

void EVP_KEM_free(EVP_KEM *kem)
{
    if (kem != NULL) {
        int i;

        CRYPTO_DOWN_REF(&kem->refcnt, &i, kem->lock);
        if (i > 0)
            return;
        ossl_provider_free(kem->prov);
        CRYPTO_THREAD_lock_free(kem->lock);
        OPENSSL_free(kem);
    }
}

int EVP_KEM_up_ref(EVP_KEM *kem)
{
    int ref = 0;

    CRYPTO_UP_REF(&kem->refcnt, &ref, kem->lock);
    return 1;
}

OSSL_PROVIDER *EVP_KEM_provider(const EVP_KEM *kem)
{
    return kem->prov;
}

EVP_KEM *EVP_KEM_fetch(OPENSSL_CTX *ctx, const char *algorithm,
                       const char *properties)
{
    return evp_generic_fetch(ctx, OSSL_OP_KEM, algorithm, properties,
                             evp_kem_from_dispatch,
                             (int (*)(void *))EVP_KEM_up_ref,
                             (void (*)(void *))EVP_KEM_free);
}

int EVP_KEM_is_a(const EVP_KEM *kem, const char *name)
{
    return evp_is_a(kem->prov, kem->name_id, NULL, name);
}

int EVP_KEM_number(const EVP_KEM *kem)
{
    return kem->name_id;
}

void EVP_KEM_do_all_provided(OPENSSL_CTX *libctx,
                             void (*fn)(EVP_KEM *kem, void *arg),
                             void *arg)
{
    evp_generic_do_all(libctx, OSSL_OP_KEM, (void (*)(void *, void *))fn, arg,
                       evp_kem_from_dispatch,
                       (void (*)(void *))EVP_KEM_free);
}

void EVP_KEM_names_do_all(const EVP_KEM *kem,
                          void (*fn)(const char *name, void *data),
                          void *data)
{
    if (kem->prov != NULL)
        evp_names_do_all(kem->prov, kem->name_id, fn, data);
}

const OSSL_PARAM *EVP_KEM_gettable_ctx_params(const EVP_KEM *kem)
{
    void *provctx;

    if (kem == NULL || kem->gettable_ctx_params == NULL)
        return NULL;

    provctx = ossl_provider_ctx(EVP_KEM_provider(kem));
    return kem->gettable_ctx_params(provctx);
}

const OSSL_PARAM *EVP_KEM_settable_ctx_params(const EVP_KEM *kem)
{
    void *provctx;

    if (kem == NULL || kem->settable_ctx_params == NULL)
        return NULL;

    provctx = ossl_provider_ctx(EVP_KEM_provider(kem));
    return kem->settable_ctx_params(provctx);
}
