skmhss/hoth_util.hpp

// Copyright 2024 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#pragma once

#include <stdplus/raw.hpp>

#include <cstdint>
#include <numeric>
#include <span>
#include <vector>

namespace ipmi_hoth
{
namespace internal
{

/** @class HothUtil
 *  @brief An interface to Hoth SKM HSS operation
 *  @details Translate Hoth requests to bytes array commands and analyze
 *  Hoth responses.
 */
class HothUtil
{
  public:
    virtual ~HothUtil() {};

    /** @brief Calculates the checksum for an EC request with the given
     * |contents|
     * @param one or more spans (or vectors) of bytes
     * @returns the checksum for a message with the given |contents|
     */

    template <typename... Ts>
    static uint8_t calculateChecksum(Ts&&... ts)
    {
        return (std::accumulate(std::begin(ts), std::end(ts), 0) + ...);
    }

    /** @brief Wrap the EC SKM HSS request by serializing the concatenation of
     * an EC request header and payload
     * @param request: the EC SKM HSS request
     * @returns the serialized EC request
     */
    virtual std::vector<uint8_t>
        wrapECSKMHSSRequest(std::span<const uint8_t> request) = 0;

    /** @brief Wrap the EC SKM HSS read request
     * @param slot: the slot number in Hoth
     * @returns the serialized EC request
     */
    virtual std::vector<uint8_t> readSKMHSS(uint32_t slot) = 0;

    /** @brief Wrap the EC SKM HSS write request
     * @param slot: the slot number in Hoth
     * @data data: SKM HSS bytes
     * @returns the serialized EC request
     */
    virtual std::vector<uint8_t> writeSKMHSS(uint32_t slot,
                                             std::span<const uint8_t> data) = 0;

    /** @brief Wrap the EC SKM HSS delete request
     * @param slot: the slot number in Hoth
     * @returns the serialized EC request
     */
    virtual std::vector<uint8_t> deleteSKMHSS(uint32_t slot) = 0;

    /** @brief Validate the EC response and extract the payload by stripping off
     * the header
     * @param rsp: bytes array representing response received from EC
     * @returns return the payload in an EC response iff the EC response is
     * valid.
     */
    virtual std::span<const uint8_t>
        payloadECResponse(std::span<const uint8_t> rsp) = 0;
};

} // namespace internal

} // namespace ipmi_hoth