cable.cpp

/*
 * Copyright 2018 Google Inc.
 *
 * 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.
 */

#include "cable.hpp"

#include "errors.hpp"
#include "handler.hpp"
#include "main.hpp"

#include <cstdint>
#include <cstring>
#include <string>

namespace google
{
namespace ipmi
{

struct CableRequest
{
    uint8_t subcommand;
    uint8_t if_name_len;
    uint8_t if_name[0];
} __attribute__((packed));

ipmi_ret_t CableCheck(const uint8_t* reqBuf, uint8_t* replyBuf, size_t* dataLen,
                      const HandlerInterface* handler)
{
    // There is an IPMI LAN channel statistics command which could be used for
    // this type of check, however, we're not able to wait for the OpenBMC
    // implementation to stabilize related to the network management.
    //
    // There is a link status file, but it is "unknown" to start with...
    // The path we're checking: /sys/class/net/eth1/statistics/rx_packets

    // This command is expecting: [0x00][len][if_name]
    if ((*dataLen) < sizeof(struct CableRequest) + sizeof(uint8_t))
    {
        std::fprintf(stderr, "Invalid command length: %u\n",
                     static_cast<uint32_t>(*dataLen));
        return IPMI_CC_REQ_DATA_LEN_INVALID;
    }

    const auto request =
        reinterpret_cast<const struct CableRequest*>(&reqBuf[0]);

    // Sanity check the object contents.
    if (request->if_name_len == 0)
    {
        std::fprintf(stderr, "Invalid string length: %d\n",
                     request->if_name_len);
        return IPMI_CC_REQ_DATA_LEN_INVALID;
    }

    // Verify the request buffer contains the object and the string.
    if ((*dataLen) < (sizeof(struct CableRequest) + request->if_name_len))
    {
        std::fprintf(stderr, "*dataLen too small: %u\n",
                     static_cast<uint32_t>(*dataLen));
        return IPMI_CC_REQ_DATA_LEN_INVALID;
    }

    // Maximum length one can specify, plus null terminator.
    char nameBuf[256] = {};
    // Copy the string out of the request buffer.
    std::memcpy(&nameBuf[0], request->if_name, request->if_name_len);
    std::string name = nameBuf;
    int64_t count;

    try
    {
        count = handler->getRxPackets(name);
    }
    catch (const IpmiException& e)
    {
        return e.getIpmiError();
    }

    struct CableReply reply;
    reply.subcommand = SysCableCheck;

    // If we have received packets then there is a cable present.
    reply.value = (count > 0) ? 1 : 0;

    // Return the subcommand and the result.
    std::memcpy(&replyBuf[0], &reply, sizeof(struct CableReply));
    (*dataLen) = sizeof(struct CableReply);

    return IPMI_CC_OK;
}

} // namespace ipmi
} // namespace google