provider_registration.cpp

#include <dirent.h>
#include <dlfcn.h>
#include <stdlib.h>
#include <string.h>

#include <iostream>

#include <host-ipmid/ipmid-api.h>
#include "command_table.hpp"
#include "main.hpp"
#include "provider_registration.hpp"

namespace provider
{

int handler_select(const struct dirent* entry)
{
    // Check for versioned libraries .so.*
    if (strstr(entry->d_name, PROVIDER_SONAME_EXTN))
    {
        return 1;
    }
    else
    {
        return 0;
    }
}

void registerCallbackHandlers(const char* providerLibPath)
{
    if (providerLibPath == NULL)
    {
        std::cerr << "Path not provided for registering IPMI provider libraries"
                  << "\n";
        return;
    }

    struct dirent** handlerList = nullptr;
    std::string handlerPath(providerLibPath);

    auto numLibs = scandir(providerLibPath, &handlerList, handler_select,
                           alphasort);
    if (numLibs < 0)
    {
        return;
    }

    // dlopen each IPMI provider shared library
    while (numLibs--)
    {
        handlerPath = providerLibPath;
        handlerPath += handlerList[numLibs]->d_name;

        auto lib_handler = dlopen(handlerPath.c_str(), RTLD_NOW);

        if (lib_handler == NULL)
        {
            std::cerr << "Error opening " << handlerPath << dlerror() << "\n";
        }
        free(handlerList[numLibs]);
    }

    free(handlerList);
}

} // namespace provider

/*
 * @brief Method that gets called from IPMI provider shared libraries to get
 *        the command handlers registered.
 *
 * When the IPMI provider shared library is loaded, the dynamic loader program
 * looks for special section(.ctors on ELF) which contains references to the
 * functions marked with the constructor attributes. This function is invoked
 * in such manner.
 *
 * @param[in] netfn - Network Function code
 * @param[in] cmd - Command
 * @param[in] context - User specific data
 * @param[in] handler - The callback routine for the command
 * @param[in] priv - IPMI Command Privilege
 */
void ipmi_register_callback(ipmi_netfn_t netfn, ipmi_cmd_t cmd,
                            ipmi_context_t context,
                            ipmid_callback_t handler, ipmi_cmd_privilege_t priv)
{
    uint16_t netFn = netfn << 10;

    // The payload type of IPMI commands provided by the shared libraries
    // is IPMI
    command::CommandID command =
    {
        ((static_cast<uint32_t>(message::PayloadType::IPMI)) << 16) |
        netFn | cmd
    };

    std::get<command::Table&>(singletonPool).registerCommand(command,
            std::make_unique<command::ProviderIpmidEntry>
            (command, handler, static_cast<session::Privilege>(priv)));
}