rippled/include/xrpl/protocol/ApiVersion.h

#ifndef XRPL_PROTOCOL_APIVERSION_H_INCLUDED
#define XRPL_PROTOCOL_APIVERSION_H_INCLUDED

#include <xrpl/beast/core/SemanticVersion.h>
#include <xrpl/beast/utility/instrumentation.h>
#include <xrpl/json/json_value.h>
#include <xrpl/protocol/jss.h>

#include <type_traits>
#include <utility>

namespace xrpl {

/**
 * API version numbers used in later API versions
 *
 * Requests with a version number in the range
 * [apiMinimumSupportedVersion, apiMaximumSupportedVersion]
 * are supported.
 *
 * If [beta_rpc_api] is enabled in config, the version numbers
 * in the range [apiMinimumSupportedVersion, apiBetaVersion]
 * are supported.
 *
 * Network Requests without explicit version numbers use
 * apiVersionIfUnspecified. apiVersionIfUnspecified is 1,
 * because all the RPC requests with a version >= 2 must
 * explicitly specify the version in the requests.
 * Note that apiVersionIfUnspecified will be lower than
 * apiMinimumSupportedVersion when we stop supporting API
 * version 1.
 *
 * Command line Requests use apiCommandLineVersion.
 */

namespace RPC {

template <unsigned int Version>
constexpr static std::integral_constant<unsigned, Version> apiVersion = {};

constexpr static auto apiInvalidVersion = apiVersion<0>;
constexpr static auto apiMinimumSupportedVersion = apiVersion<1>;
constexpr static auto apiMaximumSupportedVersion = apiVersion<2>;
constexpr static auto apiVersionIfUnspecified = apiVersion<1>;
constexpr static auto apiCommandLineVersion =
    apiVersion<1>;  // TODO Bump to 2 later
constexpr static auto apiBetaVersion = apiVersion<3>;
constexpr static auto apiMaximumValidVersion = apiBetaVersion;

static_assert(apiInvalidVersion < apiMinimumSupportedVersion);
static_assert(
    apiVersionIfUnspecified >= apiMinimumSupportedVersion &&
    apiVersionIfUnspecified <= apiMaximumSupportedVersion);
static_assert(
    apiCommandLineVersion >= apiMinimumSupportedVersion &&
    apiCommandLineVersion <= apiMaximumSupportedVersion);
static_assert(apiMaximumSupportedVersion >= apiMinimumSupportedVersion);
static_assert(apiBetaVersion >= apiMaximumSupportedVersion);
static_assert(apiMaximumValidVersion >= apiMaximumSupportedVersion);

template <class JsonObject>
void
setVersion(JsonObject& parent, unsigned int apiVersion, bool betaEnabled)
{
    XRPL_ASSERT(
        apiVersion != apiInvalidVersion,
        "xrpl::RPC::setVersion : input is valid");
    auto& retObj = addObject(parent, jss::version);

    if (apiVersion == apiVersionIfUnspecified)
    {
        // API version numbers used in API version 1
        static beast::SemanticVersion const firstVersion{"1.0.0"};
        static beast::SemanticVersion const goodVersion{"1.0.0"};
        static beast::SemanticVersion const lastVersion{"1.0.0"};

        retObj[jss::first] = firstVersion.print();
        retObj[jss::good] = goodVersion.print();
        retObj[jss::last] = lastVersion.print();
    }
    else
    {
        retObj[jss::first] = apiMinimumSupportedVersion.value;
        retObj[jss::last] =
            betaEnabled ? apiBetaVersion : apiMaximumSupportedVersion;
    }
}

/**
 * Retrieve the api version number from the json value
 *
 * Note that APIInvalidVersion will be returned if
 * 1) the version number field has a wrong format
 * 2) the version number retrieved is out of the supported range
 * 3) the version number is unspecified and
 *    APIVersionIfUnspecified is out of the supported range
 *
 * @param jv a Json value that may or may not specifies
 *        the api version number
 * @param betaEnabled if the beta API version is enabled
 * @return the api version number
 */
inline unsigned int
getAPIVersionNumber(Json::Value const& jv, bool betaEnabled)
{
    static Json::Value const minVersion(RPC::apiMinimumSupportedVersion);
    Json::Value const maxVersion(
        betaEnabled ? RPC::apiBetaVersion : RPC::apiMaximumSupportedVersion);

    if (jv.isObject())
    {
        if (jv.isMember(jss::api_version))
        {
            auto const specifiedVersion = jv[jss::api_version];
            if (!specifiedVersion.isInt() && !specifiedVersion.isUInt())
            {
                return RPC::apiInvalidVersion;
            }
            auto const specifiedVersionInt = specifiedVersion.asInt();
            if (specifiedVersionInt < minVersion ||
                specifiedVersionInt > maxVersion)
            {
                return RPC::apiInvalidVersion;
            }
            return specifiedVersionInt;
        }
    }

    return RPC::apiVersionIfUnspecified;
}

}  // namespace RPC

template <unsigned minVer, unsigned maxVer, typename Fn, typename... Args>
void
forApiVersions(Fn const& fn, Args&&... args)
    requires                                        //
    (maxVer >= minVer) &&                           //
    (minVer >= RPC::apiMinimumSupportedVersion) &&  //
    (RPC::apiMaximumValidVersion >= maxVer) && requires {
        fn(std::integral_constant<unsigned int, minVer>{},
           std::forward<Args>(args)...);
        fn(std::integral_constant<unsigned int, maxVer>{},
           std::forward<Args>(args)...);
    }
{
    constexpr auto size = maxVer + 1 - minVer;
    [&]<std::size_t... offset>(std::index_sequence<offset...>) {
        (((void)fn(
             std::integral_constant<unsigned int, minVer + offset>{},
             std::forward<Args>(args)...)),
         ...);
    }(std::make_index_sequence<size>{});
}

template <typename Fn, typename... Args>
void
forAllApiVersions(Fn const& fn, Args&&... args)
    requires requires {
        forApiVersions<
            RPC::apiMinimumSupportedVersion,
            RPC::apiMaximumValidVersion>(fn, std::forward<Args>(args)...);
    }
{
    forApiVersions<
        RPC::apiMinimumSupportedVersion,
        RPC::apiMaximumValidVersion>(fn, std::forward<Args>(args)...);
}

}  // namespace xrpl

#endif