RPCEngine.hpp

//------------------------------------------------------------------------------
/*
    This file is part of clio: https://github.com/XRPLF/clio
    Copyright (c) 2022, the clio developers.
 
    Permission to use, copy, modify, and distribute this software for any
    purpose with or without fee is hereby granted, provided that the above
    copyright notice and this permission notice appear in all copies.
 
    THE  SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
    WITH  REGARD  TO  THIS  SOFTWARE  INCLUDING  ALL  IMPLIED  WARRANTIES  OF
    MERCHANTABILITY  AND  FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
    ANY  SPECIAL,  DIRECT,  INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
    WHATSOEVER  RESULTING  FROM  LOSS  OF USE, DATA OR PROFITS, WHETHER IN AN
    ACTION  OF  CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
    OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
//==============================================================================
 
#pragma once
 
#include "data/BackendInterface.hpp"
#include "etlng/LoadBalancerInterface.hpp"
#include "rpc/Errors.hpp"
#include "rpc/RPCHelpers.hpp"
#include "rpc/WorkQueue.hpp"
#include "rpc/common/HandlerProvider.hpp"
#include "rpc/common/Types.hpp"
#include "rpc/common/impl/ForwardingProxy.hpp"
#include "util/OverloadSet.hpp"
#include "util/ResponseExpirationCache.hpp"
#include "util/log/Logger.hpp"
#include "web/Context.hpp"
#include "web/dosguard/DOSGuardInterface.hpp"
 
#include <boost/asio/spawn.hpp>
#include <boost/iterator/transform_iterator.hpp>
#include <boost/json.hpp>
#include <boost/json/object.hpp>
#include <fmt/core.h>
#include <fmt/format.h>
#include <xrpl/protocol/ErrorCodes.h>
 
#include <chrono>
#include <exception>
#include <functional>
#include <memory>
#include <optional>
#include <string>
#include <unordered_set>
#include <utility>
 
namespace rpc {
 
template <typename CountersType>
class RPCEngine {
    util::Logger perfLog_{"Performance"};
    util::Logger log_{"RPC"};
 
    std::shared_ptr<BackendInterface> backend_;
    std::reference_wrapper<web::dosguard::DOSGuardInterface const> dosGuard_;
    std::reference_wrapper<WorkQueue> workQueue_;
    std::reference_wrapper<CountersType> counters_;
 
    std::shared_ptr<HandlerProvider const> handlerProvider_;
 
    impl::ForwardingProxy<CountersType, HandlerProvider> forwardingProxy_;
 
    std::optional<util::ResponseExpirationCache> responseCache_;
 
public:
    RPCEngine(
        util::config::ClioConfigDefinition const& config,
        std::shared_ptr<BackendInterface> const& backend,
        std::shared_ptr<etlng::LoadBalancerInterface> const& balancer,
        web::dosguard::DOSGuardInterface const& dosGuard,
        WorkQueue& workQueue,
        CountersType& counters,
        std::shared_ptr<HandlerProvider const> const& handlerProvider
    )
        : backend_{backend}
        , dosGuard_{std::cref(dosGuard)}
        , workQueue_{std::ref(workQueue)}
        , counters_{std::ref(counters)}
        , handlerProvider_{handlerProvider}
        , forwardingProxy_{balancer, counters, handlerProvider}
    {
        // Let main thread catch the exception if config type is wrong
        auto const cacheTimeout = config.get<float>("rpc.cache_timeout");
 
        if (cacheTimeout > 0.f) {
            LOG(log_.info()) << fmt::format("Init RPC Cache, timeout: {} seconds", cacheTimeout);
 
            responseCache_.emplace(
                util::config::ClioConfigDefinition::toMilliseconds(cacheTimeout),
                std::unordered_set<std::string>{"server_info"}
            );
        }
    }
 
    static std::shared_ptr<RPCEngine>
    makeRPCEngine(
        util::config::ClioConfigDefinition const& config,
        std::shared_ptr<BackendInterface> const& backend,
        std::shared_ptr<etlng::LoadBalancerInterface> const& balancer,
        web::dosguard::DOSGuardInterface const& dosGuard,
        WorkQueue& workQueue,
        CountersType& counters,
        std::shared_ptr<HandlerProvider const> const& handlerProvider
    )
    {
        return std::make_shared<RPCEngine>(config, backend, balancer, dosGuard, workQueue, counters, handlerProvider);
    }
 
    Result
    buildResponse(web::Context const& ctx)
    {
        if (forwardingProxy_.shouldForward(ctx)) {
            // Disallow forwarding of the admin api, only user api is allowed for security reasons.
            if (isAdminCmd(ctx.method, ctx.params))
                return Result{Status{RippledError::rpcNO_PERMISSION}};
 
            return forwardingProxy_.forward(ctx);
        }
 
        if (not ctx.isAdmin and responseCache_ and responseCache_->shouldCache(ctx.method)) {
            auto updater =
                [this, &ctx](boost::asio::yield_context
                ) -> std::expected<util::ResponseExpirationCache::EntryData, util::ResponseExpirationCache::Error> {
                auto result = buildResponseImpl(ctx);
                auto extracted = std::visit(
                    util::OverloadSet{
                        [&result](Status status
                        ) -> std::expected<boost::json::object, util::ResponseExpirationCache::Error> {
                            return std::unexpected{util::ResponseExpirationCache::Error{
                                .status = std::move(status), .warnings = std::move(result.warnings)
                            }};
                        },
                        [](boost::json::object obj
                        ) -> std::expected<boost::json::object, util::ResponseExpirationCache::Error> { return obj; }
                    },
                    std::move(result.response)
                );
                if (extracted.has_value()) {
                    return util::ResponseExpirationCache::EntryData{
                        .lastUpdated = std::chrono::steady_clock::now(), .response = std::move(extracted).value()
                    };
                }
                return std::unexpected{std::move(extracted).error()};
            };
 
            auto result = responseCache_->getOrUpdate(
                ctx.yield,
                ctx.method,
                std::move(updater),
                [&ctx](util::ResponseExpirationCache::EntryData const& entry) {
                    return not ctx.isAdmin and not entry.response.contains("error");
                }
            );
            if (result.has_value()) {
                return Result{std::move(result).value()};
            }
 
            auto error = std::move(result).error();
            Result errorResult{std::move(error.status)};
            errorResult.warnings = std::move(error.warnings);
            return errorResult;
        }
 
        return buildResponseImpl(ctx);
    }
 
    template <typename FnType>
    bool
    post(FnType&& func, std::string const& ip)
    {
        return workQueue_.get().postCoro(std::forward<FnType>(func), dosGuard_.get().isWhiteListed(ip));
    }
 
    void
    notifyComplete(std::string const& method, std::chrono::microseconds const& duration)
    {
        if (validHandler(method))
            counters_.get().rpcComplete(method, duration);
    }
 
    void
    notifyFailed(std::string const& method)
    {
        // FIXME: seems like this is not used?
        if (validHandler(method))
            counters_.get().rpcFailed(method);
    }
 
    void
    notifyErrored(std::string const& method)
    {
        if (validHandler(method))
            counters_.get().rpcErrored(method);
    }
 
    void
    notifyTooBusy()
    {
        counters_.get().onTooBusy();
    }
 
    void
    notifyNotReady()
    {
        counters_.get().onNotReady();
    }
 
    void
    notifyBadSyntax()
    {
        counters_.get().onBadSyntax();
    }
 
    void
    notifyUnknownCommand()
    {
        counters_.get().onUnknownCommand();
    }
 
    void
    notifyInternalError()
    {
        counters_.get().onInternalError();
    }
 
private:
    bool
    validHandler(std::string const& method) const
    {
        return handlerProvider_->contains(method) || forwardingProxy_.isProxied(method);
    }
 
    Result
    buildResponseImpl(web::Context const& ctx)
    {
        if (backend_->isTooBusy()) {
            LOG(log_.error()) << "Database is too busy. Rejecting request";
            notifyTooBusy();  // TODO: should we add ctx.method if we have it?
            return Result{Status{RippledError::rpcTOO_BUSY}};
        }
 
        auto const method = handlerProvider_->getHandler(ctx.method);
        if (!method) {
            notifyUnknownCommand();
            return Result{Status{RippledError::rpcUNKNOWN_COMMAND}};
        }
 
        try {
            LOG(perfLog_.debug()) << ctx.tag() << " start executing rpc `" << ctx.method << '`';
 
            auto const context = Context{
                .yield = ctx.yield,
                .session = ctx.session,
                .isAdmin = ctx.isAdmin,
                .clientIp = ctx.clientIp,
                .apiVersion = ctx.apiVersion
            };
            auto v = (*method).process(ctx.params, context);
 
            LOG(perfLog_.debug()) << ctx.tag() << " finish executing rpc `" << ctx.method << '`';
 
            if (not v) {
                notifyErrored(ctx.method);
            }
 
            return Result{std::move(v)};
        } catch (data::DatabaseTimeout const& t) {
            LOG(log_.error()) << "Database timeout";
            notifyTooBusy();
 
            return Result{Status{RippledError::rpcTOO_BUSY}};
        } catch (std::exception const& ex) {
            LOG(log_.error()) << ctx.tag() << "Caught exception: " << ex.what();
            notifyInternalError();
 
            return Result{Status{RippledError::rpcINTERNAL}};
        }
    }
};
 
}  // namespace rpc