Server.hpp

//------------------------------------------------------------------------------
/*
    This file is part of clio: https://github.com/XRPLF/clio
    Copyright (c) 2023, 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/LedgerCacheInterface.hpp"
#include "util/Taggable.hpp"
#include "util/log/Logger.hpp"
#include "web/AdminVerificationStrategy.hpp"
#include "web/HttpSession.hpp"
#include "web/ProxyIpResolver.hpp"
#include "web/SslHttpSession.hpp"
#include "web/dosguard/DOSGuardInterface.hpp"
#include "web/interface/Concepts.hpp"
#include "web/ng/impl/ServerSslContext.hpp"
 
#include <boost/asio/io_context.hpp>
#include <boost/asio/ip/address.hpp>
#include <boost/asio/ip/tcp.hpp>
#include <boost/asio/socket_base.hpp>
#include <boost/asio/spawn.hpp>
#include <boost/asio/ssl/context.hpp>
#include <boost/asio/ssl/error.hpp>
#include <boost/asio/strand.hpp>
#include <boost/beast/core/error.hpp>
#include <boost/beast/core/flat_buffer.hpp>
#include <boost/beast/core/stream_traits.hpp>
#include <boost/beast/core/tcp_stream.hpp>
#include <fmt/format.h>
 
#include <atomic>
#include <chrono>
#include <cstdint>
#include <exception>
#include <functional>
#include <memory>
#include <optional>
#include <stdexcept>
#include <string>
#include <utility>

namespace web {

template <
    template <typename> class PlainSessionType,
    template <typename> class SslSessionType,
    SomeServerHandler HandlerType>
class Detector
    : public std::enable_shared_from_this<Detector<PlainSessionType, SslSessionType, HandlerType>> {
    using std::enable_shared_from_this<
        Detector<PlainSessionType, SslSessionType, HandlerType>>::shared_from_this;
 
    util::Logger log_{"WebServer"};
    boost::beast::tcp_stream stream_;
    std::optional<std::reference_wrapper<boost::asio::ssl::context>> ctx_;
    std::reference_wrapper<util::TagDecoratorFactory const> tagFactory_;
    std::reference_wrapper<dosguard::DOSGuardInterface> const dosGuard_;
    std::shared_ptr<HandlerType> const handler_;
    std::reference_wrapper<data::LedgerCacheInterface const> cache_;
    boost::beast::flat_buffer buffer_;
    std::shared_ptr<AdminVerificationStrategy> const adminVerification_;
    std::uint32_t maxWsSendingQueueSize_;
    std::shared_ptr<ProxyIpResolver> proxyIpResolver_;
 
public:
    Detector(
        tcp::socket&& socket,
        std::optional<std::reference_wrapper<boost::asio::ssl::context>> ctx,
        std::reference_wrapper<util::TagDecoratorFactory const> tagFactory,
        std::reference_wrapper<dosguard::DOSGuardInterface> dosGuard,
        std::shared_ptr<HandlerType> handler,
        std::reference_wrapper<data::LedgerCacheInterface const> cache,
        std::shared_ptr<AdminVerificationStrategy> adminVerification,
        std::uint32_t maxWsSendingQueueSize,
        std::shared_ptr<ProxyIpResolver> proxyIpResolver
    )
        : stream_(std::move(socket))
        , ctx_(ctx)
        , tagFactory_(std::cref(tagFactory))
        , dosGuard_(dosGuard)
        , handler_(std::move(handler))
        , cache_(cache)
        , adminVerification_(std::move(adminVerification))
        , maxWsSendingQueueSize_(maxWsSendingQueueSize)
        , proxyIpResolver_(std::move(proxyIpResolver))
    {
    }

    void
    fail(boost::system::error_code ec, char const* message)
    {
        if (ec == boost::asio::ssl::error::stream_truncated)
            return;
 
        LOG(log_.info()) << "Detector failed (" << message << "): " << ec.message();
    }

    void
    run()
    {
        boost::beast::get_lowest_layer(stream_).expires_after(std::chrono::seconds(30));
        async_detect_ssl(
            stream_,
            buffer_,
            boost::beast::bind_front_handler(&Detector::onDetect, shared_from_this())
        );
    }

    void
    onDetect(boost::beast::error_code ec, bool result)
    {
        if (ec)
            return fail(ec, "detect");
 
        std::string ip;
        try {
            ip = stream_.socket().remote_endpoint().address().to_string();
        } catch (std::exception const&) {
            return fail(ec, "cannot get remote endpoint");
        }
 
        if (result) {
            if (!ctx_)
                return fail(ec, "SSL is not supported by this server");
 
            std::make_shared<SslSessionType<HandlerType>>(
                stream_.release_socket(),
                ip,
                adminVerification_,
                proxyIpResolver_,
                *ctx_,
                tagFactory_,
                dosGuard_,
                handler_,
                cache_,
                std::move(buffer_),
                maxWsSendingQueueSize_
            )
                ->run();
            return;
        }
 
        std::make_shared<PlainSessionType<HandlerType>>(
            stream_.release_socket(),
            ip,
            adminVerification_,
            proxyIpResolver_,
            tagFactory_,
            dosGuard_,
            handler_,
            cache_,
            std::move(buffer_),
            maxWsSendingQueueSize_
        )
            ->run();
    }
};

template <
    template <typename> class PlainSessionType,
    template <typename> class SslSessionType,
    SomeServerHandler HandlerType>
class Server
    : public ServerTag,
      public std::enable_shared_from_this<Server<PlainSessionType, SslSessionType, HandlerType>> {
    using std::enable_shared_from_this<
        Server<PlainSessionType, SslSessionType, HandlerType>>::shared_from_this;
 
    util::Logger log_{"WebServer"};
    std::reference_wrapper<boost::asio::io_context> ioc_;
    std::optional<boost::asio::ssl::context> ctx_;
    util::TagDecoratorFactory tagFactory_;
    std::reference_wrapper<dosguard::DOSGuardInterface> dosGuard_;
    std::shared_ptr<HandlerType> handler_;
    std::reference_wrapper<data::LedgerCacheInterface const> cache_;
    tcp::acceptor acceptor_;
    std::shared_ptr<AdminVerificationStrategy> adminVerification_;
    std::uint32_t maxWsSendingQueueSize_;
    std::shared_ptr<ProxyIpResolver> proxyIpResolver_;
    std::atomic_bool isStopped_{false};
 
public:
    Server(
        boost::asio::io_context& ioc,
        std::optional<boost::asio::ssl::context> ctx,
        tcp::endpoint endpoint,
        util::TagDecoratorFactory tagFactory,
        dosguard::DOSGuardInterface& dosGuard,
        std::shared_ptr<HandlerType> handler,
        std::reference_wrapper<data::LedgerCacheInterface const> cache,
        std::shared_ptr<AdminVerificationStrategy> adminVerification,
        std::uint32_t maxWsSendingQueueSize,
        ProxyIpResolver proxyIpResolver
    )
        : ioc_(std::ref(ioc))
        , ctx_(std::move(ctx))
        , tagFactory_(tagFactory)
        , dosGuard_(std::ref(dosGuard))
        , handler_(std::move(handler))
        , cache_(cache)
        , acceptor_(boost::asio::make_strand(ioc))
        , adminVerification_(std::move(adminVerification))
        , maxWsSendingQueueSize_(maxWsSendingQueueSize)
        , proxyIpResolver_(std::make_shared<ProxyIpResolver>(std::move(proxyIpResolver)))
    {
        boost::beast::error_code ec;
 
        acceptor_.open(endpoint.protocol(), ec);
        if (ec)
            return;
 
        acceptor_.set_option(boost::asio::socket_base::reuse_address(true), ec);
        if (ec)
            return;
 
        acceptor_.bind(endpoint, ec);
        if (ec) {
            LOG(log_.error()) << "Failed to bind to endpoint: " << endpoint
                              << ". message: " << ec.message();
            throw std::runtime_error(
                fmt::format(
                    "Failed to bind to endpoint: {}:{}",
                    endpoint.address().to_string(),
                    endpoint.port()
                )
            );
        }
 
        acceptor_.listen(boost::asio::socket_base::max_listen_connections, ec);
        if (ec) {
            LOG(log_.error()) << "Failed to listen at endpoint: " << endpoint
                              << ". message: " << ec.message();
            throw std::runtime_error(
                fmt::format(
                    "Failed to listen at endpoint: {}:{}",
                    endpoint.address().to_string(),
                    endpoint.port()
                )
            );
        }
    }

    void
    run()
    {
        doAccept();
    }

    void
    stop(boost::asio::yield_context)
    {
        isStopped_ = true;
    }
 
private:
    void
    doAccept()
    {
        acceptor_.async_accept(
            boost::asio::make_strand(ioc_.get()),
            boost::beast::bind_front_handler(&Server::onAccept, shared_from_this())
        );
    }
 
    void
    onAccept(boost::beast::error_code ec, tcp::socket socket)
    {
        if (isStopped_) {
            return;
        }
 
        if (!ec) {
            auto ctxRef = ctx_
                ? std::optional<std::reference_wrapper<boost::asio::ssl::context>>{ctx_.value()}
                : std::nullopt;
 
            std::make_shared<Detector<PlainSessionType, SslSessionType, HandlerType>>(
                std::move(socket),
                ctxRef,
                std::cref(tagFactory_),
                dosGuard_,
                handler_,
                cache_,
                adminVerification_,
                maxWsSendingQueueSize_,
                proxyIpResolver_
            )
                ->run();
        }
 
        doAccept();
    }
};

template <typename HandlerType>
using HttpServer = Server<HttpSession, SslHttpSession, HandlerType>;

template <typename HandlerType>
static std::shared_ptr<HttpServer<HandlerType>>
makeHttpServer(
    util::config::ClioConfigDefinition const& config,
    boost::asio::io_context& ioc,
    dosguard::DOSGuardInterface& dosGuard,
    std::shared_ptr<HandlerType> const& handler,
    std::reference_wrapper<data::LedgerCacheInterface const> cache
)
{
    static util::Logger const log{"WebServer"};  // NOLINT(readability-identifier-naming)
 
    auto expectedSslContext = ng::impl::makeServerSslContext(config);
    if (not expectedSslContext) {
        LOG(log.error()) << "Failed to create SSL context: " << expectedSslContext.error();
        return nullptr;
    }
 
    auto const serverConfig = config.getObject("server");
    auto const address = boost::asio::ip::make_address(serverConfig.get<std::string>("ip"));
    auto const port = serverConfig.get<unsigned short>("port");
 
    auto expectedAdminVerification = makeAdminVerificationStrategy(config);
    if (not expectedAdminVerification.has_value()) {
        LOG(log.error()) << expectedAdminVerification.error();
        throw std::logic_error{expectedAdminVerification.error()};
    }
 
    // If the transactions number is 200 per ledger, A client which subscribes everything will send
    // 400+ feeds for each ledger. we allow user delay 3 ledgers by default
    auto const maxWsSendingQueueSize = serverConfig.get<uint32_t>("ws_max_sending_queue_size");
 
    auto proxyIpResolver = ProxyIpResolver::fromConfig(config);
 
    auto server = std::make_shared<HttpServer<HandlerType>>(
        ioc,
        std::move(expectedSslContext).value(),
        boost::asio::ip::tcp::endpoint{address, port},
        util::TagDecoratorFactory(config),
        dosGuard,
        handler,
        cache,
        std::move(expectedAdminVerification).value(),
        maxWsSendingQueueSize,
        std::move(proxyIpResolver)
    );
 
    server->run();
    return server;
}
 
}  // namespace web