Response.cpp

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/*
 * SNode.C - a slim toolkit for network communication
 * Copyright (C) Volker Christian <me@vchrist.at>
 *               2020, 2021, 2022, 2023, 2024, 2025
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published
 * by the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 */
 
#include "web/http/server/Response.h"
 
#include "SocketContext.h"
#include "core/file/FileReader.h"
#include "core/socket/stream/SocketConnection.h"
#include "web/http/MimeTypes.h"
#include "web/http/StatusCodes.h"
#include "web/http/server/SocketContextUpgradeFactorySelector.h"
 
#ifndef DOXYGEN_SHOULD_SKIP_THIS
 
#include "log/Logger.h"
#include "utils/system/time.h"
#include "web/http/CiStringMap.h"
#include "web/http/http_utils.h"
 
#include <cerrno>
#include <filesystem>
#include <iterator>
#include <numeric>
#include <sstream>
#include <system_error>
#include <utility>
 
#endif /* DOXYGEN_SHOULD_SKIP_THIS */
 
#define to_hex_str(int_val) (static_cast<std::ostringstream const&>(std::ostringstream() << std::uppercase << std::hex << int_val)).str()
 
namespace web::http::server {
 
    Response::Response(SocketContext* socketContext)
        : socketContext(socketContext) {
    }
 
    Response::~Response() {
        if (socketContext != nullptr && Sink::isStreaming()) {
            socketContext->streamEof();
        }
 
        delete socketContextUpgrade; // delete of nullptr is valid since C++14!
    }
 
    void Response::stopResponse() {
        stop();
    }
 
    void Response::init() {
        statusCode = 200;
        httpMajor = 1;
        httpMinor = 1;
        headers.clear();
        cookies.clear();
        trailer.clear();
        contentLength = 0;
        contentSent = 0;
        socketContextUpgrade = nullptr;
        connectionState = ConnectionState::Default;
        transferEncoding = TransferEncoding::HTTP10;
    }
 
    Response& Response::status(int statusCode) {
        this->statusCode = statusCode;
 
        return *this;
    }
 
    Response& Response::append(const std::string& field, const std::string& value) {
        const std::map<std::string, std::string>::iterator it = headers.find(field);
 
        if (it != headers.end()) {
            set(field, it->second.append(", ").append(value));
        } else {
            set(field, value);
        }
 
        return *this;
    }
 
    Response& Response::set(const std::map<std::string, std::string>& headers, bool overwrite) {
        for (const auto& [field, value] : headers) {
            set(field, value, overwrite);
        }
 
        return *this;
    }
 
    Response& Response::set(const std::string& field, const std::string& value, bool overwrite) {
        if (!value.empty()) {
            if (overwrite) {
                headers.insert_or_assign(field, value);
            } else {
                headers.insert({field, value});
            }
 
            if (web::http::ciEquals(field, "Connection")) {
                if (web::http::ciContains(headers[field], "keep-alive")) {
                    connectionState = ConnectionState::Keep;
                } else if (web::http::ciContains(headers[field], "close")) {
                    connectionState = ConnectionState::Close;
                }
            } else if (web::http::ciEquals(field, "Content-Length")) {
                contentLength = std::stoul(value);
                transferEncoding = TransferEncoding::Identity;
                headers.erase("Transfer-Encoding");
            } else if (web::http::ciEquals(field, "Transfer-Encoding")) {
                if (web::http::ciContains(headers[field], "chunked")) {
                    transferEncoding = TransferEncoding::Chunked;
                    headers.erase("Content-Length");
                }
                if (web::http::ciContains(headers[field], "compressed")) {
                }
                if (web::http::ciContains(headers[field], "deflate")) {
                }
                if (web::http::ciContains(headers[field], "gzip")) {
                }
            } else if (web::http::ciEquals(field, "Content-Encoding")) {
                if (web::http::ciContains(headers[field], "compressed")) {
                }
                if (web::http::ciContains(headers[field], "deflate")) {
                }
                if (web::http::ciContains(headers[field], "gzip")) {
                }
                if (web::http::ciContains(headers[field], "br")) {
                }
            }
        } else {
            headers.erase(field);
        }
 
        return *this;
    }
 
    Response& Response::type(const std::string& type) {
        return set("Content-Type", type);
    }
 
    Response& Response::cookie(const std::string& name, const std::string& value, const std::map<std::string, std::string>& options) {
        cookies.insert({name, CookieOptions(value, options)});
 
        return *this;
    }
 
    Response& Response::clearCookie(const std::string& name, const std::map<std::string, std::string>& options) {
        std::map<std::string, std::string> opts = options;
 
        opts.erase("Max-Age");
        const time_t time = 0;
        opts["Expires"] = httputils::to_http_date(utils::system::gmtime(&time));
 
        return cookie(name, "", opts);
    }
 
    Response& Response::setTrailer(const std::string& field, const std::string& value, bool overwrite) {
        if (!value.empty()) {
            if (overwrite) {
                trailer.insert_or_assign(field, value);
            } else {
                trailer.insert({field, value});
            }
            if (!headers.contains("Trailer")) {
                set("Trailer", field);
            } else {
                headers["Trailer"].append("," + field);
            }
        } else {
            trailer.erase(field);
        }
 
        return *this;
    }
 
    void Response::send(const char* chunk, std::size_t chunkLen) {
        if (chunkLen > 0) {
            set("Content-Type", "application/octet-stream", false);
        }
        set("Content-Length", std::to_string(chunkLen));
 
        sendHeader();
        sendFragment(chunk, chunkLen);
        sendCompleted();
    }
 
    void Response::send(const std::string& chunk) {
        if (!chunk.empty()) {
            set("Content-Type", "text/html; charset=utf-8", false);
        }
 
        send(chunk.data(), chunk.size());
    }
 
    void Response::sendStatus(int statusCode) {
        status(statusCode);
 
        send(StatusCode::reason(statusCode));
    }
 
    /* Just an UML-Sequence diagram test */
    /** Sequence diagram of res.upgrade(req).
@startuml
!include web/http/server/pu/response_upgrade.pu
@enduml
     */
    void Response::upgrade(const std::shared_ptr<Request>& request, const std::function<void(const std::string&)>& status) {
        std::string name;
 
        if (socketContext != nullptr) {
            if (request != nullptr) {
                if (web::http::ciContains(request->get("connection"), "Upgrade")) {
                    web::http::server::SocketContextUpgradeFactory* socketContextUpgradeFactory =
                        web::http::server::SocketContextUpgradeFactorySelector::instance()->select(*request, *this);
 
                    if (socketContextUpgradeFactory != nullptr) {
                        name = socketContextUpgradeFactory->name();
                        LOG(DEBUG) << socketContext->getSocketConnection()->getConnectionName()
                                   << " HTTP upgrade: SocketContextUpgradeFactory created successful: " << name;
 
                        socketContextUpgrade = socketContextUpgradeFactory->create(socketContext->getSocketConnection());
 
                        if (socketContextUpgrade != nullptr) {
                            LOG(DEBUG) << socketContext->getSocketConnection()->getConnectionName()
                                       << " HTTP upgrade: SocketContextUpgrade created successful: " << name;
                        } else {
                            LOG(DEBUG) << socketContext->getSocketConnection()->getConnectionName()
                                       << " HTTP upgrade: Create SocketContextUpgrade failed: " << name;
 
                            set("Connection", "close").status(404);
                        }
                    } else {
                        LOG(DEBUG) << socketContext->getSocketConnection()->getConnectionName()
                                   << " HTTP upgrade: SocketContextUpgradeFactory not supported: " << request->get("upgrade");
 
                        set("Connection", "close").status(404);
                    }
                } else {
                    LOG(DEBUG) << socketContext->getSocketConnection()->getConnectionName() << " HTTP upgrade: No upgrade requested";
 
                    set("Connection", "close").status(400);
                }
            } else {
                LOG(ERROR) << socketContext->getSocketConnection()->getConnectionName() << " HTTP upgrade: Request has gone away";
 
                set("Connection", "close").status(500);
            }
        } else {
            LOG(ERROR) << socketContext->getSocketConnection()->getConnectionName() << " HTTP upgrade: SocketContext has gone away";
        }
 
        status(name);
    }
 
    void Response::sendFile(const std::string& file, const std::function<void(int)>& callback) {
        if (socketContext != nullptr) {
            std::string absolutFileName = file;
 
            if (std::filesystem::exists(absolutFileName)) {
                std::error_code ec;
                absolutFileName = std::filesystem::canonical(absolutFileName);
 
                if (std::filesystem::is_regular_file(absolutFileName, ec) && !ec) {
                    core::file::FileReader::open(absolutFileName)->pipe(this, [this, &absolutFileName, &callback](int errnum) {
                        callback(errnum);
 
                        if (errnum == 0) {
                            set("Content-Type", web::http::MimeTypes::contentType(absolutFileName), false);
                            set("Last-Modified", httputils::file_mod_http_date(absolutFileName), false);
                            if (httpMajor == 1) {
                                if (httpMinor == 1) {
                                    set("Transfer-Encoding", "chunked");
                                } else {
                                    set("Content-Length", std::to_string(std::filesystem::file_size(absolutFileName)));
                                }
                            }
                        }
                    });
                } else {
                    errno = EEXIST;
                    callback(errno);
                }
            } else {
                errno = ENOENT;
                callback(errno);
            }
        }
    }
 
    void Response::end() {
        send("");
    }
 
    Response& Response::sendHeader() {
        if (socketContext != nullptr) {
            socketContext->responseStarted();
 
            socketContext->sendToPeer("HTTP/" + std::to_string(httpMajor)
                                                    .append(".")
                                                    .append(std::to_string(httpMinor))
                                                    .append(" ")
                                                    .append(std::to_string(statusCode))
                                                    .append(" ")
                                                    .append(StatusCode::reason(statusCode))
                                                    .append("\r\n"));
            socketContext->sendToPeer("Date: " + httputils::to_http_date() + "\r\n");
 
            set("X-Powered-By", "snode.c");
 
            for (const auto& [field, value] : headers) {
                socketContext->sendToPeer(std::string(field).append(": ").append(value).append("\r\n"));
            }
 
            for (const auto& [cookie, cookieValue] : cookies) {
                const std::string cookieString = std::accumulate(
                    cookieValue.getOptions().begin(),
                    cookieValue.getOptions().end(),
                    cookie + "=" + cookieValue.getValue(),
                    [](const std::string& str, const std::pair<const std::string&, const std::string&> option) -> std::string {
                        return str + "; " + option.first + (!option.second.empty() ? "=" + option.second : "");
                    });
                socketContext->sendToPeer("Set-Cookie: " + cookieString + "\r\n");
            }
 
            socketContext->sendToPeer("\r\n");
        }
 
        return *this;
    }
 
    Response& Response::sendFragment(const char* chunk, std::size_t chunkLen) {
        if (socketContext != nullptr) {
            if (transferEncoding == TransferEncoding::Chunked) {
                socketContext->sendToPeer(to_hex_str(chunkLen).append("\r\n"));
            }
 
            socketContext->sendToPeer(chunk, chunkLen);
            contentSent += chunkLen;
 
            if (transferEncoding == TransferEncoding::Chunked) {
                socketContext->sendToPeer("\r\n");
                contentLength += chunkLen;
            }
        }
 
        return *this;
    }
 
    Response& Response::sendFragment(const std::string& chunk) {
        return sendFragment(chunk.data(), chunk.size());
    }
 
    void Response::sendCompleted() {
        if (transferEncoding == TransferEncoding::Chunked) {
            sendFragment(""); // For transfer encoding chunked. Terminate the chunk sequence.
 
            if (!trailer.empty()) {
                for (auto& [field, value] : trailer) {
                    socketContext->sendToPeer(std::string(field).append(":").append(value).append("\r\n"));
                }
 
                socketContext->sendToPeer("\r\n");
            }
        }
 
        if (socketContext != nullptr) {
            socketContext->responseCompleted(contentSent == contentLength || (httpMajor == 1 && httpMinor == 0));
 
            if (socketContextUpgrade != nullptr) {
                socketContext->switchSocketContext(socketContextUpgrade);
                socketContextUpgrade = nullptr;
            }
        }
    }
 
    void Response::onSourceConnect(core::pipe::Source* source) {
        if (socketContext != nullptr) {
            if (socketContext->streamToPeer(source)) {
                sendHeader();
 
                source->start();
            } else {
                source->stop();
            }
        } else {
            source->stop();
        }
    }
 
    void Response::onSourceData(const char* chunk, std::size_t chunkLen) {
        sendFragment(chunk, chunkLen);
    }
 
    void Response::onSourceEof() {
        if (socketContext != nullptr) {
            socketContext->streamEof();
        }
 
        sendCompleted();
    }
 
    void Response::onSourceError(int errnum) {
        errno = errnum;
 
        if (socketContext != nullptr) {
            socketContext->streamEof();
            socketContext->close();
        }
 
        sendCompleted();
    }
 
    const std::string& Response::header(const std::string& field) {
        return headers[field];
    }
 
    SocketContext* Response::getSocketContext() const {
        return socketContext;
    }
 
} // namespace web::http::server