Simple HTTP Server

 // Copyright (C) 2018 The Qt Company Ltd.
 // SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause

 #include <QHttpServer>
 #include <QHttpServerResponse>

 #if QT_CONFIG(ssl)
 #  include <QSslCertificate>
 #  include <QSslKey>
 #endif

 #include <QCoreApplication>
 #include <QFile>
 #include <QJsonObject>
 #include <QString>

 using namespace Qt::StringLiterals;

 static inline QString host(const QHttpServerRequest &request)
 {
     return QString::fromLatin1(request.value("Host"));
 }

 int main(int argc, char *argv[])
 {
     QCoreApplication app(argc, argv);

     QHttpServer httpServer;
     httpServer.route("/", []() {
         return "Hello world";
     });

     httpServer.route("/query", [] (const QHttpServerRequest &request) {
         return host(request) + u"/query/"_s;
     });

     httpServer.route("/query/", [] (qint32 id, const QHttpServerRequest &request) {
         return u"%1/query/%2"_s.arg(host(request)).arg(id);
     });

     httpServer.route("/query/<arg>/log", [] (qint32 id, const QHttpServerRequest &request) {
         return u"%1/query/%2/log"_s.arg(host(request)).arg(id);
     });

     httpServer.route("/query/<arg>/log/", [] (qint32 id, float threshold,
                                               const QHttpServerRequest &request) {
         return u"%1/query/%2/log/%3"_s.arg(host(request)).arg(id).arg(threshold);
     });

     httpServer.route("/user/", [] (const qint32 id) {
         return u"User "_s + QString::number(id);
     });

     httpServer.route("/user/<arg>/detail", [] (const qint32 id) {
         return u"User %1 detail"_s.arg(id);
     });

     httpServer.route("/user/<arg>/detail/", [] (const qint32 id, const qint32 year) {
         return u"User %1 detail year - %2"_s.arg(id).arg(year);
     });

     httpServer.route("/json/", [] {
         return QJsonObject{
             {
                 {"key1", "1"},
                 {"key2", "2"},
                 {"key3", "3"}
             }
         };
     });

     httpServer.route("/assets/<arg>", [] (const QUrl &url) {
         return QHttpServerResponse::fromFile(u":/assets/"_s + url.path());
     });

     httpServer.route("/remote_address", [](const QHttpServerRequest &request) {
         return request.remoteAddress().toString();
     });

     // Basic authentication example (RFC 7617)
     httpServer.route("/auth", [](const QHttpServerRequest &request) {
         auto auth = request.value("authorization").simplified();

         if (auth.size() > 6 && auth.first(6).toLower() == "basic ") {
             auto token = auth.sliced(6);
             auto userPass = QByteArray::fromBase64(token);

             if (auto colon = userPass.indexOf(':'); colon > 0) {
                 auto userId = userPass.first(colon);
                 auto password = userPass.sliced(colon + 1);

                 if (userId == "Aladdin" && password == "open sesame")
                     return QHttpServerResponse("text/plain", "Success\n");
             }
         }
         QHttpServerResponse response("text/plain", "Authentication required\n",
                                      QHttpServerResponse::StatusCode::Unauthorized);
         response.setHeader("WWW-Authenticate", R"(Basic realm="Simple example", charset="UTF-8")");
         return response;
     });

     httpServer.afterRequest([](QHttpServerResponse &&resp) {
         resp.setHeader("Server", "Qt HTTP Server");
         return std::move(resp);
     });

     const auto port = httpServer.listen(QHostAddress::Any);
     if (!port) {
         qWarning() << QCoreApplication::translate("QHttpServerExample",
                                                   "Server failed to listen on a port.");
         return -1;
     }

 #if QT_CONFIG(ssl)
     const auto sslCertificateChain =
             QSslCertificate::fromPath(QStringLiteral(":/assets/certificate.crt"));
     if (sslCertificateChain.empty()) {
         qWarning() << QCoreApplication::translate("QHttpServerExample",
                                                   "Couldn't retrieve SSL certificate from file.");
         return -1;
     }
     QFile privateKeyFile(QStringLiteral(":/assets/private.key"));
     if (!privateKeyFile.open(QIODevice::ReadOnly)) {
         qWarning() << QCoreApplication::translate("QHttpServerExample",
                                                   "Couldn't open file for reading: %1")
                       .arg(privateKeyFile.errorString());
         return -1;
     }
     httpServer.sslSetup(sslCertificateChain.front(), QSslKey(&privateKeyFile, QSsl::Rsa));
     privateKeyFile.close();

     const auto sslPort = httpServer.listen(QHostAddress::Any);
     if (!sslPort) {
         qWarning() << QCoreApplication::translate("QHttpServerExample",
                                                   "Server failed to listen on a port.");
         return -1;
     }

     qInfo().noquote()
         << QCoreApplication::translate("QHttpServerExample",
                                        "Running on http://127.0.0.1:%1/ and "
                                        "https://127.0.0.1:%2/ (Press CTRL+C to quit)")
            .arg(port).arg(sslPort);
 #else
     qInfo().noquote()
         << QCoreApplication::translate("QHttpServerExample",
                                        "Running on http://127.0.0.1:%1/"
                                        "(Press CTRL+C to quit)").arg(port);
 #endif
     return app.exec();
 }