Qt HTTP Server

Qt HTTP Server supports building HTTP server functionality into an application. Common use cases are exposing the application's functionality through REST APIs, or making devices in a trusted environment configurable also via HTTP. The limitations are described in Limitations & Security.

Overview

Qt HTTP Server provides building blocks for embedding a lightweight HTTP server based on RFC 2616 in an application. There are classes for the messages sent and received, and for the various parts of an HTTP server.

An HTTP server can be created by subclassing the QAbstractHttpServer class and overriding the handleRequest() function. The QAbstractHttpServer class provides functions for listening to incoming ports or binding to an existing QTcpServer. Dispatching to callables based on incoming URLs can be simplified by using the QHttpServerRouter class.

This can be simplified even further by using the QHttpServer class. The QHttpServer class is a subclass of QAbstractHttpServer and defines an overloaded route function to bind callables to different incoming URLs, and an afterRequest() function to process the response further.

Runtime logging can be configured as described here.

Limitations & Security

Qt HTTP Server does not have many of the more advanced features and optimizations that general-purpose HTTP servers have. It also has not seen the same scrutiny regarding various attack vectors over the network. Use Qt HTTP Server, therefore, only for local connections or in a trusted network, and do not expose the ports to the internet.

You can add HTTPS support as a basic security measure, though. If Qt is compiled with support for TLS, you can bind QAbstractHttpServer and its subclasses to a QSslServer object, providing Transport Layer Security handling. This can also be achieved by calling the QAbstractHttpServer::sslSetup() function before calling listen().

Using the Module

Using a Qt module requires linking against the module library, either directly or through other dependencies. Several build tools have dedicated support for this, including CMake and qmake.

Building with CMake

Use the find_package() command to locate the needed module components in the Qt6 package:

find_package(Qt6 REQUIRED COMPONENTS HttpServer)
target_link_libraries(mytarget PRIVATE Qt6::HttpServer)

See also the Build with CMake overview.

Building with qmake

To configure the module for building with qmake, add the module as a value of the QT variable in the project's .pro file:

QT += httpserver

Licenses

Qt HTTP Server is available under commercial licenses from The Qt Company. In addition, it is available under the GNU General Public License, version 3. See Qt Licensing for further details.

Reference

• Qt HTTP Server Logging
• C++ Classes

Examples

The module provides the following Examples as a guide to using the API.