systelab / cpp-webserver-adapter

Library-agnostic API for C++ to work with a web server

C++ Web Server Adapter

This repository defines a library-agnostic API for C++ to work with a web server.

Supported features

• Server and client
• HTTP
• HTTPS
• Mutual SSL
• CORS
• Thread pool
• GZIP compression

Available implementations

• BoostAsioWebServerAdapter
• HttpLibWebServerAdapter

Usage

Use of this library begins with an instance of:

• systelab::web_server::IServerFactory class (for server features)
• systelab::web_server::IClientFactory class (for client features)

See documentation of selected implementation for details about how to build one.

HTTP server set up

Set up a new HTTP web server by providing a configuration object that specifies host address and port:

systelab::web_server::Configuration configuration;
configuration.setHostAddress("127.0.0.1");
configuration.setPort(8080);

systelab::web_server::IServerFactory& serverFactory = ...
std::unique_ptr<systelab::web_server::IServer> server = serverFactory.buildServer(configuration);

Then, register at least a web service by providing an instance of a class that implements the systelab::web_server::IWebService interface:

class MyWebService : public systelab::web_server::IWebService
{
    std::unique_ptr<systelab::web_server::Reply> execute(const systelab::web_server::Request& request)
    {
        std::unique_ptr<systelab::web_server::Reply> reply;
	
        if (canServiceHandleRequest(request))
        {
	          // Process request and build a reply
        }
	
        return reply;
    }
}

auto webService = std::make_unique<MyWebService>();
webServer->registerWebService(std::move(webService));

Finally, start the server calling the start() method:

webServer->start();

HTTPS

HTTPS can be enabled through the configuration object provided when creating the server. The systelab::web_server::SecurityConfiguration class allows defining the paths of the certificate files as follows:

systelab::web_server::Configuration configuration;
systelab::web_server::SecurityConfiguration& securityConfiguration = configuration.getSecurityConfiguration();
securityConfiguration.setHTTPSEnabled(true);
securityConfiguration.setServerCertificate("Server.cert");
securityConfiguration.setServerPrivateKey("Server.key");
securityConfiguration.setServerDHParam("Server.dhparam");

Additionally, support for specific TLS versions can be enabled/disabled:

securityConfiguration.setTLSv12Enabled(false);
securityConfiguration.setTLSv13Enabled(true);

By default only TLS v1.2 is enabled. TLS v1.3 needs to be enabled on demand because it is not supported before OpenSSL 1.1.1. Older TLS versions should be always disabled as they have known security vulnerabilities.

Mutual SSL

To enable use of mutual SSL, the path of the client certificate must be specified through the security configuration of the server:

systelab::web_server::SecurityConfiguration& securityConfiguration = configuration.getSecurityConfiguration();
securityConfiguration.setMutualSSLEnabled(true);
securityConfiguration.setClientCertificate("Client.cert");

CORS configuration

The CORS configuration of the server can be defined using the systelab::web_server::CORSConfiguration class:

systelab::web_server::Configuration configuration;
systelab::web_server::CORSConfiguration& corsConfiguration = configuration.getCORSConfiguration();
corsConfiguration.setEnabled(true);
corsConfiguration.setAllowedOrigins({"http://127.0.0.1:4200", "http://127.0.0.1:8082"});
corsConfiguration.setAllowedMethods({"GET", "POST", "PUT", "PATCH", "DELETE", "OPTIONS"});
corsConfiguration.setAllowedHeaders({"Origin", "Authorization", "Content-Type"});
corsConfiguration.setExposedHeaders({"Origin", "Authorization", "Content-Type"});
corsConfiguration.setMaxAge(1209600);
corsConfiguration.setAllowedCredentials(true);

Thread pool configuration

The size of the pool of threads dedicated to attend server requests can be specified using the configuration option:

systelab::web_server::Configuration configuration;
configuration.setThreadPoolSize(4);

GZIP compression

The server can be configured to automatically apply gzip compression to payload of replies by enabling the following configuration option:

systelab::web_server::Configuration configuration;
configuration.setGZIPCompressionEnabled(true);

HTTP/HTTPS client usage

Set up a new HTTP client by providing a server IP address and a port number:

systelab::web_server::IClientFactory& clientFactory = ...
std::unique_ptr<systelab::web_server::IClient> client = clientFactory.buildHTTPClient("127.0.0.1", 8080);

Similarly, an HTTPS client can be created as follows:

systelab::web_server::IClientFactory& clientFactory = ...
std::unique_ptr<systelab::web_server::IClient> client = clientFactory.buildHTTPSClient("localhost", 9090);

Then, the returned systelab::web_server::IClient object can be used to send requests to the server:

systelab::web_server::Request request;
request.setMethod("POST");
request.setURI("/rest/api/login"); 
request.setContent("PasswordGoesHere");
request.getHeaders().addHeader("Content-Type", "text/plain");

std::unique_ptr<Reply> reply = client->send(request);

systelab::web_server::Reply::StatusType status = reply->getStatus();
std::map<std::string, std::string> headers = reply->getHeaders();
std::string content = reply->getContent();