How to use OpenSSL in POCO C++ library correctly - c++

Question

According to the Specification in POCO assistant:
Initialize the NetSSL library, as well as the underlying OpenSSL
libraries, by calling Poco::Crypto::OpenSSLInitializer::initialize().
Should be called before using any class from the NetSSL library.
The NetSSL will be initialized automatically, through
Poco::Crypto::OpenSSLInitializer instances or similar mechanisms
when creating Context or SSLManager instances.
However, it is recommended to call initializeSSL()
in any case at application startup.
When I want to use HTTPSClientSession,do I have to construct an Application object first?
How can I use it in Client? Any guy can tell me ?Thank you very much!

Answer 1

Let's take Net/samples/httpget as an example, let's copy httpget/ as a new httpsget directory:
open Makefile, add "PocoNetSSL" to target_libs
replace 'HTTPClientSession' with 'HTTPSClientSession'
you need to create Poco::Net::Context for SSL use
replace 'HTTPClientSession session(uri.getHost(), uri.getPort());' with following two lines:
const Context::Ptr context = new Context(Context::CLIENT_USE, "", "", "", Context::VERIFY_NONE, 9, false, "ALL:!ADH:!LOW:!EXP:!MD5:#STRENGTH");
HTTPSClientSession session(uri.getHost(), uri.getPort(), context);
Summary:
add PocoNetSSL as a lib_depends
use Poco::Net::Context with HTTPSClientSession

Answer 2

No, you do not need the Application object. Here's a fully functional example:
$ httpsget https://httpbin.org/user-agent
{
"user-agent": "Poco HTTPSClientSession"
}
Code:
#include "Poco/StreamCopier.h"
#include "Poco/URI.h"
#include "Poco/Exception.h"
#include "Poco/SharedPtr.h"
#include "Poco/Net/SSLManager.h"
#include "Poco/Net/KeyConsoleHandler.h"
#include "Poco/Net/ConsoleCertificateHandler.h"
#include "Poco/Net/HTTPSClientSession.h"
#include "Poco/Net/HTTPRequest.h"
#include "Poco/Net/HTTPResponse.h"
#include <memory>
#include <iostream>
using namespace Poco;
using namespace Poco::Net;
class SSLInitializer {
public:
SSLInitializer() { Poco::Net::initializeSSL(); }
~SSLInitializer() { Poco::Net::uninitializeSSL(); }
};
int main(int argc, char** argv)
{
SSLInitializer sslInitializer;
SharedPtr<InvalidCertificateHandler> ptrCert = new ConsoleCertificateHandler(false);
Context::Ptr ptrContext = new Context(Context::CLIENT_USE, "", "", "rootcert.pem", Context::VERIFY_STRICT, 9, false, "ALL:!ADH:!LOW:!EXP:!MD5:#STRENGTH");
SSLManager::instance().initializeClient(0, ptrCert, ptrContext);
try
{
if (argc > 1)
{
URI uri(argv[1]);
HTTPSClientSession s(uri.getHost(), uri.getPort());
HTTPRequest request(HTTPRequest::HTTP_GET, uri.getPath());
request.set("user-agent", "Poco HTTPSClientSession");
s.sendRequest(request);
HTTPResponse response;
std::istream& rs = s.receiveResponse(response);
StreamCopier::copyStream(rs, std::cout);
}
}
catch (Exception& ex)
{
std::cout << ex.displayText() << std::endl;
return 1;
}
return 0;
}