Validate HTTPS requests manually in Qt WebEngine: A Step-by-Step Guide

Qt WebEngine is a powerful tool for building web-enabled applications, but when it comes to handling HTTPS requests, things can get a bit tricky. By default, Qt WebEngine uses the system’s SSL/TLS implementation to validate HTTPS requests, but sometimes you might need to take matters into your own hands. In this article, we’ll explore how to validate HTTPS requests manually in Qt WebEngine, and why you might want to do so.

Why Manual Validation?

There are several reasons why you might want to validate HTTPS requests manually in Qt WebEngine:

• Custom SSL/TLS implementation**: You might want to use a custom SSL/TLS implementation that’s not supported by the system.
• Tight control over SSL/TLS validation**: Manual validation gives you fine-grained control over the SSL/TLS validation process, allowing you to implement custom validation logic.
• Bypass system restrictions**: In some cases, the system’s SSL/TLS implementation might be too restrictive, and manual validation allows you to bypass these restrictions.

Qt WebEngine’s SSL/TLS Implementation

Before we dive into manual validation, let’s take a quick look at how Qt WebEngine handles SSL/TLS requests by default.

Qt WebEngine uses the QSslSocket class to handle SSL/TLS connections. When a web page requests an HTTPS resource, Qt WebEngine creates a QSslSocket object and initiates a connection to the server. The QSslSocket object then negotiates the SSL/TLS handshake with the server and verifies the server’s identity using the system’s SSL/TLS implementation.

Here’s some sample code to illustrate this process:

QWebEngineView view;
QUrl url("https://example.com");
view.load(url);

// Qt WebEngine creates a QSslSocket object
// and initiates a connection to the server
QSslSocket socket;
socket.connectToHostEncrypted(url.host(), 443);

// Qt WebEngine negotiates the SSL/TLS handshake
// and verifies the server's identity
socket.waitForEncrypted();

Manual Validation with Qt WebEngine

Now that we’ve covered the basics of Qt WebEngine’s SSL/TLS implementation, let’s explore how to validate HTTPS requests manually.

The key to manual validation is to use the QWebEngineUrlRequestInfo class, which provides information about the URL request, including the SSL/TLS connection.

Here’s an example of how to use QWebEngineUrlRequestInfo to validate an HTTPS request manually:

void ValidateHttpsRequest(QWebEngineUrlRequestInfo *info)
{
  // Get the QSslSocket object
  QSslSocket *socket = info->socket();

  // Check if the connection is encrypted
  if (!socket->isEncrypted()) {
    // Handle non-encrypted connection
    return;
  }

  // Get the SSL/TLS configuration
  QSslConfiguration config = socket->sslConfiguration();

  // Verify the server's identity
  if (!VerifyServerIdentity(config)) {
    // Handle invalid server identity
    return;
  }

  // Validate the SSL/TLS certificate
  if (!ValidateCertificate(config)) {
    // Handle invalid certificate
    return;
  }

  // If we reach this point, the SSL/TLS connection is valid
  // We can proceed with the request
  info->setValidationResult(QWebEngineUrlRequestInfo::ValidationResult::Success);
}

bool VerifyServerIdentity(QSslConfiguration config)
{
  // Custom server identity verification logic goes here
  // Return true if the server identity is valid, false otherwise
}

bool ValidateCertificate(QSslConfiguration config)
{
  // Custom SSL/TLS certificate validation logic goes here
  // Return true if the certificate is valid, false otherwise
}

In this example, we use the QWebEngineUrlRequestInfo class to get the QSslSocket object and check if the connection is encrypted. We then get the SSL/TLS configuration and verify the server’s identity and validate the SSL/TLS certificate using custom logic.

Function	Description
VerifyServerIdentity	Custom logic to verify the server’s identity
ValidateCertificate	Custom logic to validate the SSL/TLS certificate

Custom SSL/TLS Validation Logic

In the previous example, we used custom functions to verify the server’s identity and validate the SSL/TLS certificate. Here’s an example of how you might implement these functions:

bool VerifyServerIdentity(QSslConfiguration config)
{
  // Get the peer certificate
  QSslCertificate certificate = config.peerCertificate();

  // Check if the certificate is issued by a trusted CA
  if (!certificate.isSelfSigned() && !certificate.issuerInfo(QSslCertificate::Organization).isEmpty()) {
    return true;
  }

  // If we reach this point, the server identity is invalid
  return false;
}

bool ValidateCertificate(QSslConfiguration config)
{
  // Get the peer certificate
  QSslCertificate certificate = config.peerCertificate();

  // Check if the certificate is valid and not expired
  if (certificate.isValid() && !certificate.expiryDate().isNull()) {
    return true;
  }

  // If we reach this point, the certificate is invalid
  return false;
}

In this example, we use the QSslCertificate class to access the peer certificate and check if it’s issued by a trusted CA and if it’s valid and not expired.

Conclusion

Validating HTTPS requests manually in Qt WebEngine gives you fine-grained control over the SSL/TLS validation process, allowing you to implement custom validation logic that meets your specific needs. By using the QWebEngineUrlRequestInfo class and custom SSL/TLS validation logic, you can ensure that your application handles HTTPS requests securely and efficiently.

Remember to always prioritize security when handling HTTPS requests, and use manual validation only when necessary. With great power comes great responsibility, so make sure to test your custom validation logic thoroughly to avoid any security vulnerabilities.

That’s it for this article! I hope you found it informative and helpful. If you have any questions or comments, feel free to leave them below.

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