feat: Add https proxying

TESTING.md

@@ -52,6 +52,34 @@ curl -v --proxy http://localhost:8080 http://example.com/
 curl -v --proxy http://localhost:8080 https://example.com/
 ```
 
+### HTTPS Support
+
+The proxy now correctly supports HTTPS connections through the HTTP CONNECT method. When using HTTPS:
+
+1. The browser establishes a tunnel through the proxy to the destination server
+2. The proxy resolves the hostname using DoH
+3. All traffic is forwarded between the client and server without modification
+
+For secure browsing, you must:
+- Configure your browser to trust the connection (you may see certificate warnings)
+- Make sure your proxy settings are applied to both HTTP and HTTPS traffic
+
+### Verifying HTTPS Support
+
+To verify HTTPS support is working:
+
+1. Configure your browser to use the proxy
+2. Visit an HTTPS site like https://example.com
+3. Check the proxy logs for CONNECT requests
+4. You should see messages like:
+   ```
+   Proxying request to: example.com (port 443)
+   DoH response received, size: XXX bytes
+   Resolved example.com to XXX.XXX.XXX.XXX
+   ```
+
+If you see certificate warnings, this is normal - your browser is correctly verifying the security of the connection.
+
 ## Verifying DoH Functionality
 
 To verify that your proxy is using the DoH server for DNS resolution:
@@ -69,6 +97,25 @@ To verify that your proxy is using the DoH server for DNS resolution:
 2. **DNS resolution failures**: Check your internet connection and access to hnsdoh.com
 3. **Memory leaks**: For long-running tests, monitor memory usage to ensure proper cleanup
 
+## HTTP and HTTPS Troubleshooting
+
+If only HTTPS or only HTTP is working:
+
+### HTTP Issues
+- Ensure correct Host header extraction in HTTP requests
+- Try a simple curl command: `curl -v --proxy http://localhost:8080 http://example.com/`
+- Check proxy logs for any HTTP-specific errors
+- Verify that the proxy correctly forwards the entire HTTP request, including all headers
+
+### HTTPS Issues
+- HTTPS uses the CONNECT method which creates a tunnel without modifying content
+- Try a simple curl command: `curl -v --proxy http://localhost:8080 https://example.com/`
+- Certificate warnings are expected and don't indicate proxy failure
+- Ensure your browser's security settings allow connecting through the proxy
+
+### Common Fix for Both
+If either HTTP or HTTPS isn't working, you can restart the proxy server and try again with verbose logging enabled.
+
 ### Using Network Monitoring Tools
 
 You can use tools like Wireshark to monitor the traffic: