[HTTPCLIENT-1966] System Proxy - HTTP and SOCKS

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Not A Problem
• Affects Version/s: 4.5.5, 4.5.6
• Component/s: HttpClient (Windows)
• Assignee: Unassigned
• Reporter: Mikolaj Broniszewski
• Created: 24/Jan/19 12:50
• Updated: 19/Jun/20 20:14
• Resolved: 24/Jan/19 15:40

Description

Hello,

I have created a proxy server basing on squid solution. And I have hidden the server (Apache Tomcat 8) which I would like to access behind this proxy (it's not available from my local machine directly). Then, I have created an example project which only connects to this hidden server basing on Apache HttpClient libraries:

• org.apache.httpcomponents:httpcore:4.4.11
• org.apache.httpcomponents:httpclient:4.5.6

The code looks like:

public static void main(String ...args) throws Exception {
	System.setProperty("https.proxyHost", "<proxy_url>");
	System.setProperty("https.proxyPort", "<proxy_port>");
	System.setProperty("socksProxyHost", "<proxy_url>");
	System.setProperty("socksProxyPort", "<proxy_port>");

	URI uri = new URI("https://<hidden_server_url>");
	try (CloseableHttpClient build = HttpClientBuilder.create()
			.useSystemProperties()
			.build()) {
		final HttpUriRequest uriRequest = RequestBuilder.get()
				.setUri(uri)
				.build();
		try (CloseableHttpResponse response = build.execute(uriRequest)) {
			final StatusLine statusLine = response.getStatusLine();
			System.out.println(statusLine.toString());
		}
	}
}

Unfortunately, as squid does not support SOCKS protocol, opening socket and waiting for response hangs the program. I was thinking that maybe I'm basing on invalid server configuration however when using below code everything works fine for same system properties:

public static void main(String ...args) throws Exception {
	System.setProperty("https.proxyHost", "<proxy_url>");
	System.setProperty("https.proxyPort", "<proxy_port>");
	System.setProperty("socksProxyHost", "<proxy_url>");
	System.setProperty("socksProxyPort", "<proxy_port>");

	URI uri = new URI("https://<hidden_server_url>");
	try (InputStream stream = uri.toURL().openStream()){
		String s = IOUtils.toString(stream, "UTF-8");
		System.out.println(s != null);
	} catch (IOException e) {
		e.printStackTrace();
	}
}

So java itself handles it correctly. What is more if I simply remove the socksProxyHost and socksProxyPort settings, then Apache HttpClient connects correctly to the hidden server. I don't think that having both HTTPS proxy configuration and SOCKS is incorrect as according to Oracle documentation:

https://docs.oracle.com/javase/8/docs/technotes/guides/net/proxies.html

"Now, what happens when both a SOCKS proxy and a HTTP proxy are defined? Well the rule is that settings for higher level protocols, like HTTP or FTP, take precedence over SOCKS settings. So, in that particular case, when establishing a HTTP connection, the SOCKS proxy settings will be ignored and the HTTP proxy will be contacted. Let's look at an example:"

As in Apache HttpClient I'm using system properties (useSystemProperties) I would expect that it is handled the same as Oracle does (the SOCK proxy should be ignored). I also checked it for simple HTTP proxy (http.proxyHost, http.proxyPort) and it acts the same (fails).

Could you please help me with this issue?

Best regards,
Mikolaj Broniszewski