Allow specifying a proxy for http API connections

Adds support for the client to connect to the server via an HTTP proxy.
Client examines the engine.http.proxyHost and engine.http.proxyPort
system properties to determine the proxy to use.

Closes #190 in OIE
Signed-off-by: Mitch Gaffigan <mitch.gaffigan@comcast.net>

Author: mgaffigan

server/src/com/mirth/connect/client/core/ServerConnection.java

@@ -36,6 +36,7 @@
 import org.apache.commons.lang3.StringUtils;
 import org.apache.http.Header;
 import org.apache.http.HttpEntity;
+import org.apache.http.HttpHost;
 import org.apache.http.HttpResponse;
 import org.apache.http.HttpStatus;
 import org.apache.http.StatusLine;
@@ -91,6 +92,8 @@ public class ServerConnection implements Connector {
     public static final String EXECUTE_TYPE_PROPERTY = "executeType";
     public static final String OPERATION_PROPERTY = "operation";
     public static final String CUSTOM_HEADERS_PROPERTY = "customHeaders";
+    private static final String PROXY_HOST_PROPERTY = "engine.http.proxyHost";
+    private static final String PROXY_PORT_PROPERTY = "engine.http.proxyPort";
 
     private static final int CONNECT_TIMEOUT = 10000;
     private static final int IDLE_TIMEOUT = 300000;
@@ -134,7 +137,21 @@ public ServerConnection(int timeout, String[] httpsProtocols, String[] httpsCiph
 
         cookieStore = new BasicCookieStore();
         socketConfig = SocketConfig.custom().setSoTimeout(timeout).build();
-        requestConfig = RequestConfig.custom().setConnectTimeout(CONNECT_TIMEOUT).setSocketTimeout(timeout).build();
+
+        RequestConfig.Builder requestConfigBuilder = RequestConfig.custom()
+            .setConnectTimeout(CONNECT_TIMEOUT)
+            .setSocketTimeout(timeout);
+
+        // If HTTP Proxy is set, configure it
+        String httpProxyHost = System.getProperty(PROXY_HOST_PROPERTY);
+        if (allowHTTP && StringUtils.isNotBlank(httpProxyHost)) {
+            String httpProxyPort = System.getProperty(PROXY_PORT_PROPERTY);
+            int proxyPort = StringUtils.isNotBlank(httpProxyPort) ? Integer.parseInt(httpProxyPort) : 8888;
+            logger.info("Using API HTTP Proxy {}:{}", httpProxyHost, proxyPort);
+            requestConfigBuilder.setProxy(new HttpHost(httpProxyHost, proxyPort));
+        }
+
+        requestConfig = requestConfigBuilder.build();
         keepAliveStrategy = new CustomKeepAliveStrategy();
 
         createClient();