support for variables in 'param-value' from properties file without depending on any 3rd party libs

README.md

@@ -6,7 +6,7 @@ This is an HTTP Proxy (aka gateway) in the form of a Java servlet.  An HTTP prox
 This is hardly the first proxy, so why did I write it and thus why might you use it?
 
  * It's simple -- a single source file implementation
- * It's tested -- have confidence it works [![Build Status](https://travis-ci.org/mitre/HTTP-Proxy-Servlet.png)](https://travis-ci.org/mitre/HTTP-Proxy-Servlet)
+ * It's tested -- have confidence it works [![Build Status](https://travis-ci.org/madhbhavikar/HTTP-Proxy-Servlet.svg?branch=master)](https://travis-ci.org/madhbhavikar/HTTP-Proxy-Servlet)
  * It's securable -- via Java EE web.xml or via a servlet filter such as [Spring-Security]([http://static.springsource.org/spring-security/site/)
  * It's extendible -- via simple class extension
  * It's embeddable -- into your Java web application making testing your app easier
@@ -37,7 +37,7 @@ HTTP POST. Other application parameters can be in your POSTed url-encoded-form s
 proxyArgs.
 
 Build & Installation
-------------
+--------------------
 
 Simply build the jar using "mvn package" at the command line.
 The jar is built to "target/smiley-http-proxy-servlet-VERSION.jar".
@@ -49,7 +49,7 @@ add this to your dependencies in your pom like so:
     <dependency>
         <groupId>org.mitre.dsmiley.httpproxy</groupId>
         <artifactId>smiley-http-proxy-servlet</artifactId>
-        <version>1.7</version>
+        <version>1.9.1</version>
     </dependency>
 
 Ivy and other dependency managers can be used as well.
@@ -136,4 +136,43 @@ proxy:
     solr:
         servlet_url: /solr/*
         target_url: http://solrserver:8983/solr
+```
+
+Here is an example of using the proxy with an externalized properties file `http-proxy.properties` and / or `http-proxy-override.properties` which would be plugged into the `web.xml` if it is available in the classpath:
+
+```xml
+    ...
+    <servlet>
+        <servlet-name>solr</servlet-name>
+        <servlet-class>org.mitre.dsmiley.httpproxy.ProxyServlet</servlet-class>
+        <init-param>
+          <param-name>targetUri</param-name>
+          <param-value>${some-url}</param-value>
+        </init-param>
+        <init-param>
+          <param-name>log</param-name>
+          <param-value>true</param-value>
+        </init-param>
+    </servlet>
+    ...
+```
+
+make sure you put **${**some-url**}** is used if you want to pickup values from the properties file.
+
+The properties file could be:
+
+**http-proxy.properties**:
+
+```properties
+some-url=http://www.cisco.com/{x-some-parameter}/someEndpoint
+```
+
+Assuming `x-some-parameter`  is a custom header parameter.
+
+If this property needs to be overridden for some reason for a different environment for example, then the override properties file could be:
+
+**http-proxy-override.properties**
+
+```properties
+some-url=http://www.cisco.com/someContext/someEndpoint
 ```

pom.xml

@@ -3,7 +3,7 @@
 
   <groupId>org.mitre.dsmiley.httpproxy</groupId>
   <artifactId>smiley-http-proxy-servlet</artifactId>
-  <version>1.9-SNAPSHOT</version>
+  <version>1.9.1</version>
   <packaging>jar</packaging>
 
   <name>Smiley's HTTP Proxy Servlet</name>
@@ -29,13 +29,25 @@
       <!-- I used to work for MITRE for many years but I don't anymore. -->
       <!--<organization>MITRE</organization>-->
     </developer>
+    <developer>
+      <name>Prasad Madhbhavikar</name>
+      <email>[email protected]</email>
+      <!-- Currently working with Cisco and the changes are as requested -->
+      <organization>Cisco</organization>
+    </developer>
+    <developer>
+      <name>Gourav Jangra</name>
+      <email>[email protected]</email>
+      <!-- Currently working with Cisco and the changes are as requested -->
+      <organization>Cisco</organization>
+    </developer>
   </developers>
 
   <scm>
     <url>https://github.com/dsmiley/HTTP-Proxy-Servlet</url>
     <connection>scm:git:https://[email protected]/dsmiley/HTTP-Proxy-Servlet.git</connection>
     <developerConnection>scm:git:[email protected]:dsmiley/HTTP-Proxy-Servlet.git</developerConnection>
-    <tag>HEAD</tag>
+    <tag>smiley-http-proxy-servlet-1.9</tag>
   </scm>
 
   <properties>

src/main/java/org/mitre/dsmiley/httpproxy/ProxyServlet.java

@@ -36,16 +36,13 @@
 import org.apache.http.message.BasicHttpRequest;
 import org.apache.http.message.HeaderGroup;
 import org.apache.http.params.BasicHttpParams;
+import org.apache.http.params.CoreConnectionPNames;
 import org.apache.http.params.HttpParams;
 import org.apache.http.util.EntityUtils;
 
-import javax.servlet.ServletException;
-import javax.servlet.http.Cookie;
-import javax.servlet.http.HttpServlet;
-import javax.servlet.http.HttpServletRequest;
-import javax.servlet.http.HttpServletResponse;
 import java.io.Closeable;
 import java.io.IOException;
+import java.io.InputStream;
 import java.io.OutputStream;
 import java.lang.reflect.Constructor;
 import java.net.HttpCookie;
@@ -54,6 +51,13 @@
 import java.util.Enumeration;
 import java.util.Formatter;
 import java.util.List;
+import java.util.Properties;
+
+import javax.servlet.ServletException;
+import javax.servlet.http.Cookie;
+import javax.servlet.http.HttpServlet;
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
 
 /**
  * An HTTP reverse proxy/gateway servlet. It is designed to be extended for customization
@@ -112,6 +116,8 @@ public class ProxyServlet extends HttpServlet {
 
   private HttpClient proxyClient;
 
+  private Properties configurationProperties = null;
+
   @Override
   public String getServletInfo() {
     return "A proxy servlet by David Smiley, [email protected]";
@@ -131,7 +137,44 @@ protected HttpHost getTargetHost(HttpServletRequest servletRequest) {
    * it can be overridden.
    */
   protected String getConfigParam(String key) {
-    return getServletConfig().getInitParameter(key);
+    if(configurationProperties == null) {
+      configurationProperties = getConfigurationProperties();
+    }
+    return getValue(configurationProperties, getServletConfig().getInitParameter(key));
+  }
+
+  protected String getValue(Properties configurationProperties, String value){
+    if(value == null){
+      return value;
+    }
+    if(value.startsWith("${") && value.endsWith("}")){
+      String key = value.replaceAll("\\$\\{(.*)\\}", "$1");
+      return (String) configurationProperties.get(key);
+    }
+    return value;
+  }
+  protected Properties getConfigurationProperties()
+  {
+    Properties configurationProperties = new Properties();
+    try
+    {
+      InputStream proxyPropertiesResource = Thread.currentThread().getContextClassLoader().getResourceAsStream("http-proxy.properties");
+      if (proxyPropertiesResource != null) {
+        configurationProperties.load(proxyPropertiesResource);
+      }
+    }
+    catch (IOException e) {}
+    Properties proxyOverrideProperties = new Properties();
+    try
+    {
+      InputStream proxyOverridePropertiesResource = Thread.currentThread().getContextClassLoader().getResourceAsStream("http-proxy-override.properties");
+      if (proxyOverridePropertiesResource != null) {
+        proxyOverrideProperties.load(proxyOverridePropertiesResource);
+      }
+    }
+    catch (IOException e) {}
+    configurationProperties.putAll(proxyOverrideProperties);
+    return configurationProperties;
   }
 
   @Override
@@ -161,6 +204,12 @@ public void init() throws ServletException {
     hcParams.setParameter(ClientPNames.COOKIE_POLICY, CookiePolicy.IGNORE_COOKIES);
     hcParams.setBooleanParameter(ClientPNames.HANDLE_REDIRECTS, false); // See #70
     readConfigParam(hcParams, ClientPNames.HANDLE_REDIRECTS, Boolean.class);
+    readConfigParam(hcParams, ClientPNames.ALLOW_CIRCULAR_REDIRECTS, Boolean.class);
+    readConfigParam(hcParams, "http.conn-manager.timeout", Integer.class);
+    readConfigParam(hcParams, ClientPNames.MAX_REDIRECTS, Integer.class);
+    readConfigParam(hcParams, CoreConnectionPNames.CONNECTION_TIMEOUT, Integer.class);
+    readConfigParam(hcParams, CoreConnectionPNames.SO_TIMEOUT, Integer.class);
+    readConfigParam(hcParams, CoreConnectionPNames.STALE_CONNECTION_CHECK, Boolean.class);
     proxyClient = createHttpClient(hcParams);
   }
 
@@ -650,6 +699,10 @@ protected static CharSequence encodeUriQuery(CharSequence in) {
         formatter.format("%%%02X",(int)c);//TODO
       }
     }
+
+    if(formatter!= null){
+      formatter.close();
+    }
     return outBuf != null ? outBuf : in;
   }
 

src/main/java/org/mitre/dsmiley/httpproxy/URITemplateProxyServlet.java

@@ -20,18 +20,20 @@
 import org.apache.http.client.utils.URIUtils;
 import org.apache.http.client.utils.URLEncodedUtils;
 
-import javax.servlet.ServletException;
-import javax.servlet.http.HttpServletRequest;
-import javax.servlet.http.HttpServletResponse;
 import java.io.IOException;
 import java.net.URI;
 import java.net.URISyntaxException;
+import java.util.Enumeration;
 import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 
+import javax.servlet.ServletException;
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+
 /**
  * A proxy servlet in which the target URI is templated from incoming request parameters. The
  * format adheres to the <a href="http://tools.ietf.org/html/rfc6570">URI Template RFC</a>, "Level
@@ -55,7 +57,7 @@ public class URITemplateProxyServlet extends ProxyServlet {
   * But that's not how the spec works. So for now we will require a proxy arg to be present
   * if defined for this proxy URL.
   */
-  protected static final Pattern TEMPLATE_PATTERN = Pattern.compile("\\{([a-zA-Z0-9_%.]+)\\}");
+  protected static final Pattern TEMPLATE_PATTERN = Pattern.compile("\\{([a-zA-Z0-9_%-.]+)\\}");
   private static final String ATTR_QUERY_STRING =
           URITemplateProxyServlet.class.getSimpleName() + ".queryString";
 
@@ -100,14 +102,19 @@ protected void service(HttpServletRequest servletRequest, HttpServletResponse se
       params.put(pair.getName(), pair.getValue());
     }
 
+    LinkedHashMap<String, String> specialHeaders = getVariablesFromRequestHeaders(servletRequest);
+
     //Now rewrite the URL
     StringBuffer urlBuf = new StringBuffer();//note: StringBuilder isn't supported by Matcher
     Matcher matcher = TEMPLATE_PATTERN.matcher(targetUriTemplate);
     while (matcher.find()) {
       String arg = matcher.group(1);
       String replacement = params.remove(arg);//note we remove
       if (replacement == null) {
-        throw new ServletException("Missing HTTP parameter "+arg+" to fill the template");
+        replacement = specialHeaders.get(arg);
+        if (replacement == null) {
+            throw new ServletException("Missing HTTP parameter " + arg + " to fill the template");
+        }
       }
       matcher.appendReplacement(urlBuf, replacement);
     }
@@ -140,4 +147,16 @@ protected void service(HttpServletRequest servletRequest, HttpServletResponse se
   protected String rewriteQueryStringFromRequest(HttpServletRequest servletRequest, String queryString) {
     return (String) servletRequest.getAttribute(ATTR_QUERY_STRING);
   }
+
+    private LinkedHashMap<String, String> getVariablesFromRequestHeaders(HttpServletRequest servletRequest) {
+        LinkedHashMap<String, String> specialHeaders = new LinkedHashMap<>();
+        Enumeration headerNames = servletRequest.getHeaderNames();
+
+        while (headerNames.hasMoreElements()) {
+            String headerName = (String) headerNames.nextElement();
+            specialHeaders.put(headerName, servletRequest.getHeader(headerName));
+        }
+
+        return specialHeaders;
+    }
 }