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=propertiesSupport)](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
@@ -15,7 +15,7 @@ I have seen many quick'n'dirty proxies posted in source form on the web such as
 
 This proxy depends on [Apache HttpClient](http://hc.apache.org/httpcomponents-client-ga/), which offers another point of extension for this proxy.  At some point I may write an alternative that uses the JDK and thus doesn't have any dependencies, which is desirable. In the mean time, you'll have to add the jar files for this and its dependencies:
 
-     +- org.apache.httpcomponents:httpclient:jar:4.2.5:compile
+     +- org.apache.httpcomponents:httpclient:jar:**4.5.2**:compile
         +- org.apache.httpcomponents:httpcore:jar:4.2.4:compile
         |  +- commons-logging:commons-logging:jar:1.1.1:compile
         |  \- commons-codec:commons-codec:jar:1.6:compile
@@ -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>prasad.madhbhavikar@gmail.com</email>
+      <!-- Currently working with Cisco and the changes are as requested -->
+      <organization>Cisco</organization>
+    </developer>
+    <developer>
+      <name>Gourav Jangra</name>
+      <email>jangra.gourav143@gmail.com</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://dsmiley@github.com/dsmiley/HTTP-Proxy-Servlet.git</connection>
     <developerConnection>scm:git:git@github.com: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, dsmiley@apache.org";
@@ -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;
+    }
 }