Add http request filter extension point

To allow for integration of 3rd party server monitoring solutions,
Gitblit needs to expose an extension point for collecting http data.
diff --git a/src/main/java/WEB-INF/web.xml b/src/main/java/WEB-INF/web.xml
index cb483af..3a6c449 100644
--- a/src/main/java/WEB-INF/web.xml
+++ b/src/main/java/WEB-INF/web.xml
@@ -214,6 +214,15 @@
 		<url-pattern>/robots.txt</url-pattern>

 	</servlet-mapping>

 

+    <filter>

+		<filter-name>ProxyFilter</filter-name>

+		<filter-class>com.gitblit.servlet.ProxyFilter</filter-class>

+	</filter>

+	<filter-mapping>

+		<filter-name>ProxyFilter</filter-name>

+		<url-pattern>/*</url-pattern>

+	</filter-mapping>

+	

 	<!-- Git Access Restriction Filter

 		 <url-pattern> MUST match: 

 			* GitServlet

@@ -353,4 +362,4 @@
         <url-pattern>/*</url-pattern>

     </filter-mapping>

     

-</web-app>

+</web-app>
\ No newline at end of file
diff --git a/src/main/java/com/gitblit/dagger/DaggerFilter.java b/src/main/java/com/gitblit/dagger/DaggerFilter.java
index 1c73d4b..01c07a4 100644
--- a/src/main/java/com/gitblit/dagger/DaggerFilter.java
+++ b/src/main/java/com/gitblit/dagger/DaggerFilter.java
@@ -36,10 +36,10 @@
 	public final void init(FilterConfig filterConfig) throws ServletException {

 		ServletContext context = filterConfig.getServletContext();

 		ObjectGraph objectGraph = (ObjectGraph) context.getAttribute(DaggerContext.INJECTOR_NAME);

-		inject(objectGraph);

+		inject(objectGraph, filterConfig);

 	}

 

-	protected abstract void inject(ObjectGraph dagger);

+	protected abstract void inject(ObjectGraph dagger, FilterConfig filterConfig) throws ServletException;

 

 	@Override

 	public void destroy() {

diff --git a/src/main/java/com/gitblit/extensions/HttpRequestFilter.java b/src/main/java/com/gitblit/extensions/HttpRequestFilter.java
new file mode 100644
index 0000000..e3e330c
--- /dev/null
+++ b/src/main/java/com/gitblit/extensions/HttpRequestFilter.java
@@ -0,0 +1,49 @@
+/*
+ * Copyright 2014 gitblit.com.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.gitblit.extensions;
+
+import java.io.IOException;
+
+import javax.servlet.Filter;
+import javax.servlet.FilterChain;
+import javax.servlet.FilterConfig;
+import javax.servlet.ServletException;
+import javax.servlet.ServletRequest;
+import javax.servlet.ServletResponse;
+
+import ro.fortsoft.pf4j.ExtensionPoint;
+
+/**
+ * Extension point to intercept HTTP requests passing through the server.
+ *
+ * @author David Ostrovsky
+ * @since 1.6.0
+ *
+ */
+public abstract class HttpRequestFilter implements Filter, ExtensionPoint {
+
+	@Override
+	public void init(FilterConfig config) throws ServletException {
+	}
+
+	@Override
+	public void destroy() {
+	}
+
+	@Override
+	public abstract void doFilter(ServletRequest request, ServletResponse response,
+			FilterChain chain) throws IOException, ServletException;
+}
diff --git a/src/main/java/com/gitblit/servlet/AccessRestrictionFilter.java b/src/main/java/com/gitblit/servlet/AccessRestrictionFilter.java
index e6a0169..0e6d323 100644
--- a/src/main/java/com/gitblit/servlet/AccessRestrictionFilter.java
+++ b/src/main/java/com/gitblit/servlet/AccessRestrictionFilter.java
@@ -19,6 +19,7 @@
 import java.text.MessageFormat;

 

 import javax.servlet.FilterChain;

+import javax.servlet.FilterConfig;

 import javax.servlet.ServletException;

 import javax.servlet.ServletRequest;

 import javax.servlet.ServletResponse;

@@ -54,8 +55,8 @@
 	protected IRepositoryManager repositoryManager;

 

 	@Override

-	protected void inject(ObjectGraph dagger) {

-		super.inject(dagger);

+	protected void inject(ObjectGraph dagger, FilterConfig filterConfig) {

+		super.inject(dagger, filterConfig);

 		this.runtimeManager = dagger.get(IRuntimeManager.class);

 		this.repositoryManager = dagger.get(IRepositoryManager.class);

 	}

diff --git a/src/main/java/com/gitblit/servlet/AuthenticationFilter.java b/src/main/java/com/gitblit/servlet/AuthenticationFilter.java
index dd821ac..5710a4a 100644
--- a/src/main/java/com/gitblit/servlet/AuthenticationFilter.java
+++ b/src/main/java/com/gitblit/servlet/AuthenticationFilter.java
@@ -24,6 +24,7 @@
 import java.util.Map;

 

 import javax.servlet.FilterChain;

+import javax.servlet.FilterConfig;

 import javax.servlet.ServletException;

 import javax.servlet.ServletRequest;

 import javax.servlet.ServletResponse;

@@ -64,7 +65,7 @@
 	protected IAuthenticationManager authenticationManager;

 

 	@Override

-	protected void inject(ObjectGraph dagger) {

+	protected void inject(ObjectGraph dagger, FilterConfig filterConfig) {

 		this.authenticationManager = dagger.get(IAuthenticationManager.class);

 	}

 

diff --git a/src/main/java/com/gitblit/servlet/EnforceAuthenticationFilter.java b/src/main/java/com/gitblit/servlet/EnforceAuthenticationFilter.java
index 5fdccb7..c015021 100644
--- a/src/main/java/com/gitblit/servlet/EnforceAuthenticationFilter.java
+++ b/src/main/java/com/gitblit/servlet/EnforceAuthenticationFilter.java
@@ -19,6 +19,7 @@
 import java.text.MessageFormat;
 
 import javax.servlet.FilterChain;
+import javax.servlet.FilterConfig;
 import javax.servlet.ServletException;
 import javax.servlet.ServletRequest;
 import javax.servlet.ServletResponse;
@@ -53,7 +54,7 @@
 	private IAuthenticationManager authenticationManager;
 
 	@Override
-	protected void inject(ObjectGraph dagger) {
+	protected void inject(ObjectGraph dagger, FilterConfig filterConfig) {
 		this.settings = dagger.get(IStoredSettings.class);
 		this.authenticationManager = dagger.get(IAuthenticationManager.class);
 	}
diff --git a/src/main/java/com/gitblit/servlet/GitFilter.java b/src/main/java/com/gitblit/servlet/GitFilter.java
index f9c062d..bb3d321 100644
--- a/src/main/java/com/gitblit/servlet/GitFilter.java
+++ b/src/main/java/com/gitblit/servlet/GitFilter.java
@@ -17,6 +17,7 @@
 

 import java.text.MessageFormat;

 

+import javax.servlet.FilterConfig;

 import javax.servlet.http.HttpServletRequest;

 

 import com.gitblit.Constants.AccessRestrictionType;

@@ -53,8 +54,8 @@
 	private IFederationManager federationManager;

 

 	@Override

-	protected void inject(ObjectGraph dagger) {

-		super.inject(dagger);

+	protected void inject(ObjectGraph dagger, FilterConfig filterConfig) {

+		super.inject(dagger, filterConfig);

 		this.settings = dagger.get(IStoredSettings.class);

 		this.federationManager = dagger.get(IFederationManager.class);

 	}

diff --git a/src/main/java/com/gitblit/servlet/ProxyFilter.java b/src/main/java/com/gitblit/servlet/ProxyFilter.java
new file mode 100644
index 0000000..bfdc87f
--- /dev/null
+++ b/src/main/java/com/gitblit/servlet/ProxyFilter.java
@@ -0,0 +1,76 @@
+/*
+ * Copyright 2014 gitblit.com.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.gitblit.servlet;
+
+import java.io.IOException;
+import java.util.Iterator;
+import java.util.List;
+
+import javax.servlet.FilterChain;
+import javax.servlet.FilterConfig;
+import javax.servlet.ServletException;
+import javax.servlet.ServletRequest;
+import javax.servlet.ServletResponse;
+
+import com.gitblit.dagger.DaggerFilter;
+import com.gitblit.extensions.HttpRequestFilter;
+import com.gitblit.manager.IPluginManager;
+
+import dagger.ObjectGraph;
+
+/**
+ * A request filter than allows regsitered extension request filters to access
+ * request data.  The intended purpose is for server monitoring plugins.
+ *
+ * @author David Ostrovsky
+ * @since 1.6.0
+ */
+public class ProxyFilter extends DaggerFilter {
+	private List<HttpRequestFilter> filters;
+
+	@Override
+	protected void inject(ObjectGraph dagger, FilterConfig filterConfig) throws ServletException {
+		IPluginManager pluginManager = dagger.get(IPluginManager.class);
+		filters = pluginManager.getExtensions(HttpRequestFilter.class);
+		for (HttpRequestFilter f : filters) {
+			f.init(filterConfig);
+		}
+	}
+
+	@Override
+	public void doFilter(ServletRequest req, ServletResponse res, final FilterChain last)
+			throws IOException, ServletException {
+		final Iterator<HttpRequestFilter> itr = filters.iterator();
+		new FilterChain() {
+			@Override
+			public void doFilter(ServletRequest req, ServletResponse res) throws IOException,
+					ServletException {
+				if (itr.hasNext()) {
+					itr.next().doFilter(req, res, this);
+				} else {
+					last.doFilter(req, res);
+				}
+			}
+		}.doFilter(req, res);
+	}
+
+	@Override
+	public void destroy() {
+		for (HttpRequestFilter f : filters) {
+			f.destroy();
+		}
+	}
+}
diff --git a/src/main/java/com/gitblit/servlet/RpcFilter.java b/src/main/java/com/gitblit/servlet/RpcFilter.java
index e0b1a23..23bf956 100644
--- a/src/main/java/com/gitblit/servlet/RpcFilter.java
+++ b/src/main/java/com/gitblit/servlet/RpcFilter.java
@@ -19,6 +19,7 @@
 import java.text.MessageFormat;

 

 import javax.servlet.FilterChain;

+import javax.servlet.FilterConfig;

 import javax.servlet.ServletException;

 import javax.servlet.ServletRequest;

 import javax.servlet.ServletResponse;

@@ -53,8 +54,8 @@
 	private IRuntimeManager runtimeManager;

 

 	@Override

-	protected void inject(ObjectGraph dagger) {

-		super.inject(dagger);

+	protected void inject(ObjectGraph dagger, FilterConfig filterConfig) {

+		super.inject(dagger, filterConfig);

 		this.settings = dagger.get(IStoredSettings.class);

 		this.runtimeManager = dagger.get(IRuntimeManager.class);

 	}

diff --git a/src/main/java/com/gitblit/servlet/SyndicationFilter.java b/src/main/java/com/gitblit/servlet/SyndicationFilter.java
index 67a845e..78da47e 100644
--- a/src/main/java/com/gitblit/servlet/SyndicationFilter.java
+++ b/src/main/java/com/gitblit/servlet/SyndicationFilter.java
@@ -19,6 +19,7 @@
 import java.text.MessageFormat;

 

 import javax.servlet.FilterChain;

+import javax.servlet.FilterConfig;

 import javax.servlet.ServletException;

 import javax.servlet.ServletRequest;

 import javax.servlet.ServletResponse;

@@ -50,8 +51,8 @@
 	private IProjectManager projectManager;

 

 	@Override

-	protected void inject(ObjectGraph dagger) {

-		super.inject(dagger);

+	protected void inject(ObjectGraph dagger, FilterConfig filterConfig) {

+		super.inject(dagger, filterConfig);

 		this.runtimeManager = dagger.get(IRuntimeManager.class);

 		this.repositoryManager = dagger.get(IRepositoryManager.class);

 		this.projectManager = dagger.get(IProjectManager.class);

diff --git a/src/site/plugins_extensions.mkd b/src/site/plugins_extensions.mkd
index 60f8b47..e8b53d1 100644
--- a/src/site/plugins_extensions.mkd
+++ b/src/site/plugins_extensions.mkd
@@ -185,3 +185,23 @@
 }
 ```
 
+### Request Filter
+
+*SINCE 1.6.0*
+
+You can provide your own custom request filter by subclassing the *HttpRequestFilter* class.
+
+```java
+import com.gitblit.extensions.HttpRequestFilter;
+import ro.fortsoft.pf4j.Extension;
+
+@Extension
+public class MyRequestFilter extends HttpRequestFilter {
+
+    @Override
+    public void doFilter(ServletRequest request, ServletResponse response,
+            FilterChain chain) throws IOException, ServletException {
+    }
+}
+```
+