Stage1

examples/src/main/java/com/flipkart/gjex/examples/helloworld/filter/CustomHeaderHttpFilter.java

@@ -0,0 +1,41 @@
+package com.flipkart.gjex.examples.helloworld.filter;
+
+import com.flipkart.gjex.core.filter.RequestParams;
+import com.flipkart.gjex.core.filter.http.HttpFilter;
+
+import javax.inject.Named;
+import javax.servlet.ServletRequest;
+import javax.servlet.ServletResponse;
+import javax.servlet.http.HttpServletResponse;
+import java.util.Map;
+
+@Named("CustomHeaderHttpFilter")
+public class CustomHeaderHttpFilter extends HttpFilter {
+
+    @Override
+    public void doProcessRequest(ServletRequest servletRequest, RequestParams<Map<String, String>> requestParams) {
+        super.doProcessRequest(servletRequest, requestParams);
+    }
+
+    @Override
+    public void doProcessResponseHeaders(Map<String, String> responseHeaders) {
+        super.doProcessResponseHeaders(responseHeaders);
+    }
+
+    @Override
+    public void doProcessResponse(ServletResponse response) {
+        super.doProcessResponse(response);
+        HttpServletResponse httpServletResponse = (HttpServletResponse) response;
+        httpServletResponse.addHeader("x-custom-header", "custom-header-value");
+    }
+
+    @Override
+    public void doHandleException(Exception e) {
+        super.doHandleException(e);
+    }
+
+    @Override
+    public HttpFilter getInstance() {
+        return new CustomHeaderHttpFilter();
+    }
+}

examples/src/main/java/com/flipkart/gjex/examples/helloworld/guice/HelloWorldModule.java

@@ -16,9 +16,11 @@
 package com.flipkart.gjex.examples.helloworld.guice;
 
 import com.flipkart.gjex.core.filter.grpc.GrpcFilter;
+import com.flipkart.gjex.core.filter.http.HttpFilterParams;
 import com.flipkart.gjex.core.filter.http.JavaxFilterParams;
 import com.flipkart.gjex.core.tracing.TracingSampler;
 import com.flipkart.gjex.examples.helloworld.filter.AuthFilter;
+import com.flipkart.gjex.examples.helloworld.filter.CustomHeaderHttpFilter;
 import com.flipkart.gjex.examples.helloworld.filter.LoggingFilter;
 import com.flipkart.gjex.examples.helloworld.service.GreeterService;
 import com.flipkart.gjex.examples.helloworld.tracing.AllWhitelistTracingSampler;
@@ -54,7 +56,8 @@ protected void configure() {
 //        bind(AccessLogGrpcFilter.class).to(AccessLogTestFilter.class);
 		bind(TracingSampler.class).to(AllWhitelistTracingSampler.class);
 		bind(ResourceConfig.class).annotatedWith(Names.named("HelloWorldResourceConfig")).to(HelloWorldResourceConfig.class);
-    bind(JavaxFilterParams.class).annotatedWith(Names.named("ExampleJavaxFilter"))
-        .toInstance(JavaxFilterParams.builder().filter(new ExampleJavaxFilter()).pathSpec("/*").build());
+        bind(JavaxFilterParams.class).annotatedWith(Names.named("ExampleJavaxFilter")).toInstance(JavaxFilterParams.builder().filter(new ExampleJavaxFilter()).pathSpec("/*").build());
+        bind(HttpFilterParams.class).annotatedWith(Names.named("CustomHeaderHttpFilter")).toInstance(HttpFilterParams.builder().filter(new CustomHeaderHttpFilter()).pathSpec("/*").build());
+
 	}
 }

guice/build.gradle

@@ -66,6 +66,7 @@ dependencies {
     implementation 'org.eclipse.jetty:jetty-webapp:9.4.22.v20191022'
     implementation 'io.opentracing.brave:brave-opentracing:0.31.3'
     implementation 'io.zipkin.reporter2:zipkin-sender-okhttp3:2.7.7'
+    implementation 'commons-io:commons-io:2.16.1'
 
     implementation 'io.prometheus:prometheus-metrics-exporter-servlet-javax:1.2.0'
 

guice/src/main/java/com/flipkart/gjex/http/interceptor/FilterServletResponseWrapper.java

@@ -0,0 +1,69 @@
+package com.flipkart.gjex.http.interceptor;
+
+import javax.servlet.ServletOutputStream;
+import javax.servlet.WriteListener;
+import javax.servlet.http.HttpServletResponse;
+import javax.servlet.http.HttpServletResponseWrapper;
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.io.PrintWriter;
+
+public class FilterServletResponseWrapper extends HttpServletResponseWrapper {
+
+    ServletOutputStreamWrapper stream = new ServletOutputStreamWrapper();
+
+    /**
+     * Constructs a request object wrapping the given request.
+     *
+     * @param request
+     * @throws IllegalArgumentException if the request is null
+     */
+    public FilterServletResponseWrapper(HttpServletResponse request) {
+        super(request);
+    }
+
+    public ServletOutputStream getOutputStream() throws IOException
+    {
+        return stream;
+    }
+
+    public PrintWriter getWriter() throws IOException
+    {
+        return new PrintWriter(stream);
+    }
+
+    public byte[] getWrapperBytes()
+    {
+        return stream.getBytes();
+    }
+
+
+    static class ServletOutputStreamWrapper extends ServletOutputStream {
+
+        private final ByteArrayOutputStream out = new ByteArrayOutputStream();
+
+        public void write(int b) throws IOException {
+            out.write(b);
+        }
+
+        public byte[] getBytes() {
+            return out.toByteArray();
+        }
+
+        @Override
+        public boolean isReady() {
+            return true;
+        }
+
+        @Override
+        public void setWriteListener(WriteListener writeListener) {
+            try {
+                writeListener.onWritePossible();
+            } catch (IOException e) {
+                throw new RuntimeException(e);
+            }
+        }
+
+    }
+
+}

guice/src/main/java/com/flipkart/gjex/http/interceptor/HttpFilterInterceptor.java

@@ -4,24 +4,27 @@
 import com.flipkart.gjex.core.filter.http.HttpFilter;
 import com.flipkart.gjex.core.filter.http.HttpFilterParams;
 import org.eclipse.jetty.http.pathmap.ServletPathSpec;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 import javax.inject.Named;
 import javax.inject.Singleton;
-import javax.servlet.FilterChain;
-import javax.servlet.FilterConfig;
-import javax.servlet.ServletException;
-import javax.servlet.ServletRequest;
-import javax.servlet.ServletResponse;
+import javax.servlet.*;
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
 import java.io.IOException;
-import java.util.*;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+import java.util.Map;
 import java.util.stream.Collectors;
 
 @Singleton
 @Named("HttpFilterInterceptor")
 public class HttpFilterInterceptor implements javax.servlet.Filter {
 
+    private static final Logger logger = LoggerFactory.getLogger(HttpFilterInterceptor.class);
+
     private static class ServletPathFiltersHolder {
         ServletPathSpec spec;
         HttpFilter filter;
@@ -62,32 +65,42 @@ public void init(FilterConfig filterConfig) throws ServletException {}
     public final void doFilter(ServletRequest request, ServletResponse response,
                                FilterChain chain) throws IOException, ServletException {
 
-        List<HttpFilter> filters = new ArrayList<>();
         RequestParams.RequestParamsBuilder<Map<String,String>> requestParamsBuilder = RequestParams.builder();
-        try {
-            if (request instanceof HttpServletRequest){
-                HttpServletRequest httpServletRequest = (HttpServletRequest) request;
-                filters = getMatchingFilters(httpServletRequest.getRequestURI());
-
-                Map<String, String> headers = Collections.list(httpServletRequest.getHeaderNames())
-                    .stream().collect(Collectors.toMap(h -> h, httpServletRequest::getHeader));
-                requestParamsBuilder.metadata(headers);
-                requestParamsBuilder.clientIp(getClientIp(request));
-                requestParamsBuilder.method(httpServletRequest.getMethod());
-                requestParamsBuilder.resourcePath(getFullURL(httpServletRequest));
-            }
+
+        if (request instanceof HttpServletRequest && response instanceof HttpServletResponse) {
+            HttpServletRequest httpServletRequest = (HttpServletRequest) request;
+            HttpServletResponse httpServletResponse = (HttpServletResponse) response;
+
+            List<HttpFilter> filters = getMatchingFilters(httpServletRequest.getRequestURI());
+            Map<String, String> headers = Collections.list(httpServletRequest.getHeaderNames())
+                .stream().collect(Collectors.toMap(h -> h, httpServletRequest::getHeader));
+            requestParamsBuilder.metadata(headers);
+            requestParamsBuilder.clientIp(getClientIp(request));
+            requestParamsBuilder.method(httpServletRequest.getMethod());
+            requestParamsBuilder.resourcePath(getFullURL(httpServletRequest));
+
             RequestParams<Map<String, String>> requestParams = requestParamsBuilder.build();
-            filters.forEach(filter -> filter.doProcessRequest(request, requestParams));
-            chain.doFilter(request, response);
-        } finally {
-            if (response instanceof HttpServletResponse) {
-                HttpServletResponse httpServletResponse = (HttpServletResponse) response;
-                Map<String, String> headers = httpServletResponse.getHeaderNames()
+            FilterServletResponseWrapper responseWrapper = new FilterServletResponseWrapper(httpServletResponse);
+
+            try {
+                filters.forEach(filter -> filter.doProcessRequest(request, requestParams));
+                chain.doFilter(request, responseWrapper);
+                Map<String, String> responseHeaders = responseWrapper.getHeaderNames()
                     .stream().collect(Collectors.toMap(h -> h, httpServletResponse::getHeader));
-                filters.forEach(filter -> filter.doProcessResponseHeaders(headers));
+                filters.forEach(filter -> filter.doProcessResponseHeaders(responseHeaders));
+
+            } finally {
+                filters.forEach(filter -> filter.doProcessResponse(responseWrapper));
+                response.getOutputStream().write(responseWrapper.getWrapperBytes());
             }
-            filters.forEach(filter -> filter.doProcessResponse(response));
+
+        } else {
+            // For Unsupported request types, pass the request and response as is
+            chain.doFilter(request, response);
+            logger.warn("Unsupported request type {}, pass the request and response as is.", request.getClass());
         }
+
+
     }
 
     /**