From 12eba881887c604a86532f2f174a2dde8d3385c1 Mon Sep 17 00:00:00 2001
From: Joe Bandenburg <joe@bandenburg.com>
Date: Fri, 19 Apr 2024 16:41:19 -0400
Subject: [PATCH] [cdp][java] Allow filters to recover from failed requests in
 NetworkInterceptor

This change introduces a new exception, which is thrown through the
user's filter chain when the browser fails to get a response for a
request and a NetworkInterceptor is in use.

This gives the filter an opportunity to catch the exception and
return a custom HTTP response.

Related to #13774
---
 .../devtools/RequestFailedException.java      | 13 +++++++++++++
 .../selenium/devtools/idealized/Network.java  | 18 ++++++++++++++++--
 .../devtools/NetworkInterceptorTest.java      | 19 ++++++++++++++++++-
 3 files changed, 47 insertions(+), 3 deletions(-)
 create mode 100644 java/src/org/openqa/selenium/devtools/RequestFailedException.java

diff --git a/java/src/org/openqa/selenium/devtools/RequestFailedException.java b/java/src/org/openqa/selenium/devtools/RequestFailedException.java
new file mode 100644
index 00000000000000..74add97500ee73
--- /dev/null
+++ b/java/src/org/openqa/selenium/devtools/RequestFailedException.java
@@ -0,0 +1,13 @@
+package org.openqa.selenium.devtools;
+
+import org.openqa.selenium.WebDriverException;
+import org.openqa.selenium.remote.http.Filter;
+import org.openqa.selenium.remote.http.HttpHandler;
+
+/**
+ * This exception is thrown by the final {@link HttpHandler} in a {@link Filter} chain when the
+ * browser fails to send a HTTP request. It can be caught in a {@link Filter} to handle the error
+ * by, for example, returning a custom HTTP response.
+ */
+public class RequestFailedException extends WebDriverException {
+}
diff --git a/java/src/org/openqa/selenium/devtools/idealized/Network.java b/java/src/org/openqa/selenium/devtools/idealized/Network.java
index 2c09e877a79736..ec36b5d40d5d05 100644
--- a/java/src/org/openqa/selenium/devtools/idealized/Network.java
+++ b/java/src/org/openqa/selenium/devtools/idealized/Network.java
@@ -45,6 +45,7 @@
 import org.openqa.selenium.devtools.DevToolsException;
 import org.openqa.selenium.devtools.Event;
 import org.openqa.selenium.devtools.NetworkInterceptor;
+import org.openqa.selenium.devtools.RequestFailedException;
 import org.openqa.selenium.internal.Either;
 import org.openqa.selenium.internal.Require;
 import org.openqa.selenium.remote.http.Contents;
@@ -202,8 +203,12 @@ public void prepareToInterceptTraffic() {
             String id = getRequestId(pausedRequest);
 
             if (hasErrorResponse(pausedRequest)) {
-              pendingResponses.remove(id);
-              devTools.send(continueWithoutModification(pausedRequest));
+              CompletableFuture<HttpResponse> future = pendingResponses.remove(id);
+              if (future == null) {
+                devTools.send(continueWithoutModification(pausedRequest));
+              } else {
+                future.completeExceptionally(new RequestFailedException());
+              }
               return;
             }
 
@@ -244,6 +249,11 @@ public void prepareToInterceptTraffic() {
                             pendingResponses.remove(id);
                             return STOP_PROCESSING;
                           } catch (ExecutionException e) {
+                            if (e.getCause() instanceof RequestFailedException) {
+                              // Throwing here will give the user's filter a chance to intercept
+                              // the failure and handle it.
+                              throw (RequestFailedException) e.getCause();
+                            }
                             if (fetchEnabled.get()) {
                               LOG.log(WARNING, e, () -> "Unable to process request");
                             }
@@ -261,6 +271,10 @@ public void prepareToInterceptTraffic() {
             }
 
             devTools.send(fulfillRequest(pausedRequest, forBrowser));
+          } catch (RequestFailedException e) {
+            // If the exception reaches here, we know the user's filter has not handled it and the
+            // browser should continue its normal error handling.
+            devTools.send(continueWithoutModification(pausedRequest));
           } catch (TimeoutException e) {
             if (fetchEnabled.get()) {
               throw e;
diff --git a/java/test/org/openqa/selenium/devtools/NetworkInterceptorTest.java b/java/test/org/openqa/selenium/devtools/NetworkInterceptorTest.java
index f916a1772c115b..361affcd732f16 100644
--- a/java/test/org/openqa/selenium/devtools/NetworkInterceptorTest.java
+++ b/java/test/org/openqa/selenium/devtools/NetworkInterceptorTest.java
@@ -254,11 +254,28 @@ void shouldHandleRedirects() {
 
   @Test
   @NoDriverBeforeTest
-  void shouldProceedAsNormalIfRequestResultInAnKnownError() {
+  void shouldProceedAsNormalIfRequestResultInAnKnownErrorAndExceptionNotCaughtByFilter() {
     Filter filter = next -> next;
     try (NetworkInterceptor ignored = new NetworkInterceptor(driver, filter)) {
       assertThatExceptionOfType(WebDriverException.class)
           .isThrownBy(() -> driver.get("http://localhost:" + PortProber.findFreePort()));
     }
   }
+
+  @Test
+  @NoDriverBeforeTest
+  void shouldPassResponseBackToBrowserIfRequestResultsInAnKnownErrorAndExceptionCaughtByFilter() {
+    Filter filter = next -> req -> {
+      try {
+        return next.execute(req);
+      } catch (RequestFailedException e) {
+        return new HttpResponse().setStatus(200).setContent(Contents.utf8String("Hello, World!"));
+      }
+    };
+    try (NetworkInterceptor ignored = new NetworkInterceptor(driver, filter)) {
+      driver.get("http://localhost:" + PortProber.findFreePort());
+      String body = driver.findElement(By.tagName("body")).getText();
+      assertThat(body).contains("Hello, World!");
+    }
+  }
 }