Correctly redirect legacy URIs with any final segment

URIs like `/c/1/123`, `/c/1/1..3` or ``/c/1/anyThing` currently returns a 404.
The legacy format, without project name in the URI,
is not correctly handled.

Handle it in the backend.

Bug: Issue 346377876
Bug: Issue 346618792
Release-Notes: skip
Change-Id: Id9fff1923a9c6e5cb3cbc458af5fbb9f0dd23af9

java/com/google/gerrit/httpd/NumericChangeIdRedirectServlet.java

diff --git a/java/com/google/gerrit/httpd/NumericChangeIdRedirectServlet.java b/java/com/google/gerrit/httpd/NumericChangeIdRedirectServlet.java
index 48dcea2..2c80c9b 100644
--- a/java/com/google/gerrit/httpd/NumericChangeIdRedirectServlet.java
+++ b/java/com/google/gerrit/httpd/NumericChangeIdRedirectServlet.java
@@ -14,6 +14,9 @@
 
 package com.google.gerrit.httpd;
 
+import static com.google.common.collect.ImmutableList.toImmutableList;
+
+import com.google.common.collect.ImmutableList;
 import com.google.gerrit.common.PageLinks;
 import com.google.gerrit.entities.Change;
 import com.google.gerrit.extensions.restapi.ResourceConflictException;
@@ -24,6 +27,7 @@
 import com.google.inject.Inject;
 import com.google.inject.Singleton;
 import java.io.IOException;
+import java.util.Arrays;
 import java.util.Optional;
 import javax.servlet.http.HttpServlet;
 import javax.servlet.http.HttpServletRequest;
@@ -54,13 +58,13 @@
   @Override
   protected void doGet(HttpServletRequest req, HttpServletResponse rsp) throws IOException {
     String uriPath = req.getPathInfo();
-    // Check if we are processing a comment url, like "/c/1/comment/ff3303fd_8341647b/".
-    int commentIdx = uriPath.indexOf("/comment");
-    String idString = commentIdx == -1 ? uriPath : uriPath.substring(0, commentIdx);
 
-    if (idString.endsWith("/")) {
-      idString = idString.substring(0, idString.length() - 1);
-    }
+    ImmutableList<String> uriSegments =
+        Arrays.stream(uriPath.split("/", 2)).collect(toImmutableList());
+
+    String idString = uriSegments.get(0);
+    String finalSegment = (uriSegments.size() > 1) ? uriSegments.get(1) : null;
+
     Optional<Change.Id> id = Change.Id.tryParse(idString);
     if (id.isEmpty()) {
       rsp.sendError(HttpServletResponse.SC_NOT_FOUND);
@@ -78,9 +82,8 @@
     }
     String path =
         PageLinks.toChange(changeResource.getProject(), changeResource.getChange().getId());
-    if (commentIdx > -1) {
-      // path already contain a trailing /, hence we start from "commentIdx + 1"
-      path = path + uriPath.substring(commentIdx + 1);
+    if (finalSegment != null) {
+      path += finalSegment;
     }
     UrlModule.toGerrit(path, req, rsp);
   }

java/com/google/gerrit/httpd/UrlModule.java

diff --git a/java/com/google/gerrit/httpd/UrlModule.java b/java/com/google/gerrit/httpd/UrlModule.java
index 7a100c7..aedf8e9 100644
--- a/java/com/google/gerrit/httpd/UrlModule.java
+++ b/java/com/google/gerrit/httpd/UrlModule.java
@@ -72,8 +72,7 @@
     serveRegex("^/settings/?$").with(screen(PageLinks.SETTINGS));
     serveRegex("^/register$").with(registerScreen(false));
     serveRegex("^/register/(.+)$").with(registerScreen(true));
-    serveRegex("^(?:/c)?/([1-9][0-9]*)/?$").with(NumericChangeIdRedirectServlet.class);
-    serveRegex("^(?:/c)?/([1-9][0-9]*)/comment/\\w+/?$").with(NumericChangeIdRedirectServlet.class);
+    serveRegex("^(?:/c)?/([1-9][0-9]*)/?.*$").with(NumericChangeIdRedirectServlet.class);
     serveRegex("^/p/(.*)$").with(queryProjectNew());
     serveRegex("^/r/(.+)/?$").with(DirectChangeByCommit.class);
 

javatests/com/google/gerrit/acceptance/rest/RestApiServletIT.java

diff --git a/javatests/com/google/gerrit/acceptance/rest/RestApiServletIT.java b/javatests/com/google/gerrit/acceptance/rest/RestApiServletIT.java
index 5c1f7c2..8011fb0 100644
--- a/javatests/com/google/gerrit/acceptance/rest/RestApiServletIT.java
+++ b/javatests/com/google/gerrit/acceptance/rest/RestApiServletIT.java
@@ -33,6 +33,7 @@
 import com.google.gerrit.extensions.restapi.Url;
 import com.google.gerrit.httpd.restapi.ParameterParser;
 import com.google.gerrit.httpd.restapi.RestApiServlet;
+import com.google.gerrit.server.query.change.ChangeData;
 import com.google.inject.Inject;
 import java.io.IOException;
 import java.util.regex.Pattern;
@@ -449,6 +450,19 @@
   }
 
   @Test
+  public void testNumericChangeIdWithExtraSegments() throws Exception {
+    ChangeData changeData = createChange().getChange();
+    int changeNumber = changeData.getId().get();
+
+    String finalSegment = "any/Thing";
+
+    String redirectUri = String.format("/c/%s/+/%d/%s", project.get(), changeNumber, finalSegment);
+    anonymousRestSession
+        .get(String.format("/c/%d/%s", changeNumber, finalSegment))
+        .assertTemporaryRedirect(redirectUri);
+  }
+
+  @Test
   public void testCommentLinkWithoutPrefixRedirects() throws Exception {
     int changeNumber = createChange().getChange().getId().get();
     String commentId = "ff3303fd_8341647b";