From 0e2bfccd838ba597ea9028c1ddd523f4e2c938cf Mon Sep 17 00:00:00 2001
From: Ben Liblit <liblit@acm.org>
Date: Sat, 20 Sep 2025 17:09:49 -0400
Subject: [PATCH] Simplify a URL utility function

Personally, I'm skeptical of the nonstandard normalizations that
`relativeToAbsoluteUrl` initially applies to `urlFound`:  replacing
`\` with `/` and converting to lower case.  But that's what was done
before, presumably for good reason.

Note that the new implementation of `relativeToAbsoluteUrl` differs
from the old implementation in how it handles `..` in the interior of
the `urlFound` path.  The new implementation normalizes those away,
whereas the old implementation did not.  I'm OK with this change, so
I've updated the test suite accordingly.
---
 .../ibm/wala/cast/js/html/UrlManipulator.java | 56 ++-----------------
 .../wala/cast/js/html/UrlManipulatorTest.java |  2 +-
 2 files changed, 5 insertions(+), 53 deletions(-)

diff --git a/cast/js/src/main/java/com/ibm/wala/cast/js/html/UrlManipulator.java b/cast/js/src/main/java/com/ibm/wala/cast/js/html/UrlManipulator.java
index 40c67adbcd..04f37a6409 100644
--- a/cast/js/src/main/java/com/ibm/wala/cast/js/html/UrlManipulator.java
+++ b/cast/js/src/main/java/com/ibm/wala/cast/js/html/UrlManipulator.java
@@ -11,7 +11,6 @@
 package com.ibm.wala.cast.js.html;
 
 import java.net.MalformedURLException;
-import java.net.URI;
 import java.net.URISyntaxException;
 import java.net.URL;
 
@@ -25,57 +24,10 @@ public static URL relativeToAbsoluteUrl(String urlFound, URL context)
       throws MalformedURLException {
     urlFound = urlFound.replace("\\", "/").toLowerCase();
 
-    URI absoluteUri;
-    if (!isAbsoluteUrl(urlFound))
-      try {
-        if (urlFound.startsWith("//")) {
-          // create URL taking only the protocol from the context
-          String origHostAndPath = urlFound.substring(2); // removing "//"
-          String host;
-          String path;
-          int indexOf = origHostAndPath.indexOf('/');
-          if (indexOf > 0) {
-            host = origHostAndPath.substring(0, indexOf);
-            path = origHostAndPath.substring(indexOf);
-          } else {
-            host = origHostAndPath;
-            path = "";
-          }
-          absoluteUri = new URI(context.getProtocol(), host, path, null);
-        } else if (urlFound.startsWith("/")) {
-          // create URL taking the protocol and the host from the context
-          absoluteUri = new URI(context.getProtocol(), context.getHost(), urlFound, null);
-        } else {
-          // "concat" URL to context
-          int backDir = 0; // removing directories due to "../"
-          while (urlFound.startsWith("../")) {
-            urlFound = urlFound.substring(3);
-            backDir++;
-          }
-          StringBuilder contextPath = new StringBuilder();
-          String path = context.getPath().replace("\\", "/");
-          boolean isContextDirectory = path.endsWith("/");
-          String[] split = path.split("/");
-          // we are also removing last element in case of a directory
-          int rightTrimFromPath = (isContextDirectory ? 0 : 1) + backDir;
-
-          for (int i = 0; i < split.length - rightTrimFromPath; i++) {
-            contextPath.append(split[i]);
-            contextPath.append('/');
-          }
-          absoluteUri =
-              new URI(context.getProtocol(), context.getHost(), contextPath + urlFound, null);
-        }
-      } catch (URISyntaxException problem) {
-        throw new IllegalArgumentException(problem);
-      }
-    else {
-      absoluteUri = URI.create(urlFound);
+    try {
+      return context.toURI().resolve(urlFound).toURL();
+    } catch (final URISyntaxException problem) {
+      throw new IllegalArgumentException(problem);
     }
-    return absoluteUri.toURL();
-  }
-
-  private static boolean isAbsoluteUrl(String orig) {
-    return orig.startsWith("http");
   }
 }
diff --git a/cast/js/src/test/java/com/ibm/wala/cast/js/html/UrlManipulatorTest.java b/cast/js/src/test/java/com/ibm/wala/cast/js/html/UrlManipulatorTest.java
index 62848b6ef7..8c20fc4db8 100644
--- a/cast/js/src/test/java/com/ibm/wala/cast/js/html/UrlManipulatorTest.java
+++ b/cast/js/src/test/java/com/ibm/wala/cast/js/html/UrlManipulatorTest.java
@@ -111,7 +111,7 @@ public void testComplexRelativePath() {
     check(
         "https://example.com/dir/subdir/",
         "../../subdir2/resource/../../file",
-        "https://example.com/subdir2/resource/../../file");
+        "https://example.com/file");
   }
 
   @Test