test previously untested global policy merging code in PolicyFactory

src/test/java/org/owasp/html/PolicyFactoryTest.java

@@ -0,0 +1,223 @@
+// Copyright (c) 2019, Mike Samuel
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions
+// are met:
+//
+// Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+// Redistributions in binary form must reproduce the above copyright
+// notice, this list of conditions and the following disclaimer in the
+// documentation and/or other materials provided with the distribution.
+// Neither the name of the OWASP nor the names of its contributors may
+// be used to endorse or promote products derived from this software
+// without specific prior written permission.
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+// FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+// COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+// INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+// BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+// LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+// CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+// LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+// ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+// POSSIBILITY OF SUCH DAMAGE.
+
+package org.owasp.html;
+
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+
+import org.junit.Test;
+
+import com.google.common.base.Joiner;
+
+import junit.framework.TestCase;
+
+@SuppressWarnings({ "javadoc" })
+public final class PolicyFactoryTest extends TestCase {
+
+  @Test
+  public static void testAnd() {
+    // Filters srcset to only contain URLs with the substring "foo"
+    PolicyFactory f = new HtmlPolicyBuilder()
+        .allowElements("img")
+        .allowAttributes("srcset")
+        .matching(new SubstringFilter("foo"))
+        .globally()
+        .allowStandardUrlProtocols()
+        .toFactory();
+    // Filters srcset to only contain URLs with the substring "bar"
+    PolicyFactory g = new HtmlPolicyBuilder()
+        .allowElements("img")
+        .allowAttributes("srcset")
+        .matching(new SubstringFilter("bar"))
+        .globally()
+        .allowStandardUrlProtocols()
+        .toFactory();
+
+    // The javascript URL will be allowed if the extra policies are not
+    // preserved.
+    String html = "<img"
+        + " srcset=\"/foo.png , /bar.png , javascript:alert('foobar') , /foobar.png\""
+        // title is not whitelisted.
+        + " title=Hi>!";
+
+    PolicyFactory[] factories = {
+        f,
+        g,
+        // Test that .and() intersects regardless of order.
+        f.and(g),
+        g.and(f),
+    };
+    String[] expectedOutputs = {
+        // f
+        "<img srcset=\"/foo.png , /foobar.png\" />",
+
+        // g
+        "<img srcset=\"/bar.png , /foobar.png\" />",
+
+        // f and g
+        "<img srcset=\"/foobar.png\" />",
+
+        // g and f
+        "<img srcset=\"/foobar.png\" />",
+    };
+    String[] expectedLogs = {
+        // f
+        ""
+        + "discardedAttributes img, [title]\n"
+        + "Handled IOException BANG\n",
+
+        // g
+        ""
+        + "discardedAttributes img, [title]\n"
+        + "Handled IOException BANG\n",
+
+        // f and g
+        ""
+        + "discardedAttributes img, [title]\n"
+        + "Handled IOException BANG\n",
+
+        // g and f
+        ""
+        + "discardedAttributes img, [title]\n"
+        + "Handled IOException BANG\n",
+    };
+
+    for (int i = 0; i < factories.length; ++i) {
+      PolicyFactory factory = factories[i];
+      String expectedOutput = expectedOutputs[i];
+      String expectedLog = expectedLogs[i];
+
+      // A dummy value that lets us check that context is properly threaded
+      // through joined policies.
+      final Object context = new Object();
+      // Collect events from callbacks.
+      final StringBuilder log = new StringBuilder();
+      // Collects output HTML.
+      final StringBuilder out = new StringBuilder();
+
+      // A noisy listener that logs.
+      HtmlChangeListener<Object> listener = new HtmlChangeListener<Object>() {
+
+        public void discardedTag(Object ctx, String elementName) {
+          assertEquals(context, ctx);
+          log.append("discardedTag " + elementName + "\n");
+        }
+
+        public void discardedAttributes(
+            Object ctx, String tagName, String... attributeNames) {
+          assertEquals(context, ctx);
+          log.append(
+              "discardedAttributes " + tagName
+              + ", " + Arrays.asList(attributeNames)
+              + "\n");
+        }
+
+      };
+
+      Handler<IOException> ioHandler = new Handler<IOException>() {
+
+        public void handle(IOException x) {
+          log.append("Handled IOException " + x.getMessage() + "\n");
+        }
+
+      };
+
+      // Should not be called.
+      Handler<String> badHtmlHandler = new Handler<String>() {
+
+        public void handle(String x) {
+          throw new AssertionError(x);
+        }
+
+      };
+
+      // Wraps out to throw when a '!' is written to test the ioHandler.
+      // There is a '!' at the end of the output.
+      Appendable throwingOut = new Appendable() {
+
+        public Appendable append(CharSequence csq) throws IOException {
+          return append(csq, 0, csq.length());
+        }
+
+        public Appendable append(CharSequence csq, int start, int end) throws IOException {
+          for (int j = start; j < end; ++j) {
+            if (csq.charAt(j) == '!') {
+              throw new IOException("BANG");
+            }
+          }
+          out.append(csq, start, end);
+          return this;
+        }
+
+        public Appendable append(char c) throws IOException {
+          if (c == '!') {
+            throw new IOException("BANG");
+          }
+          out.append(c);
+          return this;
+        }
+
+      };
+
+      HtmlStreamEventReceiver receiver = new HtmlStreamRenderer(
+          throwingOut, ioHandler, badHtmlHandler);
+      HtmlSanitizer.Policy policy = factory.apply(
+          receiver, listener, context);
+      HtmlSanitizer.sanitize(html, policy);
+
+      assertEquals(
+          "i:" + i,
+
+          "Out:\n" + expectedOutput + "\n\nLog:\n" + expectedLog,
+          "Out:\n" + out + "\n\nLog:\n" + log);
+    }
+  }
+
+  static final class SubstringFilter implements AttributePolicy {
+    final String substr;
+
+    SubstringFilter(String substr) {
+      this.substr = substr;
+    }
+
+    public String apply(
+        String elementName, String attributeName, String value) {
+      List<String> outParts = new ArrayList<String>();
+      for (String part : value.split(",")) {
+        part = part.trim();
+        if (part.contains(substr)) {
+          outParts.add(part);
+        }
+      }
+      return Joiner.on(" , ").join(outParts);
+    }
+  }
+}