src/main/org/owasp/html/ElementAndAttributePolicies.java

// Copyright (c) 2011, 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
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// 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
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// BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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package org.owasp.html;

import java.util.Map;
import com.google.common.collect.ImmutableMap;
import com.google.common.collect.Maps;
import javax.annotation.concurrent.Immutable;

/**
 * Encapsulates all the information needed by the
 * {@link ElementAndAttributePolicyBasedSanitizerPolicy} to sanitize one kind
 * of element.
 */
@Immutable
final class ElementAndAttributePolicies {
  final String elementName;
  final boolean isVoid;
  final ElementPolicy elPolicy;
  final ImmutableMap<String, AttributePolicy> attrPolicies;
  final boolean skipIfEmpty;

  ElementAndAttributePolicies(
      String elementName,
      ElementPolicy elPolicy,
      Map<? extends String, ? extends AttributePolicy>
        attrPolicies,
      boolean skipIfEmpty) {
    this.elementName = elementName;
    this.isVoid = HtmlTextEscapingMode.isVoidElement(elementName);
    this.elPolicy = elPolicy;
    this.attrPolicies = ImmutableMap.copyOf(attrPolicies);
    this.skipIfEmpty = skipIfEmpty;
  }

  ElementAndAttributePolicies and(ElementAndAttributePolicies p) {
    assert elementName.equals(p.elementName):
      elementName + " != " + p.elementName;
    ImmutableMap.Builder<String, AttributePolicy> joinedAttrPolicies
        = ImmutableMap.builder();
    for (Map.Entry<String, AttributePolicy> e : this.attrPolicies.entrySet()) {
      String attrName = e.getKey();
      AttributePolicy a = e.getValue();
      AttributePolicy b = p.attrPolicies.get(attrName);
      if (b != null) {
        a = AttributePolicy.Util.join(a, b);
      }
      joinedAttrPolicies.put(attrName, a);
    }
    for (Map.Entry<String, AttributePolicy> e : p.attrPolicies.entrySet()) {
      String attrName = e.getKey();
      if (!this.attrPolicies.containsKey(attrName)) {
        joinedAttrPolicies.put(attrName, e.getValue());
      }
    }

    // HACK: this is attempting to recognize when skipIfEmpty has been
    // explicitly set in HtmlPolicyBuilder and can only make a best effort at
    // that and is also too tightly coupled with HtmlPolicyBuilder.
    // Maybe go tri-state.
    boolean combinedSkipIfEmpty;
    if (HtmlPolicyBuilder.DEFAULT_SKIP_IF_EMPTY.contains(elementName)) {
      // Either policy explicitly opted out of skip if empty.
      combinedSkipIfEmpty = skipIfEmpty && p.skipIfEmpty;
    } else {
      // Either policy explicitly specified skip if empty.
      combinedSkipIfEmpty = skipIfEmpty || p.skipIfEmpty;
    }

    return new ElementAndAttributePolicies(
        elementName,
        ElementPolicy.Util.join(elPolicy, p.elPolicy),
        joinedAttrPolicies.build(),
        combinedSkipIfEmpty);
  }

  ElementAndAttributePolicies andGlobals(
      Map<String, AttributePolicy> globalAttrPolicies) {
    if (globalAttrPolicies.isEmpty()) { return this; }
    Map<String, AttributePolicy> anded = null;
    for (Map.Entry<String, AttributePolicy> e : this.attrPolicies.entrySet()) {
      String attrName = e.getKey();
      AttributePolicy globalAttrPolicy = globalAttrPolicies.get(attrName);
      if (globalAttrPolicy != null) {
        AttributePolicy attrPolicy = e.getValue();
        AttributePolicy joined = AttributePolicy.Util.join(
            attrPolicy, globalAttrPolicy);
        if (!joined.equals(attrPolicy)) {
          if (anded == null) {
            anded = Maps.newLinkedHashMap();
            anded.putAll(this.attrPolicies);
          }
          anded.put(attrName, joined);
        }
      }
    }
    for (Map.Entry<String, AttributePolicy> e : globalAttrPolicies.entrySet()) {
      String attrName = e.getKey();
      if (!this.attrPolicies.containsKey(attrName)) {
        if (anded == null) {
          anded = Maps.newLinkedHashMap();
          anded.putAll(this.attrPolicies);
        }
        anded.put(attrName, e.getValue());
      }
    }
    if (anded == null) { return this; }
    return new ElementAndAttributePolicies(
        elementName, elPolicy, anded, skipIfEmpty);
  }

}