1 // Copyright (c) 2011, Mike Samuel 2 // All rights reserved. 3 // 4 // Redistribution and use in source and binary forms, with or without 5 // modification, are permitted provided that the following conditions 6 // are met: 7 // 8 // Redistributions of source code must retain the above copyright 9 // notice, this list of conditions and the following disclaimer. 10 // Redistributions in binary form must reproduce the above copyright 11 // notice, this list of conditions and the following disclaimer in the 12 // documentation and/or other materials provided with the distribution. 13 // Neither the name of the OWASP nor the names of its contributors may 14 // be used to endorse or promote products derived from this software 15 // without specific prior written permission. 16 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 17 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 18 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 19 // FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 20 // COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 21 // INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, 22 // BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 23 // LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER 24 // CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25 // LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN 26 // ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 27 // POSSIBILITY OF SUCH DAMAGE. 28 29 package org.owasp.html; 30 31 import com.google.common.collect.ImmutableMap; 32 33 /** 34 * From section 8.1.2.6 of http://www.whatwg.org/specs/web-apps/current-work/ 35 * <p> 36 * The text in CDATA and RCDATA elements must not contain any 37 * occurrences of the string "</" (U+003C LESS-THAN SIGN, U+002F 38 * SOLIDUS) followed by characters that case-insensitively match the 39 * tag name of the element followed by one of U+0009 CHARACTER 40 * TABULATION, U+000A LINE FEED (LF), U+000B LINE TABULATION, U+000C 41 * FORM FEED (FF), U+0020 SPACE, U+003E GREATER-THAN SIGN (>), or 42 * U+002F SOLIDUS (/), unless that string is part of an escaping 43 * text span. 44 * </p> 45 * 46 * <p> 47 * See also 48 * http://www.whatwg.org/specs/web-apps/current-work/#cdata-rcdata-restrictions 49 * for the elements which fall in each category. 50 * </p> 51 * 52 * @author Mike Samuel <mikesamuel@gmail.com> 53 */ 54 public enum HtmlTextEscapingMode { 55 /** 56 * Normally escaped character data that breaks around comments and tags. 57 */ 58 PCDATA, 59 /** 60 * A span of text where HTML special characters are interpreted literally, 61 * as in a SCRIPT tag. 62 */ 63 CDATA, 64 /** 65 * Like {@link #CDATA} but only for certain browsers. 66 */ 67 CDATA_SOMETIMES, 68 /** 69 * A span of text and character entity references where HTML special 70 * characters are interpreted literally, as in a TITLE tag. 71 */ 72 RCDATA, 73 /** 74 * A span of text where HTML special characters are interpreted literally, 75 * where there is no end tag. PLAIN_TEXT runs until the end of the file. 76 */ 77 PLAIN_TEXT, 78 79 /** 80 * Cannot contain data. 81 */ 82 VOID, 83 ; 84 85 private static final ImmutableMap<String, HtmlTextEscapingMode> ESCAPING_MODES 86 = ImmutableMap.<String, HtmlTextEscapingMode>builder() 87 .put("iframe", CDATA) 88 // HTML5 does not treat listing as CDATA and treats XMP as deprecated, 89 // but HTML2 does at 90 // http://www.w3.org/MarkUp/1995-archive/NonStandard.html 91 // Listing is not supported by browsers. 92 .put("listing", CDATA_SOMETIMES) 93 .put("xmp", CDATA) 94 95 // Technically, noembed, noscript and noframes are CDATA_SOMETIMES but 96 // we can only be hurt by allowing tag content that looks like text so 97 // we treat them as regular.. 98 //.put("noembed", CDATA_SOMETIMES) 99 //.put("noframes", CDATA_SOMETIMES) 100 //.put("noscript", CDATA_SOMETIMES) 101 .put("comment", CDATA_SOMETIMES) // IE only 102 103 // Runs till end of file. 104 .put("plaintext", PLAIN_TEXT) 105 106 .put("script", CDATA) 107 .put("style", CDATA) 108 109 // Textarea and Title are RCDATA, not CDATA, so decode entity references. 110 .put("textarea", RCDATA) 111 .put("title", RCDATA) 112 113 // Nodes that can't contain content. 114 // http://www.w3.org/TR/html-markup/syntax.html#void-elements 115 .put("area", VOID) 116 .put("base", VOID) 117 .put("br", VOID) 118 .put("col", VOID) 119 .put("command", VOID) 120 .put("embed", VOID) 121 .put("hr", VOID) 122 .put("img", VOID) 123 .put("input", VOID) 124 .put("keygen", VOID) 125 .put("link", VOID) 126 .put("meta", VOID) 127 .put("param", VOID) 128 .put("source", VOID) 129 .put("track", VOID) 130 .put("wbr", VOID) 131 132 // EMPTY per http://www.w3.org/TR/REC-html32#basefont 133 .put("basefont", VOID) 134 .build(); 135 136 137 /** 138 * The mode used for content following a start tag with the given name. 139 */ getModeForTag(String canonTagName)140 public static HtmlTextEscapingMode getModeForTag(String canonTagName) { 141 HtmlTextEscapingMode mode = ESCAPING_MODES.get(canonTagName); 142 return mode != null ? mode : PCDATA; 143 } 144 145 /** 146 * True iff the content following the given tag allows escaping text 147 * spans: {@code <!--…-->} that escape even things that might 148 * be an end tag for the corresponding open tag. 149 */ allowsEscapingTextSpan(String canonTagName)150 public static boolean allowsEscapingTextSpan(String canonTagName) { 151 // <xmp> and <plaintext> do not admit escaping text spans. 152 return "style".equals(canonTagName) || "script".equals(canonTagName) 153 || "noembed".equals(canonTagName) || "noscript".equals(canonTagName) 154 || "noframes".equals(canonTagName); 155 } 156 157 /** 158 * True if content immediately following the start tag must be treated as 159 * special CDATA so that <'s are not treated as starting tags, comments 160 * or directives. 161 */ isTagFollowedByLiteralContent(String canonTagName)162 public static boolean isTagFollowedByLiteralContent(String canonTagName) { 163 HtmlTextEscapingMode mode = getModeForTag(canonTagName); 164 return mode != PCDATA && mode != VOID; 165 } 166 167 /** 168 * True iff the tag cannot contain any content -- will an HTML parser consider 169 * the element to have ended immediately after the start tag. 170 */ isVoidElement(String canonTagName)171 public static boolean isVoidElement(String canonTagName) { 172 return getModeForTag(canonTagName) == VOID; 173 } 174 } 175