src/tests/org/owasp/html/CssFuzzerTest.java - platform/external/owasp/sanitizer - Git at Google

 // Copyright (c) 2013, 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.util.Arrays;
 import java.util.EnumMap;
 import java.util.Random;
 import java.util.regex.Pattern;

 import org.junit.Test;
 import org.owasp.html.CssTokens.TokenType;

 import com.google.common.collect.Maps;

 public class CssFuzzerTest extends FuzzyTestCase {

   private static final String[] TOKEN_PARTS = new String[] {
     "'", "\"", "<!--", "-->", "/*", "*/", "***", "//", "\r", "\n",
     "<", ">", "/", ",", ";", ":", "(", "url", "Url", ")", "[", "]", "{", "}",
     "\\", "\\a", "\\d", "\\0", " ", "\t", "42", ".", "ex", "auto", "foo", "BAr",
     "important", "!", "\ufeff", "\u0000", "\u00a0", "\ufffd", "\ud801\udc02",
     "\u007f", "\u000c", "CDATA", "style"
   };

   private static final String[] FREQUENT_TOKEN_PARTS = new String[] {
     "*/", " ", "\t", "\r", "\n",
   };

   private static final String[] DISALLOWED_IN_OUTPUT = {
     "</style", "<![CDATA[", "]]>", "\r", "\n",
   };

   final class Watcher implements Runnable {
     String input;
     long started;

     public void run() {
       synchronized (this) {
         try {
           while (true) {
             this.wait(1000 /* ms = 1s */);
             String input = this.input;
             if (input == null) { break; }  // Done
             long started = this.started;
             long now = System.nanoTime();
             if (now - started >= 1000000000L /* ns = 1s */) {
               System.err.println(
                   "`" + input + "` is slow. seed=" + CssFuzzerTest.this.seed);
             }
           }
         } catch (InterruptedException ex) {
           // Done
         }
       }
     }
   }

   @Test
   public final void testUnderStress() {
     Random r = this.rnd;
     Watcher watcher = new Watcher();
     Thread watcherThread = null;
     for (int run = 0, nRuns = (1 << 16); run < nRuns; ++run) {
       // Compose a random string from token parts.
       StringBuilder sb = new StringBuilder();
       int nParts = r.nextInt(64) + 16;
       for (int j = nParts; --j >= 0;) {
         int die = r.nextInt(32);
         switch (die) {
         case 0: sb.append((char) rnd.nextInt(0x80)); break;
         case 1: sb.append((char) rnd.nextInt(0x1800)); break;
         default:
           String[] arr = (die & 1) != 0 ? TOKEN_PARTS : FREQUENT_TOKEN_PARTS;
           sb.append(arr[rnd.nextInt(arr.length)]);
           break;
         }
       }
       String randomCss = sb.toString();

       synchronized (watcher) {
         watcher.input = randomCss;
         watcher.started = System.nanoTime();
       }
       if (watcherThread == null) {
         watcherThread = new Thread(watcher);
         watcherThread.setDaemon(true);
         watcherThread.start();
       }

       String msg = "seed=" + this.seed + ", css=`" + randomCss + "`";
       CssTokens tokens = CssTokens.lex(randomCss);

       // Test idempotent
       String renormalized = CssTokens.lex(tokens.normalizedCss).normalizedCss;
       if (!renormalized.equals(tokens.normalizedCss)) {
         if (!renormalized.equals(fixDigitSpaceUnit(tokens))) {
           for (CssTokens.TokenIterator it = tokens.iterator(); it.hasNext();
                it.advance()) {
             System.err.println(it.token() + ":" + it.type());
           }
           assertEquals(
               "not idempotent, " + msg,
               tokens.normalizedCss,
               renormalized);
         }
       }

       // Test normalized CSS does not contain HTML/XML breaking tokens.
       for (String disallowed : DISALLOWED_IN_OUTPUT) {
         assertFalse(
             "contains " + disallowed + ", " + msg,
             tokens.normalizedCss.contains(disallowed));
       }

       // Test that tokens are roughly well-formed.
       int nTokens = 0;
       for (CssTokens.TokenIterator it = tokens.iterator(); it.hasNext();) {
         CssTokens.TokenType type = it.type();
         String token = it.next();
         Pattern filter = TOKEN_TYPE_FILTERS.get(type);
         if (filter != null && !filter.matcher(token).matches()) {
           fail(type + " `" + token + "`, " + msg);
         }
         ++nTokens;
       }

       // Test that walking the bracket list works.
       int[] reverse = new int[nTokens];
       Arrays.fill(reverse, -1);
       for (int j = 0; j < nTokens; ++j) {
         int partner = tokens.brackets.partner(j);
         if (partner != -1) {
           reverse[partner] = j;
         }
       }
       for (int j = 0; j < nTokens; ++j) {
         if (reverse[j] != -1) {
           assertEquals(msg, reverse[reverse[j]], j);
         }
       }
     }
     synchronized (watcher) {
       watcher.input = null;
       watcher.notifyAll();
     }
   }

   private static final EnumMap<CssTokens.TokenType, Pattern> TOKEN_TYPE_FILTERS
     = Maps.newEnumMap(CssTokens.TokenType.class);
   static {
     String NUMBER = "-?(?:0|[1-9][0-9]*)(?:\\.[0-9]*[1-9])?(?:e-?[1-9][0-9]*)?";
     String IDENT_START = "[a-zA-Z_\\u0080-\udbff\udfff\\-]";
     String IDENT_PART = "(?:" + IDENT_START + "|[0-9])";
     String IDENT = IDENT_START + IDENT_PART + "*";
     TOKEN_TYPE_FILTERS.put(
         CssTokens.TokenType.AT, Pattern.compile("@" + IDENT));
     TOKEN_TYPE_FILTERS.put(
         CssTokens.TokenType.COLON, Pattern.compile(":"));
     TOKEN_TYPE_FILTERS.put(
         CssTokens.TokenType.COLUMN, Pattern.compile("\\|\\|"));
     TOKEN_TYPE_FILTERS.put(
         CssTokens.TokenType.COMMA, Pattern.compile(","));
     TOKEN_TYPE_FILTERS.put(
         CssTokens.TokenType.DELIM,
         Pattern.compile("[^\\w\u0000- \u0080-\uffff\\-]"));
     TOKEN_TYPE_FILTERS.put(
         CssTokens.TokenType.DIMENSION, Pattern.compile(NUMBER + "[a-z]+"));
     TOKEN_TYPE_FILTERS.put(
         CssTokens.TokenType.DOT_IDENT, Pattern.compile("\\." + IDENT));
     TOKEN_TYPE_FILTERS.put(
         CssTokens.TokenType.FUNCTION, Pattern.compile(IDENT + "[(]"));
     TOKEN_TYPE_FILTERS.put(
         CssTokens.TokenType.HASH_ID, Pattern.compile("#" + IDENT_PART + "+"));
     TOKEN_TYPE_FILTERS.put(
         CssTokens.TokenType.HASH_UNRESTRICTED,
         Pattern.compile("#[a-fA-F0-9]+"));
     TOKEN_TYPE_FILTERS.put(
         CssTokens.TokenType.IDENT,
         Pattern.compile(IDENT));
     TOKEN_TYPE_FILTERS.put(
         CssTokens.TokenType.LEFT_CURLY,
         Pattern.compile("[{]"));
     TOKEN_TYPE_FILTERS.put(
         CssTokens.TokenType.LEFT_PAREN,
         Pattern.compile("[(]"));
     TOKEN_TYPE_FILTERS.put(
         CssTokens.TokenType.LEFT_SQUARE,
         Pattern.compile("[\\[]"));
     TOKEN_TYPE_FILTERS.put(
         CssTokens.TokenType.MATCH,
         Pattern.compile("[~^$|*]="));
     TOKEN_TYPE_FILTERS.put(
         CssTokens.TokenType.NUMBER,
         Pattern.compile(NUMBER));
     TOKEN_TYPE_FILTERS.put(
         CssTokens.TokenType.PERCENTAGE,
         Pattern.compile(NUMBER + "%"));
     TOKEN_TYPE_FILTERS.put(
         CssTokens.TokenType.RIGHT_CURLY,
         Pattern.compile("[}]"));
     TOKEN_TYPE_FILTERS.put(
         CssTokens.TokenType.RIGHT_PAREN,
         Pattern.compile("[)]"));
     TOKEN_TYPE_FILTERS.put(
         CssTokens.TokenType.RIGHT_SQUARE,
         Pattern.compile("[\\]]"));
     TOKEN_TYPE_FILTERS.put(
         CssTokens.TokenType.SEMICOLON,
         Pattern.compile(";"));
     TOKEN_TYPE_FILTERS.put(
         CssTokens.TokenType.STRING,
         Pattern.compile("'(?:[^'\r\n\\\\]|\\\\[^\r\n])*'"));
     TOKEN_TYPE_FILTERS.put(
         CssTokens.TokenType.UNICODE_RANGE,
         Pattern.compile("U\\+[0-9a-f]{1,6}(?:-[0-9a-f]{1,6}|\\?{0,5})?"));
     TOKEN_TYPE_FILTERS.put(
         CssTokens.TokenType.URL,
         Pattern.compile("url\\('[0-9A-Za-z\\-_.~:/?#\\[\\]@!$&+,;=%]*'\\)"));
     TOKEN_TYPE_FILTERS.put(
         CssTokens.TokenType.WHITESPACE,
         Pattern.compile(" "));
   }

   /**
    * "1:NUMBER ex:IDENT" -> "1ex:DIMENSION" is a common source source of
    * a-idempotency, but not one that causes problems in practice.
    * This hack helps ignore it.
    */
   static String fixDigitSpaceUnit(CssTokens tokens) {
     StringBuilder sb = new StringBuilder();
     for (CssTokens.TokenIterator it = tokens.iterator(); it.hasNext();) {
       if (it.type() != TokenType.NUMBER) {
         sb.append(it.next());
       } else {
         do {
           sb.append(it.next());
         } while (it.hasNext() && it.type() == TokenType.NUMBER);
         if (it.hasNext() && it.type() == TokenType.WHITESPACE) {
           it.advance();
           String numberFollower = null;
           if (it.hasNext()) {
             String token = it.token();
             switch (it.type()) {
               case IDENT:
                 if (CssTokens.isWellKnownUnit(token)) {
                   numberFollower = token;
                   it.advance();
                   if (it.hasNext() && it.token().startsWith(".")) {
                     numberFollower += " ";
                   }
                   it.backup();
                 }
                 break;
               case FUNCTION:
                 String name = token.substring(0, token.length() - 1);
                 if (CssTokens.isWellKnownUnit(name)) {
                   numberFollower = token;
                 }
                 break;
               case DELIM:
                 if ("%".equals(token)) {
                   numberFollower = token;
                 }
                 break;
               default: break;
             }
           }
           if (numberFollower == null) {
             sb.append(' ');
           } else {
             // Drop the space and append a lower-case version of the unit.
             sb.append(Strings.toLowerCase(numberFollower));
             it.advance();
           }
         }
       }
     }
     return sb.toString();
   }
 }
	// Copyright (c) 2013, 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.util.Arrays;
	import java.util.EnumMap;
	import java.util.Random;
	import java.util.regex.Pattern;

	import org.junit.Test;
	import org.owasp.html.CssTokens.TokenType;

	import com.google.common.collect.Maps;

	public class CssFuzzerTest extends FuzzyTestCase {

	private static final String[] TOKEN_PARTS = new String[] {
	"'", "\"", "<!--", "-->", "/", "/", "***", "//", "\r", "\n",
	"<", ">", "/", ",", ";", ":", "(", "url", "Url", ")", "[", "]", "{", "}",
	"\\", "\\a", "\\d", "\\0", " ", "\t", "42", ".", "ex", "auto", "foo", "BAr",
	"important", "!", "\ufeff", "\u0000", "\u00a0", "\ufffd", "\ud801\udc02",
	"\u007f", "\u000c", "CDATA", "style"
	};

	private static final String[] FREQUENT_TOKEN_PARTS = new String[] {
	"*/", " ", "\t", "\r", "\n",
	};

	private static final String[] DISALLOWED_IN_OUTPUT = {
	"</style", "<![CDATA[", "]]>", "\r", "\n",
	};

	final class Watcher implements Runnable {
	String input;
	long started;

	public void run() {
	synchronized (this) {
	try {
	while (true) {
	this.wait(1000 /* ms = 1s */);
	String input = this.input;
	if (input == null) { break; } // Done
	long started = this.started;
	long now = System.nanoTime();
	if (now - started >= 1000000000L /* ns = 1s */) {
	System.err.println(
	"`" + input + "` is slow. seed=" + CssFuzzerTest.this.seed);
	}
	}
	} catch (InterruptedException ex) {
	// Done
	}
	}
	}
	}

	@Test
	public final void testUnderStress() {
	Random r = this.rnd;
	Watcher watcher = new Watcher();
	Thread watcherThread = null;
	for (int run = 0, nRuns = (1 << 16); run < nRuns; ++run) {
	// Compose a random string from token parts.
	StringBuilder sb = new StringBuilder();
	int nParts = r.nextInt(64) + 16;
	for (int j = nParts; --j >= 0;) {
	int die = r.nextInt(32);
	switch (die) {
	case 0: sb.append((char) rnd.nextInt(0x80)); break;
	case 1: sb.append((char) rnd.nextInt(0x1800)); break;
	default:
	String[] arr = (die & 1) != 0 ? TOKEN_PARTS : FREQUENT_TOKEN_PARTS;
	sb.append(arr[rnd.nextInt(arr.length)]);
	break;
	}
	}
	String randomCss = sb.toString();

	synchronized (watcher) {
	watcher.input = randomCss;
	watcher.started = System.nanoTime();
	}
	if (watcherThread == null) {
	watcherThread = new Thread(watcher);
	watcherThread.setDaemon(true);
	watcherThread.start();
	}

	String msg = "seed=" + this.seed + ", css=`" + randomCss + "`";
	CssTokens tokens = CssTokens.lex(randomCss);

	// Test idempotent
	String renormalized = CssTokens.lex(tokens.normalizedCss).normalizedCss;
	if (!renormalized.equals(tokens.normalizedCss)) {
	if (!renormalized.equals(fixDigitSpaceUnit(tokens))) {
	for (CssTokens.TokenIterator it = tokens.iterator(); it.hasNext();
	it.advance()) {
	System.err.println(it.token() + ":" + it.type());
	}
	assertEquals(
	"not idempotent, " + msg,
	tokens.normalizedCss,
	renormalized);
	}
	}

	// Test normalized CSS does not contain HTML/XML breaking tokens.
	for (String disallowed : DISALLOWED_IN_OUTPUT) {
	assertFalse(
	"contains " + disallowed + ", " + msg,
	tokens.normalizedCss.contains(disallowed));
	}

	// Test that tokens are roughly well-formed.
	int nTokens = 0;
	for (CssTokens.TokenIterator it = tokens.iterator(); it.hasNext();) {
	CssTokens.TokenType type = it.type();
	String token = it.next();
	Pattern filter = TOKEN_TYPE_FILTERS.get(type);
	if (filter != null && !filter.matcher(token).matches()) {
	fail(type + " `" + token + "`, " + msg);
	}
	++nTokens;
	}

	// Test that walking the bracket list works.
	int[] reverse = new int[nTokens];
	Arrays.fill(reverse, -1);
	for (int j = 0; j < nTokens; ++j) {
	int partner = tokens.brackets.partner(j);
	if (partner != -1) {
	reverse[partner] = j;
	}
	}
	for (int j = 0; j < nTokens; ++j) {
	if (reverse[j] != -1) {
	assertEquals(msg, reverse[reverse[j]], j);
	}
	}
	}
	synchronized (watcher) {
	watcher.input = null;
	watcher.notifyAll();
	}
	}

	private static final EnumMap<CssTokens.TokenType, Pattern> TOKEN_TYPE_FILTERS
	= Maps.newEnumMap(CssTokens.TokenType.class);
	static {
	String NUMBER = "-?(?:0\|[1-9][0-9])(?:\\.[0-9][1-9])?(?:e-?[1-9][0-9]*)?";
	String IDENT_START = "[a-zA-Z_\\u0080-\udbff\udfff\\-]";
	String IDENT_PART = "(?:" + IDENT_START + "\|[0-9])";
	String IDENT = IDENT_START + IDENT_PART + "*";
	TOKEN_TYPE_FILTERS.put(
	CssTokens.TokenType.AT, Pattern.compile("@" + IDENT));
	TOKEN_TYPE_FILTERS.put(
	CssTokens.TokenType.COLON, Pattern.compile(":"));
	TOKEN_TYPE_FILTERS.put(
	CssTokens.TokenType.COLUMN, Pattern.compile("\\\|\\\|"));
	TOKEN_TYPE_FILTERS.put(
	CssTokens.TokenType.COMMA, Pattern.compile(","));
	TOKEN_TYPE_FILTERS.put(
	CssTokens.TokenType.DELIM,
	Pattern.compile("[^\\w\u0000- \u0080-\uffff\\-]"));
	TOKEN_TYPE_FILTERS.put(
	CssTokens.TokenType.DIMENSION, Pattern.compile(NUMBER + "[a-z]+"));
	TOKEN_TYPE_FILTERS.put(
	CssTokens.TokenType.DOT_IDENT, Pattern.compile("\\." + IDENT));
	TOKEN_TYPE_FILTERS.put(
	CssTokens.TokenType.FUNCTION, Pattern.compile(IDENT + "[(]"));
	TOKEN_TYPE_FILTERS.put(
	CssTokens.TokenType.HASH_ID, Pattern.compile("#" + IDENT_PART + "+"));
	TOKEN_TYPE_FILTERS.put(
	CssTokens.TokenType.HASH_UNRESTRICTED,
	Pattern.compile("#[a-fA-F0-9]+"));
	TOKEN_TYPE_FILTERS.put(
	CssTokens.TokenType.IDENT,
	Pattern.compile(IDENT));
	TOKEN_TYPE_FILTERS.put(
	CssTokens.TokenType.LEFT_CURLY,
	Pattern.compile("[{]"));
	TOKEN_TYPE_FILTERS.put(
	CssTokens.TokenType.LEFT_PAREN,
	Pattern.compile("[(]"));
	TOKEN_TYPE_FILTERS.put(
	CssTokens.TokenType.LEFT_SQUARE,
	Pattern.compile("[\\[]"));
	TOKEN_TYPE_FILTERS.put(
	CssTokens.TokenType.MATCH,
	Pattern.compile("[~^$\|*]="));
	TOKEN_TYPE_FILTERS.put(
	CssTokens.TokenType.NUMBER,
	Pattern.compile(NUMBER));
	TOKEN_TYPE_FILTERS.put(
	CssTokens.TokenType.PERCENTAGE,
	Pattern.compile(NUMBER + "%"));
	TOKEN_TYPE_FILTERS.put(
	CssTokens.TokenType.RIGHT_CURLY,
	Pattern.compile("[}]"));
	TOKEN_TYPE_FILTERS.put(
	CssTokens.TokenType.RIGHT_PAREN,
	Pattern.compile("[)]"));
	TOKEN_TYPE_FILTERS.put(
	CssTokens.TokenType.RIGHT_SQUARE,
	Pattern.compile("[\\]]"));
	TOKEN_TYPE_FILTERS.put(
	CssTokens.TokenType.SEMICOLON,
	Pattern.compile(";"));
	TOKEN_TYPE_FILTERS.put(
	CssTokens.TokenType.STRING,
	Pattern.compile("'(?:[^'\r\n\\\\]\|\\\\[^\r\n])*'"));
	TOKEN_TYPE_FILTERS.put(
	CssTokens.TokenType.UNICODE_RANGE,
	Pattern.compile("U\\+[0-9a-f]{1,6}(?:-[0-9a-f]{1,6}\|\\?{0,5})?"));
	TOKEN_TYPE_FILTERS.put(
	CssTokens.TokenType.URL,
	Pattern.compile("url\\('[0-9A-Za-z\\-_.~:/?#\\[\\]@!$&+,;=%]*'\\)"));
	TOKEN_TYPE_FILTERS.put(
	CssTokens.TokenType.WHITESPACE,
	Pattern.compile(" "));
	}

	/**
	* "1:NUMBER ex:IDENT" -> "1ex:DIMENSION" is a common source source of
	* a-idempotency, but not one that causes problems in practice.
	* This hack helps ignore it.
	*/
	static String fixDigitSpaceUnit(CssTokens tokens) {
	StringBuilder sb = new StringBuilder();
	for (CssTokens.TokenIterator it = tokens.iterator(); it.hasNext();) {
	if (it.type() != TokenType.NUMBER) {
	sb.append(it.next());
	} else {
	do {
	sb.append(it.next());
	} while (it.hasNext() && it.type() == TokenType.NUMBER);
	if (it.hasNext() && it.type() == TokenType.WHITESPACE) {
	it.advance();
	String numberFollower = null;
	if (it.hasNext()) {
	String token = it.token();
	switch (it.type()) {
	case IDENT:
	if (CssTokens.isWellKnownUnit(token)) {
	numberFollower = token;
	it.advance();
	if (it.hasNext() && it.token().startsWith(".")) {
	numberFollower += " ";
	}
	it.backup();
	}
	break;
	case FUNCTION:
	String name = token.substring(0, token.length() - 1);
	if (CssTokens.isWellKnownUnit(name)) {
	numberFollower = token;
	}
	break;
	case DELIM:
	if ("%".equals(token)) {
	numberFollower = token;
	}
	break;
	default: break;
	}
	}
	if (numberFollower == null) {
	sb.append(' ');
	} else {
	// Drop the space and append a lower-case version of the unit.
	sb.append(Strings.toLowerCase(numberFollower));
	it.advance();
	}
	}
	}
	}
	return sb.toString();
	}
	}