Tomcat example source code file (UDecoder.java)

This example Tomcat source code file (UDecoder.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Tomcat tags/keywords

allow_encoded_slash, bytechunk, charchunk, charchunk, charconversionexception, charconversionexception, eof, io, ioexception, ioexception, string, string, stringbuffer, udecoder, urldecoder

The Tomcat UDecoder.java source code

/*
 *  Licensed to the Apache Software Foundation (ASF) under one or more
 *  contributor license agreements.  See the NOTICE file distributed with
 *  this work for additional information regarding copyright ownership.
 *  The ASF licenses this file to You under the Apache License, Version 2.0
 *  (the "License"); you may not use this file except in compliance with
 *  the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */

package org.apache.tomcat.util.buf;

import java.io.CharConversionException;
import java.io.IOException;

/** 
 *  All URL decoding happens here. This way we can reuse, review, optimize
 *  without adding complexity to the buffers.
 *
 *  The conversion will modify the original buffer.
 * 
 *  @author Costin Manolache
 */
public final class UDecoder {
    
    private static org.apache.juli.logging.Log log=
        org.apache.juli.logging.LogFactory.getLog(UDecoder.class );
    
    protected static final boolean ALLOW_ENCODED_SLASH = 
        Boolean.valueOf(System.getProperty("org.apache.tomcat.util.buf.UDecoder.ALLOW_ENCODED_SLASH", "false")).booleanValue();

    public UDecoder() 
    {
    }

    /** URLDecode, will modify the source.  Includes converting
     *  '+' to ' '.
     */
    public void convert( ByteChunk mb )
        throws IOException
    {
        convert(mb, true);
    }

    /** URLDecode, will modify the source.
     */
    public void convert( ByteChunk mb, boolean query )
	throws IOException
    {
	int start=mb.getOffset();
	byte buff[]=mb.getBytes();
	int end=mb.getEnd();

	int idx= ByteChunk.indexOf( buff, start, end, '%' );
        int idx2=-1;
        if( query )
            idx2= ByteChunk.indexOf( buff, start, end, '+' );
	if( idx<0 && idx2<0 ) {
	    return;
	}

	// idx will be the smallest positive inxes ( first % or + )
	if( idx2 >= 0 && idx2 < idx ) idx=idx2;
	if( idx < 0 ) idx=idx2;

    boolean noSlash = !(ALLOW_ENCODED_SLASH || query);
    
	for( int j=idx; j<end; j++, idx++ ) {
	    if( buff[ j ] == '+' && query) {
		buff[idx]= (byte)' ' ;
	    } else if( buff[ j ] != '%' ) {
		buff[idx]= buff[j];
	    } else {
		// read next 2 digits
		if( j+2 >= end ) {
		    throw new CharConversionException("EOF");
		}
		byte b1= buff[j+1];
		byte b2=buff[j+2];
		if( !isHexDigit( b1 ) || ! isHexDigit(b2 ))
		    throw new CharConversionException( "isHexDigit");
		
		j+=2;
		int res=x2c( b1, b2 );
        if (noSlash && (res == '/')) {
            throw new CharConversionException( "noSlash");
        }
		buff[idx]=(byte)res;
	    }
	}

	mb.setEnd( idx );
	
	return;
    }

    // -------------------- Additional methods --------------------
    // XXX What do we do about charset ????

    /** In-buffer processing - the buffer will be modified
     *  Includes converting  '+' to ' '.
     */
    public void convert( CharChunk mb )
	throws IOException
    {
        convert(mb, true);
    }

    /** In-buffer processing - the buffer will be modified
     */
    public void convert( CharChunk mb, boolean query )
	throws IOException
    {
	//	log( "Converting a char chunk ");
	int start=mb.getOffset();
	char buff[]=mb.getBuffer();
	int cend=mb.getEnd();

	int idx= CharChunk.indexOf( buff, start, cend, '%' );
        int idx2=-1;
        if( query )
            idx2= CharChunk.indexOf( buff, start, cend, '+' );
	if( idx<0 && idx2<0 ) {
	    return;
	}
	
	if( idx2 >= 0 && idx2 < idx ) idx=idx2; 
	if( idx < 0 ) idx=idx2;

	for( int j=idx; j<cend; j++, idx++ ) {
	    if( buff[ j ] == '+' && query ) {
		buff[idx]=( ' ' );
	    } else if( buff[ j ] != '%' ) {
		buff[idx]=buff[j];
	    } else {
		// read next 2 digits
		if( j+2 >= cend ) {
		    // invalid
		    throw new CharConversionException("EOF");
		}
		char b1= buff[j+1];
		char b2=buff[j+2];
		if( !isHexDigit( b1 ) || ! isHexDigit(b2 ))
		    throw new CharConversionException("isHexDigit");
		
		j+=2;
		int res=x2c( b1, b2 );
		buff[idx]=(char)res;
	    }
	}
	mb.setEnd( idx );
    }

    /** URLDecode, will modify the source
     *  Includes converting  '+' to ' '.
     */
    public void convert(MessageBytes mb)
	throws IOException
    {
        convert(mb, true);
    }

    /** URLDecode, will modify the source
     */
    public void convert(MessageBytes mb, boolean query)
	throws IOException
    {
	
	switch (mb.getType()) {
	case MessageBytes.T_STR:
	    String strValue=mb.toString();
	    if( strValue==null ) return;
	    mb.setString( convert( strValue, query ));
	    break;
	case MessageBytes.T_CHARS:
	    CharChunk charC=mb.getCharChunk();
	    convert( charC, query );
	    break;
	case MessageBytes.T_BYTES:
	    ByteChunk bytesC=mb.getByteChunk();
	    convert( bytesC, query );
	    break;
	}
    }

    // XXX Old code, needs to be replaced !!!!
    // 
    public final String convert(String str)
    {
        return convert(str, true);
    }

    public final String convert(String str, boolean query)
    {
        if (str == null)  return  null;
	
	if( (!query || str.indexOf( '+' ) < 0) && str.indexOf( '%' ) < 0 )
	    return str;
	
        StringBuffer dec = new StringBuffer();    // decoded string output
        int strPos = 0;
        int strLen = str.length();

        dec.ensureCapacity(str.length());
        while (strPos < strLen) {
            int laPos;        // lookahead position

            // look ahead to next URLencoded metacharacter, if any
            for (laPos = strPos; laPos < strLen; laPos++) {
                char laChar = str.charAt(laPos);
                if ((laChar == '+' && query) || (laChar == '%')) {
                    break;
                }
            }

            // if there were non-metacharacters, copy them all as a block
            if (laPos > strPos) {
                dec.append(str.substring(strPos,laPos));
                strPos = laPos;
            }

            // shortcut out of here if we're at the end of the string
            if (strPos >= strLen) {
                break;
            }

            // process next metacharacter
            char metaChar = str.charAt(strPos);
            if (metaChar == '+') {
                dec.append(' ');
                strPos++;
                continue;
            } else if (metaChar == '%') {
		// We throw the original exception - the super will deal with
		// it
		//                try {
		dec.append((char)Integer.
			   parseInt(str.substring(strPos + 1, strPos + 3),16));
                strPos += 3;
            }
        }

        return dec.toString();
    }



    private static boolean isHexDigit( int c ) {
	return ( ( c>='0' && c<='9' ) ||
		 ( c>='a' && c<='f' ) ||
		 ( c>='A' && c<='F' ));
    }
    
    private static int x2c( byte b1, byte b2 ) {
	int digit= (b1>='A') ? ( (b1 & 0xDF)-'A') + 10 :
	    (b1 -'0');
	digit*=16;
	digit +=(b2>='A') ? ( (b2 & 0xDF)-'A') + 10 :
	    (b2 -'0');
	return digit;
    }

    private static int x2c( char b1, char b2 ) {
	int digit= (b1>='A') ? ( (b1 & 0xDF)-'A') + 10 :
	    (b1 -'0');
	digit*=16;
	digit +=(b2>='A') ? ( (b2 & 0xDF)-'A') + 10 :
	    (b2 -'0');
	return digit;
    }

    private final static int debug=0;
    private static void log( String s ) {
        if (log.isDebugEnabled())
            log.debug("URLDecoder: " + s );
    }

}