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/*
 * Copyright 2005-2010 the original author or authors.
 *
 * Licensed 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.springframework.ldap.core;

import org.springframework.ldap.BadLdapGrammarException;

/**
 * Helper class to encode and decode ldap names and values.
 * 
 * @author Adam Skogman
 * @author Mattias Hellborg Arthursson
 */
public class LdapEncoder {

    private static String[] nameEscapeTable = new String[96];

    private static String[] filterEscapeTable = new String['\\' + 1];

    static {

        // Name encoding table -------------------------------------

        // all below 0x20 (control chars)
        for (char c = 0; c < ' '; c++) {
            nameEscapeTable[c] = "\\" + toTwoCharHex(c);
        }

        nameEscapeTable['#'] = "\\#";
        nameEscapeTable[','] = "\\,";
        nameEscapeTable[';'] = "\\;";
        nameEscapeTable['='] = "\\=";
        nameEscapeTable['+'] = "\\+";
        nameEscapeTable['<'] = "\\<";
        nameEscapeTable['>'] = "\\>";
        nameEscapeTable['\"'] = "\\\"";
        nameEscapeTable['\\'] = "\\\\";

        // Filter encoding table -------------------------------------

        // fill with char itself
        for (char c = 0; c < filterEscapeTable.length; c++) {
            filterEscapeTable[c] = String.valueOf(c);
        }

        // escapes (RFC2254)
        filterEscapeTable['*'] = "\\2a";
        filterEscapeTable['('] = "\\28";
        filterEscapeTable[')'] = "\\29";
        filterEscapeTable['\\'] = "\\5c";
        filterEscapeTable[0] = "\\00";

    }

    /**
     * All static methods - not to be instantiated.
     */
    private LdapEncoder() {
    }

    protected static String toTwoCharHex(char c) {

        String raw = Integer.toHexString(c).toUpperCase();

        if (raw.length() > 1)
            return raw;
        else
            return "0" + raw;
    }

    /**
     * Escape a value for use in a filter.
     * 
     * @param value
     *            the value to escape.
     * @return a properly escaped representation of the supplied value.
     */
    public static String filterEncode(String value) {

        if (value == null)
            return null;

        // make buffer roomy
        StringBuffer encodedValue = new StringBuffer(value.length() * 2);

        int length = value.length();

        for (int i = 0; i < length; i++) {

            char c = value.charAt(i);

            if (c < filterEscapeTable.length) {
                encodedValue.append(filterEscapeTable[c]);
            } else {
                // default: add the char
                encodedValue.append(c);
            }
        }

        return encodedValue.toString();
    }

    /**
     * LDAP Encodes a value for use with a DN. Escapes for LDAP, not JNDI!
     * 
     * 
Escapes:
' ' [space] - "\ " [if first or last]
'#' * [hash] - "\#"
',' [comma] - "\,"
';' [semicolon] - "\;"
'= * [equals] - "\="
'+' [plus] - "\+"
'<' [less than] - * "\<"
'>' [greater than] - "\>"
'"' [double quote] - * "\""
'\' [backslash] - "\\"
* * @param value * the value to escape. * @return The escaped value. */ static public String nameEncode(String value) { if (value == null) return null; // make buffer roomy StringBuffer encodedValue = new StringBuffer(value.length() * 2); int length = value.length(); int last = length - 1; for (int i = 0; i < length; i++) { char c = value.charAt(i); // space first or last if (c == ' ' && (i == 0 || i == last)) { encodedValue.append("\\ "); continue; } if (c < nameEscapeTable.length) { // check in table for escapes String esc = nameEscapeTable[c]; if (esc != null) { encodedValue.append(esc); continue; } } // default: add the char encodedValue.append(c); } return encodedValue.toString(); } /** * Decodes a value. Converts escaped chars to ordinary chars. * * @param value * Trimmed value, so no leading an trailing blanks, except an * escaped space last. * @return The decoded value as a string. * @throws BadLdapGrammarException */ static public String nameDecode(String value) throws BadLdapGrammarException { if (value == null) return null; // make buffer same size StringBuffer decoded = new StringBuffer(value.length()); int i = 0; while (i < value.length()) { char currentChar = value.charAt(i); if (currentChar == '\\') { if (value.length() <= i + 1) { // Ending with a single backslash is not allowed throw new BadLdapGrammarException( "Unexpected end of value " + "unterminated '\\'"); } else { char nextChar = value.charAt(i + 1); if (nextChar == ',' || nextChar == '=' || nextChar == '+' || nextChar == '<' || nextChar == '>' || nextChar == '#' || nextChar == ';' || nextChar == '\\' || nextChar == '\"' || nextChar == ' ') { // Normal backslash escape decoded.append(nextChar); i += 2; } else { if (value.length() <= i + 2) { throw new BadLdapGrammarException( "Unexpected end of value " + "expected special or hex, found '" + nextChar + "'"); } else { // This should be a hex value String hexString = "" + nextChar + value.charAt(i + 2); decoded.append((char) Integer.parseInt(hexString, 16)); i += 3; } } } } else { // This character wasn't escaped - just append it decoded.append(currentChar); i++; } } return decoded.toString(); } }




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