LdapEncoder.java
/*
* Copyright 2005-2021 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
*
* https://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.support;
import java.util.Base64;
import org.springframework.ldap.BadLdapGrammarException;
import org.springframework.util.Assert;
/**
* Helper class to encode and decode ldap names and values.
*
* @author Adam Skogman
* @author Mattias Hellborg Arthursson
* @author Thomas Darimont
*/
public final class LdapEncoder {
private static final int HEX = 16;
private static String[] NAME_ESCAPE_TABLE = new String[96];
private static String[] FILTER_ESCAPE_TABLE = new String['\\' + 1];
private static final int RFC2849_MAX_BASE64_CHARS_PER_LINE = 76;
static {
// Name encoding table -------------------------------------
// all below 0x20 (control chars)
for (char c = 0; c < ' '; c++) {
NAME_ESCAPE_TABLE[c] = "\\" + toTwoCharHex(c);
}
NAME_ESCAPE_TABLE['#'] = "\\#";
NAME_ESCAPE_TABLE[','] = "\\,";
NAME_ESCAPE_TABLE[';'] = "\\;";
NAME_ESCAPE_TABLE['='] = "\\=";
NAME_ESCAPE_TABLE['+'] = "\\+";
NAME_ESCAPE_TABLE['<'] = "\\<";
NAME_ESCAPE_TABLE['>'] = "\\>";
NAME_ESCAPE_TABLE['\"'] = "\\\"";
NAME_ESCAPE_TABLE['\\'] = "\\\\";
// Filter encoding table -------------------------------------
// fill with char itself
for (char c = 0; c < FILTER_ESCAPE_TABLE.length; c++) {
FILTER_ESCAPE_TABLE[c] = String.valueOf(c);
}
// escapes (RFC2254)
FILTER_ESCAPE_TABLE['*'] = "\\2a";
FILTER_ESCAPE_TABLE['('] = "\\28";
FILTER_ESCAPE_TABLE[')'] = "\\29";
FILTER_ESCAPE_TABLE['\\'] = "\\5c";
FILTER_ESCAPE_TABLE[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
StringBuilder encodedValue = new StringBuilder(value.length() * 2);
int length = value.length();
for (int i = 0; i < length; i++) {
char c = value.charAt(i);
if (c < FILTER_ESCAPE_TABLE.length) {
encodedValue.append(FILTER_ESCAPE_TABLE[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!
*
* <br>Escapes:<br> ' ' [space] - "\ " [if first or last] <br> '#'
* [hash] - "\#" <br> ',' [comma] - "\," <br> ';' [semicolon] - "\;" <br> '=
* [equals] - "\=" <br> '+' [plus] - "\+" <br> '<' [less than] -
* "\<" <br> '>' [greater than] - "\>" <br> '"' [double quote] -
* "\"" <br> '\' [backslash] - "\\" <br>
*
* @param value
* the value to escape.
* @return The escaped value.
*/
public static String nameEncode(String value) {
if (value == null)
return null;
// make buffer roomy
StringBuilder encodedValue = new StringBuilder(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 < NAME_ESCAPE_TABLE.length) {
// check in table for escapes
String esc = NAME_ESCAPE_TABLE[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
StringBuilder decoded = new StringBuilder(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,
HEX));
i += 3;
}
}
}
} else {
// This character wasn't escaped - just append it
decoded.append(currentChar);
i++;
}
}
return decoded.toString();
}
/**
* Converts an array of bytes into a Base64 encoded string according to the rules for converting LDAP Attributes in RFC2849.
*
* @param val
* @return
* A string containing a lexical representation of base64Binary wrapped around 76 characters.
* @throws IllegalArgumentException if <tt>val</tt> is null.
*/
public static String printBase64Binary(byte[] val) {
Assert.notNull(val, "val must not be null!");
String encoded = encode(val);
int length = encoded.length();
StringBuilder sb = new StringBuilder(length + length / RFC2849_MAX_BASE64_CHARS_PER_LINE);
for (int i = 0, len = length; i < len; i++) {
sb.append(encoded.charAt(i));
if ((i + 1) % RFC2849_MAX_BASE64_CHARS_PER_LINE == 0) {
sb.append('\n');
sb.append(' ');
}
}
return sb.toString();
}
/**
* Converts the Base64 encoded string argument into an array of bytes.
*
* @param val
* @return
* An array of bytes represented by the string argument.
* @throws IllegalArgumentException if <tt>val</tt> is null or does not conform to lexical value space defined in XML Schema Part 2: Datatypes for xsd:base64Binary.
*/
public static byte[] parseBase64Binary(String val) {
Assert.notNull(val, "val must not be null!");
int length = val.length();
StringBuilder sb = new StringBuilder(length);
for (int i = 0, len = length; i < len; i++) {
char c = val.charAt(i);
if(c == '\n'){
if(i + 1 < len && val.charAt(i + 1) == ' ') {
i++;
}
continue;
}
sb.append(c);
}
return decode(sb.toString());
}
private static String encode(byte[] decoded) {
return Base64.getEncoder().encodeToString(decoded);
}
private static byte[] decode(String encoded) {
return Base64.getDecoder().decode(encoded);
}
}