/** * Copyright (C) 2004  Free Software Foundation, Inc. * * Author: Oliver Hitz * * This file is part of GNU Libidn. * * This library is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public License * as published by the Free Software Foundation; either version 2.1 of * the License, or (at your option) any later version. * * This library is distributed in the hope that it will be useful, but * WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU * Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with this library; if not, write to the Free Software * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 * USA */package gnu.inet.encoding;public class IDNA{  public final static String ACE_PREFIX = "xn--";  /**   * Converts a Unicode string to ASCII using the procedure in RFC3490   * section 4.1. Unassigned characters are not allowed and STD3 ASCII   * rules are enforced. The input string may be a domain name   * containing dots.   *   * @param input Unicode string.   * @return Encoded string.   */  public static String toASCII(String input)    throws IDNAException  {    StringBuffer o = new StringBuffer();    StringBuffer h = new StringBuffer();    for (int i = 0; i < input.length(); i++) {      char c = input.charAt(i);      if (c == '.' || c == '\u3002' || c == '\uff0e' || c == '\uff61') {	o.append(toASCII(h.toString(), false, true));	o.append(c);	h = new StringBuffer();      } else {	h.append(c);      }    }    o.append(toASCII(h.toString(), false, true));    return o.toString();  }  /**   * Converts a Unicode string to ASCII using the procedure in RFC3490   * section 4.1. Unassigned characters are not allowed and STD3 ASCII   * rules are enforced.   *   * @param input Unicode string.   * @param allowUnassigned Unassigned characters, allowed or not?   * @param useSTD3ASCIIRules STD3 ASCII rules, enforced or not?   * @return Encoded string.   */  public static String toASCII(String input, boolean allowUnassigned, boolean useSTD3ASCIIRules)    throws IDNAException  {    // Step 1: Check if the string contains code points outside    //         the ASCII range 0..0x7c.    boolean nonASCII = false;    for (int i = 0; i < input.length(); i++) {      int c = input.charAt(i);      if (c > 0x7f) {	nonASCII = true;	break;      }    }    // Step 2: Perform the nameprep operation.    if (nonASCII) {      try {	input = Stringprep.nameprep(input, allowUnassigned);      } catch (StringprepException e) {	throw new IDNAException(e);      }    }    // Step 3: - Verify the absence of non-LDH ASCII code points    //           0..0x2c, 0x2e..0x2f, 0x3a..0x40, 0x5b..0x60,    //           0x7b..0x7f    //         - Verify the absence of leading and trailing    //           hyphen-minus    if (useSTD3ASCIIRules) {      for (int i = 0; i < input.length(); i++) {	int c = input.charAt(i);	if ((c <= 0x2c) || 	    (c >= 0x2e && c <= 0x2f) || 	    (c >= 0x3a && c <= 0x40) ||	    (c >= 0x5b && c <= 0x60) ||	    (c >= 0x7b && c <= 0x7f)) {	  throw new IDNAException(IDNAException.CONTAINS_NON_LDH);	}      }      if (input.startsWith("-") || input.endsWith("-")) {	throw new IDNAException(IDNAException.CONTAINS_HYPHEN);      }    }    // Step 4: If all code points are inside 0..0x7f, skip to step 8    nonASCII = false;    for (int i = 0; i < input.length(); i++) {      int c = input.charAt(i);      if (c > 0x7f) {	nonASCII = true;	break;      }    }    String output = input;    if (nonASCII) {      // Step 5: Verify that the sequence does not begin with the ACE prefix.      if (input.startsWith(ACE_PREFIX)) {	throw new IDNAException(IDNAException.CONTAINS_ACE_PREFIX);      }            // Step 6: Punycode      try {	output = Punycode.encode(input);      } catch (PunycodeException e) {	throw new IDNAException(e);      }      // Step 7: Prepend the ACE prefix.      output = ACE_PREFIX + output;    }    // Step 8: Check that the length is inside 1..63.    if (output.length() < 1 || output.length() > 63) {      throw new IDNAException(IDNAException.TOO_LONG);    }    return output;  }  /**   * Converts an ASCII-encoded string to Unicode. Unassigned   * characters are not allowed and STD3 hostnames are enforced. Input   * may be domain name containing dots.   *   * @param input ASCII input string.   * @return Unicode string.   */  public static String toUnicode(String input)  {    StringBuffer o = new StringBuffer();    StringBuffer h = new StringBuffer();    for (int i = 0; i < input.length(); i++) {      char c = input.charAt(i);      if (c == '.' || c == '\u3002' || c == '\uff0e' || c == '\uff61') {	o.append(toUnicode(h.toString(), false, true));	o.append(c);	h = new StringBuffer();      } else {	h.append(c);      }    }    o.append(toUnicode(h.toString(), false, true));    return o.toString();  }  /**   * Converts an ASCII-encoded string to Unicode.   *   * @param input ASCII input string.   * @param allowUnassigned Allow unassigned Unicode characters.   * @param useSTD3ASCIIRules Check that the output conforms to STD3.   * @return Unicode string.   */  public static String toUnicode(String input, boolean allowUnassigned, boolean useSTD3ASCIIRules)  {    String original = input;    boolean nonASCII = false;    // Step 1: If all code points are inside 0..0x7f, skip to step 3.    for (int i = 0; i < input.length(); i++) {      int c = input.charAt(i);      if (c > 0x7f) {	nonASCII = true;	break;      }    }    // Step 2: Perform the Nameprep operation.    if (nonASCII) {      try {	input = Stringprep.nameprep(input, allowUnassigned);      } catch (StringprepException e) {	// ToUnicode never fails!	return original;      }    }    // Step 3: Verify the sequence starts with the ACE prefix.    if (!input.startsWith(ACE_PREFIX)) {      // ToUnicode never fails!      return original;    }    String stored = input;    // Step 4: Remove the ACE prefix.    input = input.substring(ACE_PREFIX.length());    // Step 5: Decode using punycode    String output;    try {      output = Punycode.decode(input);    } catch (PunycodeException e) {      // ToUnicode never fails!      return original;    }    // Step 6: Apply toASCII    String ascii;    try {      ascii = toASCII(output, allowUnassigned, useSTD3ASCIIRules);    } catch (IDNAException e) {      // ToUnicode never fails!      return original;    }    // Step 7: Compare case-insensitively.    if (!ascii.equalsIgnoreCase(stored)) {      // ToUnicode never fails!      return original;    }    // Step 8: Return the result.    return output;  }}