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Package: BASE64MailboxEncoder
BASE64MailboxEncoder
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| BASE64MailboxEncoder(Writer) |
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| encode(String) |
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Coverage
1: /*
2: * Copyright (c) 1997, 2023 Oracle and/or its affiliates. All rights reserved.
3: *
4: * This program and the accompanying materials are made available under the
5: * terms of the Eclipse Public License v. 2.0, which is available at
6: * http://www.eclipse.org/legal/epl-2.0.
7: *
8: * This Source Code may also be made available under the following Secondary
9: * Licenses when the conditions for such availability set forth in the
10: * Eclipse Public License v. 2.0 are satisfied: GNU General Public License,
11: * version 2 with the GNU Classpath Exception, which is available at
12: * https://www.gnu.org/software/classpath/license.html.
13: *
14: * SPDX-License-Identifier: EPL-2.0 OR GPL-2.0 WITH Classpath-exception-2.0
15: */
16:
17: package org.eclipse.angus.mail.imap.protocol;
18:
19: import java.io.*;
20:
21:
22: /**
23: * From RFC2060:
24: *
25: * <blockquote><pre>
26: *
27: * 5.1.3. Mailbox International Naming Convention
28: *
29: * By convention, international mailbox names are specified using a
30: * modified version of the UTF-7 encoding described in [UTF-7]. The
31: * purpose of these modifications is to correct the following problems
32: * with UTF-7:
33: *
34: * 1) UTF-7 uses the "+" character for shifting; this conflicts with
35: * the common use of "+" in mailbox names, in particular USENET
36: * newsgroup names.
37: *
38: * 2) UTF-7's encoding is BASE64 which uses the "/" character; this
39: * conflicts with the use of "/" as a popular hierarchy delimiter.
40: *
41: * 3) UTF-7 prohibits the unencoded usage of "\"; this conflicts with
42: * the use of "\" as a popular hierarchy delimiter.
43: *
44: * 4) UTF-7 prohibits the unencoded usage of "~"; this conflicts with
45: * the use of "~" in some servers as a home directory indicator.
46: *
47: * 5) UTF-7 permits multiple alternate forms to represent the same
48: * string; in particular, printable US-ASCII chararacters can be
49: * represented in encoded form.
50: *
51: * In modified UTF-7, printable US-ASCII characters except for "&"
52: * represent themselves; that is, characters with octet values 0x20-0x25
53: * and 0x27-0x7e. The character "&" (0x26) is represented by the two-
54: * octet sequence "&-".
55: *
56: * All other characters (octet values 0x00-0x1f, 0x7f-0xff, and all
57: * Unicode 16-bit octets) are represented in modified BASE64, with a
58: * further modification from [UTF-7] that "," is used instead of "/".
59: * Modified BASE64 MUST NOT be used to represent any printing US-ASCII
60: * character which can represent itself.
61: *
62: * "&" is used to shift to modified BASE64 and "-" to shift back to US-
63: * ASCII. All names start in US-ASCII, and MUST end in US-ASCII (that
64: * is, a name that ends with a Unicode 16-bit octet MUST end with a "-
65: * ").
66: *
67: * For example, here is a mailbox name which mixes English, Japanese,
68: * and Chinese text: ~peter/mail/&ZeVnLIqe-/&U,BTFw-
69: *
70: * </pre></blockquote>
71: *
72: * This class will do the correct Encoding for the IMAP mailboxes.
73: *
74: * @author Christopher Cotton
75: */
76:
77: public class BASE64MailboxEncoder {
78: protected byte[] buffer = new byte[4];
79: protected int bufsize = 0;
80: protected boolean started = false;
81: protected Writer out = null;
82:
83:
84: public static String encode(String original) {
85: BASE64MailboxEncoder base64stream = null;
86: char origchars[] = original.toCharArray();
87: int length = origchars.length;
88: boolean changedString = false;
89: CharArrayWriter writer = new CharArrayWriter(length);
90:
91: // loop over all the chars
92:• for(int index = 0; index < length; index++) {
93: char current = origchars[index];
94:
95: // octets in the range 0x20-0x25,0x27-0x7e are themselves
96: // 0x26 "&" is represented as "&-"
97:• if (current >= 0x20 && current <= 0x7e) {
98:• if (base64stream != null) {
99: base64stream.flush();
100: }
101:
102:• if (current == '&') {
103: changedString = true;
104: writer.write('&');
105: writer.write('-');
106: } else {
107: writer.write(current);
108: }
109: } else {
110:
111: // use a B64MailboxEncoder to write out the other bytes
112: // as a modified BASE64. The stream will write out
113: // the beginning '&' and the ending '-' which is part
114: // of every encoding.
115:
116:• if (base64stream == null) {
117: base64stream = new BASE64MailboxEncoder(writer);
118: changedString = true;
119: }
120:
121: base64stream.write(current);
122: }
123: }
124:
125:
126:• if (base64stream != null) {
127: base64stream.flush();
128: }
129:
130:• if (changedString) {
131: return writer.toString();
132: } else {
133: return original;
134: }
135: }
136:
137:
138: /**
139: * Create a BASE64 encoder
140: *
141: * @param what where to write the encoded name
142: */
143: public BASE64MailboxEncoder(Writer what) {
144: out = what;
145: }
146:
147: public void write(int c) {
148: try {
149: // write out the initial character if this is the first time
150:• if (!started) {
151: started = true;
152: out.write('&');
153: }
154:
155: // we write each character as a 2 byte unicode character
156: buffer[bufsize++] = (byte) (c >> 8);
157: buffer[bufsize++] = (byte) (c & 0xff);
158:
159:• if (bufsize >= 3) {
160: encode();
161: bufsize -= 3;
162: }
163: } catch (IOException e) {
164: //e.printStackTrace();
165: }
166: }
167:
168:
169: public void flush() {
170: try {
171: // flush any bytes we have
172:• if (bufsize > 0) {
173: encode();
174: bufsize = 0;
175: }
176:
177: // write the terminating character of the encoding
178:• if (started) {
179: out.write('-');
180: started = false;
181: }
182: } catch (IOException e) {
183: //e.printStackTrace();
184: }
185: }
186:
187:
188: protected void encode() throws IOException {
189: byte a, b, c;
190:• if (bufsize == 1) {
191: a = buffer[0];
192: b = 0;
193: c = 0;
194: out.write(pem_array[(a >>> 2) & 0x3F]);
195: out.write(pem_array[((a << 4) & 0x30) + ((b >>> 4) & 0xf)]);
196: // no padding characters are written
197:• } else if (bufsize == 2) {
198: a = buffer[0];
199: b = buffer[1];
200: c = 0;
201: out.write(pem_array[(a >>> 2) & 0x3F]);
202: out.write(pem_array[((a << 4) & 0x30) + ((b >>> 4) & 0xf)]);
203: out.write(pem_array[((b << 2) & 0x3c) + ((c >>> 6) & 0x3)]);
204: // no padding characters are written
205: } else {
206: a = buffer[0];
207: b = buffer[1];
208: c = buffer[2];
209: out.write(pem_array[(a >>> 2) & 0x3F]);
210: out.write(pem_array[((a << 4) & 0x30) + ((b >>> 4) & 0xf)]);
211: out.write(pem_array[((b << 2) & 0x3c) + ((c >>> 6) & 0x3)]);
212: out.write(pem_array[c & 0x3F]);
213:
214: // copy back the extra byte
215:• if (bufsize == 4)
216: buffer[0] = buffer[3];
217: }
218: }
219:
220: private final static char pem_array[] = {
221: 'A','B','C','D','E','F','G','H', // 0
222: 'I','J','K','L','M','N','O','P', // 1
223: 'Q','R','S','T','U','V','W','X', // 2
224: 'Y','Z','a','b','c','d','e','f', // 3
225: 'g','h','i','j','k','l','m','n', // 4
226: 'o','p','q','r','s','t','u','v', // 5
227: 'w','x','y','z','0','1','2','3', // 6
228: '4','5','6','7','8','9','+',',' // 7
229: };
230: }