1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17
18 package org.apache.commons.net.telnet;
19
20 import java.io.IOException;
21 import java.io.OutputStream;
22
23 /**
24 * Wraps an output stream.
25 * <p>
26 * In binary mode, the only conversion is to double IAC.
27 * <p>
28 * In ASCII mode, if convertCRtoCRLF is true (currently always true), any CR is converted to CRLF.
29 * IACs are doubled.
30 * Also a bare LF is converted to CRLF and a bare CR is converted to CR\0
31 * <p>
32 */
33
34
35 final class TelnetOutputStream extends OutputStream
36 {
37 private final TelnetClient client;
38 // TODO there does not appear to be any way to change this value - should it be a ctor parameter?
39 private final boolean convertCRtoCRLF = true;
40 private boolean lastWasCR;
41
42 TelnetOutputStream(final TelnetClient client)
43 {
44 this.client = client;
45 }
46
47
48 /**
49 * Writes a byte to the stream.
50 * <p>
51 * @param ch The byte to write.
52 * @throws IOException If an error occurs while writing to the underlying
53 * stream.
54 */
55 @Override
56 public void write(int ch) throws IOException
57 {
58
59 synchronized (client)
60 {
61 ch &= 0xff;
62
63 if (client.requestedWont(TelnetOption.BINARY)) // i.e. ASCII
64 {
65 if (lastWasCR)
66 {
67 if (convertCRtoCRLF)
68 {
69 client.sendByte('\n');
70 if (ch == '\n') // i.e. was CRLF anyway
71 {
72 lastWasCR = false;
73 return ;
74 }
75 } // __convertCRtoCRLF
76 else if (ch != '\n')
77 {
78 client.sendByte('\0'); // RFC854 requires CR NUL for bare CR
79 }
80 }
81
82 switch (ch)
83 {
84 case '\r':
85 client.sendByte('\r');
86 lastWasCR = true;
87 break;
88 case '\n':
89 if (!lastWasCR) { // convert LF to CRLF
90 client.sendByte('\r');
91 }
92 client.sendByte(ch);
93 lastWasCR = false;
94 break;
95 case TelnetCommand.IAC:
96 client.sendByte(TelnetCommand.IAC);
97 client.sendByte(TelnetCommand.IAC);
98 lastWasCR = false;
99 break;
100 default:
101 client.sendByte(ch);
102 lastWasCR = false;
103 break;
104 }
105 } // end ASCII
106 else if (ch == TelnetCommand.IAC)
107 {
108 client.sendByte(ch);
109 client.sendByte(TelnetCommand.IAC);
110 } else {
111 client.sendByte(ch);
112 }
113 }
114 }
115
116
117 /**
118 * Writes a byte array to the stream.
119 * <p>
120 * @param buffer The byte array to write.
121 * @throws IOException If an error occurs while writing to the underlying
122 * stream.
123 */
124 @Override
125 public void write(final byte buffer[]) throws IOException
126 {
127 write(buffer, 0, buffer.length);
128 }
129
130
131 /**
132 * Writes a number of bytes from a byte array to the stream starting from
133 * a given offset.
134 * <p>
135 * @param buffer The byte array to write.
136 * @param offset The offset into the array at which to start copying data.
137 * @param length The number of bytes to write.
138 * @throws IOException If an error occurs while writing to the underlying
139 * stream.
140 */
141 @Override
142 public void write(final byte buffer[], int offset, int length) throws IOException
143 {
144 synchronized (client)
145 {
146 while (length-- > 0) {
147 write(buffer[offset++]);
148 }
149 }
150 }
151
152 /** Flushes the stream. */
153 @Override
154 public void flush() throws IOException
155 {
156 client.flushOutputStream();
157 }
158
159 /** Closes the stream. */
160 @Override
161 public void close() throws IOException
162 {
163 client.closeOutputStream();
164 }
165 }