1 /*
2 * Copyright (C) 2008, 2010 Google Inc.
3 * Copyright (C) 2008, 2009 Robin Rosenberg <robin.rosenberg@dewire.com>
4 * Copyright (C) 2008, 2020 Shawn O. Pearce <spearce@spearce.org> and others
5 *
6 * This program and the accompanying materials are made available under the
7 * terms of the Eclipse Distribution License v. 1.0 which is available at
8 * https://www.eclipse.org/org/documents/edl-v10.php.
9 *
10 * SPDX-License-Identifier: BSD-3-Clause
11 */
12
13 package org.eclipse.jgit.transport;
14
15 import static java.nio.charset.StandardCharsets.UTF_8;
16
17 import java.io.IOException;
18 import java.io.OutputStream;
19
20 import org.eclipse.jgit.lib.Constants;
21 import org.eclipse.jgit.util.RawParseUtils;
22 import org.slf4j.Logger;
23 import org.slf4j.LoggerFactory;
24
25 /**
26 * Write Git style pkt-line formatting to an output stream.
27 * <p>
28 * This class is not thread safe and may issue multiple writes to the underlying
29 * stream for each method call made.
30 * <p>
31 * This class performs no buffering on its own. This makes it suitable to
32 * interleave writes performed by this class with writes performed directly
33 * against the underlying OutputStream.
34 */
35 public class PacketLineOut {
36
37 private static final Logger log = LoggerFactory.getLogger(PacketLineOut.class);
38
39 private final OutputStream out;
40
41 private final byte[] lenbuffer;
42
43 private final boolean logEnabled;
44
45 private boolean flushOnEnd;
46
47 private boolean usingSideband;
48
49 /**
50 * Create a new packet line writer.
51 *
52 * @param outputStream
53 * stream.
54 */
55 public PacketLineOut(OutputStream outputStream) {
56 this(outputStream, true);
57 }
58
59 /**
60 * Create a new packet line writer that potentially doesn't log.
61 *
62 * @param outputStream
63 * stream.
64 * @param enableLogging
65 * {@code false} to suppress all logging; {@code true} to log
66 * normally
67 * @since 5.11
68 */
69 public PacketLineOut(OutputStream outputStream, boolean enableLogging) {
70 out = outputStream;
71 lenbuffer = new byte[5];
72 flushOnEnd = true;
73 logEnabled = enableLogging;
74 }
75
76 /**
77 * Set the flush behavior during {@link #end()}.
78 *
79 * @param flushOnEnd
80 * if true, a flush-pkt written during {@link #end()} also
81 * flushes the underlying stream.
82 */
83 public void setFlushOnEnd(boolean flushOnEnd) {
84 this.flushOnEnd = flushOnEnd;
85 }
86
87 /**
88 * @return whether to add a sideband designator to each non-flush and
89 * non-delim packet
90 * @see #setUsingSideband
91 * @since 5.5
92 */
93 public boolean isUsingSideband() {
94 return usingSideband;
95 }
96
97 /**
98 * @param value If true, when writing packet lines, add, as the first
99 * byte, a sideband designator to each non-flush and non-delim
100 * packet. See pack-protocol.txt and protocol-v2.txt from the Git
101 * project for more information, specifically the "side-band" and
102 * "sideband-all" sections.
103 * @since 5.5
104 */
105 public void setUsingSideband(boolean value) {
106 this.usingSideband = value;
107 }
108
109 /**
110 * Write a UTF-8 encoded string as a single length-delimited packet.
111 *
112 * @param s
113 * string to write.
114 * @throws java.io.IOException
115 * the packet could not be written, the stream is corrupted as
116 * the packet may have been only partially written.
117 */
118 public void writeString(String s) throws IOException {
119 writePacket(Constants.encode(s));
120 }
121
122 /**
123 * Write a binary packet to the stream.
124 *
125 * @param packet
126 * the packet to write; the length of the packet is equal to the
127 * size of the byte array.
128 * @throws java.io.IOException
129 * the packet could not be written, the stream is corrupted as
130 * the packet may have been only partially written.
131 */
132 public void writePacket(byte[] packet) throws IOException {
133 writePacket(packet, 0, packet.length);
134 }
135
136 /**
137 * Write a binary packet to the stream.
138 *
139 * @param buf
140 * the packet to write
141 * @param pos
142 * first index within {@code buf}.
143 * @param len
144 * number of bytes to write.
145 * @throws java.io.IOException
146 * the packet could not be written, the stream is corrupted as
147 * the packet may have been only partially written.
148 * @since 4.5
149 */
150 public void writePacket(byte[] buf, int pos, int len) throws IOException {
151 if (usingSideband) {
152 formatLength(len + 5);
153 out.write(lenbuffer, 0, 4);
154 out.write(1);
155 } else {
156 formatLength(len + 4);
157 out.write(lenbuffer, 0, 4);
158 }
159 out.write(buf, pos, len);
160 if (logEnabled && log.isDebugEnabled()) {
161 // Escape a trailing \n to avoid empty lines in the log.
162 if (len > 0 && buf[pos + len - 1] == '\n') {
163 log.debug(
164 "git> " + RawParseUtils.decode(UTF_8, buf, pos, len - 1) //$NON-NLS-1$
165 + "\\n"); //$NON-NLS-1$
166 } else {
167 log.debug("git> " + RawParseUtils.decode(UTF_8, buf, pos, len)); //$NON-NLS-1$
168 }
169 }
170 }
171
172 /**
173 * Write a packet delim marker (0001).
174 *
175 * @throws java.io.IOException
176 * the marker could not be written, the stream is corrupted
177 * as the marker may have been only partially written.
178 * @since 5.0
179 */
180 public void writeDelim() throws IOException {
181 formatLength(1);
182 out.write(lenbuffer, 0, 4);
183 if (logEnabled && log.isDebugEnabled()) {
184 log.debug("git> 0001"); //$NON-NLS-1$
185 }
186 }
187
188 /**
189 * Write a packet end marker, sometimes referred to as a flush command.
190 * <p>
191 * Technically this is a magical packet type which can be detected
192 * separately from an empty string or an empty packet.
193 * <p>
194 * Implicitly performs a flush on the underlying OutputStream to ensure the
195 * peer will receive all data written thus far.
196 *
197 * @throws java.io.IOException
198 * the end marker could not be written, the stream is corrupted
199 * as the end marker may have been only partially written.
200 */
201 public void end() throws IOException {
202 formatLength(0);
203 out.write(lenbuffer, 0, 4);
204 if (logEnabled && log.isDebugEnabled()) {
205 log.debug("git> 0000"); //$NON-NLS-1$
206 }
207 if (flushOnEnd) {
208 flush();
209 }
210 }
211
212 /**
213 * Flush the underlying OutputStream.
214 * <p>
215 * Performs a flush on the underlying OutputStream to ensure the peer will
216 * receive all data written thus far.
217 *
218 * @throws java.io.IOException
219 * the underlying stream failed to flush.
220 */
221 public void flush() throws IOException {
222 out.flush();
223 }
224
225 private static final byte[] hexchar = { '0', '1', '2', '3', '4', '5', '6',
226 '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f' };
227
228 private void formatLength(int w) {
229 formatLength(lenbuffer, w);
230 }
231
232 static void formatLength(byte[] lenbuffer, int w) {
233 int o = 3;
234 while (o >= 0 && w != 0) {
235 lenbuffer[o--] = hexchar[w & 0xf];
236 w >>>= 4;
237 }
238 while (o >= 0)
239 lenbuffer[o--] = '0';
240 }
241 }