PacketLineIn.java
/*
* Copyright (C) 2008, 2010 Google Inc.
* Copyright (C) 2008, 2009 Robin Rosenberg <robin.rosenberg@dewire.com>
* Copyright (C) 2008, 2020 Shawn O. Pearce <spearce@spearce.org> and others
*
* This program and the accompanying materials are made available under the
* terms of the Eclipse Distribution License v. 1.0 which is available at
* https://www.eclipse.org/org/documents/edl-v10.php.
*
* SPDX-License-Identifier: BSD-3-Clause
*/
package org.eclipse.jgit.transport;
import static java.nio.charset.StandardCharsets.UTF_8;
import java.io.IOException;
import java.io.InputStream;
import java.io.UncheckedIOException;
import java.text.MessageFormat;
import java.util.Iterator;
import org.eclipse.jgit.errors.PackProtocolException;
import org.eclipse.jgit.internal.JGitText;
import org.eclipse.jgit.lib.MutableObjectId;
import org.eclipse.jgit.util.IO;
import org.eclipse.jgit.util.RawParseUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* Read Git style pkt-line formatting from an input stream.
* <p>
* This class is not thread safe and may issue multiple reads to the underlying
* stream for each method call made.
* <p>
* This class performs no buffering on its own. This makes it suitable to
* interleave reads performed by this class with reads performed directly
* against the underlying InputStream.
*/
public class PacketLineIn {
private static final Logger log = LoggerFactory.getLogger(PacketLineIn.class);
/**
* Magic return from {@link #readString()} when a flush packet is found.
*
* @deprecated Callers should use {@link #isEnd(String)} to check if a
* string is the end marker, or
* {@link PacketLineIn#readStrings()} to iterate over all
* strings in the input stream until the marker is reached.
*/
@Deprecated
public static final String END = new String(); /* must not string pool */
/**
* Magic return from {@link #readString()} when a delim packet is found.
*
* @since 5.0
* @deprecated Callers should use {@link #isDelimiter(String)} to check if a
* string is the delimiter.
*/
@Deprecated
public static final String DELIM = new String(); /* must not string pool */
enum AckNackResult {
/** NAK */
NAK,
/** ACK */
ACK,
/** ACK + continue */
ACK_CONTINUE,
/** ACK + common */
ACK_COMMON,
/** ACK + ready */
ACK_READY;
}
private final byte[] lineBuffer = new byte[SideBandOutputStream.SMALL_BUF];
private final InputStream in;
private long limit;
/**
* Create a new packet line reader.
*
* @param in
* the input stream to consume.
*/
public PacketLineIn(InputStream in) {
this(in, 0);
}
/**
* Create a new packet line reader.
*
* @param in
* the input stream to consume.
* @param limit
* bytes to read from the input; unlimited if set to 0.
* @since 4.7
*/
public PacketLineIn(InputStream in, long limit) {
this.in = in;
this.limit = limit;
}
/**
* Parses a ACK/NAK line in protocol V2.
*
* @param line
* to parse
* @param returnedId
* in case of {@link AckNackResult#ACK_COMMON ACK_COMMON}
* @return one of {@link AckNackResult#NAK NAK},
* {@link AckNackResult#ACK_COMMON ACK_COMMON}, or
* {@link AckNackResult#ACK_READY ACK_READY}
* @throws IOException
* on protocol or transport errors
*/
static AckNackResult parseACKv2(String line, MutableObjectId returnedId)
throws IOException {
if ("NAK".equals(line)) { //$NON-NLS-1$
return AckNackResult.NAK;
}
if (line.startsWith("ACK ") && line.length() == 44) { //$NON-NLS-1$
returnedId.fromString(line.substring(4, 44));
return AckNackResult.ACK_COMMON;
}
if ("ready".equals(line)) { //$NON-NLS-1$
return AckNackResult.ACK_READY;
}
if (line.startsWith("ERR ")) { //$NON-NLS-1$
throw new PackProtocolException(line.substring(4));
}
throw new PackProtocolException(
MessageFormat.format(JGitText.get().expectedACKNAKGot, line));
}
AckNackResult readACK(MutableObjectId returnedId) throws IOException {
final String line = readString();
if (line.length() == 0)
throw new PackProtocolException(JGitText.get().expectedACKNAKFoundEOF);
if ("NAK".equals(line)) //$NON-NLS-1$
return AckNackResult.NAK;
if (line.startsWith("ACK ")) { //$NON-NLS-1$
returnedId.fromString(line.substring(4, 44));
if (line.length() == 44)
return AckNackResult.ACK;
final String arg = line.substring(44);
switch (arg) {
case " continue": //$NON-NLS-1$
return AckNackResult.ACK_CONTINUE;
case " common": //$NON-NLS-1$
return AckNackResult.ACK_COMMON;
case " ready": //$NON-NLS-1$
return AckNackResult.ACK_READY;
default:
break;
}
}
if (line.startsWith("ERR ")) //$NON-NLS-1$
throw new PackProtocolException(line.substring(4));
throw new PackProtocolException(MessageFormat.format(JGitText.get().expectedACKNAKGot, line));
}
/**
* Read a single UTF-8 encoded string packet from the input stream.
* <p>
* If the string ends with an LF, it will be removed before returning the
* value to the caller. If this automatic trimming behavior is not desired,
* use {@link #readStringRaw()} instead.
*
* @return the string. {@link #END} if the string was the magic flush
* packet, {@link #DELIM} if the string was the magic DELIM
* packet.
* @throws java.io.IOException
* the stream cannot be read.
*/
public String readString() throws IOException {
int len = readLength();
if (len == 0) {
log.debug("git< 0000"); //$NON-NLS-1$
return END;
}
if (len == 1) {
log.debug("git< 0001"); //$NON-NLS-1$
return DELIM;
}
len -= 4; // length header (4 bytes)
if (len == 0) {
log.debug("git< "); //$NON-NLS-1$
return ""; //$NON-NLS-1$
}
byte[] raw;
if (len <= lineBuffer.length)
raw = lineBuffer;
else
raw = new byte[len];
IO.readFully(in, raw, 0, len);
if (raw[len - 1] == '\n')
len--;
String s = RawParseUtils.decode(UTF_8, raw, 0, len);
log.debug("git< " + s); //$NON-NLS-1$
return s;
}
/**
* Get an iterator to read strings from the input stream.
*
* @return an iterator that calls {@link #readString()} until {@link #END}
* is encountered.
*
* @throws IOException
* on failure to read the initial packet line.
* @since 5.4
*/
public PacketLineInIterator readStrings() throws IOException {
return new PacketLineInIterator(this);
}
/**
* Read a single UTF-8 encoded string packet from the input stream.
* <p>
* Unlike {@link #readString()} a trailing LF will be retained.
*
* @return the string. {@link #END} if the string was the magic flush
* packet.
* @throws java.io.IOException
* the stream cannot be read.
*/
public String readStringRaw() throws IOException {
int len = readLength();
if (len == 0) {
log.debug("git< 0000"); //$NON-NLS-1$
return END;
}
len -= 4; // length header (4 bytes)
byte[] raw;
if (len <= lineBuffer.length)
raw = lineBuffer;
else
raw = new byte[len];
IO.readFully(in, raw, 0, len);
String s = RawParseUtils.decode(UTF_8, raw, 0, len);
log.debug("git< " + s); //$NON-NLS-1$
return s;
}
/**
* Check if a string is the delimiter marker.
*
* @param s
* the string to check
* @return true if the given string is {@link #DELIM}, otherwise false.
* @since 5.4
*/
@SuppressWarnings({ "ReferenceEquality", "StringEquality" })
public static boolean isDelimiter(String s) {
return s == DELIM;
}
/**
* Get the delimiter marker.
* <p>
* Intended for use only in tests.
*
* @return The delimiter marker.
*/
static String delimiter() {
return DELIM;
}
/**
* Get the end marker.
* <p>
* Intended for use only in tests.
*
* @return The end marker.
*/
static String end() {
return END;
}
/**
* Check if a string is the packet end marker.
*
* @param s
* the string to check
* @return true if the given string is {@link #END}, otherwise false.
* @since 5.4
*/
@SuppressWarnings({ "ReferenceEquality", "StringEquality" })
public static boolean isEnd(String s) {
return s == END;
}
void discardUntilEnd() throws IOException {
for (;;) {
int n = readLength();
if (n == 0) {
break;
}
IO.skipFully(in, n - 4);
}
}
int readLength() throws IOException {
IO.readFully(in, lineBuffer, 0, 4);
int len;
try {
len = RawParseUtils.parseHexInt16(lineBuffer, 0);
} catch (ArrayIndexOutOfBoundsException err) {
throw invalidHeader(err);
}
if (len == 0) {
return 0;
} else if (len == 1) {
return 1;
} else if (len < 4) {
throw invalidHeader();
}
if (limit != 0) {
int n = len - 4;
if (limit < n) {
limit = -1;
try {
IO.skipFully(in, n);
} catch (IOException e) {
// Ignore failure discarding packet over limit.
}
throw new InputOverLimitIOException();
}
// if set limit must not be 0 (means unlimited).
limit = n < limit ? limit - n : -1;
}
return len;
}
private IOException invalidHeader() {
return new IOException(MessageFormat.format(JGitText.get().invalidPacketLineHeader,
"" + (char) lineBuffer[0] + (char) lineBuffer[1] //$NON-NLS-1$
+ (char) lineBuffer[2] + (char) lineBuffer[3]));
}
private IOException invalidHeader(Throwable cause) {
IOException ioe = invalidHeader();
ioe.initCause(cause);
return ioe;
}
/**
* IOException thrown by read when the configured input limit is exceeded.
*
* @since 4.7
*/
public static class InputOverLimitIOException extends IOException {
private static final long serialVersionUID = 1L;
}
/**
* Iterator over packet lines.
* <p>
* Calls {@link #readString()} on the {@link PacketLineIn} until
* {@link #END} is encountered.
*
* @since 5.4
*
*/
public static class PacketLineInIterator implements Iterable<String> {
private PacketLineIn in;
private String current;
PacketLineInIterator(PacketLineIn in) throws IOException {
this.in = in;
current = in.readString();
}
@Override
public Iterator<String> iterator() {
return new Iterator<>() {
@Override
public boolean hasNext() {
return !PacketLineIn.isEnd(current);
}
@Override
public String next() {
String next = current;
try {
current = in.readString();
} catch (IOException e) {
throw new UncheckedIOException(e);
}
return next;
}
};
}
}
}