TFTPRequestPacket.java
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.commons.net.tftp;
import java.net.DatagramPacket;
import java.net.InetAddress;
/**
* An abstract class derived from TFTPPacket definiing a TFTP Request packet type. It is subclassed by the
* {@link org.apache.commons.net.tftp.TFTPReadRequestPacket} and {@link org.apache.commons.net.tftp.TFTPWriteRequestPacket} classes.
* <p>
* Details regarding the TFTP protocol and the format of TFTP packets can be found in RFC 783. But the point of these classes is to keep you from having to
* worry about the internals. Additionally, only very few people should have to care about any of the TFTPPacket classes or derived classes. Almost all users
* should only be concerned with the {@link org.apache.commons.net.tftp.TFTPClient} class {@link org.apache.commons.net.tftp.TFTPClient#receiveFile
* receiveFile()} and {@link org.apache.commons.net.tftp.TFTPClient#sendFile sendFile()} methods.
*
*
* @see TFTPPacket
* @see TFTPReadRequestPacket
* @see TFTPWriteRequestPacket
* @see TFTPPacketException
* @see TFTP
*/
public abstract class TFTPRequestPacket extends TFTPPacket {
/**
* An array containing the string names of the transfer modes and indexed by the transfer mode constants.
*/
static final String[] modeStrings = { "netascii", "octet" };
/**
* A null terminated byte array representation of the ascii names of the transfer mode constants. This is convenient for creating the TFTP request packets.
*/
private static final byte[] modeBytes[] = { { (byte) 'n', (byte) 'e', (byte) 't', (byte) 'a', (byte) 's', (byte) 'c', (byte) 'i', (byte) 'i', 0 },
{ (byte) 'o', (byte) 'c', (byte) 't', (byte) 'e', (byte) 't', 0 } };
/** The transfer mode of the request. */
private final int mode;
/** The file name of the request. */
private final String fileName;
/**
* Creates a request packet of a given type to be sent to a host at a given port with a file name and transfer mode request.
*
* @param destination The host to which the packet is going to be sent.
* @param port The port to which the packet is going to be sent.
* @param type The type of the request (either TFTPPacket.READ_REQUEST or TFTPPacket.WRITE_REQUEST).
* @param fileName The requested file name.
* @param mode The requested transfer mode. This should be on of the TFTP class MODE constants (e.g., TFTP.NETASCII_MODE).
*/
TFTPRequestPacket(final InetAddress destination, final int port, final int type, final String fileName, final int mode) {
super(type, destination, port);
this.fileName = fileName;
this.mode = mode;
}
/**
* Creates a request packet of a given type based on a received datagram. Assumes the datagram is at least length 4, else an ArrayIndexOutOfBoundsException
* may be thrown.
*
* @param type The type of the request (either TFTPPacket.READ_REQUEST or TFTPPacket.WRITE_REQUEST).
* @param datagram The datagram containing the received request.
* @throws TFTPPacketException If the datagram isn't a valid TFTP request packet of the appropriate type.
*/
TFTPRequestPacket(final int type, final DatagramPacket datagram) throws TFTPPacketException {
super(type, datagram.getAddress(), datagram.getPort());
final byte[] data = datagram.getData();
if (getType() != data[1]) {
throw new TFTPPacketException("TFTP operator code does not match type.");
}
final StringBuilder buffer = new StringBuilder();
int index = 2;
int length = datagram.getLength();
while (index < length && data[index] != 0) {
buffer.append((char) data[index]);
++index;
}
this.fileName = buffer.toString();
if (index >= length) {
throw new TFTPPacketException("Bad file name and mode format.");
}
buffer.setLength(0);
++index; // need to advance beyond the end of string marker
while (index < length && data[index] != 0) {
buffer.append((char) data[index]);
++index;
}
final String modeString = buffer.toString().toLowerCase(java.util.Locale.ENGLISH);
length = modeStrings.length;
int mode = 0;
for (index = 0; index < length; index++) {
if (modeString.equals(modeStrings[index])) {
mode = index;
break;
}
}
this.mode = mode;
if (index >= length) {
throw new TFTPPacketException("Unrecognized TFTP transfer mode: " + modeString);
// May just want to default to binary mode instead of throwing
// exception.
// _mode = TFTP.OCTET_MODE;
}
}
/**
* Returns the requested file name.
*
* @return The requested file name.
*/
public final String getFilename() {
return fileName;
}
/**
* Returns the transfer mode of the request.
*
* @return The transfer mode of the request.
*/
public final int getMode() {
return mode;
}
/**
* Creates a UDP datagram containing all the TFTP request packet data in the proper format. This is a method exposed to the programmer in case he wants to
* implement his own TFTP client instead of using the {@link org.apache.commons.net.tftp.TFTPClient} class. Under normal circumstances, you should not have
* a need to call this method.
*
* @return A UDP datagram containing the TFTP request packet.
*/
@Override
public final DatagramPacket newDatagram() {
final int fileLength;
final int modeLength;
final byte[] data;
fileLength = fileName.length();
modeLength = modeBytes[mode].length;
data = new byte[fileLength + modeLength + 4];
data[0] = 0;
data[1] = (byte) type;
System.arraycopy(fileName.getBytes(), 0, data, 2, fileLength);
data[fileLength + 2] = 0;
System.arraycopy(modeBytes[mode], 0, data, fileLength + 3, modeLength);
return new DatagramPacket(data, data.length, address, port);
}
/**
* This is a method only available within the package for implementing efficient datagram transport by elminating buffering. It takes a datagram as an
* argument, and a byte buffer in which to store the raw datagram data. Inside the method, the data is set as the datagram's data and the datagram returned.
*
* @param datagram The datagram to create.
* @param data The buffer to store the packet and to use in the datagram.
* @return The datagram argument.
*/
@Override
final DatagramPacket newDatagram(final DatagramPacket datagram, final byte[] data) {
final int fileLength;
final int modeLength;
fileLength = fileName.length();
modeLength = modeBytes[mode].length;
data[0] = 0;
data[1] = (byte) type;
System.arraycopy(fileName.getBytes(), 0, data, 2, fileLength);
data[fileLength + 2] = 0;
System.arraycopy(modeBytes[mode], 0, data, fileLength + 3, modeLength);
datagram.setAddress(address);
datagram.setPort(port);
datagram.setData(data);
datagram.setLength(fileLength + modeLength + 3);
return datagram;
}
}