Java tutorial
/* * Copyright 2012 The Netty Project * * The Netty Project 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 io.netty.handler.codec.socks; import io.netty.buffer.ByteBuf; import io.netty.util.CharsetUtil; import io.netty.util.NetUtil; import io.netty.util.internal.ObjectUtil; import java.net.IDN; /** * A socks cmd response. * * @see SocksCmdRequest * @see SocksCmdResponseDecoder */ public final class SocksCmdResponse extends SocksResponse { private final SocksCmdStatus cmdStatus; private final SocksAddressType addressType; private final String host; private final int port; // All arrays are initialized on construction time to 0/false/null remove array Initialization private static final byte[] DOMAIN_ZEROED = { 0x00 }; private static final byte[] IPv4_HOSTNAME_ZEROED = { 0x00, 0x00, 0x00, 0x00 }; private static final byte[] IPv6_HOSTNAME_ZEROED = { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }; public SocksCmdResponse(SocksCmdStatus cmdStatus, SocksAddressType addressType) { this(cmdStatus, addressType, null, 0); } /** * Constructs new response and includes provided host and port as part of it. * * @param cmdStatus status of the response * @param addressType type of host parameter * @param host host (BND.ADDR field) is address that server used when connecting to the target host. * When null a value of 4/8 0x00 octets will be used for IPv4/IPv6 and a single 0x00 byte will be * used for domain addressType. Value is converted to ASCII using {@link IDN#toASCII(String)}. * @param port port (BND.PORT field) that the server assigned to connect to the target host * @throws NullPointerException in case cmdStatus or addressType are missing * @throws IllegalArgumentException in case host or port cannot be validated * @see IDN#toASCII(String) */ public SocksCmdResponse(SocksCmdStatus cmdStatus, SocksAddressType addressType, String host, int port) { super(SocksResponseType.CMD); ObjectUtil.checkNotNull(cmdStatus, "cmdStatus"); ObjectUtil.checkNotNull(addressType, "addressType"); if (host != null) { switch (addressType) { case IPv4: if (!NetUtil.isValidIpV4Address(host)) { throw new IllegalArgumentException(host + " is not a valid IPv4 address"); } break; case DOMAIN: String asciiHost = IDN.toASCII(host); if (asciiHost.length() > 255) { throw new IllegalArgumentException(host + " IDN: " + asciiHost + " exceeds 255 char limit"); } host = asciiHost; break; case IPv6: if (!NetUtil.isValidIpV6Address(host)) { throw new IllegalArgumentException(host + " is not a valid IPv6 address"); } break; case UNKNOWN: break; } } if (port < 0 || port > 65535) { throw new IllegalArgumentException(port + " is not in bounds 0 <= x <= 65535"); } this.cmdStatus = cmdStatus; this.addressType = addressType; this.host = host; this.port = port; } /** * Returns the {@link SocksCmdStatus} of this {@link SocksCmdResponse} * * @return The {@link SocksCmdStatus} of this {@link SocksCmdResponse} */ public SocksCmdStatus cmdStatus() { return cmdStatus; } /** * Returns the {@link SocksAddressType} of this {@link SocksCmdResponse} * * @return The {@link SocksAddressType} of this {@link SocksCmdResponse} */ public SocksAddressType addressType() { return addressType; } /** * Returns host that is used as a parameter in {@link SocksCmdType}. * Host (BND.ADDR field in response) is address that server used when connecting to the target host. * This is typically different from address which client uses to connect to the SOCKS server. * * @return host that is used as a parameter in {@link SocksCmdType} * or null when there was no host specified during response construction */ public String host() { return host != null && addressType == SocksAddressType.DOMAIN ? IDN.toUnicode(host) : host; } /** * Returns port that is used as a parameter in {@link SocksCmdType}. * Port (BND.PORT field in response) is port that the server assigned to connect to the target host. * * @return port that is used as a parameter in {@link SocksCmdType} */ public int port() { return port; } @Override public void encodeAsByteBuf(ByteBuf byteBuf) { byteBuf.writeByte(protocolVersion().byteValue()); byteBuf.writeByte(cmdStatus.byteValue()); byteBuf.writeByte(0x00); byteBuf.writeByte(addressType.byteValue()); switch (addressType) { case IPv4: { byte[] hostContent = host == null ? IPv4_HOSTNAME_ZEROED : NetUtil.createByteArrayFromIpAddressString(host); byteBuf.writeBytes(hostContent); byteBuf.writeShort(port); break; } case DOMAIN: { if (host != null) { byteBuf.writeByte(host.length()); byteBuf.writeCharSequence(host, CharsetUtil.US_ASCII); } else { byteBuf.writeByte(DOMAIN_ZEROED.length); byteBuf.writeBytes(DOMAIN_ZEROED); } byteBuf.writeShort(port); break; } case IPv6: { byte[] hostContent = host == null ? IPv6_HOSTNAME_ZEROED : NetUtil.createByteArrayFromIpAddressString(host); byteBuf.writeBytes(hostContent); byteBuf.writeShort(port); break; } } } }