132 lines
4.6 KiB
Java
Executable File
132 lines
4.6 KiB
Java
Executable File
/*
|
|
* 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.socksx.v4;
|
|
|
|
import io.netty.buffer.ByteBuf;
|
|
import io.netty.channel.ChannelHandlerContext;
|
|
import io.netty.handler.codec.DecoderException;
|
|
import io.netty.handler.codec.DecoderResult;
|
|
import io.netty.handler.codec.ReplayingDecoder;
|
|
import io.netty.handler.codec.socksx.SocksVersion;
|
|
import io.netty.handler.codec.socksx.v4.Socks4ServerDecoder.State;
|
|
import io.netty.util.CharsetUtil;
|
|
import io.netty.util.NetUtil;
|
|
|
|
/**
|
|
* Decodes a single {@link Socks4CommandRequest} from the inbound {@link ByteBuf}s.
|
|
* On successful decode, this decoder will forward the received data to the next handler, so that
|
|
* other handler can remove this decoder later. On failed decode, this decoder will discard the
|
|
* received data, so that other handler closes the connection later.
|
|
*/
|
|
public class Socks4ServerDecoder extends ReplayingDecoder<State> {
|
|
|
|
private static final int MAX_FIELD_LENGTH = 255;
|
|
|
|
enum State {
|
|
START,
|
|
READ_USERID,
|
|
READ_DOMAIN,
|
|
SUCCESS,
|
|
FAILURE
|
|
}
|
|
|
|
private Socks4CommandType type;
|
|
private String dstAddr;
|
|
private int dstPort;
|
|
private String userId;
|
|
|
|
public Socks4ServerDecoder() {
|
|
super(State.START);
|
|
setSingleDecode(true);
|
|
}
|
|
|
|
@Override
|
|
protected void decode(ChannelHandlerContext ctx, ByteBuf in) throws Exception {
|
|
try {
|
|
switch (state()) {
|
|
case START: {
|
|
final int version = in.readUnsignedByte();
|
|
if (version != SocksVersion.SOCKS4a.byteValue()) {
|
|
throw new DecoderException("unsupported protocol version: " + version);
|
|
}
|
|
|
|
type = Socks4CommandType.valueOf(in.readByte());
|
|
dstPort = in.readUnsignedShort();
|
|
dstAddr = NetUtil.intToIpAddress(in.readInt());
|
|
checkpoint(State.READ_USERID);
|
|
}
|
|
case READ_USERID: {
|
|
userId = readString("userid", in);
|
|
checkpoint(State.READ_DOMAIN);
|
|
}
|
|
case READ_DOMAIN: {
|
|
// Check for Socks4a protocol marker 0.0.0.x
|
|
if (!"0.0.0.0".equals(dstAddr) && dstAddr.startsWith("0.0.0.")) {
|
|
dstAddr = readString("dstAddr", in);
|
|
}
|
|
ctx.fireChannelRead(new DefaultSocks4CommandRequest(type, dstAddr, dstPort, userId));
|
|
checkpoint(State.SUCCESS);
|
|
}
|
|
case SUCCESS: {
|
|
int readableBytes = actualReadableBytes();
|
|
if (readableBytes > 0) {
|
|
ctx.fireChannelRead(in.readRetainedSlice(readableBytes));
|
|
}
|
|
break;
|
|
}
|
|
case FAILURE: {
|
|
in.skipBytes(actualReadableBytes());
|
|
break;
|
|
}
|
|
}
|
|
} catch (Exception e) {
|
|
fail(ctx, e);
|
|
}
|
|
}
|
|
|
|
private void fail(ChannelHandlerContext ctx, Exception cause) {
|
|
if (!(cause instanceof DecoderException)) {
|
|
cause = new DecoderException(cause);
|
|
}
|
|
|
|
Socks4CommandRequest m = new DefaultSocks4CommandRequest(
|
|
type != null? type : Socks4CommandType.CONNECT,
|
|
dstAddr != null? dstAddr : "",
|
|
dstPort != 0? dstPort : 65535,
|
|
userId != null? userId : "");
|
|
|
|
m.setDecoderResult(DecoderResult.failure(cause));
|
|
ctx.fireChannelRead(m);
|
|
|
|
checkpoint(State.FAILURE);
|
|
}
|
|
|
|
/**
|
|
* Reads a variable-length NUL-terminated string as defined in SOCKS4.
|
|
*/
|
|
private static String readString(String fieldName, ByteBuf in) {
|
|
int length = in.bytesBefore(MAX_FIELD_LENGTH + 1, (byte) 0);
|
|
if (length < 0) {
|
|
throw new DecoderException("field '" + fieldName + "' longer than " + MAX_FIELD_LENGTH + " chars");
|
|
}
|
|
|
|
String value = in.readSlice(length).toString(CharsetUtil.US_ASCII);
|
|
in.skipBytes(1); // Skip the NUL.
|
|
|
|
return value;
|
|
}
|
|
}
|