| /* |
| * Copyright (C) 2021 The Android Open Source Project |
| * |
| * Licensed 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 com.android.net.module.util.structs; |
| |
| import com.android.net.module.util.Struct; |
| import com.android.net.module.util.Struct.Field; |
| import com.android.net.module.util.Struct.Type; |
| |
| /** |
| * L4 TCP header as per https://tools.ietf.org/html/rfc793. |
| * This class does not contain option and data fields. |
| * |
| * 0 1 2 3 |
| * 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 |
| * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| * | Source Port | Destination Port | |
| * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| * | Sequence Number | |
| * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| * | Acknowledgment Number | |
| * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| * | Data | |U|A|P|R|S|F| | |
| * | Offset| Reserved |R|C|S|S|Y|I| Window | |
| * | | |G|K|H|T|N|N| | |
| * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| * | Checksum | Urgent Pointer | |
| * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| * | Options | Padding | |
| * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| * | data | |
| * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| */ |
| public class TcpHeader extends Struct { |
| @Field(order = 0, type = Type.U16) |
| public final int srcPort; |
| @Field(order = 1, type = Type.U16) |
| public final int dstPort; |
| @Field(order = 2, type = Type.U32) |
| public final long seq; |
| @Field(order = 3, type = Type.U32) |
| public final long ack; |
| @Field(order = 4, type = Type.S16) |
| // data Offset (4 bits), reserved (6 bits), control bits (6 bits) |
| // TODO: update with bitfields once class Struct supports it |
| public final short dataOffsetAndControlBits; |
| @Field(order = 5, type = Type.U16) |
| public final int window; |
| @Field(order = 6, type = Type.S16) |
| public final short checksum; |
| @Field(order = 7, type = Type.U16) |
| public final int urgentPointer; |
| |
| public TcpHeader(final int srcPort, final int dstPort, final long seq, final long ack, |
| final short dataOffsetAndControlBits, final int window, final short checksum, |
| final int urgentPointer) { |
| this.srcPort = srcPort; |
| this.dstPort = dstPort; |
| this.seq = seq; |
| this.ack = ack; |
| this.dataOffsetAndControlBits = dataOffsetAndControlBits; |
| this.window = window; |
| this.checksum = checksum; |
| this.urgentPointer = urgentPointer; |
| } |
| } |