Add StructTcpHeader class to parse TCP header from a packet
Note that this class does not contain option and data fields.
Test: atest NetworkStaticLibTests
Change-Id: Icda61c129c9693e504d3f19a05242677b9dc41da
diff --git a/staticlibs/device/com/android/net/module/util/structs/TcpHeader.java b/staticlibs/device/com/android/net/module/util/structs/TcpHeader.java
new file mode 100644
index 0000000..0c97401
--- /dev/null
+++ b/staticlibs/device/com/android/net/module/util/structs/TcpHeader.java
@@ -0,0 +1,79 @@
+/*
+ * 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;
+ }
+}