1 files changed, 231 insertions, 0 deletions
diff --git a/src/com/android/networkstack/netlink/TcpInfo.java b/src/com/android/networkstack/netlink/TcpInfo.java
new file mode 100644
index 0000000..9cf415b
--- /dev/null
+++ b/src/com/android/networkstack/netlink/TcpInfo.java
@@ -0,0 +1,231 @@
+/*
+ * Copyright (C) 2019 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.networkstack.netlink;
+
+import android.util.Log;
+import android.util.Range;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+
+import com.android.internal.annotations.VisibleForTesting;
+
+import java.nio.BufferUnderflowException;
+import java.nio.ByteBuffer;
+import java.util.HashMap;
+import java.util.LinkedHashMap;
+import java.util.Objects;
+
+/**
+ * Class for tcp_info.
+ *
+ * Corresponds to {@code struct tcp_info} from bionic/libc/kernel/uapi/linux/tcp.h
+ */
+public class TcpInfo {
+    public enum Field {
+        STATE(Byte.BYTES),
+        CASTATE(Byte.BYTES),
+        RETRANSMITS(Byte.BYTES),
+        PROBES(Byte.BYTES),
+        BACKOFF(Byte.BYTES),
+        OPTIONS(Byte.BYTES),
+        WSCALE(Byte.BYTES),
+        DELIVERY_RATE_APP_LIMITED(Byte.BYTES),
+        RTO(Integer.BYTES),
+        ATO(Integer.BYTES),
+        SND_MSS(Integer.BYTES),
+        RCV_MSS(Integer.BYTES),
+        UNACKED(Integer.BYTES),
+        SACKED(Integer.BYTES),
+        LOST(Integer.BYTES),
+        RETRANS(Integer.BYTES),
+        FACKETS(Integer.BYTES),
+        LAST_DATA_SENT(Integer.BYTES),
+        LAST_ACK_SENT(Integer.BYTES),
+        LAST_DATA_RECV(Integer.BYTES),
+        LAST_ACK_RECV(Integer.BYTES),
+        PMTU(Integer.BYTES),
+        RCV_SSTHRESH(Integer.BYTES),
+        RTT(Integer.BYTES),
+        RTTVAR(Integer.BYTES),
+        SND_SSTHRESH(Integer.BYTES),
+        SND_CWND(Integer.BYTES),
+        ADVMSS(Integer.BYTES),
+        REORDERING(Integer.BYTES),
+        RCV_RTT(Integer.BYTES),
+        RCV_SPACE(Integer.BYTES),
+        TOTAL_RETRANS(Integer.BYTES),
+        PACING_RATE(Long.BYTES),
+        MAX_PACING_RATE(Long.BYTES),
+        BYTES_ACKED(Long.BYTES),
+        BYTES_RECEIVED(Long.BYTES),
+        SEGS_OUT(Integer.BYTES),
+        SEGS_IN(Integer.BYTES),
+        NOTSENT_BYTES(Integer.BYTES),
+        MIN_RTT(Integer.BYTES),
+        DATA_SEGS_IN(Integer.BYTES),
+        DATA_SEGS_OUT(Integer.BYTES),
+        DELIVERY_RATE(Long.BYTES),
+        BUSY_TIME(Long.BYTES),
+        RWND_LIMITED(Long.BYTES),
+        SNDBUF_LIMITED(Long.BYTES);
+
+        public final int size;
+
+        Field(int s) {
+            size = s;
+        }
+    }
+
+    private static final String TAG = "TcpInfo";
+    private final LinkedHashMap<Field, Number> mFieldsValues = new LinkedHashMap<Field, Number>();
+
+    private TcpInfo(@NonNull ByteBuffer bytes, int infolen) {
+        final int start = bytes.position();
+        for (final Field field : Field.values()) {
+            switch (field.size) {
+                case Byte.BYTES:
+                    mFieldsValues.put(field, getByte(bytes, start, infolen));
+                    break;
+                case Integer.BYTES:
+                    mFieldsValues.put(field, getInt(bytes, start, infolen));
+                    break;
+                case Long.BYTES:
+                    mFieldsValues.put(field, getLong(bytes, start, infolen));
+                    break;
+                default:
+                    Log.e(TAG, "Unexpected size:" + field.size);
+            }
+        }
+
+    }
+
+    @VisibleForTesting
+    public TcpInfo(@NonNull HashMap<Field, Number> info) {
+        for (final Field field : Field.values()) {
+            mFieldsValues.put(field, info.get(field));
+        }
+    }
+
+    /** Parse a TcpInfo from a giving ByteBuffer with a specific length. */
+    @Nullable
+    public static TcpInfo parse(@NonNull ByteBuffer bytes, int infolen) {
+        try {
+            TcpInfo info = new TcpInfo(bytes, infolen);
+            return info;
+        } catch (BufferUnderflowException e) {
+            Log.e(TAG, "parsing error.", e);
+            return null;
+        }
+    }
+
+    /**
+     * Helper function for handling different struct tcp_info versions in the kernel.
+     */
+    private static boolean isValidOffset(int start, int len, int pos, int targetBytes) {
+        final Range a = new Range(start, start + len);
+        final Range b = new Range(pos, pos + targetBytes);
+        return a.contains(b);
+    }
+
+    /** Get value for specific key. */
+    @Nullable
+    public Number getValue(@NonNull Field key) {
+        return mFieldsValues.get(key);
+    }
+
+    @Nullable
+    private static Byte getByte(@NonNull ByteBuffer buffer, int start, int len) {
+        if (!isValidOffset(start, len, buffer.position(), Byte.BYTES)) return null;
+
+        return buffer.get();
+    }
+
+    @Nullable
+    private static Integer getInt(@NonNull ByteBuffer buffer, int start, int len) {
+        if (!isValidOffset(start, len, buffer.position(), Integer.BYTES)) return null;
+
+        return buffer.getInt();
+    }
+
+    @Nullable
+    private static Long getLong(@NonNull ByteBuffer buffer, int start, int len) {
+        if (!isValidOffset(start, len, buffer.position(), Long.BYTES)) return null;
+
+        return buffer.getLong();
+    }
+
+    private static String decodeWscale(byte num) {
+        return String.valueOf((num >> 4) & 0x0f)  + ":" + String.valueOf(num & 0x0f);
+    }
+
+    /**
+     *  Returns a string representing a given tcp state.
+     *  Map to enum in bionic/libc/include/netinet/tcp.h
+     */
+    @VisibleForTesting
+    public static String getTcpStateName(int state) {
+        switch (state) {
+            case 1: return "TCP_ESTABLISHED";
+            case 2: return "TCP_SYN_SENT";
+            case 3: return "TCP_SYN_RECV";
+            case 4: return "TCP_FIN_WAIT1";
+            case 5: return "TCP_FIN_WAIT2";
+            case 6: return "TCP_TIME_WAIT";
+            case 7: return "TCP_CLOSE";
+            case 8: return "TCP_CLOSE_WAIT";
+            case 9: return "TCP_LAST_ACK";
+            case 10: return "TCP_LISTEN";
+            case 11: return "TCP_CLOSING";
+            default: return "UNKNOWN:" + Integer.toString(state);
+        }
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (!(obj instanceof TcpInfo)) return false;
+        TcpInfo other = (TcpInfo) obj;
+
+        for (final Field key : mFieldsValues.keySet()) {
+            if (!Objects.equals(mFieldsValues.get(key), other.mFieldsValues.get(key))) {
+                return false;
+            }
+        }
+        return true;
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(mFieldsValues.values().toArray());
+    }
+
+    @Override
+    public String toString() {
+        String str = "TcpInfo{ ";
+        for (final Field key : mFieldsValues.keySet()) {
+            str += key.name().toLowerCase() + "=";
+            if (key == Field.STATE) {
+                str += getTcpStateName(mFieldsValues.get(key).intValue()) + " ";
+            } else if (key == Field.WSCALE) {
+                str += decodeWscale(mFieldsValues.get(key).byteValue()) + " ";
+            } else {
+                str += mFieldsValues.get(key) + " ";
+            }
+        }
+        str += "}";
+        return str;
+    }
+}