1 /* 2 * Copyright (C) 2016 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package android.system; 18 19 import static android.system.OsConstants.ICMP6_ECHO_REQUEST; 20 import static android.system.OsConstants.ICMP_ECHO; 21 22 /** 23 * Corresponds to C's {@code struct icmphdr} from linux/icmp.h and {@code struct icmp6hdr} from 24 * linux/icmpv6.h 25 * 26 * @hide 27 */ 28 public final class StructIcmpHdr { 29 private byte[] packet; 30 StructIcmpHdr()31 private StructIcmpHdr() { 32 packet = new byte[8]; 33 } 34 35 /* 36 * Echo or Echo Reply Message 37 * 38 * 0 1 2 3 39 * 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 40 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 41 * | Type | Code | Checksum | 42 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 43 * | Identifier | Sequence Number | 44 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 45 * | Data ... 46 * +-+-+-+-+- 47 */ IcmpEchoHdr(boolean ipv4, int seq)48 public static StructIcmpHdr IcmpEchoHdr(boolean ipv4, int seq) { 49 StructIcmpHdr hdr = new StructIcmpHdr(); 50 hdr.packet[0] = ipv4 ? (byte) ICMP_ECHO : (byte) ICMP6_ECHO_REQUEST; 51 // packet[1]: Code is always zero. 52 // packet[2,3]: Checksum is computed by kernel. 53 // packet[4,5]: ID (= port) inserted by kernel. 54 hdr.packet[6] = (byte) (seq >> 8); 55 hdr.packet[7] = (byte) seq; 56 return hdr; 57 } 58 getBytes()59 public byte[] getBytes() { 60 return packet.clone(); 61 } 62 } 63