| /* |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF 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 org.apache.drill.exec.store.pcap.decoder; |
| |
| import com.google.common.base.Preconditions; |
| import org.slf4j.Logger; |
| import org.slf4j.LoggerFactory; |
| |
| import java.io.IOException; |
| import java.io.InputStream; |
| |
| import static org.apache.drill.exec.store.pcap.PcapFormatUtils.getInt; |
| import static org.apache.drill.exec.store.pcap.PcapFormatUtils.getIntFileOrder; |
| import static org.apache.drill.exec.store.pcap.PcapFormatUtils.getShortFileOrder; |
| |
| public class PacketDecoder { |
| // typedef struct pcap_hdr_s { |
| // guint32 magic_number; /* magic number */ |
| // guint16 version_major; /* major version number */ |
| // guint16 version_minor; /* minor version number */ |
| // gint32 thiszone; /* GMT to local correction */ |
| // guint32 sigfigs; /* accuracy of timestamps */ |
| // guint32 snaplen; /* max length of captured packets, in octets */ |
| // guint32 network; /* data link type */ |
| // } pcap_hdr_t; |
| // magic_number: used to detect the file format itself and the byte ordering. The writing application writes |
| // 0xa1b2c3d4 with it's native byte ordering format into this field. The reading application will read |
| // either 0xa1b2c3d4 (identical) or 0xd4c3b2a1 (swapped). If the reading application reads the swapped |
| // 0xd4c3b2a1 value, it knows that all the following fields will have to be swapped too. For |
| // nanosecond-resolution files, the writing application writes 0xa1b23c4d, with the two nibbles |
| // of the two lower-order bytes swapped, and the reading application will read either 0xa1b23c4d |
| // (identical) or 0x4d3cb2a1 (swapped). |
| // version_major, version_minor: the version number of this file format (current version is 2.4) |
| // thiszone: the correction time in seconds between GMT (UTC) and the local timezone of the following |
| // packet header timestamps. Examples: If the timestamps are in GMT (UTC), thiszone is simply 0. |
| // If the timestamps are in Central European time (Amsterdam, Berlin, ...) which is GMT + 1:00, |
| // thiszone must be -3600. In practice, time stamps are always in GMT, so thiszone is always 0. |
| // sigfigs: in theory, the accuracy of time stamps in the capture; in practice, all tools set it to 0 |
| // snaplen: the "snapshot length" for the capture (typically 65535 or even more, but might be limited |
| // by the user), see: incl_len vs. orig_len below |
| // network: link-layer header type, specifying the type of headers at the beginning of the packet (e.g. |
| // 1 for Ethernet, see tcpdump.org's link-layer header types page for details); this can be various |
| // types such as 802.11, 802.11 with various radio information, PPP, Token Ring, FDDI, etc. |
| private static final int GLOBAL_HEADER_SIZE = 24; |
| private static final int PCAP_MAGIC_LITTLE_ENDIAN = 0xD4C3B2A1; |
| private static final int PCAP_MAGIC_NUMBER = 0xA1B2C3D4; |
| private static final int PCAPNG_MAGIC_LITTLE_ENDIAN = 0x4D3C2B1A; |
| private static final int PCAPNG_MAGIC_NUMBER = 0x0A0D0D0A; |
| |
| private static final Logger logger = LoggerFactory.getLogger(PacketDecoder.class); |
| |
| private final int maxLength; |
| private final int network; |
| private boolean bigEndian; |
| private FileFormat fileFormat; |
| |
| private InputStream input; |
| |
| public PacketDecoder(final InputStream input) throws IOException { |
| this.input = input; |
| byte[] globalHeader = new byte[GLOBAL_HEADER_SIZE]; |
| int n = input.read(globalHeader); |
| if (n != globalHeader.length) { |
| throw new IOException("Can't read PCAP file header"); |
| } |
| switch (getInt(globalHeader, 0)) { |
| case PCAP_MAGIC_NUMBER: |
| bigEndian = true; |
| fileFormat = FileFormat.PCAP; |
| break; |
| case PCAP_MAGIC_LITTLE_ENDIAN: |
| bigEndian = false; |
| fileFormat = FileFormat.PCAP; |
| break; |
| case PCAPNG_MAGIC_NUMBER: |
| bigEndian = true; |
| fileFormat = FileFormat.PCAPNG; |
| break; |
| case PCAPNG_MAGIC_LITTLE_ENDIAN: |
| bigEndian = false; |
| fileFormat = FileFormat.PCAPNG; |
| break; |
| default: |
| //noinspection ConstantConditions |
| Preconditions.checkState(false, |
| String.format("Bad magic number = %08x", getIntFileOrder(bigEndian, globalHeader, 0))); |
| } |
| if(fileFormat == FileFormat.PCAP) { |
| Preconditions.checkState(getShortFileOrder(bigEndian, globalHeader, 4) == 2, "Wanted major version == 2"); |
| } // todo: pcapng major version == 1 precondition |
| maxLength = getIntFileOrder(bigEndian, globalHeader, 16); |
| network = getIntFileOrder(bigEndian, globalHeader, 20); |
| } |
| |
| public final int getMaxLength() { |
| return maxLength; |
| } |
| |
| public int decodePacket(final byte[] buffer, final int offset, Packet p, int maxPacket, int validBytes) { |
| int r = p.decodePcap(buffer, offset, bigEndian, Math.min(maxPacket, validBytes - offset)); |
| if (r > validBytes) { |
| logger.error("Invalid packet at offset {}", offset); |
| } |
| return r; |
| } |
| |
| public Packet packet() { |
| return new Packet(); |
| } |
| |
| public int getNetwork() { |
| return network; |
| } |
| |
| public boolean isBigEndian() { |
| return bigEndian; |
| } |
| |
| public FileFormat getFileFormat() { |
| return fileFormat; |
| } |
| |
| public Packet nextPacket() throws IOException { |
| Packet r = new Packet(); |
| if (r.readPcap(input, bigEndian, maxLength)) { |
| return r; |
| } else { |
| return null; |
| } |
| } |
| |
| public enum FileFormat { |
| PCAP, |
| PCAPNG, |
| UNKNOWN |
| } |
| } |