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using System;
using System.IO;
using System.Linq;
using System.Security.Cryptography;
public partial class MAVLink
{
public static string GetUnit(string fieldname, Type packetype = null, string name="", uint msgid = UInt32.MaxValue)
{
try
{
message_info msginfo = new message_info();
if(packetype != null)
msginfo = MAVLink.MAVLINK_MESSAGE_INFOS.First(a => a.type == packetype);
if (msgid != UInt32.MaxValue)
msginfo = MAVLink.MAVLINK_MESSAGE_INFOS.First(a => a.msgid == msgid);
if (!string.IsNullOrEmpty(name))
msginfo = MAVLink.MAVLINK_MESSAGE_INFOS.First(a => a.name == name);
if (msginfo.name == "")
return "";
var typeofthing = msginfo.type.GetField(fieldname);
if (typeofthing != null)
{
var attrib = typeofthing.GetCustomAttributes(false);
if (attrib.Length > 0)
return attrib.OfType<MAVLink.Units>().First().Unit;
}
}
catch
{
}
return "";
}
public class Units : Attribute
{
public Units(string unit)
{
Unit = unit;
}
public string Unit { get; set; }
}
public class Description : Attribute
{
public Description(string desc)
{
Text = desc;
}
public string Text { get; set; }
}
public class MavlinkParse
{
public int packetcount = 0;
public int badCRC = 0;
public int badLength = 0;
public bool hasTimestamp = false;
public MavlinkParse(bool hasTimestamp = false)
{
this.hasTimestamp = hasTimestamp;
}
public static void ReadWithTimeout(Stream BaseStream, byte[] buffer, int offset, int count)
{
int timeout = 500;
if (BaseStream.CanSeek)
{
timeout = 0;
if((BaseStream.Position + count) > BaseStream.Length)
throw new EndOfStreamException("End of data");
}
if (BaseStream.CanTimeout)
{
timeout = BaseStream.ReadTimeout;
if (timeout == -1)
timeout = 60000;
}
DateTime to = DateTime.Now.AddMilliseconds(timeout);
int toread = count;
int pos = offset;
while (true)
{
// read from stream
int read = BaseStream.Read(buffer, pos, toread);
// update counter
toread -= read;
pos += read;
// reset timeout if we get data
if (read > 0)
to = DateTime.Now.AddMilliseconds(timeout);
if (toread == 0)
break;
if (DateTime.Now > to)
{
throw new TimeoutException("Timeout waiting for data");
}
System.Threading.Thread.Sleep(1);
}
}
public MAVLinkMessage ReadPacket(Stream BaseStream)
{
byte[] buffer = new byte[MAVLink.MAVLINK_MAX_PACKET_LEN];
DateTime packettime = DateTime.MinValue;
if (hasTimestamp)
{
byte[] datearray = new byte[8];
int tem = BaseStream.Read(datearray, 0, datearray.Length);
Array.Reverse(datearray);
DateTime date1 = new DateTime(1970, 1, 1, 0, 0, 0, DateTimeKind.Utc);
UInt64 dateint = BitConverter.ToUInt64(datearray, 0);
if ((dateint / 1000 / 1000 / 60 / 60) < 9999999)
{
date1 = date1.AddMilliseconds(dateint / 1000);
packettime = date1.ToLocalTime();
}
}
int readcount = 0;
while (readcount <= MAVLink.MAVLINK_MAX_PACKET_LEN)
{
// read STX byte
ReadWithTimeout(BaseStream, buffer, 0, 1);
if (buffer[0] == MAVLink.MAVLINK_STX || buffer[0] == MAVLINK_STX_MAVLINK1)
break;
readcount++;
}
if (readcount >= MAVLink.MAVLINK_MAX_PACKET_LEN)
{
return null;
throw new InvalidDataException("No header found in data");
}
var headerlength = buffer[0] == MAVLINK_STX ? MAVLINK_CORE_HEADER_LEN : MAVLINK_CORE_HEADER_MAVLINK1_LEN;
var headerlengthstx = headerlength + 1;
// read header
try {
ReadWithTimeout(BaseStream, buffer, 1, headerlength);
}
catch (EndOfStreamException)
{
return null;
}
// packet length
int lengthtoread = 0;
if (buffer[0] == MAVLINK_STX)
{
lengthtoread = buffer[1] + headerlengthstx + 2 - 2; // data + header + checksum - magic - length
if ((buffer[2] & MAVLINK_IFLAG_SIGNED) > 0)
{
lengthtoread += MAVLINK_SIGNATURE_BLOCK_LEN;
}
}
else
{
lengthtoread = buffer[1] + headerlengthstx + 2 - 2; // data + header + checksum - U - length
}
try
{
//read rest of packet
ReadWithTimeout(BaseStream, buffer, headerlengthstx, lengthtoread - (headerlengthstx - 2));
}
catch (EndOfStreamException)
{
return null;
}
// resize the packet to the correct length
Array.Resize<byte>(ref buffer, lengthtoread + 2);
MAVLinkMessage message = new MAVLinkMessage(buffer, packettime);
// calc crc
ushort crc = MavlinkCRC.crc_calculate(buffer, buffer.Length - 2);
// calc extra bit of crc for mavlink 1.0+
if (message.header == MAVLINK_STX || message.header == MAVLINK_STX_MAVLINK1)
{
crc = MavlinkCRC.crc_accumulate(MAVLINK_MESSAGE_INFOS.GetMessageInfo(message.msgid).crc, crc);
}
// check crc
if ((message.crc16 >> 8) != (crc >> 8) ||
(message.crc16 & 0xff) != (crc & 0xff))
{
badCRC++;
// crc fail
return null;
}
return message;
}
public byte[] GenerateMAVLinkPacket10(MAVLINK_MSG_ID messageType, object indata, byte sysid = 255, byte compid = (byte)MAV_COMPONENT.MAV_COMP_ID_MISSIONPLANNER, int sequence = -1)
{
byte[] data;
data = MavlinkUtil.StructureToByteArray(indata);
byte[] packet = new byte[data.Length + 6 + 2];
packet[0] = MAVLINK_STX_MAVLINK1;
packet[1] = (byte)data.Length;
packet[2] = (byte)packetcount;
if (sequence != -1)
packet[2] = (byte)sequence;
packetcount++;
packet[3] = sysid; // this is always 255 - MYGCS
packet[4] = compid;
packet[5] = (byte)messageType;
int i = 6;
foreach (byte b in data)
{
packet[i] = b;
i++;
}
ushort checksum = MavlinkCRC.crc_calculate(packet, packet[1] + 6);
checksum = MavlinkCRC.crc_accumulate(MAVLINK_MESSAGE_INFOS.GetMessageInfo((uint)messageType).crc, checksum);
byte ck_a = (byte)(checksum & 0xFF); ///< High byte
byte ck_b = (byte)(checksum >> 8); ///< Low byte
packet[i] = ck_a;
i += 1;
packet[i] = ck_b;
i += 1;
return packet;
}
public byte[] GenerateMAVLinkPacket20(MAVLINK_MSG_ID messageType, object indata, bool sign = false, byte sysid = 255, byte compid= (byte)MAV_COMPONENT.MAV_COMP_ID_MISSIONPLANNER, int sequence = -1)
{
byte[] data;
data = MavlinkUtil.StructureToByteArray(indata);
MavlinkUtil.trim_payload(ref data);
int extra = 0;
if (sign)
extra = MAVLINK_SIGNATURE_BLOCK_LEN;
byte[] packet = new byte[data.Length + MAVLINK_NUM_NON_PAYLOAD_BYTES + extra];
packet[0] = MAVLINK_STX;
packet[1] = (byte)data.Length;
packet[2] = 0;//incompat signing
if (sign)
packet[2] |= MAVLINK_IFLAG_SIGNED;
packet[3] = 0;//compat
packet[4] = (byte)packetcount;
if (sequence != -1)
packet[4] = (byte)sequence;
packetcount++;
packet[5] = sysid;
packet[6] = compid;
packet[7] = (byte)((UInt32)messageType);
packet[8] = (byte)((UInt32)messageType >> 8);
packet[9] = (byte)((UInt32)messageType >> 16);
int i = MAVLINK_NUM_HEADER_BYTES;
foreach (byte b in data)
{
packet[i] = b;
i++;
}
ushort checksum = MavlinkCRC.crc_calculate(packet, data.Length + MAVLINK_NUM_HEADER_BYTES);
checksum = MavlinkCRC.crc_accumulate(MAVLINK_MESSAGE_INFOS.GetMessageInfo((uint)messageType).crc, checksum);
byte ck_a = (byte)(checksum & 0xFF); ///< High byte
byte ck_b = (byte)(checksum >> 8); ///< Low byte
packet[i] = ck_a;
i += 1;
packet[i] = ck_b;
i += 1;
if (sign)
{
//https://docs.google.com/document/d/1ETle6qQRcaNWAmpG2wz0oOpFKSF_bcTmYMQvtTGI8ns/edit
/*
8 bits of link ID
48 bits of timestamp
48 bits of signature
*/
// signature = sha256_48(secret_key + header + payload + CRC + link-ID + timestamp)
var timestamp = (UInt64)((DateTime.UtcNow - new DateTime(2015, 1, 1)).TotalMilliseconds * 100);
if (timestamp == lasttimestamp)
timestamp++;
lasttimestamp = timestamp;
var timebytes = BitConverter.GetBytes(timestamp);
var sig = new byte[7]; // 13 includes the outgoing hash
sig[0] = sendlinkid;
Array.Copy(timebytes, 0, sig, 1, 6); // timestamp
//Console.WriteLine("gen linkid {0}, time {1} {2} {3} {4} {5} {6} {7}", sig[0], sig[1], sig[2], sig[3], sig[4], sig[5], sig[6], timestamp);
if (signingKey == null || signingKey.Length != 32)
{
signingKey = new byte[32];
}
using (SHA256 signit = SHA256.Create())
{
MemoryStream ms = new MemoryStream();
ms.Write(signingKey, 0, signingKey.Length);
ms.Write(packet, 0, i);
ms.Write(sig, 0, sig.Length);
var ctx = signit.ComputeHash(ms.ToArray());
// trim to 48
Array.Resize(ref ctx, 6);
foreach (byte b in sig)
{
packet[i] = b;
i++;
}
foreach (byte b in ctx)
{
packet[i] = b;
i++;
}
}
}
return packet;
}
public byte sendlinkid { get; set; }
public ulong lasttimestamp { get; set; }
public byte[] signingKey { get; set; }
}
}