/// <summary>
/// Checks the first four bytes for the total Trace Length
/// Stores the length in _POLLDATA object and Enqueues all bytes
/// </summary>
/// <param name="blok">the bytes that contain the Trace Length, plus possible overflow</param>
/// <returns>-1 if less than four bytes have been received, otherwise the length of the trace data</returns>
private long StoreTraceLength(byte[] newBlok)
{
byte[] blok;
if (_POLLDATA.DataQ.Count == 1) //get the previous blok, should never be greater than 1
{ //Combine into 1 blok
byte[] prevBlok = (byte[])_POLLDATA.DataQ.Dequeue();
int len = prevBlok.Length + newBlok.Length;
blok = new byte[len];
int i = 0;
for (i = 0; i < prevBlok.Length; i++)
{
blok[i] = prevBlok[i];
}
for (i = prevBlok.Length; i < len; i++)
{
blok[i] = newBlok[i];
}
}
else
{
blok = newBlok;
}
long traceLen = -1;
if (blok.Length >= 4)
{
traceLen = (long)SVSEUtility.GetUINT32(0, blok);
}
_POLLDATA.DataQ.Enqueue(blok);
return(traceLen);
}
/// <summary>
/// Read each packet
/// </summary>
/// <param name="data">All of the IP packets,
/// this data contains a 12 byte header before each packet
/// with a 4 byte length and a 8 byte store clock</param>
/// <param name="offset">offset into the data of this packet</param>
/// <returns>offset of next packet</returns>
private int ReadNextPacket(int offset, byte[] data, out PcapIpPacket packet, bool writeDebug)
{
//RawDataConverter convert = new RawDataConverter();
uint len = SVSEUtility.GetUINT32(offset, data);
DateTime stck = SVSEUtility.GetDateTimeUTC(offset + 4, data);//8 byte STCK
int offPack = offset + 12;
//int verFromIpHeader = Convert.ToInt32(data[offPack]);
ushort lenFromIpHeader = SVSEUtility.GetUINT16(offPack + 2, data);//2 bytes into the packet header
packet = new PcapIpPacket();
if (writeDebug)
{
Debug.WriteLine( //"[ " + verFromIpHeader.ToString() + " ]"
"packet offset = " + offPack.ToString("X").PadRight(8, '0') + //should be 69 for a IPv4 header
" : STCK(ss:us) = " + SVSEUtility.GetUINT64(offset + 4, data).ToString("X") + " = " + SVSEUtility.GetDateTimeUTC(offset + 4, data).ToString("MM-dd-yyyy HH:mm:ss:ffffff") +
" : Length = " + len.ToString().PadRight(5, ' ') + "...from IP header = " + lenFromIpHeader.ToString());
}
//if (verFromIpHeader == 69)//0x45 = IPv4 with a 40 byte IP header
//{
DateTime utcJan11970 = new DateTime(1970, 1, 1, 0, 0, 0).ToUniversalTime(); //UTC time on Jan 1, 1970 00:00:00
TimeSpan tspan = stck.Subtract(utcJan11970); //The timespan between Jan 1, 1970 00:00:00 and the capture
uint tsSeconds = 0; //The number of seconds in the timespan
uint tsUseconds = 0; //The usec offset
if (tspan.TotalSeconds > 0)
{ /* tsSeconds must be rounded down with Math.Floor */
tsSeconds = Convert.ToUInt32(Math.Floor(tspan.TotalSeconds)); //Total seconds since Jan 1, 1970 00:00:00
tsUseconds = Convert.ToUInt32(tspan.Milliseconds * 1000); //Usec offset
}
uint inclLength = len; //# of bytes actually saved in file
uint origLength = lenFromIpHeader; //# of bytes in packet when it was captured, in case snaplen trims it
/* Get the header and data */
byte[] ipPack = new byte[inclLength];
for (int i = 0; i < ipPack.Length; i++)
{
ipPack[i] = data[offPack + i];
}
packet = new PcapIpPacket(tsSeconds, tsUseconds, inclLength, origLength, ipPack);
//}else if(writeDebug){Debug.Write("*ERROR not IPv4*");}
return(offPack + Convert.ToInt32(len));
}
