private byte[] getPreBuffer()
{
// get md5 hash
ChecksumCalc checksum = new ChecksumCalc();
byte[] md5 = checksum.GetMD5Checksum(filePath);
FileInfo f = new FileInfo(filePath);
// Using windows 1252 encoding
Encoding encoding1252 = Encoding.GetEncoding(1252);
//byte[] fileName = Encoding.ASCII.GetBytes(f.Name);
byte[] fileName = encoding1252.GetBytes(f.Name);
byte[] filenameSizePlusFilename = new byte[fileName.Length + 1];
// copy byte representing the size of the filename
// to the beginning of the first packet sent
int length = fileName.Length;
byte lengthB = (byte)length;
new byte[] { lengthB }.CopyTo(filenameSizePlusFilename, 0);
// copies file name in ASCII format from index 1 to length of filename
Array.Copy(fileName, 0, filenameSizePlusFilename, 1, fileName.Length);
// get file size and convert to 8 bytes
long fileSize = f.Length;
byte[] fileSizeB = BitConverter.GetBytes(fileSize);
// preBuffer has size:
// file name +
// 1 byte for file name size +
// 8 bytes is the size of the file +
// 16 bytes is the md5 hash of the file
byte[] preBuffer = new byte[fileName.Length + 1 + 8 + 16];
// copy file name size and file name to preBuffer
filenameSizePlusFilename.CopyTo(preBuffer, 0);
// copy fileSizeB to end of preBuffer
Array.Copy(fileSizeB, 0, preBuffer, fileName.Length + 1, 8);
// copy md5 hash to preBuffer
Array.Copy(md5, 0, preBuffer, fileName.Length + 1 + 8, 16);
// format the transfer like this:
// byte = filename size
// file name
// long = file size in bytes, ulong is 64 bit so filesize could be limitless
// 16 bytes md5 hash of file
// file content
return(preBuffer);
}
public void ReadCallback(IAsyncResult ar)
{
StateObject tempState = (StateObject)ar.AsyncState;
Socket handler = tempState.workSocket;
// handle connection problems
int bytesRead = 0;
try
{
bytesRead = handler.EndReceive(ar);
}
catch (SocketException socketError)
{
Console.WriteLine("Socket error while transfering: " + socketError.Message);
Console.WriteLine("Reseting connection...");
resetConnection();
}
catch (Exception error)
{
Console.WriteLine("Error while transfering: " + error.Message);
return;
}
if (bytesRead <= 0)
{
return;
}
// add to counter
counter.AddBytes((uint)bytesRead);
if (isFirstPacket)
{
try
{
// gets the first byte
byte[] firstByte = new byte[1];
firstByte = tempState.buffer.Take(1).ToArray();
// first byte has a value 0 - 255
fileNameLength = Convert.ToInt32(firstByte[0]);
// a fileName cannot be more then 255 characters because a byte cannot have have a higher value...
if (fileNameLength > 255)
{
// filename is not valid...
// this should not happen, should somehow at least validate the first packet to ensure
// it contain the right information...
return;
//fileNameLength = 255;
}
// TODO:
// check if fileName is valid
// Windows 1252 encoding
Encoding encoding1252 = Encoding.GetEncoding(1252);
fileName = encoding1252.GetString(tempState.buffer, 1, fileNameLength);
// after the file name comes the size of the file
// should be a long
// that is 64 bit = 8 byte
byte[] fileSizeB = tempState.buffer.Skip(1 + fileNameLength).Take(8).ToArray();
fileSize = BitConverter.ToInt64(fileSizeB, 0);
// get md5 hash
// md5 hash is 16 bytes = 128 bit
md5 = tempState.buffer.Skip(1 + fileNameLength + 8).Take(16).ToArray();
// set total to be received
totalBytesToBeReceived = fileNameLength + fileSize + 9 + 16;
// TODO:
// get FileInfo object
// TODO:
// start download counter, datetime, total filesize to download etc
// get MD5 hash or other hash of file
// make sure all meta data and other stuff is actually sent
// calculate hash of when file has been received and written to a file here
// close socket and stop thread when entire file has been written
// start timer that will execute an event every 1 sec
// that shows mb/s kb/s etc
timer = new System.Timers.Timer()
{
Interval = 1000, Enabled = true
};
timer.Elapsed += timer_Elapsed;
timer.Start();
}
catch (InvalidCastException castError)
{
// was not able to find file size
Console.WriteLine(castError.Message);
return;
}
catch (Exception error)
{
Console.WriteLine(error.Message);
return;
}
}
BinaryWriter writer = null;
try
{
// TODO:
// only open file while it is not in use
// wait until file is ready to be written to
if (isFirstPacket)
{
// old way
//writer = new BinaryWriter(File.Open(savePathAndFileName, FileMode.Append));
// TODO:
// check that file name and path is correct
string savePathAndFileName = receivePath + "\\" + fileName;
// check if file already exist
// if it does, simply append to the file
if (File.Exists(savePathAndFileName))
{
// TODO:
// check if md5 hash of existing file is correct
// if so, stop transfer
// TODO:
// if md5 hash is not the same, check file size of existing file
// if its bigger than it's supposed too, remove it
// if not, start appending to the file
Console.WriteLine("File already exist, appending to file...");
fileWriter = new ParallelFileWriter(savePathAndFileName, 200, true);
}
else
{
// creates a thread pool using BlockingCollection
// this will allow a queue of max 200 threads waiting to write to the file
// if more than 200 threads are created, they are blocked and wait until the '
// queue is free
fileWriter = new ParallelFileWriter(savePathAndFileName, 200);
}
// the first packet contain information that should not be written to the file itself so
// if first packet then increase the index to size of fileName + one byte
// since we increase the index, we need to reduce the count by the same amount
// + 1 byte for size of fileName byte
// + 8 bytes for 64 bit long with file size
// + 16 bytes for md5 hash
// shift = 9 bytes + fileName
int shift = fileNameLength + 9 + 16;
//writer.Write(tempState.buffer, shift, bytesRead - shift);
byte[] data = new byte[bytesRead - shift];
Array.Copy(tempState.buffer, shift, data, 0, bytesRead - shift);
fileWriter.Write(data);
isFirstPacket = false;
// set fileName, but do not trigger event
FileTransferEvents.filename = fileName;
}
else
{
byte[] data = new byte[bytesRead];
Array.Copy(tempState.buffer, 0, data, 0, bytesRead);
fileWriter.Write(data);
//writer.Write(tempState.buffer, 0, bytesRead);
}
// add to written files
totalBytesReceived += bytesRead;
// check if all bytes has been read and transfer is complete
if (totalBytesReceived == totalBytesToBeReceived)
{
// trigger file received event
FileTransferEvents.FileReceived = fileName;
// get file location
string savePathAndFileName = receivePath + "\\" + fileName;
// reset connection
// set everything back to default and wait for new file
resetConnection();
// close file writer so we can access file again
if (writer != null)
{
writer.Close();
}
// complete writing tasks and threads
fileWriter.Dispose();
Console.WriteLine("Calculating md5 hash of received file...");
// get md5 hash
ChecksumCalc checksum = new ChecksumCalc();
byte[] md5AfterTransfer = checksum.GetMD5Checksum(savePathAndFileName);
// check if md5 received is identical to md5 calculated after transfer
bool isIdentical = checksum.checkIfHashisIdentical(md5, md5AfterTransfer);
if (isIdentical)
{
// the hash received before the file transfer is identical to the
// hash calculated with the new file
Console.WriteLine("SUCCESS: md5 hash match the md5 of received file");
}
else
{
// delete file?
Console.WriteLine("ERROR: File is corrupt, md5 hash does NOT match the md5 of the file received");
}
}
}
catch (Exception error)
{
Console.WriteLine(error.Message);
Thread.Sleep(30);
}
finally
{
if (writer != null)
{
writer.Close();
}
// triggers event with long of bytes written
//FileTransferEvents.BytesReceived = written;
// this method starts a new AsyncCallback(ReadCallback)
// and this method is ReadCallback so it works as a recursive method
try
{
handler.BeginReceive(tempState.buffer, 0, StateObject.BufferSize, 0, new AsyncCallback(ReadCallback), tempState);
}
catch (SocketException socketError)
{
Console.WriteLine("Socket error while transfering: " + socketError.Message);
Console.WriteLine("Reseting connection...");
resetConnection();
}
catch (Exception error)
{
Console.WriteLine("Error while transfering: " + error.Message);
}
}
}
