This is how I send a file using a NetworkStream.
private void go() { byte[] send = File.ReadAllBytes("example.txt"); ns.Write(send, 0, send.Length); } ns is a NetworkStream of course.
Now I would like to know how I could receive and read an incoming NetworkStream?
I know that I need to specify a buffer to read from like this,
ns.Read(buffer,0,buffer.length). but which buffer should be there?
TCP is a stream based protocol, which means that there is no notation of application messages like in UDP. Thus you cannot really detect by TCP itself where an application message ends.
Therefore you need to introduce some kind of detection. Typically you add a suffix (new line, semicolon or whatever) or a length header.
In this case it's easier to add a length header since the chosen suffix could be found in the file data.
So sending the file would look like this:
private void SendFile(string fileName, NetworkStream ns) { var bytesToSend = File.ReadAllBytes(fileName); var header = BitConverter.GetBytes(bytesToSend.Length); ns.Write(header, 0, header.Length); ns.Write(bytesToSend, 0, bytesToSend.Length); } On the receiver side it's important that you check the return value from Read as contents can come in chunks:
public byte[] ReadFile(NetworkStream ns) { var header = new byte[4]; var bytesLeft = 4; var offset = 0; // have to repeat as messages can come in chunks while (bytesLeft > 0) { var bytesRead = ns.Read(header, offset, bytesLeft); offset += bytesRead; bytesLeft -= bytesRead; } bytesLeft = BitConverter.ToInt32(header, 0); offset = 0; var fileContents = new byte[bytesLeft]; // have to repeat as messages can come in chunks while (bytesLeft > 0) { var bytesRead = ns.Read(fileContents, offset, bytesLeft); offset += bytesRead; bytesLeft -= bytesRead; } return fileContents; } 
