Question

I am transferring files using c#. I have used this code. The problem is small files like .txt files are transferred correctly but not big files like images, documents, pdf, ppt. Sometimes code works fine but most of the times it transfers less amount of data.

Server Code:

Socket clientSock = sock.Accept();

byte[] clientData = new byte[1024 * 50000];
int receivedBytesLen = clientSock.Receive(clientData);
int fileNameLen = BitConverter.ToInt32(clientData, 0);
string fileName = Encoding.ASCII.GetString(clientData, 4, fileNameLen);
BinaryWriter bWrite = new BinaryWriter(File.Open(receivedPath + "/" + fileName, FileMode.Append));
bWrite.Write(clientData, 4 + fileNameLen, receivedBytesLen - 4 - fileNameLen);
bWrite.Close();
clientSock.Close();

Client Code:

byte[] fileNameByte = Encoding.ASCII.GetBytes(fileName);
byte[] fileData = File.ReadAllBytes(filePath + fileName);
byte[] clientData = new byte[4 + fileNameByte.Length + fileData.Length];
byte[] fileNameLen = BitConverter.GetBytes(fileNameByte.Length);
fileNameLen.CopyTo(clientData, 0);
fileNameByte.CopyTo(clientData, 4);
fileData.CopyTo(clientData, 4 + fileNameByte.Length);
clientSock.Connect(ipEnd);
clientSock.Send(clientData);
clientSock.Close();

Complete code is given in the above link. I have also seen this post but this is not helpful.

Answer 1

As CodeCaster’s answered that Socket.Receive(), it doesn't always return all data that gets sent to it. This is 100% correct and tested but the next step of sending the file size is not working, I found an easy and correct solution.

Socket.Receive() method takes the byte array in which received data will be copied and returns the number of bytes received. So we can easily loop it till bytes received are 0.

byte[] tempData = new byte[1024 * 5000];

BinaryWriter bWrite = null;
int bytes_received;
int fileNamelength = 0;
bool isFirstPacket = true;

do
{
    bytes_received = clientSock.Receive(tempData);
    if(isFirstPacket)
    {
        isFirstPacket = false;
        int fileNameLen = BitConverter.ToInt32(tempData, 0);
        string fileName = Encoding.ASCII.GetString(clientData, 4, fileNameLen);

        bWrite = new BinaryWriter(File.Open(receivedPath + fileName, FileMode.Append))
        bWrite.Write(tempData, 4 + fileNameLength, bytes_received - 4 - fileNamelength);
    }
    else
        bWrite.Write(tempData, 0, bytes_received);
}
while (bytes_received != 0);