using python to send an image over TCP to c# server

Question

I am working on a project that uses a python script to send an image taken with a webcam to a c# webserver using sockets. I am currently sending strings to the server from the python client using code like:

info = bytearray("Text to send", "UTF-8")
socket.send(info)

to send data to the c# server and it functions perfectly for text and numbers. I run into an issue when trying to encode the data read from the .bmp into "UTF-8", as trying this returns an error of not being able to encode certain characters into UTF-8.

I was wondering if anyone had any idea of a way to encode this that c# will be able to recognize, or, if there is a better way of trying to implement this process, I am all ears.

A couple of options I have come up with would be to 1 - use something like google drive to save the image to, or an FTP server and then have the c# server retrieve it from there or 2 - create a packet system containing the RGB values and recreating the image from those pixel values on the server.

Thanks for your help.

EDIT: I have tried sending the file this way

 data = bytearray("123456789","UTF-8")
 file = open("image.bmp", "rb")
 data += file.read()
 socket.send(data)

and was able to successfully retreive the string "123456789", but the data after this is garbage. I have also implemented sending the size of the file before sending the data and that size number is retrieved fine, but the img data saves as a black bmp.

Edit 2 :

Here is the server and client code I am using to try and recreate the image using a memory stream. I the client code is using the process mentioned by hcalves.

Client

if __name__ == "__main__":
sock = socket.socket()
sock.connect(("localhost", 50839))

with open("image.bmp", "rb") as fd:
    buf = fd.read(1024)
    while (buf):
        sock.send(buf)
        buf = fd.read(1024)
sock.close()

Server

Socket client = server.AcceptSocket();
NetworkStream stream = new NetworkStream(client);
byte[] imgData = new byte[1024];
MemoryStream memstream = new MemoryStream();
stream.Read(imgData,0, 1024);
int counter = 0;
while (stream.DataAvailable)
{
    memstream.Write(imgData, 0, 1024);
    stream.Read(imgData, 0, 1024);
    counter = counter + 1024;
}

memstream.Seek(0, SeekOrigin.Begin);

using (Stream file = File.OpenWrite("img.bmp"))
{
    byte[] buffer = new byte[8*1024];
    int len;
    while ((len = memstream.Read(buffer, 0, buffer.Length)) > 0)
    {
        file.Write(buffer,0,len);
    }
}

Answer 1

You shouldn't need more than this recipe:

import socket

if __name__ == "__main__":
    sock = socket.socket()
    sock.connect(("localhost", 50839))

    with open("data.bin", "rb") as fd:
        buf = fd.read(1024)
        while (buf):
            sock.send(buf)
            buf = fd.read(1024)
    sock.close()

For practical reasons, you can treat str objects (the result of fd.read) as raw data, you don't need any further crazy encoding. Just iterate the file and send over the socket. Test by running this server which just echoes to stdout with python server.py > data2.bin:

import socket
import sys

if __name__ == "__main__":
    sock = socket.socket()
    sock.bind(("localhost", 50839))
    sock.listen(1)

    client, address = sock.accept()

    buf = client.recv(1024)
    while (buf):
        sys.stdout.write(buf)
        buf = client.recv(1024)

    client.close()
    sock.close()

A checksum shows the binary data is sent correctly:

% md5 data.bin data2.bin      
MD5 (data.bin) = 8b3280072275badf3e53a6f7aae0b8be
MD5 (data2.bin) = 8b3280072275badf3e53a6f7aae0b8be

Your C# server should be able to accept this data as is. If it doesn't work, it's because your server is expecting something in particular, not just raw data.