Tcpclient send [FIN, ACK]

Question

Malin 2023-2-17

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1914430-tcpclient-send-fin-ack

评论： Malin 2023-3-23

采纳的回答： Surya

在 MATLAB Online 中打开

Hi!

I'm trying to communicate with an external server from MATLAB using tcpclient.

To test the connection, the server can be quarried with a ping sending a message in the format '{ "Ping" : 1 }', the response is '{ "Pong" : 1 }'.

Using wireshark, a correct sequence for the ping procedure is:

i.e. the server expects a tcp packet with the FIN flag enabled indicating "end of message" .

Using python the behavior can be replicated using the socket library

import socket
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.connect(('localhost', 8333))
s.sendall('{ "Ping" : 1 }'.encode())
s.shutdown(1)
data = s.recv(15)
print ('Received', data.decode())

Using Matlab and tcpclient I'm not able to get this behavior with the FIN packets, indicating end of message.

I've tried

client = tcpclient("0.0.0.0",8333,'Timeout',1)
configureTerminator(client,"CR")
data='{ "Ping" : 1 }'
writeline(client,data)
response=readline(client)
fclose(client);
delete(client)

but the server only response after getting a [FIN] packet, which only occurs with "delete(client)", which means I cannot handle the response as I've just deleted the client.

My question is if there's a way to sending a [FIN] packet without deleting the object handling the communication using tcpclient and Matlab?

Kind regards

/Marcus

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Answer 1

Surya 2023-3-20

0
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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1914430-tcpclient-send-fin-ack#answer_1196455

在 MATLAB Online 中打开

Hi,

You can make use to Python MATLAB interface to resolve the issue.

Here is the sample code,

s = py.socket.socket(py.socket.AF_INET, py.socket.SOCK_STREAM)
s.connect({'localhost', int32(8333)});
req = py.str('{ "Ping" : 1 }').encode()
s.sendall(req);
s.shutdown(1);
data = s.recv(15)