30 Project: Using Select

In this project we’re going to write a server that uses select() to handle multiple simultaneous connections.

The client is already provided. You fill in the server.

30.1 Demo Code

Grab this ZIP file¹⁵ with all the input files.

The select_client.py file is already complete.

You have to fill in the select_server.py file to get it going.

30.2 Features to Add

Your server should do the following:

• When a client connects, the server prints out the client connection info in this form (it’s the client IP and port number in front):

  ('127.0.0.1', 61457): connected

• When a client disconnects, the server prints out the late client’s connection info in this form:

  ('127.0.0.1', 61457): disconnected

  Hint: You can use the .getpeername() method on a socket to get the address of the remote side even after it has disconnected. It’ll come back as a tuple containing ("host", port), just like what you pass to connect().

• When a client sends data, the server should print out the length of the data as well as the raw bytestring object received:

  ('127.0.0.1', 61457) 22 bytes: b'test1: xajrxttphhlwmjf'

30.3 Example Run

Running the server:

python select_server.py 3490

Running the clients:

python select_client.py alice localhost 3490
python select_client.py bob localhost 3490
python select_client.py chris localhost 3490

The first argument to the client can be any string–the server prints it out with the data to help you identify which client it came from.

Example output:

waiting for connections
('127.0.0.1', 61457): connected
('127.0.0.1', 61457) 22 bytes: b'test1: xajrxttphhlwmjf'
('127.0.0.1', 61457) 22 bytes: b'test1: geqtgopbayogenz'
('127.0.0.1', 61457) 23 bytes: b'test1: jquijcatyhvfpydn'
('127.0.0.1', 61457) 23 bytes: b'test1: qbavdzfihualuxzu'
('127.0.0.1', 61457) 24 bytes: b'test1: dyqmzawthxjpkgpcg'
('127.0.0.1', 61457) 23 bytes: b'test1: mhxebjpmsmjsycmj'
('127.0.0.1', 61458): connected
('127.0.0.1', 61458) 23 bytes: b'test2: bejnrwxftgzcgdyg'
('127.0.0.1', 61457) 24 bytes: b'test1: ptcavvhroihmgdfyw'
('127.0.0.1', 61458) 24 bytes: b'test2: qrumcrmqxauwtcuaj'
('127.0.0.1', 61457) 26 bytes: b'test1: tzoitpusjaxljkfxfvw'
('127.0.0.1', 61457) 17 bytes: b'test1: mtcwokwquc'
('127.0.0.1', 61458) 18 bytes: b'test2: whvqnzgtaem'
('127.0.0.1', 61457): disconnected
('127.0.0.1', 61458) 21 bytes: b'test2: raqlvexhimxfgl'
('127.0.0.1', 61458): disconnected