CSE 333 25au Exercise 15

out: Monday, November 10, 2025
due: Friday, November 14, 2025 by 10:00 am. No late exercises accepted.

Goals: Create a program that uses TCP sockets to connect to a server and exchange data with it.

Description: Write a C++ program that accepts three command line arguments:

• the hostname of a server
• the port number of that server
• the name of a local file

The program should connect (via TCP) to the server on the supplied hostname and port. Once connected, the program should read the bytes from the local file, and it should write those bytes over the TCP connection. Once all of the bytes have been written, the program should close the TCP connection and exit.

To test your program, you can run a server using the nc program. For example, to run the server on port 5555, and to have the server redirect the incoming bytes to file output.bytes, run the following command:

nc -l 5555 > output.bytes

Note that nc will exit once it has processed a single connection, so you'll need to rerun nc each time you test your client.

If you are running nc on the same computer/host where you are running your ex15 code, you can use the special loop-back IP address 127.0.0.1 to refer to the same local host. Please note that each attu (e.g. attu1, attu2, etc.) is a separate machine with its own IP addresses, so if you are running on attu you can only reliably use 127.0.0.1 if both client and server are running on the same actual machine.

There are a few requirements on your code:

• you should modularize it nicely; consider splitting it into multiple source files if that makes sense, for example by isolating all of the network-specific code in a module.
• you should use read and write both to read from the input file and write over the socket to the server; note this means you need to pay attention to the possibility that read/write might return EINTR or EAGAIN, and they might read/write less than you ask for. We recommend writing some utility functions to deal with this.
• write a Makefile so that we can compile your code by typing make. Your Makefile should produce an executable binary called ex15 and should only recompile and relink files that need to be rebuilt to bring the program up to date.

Feel free to adapt sample code from lecture and section as part of your solution if it helps (it probably will), but be sure you understand what your code does when you're done.

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In addition, your code must:

• compile without errors or warnings on CSE Linux machines (lab workstations, attu, or CSE home VM)
• have no crashes, memory leaks, or memory errors on CSE linux machines
• have a Makefile as described above that compiles the code with the g++ options -Wall -g -std=c++17
• be pretty: the formatting, modularization, variable and function names, use of const and so on must make us smile rather than cry. (Hints: Google C++ Style Guide and cpplint)
• be robust: you should think about handling bogus input from the user (if any), and you should handle hard-to-handle cases (if there are any) gracefully.
• have a comment at the top of each source file with your name, and CSE or UW email address.

You should submit your exercise using the Gradescope dropbox linked on the course resources web page.