SPAaSM Assignment 2. Remote shell

Author: Oles Andrela

AIS ID: 136166

Seminar: Wed, 18:00

Tutor: J. Mikulec

Task

To implement a simple program that provides a remote shell functionality as a client and a server.

Allowed languages:

• C 23
• C++ 23
• NASM x64

Minimal provided functionality

• help command - write the following information;

  • Author info;
  • What the programm is that;
  • How to use;
  • Available commands.

• quit command - close the connection sent this command;

• halt command - close all connections and stop the entire program;

• -p flag - select a port;

• -h flag - write help information and quit;

• -s flag - use server behavior;

• -c flag - use client behavior;

• Start with no -s or -c arguments - similar to one with -s;

• Predefined prompt for client and server: <username>@<hostname><prompt_end_symbol>, where <username> and <hostname> are got by library functions or system calls;

• Validity checks, starting incoming scripts, redirecting using system calls;

• Usage of popen() and similar functions for executing shell scripts is prohibited;

• Connections established via sockets;

• Multiple active connections via the same port;

• No compiler warnings;

# Server start
remshell -s -p <port>
remshell -p <port>

# Client start
remshell -c -p <port>

Bonus tasks

3. stat command - list all active connections; (3 points)

user@host#stat
0. 147.145.0.2:2345
1. 147.145.0.2:2346
2. 147.145.3.5:3333

6. <username> and <hostname> using inline ASM; (3 points)

7. Makefile;

8. English documentation;

Command execution

Commands should be executed directly (without initiating a shell process). To do this, we can fork the current process, and exec the requested program (each command is a program contained in directories included in $PATH). For parsing the operator syntax, idea of automates can be used.