Developed for Advanced C Programming (CS 591) in Fall 2017, each lab represents a step towards the "ultimate" client-server.
The functionality revolves around creating an ssh client-server which sets bash up for a connecting client on the server. However, this can easily be swapped for any other function; such as a web server (nginx). The labs crescendo into a much more sophisticated implementation using epoll and a thread pool to handle all processing. It also handles DDOS attacks and malicious clients.
Additionally, each folder has a makefile which can be used to make each client and server. More details for each particular implementation can be found in the particular folder:
The code was written with Linux in mind and doesn't necessarily conform to POSIX standards. Verify code before reuse.
| Feature | Lab 1 | Lab 2 | Lab 3 | Lab 4 (ThrPool) | Lab 5 |
|---|---|---|---|---|---|
| Processes Created* | 1 | 3 | 1 | - | 1 |
| Threads Created | 0 | 0 | 2 | - | 8 (Num_Cores) |
| Concurrent Server | YES | YES | YES | - | YES |
| Three-way Handshake | YES | YES | YES | - | YES |
| IO Type | Blocking | Blocking | Blocking | - | Non-blocking |
| Debug Mode | NO | YES | YES | YES | YES |
| Signal Handler | NO | YES | YES | NO | YES |
| Handles Malicious Clients | NO | NO | YES** | - | YES |
| Handles Partial Writes | NO | NO | NO | - | YES |
| Thread Pool | NO | NO | NO | YES | YES |
| Epoll | NO | NO | YES | - | YES |
*It is important to note that there will be at least 1 process created for bash.
**Lab 3 handles malicious clients by using timers whereas Lab5 uses timerfd with its own epoll unit.
First start by running the server:
./server
Then connect a client (or more) using the server IP:
./client 127.0.0.1
The following scripts can be used to test or debug the server:
- Broken Clients Test
- Concurrent Clients Test
- Flood Server Test
- Flood Server Hybrid Test
- Pwrite
- Show Server
- Show Clients
- Show Sockets
- All Broken Clients
I plan on implementing a logger to record and report what happens during server runtime such as:
- Server creation
- Client connection
- Client destruction
- Client errors
- Server errors