README and code base best viewed on Github

This is an assignment for my Operating Systems class CSCI 3120

This program uses threads and a mailbox system to authenticate users read in from a file, allow them to run services read in from another file and return the result of a service call to the main client thread.

This program only has two threads working fully with each other. That is the client thread and the authentication thread. The program allows creates a client thread which allows the user to input a username and password. It then sends this to the authentication thread through the mailbox system which then checks agaisnt a list of read in usernames and passwords to see if it should authenticate. If it authenticates, the thread sends a message back to the client thread with the authentication string.

This program requires gcc and make to compile.

This program is made to run on the bluenose.cs.dal.ca servers but should work on most linux distros.

1. Copy files into working directory.
2. run make command in terminal
3. run ./main authFile.txt serviceFile.txt You can give the program different file arguments than above, but check below in the configuration section for the format of each file

1. You will be prompted for a username(mike) and password(bobby) or enter any user:pass found in the authFile.txt.
2. This will send a message to the authentication thread which will verify the user and password was correct
3. You will receive an authentication string back to the client thread that includes the secret ticket value (apple)
4. If you enter incorrect credentials, you will receive a string in the form 0:username:password:0
5. The program will then exit

Edit the authFile.txt or make your own, then put usernames and passwords on each line in the form username:password

Edit the serviceFile.txt or make your own, then put service names(add, sub, mult), secret values, and a list of users that can use that service in the form service:secret:user1,user2,user3...userN

Linked list structure with methods for adding, removing, and getting nodes from a list.

This is a mailbox system to send messages between threads safely.

This handles the different threads, creates them, and handles the authentication and message sending for the program.

List_t *readInServiceFile(char *filename);

- Reads in a service file of the format `service:secret:user1,user2,user3...userN` on each line
It splits each part into a struct, then stores this in a list for each line, then returns the list.

List_t *readInUsersFromFile(char *filename);

- Reads in a authentication file of the format `username:password` on each line
It stores each line in a struct, then stores this in a list for each line, then returns the list.

void *authThread(void *auth);

- The auth thread waits for a user name and pass to get sent to it from the client thread
which it will then authenticate. It will return a valid authentication string or invalid
if the user is authenticated or not. It authenticates based on the list of usernames:passwords from
the authentication file read in at the start. It returns NULL. This thread receives and sends messages to the
client thread.

void *clientThread();

- The client thread reads in a username and password and then tries to authenticate with the
authentication thread. If it receives a proper message back it should allow the user to
run a service name with two arguments (which is not implemented). It returns NULL. This thread sends and receives
messages from the authentication thread.

void *ticketGrantingThread();

- This thread is not implemented but would wait for a message from the client thread with an authentication string, service
and a username. It would then verify that the authentication string is correct and return a valid ticket string to the user.

void *serviceThread();

- This thread is not implemented but would include support for add, sub and mult services, which would wait
for tickets from the client thread, check if the ticket is valid, perform the requested operation, then send a message
back to the client thread.

See testCases.txt for test cases done

The mailbox system was developed from the professor Mike McAllister.