Web Client. Communication with REST API

Description

This project focuses on developing a C/C++ client application that interacts with a REST API. The client provides a command line interface (CLI) for users to input commands, which are then translated into requests sent to the server. The server, in this case, simulates a virtual library and exposes a REST API for various operations.

Structure

The project consists of the following files:

• client.c : Implementation of the web client
• request.c : Implementation of the request functions
• request.h : Header file for request functions
• helpers.c : Implementation of helper functions for server operations
• helpers.h : Header file for helper functions
• buffer.c : Implementation of buffer-related functions
• buffer.h : Header file for buffer-related functions

Main commands for User Input

The program reads each command in an infinite loop while opening a connection with the server. The accepted commands from the user include:

1. exit: Terminate the program.
2. register: Register a new user.
3. login: Authenticate a user.
4. logout: Disconnect the client.
5. enter_library: Gain access to the library.
6. get_books: Retrieve all books.
7. get_book: Get information about a specific book.
8. add_book: Add a book to the library.
9. delete_book: Delete a book from the library.

If an unrecognized command is entered, an error message is displayed.

register

For registration, the program reads the username and password, utilizing the get_user_infos() function, which is also used for login. A POST request message is created and sent to the server, and the following errors are handled:

• The username has already been used.
• The username contains whitespace.

In case of a successful registration, the user is notified.

login

The program reads the login credentials and parses them using the get_user_infos() function. A POST request message is created, and the following errors are handled based on the server response:

• The credentials do not match.
• The username contains whitespace.

In case of a successful login, the user is notified, and the obtained cookie is stored.

logout

Since no user input is required for logout, a POST request message is created directly. The following error is handled based on the server response:

• The user was not logged in.

In case of a successful logout, the user is notified.

enter_library

A GET request message is created to gain access to the library, and the following error is handled based on the server response:

• Unauthorized access.

In case of successful access, the user is notified, and the obtained token is stored.

get_books

A GET request message is created to retrieve the list of books, and the following error is handled based on the server response:

• Unauthorized access.

In case of a successful request, the JSON list of books is displayed.

get_book

The program obtains the book ID from the user using the get_id() function and generates a new path. A GET request message is created, and the following errors are handled based on the server response:

• Unauthorized access.
• The ID is in an invalid format or was not entered.
• The book was not found in the library.

In case of a successful request, the details about the book are displayed.

add_book

The program reads the information about the book and creates a POST request message. The following errors are handled based on the server response:

• Unauthorized access.
• Incomplete or incorrectly formatted data.

In case of a successful request, a success message is displayed.

delete_book

The program obtains the book ID from the user using the get_id() function and generates a new path. A DELETE request message is created, and the following errors are handled based on the server response:

• Unauthorized access.
• The ID is in an invalid format or was not entered.
• The book was not found in the library.

In case of a successful request, a success message is displayed.