Centralized Peer-to-Peer File Sharing Architecture

Contents

• Working
• Requirements
• Installation Process
• Compilation
• Execution
• Bugs
• Finalization

The aim of this project is to provide a file sharing system, among the peers connected to the network, administered by a centralized server.

Working

Commands supported:

Command syntax	Function	Example	Parameters
-sys COMMAND	Executes the COMMAND as a CLI	-sys ls	None
-s OPTION	Message intended for server	-s exit	exit -> closes the connection with server. upload -> Uploads a file to the server. ls -> Requests the files list from the server. download -> Requests to download a file from the server.

• A client first joins the network by registering a username and password with the server, or by loging in if it's already registered.

• The client can upload a file to the server, using the command -s upload, and then specifying the local path of the file.

• The server then splits the file based on a fixed block size, and uploads these blocks to clients connected to the network. The location of each block is recorded.

• The client can request for a file from the server using the command -s download, specifying the name of the file. The server then sends the block locations of the file to the requesting client.

• The client then downloads all the blocks from it's respective locations. It then merges these blocks, to retrieve the file.

Requirements

• Linux based Operating System.

Installation Process

• Download the server.c and client.c files.

Server side

• Installing MySQL

  • Execute the following commands on Ubuntu:
    sudo apt-get update
sudo apt-get install mysql-server

• Create a new database 'p2p' and add thefour tables to it, namely:

  • login_details

  CREATE TABLE login_details(log_id INT PRIMARY KEY, user_name TEXT, password TEXT, isOnline TINYINT(1));
  

  Field	Type	Null	Key	Default	Extra
  log_id	int	NO	PRI	NULL
  user_name	text	YES		NULL
  password	text	YES		NULL
  isOnline	tinyint(1)	YES		NULL

  • online_clients

  CREATE TABLE online_clients(p_id INT PRIMARY KEY, IP TEXT NOT NULL, port INT NOT NULL,
  log_id INT NOT NULL, FOREIGN KEY (log_id) REFERENCES login_details(log_id));
  

  Field	Type	Null	Key	Default	Extra
  p_id	int	NO	PRI	NULL
  IP	text	NO		NULL
  port	int	NO		NULL
  log_id	int	NO	MUL	NULL

  • files

  CREATE TABLE files(f_id INT PRIMARY KEY, filename TEXT NOT NULL, p_id INT);
  

  Field	Type	Null	Key	Default	Extra
  f_id	int	NO	PRI	NULL
  filename	text	NO		NULL
  p_id	int	NO		NULL

  • blocks

  CREATE TABLE blocks(blockname TEXT NOT NULL, dst_IP TEXT NOT NULL, dst_port INT NOT NULL,
  f_id INT NOT NULL, FOREIGN KEY (f_id) REFERENCES files(f_id));
  

  Field	Type	Null	Key	Default	Extra
  blockname	text	NO		NULL
  dst_IP	text	NO		NULL
  dst_port	int	NO		NULL
  f_id	int	NO	MUL	NULL

• Create a new user and grant all privileges to it.

Compilation

• Compile the server side code using the following command :
  

   gcc server.c -o server.out `mysql_config --cflags --libs`

• Compile the client side code using the following command :
  

   gcc client.c -o client.out 

Execution

• First start the server side program using ./server.out and provide the following details:
  

  • Server Port Number
  • User id and password of the MySQL client

• Start the client side program using ./client.out and provide the following details:
  

  • Server IP address and port number
  • UDP socket port number

• Once connection with server is established, choose whether the client is a new user or not.

• The client enters it's user name and password, which is registered/auhtenticated by the server.

BUGS

• The number of blocks created should depend on a fixed block size, and not on the number of users online (as is the case now.)
• The occasional file transfer errors that occur needs to be fixed.
• Maybe using file descriptors was not the right choice after all. Maybe threading is better?

Finalization

• Remove the clear table commands that is executed, everytime the server starts.
• Adding the GUI looks close to impossible. Quite the unexpected. It wants me to conver this while thing to a library!
• Add compression: Looking into arithmetic encoding.
• Add encryption.