What is this?

This is an Image sharing system based on a low level implmentation of UDP protocol that handles fragmentation and fault tollerance.

Archticture

The project is Object Oriented through these classes:

• Message: class that represents the message entity that is used in message passing in the communication
• UDPSocket: the lowest level of the system that handles communcation on the UDP protocol level and that does fragmentation of messages. as a blackbox, it is a socket that sends a message passed to it and receives a message in the received messages queue.
• Peer: a higher level that represents the communicating entity which is the peer. it handles the RPC implmentation for the peer's operations.
• directoryServer: which represents another communicating entity that handles the directoryServer's operation.
• Image: represents the Image that is to be used on the system. it handles the steganogrophy of images, access management, formulation of all files related to the image.

How to use

UDPSocket

• initializing socket:

  UDPSocket sock;
  sock.initializeSocket({PORT_NUMBER});

  replace {PORT_NUMBER} with an int representing the port number
• sending message

  Message *msg = new Message();
  //initialize msg and fill it
  if(sock.sendMessage(msg)){
      //message added to the send queue successfully
      cout<<"Yaay";
  }

• receiving message

  Message *msg = sock.receiveMsg();//blocks until a message is ready to be received

• get socket info

  string ip = sock.getMyIP();
  int port = sock.getMyPort();

Image

for using this class you need to know which actor are you:

• creator of a new image
• owner of an existing image(using it for editing)
• viewer of an image that is not owner by you

I am going to define code snippets for all test cases that may be required

• Creator

  Image image;//create an object
  //you have to set the username and imageId in the beginning because it is needed for naming schemes
  image.setownerUsername("user1");//required in order
  image.setImageId("image123");//required in order
  //you supply the object with the path of the image
  image.chooseImage(string(IMAGE_DIR)+"small.jpg");//required in order
  struct userProperty prop;//this struct represent the setting for each user for the image
  prop.user_name="osama";
  prop.views=5;
  //access the properties of the image and edit as much as you want
  image.properties.push_back(prop);
  //write the properties to the properties file
  image.writeProperties();//required in order
  //steganize the image
  image.steg();//required in order
  //whenever you need to remove all other files except the steganized image file, call removeMiddleFiles
  image.removeMiddleFiles();

• Owner

  Image image;
  //check if the image exists
  //findImage takes the username and imageId that are used for searching in the ImageDir
  if(!image.findImage("user1","image123"))
      //no Image Found

• viewer

  string imagestr;//string that holds the image
  Image image;
  //check if the image exists
  //writeImage takes the string of the image and the owner(not the user's) username and imageId that are used for searching in the ImageDir
  image.writeImage(imagestr,"user1","image123");

• Common Operations

  1 read and edit properties

  // readTheProperties and fill the propertiesVector
  image.readProperties();
  for(int i = 0;i<image.properties.size();i++)
  {
      if(image.properties[i].user_name=="osama"&&image.properties[i].views>0)
          image.properties[i].views+=10;
  }
  //updates the properties file but does not steganize
  image.updateProperties(); 

  2 get Image Paths

  string path1 = image.getAuthorizedImagePath();
  string path2 = image.getUnAuthorizedImagePath();

  3 remove middle files

  image.removeMiddleFiles();

  4 steganize && desteganize

  image.steg();
  image.desteg();

  5 get stegImage in a string for sharing

  string imageExtract = image.extractImage();

  6 get the actual image's thumbnail in a string

  image.desteg();//required in order
  string image64Extract = image.getSmallScaleImage();

  it is base64_enoded twice so you need to decode it twice before writing to a file

Peer

• Initialization

  Peer peer(1);//port number
  peer.setDS("127.0.0.1",50);//the directoryService IP and port

• Powering the Status update thread

  peer.startStatusUpdates("QisuAsSDAWeq126UhJS");//the token retreived after authentication

• Sample Functions

  string token = peer.login("osama","123");//the username and password
  if(token=="not a user")
      cout<<"wrong username or password"<<endl;
  
  string token = peer.signup("osama","123");//the username and password
  if(token=="user already exists")
      cout<<"used username"<<endl;
  
  peer.addImageLocally("image123");//imageid
  peer.removeImageLocally("image123");
  
  string response = getAllImagesFromPeer("myUsername","theTargetPeerUsername","127.0.0.1",23);//the ip and port of the other peer
  if(response=="no photos")
      cout<<"no photos with that peer";
  else{
      vector<string> args;
      split(response,args,',');//you can copy the split function from the Peer.cpp class
      args[0];//the first encoded image received from the other peer
  }

directoryServer

Initialization in main

    directoryServer ds(1);//directory server's port number
    while(1);//keeps the ds running

login

remotley called by a peer. the DS validates the peer's credentials, returning a positive (token) or negative("not a user") reply based on the credentials sent. The permanent file containing the status of all users is updated.

logout

remotley called by a peer. The DS logs the user with the token sent, updating the permanent file. Replys with either "ok" or "not a user".

signup

Remotley called by a peer. Username is checked for duplication, reply is either "username already exists" or a new user is added and a token reply is sent back.

uploadImage

remotley called by a peer. Uploads a sample image and it's name. User is identified by a token. If successful, "ok" is the reply sent back.

getPortnIP

Remotley called by a peer. The desired username is looked up, sending back the port and ip of the peer, allowing peers to communicate directly. If username does not exist "not a user" is the reply sent back.

getAllImages

Remotley called by a peer. Returns all the images, imagenames, and their corresponding usernames to the peer.

updateStatus

Processes the status of the peer. If a peer does not send a status update for "TIMEOUT" seconds, they are considered offline, updating the permaenent file.