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

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.

• 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();

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

• 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
  }

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.