Echo Server Code updated

ChatClient/README.md

@@ -17,7 +17,7 @@ In the **Buggs** directory you can find starting code for our simple Whatsapp cl
  - The **main.py** file, is the Entry Point.  I dont really expect you to modify this.
    HOWEVER,  you can change the logging level to remove debugging messages
  - The **network** file contains the base networking code.  You can Ignore this.
- - The **driver.py** file is what you need to edit.
+ - The twho **<whatever>Driver.py** file is what you need to edit.
 
 ### Driver Code
 
@@ -131,7 +131,174 @@ Capture the traffic again and see if you can identify the messages.
     We can filter this using the filter ```tcp.port == 4242```
 
 
-## 
+## Part 2:  Changing the Behaviour of the Client
+
+Before we get adding encryption lets look at changing the behaviour of the chat
+The two *driver* files contain the logic for sending and recieving data.
+
+
+### Changing the Send Logic.
+
+To change what the Client sends we can need to modify the *sendMessage* function in *clientDriver*
+
+
+```python
+def sendMessage(self, message):
+    """Helper Function to send a message
+    This is what we need to modify to send a message
+    """        
+    self.sock.sendall(message.encode())
+```
+
+Lets change the Code to Prefix Everything with "MESSAGE"
+
+!!! note "Keeping the Code Sane"
+
+    We could do this in-place, but to keep the code sane we are going to create a
+    a new funciton to modify the data.
+
+    This means we can just change the function,  rahter than have to fix the
+    send message code each time we make a modifiaction
+
+
+```python
+def modifyData(self, message):
+    procMessage = "MESSAGE: {0}".format(message)
+    return procMessage
+
+def sendMessage(self, message):
+    """Helper Function to send a message
+    This is what we need to modify to send a message
+    """
+
+    procMesage = modifyData(message)
+    self.sock.sendall(procMessage.encode())
+```
+
+
+!!! task "Change the Send Code"
+
+    Lets pretend we are sending a password
+    Change the modifyData function to hash the input and send it
+
+### Changing the Server Functionality
+
+We can also modify the **procesData()** function in **serverDriver**, to change the behaviour
+when we receive data.
+
+For example.  We could print an all uppercase version of the Input using the code below
+
+```
+    def processData(self, data):
+        """
+        And process the data 
+
+        Add our Logic Here
+        """
+        self.log.debug("Message {0}".format(data))
+	self.log.debug("Uppercase {0}".format(data.upper())
+```
+
+
+!!! task "Change the Receive Code"
+
+    Lets continue the password task.
+    
+    Change the receive code to take the hash that you have sent
+    in the task above.  And check it against a known hash (ie the correct password)
+    Print a message if the login is successful
+
+
+### Getting the Server to return Data.
+
+!!! note
+
+    The output may  be a bit confusing when you are running locally, as you are sending
+    a message back to yourself (thus everything is in one window)
+
+    Rememebr you can also send to anopther machine
+
+
+
+Finally lets get the server to send a message back to the client.  I am going to Echo back the message in uppercase
+We need to do two things here.
+
+
+#### 1.  Tell the client to expect data to come back
+
+After our send call we can do another recv() to tell the client to expect data from the server
+
+```
+    def sendMessage(self, message):
+        """Helper Function to send a message
+
+        This is what we need to modify to send a message
+        """
+
+        self.sock.sendall(procMessage.encode())
+
+        #And Expect a response
+        data = self.sock.recv(1024)
+        print("RESONSE FROM SERVER {0}".format(data))
+```
+
+#### 2. Tell the Server to send something
+
+The server can use the  ```self.request.sendall()``` function to send data back.
+
+```
+    def processData(self, data):
+        """
+        And process the data 
+
+        Add our Logic Here
+        """
+        self.log.debug("Message {0}".format(data))
+
+        #Send something back
+        self.request.sendall(data.upper())
+```
+
+
+You can see that the server will now send the data back in upper case
+
+```
+$ python main.py 
+WARNING:root:YOU ARE NOT EXPECTED TO IMPORT THIS CODE
+WARNING:root:Run as $python main.py
+You need to specify an address to connect to
+for example:
+  - 127.0.0.1 (for your machine)
+  - 10.0.2.15 (for someone elses machine)
+>127.0.0.1
+DEBUG:MAIN:Creating Server
+DEBUG:CLIENT:Initialise Client
+>DEBUG:SERVER:Connection from ('127.0.0.1', 52314)
+Foo
+DEBUG:SERVER:Message b'Foo'
+RESONSE FROM SERVER b'FOO'
+>Bar
+DEBUG:SERVER:Message b'Bar'
+RESONSE FROM SERVER b'BAR'
+>
+
+```
+
+!!! task "Login Client"
+
+    Modify the hash sending and checking code you developed eariler
+    to simulate a login process.
+
+    Get the server to send a message back to the client if login was
+    successfull
+
+
+
+
+    
+
+
+