Client

- Added `CryptClient` which is a kind-of `Stream` (from the `river` library)
- Constructor takes in an underlying connection, potentially a socket, but some `RiverStream` that can be used for the Botan client to communicate with
- Added `openCheck()` to be called prior to any code inside the `write`, `writeFully`, `read` and `readFully` methods which calls the `botanClient.isActive()`, if this is false (i.e. the TLS session is not active) then an exception (a `StreamException`) is thrown

source/cryptstream/streams/client.d

@@ -1,3 +1,89 @@
 module cryptstream.streams.client;
 
-import botan.tls.client;
+import botan.tls.client;
+
+import river.core : RiverStream = Stream, StreamException, StreamError;
+
+// TODO: This should be a kind-of `RiverStream`, but
+// ... we defs can take IN a stream to use as the underlying
+// ... connection upon which the TLS data will be sent over
+public class CryptClient : RiverStream
+{
+    /**
+     * Underlying stream to use for TLS-encrypted communication
+     */
+    private RiverStream stream;
+    
+    /** 
+     * Botan TLS client
+     */
+    private TLSClient botanClient;
+
+    /** 
+     * Constructs a new TLS-enabled client stream
+     * Params:
+     *   stream = 
+     */
+    this(RiverStream stream)
+    {
+        this.stream = stream;
+
+        this.botanClient = new TLSClient(&tlsOutputHandler);
+
+        // TODO: Insert code to init using botan OVER `stream`
+    }
+
+    private void tlsOutputHandler(in ubyte[] dataOut)
+    {
+
+    }
+
+    
+    public override ulong read(byte[] toArray)
+    {
+        // TODO: Implement me
+        return 0;
+    }
+
+    public override ulong readFully(byte[] toArray)
+    {
+        // TODO: Implement me
+        return 0;
+    }
+
+    public override ulong write(byte[] fromArray)
+    {
+        /* Ensure the TLS session is active */
+        openCheck();
+        
+        // TODO: Implement me
+
+        // botanClient.send()
+
+        return 0;
+    }
+
+    
+    public override ulong writeFully(byte[] fromArray)
+    {
+        // TODO: Implement me
+        return 0;
+    }
+
+    public override void close()
+    {
+        // TODO: Implement me
+    }
+
+    /** 
+     * Ensures that the TLS client is active is open, if not, then throws an
+     * exception
+     */
+    private void openCheck()
+    {
+        if(!botanClient.isActive())
+        {
+            throw new StreamException(StreamError.CLOSED);
+        }
+    }
+}