bformat/source/bformat/sockets.d

/** 
 * Socket encoding/decoding functions
 */
module bformat.sockets;

import std.socket : Socket, SocketFlags, MSG_WAITALL;

public class BClient
{
	/** 
	 * Underlying socket
	 */
	private Socket socket;

	// TODO: comment
	this(Socket socket)
	{
		this.socket = socket;
	}

	/** 
	 * Receives a message from the provided socket
	 * by decoding the streamed bytes into bformat
	 * and finally placing the resulting payload in
	 * the provided array
	 *
	 * Params:
	 *   originator = the socket to receive from
	 *   receiveMessage = the nbuffer to receive into
	 *
	 * Returns: true if the receive succeeded, false otheriwse
	 */
	public bool receiveMessage(ref byte[] receiveMessage)
	{
		/* Construct a buffer to receive into */
		byte[] receiveBuffer;

		bool status = true;


		/* The amount of bytes received */
		long bytesReceived;

		/* Get the length of the message */
		byte[4] messageLengthBytes;
		bytesReceived = socket.receive(messageLengthBytes, cast(SocketFlags)MSG_WAITALL);

		/* If there was an error reading from the socket */
		if(!(bytesReceived > 0))
		{
			status =  false;
		}
		/* If the receive was successful */
		else
		{
			/* Response message length */
			uint messageLength;

			/* Little endian version you simply read if off the bone (it's already in the correct order) */
			version(LittleEndian)
			{
				messageLength = *cast(int*)messageLengthBytes.ptr;
			}

			/* Big endian requires we byte-sapped the little-endian encoded number */
			version(BigEndian)
			{
				byte[] swappedLength;
				swappedLength.length = 4;

				swappedLength[0] = messageLengthBytes[3];
				swappedLength[1] = messageLengthBytes[2];
				swappedLength[2] = messageLengthBytes[1];
				swappedLength[3] = messageLengthBytes[0];

				messageLength = *cast(int*)swappedLength.ptr;
			}


			/* Read the full message */
			receiveBuffer.length = messageLength;
			bytesReceived = socket.receive(receiveBuffer, cast(SocketFlags)MSG_WAITALL);

			/* If there was an error reading from the socket */
			if(!(bytesReceived > 0))
			{
				status = false;
			}
			/* If there was no error receiving the message */
			else
			{
				receiveMessage = receiveBuffer;
			}
		}

		return status;
	}

	/** 
	 * Encodes the provided message into the bformat format
	 * and sends it over the provided socket
	 *
	 * Params:
	 *   recipient = the socket to send over
	 *   message = the message to encode and send
	 *
	 * Returns: true if the send succeeded, false otherwise
	 */
	public bool sendMessage(byte[] message)
	{
		/* The message buffer */
		byte[] messageBuffer;

		/* Encode the 4 byte message length header (little endian) */
		int payloadLength = cast(int)message.length;
		byte* lengthBytes = cast(byte*)&payloadLength;

		/* On little endian simply get the bytes as is (it would be encoded as little endian) */
		version(LittleEndian)
		{
			messageBuffer ~= *(lengthBytes+0);
			messageBuffer ~= *(lengthBytes+1);
			messageBuffer ~= *(lengthBytes+2);
			messageBuffer ~= *(lengthBytes+3);
		}

		/* On Big Endian you must swap the big-endian-encoded number to be in little endian ordering */
		version(BigEndian)
		{
			messageBuffer ~= *(lengthBytes+3);
			messageBuffer ~= *(lengthBytes+2);
			messageBuffer ~= *(lengthBytes+1);
			messageBuffer ~= *(lengthBytes+0);
		}
		

		/* Add the message to the buffer */
		messageBuffer ~= cast(byte[])message;

		/* Send the message */
		long bytesSent = socket.send(messageBuffer);

		/* TODO: Compact this */
		return bytesSent > 0;
	}

}