bformat/source/bformat/sockets.d

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

import std.socket : Socket, SocketFlags, MSG_WAITALL;

/** 
 * 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(Socket originator, 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 = originator.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 = originator.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(Socket recipient, 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 = recipient.send(messageBuffer);

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