107 lines
2.5 KiB
D
107 lines
2.5 KiB
D
/**
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* Standalone encoding/decoding functions
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*/
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module bformat.marshall;
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/**
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* Decodes the provided bformat message into the
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* message itself
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*
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* Params:
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* bformatBytes = the bformat payload the decode
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* Returns: the decoded message
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*/
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public byte[] decodeMessage(byte[] bformatBytes)
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{
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/* Construct a buffer to receive into */
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byte[] receiveBuffer;
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/* Get the length of the message */
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byte[4] messageLengthBytes = bformatBytes[0..4];
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/* Response message length */
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uint messageLength;
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/* Little endian version you simply read if off the bone (it's already in the correct order) */
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version(LittleEndian)
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{
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messageLength = *cast(int*)messageLengthBytes.ptr;
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}
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/* Big endian requires we byte-sapped the little-endian encoded number */
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version(BigEndian)
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{
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byte[] swappedLength;
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swappedLength.length = 4;
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swappedLength[0] = messageLengthBytes[3];
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swappedLength[1] = messageLengthBytes[2];
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swappedLength[2] = messageLengthBytes[1];
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swappedLength[3] = messageLengthBytes[0];
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messageLength = *cast(int*)swappedLength.ptr;
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}
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/* Read the full message */
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receiveBuffer = bformatBytes[4..4+messageLength];
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return receiveBuffer;
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}
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/**
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* Encodes the provided message into the bformat format
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*
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* Params:
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* message = the buffer containing bytes to encode
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* Returns: the encoded payload
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*/
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public byte[] encodeBformat(byte[] message)
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{
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/* The message buffer */
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byte[] messageBuffer;
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/* Encode the 4 byte message length header (little endian) */
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int payloadLength = cast(int)message.length;
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byte* lengthBytes = cast(byte*)&payloadLength;
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/* On little endian simply get the bytes as is (it would be encoded as little endian) */
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version(LittleEndian)
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{
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messageBuffer ~= *(lengthBytes+0);
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messageBuffer ~= *(lengthBytes+1);
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messageBuffer ~= *(lengthBytes+2);
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messageBuffer ~= *(lengthBytes+3);
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}
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/* On Big Endian you must swap the big-endian-encoded number to be in little endian ordering */
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version(BigEndian)
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{
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messageBuffer ~= *(lengthBytes+3);
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messageBuffer ~= *(lengthBytes+2);
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messageBuffer ~= *(lengthBytes+1);
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messageBuffer ~= *(lengthBytes+0);
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}
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/* Add the message to the buffer */
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messageBuffer ~= cast(byte[])message;
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return messageBuffer;
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}
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version(unittest)
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{
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import std.string : cmp;
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}
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unittest
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{
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string message = "This is my message";
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byte[] bformatEncoded = encodeBformat(cast(byte[])message);
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byte[] decodedMessageBytes = decodeMessage(bformatEncoded);
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string decodedMessage = cast(string)decodedMessageBytes;
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assert(cmp(message, decodedMessage) == 0);
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} |