TCP/IP Sockets in c# argument null while decoding

Question

I thought the most easiest thing to help with my problem would be to simply post the project here. But that isn't going to work.

So here are the parts where I think it is going wrong:

public class ItemQuoteDecoderText : ItemQuoteDecoder
{
    //Character encoding
    public Encoding encoding;

    public ItemQuoteDecoderText() : this(ItemQuoteTextConst.DEFAULT_CHAR_ENC) { }

    public ItemQuoteDecoderText(string encodingDesc)
    {
        encoding = Encoding.GetEncoding(encodingDesc);
    }

    public ItemQuote decode(Stream wire)
    {
        string itemNo, description, quant, price, flags;

        byte[] space = encoding.GetBytes(" ");
        byte[] newline = encoding.GetBytes("\n");

        itemNo = encoding.GetString(ItemQuoteFramer.nextToken(wire, space));
        description = encoding.GetString(ItemQuoteFramer.nextToken(wire, newline));
        quant = encoding.GetString(ItemQuoteFramer.nextToken(wire, newline));
        price = encoding.GetString(ItemQuoteFramer.nextToken(wire, newline));
        flags = encoding.GetString(ItemQuoteFramer.nextToken(wire, newline));

        return new ItemQuote(Int64.Parse(itemNo),
                                description,
                                Int32.Parse(quant),
                                Int32.Parse(price),
                                (flags.IndexOf('d') != -1),
                                (flags.IndexOf('s') != -1));
    }

    public ItemQuote decode(byte[] packet)
    {
        Stream payload = new MemoryStream(packet, 0, packet.Length, false);
        return decode(payload);
    }
}

At the decoder the incoming stream is decoded to form a read-able outcome. Unfortunately the error that occurs at:

price = encoding.GetString(ItemQuoteFramer.nextToken(wire, newline));

With the message:

An exception of type 'System.ArgumentNullException' occurred in mscorlib.dll but was not handled in user code

Additional information: Array cannot be null.

The ItemQuoteFramer:

    public class ItemQuoteFramer
{
    public static byte[] nextToken(Stream input, byte[] delimiter)
    {
        int nextByte;

        //If the stream has already ended, return null
        if ((nextByte = input.ReadByte()) == -1)
            return null;

        MemoryStream tokenBuffer = new MemoryStream();
        do
        {
            tokenBuffer.WriteByte((byte)nextByte);
            byte[] currentToken = tokenBuffer.ToArray();
            if (endsWith(currentToken, delimiter))
            {
                int tokenLength = currentToken.Length - delimiter.Length;
                byte[] token = new byte[tokenLength];
                Array.Copy(currentToken, 0, token, 0, tokenLength);

                return token;
            }
        }
        while ((nextByte = input.ReadByte()) != -1);

        return tokenBuffer.ToArray();
    }

    static bool endsWith(byte[] value, byte[] suffix)
    {
        if (value.Length < suffix.Length)
            return false;

        for (int offset = 1; offset <= suffix.Length; offset++)
            if (value[value.Length - offset] != suffix[suffix.Length - offset])
                return false;

        return true;
    }
}

Will skip it's delimiter after the variable "quant" in ItemQuoteDecoderText is filled. Which leaves the last part of the send packet: "1000 12999 d" as a whole in "quant" and will return null for the last two ("price" & "flags") variables.

    public class SendUdp
{
    public SendUdp(string[] args)
    {
        SendUdpMethod(args);
    }

    void SendUdpMethod(string[] args)
    {
        //Check for correct amount of arguments
        if ((args.Length < 2) || (args.Length > 3))
            throw new ArgumentException("Parameters: <Destination> <Port> [<Encoding>]");

        string server = args[0];
        int destPort = Int32.Parse(args[1]);

        //Make an item to quote
        ItemQuote quote = new ItemQuote(12345678909876554L, "5mm Super Widgets", 1000, 12999, true, false);

        UdpClient client = new UdpClient();

        ItemQuoteEncoder encoder = ((args.Length == 3) ? new ItemQuoteEncoderText(args[2]) : new ItemQuoteEncoderText());
        byte[] codedQuote = encoder.encode(quote);

        client.Send(codedQuote, codedQuote.Length, server, destPort);
        client.Close();
    }
}

This is the code that will handle how the packet will be received:

    public class ReceiveUdp
{
    public ReceiveUdp(string[] args)
    {
        ReceiveUdpMethod(args);
    }

    void ReceiveUdpMethod(string[] args)
    {
        //Check for correct amount of arguments
        if ((args.Length < 1) || (args.Length > 2))
            throw new ArgumentException("Parameters: <Port> [<Encoding>]");

        int port = Int32.Parse(args[0]);
        UdpClient client = new UdpClient(port);

        byte[] packet = new byte[ItemQuoteTextConst.MAX_WIRE_LENGTH];
        IPEndPoint remoteIPEndPoint = new IPEndPoint(IPAddress.Any, port);

        packet = client.Receive(ref remoteIPEndPoint);
        ItemQuoteDecoderText decoder = ((args.Length == 2) ? new ItemQuoteDecoderText(args[1]) : new ItemQuoteDecoderText());

        ItemQuote quote = decoder.decode(packet);
        Console.WriteLine(quote);

        client.Close();
    }
}

ItemQuoteFramer likes to skip the delimiter and I think that's where it goes wrong. But I have no idea what to do about it. Would anyone be so kind to take the time to help me figure it out?

Thank you very much,
Farcrada

Answer 1

The answer lies in the way the delimiter is given. The variable "quant" holds (at the time of the error) the following: "1000 12999 d".

If you look at which delimiter has been given through, it gives: "newline". If we change that to: "space", we fix our problem.

To clarify, the following in ItemQuoteDecoderText:

    itemNo = encoding.GetString(ItemQuoteFramer.nextToken(wire, space));
    description = encoding.GetString(ItemQuoteFramer.nextToken(wire, newline));
    quant = encoding.GetString(ItemQuoteFramer.nextToken(wire, newline));
    price = encoding.GetString(ItemQuoteFramer.nextToken(wire, newline));
    flags = encoding.GetString(ItemQuoteFramer.nextToken(wire, newline));

Should become:

    itemNo = encoding.GetString(ItemQuoteFramer.nextToken(wire, space));
    description = encoding.GetString(ItemQuoteFramer.nextToken(wire, newline));
    quant = encoding.GetString(ItemQuoteFramer.nextToken(wire, space));
    price = encoding.GetString(ItemQuoteFramer.nextToken(wire, space));
    flags = encoding.GetString(ItemQuoteFramer.nextToken(wire, newline));

I would like to thank everyone that took their time to take a look at this.

Thank you very much,
Farcrada