Member Avatar for Minko

Hello,

I am getting an error on this line:

ReceivedData = NetStream.Read(CryptData, 0, Size)

This is the information it gives me:

A first chance exception of type 'System.ArgumentOutOfRangeException' occurred in System.dll

Additional information: Specified argument was out of the range of valid values.

If you could help me understand why this is happening I would be very grateful, if you need more code or information just say.

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Dani AI

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A brief, practical explanation and some concrete checks to avoid this happening again.

An ArgumentOutOfRangeException from a Stream.Read call means one or more of the method parameters were outside the allowed range. is right that a negative Size will trigger it, but other common causes are: the buffer is Nothing, the offset is negative, the count is negative, or offset+count > buffer.Length. Validate those values before calling Read so the exception never occurs from bad inputs.

Quick guard you can run before any read (VB.NET):

If buffer Is Nothing Then Throw New ArgumentNullException(NameOf(buffer))
If offset < 0 OrElse count < 0 OrElse offset + count > buffer.Length Then
    Throw New ArgumentOutOfRangeException("offset/count/buffer")
End If

If Size is obtained from a protocol header, parse and validate it immediately: check endianness, use unsigned when appropriate, and enforce a sane upper limit (for example a configurable MAX_MESSAGE_SIZE) before allocating or attempting to read that many bytes. Also remember NetworkStream.Read may return fewer bytes than requested — loop until you have the full payload or until Read returns 0 (remote closed).

A robust “read exactly N bytes” pattern:

Private Function ReadExact(stream As NetworkStream, buffer As Byte(), offset As Integer, count As Integer) As Integer
    Dim total As Integer = 0
    While total < count
        Dim n As Integer = stream.Read(buffer, offset + total, count - total)
        If n = 0 Then Throw New IOException("Remote closed during read")
        total += n
    End While
    Return total
End Function

Troubleshooting tips: log the values of Size, buffer.Length and offset right before the read, set a breakpoint to inspect them, and add try/catch logging for IOException/SocketException. That combination of validation, bounds checks, and a ReadExact loop will prevent the ArgumentOutOfRangeException and handle partial reads safely. — if you fixed it, it was most likely one of these causes (negative or mis-parsed length, or a buffer-size mismatch).

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Member Avatar for tinstaafl

That exception would occur if Size is negative.

Member Avatar for Minko

Hello,

I can really not figure this problem out, if I sent you the source would you be able to take a look at it for me?

Member Avatar for Minko

At the moment I seemed to have solved the problem thank you for helping.

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