About this article
This article was created using an automated generation workflow powered by generative AI. It reviews RFC 9293 and the .NET Socket API, organizing the concept of attaching length information to a TCP byte stream into an observable format on localhost.Verification status: 📘 RFC and .NET official specifications checked, actual hardware not verified
TCP does not have application message boundaries. Therefore, we will experience a length prefix—where "how many bytes come next" is placed before the body—using minimal data.
Try it first
$msg='HELLO' $body=[Text.Encoding]::UTF8.GetBytes($msg) $prefix=[BitConverter]::GetBytes([Net.IPAddress]::HostToNetworkOrder($body.Length)) "prefix=$([BitConverter]::ToString($prefix)) body=$msg" $len=[Net.IPAddress]::NetworkToHostOrder([BitConverter]::ToInt32($prefix,0)) "receiver expects $len bytes"
Look here
Before reading the body, the receiving side can know5 bytes.SendorReadThe key point is that the application itself defines the boundaries, rather than the number of times
Change one part
HELLOtoこんにちはand verify that the UTF-8byte count, rather than the character count, becomes the prefix.
Why this happens
TCP guarantees an ordered byte stream. Framing mechanisms such as fixed lengths, delimiters, or length prefixes are the responsibility of the upper layer protocol.
graph LR L[4-byte length] --> B[payload bytes] B --> R[receiver reads exactly length]
If used in production
In implementations, you must also consider cases where the prefix itself is received in fragments, requiring logic to "read until 4 bytes are accumulated" and "read until the declared length is accumulated." Also, set an upper limit rather than unconditionally allocating huge declared lengths.
RFC 9293: https://www.rfc-editor.org/rfc/rfc9293
Microsoft NetworkStream.Read: https://learn.microsoft.com/dotnet/api/system.net.sockets.networkstream.read
