Crate vstp 

VSTP - Vishu’s Secure Transfer Protocol

A general-purpose, binary, extensible application-layer protocol designed to be:

• Secure by default on TCP (TLS 1.3)
• Fast on UDP (no TLS initially)
• Minimal but extensible with binary headers
• Easy to implement across languages

Quick Start

use vstp::easy::{VstpClient, VstpServer};
use serde::{Serialize, Deserialize};

#[derive(Serialize, Deserialize)]
struct Message {
    content: String,
}

// Start a TCP server
let server = VstpServer::bind_tcp("127.0.0.1:8080").await?;
tokio::spawn(async move {
    server.serve(|msg: Message| async move {
        println!("Received: {}", msg.content);
        Ok(msg) // Echo the message back
    }).await
});

// Connect a client
let mut client = VstpClient::connect_tcp("127.0.0.1:8080").await?;

// Send a message
let msg = Message { content: "Hello, VSTP!".to_string() };
client.send(msg).await?;

// Receive the response
let response: Message = client.receive().await?;
println!("Got response: {}", response.content);

Protocol Overview

VSTP frames have the following wire format:

• MAGIC (2B): Protocol identifier
• VER (1B): Protocol version
• TYPE (1B): Message type
• FLAGS (1B): Bit flags
• HDR_LEN (2B LE): Header section length (little-endian)
• PAY_LEN (4B BE): Payload length (big-endian)
• HEADERS: Variable-length header section
• PAYLOAD: Variable-length payload section
• CRC32: 32-bit checksum

Where:

• MAGIC: 0x56 0x54 (“VT”) to identify VSTP
• VER: Protocol version (0x01 for v1)
• TYPE: Message type (Hello, Welcome, Data, etc.)
• FLAGS: Bit flags (REQ_ACK, CRC, FRAG, COMP)
• HDR_LEN: Little-endian header section length
• PAY_LEN: Big-endian payload length
• HEADERS: Concatenated binary K/V entries
• PAYLOAD: Raw bytes (UTF-8 text, JSON, binary, etc.)
• CHECKSUM: CRC16-IBM over HEADERS|PAYLOAD (optional)

Transport Modes

• TCP mode: Reliable + encrypted (TLS 1.3 via rustls)
• UDP mode: Connectionless + fast (no TLS in v0.1)

Message Types

Type	Name	Direction	Description
0x01	HELLO	Client → Server	Start of session
0x02	WELCOME	Server → Client	Server accept
0x03	DATA	Both	Application data
0x04	PING	Both	Keepalive request
0x05	PONG	Both	Keepalive response
0x06	BYE	Both	Graceful close
0x07	ACK	Both	Acknowledgement
0x08	ERR	Both	Error frame

Re-exports

pub use types::Flags;

pub use types::Frame;

pub use types::FrameType;

pub use types::Header;

pub use types::SessionId;

pub use types::VstpError;

pub use types::VSTP_MAGIC;

pub use types::VSTP_VERSION;

pub use codec::VstpFrameCodec;

pub use frame::encode_frame;

pub use frame::try_decode_frame;

pub use tcp::VstpTcpClient;

pub use tcp::VstpTcpServer;

pub use udp::VstpUdpClient;

pub use udp::VstpUdpServer;

pub use easy::VstpClient;

pub use easy::VstpServer;

Modules

codec

easy

frame

tcp

TCP transport implementation for VSTP

types

udp

UDP transport implementation for VSTP