NewMai/protobytes

Protobytes

Protobytes is a Go library inspired by Rust's crate bytes. It provides a series of methods for big-endian and little-endian number operations, as well as a helper for io.Reader.

Purpose

The goal of this library is to provide an easy-to-use bytes.Buffer. However, it has been split into BytesReader and BytesWriter, which perform similarly to using bytes.Buffer directly.

When using bytes.Buffer, binary.Write has poor performance and unnecessary allocation. Instead, you can use the methods provided by protobytes.

Usage

BytesReader and BytesWriter are similar to bytes.Buffer, but they are not thread-safe. bytes.Buffer, binary.Write and []byte conversion is very easy and cheap.

buf := make([]byte, 0, 1024)
w := BytesWriter(buf)
w.ReadFull(rand.Reader, 64)
w.PutUint8(0x01)
w.PutUint16be(0x0203)

r := BytesReader(w.Bytes())
randomBytes, r := r.SplitAt(64) // split to two BytesReader
r.ReadUint8() // auto step forward
r.ReadUint16be()

example for parse proxy protocol v2 using BytesReader:

hexStr := "0d0a0d0a000d0a515549540a20120c000c22384eac10000104d21f90"
buf, _ := hex.DecodeString(hexStr)

r := BytesReader(buf)

if r.Len() < 16 {
    panic("short buffer")
}

sign, r := r.SplitAt(12)
if !bytes.Equal(signature, sign) {
    panic("invalid signature")
}

header := &Header{}

switch command := r.ReadUint8(); command {
case LOCAL, PROXY:
    header.Command = command
default:
    panic(fmt.Errorf("invalid command %x", command))
}

switch protocol := r.ReadUint8(); protocol {
case UNSPEC, TCPOverIPv4, UDPOverIPv4, TCPOverIPv6, UDPOverIPv6, UNIXStream, UNIXDatagram:
    header.TransportProtocol = protocol
default:
    panic(fmt.Errorf("invalid protocol %x", protocol))
}

length := r.ReadUint16le()
switch length {
case lengthIPv4, lengthIPv6, lengthUnix:
default:
    panic(fmt.Errorf("invalid length %x", length))
}

if r.Len() < int(length) {
    panic("short buffer")
}

switch length {
case lengthIPv4:
    srcAddr := r.ReadIPv4()
    dstAddr := r.ReadIPv4()
    srcPort := r.ReadUint16be()
    dstPort := r.ReadUint16be()

    header.SourceAddr = netip.AddrPortFrom(srcAddr, srcPort)
    header.DestinationAddr = netip.AddrPortFrom(dstAddr, dstPort)
case lengthIPv6:
    srcAddr := r.ReadIPv6()
    dstAddr := r.ReadIPv6()
    srcPort := r.ReadUint16be()
    dstPort := r.ReadUint16be()

    header.SourceAddr = netip.AddrPortFrom(srcAddr, srcPort)
    header.DestinationAddr = netip.AddrPortFrom(dstAddr, dstPort)
default:
    panic(fmt.Errorf("unsupported protocol %x", length))
}

fmt.Printf("%+v\n", header)