Write/Read string to io.Writer/Reader with length header

netutil.go

package core
import "io"
import "encoding/binary"
import "bufio"


func WriteString(writer io.Writer, s string) (err error) {
    l := len(s)
    if l < 128 {
        err = binary.Write(writer, binary.BigEndian, byte(l))
    } else {
        err = binary.Write(writer, binary.BigEndian, uint32(l))
    }
    if err != nil {
        return
    }
    _, err = writer.Write([]byte(s))
    return
}

func ReadString(reader io.Reader) (string, error) {
    var l byte
    r := bufio.NewReader(reader)
    if err := binary.Read(r, binary.BigEndian, &l); err != nil {
        return "", err
    }
    if l < 128 {
        var buf [128]byte
        b := buf[:l]
        if _, err := r.Read(b); err != nil {
            return "", err
        }
        return string(b), nil
    }

    r.UnreadByte()

    var ll uint32
    if err := binary.Read(r, binary.BigEndian, &ll); err != nil {
        return "", err
    }
    b := make([]byte, ll)
    if _, err := r.Read(b); err != nil {
        return "", err
    }
    return string(b), nil
}