use bufio.Reader may error

[ghost]

func ServConn(local_reader *bufio.Reader, local *net.TCPConn, dialer Dialer) error {
connections.Add(1)
defer local.Close()
defer connections.Done()

// SOCKS does not include a length in the header, so take
// a punt that each request will be readable in one go.
buf := make([]byte, 256)
n, err := local_reader.Read(buf)
if err != nil || n < 2 {
    //log.Printf("[%s] unable to read SOCKS header: %v", local.RemoteAddr(), err)
    return fmt.Errorf("[%s] unable to read SOCKS header: %v", local.RemoteAddr(), err)
}
buf = buf[:n]

.......
see http://golang.org/pkg/bufio/#Reader.Read
It calls Read at most once on the underlying Reader, hence n may be less than len(p).
if local_reader.Read(buf) return 4 bytes, it may fall, is it?

[yinqiwen]

Theoretically, it may fail. But in reality, the header part is sent by client at once after connected, Server have very little chance that read less data than such a few bytes.