如何使用过滤器进行websocket portforward或在golang中保存（以数组形式）转发的数据包？

i found a ready source code on github for portforwarding in golang

here is the code

package main

import (
"io"
"log"
"net"
)

var localServerHost = "localhost:1020"
var remoteServerHost = "192.168.10.1:1020"

func main() {

ln, err := net.Listen("tcp", localServerHost)
if err != nil {
    log.Fatal(err)
}

log.Println("Port forwarding server up and listening on ", 
localServerHost)

for {
    conn, err := ln.Accept()
    if err != nil {
        log.Fatal(err)
    }

    go handleConnection(conn)
 }
}

func forward(src, dest net.Conn) {
defer src.Close()
defer dest.Close()
io.Copy(src, dest)
}

func handleConnection(c net.Conn) {

log.Println("Connection from : ", c.RemoteAddr())

remote, err := net.Dial("tcp", remoteServerHost)
if err != nil {
    log.Fatal(err)
}

log.Println("Connected to ", remoteServerHost)
go forward(c, remote)
go forward(remote, c)
}

i dont have any idea now how can i put flag on user connections, so then i can read data form user connection and save or filter some of packets depend on connection flag

its a wrong way ?

Edit: This is an answer original question about forwarding and filtering TCP. @ermya has since changed the question to ask about WebSockets. This answer is not relevant to what is now a very different question.

You can filter the stream by interposing a reader or writer in the io.Copy operation. Here's how to interpose a reader:

type myFilter struct {
    r io.Reader
}

func (f myFilter) Read(p []byte) (int, error) {
    n, err := f.r.Read(p)

    // Do something with p[:n].  As an example, the following for loop shows how 
    // to uppercase ASCII letters.  Replace this for loop with the filtering of 
    // your choice.
    for i, b := range p[:n] {
        if 'a' <= b && b <= 'z' {
           p[i] = b - ('a' - 'A')
        }
    }

    return n, err
}

Filter data from net.Conn by replacing the call to go forward(remote, c) with:

go func() {
    defer remote.Close()
    defer c.Close()
    io.Copy(remote, myFilter{c})  // interpose the filter here
}()

As an aside, the naming in forward is confusing because src is actually the destination and dest is the source. Use this:

func forward(dest, src net.Conn) {
  defer src.Close()
  defer dest.Close()
  io.Copy(dest, src)
}