HTTP Server logging everything sent and received on the TCP socket.

main.go

package main

import (
	"bufio"
	"fmt"
	"log"
	"net"
	"net/http"
)

type loggingConn struct {
	net.Conn
}

func (conn loggingConn) Read(b []byte) (n int, err error) {
	n, err = conn.Conn.Read(b)
	if n > 0 {
		log.Printf("Received: %q", b[:n])
	}
	return
}

func (conn loggingConn) Write(b []byte) (n int, err error) {
	n, err = conn.Conn.Write(b)
	if n > 0 {
		log.Printf("Sent: %q", b[:n])
	}
	return
}

func loggingListener(inner net.Listener) net.Listener {
	return &wrappedListener{inner}
}

type wrappedListener struct {
	net.Listener
}

func (ln wrappedListener) Accept() (net.Conn, error) {
	conn, err := ln.Listener.Accept()
	if err != nil {
		return nil, err
	}
	return loggingConn{conn}, nil
}

func handler(w http.ResponseWriter, r *http.Request) {
	fmt.Fprintf(w, "Hello, world!")
}

func main() {
	ln, err := net.Listen("tcp", ":80")
	if err != nil {
		log.Fatal(err)
	}

	http.HandleFunc("/", handler)
	log.Fatal(http.Serve(loggingListener(ln), nil))
}