Example of how fasthttp might get corrupted with fasthttp

corrupt-header-example.go

package main

import (
	"bytes"
	"math/rand"
	"net"
	"time"

	"github.com/valyala/fasthttp"
)

func main() {
	var b []byte

	s := &fasthttp.Server{
		Handler: func(ctx *fasthttp.RequestCtx) {
			if b == nil {
				// Keeping a reference to a header after the request ended is a bad idea!
				// If you need to do this copy() the value.
				b = ctx.Request.Header.Peek("X-Test")
			} else if s := string(ctx.Request.Header.Peek("X-Test")); s != "foobar" {
				println(s)
			}
		},
	}

	rw := &readWriter{}
	rw.r.Grow(1024)
	rw.w.Grow(1024)

	rw.r.WriteString("GET / HTTP/1.1\r\nHost: google.com\r\nX-Test: foobar\r\n\r\n")
	if err := s.ServeConn(rw); err != nil {
		panic(err)
	}

	// Reset the write buffer to make space for the next response.
	rw.w.Reset()

	go func() {
		for {
			// We are always writing "foobar"
			rw.r.WriteString("GET / HTTP/1.1\r\nHost: google.com\r\nX-Test: foobar\r\n\r\n")
			if err := s.ServeConn(rw); err != nil {
				panic(err)
			}

			// Reset the write buffer to make space for the next response.
			rw.w.Reset()

			time.Sleep(time.Millisecond)
		}
	}()

	for {
		// Change the first byte of the header that we kept to a random character between a and z.
		b[0] = 'a' + byte(rand.Intn('z'-'a'))
		time.Sleep(time.Microsecond)
	}
}

var zeroTCPAddr = &net.TCPAddr{
	IP: net.IPv4zero,
}

type readWriter struct {
	net.Conn
	r bytes.Buffer
	w bytes.Buffer
}

func (rw *readWriter) Close() error {
	return nil
}

func (rw *readWriter) Read(b []byte) (int, error) {
	return rw.r.Read(b)
}

func (rw *readWriter) Write(b []byte) (int, error) {
	return rw.w.Write(b)
}

func (rw *readWriter) RemoteAddr() net.Addr {
	return zeroTCPAddr
}

func (rw *readWriter) LocalAddr() net.Addr {
	return zeroTCPAddr
}

func (rw *readWriter) SetReadDeadline(t time.Time) error {
	return nil
}

func (rw *readWriter) SetWriteDeadline(t time.Time) error {
	return nil
}