http.go

package main

import (
	"crypto/tls"
	"log"
	"net"
	"net/http"
	"strings"
	"time"
)

type Server struct {
	Handler http.Handler
	Opts    *Options
}

func (s *Server) ListenAndServe() {
	if s.Opts.TLSKeyFile != "" || s.Opts.TLSCertFile != "" {
		s.ServeHTTPS()
	} else {
		s.ServeHTTP()
	}
}

func (s *Server) ServeHTTP() {
	httpAddress := s.Opts.HttpAddress
	scheme := ""

	i := strings.Index(httpAddress, "://")
	if i > -1 {
		scheme = httpAddress[0:i]
	}

	var networkType string
	switch scheme {
	case "", "http":
		networkType = "tcp"
	default:
		networkType = scheme
	}

	slice := strings.SplitN(httpAddress, "//", 2)
	listenAddr := slice[len(slice)-1]

	listener, err := net.Listen(networkType, listenAddr)
	if err != nil {
		log.Fatalf("FATAL: listen (%s, %s) failed - %s", networkType, listenAddr, err)
	}
	log.Printf("HTTP: listening on %s", listenAddr)

	server := &http.Server{Handler: s.Handler}
	err = server.Serve(listener)
	if err != nil && !strings.Contains(err.Error(), "use of closed network connection") {
		log.Printf("ERROR: http.Serve() - %s", err)
	}

	log.Printf("HTTP: closing %s", listener.Addr())
}

func (s *Server) ServeHTTPS() {
	addr := s.Opts.HttpsAddress
	config := &tls.Config{
		MinVersion: tls.VersionTLS12,
		MaxVersion: tls.VersionTLS13,
	}
	if config.NextProtos == nil {
		config.NextProtos = []string{"http/1.1"}
	}

	var err error
	config.Certificates = make([]tls.Certificate, 1)
	config.Certificates[0], err = tls.LoadX509KeyPair(s.Opts.TLSCertFile, s.Opts.TLSKeyFile)
	if err != nil {
		log.Fatalf("FATAL: loading tls config (%s, %s) failed - %s", s.Opts.TLSCertFile, s.Opts.TLSKeyFile, err)
	}

	ln, err := net.Listen("tcp", addr)
	if err != nil {
		log.Fatalf("FATAL: listen (%s) failed - %s", addr, err)
	}
	log.Printf("HTTPS: listening on %s", ln.Addr())

	tlsListener := tls.NewListener(tcpKeepAliveListener{ln.(*net.TCPListener)}, config)
	srv := &http.Server{Handler: s.Handler}
	err = srv.Serve(tlsListener)

	if err != nil && !strings.Contains(err.Error(), "use of closed network connection") {
		log.Printf("ERROR: https.Serve() - %s", err)
	}

	log.Printf("HTTPS: closing %s", tlsListener.Addr())
}

// tcpKeepAliveListener sets TCP keep-alive timeouts on accepted
// connections. It's used by ListenAndServe and ListenAndServeTLS so
// dead TCP connections (e.g. closing laptop mid-download) eventually
// go away.
type tcpKeepAliveListener struct {
	*net.TCPListener
}

func (ln tcpKeepAliveListener) Accept() (c net.Conn, err error) {
	tc, err := ln.AcceptTCP()
	if err != nil {
		return
	}
	tc.SetKeepAlive(true)
	tc.SetKeepAlivePeriod(3 * time.Minute)
	return tc, nil
}

// extract client ip address from configured header
func extractClientIP(req *http.Request, header string) string {
	if header != "" {
		val := req.Header.Get(header)
		if val != "" {
			if header == "X-Forwarded-For" {
				val = strings.TrimSpace(strings.SplitN(val, ",", 2)[0])
			}
			return val
		}
	}
	return ""
}

func redirectToHTTPS(h http.Handler, httpsAddr string) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		proto := strings.ToLower(r.Header.Get("X-Forwarded-Proto"))
		if ((r.TLS == nil && proto != "https") || (r.TLS != nil && proto == "http")) && r.URL.Path != "/ping" {
			url := *r.URL
			host := strings.Split(r.Host, ":")[0]
			if !strings.HasSuffix(httpsAddr, ":443") {
				host += ":" + strings.Split(httpsAddr, ":")[1]
			}
			url.Host = host
			url.Scheme = "https"
			http.Redirect(w, r, url.String(), http.StatusPermanentRedirect)
		} else {
			// normal case
			h.ServeHTTP(w, r)
		}
	})
}