go-tunnel/cmd/server/main.go

package main

import (
	"context"
	"net"
	"net/http"
	"net/http/httputil"
	"net/url"
	"strings"
	"time"

	"cdr.dev/slog"
	"forge.cadoles.com/wpetit/go-tunnel"
	"github.com/pkg/errors"
	"gitlab.com/wpetit/goweb/logger"
)

const sharedKey = "go-tunnel"
const salt = "go-tunnel"

var registry = NewRegistry()

func main() {
	ctx := context.Background()

	logger.SetLevel(slog.LevelDebug)

	server := tunnel.NewServer(
		tunnel.WithServerAESBlockCrypt(sharedKey, salt),
		tunnel.WithServerOnClientAuth(registry.OnClientAuth),
		tunnel.WithServerOnClientDisconnect(registry.OnClientDisconnect),
	)

	go func() {
		if err := server.Listen(ctx); err != nil {
			logger.Fatal(ctx, "error while listening", logger.E(err))
		}
	}()

	if err := http.ListenAndServe(":3003", http.HandlerFunc(handleRequest)); err != nil {
		logger.Fatal(ctx, "error while listening", logger.E(err))
	}
}

func handleRequest(w http.ResponseWriter, r *http.Request) {
	subdomains := strings.SplitN(r.Host, ".", 2)

	if len(subdomains) < 2 {
		http.Error(w, http.StatusText(http.StatusNotFound), http.StatusNotFound)

		return
	}

	clientID := subdomains[0]
	remoteClient := registry.Get(clientID)

	if remoteClient == nil {
		http.Error(w, http.StatusText(http.StatusBadGateway), http.StatusBadGateway)

		return
	}

	target, err := url.Parse("http://localhost:3000")
	if err != nil {
		logger.Fatal(r.Context(), "could not parse url", logger.E(err))
	}

	reverse := httputil.NewSingleHostReverseProxy(target)
	reverse.Transport = &http.Transport{
		Proxy: http.ProxyFromEnvironment,
		DialContext: func(ctx context.Context, network string, addr string) (net.Conn, error) {
			conn, err := remoteClient.Proxy(ctx, network, addr)
			if err != nil {
				return nil, errors.WithStack(err)
			}

			return conn, nil
		},
		ForceAttemptHTTP2:     true,
		MaxIdleConns:          100,
		IdleConnTimeout:       90 * time.Second,
		TLSHandshakeTimeout:   10 * time.Second,
		ExpectContinueTimeout: 1 * time.Second,
	}

	reverse.ServeHTTP(w, r)
}