Initial commit

mapping.go

@@ -0,0 +1,96 @@
+package main
+
+import (
+	"crypto/tls"
+	"fmt"
+	"io"
+	"log/slog"
+	"net"
+	"net/http"
+	"net/url"
+	"sync"
+)
+
+type ProxyDirection struct {
+	Output *url.URL
+
+	listener *Listener
+}
+
+type HostMapping map[string]ProxyDirection // hostName -> rule
+
+func (h HostMapping) Add(host, outputUrlStr string) error {
+	outputUrl, err := url.Parse(outputUrlStr)
+	if err != nil {
+		return err
+	}
+
+	pd := ProxyDirection{outputUrl, NewListener()}
+
+	switch outputUrl.Scheme {
+	case "file":
+		server := http.Server{Handler: http.FileServer(http.Dir(outputUrl.Path))}
+		go func() { _ = server.Serve(pd.listener) }()
+	case "tcp":
+		go func(pd ProxyDirection) {
+			for {
+				conn, err := pd.listener.Accept()
+				if err != nil {
+					slog.Debug(err.Error())
+					continue
+				}
+				go func() { _ = handleProxy(conn.(*tls.Conn), pd.Output) }()
+			}
+		}(pd)
+	default:
+		return fmt.Errorf("unknown output protocol: %v", outputUrl.Scheme)
+	}
+
+	h[host] = pd
+
+	return nil
+}
+
+func handleTlsConn(conn *tls.Conn, hosts HostMapping) error {
+	err := conn.Handshake()
+	if err != nil {
+		return fmt.Errorf("handshake error: %v", err)
+	}
+
+	hostName := conn.ConnectionState().ServerName
+	proxyDirection, exists := hosts[hostName]
+	if !exists {
+		return fmt.Errorf("requested host not found: %s", hostName)
+	}
+
+	proxyDirection.listener.Add(conn)
+
+	return nil
+}
+
+func handleProxy(conn *tls.Conn, outputUrl *url.URL) error {
+	c, err := net.Dial(outputUrl.Scheme, outputUrl.Host)
+	if err != nil {
+		return fmt.Errorf("dial: %v", err)
+	}
+	defer c.Close()
+
+	wg := new(sync.WaitGroup)
+	wg.Add(2)
+
+	go func() {
+		defer wg.Done()
+
+		_, _ = io.Copy(conn, c)
+	}()
+
+	go func() {
+		defer wg.Done()
+
+		_, _ = io.Copy(c, conn)
+	}()
+
+	wg.Wait()
+
+	return nil
+}