add relay proxy

pkg/handler/relay/forward.go

@@ -0,0 +1,49 @@
+package relay
+
+import (
+	"context"
+	"net"
+	"time"
+
+	"github.com/go-gost/gost/pkg/chain"
+	"github.com/go-gost/gost/pkg/handler"
+)
+
+func (h *relayHandler) handleForward(ctx context.Context, conn net.Conn, network string) {
+	target := h.group.Next()
+	if target == nil {
+		h.logger.Error("no target available")
+		return
+	}
+
+	h.logger = h.logger.WithFields(map[string]interface{}{
+		"dst": target.Addr(),
+	})
+
+	h.logger.Infof("%s >> %s", conn.RemoteAddr(), target.Addr())
+
+	r := (&chain.Router{}).
+		WithChain(h.chain).
+		WithRetry(h.md.retryCount).
+		WithLogger(h.logger)
+
+	cc, err := r.Dial(ctx, network, target.Addr())
+	if err != nil {
+		h.logger.Error(err)
+		// TODO: the router itself may be failed due to the failed node in the router,
+		// the dead marker may be a wrong operation.
+		target.Marker().Mark()
+		return
+	}
+	defer cc.Close()
+	target.Marker().Reset()
+
+	t := time.Now()
+	h.logger.Infof("%s <-> %s", conn.RemoteAddr(), target.Addr())
+	handler.Transport(conn, cc)
+	h.logger.
+		WithFields(map[string]interface{}{
+			"duration": time.Since(t),
+		}).
+		Infof("%s >-< %s", conn.RemoteAddr(), target.Addr())
+}