[client] Add experimental support for userspace routing (#3134)

client/server/trace.go

@@ -0,0 +1,123 @@
+package server
+
+import (
+	"context"
+	"fmt"
+	"net"
+
+	fw "github.com/netbirdio/netbird/client/firewall/manager"
+	"github.com/netbirdio/netbird/client/firewall/uspfilter"
+	"github.com/netbirdio/netbird/client/proto"
+)
+
+type packetTracer interface {
+	TracePacketFromBuilder(builder *uspfilter.PacketBuilder) (*uspfilter.PacketTrace, error)
+}
+
+func (s *Server) TracePacket(_ context.Context, req *proto.TracePacketRequest) (*proto.TracePacketResponse, error) {
+	s.mutex.Lock()
+	defer s.mutex.Unlock()
+
+	if s.connectClient == nil {
+		return nil, fmt.Errorf("connect client not initialized")
+	}
+	engine := s.connectClient.Engine()
+	if engine == nil {
+		return nil, fmt.Errorf("engine not initialized")
+	}
+
+	fwManager := engine.GetFirewallManager()
+	if fwManager == nil {
+		return nil, fmt.Errorf("firewall manager not initialized")
+	}
+
+	tracer, ok := fwManager.(packetTracer)
+	if !ok {
+		return nil, fmt.Errorf("firewall manager does not support packet tracing")
+	}
+
+	srcIP := net.ParseIP(req.GetSourceIp())
+	if req.GetSourceIp() == "self" {
+		srcIP = engine.GetWgAddr()
+	}
+
+	dstIP := net.ParseIP(req.GetDestinationIp())
+	if req.GetDestinationIp() == "self" {
+		dstIP = engine.GetWgAddr()
+	}
+
+	if srcIP == nil || dstIP == nil {
+		return nil, fmt.Errorf("invalid IP address")
+	}
+
+	var tcpState *uspfilter.TCPState
+	if flags := req.GetTcpFlags(); flags != nil {
+		tcpState = &uspfilter.TCPState{
+			SYN: flags.GetSyn(),
+			ACK: flags.GetAck(),
+			FIN: flags.GetFin(),
+			RST: flags.GetRst(),
+			PSH: flags.GetPsh(),
+			URG: flags.GetUrg(),
+		}
+	}
+
+	var dir fw.RuleDirection
+	switch req.GetDirection() {
+	case "in":
+		dir = fw.RuleDirectionIN
+	case "out":
+		dir = fw.RuleDirectionOUT
+	default:
+		return nil, fmt.Errorf("invalid direction")
+	}
+
+	var protocol fw.Protocol
+	switch req.GetProtocol() {
+	case "tcp":
+		protocol = fw.ProtocolTCP
+	case "udp":
+		protocol = fw.ProtocolUDP
+	case "icmp":
+		protocol = fw.ProtocolICMP
+	default:
+		return nil, fmt.Errorf("invalid protocolcol")
+	}
+
+	builder := &uspfilter.PacketBuilder{
+		SrcIP:     srcIP,
+		DstIP:     dstIP,
+		Protocol:  protocol,
+		SrcPort:   uint16(req.GetSourcePort()),
+		DstPort:   uint16(req.GetDestinationPort()),
+		Direction: dir,
+		TCPState:  tcpState,
+		ICMPType:  uint8(req.GetIcmpType()),
+		ICMPCode:  uint8(req.GetIcmpCode()),
+	}
+	trace, err := tracer.TracePacketFromBuilder(builder)
+	if err != nil {
+		return nil, fmt.Errorf("trace packet: %w", err)
+	}
+
+	resp := &proto.TracePacketResponse{}
+
+	for _, result := range trace.Results {
+		stage := &proto.TraceStage{
+			Name:    result.Stage.String(),
+			Message: result.Message,
+			Allowed: result.Allowed,
+		}
+		if result.ForwarderAction != nil {
+			details := fmt.Sprintf("%s to %s", result.ForwarderAction.Action, result.ForwarderAction.RemoteAddr)
+			stage.ForwardingDetails = &details
+		}
+		resp.Stages = append(resp.Stages, stage)
+	}
+
+	if len(trace.Results) > 0 {
+		resp.FinalDisposition = trace.Results[len(trace.Results)-1].Allowed
+	}
+
+	return resp, nil
+}