chore: refine code and add annotations

control/bpf_utils.go

@@ -11,11 +11,13 @@ import (
 	"errors"
 	"fmt"
 	"github.com/cilium/ebpf"
+	"github.com/sirupsen/logrus"
 	"github.com/v2rayA/dae/common"
 	"github.com/v2rayA/dae/common/consts"
 	"github.com/v2rayA/dae/pkg/ebpf_internal"
 	"net/netip"
 	"os"
+	"path/filepath"
 	"reflect"
 	"strings"
 	"sync"
@@ -183,3 +185,61 @@ func (p bpfIfParams) CheckVersionRequirement(version *internal.Version) (err err
 	}
 	return nil
 }
+
+type loadBpfOptions struct {
+	PinPath           string
+	CollectionOptions *ebpf.CollectionOptions
+	BindLan           bool
+	BindWan           bool
+}
+
+func selectivelyLoadBpfObjects(
+	log *logrus.Logger,
+	bpf *bpfObjects,
+	opts *loadBpfOptions,
+) (err error) {
+	// Trick. Replace the beams with rotten timbers to reduce the loading.
+	var obj interface{} = bpf // Bind to both LAN and WAN.
+	if opts.BindLan && !opts.BindWan {
+		// Only bind LAN.
+		obj = &bpfObjectsLan{}
+	} else if !opts.BindLan && opts.BindWan {
+		// Only bind to WAN.
+		// Trick. Replace the beams with rotten timbers.
+		obj = &bpfObjectsWan{}
+	}
+retryLoadBpf:
+	if err = loadBpfObjects(obj, opts.CollectionOptions); err != nil {
+		if errors.Is(err, ebpf.ErrMapIncompatible) {
+			// Map property is incompatible. Remove the old map and try again.
+			prefix := "use pinned map "
+			_, after, ok := strings.Cut(err.Error(), prefix)
+			if !ok {
+				return fmt.Errorf("loading objects: bad format: %w", err)
+			}
+			mapName, _, _ := strings.Cut(after, ":")
+			_ = os.Remove(filepath.Join(opts.PinPath, mapName))
+			log.Infof("Incompatible new map format with existing map %v detected; removed the old one.", mapName)
+			goto retryLoadBpf
+		}
+		// Get detailed log from ebpf.internal.(*VerifierError)
+		if log.Level == logrus.FatalLevel {
+			if v := reflect.Indirect(reflect.ValueOf(errors.Unwrap(errors.Unwrap(err)))); v.Kind() == reflect.Struct {
+				if _log := v.FieldByName("Log"); _log.IsValid() {
+					if strSlice, ok := _log.Interface().([]string); ok {
+						log.Fatalln(strings.Join(strSlice, "\n"))
+					}
+				}
+			}
+		}
+		if strings.Contains(err.Error(), "no BTF found for kernel version") {
+			err = fmt.Errorf("%w: maybe installing the linux-headers package will solve it", err)
+		}
+		return err
+	}
+	if _, ok := obj.(*bpfObjects); !ok {
+		// Reverse takeover.
+		AssignBpfObjects(bpf, obj)
+	}
+	return nil
+}

control/control_plane.go

@@ -7,7 +7,6 @@ package control
 
 import (
 	"context"
-	"errors"
 	"fmt"
 	"github.com/cilium/ebpf"
 	"github.com/cilium/ebpf/rlimit"
@@ -26,7 +25,6 @@ import (
 	"net/netip"
 	"os"
 	"path/filepath"
-	"reflect"
 	"strconv"
 	"strings"
 	"sync"
@@ -68,7 +66,8 @@ func NewControlPlane(
 	if e != nil {
 		return nil, fmt.Errorf("failed to get kernel version: %w", e)
 	}
-	// Must judge version from high to low to reduce the number of user upgrading kernel.
+	/// Check linux kernel requirements.
+	// Check version from high to low to reduce the number of user upgrading kernel.
 	if kernelVersion.Less(consts.ChecksumFeatureVersion) {
 		return nil, fmt.Errorf("your kernel version %v does not support checksum related features; expect >=%v; upgrade your kernel and try again",
 			kernelVersion.String(),
@@ -90,7 +89,7 @@ func NewControlPlane(
 			consts.BasicFeatureVersion.String())
 	}
 
-	// Allow the current process to lock memory for eBPF resources.
+	/// Allow the current process to lock memory for eBPF resources.
 	if err = rlimit.RemoveMemlock(); err != nil {
 		return nil, fmt.Errorf("rlimit.RemoveMemlock:%v", err)
 	}
@@ -99,7 +98,7 @@ func NewControlPlane(
 		return nil, err
 	}
 
-	// Load pre-compiled programs and maps into the kernel.
+	/// Load pre-compiled programs and maps into the kernel.
 	log.Infof("Loading eBPF programs and maps into the kernel")
 	var bpf bpfObjects
 	var ProgramOptions = ebpf.ProgramOptions{
@@ -109,54 +108,19 @@ func NewControlPlane(
 		ProgramOptions.LogLevel = ebpf.LogLevelBranch | ebpf.LogLevelStats
 		// ProgramOptions.LogLevel = ebpf.LogLevelInstruction | ebpf.LogLevelStats
 	}
-
+	collectionOpts := &ebpf.CollectionOptions{
-	// Trick. Replace the beams with rotten timbers to reduce the loading.
-	var obj interface{} = &bpf // Bind to both LAN and WAN.
-	if len(lanInterface) > 0 && len(wanInterface) == 0 {
-		// Only bind LAN.
-		obj = &bpfObjectsLan{}
-	} else if len(lanInterface) == 0 && len(wanInterface) > 0 {
-		// Only bind to WAN.
-		// Trick. Replace the beams with rotten timbers.
-		obj = &bpfObjectsWan{}
-	}
-retryLoadBpf:
-	if err = loadBpfObjects(obj, &ebpf.CollectionOptions{
 		Maps: ebpf.MapOptions{
 			PinPath: pinPath,
 		},
 		Programs: ProgramOptions,
+	}
+	if err = selectivelyLoadBpfObjects(log, &bpf, &loadBpfOptions{
+		PinPath:           pinPath,
+		CollectionOptions: collectionOpts,
+		BindLan:           len(lanInterface) > 0,
+		BindWan:           len(wanInterface) > 0,
 	}); err != nil {
-		if errors.Is(err, ebpf.ErrMapIncompatible) {
+		return nil, fmt.Errorf("load eBPF objects: %w", err)
-			// Map property is incompatible. Remove the old map and try again.
-			prefix := "use pinned map "
-			_, after, ok := strings.Cut(err.Error(), prefix)
-			if !ok {
-				return nil, fmt.Errorf("loading objects: bad format: %w", err)
-			}
-			mapName, _, _ := strings.Cut(after, ":")
-			_ = os.Remove(filepath.Join(pinPath, mapName))
-			log.Infof("Incompatible new map format with existing map %v detected; removed the old one.", mapName)
-			goto retryLoadBpf
-		}
-		// Get detailed log from ebpf.internal.(*VerifierError)
-		if log.Level == logrus.FatalLevel {
-			if v := reflect.Indirect(reflect.ValueOf(errors.Unwrap(errors.Unwrap(err)))); v.Kind() == reflect.Struct {
-				if _log := v.FieldByName("Log"); _log.IsValid() {
-					if strSlice, ok := _log.Interface().([]string); ok {
-						log.Fatalln(strings.Join(strSlice, "\n"))
-					}
-				}
-			}
-		}
-		if strings.Contains(err.Error(), "no BTF found for kernel version") {
-			err = fmt.Errorf("%w: maybe installing the linux-headers package will solve it", err)
-		}
-		return nil, fmt.Errorf("loading objects: %w", err)
-	}
-	if _, ok := obj.(*bpfObjects); !ok {
-		// Reverse takeover.
-		AssignBpfObjects(&bpf, obj)
 	}
 
 	// Write params.
@@ -170,7 +134,7 @@ retryLoadBpf:
 	if err = bpf.ParamMap.Update(consts.ControlPlaneOidKey, uint32(os.Getpid()), ebpf.UpdateAny); err != nil {
 		return nil, err
 	}
-	// Write ip_proto to hdr_size map for IPv6 extension extraction.
+	// Write ip_proto to hdr_size mapping for IPv6 extension extraction (it is just for eBPF code insns optimization).
 	if err = bpf.IpprotoHdrsizeMap.Update(uint32(unix.IPPROTO_HOPOPTS), int32(-1), ebpf.UpdateAny); err != nil {
 		return nil, err
 	}
@@ -226,7 +190,7 @@ retryLoadBpf:
 		}
 	}
 
-	// DialerGroups (outbounds).
+	/// DialerGroups (outbounds).
 	option := &dialer.GlobalOption{
 		Log:           log,
 		CheckUrl:      checkUrl,
@@ -274,6 +238,7 @@ retryLoadBpf:
 		outbounds = append(outbounds, dialerGroup)
 	}
 
+	/// Routing.
 	// Generate outboundName2Id from outbounds.
 	if len(outbounds) > 0xff {
 		return nil, fmt.Errorf("too many outbounds")
@@ -283,8 +248,6 @@ retryLoadBpf:
 		outboundName2Id[o.Name] = uint8(i)
 	}
 	builder := NewRoutingMatcherBuilder(outboundName2Id, &bpf)
-
-	// Routing.
 	var rules []*config_parser.RoutingRule
 	if rules, err = routing.ApplyRulesOptimizers(routingA.Rules,
 		&routing.RefineFunctionParamKeyOptimizer{},
@@ -308,7 +271,7 @@ retryLoadBpf:
 		return nil, fmt.Errorf("RoutingMatcherBuilder.Build: %w", err)
 	}
 
-	// DNS upstream.
+	/// DNS upstream.
 	var dnsAddrPort netip.AddrPort
 	if dnsUpstream != "" {
 		dnsAddrPort, err = netip.ParseAddrPort(dnsUpstream)
@@ -332,6 +295,7 @@ retryLoadBpf:
 		}
 	}
 
+	/// Listen address.
 	listenIp := "::1"
 	if len(wanInterface) > 0 {
 		listenIp = "0.0.0.0"