feat: Ajouter le module de capture réseau avec filtres BPF et tests associés

Co-authored-by: aider (openrouter/qwen/qwen3-coder-plus) <aider@aider.chat>

internal/capture/capture.go

@@ -0,0 +1,112 @@
+package capture
+
+import (
+	"fmt"
+	"net"
+	"time"
+
+	"github.com/google/gopacket"
+	"github.com/google/gopacket/layers"
+	"github.com/google/gopacket/pcap"
+
+	"ja4sentinel/internal/api"
+)
+
+// CaptureImpl implémente l'interface capture.Capture
+type CaptureImpl struct {
+	handle *pcap.Handle
+}
+
+// New crée une nouvelle instance de capture
+func New() *CaptureImpl {
+	return &CaptureImpl{}
+}
+
+// Run démarre la capture des paquets réseau selon la configuration
+func (c *CaptureImpl) Run(cfg api.Config, out chan<- api.RawPacket) error {
+	var err error
+	c.handle, err = pcap.OpenLive(cfg.Interface, 1600, true, pcap.BlockForever)
+	if err != nil {
+		return fmt.Errorf("failed to open interface %s: %w", cfg.Interface, err)
+	}
+	defer c.handle.Close()
+
+	// Appliquer le filtre BPF s'il est fourni
+	if cfg.BPFFilter != "" {
+		err = c.handle.SetBPFFilter(cfg.BPFFilter)
+		if err != nil {
+			return fmt.Errorf("failed to set BPF filter: %w", err)
+		}
+	} else {
+		// Créer un filtre par défaut pour les ports surveillés
+		defaultFilter := buildBPFForPorts(cfg.ListenPorts)
+		err = c.handle.SetBPFFilter(defaultFilter)
+		if err != nil {
+			return fmt.Errorf("failed to set default BPF filter: %w", err)
+		}
+	}
+
+	packetSource := gopacket.NewPacketSource(c.handle, c.handle.LinkType())
+	
+	for packet := range packetSource.Packets() {
+		// Convertir le paquet en RawPacket
+		rawPkt := packetToRawPacket(packet)
+		if rawPkt != nil {
+			select {
+			case out <- *rawPkt:
+				// Paquet envoyé avec succès
+			default:
+				// Canal plein, ignorer le paquet
+			}
+		}
+	}
+	
+	return nil
+}
+
+// buildBPFForPorts construit un filtre BPF pour les ports TCP spécifiés
+func buildBPFForPorts(ports []uint16) string {
+	if len(ports) == 0 {
+		return "tcp"
+	}
+	
+	filterParts := make([]string, len(ports))
+	for i, port := range ports {
+		filterParts[i] = fmt.Sprintf("tcp port %d", port)
+	}
+	return "(" + joinString(filterParts, ") or (") + ")"
+}
+
+// joinString joint des chaînes avec un séparateur
+func joinString(parts []string, sep string) string {
+	if len(parts) == 0 {
+		return ""
+	}
+	result := parts[0]
+	for _, part := range parts[1:] {
+		result += sep + part
+	}
+	return result
+}
+
+// packetToRawPacket convertit un paquet gopacket en RawPacket
+func packetToRawPacket(packet gopacket.Packet) *api.RawPacket {
+	data := packet.Data()
+	if len(data) == 0 {
+		return nil
+	}
+
+	return &api.RawPacket{
+		Data:      data,
+		Timestamp: packet.Metadata().Timestamp.UnixNano(),
+	}
+}
+
+// Close ferme correctement la capture
+func (c *CaptureImpl) Close() error {
+	if c.handle != nil {
+		c.handle.Close()
+		return nil
+	}
+	return nil
+}

internal/capture/capture_test.go

@@ -0,0 +1,84 @@
+package capture
+
+import (
+	"testing"
+	"time"
+
+	"ja4sentinel/internal/api"
+)
+
+func TestBuildBPFForPorts(t *testing.T) {
+	tests := []struct {
+		name  string
+		ports []uint16
+		want  string
+	}{
+		{
+			name:  "single port",
+			ports: []uint16{443},
+			want:  "(tcp port 443)",
+		},
+		{
+			name:  "multiple ports",
+			ports: []uint16{443, 8443},
+			want:  "(tcp port 443) or (tcp port 8443)",
+		},
+		{
+			name:  "no ports",
+			ports: []uint16{},
+			want:  "tcp",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := buildBPFForPorts(tt.ports)
+			if got != tt.want {
+				t.Errorf("buildBPFForPorts() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}
+
+func TestJoinString(t *testing.T) {
+	tests := []struct {
+		name  string
+		parts []string
+		sep   string
+		want  string
+	}{
+		{
+			name:  "empty slices",
+			parts: []string{},
+			sep:   ", ",
+			want:  "",
+		},
+		{
+			name:  "single element",
+			parts: []string{"hello"},
+			sep:   ", ",
+			want:  "hello",
+		},
+		{
+			name:  "multiple elements",
+			parts: []string{"hello", "world", "test"},
+			sep:   ", ",
+			want:  "hello, world, test",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := joinString(tt.parts, tt.sep)
+			if got != tt.want {
+				t.Errorf("joinString() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}
+
+// Tests d'intégration nécessitant une interface valide seront à faire dans des environnements de test appropriés
+// car la capture réseau nécessite des permissions élevées
+func TestCaptureIntegration(t *testing.T) {
+	t.Skip("Skipping integration test requiring network access and elevated privileges")
+}