Add stats collection

client/firewall/manager/firewall.go

@@ -100,6 +100,9 @@ type Manager interface {
 
 	// Flush the changes to firewall controller
 	Flush() error
+
+	// CollectStats returns the statistics of the firewall manager
+	CollectStats() []*FlowStats
 }
 
 func GenKey(format string, pair RouterPair) string {

client/firewall/manager/stats.go

@@ -0,0 +1,107 @@
+package manager
+
+import (
+	"encoding/json"
+	"net"
+	"slices"
+	"strconv"
+	"sync/atomic"
+	"time"
+)
+
+const (
+	DirectionInbound  Direction = 0
+	DirectionOutbound Direction = 1
+)
+
+type Direction uint8
+
+func (d Direction) String() string {
+	switch d {
+	case DirectionInbound:
+		return "inbound"
+	case DirectionOutbound:
+		return "outbound"
+	default:
+		return "unknown"
+	}
+}
+
+// FlowStats tracks statistics for an individual connection
+type FlowStats struct {
+	StartTime  time.Time
+	LastSeen   time.Time
+	BytesIn    atomic.Uint64
+	BytesOut   atomic.Uint64
+	PacketsIn  atomic.Uint64
+	PacketsOut atomic.Uint64
+	Protocol   uint8
+	Direction  Direction
+	SourceIP   net.IP
+	DestIP     net.IP
+	SourcePort uint16
+	DestPort   uint16
+}
+
+func (f *FlowStats) Clone() *FlowStats {
+	flowCopy := FlowStats{
+		StartTime:  f.StartTime,
+		LastSeen:   f.LastSeen,
+		Protocol:   f.Protocol,
+		Direction:  f.Direction,
+		SourceIP:   slices.Clone(f.SourceIP),
+		DestIP:     slices.Clone(f.DestIP),
+		SourcePort: f.SourcePort,
+		DestPort:   f.DestPort,
+	}
+	flowCopy.BytesIn.Store(f.BytesIn.Load())
+	flowCopy.BytesOut.Store(f.BytesOut.Load())
+	flowCopy.PacketsIn.Store(f.PacketsIn.Load())
+	flowCopy.PacketsOut.Store(f.PacketsOut.Load())
+
+	return &flowCopy
+}
+
+// MarshalJSON implements json.Marshaler interface
+func (f *FlowStats) MarshalJSON() ([]byte, error) {
+	return json.Marshal(&struct {
+		StartTime  time.Time
+		LastSeen   time.Time
+		BytesIn    uint64
+		BytesOut   uint64
+		PacketsIn  uint64
+		PacketsOut uint64
+		Protocol   Protocol
+		Direction  string
+		SourceIP   net.IP
+		DestIP     net.IP
+		SourcePort uint16
+		DestPort   uint16
+	}{
+		StartTime:  f.StartTime,
+		LastSeen:   f.LastSeen,
+		BytesIn:    f.BytesIn.Load(),
+		BytesOut:   f.BytesOut.Load(),
+		PacketsIn:  f.PacketsIn.Load(),
+		PacketsOut: f.PacketsOut.Load(),
+		Protocol:   protoFromInt(f.Protocol),
+		Direction:  f.Direction.String(),
+		SourceIP:   f.SourceIP,
+		DestIP:     f.DestIP,
+		SourcePort: f.SourcePort,
+		DestPort:   f.DestPort,
+	})
+}
+
+func protoFromInt(p uint8) Protocol {
+	switch p {
+	case 6:
+		return ProtocolTCP
+	case 17:
+		return ProtocolUDP
+	case 1:
+		return ProtocolICMP
+	default:
+		return Protocol(strconv.Itoa(int(p)))
+	}
+}