UDP scan

README.md

@@ -10,6 +10,7 @@ Features:
   * TCP SYN scan
   * TCP FIN / NULL / Xmas scans
   * Custom TCP scans with any TCP flags
+  * UDP scan
 
 ## Building
 

command/udp.go

@@ -0,0 +1,60 @@
+package command
+
+import (
+	"context"
+	"errors"
+	"os"
+	"os/signal"
+	"runtime"
+	"strings"
+
+	"github.com/spf13/cobra"
+	"github.com/v-byte-cpu/sx/pkg/scan"
+	"github.com/v-byte-cpu/sx/pkg/scan/arp"
+	"github.com/v-byte-cpu/sx/pkg/scan/icmp"
+	"github.com/v-byte-cpu/sx/pkg/scan/udp"
+)
+
+func init() {
+	udpCmd.Flags().StringVarP(&cliPortsFlag, "ports", "p", "", "set ports to scan")
+	rootCmd.AddCommand(udpCmd)
+}
+
+var udpCmd = &cobra.Command{
+	Use:     "udp [flags] subnet",
+	Example: strings.Join([]string{"udp -p 22 192.168.0.1/24", "udp -p 22-4567 10.0.0.1"}, "\n"),
+	Short:   "Perform UDP scan",
+	Args: func(cmd *cobra.Command, args []string) error {
+		if len(args) != 1 {
+			return errors.New("requires one ip subnet argument")
+		}
+		return nil
+	},
+	RunE: func(cmd *cobra.Command, args []string) (err error) {
+		ctx, cancel := signal.NotifyContext(context.Background(), os.Interrupt)
+		defer cancel()
+
+		var conf *scanConfig
+		if conf, err = parseScanConfig(udp.ScanType, args[0], cliPortsFlag); err != nil {
+			return
+		}
+
+		m := newUDPScanMethod(ctx, conf)
+
+		return startEngine(ctx, &engineConfig{
+			logger:     conf.logger,
+			scanRange:  conf.scanRange,
+			scanMethod: m,
+			bpfFilter:  icmp.BPFFilter,
+		})
+	},
+}
+
+func newUDPScanMethod(ctx context.Context, conf *scanConfig) *udp.ScanMethod {
+	reqgen := arp.NewCacheRequestGenerator(
+		scan.RequestGeneratorFunc(scan.Requests), conf.gatewayIP, conf.cache)
+	pktgen := scan.NewPacketMultiGenerator(udp.NewPacketFiller(), runtime.NumCPU())
+	psrc := scan.NewPacketSource(reqgen, pktgen)
+	results := scan.NewResultChan(ctx, 1000)
+	return udp.NewScanMethod(psrc, results)
+}

pkg/scan/icmp/bpf.go

@@ -0,0 +1,18 @@
+package icmp
+
+import (
+	"fmt"
+
+	"github.com/v-byte-cpu/sx/pkg/scan"
+)
+
+// Set to typical maximum Ethernet frame size = MTU (1500 bytes)
+// + Ethernet header (14 bytes) + FCS (4 bytes)
+const MaxPacketLength = 1518
+
+func BPFFilter(r *scan.Range) (filter string, maxPacketLength int) {
+	if r.DstSubnet == nil {
+		return "icmp", MaxPacketLength
+	}
+	return fmt.Sprintf("icmp and ip src net %s", r.DstSubnet.String()), MaxPacketLength
+}

pkg/scan/icmp/bpf_test.go

@@ -0,0 +1,43 @@
+package icmp
+
+import (
+	"net"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/v-byte-cpu/sx/pkg/scan"
+)
+
+func TestBPFFilter(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		name           string
+		scanRange      *scan.Range
+		expectedFilter string
+	}{
+		{
+			name:           "EmptySubnet",
+			expectedFilter: "icmp",
+			scanRange:      &scan.Range{},
+		},
+		{
+			name: "OneSubnet",
+			scanRange: &scan.Range{
+				DstSubnet: &net.IPNet{
+					IP:   net.IPv4(192, 168, 0, 0),
+					Mask: net.CIDRMask(24, 32),
+				},
+			},
+			expectedFilter: "icmp and ip src net 192.168.0.0/24",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			filter, maxPacketLength := BPFFilter(tt.scanRange)
+			assert.Equal(t, tt.expectedFilter, filter)
+			assert.Equal(t, maxPacketLength, MaxPacketLength)
+		})
+	}
+}

pkg/scan/icmp/icmp.go

@@ -0,0 +1,6 @@
+package icmp
+
+type Response struct {
+	Type uint8
+	Code uint8
+}