Add native protocol service plugins

plugins/services/modbus.go

@@ -0,0 +1,104 @@
+//go:build plugin_modbus || !plugin_selective
+
+package services
+
+import (
+	"context"
+	"encoding/binary"
+	"fmt"
+	"io"
+	"time"
+
+	"github.com/shadow1ng/fscan/common"
+	"github.com/shadow1ng/fscan/plugins"
+)
+
+type ModbusPlugin struct {
+	plugins.BasePlugin
+}
+
+func NewModbusPlugin() *ModbusPlugin {
+	return &ModbusPlugin{BasePlugin: plugins.NewBasePlugin("modbus")}
+}
+
+func (p *ModbusPlugin) Scan(ctx context.Context, info *common.HostInfo, session *common.ScanSession) *ScanResult {
+	timeout := session.Config.Timeout
+	if timeout <= 0 {
+		timeout = 3 * time.Second
+	}
+
+	addr := fmt.Sprintf("%s:%d", info.Host, info.Port)
+	conn, err := session.DialTCP(ctx, "tcp", addr, timeout)
+	if err != nil {
+		return &ScanResult{Success: false, Service: "modbus"}
+	}
+	defer conn.Close()
+
+	txID := randomUint16()
+	req := buildModbusDeviceIDRequest(txID)
+	_ = conn.SetDeadline(time.Now().Add(timeout))
+	if _, err := conn.Write(req); err != nil {
+		return &ScanResult{Success: false, Service: "modbus"}
+	}
+
+	header := make([]byte, 7)
+	if _, err := io.ReadFull(conn, header); err != nil {
+		return &ScanResult{Success: false, Service: "modbus"}
+	}
+	length := int(binary.BigEndian.Uint16(header[4:6]))
+	if length < 2 || length > 260 {
+		return &ScanResult{Success: false, Service: "modbus"}
+	}
+	body := make([]byte, length-1)
+	if _, err := io.ReadFull(conn, body); err != nil {
+		return &ScanResult{Success: false, Service: "modbus"}
+	}
+
+	banner, ok := parseModbusResponse(header, body, txID)
+	if !ok {
+		return &ScanResult{Success: false, Service: "modbus"}
+	}
+
+	return &ScanResult{
+		Success: true,
+		Type:    plugins.ResultTypeService,
+		Service: "modbus",
+		Banner:  banner,
+	}
+}
+
+func buildModbusDeviceIDRequest(txID uint16) []byte {
+	req := make([]byte, 11)
+	binary.BigEndian.PutUint16(req[0:2], txID)
+	binary.BigEndian.PutUint16(req[2:4], 0)
+	binary.BigEndian.PutUint16(req[4:6], 5)
+	req[6] = 0xff
+	req[7] = 0x2b
+	req[8] = 0x0e
+	req[9] = 0x01
+	req[10] = 0x00
+	return req
+}
+
+func parseModbusResponse(header, body []byte, txID uint16) (string, bool) {
+	if len(header) < 7 || len(body) < 1 {
+		return "", false
+	}
+	if binary.BigEndian.Uint16(header[0:2]) != txID || binary.BigEndian.Uint16(header[2:4]) != 0 {
+		return "", false
+	}
+	switch body[0] {
+	case 0x2b:
+		return "Modbus TCP device identification response", true
+	case 0xab:
+		return "Modbus TCP exception response", true
+	default:
+		return "", false
+	}
+}
+
+func init() {
+	RegisterPluginWithPorts("modbus", func() Plugin {
+		return NewModbusPlugin()
+	}, []int{502})
+}