Modbus proxy: make readonly ignore writes, add deny option (BC) (#10658)

cmd/root.go

@@ -179,7 +179,13 @@ func runRoot(cmd *cobra.Command, args []string) {
 	// setup modbus proxy
 	if err == nil {
 		for _, cfg := range conf.ModbusProxy {
-			if err = modbus.StartProxy(cfg.Port, cfg.Settings, cfg.ReadOnly); err != nil {
+			var mode modbus.ReadOnlyMode
+			mode, err = modbus.ReadOnlyModeString(cfg.ReadOnly)
+			if err != nil {
+				break
+			}
+
+			if err = modbus.StartProxy(cfg.Port, cfg.Settings, mode); err != nil {
 				break
 			}
 		}

cmd/setup.go

@@ -113,7 +113,7 @@ type goConfig struct {
 
 type proxyConfig struct {
 	Port            int
-	ReadOnly        bool
+	ReadOnly        string
 	modbus.Settings `mapstructure:",squash"`
 }
 

evcc.dist.yaml

@@ -49,7 +49,7 @@ modbusproxy:
   #  - port: 5200
   #    uri: solar-edge:502
   #    # rtu: true
-  #    # readonly: true
+  #    # readonly: true # use `deny` to raise modbus errors
 
 # meter definitions
 # name can be freely chosen and is used as reference when assigning meters to site and loadpoints

server/modbus/handler.go

@@ -13,7 +13,7 @@ import (
 
 type handler struct {
 	log      *util.Logger
-	readOnly bool
+	readOnly ReadOnlyMode
 	conn     *modbus.Connection
 }
 
@@ -104,8 +104,13 @@ func (h *handler) HandleDiscreteInputs(req *mbserver.DiscreteInputsRequest) ([]b
 
 func (h *handler) HandleCoils(req *mbserver.CoilsRequest) ([]bool, error) {
 	if req.IsWrite {
-		if h.readOnly {
+		switch h.readOnly {
+		case ReadOnlyDeny:
+			h.log.TRACE.Printf("deny: write coils: id %d addr %d qty %d val %v", req.UnitId, req.Addr, req.Quantity, req.Args)
 			return nil, mbserver.ErrIllegalFunction
+		case ReadOnlyTrue:
+			h.log.TRACE.Printf("ignore: write coils: id %d addr %d qty %d val %v", req.UnitId, req.Addr, req.Quantity, req.Args)
+			return req.Args, nil
 		}
 
 		if req.WriteFuncCode == gridx.FuncCodeWriteSingleCoil {
@@ -138,8 +143,13 @@ func (h *handler) HandleInputRegisters(req *mbserver.InputRegistersRequest) ([]u
 
 func (h *handler) HandleHoldingRegisters(req *mbserver.HoldingRegistersRequest) ([]uint16, error) {
 	if req.IsWrite {
-		if h.readOnly {
+		switch h.readOnly {
+		case ReadOnlyDeny:
+			h.log.TRACE.Printf("deny: write holdings: id %d addr %d qty %d val %0x", req.UnitId, req.Addr, req.Quantity, asBytes(req.Args))
 			return nil, mbserver.ErrIllegalFunction
+		case ReadOnlyTrue:
+			h.log.TRACE.Printf("ignore: write holdings: id %d addr %d qty %d val %0x", req.UnitId, req.Addr, req.Quantity, asBytes(req.Args))
+			return req.Args, nil
 		}
 
 		if req.WriteFuncCode == gridx.FuncCodeWriteSingleRegister {

server/modbus/proxy.go

@@ -11,7 +11,7 @@ import (
 	"github.com/evcc-io/evcc/util/sponsor"
 )
 
-func StartProxy(port int, config modbus.Settings, readOnly bool) error {
+func StartProxy(port int, config modbus.Settings, readOnly ReadOnlyMode) error {
 	conn, err := modbus.NewConnection(config.URI, config.Device, config.Comset, config.Baudrate, modbus.ProtocolFromRTU(config.RTU), config.ID)
 	if err != nil {
 		return err

server/modbus/readonlymode.go

@@ -0,0 +1,11 @@
+package modbus
+
+// go:generate enumer -type ReadOnlyMode -trimprefix ReadOnly -transform=lower
+
+type ReadOnlyMode int
+
+const (
+	ReadOnlyFalse ReadOnlyMode = iota
+	ReadOnlyDeny
+	ReadOnlyTrue
+)

server/modbus/readonlymode_enumer.go

@@ -0,0 +1,90 @@
+// Code generated by "enumer -type ReadOnlyMode -trimprefix ReadOnly -transform=lower"; DO NOT EDIT.
+
+package modbus
+
+import (
+	"fmt"
+	"strings"
+)
+
+const _ReadOnlyModeName = "falsedenytrue"
+
+var _ReadOnlyModeIndex = [...]uint8{0, 5, 9, 13}
+
+const _ReadOnlyModeLowerName = "falsedenytrue"
+
+func (i ReadOnlyMode) String() string {
+	if i < 0 || i >= ReadOnlyMode(len(_ReadOnlyModeIndex)-1) {
+		return fmt.Sprintf("ReadOnlyMode(%d)", i)
+	}
+	return _ReadOnlyModeName[_ReadOnlyModeIndex[i]:_ReadOnlyModeIndex[i+1]]
+}
+
+// An "invalid array index" compiler error signifies that the constant values have changed.
+// Re-run the stringer command to generate them again.
+func _ReadOnlyModeNoOp() {
+	var x [1]struct{}
+	_ = x[ReadOnlyFalse-(0)]
+	_ = x[ReadOnlyDeny-(1)]
+	_ = x[ReadOnlyTrue-(2)]
+}
+
+var _ReadOnlyModeValues = []ReadOnlyMode{ReadOnlyFalse, ReadOnlyDeny, ReadOnlyTrue}
+
+var _ReadOnlyModeNameToValueMap = map[string]ReadOnlyMode{
+	_ReadOnlyModeName[0:5]:       ReadOnlyFalse,
+	_ReadOnlyModeLowerName[0:5]:  ReadOnlyFalse,
+	_ReadOnlyModeName[5:9]:       ReadOnlyDeny,
+	_ReadOnlyModeLowerName[5:9]:  ReadOnlyDeny,
+	_ReadOnlyModeName[9:13]:      ReadOnlyTrue,
+	_ReadOnlyModeLowerName[9:13]: ReadOnlyTrue,
+}
+
+var _ReadOnlyModeNames = []string{
+	_ReadOnlyModeName[0:5],
+	_ReadOnlyModeName[5:9],
+	_ReadOnlyModeName[9:13],
+}
+
+// ReadOnlyModeString retrieves an enum value from the enum constants string name.
+// Throws an error if the param is not part of the enum.
+func ReadOnlyModeString(s string) (ReadOnlyMode, error) {
+	if val, ok := _ReadOnlyModeNameToValueMap[s]; ok {
+		return val, nil
+	}
+
+	if val, ok := _ReadOnlyModeNameToValueMap[strings.ToLower(s)]; ok {
+		return val, nil
+	}
+
+	switch s {
+	case "", "0":
+		return ReadOnlyFalse, nil
+	case "1":
+		return ReadOnlyTrue, nil
+	}
+
+	return 0, fmt.Errorf("%s does not belong to ReadOnlyMode values", s)
+}
+
+// ReadOnlyModeValues returns all values of the enum
+func ReadOnlyModeValues() []ReadOnlyMode {
+	return _ReadOnlyModeValues
+}
+
+// ReadOnlyModeStrings returns a slice of all String values of the enum
+func ReadOnlyModeStrings() []string {
+	strs := make([]string, len(_ReadOnlyModeNames))
+	copy(strs, _ReadOnlyModeNames)
+	return strs
+}
+
+// IsAReadOnlyMode returns "true" if the value is listed in the enum definition. "false" otherwise
+func (i ReadOnlyMode) IsAReadOnlyMode() bool {
+	for _, v := range _ReadOnlyModeValues {
+		if i == v {
+			return true
+		}
+	}
+	return false
+}