Fixed code smells

protocol/meshtastic/node.go

@@ -0,0 +1,173 @@
+package meshtastic
+
+import (
+	"crypto/rand"
+	"encoding/binary"
+	"fmt"
+	"math"
+	"math/big"
+	"strconv"
+	"strings"
+)
+
+type NodeID uint32
+
+const (
+	// BroadcastNodeID is the special NodeID used when broadcasting a packet to a channel.
+	BroadcastNodeID NodeID = math.MaxUint32
+
+	// BroadcastNodeIDNoLora is a special broadcast address that excludes LoRa transmission.
+	// Used for MQTT-only broadcasts. This is ^all with the NO_LORA flag (0x40) cleared.
+	BroadcastNodeIDNoLora NodeID = math.MaxUint32 ^ 0x40
+
+	// ReservedNodeIDThreshold is the threshold at which NodeIDs are considered reserved. Random NodeIDs should not
+	// be generated below this threshold.
+	// Source: https://github.com/meshtastic/firmware/blob/d1ea58975755e146457a8345065e4ca357555275/src/mesh/NodeDB.cpp#L461
+	reservedNodeIDThreshold NodeID = 4
+)
+
+// ParseNodeID parses a NodeID from various string formats:
+//   - "!abcd1234" (Meshtastic format with ! prefix)
+//   - "0xabcd1234" (hex with 0x prefix)
+//   - "abcd1234" (plain hex)
+//   - "12345678" (decimal)
+func ParseNodeID(s string) (NodeID, error) {
+	s = strings.TrimSpace(s)
+	if s == "" {
+		return 0, fmt.Errorf("empty node ID string")
+	}
+
+	// Handle !prefix format
+	if strings.HasPrefix(s, "!") {
+		s = s[1:]
+		n, err := strconv.ParseUint(s, 16, 32)
+		if err != nil {
+			return 0, fmt.Errorf("invalid node ID %q: %w", s, err)
+		}
+		return NodeID(n), nil
+	}
+
+	// Handle 0x prefix
+	if strings.HasPrefix(s, "0x") || strings.HasPrefix(s, "0X") {
+		n, err := strconv.ParseUint(s[2:], 16, 32)
+		if err != nil {
+			return 0, fmt.Errorf("invalid node ID %q: %w", s, err)
+		}
+		return NodeID(n), nil
+	}
+
+	// Try hex first if it looks like hex (contains a-f)
+	sLower := strings.ToLower(s)
+	if strings.ContainsAny(sLower, "abcdef") {
+		n, err := strconv.ParseUint(s, 16, 32)
+		if err != nil {
+			return 0, fmt.Errorf("invalid node ID %q: %w", s, err)
+		}
+		return NodeID(n), nil
+	}
+
+	// Try decimal
+	n, err := strconv.ParseUint(s, 10, 32)
+	if err != nil {
+		// Fall back to hex for 8-char strings
+		if len(s) == 8 {
+			n, err = strconv.ParseUint(s, 16, 32)
+			if err != nil {
+				return 0, fmt.Errorf("invalid node ID %q: %w", s, err)
+			}
+			return NodeID(n), nil
+		}
+		return 0, fmt.Errorf("invalid node ID %q: %w", s, err)
+	}
+	return NodeID(n), nil
+}
+
+// Uint32 returns the underlying uint32 value of the NodeID.
+func (n NodeID) Uint32() uint32 {
+	return uint32(n)
+}
+
+// String converts the NodeID to a hex formatted string.
+// This is typically how NodeIDs are displayed in Meshtastic UIs.
+func (n NodeID) String() string {
+	return fmt.Sprintf("!%08x", uint32(n))
+}
+
+// Bytes converts the NodeID to a byte slice
+func (n NodeID) Bytes() []byte {
+	bytes := make([]byte, 4) // uint32 is 4 bytes
+	binary.BigEndian.PutUint32(bytes, n.Uint32())
+	return bytes
+}
+
+// DefaultLongName returns the default long node name based on the NodeID.
+// Source: https://github.com/meshtastic/firmware/blob/d1ea58975755e146457a8345065e4ca357555275/src/mesh/NodeDB.cpp#L382
+func (n NodeID) DefaultLongName() string {
+	bytes := make([]byte, 4) // uint32 is 4 bytes
+	binary.BigEndian.PutUint32(bytes, n.Uint32())
+	return fmt.Sprintf("Meshtastic %04x", bytes[2:])
+}
+
+// DefaultShortName returns the default short node name based on the NodeID.
+// Last two bytes of the NodeID represented in hex.
+// Source: https://github.com/meshtastic/firmware/blob/d1ea58975755e146457a8345065e4ca357555275/src/mesh/NodeDB.cpp#L382
+func (n NodeID) DefaultShortName() string {
+	bytes := make([]byte, 4) // uint32 is 4 bytes
+	binary.BigEndian.PutUint32(bytes, n.Uint32())
+	return fmt.Sprintf("%04x", bytes[2:])
+}
+
+// UnmarshalText implements encoding.TextUnmarshaler for use with config parsers like Viper.
+func (n *NodeID) UnmarshalText(text []byte) error {
+	parsed, err := ParseNodeID(string(text))
+	if err != nil {
+		return err
+	}
+	*n = parsed
+	return nil
+}
+
+// MarshalText implements encoding.TextMarshaler.
+func (n NodeID) MarshalText() ([]byte, error) {
+	return []byte(n.String()), nil
+}
+
+// IsReservedID returns true if this is a reserved or broadcast NodeID.
+func (n NodeID) IsReservedID() bool {
+	return n < reservedNodeIDThreshold || n >= BroadcastNodeIDNoLora
+}
+
+// IsBroadcast returns true if this is any form of broadcast address.
+func (n NodeID) IsBroadcast() bool {
+	return n == BroadcastNodeID || n == BroadcastNodeIDNoLora
+}
+
+// ToMacAddress returns a MAC address string derived from the NodeID.
+// This creates a locally administered unicast MAC address.
+func (n NodeID) ToMacAddress() string {
+	bytes := n.Bytes()
+	// Use 0x02 as the first octet (locally administered, unicast)
+	// Then 0x00 as padding, followed by the 4 bytes of the NodeID
+	return fmt.Sprintf("02:00:%02x:%02x:%02x:%02x", bytes[0], bytes[1], bytes[2], bytes[3])
+}
+
+// RandomNodeID returns a randomised NodeID.
+// It's recommended to call this the first time a node is started and persist the result.
+//
+// Hardware meshtastic nodes first try a NodeID of the last four bytes of the BLE MAC address. If that ID is already in
+// use or invalid, a random NodeID is generated.
+// Source: https://github.com/meshtastic/firmware/blob/d1ea58975755e146457a8345065e4ca357555275/src/mesh/NodeDB.cpp#L466
+func RandomNodeID() (NodeID, error) {
+	// Generates a random uint32 between reservedNodeIDThreshold and math.MaxUint32
+	randomInt, err := rand.Int(
+		rand.Reader,
+		big.NewInt(
+			int64(math.MaxUint32-reservedNodeIDThreshold.Uint32()),
+		),
+	)
+	if err != nil {
+		return NodeID(0), fmt.Errorf("reading entropy: %w", err)
+	}
+	r := uint32(randomInt.Uint64()) + reservedNodeIDThreshold.Uint32()
+	return NodeID(r), nil
+}

protocol/meshtastic/packet.go

@@ -0,0 +1,54 @@
+package meshtastic
+
+import (
+	"encoding/binary"
+	"errors"
+)
+
+const (
+	minPacketSize  = 4 + 4 + 4 + 1 + 1 + 1 + 1
+	maxPayloadSize = 237
+)
+
+var (
+	// ErrInvalidPacket signals the source buffer does not contain a valid packet.
+	ErrInvalidPacket = errors.New("meshtastic: invalid packet")
+)
+
+type Packet struct {
+	Destination   NodeID
+	Source        NodeID
+	ID            uint32
+	Flags         uint8
+	ChannelHash   uint8
+	NextHop       uint8
+	RelayNode     uint8
+	PayloadLength int
+	Payload       [maxPayloadSize]byte
+}
+
+func (packet *Packet) Decode(data []byte) error {
+	if len(data) < minPacketSize {
+		return ErrInvalidPacket
+	}
+
+	packet.Destination = parseNodeID(data[0:])
+	packet.Source = parseNodeID(data[4:])
+	packet.ID = binary.LittleEndian.Uint32(data[8:])
+	packet.Flags = data[12]
+	packet.ChannelHash = data[13]
+	packet.NextHop = data[14]
+	packet.RelayNode = data[15]
+	packet.PayloadLength = len(data[16:])
+	copy(packet.Payload[:], data[16:])
+
+	return nil
+}
+
+func (packet *Packet) HopLimit() int {
+	return
+}
+
+func parseNodeID(data []byte) NodeID {
+	return NodeID(binary.LittleEndian.Uint32(data))
+}