go-p2p/specs/node-levin.md

levin

Import: dappco.re/go/core/p2p/node/levin

Files: 4

Types

Connection

type Connection struct {
	MaxPayloadSize uint64
	ReadTimeout    time.Duration
	WriteTimeout   time.Duration
}

Wrapper around net.Conn that reads and writes framed Levin packets.

• MaxPayloadSize: per-connection payload ceiling enforced by ReadPacket. NewConnection starts with the package MaxPayloadSize default.
• ReadTimeout: deadline applied before each ReadPacket call. NewConnection sets this to DefaultReadTimeout.
• WriteTimeout: deadline applied before each write. NewConnection sets this to DefaultWriteTimeout.

Header

type Header struct {
	Signature       uint64
	PayloadSize     uint64
	ExpectResponse  bool
	Command         uint32
	ReturnCode      int32
	Flags           uint32
	ProtocolVersion uint32
}

Packed 33-byte Levin frame header. EncodeHeader writes these fields little-endian, and DecodeHeader validates the Signature and package-level MaxPayloadSize.

Section

type Section map[string]Value

Portable-storage object used by the Levin encoder and decoder. EncodeStorage sorts keys alphabetically for deterministic output.

Value

type Value struct {
	Type uint8
}

Tagged portable-storage value. The exported Type field identifies which internal scalar or array slot is populated; constructors such as Uint64Value, StringValue, and ObjectArrayValue create correctly-typed instances.

Functions

Top-level framing and storage functions

Name	Signature	Description
NewConnection	func NewConnection(conn net.Conn) *Connection	Wraps conn with Levin defaults: 100 MB payload limit, 120 s read timeout, and 30 s write timeout.
EncodeHeader	func EncodeHeader(h *Header) [HeaderSize]byte	Serialises h into the fixed 33-byte Levin header format.
DecodeHeader	func DecodeHeader(buf [HeaderSize]byte) (Header, error)	Parses a 33-byte header, rejecting bad magic signatures and payload sizes above the package-level limit.
PackVarint	func PackVarint(v uint64) []byte	Encodes v using the epee portable-storage varint scheme where the low two bits of the first byte encode the width.
UnpackVarint	func UnpackVarint(buf []byte) (value uint64, bytesConsumed int, err error)	Decodes one portable-storage varint and returns the value, consumed width, and any truncation or overflow error.
EncodeStorage	func EncodeStorage(s Section) ([]byte, error)	Serialises a Section into portable-storage binary form, including the 9-byte storage header.
DecodeStorage	func DecodeStorage(data []byte) (Section, error)	Deserialises portable-storage binary data, validates the storage signatures and version, and reconstructs a Section.

Value constructors

Name	Signature	Description
Uint64Value	func Uint64Value(v uint64) Value	Creates a scalar Value with TypeUint64.
Uint32Value	func Uint32Value(v uint32) Value	Creates a scalar Value with TypeUint32.
Uint16Value	func Uint16Value(v uint16) Value	Creates a scalar Value with TypeUint16.
Uint8Value	func Uint8Value(v uint8) Value	Creates a scalar Value with TypeUint8.
Int64Value	func Int64Value(v int64) Value	Creates a scalar Value with TypeInt64.
Int32Value	func Int32Value(v int32) Value	Creates a scalar Value with TypeInt32.
Int16Value	func Int16Value(v int16) Value	Creates a scalar Value with TypeInt16.
Int8Value	func Int8Value(v int8) Value	Creates a scalar Value with TypeInt8.
BoolValue	func BoolValue(v bool) Value	Creates a scalar Value with TypeBool.
DoubleValue	func DoubleValue(v float64) Value	Creates a scalar Value with TypeDouble.
StringValue	func StringValue(v []byte) Value	Creates a scalar Value with TypeString. The byte slice is stored without copying.
ObjectValue	func ObjectValue(s Section) Value	Creates a scalar Value with TypeObject that wraps a nested Section.
Uint64ArrayValue	func Uint64ArrayValue(vs []uint64) Value	Creates an array Value tagged as `ArrayFlag
Uint32ArrayValue	func Uint32ArrayValue(vs []uint32) Value	Creates an array Value tagged as `ArrayFlag
StringArrayValue	func StringArrayValue(vs [][]byte) Value	Creates an array Value tagged as `ArrayFlag
ObjectArrayValue	func ObjectArrayValue(vs []Section) Value	Creates an array Value tagged as `ArrayFlag

*Connection methods

Name	Signature	Description
WritePacket	func (c *Connection) WritePacket(cmd uint32, payload []byte, expectResponse bool) error	Sends a Levin request or notification with FlagRequest, ReturnOK, and the current protocol version. Header and payload writes are serialised by an internal mutex.
WriteResponse	func (c *Connection) WriteResponse(cmd uint32, payload []byte, returnCode int32) error	Sends a Levin response with FlagResponse and the supplied return code.
ReadPacket	func (c *Connection) ReadPacket() (Header, []byte, error)	Applies the read deadline, reads exactly one header and payload, validates the frame, and enforces the connection-specific MaxPayloadSize. Empty payloads are returned as nil without allocation.
Close	func (c *Connection) Close() error	Closes the wrapped network connection.
RemoteAddr	func (c *Connection) RemoteAddr() string	Returns the wrapped connection's remote address string.

Value methods

Name	Signature	Description
AsUint64	func (v Value) AsUint64() (uint64, error)	Returns the scalar uint64 value or ErrStorageTypeMismatch.
AsUint32	func (v Value) AsUint32() (uint32, error)	Returns the scalar uint32 value or ErrStorageTypeMismatch.
AsUint16	func (v Value) AsUint16() (uint16, error)	Returns the scalar uint16 value or ErrStorageTypeMismatch.
AsUint8	func (v Value) AsUint8() (uint8, error)	Returns the scalar uint8 value or ErrStorageTypeMismatch.
AsInt64	func (v Value) AsInt64() (int64, error)	Returns the scalar int64 value or ErrStorageTypeMismatch.
AsInt32	func (v Value) AsInt32() (int32, error)	Returns the scalar int32 value or ErrStorageTypeMismatch.
AsInt16	func (v Value) AsInt16() (int16, error)	Returns the scalar int16 value or ErrStorageTypeMismatch.
AsInt8	func (v Value) AsInt8() (int8, error)	Returns the scalar int8 value or ErrStorageTypeMismatch.
AsBool	func (v Value) AsBool() (bool, error)	Returns the scalar bool value or ErrStorageTypeMismatch.
AsDouble	func (v Value) AsDouble() (float64, error)	Returns the scalar float64 value or ErrStorageTypeMismatch.
AsString	func (v Value) AsString() ([]byte, error)	Returns the scalar byte-string or ErrStorageTypeMismatch.
AsSection	func (v Value) AsSection() (Section, error)	Returns the nested Section or ErrStorageTypeMismatch.
AsUint64Array	func (v Value) AsUint64Array() ([]uint64, error)	Returns the []uint64 array or ErrStorageTypeMismatch.
AsUint32Array	func (v Value) AsUint32Array() ([]uint32, error)	Returns the []uint32 array or ErrStorageTypeMismatch.
AsStringArray	func (v Value) AsStringArray() ([][]byte, error)	Returns the [][]byte array or ErrStorageTypeMismatch.
AsSectionArray	func (v Value) AsSectionArray() ([]Section, error)	Returns the []Section array or ErrStorageTypeMismatch.