Module datatype 

Data types for the Tor relay protocol.

This module provides low-level data types used in ORPort communication with Tor relays. These types handle the binary encoding and decoding of protocol messages as defined in the Tor specification.

Overview

The module contains several categories of types:

• Size types: Size for packing/unpacking integers of various widths
• Protocol versioning: LinkProtocol for version-dependent constants
• Addressing: Address, AddrType, and LinkSpecifier for relay addresses
• Certificates: Certificate and CertType for relay certificates
• Commands: RelayCommand and CloseReason for circuit operations
• Key derivation: KDF for cryptographic key material

Conceptual Role

These types form the foundation of the ORPort protocol implementation. They handle the serialization and deserialization of binary data according to Tor’s wire format, which uses big-endian byte ordering throughout.

Most users should interact with the higher-level Relay and RelayCircuit types rather than using these primitives directly.

Wire Format

All multi-byte integers are encoded in network byte order (big-endian). Variable-length fields are typically prefixed with their length.

Example

use stem_rs::client::datatype::{Size, Address, AddrType};

// Pack and unpack integers
let packed = Size::Short.pack(9001);
assert_eq!(packed, vec![0x23, 0x29]);

let unpacked = Size::Short.unpack(&packed).unwrap();
assert_eq!(unpacked, 9001);

// Parse an IPv4 address
let addr = Address::new("127.0.0.1").unwrap();
assert_eq!(addr.addr_type, AddrType::IPv4);

Security Considerations

These types handle untrusted network data. All parsing functions validate input lengths and return errors for malformed data rather than panicking.

See Also

• cell - Cell types that use these data types for encoding
• Relay - High-level relay connection interface
• RelayCircuit - Circuit management using these primitives

Structs

Address

A relay address with type information.

Certificate

A relay certificate as defined in tor-spec section 4.2.

KDF

KDF-TOR derived key material.

LinkProtocol

Link protocol version with version-dependent constants.

Enums

AddrType

Address type identifier for relay addresses.

CertType

Certificate type identifier.

CloseReason

Reason for closing a circuit or stream.

LinkSpecifier

Method of communicating with a relay in a circuit.

RelayCommand

Relay cell command types.

Size

Integer size types for packing and unpacking binary data.

Constants

HASH_LEN

Length of SHA-1 hash output in bytes (160 bits).

KEY_LEN

Length of symmetric encryption keys in bytes (128 bits).

ZERO

Null byte constant used for padding in the Tor protocol.

Functions

split

Splits a byte slice at the given position, clamping to the slice length.