Module relay 

TURN-style relay protocol for NAT traversal fallback TURN-style Relay Protocol Implementation

This module implements a TURN-style relay protocol for NAT traversal fallback when direct peer-to-peer connections cannot be established. The relay system provides a fallback mechanism to ensure connectivity between peers through trusted relay servers.

Protocol Overview

The relay protocol uses QUIC extension frames for communication:

• RELAY_REQUEST (0x44): Request relay connection establishment
• RELAY_RESPONSE (0x45): Response to relay request with status
• RELAY_DATA (0x46): Bidirectional data forwarding through relay

Security

All relay operations use Ed25519 cryptographic authentication with anti-replay protection. Rate limiting prevents abuse and ensures fair resource allocation among clients.

Re-exports

pub use authenticator::AuthToken;

pub use authenticator::RelayAuthenticator;

pub use connection::RelayAction;

pub use connection::RelayConnection;

pub use connection::RelayConnectionConfig;

pub use connection::RelayEvent;

pub use error::RelayError;

pub use error::RelayResult;

pub use rate_limiter::RateLimiter;

pub use rate_limiter::TokenBucket;

pub use session_manager::RelaySessionInfo;

pub use session_manager::SessionConfig;

pub use session_manager::SessionId;

pub use session_manager::SessionManager;

pub use session_manager::SessionManagerStats;

pub use session_manager::SessionState;

pub use statistics::RelayStatisticsCollector;

Modules

authenticator

Ed25519-based authentication for relay operations with anti-replay protection.

connection

Relay connection implementation for bidirectional data forwarding.

error

Error types for the relay protocol implementation.

rate_limiter

Token bucket rate limiting implementation for relay operations.

session_manager

Session management for relay connections with complete state machine.

statistics

Comprehensive relay statistics collection and aggregation.

Structs

AuthenticationStatistics

Authentication and security statistics

ConnectionStatistics

Connection-level statistics

ErrorStatistics

Error and failure statistics

RateLimitingStatistics

Rate limiting statistics

RelayStatistics

Comprehensive relay statistics combining all relay operations

SessionStatistics

Session management statistics

Constants

ANTI_REPLAY_WINDOW_SIZE

Anti-replay window size for authentication tokens

DEFAULT_BANDWIDTH_LIMIT

Default bandwidth limit per session (1 MB/s)

DEFAULT_SESSION_TIMEOUT

Default relay session timeout (5 minutes)

MAX_CONCURRENT_SESSIONS

Maximum number of concurrent relay sessions per client

MAX_RELAY_DATA_SIZE

Maximum size of relay data frame payload (64 KB)

RATE_LIMIT_BURST_SIZE

Rate limiting: maximum burst size (500 tokens)

RATE_LIMIT_TOKENS_PER_SECOND

Rate limiting: tokens per second (100 requests/second)

SESSION_CLEANUP_INTERVAL

Session cleanup interval (check every 30 seconds)