erlang_quic Features

Core Protocol (RFC 9000)

Connection Management

• [x] Connection establishment with TLS 1.3 handshake
• [x] Connection close (immediate and draining states)
• [x] Idle timeout enforcement (configurable via idle_timeout option)
• [x] Version negotiation
• [x] Retry packets for address validation

Streams

• [x] Bidirectional streams (client and server initiated)
• [x] Unidirectional streams
• [x] Stream prioritization (RFC 9218) with 8 urgency levels
• [x] Incremental delivery flag support

Flow Control

• [x] Connection-level flow control (MAX_DATA)
• [x] Stream-level flow control (MAX_STREAM_DATA)
• [x] MAX_STREAMS limits (bidirectional and unidirectional)

Packet Handling

• [x] Initial, Handshake, and 1-RTT packet types
• [x] Short header (1-RTT) packets
• [x] Packet number encoding (1-4 bytes)
• [x] Packet number reconstruction per RFC 9000 Appendix A
• [x] Coalesced packets
• [x] Frame coalescing (ACK + small stream data in single packet)

Connection Migration (RFC 9000 Section 9)

• [x] PATH_CHALLENGE / PATH_RESPONSE validation
• [x] Active connection migration (quic:migrate/1, quic:migrate/2)
• [x] Preferred address handling (RFC 9000 Section 9.6)
• [x] Server-side address change detection (NAT rebinding and active migration)
• [x] Congestion control reset on path change (RFC 9002 Section 9.4)
• [x] CID rotation on migration for path unlinkability (RFC 9000 Section 9.5)
• [x] disable_active_migration transport parameter support
• [x] Path validation timeout with retry (3 * PTO, up to 3 attempts)

Connection ID Management

• [x] Multiple connection IDs
• [x] NEW_CONNECTION_ID frames
• [x] RETIRE_CONNECTION_ID frames
• [x] Active connection ID limit

Loss Detection & Congestion Control (RFC 9002)

Loss Detection

• [x] Packet loss detection
• [x] Probe timeout (PTO)
• [x] RTT measurement (smoothed RTT, RTT variance)

Congestion Control

• [x] Pluggable congestion control behavior
• [x] NewReno (default, RFC 9002)
• [x] CUBIC (RFC 9438)
• [x] BBR (Bottleneck Bandwidth and RTT)
• [x] HyStart++ slow start (RFC 9406) for all algorithms
• [x] Slow start with improved exit detection
• [x] Congestion avoidance
• [x] Recovery on packet loss
• [x] Persistent congestion detection (resets cwnd after PTO * 3)
• [x] ECN support (ECN-CE triggers congestion response)
• [x] Packet pacing (RFC 9002 Section 7.7) to prevent bursts
• [x] RTT-based flow control auto-tuning

Path MTU Discovery (RFC 8899 - DPLPMTUD)

• [x] Binary search probing for optimal MTU
• [x] Integration with peer's max_udp_payload_size transport parameter
• [x] Black hole detection and recovery
• [x] Automatic MTU reset on connection migration
• [x] Periodic re-probing for MTU increases
• [x] Congestion control integration (updates cwnd-related parameters)

TLS 1.3 Integration (RFC 9001)

Handshake

• [x] Full TLS 1.3 handshake
• [x] ALPN negotiation
• [x] Transport parameters exchange
• [x] Certificate verification

Encryption

• [x] AES-128-GCM cipher suite
• [x] AES-256-GCM cipher suite
• [x] ChaCha20-Poly1305 cipher suite
• [x] Header protection
• [x] Key derivation (HKDF)

Key Management

• [x] Initial secrets derivation
• [x] Handshake secrets
• [x] Application secrets
• [x] Key updates (RFC 9001 Section 6)

Session Resumption

• [x] Session tickets (NewSessionTicket)
• [x] PSK-based resumption
• [x] 0-RTT early data

QUIC Version 2 (RFC 9369)

• [x] Version 2 (0x6b3343cf) support
• [x] Updated initial salt
• [x] Updated retry integrity tag key

QUIC-LB Load Balancer Support (RFC 9312)

• [x] Server ID encoding in Connection IDs for LB routing
• [x] Config rotation bits for LB coordination
• [x] Variable CID length support (1-20 bytes)
• [x] Three encoding algorithms:
  • Plaintext: Server ID visible in CID (no encryption)
  • Stream Cipher: AES-128-CTR encryption
  • Block Cipher: Feistel network for variable lengths
• [x] LB-aware CID generation in listener and connection

API

Connection

• quic:connect/3,4 - Connect to server
• quic:close/1,2,3 - Close connection (with optional app error code)
• quic:peername/1 - Get peer address
• quic:sockname/1 - Get local address
• quic:peercert/1 - Get peer certificate
• quic:migrate/1,2 - Trigger connection migration (with optional timeout)

Datagrams (RFC 9221)

• quic:send_datagram/2 - Send unreliable datagram
• quic:datagram_max_size/1 - Get max datagram size (0 if unsupported)

Streams

• quic:open_stream/1 - Open bidirectional stream
• quic:open_unidirectional_stream/1 - Open unidirectional stream
• quic:send/3,4 - Send data on stream
• quic:close_stream/2,3 - Close stream
• quic:set_stream_priority/4 - Set stream priority (urgency, incremental)
• quic:get_stream_priority/2 - Get stream priority

Server

• quic:listen/2 - Start listener
• quic:accept/1,2 - Accept connection
• quic:close_listener/1 - Close listener

Multi-Pool Server Management

• quic:start_server/3 - Start named server pool
• quic:stop_server/1 - Stop named server
• quic:get_server_info/1 - Get server information
• quic:get_server_port/1 - Get server listening port
• quic:get_server_connections/1 - Get server connection PIDs
• quic:which_servers/0 - List all running servers

Load Balancer (RFC 9312)

• quic_lb:new_config/1 - Create LB configuration from options map
• quic_lb:new_cid_config/1 - Create CID generation configuration
• quic_lb:generate_cid/1 - Generate CID with encoded server_id
• quic_lb:decode_server_id/2 - Extract server_id from CID
• quic_lb:is_lb_routable/1 - Check if CID has valid LB routing bits
• quic_lb:get_config_rotation/1 - Get config rotation bits from CID
• quic_lb:expected_cid_len/1 - Calculate expected CID length from config

Options

• idle_timeout - Connection idle timeout in milliseconds (0 to disable)
• max_data - Connection-level flow control limit
• max_stream_data - Stream-level flow control limit
• max_datagram_frame_size - Max datagram size to accept (0 = disabled, default: 0)
• alpn - ALPN protocols list
• verify - Certificate verification mode
• preferred_ipv4 - Server preferred IPv4 address
• preferred_ipv6 - Server preferred IPv6 address
• pool_size - Number of listener processes for server pools (default: 1)
• connection_handler - Callback for handling new connections
• lb_config - QUIC-LB configuration map for load balancer routing
• keep_alive_interval - Keep-alive PING interval (disabled, auto, or milliseconds)
• pmtu_enabled - Enable Path MTU Discovery (default: true)
• pmtu_max_mtu - Maximum MTU to probe (default: 1500)
• recbuf - UDP receive buffer size in bytes (default: 7MB)
• sndbuf - UDP send buffer size in bytes (default: 7MB)

PMTU Discovery

• quic:get_mtu/1 - Get current effective MTU for a connection

Erlang Distribution (quic_dist)

QUIC-based Erlang distribution protocol implementation.

Features

• [x] Full distribution protocol over QUIC transport
• [x] TLS 1.3 encryption built-in (no separate SSL setup)
• [x] 0-RTT session resumption for fast reconnection
• [x] Multiple streams: control (urgency 0) + data (urgency 4-6)
• [x] Stream prioritization for tick/control messages
• [x] QUIC-level liveness detection (packet counts, not blocked by flow control)
• [x] Keep-alive PING frames for transport liveness
• [x] Backpressure mechanism for congestion control
• [x] Session ticket storage for 0-RTT

Modules

• quic_dist - Distribution protocol callbacks
• quic_dist_controller - Per-connection state machine
• quic_dist_sup - Distribution supervisor
• quic_dist_tickets - Session ticket storage
• quic_epmd - EPMD replacement module

Discovery Backends

• quic_discovery_static - Static node configuration
• quic_discovery_dns - DNS SRV-based discovery
• Custom backends via quic_discovery behaviour

Distribution API

• quic:get_stats/1 - Get packet counts for liveness detection
• quic:send_ping/1 - Send transport-level PING frame

Interop Runner Compliance

All 10 QUIC Interop Runner test cases pass: