ACDS Server

🌐 Discovery server TCP connection manager

🌐 Discovery server TCP connection manager

Server-side ACIP (ascii-chat IP Protocol) utilities for:

• Packet validation and parsing
• Protocol compliance checking
• Error response generation
• Common server-side packet handling

ACDS Server Protocol

Server Role in ACIP

The ACDS (ascii-chat Discovery Service) server orchestrates:

1. Session Management: Creating, joining, leaving sessions
2. Credential Verification: Password/identity authentication
3. Connection Brokerage: Revealing host IP only to authenticated clients
4. WebRTC Coordination: Relaying SDP and ICE candidates
5. Participant Tracking: Maintaining session roster and state

Packet Processing Flow

1. Receive: acip_transport_recv() reads packet from socket
2. Validate: Verify packet header (magic, CRC32, length)
3. Dispatch: Route to appropriate handler (session, webrtc, etc.)
4. Process: Handler executes business logic
5. Respond: Send response packet back to client

Security Features

• Identity Verification: Ed25519 digital signatures (replay-protected with timestamps)
• Password Auth: Argon2id hashing (resistant to brute-force)
• IP Privacy: Host IP only revealed after authentication
• CRC32 Validation: Detect payload corruption
• Timestamp Validation: Prevent replay attacks (5-minute window)

Session Database

• Storage: SQLite (persistent across restarts)
• Schema: session_id (UUID) → session_info (metadata, expiration)
• Expiration: Sessions expire after 24 hours
• Cleanup: Automatic garbage collection of expired sessions

Packet Type Reference (Server Perspective)

• Inbound: SESSION_CREATE, SESSION_LOOKUP, SESSION_JOIN, SESSION_LEAVE, WEBRTC_SDP, WEBRTC_ICE
• Outbound: SESSION_CREATED, SESSION_INFO, SESSION_JOINED, SESSION_END, PARTICIPANT_JOINED, PARTICIPANT_LEFT
• Broadcast: PARTICIPANT_* notifications to all session members

ACIP Protocol Overview:

• Binary TCP protocol (not HTTP/JSON)
• Packet-based with CRC32 validation
• Ed25519 identity signatures for authentication
• Session management and WebRTC signaling

Primary Use Case: Library functions for building ACIP servers (like ACDS - ascii-chat Discovery Service). Provides reusable validation and packet handling logic that any ACIP server implementation can use.

Integration:

• Used by src/acds/ ACDS server implementation
• Can be used by custom ACIP server implementations
• Complements network/acip/acds_client.h (client-side protocol)

Note

This module provides library-level utilities. The ACDS server application code is in src/acds/.

See also

network/acip/acds_client.h for client-side ACIP library

network/acip/acds.h for ACDS message structures

network/acip/protocol.h for ACIP Packet Types types

network/acip/transport.h for transport abstraction layer

Author

Zachary Fogg me@zf.nosp@m.o.gg

Date

January 2026

Version

1.0 (ACDS Server API)