Dialtone

AOL 3.x Protocol Server

Dialtone is a modern, from-scratch implementation of the AOL 3.x protocol stack.
It speaks the classic P3 wire protocol, implements token routing, FDO (Form Definition Objects), XFER, DOD (Data on Demand), and session control --- allowing vintage AOL clients to connect to a fully open, modern server implementation.

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Table of Contents

• Project Goals
• Protocol Stack Overview
• Implemented Subsystems
• Architecture
• Wire-Level Compatibility
• Authentication & Session Model
• Web Management Layer
• Build & Run
• Configuration
• Docker Deployment
• Testing Strategy
• Development Philosophy
• License

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Project Goals

Dialtone exists to:

• Reconstruct the AOL 3.x server-side protocol stack
• Achieve wire-level compatibility with classic clients
• Preserve protocol behavior including sliding window flow control
• Modernize infrastructure without altering legacy semantics
• Open-source a previously opaque ecosystem

This project emphasizes correctness at the packet boundary level.

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Protocol Stack Overview

Dialtone implements the following layered architecture:

TCP Socket
    ↓
P3 Framing Layer
    ↓
Token Dispatcher
    ↓
Atomizer / FDO Engine
    ↓
Application Tools (XFER, DOD, IM, etc.)

P3 (Packet Protocol 3)

• Fixed header framing
• CRC-16 validation
• Sliding window (max 16 outstanding packets)
• Sequence number wrap (0x10--0x7F range)
• Implicit ACK via RXseq field
• Explicit ACK / NAK / HEARTBEAT support
• INIT handshake logic

The P3 implementation mirrors WAOL semantics, including:

• Direction bit masking
• Control packet non-consumption of sequence numbers
• Burst flow control behavior

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Implemented Subsystems

FDO (Form Definition Objects)

• Dynamic UI rendering
• Atom stream parsing
• Object graph construction
• Nested stream management
• Proper handling of 8 encoding styles

XFER

• Client → server upload
• Server → client download
• Thumbnail prelude handling
• Escape-based encoding (DL_ESC / DL_XOR)
• Optional RLE support
• Burst throttling (8-packet transmission window)
• Proper fX completion signaling

DOD (Download on Demand)

• Hints-first model
• Big-endian width/height encoding
• Multi-form focus prioritization
• Transaction ID correlation
• Progressive streaming semantics

Messaging

• Instant messaging (real-time)
• Multi-user chat rooms
• Session tracking
• Presence updates

Session Control

• LO logout handling
• TOKEN_DSTAR clean disconnect
• TOKEN_XS force-off with message
• Proper state transitions and teardown

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Architecture

Dialtone runs two servers inside a single JVM:

1. AOL Protocol Server (Port 5191)

• Netty-based TCP implementation
• Binary P3 framing
• Token parsing and dispatch
• Atom compilation/decompilation
• Tool subsystem routing

2. Web Management Server (Port 5200)

• Javalin HTTP server
• React SPA frontend
• OAuth login support
• User administration
• API endpoints for automation

Shared SQLite database using HikariCP connection pooling.

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Wire-Level Compatibility

Dialtone maintains compatibility at the following layers:

Layer Compatibility Target

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P3 framing Byte-for-byte behavior Sequence control Identical wrap semantics Token ordering Preserved Atom encoding ADA32-compatible DOD hints Endianness-accurate XFER block markers 'b', 'd', 'e' honored

The implementation does not approximate --- it mirrors.

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Authentication & Session Model

• JWT-based web sessions
• OAuth login (X and Discord)
• Email magic link support
• Ephemeral guest sessions
• Clean logout and forced disconnect handling

All AOL client authentication flows pass through P3 token exchange and stateful session binding.

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Web Management Layer

The management interface provides:

• Account creation
• OAuth linking
• Session visibility
• Moderation tools
• Administrative messaging

Designed to coexist with legacy client protocol without modifying it.

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Build & Run

Requirements

• Java 21+
• Maven 3.x
• GitHub Packages access (for atomforge-fdo-java)

Setup

git clone https://github.com/iconidentify/dialtone.git
cd dialtone

cp application.properties.example src/main/resources/application.properties
# Configure credentials

mvn clean package
java -jar target/dialtone-1.0-SNAPSHOT.jar

Default ports:

• 5191 -- AOL protocol server
• 5200 -- Web interface

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Configuration

Located at:

src/main/resources/application.properties

Required

Setting Purpose

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jwt.secret 32+ character HMAC key x.oauth.client.id OAuth client ID x.oauth.client.secret OAuth client secret

Optional

Setting Purpose

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grok.api.key AI chatbot integration discord.oauth.* Discord OAuth email.resend.api.key Magic link authentication

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CI profile includes:

• Increased property-based testing iterations
• Coverage enforcement
• Protocol boundary validation

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License

MIT License.

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Dialtone is a preservation project, a research project, and a production-grade server implementation.