Hotsprings Protocol

Licensing

The Hotline Protocol is the property of Hotsprings Inc. and is licensed under the GPL. For closed-source development, a commercial license must be negotiated.

Protocol Overview

Hotline uses a client-server architecture facilitated by a Tracker application. All communication utilizes TCP/IP.

Port Assignments

The base port number is set manually. Related ports are derived as follows:

Port	Usage
Base port	Regular transactions
Base port + 1	Upload/download
Base port + 2	HTTP tunneling (transactions)
Base port + 3	HTTP tunneling (uploads/downloads)

Note: Numeric data is always in network byte order (big-endian).

Session Initialization

After TCP connection, a TRTP handshake occurs.

Client Request

Description	Size (Bytes)	Data	Note
Protocol ID	4	'TRTP'	0x54525450
Sub-protocol ID	4		User defined
Version	2	1	Currently 1
Sub-version	2		User defined

Server Reply

Description	Size (Bytes)	Data	Note
Protocol ID	4	'TRTP'
Error code	4		0 = no error

Transactions

Every transaction consists of a header followed by a parameter list.

Transaction Header

Description	Size	Note
Flags	1	Reserved (0)
Is reply	1	Request (0) or reply (1)
Type	2	Requested operation ID
ID	4	Unique ID (must be != 0)
Error code	4	0 = no error
Total size	4	Total transaction data size
Data size	4	Size of data in this part

Parameter Structure

A transaction contains a 2-byte field for the Number of parameters, followed by multiple structures:

Description	Size	Note
Field ID	2	Unique identifier
Field size	2	Data part size
Field data	Var	Actual content

Transaction Descriptions

Login (107)

• Constant: myTran_Login
• Initiator: Client

Request Fields:

• 105: User login
• 106: User password
• 160: Version (Currently 151)

Reply Fields:

• 160: Version
• 161/162: Banner ID/Server Name (if Version >= 151)

Send Chat (105)

• Access: Send Chat (10)
• Initiator: Client

Request Fields:

• 101: Chat message string
• 109: Chat options (Normal 0, Alternate 1)
• 114: Chat ID (Optional)

Disconnect User (110)

• Access: Disconnect User (22)
• Initiator: Client

Request Fields:

• 103: User ID
• 113: Options (Ban options)

Flattened File Object (FILP)

Used for file/folder transfers (Trans 202, 203, 210, 213).

Flat File Header

• Format: 'FILP' (0x46494C50)
• Fork Count: 2 (Information Fork and Data Fork)

Information Fork (INFO)

• Platform: 'AMAC' or 'MWIN'
• Metadata: Type signature, Creator signature, Create/Modify dates, Name.

Data Fork (DATA)

• Data Size: 4 bytes
• Content: Actual file bytes.

Transaction Fields

Predefined types: Integer, String, and Binary.

ID	Constant	Type	Note
101	myField_Data	Binary	General data
102	myField_UserName	String
103	myField_UserID	Integer
105	myField_UserLogin	String
106	myField_UserPassword	String
110	myField_UserAccess	Binary	64-bit bitmap
114	myField_ChatID	Integer
160	myField_Vers	Integer	Protocol version
202	myField_FilePath	Binary	File path structure

Access Privileges

Represented as a 64-bit bitmap in Field 110.

Bit	Name	Constant	Type
0	Delete File	myAcc_DeleteFile	folder
1	Upload File	myAcc_UploadFile	folder/general
9	Read Chat	myAcc_ReadChat	general
10	Send Chat	myAcc_SendChat	general
22	Disconnect User	myAcc_DisconUser	general
32	Broadcast	myAcc_Broadcast	general

Tracker Interface

Client to Tracker

Request:

• Magic Number: 'HTRK' (4 bytes)
• Version: 1 or 2 (2 bytes)

Record Structure:

• IP Address (4), Port (2), User Count (2), Name Size (1), Name (Var).

HTTP Tunneling

Uses POST for sending and GET for receiving.

• MIME: hotline/protocol
• Data Header: 4-byte Code (0=Disconnect, 1=Data, 2=Padding), 4-byte Size.

Global Server

Servers register with a unique name and password to the Global Server to receive a Server ID.

Fields Stored

• Server ID, Name, Password, Alias, Description, IP, Status Flags, User Count.