TCP Chat Application (Go)

A multi-client TCP chat server where clients connect via TCP, register nickname, list users, send direct messages and broadcasts messages to groups.

How to run locally

Prerequisites

• Go 1.22+ (tested with Go 1.22.2)

Start a server(terminal 1)

From the project root(where go.mod is)

go run ./cmd/server

Start a client(terminal 2)

From the project root(where go.mod is)

go run ./cmd/client

You can start many clients with different terminals to test

Commands

Commands are case-insensitive

/NCK <nickname>

Set or change a nickname.

• Must start with alphabet optionally followed by alphanemeric or underscore. Up to 10 characters.

• Fail when the nickname is taken.

Example:

/nck homer

/LST

Show list of registered nicknames.

Example:

/LST

/MSG <recipients> <message>

Send message to recipients.

• Must set nickname first.

Examples:

/MSG homer hello homer

/msg homer,bart hello simpson!

/GRP <groupname> <users>

Register a group for registered users.

• Group name must start with # followed by alphabet and optionally followed by alphanumeric or underscore character. Up to 11 characters.

Example:

/GRP #simpson homer,bart

/MSG #simpson hello simpson!

Architecture

• Server listens on port 6666 and accepts clients.
• Each client connection starts a new goroutine (HandleConnection).
• Client goroutines send Message into a shared messages channel.
• Server retrieves Message from messages channel and replies through Replies channel which each client has.

This design avoids shared mutable state between goroutines.

Refer to Architecture.md for detailed internal structure.