Chat Application

A simple TCP-based chat application with multithreading support, implementing all required features from the project rubric.

Features

Core Features (14 points total)

1. Get Friend List and Status (1 point)

   • Display list of users and their online/offline status

2. Send and Receive Messages (1-1) (1 point)

   • Real-time 1-1 chat between two users

3. Disconnect (1 point)

   • When a user leaves a conversation, the system notifies the other party

4. Create Group Chat (1 point)

   • Allows users to create new group chats

5. Add Users to Group Chat (1 point)

   • Group creator can invite more members

6. Remove Users from Group Chat (1 point)

   • Group administrators can remove members from the group

7. Leave Group Chat (1 point)

   • Users can leave groups they are participating in

8. Send and Receive Messages in Group Chat (1 point)

   • Supports sending messages to all members in the group

9. Send Offline Messages (1 point)

   • Saves messages when the recipient is not yet online

10. Log Activity (1 point)

    • Records all user activity for review

11. Search Chat History (1 point)

    • Allows searching old messages by keyword

12. Send Emoji (1 point)

    • Supports emojis in messages

13. Set Group Nickname (0.5 points)

    • Rename group chat

14. Block User (1 point)

    • Block users

15. Pin Message in Conversation (0.5 points)

    • Pin messages in chat segment

Architecture

• Server: Multithreaded TCP server handling multiple client connections
• Client: TCP client with separate receive thread for real-time messaging
• Protocol: Custom text-based protocol for communication
• Storage: File-based storage for messages and activity logs

Building

Windows (MinGW/MSVC)

# Using MinGW
make

# Or compile manually
gcc -Wall -Wextra -std=c11 -o server.exe server.c common.c -lws2_32
gcc -Wall -Wextra -std=c11 -o client.exe client.c common.c -lws2_32

Linux

make

# Or compile manually
gcc -Wall -Wextra -std=c11 -o server server.c common.c -pthread
gcc -Wall -Wextra -std=c11 -o client client.c common.c -pthread

Running

Quick Start

1. Build the project:

   make

2. Start the server (in one terminal):

   # Windows
   server.exe
   
   # Linux
   ./server

   You should see: Server started on port 8080

3. Start a client (in another terminal):

   # Windows
   client.exe
   
   # Linux
   ./client

   To connect to a remote server: client.exe 192.168.1.100

4. Use the menu to register, login, and chat!

See QUICKSTART.md for detailed step-by-step instructions and examples.

Usage

1. Register: Create a new account with username and password
2. Login: Login with your credentials
3. Get Friends: View your friend list and their online status
4. Send Message: Send 1-1 messages to other users
5. Create Group: Create a new group chat
6. Group Operations: Add/remove members, send group messages
7. Search: Search through chat history
8. Block/Unblock: Manage blocked users
9. Pin Messages: Pin important messages in groups

Files

• server.c / server.h: Server implementation
• client.c / client.h: Client implementation
• common.c / common.h: Shared utilities and data structures
• Makefile: Build configuration
• activity.log: Activity log file (created at runtime)
• messages.txt: Message storage file (created at runtime)
• account.txt: Simple username/password persistence (one account per line: username password). The server loads this file at startup and appends new accounts on successful registration.

Protocol

The application uses a custom text-based protocol:

CMD:<command_type>|SENDER:<username>|RECIPIENT:<recipient>|CONTENT:<content>|EXTRA:<extra_data>|TYPE:<message_type>|PINNED:<0|1>|

Notes

• The server supports multiple concurrent clients using multithreading
• Messages are stored in messages.txt for persistence
• Activity logs are written to activity.log
• Offline messages are stored and can be retrieved when users come online
• Group administrators can manage group members and settings