Echo Client - Bitwise Operation Protocol

Overview

This is a C-based TCP client that implements a custom protocol (cs230) for performing bitwise operations. The client connects to a server, exchanges messages, and performs various bitwise operations on numbers received from the server.

Protocol Description

Message Format

• Initial Handshake: cs230 HELLO <identification>\n
• Server Request: cs230 STATUS <operation> <number>\n
• Client Response: cs230 <result>\n
• Termination: Server sends BYE when complete

Supported Operations

LEFT - Left bit shift

Shifts the number left by (number % 10) positions

RIGHT - Right bit shift

Shifts the number right by (number % 10) positions

OR - Bitwise OR with mask

• Extracts the least significant 4 bits of the number
• Creates a mask by repeating this value: least_sig * 0x11111111
• Performs OR operation: number | mask

AND - Bitwise AND with mask

• Extracts the least significant 4 bits of the number
• Creates a mask by repeating this value: least_sig * 0x11111111
• Performs AND operation: number & mask

Compilation

gcc -o echo_client echo_client.c

Usage

./echo_client <identification> <port> <host_ip>

Parameters

• identification: A string identifier for this client
• port: The port number of the server
• host_ip: The IP address of the server

Example

./echo_client myid123 8080 127.0.0.1

Program Flow

1. Connection: Connects to the specified server
2. Handshake: Sends HELLO message with identification
3. Operation Loop:
   • Receives operation request from server
   • Parses operation type and number
   • Performs the requested bitwise operation
   • Sends result back to server
   • Repeats until BYE is received
4. Termination: Closes connection and exits

Output

The client prints all sent and received messages, along with the operation details:

Echo Client is creating a socket.
Echo Client is trying to connect to (127.0.0.1:8080).
Echo Client connected.
SENT: cs230 HELLO myid123
RECEIVED: cs230 STATUS LEFT 42
Operation: LEFT
Number: 42
SENT: cs230 2688
...

Error Handling

• Validates command-line arguments
• Checks socket creation and connection
• Verifies send/recv operations
• Exits with error messages on failure

Requirements

• POSIX-compliant system (Linux/Unix/macOS)
• Standard C libraries
• Network connectivity to target server