Computer-Networks

Socket Programming Examples in C

A comprehensive collection of network programming examples demonstrating various aspects of socket programming and network protocols.

Core Socket Programming Concepts

Socket Types and Domains

Stream Sockets (SOCK_STREAM)

• TCP/IP based
• Connection-oriented
• Reliable data delivery
• Used in all chat applications

Internet Protocol Family (AF_INET)

• IPv4 addressing
• Port-based services
• Network byte ordering
• Host-to-network conversions

Common Socket Functions

Basic Socket Operations

socket()   // Create new socket
bind()     // Associate socket with address
listen()   // Mark socket as passive
accept()   // Accept incoming connection
connect()  // Connect to remote host

Data Transfer

send()     // Send data on connected socket
recv()     // Receive data from socket
close()    // Close socket connection

Network Address Structures

struct sockaddr_in {
    sa_family_t sin_family;     // AF_INET
    in_port_t sin_port;         // Port number
    struct in_addr sin_addr;    // IPv4 address
};

Application Categories

Progressive Learning Path

1. Basic Communication (chat_app_1)
   • Single message exchange
   • Basic socket setup
   • Simple error handling
2. Interactive Communication (chat_app_2)
   • Two-way messaging
   • Session management
   • Enhanced error handling
3. Concurrent Communication (chat_app_3)
   • Multi-threaded design
   • Real-time messaging
   • Thread synchronization

Specialized Applications

1. Time Services (time_of_server)
   • Time synchronization
   • Formatted time handling
   • Simple request-response
2. Data Processing (sorter_application)
   • Binary protocols
   • Network byte ordering
   • Array manipulation
3. Multi-Service (ask_server)
   • Menu-driven interface
   • Multiple services
   • State management

Advanced Topics Covered

Threading Concepts

• POSIX threads (pthread)
• Thread synchronization
• Shared resource management
• Race condition prevention

Protocol Design

• Text-based protocols
• Binary protocols
• Request-response patterns
• Message formatting

Network Programming Patterns

• Iterative servers
• Concurrent servers
• Connection management
• Resource cleanup

Error Handling

• Socket errors
• Network failures
• Resource cleanup
• User input validation

Additional Resources

Exponential Backoff

• Network congestion handling
• Retry mechanisms
• Collision avoidance
• Mathematical analysis

Building and Running

Each application includes:

• Detailed README
• Compilation instructions
• Usage examples
• Error handling guides

General Compilation Pattern

# Basic applications
gcc server.c -o server
gcc client.c -o client

# Threaded applications
gcc server.c -o server -pthread
gcc client.c -o client -pthread

Learning Path Recommendations

1. Start with chat_app_1 for basic concepts
2. Progress to chat_app_2 for interactive features
3. Explore time_of_server for simple services
4. Study sorter_application for binary protocols
5. Implement chat_app_3 for threading concepts
6. Master ask_server for complete service design

Best Practices

Code Organization

• Modular design
• Clear error handling
• Proper resource management
• Consistent style

Network Programming

• Buffer management
• Error checking
• Proper cleanup
• Protocol documentation

Thread Safety

• Synchronization
• Resource protection
• State management
• Clean termination