UDP Sockets Via

UDP Sockets Via Example

Overview

This NetBurner application demonstrates UDP socket communication using the NetBurner Development Kit (NNDK). The application creates multiple UDP sockets across different network interfaces and allows bidirectional communication with other hosts on the network.

Features

• Multiple Socket Types: Creates receive-only (RX), transmit-only (TX), and bidirectional (RX/TX) UDP sockets
• Multi-Interface Support: Automatically creates sockets for all available network interfaces
• Port Management: Uses sequential port numbering starting from port 5000
• Select-based Receiving: Demonstrates non-blocking UDP packet reception using the select() system call
• Interactive Menu: Provides a simple command interface via serial terminal

Application Functionality

Socket Creation

The application creates three types of UDP sockets for each interface:

1. RX Socket: Receive-only socket for incoming UDP packets
2. RX/TX Socket: Bidirectional socket for both sending and receiving
3. TX Socket: Transmit-only socket for outgoing UDP packets

Interface Detection

The program automatically detects all available network interfaces and creates sockets for:

• All interfaces (general sockets)
• Specific interface numbers
• Specific IP addresses

Port Assignment

Starting from port 5000, the application assigns ports sequentially:

• Port N: RX socket
• Port N+1: RX/TX socket
  
• Port N+2: TX socket

Usage

Setup

1. Compile and flash the application to your NetBurner device
2. Connect to the device using MTTTY serial port program
3. Wait for the network to initialize and obtain a DHCP address

Operation

1. Enter Destination IP: When prompted, enter the IP address of the UDP host you want to communicate with
2. View Socket Information: The application displays a table showing:

    RX  | RXTX|  TX |  On    
   5000| 5001| 5002|All
   5003| 5004| 5005|ifn1 on 192.168.1.100
   5006| 5007| 5008|IP:192.168.1.100

3. Send Test Packets: Press 'T' or 't' to transmit test messages to all TX-capable sockets
4. Receive Packets: The application automatically displays received UDP packets with source information

Commands

• T or t: Transmit test packets to all transmit-capable sockets

Code Structure

Main Components

• AddSocketsIfn(): Creates sockets for a specific interface number
• AddSocketsIP(): Creates sockets for a specific IP address
  
• TransmitAll(): Sends test messages through all transmit sockets
• UserMain(): Main application loop handling initialization and packet processing

Key Variables

• rx_fd[]: Array of receive-capable socket file descriptors
• tx_fd[]: Array of transmit-capable socket file descriptors
• using_port: Current port number for socket creation
• nrxfd, ntxfd: Counters for RX and TX socket arrays

Testing

External UDP Hosts

You can test the application using:

• NetBurner Java UDP example application
• NetBurner UDP terminal program
• Any standard UDP client/server application

Packet Reception

When UDP packets are received, the application displays:

• Number of bytes received
• Source IP address
• Local port number
• Remote port number
• Hexadecimal dump of packet data

API Information

This example demonstrates the NetBurner UDP Sockets API functions:

• CreateRxUdpSocket()
• CreateTxUdpSocket()
  
• CreateRxTxUdpSocket()
• CreateRxUdpSocketVia()
• CreateTxUdpSocketVia()
• CreateRxTxUdpSocketVia()

For C++ applications, NetBurner also provides a UDPPacket class API for object-oriented UDP handling.

Notes

• The application enables system diagnostics for debugging (should be disabled in production)
• All sockets use UDP protocol for lightweight, connectionless communication
• The select() mechanism allows efficient handling of multiple socket file descriptors
• Socket creation spans all detected network interfaces automatically