Ping

Ping Example

Overview

The Ping Test application is a network connectivity testing utility that allows users to verify the reach-ability and response time of remote devices on a network. This application demonstrates the basic implementation of ICMP ping functionality using hostname resolution and network diagnostics.

Features

• Interactive Command Line Interface: User-friendly prompt-based interaction for entering target addresses
• Hostname Resolution: Automatic DNS lookup to resolve hostnames to IP addresses
• ICMP Ping Testing: Sends ping packets to test network connectivity
• Response Time Measurement: Reports the time taken for ping responses in system ticks
• Input Editing: Basic command-line editing with backspace support
• Continuous Operation: Runs in a loop allowing multiple ping tests without restarting

How It Works

1. User Input: The application prompts the user to enter an IP address or hostname
2. DNS Resolution: Uses GetHostByName() to resolve hostnames to IP addresses
3. Ping Execution: Sends an ICMP ping packet using the Ping() function
4. Result Display: Shows the target IP address and response time or failure status
5. Loop Continuation: Returns to step 1 for continuous testing

Key Functions

Gets_w_Edit(char *buf, int maxl)

Custom input function that provides basic line editing capabilities:

• Handles character input with buffer management
• Supports backspace (ASCII 8) for editing
• Terminates input on carriage return or newline
• Prevents buffer overflow by limiting input length

UserMain(void *pd)

Main application loop that:

• Initializes the system and enables diagnostics
• Manages the interactive ping testing cycle
• Handles DNS resolution and ping execution
• Displays results and error messages

Technical Details

• Language: C/C++
• Dependencies:
  • init.h - System initialization
  • dns.h - DNS resolution functions
• Network Functions:
  • GetHostByName() - DNS hostname resolution
  • Ping() - ICMP ping implementation
• Timeout: DNS resolution timeout set to 30 seconds
• Ping Parameters:
  • ID: 1
  • Sequence: 1
    
  • Maximum wait time: 100 ticks

Usage Example

Enter address to ping: google.com
Got:[google.com]
IP address is 172.217.12.110
Response Took 25 ticks
 
Enter address to ping: 8.8.8.8
Got:[8.8.8.8]
IP address is 8.8.8.8
Response Took 15 ticks
 
Enter address to ping: invalid-host.example
Got:[invalid-host.example]
Failed to resolve host

Error Handling

The application handles several error conditions:

• DNS Resolution Failure: Displays "Failed to resolve host" when hostname cannot be resolved
• Ping Failure: Shows "Ping Failed!" when the ping operation returns -1
• Input Validation: Prevents buffer overflow in user input

System Requirements

• Compatible embedded system or platform supporting the included header files
• Network connectivity capability
• ICMP protocol support
• DNS resolution functionality

Development Notes

• System diagnostics are enabled for debugging (should be disabled in production)
• The application runs indefinitely until manually terminated
• Input editing is basic but functional for typical use cases
• Response times are measured in system-specific ticks

Purpose

This application serves as a fundamental example of network connectivity testing and demonstrates:

• Basic network programming concepts
• DNS resolution implementation
• ICMP ping functionality
• Interactive command-line application design
• Error handling in network operations

The Ping Test utility is particularly useful for network troubleshooting, connectivity verification, and as a learning example for embedded network programming.