Issue/164-alternate - JSON functionality

[AthenaNetworks]

This PR implements comprehensive JSON output support for fping as requested in #164, adding both compact and pretty-printed formatting options. Based on the wonderful code in #379 by @gsnw-sebast 😊

New Features

1. JSON Output Format

   • New -j/--json flag for compact JSON output
   • New --json-pretty flag for formatted, human-readable output
   • Consistent JSON structure across all output types (per-system and global stats)

2. Pretty Print Functionality

   • Configurable indentation (default: 2 spaces)
   • Proper array and object formatting
   • Optimized spacing around key-value pairs
   • Clean handling of newlines

Technical Implementation

• Added new source files:

  • src/json.c: Core JSON formatting implementation
  • src/json.h: JSON interface definitions

• Key Functions:

  • Enhanced print_per_system_stats() with JSON support
  • Enhanced print_global_stats() with JSON support
  • Added JSON utility functions for consistent formatting

Example Output

Pretty-printed format (--json-pretty):

{
  "hosts": [
    {
      "host": "1.1.1.1",
      "count": [
        "0.400",
        "0.565"
      ]
    }
  ]
}

Compact format (--json):

{"hosts":[{"host":"1.1.1.1","count":["0.400","0.565"]}]}

Compatibility

• No breaking changes
• Default behavior remains unchanged
• Existing output formats are preserved
• JSON output is optional and controlled by flags

Code Changes

• Modified 4 files:
• 172 insertions
• 100 deletions
• Primary changes in src/fping.c, src/json.c, and src/json.h

Test Coverage Details

Added comprehensive test suite to verify JSON output functionality. The tests cover:

1. Basic JSON Output (-J -c)

   • Verifies correct host information
   • Validates statistics fields (xmt, rcv, loss)
   • Checks timing information (min, avg, max)
   • Ensures proper numeric formatting

2. Pretty-Printed JSON (--json-pretty)

   • Validates proper indentation structure
   • Verifies consistent spacing around key-value pairs
   • Ensures proper array and object formatting
   • Maintains same data structure as compact output

3. Count-Based Statistics (-J -C)

   • Tests array of ping responses
   • Verifies proper time formatting for each ping
   • Handles both successful pings and timeouts ("-")
   • Ensures correct array structure

4. Multiple Host Support (-J -g)

   • Tests subnet scanning functionality
   • Verifies each host has complete statistics
   • Validates consistent structure across hosts
   • Ensures proper array nesting

Each test case includes:

• Input validation
• Output structure verification
• Data type checking
• Error case handling
• Format consistency checks

The test suite helps maintain JSON output reliability and should improve code coverage metrics.

[AthenaNetworks]

Finally..... finally I got a working build. Tests are hard, man.