d4t_formulas/assets/formulas/it-networking.d4rt

[
  {
    "name": "Network Address from Host IP",
    "description": r"""Calculates the network address from a host IP/MASK notation.

Given a host IP address and subnet mask in CIDR notation (e.g., 192.168.1.100/24),
this formula extracts the network address (e.g., 192.168.1.0/24).

Where:
- Host IP/MASK: IP address with CIDR subnet mask (e.g., 192.168.1.100/24)
- Network: The resulting network address in IP/MASK format (e.g., 192.168.1.0/24)

The network address is calculated by applying the subnet mask to zero out the host bits.""",
    "input": [
      {"name": "hostIP", "unit": "string"}
    ],
    "output": {"name": "network", "unit": "string"},
    "d4rtCode": r"""
       hostIP = hostIP.toString();
       var parts = hostIP.split('/');
       if( parts.length != 2 ) {
         signal('Invalid input format. Expected format: IP/MASK');
       }
       var ip = parts[0];
       var mask = int.tryParse(parts[1]);
       if( mask == null || mask < 0 || mask > 32 ) {
         signal('Invalid subnet mask. Must be an integer between 0 and 32.');
       }
       var octets = ip.split('.').map((e) => int.tryParse(e)).toList();
       if( octets.length != 4 ) {
         signal('Invalid IP address format. Expected 4 octets separated by dots.');
       }
       var hostBits = 32 - mask;
       var shiftAmount = hostBits;
       var networkValue = 0;
       for (var i = 0; i < 4; i++) {
         if (octets[i] == null || octets[i] < 0 || octets[i] > 255) {
           signal('Invalid IP address. Each octet must be between 0 and 255.');
         }
         networkValue = (networkValue << 8) | octets[i];
       }
       networkValue = (networkValue >> shiftAmount) << shiftAmount;
       var networkOctets = [];
       for (var i = 0; i < 4; i++) {
         networkOctets.insert(0, networkValue & 0xFF);
         networkValue = networkValue >> 8;
       }
       network = networkOctets.join('.') + '/' + mask.toString();
    """,
    "tags": ["networking", "ip", "subnetting", "cidr", "network"]
  }
]