66 lines
2.2 KiB
TypeScript
66 lines
2.2 KiB
TypeScript
import { networkInterfaces } from 'os';
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import type { NetworkInterfaceInfo } from 'node:os';
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interface DHCPConfig {
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interfaceName: string;
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rangeStart: string;
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rangeEnd: string;
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subnetMask: string;
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}
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const DEFAULT_SUBNET_MASK = '255.255.255.0';
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const DEFAULT_SUBNET_MASK_OCTETS = DEFAULT_SUBNET_MASK.split('.').map(Number);
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function checkIsIPv4(addr: NetworkInterfaceInfo): boolean {
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return addr.family === 'IPv4' && !addr.internal;
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}
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function calculateNetwork(ip: number[], mask: number[]): number[] {
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// Calculate the network address by applying the bitwise AND operation.
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// eslint-disable-next-line no-bitwise
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return ip.map((octet, i) => octet & mask[i]);
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}
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function calculateBroadcast(network: number[], mask: number[]): number[] {
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// Calculate the broadcast address by ORing the network address with the inverted mask.
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// eslint-disable-next-line no-bitwise
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return network.map((octet, i) => octet | (~mask[i] & 255));
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}
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export function getDHCPConfig(): DHCPConfig {
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const interfaces = networkInterfaces();
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// Select the first interface that has a valid non-internal IPv4 address.
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const ipV4Interface = Object.entries(interfaces)
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.map(([name, addresses]) => ({ name, addresses }))
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.find((i) => i.addresses?.some(checkIsIPv4));
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if (!ipV4Interface) {
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throw new Error('No suitable network interface found');
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}
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// Get the first valid IPv4 address from the interface.
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const ipv4Address = ipV4Interface.addresses.find(checkIsIPv4);
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const ip = ipv4Address.address.split('.').map(Number);
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const mask = ipv4Address.netmask?.split('.').map(Number) || DEFAULT_SUBNET_MASK_OCTETS;
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const network = calculateNetwork(ip, mask);
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// Calculate first usable address (network address + 1)
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const rangeStart = [...network];
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rangeStart[3] = network[3] + 1;
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// Calculate broadcast address and then the last usable address (broadcast - 1)
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const broadcast = calculateBroadcast(network, mask);
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const rangeEnd = [...broadcast];
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rangeEnd[3] = broadcast[3] - 1;
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return {
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interfaceName: ipV4Interface.name,
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rangeStart: rangeStart.join('.'),
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rangeEnd: rangeEnd.join('.'),
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subnetMask: ipv4Address.netmask || DEFAULT_SUBNET_MASK,
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};
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}
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