@chainsafe/netmask/dist/src/cidr.js

Typescript implementation of netmask filtering

import { parseIPv4, parseIPv6 } from "@chainsafe/is-ip/parse";
import { IPv4Len, IPv6Len, maskIp } from "./ip.js";
export function parseCidr(s) {
    const [address, maskString] = s.split("/");
    if (!address || !maskString)
        throw new Error("Failed to parse given CIDR: " + s);
    let ipLength = IPv4Len;
    let ip = parseIPv4(address);
    if (ip == null) {
        ipLength = IPv6Len;
        ip = parseIPv6(address);
        if (ip == null)
            throw new Error("Failed to parse given CIDR: " + s);
    }
    const m = parseInt(maskString, 10);
    if (Number.isNaN(m) ||
        String(m).length !== maskString.length ||
        m < 0 ||
        m > ipLength * 8) {
        throw new Error("Failed to parse given CIDR: " + s);
    }
    const mask = cidrMask(m, 8 * ipLength);
    return {
        network: maskIp(ip, mask),
        mask,
    };
}
export function cidrMask(ones, bits) {
    if (bits !== 8 * IPv4Len && bits !== 8 * IPv6Len)
        throw new Error("Invalid CIDR mask");
    if (ones < 0 || ones > bits)
        throw new Error("Invalid CIDR mask");
    const l = bits / 8;
    const m = new Uint8Array(l);
    for (let i = 0; i < l; i++) {
        if (ones >= 8) {
            m[i] = 0xff;
            ones -= 8;
            continue;
        }
        m[i] = 255 - (0xff >> ones);
        ones = 0;
    }
    return m;
}
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