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fast-cidr-tools

v0.3.1

Published

cidr-tools but up to 20x faster

Downloads

316

Readme

fast-cidr-tools

Tools to work with IPv4 and IPv6 CIDR, but 20x faster than cidr-tools, and is not Pure ESM (publish both CommonJS and ESM).

Requires BigInt supports.

Usage

import {
  ip2bigint, // support both IPv4 and IPv6
  bigint2ip, // support both IPv4 and IPv6
  contains,
  exclude,
  expand,
  merge,
  overlap
} from 'fast-cidr-tools';

contains(['1.0.0.0/24', '2.0.0.0/24'], ['1.0.0.1']) //=> true
exclude(['::1/127'], ['::1/128']) //=> ['::/128']
expand(['2001:db8::/126']) //=> ['2001:db8::', '2001:db8::1', '2001:db8::2', '2001:db8::3']
merge(['1.0.0.0/24'], ['1.0.1.0/24']); //=> ['1.0.0.0/23']
overlap(['1.0.0.0/24'], ['1.0.0.128/25']) //=> true

Performance

fast-cidr-tools is very fast, and is specfically optimized for IPv4. In some cases, it can be 20x faster than cidr-tools. fast-cidr-tools acheive this performance by:

  • Doing less things, E.g.:
    • cidr-tools will cast input to an array if it is string (cidrTools.merge('1.0.0.0/24', '1.0.1.0/24')). fast-cidr-tools only supports array input.
    • cidr-tools sort the return value of merge and exclude by default. fast-cidr-tools's sort is opt-in.
    • And many more.
  • Use efficient calculation and avoid unnecessary string operations.
    • how cidr-tools and fast-cidr-tools calculate the "biggest power of two":
      // cidr-tools
      function biggestPowerOfTwo(num) {
        if (num === 0n) return 0n;
        return 2n ** BigInt(String(num.toString(2).length - 1));
      }
      
      // fast-cidr-tools
      // Not the actual implementation: fast-cidr-tools actually inlines the calculation
      // for better performance
      const uint64 = new BigUint64Array(1);
      const uint32 = new Uint32Array(uint64.buffer);
      function clz64(bigint: bigint) {
        uint64[0] = bigint;
        let r = Math.clz32(uint32[1]);
        if (r === 32) {
          r += Math.clz32(uint32[0]);
        }
        return r;
      }
      function biggestPowerOfTwo(num: bigint) {
        if (num === 0n) return 0n;
        const power = BigInt(64 - clz64(size) - 1);
        return 2n ** (power === -1n ? 128n : power);
      }
    • how cidr-tools and fast-cidr-tools calculate the prefix of a CIDR:
      // cidr-tools
      const zeroes = (part.end + 1n - part.start).toString(2);
      const prefix = bits[v] - (zeroes.match(/0/g) || []).length;
      
      // fast-cidr-tools
      function fast_popcnt(value: bigint | number) {
        let v = Number(value);
        v -= v >>> 1 & 0x55_55_55_55;
        v = (v & 0x33_33_33_33) + (v >>> 2 & 0x33_33_33_33);
        return BigInt((((v + (v >>> 4)) & 0x0F_0F_0F_0F) * 0x01_01_01_01) >>> 24);
      }
      const uint64_0 = new BigInt64Array(1);
      const uint32_0 = new Int32Array(uint64_0.buffer);
      function fast_popcnt64(value: bigint) {
        uint64_0[0] = value;
        return fast_popcnt(uint32_0[0]) + fast_popcnt(uint32_0[1]);
      }
      const prefix = bits[v] - (v === 4 ? fast_popcnt(end - start) : fast_popcnt64(end - start));
  • Use a more compact internal data structure. Compare how cidr-tools and fast-cidr-tools represent a CIDR internally:
    // cidr-tools
    parse('::/64'); //=> { cidr: '::/64', version: 6, prefix: '64', start: 0n, end: 18446744073709551615n }
    
    // fast-cidr-tools
    parse('::/64'); //=> [0n, 18446744073709551615n, 6]
  • Avoid repeated calculations. Notice how fast-cidr-tools pre-parse inputs instead of parsing them repeatedly:

fast-cidr-tools © Sukka, Authored and maintained by Sukka with help from contributors (list).

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