cidrv6Intersect - cidrv6.ts - @hertzg/ip documentation

function cidrv6Intersect



cidrv6Intersect(a: Cidrv6,
b: Cidrv6
): Cidrv6 | null

Returns the intersection of two IPv6 CIDR blocks.

Since CIDR blocks are power-of-2-aligned, two overlapping blocks always have a containment relationship -- the intersection is the more specific (longer prefix) block with its canonical network address.

The result matches the dialect of the inputs. When they disagree, it is a MaskedCidrv6 (ADR 0006).

Examples

Find overlap between allocations

import { assertEquals } from "@std/assert";
import { cidrv6Intersect, parseCidrv6, stringifyCidrv6 } from "@hertzg/ip/cidrv6";

const result = cidrv6Intersect(
  parseCidrv6("2001:db8::/32"),
  parseCidrv6("2001:db8::/48"),
);
assertEquals(result && stringifyCidrv6(result), "2001:db8::/48");

No overlap returns null

import { assertEquals } from "@std/assert";
import { cidrv6Intersect, parseCidrv6 } from "@hertzg/ip/cidrv6";

assertEquals(cidrv6Intersect(
  parseCidrv6("2001:db8::/32"),
  parseCidrv6("2001:db9::/32"),
), null);

Mixed dialects intersect to a masked block

import { assertEquals } from "@std/assert";
import { cidrv6Intersect, parseCidrv6 } from "@hertzg/ip/cidrv6";

const mask = 0xFFFFFFFFFFFF00000000000000000000n;
const result = cidrv6Intersect(
  parseCidrv6("2001:db8::/32"),
  { address: 0x20010db8n << 96n, mask },
);
assertEquals(result, { address: 0x20010db8n << 96n, mask });

Parameters



a: Cidrv6

The first CIDR block



b: Cidrv6

The second CIDR block

Return Type

Cidrv6 | null

The overlapping CIDR with canonical network address, or null if disjoint