cidrv4Intersect - mod.ts - @hertzg/ip documentation

function cidrv4Intersect



cidrv4Intersect(a: Cidrv4,
b: Cidrv4
): Cidrv4 | null

Returns the intersection of two IPv4 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 MaskedCidrv4 (ADR 0006).

Examples

Find overlap between allocations

import { assertEquals } from "@std/assert";
import { cidrv4Intersect, parseCidrv4, stringifyCidrv4 } from "@hertzg/ip/cidrv4";

const result = cidrv4Intersect(
  parseCidrv4("192.168.1.0/24"),
  parseCidrv4("192.168.1.0/28"),
);
assertEquals(result && stringifyCidrv4(result), "192.168.1.0/28");

No overlap returns null

import { assertEquals } from "@std/assert";
import { cidrv4Intersect, parseCidrv4 } from "@hertzg/ip/cidrv4";

assertEquals(cidrv4Intersect(
  parseCidrv4("10.0.0.0/8"),
  parseCidrv4("172.16.0.0/12"),
), null);

Mixed dialects intersect to a masked block

import { assertEquals } from "@std/assert";
import { cidrv4Intersect, parseCidrv4 } from "@hertzg/ip/cidrv4";

const result = cidrv4Intersect(
  parseCidrv4("192.168.1.0/24"),
  { address: 3232235776, mask: 0xFFFFFFF0 },
);
assertEquals(result, { address: 3232235776, mask: 0xFFFFFFF0 });

Parameters



a: Cidrv4

The first CIDR block



b: Cidrv4

The second CIDR block

Return Type

Cidrv4 | null

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