Embedding Strategies
When using version 4 and version 6 addresses interchangeably (via the
Multi class), version 4 addresses are embedded into version 6 addresses so
that both versions are stored as 16-byte binary sequences.
Unfortunately there are several different strategies for embedding a version 4 address into version 6, so this library offers various strategy implementations for the main three:
| Strategy Name | Implementation | Format |
|---|---|---|
| 6to4-derived | Darsyn\IP\Strategy\Derived |
2002:XXXX:XXXX:0000:0000:0000:0000:0000 |
| IPv4-compatible | Darsyn\IP\Strategy\Compatible |
0000:0000:0000:0000:0000:0000:XXXX:XXXX |
| IPv4-mapped | Darsyn\IP\Strategy\Mapped |
0000:0000:0000:0000:0000:ffff:XXXX:XXXX |
Each embedding strategy implements the
Darsyn\IP\Strategy\EmbeddingStrategyInterface which defines methods to:
- Detect whether a version 4 address is embedded into a version 6 address,
- Extracting a version 4 address from a version 6 address, and
- Packing a version 4 address into a version 6 address according to the given strategy.
Specifying a Strategy
This library will automatically use the IPv4-mapped embedding strategy unless otherwise instructed.
An embedding strategy can be specified globally or on a per-instance basis.
<?php
use Darsyn\IP\Strategy;
use Darsyn\IP\Version\Multi as IP;
// Set the IPv4-compatible embedding strategy to be used globally.
IP::setDefaultEmbeddingStrategy(new Strategy\Compatible);
// But for this specific instance use the 6to4-derived embedding strategy.
$ip = IP::factory('127.0.0.1', new Strategy\Derived);