IPv4-mapped IPv6 address support · Issue #36 · WICG/private-network-access (original) (raw)

Dual stack applications such as modern browsers should never have to deal with IPv4-mapped IPv6 addresses (https://tools.ietf.org/html/rfc4291#section-2.5.5), as they can simply use IPv4 addresses instead. This is not the case today however, at least in Chromium, in which for example [::ffff:7f00:1] resolves to localhost.

This situation is unfortunate, as it results in us having to specify how to determine the address space of such addresses (use the address space of the embedded IPv4 address).

It would be nice to reach a more satisfactory end state, maybe by amending the Fetch specification to forbid accessing such IP addresses?