Resolve all localhost addresses without querying DNS servers (#16749)#16820
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Motivation: According to RFC 6761, all domains within .localhost. should be resolved to the loopback address without querying DNS servers. This is useful e.g. when you have multiple web servers behind a local reverse proxy and you want to route the requests based on the hostname. Previously, netty would only resolve hostnames specified in the hosts file (or localhost and the machine hostname on windows) without querying DNS servers. Modifications: - localhost and all domains within .localhost. are now directly resolved to the loopback address - Replaced isLocalWindowsHost with isLocalHostAddress - Replaced LOCALHOST_ADDRESS constant with getLocalHostAddress method to correctly return the correct loopback address based on resolvedAddressTypes - Added test that covers all combinations of DnsNameResolverChannelStrategy, ResolvedAddressTypes and various localhost hostnames Result: Localhost hostnames are now resolved directly to the loopback address without querying a DNS server. Overriding them in the hosts file is still possible. Fixes #16744 --------- Co-authored-by: Norman Maurer <norman_maurer@apple.com>
yawkat
approved these changes
May 18, 2026
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Motivation:
According to RFC 6761, all domains within .localhost. should be resolved to the loopback address without querying DNS servers. This is useful e.g. when you have multiple web servers behind a local reverse proxy and you want to route the requests based on the hostname. Previously, netty would only resolve hostnames specified in the hosts file (or localhost and the machine hostname on windows) without querying DNS servers.
Modifications:
Result:
Localhost hostnames are now resolved directly to the loopback address without querying a DNS server. Overriding them in the hosts file is still possible.
Fixes #16744