hostmatch

Documentation

Overview

Package hostmatch parses and matches the host entries that appear in an endpoint's `hosts = [...]` list. Entries may be exact `api.foo.com`, port-qualified `api.foo.com:443`, IP literals `10.0.0.5`, IPv6 literals `[fd00::1]:22`, or wildcard suffixes `*.foo.com` (optionally port-qualified).

Wildcards take the form `*.<suffix>`: a single `*` at the leftmost label, immediately followed by `.`, followed by a non-empty hostname containing no further metacharacters. `*.foo.com` matches any name that ends in `.foo.com` and has at least one character before that suffix — both `s3.foo.com` and `s3.us-east-1.foo.com` match, but the bare `foo.com` does not. Single-label restriction (RFC 6125 TLS cert wildcards) is deliberately NOT applied: the matching here is for endpoint routing, not certificate validation, and the operator use case (e.g. `*.amazonaws.com`) needs to span multiple label depths.

Index

• func IsWildcardHost(entry string) bool
• func MatchWildcard(pattern, hostname string) bool
• func SplitHostPort(entry string) (host, port string, err error)
• func ValidateHost(entry string) error

Functions

func IsWildcardHost

func IsWildcardHost(entry string) bool

IsWildcardHost reports whether the host portion of entry is a wildcard pattern. entry may carry a `:port` suffix.

func MatchWildcard

func MatchWildcard(pattern, hostname string) bool

MatchWildcard reports whether the lowercased hostname matches the wildcard pattern. pattern must be a validated `*.<suffix>` form; hostname must be a bare host (no port). Both should already be lowercased — this function does no case folding.

func SplitHostPort

func SplitHostPort(entry string) (host, port string, err error)

SplitHostPort separates a `host[:port]` entry into its parts. For bare hosts it returns port="". Unlike net.SplitHostPort it does NOT error on the bare-host case — the caller (an endpoint's hosts list) routinely accepts both forms.

Wildcard hosts like `*.foo.com` pass through unchanged in the host return; `*.foo.com:443` separates as host=`*.foo.com`, port=`443`.

func ValidateHost

func ValidateHost(entry string) error

ValidateHost checks that entry is a syntactically valid host entry. Accepts exact hostnames, IP literals, port-qualified forms, and `*.<suffix>` wildcards. Returns an error explaining what's wrong when entry doesn't fit any of those.