30 lines
930 B
Go
30 lines
930 B
Go
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package handlers
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import (
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"net/http"
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"strings"
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)
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// forwardedHost returns the public host a reverse proxy or CDN forwarded the
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// request on behalf of, taken from the first X-Forwarded-Host value, or "" when
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// the header is absent.
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//
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// Behind a TLS-terminating CDN/proxy, r.Host is the internal origin host the
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// proxy dialed, while the public host the browser actually used arrives here.
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// Callers that need to reason about the client-facing host (origin checks,
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// absolute URL construction) must prefer this over r.Host.
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func forwardedHost(r *http.Request) string {
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forwarded := strings.TrimSpace(r.Header.Get("X-Forwarded-Host"))
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if forwarded == "" {
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return ""
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}
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// Multiple proxy hops produce a comma-separated list; the first entry is
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// the original client-facing host.
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if comma := strings.IndexByte(forwarded, ','); comma >= 0 {
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forwarded = forwarded[:comma]
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}
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return strings.TrimSpace(forwarded)
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}
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