outposts/proxy: revert to using request Host for redirect URI

Signed-off-by: Jens Langhammer <jens.langhammer@beryju.org>

outpost/pkg/proxy/oauth.go

@@ -161,7 +161,7 @@ func (p *OAuthProxy) OAuthStart(rw http.ResponseWriter, req *http.Request) {
 		p.ErrorPage(rw, http.StatusInternalServerError, "Internal Server Error", err.Error())
 		return
 	}
-	redirectURI := p.GetRedirectURI(getHost(req))
+	redirectURI := p.GetRedirectURI(req.Host)
 	http.Redirect(rw, req, p.provider.GetLoginURL(redirectURI, fmt.Sprintf("%v:%v", nonce, redirect)), http.StatusFound)
 }