fix: allow any 127.0.0.x as bind IPs (#9281)

It is some times common and convenient to use
just local IPs for testing purposes, 127.0.0.x
are special IPs regardless of being available on
an interface they can be bound to on all operating
systems.

Allow this behavior to work for minio server

fixes #9274

cmd/net.go

@@ -277,9 +277,23 @@ func isLocalHost(host string, port string, localPort string) (bool, error) {
 		return false, err
 	}
 
+	nonInterIPV4s := mustGetLocalIP4().Intersection(hostIPs)
+	if nonInterIPV4s.IsEmpty() {
+		hostIPs = hostIPs.ApplyFunc(func(ip string) string {
+			if net.ParseIP(ip).IsLoopback() {
+				// Any loopback IP which is not 127.0.0.1
+				// convert it to check for intersections.
+				return "127.0.0.1"
+			}
+			return ip
+		})
+		nonInterIPV4s = mustGetLocalIP4().Intersection(hostIPs)
+	}
+	nonInterIPV6s := mustGetLocalIP6().Intersection(hostIPs)
+
 	// If intersection of two IP sets is not empty, then the host is localhost.
-	isLocalv4 := !mustGetLocalIP4().Intersection(hostIPs).IsEmpty()
+	isLocalv4 := !nonInterIPV4s.IsEmpty()
-	isLocalv6 := !mustGetLocalIP6().Intersection(hostIPs).IsEmpty()
+	isLocalv6 := !nonInterIPV6s.IsEmpty()
 	if port != "" {
 		return (isLocalv4 || isLocalv6) && (port == localPort), nil
 	}