openshift/openshift-copies.go
func newProxierWithNoProxyCIDR(delegate func(req *http.Request) (*url.URL, error)) func(req *http.Request) (*url.URL, error) {
	// we wrap the default method, so we only need to perform our check if the NO_PROXY envvar has a CIDR in it
	noProxyEnv := os.Getenv("NO_PROXY")
	noProxyRules := strings.Split(noProxyEnv, ",")

	cidrs := []*net.IPNet{}
	for _, noProxyRule := range noProxyRules {
		_, cidr, _ := net.ParseCIDR(noProxyRule)
		if cidr != nil {
			cidrs = append(cidrs, cidr)
		}
	}

	if len(cidrs) == 0 {
		return delegate
	}

	return func(req *http.Request) (*url.URL, error) {
		host := req.URL.Host
		// for some urls, the Host is already the host, not the host:port
		if net.ParseIP(host) == nil {
			var err error
			host, _, err = net.SplitHostPort(req.URL.Host)
			if err != nil {
				return delegate(req)
			}
		}

		ip := net.ParseIP(host)
		if ip == nil {
			return delegate(req)
		}

		for _, cidr := range cidrs {
			if cidr.Contains(ip) {
				return nil, nil
			}
		}

		return delegate(req)
	}
}
func newProxierWithNoProxyCIDR(delegate func(req *http.Request) (*url.URL, error)) func(req *http.Request) (*url.URL, error) {
	// we wrap the default method, so we only need to perform our check if the NO_PROXY envvar has a CIDR in it
	noProxyEnv := os.Getenv("NO_PROXY")
	noProxyRules := strings.Split(noProxyEnv, ",")

	cidrs := []*net.IPNet{}
	for _, noProxyRule := range noProxyRules {
		_, cidr, _ := net.ParseCIDR(noProxyRule)
		if cidr != nil {
			cidrs = append(cidrs, cidr)
		}
	}

	if len(cidrs) == 0 {
		return delegate
	}

	return func(req *http.Request) (*url.URL, error) {
		host := req.URL.Host
		// for some urls, the Host is already the host, not the host:port
		if net.ParseIP(host) == nil {
			var err error
			host, _, err = net.SplitHostPort(req.URL.Host)
			if err != nil {
				return delegate(req)
			}
		}

		ip := net.ParseIP(host)
		if ip == nil {
			return delegate(req)
		}

		for _, cidr := range cidrs {
			if cidr.Contains(ip) {
				return nil, nil
			}
		}

		return delegate(req)
	}
}
// newProxierWithNoProxyCIDR is a modified copy of k8s.io/apimachinery/pkg/util/net.NewProxierWithNoProxyCIDR.
// NewProxierWithNoProxyCIDR constructs a Proxier function that respects CIDRs in NO_PROXY and delegates if
// no matching CIDRs are found