// Do not remove or change the type signature.
// See go.dev/issue/67401.
//
//go:linkname defaultNS
var defaultNS = []string{"127.0.0.1:53", "[::1]:53"}

var getHostname = os.Hostname // variable for testing

type dnsConfig struct {
	servers       []string      // server addresses (in host:port form) to use
	search        []string      // rooted suffixes to append to local name

		hostnetwork       bool
		dnsPolicy         v1.DNSPolicy
		dnsConfig         *v1.PodDNSConfig
		expectedDNSConfig *runtimeapi.DNSConfig
	}{
		{
			desc:              "DNSNone without DNSConfig should have empty DNS settings",
			dnsPolicy:         v1.DNSNone,
			expectedDNSConfig: &runtimeapi.DNSConfig{},
		},
		{
			desc:      "DNSNone with DNSConfig should have a merged DNS settings",
			dnsPolicy: v1.DNSNone,

	lastChecked time.Time     // last time resolv.conf was checked

	dnsConfig atomic.Pointer[dnsConfig] // parsed resolv.conf structure used in lookups
}

var resolvConf resolverConfig

func getSystemDNSConfig() *dnsConfig {
	resolvConf.tryUpdate("/etc/resolv.conf")
	return resolvConf.dnsConfig.Load()
}

// init initializes conf and is only called via conf.initOnce.

package net

import (
	"internal/bytealg"
	"internal/stringslite"
	"net/netip"
	"time"
)

// See resolv.conf(5) on a Linux machine.
func dnsReadConfig(filename string) *dnsConfig {
	conf := &dnsConfig{
		ndots:    1,
		timeout:  5 * time.Second,
		attempts: 2,
	}
	file, err := open(filename)
	if err != nil {
		conf.servers = defaultNS
		conf.search = dnsDefaultSearch()
		conf.err = err

// The provided Resolver is optional. nil means to not consider its options.
// It also returns dnsConfig when it was used to determine the lookup order.
func (c *conf) addrLookupOrder(r *Resolver, addr string) (ret hostLookupOrder, dnsConf *dnsConfig) {
	if c.dnsDebugLevel > 1 {
		defer func() {
			print("go package net: addrLookupOrder(", addr, ") = ", ret.String(), "\n")
		}()
	}

	// traffic to port 53 will be captured.
	if c.RedirectDNS && !c.CaptureAllDNS {
		dnsConfig, err := dns.ClientConfigFromFile("/etc/resolv.conf")
		if err != nil {
			return fmt.Errorf("failed to load /etc/resolv.conf: %v", err)
		}
		c.DNSServersV4, c.DNSServersV6 = netutil.IPsSplitV4V6(dnsConfig.Servers)
	}
	return nil
}

// mock net.InterfaceAddrs to make its unit test become available
var (

			Uid:       podUID,
			Attempt:   attempt,
		},
		Labels:      newPodLabels(pod),
		Annotations: newPodAnnotations(pod),
	}

	dnsConfig, err := m.runtimeHelper.GetPodDNS(pod)
	if err != nil {
		return nil, err
	}
	podSandboxConfig.DnsConfig = dnsConfig

	if !kubecontainer.IsHostNetworkPod(pod) {
		// TODO: Add domain support in new runtime interface

	GenerateRunContainerOptions(ctx context.Context, pod *v1.Pod, container *v1.Container, podIP string, podIPs []string) (contOpts *RunContainerOptions, cleanupAction func(), err error)
	GetPodDNS(pod *v1.Pod) (dnsConfig *runtimeapi.DNSConfig, err error)
	// GetPodCgroupParent returns the CgroupName identifier, and its literal cgroupfs form on the host
	// of a pod.
	GetPodCgroupParent(pod *v1.Pod) string
	GetPodDir(podUID types.UID) string

      # the application will first try to resolve the hostname (a, a.ns, etc.) as is
      # before attempting to add the search namespaces.
      dnsPolicy: None
      dnsConfig:
        nameservers:
        - "8.8.8.8"
        options:
        - name: "ndots"
          value: "1"
{{- if $.VM.IstioHost }}
      # Override the istiod host to force traffic through east-west gateway.

}

func (conf *resolvConfTest) forceUpdateConf(c *dnsConfig, lastChecked time.Time) bool {
	conf.dnsConfig.Store(c)
	for i := 0; i < 5; i++ {
		if conf.tryAcquireSema() {
			conf.lastChecked = lastChecked
			conf.releaseSema()
			return true
		}
	}
	return false
}

func (conf *resolvConfTest) servers() []string {
	return conf.dnsConfig.Load().servers
}