diff --git a/libnetwork/endpoint.go b/libnetwork/endpoint.go index e92d610dcc..85ab1e0f05 100644 --- a/libnetwork/endpoint.go +++ b/libnetwork/endpoint.go @@ -6,11 +6,11 @@ import ( "path/filepath" "github.com/Sirupsen/logrus" - "github.com/docker/docker/pkg/etchosts" - "github.com/docker/docker/pkg/resolvconf" "github.com/docker/libnetwork/driverapi" "github.com/docker/libnetwork/netutils" + "github.com/docker/libnetwork/pkg/etchosts" "github.com/docker/libnetwork/pkg/netlabel" + "github.com/docker/libnetwork/pkg/resolvconf" "github.com/docker/libnetwork/sandbox" "github.com/docker/libnetwork/types" ) @@ -412,7 +412,7 @@ func (ep *endpoint) setupDNS() error { } // replace any localhost/127.* but always discard IPv6 entries for now. - resolvConf, _ = resolvconf.FilterResolvDns(resolvConf, ep.network.enableIPv6) + resolvConf, _ = resolvconf.FilterResolvDNS(resolvConf, ep.network.enableIPv6) return ioutil.WriteFile(ep.container.config.resolvConfPath, resolvConf, 0644) } diff --git a/libnetwork/pkg/etchosts/etchosts.go b/libnetwork/pkg/etchosts/etchosts.go new file mode 100644 index 0000000000..88e6b63e70 --- /dev/null +++ b/libnetwork/pkg/etchosts/etchosts.go @@ -0,0 +1,79 @@ +package etchosts + +import ( + "bytes" + "fmt" + "io" + "io/ioutil" + "regexp" +) + +// Record Structure for a single host record +type Record struct { + Hosts string + IP string +} + +// WriteTo writes record to file and returns bytes written or error +func (r Record) WriteTo(w io.Writer) (int64, error) { + n, err := fmt.Fprintf(w, "%s\t%s\n", r.IP, r.Hosts) + return int64(n), err +} + +// Default hosts config records slice +var defaultContent = []Record{ + {Hosts: "localhost", IP: "127.0.0.1"}, + {Hosts: "localhost ip6-localhost ip6-loopback", IP: "::1"}, + {Hosts: "ip6-localnet", IP: "fe00::0"}, + {Hosts: "ip6-mcastprefix", IP: "ff00::0"}, + {Hosts: "ip6-allnodes", IP: "ff02::1"}, + {Hosts: "ip6-allrouters", IP: "ff02::2"}, +} + +// Build function +// path is path to host file string required +// IP, hostname, and domainname set main record leave empty for no master record +// extraContent is an array of extra host records. +func Build(path, IP, hostname, domainname string, extraContent []Record) error { + content := bytes.NewBuffer(nil) + if IP != "" { + //set main record + var mainRec Record + mainRec.IP = IP + if domainname != "" { + mainRec.Hosts = fmt.Sprintf("%s.%s %s", hostname, domainname, hostname) + } else { + mainRec.Hosts = hostname + } + if _, err := mainRec.WriteTo(content); err != nil { + return err + } + } + // Write defaultContent slice to buffer + for _, r := range defaultContent { + if _, err := r.WriteTo(content); err != nil { + return err + } + } + // Write extra content from function arguments + for _, r := range extraContent { + if _, err := r.WriteTo(content); err != nil { + return err + } + } + + return ioutil.WriteFile(path, content.Bytes(), 0644) +} + +// Update all IP addresses where hostname matches. +// path is path to host file +// IP is new IP address +// hostname is hostname to search for to replace IP +func Update(path, IP, hostname string) error { + old, err := ioutil.ReadFile(path) + if err != nil { + return err + } + var re = regexp.MustCompile(fmt.Sprintf("(\\S*)(\\t%s)", regexp.QuoteMeta(hostname))) + return ioutil.WriteFile(path, re.ReplaceAll(old, []byte(IP+"$2")), 0644) +} diff --git a/libnetwork/pkg/etchosts/etchosts_test.go b/libnetwork/pkg/etchosts/etchosts_test.go new file mode 100644 index 0000000000..c033904c31 --- /dev/null +++ b/libnetwork/pkg/etchosts/etchosts_test.go @@ -0,0 +1,134 @@ +package etchosts + +import ( + "bytes" + "io/ioutil" + "os" + "testing" +) + +func TestBuildDefault(t *testing.T) { + file, err := ioutil.TempFile("", "") + if err != nil { + t.Fatal(err) + } + defer os.Remove(file.Name()) + + // check that /etc/hosts has consistent ordering + for i := 0; i <= 5; i++ { + err = Build(file.Name(), "", "", "", nil) + if err != nil { + t.Fatal(err) + } + + content, err := ioutil.ReadFile(file.Name()) + if err != nil { + t.Fatal(err) + } + expected := "127.0.0.1\tlocalhost\n::1\tlocalhost ip6-localhost ip6-loopback\nfe00::0\tip6-localnet\nff00::0\tip6-mcastprefix\nff02::1\tip6-allnodes\nff02::2\tip6-allrouters\n" + + if expected != string(content) { + t.Fatalf("Expected to find '%s' got '%s'", expected, content) + } + } +} + +func TestBuildHostnameDomainname(t *testing.T) { + file, err := ioutil.TempFile("", "") + if err != nil { + t.Fatal(err) + } + defer os.Remove(file.Name()) + + err = Build(file.Name(), "10.11.12.13", "testhostname", "testdomainname", nil) + if err != nil { + t.Fatal(err) + } + + content, err := ioutil.ReadFile(file.Name()) + if err != nil { + t.Fatal(err) + } + + if expected := "10.11.12.13\ttesthostname.testdomainname testhostname\n"; !bytes.Contains(content, []byte(expected)) { + t.Fatalf("Expected to find '%s' got '%s'", expected, content) + } +} + +func TestBuildHostname(t *testing.T) { + file, err := ioutil.TempFile("", "") + if err != nil { + t.Fatal(err) + } + defer os.Remove(file.Name()) + + err = Build(file.Name(), "10.11.12.13", "testhostname", "", nil) + if err != nil { + t.Fatal(err) + } + + content, err := ioutil.ReadFile(file.Name()) + if err != nil { + t.Fatal(err) + } + + if expected := "10.11.12.13\ttesthostname\n"; !bytes.Contains(content, []byte(expected)) { + t.Fatalf("Expected to find '%s' got '%s'", expected, content) + } +} + +func TestBuildNoIP(t *testing.T) { + file, err := ioutil.TempFile("", "") + if err != nil { + t.Fatal(err) + } + defer os.Remove(file.Name()) + + err = Build(file.Name(), "", "testhostname", "", nil) + if err != nil { + t.Fatal(err) + } + + content, err := ioutil.ReadFile(file.Name()) + if err != nil { + t.Fatal(err) + } + + if expected := ""; !bytes.Contains(content, []byte(expected)) { + t.Fatalf("Expected to find '%s' got '%s'", expected, content) + } +} + +func TestUpdate(t *testing.T) { + file, err := ioutil.TempFile("", "") + if err != nil { + t.Fatal(err) + } + defer os.Remove(file.Name()) + + if err := Build(file.Name(), "10.11.12.13", "testhostname", "testdomainname", nil); err != nil { + t.Fatal(err) + } + + content, err := ioutil.ReadFile(file.Name()) + if err != nil { + t.Fatal(err) + } + + if expected := "10.11.12.13\ttesthostname.testdomainname testhostname\n"; !bytes.Contains(content, []byte(expected)) { + t.Fatalf("Expected to find '%s' got '%s'", expected, content) + } + + if err := Update(file.Name(), "1.1.1.1", "testhostname"); err != nil { + t.Fatal(err) + } + + content, err = ioutil.ReadFile(file.Name()) + if err != nil { + t.Fatal(err) + } + + if expected := "1.1.1.1\ttesthostname.testdomainname testhostname\n"; !bytes.Contains(content, []byte(expected)) { + t.Fatalf("Expected to find '%s' got '%s'", expected, content) + } +} diff --git a/libnetwork/pkg/resolvconf/README.md b/libnetwork/pkg/resolvconf/README.md new file mode 100644 index 0000000000..cdda554ba5 --- /dev/null +++ b/libnetwork/pkg/resolvconf/README.md @@ -0,0 +1 @@ +Package resolvconf provides utility code to query and update DNS configuration in /etc/resolv.conf diff --git a/libnetwork/pkg/resolvconf/resolvconf.go b/libnetwork/pkg/resolvconf/resolvconf.go new file mode 100644 index 0000000000..d491fddad2 --- /dev/null +++ b/libnetwork/pkg/resolvconf/resolvconf.go @@ -0,0 +1,195 @@ +// Package resolvconf provides utility code to query and update DNS configuration in /etc/resolv.conf +package resolvconf + +import ( + "bytes" + "io/ioutil" + "regexp" + "strings" + "sync" + + "github.com/Sirupsen/logrus" + "github.com/docker/docker/pkg/ioutils" +) + +var ( + // Note: the default IPv4 & IPv6 resolvers are set to Google's Public DNS + defaultIPv4Dns = []string{"nameserver 8.8.8.8", "nameserver 8.8.4.4"} + defaultIPv6Dns = []string{"nameserver 2001:4860:4860::8888", "nameserver 2001:4860:4860::8844"} + ipv4NumBlock = `(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)` + ipv4Address = `(` + ipv4NumBlock + `\.){3}` + ipv4NumBlock + // This is not an IPv6 address verifier as it will accept a super-set of IPv6, and also + // will *not match* IPv4-Embedded IPv6 Addresses (RFC6052), but that and other variants + // -- e.g. other link-local types -- either won't work in containers or are unnecessary. + // For readability and sufficiency for Docker purposes this seemed more reasonable than a + // 1000+ character regexp with exact and complete IPv6 validation + ipv6Address = `([0-9A-Fa-f]{0,4}:){2,7}([0-9A-Fa-f]{0,4})` + ipLocalhost = `((127\.([0-9]{1,3}.){2}[0-9]{1,3})|(::1))` + + localhostIPRegexp = regexp.MustCompile(ipLocalhost) + localhostNSRegexp = regexp.MustCompile(`(?m)^nameserver\s+` + ipLocalhost + `\s*\n*`) + nsIPv6Regexp = regexp.MustCompile(`(?m)^nameserver\s+` + ipv6Address + `\s*\n*`) + nsRegexp = regexp.MustCompile(`^\s*nameserver\s*((` + ipv4Address + `)|(` + ipv6Address + `))\s*$`) + searchRegexp = regexp.MustCompile(`^\s*search\s*(([^\s]+\s*)*)$`) +) + +var lastModified struct { + sync.Mutex + sha256 string + contents []byte +} + +// Get returns the contents of /etc/resolv.conf +func Get() ([]byte, error) { + resolv, err := ioutil.ReadFile("/etc/resolv.conf") + if err != nil { + return nil, err + } + return resolv, nil +} + +// GetIfChanged retrieves the host /etc/resolv.conf file, checks against the last hash +// and, if modified since last check, returns the bytes and new hash. +// This feature is used by the resolv.conf updater for containers +func GetIfChanged() ([]byte, string, error) { + lastModified.Lock() + defer lastModified.Unlock() + + resolv, err := ioutil.ReadFile("/etc/resolv.conf") + if err != nil { + return nil, "", err + } + newHash, err := ioutils.HashData(bytes.NewReader(resolv)) + if err != nil { + return nil, "", err + } + if lastModified.sha256 != newHash { + lastModified.sha256 = newHash + lastModified.contents = resolv + return resolv, newHash, nil + } + // nothing changed, so return no data + return nil, "", nil +} + +// GetLastModified retrieves the last used contents and hash of the host resolv.conf. +// Used by containers updating on restart +func GetLastModified() ([]byte, string) { + lastModified.Lock() + defer lastModified.Unlock() + + return lastModified.contents, lastModified.sha256 +} + +// FilterResolvDNS cleans up the config in resolvConf. It has two main jobs: +// 1. It looks for localhost (127.*|::1) entries in the provided +// resolv.conf, removing local nameserver entries, and, if the resulting +// cleaned config has no defined nameservers left, adds default DNS entries +// 2. Given the caller provides the enable/disable state of IPv6, the filter +// code will remove all IPv6 nameservers if it is not enabled for containers +// +// It returns a boolean to notify the caller if changes were made at all +func FilterResolvDNS(resolvConf []byte, ipv6Enabled bool) ([]byte, bool) { + changed := false + cleanedResolvConf := localhostNSRegexp.ReplaceAll(resolvConf, []byte{}) + // if IPv6 is not enabled, also clean out any IPv6 address nameserver + if !ipv6Enabled { + cleanedResolvConf = nsIPv6Regexp.ReplaceAll(cleanedResolvConf, []byte{}) + } + // if the resulting resolvConf has no more nameservers defined, add appropriate + // default DNS servers for IPv4 and (optionally) IPv6 + if len(GetNameservers(cleanedResolvConf)) == 0 { + logrus.Infof("No non-localhost DNS nameservers are left in resolv.conf. Using default external servers : %v", defaultIPv4Dns) + dns := defaultIPv4Dns + if ipv6Enabled { + logrus.Infof("IPv6 enabled; Adding default IPv6 external servers : %v", defaultIPv6Dns) + dns = append(dns, defaultIPv6Dns...) + } + cleanedResolvConf = append(cleanedResolvConf, []byte("\n"+strings.Join(dns, "\n"))...) + } + if !bytes.Equal(resolvConf, cleanedResolvConf) { + changed = true + } + return cleanedResolvConf, changed +} + +// getLines parses input into lines and strips away comments. +func getLines(input []byte, commentMarker []byte) [][]byte { + lines := bytes.Split(input, []byte("\n")) + var output [][]byte + for _, currentLine := range lines { + var commentIndex = bytes.Index(currentLine, commentMarker) + if commentIndex == -1 { + output = append(output, currentLine) + } else { + output = append(output, currentLine[:commentIndex]) + } + } + return output +} + +// IsLocalhost returns true if ip matches the localhost IP regular expression. +// Used for determining if nameserver settings are being passed which are +// localhost addresses +func IsLocalhost(ip string) bool { + return localhostIPRegexp.MatchString(ip) +} + +// GetNameservers returns nameservers (if any) listed in /etc/resolv.conf +func GetNameservers(resolvConf []byte) []string { + nameservers := []string{} + for _, line := range getLines(resolvConf, []byte("#")) { + var ns = nsRegexp.FindSubmatch(line) + if len(ns) > 0 { + nameservers = append(nameservers, string(ns[1])) + } + } + return nameservers +} + +// GetNameserversAsCIDR returns nameservers (if any) listed in +// /etc/resolv.conf as CIDR blocks (e.g., "1.2.3.4/32") +// This function's output is intended for net.ParseCIDR +func GetNameserversAsCIDR(resolvConf []byte) []string { + nameservers := []string{} + for _, nameserver := range GetNameservers(resolvConf) { + nameservers = append(nameservers, nameserver+"/32") + } + return nameservers +} + +// GetSearchDomains returns search domains (if any) listed in /etc/resolv.conf +// If more than one search line is encountered, only the contents of the last +// one is returned. +func GetSearchDomains(resolvConf []byte) []string { + domains := []string{} + for _, line := range getLines(resolvConf, []byte("#")) { + match := searchRegexp.FindSubmatch(line) + if match == nil { + continue + } + domains = strings.Fields(string(match[1])) + } + return domains +} + +// Build writes a configuration file to path containing a "nameserver" entry +// for every element in dns, and a "search" entry for every element in +// dnsSearch. +func Build(path string, dns, dnsSearch []string) error { + content := bytes.NewBuffer(nil) + for _, dns := range dns { + if _, err := content.WriteString("nameserver " + dns + "\n"); err != nil { + return err + } + } + if len(dnsSearch) > 0 { + if searchString := strings.Join(dnsSearch, " "); strings.Trim(searchString, " ") != "." { + if _, err := content.WriteString("search " + searchString + "\n"); err != nil { + return err + } + } + } + + return ioutil.WriteFile(path, content.Bytes(), 0644) +} diff --git a/libnetwork/pkg/resolvconf/resolvconf_test.go b/libnetwork/pkg/resolvconf/resolvconf_test.go new file mode 100644 index 0000000000..dfb0a053f9 --- /dev/null +++ b/libnetwork/pkg/resolvconf/resolvconf_test.go @@ -0,0 +1,238 @@ +package resolvconf + +import ( + "bytes" + "io/ioutil" + "os" + "testing" +) + +func TestGet(t *testing.T) { + resolvConfUtils, err := Get() + if err != nil { + t.Fatal(err) + } + resolvConfSystem, err := ioutil.ReadFile("/etc/resolv.conf") + if err != nil { + t.Fatal(err) + } + if string(resolvConfUtils) != string(resolvConfSystem) { + t.Fatalf("/etc/resolv.conf and GetResolvConf have different content.") + } +} + +func TestGetNameservers(t *testing.T) { + for resolv, result := range map[string][]string{` +nameserver 1.2.3.4 +nameserver 40.3.200.10 +search example.com`: {"1.2.3.4", "40.3.200.10"}, + `search example.com`: {}, + `nameserver 1.2.3.4 +search example.com +nameserver 4.30.20.100`: {"1.2.3.4", "4.30.20.100"}, + ``: {}, + ` nameserver 1.2.3.4 `: {"1.2.3.4"}, + `search example.com +nameserver 1.2.3.4 +#nameserver 4.3.2.1`: {"1.2.3.4"}, + `search example.com +nameserver 1.2.3.4 # not 4.3.2.1`: {"1.2.3.4"}, + } { + test := GetNameservers([]byte(resolv)) + if !strSlicesEqual(test, result) { + t.Fatalf("Wrong nameserver string {%s} should be %v. Input: %s", test, result, resolv) + } + } +} + +func TestGetNameserversAsCIDR(t *testing.T) { + for resolv, result := range map[string][]string{` +nameserver 1.2.3.4 +nameserver 40.3.200.10 +search example.com`: {"1.2.3.4/32", "40.3.200.10/32"}, + `search example.com`: {}, + `nameserver 1.2.3.4 +search example.com +nameserver 4.30.20.100`: {"1.2.3.4/32", "4.30.20.100/32"}, + ``: {}, + ` nameserver 1.2.3.4 `: {"1.2.3.4/32"}, + `search example.com +nameserver 1.2.3.4 +#nameserver 4.3.2.1`: {"1.2.3.4/32"}, + `search example.com +nameserver 1.2.3.4 # not 4.3.2.1`: {"1.2.3.4/32"}, + } { + test := GetNameserversAsCIDR([]byte(resolv)) + if !strSlicesEqual(test, result) { + t.Fatalf("Wrong nameserver string {%s} should be %v. Input: %s", test, result, resolv) + } + } +} + +func TestGetSearchDomains(t *testing.T) { + for resolv, result := range map[string][]string{ + `search example.com`: {"example.com"}, + `search example.com # ignored`: {"example.com"}, + ` search example.com `: {"example.com"}, + ` search example.com # ignored`: {"example.com"}, + `search foo.example.com example.com`: {"foo.example.com", "example.com"}, + ` search foo.example.com example.com `: {"foo.example.com", "example.com"}, + ` search foo.example.com example.com # ignored`: {"foo.example.com", "example.com"}, + ``: {}, + `# ignored`: {}, + `nameserver 1.2.3.4 +search foo.example.com example.com`: {"foo.example.com", "example.com"}, + `nameserver 1.2.3.4 +search dup1.example.com dup2.example.com +search foo.example.com example.com`: {"foo.example.com", "example.com"}, + `nameserver 1.2.3.4 +search foo.example.com example.com +nameserver 4.30.20.100`: {"foo.example.com", "example.com"}, + } { + test := GetSearchDomains([]byte(resolv)) + if !strSlicesEqual(test, result) { + t.Fatalf("Wrong search domain string {%s} should be %v. Input: %s", test, result, resolv) + } + } +} + +func strSlicesEqual(a, b []string) bool { + if len(a) != len(b) { + return false + } + + for i, v := range a { + if v != b[i] { + return false + } + } + + return true +} + +func TestBuild(t *testing.T) { + file, err := ioutil.TempFile("", "") + if err != nil { + t.Fatal(err) + } + defer os.Remove(file.Name()) + + err = Build(file.Name(), []string{"ns1", "ns2", "ns3"}, []string{"search1"}) + if err != nil { + t.Fatal(err) + } + + content, err := ioutil.ReadFile(file.Name()) + if err != nil { + t.Fatal(err) + } + + if expected := "nameserver ns1\nnameserver ns2\nnameserver ns3\nsearch search1\n"; !bytes.Contains(content, []byte(expected)) { + t.Fatalf("Expected to find '%s' got '%s'", expected, content) + } +} + +func TestBuildWithZeroLengthDomainSearch(t *testing.T) { + file, err := ioutil.TempFile("", "") + if err != nil { + t.Fatal(err) + } + defer os.Remove(file.Name()) + + err = Build(file.Name(), []string{"ns1", "ns2", "ns3"}, []string{"."}) + if err != nil { + t.Fatal(err) + } + + content, err := ioutil.ReadFile(file.Name()) + if err != nil { + t.Fatal(err) + } + + if expected := "nameserver ns1\nnameserver ns2\nnameserver ns3\n"; !bytes.Contains(content, []byte(expected)) { + t.Fatalf("Expected to find '%s' got '%s'", expected, content) + } + if notExpected := "search ."; bytes.Contains(content, []byte(notExpected)) { + t.Fatalf("Expected to not find '%s' got '%s'", notExpected, content) + } +} + +func TestFilterResolvDns(t *testing.T) { + ns0 := "nameserver 10.16.60.14\nnameserver 10.16.60.21\n" + + if result, _ := FilterResolvDNS([]byte(ns0), false); result != nil { + if ns0 != string(result) { + t.Fatalf("Failed No Localhost: expected \n<%s> got \n<%s>", ns0, string(result)) + } + } + + ns1 := "nameserver 10.16.60.14\nnameserver 10.16.60.21\nnameserver 127.0.0.1\n" + if result, _ := FilterResolvDNS([]byte(ns1), false); result != nil { + if ns0 != string(result) { + t.Fatalf("Failed Localhost: expected \n<%s> got \n<%s>", ns0, string(result)) + } + } + + ns1 = "nameserver 10.16.60.14\nnameserver 127.0.0.1\nnameserver 10.16.60.21\n" + if result, _ := FilterResolvDNS([]byte(ns1), false); result != nil { + if ns0 != string(result) { + t.Fatalf("Failed Localhost: expected \n<%s> got \n<%s>", ns0, string(result)) + } + } + + ns1 = "nameserver 127.0.1.1\nnameserver 10.16.60.14\nnameserver 10.16.60.21\n" + if result, _ := FilterResolvDNS([]byte(ns1), false); result != nil { + if ns0 != string(result) { + t.Fatalf("Failed Localhost: expected \n<%s> got \n<%s>", ns0, string(result)) + } + } + + ns1 = "nameserver ::1\nnameserver 10.16.60.14\nnameserver 127.0.2.1\nnameserver 10.16.60.21\n" + if result, _ := FilterResolvDNS([]byte(ns1), false); result != nil { + if ns0 != string(result) { + t.Fatalf("Failed Localhost: expected \n<%s> got \n<%s>", ns0, string(result)) + } + } + + ns1 = "nameserver 10.16.60.14\nnameserver ::1\nnameserver 10.16.60.21\nnameserver ::1" + if result, _ := FilterResolvDNS([]byte(ns1), false); result != nil { + if ns0 != string(result) { + t.Fatalf("Failed Localhost: expected \n<%s> got \n<%s>", ns0, string(result)) + } + } + + // with IPv6 disabled (false param), the IPv6 nameserver should be removed + ns1 = "nameserver 10.16.60.14\nnameserver 2002:dead:beef::1\nnameserver 10.16.60.21\nnameserver ::1" + if result, _ := FilterResolvDNS([]byte(ns1), false); result != nil { + if ns0 != string(result) { + t.Fatalf("Failed Localhost+IPv6 off: expected \n<%s> got \n<%s>", ns0, string(result)) + } + } + + // with IPv6 enabled, the IPv6 nameserver should be preserved + ns0 = "nameserver 10.16.60.14\nnameserver 2002:dead:beef::1\nnameserver 10.16.60.21\n" + ns1 = "nameserver 10.16.60.14\nnameserver 2002:dead:beef::1\nnameserver 10.16.60.21\nnameserver ::1" + if result, _ := FilterResolvDNS([]byte(ns1), true); result != nil { + if ns0 != string(result) { + t.Fatalf("Failed Localhost+IPv6 on: expected \n<%s> got \n<%s>", ns0, string(result)) + } + } + + // with IPv6 enabled, and no non-localhost servers, Google defaults (both IPv4+IPv6) should be added + ns0 = "\nnameserver 8.8.8.8\nnameserver 8.8.4.4\nnameserver 2001:4860:4860::8888\nnameserver 2001:4860:4860::8844" + ns1 = "nameserver 127.0.0.1\nnameserver ::1\nnameserver 127.0.2.1" + if result, _ := FilterResolvDNS([]byte(ns1), true); result != nil { + if ns0 != string(result) { + t.Fatalf("Failed no Localhost+IPv6 enabled: expected \n<%s> got \n<%s>", ns0, string(result)) + } + } + + // with IPv6 disabled, and no non-localhost servers, Google defaults (only IPv4) should be added + ns0 = "\nnameserver 8.8.8.8\nnameserver 8.8.4.4" + ns1 = "nameserver 127.0.0.1\nnameserver ::1\nnameserver 127.0.2.1" + if result, _ := FilterResolvDNS([]byte(ns1), false); result != nil { + if ns0 != string(result) { + t.Fatalf("Failed no Localhost+IPv6 enabled: expected \n<%s> got \n<%s>", ns0, string(result)) + } + } +}