add resolvconf
Docker-DCO-1.1-Signed-off-by: Victor Vieux <vieux@docker.com> (github: vieux)
This commit is contained in:
Victor Vieux
parent
05227e1d6f
commit
5b4c76a6d6
2 changed files with 220 additions and 0 deletions
87
networkfs/resolvconf/resolvconf.go
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87
networkfs/resolvconf/resolvconf.go
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package resolvconf
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import (
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"bytes"
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"io/ioutil"
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"regexp"
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"strings"
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)
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func Get() ([]byte, error) {
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resolv, err := ioutil.ReadFile("/etc/resolv.conf")
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if err != nil {
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return nil, err
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}
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return resolv, nil
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}
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// getLines parses input into lines and strips away comments.
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func getLines(input []byte, commentMarker []byte) [][]byte {
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lines := bytes.Split(input, []byte("\n"))
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var output [][]byte
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for _, currentLine := range lines {
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var commentIndex = bytes.Index(currentLine, commentMarker)
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if commentIndex == -1 {
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output = append(output, currentLine)
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} else {
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output = append(output, currentLine[:commentIndex])
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}
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}
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return output
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}
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// GetNameservers returns nameservers (if any) listed in /etc/resolv.conf
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func GetNameservers(resolvConf []byte) []string {
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nameservers := []string{}
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re := regexp.MustCompile(`^\s*nameserver\s*(([0-9]+\.){3}([0-9]+))\s*$`)
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for _, line := range getLines(resolvConf, []byte("#")) {
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var ns = re.FindSubmatch(line)
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if len(ns) > 0 {
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nameservers = append(nameservers, string(ns[1]))
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}
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}
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return nameservers
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}
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// GetNameserversAsCIDR returns nameservers (if any) listed in
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// /etc/resolv.conf as CIDR blocks (e.g., "1.2.3.4/32")
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// This function's output is intended for net.ParseCIDR
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func GetNameserversAsCIDR(resolvConf []byte) []string {
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nameservers := []string{}
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for _, nameserver := range GetNameservers(resolvConf) {
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nameservers = append(nameservers, nameserver+"/32")
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}
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return nameservers
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}
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// GetSearchDomains returns search domains (if any) listed in /etc/resolv.conf
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// If more than one search line is encountered, only the contents of the last
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// one is returned.
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func GetSearchDomains(resolvConf []byte) []string {
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re := regexp.MustCompile(`^\s*search\s*(([^\s]+\s*)*)$`)
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domains := []string{}
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for _, line := range getLines(resolvConf, []byte("#")) {
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match := re.FindSubmatch(line)
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if match == nil {
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continue
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}
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domains = strings.Fields(string(match[1]))
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}
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return domains
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}
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func Build(path string, dns, dnsSearch []string) error {
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content := bytes.NewBuffer(nil)
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for _, dns := range dns {
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if _, err := content.WriteString("nameserver " + dns + "\n"); err != nil {
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return err
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}
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}
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if len(dnsSearch) > 0 {
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if _, err := content.WriteString("search " + strings.Join(dnsSearch, " ") + "\n"); err != nil {
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return err
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}
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}
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return ioutil.WriteFile(path, content.Bytes(), 0644)
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}
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133
networkfs/resolvconf/resolvconf_test.go
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133
networkfs/resolvconf/resolvconf_test.go
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package resolvconf
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import (
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"bytes"
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"io/ioutil"
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"os"
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"testing"
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)
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func TestGet(t *testing.T) {
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resolvConfUtils, err := Get()
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if err != nil {
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t.Fatal(err)
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}
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resolvConfSystem, err := ioutil.ReadFile("/etc/resolv.conf")
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if err != nil {
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t.Fatal(err)
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}
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if string(resolvConfUtils) != string(resolvConfSystem) {
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t.Fatalf("/etc/resolv.conf and GetResolvConf have different content.")
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}
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}
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func TestGetNameservers(t *testing.T) {
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for resolv, result := range map[string][]string{`
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nameserver 1.2.3.4
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nameserver 40.3.200.10
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search example.com`: {"1.2.3.4", "40.3.200.10"},
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`search example.com`: {},
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`nameserver 1.2.3.4
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search example.com
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nameserver 4.30.20.100`: {"1.2.3.4", "4.30.20.100"},
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``: {},
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` nameserver 1.2.3.4 `: {"1.2.3.4"},
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`search example.com
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nameserver 1.2.3.4
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#nameserver 4.3.2.1`: {"1.2.3.4"},
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`search example.com
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nameserver 1.2.3.4 # not 4.3.2.1`: {"1.2.3.4"},
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} {
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test := GetNameservers([]byte(resolv))
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if !strSlicesEqual(test, result) {
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t.Fatalf("Wrong nameserver string {%s} should be %v. Input: %s", test, result, resolv)
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}
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}
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}
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func TestGetNameserversAsCIDR(t *testing.T) {
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for resolv, result := range map[string][]string{`
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nameserver 1.2.3.4
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nameserver 40.3.200.10
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search example.com`: {"1.2.3.4/32", "40.3.200.10/32"},
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`search example.com`: {},
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`nameserver 1.2.3.4
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search example.com
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nameserver 4.30.20.100`: {"1.2.3.4/32", "4.30.20.100/32"},
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``: {},
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` nameserver 1.2.3.4 `: {"1.2.3.4/32"},
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`search example.com
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nameserver 1.2.3.4
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#nameserver 4.3.2.1`: {"1.2.3.4/32"},
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`search example.com
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nameserver 1.2.3.4 # not 4.3.2.1`: {"1.2.3.4/32"},
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} {
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test := GetNameserversAsCIDR([]byte(resolv))
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if !strSlicesEqual(test, result) {
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t.Fatalf("Wrong nameserver string {%s} should be %v. Input: %s", test, result, resolv)
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}
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}
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}
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func TestGetSearchDomains(t *testing.T) {
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for resolv, result := range map[string][]string{
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`search example.com`: {"example.com"},
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`search example.com # ignored`: {"example.com"},
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` search example.com `: {"example.com"},
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` search example.com # ignored`: {"example.com"},
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`search foo.example.com example.com`: {"foo.example.com", "example.com"},
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` search foo.example.com example.com `: {"foo.example.com", "example.com"},
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` search foo.example.com example.com # ignored`: {"foo.example.com", "example.com"},
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``: {},
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`# ignored`: {},
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`nameserver 1.2.3.4
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search foo.example.com example.com`: {"foo.example.com", "example.com"},
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`nameserver 1.2.3.4
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search dup1.example.com dup2.example.com
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search foo.example.com example.com`: {"foo.example.com", "example.com"},
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`nameserver 1.2.3.4
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search foo.example.com example.com
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nameserver 4.30.20.100`: {"foo.example.com", "example.com"},
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} {
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test := GetSearchDomains([]byte(resolv))
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if !strSlicesEqual(test, result) {
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t.Fatalf("Wrong search domain string {%s} should be %v. Input: %s", test, result, resolv)
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}
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}
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}
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func strSlicesEqual(a, b []string) bool {
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if len(a) != len(b) {
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return false
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}
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for i, v := range a {
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if v != b[i] {
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return false
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}
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}
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return true
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}
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func TestBuild(t *testing.T) {
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file, err := ioutil.TempFile("", "")
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if err != nil {
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t.Fatal(err)
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}
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defer os.Remove(file.Name())
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err = Build(file.Name(), []string{"ns1", "ns2", "ns3"}, []string{"search1"})
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if err != nil {
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t.Fatal(err)
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}
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content, err := ioutil.ReadFile(file.Name())
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if err != nil {
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t.Fatal(err)
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}
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if expected := "nameserver ns1\nnameserver ns2\nnameserver ns3\nsearch search1\n"; !bytes.Contains(content, []byte(expected)) {
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t.Fatalf("Expected to find '%s' got '%s'", expected, content)
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}
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}
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