mirror of
https://github.com/netbirdio/netbird.git
synced 2024-11-25 17:43:38 +01:00
299 lines
8.9 KiB
Go
299 lines
8.9 KiB
Go
//go:build !ios
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package dns
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import (
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"bufio"
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"bytes"
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"fmt"
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"io"
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"net/netip"
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"os/exec"
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"strconv"
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"strings"
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log "github.com/sirupsen/logrus"
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)
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const (
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netbirdDNSStateKeyFormat = "State:/Network/Service/NetBird-%s/DNS"
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globalIPv4State = "State:/Network/Global/IPv4"
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primaryServiceSetupKeyFormat = "Setup:/Network/Service/%s/DNS"
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keySupplementalMatchDomains = "SupplementalMatchDomains"
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keySupplementalMatchDomainsNoSearch = "SupplementalMatchDomainsNoSearch"
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keyServerAddresses = "ServerAddresses"
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keyServerPort = "ServerPort"
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arraySymbol = "* "
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digitSymbol = "# "
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scutilPath = "/usr/sbin/scutil"
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searchSuffix = "Search"
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matchSuffix = "Match"
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)
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type systemConfigurator struct {
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// primaryServiceID primary interface in the system. AKA the interface with the default route
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primaryServiceID string
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createdKeys map[string]struct{}
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}
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func newHostManager() (hostManager, error) {
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return &systemConfigurator{
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createdKeys: make(map[string]struct{}),
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}, nil
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}
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func (s *systemConfigurator) supportCustomPort() bool {
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return true
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}
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func (s *systemConfigurator) applyDNSConfig(config HostDNSConfig) error {
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var err error
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if config.RouteAll {
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err = s.addDNSSetupForAll(config.ServerIP, config.ServerPort)
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if err != nil {
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return fmt.Errorf("add dns setup for all: %w", err)
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}
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} else if s.primaryServiceID != "" {
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err = s.removeKeyFromSystemConfig(getKeyWithInput(primaryServiceSetupKeyFormat, s.primaryServiceID))
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if err != nil {
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return fmt.Errorf("remote key from system config: %w", err)
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}
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s.primaryServiceID = ""
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log.Infof("removed %s:%d as main DNS resolver for this peer", config.ServerIP, config.ServerPort)
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}
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// create a file for unclean shutdown detection
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if err := createUncleanShutdownIndicator(); err != nil {
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log.Errorf("failed to create unclean shutdown file: %s", err)
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}
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var (
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searchDomains []string
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matchDomains []string
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)
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for _, dConf := range config.Domains {
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if dConf.Disabled {
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continue
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}
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if dConf.MatchOnly {
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matchDomains = append(matchDomains, dConf.Domain)
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continue
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}
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searchDomains = append(searchDomains, dConf.Domain)
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}
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matchKey := getKeyWithInput(netbirdDNSStateKeyFormat, matchSuffix)
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if len(matchDomains) != 0 {
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err = s.addMatchDomains(matchKey, strings.Join(matchDomains, " "), config.ServerIP, config.ServerPort)
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} else {
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log.Infof("removing match domains from the system")
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err = s.removeKeyFromSystemConfig(matchKey)
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}
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if err != nil {
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return fmt.Errorf("add match domains: %w", err)
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}
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searchKey := getKeyWithInput(netbirdDNSStateKeyFormat, searchSuffix)
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if len(searchDomains) != 0 {
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err = s.addSearchDomains(searchKey, strings.Join(searchDomains, " "), config.ServerIP, config.ServerPort)
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} else {
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log.Infof("removing search domains from the system")
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err = s.removeKeyFromSystemConfig(searchKey)
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}
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if err != nil {
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return fmt.Errorf("add search domains: %w", err)
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}
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return nil
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}
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func (s *systemConfigurator) restoreHostDNS() error {
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lines := ""
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for key := range s.createdKeys {
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lines += buildRemoveKeyOperation(key)
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keyType := "search"
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if strings.Contains(key, matchSuffix) {
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keyType = "match"
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}
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log.Infof("removing %s domains from system", keyType)
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}
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if s.primaryServiceID != "" {
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lines += buildRemoveKeyOperation(getKeyWithInput(primaryServiceSetupKeyFormat, s.primaryServiceID))
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log.Infof("restoring DNS resolver configuration for system")
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}
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_, err := runSystemConfigCommand(wrapCommand(lines))
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if err != nil {
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log.Errorf("got an error while cleaning the system configuration: %s", err)
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return fmt.Errorf("clean system: %w", err)
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}
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if err := removeUncleanShutdownIndicator(); err != nil {
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log.Errorf("failed to remove unclean shutdown file: %s", err)
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}
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return nil
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}
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func (s *systemConfigurator) removeKeyFromSystemConfig(key string) error {
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line := buildRemoveKeyOperation(key)
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_, err := runSystemConfigCommand(wrapCommand(line))
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if err != nil {
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return fmt.Errorf("remove key: %w", err)
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}
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delete(s.createdKeys, key)
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return nil
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}
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func (s *systemConfigurator) addSearchDomains(key, domains string, ip string, port int) error {
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err := s.addDNSState(key, domains, ip, port, true)
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if err != nil {
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return fmt.Errorf("add dns state: %w", err)
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}
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log.Infof("added %d search domains to the state. Domain list: %s", len(strings.Split(domains, " ")), domains)
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s.createdKeys[key] = struct{}{}
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return nil
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}
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func (s *systemConfigurator) addMatchDomains(key, domains, dnsServer string, port int) error {
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err := s.addDNSState(key, domains, dnsServer, port, false)
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if err != nil {
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return fmt.Errorf("add dns state: %w", err)
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}
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log.Infof("added %d match domains to the state. Domain list: %s", len(strings.Split(domains, " ")), domains)
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s.createdKeys[key] = struct{}{}
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return nil
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}
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func (s *systemConfigurator) addDNSState(state, domains, dnsServer string, port int, enableSearch bool) error {
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noSearch := "1"
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if enableSearch {
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noSearch = "0"
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}
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lines := buildAddCommandLine(keySupplementalMatchDomains, arraySymbol+domains)
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lines += buildAddCommandLine(keySupplementalMatchDomainsNoSearch, digitSymbol+noSearch)
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lines += buildAddCommandLine(keyServerAddresses, arraySymbol+dnsServer)
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lines += buildAddCommandLine(keyServerPort, digitSymbol+strconv.Itoa(port))
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addDomainCommand := buildCreateStateWithOperation(state, lines)
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stdinCommands := wrapCommand(addDomainCommand)
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_, err := runSystemConfigCommand(stdinCommands)
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if err != nil {
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return fmt.Errorf("applying state for domains %s, error: %w", domains, err)
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}
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return nil
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}
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func (s *systemConfigurator) addDNSSetupForAll(dnsServer string, port int) error {
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primaryServiceKey, existingNameserver, err := s.getPrimaryService()
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if err != nil || primaryServiceKey == "" {
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return fmt.Errorf("couldn't find the primary service key: %w", err)
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}
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err = s.addDNSSetup(getKeyWithInput(primaryServiceSetupKeyFormat, primaryServiceKey), dnsServer, port, existingNameserver)
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if err != nil {
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return fmt.Errorf("add dns setup: %w", err)
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}
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log.Infof("configured %s:%d as main DNS resolver for this peer", dnsServer, port)
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s.primaryServiceID = primaryServiceKey
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return nil
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}
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func (s *systemConfigurator) getPrimaryService() (string, string, error) {
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line := buildCommandLine("show", globalIPv4State, "")
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stdinCommands := wrapCommand(line)
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b, err := runSystemConfigCommand(stdinCommands)
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if err != nil {
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return "", "", fmt.Errorf("sending the command: %w", err)
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}
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scanner := bufio.NewScanner(bytes.NewReader(b))
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primaryService := ""
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router := ""
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for scanner.Scan() {
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text := scanner.Text()
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if strings.Contains(text, "PrimaryService") {
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primaryService = strings.TrimSpace(strings.Split(text, ":")[1])
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}
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if strings.Contains(text, "Router") {
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router = strings.TrimSpace(strings.Split(text, ":")[1])
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}
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}
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if err := scanner.Err(); err != nil && err != io.EOF {
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return primaryService, router, fmt.Errorf("scan: %w", err)
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}
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return primaryService, router, nil
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}
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func (s *systemConfigurator) addDNSSetup(setupKey, dnsServer string, port int, existingDNSServer string) error {
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lines := buildAddCommandLine(keySupplementalMatchDomainsNoSearch, digitSymbol+strconv.Itoa(0))
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lines += buildAddCommandLine(keyServerAddresses, arraySymbol+dnsServer+" "+existingDNSServer)
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lines += buildAddCommandLine(keyServerPort, digitSymbol+strconv.Itoa(port))
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addDomainCommand := buildCreateStateWithOperation(setupKey, lines)
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stdinCommands := wrapCommand(addDomainCommand)
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_, err := runSystemConfigCommand(stdinCommands)
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if err != nil {
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return fmt.Errorf("applying dns setup, error: %w", err)
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}
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return nil
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}
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func (s *systemConfigurator) restoreUncleanShutdownDNS(*netip.Addr) error {
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if err := s.restoreHostDNS(); err != nil {
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return fmt.Errorf("restoring dns via scutil: %w", err)
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}
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return nil
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}
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func getKeyWithInput(format, key string) string {
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return fmt.Sprintf(format, key)
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}
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func buildAddCommandLine(key, value string) string {
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return buildCommandLine("d.add", key, value)
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}
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func buildCommandLine(action, key, value string) string {
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return fmt.Sprintf("%s %s %s\n", action, key, value)
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}
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func wrapCommand(commands string) string {
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return fmt.Sprintf("open\n%s\nquit\n", commands)
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}
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func buildRemoveKeyOperation(key string) string {
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return fmt.Sprintf("remove %s\n", key)
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}
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func buildCreateStateWithOperation(state, commands string) string {
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return buildWriteStateOperation("set", state, commands)
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}
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func buildWriteStateOperation(operation, state, commands string) string {
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return fmt.Sprintf("d.init\n%s %s\n%s\nset %s\n", operation, state, commands, state)
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}
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func runSystemConfigCommand(command string) ([]byte, error) {
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cmd := exec.Command(scutilPath)
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cmd.Stdin = strings.NewReader(command)
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out, err := cmd.Output()
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if err != nil {
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return nil, fmt.Errorf("running system configuration command: \"%s\", error: %w", command, err)
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}
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return out, nil
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}
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