diff options
Diffstat (limited to 'vendor/github.com/docker/libnetwork/resolvconf/resolvconf.go')
| -rw-r--r-- | vendor/github.com/docker/libnetwork/resolvconf/resolvconf.go | 285 |
1 files changed, 0 insertions, 285 deletions
diff --git a/vendor/github.com/docker/libnetwork/resolvconf/resolvconf.go b/vendor/github.com/docker/libnetwork/resolvconf/resolvconf.go deleted file mode 100644 index 946bb8712..000000000 --- a/vendor/github.com/docker/libnetwork/resolvconf/resolvconf.go +++ /dev/null @@ -1,285 +0,0 @@ -// 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/docker/docker/pkg/ioutils" - "github.com/docker/libnetwork/resolvconf/dns" - "github.com/docker/libnetwork/types" - "github.com/sirupsen/logrus" -) - -const ( - // defaultPath is the default path to the resolv.conf that contains information to resolve DNS. See Path(). - defaultPath = "/etc/resolv.conf" - // alternatePath is a path different from defaultPath, that may be used to resolve DNS. See Path(). - alternatePath = "/run/systemd/resolve/resolv.conf" -) - -var ( - detectSystemdResolvConfOnce sync.Once - pathAfterSystemdDetection = defaultPath -) - -// Path returns the path to the resolv.conf file that libnetwork should use. -// -// When /etc/resolv.conf contains 127.0.0.53 as the only nameserver, then -// it is assumed systemd-resolved manages DNS. Because inside the container 127.0.0.53 -// is not a valid DNS server, Path() returns /run/systemd/resolve/resolv.conf -// which is the resolv.conf that systemd-resolved generates and manages. -// Otherwise Path() returns /etc/resolv.conf. -// -// Errors are silenced as they will inevitably resurface at future open/read calls. -// -// More information at https://www.freedesktop.org/software/systemd/man/systemd-resolved.service.html#/etc/resolv.conf -func Path() string { - detectSystemdResolvConfOnce.Do(func() { - candidateResolvConf, err := ioutil.ReadFile(defaultPath) - if err != nil { - // silencing error as it will resurface at next calls trying to read defaultPath - return - } - ns := GetNameservers(candidateResolvConf, types.IP) - if len(ns) == 1 && ns[0] == "127.0.0.53" { - pathAfterSystemdDetection = alternatePath - logrus.Infof("detected 127.0.0.53 nameserver, assuming systemd-resolved, so using resolv.conf: %s", alternatePath) - } - }) - return pathAfterSystemdDetection -} - -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})(%\w+)?` - - localhostNSRegexp = regexp.MustCompile(`(?m)^nameserver\s+` + dns.IPLocalhost + `\s*\n*`) - nsIPv6Regexp = regexp.MustCompile(`(?m)^nameserver\s+` + ipv6Address + `\s*\n*`) - nsRegexp = regexp.MustCompile(`^\s*nameserver\s*((` + ipv4Address + `)|(` + ipv6Address + `))\s*$`) - nsIPv6Regexpmatch = regexp.MustCompile(`^\s*nameserver\s*((` + ipv6Address + `))\s*$`) - nsIPv4Regexpmatch = regexp.MustCompile(`^\s*nameserver\s*((` + ipv4Address + `))\s*$`) - searchRegexp = regexp.MustCompile(`^\s*search\s*(([^\s]+\s*)*)$`) - optionsRegexp = regexp.MustCompile(`^\s*options\s*(([^\s]+\s*)*)$`) -) - -var lastModified struct { - sync.Mutex - sha256 string - contents []byte -} - -// File contains the resolv.conf content and its hash -type File struct { - Content []byte - Hash string -} - -// Get returns the contents of /etc/resolv.conf and its hash -func Get() (*File, error) { - return GetSpecific(Path()) -} - -// GetSpecific returns the contents of the user specified resolv.conf file and its hash -func GetSpecific(path string) (*File, error) { - resolv, err := ioutil.ReadFile(path) - if err != nil { - return nil, err - } - hash, err := ioutils.HashData(bytes.NewReader(resolv)) - if err != nil { - return nil, err - } - return &File{Content: resolv, Hash: hash}, 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() (*File, error) { - lastModified.Lock() - defer lastModified.Unlock() - - resolv, err := ioutil.ReadFile(Path()) - 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 &File{Content: resolv, Hash: 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() *File { - lastModified.Lock() - defer lastModified.Unlock() - - return &File{Content: lastModified.contents, Hash: 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 -// -func FilterResolvDNS(resolvConf []byte, ipv6Enabled bool) (*File, error) { - 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, types.IP)) == 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"))...) - } - hash, err := ioutils.HashData(bytes.NewReader(cleanedResolvConf)) - if err != nil { - return nil, err - } - return &File{Content: cleanedResolvConf, Hash: hash}, nil -} - -// 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 -} - -// GetNameservers returns nameservers (if any) listed in /etc/resolv.conf -func GetNameservers(resolvConf []byte, kind int) []string { - nameservers := []string{} - for _, line := range getLines(resolvConf, []byte("#")) { - var ns [][]byte - if kind == types.IP { - ns = nsRegexp.FindSubmatch(line) - } else if kind == types.IPv4 { - ns = nsIPv4Regexpmatch.FindSubmatch(line) - } else if kind == types.IPv6 { - ns = nsIPv6Regexpmatch.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, types.IP) { - var address string - // If IPv6, strip zone if present - if strings.Contains(nameserver, ":") { - address = strings.Split(nameserver, "%")[0] + "/128" - } else { - address = nameserver + "/32" - } - nameservers = append(nameservers, address) - } - 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 -} - -// GetOptions returns options (if any) listed in /etc/resolv.conf -// If more than one options line is encountered, only the contents of the last -// one is returned. -func GetOptions(resolvConf []byte) []string { - options := []string{} - for _, line := range getLines(resolvConf, []byte("#")) { - match := optionsRegexp.FindSubmatch(line) - if match == nil { - continue - } - options = strings.Fields(string(match[1])) - } - return options -} - -// Build writes a configuration file to path containing a "nameserver" entry -// for every element in dns, a "search" entry for every element in -// dnsSearch, and an "options" entry for every element in dnsOptions. -func Build(path string, dns, dnsSearch, dnsOptions []string) (*File, error) { - content := bytes.NewBuffer(nil) - if len(dnsSearch) > 0 { - if searchString := strings.Join(dnsSearch, " "); strings.Trim(searchString, " ") != "." { - if _, err := content.WriteString("search " + searchString + "\n"); err != nil { - return nil, err - } - } - } - for _, dns := range dns { - if _, err := content.WriteString("nameserver " + dns + "\n"); err != nil { - return nil, err - } - } - if len(dnsOptions) > 0 { - if optsString := strings.Join(dnsOptions, " "); strings.Trim(optsString, " ") != "" { - if _, err := content.WriteString("options " + optsString + "\n"); err != nil { - return nil, err - } - } - } - - hash, err := ioutils.HashData(bytes.NewReader(content.Bytes())) - if err != nil { - return nil, err - } - - return &File{Content: content.Bytes(), Hash: hash}, ioutil.WriteFile(path, content.Bytes(), 0644) -} |