diff options
Diffstat (limited to 'pkg/resolvconf')
-rw-r--r-- | pkg/resolvconf/dns/resolvconf.go | 28 | ||||
-rw-r--r-- | pkg/resolvconf/resolvconf.go | 250 |
2 files changed, 0 insertions, 278 deletions
diff --git a/pkg/resolvconf/dns/resolvconf.go b/pkg/resolvconf/dns/resolvconf.go deleted file mode 100644 index cb4bd1033..000000000 --- a/pkg/resolvconf/dns/resolvconf.go +++ /dev/null @@ -1,28 +0,0 @@ -// Originally from github.com/docker/libnetwork/resolvconf/dns - -package dns - -import ( - "regexp" -) - -// IPLocalhost is a regex pattern for IPv4 or IPv6 loopback range. -const IPLocalhost = `((127\.([0-9]{1,3}\.){2}[0-9]{1,3})|(::1)$)` - -// IPv4Localhost is a regex pattern for IPv4 localhost address range. -const IPv4Localhost = `(127\.([0-9]{1,3}\.){2}[0-9]{1,3})` - -var localhostIPRegexp = regexp.MustCompile(IPLocalhost) -var localhostIPv4Regexp = regexp.MustCompile(IPv4Localhost) - -// 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) -} - -// IsIPv4Localhost returns true if ip matches the IPv4 localhost regular expression. -func IsIPv4Localhost(ip string) bool { - return localhostIPv4Regexp.MatchString(ip) -} diff --git a/pkg/resolvconf/resolvconf.go b/pkg/resolvconf/resolvconf.go deleted file mode 100644 index f23cd61b0..000000000 --- a/pkg/resolvconf/resolvconf.go +++ /dev/null @@ -1,250 +0,0 @@ -// Package resolvconf provides utility code to query and update DNS configuration in /etc/resolv.conf. -// Originally from github.com/docker/libnetwork/resolvconf. -package resolvconf - -import ( - "bytes" - "io/ioutil" - "regexp" - "strings" - "sync" - - "github.com/containers/podman/v4/pkg/resolvconf/dns" - "github.com/containers/storage/pkg/ioutils" - "github.com/sirupsen/logrus" -) - -const ( - // DefaultResolvConf points to the default file used for dns configuration on a linux machine - DefaultResolvConf = "/etc/resolv.conf" -) - -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*$`) - 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(DefaultResolvConf) -} - -// 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("/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 &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. If a netns is enabled, 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, netnsEnabled bool) (*File, error) { - // If we're using the host netns, we have nothing to do besides hash the file. - if !netnsEnabled { - hash, err := ioutils.HashData(bytes.NewReader(resolvConf)) - if err != nil { - return nil, err - } - return &File{Content: resolvConf, Hash: hash}, nil - } - 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"))...) - } - 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) []string { - nameservers := []string{} - for _, line := range getLines(resolvConf, []byte("#")) { - 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) { - 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) -} |