use resolvconf package from c/common/libnetwork

Podman and Buildah should use the same code the generate the resolv.conf
file. This mostly moved the podman code into c/common and created a
better API for it so buildah can use it as well.

[NO NEW TESTS NEEDED] All existing tests should continue to pass.

Fixes #13599 (There is no way to test this in CI without breaking the
hosts resolv.conf)

Signed-off-by: Paul Holzinger <pholzing@redhat.com>

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)
-}