Update Lego

vendor/github.com/xenolf/lego/challenge/dns01/nameserver.go

@@ -0,0 +1,232 @@
+package dns01
+
+import (
+	"fmt"
+	"net"
+	"strings"
+	"sync"
+	"time"
+
+	"github.com/miekg/dns"
+)
+
+const defaultResolvConf = "/etc/resolv.conf"
+
+// dnsTimeout is used to override the default DNS timeout of 10 seconds.
+var dnsTimeout = 10 * time.Second
+
+var (
+	fqdnToZone   = map[string]string{}
+	muFqdnToZone sync.Mutex
+)
+
+var defaultNameservers = []string{
+	"google-public-dns-a.google.com:53",
+	"google-public-dns-b.google.com:53",
+}
+
+// recursiveNameservers are used to pre-check DNS propagation
+var recursiveNameservers = getNameservers(defaultResolvConf, defaultNameservers)
+
+// ClearFqdnCache clears the cache of fqdn to zone mappings. Primarily used in testing.
+func ClearFqdnCache() {
+	muFqdnToZone.Lock()
+	fqdnToZone = map[string]string{}
+	muFqdnToZone.Unlock()
+}
+
+func AddDNSTimeout(timeout time.Duration) ChallengeOption {
+	return func(_ *Challenge) error {
+		dnsTimeout = timeout
+		return nil
+	}
+}
+
+func AddRecursiveNameservers(nameservers []string) ChallengeOption {
+	return func(_ *Challenge) error {
+		recursiveNameservers = ParseNameservers(nameservers)
+		return nil
+	}
+}
+
+// getNameservers attempts to get systems nameservers before falling back to the defaults
+func getNameservers(path string, defaults []string) []string {
+	config, err := dns.ClientConfigFromFile(path)
+	if err != nil || len(config.Servers) == 0 {
+		return defaults
+	}
+
+	return ParseNameservers(config.Servers)
+}
+
+func ParseNameservers(servers []string) []string {
+	var resolvers []string
+	for _, resolver := range servers {
+		// ensure all servers have a port number
+		if _, _, err := net.SplitHostPort(resolver); err != nil {
+			resolvers = append(resolvers, net.JoinHostPort(resolver, "53"))
+		} else {
+			resolvers = append(resolvers, resolver)
+		}
+	}
+	return resolvers
+}
+
+// lookupNameservers returns the authoritative nameservers for the given fqdn.
+func lookupNameservers(fqdn string) ([]string, error) {
+	var authoritativeNss []string
+
+	zone, err := FindZoneByFqdn(fqdn)
+	if err != nil {
+		return nil, fmt.Errorf("could not determine the zone: %v", err)
+	}
+
+	r, err := dnsQuery(zone, dns.TypeNS, recursiveNameservers, true)
+	if err != nil {
+		return nil, err
+	}
+
+	for _, rr := range r.Answer {
+		if ns, ok := rr.(*dns.NS); ok {
+			authoritativeNss = append(authoritativeNss, strings.ToLower(ns.Ns))
+		}
+	}
+
+	if len(authoritativeNss) > 0 {
+		return authoritativeNss, nil
+	}
+	return nil, fmt.Errorf("could not determine authoritative nameservers")
+}
+
+// FindZoneByFqdn determines the zone apex for the given fqdn
+// by recursing up the domain labels until the nameserver returns a SOA record in the answer section.
+func FindZoneByFqdn(fqdn string) (string, error) {
+	return FindZoneByFqdnCustom(fqdn, recursiveNameservers)
+}
+
+// FindZoneByFqdnCustom determines the zone apex for the given fqdn
+// by recursing up the domain labels until the nameserver returns a SOA record in the answer section.
+func FindZoneByFqdnCustom(fqdn string, nameservers []string) (string, error) {
+	muFqdnToZone.Lock()
+	defer muFqdnToZone.Unlock()
+
+	// Do we have it cached?
+	if zone, ok := fqdnToZone[fqdn]; ok {
+		return zone, nil
+	}
+
+	var err error
+	var in *dns.Msg
+
+	labelIndexes := dns.Split(fqdn)
+	for _, index := range labelIndexes {
+		domain := fqdn[index:]
+
+		in, err = dnsQuery(domain, dns.TypeSOA, nameservers, true)
+		if err != nil {
+			continue
+		}
+
+		if in == nil {
+			continue
+		}
+
+		switch in.Rcode {
+		case dns.RcodeSuccess:
+			// Check if we got a SOA RR in the answer section
+
+			if len(in.Answer) == 0 {
+				continue
+			}
+
+			// CNAME records cannot/should not exist at the root of a zone.
+			// So we skip a domain when a CNAME is found.
+			if dnsMsgContainsCNAME(in) {
+				continue
+			}
+
+			for _, ans := range in.Answer {
+				if soa, ok := ans.(*dns.SOA); ok {
+					zone := soa.Hdr.Name
+					fqdnToZone[fqdn] = zone
+					return zone, nil
+				}
+			}
+		case dns.RcodeNameError:
+			// NXDOMAIN
+		default:
+			// Any response code other than NOERROR and NXDOMAIN is treated as error
+			return "", fmt.Errorf("unexpected response code '%s' for %s", dns.RcodeToString[in.Rcode], domain)
+		}
+	}
+
+	return "", fmt.Errorf("could not find the start of authority for %s%s", fqdn, formatDNSError(in, err))
+}
+
+// dnsMsgContainsCNAME checks for a CNAME answer in msg
+func dnsMsgContainsCNAME(msg *dns.Msg) bool {
+	for _, ans := range msg.Answer {
+		if _, ok := ans.(*dns.CNAME); ok {
+			return true
+		}
+	}
+	return false
+}
+
+func dnsQuery(fqdn string, rtype uint16, nameservers []string, recursive bool) (*dns.Msg, error) {
+	m := createDNSMsg(fqdn, rtype, recursive)
+
+	var in *dns.Msg
+	var err error
+
+	for _, ns := range nameservers {
+		in, err = sendDNSQuery(m, ns)
+		if err == nil && len(in.Answer) > 0 {
+			break
+		}
+	}
+	return in, err
+}
+
+func createDNSMsg(fqdn string, rtype uint16, recursive bool) *dns.Msg {
+	m := new(dns.Msg)
+	m.SetQuestion(fqdn, rtype)
+	m.SetEdns0(4096, false)
+
+	if !recursive {
+		m.RecursionDesired = false
+	}
+
+	return m
+}
+
+func sendDNSQuery(m *dns.Msg, ns string) (*dns.Msg, error) {
+	udp := &dns.Client{Net: "udp", Timeout: dnsTimeout}
+	in, _, err := udp.Exchange(m, ns)
+
+	if in != nil && in.Truncated {
+		tcp := &dns.Client{Net: "tcp", Timeout: dnsTimeout}
+		// If the TCP request succeeds, the err will reset to nil
+		in, _, err = tcp.Exchange(m, ns)
+	}
+
+	return in, err
+}
+
+func formatDNSError(msg *dns.Msg, err error) string {
+	var parts []string
+
+	if msg != nil {
+		parts = append(parts, dns.RcodeToString[msg.Rcode])
+	}
+
+	if err != nil {
+		parts = append(parts, fmt.Sprintf("%v", err))
+	}
+
+	if len(parts) > 0 {
+		return ": " + strings.Join(parts, " ")
+	}
+
+	return ""
+}