Update Lego

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

@@ -0,0 +1,114 @@
+package dns01
+
+import (
+	"fmt"
+	"net"
+	"strings"
+
+	"github.com/miekg/dns"
+)
+
+// PreCheckFunc checks DNS propagation before notifying ACME that the DNS challenge is ready.
+type PreCheckFunc func(fqdn, value string) (bool, error)
+
+func AddPreCheck(preCheck PreCheckFunc) ChallengeOption {
+	// Prevent race condition
+	check := preCheck
+	return func(chlg *Challenge) error {
+		chlg.preCheck.checkFunc = check
+		return nil
+	}
+}
+
+func DisableCompletePropagationRequirement() ChallengeOption {
+	return func(chlg *Challenge) error {
+		chlg.preCheck.requireCompletePropagation = false
+		return nil
+	}
+}
+
+type preCheck struct {
+	// checks DNS propagation before notifying ACME that the DNS challenge is ready.
+	checkFunc PreCheckFunc
+	// require the TXT record to be propagated to all authoritative name servers
+	requireCompletePropagation bool
+}
+
+func newPreCheck() preCheck {
+	return preCheck{
+		requireCompletePropagation: true,
+	}
+}
+
+func (p preCheck) call(fqdn, value string) (bool, error) {
+	if p.checkFunc == nil {
+		return p.checkDNSPropagation(fqdn, value)
+	}
+	return p.checkFunc(fqdn, value)
+}
+
+// checkDNSPropagation checks if the expected TXT record has been propagated to all authoritative nameservers.
+func (p preCheck) checkDNSPropagation(fqdn, value string) (bool, error) {
+	// Initial attempt to resolve at the recursive NS
+	r, err := dnsQuery(fqdn, dns.TypeTXT, recursiveNameservers, true)
+	if err != nil {
+		return false, err
+	}
+
+	if !p.requireCompletePropagation {
+		return true, nil
+	}
+
+	if r.Rcode == dns.RcodeSuccess {
+		// If we see a CNAME here then use the alias
+		for _, rr := range r.Answer {
+			if cn, ok := rr.(*dns.CNAME); ok {
+				if cn.Hdr.Name == fqdn {
+					fqdn = cn.Target
+					break
+				}
+			}
+		}
+	}
+
+	authoritativeNss, err := lookupNameservers(fqdn)
+	if err != nil {
+		return false, err
+	}
+
+	return checkAuthoritativeNss(fqdn, value, authoritativeNss)
+}
+
+// checkAuthoritativeNss queries each of the given nameservers for the expected TXT record.
+func checkAuthoritativeNss(fqdn, value string, nameservers []string) (bool, error) {
+	for _, ns := range nameservers {
+		r, err := dnsQuery(fqdn, dns.TypeTXT, []string{net.JoinHostPort(ns, "53")}, false)
+		if err != nil {
+			return false, err
+		}
+
+		if r.Rcode != dns.RcodeSuccess {
+			return false, fmt.Errorf("NS %s returned %s for %s", ns, dns.RcodeToString[r.Rcode], fqdn)
+		}
+
+		var records []string
+
+		var found bool
+		for _, rr := range r.Answer {
+			if txt, ok := rr.(*dns.TXT); ok {
+				record := strings.Join(txt.Txt, "")
+				records = append(records, record)
+				if record == value {
+					found = true
+					break
+				}
+			}
+		}
+
+		if !found {
+			return false, fmt.Errorf("NS %s did not return the expected TXT record [fqdn: %s, value: %s]: %s", ns, fqdn, value, strings.Join(records, " ,"))
+		}
+	}
+
+	return true, nil
+}