206 lines
6.3 KiB
Go
206 lines
6.3 KiB
Go
// Package rfc2136 implements a DNS provider for solving the DNS-01 challenge
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// using the rfc2136 dynamic update.
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package rfc2136
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import (
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"errors"
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"fmt"
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"net"
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"os"
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"strings"
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"time"
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"github.com/miekg/dns"
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"github.com/xenolf/lego/acme"
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"github.com/xenolf/lego/platform/config/env"
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)
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const defaultTimeout = 60 * time.Second
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// Config is used to configure the creation of the DNSProvider
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type Config struct {
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Nameserver string
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TSIGAlgorithm string
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TSIGKey string
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TSIGSecret string
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PropagationTimeout time.Duration
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PollingInterval time.Duration
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TTL int
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}
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// NewDefaultConfig returns a default configuration for the DNSProvider
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func NewDefaultConfig() *Config {
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return &Config{
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TSIGAlgorithm: env.GetOrDefaultString("RFC2136_TSIG_ALGORITHM", dns.HmacMD5),
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TTL: env.GetOrDefaultInt("RFC2136_TTL", 120),
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PropagationTimeout: env.GetOrDefaultSecond("RFC2136_PROPAGATION_TIMEOUT",
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env.GetOrDefaultSecond("RFC2136_TIMEOUT", 60*time.Second)),
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PollingInterval: env.GetOrDefaultSecond("RFC2136_POLLING_INTERVAL", 2*time.Second),
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}
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}
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// DNSProvider is an implementation of the acme.ChallengeProvider interface that
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// uses dynamic DNS updates (RFC 2136) to create TXT records on a nameserver.
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type DNSProvider struct {
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config *Config
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}
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// NewDNSProvider returns a DNSProvider instance configured for rfc2136
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// dynamic update. Configured with environment variables:
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// RFC2136_NAMESERVER: Network address in the form "host" or "host:port".
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// RFC2136_TSIG_ALGORITHM: Defaults to hmac-md5.sig-alg.reg.int. (HMAC-MD5).
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// See https://github.com/miekg/dns/blob/master/tsig.go for supported values.
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// RFC2136_TSIG_KEY: Name of the secret key as defined in DNS server configuration.
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// RFC2136_TSIG_SECRET: Secret key payload.
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// RFC2136_TIMEOUT: DNS propagation timeout in time.ParseDuration format. (60s)
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// To disable TSIG authentication, leave the RFC2136_TSIG* variables unset.
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func NewDNSProvider() (*DNSProvider, error) {
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values, err := env.Get("RFC2136_NAMESERVER")
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if err != nil {
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return nil, fmt.Errorf("rfc2136: %v", err)
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}
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config := NewDefaultConfig()
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config.Nameserver = values["RFC2136_NAMESERVER"]
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config.TSIGKey = os.Getenv("RFC2136_TSIG_KEY")
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config.TSIGSecret = os.Getenv("RFC2136_TSIG_SECRET")
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return NewDNSProviderConfig(config)
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}
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// NewDNSProviderCredentials uses the supplied credentials
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// to return a DNSProvider instance configured for rfc2136 dynamic update.
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// To disable TSIG authentication, leave the TSIG parameters as empty strings.
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// nameserver must be a network address in the form "host" or "host:port".
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// Deprecated
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func NewDNSProviderCredentials(nameserver, tsigAlgorithm, tsigKey, tsigSecret, rawTimeout string) (*DNSProvider, error) {
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config := NewDefaultConfig()
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config.Nameserver = nameserver
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config.TSIGAlgorithm = tsigAlgorithm
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config.TSIGKey = tsigKey
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config.TSIGSecret = tsigSecret
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timeout := defaultTimeout
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if rawTimeout != "" {
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t, err := time.ParseDuration(rawTimeout)
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if err != nil {
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return nil, err
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} else if t < 0 {
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return nil, fmt.Errorf("rfc2136: invalid/negative RFC2136_TIMEOUT: %v", rawTimeout)
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} else {
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timeout = t
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}
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}
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config.PropagationTimeout = timeout
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return NewDNSProviderConfig(config)
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}
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// NewDNSProviderConfig return a DNSProvider instance configured for rfc2136.
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func NewDNSProviderConfig(config *Config) (*DNSProvider, error) {
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if config == nil {
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return nil, errors.New("rfc2136: the configuration of the DNS provider is nil")
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}
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if config.Nameserver == "" {
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return nil, fmt.Errorf("rfc2136: nameserver missing")
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}
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if config.TSIGAlgorithm == "" {
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config.TSIGAlgorithm = dns.HmacMD5
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}
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// Append the default DNS port if none is specified.
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if _, _, err := net.SplitHostPort(config.Nameserver); err != nil {
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if strings.Contains(err.Error(), "missing port") {
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config.Nameserver = net.JoinHostPort(config.Nameserver, "53")
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} else {
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return nil, fmt.Errorf("rfc2136: %v", err)
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}
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}
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if len(config.TSIGKey) == 0 && len(config.TSIGSecret) > 0 ||
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len(config.TSIGKey) > 0 && len(config.TSIGSecret) == 0 {
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config.TSIGKey = ""
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config.TSIGSecret = ""
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}
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return &DNSProvider{config: config}, nil
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}
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// Timeout returns the timeout and interval to use when checking for DNS propagation.
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// Adjusting here to cope with spikes in propagation times.
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func (d *DNSProvider) Timeout() (timeout, interval time.Duration) {
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return d.config.PropagationTimeout, d.config.PollingInterval
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}
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// Present creates a TXT record using the specified parameters
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func (d *DNSProvider) Present(domain, token, keyAuth string) error {
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fqdn, value, _ := acme.DNS01Record(domain, keyAuth)
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err := d.changeRecord("INSERT", fqdn, value, d.config.TTL)
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if err != nil {
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return fmt.Errorf("rfc2136: %v", err)
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}
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return nil
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}
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// CleanUp removes the TXT record matching the specified parameters
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func (d *DNSProvider) CleanUp(domain, token, keyAuth string) error {
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fqdn, value, _ := acme.DNS01Record(domain, keyAuth)
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err := d.changeRecord("REMOVE", fqdn, value, d.config.TTL)
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if err != nil {
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return fmt.Errorf("rfc2136: %v", err)
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}
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return nil
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}
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func (d *DNSProvider) changeRecord(action, fqdn, value string, ttl int) error {
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// Find the zone for the given fqdn
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zone, err := acme.FindZoneByFqdn(fqdn, []string{d.config.Nameserver})
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if err != nil {
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return err
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}
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// Create RR
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rr := new(dns.TXT)
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rr.Hdr = dns.RR_Header{Name: fqdn, Rrtype: dns.TypeTXT, Class: dns.ClassINET, Ttl: uint32(ttl)}
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rr.Txt = []string{value}
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rrs := []dns.RR{rr}
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// Create dynamic update packet
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m := new(dns.Msg)
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m.SetUpdate(zone)
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switch action {
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case "INSERT":
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// Always remove old challenge left over from who knows what.
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m.RemoveRRset(rrs)
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m.Insert(rrs)
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case "REMOVE":
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m.Remove(rrs)
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default:
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return fmt.Errorf("unexpected action: %s", action)
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}
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// Setup client
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c := new(dns.Client)
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c.SingleInflight = true
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// TSIG authentication / msg signing
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if len(d.config.TSIGKey) > 0 && len(d.config.TSIGSecret) > 0 {
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m.SetTsig(dns.Fqdn(d.config.TSIGKey), d.config.TSIGAlgorithm, 300, time.Now().Unix())
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c.TsigSecret = map[string]string{dns.Fqdn(d.config.TSIGKey): d.config.TSIGSecret}
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}
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// Send the query
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reply, _, err := c.Exchange(m, d.config.Nameserver)
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if err != nil {
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return fmt.Errorf("DNS update failed: %v", err)
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}
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if reply != nil && reply.Rcode != dns.RcodeSuccess {
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return fmt.Errorf("DNS update failed. Server replied: %s", dns.RcodeToString[reply.Rcode])
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}
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return nil
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}
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