mirror of
https://github.com/go-acme/lego.git
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202 lines
6.4 KiB
Go
202 lines
6.4 KiB
Go
// Package rfc2136 implements a DNS provider for solving the DNS-01 challenge 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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"strings"
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"time"
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"github.com/go-acme/lego/v4/challenge/dns01"
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"github.com/go-acme/lego/v4/platform/config/env"
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"github.com/miekg/dns"
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)
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// Environment variables names.
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const (
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envNamespace = "RFC2136_"
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EnvTSIGKey = envNamespace + "TSIG_KEY"
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EnvTSIGSecret = envNamespace + "TSIG_SECRET"
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EnvTSIGAlgorithm = envNamespace + "TSIG_ALGORITHM"
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EnvNameserver = envNamespace + "NAMESERVER"
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EnvDNSTimeout = envNamespace + "DNS_TIMEOUT"
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EnvTTL = envNamespace + "TTL"
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EnvPropagationTimeout = envNamespace + "PROPAGATION_TIMEOUT"
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EnvPollingInterval = envNamespace + "POLLING_INTERVAL"
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EnvSequenceInterval = envNamespace + "SEQUENCE_INTERVAL"
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)
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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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SequenceInterval time.Duration
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DNSTimeout time.Duration
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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(EnvTSIGAlgorithm, dns.HmacSHA1),
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TTL: env.GetOrDefaultInt(EnvTTL, dns01.DefaultTTL),
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PropagationTimeout: env.GetOrDefaultSecond(EnvPropagationTimeout, env.GetOrDefaultSecond("RFC2136_TIMEOUT", 60*time.Second)),
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PollingInterval: env.GetOrDefaultSecond(EnvPollingInterval, 2*time.Second),
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SequenceInterval: env.GetOrDefaultSecond(EnvSequenceInterval, dns01.DefaultPropagationTimeout),
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DNSTimeout: env.GetOrDefaultSecond(EnvDNSTimeout, 10*time.Second),
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}
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}
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// DNSProvider implements the challenge.Provider interface.
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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_PROPAGATION_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(EnvNameserver)
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if err != nil {
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return nil, fmt.Errorf("rfc2136: %w", err)
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}
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config := NewDefaultConfig()
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config.Nameserver = values[EnvNameserver]
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config.TSIGKey = env.GetOrFile(EnvTSIGKey)
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config.TSIGSecret = env.GetOrFile(EnvTSIGSecret)
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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, errors.New("rfc2136: nameserver missing")
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}
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if config.TSIGAlgorithm == "" {
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config.TSIGAlgorithm = dns.HmacSHA1
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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: %w", err)
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}
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}
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if config.TSIGKey == "" || config.TSIGSecret == "" {
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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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// Sequential All DNS challenges for this provider will be resolved sequentially.
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// Returns the interval between each iteration.
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func (d *DNSProvider) Sequential() time.Duration {
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return d.config.SequenceInterval
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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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info := dns01.GetChallengeInfo(domain, keyAuth)
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err := d.changeRecord("INSERT", info.EffectiveFQDN, info.Value, d.config.TTL)
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if err != nil {
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return fmt.Errorf("rfc2136: failed to insert: %w", 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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info := dns01.GetChallengeInfo(domain, keyAuth)
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err := d.changeRecord("REMOVE", info.EffectiveFQDN, info.Value, d.config.TTL)
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if err != nil {
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return fmt.Errorf("rfc2136: failed to remove: %w", 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 := dns01.FindZoneByFqdnCustom(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 := &dns.Client{Timeout: d.config.DNSTimeout}
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// TSIG authentication / msg signing
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if d.config.TSIGKey != "" && d.config.TSIGSecret != "" {
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key := strings.ToLower(dns.Fqdn(d.config.TSIGKey))
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alg := dns.Fqdn(d.config.TSIGAlgorithm)
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m.SetTsig(key, alg, 300, time.Now().Unix())
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// secret(s) for Tsig map[<zonename>]<base64 secret>,
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// zonename must be in canonical form (lowercase, fqdn, see RFC 4034 Section 6.2)
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c.TsigSecret = map[string]string{key: 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: %w", 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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