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package dns01
import (
"crypto/sha256"
"encoding/base64"
"fmt"
"time"
"github.com/xenolf/lego/acme"
"github.com/xenolf/lego/acme/api"
"github.com/xenolf/lego/challenge"
"github.com/xenolf/lego/log"
"github.com/xenolf/lego/platform/wait"
)
const (
// DefaultPropagationTimeout default propagation timeout
DefaultPropagationTimeout = 60 * time.Second
// DefaultPollingInterval default polling interval
DefaultPollingInterval = 2 * time.Second
// DefaultTTL default TTL
DefaultTTL = 120
)
type ValidateFunc func(core *api.Core, domain string, chlng acme.Challenge) error
type ChallengeOption func(*Challenge) error
// CondOption Conditional challenge option.
func CondOption(condition bool, opt ChallengeOption) ChallengeOption {
if !condition {
// NoOp options
return func(*Challenge) error {
return nil
}
}
return opt
}
// Challenge implements the dns-01 challenge
type Challenge struct {
core *api.Core
validate ValidateFunc
provider challenge.Provider
preCheck preCheck
dnsTimeout time.Duration
}
func NewChallenge(core *api.Core, validate ValidateFunc, provider challenge.Provider, opts ...ChallengeOption) *Challenge {
chlg := &Challenge{
core: core,
validate: validate,
provider: provider,
preCheck: newPreCheck(),
dnsTimeout: 10 * time.Second,
}
for _, opt := range opts {
err := opt(chlg)
if err != nil {
log.Infof("challenge option error: %v", err)
}
}
return chlg
}
// PreSolve just submits the txt record to the dns provider.
// It does not validate record propagation, or do anything at all with the acme server.
func (c *Challenge) PreSolve(authz acme.Authorization) error {
domain := challenge.GetTargetedDomain(authz)
log.Infof("[%s] acme: Preparing to solve DNS-01", domain)
chlng, err := challenge.FindChallenge(challenge.DNS01, authz)
if err != nil {
return err
}
if c.provider == nil {
return fmt.Errorf("[%s] acme: no DNS Provider configured", domain)
}
// Generate the Key Authorization for the challenge
keyAuth, err := c.core.GetKeyAuthorization(chlng.Token)
if err != nil {
return err
}
err = c.provider.Present(authz.Identifier.Value, chlng.Token, keyAuth)
if err != nil {
return fmt.Errorf("[%s] acme: error presenting token: %s", domain, err)
}
return nil
}
func (c *Challenge) Solve(authz acme.Authorization) error {
domain := challenge.GetTargetedDomain(authz)
log.Infof("[%s] acme: Trying to solve DNS-01", domain)
chlng, err := challenge.FindChallenge(challenge.DNS01, authz)
if err != nil {
return err
}
// Generate the Key Authorization for the challenge
keyAuth, err := c.core.GetKeyAuthorization(chlng.Token)
if err != nil {
return err
}
fqdn, value := GetRecord(authz.Identifier.Value, keyAuth)
var timeout, interval time.Duration
switch provider := c.provider.(type) {
case challenge.ProviderTimeout:
timeout, interval = provider.Timeout()
default:
timeout, interval = DefaultPropagationTimeout, DefaultPollingInterval
}
log.Infof("[%s] acme: Checking DNS record propagation using %+v", domain, recursiveNameservers)
err = wait.For("propagation", timeout, interval, func() (bool, error) {
stop, errP := c.preCheck.call(fqdn, value)
if !stop || errP != nil {
log.Infof("[%s] acme: Waiting for DNS record propagation.", domain)
}
return stop, errP
})
if err != nil {
return err
}
chlng.KeyAuthorization = keyAuth
return c.validate(c.core, authz.Identifier.Value, chlng)
}
// CleanUp cleans the challenge.
func (c *Challenge) CleanUp(authz acme.Authorization) error {
log.Infof("[%s] acme: Cleaning DNS-01 challenge", challenge.GetTargetedDomain(authz))
chlng, err := challenge.FindChallenge(challenge.DNS01, authz)
if err != nil {
return err
}
keyAuth, err := c.core.GetKeyAuthorization(chlng.Token)
if err != nil {
return err
}
return c.provider.CleanUp(authz.Identifier.Value, chlng.Token, keyAuth)
}
func (c *Challenge) Sequential() (bool, time.Duration) {
if p, ok := c.provider.(sequential); ok {
return ok, p.Sequential()
}
return false, 0
}
type sequential interface {
Sequential() time.Duration
}
// GetRecord returns a DNS record which will fulfill the `dns-01` challenge
func GetRecord(domain, keyAuth string) (fqdn string, value string) {
keyAuthShaBytes := sha256.Sum256([]byte(keyAuth))
// base64URL encoding without padding
value = base64.RawURLEncoding.EncodeToString(keyAuthShaBytes[:sha256.Size])
fqdn = fmt.Sprintf("_acme-challenge.%s.", domain)
return
}
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