93 lines
2.3 KiB
Go
93 lines
2.3 KiB
Go
package acme
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import (
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"crypto/sha256"
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"encoding/base64"
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"encoding/json"
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"errors"
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"fmt"
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"net/http"
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"strings"
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"time"
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)
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// DNSProvider represents a service for creating dns records.
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type DNSProvider interface {
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// CreateTXT creates a TXT record
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CreateTXTRecord(fqdn, value string, ttl int) error
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RemoveTXTRecord(fqdn, value string, ttl int) error
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}
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// dnsChallenge implements the dns-01 challenge according to ACME 7.5
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type dnsChallenge struct {
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jws *jws
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provider DNSProvider
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}
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func (s *dnsChallenge) Solve(chlng challenge, domain string) error {
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logf("[INFO] acme: Trying to solve DNS-01")
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// Generate the Key Authorization for the challenge
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keyAuth, err := getKeyAuthorization(chlng.Token, &s.jws.privKey.PublicKey)
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if err != nil {
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return err
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}
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keyAuthShaBytes := sha256.Sum256([]byte(keyAuth))
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// base64URL encoding without padding
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keyAuthSha := base64.URLEncoding.EncodeToString(keyAuthShaBytes[:sha256.Size])
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keyAuthSha = strings.TrimRight(keyAuthSha, "=")
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fqdn := fmt.Sprintf("_acme-challenge.%s.", domain)
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if err = s.provider.CreateTXTRecord(fqdn, keyAuthSha, 120); err != nil {
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return err
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}
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jsonBytes, err := json.Marshal(challenge{Resource: "challenge", Type: chlng.Type, Token: chlng.Token, KeyAuthorization: keyAuth})
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if err != nil {
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return errors.New("Failed to marshal network message...")
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}
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// Tell the server we handle DNS-01
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resp, err := s.jws.post(chlng.URI, jsonBytes)
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if err != nil {
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return fmt.Errorf("Failed to post JWS message. -> %v", err)
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}
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// Repeatedly check the server for an updated status on our request.
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var challengeResponse challenge
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Loop:
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for {
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if resp.StatusCode >= http.StatusBadRequest {
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return handleHTTPError(resp)
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}
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err = json.NewDecoder(resp.Body).Decode(&challengeResponse)
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resp.Body.Close()
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if err != nil {
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return err
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}
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switch challengeResponse.Status {
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case "valid":
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logf("The server validated our request")
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break Loop
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case "pending":
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break
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case "invalid":
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return errors.New("The server could not validate our request.")
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default:
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return errors.New("The server returned an unexpected state.")
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}
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time.Sleep(1 * time.Second)
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resp, err = http.Get(chlng.URI)
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}
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if err = s.provider.RemoveTXTRecord(fqdn, keyAuthSha, 120); err != nil {
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logf("[WARN] acme: Failed to cleanup DNS record. -> %v ", err)
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}
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return nil
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}
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