Migrate to go-acme/lego.

vendor/github.com/go-acme/lego/acme/api/challenge.go

@@ -0,0 +1,45 @@
+package api
+
+import (
+	"errors"
+
+	"github.com/go-acme/lego/acme"
+)
+
+type ChallengeService service
+
+// New Creates a challenge.
+func (c *ChallengeService) New(chlgURL string) (acme.ExtendedChallenge, error) {
+	if len(chlgURL) == 0 {
+		return acme.ExtendedChallenge{}, errors.New("challenge[new]: empty URL")
+	}
+
+	// Challenge initiation is done by sending a JWS payload containing the trivial JSON object `{}`.
+	// We use an empty struct instance as the postJSON payload here to achieve this result.
+	var chlng acme.ExtendedChallenge
+	resp, err := c.core.post(chlgURL, struct{}{}, &chlng)
+	if err != nil {
+		return acme.ExtendedChallenge{}, err
+	}
+
+	chlng.AuthorizationURL = getLink(resp.Header, "up")
+	chlng.RetryAfter = getRetryAfter(resp)
+	return chlng, nil
+}
+
+// Get Gets a challenge.
+func (c *ChallengeService) Get(chlgURL string) (acme.ExtendedChallenge, error) {
+	if len(chlgURL) == 0 {
+		return acme.ExtendedChallenge{}, errors.New("challenge[get]: empty URL")
+	}
+
+	var chlng acme.ExtendedChallenge
+	resp, err := c.core.postAsGet(chlgURL, &chlng)
+	if err != nil {
+		return acme.ExtendedChallenge{}, err
+	}
+
+	chlng.AuthorizationURL = getLink(resp.Header, "up")
+	chlng.RetryAfter = getRetryAfter(resp)
+	return chlng, nil
+}