add dns package with func to set TXT record

dns/dns.go

@@ -0,0 +1,44 @@
+package dns
+
+import (
+	"fmt"
+	"net/http"
+	"net/url"
+	"strings"
+
+	"github.com/cert-manager/webhook-example/auth"
+)
+
+var (
+	baseUrl        = "https://api.nearlyfreespeech.net"
+	authHeaderName = "X-NFSN-Authentication"
+)
+
+func SetTXTRecord(domain string, resolvedFqdn string, key string, login string, apiKey string) error {
+	resolvedFqdn = strings.TrimSuffix(resolvedFqdn, domain)
+	requestUrl := fmt.Sprintf("%s/dns/%s", baseUrl, domain)
+
+	values := url.Values{"name": {resolvedFqdn}, "type": {"TXT"}, "data": {key}}
+	body := values.Encode()
+	authHeader, err := auth.GetAuthHeader(login, apiKey, requestUrl, body)
+	if err != nil {
+		return err
+	}
+
+	bodyReader := strings.NewReader(body)
+	req, err := http.NewRequest("POST", requestUrl, bodyReader)
+	if err != nil {
+		return err
+	}
+
+	req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
+	req.Header.Set(authHeaderName, authHeader)
+
+	resp, err := http.DefaultClient.Do(req)
+	if err != nil {
+		return err
+	}
+	defer resp.Body.Close()
+
+	return nil
+}