Add interactive form/report

checker/interactive.go

@@ -0,0 +1,103 @@
+package checker
+
+import (
+	"encoding/json"
+	"errors"
+	"fmt"
+	"net/http"
+	"strings"
+
+	sdk "git.happydns.org/checker-sdk-go/checker"
+	"github.com/miekg/dns"
+)
+
+// RenderForm implements sdk.CheckerInteractive. It lists the minimal human
+// inputs needed to bootstrap a check when this checker runs standalone
+// (outside of a happyDomain host).
+func (p *nsProvider) RenderForm() []sdk.CheckerOptionField {
+	return []sdk.CheckerOptionField{
+		{
+			Id:          "domain",
+			Type:        "string",
+			Label:       "Domain name",
+			Placeholder: "example.com",
+			Required:    true,
+			Description: "Zone to probe. Its NS records will be resolved and each nameserver tested.",
+		},
+	}
+}
+
+// ParseForm implements sdk.CheckerInteractive. It resolves the NS records
+// for the requested domain via DNS and assembles the CheckerOptions that
+// Collect expects — replacing the AutoFill work that happyDomain would
+// otherwise perform.
+func (p *nsProvider) ParseForm(r *http.Request) (sdk.CheckerOptions, error) {
+	domain := strings.TrimSpace(r.FormValue("domain"))
+	if domain == "" {
+		return nil, errors.New("domain is required")
+	}
+	fqdn := dns.Fqdn(domain)
+
+	nsRecords, err := resolveNS(fqdn)
+	if err != nil {
+		return nil, fmt.Errorf("could not resolve NS records for %s: %w", domain, err)
+	}
+	if len(nsRecords) == 0 {
+		return nil, fmt.Errorf("no NS records found for %s", domain)
+	}
+
+	payload, err := json.Marshal(originPayload{NameServers: nsRecords})
+	if err != nil {
+		return nil, fmt.Errorf("failed to encode origin payload: %w", err)
+	}
+
+	svc := serviceMessage{
+		Type:    serviceTypeOrigin,
+		Domain:  "",
+		Service: payload,
+	}
+
+	return sdk.CheckerOptions{
+		"service":    svc,
+		"domainName": strings.TrimSuffix(fqdn, "."),
+	}, nil
+}
+
+// resolveNS queries the system resolver for the NS records of fqdn and
+// returns them as miekg *dns.NS records so they match the shape produced
+// by happyDomain's Origin service payload.
+func resolveNS(fqdn string) ([]*dns.NS, error) {
+	c := new(dns.Client)
+	m := new(dns.Msg)
+	m.SetQuestion(fqdn, dns.TypeNS)
+	m.RecursionDesired = true
+
+	config, err := dns.ClientConfigFromFile("/etc/resolv.conf")
+	if err != nil || config == nil || len(config.Servers) == 0 {
+		config = &dns.ClientConfig{Servers: []string{"1.1.1.1", "8.8.8.8"}, Port: "53"}
+	}
+
+	var lastErr error
+	for _, server := range config.Servers {
+		in, _, err := c.Exchange(m, server+":"+config.Port)
+		if err != nil {
+			lastErr = err
+			continue
+		}
+		if in.Rcode != dns.RcodeSuccess {
+			lastErr = fmt.Errorf("DNS response code %s", dns.RcodeToString[in.Rcode])
+			continue
+		}
+		var records []*dns.NS
+		for _, rr := range in.Answer {
+			if ns, ok := rr.(*dns.NS); ok {
+				records = append(records, ns)
+			}
+		}
+		return records, nil
+	}
+	if lastErr == nil {
+		lastErr = errors.New("no resolver available")
+	}
+	return nil, lastErr
+}