Initial commit

Generic SRV records checker for happyDomain.

For each SRV record attached to an svcs.UnknownSRV service, the checker
resolves every target and probes reachability:

  - DNS resolution (A/AAAA), CNAME detection (RFC 2782 violation),
    null-target detection (RFC 2782 "service explicitly unavailable")
  - TCP connect to target:port for _tcp SRVs
  - UDP probe for _udp SRVs, using ICMP port-unreachable detection

The checker also publishes TLS endpoints (host, port, SNI) for every
SRV target hitting a well-known direct-TLS port (443, 465, 636, 853,
993, 995, 5061, 5223, …) via the EndpointDiscoverer SDK interface, so
a downstream TLS checker can pick them up.

The HTML report groups records as cards and surfaces the most common
failure scenarios (DNS failure, CNAME target, TCP unreachable,
null-target) at the top with remediation guidance.

checker/interactive.go

@@ -0,0 +1,49 @@
+//go:build standalone
+
+package checker
+
+import (
+	"errors"
+	"net/http"
+	"strings"
+
+	sdk "git.happydns.org/checker-sdk-go/checker"
+)
+
+func (p *srvProvider) RenderForm() []sdk.CheckerOptionField {
+	return []sdk.CheckerOptionField{
+		{
+			Id:          "name",
+			Type:        "string",
+			Label:       "SRV record name to check",
+			Placeholder: "_sip._tcp.example.com",
+			Required:    true,
+			Description: "Fully-qualified SRV owner name (e.g. _service._proto.domain).",
+		},
+	}
+}
+
+func (p *srvProvider) ParseForm(r *http.Request) (sdk.CheckerOptions, error) {
+	name := strings.TrimSpace(r.FormValue("name"))
+	if name == "" {
+		return nil, errors.New("name is required")
+	}
+	name = strings.TrimSuffix(name, ".")
+
+	// Split into subdomain + domain so collect's serviceDomain
+	// (subdomain + "." + domain) reconstructs the full SRV owner.
+	parts := strings.SplitN(name, ".", 2)
+	sub := parts[0]
+	parent := ""
+	if len(parts) == 2 {
+		parent = parts[1]
+	} else {
+		parent = name
+		sub = ""
+	}
+
+	return sdk.CheckerOptions{
+		"domain":    parent,
+		"subdomain": sub,
+	}, nil
+}