GIDINET: Auto-suggest nameservers and add premium DNS helper (#4203)

## Summary

- **`GetNameservers` now returns the static free-tier Gidinet
nameservers** (`dnsl1/dnsl2.gidinet.com`). Previously it returned `nil,
nil`, which meant DNSControl could not derive registrar delegation from
the DNS provider for Gidinet-hosted zones. With this change, zones
declared as `D(..., REG_GIDINET, DnsProvider(DSP_GIDINET), ...)` get
correct NS suggestions automatically, matching the behavior of providers
like Cloudflare or netcup.
- **New `GIDINET_PREMIUM_NS()` JS helper** that emits
`NAMESERVER("dns1..dns5.gidinet.com.")` for zones on Gidinet's premium
DNS tier. Intended to be paired with `DnsProvider(DSP_GIDINET, 0)` so
the free-tier defaults from `GetNameservers` are skipped and only the
five premium nameservers drive the delegation.
- **`filterApexNS` now drops apex NS records silently when they were
synthesized from `dc.Nameservers`** (either auto-injected by
`GetNameservers` or declared via `NAMESERVER()`), since `AddNSRecords`
adds those to `dc.Records` automatically. Previously it warned on every
preview once `GetNameservers` began returning values. Truly unexpected
apex NS targets (e.g. a stray `NS("@", "something-else.")`) still emit a
warning because the Gidinet DNS API cannot honor them.
- **Documentation updated** to describe both tiers and the
`GIDINET_PREMIUM_NS()` usage pattern.

## Motivation

Before this change, a zone served by Gidinet DNS required a redundant
`NS_GIDINET()`-style block of explicit `NAMESERVER()` calls just so
`REG_GIDINET` could propose the correct delegation. Users hit a
no-op/warning loop where the registrar had nothing to compare against
and/or where apex NS records raised spurious warnings. Gidinet's
nameservers are static per-tier, so returning them from `GetNameservers`
is safe and matches the convention used by other providers.

## Test plan

- [x] `go test ./...`
- [x] `go vet ./...`
- [x] `gofmt -l providers/gidinet/ pkg/js/`
- [x] `dnscontrol check` on a real Gidinet-hosted configuration
- [x] `dnscontrol preview` on a free-tier zone: registrar correctly
proposes `dnsl1/dnsl2.gidinet.com` delegation without explicit
`NAMESERVER()` in the zone file; no spurious apex-NS warnings.
- [ ] `dnscontrol preview` on a premium-tier zone using
`DnsProvider(DSP_GIDINET, 0) + GIDINET_PREMIUM_NS()` (pending
availability of a premium zone for the author to validate end-to-end).
- [x] IR inspection (`print-ir`) on a synthetic premium-tier config
confirms the helper expands to the five
`NAMESERVER("dns1..5.gidinet.com.")` entries.

## Notes

- No interface or API changes.
- Backwards compatible: zones that already include explicit
`NAMESERVER("dnsl1/dnsl2…")` records still work (the registrar-side
dedup already handles duplicates).

Author: zupolgec

documentation/provider/gidinet.md

@@ -123,28 +123,52 @@ Allowed TTL values (in seconds):
 
 ### Nameservers
 
-Gidinet's default nameservers are:
+Gidinet offers two DNS tiers with different nameserver sets.
+
+**Free tier (default):**
 - `dnsl1.gidinet.com`
 - `dnsl2.gidinet.com`
 
-**Apex NS records are automatically filtered** by the DNS provider with a warning message. Gidinet does not support modifying NS records at the zone apex via the DNS API - they are managed by the registrar.
+**Premium DNS:**
+- `dns1.gidinet.com`
+- `dns2.gidinet.com`
+- `dns3.gidinet.com`
+- `dns4.gidinet.com`
+- `dns5.gidinet.com`
 
-To manage nameserver delegation, use Gidinet as a **registrar** with the `NAMESERVER()` function:
+The DNS provider returns the free-tier nameservers via `GetNameservers`, so free-tier zones need no explicit `NAMESERVER(...)` — DNSControl will suggest the correct delegation to the registrar automatically:
 
 {% code title="dnsconfig.js" %}
 ```javascript
 var REG_GIDINET = NewRegistrar("gidinet");
 var DSP_GIDINET = NewDnsProvider("gidinet");
 
 D("example.com", REG_GIDINET, DnsProvider(DSP_GIDINET),
-    NAMESERVER("dnsl1.gidinet.com."),
-    NAMESERVER("dnsl2.gidinet.com."),
     A("test", "1.2.3.4"),
 );
 ```
 {% endcode %}
 
-This uses the Core API's `domainNameServersChange` method to update the nameservers at the registry level.
+For zones on the **premium DNS** tier, opt out of the free-tier defaults with `DnsProvider(DSP_GIDINET, 0)` and use the `GIDINET_PREMIUM_NS()` helper to emit the five premium `NAMESERVER()` records:
+
+{% code title="dnsconfig.js" %}
+```javascript
+var REG_GIDINET = NewRegistrar("gidinet");
+var DSP_GIDINET = NewDnsProvider("gidinet");
+
+D("premium.example", REG_GIDINET,
+    DnsProvider(DSP_GIDINET, 0),
+    GIDINET_PREMIUM_NS(),
+    A("test", "1.2.3.4"),
+);
+```
+{% endcode %}
+
+The `0` passed to `DnsProvider()` tells DNSControl to skip the provider's auto-injected nameservers for that zone, so only the explicit `NAMESERVER()` records drive the delegation.
+
+When used as a registrar, Gidinet updates the nameservers at the registry level via the Core API's `domainNameServersChange` method.
+
+**Apex NS records are automatically filtered** by the DNS provider with a warning message. Gidinet does not support modifying NS records at the zone apex via the DNS API — they are managed by the registrar. If you use a DNS provider other than Gidinet, declare `NAMESERVER(...)` records (or rely on the other provider's `GetNameservers`) so `REG_GIDINET` can drive the delegation.
 
 ### Zone creation
 

pkg/js/helpers.js

@@ -1490,6 +1490,28 @@ function HEDNS_DDNS_KEY(key) {
     return { hedns_dynamic: 'on', hedns_ddns_key: key };
 }
 
+// Gidinet aliases:
+
+// GIDINET_PREMIUM_NS(): Emit NAMESERVER records for Gidinet premium DNS
+// (dns1..dns5.gidinet.com). Use together with DnsProvider(DNS_GIDINET, 0)
+// so the free-tier defaults from GetNameservers are skipped.
+//
+// Usage:
+//   D("premium.example", REG_GIDINET,
+//     DnsProvider(DNS_GIDINET, 0),
+//     GIDINET_PREMIUM_NS(),
+//     A("www", "1.2.3.4"),
+//   );
+function GIDINET_PREMIUM_NS() {
+    return [
+        NAMESERVER('dns1.gidinet.com.'),
+        NAMESERVER('dns2.gidinet.com.'),
+        NAMESERVER('dns3.gidinet.com.'),
+        NAMESERVER('dns4.gidinet.com.'),
+        NAMESERVER('dns5.gidinet.com.'),
+    ];
+}
+
 // CUSTOM, PROVIDER SPECIFIC RECORD TYPES
 
 function _validateCloudflareRedirect(value) {

providers/gidinet/gidinetProvider.go

@@ -97,11 +97,15 @@ func NewGidinet(m map[string]string, metadata json.RawMessage) (providers.DNSSer
 	return api, nil
 }
 
-// GetNameservers returns the nameservers for a domain.
-// Returns empty because apex NS records cannot be managed via the DNS API -
-// they are managed by the registrar. Use REG_GIDINET with NAMESERVER() instead.
+// GetNameservers returns the static Gidinet DNS nameservers used by every
+// zone hosted on the platform. Returning them here lets dnscontrol suggest
+// the correct delegation to the registrar without requiring an explicit
+// NAMESERVER() in the zone file.
 func (c *gidinetProvider) GetNameservers(domain string) ([]*models.Nameserver, error) {
-	return nil, nil
+	return models.ToNameservers([]string{
+		"dnsl1.gidinet.com",
+		"dnsl2.gidinet.com",
+	})
 }
 
 // GetZoneRecords gets the records of a zone and returns them in RecordConfig format.
@@ -335,12 +339,24 @@ func toGidinetRecord(domain string, rc *models.RecordConfig) *DNSRecord {
 
 // filterApexNS removes NS records at the apex from dc.Records.
 // Gidinet does not support modifying apex NS records via the DNS API - they are
-// managed by the registrar. Use REG_GIDINET with NAMESERVER() to manage them.
+// managed by the registrar. Apex NS records synthesized from dc.Nameservers
+// (auto-injected by GetNameservers or declared via NAMESERVER()) are dropped
+// silently since they are handled by the registrar side. Any other apex NS
+// record is dropped with a warning because it cannot be honored by the
+// Gidinet DNS API.
 func filterApexNS(dc *models.DomainConfig) {
+	expected := make(map[string]bool, len(dc.Nameservers))
+	for _, ns := range dc.Nameservers {
+		expected[strings.TrimSuffix(ns.Name, ".")] = true
+	}
+
 	newList := make([]*models.RecordConfig, 0, len(dc.Records))
 	for _, rec := range dc.Records {
 		if rec.Type == "NS" && rec.GetLabelFQDN() == dc.Name {
-			printer.Warnf("GIDINET does not support modifying NS records at apex. %s will not be added. Use REG_GIDINET with NAMESERVER() instead.\n", rec.GetTargetField())
+			target := strings.TrimSuffix(rec.GetTargetField(), ".")
+			if !expected[target] {
+				printer.Warnf("GIDINET does not support modifying NS records at apex. %s will not be added.\n", rec.GetTargetField())
+			}
 			continue
 		}
 		newList = append(newList, rec)