From bc855fdc68ed5ae77eb23579f92bb504b649334d Mon Sep 17 00:00:00 2001
From: Andras Bacsai <5845193+andrasbacsai@users.noreply.github.com>
Date: Mon, 2 Nov 2026 14:46:19 +0100
Subject: [PATCH] fix(transfer): resolve IPv6-only server host names

The domain check of the transfer checklist resolved the server host name
with gethostbynamel(), which returns IPv4 only, so a domain that points to
an IPv6-only server was reported as pointing to another address. Resolve A
and AAAA records and compare normalized addresses. The Cloud SSH probe now
also resolves AAAA records when a host name has no A record.

Closes #12397

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
---
 .../Api/ServerTransferController.php          |  2 +-
 .../TransferFinishChecklist.php               | 21 ++++++++++++++++---
 2 files changed, 19 insertions(+), 4 deletions(-)

diff --git a/app/Http/Controllers/Api/ServerTransferController.php b/app/Http/Controllers/Api/ServerTransferController.php
index efd8f428b7..0dc0229a30 100644
--- a/app/Http/Controllers/Api/ServerTransferController.php
+++ b/app/Http/Controllers/Api/ServerTransferController.php
@@ -232,7 +232,7 @@ class ServerTransferController extends Controller
         Server::throttleValidation($teamId, $ip);
         $probeIp = Server::normalizeIp($ip);
         if (isCloud() && ! filter_var($probeIp, FILTER_VALIDATE_IP)) {
-            $probeIp = gethostbyname($probeIp);
+            $probeIp = resolveHostToIp($probeIp);
         }
         $probeHost = filter_var($probeIp, FILTER_VALIDATE_IP, FILTER_FLAG_IPV6) ? "[{$probeIp}]" : $probeIp;
         $probeAllowed = ! isCloud() || (filter_var($probeIp, FILTER_VALIDATE_IP)
diff --git a/app/Services/ServerTransfer/TransferFinishChecklist.php b/app/Services/ServerTransfer/TransferFinishChecklist.php
index d894b49cb3..25d6d19e61 100644
--- a/app/Services/ServerTransfer/TransferFinishChecklist.php
+++ b/app/Services/ServerTransfer/TransferFinishChecklist.php
@@ -407,14 +407,29 @@ class TransferFinishChecklist
             : ['action', 'This instance does not own the record yet.', 'Until it owns the record, this instance does not change or delete it.'];
     }
 
+    /**
+     * The IPv4 and IPv6 addresses of a host name, in the normalized form of normalizeIpAddress().
+     *
+     * @return array<int, string>
+     */
+    private function resolveIps(string $host): array
+    {
+        $records = @dns_get_record($host, DNS_A | DNS_AAAA) ?: [];
+
+        return array_values(array_filter(array_map(
+            fn (array $record): ?string => isset($record['ip']) || isset($record['ipv6']) ? normalizeIpAddress($record['ip'] ?? $record['ipv6']) : null,
+            $records,
+        )));
+    }
+
     /**
      * @return array{0: string, 1: string, 2: string|null}
      */
     private function checkDomain(Server $server, string $host): array
     {
-        $serverIps = filter_var($server->ip, FILTER_VALIDATE_IP) ? [$server->ip] : (gethostbynamel($server->ip) ?: []);
-        $records = @dns_get_record($host, DNS_A | DNS_AAAA) ?: [];
-        $ips = array_values(array_filter(array_map(fn (array $record) => $record['ip'] ?? $record['ipv6'] ?? null, $records)));
+        $serverIp = normalizeIpAddress($server->ip);
+        $serverIps = filter_var($serverIp, FILTER_VALIDATE_IP) ? [$serverIp] : $this->resolveIps($serverIp);
+        $ips = $this->resolveIps($host);
         if ($ips === []) {
             return ['action', 'The domain does not resolve.', null];
         }