feat: add TemporarilyUnavailableError for 503 responses

Author: boutetnico

client.go

@@ -140,7 +140,7 @@ func (c *Client) handleError(resp *http.Response, body []byte) error {
 	}
 
 	var retryAfter int
-	if resp.StatusCode == 429 {
+	if resp.StatusCode == 429 || resp.StatusCode == 503 {
 		if v := resp.Header.Get("Retry-After"); v != "" {
 			retryAfter, _ = strconv.Atoi(v)
 		}

client_test.go

@@ -567,6 +567,35 @@ func TestErrorResponses(t *testing.T) {
 				}
 			},
 		},
+		{
+			name:    "503 TemporarilyUnavailableError",
+			status:  503,
+			body:    `{"error":"temporarily_unavailable","message":"Data for this domain is temporarily unavailable."}`,
+			headers: map[string]string{"Retry-After": "300"},
+			checkErr: func(t *testing.T, err error) {
+				var target *TemporarilyUnavailableError
+				if !errors.As(err, &target) {
+					t.Fatal("expected TemporarilyUnavailableError")
+				}
+				if target.RetryAfter != 300 {
+					t.Errorf("RetryAfter = %d, want 300", target.RetryAfter)
+				}
+			},
+		},
+		{
+			name:   "503 TemporarilyUnavailableError without Retry-After",
+			status: 503,
+			body:   `{"error":"temporarily_unavailable","message":"Data for this domain is temporarily unavailable."}`,
+			checkErr: func(t *testing.T, err error) {
+				var target *TemporarilyUnavailableError
+				if !errors.As(err, &target) {
+					t.Fatal("expected TemporarilyUnavailableError")
+				}
+				if target.RetryAfter != 0 {
+					t.Errorf("RetryAfter = %d, want 0", target.RetryAfter)
+				}
+			},
+		},
 		{
 			name:   "500 unknown error",
 			status: 500,

errors.go

@@ -33,6 +33,9 @@ type NotFoundError struct{ *APIError }
 // RateLimitError is returned when rate limit or monthly quota is exceeded (HTTP 429).
 type RateLimitError struct{ *APIError }
 
+// TemporarilyUnavailableError is returned when the domain data is temporarily unavailable (HTTP 503).
+type TemporarilyUnavailableError struct{ *APIError }
+
 // UpstreamError is returned when the upstream RDAP server fails (HTTP 502).
 type UpstreamError struct{ *APIError }
 
@@ -58,6 +61,8 @@ func newError(statusCode int, code, message string, retryAfter int) error {
 		return &RateLimitError{base}
 	case 502:
 		return &UpstreamError{base}
+	case 503:
+		return &TemporarilyUnavailableError{base}
 	default:
 		return base
 	}

errors_test.go

@@ -42,6 +42,7 @@ func TestNewErrorTypedErrors(t *testing.T) {
 		{404, "not_found", "not found", 0, "NotFoundError"},
 		{429, "rate_limited", "too many", 30, "RateLimitError"},
 		{502, "upstream_error", "upstream fail", 0, "UpstreamError"},
+		{503, "temporarily_unavailable", "temporarily unavailable", 300, "TemporarilyUnavailableError"},
 	}
 
 	for _, tt := range tests {
@@ -94,6 +95,15 @@ func TestNewErrorTypedErrors(t *testing.T) {
 					t.Fatal("errors.As failed for UpstreamError")
 				}
 				checkBase(t, target.APIError, tt)
+			case 503:
+				var target *TemporarilyUnavailableError
+				if !errors.As(err, &target) {
+					t.Fatal("errors.As failed for TemporarilyUnavailableError")
+				}
+				checkBase(t, target.APIError, tt)
+				if target.RetryAfter != 300 {
+					t.Errorf("RetryAfter = %d, want 300", target.RetryAfter)
+				}
 			}
 
 			// Typed errors embed *APIError, accessible via the field.