snapshot of https://github.com/grpc/grpc-go.git (master, 2026-09-15; blobs > 131072B omitted)

xds/googledirectpath/utils.go

@@ -0,0 +1,101 @@
+/*
+ *
+ * Copyright 2021 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+package googledirectpath
+
+import (
+	"bytes"
+	"fmt"
+	"io"
+	"net/http"
+	"net/url"
+	"strings"
+	"sync"
+	"time"
+)
+
+func getFromMetadata(timeout time.Duration, urlStr string) ([]byte, error) {
+	parsedURL, err := url.Parse(urlStr)
+	if err != nil {
+		return nil, err
+	}
+	client := &http.Client{Timeout: timeout}
+	req := &http.Request{
+		Method: http.MethodGet,
+		URL:    parsedURL,
+		Header: http.Header{"Metadata-Flavor": {"Google"}},
+	}
+	resp, err := client.Do(req)
+	if err != nil {
+		return nil, fmt.Errorf("failed communicating with metadata server: %v", err)
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode != http.StatusOK {
+		return nil, fmt.Errorf("metadata server returned resp with non-OK: %v", resp)
+	}
+	body, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return nil, fmt.Errorf("failed reading from metadata server: %v", err)
+	}
+	return body, nil
+}
+
+var (
+	zone     string
+	zoneOnce sync.Once
+)
+
+// Defined as var to be overridden in tests.
+var getZone = func(timeout time.Duration) string {
+	zoneOnce.Do(func() {
+		qualifiedZone, err := getFromMetadata(timeout, zoneURL)
+		if err != nil {
+			logger.Warningf("could not discover instance zone: %v", err)
+			return
+		}
+		i := bytes.LastIndexByte(qualifiedZone, '/')
+		if i == -1 {
+			logger.Warningf("could not parse zone from metadata server: %s", qualifiedZone)
+			return
+		}
+		zone = string(qualifiedZone[i+1:])
+	})
+	return zone
+}
+
+var (
+	ipv6Capable     bool
+	ipv6CapableOnce sync.Once
+)
+
+// Defined as var to be overridden in tests.
+var getIPv6Capable = func(timeout time.Duration) bool {
+	ipv6CapableOnce.Do(func() {
+		addr, err := getFromMetadata(timeout, ipv6URL)
+		if err != nil {
+			logger.Warningf("could not discover ipv6 capability: %v", err)
+			return
+		}
+		if trimmedAddr := strings.TrimSpace(string(addr)); trimmedAddr == "" {
+			logger.Warningf("metadata server returned empty ipv6 address")
+			return
+		}
+		ipv6Capable = true
+	})
+	return ipv6Capable
+}