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/*
*
* 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"
"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() {
_, err := getFromMetadata(timeout, ipv6URL)
if err != nil {
logger.Warningf("could not discover ipv6 capability: %v", err)
return
}
ipv6Capable = true
})
return ipv6Capable
}
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