From c9849d667ab55c23d343332a11afb3eb8ede3f2d Mon Sep 17 00:00:00 2001
From: Niall Sheridan <nsheridan@gmail.com>
Date: Sun, 17 Jul 2016 17:16:14 +0100
Subject: Update vendor libs

---
 .../cloud/compute/metadata/metadata.go             | 87 ++++++++++++++++++----
 1 file changed, 71 insertions(+), 16 deletions(-)

(limited to 'vendor/google.golang.org/cloud/compute/metadata')

diff --git a/vendor/google.golang.org/cloud/compute/metadata/metadata.go b/vendor/google.golang.org/cloud/compute/metadata/metadata.go
index 13a1ed9..9821843 100644
--- a/vendor/google.golang.org/cloud/compute/metadata/metadata.go
+++ b/vendor/google.golang.org/cloud/compute/metadata/metadata.go
@@ -27,6 +27,7 @@ import (
 	"net/http"
 	"net/url"
 	"os"
+	"runtime"
 	"strings"
 	"sync"
 	"time"
@@ -37,8 +38,17 @@ import (
 	"google.golang.org/cloud/internal"
 )
 
-// metadataIP is the documented metadata server IP address.
-const metadataIP = "169.254.169.254"
+const (
+	// metadataIP is the documented metadata server IP address.
+	metadataIP = "169.254.169.254"
+
+	// metadataHostEnv is the environment variable specifying the
+	// GCE metadata hostname.  If empty, the default value of
+	// metadataIP ("169.254.169.254") is used instead.
+	// This is variable name is not defined by any spec, as far as
+	// I know; it was made up for the Go package.
+	metadataHostEnv = "GCE_METADATA_HOST"
+)
 
 type cachedValue struct {
 	k    string
@@ -110,7 +120,7 @@ func getETag(client *http.Client, suffix string) (value, etag string, err error)
 	// deployments. To enable spoofing of the metadata service, the environment
 	// variable GCE_METADATA_HOST is first inspected to decide where metadata
 	// requests shall go.
-	host := os.Getenv("GCE_METADATA_HOST")
+	host := os.Getenv(metadataHostEnv)
 	if host == "" {
 		// Using 169.254.169.254 instead of "metadata" here because Go
 		// binaries built with the "netgo" tag and without cgo won't
@@ -163,25 +173,27 @@ func (c *cachedValue) get() (v string, err error) {
 	return
 }
 
-var onGCE struct {
-	sync.Mutex
-	set bool
-	v   bool
-}
+var (
+	onGCEOnce sync.Once
+	onGCE     bool
+)
 
 // OnGCE reports whether this process is running on Google Compute Engine.
 func OnGCE() bool {
-	defer onGCE.Unlock()
-	onGCE.Lock()
-	if onGCE.set {
-		return onGCE.v
-	}
-	onGCE.set = true
-	onGCE.v = testOnGCE()
-	return onGCE.v
+	onGCEOnce.Do(initOnGCE)
+	return onGCE
+}
+
+func initOnGCE() {
+	onGCE = testOnGCE()
 }
 
 func testOnGCE() bool {
+	// The user explicitly said they're on GCE, so trust them.
+	if os.Getenv(metadataHostEnv) != "" {
+		return true
+	}
+
 	ctx, cancel := context.WithCancel(context.Background())
 	defer cancel()
 
@@ -208,9 +220,52 @@ func testOnGCE() bool {
 		resc <- strsContains(addrs, metadataIP)
 	}()
 
+	tryHarder := systemInfoSuggestsGCE()
+	if tryHarder {
+		res := <-resc
+		if res {
+			// The first strategy succeeded, so let's use it.
+			return true
+		}
+		// Wait for either the DNS or metadata server probe to
+		// contradict the other one and say we are running on
+		// GCE. Give it a lot of time to do so, since the system
+		// info already suggests we're running on a GCE BIOS.
+		timer := time.NewTimer(5 * time.Second)
+		defer timer.Stop()
+		select {
+		case res = <-resc:
+			return res
+		case <-timer.C:
+			// Too slow. Who knows what this system is.
+			return false
+		}
+	}
+
+	// There's no hint from the system info that we're running on
+	// GCE, so use the first probe's result as truth, whether it's
+	// true or false. The goal here is to optimize for speed for
+	// users who are NOT running on GCE. We can't assume that
+	// either a DNS lookup or an HTTP request to a blackholed IP
+	// address is fast. Worst case this should return when the
+	// metaClient's Transport.ResponseHeaderTimeout or
+	// Transport.Dial.Timeout fires (in two seconds).
 	return <-resc
 }
 
+// systemInfoSuggestsGCE reports whether the local system (without
+// doing network requests) suggests that we're running on GCE. If this
+// returns true, testOnGCE tries a bit harder to reach its metadata
+// server.
+func systemInfoSuggestsGCE() bool {
+	if runtime.GOOS != "linux" {
+		// We don't have any non-Linux clues available, at least yet.
+		return false
+	}
+	slurp, _ := ioutil.ReadFile("/sys/class/dmi/id/product_name")
+	return strings.TrimSpace(string(slurp)) == "Google"
+}
+
 // Subscribe subscribes to a value from the metadata service.
 // The suffix is appended to "http://${GCE_METADATA_HOST}/computeMetadata/v1/".
 // The suffix may contain query parameters.
-- 
cgit v1.2.3