vm/gce: use regional serial port connections

It's now the recommended approach.

Co-authored-by: Alex Tyler <alextyler@google.com>
Co-authored-by: Aleksandr Nogikh <nogikh@google.com>

3 files changed, 44 insertions, 2 deletions

diff --git a/pkg/gce/gce.go b/pkg/gce/gce.go
index 5e45cbce2..0072bd21f 100644
--- a/pkg/gce/gce.go
+++ b/pkg/gce/gce.go
@@ -17,6 +17,7 @@ import (
 	"io"
 	"math/rand"
 	"net/http"
+	"regexp"
 	"strings"
 	"time"
 
@@ -30,6 +31,7 @@ import (
 type Context struct {
 	ProjectID  string
 	ZoneID     string
+	RegionID   string
 	Instance   string
 	InternalIP string
 	ExternalIP string
@@ -82,6 +84,13 @@ func NewContext(customZoneID string) (*Context, error) {
 	} else {
 		ctx.ZoneID = myZoneID
 	}
+	if !validateZone(ctx.ZoneID) {
+		return nil, fmt.Errorf("%q is not a valid zone name", ctx.ZoneID)
+	}
+	ctx.RegionID = zoneToRegion(ctx.ZoneID)
+	if ctx.RegionID == "" {
+		return nil, fmt.Errorf("failed to extract region id from %s", ctx.ZoneID)
+	}
 	ctx.Instance, err = ctx.getMeta("instance/name")
 	if err != nil {
 		return nil, fmt.Errorf("failed to query gce instance name: %w", err)
@@ -373,3 +382,15 @@ func (ctx *Context) apiCall(fn func() error) error {
 		return err
 	}
 }
+
+var zoneNameRe = regexp.MustCompile("^[a-zA-Z0-9]*-[a-zA-Z0-9]*[-][a-zA-Z0-9]*$")
+
+func validateZone(zone string) bool {
+	return zoneNameRe.MatchString(zone)
+}
+
+var regionNameRe = regexp.MustCompile("^[a-zA-Z0-9]*-[a-zA-Z0-9]*")
+
+func zoneToRegion(zone string) string {
+	return regionNameRe.FindString(zone)
+}
diff --git a/pkg/gce/gce_test.go b/pkg/gce/gce_test.go
new file mode 100644
index 000000000..39f086bdc
--- /dev/null
+++ b/pkg/gce/gce_test.go
@@ -0,0 +1,21 @@
+// Copyright 2024 syzkaller project authors. All rights reserved.
+// Use of this source code is governed by Apache 2 LICENSE that can be found in the LICENSE file.
+
+package gce
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestValidateZone(t *testing.T) {
+	assert.True(t, validateZone("us-west1-b"))
+	assert.True(t, validateZone("us-central1-a"))
+	assert.False(t, validateZone("us-central1"))
+}
+
+func TestZoneToRegion(t *testing.T) {
+	assert.Equal(t, "us-west1", zoneToRegion("us-west1-b"))
+	assert.Equal(t, "northamerica-northeast2", zoneToRegion("northamerica-northeast2-a"))
+}
diff --git a/vm/gce/gce.go b/vm/gce/gce.go
index e8eb35f06..f775f43b5 100644
--- a/vm/gce/gce.go
+++ b/vm/gce/gce.go
@@ -453,8 +453,8 @@ func (inst *instance) serialPortArgs(replay bool) []string {
 	if replay {
 		replayArg = ".replay-lines=10000"
 	}
-	conAddr := fmt.Sprintf("%v.%v.%v.%s.port=1%s@ssh-serialport.googleapis.com",
-		inst.GCE.ProjectID, inst.GCE.ZoneID, inst.name, user, replayArg)
+	conAddr := fmt.Sprintf("%v.%v.%v.%s.port=1%s@%v-ssh-serialport.googleapis.com",
+		inst.GCE.ProjectID, inst.GCE.ZoneID, inst.name, user, replayArg, inst.GCE.RegionID)
 	conArgs := append(vmimpl.SSHArgs(inst.debug, key, 9600), conAddr)
 	// TODO(blackgnezdo): Remove this once ssh-serialport.googleapis.com stops using
 	// host key algorithm: ssh-rsa.