From 815992d4fc7e7502d26c40cdef355aa2e3c322c5 Mon Sep 17 00:00:00 2001
From: Menghan Li <menghanl@google.com>
Date: Fri, 4 Jun 2021 15:40:06 -0700
Subject: [PATCH] [c2p_id_random] c2p: add random number to xDS node ID in
 google-c2p resolver

---
 internal/grpcrand/grpcrand.go          | 7 +++++++
 xds/googledirectpath/googlec2p.go      | 5 ++++-
 xds/googledirectpath/googlec2p_test.go | 2 +-
 3 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/internal/grpcrand/grpcrand.go b/internal/grpcrand/grpcrand.go
index 200b115ca209..97de06fe7216 100644
--- a/internal/grpcrand/grpcrand.go
+++ b/internal/grpcrand/grpcrand.go
@@ -31,6 +31,13 @@ var (
 	mu sync.Mutex
 )
 
+func Int() int {
+	mu.Lock()
+	res := r.Int()
+	mu.Unlock()
+	return res
+}
+
 // Int63n implements rand.Int63n on the grpcrand global source.
 func Int63n(n int64) int64 {
 	mu.Lock()
diff --git a/xds/googledirectpath/googlec2p.go b/xds/googledirectpath/googlec2p.go
index b514f03bfbfa..af487ec4a736 100644
--- a/xds/googledirectpath/googlec2p.go
+++ b/xds/googledirectpath/googlec2p.go
@@ -35,6 +35,7 @@ import (
 	"google.golang.org/grpc/grpclog"
 	"google.golang.org/grpc/internal/googlecloud"
 	internalgrpclog "google.golang.org/grpc/internal/grpclog"
+	"google.golang.org/grpc/internal/grpcrand"
 	"google.golang.org/grpc/internal/xds/env"
 	"google.golang.org/grpc/resolver"
 	_ "google.golang.org/grpc/xds" // To register xds resolvers and balancers.
@@ -152,13 +153,15 @@ var ipv6EnabledMetadata = &structpb.Struct{
 	},
 }
 
+var id = fmt.Sprintf("C2P-%d", grpcrand.Int())
+
 // newNode makes a copy of defaultNode, and populate it's Metadata and
 // Locality fields.
 func newNode(zone string, ipv6Capable bool) *v3corepb.Node {
 	ret := &v3corepb.Node{
 		// Not all required fields are set in defaultNote. Metadata will be set
 		// if ipv6 is enabled. Locality will be set to the value from metadata.
-		Id:                   "C2P",
+		Id:                   id,
 		UserAgentName:        gRPCUserAgentName,
 		UserAgentVersionType: &v3corepb.Node_UserAgentVersion{UserAgentVersion: grpc.Version},
 		ClientFeatures:       []string{clientFeatureNoOverprovisioning},
diff --git a/xds/googledirectpath/googlec2p_test.go b/xds/googledirectpath/googlec2p_test.go
index 5b8085ef34c3..fb68fa23a1d0 100644
--- a/xds/googledirectpath/googlec2p_test.go
+++ b/xds/googledirectpath/googlec2p_test.go
@@ -194,7 +194,7 @@ func TestBuildXDS(t *testing.T) {
 			}
 
 			wantNode := &v3corepb.Node{
-				Id:                   "C2P",
+				Id:                   id,
 				Metadata:             nil,
 				Locality:             &v3corepb.Locality{Zone: testZone},
 				UserAgentName:        gRPCUserAgentName,