From 678b00adf9001d8b866ee259a2f985553e86fcb9 Mon Sep 17 00:00:00 2001
From: James Blair <mail@jamesblair.net>
Date: Mon, 30 Oct 2023 19:30:10 +1300
Subject: [PATCH] Backport clientv3: fix errors init client RejectOldCluster.

Signed-off-by: James Blair <mail@jamesblair.net>
---
 clientv3/client.go      |   4 +-
 clientv3/client_test.go | 106 ++++++++++++++++++++++++++++++++++++++++
 2 files changed, 108 insertions(+), 2 deletions(-)

diff --git a/clientv3/client.go b/clientv3/client.go
index 3c2317faa..b943ae0f6 100644
--- a/clientv3/client.go
+++ b/clientv3/client.go
@@ -539,7 +539,7 @@ func (c *Client) checkVersion() (err error) {
 					return
 				}
 			}
-			if maj < 3 || (maj == 3 && min < 2) {
+			if maj < 3 || (maj == 3 && min < 3) {
 				rerr = ErrOldCluster
 			}
 			errc <- rerr
@@ -547,7 +547,7 @@ func (c *Client) checkVersion() (err error) {
 	}
 	// wait for success
 	for range eps {
-		if err = <-errc; err == nil {
+		if err = <-errc; err != nil {
 			break
 		}
 	}
diff --git a/clientv3/client_test.go b/clientv3/client_test.go
index a6d9fc439..494733c06 100644
--- a/clientv3/client_test.go
+++ b/clientv3/client_test.go
@@ -17,7 +17,9 @@ package clientv3
 import (
 	"context"
 	"fmt"
+	"io"
 	"net"
+	"sync"
 	"testing"
 	"time"
 
@@ -188,6 +190,110 @@ func TestSyncFiltersMembers(t *testing.T) {
 	c.Close()
 }
 
+func TestClientRejectOldCluster(t *testing.T) {
+	defer testutil.AfterTest(t)
+	var tests = []struct {
+		name          string
+		endpoints     []string
+		versions      []string
+		expectedError error
+	}{
+		{
+			name:          "all new versions with the same value",
+			endpoints:     []string{"192.168.3.41:22379", "192.168.3.41:22479", "192.168.3.41:22579"},
+			versions:      []string{"3.4.4", "3.4.4", "3.4.4"},
+			expectedError: nil,
+		},
+		{
+			name:          "all new versions with different values",
+			endpoints:     []string{"192.168.3.41:22379", "192.168.3.41:22479", "192.168.3.41:22579"},
+			versions:      []string{"3.4.4", "3.4.4", "3.4.0"},
+			expectedError: nil,
+		},
+		{
+			name:          "all old versions with different values",
+			endpoints:     []string{"192.168.3.41:22379", "192.168.3.41:22479", "192.168.3.41:22579"},
+			versions:      []string{"3.2.0", "3.2.0", "3.3.0"},
+			expectedError: ErrOldCluster,
+		},
+		{
+			name:          "all old versions with the same value",
+			endpoints:     []string{"192.168.3.41:22379", "192.168.3.41:22479", "192.168.3.41:22579"},
+			versions:      []string{"3.2.0", "3.2.0", "3.2.0"},
+			expectedError: ErrOldCluster,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if len(tt.endpoints) != len(tt.versions) || len(tt.endpoints) == 0 {
+				t.Errorf("Unexpected endpoints and versions length, len(endpoints):%d, len(versions):%d", len(tt.endpoints), len(tt.versions))
+				return
+			}
+			endpointToVersion := make(map[string]string)
+			for j := range tt.endpoints {
+				endpointToVersion[tt.endpoints[j]] = tt.versions[j]
+			}
+			c := &Client{
+				ctx: context.Background(),
+				cfg: Config{
+					Endpoints: tt.endpoints,
+				},
+				Maintenance: &mockMaintenance{
+					Version: endpointToVersion,
+				},
+				mu: new(sync.RWMutex),
+			}
+
+			if err := c.checkVersion(); err != tt.expectedError {
+				t.Errorf("checkVersion err:%v", err)
+			}
+		})
+
+	}
+
+}
+
+type mockMaintenance struct {
+	Version map[string]string
+}
+
+func (mm mockMaintenance) Status(ctx context.Context, endpoint string) (*StatusResponse, error) {
+	return &StatusResponse{Version: mm.Version[endpoint]}, nil
+}
+
+func (mm mockMaintenance) AlarmList(ctx context.Context) (*AlarmResponse, error) {
+	return nil, nil
+}
+
+func (mm mockMaintenance) AlarmDisarm(ctx context.Context, m *AlarmMember) (*AlarmResponse, error) {
+	return nil, nil
+}
+
+func (mm mockMaintenance) Defragment(ctx context.Context, endpoint string) (*DefragmentResponse, error) {
+	return nil, nil
+}
+
+func (mm mockMaintenance) HashKV(ctx context.Context, endpoint string, rev int64) (*HashKVResponse, error) {
+	return nil, nil
+}
+
+func (mm mockMaintenance) SnapshotWithVersion(ctx context.Context) error {
+	return nil
+}
+
+func (mm mockMaintenance) Snapshot(ctx context.Context) (io.ReadCloser, error) {
+	return nil, nil
+}
+
+func (mm mockMaintenance) MoveLeader(ctx context.Context, transfereeID uint64) (*MoveLeaderResponse, error) {
+	return nil, nil
+}
+
+func (mm mockMaintenance) Downgrade(ctx context.Context, version string) error {
+	return nil
+}
+
 type mockCluster struct {
 	members []*etcdserverpb.Member
 }