server: validate each --join endpoint separately

server/config/config.go

@@ -18,7 +18,6 @@ import (
 	"crypto/tls"
 	"encoding/json"
 	"fmt"
-	"net/url"
 	"os"
 	"path/filepath"
 	"strings"
@@ -391,8 +390,12 @@ func (c *Config) Adjust(meta *toml.MetaData, reloading bool) error {
 	configutil.AdjustString(&c.InitialClusterState, defaultInitialClusterState)
 	configutil.AdjustString(&c.InitialClusterToken, defaultInitialClusterToken)
 
+	// Join is a comma-separated list of endpoints (see the field comment and
+	// server/join, which splits it on ","), so validate it per endpoint rather
+	// than passing the whole list to a single url.Parse, which accepts it as
+	// one malformed URL with a host of "pd-0:2379,http:".
 	if len(c.Join) > 0 {
-		if _, err := url.Parse(c.Join); err != nil {
+		if _, err := parseUrls(c.Join); err != nil {
 			return errors.Errorf("failed to parse join addr:%s, err:%v", c.Join, err)
 		}
 	}

server/config/config_test.go

@@ -62,6 +62,51 @@ func TestBadFormatJoinAddr(t *testing.T) {
 	re.Error(cfg.Adjust(nil, false))
 }
 
+// TestJoinAddr covers that --join accepts the comma-separated endpoint list it
+// is documented to take, and still rejects a list containing a bad endpoint.
+func TestJoinAddr(t *testing.T) {
+	testCases := []struct {
+		name    string
+		join    string
+		wantErr bool
+	}{
+		{
+			name: "single endpoint",
+			join: "http://127.0.0.1:2379",
+		},
+		{
+			name: "two endpoints",
+			join: "http://127.0.0.1:2379,http://127.0.0.1:2381",
+		},
+		{
+			name: "three endpoints with mixed schemes",
+			join: "http://pd-0.pd-peer:2379,https://pd-1.pd-peer:2379,http://[::1]:2379",
+		},
+		{
+			name: "peer service endpoints",
+			join: "http://demo-pd-0.demo-pd-peer.demo.svc:2380,http://demo-pd-1.demo-pd-peer.demo.svc:2380",
+		},
+		{
+			name:    "second endpoint has no scheme",
+			join:    "http://127.0.0.1:2379,127.0.0.1:2381",
+			wantErr: true,
+		},
+	}
+	for _, testCase := range testCases {
+		t.Run(testCase.name, func(t *testing.T) {
+			re := require.New(t)
+			cfg := NewConfig()
+			cfg.Join = testCase.join
+			err := cfg.Adjust(nil, false)
+			if testCase.wantErr {
+				re.Error(err)
+				return
+			}
+			re.NoError(err)
+		})
+	}
+}
+
 func TestReloadConfig(t *testing.T) {
 	re := require.New(t)
 	opt, err := newTestScheduleOption()