add support unix socket for GRPC (#5943)

plugin/pkg/parse/host.go

@@ -33,6 +33,14 @@ func HostPortOrFile(s ...string) ([]string, error) {
 	var servers []string
 	for _, h := range s {
 		trans, host := Transport(h)
+		if len(host) == 0 {
+			return servers, fmt.Errorf("invalid address: %q", h)
+		}
+
+		if trans == transport.UNIX {
+			servers = append(servers, trans+"://"+host)
+			continue
+		}
 
 		addr, _, err := net.SplitHostPort(host)
 

plugin/pkg/parse/host_test.go

@@ -58,6 +58,16 @@ func TestHostPortOrFile(t *testing.T) {
 			"",
 			true,
 		},
+		{
+			"unix:///var/run/g.sock",
+			"unix:///var/run/g.sock",
+			false,
+		},
+		{
+			"unix://",
+			"",
+			true,
+		},
 	}
 
 	err := os.WriteFile("resolv.conf", []byte("nameserver 127.0.0.1\n"), 0600)

plugin/pkg/parse/transport.go

@@ -27,6 +27,9 @@ func Transport(s string) (trans string, addr string) {
 		s = s[len(transport.HTTPS+"://"):]
 
 		return transport.HTTPS, s
+	case strings.HasPrefix(s, transport.UNIX+"://"):
+		s = s[len(transport.UNIX+"://"):]
+		return transport.UNIX, s
 	}
 
 	return transport.DNS, s

plugin/pkg/transport/transport.go

@@ -6,6 +6,7 @@ const (
 	TLS   = "tls"
 	GRPC  = "grpc"
 	HTTPS = "https"
+	UNIX  = "unix"
 )
 
 // Port numbers for the various transports.