Verify server response cap flags to fail earlier

connection.go

@@ -417,7 +417,7 @@ func (mc *mysqlConn) readIgnoreColumns(rows *textRows, resLen int) (*textRows, e
 		rows.rs.columnNames = make([]string, resLen)
 		return rows, nil
 	}
-	return nil, ErrOptionalResultSet
+	return nil, ErrOptionalResultSetPkt
 }
 
 // Gets the value of the given MySQL System Variable

connector.go

@@ -143,7 +143,7 @@ func (c *connector) Connect(ctx context.Context) (driver.Conn, error) {
 			mc.resultSetMetadata = resultSetMetadataFull
 		default:
 			mc.Close()
-			return nil, ErrOptionalResultSet
+			return nil, ErrOptionalResultSetPkt
 		}
 	}
 

driver_test.go

@@ -202,6 +202,7 @@ func (dbt *DBTest) mustQuery(query string, args ...interface{}) (rows *sql.Rows)
 func maybeSkip(t *testing.T, err error, skipErrno uint16) {
 	mySQLErr, ok := err.(*MySQLError)
 	if !ok {
+		errLog.Print("non match")
 		return
 	}
 
@@ -1348,9 +1349,11 @@ func TestFoundRows(t *testing.T) {
 func TestOptionalResultSetMetadata(t *testing.T) {
 	runTests(t, dsn+"&resultSetMetadata=none", func(dbt *DBTest) {
 		_, err := dbt.db.Exec("CREATE TABLE test (id INT NOT NULL ,data INT NOT NULL)")
-		// Error 1193: Unknown system variable 'resultset_metadata' => skip test,
-		// MySQL server version is too old
-		maybeSkip(t, err, 1193)
+		if err == ErrNoOptionalResultSet {
+			t.Skip("server does not support resultset metadata")
+		} else if err != nil {
+			dbt.Fatal(err)
+		}
 		dbt.mustExec("INSERT INTO test (id, data) VALUES (0, 0),(0, 0),(1, 0),(1, 0),(1, 1)")
 
 		row := dbt.db.QueryRow("SELECT id, data FROM test WHERE id = 1")
@@ -1366,9 +1369,11 @@ func TestOptionalResultSetMetadata(t *testing.T) {
 	})
 	runTests(t, dsn+"&resultSetMetadata=full", func(dbt *DBTest) {
 		_, err := dbt.db.Exec("CREATE TABLE test (id INT NOT NULL ,data INT NOT NULL)")
-		// Error 1193: Unknown system variable 'resultset_metadata' => skip test,
-		// MySQL server version is too old
-		maybeSkip(t, err, 1193)
+		if err == ErrNoOptionalResultSet {
+			t.Skip("server does not support resultset metadata")
+		} else if err != nil {
+			dbt.Fatal(err)
+		}
 		dbt.mustExec("INSERT INTO test (id, data) VALUES (0, 0),(0, 0),(1, 0),(1, 0),(1, 1)")
 
 		row := dbt.db.QueryRow("SELECT id, data FROM test WHERE id = 1")

errors.go

@@ -17,19 +17,20 @@ import (
 
 // Various errors the driver might return. Can change between driver versions.
 var (
-	ErrInvalidConn       = errors.New("invalid connection")
-	ErrMalformPkt        = errors.New("malformed packet")
-	ErrNoTLS             = errors.New("TLS requested but server does not support TLS")
-	ErrCleartextPassword = errors.New("this user requires clear text authentication. If you still want to use it, please add 'allowCleartextPasswords=1' to your DSN")
-	ErrNativePassword    = errors.New("this user requires mysql native password authentication")
-	ErrOldPassword       = errors.New("this user requires old password authentication. If you still want to use it, please add 'allowOldPasswords=1' to your DSN. See also https://github.com/go-sql-driver/mysql/wiki/old_passwords")
-	ErrUnknownPlugin     = errors.New("this authentication plugin is not supported")
-	ErrOldProtocol       = errors.New("MySQL server does not support required protocol 41+")
-	ErrPktSync           = errors.New("commands out of sync. You can't run this command now")
-	ErrPktSyncMul        = errors.New("commands out of sync. Did you run multiple statements at once?")
-	ErrPktTooLarge       = errors.New("packet for query is too large. Try adjusting the 'max_allowed_packet' variable on the server")
-	ErrBusyBuffer        = errors.New("busy buffer")
-	ErrOptionalResultSet = errors.New("malformed optional resultset metadata packets")
+	ErrInvalidConn          = errors.New("invalid connection")
+	ErrMalformPkt           = errors.New("malformed packet")
+	ErrNoTLS                = errors.New("TLS requested but server does not support TLS")
+	ErrCleartextPassword    = errors.New("this user requires clear text authentication. If you still want to use it, please add 'allowCleartextPasswords=1' to your DSN")
+	ErrNativePassword       = errors.New("this user requires mysql native password authentication")
+	ErrOldPassword          = errors.New("this user requires old password authentication. If you still want to use it, please add 'allowOldPasswords=1' to your DSN. See also https://github.com/go-sql-driver/mysql/wiki/old_passwords")
+	ErrUnknownPlugin        = errors.New("this authentication plugin is not supported")
+	ErrOldProtocol          = errors.New("MySQL server does not support required protocol 41+")
+	ErrPktSync              = errors.New("commands out of sync. You can't run this command now")
+	ErrPktSyncMul           = errors.New("commands out of sync. Did you run multiple statements at once?")
+	ErrPktTooLarge          = errors.New("packet for query is too large. Try adjusting the 'max_allowed_packet' variable on the server")
+	ErrBusyBuffer           = errors.New("busy buffer")
+	ErrNoOptionalResultSet  = errors.New("requested optional resultset metadata but server does not support")
+	ErrOptionalResultSetPkt = errors.New("malformed optional resultset metadata packets")
 
 	// errBadConnNoWrite is used for connection errors where nothing was sent to the database yet.
 	// If this happens first in a function starting a database interaction, it should be replaced by driver.ErrBadConn

packets.go

@@ -235,10 +235,18 @@ func (mc *mysqlConn) readHandshakePacket() (data []byte, plugin string, err erro
 	if len(data) > pos {
 		// character set [1 byte]
 		// status flags [2 bytes]
+		pos += 1 + 2
 		// capability flags (upper 2 bytes) [2 bytes]
+		upperFlags := clientFlag(binary.LittleEndian.Uint16(data[pos : pos+2]))
+		mc.flags |= upperFlags << 16
+		pos += 2
+		if mc.flags&clientOptionalResultSetMetadata == 0 && mc.cfg.ResultSetMetadata != "" {
+			return nil, "", ErrNoOptionalResultSet
+		}
+
 		// length of auth-plugin-data [1 byte]
 		// reserved (all [00]) [10 bytes]
-		pos += 1 + 2 + 2 + 1 + 10
+		pos += 1 + 10
 
 		// second part of the password cipher [mininum 13 bytes],
 		// where len=MAX(13, length of auth-plugin-data - 8)
@@ -562,10 +570,10 @@ func (mc *mysqlConn) readResultSetHeaderPacket() (int, error) {
 		// Sniff one extra byte for resultset metadata if we set capability
 		// CLIENT_OPTIONAL_RESULTSET_METADTA
 		// https://dev.mysql.com/worklog/task/?id=8134
-		if len(data) == 2 {
+		if len(data) == 2 && mc.flags&clientOptionalResultSetMetadata != 0 {
 			// ResultSet metadata flag check
 			if mc.resultSetMetadata != data[1] {
-				return 0, ErrOptionalResultSet
+				return 0, ErrOptionalResultSetPkt
 			}
 			return int(num), nil
 		}