upgrade go-sql-driver/mysql to fix invalid connection error (#5748)

should fix #5736

11 files changed, 463 insertions, 519 deletions

diff --git a/vendor/github.com/go-sql-driver/mysql/AUTHORS b/vendor/github.com/go-sql-driver/mysql/AUTHORS
index 73ff68fbcf..5ce4f7eca1 100644
--- a/vendor/github.com/go-sql-driver/mysql/AUTHORS
+++ b/vendor/github.com/go-sql-driver/mysql/AUTHORS
@@ -35,6 +35,7 @@ Hanno Braun <mail at hannobraun.com>
 Henri Yandell <flamefew at gmail.com>
 Hirotaka Yamamoto <ymmt2005 at gmail.com>
 ICHINOSE Shogo <shogo82148 at gmail.com>
+Ilia Cimpoes <ichimpoesh at gmail.com>
 INADA Naoki <songofacandy at gmail.com>
 Jacek Szwec <szwec.jacek at gmail.com>
 James Harr <james.harr at gmail.com>
@@ -72,6 +73,9 @@ Shuode Li <elemount at qq.com>
 Soroush Pour <me at soroushjp.com>
 Stan Putrya <root.vagner at gmail.com>
 Stanley Gunawan <gunawan.stanley at gmail.com>
+Steven Hartland <steven.hartland at multiplay.co.uk>
+Thomas Wodarek <wodarekwebpage at gmail.com>
+Tom Jenkinson <tom at tjenkinson.me>
 Xiangyu Hu <xiangyu.hu at outlook.com>
 Xiaobing Jiang <s7v7nislands at gmail.com>
 Xiuming Chen <cc at cxm.cc>
@@ -87,3 +91,4 @@ Keybase Inc.
 Percona LLC
 Pivotal Inc.
 Stripe Inc.
+Multiplay Ltd.
diff --git a/vendor/github.com/go-sql-driver/mysql/auth.go b/vendor/github.com/go-sql-driver/mysql/auth.go
index 0b59f52ee7..fec7040d4a 100644
--- a/vendor/github.com/go-sql-driver/mysql/auth.go
+++ b/vendor/github.com/go-sql-driver/mysql/auth.go
@@ -234,64 +234,64 @@ func (mc *mysqlConn) sendEncryptedPassword(seed []byte, pub *rsa.PublicKey) erro
 	if err != nil {
 		return err
 	}
-	return mc.writeAuthSwitchPacket(enc, false)
+	return mc.writeAuthSwitchPacket(enc)
 }
 
-func (mc *mysqlConn) auth(authData []byte, plugin string) ([]byte, bool, error) {
+func (mc *mysqlConn) auth(authData []byte, plugin string) ([]byte, error) {
 	switch plugin {
 	case "caching_sha2_password":
 		authResp := scrambleSHA256Password(authData, mc.cfg.Passwd)
-		return authResp, (authResp == nil), nil
+		return authResp, nil
 
 	case "mysql_old_password":
 		if !mc.cfg.AllowOldPasswords {
-			return nil, false, ErrOldPassword
+			return nil, ErrOldPassword
 		}
 		// Note: there are edge cases where this should work but doesn't;
 		// this is currently "wontfix":
 		// https://github.com/go-sql-driver/mysql/issues/184
-		authResp := scrambleOldPassword(authData[:8], mc.cfg.Passwd)
-		return authResp, true, nil
+		authResp := append(scrambleOldPassword(authData[:8], mc.cfg.Passwd), 0)
+		return authResp, nil
 
 	case "mysql_clear_password":
 		if !mc.cfg.AllowCleartextPasswords {
-			return nil, false, ErrCleartextPassword
+			return nil, ErrCleartextPassword
 		}
 		// http://dev.mysql.com/doc/refman/5.7/en/cleartext-authentication-plugin.html
 		// http://dev.mysql.com/doc/refman/5.7/en/pam-authentication-plugin.html
-		return []byte(mc.cfg.Passwd), true, nil
+		return append([]byte(mc.cfg.Passwd), 0), nil
 
 	case "mysql_native_password":
 		if !mc.cfg.AllowNativePasswords {
-			return nil, false, ErrNativePassword
+			return nil, ErrNativePassword
 		}
 		// https://dev.mysql.com/doc/internals/en/secure-password-authentication.html
 		// Native password authentication only need and will need 20-byte challenge.
 		authResp := scramblePassword(authData[:20], mc.cfg.Passwd)
-		return authResp, false, nil
+		return authResp, nil
 
 	case "sha256_password":
 		if len(mc.cfg.Passwd) == 0 {
-			return nil, true, nil
+			return []byte{0}, nil
 		}
 		if mc.cfg.tls != nil || mc.cfg.Net == "unix" {
 			// write cleartext auth packet
-			return []byte(mc.cfg.Passwd), true, nil
+			return append([]byte(mc.cfg.Passwd), 0), nil
 		}
 
 		pubKey := mc.cfg.pubKey
 		if pubKey == nil {
 			// request public key from server
-			return []byte{1}, false, nil
+			return []byte{1}, nil
 		}
 
 		// encrypted password
 		enc, err := encryptPassword(mc.cfg.Passwd, authData, pubKey)
-		return enc, false, err
+		return enc, err
 
 	default:
 		errLog.Print("unknown auth plugin:", plugin)
-		return nil, false, ErrUnknownPlugin
+		return nil, ErrUnknownPlugin
 	}
 }
 
@@ -315,11 +315,11 @@ func (mc *mysqlConn) handleAuthResult(oldAuthData []byte, plugin string) error {
 
 		plugin = newPlugin
 
-		authResp, addNUL, err := mc.auth(authData, plugin)
+		authResp, err := mc.auth(authData, plugin)
 		if err != nil {
 			return err
 		}
-		if err = mc.writeAuthSwitchPacket(authResp, addNUL); err != nil {
+		if err = mc.writeAuthSwitchPacket(authResp); err != nil {
 			return err
 		}
 
@@ -352,7 +352,7 @@ func (mc *mysqlConn) handleAuthResult(oldAuthData []byte, plugin string) error {
 			case cachingSha2PasswordPerformFullAuthentication:
 				if mc.cfg.tls != nil || mc.cfg.Net == "unix" {
 					// write cleartext auth packet
-					err = mc.writeAuthSwitchPacket([]byte(mc.cfg.Passwd), true)
+					err = mc.writeAuthSwitchPacket(append([]byte(mc.cfg.Passwd), 0))
 					if err != nil {
 						return err
 					}
@@ -360,13 +360,15 @@ func (mc *mysqlConn) handleAuthResult(oldAuthData []byte, plugin string) error {
 					pubKey := mc.cfg.pubKey
 					if pubKey == nil {
 						// request public key from server
-						data := mc.buf.takeSmallBuffer(4 + 1)
+						data, err := mc.buf.takeSmallBuffer(4 + 1)
+						if err != nil {
+							return err
+						}
 						data[4] = cachingSha2PasswordRequestPublicKey
 						mc.writePacket(data)
 
 						// parse public key
-						data, err := mc.readPacket()
-						if err != nil {
+						if data, err = mc.readPacket(); err != nil {
 							return err
 						}
 
diff --git a/vendor/github.com/go-sql-driver/mysql/buffer.go b/vendor/github.com/go-sql-driver/mysql/buffer.go
index eb4748bf44..19486bd6f6 100644
--- a/vendor/github.com/go-sql-driver/mysql/buffer.go
+++ b/vendor/github.com/go-sql-driver/mysql/buffer.go
@@ -22,17 +22,17 @@ const defaultBufSize = 4096
 // The buffer is similar to bufio.Reader / Writer but zero-copy-ish
 // Also highly optimized for this particular use case.
 type buffer struct {
-	buf     []byte
+	buf     []byte // buf is a byte buffer who's length and capacity are equal.
 	nc      net.Conn
 	idx     int
 	length  int
 	timeout time.Duration
 }
 
+// newBuffer allocates and returns a new buffer.
 func newBuffer(nc net.Conn) buffer {
-	var b [defaultBufSize]byte
 	return buffer{
-		buf: b[:],
+		buf: make([]byte, defaultBufSize),
 		nc:  nc,
 	}
 }
@@ -105,43 +105,56 @@ func (b *buffer) readNext(need int) ([]byte, error) {
 	return b.buf[offset:b.idx], nil
 }
 
-// returns a buffer with the requested size.
+// takeBuffer returns a buffer with the requested size.
 // If possible, a slice from the existing buffer is returned.
 // Otherwise a bigger buffer is made.
 // Only one buffer (total) can be used at a time.
-func (b *buffer) takeBuffer(length int) []byte {
+func (b *buffer) takeBuffer(length int) ([]byte, error) {
 	if b.length > 0 {
-		return nil
+		return nil, ErrBusyBuffer
 	}
 
 	// test (cheap) general case first
-	if length <= defaultBufSize || length <= cap(b.buf) {
-		return b.buf[:length]
+	if length <= cap(b.buf) {
+		return b.buf[:length], nil
 	}
 
 	if length < maxPacketSize {
 		b.buf = make([]byte, length)
-		return b.buf
+		return b.buf, nil
 	}
-	return make([]byte, length)
+
+	// buffer is larger than we want to store.
+	return make([]byte, length), nil
 }
 
-// shortcut which can be used if the requested buffer is guaranteed to be
-// smaller than defaultBufSize
+// takeSmallBuffer is shortcut which can be used if length is
+// known to be smaller than defaultBufSize.
 // Only one buffer (total) can be used at a time.
-func (b *buffer) takeSmallBuffer(length int) []byte {
+func (b *buffer) takeSmallBuffer(length int) ([]byte, error) {
 	if b.length > 0 {
-		return nil
+		return nil, ErrBusyBuffer
 	}
-	return b.buf[:length]
+	return b.buf[:length], nil
 }
 
 // takeCompleteBuffer returns the complete existing buffer.
 // This can be used if the necessary buffer size is unknown.
+// cap and len of the returned buffer will be equal.
 // Only one buffer (total) can be used at a time.
-func (b *buffer) takeCompleteBuffer() []byte {
+func (b *buffer) takeCompleteBuffer() ([]byte, error) {
+	if b.length > 0 {
+		return nil, ErrBusyBuffer
+	}
+	return b.buf, nil
+}
+
+// store stores buf, an updated buffer, if its suitable to do so.
+func (b *buffer) store(buf []byte) error {
 	if b.length > 0 {
-		return nil
+		return ErrBusyBuffer
+	} else if cap(buf) <= maxPacketSize && cap(buf) > cap(b.buf) {
+		b.buf = buf[:cap(buf)]
 	}
-	return b.buf
+	return nil
 }
diff --git a/vendor/github.com/go-sql-driver/mysql/connection.go b/vendor/github.com/go-sql-driver/mysql/connection.go
index e57061412b..fc4ec7597d 100644
--- a/vendor/github.com/go-sql-driver/mysql/connection.go
+++ b/vendor/github.com/go-sql-driver/mysql/connection.go
@@ -9,6 +9,8 @@
 package mysql
 
 import (
+	"context"
+	"database/sql"
 	"database/sql/driver"
 	"io"
 	"net"
@@ -17,16 +19,6 @@ import (
 	"time"
 )
 
-// a copy of context.Context for Go 1.7 and earlier
-type mysqlContext interface {
-	Done() <-chan struct{}
-	Err() error
-
-	// defined in context.Context, but not used in this driver:
-	// Deadline() (deadline time.Time, ok bool)
-	// Value(key interface{}) interface{}
-}
-
 type mysqlConn struct {
 	buf              buffer
 	netConn          net.Conn
@@ -43,7 +35,7 @@ type mysqlConn struct {
 
 	// for context support (Go 1.8+)
 	watching bool
-	watcher  chan<- mysqlContext
+	watcher  chan<- context.Context
 	closech  chan struct{}
 	finished chan<- struct{}
 	canceled atomicError // set non-nil if conn is canceled
@@ -190,10 +182,10 @@ func (mc *mysqlConn) interpolateParams(query string, args []driver.Value) (strin
 		return "", driver.ErrSkip
 	}
 
-	buf := mc.buf.takeCompleteBuffer()
-	if buf == nil {
+	buf, err := mc.buf.takeCompleteBuffer()
+	if err != nil {
 		// can not take the buffer. Something must be wrong with the connection
-		errLog.Print(ErrBusyBuffer)
+		errLog.Print(err)
 		return "", ErrInvalidConn
 	}
 	buf = buf[:0]
@@ -459,3 +451,193 @@ func (mc *mysqlConn) finish() {
 	case <-mc.closech:
 	}
 }
+
+// Ping implements driver.Pinger interface
+func (mc *mysqlConn) Ping(ctx context.Context) (err error) {
+	if mc.closed.IsSet() {
+		errLog.Print(ErrInvalidConn)
+		return driver.ErrBadConn
+	}
+
+	if err = mc.watchCancel(ctx); err != nil {
+		return
+	}
+	defer mc.finish()
+
+	if err = mc.writeCommandPacket(comPing); err != nil {
+		return mc.markBadConn(err)
+	}
+
+	return mc.readResultOK()
+}
+
+// BeginTx implements driver.ConnBeginTx interface
+func (mc *mysqlConn) BeginTx(ctx context.Context, opts driver.TxOptions) (driver.Tx, error) {
+	if err := mc.watchCancel(ctx); err != nil {
+		return nil, err
+	}
+	defer mc.finish()
+
+	if sql.IsolationLevel(opts.Isolation) != sql.LevelDefault {
+		level, err := mapIsolationLevel(opts.Isolation)
+		if err != nil {
+			return nil, err
+		}
+		err = mc.exec("SET TRANSACTION ISOLATION LEVEL " + level)
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	return mc.begin(opts.ReadOnly)
+}
+
+func (mc *mysqlConn) QueryContext(ctx context.Context, query string, args []driver.NamedValue) (driver.Rows, error) {
+	dargs, err := namedValueToValue(args)
+	if err != nil {
+		return nil, err
+	}
+
+	if err := mc.watchCancel(ctx); err != nil {
+		return nil, err
+	}
+
+	rows, err := mc.query(query, dargs)
+	if err != nil {
+		mc.finish()
+		return nil, err
+	}
+	rows.finish = mc.finish
+	return rows, err
+}
+
+func (mc *mysqlConn) ExecContext(ctx context.Context, query string, args []driver.NamedValue) (driver.Result, error) {
+	dargs, err := namedValueToValue(args)
+	if err != nil {
+		return nil, err
+	}
+
+	if err := mc.watchCancel(ctx); err != nil {
+		return nil, err
+	}
+	defer mc.finish()
+
+	return mc.Exec(query, dargs)
+}
+
+func (mc *mysqlConn) PrepareContext(ctx context.Context, query string) (driver.Stmt, error) {
+	if err := mc.watchCancel(ctx); err != nil {
+		return nil, err
+	}
+
+	stmt, err := mc.Prepare(query)
+	mc.finish()
+	if err != nil {
+		return nil, err
+	}
+
+	select {
+	default:
+	case <-ctx.Done():
+		stmt.Close()
+		return nil, ctx.Err()
+	}
+	return stmt, nil
+}
+
+func (stmt *mysqlStmt) QueryContext(ctx context.Context, args []driver.NamedValue) (driver.Rows, error) {
+	dargs, err := namedValueToValue(args)
+	if err != nil {
+		return nil, err
+	}
+
+	if err := stmt.mc.watchCancel(ctx); err != nil {
+		return nil, err
+	}
+
+	rows, err := stmt.query(dargs)
+	if err != nil {
+		stmt.mc.finish()
+		return nil, err
+	}
+	rows.finish = stmt.mc.finish
+	return rows, err
+}
+
+func (stmt *mysqlStmt) ExecContext(ctx context.Context, args []driver.NamedValue) (driver.Result, error) {
+	dargs, err := namedValueToValue(args)
+	if err != nil {
+		return nil, err
+	}
+
+	if err := stmt.mc.watchCancel(ctx); err != nil {
+		return nil, err
+	}
+	defer stmt.mc.finish()
+
+	return stmt.Exec(dargs)
+}
+
+func (mc *mysqlConn) watchCancel(ctx context.Context) error {
+	if mc.watching {
+		// Reach here if canceled,
+		// so the connection is already invalid
+		mc.cleanup()
+		return nil
+	}
+	// When ctx is already cancelled, don't watch it.
+	if err := ctx.Err(); err != nil {
+		return err
+	}
+	// When ctx is not cancellable, don't watch it.
+	if ctx.Done() == nil {
+		return nil
+	}
+	// When watcher is not alive, can't watch it.
+	if mc.watcher == nil {
+		return nil
+	}
+
+	mc.watching = true
+	mc.watcher <- ctx
+	return nil
+}
+
+func (mc *mysqlConn) startWatcher() {
+	watcher := make(chan context.Context, 1)
+	mc.watcher = watcher
+	finished := make(chan struct{})
+	mc.finished = finished
+	go func() {
+		for {
+			var ctx context.Context
+			select {
+			case ctx = <-watcher:
+			case <-mc.closech:
+				return
+			}
+
+			select {
+			case <-ctx.Done():
+				mc.cancel(ctx.Err())
+			case <-finished:
+			case <-mc.closech:
+				return
+			}
+		}
+	}()
+}
+
+func (mc *mysqlConn) CheckNamedValue(nv *driver.NamedValue) (err error) {
+	nv.Value, err = converter{}.ConvertValue(nv.Value)
+	return
+}
+
+// ResetSession implements driver.SessionResetter.
+// (From Go 1.10)
+func (mc *mysqlConn) ResetSession(ctx context.Context) error {
+	if mc.closed.IsSet() {
+		return driver.ErrBadConn
+	}
+	return nil
+}
diff --git a/vendor/github.com/go-sql-driver/mysql/connection_go18.go b/vendor/github.com/go-sql-driver/mysql/connection_go18.go
deleted file mode 100644
index 62796bfcea..0000000000
--- a/vendor/github.com/go-sql-driver/mysql/connection_go18.go
+++ /dev/null
@@ -1,208 +0,0 @@
-// Go MySQL Driver - A MySQL-Driver for Go's database/sql package
-//
-// Copyright 2012 The Go-MySQL-Driver Authors. All rights reserved.
-//
-// This Source Code Form is subject to the terms of the Mozilla Public
-// License, v. 2.0. If a copy of the MPL was not distributed with this file,
-// You can obtain one at http://mozilla.org/MPL/2.0/.
-
-// +build go1.8
-
-package mysql
-
-import (
-	"context"
-	"database/sql"
-	"database/sql/driver"
-)
-
-// Ping implements driver.Pinger interface
-func (mc *mysqlConn) Ping(ctx context.Context) (err error) {
-	if mc.closed.IsSet() {
-		errLog.Print(ErrInvalidConn)
-		return driver.ErrBadConn
-	}
-
-	if err = mc.watchCancel(ctx); err != nil {
-		return
-	}
-	defer mc.finish()
-
-	if err = mc.writeCommandPacket(comPing); err != nil {
-		return
-	}
-
-	return mc.readResultOK()
-}
-
-// BeginTx implements driver.ConnBeginTx interface
-func (mc *mysqlConn) BeginTx(ctx context.Context, opts driver.TxOptions) (driver.Tx, error) {
-	if err := mc.watchCancel(ctx); err != nil {
-		return nil, err
-	}
-	defer mc.finish()
-
-	if sql.IsolationLevel(opts.Isolation) != sql.LevelDefault {
-		level, err := mapIsolationLevel(opts.Isolation)
-		if err != nil {
-			return nil, err
-		}
-		err = mc.exec("SET TRANSACTION ISOLATION LEVEL " + level)
-		if err != nil {
-			return nil, err
-		}
-	}
-
-	return mc.begin(opts.ReadOnly)
-}
-
-func (mc *mysqlConn) QueryContext(ctx context.Context, query string, args []driver.NamedValue) (driver.Rows, error) {
-	dargs, err := namedValueToValue(args)
-	if err != nil {
-		return nil, err
-	}
-
-	if err := mc.watchCancel(ctx); err != nil {
-		return nil, err
-	}
-
-	rows, err := mc.query(query, dargs)
-	if err != nil {
-		mc.finish()
-		return nil, err
-	}
-	rows.finish = mc.finish
-	return rows, err
-}
-
-func (mc *mysqlConn) ExecContext(ctx context.Context, query string, args []driver.NamedValue) (driver.Result, error) {
-	dargs, err := namedValueToValue(args)
-	if err != nil {
-		return nil, err
-	}
-
-	if err := mc.watchCancel(ctx); err != nil {
-		return nil, err
-	}
-	defer mc.finish()
-
-	return mc.Exec(query, dargs)
-}
-
-func (mc *mysqlConn) PrepareContext(ctx context.Context, query string) (driver.Stmt, error) {
-	if err := mc.watchCancel(ctx); err != nil {
-		return nil, err
-	}
-
-	stmt, err := mc.Prepare(query)
-	mc.finish()
-	if err != nil {
-		return nil, err
-	}
-
-	select {
-	default:
-	case <-ctx.Done():
-		stmt.Close()
-		return nil, ctx.Err()
-	}
-	return stmt, nil
-}
-
-func (stmt *mysqlStmt) QueryContext(ctx context.Context, args []driver.NamedValue) (driver.Rows, error) {
-	dargs, err := namedValueToValue(args)
-	if err != nil {
-		return nil, err
-	}
-
-	if err := stmt.mc.watchCancel(ctx); err != nil {
-		return nil, err
-	}
-
-	rows, err := stmt.query(dargs)
-	if err != nil {
-		stmt.mc.finish()
-		return nil, err
-	}
-	rows.finish = stmt.mc.finish
-	return rows, err
-}
-
-func (stmt *mysqlStmt) ExecContext(ctx context.Context, args []driver.NamedValue) (driver.Result, error) {
-	dargs, err := namedValueToValue(args)
-	if err != nil {
-		return nil, err
-	}
-
-	if err := stmt.mc.watchCancel(ctx); err != nil {
-		return nil, err
-	}
-	defer stmt.mc.finish()
-
-	return stmt.Exec(dargs)
-}
-
-func (mc *mysqlConn) watchCancel(ctx context.Context) error {
-	if mc.watching {
-		// Reach here if canceled,
-		// so the connection is already invalid
-		mc.cleanup()
-		return nil
-	}
-	if ctx.Done() == nil {
-		return nil
-	}
-
-	mc.watching = true
-	select {
-	default:
-	case <-ctx.Done():
-		return ctx.Err()
-	}
-	if mc.watcher == nil {
-		return nil
-	}
-
-	mc.watcher <- ctx
-
-	return nil
-}
-
-func (mc *mysqlConn) startWatcher() {
-	watcher := make(chan mysqlContext, 1)
-	mc.watcher = watcher
-	finished := make(chan struct{})
-	mc.finished = finished
-	go func() {
-		for {
-			var ctx mysqlContext
-			select {
-			case ctx = <-watcher:
-			case <-mc.closech:
-				return
-			}
-
-			select {
-			case <-ctx.Done():
-				mc.cancel(ctx.Err())
-			case <-finished:
-			case <-mc.closech:
-				return
-			}
-		}
-	}()
-}
-
-func (mc *mysqlConn) CheckNamedValue(nv *driver.NamedValue) (err error) {
-	nv.Value, err = converter{}.ConvertValue(nv.Value)
-	return
-}
-
-// ResetSession implements driver.SessionResetter.
-// (From Go 1.10)
-func (mc *mysqlConn) ResetSession(ctx context.Context) error {
-	if mc.closed.IsSet() {
-		return driver.ErrBadConn
-	}
-	return nil
-}
diff --git a/vendor/github.com/go-sql-driver/mysql/driver.go b/vendor/github.com/go-sql-driver/mysql/driver.go
index 1a75a16ecf..9f4967087f 100644
--- a/vendor/github.com/go-sql-driver/mysql/driver.go
+++ b/vendor/github.com/go-sql-driver/mysql/driver.go
@@ -23,11 +23,6 @@ import (
 	"sync"
 )
 
-// watcher interface is used for context support (From Go 1.8)
-type watcher interface {
-	startWatcher()
-}
-
 // MySQLDriver is exported to make the driver directly accessible.
 // In general the driver is used via the database/sql package.
 type MySQLDriver struct{}
@@ -55,7 +50,7 @@ func RegisterDial(net string, dial DialFunc) {
 
 // Open new Connection.
 // See https://github.com/go-sql-driver/mysql#dsn-data-source-name for how
-// the DSN string is formated
+// the DSN string is formatted
 func (d MySQLDriver) Open(dsn string) (driver.Conn, error) {
 	var err error
 
@@ -82,6 +77,10 @@ func (d MySQLDriver) Open(dsn string) (driver.Conn, error) {
 		mc.netConn, err = nd.Dial(mc.cfg.Net, mc.cfg.Addr)
 	}
 	if err != nil {
+		if nerr, ok := err.(net.Error); ok && nerr.Temporary() {
+			errLog.Print("net.Error from Dial()': ", nerr.Error())
+			return nil, driver.ErrBadConn
+		}
 		return nil, err
 	}
 
@@ -96,9 +95,7 @@ func (d MySQLDriver) Open(dsn string) (driver.Conn, error) {
 	}
 
 	// Call startWatcher for context support (From Go 1.8)
-	if s, ok := interface{}(mc).(watcher); ok {
-		s.startWatcher()
-	}
+	mc.startWatcher()
 
 	mc.buf = newBuffer(mc.netConn)
 
@@ -112,20 +109,23 @@ func (d MySQLDriver) Open(dsn string) (driver.Conn, error) {
 		mc.cleanup()
 		return nil, err
 	}
+	if plugin == "" {
+		plugin = defaultAuthPlugin
+	}
 
 	// Send Client Authentication Packet
-	authResp, addNUL, err := mc.auth(authData, plugin)
+	authResp, err := mc.auth(authData, plugin)
 	if err != nil {
 		// try the default auth plugin, if using the requested plugin failed
 		errLog.Print("could not use requested auth plugin '"+plugin+"': ", err.Error())
 		plugin = defaultAuthPlugin
-		authResp, addNUL, err = mc.auth(authData, plugin)
+		authResp, err = mc.auth(authData, plugin)
 		if err != nil {
 			mc.cleanup()
 			return nil, err
 		}
 	}
-	if err = mc.writeHandshakeResponsePacket(authResp, addNUL, plugin); err != nil {
+	if err = mc.writeHandshakeResponsePacket(authResp, plugin); err != nil {
 		mc.cleanup()
 		return nil, err
 	}
diff --git a/vendor/github.com/go-sql-driver/mysql/dsn.go b/vendor/github.com/go-sql-driver/mysql/dsn.go
index be014babe3..b9134722eb 100644
--- a/vendor/github.com/go-sql-driver/mysql/dsn.go
+++ b/vendor/github.com/go-sql-driver/mysql/dsn.go
@@ -560,7 +560,7 @@ func parseDSNParams(cfg *Config, params string) (err error) {
 				} else {
 					cfg.TLSConfig = "false"
 				}
-			} else if vl := strings.ToLower(value); vl == "skip-verify" {
+			} else if vl := strings.ToLower(value); vl == "skip-verify" || vl == "preferred" {
 				cfg.TLSConfig = vl
 				cfg.tls = &tls.Config{InsecureSkipVerify: true}
 			} else {
diff --git a/vendor/github.com/go-sql-driver/mysql/packets.go b/vendor/github.com/go-sql-driver/mysql/packets.go
index d873a97b2f..5e0853767d 100644
--- a/vendor/github.com/go-sql-driver/mysql/packets.go
+++ b/vendor/github.com/go-sql-driver/mysql/packets.go
@@ -51,7 +51,7 @@ func (mc *mysqlConn) readPacket() ([]byte, error) {
 		mc.sequence++
 
 		// packets with length 0 terminate a previous packet which is a
-		// multiple of (2^24)−1 bytes long
+		// multiple of (2^24)-1 bytes long
 		if pktLen == 0 {
 			// there was no previous packet
 			if prevData == nil {
@@ -154,15 +154,15 @@ func (mc *mysqlConn) writePacket(data []byte) error {
 
 // Handshake Initialization Packet
 // http://dev.mysql.com/doc/internals/en/connection-phase-packets.html#packet-Protocol::Handshake
-func (mc *mysqlConn) readHandshakePacket() ([]byte, string, error) {
-	data, err := mc.readPacket()
+func (mc *mysqlConn) readHandshakePacket() (data []byte, plugin string, err error) {
+	data, err = mc.readPacket()
 	if err != nil {
 		// for init we can rewrite this to ErrBadConn for sql.Driver to retry, since
 		// in connection initialization we don't risk retrying non-idempotent actions.
 		if err == ErrInvalidConn {
 			return nil, "", driver.ErrBadConn
 		}
-		return nil, "", err
+		return
 	}
 
 	if data[0] == iERR {
@@ -194,11 +194,14 @@ func (mc *mysqlConn) readHandshakePacket() ([]byte, string, error) {
 		return nil, "", ErrOldProtocol
 	}
 	if mc.flags&clientSSL == 0 && mc.cfg.tls != nil {
-		return nil, "", ErrNoTLS
+		if mc.cfg.TLSConfig == "preferred" {
+			mc.cfg.tls = nil
+		} else {
+			return nil, "", ErrNoTLS
+		}
 	}
 	pos += 2
 
-	plugin := ""
 	if len(data) > pos {
 		// character set [1 byte]
 		// status flags [2 bytes]
@@ -236,8 +239,6 @@ func (mc *mysqlConn) readHandshakePacket() ([]byte, string, error) {
 		return b[:], plugin, nil
 	}
 
-	plugin = defaultAuthPlugin
-
 	// make a memory safe copy of the cipher slice
 	var b [8]byte
 	copy(b[:], authData)
@@ -246,7 +247,7 @@ func (mc *mysqlConn) readHandshakePacket() ([]byte, string, error) {
 
 // Client Authentication Packet
 // http://dev.mysql.com/doc/internals/en/connection-phase-packets.html#packet-Protocol::HandshakeResponse
-func (mc *mysqlConn) writeHandshakeResponsePacket(authResp []byte, addNUL bool, plugin string) error {
+func (mc *mysqlConn) writeHandshakeResponsePacket(authResp []byte, plugin string) error {
 	// Adjust client flags based on server support
 	clientFlags := clientProtocol41 |
 		clientSecureConn |
@@ -272,7 +273,8 @@ func (mc *mysqlConn) writeHandshakeResponsePacket(authResp []byte, addNUL bool,
 
 	// encode length of the auth plugin data
 	var authRespLEIBuf [9]byte
-	authRespLEI := appendLengthEncodedInteger(authRespLEIBuf[:0], uint64(len(authResp)))
+	authRespLen := len(authResp)
+	authRespLEI := appendLengthEncodedInteger(authRespLEIBuf[:0], uint64(authRespLen))
 	if len(authRespLEI) > 1 {
 		// if the length can not be written in 1 byte, it must be written as a
 		// length encoded integer
@@ -280,9 +282,6 @@ func (mc *mysqlConn) writeHandshakeResponsePacket(authResp []byte, addNUL bool,
 	}
 
 	pktLen := 4 + 4 + 1 + 23 + len(mc.cfg.User) + 1 + len(authRespLEI) + len(authResp) + 21 + 1
-	if addNUL {
-		pktLen++
-	}
 
 	// To specify a db name
 	if n := len(mc.cfg.DBName); n > 0 {
@@ -291,10 +290,10 @@ func (mc *mysqlConn) writeHandshakeResponsePacket(authResp []byte, addNUL bool,
 	}
 
 	// Calculate packet length and get buffer with that size
-	data := mc.buf.takeSmallBuffer(pktLen + 4)
-	if data == nil {
+	data, err := mc.buf.takeSmallBuffer(pktLen + 4)
+	if err != nil {
 		// cannot take the buffer. Something must be wrong with the connection
-		errLog.Print(ErrBusyBuffer)
+		errLog.Print(err)
 		return errBadConnNoWrite
 	}
 
@@ -353,10 +352,6 @@ func (mc *mysqlConn) writeHandshakeResponsePacket(authResp []byte, addNUL bool,
 	// Auth Data [length encoded integer]
 	pos += copy(data[pos:], authRespLEI)
 	pos += copy(data[pos:], authResp)
-	if addNUL {
-		data[pos] = 0x00
-		pos++
-	}
 
 	// Databasename [null terminated string]
 	if len(mc.cfg.DBName) > 0 {
@@ -367,30 +362,24 @@ func (mc *mysqlConn) writeHandshakeResponsePacket(authResp []byte, addNUL bool,
 
 	pos += copy(data[pos:], plugin)
 	data[pos] = 0x00
+	pos++
 
 	// Send Auth packet
-	return mc.writePacket(data)
+	return mc.writePacket(data[:pos])
 }
 
 // http://dev.mysql.com/doc/internals/en/connection-phase-packets.html#packet-Protocol::AuthSwitchResponse
-func (mc *mysqlConn) writeAuthSwitchPacket(authData []byte, addNUL bool) error {
+func (mc *mysqlConn) writeAuthSwitchPacket(authData []byte) error {
 	pktLen := 4 + len(authData)
-	if addNUL {
-		pktLen++
-	}
-	data := mc.buf.takeSmallBuffer(pktLen)
-	if data == nil {
+	data, err := mc.buf.takeSmallBuffer(pktLen)
+	if err != nil {
 		// cannot take the buffer. Something must be wrong with the connection
-		errLog.Print(ErrBusyBuffer)
+		errLog.Print(err)
 		return errBadConnNoWrite
 	}
 
 	// Add the auth data [EOF]
 	copy(data[4:], authData)
-	if addNUL {
-		data[pktLen-1] = 0x00
-	}
-
 	return mc.writePacket(data)
 }
 
@@ -402,10 +391,10 @@ func (mc *mysqlConn) writeCommandPacket(command byte) error {
 	// Reset Packet Sequence
 	mc.sequence = 0
 
-	data := mc.buf.takeSmallBuffer(4 + 1)
-	if data == nil {
+	data, err := mc.buf.takeSmallBuffer(4 + 1)
+	if err != nil {
 		// cannot take the buffer. Something must be wrong with the connection
-		errLog.Print(ErrBusyBuffer)
+		errLog.Print(err)
 		return errBadConnNoWrite
 	}
 
@@ -421,10 +410,10 @@ func (mc *mysqlConn) writeCommandPacketStr(command byte, arg string) error {
 	mc.sequence = 0
 
 	pktLen := 1 + len(arg)
-	data := mc.buf.takeBuffer(pktLen + 4)
-	if data == nil {
+	data, err := mc.buf.takeBuffer(pktLen + 4)
+	if err != nil {
 		// cannot take the buffer. Something must be wrong with the connection
-		errLog.Print(ErrBusyBuffer)
+		errLog.Print(err)
 		return errBadConnNoWrite
 	}
 
@@ -442,10 +431,10 @@ func (mc *mysqlConn) writeCommandPacketUint32(command byte, arg uint32) error {
 	// Reset Packet Sequence
 	mc.sequence = 0
 
-	data := mc.buf.takeSmallBuffer(4 + 1 + 4)
-	if data == nil {
+	data, err := mc.buf.takeSmallBuffer(4 + 1 + 4)
+	if err != nil {
 		// cannot take the buffer. Something must be wrong with the connection
-		errLog.Print(ErrBusyBuffer)
+		errLog.Print(err)
 		return errBadConnNoWrite
 	}
 
@@ -482,7 +471,7 @@ func (mc *mysqlConn) readAuthResult() ([]byte, string, error) {
 		return data[1:], "", err
 
 	case iEOF:
-		if len(data) < 1 {
+		if len(data) == 1 {
 			// https://dev.mysql.com/doc/internals/en/connection-phase-packets.html#packet-Protocol::OldAuthSwitchRequest
 			return nil, "mysql_old_password", nil
 		}
@@ -898,7 +887,7 @@ func (stmt *mysqlStmt) writeExecutePacket(args []driver.Value) error {
 	const minPktLen = 4 + 1 + 4 + 1 + 4
 	mc := stmt.mc
 
-	// Determine threshould dynamically to avoid packet size shortage.
+	// Determine threshold dynamically to avoid packet size shortage.
 	longDataSize := mc.maxAllowedPacket / (stmt.paramCount + 1)
 	if longDataSize < 64 {
 		longDataSize = 64
@@ -908,15 +897,17 @@ func (stmt *mysqlStmt) writeExecutePacket(args []driver.Value) error {
 	mc.sequence = 0
 
 	var data []byte
+	var err error
 
 	if len(args) == 0 {
-		data = mc.buf.takeBuffer(minPktLen)
+		data, err = mc.buf.takeBuffer(minPktLen)
 	} else {
-		data = mc.buf.takeCompleteBuffer()
+		data, err = mc.buf.takeCompleteBuffer()
+		// In this case the len(data) == cap(data) which is used to optimise the flow below.
 	}
-	if data == nil {
+	if err != nil {
 		// cannot take the buffer. Something must be wrong with the connection
-		errLog.Print(ErrBusyBuffer)
+		errLog.Print(err)
 		return errBadConnNoWrite
 	}
 
@@ -942,7 +933,7 @@ func (stmt *mysqlStmt) writeExecutePacket(args []driver.Value) error {
 		pos := minPktLen
 
 		var nullMask []byte
-		if maskLen, typesLen := (len(args)+7)/8, 1+2*len(args); pos+maskLen+typesLen >= len(data) {
+		if maskLen, typesLen := (len(args)+7)/8, 1+2*len(args); pos+maskLen+typesLen >= cap(data) {
 			// buffer has to be extended but we don't know by how much so
 			// we depend on append after all data with known sizes fit.
 			// We stop at that because we deal with a lot of columns here
@@ -951,10 +942,11 @@ func (stmt *mysqlStmt) writeExecutePacket(args []driver.Value) error {
 			copy(tmp[:pos], data[:pos])
 			data = tmp
 			nullMask = data[pos : pos+maskLen]
+			// No need to clean nullMask as make ensures that.
 			pos += maskLen
 		} else {
 			nullMask = data[pos : pos+maskLen]
-			for i := 0; i < maskLen; i++ {
+			for i := range nullMask {
 				nullMask[i] = 0
 			}
 			pos += maskLen
@@ -1091,7 +1083,10 @@ func (stmt *mysqlStmt) writeExecutePacket(args []driver.Value) error {
 		// In that case we must build the data packet with the new values buffer
 		if valuesCap != cap(paramValues) {
 			data = append(data[:pos], paramValues...)
-			mc.buf.buf = data
+			if err = mc.buf.store(data); err != nil {
+				errLog.Print(err)
+				return errBadConnNoWrite
+			}
 		}
 
 		pos += len(paramValues)
@@ -1261,7 +1256,7 @@ func (rows *binaryRows) readRow(dest []driver.Value) error {
 						rows.rs.columns[i].decimals,
 					)
 				}
-				dest[i], err = formatBinaryDateTime(data[pos:pos+int(num)], dstlen, true)
+				dest[i], err = formatBinaryTime(data[pos:pos+int(num)], dstlen)
 			case rows.mc.parseTime:
 				dest[i], err = parseBinaryDateTime(num, data[pos:], rows.mc.cfg.Loc)
 			default:
@@ -1281,7 +1276,7 @@ func (rows *binaryRows) readRow(dest []driver.Value) error {
 						)
 					}
 				}
-				dest[i], err = formatBinaryDateTime(data[pos:pos+int(num)], dstlen, false)
+				dest[i], err = formatBinaryDateTime(data[pos:pos+int(num)], dstlen)
 			}
 
 			if err == nil {
diff --git a/vendor/github.com/go-sql-driver/mysql/utils.go b/vendor/github.com/go-sql-driver/mysql/utils.go
index 84d595b6ba..cb3650bb9b 100644
--- a/vendor/github.com/go-sql-driver/mysql/utils.go
+++ b/vendor/github.com/go-sql-driver/mysql/utils.go
@@ -10,10 +10,13 @@ package mysql
 
 import (
 	"crypto/tls"
+	"database/sql"
 	"database/sql/driver"
 	"encoding/binary"
+	"errors"
 	"fmt"
 	"io"
+	"strconv"
 	"strings"
 	"sync"
 	"sync/atomic"
@@ -79,7 +82,7 @@ func DeregisterTLSConfig(key string) {
 func getTLSConfigClone(key string) (config *tls.Config) {
 	tlsConfigLock.RLock()
 	if v, ok := tlsConfigRegistry[key]; ok {
-		config = cloneTLSConfig(v)
+		config = v.Clone()
 	}
 	tlsConfigLock.RUnlock()
 	return
@@ -227,141 +230,156 @@ var zeroDateTime = []byte("0000-00-00 00:00:00.000000")
 const digits01 = "0123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789"
 const digits10 = "0000000000111111111122222222223333333333444444444455555555556666666666777777777788888888889999999999"
 
-func formatBinaryDateTime(src []byte, length uint8, justTime bool) (driver.Value, error) {
-	// length expects the deterministic length of the zero value,
-	// negative time and 100+ hours are automatically added if needed
-	if len(src) == 0 {
-		if justTime {
-			return zeroDateTime[11 : 11+length], nil
-		}
-		return zeroDateTime[:length], nil
+func appendMicrosecs(dst, src []byte, decimals int) []byte {
+	if decimals <= 0 {
+		return dst
 	}
-	var dst []byte          // return value
-	var pt, p1, p2, p3 byte // current digit pair
-	var zOffs byte          // offset of value in zeroDateTime
-	if justTime {
-		switch length {
-		case
-			8,                      // time (can be up to 10 when negative and 100+ hours)
-			10, 11, 12, 13, 14, 15: // time with fractional seconds
-		default:
-			return nil, fmt.Errorf("illegal TIME length %d", length)
-		}
-		switch len(src) {
-		case 8, 12:
-		default:
-			return nil, fmt.Errorf("invalid TIME packet length %d", len(src))
-		}
-		// +2 to enable negative time and 100+ hours
-		dst = make([]byte, 0, length+2)
-		if src[0] == 1 {
-			dst = append(dst, '-')
-		}
-		if src[1] != 0 {
-			hour := uint16(src[1])*24 + uint16(src[5])
-			pt = byte(hour / 100)
-			p1 = byte(hour - 100*uint16(pt))
-			dst = append(dst, digits01[pt])
-		} else {
-			p1 = src[5]
-		}
-		zOffs = 11
-		src = src[6:]
-	} else {
-		switch length {
-		case 10, 19, 21, 22, 23, 24, 25, 26:
-		default:
-			t := "DATE"
-			if length > 10 {
-				t += "TIME"
-			}
-			return nil, fmt.Errorf("illegal %s length %d", t, length)
-		}
-		switch len(src) {
-		case 4, 7, 11:
-		default:
-			t := "DATE"
-			if length > 10 {
-				t += "TIME"
-			}
-			return nil, fmt.Errorf("illegal %s packet length %d", t, len(src))
-		}
-		dst = make([]byte, 0, length)
-		// start with the date
-		year := binary.LittleEndian.Uint16(src[:2])
-		pt = byte(year / 100)
-		p1 = byte(year - 100*uint16(pt))
-		p2, p3 = src[2], src[3]
-		dst = append(dst,
-			digits10[pt], digits01[pt],
-			digits10[p1], digits01[p1], '-',
-			digits10[p2], digits01[p2], '-',
-			digits10[p3], digits01[p3],
-		)
-		if length == 10 {
-			return dst, nil
-		}
-		if len(src) == 4 {
-			return append(dst, zeroDateTime[10:length]...), nil
-		}
-		dst = append(dst, ' ')
-		p1 = src[4] // hour
-		src = src[5:]
-	}
-	// p1 is 2-digit hour, src is after hour
-	p2, p3 = src[0], src[1]
-	dst = append(dst,
-		digits10[p1], digits01[p1], ':',
-		digits10[p2], digits01[p2], ':',
-		digits10[p3], digits01[p3],
-	)
-	if length <= byte(len(dst)) {
-		return dst, nil
-	}
-	src = src[2:]
 	if len(src) == 0 {
-		return append(dst, zeroDateTime[19:zOffs+length]...), nil
+		return append(dst, ".000000"[:decimals+1]...)
 	}
+
 	microsecs := binary.LittleEndian.Uint32(src[:4])
-	p1 = byte(microsecs / 10000)
+	p1 := byte(microsecs / 10000)
 	microsecs -= 10000 * uint32(p1)
-	p2 = byte(microsecs / 100)
+	p2 := byte(microsecs / 100)
 	microsecs -= 100 * uint32(p2)
-	p3 = byte(microsecs)
-	switch decimals := zOffs + length - 20; decimals {
+	p3 := byte(microsecs)
+
+	switch decimals {
 	default:
 		return append(dst, '.',
 			digits10[p1], digits01[p1],
 			digits10[p2], digits01[p2],
 			digits10[p3], digits01[p3],
-		), nil
+		)
 	case 1:
 		return append(dst, '.',
 			digits10[p1],
-		), nil
+		)
 	case 2:
 		return append(dst, '.',
 			digits10[p1], digits01[p1],
-		), nil
+		)
 	case 3:
 		return append(dst, '.',
 			digits10[p1], digits01[p1],
 			digits10[p2],
-		), nil
+		)
 	case 4:
 		return append(dst, '.',
 			digits10[p1], digits01[p1],
 			digits10[p2], digits01[p2],
-		), nil
+		)
 	case 5:
 		return append(dst, '.',
 			digits10[p1], digits01[p1],
 			digits10[p2], digits01[p2],
 			digits10[p3],
-		), nil
+		)
 	}
 }
 
+func formatBinaryDateTime(src []byte, length uint8) (driver.Value, error) {
+	// length expects the deterministic length of the zero value,
+	// negative time and 100+ hours are automatically added if needed
+	if len(src) == 0 {
+		return zeroDateTime[:length], nil
+	}
+	var dst []byte      // return value
+	var p1, p2, p3 byte // current digit pair
+
+	switch length {
+	case 10, 19, 21, 22, 23, 24, 25, 26:
+	default:
+		t := "DATE"
+		if length > 10 {
+			t += "TIME"
+		}
+		return nil, fmt.Errorf("illegal %s length %d", t, length)
+	}
+	switch len(src) {
+	case 4, 7, 11:
+	default:
+		t := "DATE"
+		if length > 10 {
+			t += "TIME"
+		}
+		return nil, fmt.Errorf("illegal %s packet length %d", t, len(src))
+	}
+	dst = make([]byte, 0, length)
+	// start with the date
+	year := binary.LittleEndian.Uint16(src[:2])
+	pt := year / 100
+	p1 = byte(year - 100*uint16(pt))
+	p2, p3 = src[2], src[3]
+	dst = append(dst,
+		digits10[pt], digits01[pt],
+		digits10[p1], digits01[p1], '-',
+		digits10[p2], digits01[p2], '-',
+		digits10[p3], digits01[p3],
+	)
+	if length == 10 {
+		return dst, nil
+	}
+	if len(src) == 4 {
+		return append(dst, zeroDateTime[10:length]...), nil
+	}
+	dst = append(dst, ' ')
+	p1 = src[4] // hour
+	src = src[5:]
+
+	// p1 is 2-digit hour, src is after hour
+	p2, p3 = src[0], src[1]
+	dst = append(dst,
+		digits10[p1], digits01[p1], ':',
+		digits10[p2], digits01[p2], ':',
+		digits10[p3], digits01[p3],
+	)
+	return appendMicrosecs(dst, src[2:], int(length)-20), nil
+}
+
+func formatBinaryTime(src []byte, length uint8) (driver.Value, error) {
+	// length expects the deterministic length of the zero value,
+	// negative time and 100+ hours are automatically added if needed
+	if len(src) == 0 {
+		return zeroDateTime[11 : 11+length], nil
+	}
+	var dst []byte // return value
+
+	switch length {
+	case
+		8,                      // time (can be up to 10 when negative and 100+ hours)
+		10, 11, 12, 13, 14, 15: // time with fractional seconds
+	default:
+		return nil, fmt.Errorf("illegal TIME length %d", length)
+	}
+	switch len(src) {
+	case 8, 12:
+	default:
+		return nil, fmt.Errorf("invalid TIME packet length %d", len(src))
+	}
+	// +2 to enable negative time and 100+ hours
+	dst = make([]byte, 0, length+2)
+	if src[0] == 1 {
+		dst = append(dst, '-')
+	}
+	days := binary.LittleEndian.Uint32(src[1:5])
+	hours := int64(days)*24 + int64(src[5])
+
+	if hours >= 100 {
+		dst = strconv.AppendInt(dst, hours, 10)
+	} else {
+		dst = append(dst, digits10[hours], digits01[hours])
+	}
+
+	min, sec := src[6], src[7]
+	dst = append(dst, ':',
+		digits10[min], digits01[min], ':',
+		digits10[sec], digits01[sec],
+	)
+	return appendMicrosecs(dst, src[8:], int(length)-9), nil
+}
+
 /******************************************************************************
 *                       Convert from and to bytes                             *
 ******************************************************************************/
@@ -708,3 +726,30 @@ func (ae *atomicError) Value() error {
 	}
 	return nil
 }
+
+func namedValueToValue(named []driver.NamedValue) ([]driver.Value, error) {
+	dargs := make([]driver.Value, len(named))
+	for n, param := range named {
+		if len(param.Name) > 0 {
+			// TODO: support the use of Named Parameters #561
+			return nil, errors.New("mysql: driver does not support the use of Named Parameters")
+		}
+		dargs[n] = param.Value
+	}
+	return dargs, nil
+}
+
+func mapIsolationLevel(level driver.IsolationLevel) (string, error) {
+	switch sql.IsolationLevel(level) {
+	case sql.LevelRepeatableRead:
+		return "REPEATABLE READ", nil
+	case sql.LevelReadCommitted:
+		return "READ COMMITTED", nil
+	case sql.LevelReadUncommitted:
+		return "READ UNCOMMITTED", nil
+	case sql.LevelSerializable:
+		return "SERIALIZABLE", nil
+	default:
+		return "", fmt.Errorf("mysql: unsupported isolation level: %v", level)
+	}
+}
diff --git a/vendor/github.com/go-sql-driver/mysql/utils_go17.go b/vendor/github.com/go-sql-driver/mysql/utils_go17.go
deleted file mode 100644
index f595634567..0000000000
--- a/vendor/github.com/go-sql-driver/mysql/utils_go17.go
+++ /dev/null
@@ -1,40 +0,0 @@
-// Go MySQL Driver - A MySQL-Driver for Go's database/sql package
-//
-// Copyright 2017 The Go-MySQL-Driver Authors. All rights reserved.
-//
-// This Source Code Form is subject to the terms of the Mozilla Public
-// License, v. 2.0. If a copy of the MPL was not distributed with this file,
-// You can obtain one at http://mozilla.org/MPL/2.0/.
-
-// +build go1.7
-// +build !go1.8
-
-package mysql
-
-import "crypto/tls"
-
-func cloneTLSConfig(c *tls.Config) *tls.Config {
-	return &tls.Config{
-		Rand:                        c.Rand,
-		Time:                        c.Time,
-		Certificates:                c.Certificates,
-		NameToCertificate:           c.NameToCertificate,
-		GetCertificate:              c.GetCertificate,
-		RootCAs:                     c.RootCAs,
-		NextProtos:                  c.NextProtos,
-		ServerName:                  c.ServerName,
-		ClientAuth:                  c.ClientAuth,
-		ClientCAs:                   c.ClientCAs,
-		InsecureSkipVerify:          c.InsecureSkipVerify,
-		CipherSuites:                c.CipherSuites,
-		PreferServerCipherSuites:    c.PreferServerCipherSuites,
-		SessionTicketsDisabled:      c.SessionTicketsDisabled,
-		SessionTicketKey:            c.SessionTicketKey,
-		ClientSessionCache:          c.ClientSessionCache,
-		MinVersion:                  c.MinVersion,
-		MaxVersion:                  c.MaxVersion,
-		CurvePreferences:            c.CurvePreferences,
-		DynamicRecordSizingDisabled: c.DynamicRecordSizingDisabled,
-		Renegotiation:               c.Renegotiation,
-	}
-}
diff --git a/vendor/github.com/go-sql-driver/mysql/utils_go18.go b/vendor/github.com/go-sql-driver/mysql/utils_go18.go
deleted file mode 100644
index c35c2a6aab..0000000000
--- a/vendor/github.com/go-sql-driver/mysql/utils_go18.go
+++ /dev/null
@@ -1,50 +0,0 @@
-// Go MySQL Driver - A MySQL-Driver for Go's database/sql package
-//
-// Copyright 2017 The Go-MySQL-Driver Authors. All rights reserved.
-//
-// This Source Code Form is subject to the terms of the Mozilla Public
-// License, v. 2.0. If a copy of the MPL was not distributed with this file,
-// You can obtain one at http://mozilla.org/MPL/2.0/.
-
-// +build go1.8
-
-package mysql
-
-import (
-	"crypto/tls"
-	"database/sql"
-	"database/sql/driver"
-	"errors"
-	"fmt"
-)
-
-func cloneTLSConfig(c *tls.Config) *tls.Config {
-	return c.Clone()
-}
-
-func namedValueToValue(named []driver.NamedValue) ([]driver.Value, error) {
-	dargs := make([]driver.Value, len(named))
-	for n, param := range named {
-		if len(param.Name) > 0 {
-			// TODO: support the use of Named Parameters #561
-			return nil, errors.New("mysql: driver does not support the use of Named Parameters")
-		}
-		dargs[n] = param.Value
-	}
-	return dargs, nil
-}
-
-func mapIsolationLevel(level driver.IsolationLevel) (string, error) {
-	switch sql.IsolationLevel(level) {
-	case sql.LevelRepeatableRead:
-		return "REPEATABLE READ", nil
-	case sql.LevelReadCommitted:
-		return "READ COMMITTED", nil
-	case sql.LevelReadUncommitted:
-		return "READ UNCOMMITTED", nil
-	case sql.LevelSerializable:
-		return "SERIALIZABLE", nil
-	default:
-		return "", fmt.Errorf("mysql: unsupported isolation level: %v", level)
-	}
-}