niki/vendor/github.com/go-sql-driver/mysql/connector.go

// Go MySQL Driver - A MySQL-Driver for Go's database/sql package

//

// Copyright 2018 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/.

package mysql

import (
	"context"
	"database/sql/driver"
	"net"
)

type connector struct {
	cfg *Config // immutable private copy.

}

// Connect implements driver.Connector interface.

// Connect returns a connection to the database.

func (c *connector) Connect(ctx context.Context) (driver.Conn, error) {

	var err error

	// New mysqlConn

	mc := &mysqlConn{

		maxAllowedPacket: maxPacketSize,

		maxWriteSize: maxPacketSize - 1,

		closech: make(chan struct{}),

		cfg: c.cfg,
	}

	mc.parseTime = mc.cfg.ParseTime

	// Connect to Server

	dialsLock.RLock()

	dial, ok := dials[mc.cfg.Net]

	dialsLock.RUnlock()

	if ok {

		dctx := ctx

		if mc.cfg.Timeout > 0 {

			var cancel context.CancelFunc

			dctx, cancel = context.WithTimeout(ctx, c.cfg.Timeout)

			defer cancel()

		}

		mc.netConn, err = dial(dctx, mc.cfg.Addr)

	} else {

		nd := net.Dialer{Timeout: mc.cfg.Timeout}

		mc.netConn, err = nd.DialContext(ctx, mc.cfg.Net, mc.cfg.Addr)

	}

	if err != nil {

		return nil, err

	}

	// Enable TCP Keepalives on TCP connections

	if tc, ok := mc.netConn.(*net.TCPConn); ok {

		if err := tc.SetKeepAlive(true); err != nil {

			// Don't send COM_QUIT before handshake.

			mc.netConn.Close()

			mc.netConn = nil

			return nil, err

		}

	}

	// Call startWatcher for context support (From Go 1.8)

	mc.startWatcher()

	if err := mc.watchCancel(ctx); err != nil {

		mc.cleanup()

		return nil, err

	}

	defer mc.finish()

	mc.buf = newBuffer(mc.netConn)

	// Set I/O timeouts

	mc.buf.timeout = mc.cfg.ReadTimeout

	mc.writeTimeout = mc.cfg.WriteTimeout

	// Reading Handshake Initialization Packet

	authData, plugin, err := mc.readHandshakePacket()

	if err != nil {

		mc.cleanup()

		return nil, err

	}

	if plugin == "" {

		plugin = defaultAuthPlugin

	}

	// Send Client Authentication Packet

	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, err = mc.auth(authData, plugin)

		if err != nil {

			mc.cleanup()

			return nil, err

		}

	}

	if err = mc.writeHandshakeResponsePacket(authResp, plugin); err != nil {

		mc.cleanup()

		return nil, err

	}

	// Handle response to auth packet, switch methods if possible

	if err = mc.handleAuthResult(authData, plugin); err != nil {

		// Authentication failed and MySQL has already closed the connection

		// (https://dev.mysql.com/doc/internals/en/authentication-fails.html).

		// Do not send COM_QUIT, just cleanup and return the error.

		mc.cleanup()

		return nil, err

	}

	if mc.cfg.MaxAllowedPacket > 0 {

		mc.maxAllowedPacket = mc.cfg.MaxAllowedPacket

	} else {

		// Get max allowed packet size

		maxap, err := mc.getSystemVar("max_allowed_packet")

		if err != nil {

			mc.Close()

			return nil, err

		}

		mc.maxAllowedPacket = stringToInt(maxap) - 1

	}

	if mc.maxAllowedPacket < maxPacketSize {

		mc.maxWriteSize = mc.maxAllowedPacket

	}

	// Handle DSN Params

	err = mc.handleParams()

	if err != nil {

		mc.Close()

		return nil, err

	}

	return mc, nil

}

// Driver implements driver.Connector interface.

// Driver returns &MySQLDriver{}.

func (c *connector) Driver() driver.Driver {

	return &MySQLDriver{}

}