1// Copyright 2012 The Go-MySQL-Driver Authors. All rights reserved.
2//
3// This Source Code Form is subject to the terms of the Mozilla Public
4// License, v. 2.0. If a copy of the MPL was not distributed with this file,
5// You can obtain one at http://mozilla.org/MPL/2.0/.
6
7// Package mysql provides a MySQL driver for Go's database/sql package.
8//
9// The driver should be used via the database/sql package:
10//
11//  import "database/sql"
12//  import _ "github.com/go-sql-driver/mysql"
13//
14//  db, err := sql.Open("mysql", "user:password@/dbname")
15//
16// See https://github.com/go-sql-driver/mysql#usage for details
17package mysql
18
19import (
20	"database/sql"
21	"database/sql/driver"
22	"net"
23	"sync"
24)
25
26// MySQLDriver is exported to make the driver directly accessible.
27// In general the driver is used via the database/sql package.
28type MySQLDriver struct{}
29
30// DialFunc is a function which can be used to establish the network connection.
31// Custom dial functions must be registered with RegisterDial
32type DialFunc func(addr string) (net.Conn, error)
33
34var (
35	dialsLock sync.RWMutex
36	dials     map[string]DialFunc
37)
38
39// RegisterDial registers a custom dial function. It can then be used by the
40// network address mynet(addr), where mynet is the registered new network.
41// addr is passed as a parameter to the dial function.
42func RegisterDial(net string, dial DialFunc) {
43	dialsLock.Lock()
44	defer dialsLock.Unlock()
45	if dials == nil {
46		dials = make(map[string]DialFunc)
47	}
48	dials[net] = dial
49}
50
51// Open new Connection.
52// See https://github.com/go-sql-driver/mysql#dsn-data-source-name for how
53// the DSN string is formated
54func (d MySQLDriver) Open(dsn string) (driver.Conn, error) {
55	var err error
56
57	// New mysqlConn
58	mc := &mysqlConn{
59		maxAllowedPacket: maxPacketSize,
60		maxWriteSize:     maxPacketSize - 1,
61		closech:          make(chan struct{}),
62	}
63	mc.cfg, err = ParseDSN(dsn)
64	if err != nil {
65		return nil, err
66	}
67	mc.parseTime = mc.cfg.ParseTime
68
69	// Connect to Server
70	dialsLock.RLock()
71	dial, ok := dials[mc.cfg.Net]
72	dialsLock.RUnlock()
73	if ok {
74		mc.netConn, err = dial(mc.cfg.Addr)
75	} else {
76		nd := net.Dialer{Timeout: mc.cfg.Timeout}
77		mc.netConn, err = nd.Dial(mc.cfg.Net, mc.cfg.Addr)
78	}
79	if err != nil {
80		return nil, err
81	}
82
83	// Enable TCP Keepalives on TCP connections
84	if tc, ok := mc.netConn.(*net.TCPConn); ok {
85		if err := tc.SetKeepAlive(true); err != nil {
86			// Don't send COM_QUIT before handshake.
87			mc.netConn.Close()
88			mc.netConn = nil
89			return nil, err
90		}
91	}
92
93	// Call startWatcher for context support (From Go 1.8)
94	mc.startWatcher()
95
96	mc.buf = newBuffer(mc.netConn)
97
98	// Set I/O timeouts
99	mc.buf.timeout = mc.cfg.ReadTimeout
100	mc.writeTimeout = mc.cfg.WriteTimeout
101
102	// Reading Handshake Initialization Packet
103	authData, plugin, err := mc.readHandshakePacket()
104	if err != nil {
105		mc.cleanup()
106		return nil, err
107	}
108	if plugin == "" {
109		plugin = defaultAuthPlugin
110	}
111
112	// Send Client Authentication Packet
113	authResp, addNUL, err := mc.auth(authData, plugin)
114	if err != nil {
115		// try the default auth plugin, if using the requested plugin failed
116		errLog.Print("could not use requested auth plugin '"+plugin+"': ", err.Error())
117		plugin = defaultAuthPlugin
118		authResp, addNUL, err = mc.auth(authData, plugin)
119		if err != nil {
120			mc.cleanup()
121			return nil, err
122		}
123	}
124	if err = mc.writeHandshakeResponsePacket(authResp, addNUL, plugin); err != nil {
125		mc.cleanup()
126		return nil, err
127	}
128
129	// Handle response to auth packet, switch methods if possible
130	if err = mc.handleAuthResult(authData, plugin); err != nil {
131		// Authentication failed and MySQL has already closed the connection
132		// (https://dev.mysql.com/doc/internals/en/authentication-fails.html).
133		// Do not send COM_QUIT, just cleanup and return the error.
134		mc.cleanup()
135		return nil, err
136	}
137
138	if mc.cfg.MaxAllowedPacket > 0 {
139		mc.maxAllowedPacket = mc.cfg.MaxAllowedPacket
140	} else {
141		// Get max allowed packet size
142		maxap, err := mc.getSystemVar("max_allowed_packet")
143		if err != nil {
144			mc.Close()
145			return nil, err
146		}
147		mc.maxAllowedPacket = stringToInt(maxap) - 1
148	}
149	if mc.maxAllowedPacket < maxPacketSize {
150		mc.maxWriteSize = mc.maxAllowedPacket
151	}
152
153	// Handle DSN Params
154	err = mc.handleParams()
155	if err != nil {
156		mc.Close()
157		return nil, err
158	}
159
160	return mc, nil
161}
162
163func init() {
164	sql.Register("mysql", &MySQLDriver{})
165}
166