allowOldPasswords broken

[florck]

Issue description

When I activate the allowOldPasswords=1, I get a panic.

Example code

data := []myData{}
	connString := config.Config.Database.DbUser+":"+config.Config.Database.DbPassword+"@tcp("+config.Config.Database.DbAdresse+")/db?allowOldPasswords=1"
    logp.Info("I will connect to:")
	logp.Info(connString)
	db,errcon := sqlx.Connect("mysql", connString)
    logp.Info("MySQL connection opened.")
	if errcon != nil {
		logp.Info("probleme sql.Open")
        logp.Info(errcon.Error())
		log.Fatal(errcon)
	}
	defer db.Close()

As per you know, it fails before saying "MySQL connection opened."

Error log

panic: runtime error: slice bounds out of range

goroutine 1 [running]:
panic(0x8e2440, 0xc420012180)
        /usr/lib/go/src/runtime/panic.go:500 +0x1a1
github.com/go-sql-driver/mysql.scrambleOldPassword(0x0, 0x0, 0x0, 0xc420199340, 0x8, 0x20, 0xc4201993d8, 0x54539b, 0x401dbe)
        /home/tutu/go/src/github.com/go-sql-driver/mysql/utils.go:176 +0x2bd
github.com/go-sql-driver/mysql.(*mysqlConn).writeOldAuthPacket(0xc420108360, 0x0, 0x0, 0x0, 0xbd8101, 0xc4200e2fb0)
        /home/tutu/go/src/github.com/go-sql-driver/mysql/packets.go:344 +0xa4
github.com/go-sql-driver/mysql.handleAuthResult(0xc420108360, 0xc4201b8720, 0x14)
        /home/tutu/go/src/github.com/go-sql-driver/mysql/driver.go:153 +0x2bf
github.com/go-sql-driver/mysql.MySQLDriver.Open(0xc4200ded70, 0x43, 0x0, 0x28, 0x28, 0x9bd283)
        /home/tutu/go/src/github.com/go-sql-driver/mysql/driver.go:104 +0x44e
github.com/go-sql-driver/mysql.(*MySQLDriver).Open(0xc234a8, 0xc4200ded70, 0x43, 0xc420199698, 0x41002e, 0xc4201c86c0, 0x30)
        <autogenerated>:6 +0x60
database/sql.(*DB).conn(0xc420147b80, 0x1, 0xc420147b80, 0xc4201c86c0, 0xc4201c8690)
        /usr/lib/go/src/database/sql/sql.go:824 +0x24e
database/sql.(*DB).Ping(0xc420147b80, 0x5, 0xc4200ded70)
        /usr/lib/go/src/database/sql/sql.go:503 +0x34
github.com/jmoiron/sqlx.Connect(0x9766fb, 0x5, 0xc4200ded70, 0x43, 0x0, 0x43, 0x1c)
        /home/tutu/go/src/github.com/jmoiron/sqlx/sqlx.go:603 +0x72
_/home/tutu/Documents/Travail/TW/ElasticStack/tatabeat/tatabeat/beater.(*tatabeat).getData(0xc4200e9b40, 0xc4201182c0, 0xc4201b8580, 0x17, 0xc420185ae8, 0x6, 0xc420185af0, 0xe, 0xc420185b60, 0x10, ...)
        /home/tutu/Documents/Travail/TW/ElasticStack/tatabeat/tatabeat/beater/tatabeat.go:229 +0x22a
_/home/tutu/Documents/Travail/TW/ElasticStack/tatabeat/tatabeat/beater.(*tatabeat).Run(0xc4200e9b40, 0xc4201182c0, 0xc420118368, 0xb)
        /home/tutu/Documents/Travail/TW/ElasticStack/tatabeat/tatabeat/beater/tatabeat.go:159 +0x31e
github.com/elastic/beats/libbeat/beat.(*Beat).launch(0xc4201182c0, 0x9bf2f0, 0x0, 0x0)
        /home/tutu/go/src/github.com/elastic/beats/libbeat/beat/beat.go:211 +0x699
github.com/elastic/beats/libbeat/beat.Run(0x97a445, 0x9, 0x0, 0x0, 0x9bf2f0, 0x55326e, 0xc4200001a0)
        /home/tutu/go/src/github.com/elastic/beats/libbeat/beat/beat.go:136 +0x65
main.main()

Configuration

Driver version (or git SHA):
commit 665b834

Go version: run go version in your console
go version go1.7.3 linux/amd64

Server version: E.g. MySQL 5.6, MariaDB 10.0.20
mysql Ver 14.12 Distrib 5.0.95, for redhat-linux-gnu (x86_64) using readline 5.1

Server OS: E.g. Debian 8.1 (Jessie), Windows 10
CentOS release 5.9 (Final)

[florck]

This is the last commit 665b834 that introduced this regression.
With HEAD est maintenant sur 8f6c67f... rows: Invalidate connection on error in discardResults() (#513)
It works fine.

[julienschmidt]

It took me ages to set up a debug environment where I was able to reproduce the panic, but finally a docker container with the same MySQL version did the trick.

It seems like ce924a4 / #494 broke it, not 665b834.

See #524 for a proposed fix.