auth_old_password.go

// Go MySQL Driver - A MySQL-Driver for Go's database/sql package
//
// Copyright 2023 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"

// oldPasswordPlugin implements the mysql_old_password authentication
type oldPasswordPlugin struct{ simpleAuth }

func init() {
	RegisterAuthPlugin("mysql_old_password", func() AuthPlugin { return &oldPasswordPlugin{} })
}

func (p *oldPasswordPlugin) InitAuth(ctx context.Context, authData []byte, auth *AuthContext) ([]byte, error) {
	if auth.Password() == "" {
		return nil, nil
	}
	if len(authData) < 8 {
		return nil, ErrMalformPkt
	}
	// 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
	return append(p.scrambleOldPassword(authData[:8], auth.Password()), 0), nil
}

// Hash password using insecure pre 4.1 method
func (p *oldPasswordPlugin) scrambleOldPassword(scramble []byte, password string) []byte {
	scramble = scramble[:8]

	hashPw := pwHash([]byte(password))
	hashSc := pwHash(scramble)

	r := newMyRnd(hashPw[0]^hashSc[0], hashPw[1]^hashSc[1])

	var out [8]byte
	for i := range out {
		out[i] = r.NextByte() + 64
	}

	mask := r.NextByte()
	for i := range out {
		out[i] ^= mask
	}

	return out[:]
}

// Hash password using pre 4.1 (old password) method
// https://github.com/atcurtis/mariadb/blob/master/mysys/my_rnd.c
type myRnd struct {
	seed1, seed2 uint32
}

// Tested to be equivalent to MariaDB's floating point variant
// http://play.golang.org/p/QHvhd4qved
// http://play.golang.org/p/RG0q4ElWDx
func (r *myRnd) NextByte() byte {
	r.seed1 = (r.seed1*3 + r.seed2) % myRndMaxVal
	r.seed2 = (r.seed1 + r.seed2 + 33) % myRndMaxVal

	return byte(uint64(r.seed1) * 31 / myRndMaxVal)
}

const myRndMaxVal = 0x3FFFFFFF

// Pseudo random number generator
func newMyRnd(seed1, seed2 uint32) *myRnd {
	return &myRnd{
		seed1: seed1 % myRndMaxVal,
		seed2: seed2 % myRndMaxVal,
	}
}

// Generate binary hash from byte string using insecure pre 4.1 method
func pwHash(password []byte) (result [2]uint32) {
	var add uint32 = 7
	var tmp uint32

	result[0] = 1345345333
	result[1] = 0x12345671

	for _, c := range password {
		// skip spaces and tabs in password
		if c == ' ' || c == '\t' {
			continue
		}

		tmp = uint32(c)
		result[0] ^= (((result[0] & 63) + add) * tmp) + (result[0] << 8)
		result[1] += (result[1] << 8) ^ result[0]
		add += tmp
	}

	// Remove sign bit (1<<31)-1)
	result[0] &= 0x7FFFFFFF
	result[1] &= 0x7FFFFFFF

	return
}