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mssql.go
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mssql.go
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package dbms
import (
"crypto/tls"
"errors"
"fmt"
"io"
"net"
"sync"
"time"
"github.com/nim4/DBShield/dbshield/logger"
"github.com/nim4/DBShield/dbshield/sql"
)
const maxMSSQLPayloadLen = 4096
const (
mssqlEncryptionAvailableAndOff = iota
mssqlEncryptionAvailableAndOn
mssqlEncryptionNotAvailable
mssqlEncryptionRequired
)
//MSSQL DBMS
type MSSQL struct {
client net.Conn
server net.Conn
certificate tls.Certificate
currentDB []byte
username []byte
reader func(io.Reader) ([]byte, error)
}
//SetCertificate to use if client asks for SSL
func (m *MSSQL) SetCertificate(crt, key string) (err error) {
m.certificate, err = tls.LoadX509KeyPair(crt, key)
return
}
//SetReader function for sockets IO
func (m *MSSQL) SetReader(f func(io.Reader) ([]byte, error)) {
m.reader = f
}
//SetSockets for dbms (client and server sockets)
func (m *MSSQL) SetSockets(c, s net.Conn) {
m.client = c
m.server = s
}
//Close sockets
func (m *MSSQL) Close() {
defer handlePanic()
m.client.Close()
m.server.Close()
}
//DefaultPort of the DBMS
func (m *MSSQL) DefaultPort() uint {
return 1433
}
//Handler gets incoming requests
func (m *MSSQL) Handler() error {
defer handlePanic()
defer m.Close()
success, err := m.handleLogin()
if err != nil {
return err
}
if !success {
logger.Warning("Login failed")
return nil
}
for {
var buf []byte
buf, err = m.reader(m.client)
if err != nil || len(buf) < 8 {
return err
}
switch buf[0] {
case 0x01: //SQL batch
query := buf[8:]
context := sql.QueryContext{
Query: query,
Database: m.currentDB,
User: m.username,
Client: remoteAddrToIP(m.client.RemoteAddr()),
Time: time.Now(),
}
processContext(context)
}
//Send query/request to server
_, err = m.server.Write(buf)
if err != nil {
return err
}
//Recive response
err = readWrite(m.server, m.client, m.reader)
if err != nil {
return err
}
}
}
func (m *MSSQL) handleLogin() (success bool, err error) {
//Receive PreLogin Request
buf, err := m.reader(m.client)
if err != nil {
return
}
if buf[0] != 0x12 {
err = errors.New("packet is not PRELOGIN")
return
}
//Send PreLogin to server
_, err = m.server.Write(buf)
if err != nil {
return
}
//Receive PRELOGIN response
buf, err = m.reader(m.server)
if err != nil {
return
}
if buf[0] != 0x4 {
err = errors.New("packet is not PRELOGIN response")
return
}
//Send PreLogin to server
_, err = m.client.Write(buf)
if err != nil {
return
}
//Set data to beginning of the prelogin message
data := buf[8:]
var encryption byte
//Lookup Encryption
for i := 0; i < len(data); i += 5 {
switch data[i] {
case 0x01: //Encryption
encryption = data[int(data[i+1])]
break
case 0xff: //Terminator
break
}
}
logger.Debugf("Encryption: %v", encryption)
// buf, err = m.reader(m.client)
// if err != nil {
// return
// }
//
//m.username, m.currentDB = MSSQLGetUsernameDB(buf)
for {
//Receive PreLogin Request
err = readWrite(m.client, m.server, m.reader)
if err != nil {
return
}
//Receive PRELOGIN response
buf, err = m.reader(m.server)
if err != nil {
return
}
//Send PreLogin to server
_, err = m.client.Write(buf)
if err != nil {
return
}
if buf[0] == 0x4 {
break
}
}
success = true
return
}
//buffer pool for MSSQLReadPacket
var mssqlDataPool = sync.Pool{
New: func() interface{} {
return make([]byte, maxMSSQLPayloadLen)
},
}
//MSSQLReadPacket handles reading mysql packets
func MSSQLReadPacket(src io.Reader) ([]byte, error) {
data := mssqlDataPool.Get().([]byte)
defer mssqlDataPool.Put(data)
n, err := src.Read(data)
if err != nil && err != io.EOF {
return nil, err
}
if n < maxMSSQLPayloadLen || err == io.EOF {
return data[:n], nil
}
buf, err := MSSQLReadPacket(src)
if err != nil {
return nil, err
}
return append(data, buf...), nil
}
//MSSQLGetUsernameDB parse packet and gets username and db name
func MSSQLGetUsernameDB(data []byte) (username, db []byte) {
//TODO: Extract Username and db name
fmt.Printf("%x", data)
return
}