/
db2.go
182 lines (161 loc) · 3.34 KB
/
db2.go
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package dbms
import (
"bytes"
"crypto/tls"
"io"
"net"
"time"
"github.com/nim4/DBShield/dbshield/logger"
"github.com/nim4/DBShield/dbshield/sql"
)
//DB2 DBMS
type DB2 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 (d *DB2) SetCertificate(crt, key string) (err error) {
d.certificate, err = tls.LoadX509KeyPair(crt, key)
return
}
//SetReader function for sockets IO
func (d *DB2) SetReader(f func(io.Reader) ([]byte, error)) {
d.reader = f
}
//SetSockets for dbms (client and server sockets)
func (d *DB2) SetSockets(c, s net.Conn) {
defer handlePanic()
d.client = c
d.server = s
}
//Close sockets
func (d *DB2) Close() {
defer handlePanic()
d.client.Close()
d.server.Close()
}
//DefaultPort of the DBMS
func (d *DB2) DefaultPort() uint {
return 50000
}
//Handler gets incoming requests
func (d *DB2) Handler() (err error) {
defer handlePanic()
defer d.Close()
success, err := d.handleLogin()
if err != nil {
return
}
if !success {
logger.Warning("Login failed")
return
}
end := false
for {
var buf []byte
//Read client request
buf, err = d.reader(d.client)
if err != nil {
return
}
for len(buf) > 0 {
dr, n := parseDRDA(buf)
buf = buf[n:]
if dr.ddm[0] == 0xc0 && dr.ddm[1] == 0x04 {
//ENDUOWRM (end)
end = true
} else if dr.ddm[0] == 0x24 && dr.ddm[1] == 0x14 {
context := sql.QueryContext{
Query: dr.param,
Database: d.currentDB,
User: d.username,
Client: remoteAddrToIP(d.client.RemoteAddr()),
Time: time.Now(),
}
processContext(context)
}
}
//Send request to server
_, err = d.server.Write(buf)
if err != nil {
return
}
if end {
return
}
err = readWrite(d.server, d.client, d.reader)
if err != nil {
return
}
}
}
func (d *DB2) handleLogin() (success bool, err error) {
//Receive EXCSAT | ACCSEC
err = readWrite(d.client, d.server, d.reader)
if err != nil {
return
}
//Receive EXCSATRD | ACCSECRD
err = readWrite(d.server, d.client, d.reader)
if err != nil {
return
}
//Receive Auth
buf, err := d.reader(d.client)
if err != nil {
return
}
//Send result
_, err = d.server.Write(buf)
if err != nil {
return
}
//Get database name
startIndex := bytes.Index(buf, []byte{0x21, 0x10})
buf = buf[startIndex+2:]
atByteIndex := bytes.IndexByte(buf, 0x40) // 0x40 = @
d.currentDB = ebc2asc(buf[:atByteIndex])
//Get username
startIndex = bytes.Index(buf, []byte{0x11, 0xa0})
buf = buf[startIndex+2:]
nullByteIndex := bytes.IndexByte(buf, 0x00)
d.username = ebc2asc(buf[:nullByteIndex])
//Receive result
buf, err = d.reader(d.server)
if err != nil {
return
}
//Send result
_, err = d.client.Write(buf)
if err != nil {
return
}
for {
dr, n := parseDRDA(buf)
success = len(dr.ddm) == 2 && dr.ddm[0] == 0x22 && dr.ddm[1] == 0x01
buf = buf[n:]
if success || len(buf) == 0 {
break
}
}
return
}
type drda struct {
ddm []byte
param []byte
}
func parseDRDA(buf []byte) (dr drda, n int) {
n = int(buf[0])*256 + int(buf[1])
dr.ddm = buf[8:10]
if len(buf) > 15 {
nullByteIndex := bytes.IndexByte(buf[15:], 0xff) // 0xff is string terminator
if nullByteIndex > 0 {
dr.param = buf[15 : nullByteIndex+15]
}
}
return
}