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package transfer
import (
"bytes"
"crypto/hmac"
"crypto/md5"
"crypto/rc4"
"encoding/binary"
"errors"
"hash"
"io"
"net"
"syscall"
"time"
)
type digestMD5PrivacyConn struct {
conn net.Conn
readDeadline time.Time
sendSeqNum int
readSeqNum int
decodeMAC hash.Hash
encodeMAC hash.Hash
decryptor *rc4.Cipher
encryptor *rc4.Cipher
readBuf bytes.Buffer
writeBuf bytes.Buffer
}
// digestMD5PrivacyConn returns a net.Conn wrapper that peforms md5-digest
// encryption on data passing over it.
func newDigestMD5PrivacyConn(conn net.Conn, kic, kis, kcc, kcs []byte) digestMD5Conn {
encryptor, _ := rc4.NewCipher(kcc)
decryptor, _ := rc4.NewCipher(kcs)
return &digestMD5PrivacyConn{
conn: conn,
encryptor: encryptor,
decryptor: decryptor,
decodeMAC: hmac.New(md5.New, kis),
encodeMAC: hmac.New(md5.New, kic),
}
}
func (d *digestMD5PrivacyConn) Close() error {
return d.conn.Close()
}
func (d *digestMD5PrivacyConn) LocalAddr() net.Addr {
return d.conn.LocalAddr()
}
func (d *digestMD5PrivacyConn) RemoteAddr() net.Addr {
return d.conn.RemoteAddr()
}
func (d *digestMD5PrivacyConn) SetDeadline(t time.Time) error {
d.readDeadline = t
return d.conn.SetDeadline(t)
}
func (d *digestMD5PrivacyConn) SetReadDeadline(t time.Time) error {
d.readDeadline = t
return d.conn.SetReadDeadline(t)
}
func (d *digestMD5PrivacyConn) SetWriteDeadline(t time.Time) error {
return d.conn.SetWriteDeadline(t)
}
func (d *digestMD5PrivacyConn) Read(b []byte) (int, error) {
if !d.readDeadline.IsZero() && d.readDeadline.Before(time.Now()) {
return 0, syscall.ETIMEDOUT
}
n, err := d.readBuf.Read(b)
if len(b) == n || (err != nil && err != io.EOF) {
return n, err
}
var sz int32
err = binary.Read(d.conn, binary.BigEndian, &sz)
if err != nil {
return 0, err
}
d.readBuf.Reset()
d.readBuf.Grow(int(sz))
_, err = io.CopyN(&d.readBuf, d.conn, int64(sz))
if err != nil {
return n, err
}
decoded, err := d.decode(d.readBuf.Bytes())
if err != nil {
return n, err
}
d.readBuf.Truncate(len(decoded))
return d.readBuf.Read(b[n:])
}
func (d *digestMD5PrivacyConn) decode(input []byte) (out []byte, err error) {
inputLen := len(input)
if inputLen < saslIntegrityPrefixLength {
return nil, errors.New("invalid response from datanode: bad response length")
}
seqNumStart := inputLen - macSeqNumLen
msgTypeStart := seqNumStart - macMsgTypeLen
encryptedLen := inputLen - macMsgTypeLen - macSeqNumLen
d.decryptor.XORKeyStream(input[:encryptedLen], input[:encryptedLen])
origHash := input[encryptedLen-macHMACLen : encryptedLen]
encryptedLen -= macHMACLen
seqBuf := lenEncodeBytes(d.readSeqNum)
hmac := msgHMAC(d.decodeMAC, seqBuf, input[:encryptedLen])
msgType := input[msgTypeStart : msgTypeStart+macMsgTypeLen]
seqNum := input[seqNumStart : seqNumStart+macSeqNumLen]
if !bytes.Equal(hmac, origHash) || !bytes.Equal(macMsgType[:], msgType) || !bytes.Equal(seqNum, seqBuf[:]) {
return nil, errors.New("invalid response from datanode: HMAC check failed")
}
d.readSeqNum++
return input[:encryptedLen], nil
}
func (d *digestMD5PrivacyConn) Write(b []byte) (int, error) {
inputLen := len(b)
seqBuf := lenEncodeBytes(d.sendSeqNum)
encryptedLen := inputLen + macHMACLen
outputLen := macDataLen + encryptedLen + macMsgTypeLen + macSeqNumLen
d.writeBuf.Reset()
d.writeBuf.Grow(outputLen)
finalLength := encryptedLen + macMsgTypeLen + macSeqNumLen
binary.Write(&d.writeBuf, binary.BigEndian, int32(finalLength))
d.writeBuf.Write(b)
hmac := msgHMAC(d.encodeMAC, seqBuf, b)
d.writeBuf.Write(hmac)
toEncrypt := d.writeBuf.Bytes()[macDataLen:]
d.encryptor.XORKeyStream(toEncrypt, toEncrypt)
d.writeBuf.Write(macMsgType[:])
binary.Write(&d.writeBuf, binary.BigEndian, int32(d.sendSeqNum))
d.sendSeqNum++
n, err := d.writeBuf.WriteTo(d.conn)
return int(n), err
}
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