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// Copyright 2012 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package runner
import (
"bytes"
"crypto/aes"
"crypto/cipher"
"crypto/hmac"
"crypto/sha256"
"crypto/subtle"
"errors"
"io"
)
// sessionState contains the information that is serialized into a session
// ticket in order to later resume a connection.
type sessionState struct {
vers uint16
cipherSuite uint16
masterSecret []byte
handshakeHash []byte
certificates [][]byte
extendedMasterSecret bool
}
func (s *sessionState) equal(i interface{}) bool {
s1, ok := i.(*sessionState)
if !ok {
return false
}
if s.vers != s1.vers ||
s.cipherSuite != s1.cipherSuite ||
!bytes.Equal(s.masterSecret, s1.masterSecret) ||
!bytes.Equal(s.handshakeHash, s1.handshakeHash) ||
s.extendedMasterSecret != s1.extendedMasterSecret {
return false
}
if len(s.certificates) != len(s1.certificates) {
return false
}
for i := range s.certificates {
if !bytes.Equal(s.certificates[i], s1.certificates[i]) {
return false
}
}
return true
}
func (s *sessionState) marshal() []byte {
length := 2 + 2 + 2 + len(s.masterSecret) + 2 + len(s.handshakeHash) + 2
for _, cert := range s.certificates {
length += 4 + len(cert)
}
length++
ret := make([]byte, length)
x := ret
x[0] = byte(s.vers >> 8)
x[1] = byte(s.vers)
x[2] = byte(s.cipherSuite >> 8)
x[3] = byte(s.cipherSuite)
x[4] = byte(len(s.masterSecret) >> 8)
x[5] = byte(len(s.masterSecret))
x = x[6:]
copy(x, s.masterSecret)
x = x[len(s.masterSecret):]
x[0] = byte(len(s.handshakeHash) >> 8)
x[1] = byte(len(s.handshakeHash))
x = x[2:]
copy(x, s.handshakeHash)
x = x[len(s.handshakeHash):]
x[0] = byte(len(s.certificates) >> 8)
x[1] = byte(len(s.certificates))
x = x[2:]
for _, cert := range s.certificates {
x[0] = byte(len(cert) >> 24)
x[1] = byte(len(cert) >> 16)
x[2] = byte(len(cert) >> 8)
x[3] = byte(len(cert))
copy(x[4:], cert)
x = x[4+len(cert):]
}
if s.extendedMasterSecret {
x[0] = 1
}
x = x[1:]
return ret
}
func (s *sessionState) unmarshal(data []byte) bool {
if len(data) < 8 {
return false
}
s.vers = uint16(data[0])<<8 | uint16(data[1])
s.cipherSuite = uint16(data[2])<<8 | uint16(data[3])
masterSecretLen := int(data[4])<<8 | int(data[5])
data = data[6:]
if len(data) < masterSecretLen {
return false
}
s.masterSecret = data[:masterSecretLen]
data = data[masterSecretLen:]
if len(data) < 2 {
return false
}
handshakeHashLen := int(data[0])<<8 | int(data[1])
data = data[2:]
if len(data) < handshakeHashLen {
return false
}
s.handshakeHash = data[:handshakeHashLen]
data = data[handshakeHashLen:]
if len(data) < 2 {
return false
}
numCerts := int(data[0])<<8 | int(data[1])
data = data[2:]
s.certificates = make([][]byte, numCerts)
for i := range s.certificates {
if len(data) < 4 {
return false
}
certLen := int(data[0])<<24 | int(data[1])<<16 | int(data[2])<<8 | int(data[3])
data = data[4:]
if certLen < 0 {
return false
}
if len(data) < certLen {
return false
}
s.certificates[i] = data[:certLen]
data = data[certLen:]
}
if len(data) < 1 {
return false
}
s.extendedMasterSecret = false
if data[0] == 1 {
s.extendedMasterSecret = true
}
data = data[1:]
if len(data) > 0 {
return false
}
return true
}
func (c *Conn) encryptTicket(state *sessionState) ([]byte, error) {
serialized := state.marshal()
encrypted := make([]byte, aes.BlockSize+len(serialized)+sha256.Size)
iv := encrypted[:aes.BlockSize]
macBytes := encrypted[len(encrypted)-sha256.Size:]
if _, err := io.ReadFull(c.config.rand(), iv); err != nil {
return nil, err
}
block, err := aes.NewCipher(c.config.SessionTicketKey[:16])
if err != nil {
return nil, errors.New("tls: failed to create cipher while encrypting ticket: " + err.Error())
}
cipher.NewCTR(block, iv).XORKeyStream(encrypted[aes.BlockSize:], serialized)
mac := hmac.New(sha256.New, c.config.SessionTicketKey[16:32])
mac.Write(encrypted[:len(encrypted)-sha256.Size])
mac.Sum(macBytes[:0])
return encrypted, nil
}
func (c *Conn) decryptTicket(encrypted []byte) (*sessionState, bool) {
if len(encrypted) < aes.BlockSize+sha256.Size {
return nil, false
}
iv := encrypted[:aes.BlockSize]
macBytes := encrypted[len(encrypted)-sha256.Size:]
mac := hmac.New(sha256.New, c.config.SessionTicketKey[16:32])
mac.Write(encrypted[:len(encrypted)-sha256.Size])
expected := mac.Sum(nil)
if subtle.ConstantTimeCompare(macBytes, expected) != 1 {
return nil, false
}
block, err := aes.NewCipher(c.config.SessionTicketKey[:16])
if err != nil {
return nil, false
}
ciphertext := encrypted[aes.BlockSize : len(encrypted)-sha256.Size]
plaintext := make([]byte, len(ciphertext))
cipher.NewCTR(block, iv).XORKeyStream(plaintext, ciphertext)
state := new(sessionState)
ok := state.unmarshal(plaintext)
return state, ok
}
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