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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 (
"crypto/aes"
"crypto/cipher"
"crypto/hmac"
"crypto/sha256"
"crypto/subtle"
"encoding/binary"
"errors"
"io"
"time"
)
// 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
earlyALPN []byte
ticketCreationTime time.Time
ticketExpiration time.Time
ticketFlags uint32
ticketAgeAdd uint32
}
func (s *sessionState) marshal() []byte {
msg := newByteBuilder()
msg.addU16(s.vers)
msg.addU16(s.cipherSuite)
masterSecret := msg.addU16LengthPrefixed()
masterSecret.addBytes(s.masterSecret)
handshakeHash := msg.addU16LengthPrefixed()
handshakeHash.addBytes(s.handshakeHash)
msg.addU16(uint16(len(s.certificates)))
for _, cert := range s.certificates {
certMsg := msg.addU32LengthPrefixed()
certMsg.addBytes(cert)
}
if s.extendedMasterSecret {
msg.addU8(1)
} else {
msg.addU8(0)
}
if s.vers >= VersionTLS13 {
msg.addU64(uint64(s.ticketCreationTime.UnixNano()))
msg.addU64(uint64(s.ticketExpiration.UnixNano()))
msg.addU32(s.ticketFlags)
msg.addU32(s.ticketAgeAdd)
}
earlyALPN := msg.addU16LengthPrefixed()
earlyALPN.addBytes(s.earlyALPN)
return msg.finish()
}
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 s.vers >= VersionTLS13 {
if len(data) < 24 {
return false
}
s.ticketCreationTime = time.Unix(0, int64(binary.BigEndian.Uint64(data)))
data = data[8:]
s.ticketExpiration = time.Unix(0, int64(binary.BigEndian.Uint64(data)))
data = data[8:]
s.ticketFlags = binary.BigEndian.Uint32(data)
data = data[4:]
s.ticketAgeAdd = binary.BigEndian.Uint32(data)
data = data[4:]
}
earlyALPNLen := int(data[0])<<8 | int(data[1])
data = data[2:]
if len(data) < earlyALPNLen {
return false
}
s.earlyALPN = data[:earlyALPNLen]
data = data[earlyALPNLen:]
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
}