blob: 687e5ef11b462baab95cf01ce36f1ce74e1fe10d [file] [log] [blame]
// Copyright 2009 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 tls
import (
"bytes"
"crypto"
"crypto/rsa"
"crypto/subtle"
"crypto/x509"
"errors"
"io"
"strconv"
)
func (c *Conn) clientHandshake() error {
finishedHash := newFinishedHash(versionTLS10)
if c.config == nil {
c.config = defaultConfig()
}
hello := &clientHelloMsg{
vers: maxVersion,
cipherSuites: c.config.cipherSuites(),
compressionMethods: []uint8{compressionNone},
random: make([]byte, 32),
ocspStapling: true,
serverName: c.config.ServerName,
supportedCurves: []uint16{curveP256, curveP384, curveP521},
supportedPoints: []uint8{pointFormatUncompressed},
nextProtoNeg: len(c.config.NextProtos) > 0,
}
t := uint32(c.config.time().Unix())
hello.random[0] = byte(t >> 24)
hello.random[1] = byte(t >> 16)
hello.random[2] = byte(t >> 8)
hello.random[3] = byte(t)
_, err := io.ReadFull(c.config.rand(), hello.random[4:])
if err != nil {
c.sendAlert(alertInternalError)
return errors.New("short read from Rand")
}
finishedHash.Write(hello.marshal())
c.writeRecord(recordTypeHandshake, hello.marshal())
msg, err := c.readHandshake()
if err != nil {
return err
}
serverHello, ok := msg.(*serverHelloMsg)
if !ok {
return c.sendAlert(alertUnexpectedMessage)
}
finishedHash.Write(serverHello.marshal())
vers, ok := mutualVersion(serverHello.vers)
if !ok || vers < versionTLS10 {
// TLS 1.0 is the minimum version supported as a client.
return c.sendAlert(alertProtocolVersion)
}
c.vers = vers
c.haveVers = true
if serverHello.compressionMethod != compressionNone {
return c.sendAlert(alertUnexpectedMessage)
}
if !hello.nextProtoNeg && serverHello.nextProtoNeg {
c.sendAlert(alertHandshakeFailure)
return errors.New("server advertised unrequested NPN")
}
suite := mutualCipherSuite(c.config.cipherSuites(), serverHello.cipherSuite)
if suite == nil {
return c.sendAlert(alertHandshakeFailure)
}
msg, err = c.readHandshake()
if err != nil {
return err
}
certMsg, ok := msg.(*certificateMsg)
if !ok || len(certMsg.certificates) == 0 {
return c.sendAlert(alertUnexpectedMessage)
}
finishedHash.Write(certMsg.marshal())
certs := make([]*x509.Certificate, len(certMsg.certificates))
for i, asn1Data := range certMsg.certificates {
cert, err := x509.ParseCertificate(asn1Data)
if err != nil {
c.sendAlert(alertBadCertificate)
return errors.New("failed to parse certificate from server: " + err.Error())
}
certs[i] = cert
}
if !c.config.InsecureSkipVerify {
opts := x509.VerifyOptions{
Roots: c.config.rootCAs(),
CurrentTime: c.config.time(),
DNSName: c.config.ServerName,
Intermediates: x509.NewCertPool(),
}
for i, cert := range certs {
if i == 0 {
continue
}
opts.Intermediates.AddCert(cert)
}
c.verifiedChains, err = certs[0].Verify(opts)
if err != nil {
c.sendAlert(alertBadCertificate)
return err
}
}
if _, ok := certs[0].PublicKey.(*rsa.PublicKey); !ok {
return c.sendAlert(alertUnsupportedCertificate)
}
c.peerCertificates = certs
if serverHello.ocspStapling {
msg, err = c.readHandshake()
if err != nil {
return err
}
cs, ok := msg.(*certificateStatusMsg)
if !ok {
return c.sendAlert(alertUnexpectedMessage)
}
finishedHash.Write(cs.marshal())
if cs.statusType == statusTypeOCSP {
c.ocspResponse = cs.response
}
}
msg, err = c.readHandshake()
if err != nil {
return err
}
keyAgreement := suite.ka()
skx, ok := msg.(*serverKeyExchangeMsg)
if ok {
finishedHash.Write(skx.marshal())
err = keyAgreement.processServerKeyExchange(c.config, hello, serverHello, certs[0], skx)
if err != nil {
c.sendAlert(alertUnexpectedMessage)
return err
}
msg, err = c.readHandshake()
if err != nil {
return err
}
}
var certToSend *Certificate
certReq, ok := msg.(*certificateRequestMsg)
if ok {
// RFC 4346 on the certificateAuthorities field:
// A list of the distinguished names of acceptable certificate
// authorities. These distinguished names may specify a desired
// distinguished name for a root CA or for a subordinate CA;
// thus, this message can be used to describe both known roots
// and a desired authorization space. If the
// certificate_authorities list is empty then the client MAY
// send any certificate of the appropriate
// ClientCertificateType, unless there is some external
// arrangement to the contrary.
finishedHash.Write(certReq.marshal())
// For now, we only know how to sign challenges with RSA
rsaAvail := false
for _, certType := range certReq.certificateTypes {
if certType == certTypeRSASign {
rsaAvail = true
break
}
}
// We need to search our list of client certs for one
// where SignatureAlgorithm is RSA and the Issuer is in
// certReq.certificateAuthorities
findCert:
for i, cert := range c.config.Certificates {
if !rsaAvail {
continue
}
leaf := cert.Leaf
if leaf == nil {
if leaf, err = x509.ParseCertificate(cert.Certificate[0]); err != nil {
c.sendAlert(alertInternalError)
return errors.New("tls: failed to parse client certificate #" + strconv.Itoa(i) + ": " + err.Error())
}
}
if leaf.PublicKeyAlgorithm != x509.RSA {
continue
}
if len(certReq.certificateAuthorities) == 0 {
// they gave us an empty list, so just take the
// first RSA cert from c.config.Certificates
certToSend = &cert
break
}
for _, ca := range certReq.certificateAuthorities {
if bytes.Equal(leaf.RawIssuer, ca) {
certToSend = &cert
break findCert
}
}
}
msg, err = c.readHandshake()
if err != nil {
return err
}
}
shd, ok := msg.(*serverHelloDoneMsg)
if !ok {
return c.sendAlert(alertUnexpectedMessage)
}
finishedHash.Write(shd.marshal())
if certToSend != nil {
certMsg = new(certificateMsg)
certMsg.certificates = certToSend.Certificate
finishedHash.Write(certMsg.marshal())
c.writeRecord(recordTypeHandshake, certMsg.marshal())
}
preMasterSecret, ckx, err := keyAgreement.generateClientKeyExchange(c.config, hello, certs[0])
if err != nil {
c.sendAlert(alertInternalError)
return err
}
if ckx != nil {
finishedHash.Write(ckx.marshal())
c.writeRecord(recordTypeHandshake, ckx.marshal())
}
if certToSend != nil {
certVerify := new(certificateVerifyMsg)
digest := make([]byte, 0, 36)
digest = finishedHash.serverMD5.Sum(digest)
digest = finishedHash.serverSHA1.Sum(digest)
signed, err := rsa.SignPKCS1v15(c.config.rand(), c.config.Certificates[0].PrivateKey.(*rsa.PrivateKey), crypto.MD5SHA1, digest)
if err != nil {
return c.sendAlert(alertInternalError)
}
certVerify.signature = signed
finishedHash.Write(certVerify.marshal())
c.writeRecord(recordTypeHandshake, certVerify.marshal())
}
masterSecret, clientMAC, serverMAC, clientKey, serverKey, clientIV, serverIV :=
keysFromPreMasterSecret(c.vers, preMasterSecret, hello.random, serverHello.random, suite.macLen, suite.keyLen, suite.ivLen)
clientCipher := suite.cipher(clientKey, clientIV, false /* not for reading */ )
clientHash := suite.mac(c.vers, clientMAC)
c.out.prepareCipherSpec(c.vers, clientCipher, clientHash)
c.writeRecord(recordTypeChangeCipherSpec, []byte{1})
if serverHello.nextProtoNeg {
nextProto := new(nextProtoMsg)
proto, fallback := mutualProtocol(c.config.NextProtos, serverHello.nextProtos)
nextProto.proto = proto
c.clientProtocol = proto
c.clientProtocolFallback = fallback
finishedHash.Write(nextProto.marshal())
c.writeRecord(recordTypeHandshake, nextProto.marshal())
}
finished := new(finishedMsg)
finished.verifyData = finishedHash.clientSum(masterSecret)
finishedHash.Write(finished.marshal())
c.writeRecord(recordTypeHandshake, finished.marshal())
serverCipher := suite.cipher(serverKey, serverIV, true /* for reading */ )
serverHash := suite.mac(c.vers, serverMAC)
c.in.prepareCipherSpec(c.vers, serverCipher, serverHash)
c.readRecord(recordTypeChangeCipherSpec)
if c.err != nil {
return c.err
}
msg, err = c.readHandshake()
if err != nil {
return err
}
serverFinished, ok := msg.(*finishedMsg)
if !ok {
return c.sendAlert(alertUnexpectedMessage)
}
verify := finishedHash.serverSum(masterSecret)
if len(verify) != len(serverFinished.verifyData) ||
subtle.ConstantTimeCompare(verify, serverFinished.verifyData) != 1 {
return c.sendAlert(alertHandshakeFailure)
}
c.handshakeComplete = true
c.cipherSuite = suite.id
return nil
}
// mutualProtocol finds the mutual Next Protocol Negotiation protocol given the
// set of client and server supported protocols. The set of client supported
// protocols must not be empty. It returns the resulting protocol and flag
// indicating if the fallback case was reached.
func mutualProtocol(clientProtos, serverProtos []string) (string, bool) {
for _, s := range serverProtos {
for _, c := range clientProtos {
if s == c {
return s, false
}
}
}
return clientProtos[0], true
}