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handshake_server.go
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handshake_server.go
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// Copyright (c) 2019 The BFE Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// 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 bfe_tls
import (
"crypto"
"crypto/ecdsa"
"crypto/rsa"
"crypto/subtle"
"crypto/x509"
"encoding/asn1"
"errors"
"fmt"
"io"
"strings"
"time"
)
// serverHandshakeState contains details of a server handshake in progress.
// It's discarded once the handshake has completed.
type serverHandshakeState struct {
c *Conn
clientHello *clientHelloMsg
hello *serverHelloMsg
suite *cipherSuite
ellipticOk bool
ecdsaOk bool
chachaOk bool
sessionTicketOK bool
useRC4 uint8
sessionState *sessionState
finishedHash finishedHash
masterSecret []byte
certsFromClient [][]byte
cert *Certificate
}
// serverHandshake performs a TLS handshake as a server.
func (c *Conn) serverHandshake() error {
handshakeStart := time.Now()
config := c.config
// If this is the first server handshake, we generate a random key to
// encrypt the tickets with.
config.serverInitOnce.Do(config.serverInit)
hs := serverHandshakeState{
c: c,
}
isResume, err := hs.readClientHello()
if err == io.EOF && 0 == c.readFromUntilLen {
state.TlsHandshakeZeroData.Inc(1)
}
if err != nil {
state.TlsHandshakeReadClientHelloErr.Inc(1)
return err
}
// For an overview of TLS handshaking, see https://tools.ietf.org/html/rfc5246#section-7.3
if isResume {
state.TlsHandshakeResumeAll.Inc(1)
// The client has included a session ticket and so we do an abbreviated handshake.
if err := hs.doResumeHandshake(); err != nil {
return err
}
if err := hs.establishKeys(); err != nil {
return err
}
if err := hs.sendFinished(); err != nil {
return err
}
if err := hs.readFinished(); err != nil {
return err
}
c.didResume = true
state.TlsHandshakeResumeSucc.Inc(1)
} else {
state.TlsHandshakeFullAll.Inc(1)
// The client didn't include a session ticket, or it wasn't
// valid so we do a full handshake.
if err := hs.doFullHandshake(); err != nil {
return err
}
if err := hs.establishKeys(); err != nil {
return err
}
if err := hs.readFinished(); err != nil {
return err
}
if err := hs.sendSessionTicket(); err != nil {
return err
}
if err := hs.sendFinished(); err != nil {
return err
}
// update session cache
if !c.config.SessionCacheDisabled && c.config.ServerSessionCache != nil {
// If a server is planning on issuing a session ticket to a client that
// does not present one, it SHOULD include an empty Session ID in the ServerHello
// If the Session Id is not empty, the sever choose stateful resume(session id).
if len(hs.hello.sessionId) > 0 {
state := &sessionState{
vers: c.vers,
cipherSuite: hs.suite.id,
sessionId: hs.hello.sessionId,
masterSecret: hs.masterSecret,
certificates: hs.certsFromClient,
}
c.config.ServerSessionCache.Put(fmt.Sprintf("%x", hs.hello.sessionId),
state.marshal())
}
}
state.TlsHandshakeFullSucc.Inc(1)
}
c.handshakeComplete = true
c.handshakeTime = time.Since(handshakeStart)
// Record master secret for established tls conn. Master secret may
// saved in NSS key log format so that external programs (eg. wireshark)
// can decrypt TLS connections for trouble shooting.
c.clientRandom = hs.clientHello.random
c.serverRandom = hs.hello.random
c.masterSecret = hs.masterSecret
return nil
}
// readClientHello reads a ClientHello message from the client and decides
// whether we will perform session resumption.
func (hs *serverHandshakeState) readClientHello() (isResume bool, err error) {
config := hs.c.config
c := hs.c
msg, err := c.readHandshake()
if err != nil {
return false, err
}
var ok bool
hs.clientHello, ok = msg.(*clientHelloMsg)
if !ok {
c.sendAlert(alertUnexpectedMessage)
return false, unexpectedMessageError(hs.clientHello, msg)
}
c.vers, ok = config.mutualVersion(hs.clientHello.vers)
if !ok {
c.sendAlert(alertProtocolVersion)
return false, fmt.Errorf("tls: client offered an unsupported, maximum protocol version of %x", hs.clientHello.vers)
}
if len(hs.clientHello.serverName) > 0 {
c.serverName = hs.clientHello.serverName
}
// get customized config for current connection
var rule *Rule
if config.ServerRule != nil {
rule = config.ServerRule.Get(c)
}
c.grade = GradeC
if rule != nil {
c.grade = rule.Grade
c.enableDynamicRecord = rule.DynamicRecord
}
c.vers, ok = config.checkVersionGrade(c.vers, c.grade)
if !ok {
c.sendAlert(alertProtocolVersion)
return false, fmt.Errorf("tls: client offered an unsupported suite for this grade, grade is %s", c.grade)
}
c.haveVers = true
hs.useRC4 = config.checkCipherGrade(c)
hs.finishedHash = newFinishedHash(c.vers)
if c.sslv2Data == nil {
hs.finishedHash.Write(hs.clientHello.marshal())
} else {
hs.finishedHash.Write(c.sslv2Data)
c.sslv2Data = nil
}
hs.hello = new(serverHelloMsg)
supportedCurve := false
preferredCurves := config.curvePreferences()
Curves:
for _, curve := range hs.clientHello.supportedCurves {
for _, supported := range preferredCurves {
if supported == curve {
supportedCurve = true
break Curves
}
}
}
supportedPointFormat := false
for _, pointFormat := range hs.clientHello.supportedPoints {
if pointFormat == pointFormatUncompressed {
supportedPointFormat = true
break
}
}
hs.ellipticOk = supportedCurve && supportedPointFormat
foundCompression := false
// We only support null compression, so check that the client offered it.
for _, compression := range hs.clientHello.compressionMethods {
if compression == compressionNone {
foundCompression = true
break
}
}
if !foundCompression {
c.sendAlert(alertHandshakeFailure)
return false, errors.New("tls: client does not support uncompressed connections")
}
hs.hello.vers = c.vers
hs.hello.random, err = generateHelloRandom(config.rand())
if err != nil {
c.sendAlert(alertInternalError)
return false, err
}
hs.hello.secureRenegotiation = hs.clientHello.secureRenegotiation
hs.hello.compressionMethod = compressionNone
nextProtos := config.NextProtos
if rule != nil {
nextProtos = rule.NextProtos.Get(c)
}
if len(hs.clientHello.alpnProtocols) > 0 {
if selectedProto, fallback := mutualProtocol(hs.clientHello.alpnProtocols, nextProtos); !fallback {
hs.hello.alpnProtocol = selectedProto
c.clientProtocol = selectedProto
}
} else {
// Although sending an NPN extension without h2 is reasonable, some client
// has a bug around this. Best to send NPN without h2.
nextProtos = checkAndRemoveH2(nextProtos)
// Although sending an empty NPN extension is reasonable, Firefox has
// had a bug around this. Best to send nothing at all if
// config.NextProtos is empty. See
// https://code.google.com/p/go/issues/detail?id=5445.
if hs.clientHello.nextProtoNeg && len(nextProtos) > 0 {
hs.hello.nextProtoNeg = true
hs.hello.nextProtos = nextProtos
}
}
// Select certificate for current connection
if len(config.Certificates) == 0 {
c.sendAlert(alertInternalError)
return false, errors.New("tls: no certificates configured")
}
hs.cert = &config.Certificates[0]
if len(hs.clientHello.serverName) > 0 {
hs.cert = config.getCertificateForName(hs.clientHello.serverName)
}
if tlsMultiCertificate != nil {
// select certificate by thirdparty policy
if cert := tlsMultiCertificate.Get(c); cert != nil {
hs.cert = cert
}
} else if config.MultiCert != nil {
// select certificate by default policy
if cert := config.MultiCert.Get(c); cert != nil {
hs.cert = cert
}
}
_, hs.ecdsaOk = hs.cert.PrivateKey.(*ecdsa.PrivateKey)
// Select client auth policy for current connection
c.clientAuth = config.ClientAuth
if rule != nil && rule.ClientAuth {
c.clientAuth = RequireAndVerifyClientCert
c.clientCAs = rule.ClientCAs
c.clientCAName = rule.ClientCAName
c.clientCRLPool = rule.ClientCRLPool
}
// check whether chacha20-poly1305 is enabled for current connection
if rule != nil {
hs.chachaOk = rule.Chacha20
}
if hs.checkForResumption() {
return true, nil
}
var preferenceList, supportedList []uint16
if c.config.PreferServerCipherSuites {
preferenceList = c.config.cipherSuites()
supportedList = hs.clientHello.cipherSuites
} else {
preferenceList = hs.clientHello.cipherSuites
supportedList = c.config.cipherSuites()
}
if c.config.PreferServerCipherSuites && len(c.config.CipherSuitesPriority) == len(preferenceList) {
// Equivalent cipher suite negotiation
hs.suite = hs.negotiateEquivalentCipherSuites(supportedList, preferenceList)
} else {
// Normal cipher suite negotiation
for _, id := range preferenceList {
if hs.suite, _ = c.tryCipherSuite(id, supportedList, c.vers,
hs.ellipticOk, hs.ecdsaOk, hs.chachaOk, hs.useRC4); hs.suite != nil {
break
}
}
}
// no cipher suite supported by both client and server.
if hs.suite == nil {
// If client proposes ECDHE without ECC extensions, just try ECDHE cipher suite
// and choose CurveP256 and Uncompressed point format for client.
//
// Note: A client that proposes ECC cipher suites may choose not to include
// elliptic curves extension or elliptic point format extension. In this case,
// the server is free to choose any one of the elliptic curves or point formats.
//
// For more information, see RFC 4492 Section 4
ellipticMayOk := hs.checkEllipticMayOk(supportedCurve, supportedPointFormat)
if ellipticMayOk {
for _, id := range preferenceList {
if !CheckSuiteECDHE(id) {
continue
}
if hs.suite, _ = c.tryCipherSuite(id, supportedList, c.vers, true, hs.ecdsaOk, hs.chachaOk, hs.useRC4); hs.suite != nil {
break
}
}
if hs.suite != nil {
state.TlsHandshakeAcceptEcdheWithoutExt.Inc(1)
hs.clientHello.supportedCurves = append(hs.clientHello.supportedCurves, CurveP256)
hs.clientHello.supportedPoints = append(hs.clientHello.supportedPoints, pointFormatUncompressed)
}
}
}
if hs.suite == nil {
c.sendAlert(alertHandshakeFailure)
state.TlsHandshakeNoSharedCipherSuite.Inc(1)
return false, fmt.Errorf("tls: no cipher suite supported by both client and server: %v",
hs.clientHello.cipherSuites)
}
// See https://tools.ietf.org/html/draft-ietf-tls-downgrade-scsv-00.
for _, id := range hs.clientHello.cipherSuites {
if id == TLS_FALLBACK_SCSV {
// The client is doing a fallback connection.
if hs.clientHello.vers < c.config.MaxVersion {
c.sendAlert(alertInappropriateFallback)
return false, errors.New("tls: client using inppropriate protocol fallback")
}
break
}
}
hs.validateHttp2Accepted()
return false, nil
}
// Equivalent cipher suite negotiation
// Note: for equivalent cipher suites (cipher suites with same priority in server side),
// selects the client's most preferred ciphersuite.
func (hs *serverHandshakeState) negotiateEquivalentCipherSuites(clientSuites, serverSuites []uint16) *cipherSuite {
var suiteSelected *cipherSuite
var suiteServerOrder uint16
var suiteClientOrder int
c := hs.c
for index, serverOrder := range c.config.CipherSuitesPriority {
id := serverSuites[index]
// check whether current suite is acceptable by client and client's preference for it
if suite, clientOrder := c.tryCipherSuite(id, clientSuites, c.vers,
hs.ellipticOk, hs.ecdsaOk, hs.chachaOk, hs.useRC4); suite != nil {
// if found first acceptable suite or better suite
if suiteSelected == nil || (serverOrder == suiteServerOrder && clientOrder < suiteClientOrder) {
suiteSelected = suite
suiteServerOrder = serverOrder
suiteClientOrder = clientOrder
}
}
// stop check suite with lower priority
if suiteSelected != nil && suiteServerOrder < serverOrder {
break
}
}
return suiteSelected
}
func checkAndRemoveH2(protos []string) []string {
nextProtos := make([]string, 0)
for _, p := range protos {
if p != "h2" {
nextProtos = append(nextProtos, p)
}
}
return nextProtos
}
func (hs *serverHandshakeState) validateHttp2Accepted() {
// Note: implementations for http2 Must use TLS1.2 or higher and SHOULD not use
// any of the cipher suites that are listed in the cipher suite black list.
// See RFC 7540 Section 9.2
c := hs.c
if hs.hello.alpnProtocol == "h2" {
if !checkCipherSuiteHttp2Accepted(hs.suite.id) || c.vers < VersionTLS12 {
hs.hello.alpnProtocol = "http/1.1"
c.clientProtocol = "http/1.1"
}
}
}
func (hs *serverHandshakeState) checkEllipticMayOk(supportedCurve, supportedPointFormat bool) bool {
if hs.c.vers <= VersionSSL30 {
return false
}
if supportedCurve && len(hs.clientHello.supportedPoints) == 0 {
return true
}
if supportedPointFormat && len(hs.clientHello.supportedCurves) == 0 {
return true
}
if len(hs.clientHello.supportedCurves) == 0 && len(hs.clientHello.supportedPoints) == 0 {
return true
}
return false
}
// checkForResumption returns true if we should perform resumption on this connection.
func (hs *serverHandshakeState) checkForResumption() bool {
c := hs.c
var ok bool
// check session ticket
if !c.config.SessionTicketsDisabled && hs.clientHello.ticketSupported && len(hs.clientHello.sessionTicket) != 0 {
state.TlsHandshakeCheckResumeSessionTicket.Inc(1)
hs.sessionTicketOK = true
if hs.sessionState, ok = c.decryptTicket(hs.clientHello.sessionTicket); !ok {
return false
}
} else {
// check session cache
if len(hs.clientHello.sessionId) == 0 {
return false
}
state.TlsHandshakeCheckResumeSessionCache.Inc(1)
hs.sessionTicketOK = false
hs.sessionState = nil
if !c.config.SessionCacheDisabled && c.config.ServerSessionCache != nil {
sessionCache := c.config.ServerSessionCache
sessionParam, ok := sessionCache.Get(fmt.Sprintf("%x", hs.clientHello.sessionId))
if !ok {
return false
}
candidateSession := new(sessionState)
if ok := candidateSession.unmarshal(sessionParam); !ok {
return false
}
hs.sessionState = candidateSession
}
}
if hs.sessionState == nil || hs.sessionState.vers > hs.clientHello.vers {
return false
}
if vers, ok := c.config.mutualVersion(hs.sessionState.vers); !ok || vers != hs.sessionState.vers {
return false
}
cipherSuiteOk := false
// Check that the client is still offering the ciphersuite in the session.
for _, id := range hs.clientHello.cipherSuites {
if id == hs.sessionState.cipherSuite {
cipherSuiteOk = true
break
}
}
if !cipherSuiteOk {
return false
}
// Check that we also support the ciphersuite from the session.
hs.suite, _ = c.tryCipherSuite(hs.sessionState.cipherSuite, c.config.cipherSuites(), hs.sessionState.vers,
hs.ellipticOk, hs.ecdsaOk, hs.chachaOk, hs.useRC4)
if hs.suite == nil {
return false
}
sessionHasClientCerts := len(hs.sessionState.certificates) != 0
needClientCerts := c.clientAuth == RequireAnyClientCert || c.clientAuth == RequireAndVerifyClientCert
if needClientCerts && !sessionHasClientCerts {
return false
}
if sessionHasClientCerts && c.clientAuth == NoClientCert {
return false
}
if hs.sessionTicketOK {
state.TlsHandshakeShouldResumeSessionTicket.Inc(1)
} else {
state.TlsHandshakeShouldResumeSessionCache.Inc(1)
}
hs.validateHttp2Accepted()
return true
}
func (hs *serverHandshakeState) doResumeHandshake() error {
c := hs.c
hs.hello.cipherSuite = hs.suite.id
// We echo the client's session ID in the ServerHello to let it know
// that we're doing a resumption.
hs.hello.sessionId = hs.clientHello.sessionId
hs.finishedHash.Write(hs.hello.marshal())
c.writeRecord(recordTypeHandshake, hs.hello.marshal())
if len(hs.sessionState.certificates) > 0 {
if _, err := hs.processCertsFromClient(hs.sessionState.certificates); err != nil {
return err
}
}
hs.masterSecret = hs.sessionState.masterSecret
return nil
}
// judge whether ocspstapling update time suitable for server time
func (hs *serverHandshakeState) ocspTimeCheck() bool {
if hs.cert.OCSPParse == nil {
return false
}
if !OcspTimeRangeCheck(hs.cert.OCSPParse) {
state.TlsHandshakeOcspTimeErr.Inc(1)
return false
}
return true
}
func (hs *serverHandshakeState) doFullHandshake() error {
config := hs.c.config
c := hs.c
if hs.clientHello.ocspStapling && len(hs.cert.OCSPStaple) > 0 {
// check ocspstapling time
if ocspOk := hs.ocspTimeCheck(); ocspOk {
hs.hello.ocspStapling = true
c.ocspStaple = true
}
}
if hs.clientHello.ocspStapling {
state.TlsStatusRequestExtCount.Inc(1)
}
hs.hello.ticketSupported = hs.clientHello.ticketSupported && !config.SessionTicketsDisabled
if !hs.hello.ticketSupported && !c.config.SessionCacheDisabled {
// create new session id
hs.hello.sessionId = make([]byte, 32)
if _, err := io.ReadFull(c.config.rand(), hs.hello.sessionId); err != nil {
c.sendAlert(alertInternalError)
return err
}
}
hs.hello.cipherSuite = hs.suite.id
hs.finishedHash.Write(hs.hello.marshal())
c.writeRecord(recordTypeHandshake, hs.hello.marshal())
var certMsg *certificateMsg
var certMsgData []byte
if hs.cert.message != nil {
certMsgData = hs.cert.message
} else {
certMsg := new(certificateMsg)
certMsg.certificates = hs.cert.Certificate
certMsgData = certMsg.marshal()
}
hs.finishedHash.Write(certMsgData)
c.writeRecord(recordTypeHandshake, certMsgData)
if hs.hello.ocspStapling {
certStatus := new(certificateStatusMsg)
certStatus.statusType = statusTypeOCSP
certStatus.response = hs.cert.OCSPStaple
hs.finishedHash.Write(certStatus.marshal())
c.writeRecord(recordTypeHandshake, certStatus.marshal())
}
keyAgreement := hs.suite.ka(c.vers)
skx, err := keyAgreement.generateServerKeyExchange(config, hs.cert, hs.clientHello, hs.hello)
if err != nil {
c.sendAlert(alertHandshakeFailure)
return err
}
if skx != nil {
hs.finishedHash.Write(skx.marshal())
c.writeRecord(recordTypeHandshake, skx.marshal())
}
if c.clientAuth >= RequestClientCert {
// Request a client certificate
certReq := new(certificateRequestMsg)
certReq.certificateTypes = []byte{
byte(certTypeRSASign),
byte(certTypeECDSASign),
}
if c.vers >= VersionTLS12 {
certReq.hasSignatureAndHash = true
certReq.signatureAndHashes = supportedClientCertSignatureAlgorithms
}
// An empty list of certificateAuthorities signals to
// the client that it may send any certificate in response
// to our request. When we know the CAs we trust, then
// we can send them down, so that the client can choose
// an appropriate certificate to give to us.
if clientCAs := c.getClientCAs(); clientCAs != nil {
certReq.certificateAuthorities = clientCAs.Subjects()
}
hs.finishedHash.Write(certReq.marshal())
c.writeRecord(recordTypeHandshake, certReq.marshal())
}
helloDone := new(serverHelloDoneMsg)
hs.finishedHash.Write(helloDone.marshal())
c.writeRecord(recordTypeHandshake, helloDone.marshal())
var pub crypto.PublicKey // public key for client auth, if any
msg, err := c.readHandshake()
if err != nil {
return err
}
var ok bool
// If we requested a client certificate, then the client must send a
// certificate message, even if it's empty.
if c.clientAuth >= RequestClientCert {
if certMsg, ok = msg.(*certificateMsg); !ok {
c.sendAlert(alertUnexpectedMessage)
return unexpectedMessageError(certMsg, msg)
}
hs.finishedHash.Write(certMsg.marshal())
if len(certMsg.certificates) == 0 {
// The client didn't actually send a certificate
switch c.clientAuth {
case RequireAnyClientCert, RequireAndVerifyClientCert:
c.sendAlert(alertBadCertificate)
return errors.New("tls: client didn't provide a certificate")
}
}
pub, err = hs.processCertsFromClient(certMsg.certificates)
if err != nil {
return err
}
msg, err = c.readHandshake()
if err != nil {
return err
}
}
// Get client key exchange
ckx, ok := msg.(*clientKeyExchangeMsg)
if !ok {
c.sendAlert(alertUnexpectedMessage)
return unexpectedMessageError(ckx, msg)
}
hs.finishedHash.Write(ckx.marshal())
// If we received a client cert in response to our certificate request message,
// the client will send us a certificateVerifyMsg immediately after the
// clientKeyExchangeMsg. This message is a digest of all preceding
// handshake-layer messages that is signed using the private key corresponding
// to the client's certificate. This allows us to verify that the client is in
// possession of the private key of the certificate.
if len(c.peerCertificates) > 0 {
msg, err = c.readHandshake()
if err != nil {
return err
}
certVerify, ok := msg.(*certificateVerifyMsg)
if !ok {
c.sendAlert(alertUnexpectedMessage)
return unexpectedMessageError(certVerify, msg)
}
switch key := pub.(type) {
case *ecdsa.PublicKey:
ecdsaSig := new(ecdsaSignature)
if _, err = asn1.Unmarshal(certVerify.signature, ecdsaSig); err != nil {
break
}
if ecdsaSig.R.Sign() <= 0 || ecdsaSig.S.Sign() <= 0 {
err = errors.New("ECDSA signature contained zero or negative values")
break
}
digest, _, _ := hs.finishedHash.hashForClientCertificate(signatureECDSA)
if !ecdsa.Verify(key, digest, ecdsaSig.R, ecdsaSig.S) {
err = errors.New("ECDSA verification failure")
break
}
case *rsa.PublicKey:
digest, hashFunc, _ := hs.finishedHash.hashForClientCertificate(signatureRSA)
err = rsa.VerifyPKCS1v15(key, hashFunc, digest, certVerify.signature)
}
if err != nil {
c.sendAlert(alertBadCertificate)
return errors.New("could not validate signature of connection nonces: " + err.Error())
}
hs.finishedHash.Write(certVerify.marshal())
}
preMasterSecret, err := keyAgreement.processClientKeyExchange(config, hs.cert, ckx, c.vers)
if err != nil {
c.sendAlert(alertHandshakeFailure)
return err
}
hs.masterSecret = masterFromPreMasterSecret(c.vers, preMasterSecret, hs.clientHello.random, hs.hello.random)
return nil
}
func (hs *serverHandshakeState) establishKeys() error {
c := hs.c
clientMAC, serverMAC, clientKey, serverKey, clientIV, serverIV :=
keysFromMasterSecret(c.vers, hs.masterSecret, hs.clientHello.random, hs.hello.random, hs.suite.macLen, hs.suite.keyLen, hs.suite.ivLen)
var clientCipher, serverCipher interface{}
var clientHash, serverHash macFunction
if hs.suite.aead == nil {
clientCipher = hs.suite.cipher(clientKey, clientIV, true /* for reading */)
clientHash = hs.suite.mac(c.vers, clientMAC)
serverCipher = hs.suite.cipher(serverKey, serverIV, false /* not for reading */)
serverHash = hs.suite.mac(c.vers, serverMAC)
} else {
clientCipher = hs.suite.aead(clientKey, clientIV)
serverCipher = hs.suite.aead(serverKey, serverIV)
}
c.in.prepareCipherSpec(c.vers, clientCipher, clientHash)
c.out.prepareCipherSpec(c.vers, serverCipher, serverHash)
return nil
}
func (hs *serverHandshakeState) readFinished() error {
c := hs.c
c.readRecord(recordTypeChangeCipherSpec)
if err := c.in.error(); err != nil {
return err
}
if hs.hello.nextProtoNeg {
msg, err := c.readHandshake()
if err != nil {
return err
}
nextProto, ok := msg.(*nextProtoMsg)
if !ok {
c.sendAlert(alertUnexpectedMessage)
return unexpectedMessageError(nextProto, msg)
}
hs.finishedHash.Write(nextProto.marshal())
c.clientProtocol = nextProto.proto
}
msg, err := c.readHandshake()
if err != nil {
return err
}
clientFinished, ok := msg.(*finishedMsg)
if !ok {
c.sendAlert(alertUnexpectedMessage)
return unexpectedMessageError(clientFinished, msg)
}
verify := hs.finishedHash.clientSum(hs.masterSecret)
if len(verify) != len(clientFinished.verifyData) ||
subtle.ConstantTimeCompare(verify, clientFinished.verifyData) != 1 {
c.sendAlert(alertHandshakeFailure)
return errors.New("tls: client's Finished message is incorrect")
}
hs.finishedHash.Write(clientFinished.marshal())
return nil
}
func (hs *serverHandshakeState) sendSessionTicket() error {
if !hs.hello.ticketSupported {
return nil
}
c := hs.c
m := new(newSessionTicketMsg)
var err error
state := sessionState{
vers: c.vers,
cipherSuite: hs.suite.id,
masterSecret: hs.masterSecret,
certificates: hs.certsFromClient,
}
m.ticket, err = c.encryptTicket(&state)
if err != nil {
return err
}
hs.finishedHash.Write(m.marshal())
c.writeRecord(recordTypeHandshake, m.marshal())
return nil
}
func (hs *serverHandshakeState) sendFinished() error {
c := hs.c
c.writeRecord(recordTypeChangeCipherSpec, []byte{1})
finished := new(finishedMsg)
finished.verifyData = hs.finishedHash.serverSum(hs.masterSecret)
hs.finishedHash.Write(finished.marshal())
c.writeRecord(recordTypeHandshake, finished.marshal())
c.cipherSuite = hs.suite.id
return nil
}
// processCertsFromClient takes a chain of client certificates either from a
// Certificates message or from a sessionState and verifies them. It returns
// the public key of the leaf certificate.
func (hs *serverHandshakeState) processCertsFromClient(certificates [][]byte) (crypto.PublicKey, error) {
c := hs.c
hs.certsFromClient = certificates
certs := make([]*x509.Certificate, len(certificates))
var err error
for i, asn1Data := range certificates {
if certs[i], err = x509.ParseCertificate(asn1Data); err != nil {
c.sendAlert(alertBadCertificate)
return nil, errors.New("tls: failed to parse client certificate: " + err.Error())
}
if c.clientCRLPool != nil && c.clientCRLPool.CheckCertRevoked(certs[i]) {
c.sendAlert(alertCertificateRevoked)
return nil, fmt.Errorf("tls: revoked client certificate: %s %s", strings.ToUpper(certs[i].SerialNumber.Text(16)), certs[i].Subject.CommonName)
}
}
if c.clientAuth >= VerifyClientCertIfGiven && len(certs) > 0 {
opts := x509.VerifyOptions{
Roots: c.getClientCAs(),
CurrentTime: c.config.time(),
Intermediates: x509.NewCertPool(),
KeyUsages: []x509.ExtKeyUsage{x509.ExtKeyUsageClientAuth},
}
for _, cert := range certs[1:] {
opts.Intermediates.AddCert(cert)
}
chains, err := certs[0].Verify(opts)
if err != nil {
c.sendAlert(alertBadCertificate)
return nil, errors.New("tls: failed to verify client's certificate: " + err.Error())
}
ok := false
for _, ku := range certs[0].ExtKeyUsage {
if ku == x509.ExtKeyUsageClientAuth {
ok = true
break
}
}
if !ok {
c.sendAlert(alertHandshakeFailure)
return nil, errors.New("tls: client's certificate's extended key usage doesn't permit it to be used for client authentication")
}
c.verifiedChains = chains
}
if len(certs) > 0 {
var pub crypto.PublicKey
switch key := certs[0].PublicKey.(type) {
case *ecdsa.PublicKey, *rsa.PublicKey:
pub = key
default:
c.sendAlert(alertUnsupportedCertificate)
return nil, fmt.Errorf("tls: client's certificate contains an unsupported public key of type %T", certs[0].PublicKey)
}
c.peerCertificates = certs
return pub, nil
}
return nil, nil
}
// tryCipherSuite returns a cipherSuite with the given id if that cipher suite
// is acceptable to use.
func (c *Conn) tryCipherSuite(id uint16, supportedCipherSuites []uint16, version uint16,
ellipticOk, ecdsaOk, chachaOk bool, useRC4 uint8) (*cipherSuite, int) {
for i, supported := range supportedCipherSuites {
if id == supported {
var candidate *cipherSuite
for _, s := range cipherSuites {
if s.id == id {
candidate = s
break
}
}
if candidate == nil {
continue
}
// Don't select a ciphersuite which we can't
// support for this client.
if (candidate.flags&suiteECDHE != 0) && !ellipticOk {
continue
}
if (candidate.flags&suiteECDSA != 0) != ecdsaOk {
continue
}
if version < VersionTLS12 && candidate.flags&suiteTLS12 != 0 {
continue
}
if candidate.flags&suiteChacha20 != 0 && !chachaOk {
continue
}
if candidate.flags&suiteRC4 != 0 && useRC4 == disableRC4 {
continue
}
if candidate.flags&suiteRC4 == 0 && useRC4 == onlyRC4 {
continue
}
return candidate, i
}
}
return nil, 0
}
func IsEcdheCipherSuite(suite interface{}) bool {
if s, ok := suite.(*cipherSuite); ok {
return (s.flags & suiteECDHE) != 0
}
return false
}