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747 |
jeremybenn |
// Copyright 2009 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package tls
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import (
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"bytes"
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"crypto"
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"crypto/rsa"
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"crypto/subtle"
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"crypto/x509"
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"errors"
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"io"
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"strconv"
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)
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func (c *Conn) clientHandshake() error {
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finishedHash := newFinishedHash(versionTLS10)
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if c.config == nil {
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c.config = defaultConfig()
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}
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hello := &clientHelloMsg{
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vers: maxVersion,
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cipherSuites: c.config.cipherSuites(),
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compressionMethods: []uint8{compressionNone},
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random: make([]byte, 32),
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ocspStapling: true,
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serverName: c.config.ServerName,
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supportedCurves: []uint16{curveP256, curveP384, curveP521},
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supportedPoints: []uint8{pointFormatUncompressed},
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nextProtoNeg: len(c.config.NextProtos) > 0,
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}
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t := uint32(c.config.time().Unix())
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hello.random[0] = byte(t >> 24)
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hello.random[1] = byte(t >> 16)
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hello.random[2] = byte(t >> 8)
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hello.random[3] = byte(t)
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_, err := io.ReadFull(c.config.rand(), hello.random[4:])
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if err != nil {
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c.sendAlert(alertInternalError)
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return errors.New("short read from Rand")
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}
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finishedHash.Write(hello.marshal())
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c.writeRecord(recordTypeHandshake, hello.marshal())
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msg, err := c.readHandshake()
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if err != nil {
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return err
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}
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serverHello, ok := msg.(*serverHelloMsg)
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if !ok {
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return c.sendAlert(alertUnexpectedMessage)
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}
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finishedHash.Write(serverHello.marshal())
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vers, ok := mutualVersion(serverHello.vers)
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if !ok || vers < versionTLS10 {
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// TLS 1.0 is the minimum version supported as a client.
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return c.sendAlert(alertProtocolVersion)
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}
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c.vers = vers
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c.haveVers = true
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if serverHello.compressionMethod != compressionNone {
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return c.sendAlert(alertUnexpectedMessage)
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}
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if !hello.nextProtoNeg && serverHello.nextProtoNeg {
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c.sendAlert(alertHandshakeFailure)
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return errors.New("server advertised unrequested NPN")
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}
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suite := mutualCipherSuite(c.config.cipherSuites(), serverHello.cipherSuite)
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if suite == nil {
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return c.sendAlert(alertHandshakeFailure)
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}
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msg, err = c.readHandshake()
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if err != nil {
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return err
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}
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certMsg, ok := msg.(*certificateMsg)
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if !ok || len(certMsg.certificates) == 0 {
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return c.sendAlert(alertUnexpectedMessage)
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}
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finishedHash.Write(certMsg.marshal())
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certs := make([]*x509.Certificate, len(certMsg.certificates))
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for i, asn1Data := range certMsg.certificates {
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cert, err := x509.ParseCertificate(asn1Data)
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if err != nil {
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c.sendAlert(alertBadCertificate)
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return errors.New("failed to parse certificate from server: " + err.Error())
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}
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certs[i] = cert
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}
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if !c.config.InsecureSkipVerify {
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opts := x509.VerifyOptions{
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Roots: c.config.rootCAs(),
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CurrentTime: c.config.time(),
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DNSName: c.config.ServerName,
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Intermediates: x509.NewCertPool(),
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}
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for i, cert := range certs {
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if i == 0 {
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continue
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}
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opts.Intermediates.AddCert(cert)
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}
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c.verifiedChains, err = certs[0].Verify(opts)
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if err != nil {
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c.sendAlert(alertBadCertificate)
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return err
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}
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}
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if _, ok := certs[0].PublicKey.(*rsa.PublicKey); !ok {
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return c.sendAlert(alertUnsupportedCertificate)
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}
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c.peerCertificates = certs
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if serverHello.ocspStapling {
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msg, err = c.readHandshake()
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if err != nil {
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return err
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}
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cs, ok := msg.(*certificateStatusMsg)
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if !ok {
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return c.sendAlert(alertUnexpectedMessage)
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}
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finishedHash.Write(cs.marshal())
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if cs.statusType == statusTypeOCSP {
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c.ocspResponse = cs.response
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}
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}
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msg, err = c.readHandshake()
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if err != nil {
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return err
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}
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keyAgreement := suite.ka()
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skx, ok := msg.(*serverKeyExchangeMsg)
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if ok {
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finishedHash.Write(skx.marshal())
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err = keyAgreement.processServerKeyExchange(c.config, hello, serverHello, certs[0], skx)
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if err != nil {
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c.sendAlert(alertUnexpectedMessage)
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return err
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}
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msg, err = c.readHandshake()
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if err != nil {
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return err
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}
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}
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var certToSend *Certificate
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certReq, ok := msg.(*certificateRequestMsg)
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if ok {
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// RFC 4346 on the certificateAuthorities field:
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// A list of the distinguished names of acceptable certificate
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// authorities. These distinguished names may specify a desired
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// distinguished name for a root CA or for a subordinate CA;
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// thus, this message can be used to describe both known roots
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// and a desired authorization space. If the
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// certificate_authorities list is empty then the client MAY
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// send any certificate of the appropriate
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// ClientCertificateType, unless there is some external
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// arrangement to the contrary.
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finishedHash.Write(certReq.marshal())
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// For now, we only know how to sign challenges with RSA
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rsaAvail := false
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for _, certType := range certReq.certificateTypes {
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if certType == certTypeRSASign {
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rsaAvail = true
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break
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}
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}
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// We need to search our list of client certs for one
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// where SignatureAlgorithm is RSA and the Issuer is in
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// certReq.certificateAuthorities
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findCert:
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for i, cert := range c.config.Certificates {
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if !rsaAvail {
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continue
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}
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leaf := cert.Leaf
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if leaf == nil {
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if leaf, err = x509.ParseCertificate(cert.Certificate[0]); err != nil {
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c.sendAlert(alertInternalError)
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return errors.New("tls: failed to parse client certificate #" + strconv.Itoa(i) + ": " + err.Error())
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}
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}
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if leaf.PublicKeyAlgorithm != x509.RSA {
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continue
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}
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if len(certReq.certificateAuthorities) == 0 {
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// they gave us an empty list, so just take the
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// first RSA cert from c.config.Certificates
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certToSend = &cert
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break
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}
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for _, ca := range certReq.certificateAuthorities {
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if bytes.Equal(leaf.RawIssuer, ca) {
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certToSend = &cert
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break findCert
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}
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}
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}
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msg, err = c.readHandshake()
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if err != nil {
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return err
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}
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}
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shd, ok := msg.(*serverHelloDoneMsg)
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if !ok {
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return c.sendAlert(alertUnexpectedMessage)
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}
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finishedHash.Write(shd.marshal())
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if certToSend != nil {
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certMsg = new(certificateMsg)
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certMsg.certificates = certToSend.Certificate
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finishedHash.Write(certMsg.marshal())
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c.writeRecord(recordTypeHandshake, certMsg.marshal())
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}
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preMasterSecret, ckx, err := keyAgreement.generateClientKeyExchange(c.config, hello, certs[0])
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if err != nil {
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c.sendAlert(alertInternalError)
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return err
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}
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if ckx != nil {
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finishedHash.Write(ckx.marshal())
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c.writeRecord(recordTypeHandshake, ckx.marshal())
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}
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if certToSend != nil {
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certVerify := new(certificateVerifyMsg)
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digest := make([]byte, 0, 36)
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digest = finishedHash.serverMD5.Sum(digest)
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digest = finishedHash.serverSHA1.Sum(digest)
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signed, err := rsa.SignPKCS1v15(c.config.rand(), c.config.Certificates[0].PrivateKey.(*rsa.PrivateKey), crypto.MD5SHA1, digest)
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if err != nil {
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return c.sendAlert(alertInternalError)
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}
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certVerify.signature = signed
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finishedHash.Write(certVerify.marshal())
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c.writeRecord(recordTypeHandshake, certVerify.marshal())
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}
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masterSecret, clientMAC, serverMAC, clientKey, serverKey, clientIV, serverIV :=
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keysFromPreMasterSecret(c.vers, preMasterSecret, hello.random, serverHello.random, suite.macLen, suite.keyLen, suite.ivLen)
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clientCipher := suite.cipher(clientKey, clientIV, false /* not for reading */ )
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clientHash := suite.mac(c.vers, clientMAC)
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c.out.prepareCipherSpec(c.vers, clientCipher, clientHash)
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c.writeRecord(recordTypeChangeCipherSpec, []byte{1})
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if serverHello.nextProtoNeg {
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nextProto := new(nextProtoMsg)
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proto, fallback := mutualProtocol(c.config.NextProtos, serverHello.nextProtos)
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nextProto.proto = proto
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c.clientProtocol = proto
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c.clientProtocolFallback = fallback
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finishedHash.Write(nextProto.marshal())
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c.writeRecord(recordTypeHandshake, nextProto.marshal())
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}
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finished := new(finishedMsg)
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finished.verifyData = finishedHash.clientSum(masterSecret)
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finishedHash.Write(finished.marshal())
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c.writeRecord(recordTypeHandshake, finished.marshal())
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serverCipher := suite.cipher(serverKey, serverIV, true /* for reading */ )
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serverHash := suite.mac(c.vers, serverMAC)
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c.in.prepareCipherSpec(c.vers, serverCipher, serverHash)
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c.readRecord(recordTypeChangeCipherSpec)
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if c.err != nil {
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return c.err
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}
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| 304 |
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| 305 |
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msg, err = c.readHandshake()
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| 306 |
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if err != nil {
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return err
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| 308 |
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}
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| 309 |
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serverFinished, ok := msg.(*finishedMsg)
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if !ok {
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return c.sendAlert(alertUnexpectedMessage)
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| 312 |
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}
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| 314 |
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verify := finishedHash.serverSum(masterSecret)
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if len(verify) != len(serverFinished.verifyData) ||
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subtle.ConstantTimeCompare(verify, serverFinished.verifyData) != 1 {
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| 317 |
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return c.sendAlert(alertHandshakeFailure)
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| 318 |
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}
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| 319 |
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| 320 |
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c.handshakeComplete = true
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c.cipherSuite = suite.id
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| 322 |
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return nil
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| 323 |
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}
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| 324 |
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| 325 |
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// mutualProtocol finds the mutual Next Protocol Negotiation protocol given the
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| 326 |
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// set of client and server supported protocols. The set of client supported
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| 327 |
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// protocols must not be empty. It returns the resulting protocol and flag
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| 328 |
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// indicating if the fallback case was reached.
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func mutualProtocol(clientProtos, serverProtos []string) (string, bool) {
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| 330 |
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for _, s := range serverProtos {
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for _, c := range clientProtos {
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| 332 |
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if s == c {
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return s, false
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| 334 |
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}
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}
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| 336 |
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}
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| 337 |
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return clientProtos[0], true
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| 339 |
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}
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