Subversion Repositories openrisc

// 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 (
        "crypto"
        "crypto/rsa"
        "crypto/subtle"
        "crypto/x509"
        "errors"
        "io"
)

func (c *Conn) serverHandshake() error {
        config := c.config
        msg, err := c.readHandshake()
        if err != nil {
                return err
        }
        clientHello, ok := msg.(*clientHelloMsg)
        if !ok {
                return c.sendAlert(alertUnexpectedMessage)
        }
        vers, ok := mutualVersion(clientHello.vers)
        if !ok {
                return c.sendAlert(alertProtocolVersion)
        }
        c.vers = vers
        c.haveVers = true

        finishedHash := newFinishedHash(vers)
        finishedHash.Write(clientHello.marshal())

        hello := new(serverHelloMsg)

        supportedCurve := false
Curves:
        for _, curve := range clientHello.supportedCurves {
                switch curve {
                case curveP256, curveP384, curveP521:
                        supportedCurve = true
                        break Curves
                }
        }

        supportedPointFormat := false
        for _, pointFormat := range clientHello.supportedPoints {
                if pointFormat == pointFormatUncompressed {
                        supportedPointFormat = true
                        break
                }
        }

        ellipticOk := supportedCurve && supportedPointFormat

        var suite *cipherSuite
FindCipherSuite:
        for _, id := range clientHello.cipherSuites {
                for _, supported := range config.cipherSuites() {
                        if id == supported {
                                suite = nil
                                for _, s := range cipherSuites {
                                        if s.id == id {
                                                suite = s
                                                break
                                        }
                                }
                                if suite == nil {
                                        continue
                                }
                                // Don't select a ciphersuite which we can't
                                // support for this client.
                                if suite.elliptic && !ellipticOk {
                                        continue
                                }
                                break FindCipherSuite
                        }
                }
        }

        foundCompression := false
        // We only support null compression, so check that the client offered it.
        for _, compression := range clientHello.compressionMethods {
                if compression == compressionNone {
                        foundCompression = true
                        break
                }
        }

        if suite == nil || !foundCompression {
                return c.sendAlert(alertHandshakeFailure)
        }

        hello.vers = vers
        hello.cipherSuite = suite.id
        t := uint32(config.time().Unix())
        hello.random = make([]byte, 32)
        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(config.rand(), hello.random[4:])
        if err != nil {
                return c.sendAlert(alertInternalError)
        }
        hello.compressionMethod = compressionNone
        if clientHello.nextProtoNeg {
                hello.nextProtoNeg = true
                hello.nextProtos = config.NextProtos
        }
        if clientHello.ocspStapling && len(config.Certificates[0].OCSPStaple) > 0 {
                hello.ocspStapling = true
        }

        finishedHash.Write(hello.marshal())
        c.writeRecord(recordTypeHandshake, hello.marshal())

        if len(config.Certificates) == 0 {
                return c.sendAlert(alertInternalError)
        }

        certMsg := new(certificateMsg)
        if len(clientHello.serverName) > 0 {
                c.serverName = clientHello.serverName
                certMsg.certificates = config.getCertificateForName(clientHello.serverName).Certificate
        } else {
                certMsg.certificates = config.Certificates[0].Certificate
        }
        finishedHash.Write(certMsg.marshal())
        c.writeRecord(recordTypeHandshake, certMsg.marshal())

        if hello.ocspStapling {
                certStatus := new(certificateStatusMsg)
                certStatus.statusType = statusTypeOCSP
                certStatus.response = config.Certificates[0].OCSPStaple
                finishedHash.Write(certStatus.marshal())
                c.writeRecord(recordTypeHandshake, certStatus.marshal())
        }

        keyAgreement := suite.ka()
        skx, err := keyAgreement.generateServerKeyExchange(config, clientHello, hello)
        if err != nil {
                c.sendAlert(alertHandshakeFailure)
                return err
        }
        if skx != nil {
                finishedHash.Write(skx.marshal())
                c.writeRecord(recordTypeHandshake, skx.marshal())
        }

        if config.ClientAuth >= RequestClientCert {
                // Request a client certificate
                certReq := new(certificateRequestMsg)
                certReq.certificateTypes = []byte{certTypeRSASign}

                // 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 config.ClientCAs != nil {
                        certReq.certificateAuthorities = config.ClientCAs.Subjects()
                }
                finishedHash.Write(certReq.marshal())
                c.writeRecord(recordTypeHandshake, certReq.marshal())
        }

        helloDone := new(serverHelloDoneMsg)
        finishedHash.Write(helloDone.marshal())
        c.writeRecord(recordTypeHandshake, helloDone.marshal())

        var pub *rsa.PublicKey // public key for client auth, if any

        msg, err = c.readHandshake()
        if err != nil {
                return err
        }

        // If we requested a client certificate, then the client must send a
        // certificate message, even if it's empty.
        if config.ClientAuth >= RequestClientCert {
                if certMsg, ok = msg.(*certificateMsg); !ok {
                        return c.sendAlert(alertHandshakeFailure)
                }
                finishedHash.Write(certMsg.marshal())

                if len(certMsg.certificates) == 0 {
                        // The client didn't actually send a certificate
                        switch config.ClientAuth {
                        case RequireAnyClientCert, RequireAndVerifyClientCert:
                                c.sendAlert(alertBadCertificate)
                                return errors.New("tls: client didn't provide a certificate")
                        }
                }

                certs := make([]*x509.Certificate, len(certMsg.certificates))
                for i, asn1Data := range certMsg.certificates {
                        if certs[i], err = x509.ParseCertificate(asn1Data); err != nil {
                                c.sendAlert(alertBadCertificate)
                                return errors.New("tls: failed to parse client certificate: " + err.Error())
                        }
                }

                if c.config.ClientAuth >= VerifyClientCertIfGiven && len(certs) > 0 {
                        opts := x509.VerifyOptions{
                                Roots:         c.config.ClientCAs,
                                CurrentTime:   c.config.time(),
                                Intermediates: x509.NewCertPool(),
                        }

                        for i, cert := range certs {
                                if i == 0 {
                                        continue
                                }
                                opts.Intermediates.AddCert(cert)
                        }

                        chains, err := certs[0].Verify(opts)
                        if err != nil {
                                c.sendAlert(alertBadCertificate)
                                return 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 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 {
                        if pub, ok = certs[0].PublicKey.(*rsa.PublicKey); !ok {
                                return c.sendAlert(alertUnsupportedCertificate)
                        }
                        c.peerCertificates = certs
                }

                msg, err = c.readHandshake()
                if err != nil {
                        return err
                }
        }

        // Get client key exchange
        ckx, ok := msg.(*clientKeyExchangeMsg)
        if !ok {
                return c.sendAlert(alertUnexpectedMessage)
        }
        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 MD5SHA1 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 {
                        return c.sendAlert(alertUnexpectedMessage)
                }

                digest := make([]byte, 0, 36)
                digest = finishedHash.serverMD5.Sum(digest)
                digest = finishedHash.serverSHA1.Sum(digest)
                err = rsa.VerifyPKCS1v15(pub, crypto.MD5SHA1, digest, certVerify.signature)
                if err != nil {
                        c.sendAlert(alertBadCertificate)
                        return errors.New("could not validate signature of connection nonces: " + err.Error())
                }

                finishedHash.Write(certVerify.marshal())
        }

        preMasterSecret, err := keyAgreement.processClientKeyExchange(config, ckx, c.vers)
        if err != nil {
                c.sendAlert(alertHandshakeFailure)
                return err
        }

        masterSecret, clientMAC, serverMAC, clientKey, serverKey, clientIV, serverIV :=
                keysFromPreMasterSecret(c.vers, preMasterSecret, clientHello.random, hello.random, suite.macLen, suite.keyLen, suite.ivLen)

        clientCipher := suite.cipher(clientKey, clientIV, true /* for reading */ )
        clientHash := suite.mac(c.vers, clientMAC)
        c.in.prepareCipherSpec(c.vers, clientCipher, clientHash)
        c.readRecord(recordTypeChangeCipherSpec)
        if err := c.error(); err != nil {
                return err
        }

        if hello.nextProtoNeg {
                msg, err = c.readHandshake()
                if err != nil {
                        return err
                }
                nextProto, ok := msg.(*nextProtoMsg)
                if !ok {
                        return c.sendAlert(alertUnexpectedMessage)
                }
                finishedHash.Write(nextProto.marshal())
                c.clientProtocol = nextProto.proto
        }

        msg, err = c.readHandshake()
        if err != nil {
                return err
        }
        clientFinished, ok := msg.(*finishedMsg)
        if !ok {
                return c.sendAlert(alertUnexpectedMessage)
        }

        verify := finishedHash.clientSum(masterSecret)
        if len(verify) != len(clientFinished.verifyData) ||
                subtle.ConstantTimeCompare(verify, clientFinished.verifyData) != 1 {
                return c.sendAlert(alertHandshakeFailure)
        }

        finishedHash.Write(clientFinished.marshal())

        serverCipher := suite.cipher(serverKey, serverIV, false /* not for reading */ )
        serverHash := suite.mac(c.vers, serverMAC)
        c.out.prepareCipherSpec(c.vers, serverCipher, serverHash)
        c.writeRecord(recordTypeChangeCipherSpec, []byte{1})

        finished := new(finishedMsg)
        finished.verifyData = finishedHash.serverSum(masterSecret)
        c.writeRecord(recordTypeHandshake, finished.marshal())

        c.handshakeComplete = true
        c.cipherSuite = suite.id

        return nil
}