libgo: Merge to master revision 19184.

[official-gcc.git] / libgo / go / crypto / tls / handshake_client.go

// 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/ecdsa"
        "crypto/rsa"
        "crypto/subtle"
        "crypto/x509"
        "encoding/asn1"
        "errors"
        "fmt"
        "io"
        "net"
        "strconv"
)

type clientHandshakeState struct {
        c            *Conn
        serverHello  *serverHelloMsg
        hello        *clientHelloMsg
        suite        *cipherSuite
        finishedHash finishedHash
        masterSecret []byte
        session      *ClientSessionState
}

func (c *Conn) clientHandshake() error {
        if c.config == nil {
                c.config = defaultConfig()
        }

        hello := &clientHelloMsg{
                vers:                c.config.maxVersion(),
                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,
                secureRenegotiation: true,
        }

        possibleCipherSuites := c.config.cipherSuites()
        hello.cipherSuites = make([]uint16, 0, len(possibleCipherSuites))

NextCipherSuite:
        for _, suiteId := range possibleCipherSuites {
                for _, suite := range cipherSuites {
                        if suite.id != suiteId {
                                continue
                        }
                        // Don't advertise TLS 1.2-only cipher suites unless
                        // we're attempting TLS 1.2.
                        if hello.vers < VersionTLS12 && suite.flags&suiteTLS12 != 0 {
                                continue
                        }
                        hello.cipherSuites = append(hello.cipherSuites, suiteId)
                        continue NextCipherSuite
                }
        }

        _, err := io.ReadFull(c.config.rand(), hello.random)
        if err != nil {
                c.sendAlert(alertInternalError)
                return errors.New("tls: short read from Rand: " + err.Error())
        }

        if hello.vers >= VersionTLS12 {
                hello.signatureAndHashes = supportedSKXSignatureAlgorithms
        }

        var session *ClientSessionState
        var cacheKey string
        sessionCache := c.config.ClientSessionCache
        if c.config.SessionTicketsDisabled {
                sessionCache = nil
        }

        if sessionCache != nil {
                hello.ticketSupported = true

                // Try to resume a previously negotiated TLS session, if
                // available.
                cacheKey = clientSessionCacheKey(c.conn.RemoteAddr(), c.config)
                candidateSession, ok := sessionCache.Get(cacheKey)
                if ok {
                        // Check that the ciphersuite/version used for the
                        // previous session are still valid.
                        cipherSuiteOk := false
                        for _, id := range hello.cipherSuites {
                                if id == candidateSession.cipherSuite {
                                        cipherSuiteOk = true
                                        break
                                }
                        }

                        versOk := candidateSession.vers >= c.config.minVersion() &&
                                candidateSession.vers <= c.config.maxVersion()
                        if versOk && cipherSuiteOk {
                                session = candidateSession
                        }
                }
        }

        if session != nil {
                hello.sessionTicket = session.sessionTicket
                // A random session ID is used to detect when the
                // server accepted the ticket and is resuming a session
                // (see RFC 5077).
                hello.sessionId = make([]byte, 16)
                if _, err := io.ReadFull(c.config.rand(), hello.sessionId); err != nil {
                        c.sendAlert(alertInternalError)
                        return errors.New("tls: short read from Rand: " + err.Error())
                }
        }

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

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

        vers, ok := c.config.mutualVersion(serverHello.vers)
        if !ok || vers < VersionTLS10 {
                // TLS 1.0 is the minimum version supported as a client.
                c.sendAlert(alertProtocolVersion)
                return fmt.Errorf("tls: server selected unsupported protocol version %x", serverHello.vers)
        }
        c.vers = vers
        c.haveVers = true

        suite := mutualCipherSuite(c.config.cipherSuites(), serverHello.cipherSuite)
        if suite == nil {
                c.sendAlert(alertHandshakeFailure)
                return fmt.Errorf("tls: server selected an unsupported cipher suite")
        }

        hs := &clientHandshakeState{
                c:            c,
                serverHello:  serverHello,
                hello:        hello,
                suite:        suite,
                finishedHash: newFinishedHash(c.vers),
                session:      session,
        }

        hs.finishedHash.Write(hs.hello.marshal())
        hs.finishedHash.Write(hs.serverHello.marshal())

        isResume, err := hs.processServerHello()
        if err != nil {
                return err
        }

        if isResume {
                if err := hs.establishKeys(); err != nil {
                        return err
                }
                if err := hs.readSessionTicket(); err != nil {
                        return err
                }
                if err := hs.readFinished(); err != nil {
                        return err
                }
                if err := hs.sendFinished(); err != nil {
                        return err
                }
        } else {
                if err := hs.doFullHandshake(); err != nil {
                        return err
                }
                if err := hs.establishKeys(); err != nil {
                        return err
                }
                if err := hs.sendFinished(); err != nil {
                        return err
                }
                if err := hs.readSessionTicket(); err != nil {
                        return err
                }
                if err := hs.readFinished(); err != nil {
                        return err
                }
        }

        if sessionCache != nil && hs.session != nil && session != hs.session {
                sessionCache.Put(cacheKey, hs.session)
        }

        c.didResume = isResume
        c.handshakeComplete = true
        c.cipherSuite = suite.id
        return nil
}

func (hs *clientHandshakeState) doFullHandshake() error {
        c := hs.c

        msg, err := c.readHandshake()
        if err != nil {
                return err
        }
        certMsg, ok := msg.(*certificateMsg)
        if !ok || len(certMsg.certificates) == 0 {
                c.sendAlert(alertUnexpectedMessage)
                return unexpectedMessageError(certMsg, msg)
        }
        hs.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("tls: 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
                }
        }

        switch certs[0].PublicKey.(type) {
        case *rsa.PublicKey, *ecdsa.PublicKey:
                break
        default:
                c.sendAlert(alertUnsupportedCertificate)
                return fmt.Errorf("tls: server's certificate contains an unsupported type of public key: %T", certs[0].PublicKey)
        }

        c.peerCertificates = certs

        if hs.serverHello.ocspStapling {
                msg, err = c.readHandshake()
                if err != nil {
                        return err
                }
                cs, ok := msg.(*certificateStatusMsg)
                if !ok {
                        c.sendAlert(alertUnexpectedMessage)
                        return unexpectedMessageError(cs, msg)
                }
                hs.finishedHash.Write(cs.marshal())

                if cs.statusType == statusTypeOCSP {
                        c.ocspResponse = cs.response
                }
        }

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

        keyAgreement := hs.suite.ka(c.vers)

        skx, ok := msg.(*serverKeyExchangeMsg)
        if ok {
                hs.finishedHash.Write(skx.marshal())
                err = keyAgreement.processServerKeyExchange(c.config, hs.hello, hs.serverHello, certs[0], skx)
                if err != nil {
                        c.sendAlert(alertUnexpectedMessage)
                        return err
                }

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

        var chainToSend *Certificate
        var certRequested bool
        certReq, ok := msg.(*certificateRequestMsg)
        if ok {
                certRequested = true

                // 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.

                hs.finishedHash.Write(certReq.marshal())

                var rsaAvail, ecdsaAvail bool
                for _, certType := range certReq.certificateTypes {
                        switch certType {
                        case certTypeRSASign:
                                rsaAvail = true
                        case certTypeECDSASign:
                                ecdsaAvail = true
                        }
                }

                // 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, chain := range c.config.Certificates {
                        if !rsaAvail && !ecdsaAvail {
                                continue
                        }

                        for j, cert := range chain.Certificate {
                                x509Cert := chain.Leaf
                                // parse the certificate if this isn't the leaf
                                // node, or if chain.Leaf was nil
                                if j != 0 || x509Cert == nil {
                                        if x509Cert, err = x509.ParseCertificate(cert); err != nil {
                                                c.sendAlert(alertInternalError)
                                                return errors.New("tls: failed to parse client certificate #" + strconv.Itoa(i) + ": " + err.Error())
                                        }
                                }

                                switch {
                                case rsaAvail && x509Cert.PublicKeyAlgorithm == x509.RSA:
                                case ecdsaAvail && x509Cert.PublicKeyAlgorithm == x509.ECDSA:
                                default:
                                        continue findCert
                                }

                                if len(certReq.certificateAuthorities) == 0 {
                                        // they gave us an empty list, so just take the
                                        // first RSA cert from c.config.Certificates
                                        chainToSend = &chain
                                        break findCert
                                }

                                for _, ca := range certReq.certificateAuthorities {
                                        if bytes.Equal(x509Cert.RawIssuer, ca) {
                                                chainToSend = &chain
                                                break findCert
                                        }
                                }
                        }
                }

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

        shd, ok := msg.(*serverHelloDoneMsg)
        if !ok {
                c.sendAlert(alertUnexpectedMessage)
                return unexpectedMessageError(shd, msg)
        }
        hs.finishedHash.Write(shd.marshal())

        // If the server requested a certificate then we have to send a
        // Certificate message, even if it's empty because we don't have a
        // certificate to send.
        if certRequested {
                certMsg = new(certificateMsg)
                if chainToSend != nil {
                        certMsg.certificates = chainToSend.Certificate
                }
                hs.finishedHash.Write(certMsg.marshal())
                c.writeRecord(recordTypeHandshake, certMsg.marshal())
        }

        preMasterSecret, ckx, err := keyAgreement.generateClientKeyExchange(c.config, hs.hello, certs[0])
        if err != nil {
                c.sendAlert(alertInternalError)
                return err
        }
        if ckx != nil {
                hs.finishedHash.Write(ckx.marshal())
                c.writeRecord(recordTypeHandshake, ckx.marshal())
        }

        if chainToSend != nil {
                var signed []byte
                certVerify := &certificateVerifyMsg{
                        hasSignatureAndHash: c.vers >= VersionTLS12,
                }

                switch key := c.config.Certificates[0].PrivateKey.(type) {
                case *ecdsa.PrivateKey:
                        digest, _, hashId := hs.finishedHash.hashForClientCertificate(signatureECDSA)
                        r, s, err := ecdsa.Sign(c.config.rand(), key, digest)
                        if err == nil {
                                signed, err = asn1.Marshal(ecdsaSignature{r, s})
                        }
                        certVerify.signatureAndHash.signature = signatureECDSA
                        certVerify.signatureAndHash.hash = hashId
                case *rsa.PrivateKey:
                        digest, hashFunc, hashId := hs.finishedHash.hashForClientCertificate(signatureRSA)
                        signed, err = rsa.SignPKCS1v15(c.config.rand(), key, hashFunc, digest)
                        certVerify.signatureAndHash.signature = signatureRSA
                        certVerify.signatureAndHash.hash = hashId
                default:
                        err = errors.New("unknown private key type")
                }
                if err != nil {
                        c.sendAlert(alertInternalError)
                        return errors.New("tls: failed to sign handshake with client certificate: " + err.Error())
                }
                certVerify.signature = signed

                hs.finishedHash.Write(certVerify.marshal())
                c.writeRecord(recordTypeHandshake, certVerify.marshal())
        }

        hs.masterSecret = masterFromPreMasterSecret(c.vers, preMasterSecret, hs.hello.random, hs.serverHello.random)
        return nil
}

func (hs *clientHandshakeState) establishKeys() error {
        c := hs.c

        clientMAC, serverMAC, clientKey, serverKey, clientIV, serverIV :=
                keysFromMasterSecret(c.vers, hs.masterSecret, hs.hello.random, hs.serverHello.random, hs.suite.macLen, hs.suite.keyLen, hs.suite.ivLen)
        var clientCipher, serverCipher interface{}
        var clientHash, serverHash macFunction
        if hs.suite.cipher != nil {
                clientCipher = hs.suite.cipher(clientKey, clientIV, false /* not for reading */)
                clientHash = hs.suite.mac(c.vers, clientMAC)
                serverCipher = hs.suite.cipher(serverKey, serverIV, true /* 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, serverCipher, serverHash)
        c.out.prepareCipherSpec(c.vers, clientCipher, clientHash)
        return nil
}

func (hs *clientHandshakeState) serverResumedSession() bool {
        // If the server responded with the same sessionId then it means the
        // sessionTicket is being used to resume a TLS session.
        return hs.session != nil && hs.hello.sessionId != nil &&
                bytes.Equal(hs.serverHello.sessionId, hs.hello.sessionId)
}

func (hs *clientHandshakeState) processServerHello() (bool, error) {
        c := hs.c

        if hs.serverHello.compressionMethod != compressionNone {
                c.sendAlert(alertUnexpectedMessage)
                return false, errors.New("tls: server selected unsupported compression format")
        }

        if !hs.hello.nextProtoNeg && hs.serverHello.nextProtoNeg {
                c.sendAlert(alertHandshakeFailure)
                return false, errors.New("server advertised unrequested NPN extension")
        }

        if hs.serverResumedSession() {
                // Restore masterSecret and peerCerts from previous state
                hs.masterSecret = hs.session.masterSecret
                c.peerCertificates = hs.session.serverCertificates
                return true, nil
        }
        return false, nil
}

func (hs *clientHandshakeState) readFinished() error {
        c := hs.c

        c.readRecord(recordTypeChangeCipherSpec)
        if err := c.error(); err != nil {
                return err
        }

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

        verify := hs.finishedHash.serverSum(hs.masterSecret)
        if len(verify) != len(serverFinished.verifyData) ||
                subtle.ConstantTimeCompare(verify, serverFinished.verifyData) != 1 {
                c.sendAlert(alertHandshakeFailure)
                return errors.New("tls: server's Finished message was incorrect")
        }
        hs.finishedHash.Write(serverFinished.marshal())
        return nil
}

func (hs *clientHandshakeState) readSessionTicket() error {
        if !hs.serverHello.ticketSupported {
                return nil
        }

        c := hs.c
        msg, err := c.readHandshake()
        if err != nil {
                return err
        }
        sessionTicketMsg, ok := msg.(*newSessionTicketMsg)
        if !ok {
                c.sendAlert(alertUnexpectedMessage)
                return unexpectedMessageError(sessionTicketMsg, msg)
        }
        hs.finishedHash.Write(sessionTicketMsg.marshal())

        hs.session = &ClientSessionState{
                sessionTicket:      sessionTicketMsg.ticket,
                vers:               c.vers,
                cipherSuite:        hs.suite.id,
                masterSecret:       hs.masterSecret,
                serverCertificates: c.peerCertificates,
        }

        return nil
}

func (hs *clientHandshakeState) sendFinished() error {
        c := hs.c

        c.writeRecord(recordTypeChangeCipherSpec, []byte{1})
        if hs.serverHello.nextProtoNeg {
                nextProto := new(nextProtoMsg)
                proto, fallback := mutualProtocol(c.config.NextProtos, hs.serverHello.nextProtos)
                nextProto.proto = proto
                c.clientProtocol = proto
                c.clientProtocolFallback = fallback

                hs.finishedHash.Write(nextProto.marshal())
                c.writeRecord(recordTypeHandshake, nextProto.marshal())
        }

        finished := new(finishedMsg)
        finished.verifyData = hs.finishedHash.clientSum(hs.masterSecret)
        hs.finishedHash.Write(finished.marshal())
        c.writeRecord(recordTypeHandshake, finished.marshal())
        return nil
}

// clientSessionCacheKey returns a key used to cache sessionTickets that could
// be used to resume previously negotiated TLS sessions with a server.
func clientSessionCacheKey(serverAddr net.Addr, config *Config) string {
        if len(config.ServerName) > 0 {
                return config.ServerName
        }
        return serverAddr.String()
}

// 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
}