| // 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/ecdsa" |
| "crypto/ed25519" |
| "crypto/rsa" |
| "crypto/subtle" |
| "crypto/x509" |
| "errors" |
| "fmt" |
| "io" |
| "net" |
| "strconv" |
| "strings" |
| "sync/atomic" |
| "time" |
| ) |
| |
| type clientHandshakeState struct { |
| c *Conn |
| serverHello *serverHelloMsg |
| hello *clientHelloMsg |
| suite *cipherSuite |
| finishedHash finishedHash |
| masterSecret []byte |
| session *ClientSessionState |
| } |
| |
| func (c *Conn) makeClientHello() (*clientHelloMsg, ecdheParameters, error) { |
| config := c.config |
| if len(config.ServerName) == 0 && !config.InsecureSkipVerify { |
| return nil, nil, errors.New("tls: either ServerName or InsecureSkipVerify must be specified in the tls.Config") |
| } |
| |
| nextProtosLength := 0 |
| for _, proto := range config.NextProtos { |
| if l := len(proto); l == 0 || l > 255 { |
| return nil, nil, errors.New("tls: invalid NextProtos value") |
| } else { |
| nextProtosLength += 1 + l |
| } |
| } |
| if nextProtosLength > 0xffff { |
| return nil, nil, errors.New("tls: NextProtos values too large") |
| } |
| |
| supportedVersions := config.supportedVersions(true) |
| if len(supportedVersions) == 0 { |
| return nil, nil, errors.New("tls: no supported versions satisfy MinVersion and MaxVersion") |
| } |
| |
| clientHelloVersion := supportedVersions[0] |
| // The version at the beginning of the ClientHello was capped at TLS 1.2 |
| // for compatibility reasons. The supported_versions extension is used |
| // to negotiate versions now. See RFC 8446, Section 4.2.1. |
| if clientHelloVersion > VersionTLS12 { |
| clientHelloVersion = VersionTLS12 |
| } |
| |
| hello := &clientHelloMsg{ |
| vers: clientHelloVersion, |
| compressionMethods: []uint8{compressionNone}, |
| random: make([]byte, 32), |
| sessionId: make([]byte, 32), |
| ocspStapling: true, |
| scts: true, |
| serverName: hostnameInSNI(config.ServerName), |
| supportedCurves: config.curvePreferences(), |
| supportedPoints: []uint8{pointFormatUncompressed}, |
| nextProtoNeg: len(config.NextProtos) > 0, |
| secureRenegotiationSupported: true, |
| alpnProtocols: config.NextProtos, |
| supportedVersions: supportedVersions, |
| } |
| |
| if c.handshakes > 0 { |
| hello.secureRenegotiation = c.clientFinished[:] |
| } |
| |
| possibleCipherSuites := config.cipherSuites() |
| hello.cipherSuites = make([]uint16, 0, len(possibleCipherSuites)) |
| |
| 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 { |
| break |
| } |
| hello.cipherSuites = append(hello.cipherSuites, suiteId) |
| break |
| } |
| } |
| |
| _, err := io.ReadFull(config.rand(), hello.random) |
| if err != nil { |
| return nil, nil, errors.New("tls: short read from Rand: " + err.Error()) |
| } |
| |
| // A random session ID is used to detect when the server accepted a ticket |
| // and is resuming a session (see RFC 5077). In TLS 1.3, it's always set as |
| // a compatibility measure (see RFC 8446, Section 4.1.2). |
| if _, err := io.ReadFull(config.rand(), hello.sessionId); err != nil { |
| return nil, nil, errors.New("tls: short read from Rand: " + err.Error()) |
| } |
| |
| if hello.vers >= VersionTLS12 { |
| hello.supportedSignatureAlgorithms = supportedSignatureAlgorithms |
| } |
| |
| var params ecdheParameters |
| if hello.supportedVersions[0] == VersionTLS13 { |
| hello.cipherSuites = append(hello.cipherSuites, defaultCipherSuitesTLS13()...) |
| |
| curveID := config.curvePreferences()[0] |
| if _, ok := curveForCurveID(curveID); curveID != X25519 && !ok { |
| return nil, nil, errors.New("tls: CurvePreferences includes unsupported curve") |
| } |
| params, err = generateECDHEParameters(config.rand(), curveID) |
| if err != nil { |
| return nil, nil, err |
| } |
| hello.keyShares = []keyShare{{group: curveID, data: params.PublicKey()}} |
| } |
| |
| return hello, params, nil |
| } |
| |
| func (c *Conn) clientHandshake() (err error) { |
| if c.config == nil { |
| c.config = defaultConfig() |
| } |
| |
| // This may be a renegotiation handshake, in which case some fields |
| // need to be reset. |
| c.didResume = false |
| |
| hello, ecdheParams, err := c.makeClientHello() |
| if err != nil { |
| return err |
| } |
| |
| cacheKey, session, earlySecret, binderKey := c.loadSession(hello) |
| if cacheKey != "" && session != nil { |
| defer func() { |
| // If we got a handshake failure when resuming a session, throw away |
| // the session ticket. See RFC 5077, Section 3.2. |
| // |
| // RFC 8446 makes no mention of dropping tickets on failure, but it |
| // does require servers to abort on invalid binders, so we need to |
| // delete tickets to recover from a corrupted PSK. |
| if err != nil { |
| c.config.ClientSessionCache.Put(cacheKey, nil) |
| } |
| }() |
| } |
| |
| if _, err := c.writeRecord(recordTypeHandshake, hello.marshal()); err != nil { |
| return err |
| } |
| |
| msg, err := c.readHandshake() |
| if err != nil { |
| return err |
| } |
| |
| serverHello, ok := msg.(*serverHelloMsg) |
| if !ok { |
| c.sendAlert(alertUnexpectedMessage) |
| return unexpectedMessageError(serverHello, msg) |
| } |
| |
| if err := c.pickTLSVersion(serverHello); err != nil { |
| return err |
| } |
| |
| if c.vers == VersionTLS13 { |
| hs := &clientHandshakeStateTLS13{ |
| c: c, |
| serverHello: serverHello, |
| hello: hello, |
| ecdheParams: ecdheParams, |
| session: session, |
| earlySecret: earlySecret, |
| binderKey: binderKey, |
| } |
| |
| // In TLS 1.3, session tickets are delivered after the handshake. |
| return hs.handshake() |
| } |
| |
| hs := &clientHandshakeState{ |
| c: c, |
| serverHello: serverHello, |
| hello: hello, |
| session: session, |
| } |
| |
| if err := hs.handshake(); err != nil { |
| return err |
| } |
| |
| // If we had a successful handshake and hs.session is different from |
| // the one already cached - cache a new one. |
| if cacheKey != "" && hs.session != nil && session != hs.session { |
| c.config.ClientSessionCache.Put(cacheKey, hs.session) |
| } |
| |
| return nil |
| } |
| |
| func (c *Conn) loadSession(hello *clientHelloMsg) (cacheKey string, |
| session *ClientSessionState, earlySecret, binderKey []byte) { |
| if c.config.SessionTicketsDisabled || c.config.ClientSessionCache == nil { |
| return "", nil, nil, nil |
| } |
| |
| hello.ticketSupported = true |
| |
| if hello.supportedVersions[0] == VersionTLS13 { |
| // Require DHE on resumption as it guarantees forward secrecy against |
| // compromise of the session ticket key. See RFC 8446, Section 4.2.9. |
| hello.pskModes = []uint8{pskModeDHE} |
| } |
| |
| // Session resumption is not allowed if renegotiating because |
| // renegotiation is primarily used to allow a client to send a client |
| // certificate, which would be skipped if session resumption occurred. |
| if c.handshakes != 0 { |
| return "", nil, nil, nil |
| } |
| |
| // Try to resume a previously negotiated TLS session, if available. |
| cacheKey = clientSessionCacheKey(c.conn.RemoteAddr(), c.config) |
| session, ok := c.config.ClientSessionCache.Get(cacheKey) |
| if !ok || session == nil { |
| return cacheKey, nil, nil, nil |
| } |
| |
| // Check that version used for the previous session is still valid. |
| versOk := false |
| for _, v := range hello.supportedVersions { |
| if v == session.vers { |
| versOk = true |
| break |
| } |
| } |
| if !versOk { |
| return cacheKey, nil, nil, nil |
| } |
| |
| // Check that the cached server certificate is not expired, and that it's |
| // valid for the ServerName. This should be ensured by the cache key, but |
| // protect the application from a faulty ClientSessionCache implementation. |
| if !c.config.InsecureSkipVerify { |
| if len(session.verifiedChains) == 0 { |
| // The original connection had InsecureSkipVerify, while this doesn't. |
| return cacheKey, nil, nil, nil |
| } |
| serverCert := session.serverCertificates[0] |
| if c.config.time().After(serverCert.NotAfter) { |
| // Expired certificate, delete the entry. |
| c.config.ClientSessionCache.Put(cacheKey, nil) |
| return cacheKey, nil, nil, nil |
| } |
| if err := serverCert.VerifyHostname(c.config.ServerName); err != nil { |
| return cacheKey, nil, nil, nil |
| } |
| } |
| |
| if session.vers != VersionTLS13 { |
| // In TLS 1.2 the cipher suite must match the resumed session. Ensure we |
| // are still offering it. |
| if mutualCipherSuite(hello.cipherSuites, session.cipherSuite) == nil { |
| return cacheKey, nil, nil, nil |
| } |
| |
| hello.sessionTicket = session.sessionTicket |
| return |
| } |
| |
| // Check that the session ticket is not expired. |
| if c.config.time().After(session.useBy) { |
| c.config.ClientSessionCache.Put(cacheKey, nil) |
| return cacheKey, nil, nil, nil |
| } |
| |
| // In TLS 1.3 the KDF hash must match the resumed session. Ensure we |
| // offer at least one cipher suite with that hash. |
| cipherSuite := cipherSuiteTLS13ByID(session.cipherSuite) |
| if cipherSuite == nil { |
| return cacheKey, nil, nil, nil |
| } |
| cipherSuiteOk := false |
| for _, offeredID := range hello.cipherSuites { |
| offeredSuite := cipherSuiteTLS13ByID(offeredID) |
| if offeredSuite != nil && offeredSuite.hash == cipherSuite.hash { |
| cipherSuiteOk = true |
| break |
| } |
| } |
| if !cipherSuiteOk { |
| return cacheKey, nil, nil, nil |
| } |
| |
| // Set the pre_shared_key extension. See RFC 8446, Section 4.2.11.1. |
| ticketAge := uint32(c.config.time().Sub(session.receivedAt) / time.Millisecond) |
| identity := pskIdentity{ |
| label: session.sessionTicket, |
| obfuscatedTicketAge: ticketAge + session.ageAdd, |
| } |
| hello.pskIdentities = []pskIdentity{identity} |
| hello.pskBinders = [][]byte{make([]byte, cipherSuite.hash.Size())} |
| |
| // Compute the PSK binders. See RFC 8446, Section 4.2.11.2. |
| psk := cipherSuite.expandLabel(session.masterSecret, "resumption", |
| session.nonce, cipherSuite.hash.Size()) |
| earlySecret = cipherSuite.extract(psk, nil) |
| binderKey = cipherSuite.deriveSecret(earlySecret, resumptionBinderLabel, nil) |
| transcript := cipherSuite.hash.New() |
| transcript.Write(hello.marshalWithoutBinders()) |
| pskBinders := [][]byte{cipherSuite.finishedHash(binderKey, transcript)} |
| hello.updateBinders(pskBinders) |
| |
| return |
| } |
| |
| func (c *Conn) pickTLSVersion(serverHello *serverHelloMsg) error { |
| peerVersion := serverHello.vers |
| if serverHello.supportedVersion != 0 { |
| peerVersion = serverHello.supportedVersion |
| } |
| |
| vers, ok := c.config.mutualVersion(true, []uint16{peerVersion}) |
| if !ok { |
| c.sendAlert(alertProtocolVersion) |
| return fmt.Errorf("tls: server selected unsupported protocol version %x", peerVersion) |
| } |
| |
| c.vers = vers |
| c.haveVers = true |
| c.in.version = vers |
| c.out.version = vers |
| |
| return nil |
| } |
| |
| // Does the handshake, either a full one or resumes old session. Requires hs.c, |
| // hs.hello, hs.serverHello, and, optionally, hs.session to be set. |
| func (hs *clientHandshakeState) handshake() error { |
| c := hs.c |
| |
| isResume, err := hs.processServerHello() |
| if err != nil { |
| return err |
| } |
| |
| hs.finishedHash = newFinishedHash(c.vers, hs.suite) |
| |
| // No signatures of the handshake are needed in a resumption. |
| // Otherwise, in a full handshake, if we don't have any certificates |
| // configured then we will never send a CertificateVerify message and |
| // thus no signatures are needed in that case either. |
| if isResume || (len(c.config.Certificates) == 0 && c.config.GetClientCertificate == nil) { |
| hs.finishedHash.discardHandshakeBuffer() |
| } |
| |
| hs.finishedHash.Write(hs.hello.marshal()) |
| hs.finishedHash.Write(hs.serverHello.marshal()) |
| |
| c.buffering = true |
| if isResume { |
| if err := hs.establishKeys(); err != nil { |
| return err |
| } |
| if err := hs.readSessionTicket(); err != nil { |
| return err |
| } |
| if err := hs.readFinished(c.serverFinished[:]); err != nil { |
| return err |
| } |
| c.clientFinishedIsFirst = false |
| if err := hs.sendFinished(c.clientFinished[:]); err != nil { |
| return err |
| } |
| if _, err := c.flush(); 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(c.clientFinished[:]); err != nil { |
| return err |
| } |
| if _, err := c.flush(); err != nil { |
| return err |
| } |
| c.clientFinishedIsFirst = true |
| if err := hs.readSessionTicket(); err != nil { |
| return err |
| } |
| if err := hs.readFinished(c.serverFinished[:]); err != nil { |
| return err |
| } |
| } |
| |
| c.ekm = ekmFromMasterSecret(c.vers, hs.suite, hs.masterSecret, hs.hello.random, hs.serverHello.random) |
| c.didResume = isResume |
| atomic.StoreUint32(&c.handshakeStatus, 1) |
| |
| return nil |
| } |
| |
| func (hs *clientHandshakeState) pickCipherSuite() error { |
| if hs.suite = mutualCipherSuite(hs.hello.cipherSuites, hs.serverHello.cipherSuite); hs.suite == nil { |
| hs.c.sendAlert(alertHandshakeFailure) |
| return errors.New("tls: server chose an unconfigured cipher suite") |
| } |
| |
| hs.c.cipherSuite = hs.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()) |
| |
| if c.handshakes == 0 { |
| // If this is the first handshake on a connection, process and |
| // (optionally) verify the server's certificates. |
| if err := c.verifyServerCertificate(certMsg.certificates); err != nil { |
| return err |
| } |
| } else { |
| // This is a renegotiation handshake. We require that the |
| // server's identity (i.e. leaf certificate) is unchanged and |
| // thus any previous trust decision is still valid. |
| // |
| // See https://mitls.org/pages/attacks/3SHAKE for the |
| // motivation behind this requirement. |
| if !bytes.Equal(c.peerCertificates[0].Raw, certMsg.certificates[0]) { |
| c.sendAlert(alertBadCertificate) |
| return errors.New("tls: server's identity changed during renegotiation") |
| } |
| } |
| |
| msg, err = c.readHandshake() |
| if err != nil { |
| return err |
| } |
| |
| cs, ok := msg.(*certificateStatusMsg) |
| if ok { |
| // RFC4366 on Certificate Status Request: |
| // The server MAY return a "certificate_status" message. |
| |
| if !hs.serverHello.ocspStapling { |
| // If a server returns a "CertificateStatus" message, then the |
| // server MUST have included an extension of type "status_request" |
| // with empty "extension_data" in the extended server hello. |
| |
| c.sendAlert(alertUnexpectedMessage) |
| return errors.New("tls: received unexpected CertificateStatus message") |
| } |
| hs.finishedHash.Write(cs.marshal()) |
| |
| 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, c.peerCertificates[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 |
| hs.finishedHash.Write(certReq.marshal()) |
| |
| cri := certificateRequestInfoFromMsg(certReq) |
| if chainToSend, err = c.getClientCertificate(cri); err != nil { |
| c.sendAlert(alertInternalError) |
| return err |
| } |
| |
| 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) |
| certMsg.certificates = chainToSend.Certificate |
| hs.finishedHash.Write(certMsg.marshal()) |
| if _, err := c.writeRecord(recordTypeHandshake, certMsg.marshal()); err != nil { |
| return err |
| } |
| } |
| |
| preMasterSecret, ckx, err := keyAgreement.generateClientKeyExchange(c.config, hs.hello, c.peerCertificates[0]) |
| if err != nil { |
| c.sendAlert(alertInternalError) |
| return err |
| } |
| if ckx != nil { |
| hs.finishedHash.Write(ckx.marshal()) |
| if _, err := c.writeRecord(recordTypeHandshake, ckx.marshal()); err != nil { |
| return err |
| } |
| } |
| |
| if chainToSend != nil && len(chainToSend.Certificate) > 0 { |
| certVerify := &certificateVerifyMsg{ |
| hasSignatureAlgorithm: c.vers >= VersionTLS12, |
| } |
| |
| key, ok := chainToSend.PrivateKey.(crypto.Signer) |
| if !ok { |
| c.sendAlert(alertInternalError) |
| return fmt.Errorf("tls: client certificate private key of type %T does not implement crypto.Signer", chainToSend.PrivateKey) |
| } |
| |
| signatureAlgorithm, sigType, hashFunc, err := pickSignatureAlgorithm(key.Public(), certReq.supportedSignatureAlgorithms, supportedSignatureAlgorithmsTLS12, c.vers) |
| if err != nil { |
| c.sendAlert(alertInternalError) |
| return err |
| } |
| // SignatureAndHashAlgorithm was introduced in TLS 1.2. |
| if certVerify.hasSignatureAlgorithm { |
| certVerify.signatureAlgorithm = signatureAlgorithm |
| } |
| signed, err := hs.finishedHash.hashForClientCertificate(sigType, hashFunc, hs.masterSecret) |
| if err != nil { |
| c.sendAlert(alertInternalError) |
| return err |
| } |
| signOpts := crypto.SignerOpts(hashFunc) |
| if sigType == signatureRSAPSS { |
| signOpts = &rsa.PSSOptions{SaltLength: rsa.PSSSaltLengthEqualsHash, Hash: hashFunc} |
| } |
| certVerify.signature, err = key.Sign(c.config.rand(), signed, signOpts) |
| if err != nil { |
| c.sendAlert(alertInternalError) |
| return err |
| } |
| |
| hs.finishedHash.Write(certVerify.marshal()) |
| if _, err := c.writeRecord(recordTypeHandshake, certVerify.marshal()); err != nil { |
| return err |
| } |
| } |
| |
| hs.masterSecret = masterFromPreMasterSecret(c.vers, hs.suite, preMasterSecret, hs.hello.random, hs.serverHello.random) |
| if err := c.config.writeKeyLog(keyLogLabelTLS12, hs.hello.random, hs.masterSecret); err != nil { |
| c.sendAlert(alertInternalError) |
| return errors.New("tls: failed to write to key log: " + err.Error()) |
| } |
| |
| hs.finishedHash.discardHandshakeBuffer() |
| |
| return nil |
| } |
| |
| func (hs *clientHandshakeState) establishKeys() error { |
| c := hs.c |
| |
| clientMAC, serverMAC, clientKey, serverKey, clientIV, serverIV := |
| keysFromMasterSecret(c.vers, hs.suite, 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 err := hs.pickCipherSuite(); err != nil { |
| return false, err |
| } |
| |
| if hs.serverHello.compressionMethod != compressionNone { |
| c.sendAlert(alertUnexpectedMessage) |
| return false, errors.New("tls: server selected unsupported compression format") |
| } |
| |
| if c.handshakes == 0 && hs.serverHello.secureRenegotiationSupported { |
| c.secureRenegotiation = true |
| if len(hs.serverHello.secureRenegotiation) != 0 { |
| c.sendAlert(alertHandshakeFailure) |
| return false, errors.New("tls: initial handshake had non-empty renegotiation extension") |
| } |
| } |
| |
| if c.handshakes > 0 && c.secureRenegotiation { |
| var expectedSecureRenegotiation [24]byte |
| copy(expectedSecureRenegotiation[:], c.clientFinished[:]) |
| copy(expectedSecureRenegotiation[12:], c.serverFinished[:]) |
| if !bytes.Equal(hs.serverHello.secureRenegotiation, expectedSecureRenegotiation[:]) { |
| c.sendAlert(alertHandshakeFailure) |
| return false, errors.New("tls: incorrect renegotiation extension contents") |
| } |
| } |
| |
| clientDidNPN := hs.hello.nextProtoNeg |
| clientDidALPN := len(hs.hello.alpnProtocols) > 0 |
| serverHasNPN := hs.serverHello.nextProtoNeg |
| serverHasALPN := len(hs.serverHello.alpnProtocol) > 0 |
| |
| if !clientDidNPN && serverHasNPN { |
| c.sendAlert(alertHandshakeFailure) |
| return false, errors.New("tls: server advertised unrequested NPN extension") |
| } |
| |
| if !clientDidALPN && serverHasALPN { |
| c.sendAlert(alertHandshakeFailure) |
| return false, errors.New("tls: server advertised unrequested ALPN extension") |
| } |
| |
| if serverHasNPN && serverHasALPN { |
| c.sendAlert(alertHandshakeFailure) |
| return false, errors.New("tls: server advertised both NPN and ALPN extensions") |
| } |
| |
| if serverHasALPN { |
| c.clientProtocol = hs.serverHello.alpnProtocol |
| c.clientProtocolFallback = false |
| } |
| c.scts = hs.serverHello.scts |
| |
| if !hs.serverResumedSession() { |
| return false, nil |
| } |
| |
| if hs.session.vers != c.vers { |
| c.sendAlert(alertHandshakeFailure) |
| return false, errors.New("tls: server resumed a session with a different version") |
| } |
| |
| if hs.session.cipherSuite != hs.suite.id { |
| c.sendAlert(alertHandshakeFailure) |
| return false, errors.New("tls: server resumed a session with a different cipher suite") |
| } |
| |
| // Restore masterSecret and peerCerts from previous state |
| hs.masterSecret = hs.session.masterSecret |
| c.peerCertificates = hs.session.serverCertificates |
| c.verifiedChains = hs.session.verifiedChains |
| return true, nil |
| } |
| |
| func (hs *clientHandshakeState) readFinished(out []byte) error { |
| c := hs.c |
| |
| if err := c.readChangeCipherSpec(); 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()) |
| copy(out, verify) |
| 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, |
| verifiedChains: c.verifiedChains, |
| receivedAt: c.config.time(), |
| } |
| |
| return nil |
| } |
| |
| func (hs *clientHandshakeState) sendFinished(out []byte) error { |
| c := hs.c |
| |
| if _, err := c.writeRecord(recordTypeChangeCipherSpec, []byte{1}); err != nil { |
| return err |
| } |
| 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()) |
| if _, err := c.writeRecord(recordTypeHandshake, nextProto.marshal()); err != nil { |
| return err |
| } |
| } |
| |
| finished := new(finishedMsg) |
| finished.verifyData = hs.finishedHash.clientSum(hs.masterSecret) |
| hs.finishedHash.Write(finished.marshal()) |
| if _, err := c.writeRecord(recordTypeHandshake, finished.marshal()); err != nil { |
| return err |
| } |
| copy(out, finished.verifyData) |
| return nil |
| } |
| |
| // verifyServerCertificate parses and verifies the provided chain, setting |
| // c.verifiedChains and c.peerCertificates or sending the appropriate alert. |
| func (c *Conn) verifyServerCertificate(certificates [][]byte) error { |
| certs := make([]*x509.Certificate, len(certificates)) |
| for i, asn1Data := range 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 _, cert := range certs[1:] { |
| opts.Intermediates.AddCert(cert) |
| } |
| var err error |
| c.verifiedChains, err = certs[0].Verify(opts) |
| if err != nil { |
| c.sendAlert(alertBadCertificate) |
| return err |
| } |
| } |
| |
| if c.config.VerifyPeerCertificate != nil { |
| if err := c.config.VerifyPeerCertificate(certificates, c.verifiedChains); err != nil { |
| c.sendAlert(alertBadCertificate) |
| return err |
| } |
| } |
| |
| switch certs[0].PublicKey.(type) { |
| case *rsa.PublicKey, *ecdsa.PublicKey, ed25519.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 |
| |
| return nil |
| } |
| |
| // tls11SignatureSchemes contains the signature schemes that we synthesise for |
| // a TLS <= 1.1 connection, based on the supported certificate types. |
| var ( |
| tls11SignatureSchemes = []SignatureScheme{ECDSAWithP256AndSHA256, ECDSAWithP384AndSHA384, ECDSAWithP521AndSHA512, PKCS1WithSHA256, PKCS1WithSHA384, PKCS1WithSHA512, PKCS1WithSHA1} |
| tls11SignatureSchemesECDSA = tls11SignatureSchemes[:3] |
| tls11SignatureSchemesRSA = tls11SignatureSchemes[3:] |
| ) |
| |
| // certificateRequestInfoFromMsg generates a CertificateRequestInfo from a TLS |
| // <= 1.2 CertificateRequest, making an effort to fill in missing information. |
| func certificateRequestInfoFromMsg(certReq *certificateRequestMsg) *CertificateRequestInfo { |
| var rsaAvail, ecAvail bool |
| for _, certType := range certReq.certificateTypes { |
| switch certType { |
| case certTypeRSASign: |
| rsaAvail = true |
| case certTypeECDSASign: |
| ecAvail = true |
| } |
| } |
| |
| cri := &CertificateRequestInfo{ |
| AcceptableCAs: certReq.certificateAuthorities, |
| } |
| |
| if !certReq.hasSignatureAlgorithm { |
| // Prior to TLS 1.2, the signature schemes were not |
| // included in the certificate request message. In this |
| // case we use a plausible list based on the acceptable |
| // certificate types. |
| switch { |
| case rsaAvail && ecAvail: |
| cri.SignatureSchemes = tls11SignatureSchemes |
| case rsaAvail: |
| cri.SignatureSchemes = tls11SignatureSchemesRSA |
| case ecAvail: |
| cri.SignatureSchemes = tls11SignatureSchemesECDSA |
| } |
| return cri |
| } |
| |
| // Filter the signature schemes based on the certificate types. |
| // See RFC 5246, Section 7.4.4 (where it calls this "somewhat complicated"). |
| cri.SignatureSchemes = make([]SignatureScheme, 0, len(certReq.supportedSignatureAlgorithms)) |
| for _, sigScheme := range certReq.supportedSignatureAlgorithms { |
| switch signatureFromSignatureScheme(sigScheme) { |
| case signatureECDSA, signatureEd25519: |
| if ecAvail { |
| cri.SignatureSchemes = append(cri.SignatureSchemes, sigScheme) |
| } |
| case signatureRSAPSS, signaturePKCS1v15: |
| if rsaAvail { |
| cri.SignatureSchemes = append(cri.SignatureSchemes, sigScheme) |
| } |
| } |
| } |
| |
| return cri |
| } |
| |
| func (c *Conn) getClientCertificate(cri *CertificateRequestInfo) (*Certificate, error) { |
| if c.config.GetClientCertificate != nil { |
| return c.config.GetClientCertificate(cri) |
| } |
| |
| // We need to search our list of client certs for one |
| // where SignatureAlgorithm is acceptable to the server and the |
| // Issuer is in AcceptableCAs. |
| for i, chain := range c.config.Certificates { |
| sigOK := false |
| for _, alg := range signatureSchemesForCertificate(c.vers, &chain) { |
| if isSupportedSignatureAlgorithm(alg, cri.SignatureSchemes) { |
| sigOK = true |
| break |
| } |
| } |
| if !sigOK { |
| continue |
| } |
| |
| if len(cri.AcceptableCAs) == 0 { |
| return &chain, nil |
| } |
| |
| 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 { |
| var err error |
| if x509Cert, err = x509.ParseCertificate(cert); err != nil { |
| c.sendAlert(alertInternalError) |
| return nil, errors.New("tls: failed to parse configured certificate chain #" + strconv.Itoa(i) + ": " + err.Error()) |
| } |
| } |
| |
| for _, ca := range cri.AcceptableCAs { |
| if bytes.Equal(x509Cert.RawIssuer, ca) { |
| return &chain, nil |
| } |
| } |
| } |
| } |
| |
| // No acceptable certificate found. Don't send a certificate. |
| return new(Certificate), 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 or ALPN protocol |
| // given list of possible protocols and a list of the preference order. The |
| // first list must not be empty. It returns the resulting protocol and flag |
| // indicating if the fallback case was reached. |
| func mutualProtocol(protos, preferenceProtos []string) (string, bool) { |
| for _, s := range preferenceProtos { |
| for _, c := range protos { |
| if s == c { |
| return s, false |
| } |
| } |
| } |
| |
| return protos[0], true |
| } |
| |
| // hostnameInSNI converts name into an approriate hostname for SNI. |
| // Literal IP addresses and absolute FQDNs are not permitted as SNI values. |
| // See RFC 6066, Section 3. |
| func hostnameInSNI(name string) string { |
| host := name |
| if len(host) > 0 && host[0] == '[' && host[len(host)-1] == ']' { |
| host = host[1 : len(host)-1] |
| } |
| if i := strings.LastIndex(host, "%"); i > 0 { |
| host = host[:i] |
| } |
| if net.ParseIP(host) != nil { |
| return "" |
| } |
| for len(name) > 0 && name[len(name)-1] == '.' { |
| name = name[:len(name)-1] |
| } |
| return name |
| } |