github.com/gidoBOSSftw5731/go/src@v0.0.0-20210226122457-d24b0edbf019/crypto/tls/handshake_client.go (about) 1 // Copyright 2009 The Go Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style 3 // license that can be found in the LICENSE file. 4 5 package tls 6 7 import ( 8 "bytes" 9 "crypto" 10 "crypto/ecdsa" 11 "crypto/ed25519" 12 "crypto/rsa" 13 "crypto/subtle" 14 "crypto/x509" 15 "errors" 16 "fmt" 17 "hash" 18 "io" 19 "net" 20 "strings" 21 "sync/atomic" 22 "time" 23 ) 24 25 type clientHandshakeState struct { 26 c *Conn 27 serverHello *serverHelloMsg 28 hello *clientHelloMsg 29 suite *cipherSuite 30 finishedHash finishedHash 31 masterSecret []byte 32 session *ClientSessionState 33 } 34 35 func (c *Conn) makeClientHello() (*clientHelloMsg, ecdheParameters, error) { 36 config := c.config 37 if len(config.ServerName) == 0 && !config.InsecureSkipVerify { 38 return nil, nil, errors.New("tls: either ServerName or InsecureSkipVerify must be specified in the tls.Config") 39 } 40 41 nextProtosLength := 0 42 for _, proto := range config.NextProtos { 43 if l := len(proto); l == 0 || l > 255 { 44 return nil, nil, errors.New("tls: invalid NextProtos value") 45 } else { 46 nextProtosLength += 1 + l 47 } 48 } 49 if nextProtosLength > 0xffff { 50 return nil, nil, errors.New("tls: NextProtos values too large") 51 } 52 53 supportedVersions := config.supportedVersions() 54 if len(supportedVersions) == 0 { 55 return nil, nil, errors.New("tls: no supported versions satisfy MinVersion and MaxVersion") 56 } 57 58 clientHelloVersion := config.maxSupportedVersion() 59 // The version at the beginning of the ClientHello was capped at TLS 1.2 60 // for compatibility reasons. The supported_versions extension is used 61 // to negotiate versions now. See RFC 8446, Section 4.2.1. 62 if clientHelloVersion > VersionTLS12 { 63 clientHelloVersion = VersionTLS12 64 } 65 66 hello := &clientHelloMsg{ 67 vers: clientHelloVersion, 68 compressionMethods: []uint8{compressionNone}, 69 random: make([]byte, 32), 70 sessionId: make([]byte, 32), 71 ocspStapling: true, 72 scts: true, 73 serverName: hostnameInSNI(config.ServerName), 74 supportedCurves: config.curvePreferences(), 75 supportedPoints: []uint8{pointFormatUncompressed}, 76 secureRenegotiationSupported: true, 77 alpnProtocols: config.NextProtos, 78 supportedVersions: supportedVersions, 79 } 80 81 if c.handshakes > 0 { 82 hello.secureRenegotiation = c.clientFinished[:] 83 } 84 85 possibleCipherSuites := config.cipherSuites() 86 hello.cipherSuites = make([]uint16, 0, len(possibleCipherSuites)) 87 88 for _, suiteId := range possibleCipherSuites { 89 for _, suite := range cipherSuites { 90 if suite.id != suiteId { 91 continue 92 } 93 // Don't advertise TLS 1.2-only cipher suites unless 94 // we're attempting TLS 1.2. 95 if hello.vers < VersionTLS12 && suite.flags&suiteTLS12 != 0 { 96 break 97 } 98 hello.cipherSuites = append(hello.cipherSuites, suiteId) 99 break 100 } 101 } 102 103 _, err := io.ReadFull(config.rand(), hello.random) 104 if err != nil { 105 return nil, nil, errors.New("tls: short read from Rand: " + err.Error()) 106 } 107 108 // A random session ID is used to detect when the server accepted a ticket 109 // and is resuming a session (see RFC 5077). In TLS 1.3, it's always set as 110 // a compatibility measure (see RFC 8446, Section 4.1.2). 111 if _, err := io.ReadFull(config.rand(), hello.sessionId); err != nil { 112 return nil, nil, errors.New("tls: short read from Rand: " + err.Error()) 113 } 114 115 if hello.vers >= VersionTLS12 { 116 hello.supportedSignatureAlgorithms = supportedSignatureAlgorithms 117 } 118 119 var params ecdheParameters 120 if hello.supportedVersions[0] == VersionTLS13 { 121 hello.cipherSuites = append(hello.cipherSuites, defaultCipherSuitesTLS13()...) 122 123 curveID := config.curvePreferences()[0] 124 if _, ok := curveForCurveID(curveID); curveID != X25519 && !ok { 125 return nil, nil, errors.New("tls: CurvePreferences includes unsupported curve") 126 } 127 params, err = generateECDHEParameters(config.rand(), curveID) 128 if err != nil { 129 return nil, nil, err 130 } 131 hello.keyShares = []keyShare{{group: curveID, data: params.PublicKey()}} 132 } 133 134 return hello, params, nil 135 } 136 137 func (c *Conn) clientHandshake() (err error) { 138 if c.config == nil { 139 c.config = defaultConfig() 140 } 141 142 // This may be a renegotiation handshake, in which case some fields 143 // need to be reset. 144 c.didResume = false 145 146 hello, ecdheParams, err := c.makeClientHello() 147 if err != nil { 148 return err 149 } 150 c.serverName = hello.serverName 151 152 cacheKey, session, earlySecret, binderKey := c.loadSession(hello) 153 if cacheKey != "" && session != nil { 154 defer func() { 155 // If we got a handshake failure when resuming a session, throw away 156 // the session ticket. See RFC 5077, Section 3.2. 157 // 158 // RFC 8446 makes no mention of dropping tickets on failure, but it 159 // does require servers to abort on invalid binders, so we need to 160 // delete tickets to recover from a corrupted PSK. 161 if err != nil { 162 c.config.ClientSessionCache.Put(cacheKey, nil) 163 } 164 }() 165 } 166 167 if _, err := c.writeRecord(recordTypeHandshake, hello.marshal()); err != nil { 168 return err 169 } 170 171 msg, err := c.readHandshake() 172 if err != nil { 173 return err 174 } 175 176 serverHello, ok := msg.(*serverHelloMsg) 177 if !ok { 178 c.sendAlert(alertUnexpectedMessage) 179 return unexpectedMessageError(serverHello, msg) 180 } 181 182 if err := c.pickTLSVersion(serverHello); err != nil { 183 return err 184 } 185 186 // If we are negotiating a protocol version that's lower than what we 187 // support, check for the server downgrade canaries. 188 // See RFC 8446, Section 4.1.3. 189 maxVers := c.config.maxSupportedVersion() 190 tls12Downgrade := string(serverHello.random[24:]) == downgradeCanaryTLS12 191 tls11Downgrade := string(serverHello.random[24:]) == downgradeCanaryTLS11 192 if maxVers == VersionTLS13 && c.vers <= VersionTLS12 && (tls12Downgrade || tls11Downgrade) || 193 maxVers == VersionTLS12 && c.vers <= VersionTLS11 && tls11Downgrade { 194 c.sendAlert(alertIllegalParameter) 195 return errors.New("tls: downgrade attempt detected, possibly due to a MitM attack or a broken middlebox") 196 } 197 198 if c.vers == VersionTLS13 { 199 hs := &clientHandshakeStateTLS13{ 200 c: c, 201 serverHello: serverHello, 202 hello: hello, 203 ecdheParams: ecdheParams, 204 session: session, 205 earlySecret: earlySecret, 206 binderKey: binderKey, 207 } 208 209 // In TLS 1.3, session tickets are delivered after the handshake. 210 return hs.handshake() 211 } 212 213 hs := &clientHandshakeState{ 214 c: c, 215 serverHello: serverHello, 216 hello: hello, 217 session: session, 218 } 219 220 if err := hs.handshake(); err != nil { 221 return err 222 } 223 224 // If we had a successful handshake and hs.session is different from 225 // the one already cached - cache a new one. 226 if cacheKey != "" && hs.session != nil && session != hs.session { 227 c.config.ClientSessionCache.Put(cacheKey, hs.session) 228 } 229 230 return nil 231 } 232 233 func (c *Conn) loadSession(hello *clientHelloMsg) (cacheKey string, 234 session *ClientSessionState, earlySecret, binderKey []byte) { 235 if c.config.SessionTicketsDisabled || c.config.ClientSessionCache == nil { 236 return "", nil, nil, nil 237 } 238 239 hello.ticketSupported = true 240 241 if hello.supportedVersions[0] == VersionTLS13 { 242 // Require DHE on resumption as it guarantees forward secrecy against 243 // compromise of the session ticket key. See RFC 8446, Section 4.2.9. 244 hello.pskModes = []uint8{pskModeDHE} 245 } 246 247 // Session resumption is not allowed if renegotiating because 248 // renegotiation is primarily used to allow a client to send a client 249 // certificate, which would be skipped if session resumption occurred. 250 if c.handshakes != 0 { 251 return "", nil, nil, nil 252 } 253 254 // Try to resume a previously negotiated TLS session, if available. 255 cacheKey = clientSessionCacheKey(c.conn.RemoteAddr(), c.config) 256 session, ok := c.config.ClientSessionCache.Get(cacheKey) 257 if !ok || session == nil { 258 return cacheKey, nil, nil, nil 259 } 260 261 // Check that version used for the previous session is still valid. 262 versOk := false 263 for _, v := range hello.supportedVersions { 264 if v == session.vers { 265 versOk = true 266 break 267 } 268 } 269 if !versOk { 270 return cacheKey, nil, nil, nil 271 } 272 273 // Check that the cached server certificate is not expired, and that it's 274 // valid for the ServerName. This should be ensured by the cache key, but 275 // protect the application from a faulty ClientSessionCache implementation. 276 if !c.config.InsecureSkipVerify { 277 if len(session.verifiedChains) == 0 { 278 // The original connection had InsecureSkipVerify, while this doesn't. 279 return cacheKey, nil, nil, nil 280 } 281 serverCert := session.serverCertificates[0] 282 if c.config.time().After(serverCert.NotAfter) { 283 // Expired certificate, delete the entry. 284 c.config.ClientSessionCache.Put(cacheKey, nil) 285 return cacheKey, nil, nil, nil 286 } 287 if err := serverCert.VerifyHostname(c.config.ServerName); err != nil { 288 return cacheKey, nil, nil, nil 289 } 290 } 291 292 if session.vers != VersionTLS13 { 293 // In TLS 1.2 the cipher suite must match the resumed session. Ensure we 294 // are still offering it. 295 if mutualCipherSuite(hello.cipherSuites, session.cipherSuite) == nil { 296 return cacheKey, nil, nil, nil 297 } 298 299 hello.sessionTicket = session.sessionTicket 300 return 301 } 302 303 // Check that the session ticket is not expired. 304 if c.config.time().After(session.useBy) { 305 c.config.ClientSessionCache.Put(cacheKey, nil) 306 return cacheKey, nil, nil, nil 307 } 308 309 // In TLS 1.3 the KDF hash must match the resumed session. Ensure we 310 // offer at least one cipher suite with that hash. 311 cipherSuite := cipherSuiteTLS13ByID(session.cipherSuite) 312 if cipherSuite == nil { 313 return cacheKey, nil, nil, nil 314 } 315 cipherSuiteOk := false 316 for _, offeredID := range hello.cipherSuites { 317 offeredSuite := cipherSuiteTLS13ByID(offeredID) 318 if offeredSuite != nil && offeredSuite.hash == cipherSuite.hash { 319 cipherSuiteOk = true 320 break 321 } 322 } 323 if !cipherSuiteOk { 324 return cacheKey, nil, nil, nil 325 } 326 327 // Set the pre_shared_key extension. See RFC 8446, Section 4.2.11.1. 328 ticketAge := uint32(c.config.time().Sub(session.receivedAt) / time.Millisecond) 329 identity := pskIdentity{ 330 label: session.sessionTicket, 331 obfuscatedTicketAge: ticketAge + session.ageAdd, 332 } 333 hello.pskIdentities = []pskIdentity{identity} 334 hello.pskBinders = [][]byte{make([]byte, cipherSuite.hash.Size())} 335 336 // Compute the PSK binders. See RFC 8446, Section 4.2.11.2. 337 psk := cipherSuite.expandLabel(session.masterSecret, "resumption", 338 session.nonce, cipherSuite.hash.Size()) 339 earlySecret = cipherSuite.extract(psk, nil) 340 binderKey = cipherSuite.deriveSecret(earlySecret, resumptionBinderLabel, nil) 341 transcript := cipherSuite.hash.New() 342 transcript.Write(hello.marshalWithoutBinders()) 343 pskBinders := [][]byte{cipherSuite.finishedHash(binderKey, transcript)} 344 hello.updateBinders(pskBinders) 345 346 return 347 } 348 349 func (c *Conn) pickTLSVersion(serverHello *serverHelloMsg) error { 350 peerVersion := serverHello.vers 351 if serverHello.supportedVersion != 0 { 352 peerVersion = serverHello.supportedVersion 353 } 354 355 vers, ok := c.config.mutualVersion([]uint16{peerVersion}) 356 if !ok { 357 c.sendAlert(alertProtocolVersion) 358 return fmt.Errorf("tls: server selected unsupported protocol version %x", peerVersion) 359 } 360 361 c.vers = vers 362 c.haveVers = true 363 c.in.version = vers 364 c.out.version = vers 365 366 return nil 367 } 368 369 // Does the handshake, either a full one or resumes old session. Requires hs.c, 370 // hs.hello, hs.serverHello, and, optionally, hs.session to be set. 371 func (hs *clientHandshakeState) handshake() error { 372 c := hs.c 373 374 isResume, err := hs.processServerHello() 375 if err != nil { 376 return err 377 } 378 379 hs.finishedHash = newFinishedHash(c.vers, hs.suite) 380 381 // No signatures of the handshake are needed in a resumption. 382 // Otherwise, in a full handshake, if we don't have any certificates 383 // configured then we will never send a CertificateVerify message and 384 // thus no signatures are needed in that case either. 385 if isResume || (len(c.config.Certificates) == 0 && c.config.GetClientCertificate == nil) { 386 hs.finishedHash.discardHandshakeBuffer() 387 } 388 389 hs.finishedHash.Write(hs.hello.marshal()) 390 hs.finishedHash.Write(hs.serverHello.marshal()) 391 392 c.buffering = true 393 c.didResume = isResume 394 if isResume { 395 if err := hs.establishKeys(); err != nil { 396 return err 397 } 398 if err := hs.readSessionTicket(); err != nil { 399 return err 400 } 401 if err := hs.readFinished(c.serverFinished[:]); err != nil { 402 return err 403 } 404 c.clientFinishedIsFirst = false 405 // Make sure the connection is still being verified whether or not this 406 // is a resumption. Resumptions currently don't reverify certificates so 407 // they don't call verifyServerCertificate. See Issue 31641. 408 if c.config.VerifyConnection != nil { 409 if err := c.config.VerifyConnection(c.connectionStateLocked()); err != nil { 410 c.sendAlert(alertBadCertificate) 411 return err 412 } 413 } 414 if err := hs.sendFinished(c.clientFinished[:]); err != nil { 415 return err 416 } 417 if _, err := c.flush(); err != nil { 418 return err 419 } 420 } else { 421 if err := hs.doFullHandshake(); err != nil { 422 return err 423 } 424 if err := hs.establishKeys(); err != nil { 425 return err 426 } 427 if err := hs.sendFinished(c.clientFinished[:]); err != nil { 428 return err 429 } 430 if _, err := c.flush(); err != nil { 431 return err 432 } 433 c.clientFinishedIsFirst = true 434 if err := hs.readSessionTicket(); err != nil { 435 return err 436 } 437 if err := hs.readFinished(c.serverFinished[:]); err != nil { 438 return err 439 } 440 } 441 442 c.ekm = ekmFromMasterSecret(c.vers, hs.suite, hs.masterSecret, hs.hello.random, hs.serverHello.random) 443 atomic.StoreUint32(&c.handshakeStatus, 1) 444 445 return nil 446 } 447 448 func (hs *clientHandshakeState) pickCipherSuite() error { 449 if hs.suite = mutualCipherSuite(hs.hello.cipherSuites, hs.serverHello.cipherSuite); hs.suite == nil { 450 hs.c.sendAlert(alertHandshakeFailure) 451 return errors.New("tls: server chose an unconfigured cipher suite") 452 } 453 454 hs.c.cipherSuite = hs.suite.id 455 return nil 456 } 457 458 func (hs *clientHandshakeState) doFullHandshake() error { 459 c := hs.c 460 461 msg, err := c.readHandshake() 462 if err != nil { 463 return err 464 } 465 certMsg, ok := msg.(*certificateMsg) 466 if !ok || len(certMsg.certificates) == 0 { 467 c.sendAlert(alertUnexpectedMessage) 468 return unexpectedMessageError(certMsg, msg) 469 } 470 hs.finishedHash.Write(certMsg.marshal()) 471 472 msg, err = c.readHandshake() 473 if err != nil { 474 return err 475 } 476 477 cs, ok := msg.(*certificateStatusMsg) 478 if ok { 479 // RFC4366 on Certificate Status Request: 480 // The server MAY return a "certificate_status" message. 481 482 if !hs.serverHello.ocspStapling { 483 // If a server returns a "CertificateStatus" message, then the 484 // server MUST have included an extension of type "status_request" 485 // with empty "extension_data" in the extended server hello. 486 487 c.sendAlert(alertUnexpectedMessage) 488 return errors.New("tls: received unexpected CertificateStatus message") 489 } 490 hs.finishedHash.Write(cs.marshal()) 491 492 c.ocspResponse = cs.response 493 494 msg, err = c.readHandshake() 495 if err != nil { 496 return err 497 } 498 } 499 500 if c.handshakes == 0 { 501 // If this is the first handshake on a connection, process and 502 // (optionally) verify the server's certificates. 503 if err := c.verifyServerCertificate(certMsg.certificates); err != nil { 504 return err 505 } 506 } else { 507 // This is a renegotiation handshake. We require that the 508 // server's identity (i.e. leaf certificate) is unchanged and 509 // thus any previous trust decision is still valid. 510 // 511 // See https://mitls.org/pages/attacks/3SHAKE for the 512 // motivation behind this requirement. 513 if !bytes.Equal(c.peerCertificates[0].Raw, certMsg.certificates[0]) { 514 c.sendAlert(alertBadCertificate) 515 return errors.New("tls: server's identity changed during renegotiation") 516 } 517 } 518 519 keyAgreement := hs.suite.ka(c.vers) 520 521 skx, ok := msg.(*serverKeyExchangeMsg) 522 if ok { 523 hs.finishedHash.Write(skx.marshal()) 524 err = keyAgreement.processServerKeyExchange(c.config, hs.hello, hs.serverHello, c.peerCertificates[0], skx) 525 if err != nil { 526 c.sendAlert(alertUnexpectedMessage) 527 return err 528 } 529 530 msg, err = c.readHandshake() 531 if err != nil { 532 return err 533 } 534 } 535 536 var chainToSend *Certificate 537 var certRequested bool 538 certReq, ok := msg.(*certificateRequestMsg) 539 if ok { 540 certRequested = true 541 hs.finishedHash.Write(certReq.marshal()) 542 543 cri := certificateRequestInfoFromMsg(c.vers, certReq) 544 if chainToSend, err = c.getClientCertificate(cri); err != nil { 545 c.sendAlert(alertInternalError) 546 return err 547 } 548 549 msg, err = c.readHandshake() 550 if err != nil { 551 return err 552 } 553 } 554 555 shd, ok := msg.(*serverHelloDoneMsg) 556 if !ok { 557 c.sendAlert(alertUnexpectedMessage) 558 return unexpectedMessageError(shd, msg) 559 } 560 hs.finishedHash.Write(shd.marshal()) 561 562 // If the server requested a certificate then we have to send a 563 // Certificate message, even if it's empty because we don't have a 564 // certificate to send. 565 if certRequested { 566 certMsg = new(certificateMsg) 567 certMsg.certificates = chainToSend.Certificate 568 hs.finishedHash.Write(certMsg.marshal()) 569 if _, err := c.writeRecord(recordTypeHandshake, certMsg.marshal()); err != nil { 570 return err 571 } 572 } 573 574 preMasterSecret, ckx, err := keyAgreement.generateClientKeyExchange(c.config, hs.hello, c.peerCertificates[0]) 575 if err != nil { 576 c.sendAlert(alertInternalError) 577 return err 578 } 579 if ckx != nil { 580 hs.finishedHash.Write(ckx.marshal()) 581 if _, err := c.writeRecord(recordTypeHandshake, ckx.marshal()); err != nil { 582 return err 583 } 584 } 585 586 if chainToSend != nil && len(chainToSend.Certificate) > 0 { 587 certVerify := &certificateVerifyMsg{} 588 589 key, ok := chainToSend.PrivateKey.(crypto.Signer) 590 if !ok { 591 c.sendAlert(alertInternalError) 592 return fmt.Errorf("tls: client certificate private key of type %T does not implement crypto.Signer", chainToSend.PrivateKey) 593 } 594 595 var sigType uint8 596 var sigHash crypto.Hash 597 if c.vers >= VersionTLS12 { 598 signatureAlgorithm, err := selectSignatureScheme(c.vers, chainToSend, certReq.supportedSignatureAlgorithms) 599 if err != nil { 600 c.sendAlert(alertIllegalParameter) 601 return err 602 } 603 sigType, sigHash, err = typeAndHashFromSignatureScheme(signatureAlgorithm) 604 if err != nil { 605 return c.sendAlert(alertInternalError) 606 } 607 certVerify.hasSignatureAlgorithm = true 608 certVerify.signatureAlgorithm = signatureAlgorithm 609 } else { 610 sigType, sigHash, err = legacyTypeAndHashFromPublicKey(key.Public()) 611 if err != nil { 612 c.sendAlert(alertIllegalParameter) 613 return err 614 } 615 } 616 617 signed := hs.finishedHash.hashForClientCertificate(sigType, sigHash, hs.masterSecret) 618 signOpts := crypto.SignerOpts(sigHash) 619 if sigType == signatureRSAPSS { 620 signOpts = &rsa.PSSOptions{SaltLength: rsa.PSSSaltLengthEqualsHash, Hash: sigHash} 621 } 622 certVerify.signature, err = key.Sign(c.config.rand(), signed, signOpts) 623 if err != nil { 624 c.sendAlert(alertInternalError) 625 return err 626 } 627 628 hs.finishedHash.Write(certVerify.marshal()) 629 if _, err := c.writeRecord(recordTypeHandshake, certVerify.marshal()); err != nil { 630 return err 631 } 632 } 633 634 hs.masterSecret = masterFromPreMasterSecret(c.vers, hs.suite, preMasterSecret, hs.hello.random, hs.serverHello.random) 635 if err := c.config.writeKeyLog(keyLogLabelTLS12, hs.hello.random, hs.masterSecret); err != nil { 636 c.sendAlert(alertInternalError) 637 return errors.New("tls: failed to write to key log: " + err.Error()) 638 } 639 640 hs.finishedHash.discardHandshakeBuffer() 641 642 return nil 643 } 644 645 func (hs *clientHandshakeState) establishKeys() error { 646 c := hs.c 647 648 clientMAC, serverMAC, clientKey, serverKey, clientIV, serverIV := 649 keysFromMasterSecret(c.vers, hs.suite, hs.masterSecret, hs.hello.random, hs.serverHello.random, hs.suite.macLen, hs.suite.keyLen, hs.suite.ivLen) 650 var clientCipher, serverCipher interface{} 651 var clientHash, serverHash hash.Hash 652 if hs.suite.cipher != nil { 653 clientCipher = hs.suite.cipher(clientKey, clientIV, false /* not for reading */) 654 clientHash = hs.suite.mac(clientMAC) 655 serverCipher = hs.suite.cipher(serverKey, serverIV, true /* for reading */) 656 serverHash = hs.suite.mac(serverMAC) 657 } else { 658 clientCipher = hs.suite.aead(clientKey, clientIV) 659 serverCipher = hs.suite.aead(serverKey, serverIV) 660 } 661 662 c.in.prepareCipherSpec(c.vers, serverCipher, serverHash) 663 c.out.prepareCipherSpec(c.vers, clientCipher, clientHash) 664 return nil 665 } 666 667 func (hs *clientHandshakeState) serverResumedSession() bool { 668 // If the server responded with the same sessionId then it means the 669 // sessionTicket is being used to resume a TLS session. 670 return hs.session != nil && hs.hello.sessionId != nil && 671 bytes.Equal(hs.serverHello.sessionId, hs.hello.sessionId) 672 } 673 674 func (hs *clientHandshakeState) processServerHello() (bool, error) { 675 c := hs.c 676 677 if err := hs.pickCipherSuite(); err != nil { 678 return false, err 679 } 680 681 if hs.serverHello.compressionMethod != compressionNone { 682 c.sendAlert(alertUnexpectedMessage) 683 return false, errors.New("tls: server selected unsupported compression format") 684 } 685 686 if c.handshakes == 0 && hs.serverHello.secureRenegotiationSupported { 687 c.secureRenegotiation = true 688 if len(hs.serverHello.secureRenegotiation) != 0 { 689 c.sendAlert(alertHandshakeFailure) 690 return false, errors.New("tls: initial handshake had non-empty renegotiation extension") 691 } 692 } 693 694 if c.handshakes > 0 && c.secureRenegotiation { 695 var expectedSecureRenegotiation [24]byte 696 copy(expectedSecureRenegotiation[:], c.clientFinished[:]) 697 copy(expectedSecureRenegotiation[12:], c.serverFinished[:]) 698 if !bytes.Equal(hs.serverHello.secureRenegotiation, expectedSecureRenegotiation[:]) { 699 c.sendAlert(alertHandshakeFailure) 700 return false, errors.New("tls: incorrect renegotiation extension contents") 701 } 702 } 703 704 if hs.serverHello.alpnProtocol != "" { 705 if len(hs.hello.alpnProtocols) == 0 { 706 c.sendAlert(alertUnsupportedExtension) 707 return false, errors.New("tls: server advertised unrequested ALPN extension") 708 } 709 if mutualProtocol([]string{hs.serverHello.alpnProtocol}, hs.hello.alpnProtocols) == "" { 710 c.sendAlert(alertUnsupportedExtension) 711 return false, errors.New("tls: server selected unadvertised ALPN protocol") 712 } 713 c.clientProtocol = hs.serverHello.alpnProtocol 714 } 715 716 c.scts = hs.serverHello.scts 717 718 if !hs.serverResumedSession() { 719 return false, nil 720 } 721 722 if hs.session.vers != c.vers { 723 c.sendAlert(alertHandshakeFailure) 724 return false, errors.New("tls: server resumed a session with a different version") 725 } 726 727 if hs.session.cipherSuite != hs.suite.id { 728 c.sendAlert(alertHandshakeFailure) 729 return false, errors.New("tls: server resumed a session with a different cipher suite") 730 } 731 732 // Restore masterSecret, peerCerts, and ocspResponse from previous state 733 hs.masterSecret = hs.session.masterSecret 734 c.peerCertificates = hs.session.serverCertificates 735 c.verifiedChains = hs.session.verifiedChains 736 c.ocspResponse = hs.session.ocspResponse 737 // Let the ServerHello SCTs override the session SCTs from the original 738 // connection, if any are provided 739 if len(c.scts) == 0 && len(hs.session.scts) != 0 { 740 c.scts = hs.session.scts 741 } 742 743 return true, nil 744 } 745 746 func (hs *clientHandshakeState) readFinished(out []byte) error { 747 c := hs.c 748 749 if err := c.readChangeCipherSpec(); err != nil { 750 return err 751 } 752 753 msg, err := c.readHandshake() 754 if err != nil { 755 return err 756 } 757 serverFinished, ok := msg.(*finishedMsg) 758 if !ok { 759 c.sendAlert(alertUnexpectedMessage) 760 return unexpectedMessageError(serverFinished, msg) 761 } 762 763 verify := hs.finishedHash.serverSum(hs.masterSecret) 764 if len(verify) != len(serverFinished.verifyData) || 765 subtle.ConstantTimeCompare(verify, serverFinished.verifyData) != 1 { 766 c.sendAlert(alertHandshakeFailure) 767 return errors.New("tls: server's Finished message was incorrect") 768 } 769 hs.finishedHash.Write(serverFinished.marshal()) 770 copy(out, verify) 771 return nil 772 } 773 774 func (hs *clientHandshakeState) readSessionTicket() error { 775 if !hs.serverHello.ticketSupported { 776 return nil 777 } 778 779 c := hs.c 780 msg, err := c.readHandshake() 781 if err != nil { 782 return err 783 } 784 sessionTicketMsg, ok := msg.(*newSessionTicketMsg) 785 if !ok { 786 c.sendAlert(alertUnexpectedMessage) 787 return unexpectedMessageError(sessionTicketMsg, msg) 788 } 789 hs.finishedHash.Write(sessionTicketMsg.marshal()) 790 791 hs.session = &ClientSessionState{ 792 sessionTicket: sessionTicketMsg.ticket, 793 vers: c.vers, 794 cipherSuite: hs.suite.id, 795 masterSecret: hs.masterSecret, 796 serverCertificates: c.peerCertificates, 797 verifiedChains: c.verifiedChains, 798 receivedAt: c.config.time(), 799 ocspResponse: c.ocspResponse, 800 scts: c.scts, 801 } 802 803 return nil 804 } 805 806 func (hs *clientHandshakeState) sendFinished(out []byte) error { 807 c := hs.c 808 809 if _, err := c.writeRecord(recordTypeChangeCipherSpec, []byte{1}); err != nil { 810 return err 811 } 812 813 finished := new(finishedMsg) 814 finished.verifyData = hs.finishedHash.clientSum(hs.masterSecret) 815 hs.finishedHash.Write(finished.marshal()) 816 if _, err := c.writeRecord(recordTypeHandshake, finished.marshal()); err != nil { 817 return err 818 } 819 copy(out, finished.verifyData) 820 return nil 821 } 822 823 // verifyServerCertificate parses and verifies the provided chain, setting 824 // c.verifiedChains and c.peerCertificates or sending the appropriate alert. 825 func (c *Conn) verifyServerCertificate(certificates [][]byte) error { 826 certs := make([]*x509.Certificate, len(certificates)) 827 for i, asn1Data := range certificates { 828 cert, err := x509.ParseCertificate(asn1Data) 829 if err != nil { 830 c.sendAlert(alertBadCertificate) 831 return errors.New("tls: failed to parse certificate from server: " + err.Error()) 832 } 833 certs[i] = cert 834 } 835 836 if !c.config.InsecureSkipVerify { 837 opts := x509.VerifyOptions{ 838 Roots: c.config.RootCAs, 839 CurrentTime: c.config.time(), 840 DNSName: c.config.ServerName, 841 Intermediates: x509.NewCertPool(), 842 } 843 for _, cert := range certs[1:] { 844 opts.Intermediates.AddCert(cert) 845 } 846 var err error 847 c.verifiedChains, err = certs[0].Verify(opts) 848 if err != nil { 849 c.sendAlert(alertBadCertificate) 850 return err 851 } 852 } 853 854 switch certs[0].PublicKey.(type) { 855 case *rsa.PublicKey, *ecdsa.PublicKey, ed25519.PublicKey: 856 break 857 default: 858 c.sendAlert(alertUnsupportedCertificate) 859 return fmt.Errorf("tls: server's certificate contains an unsupported type of public key: %T", certs[0].PublicKey) 860 } 861 862 c.peerCertificates = certs 863 864 if c.config.VerifyPeerCertificate != nil { 865 if err := c.config.VerifyPeerCertificate(certificates, c.verifiedChains); err != nil { 866 c.sendAlert(alertBadCertificate) 867 return err 868 } 869 } 870 871 if c.config.VerifyConnection != nil { 872 if err := c.config.VerifyConnection(c.connectionStateLocked()); err != nil { 873 c.sendAlert(alertBadCertificate) 874 return err 875 } 876 } 877 878 return nil 879 } 880 881 // certificateRequestInfoFromMsg generates a CertificateRequestInfo from a TLS 882 // <= 1.2 CertificateRequest, making an effort to fill in missing information. 883 func certificateRequestInfoFromMsg(vers uint16, certReq *certificateRequestMsg) *CertificateRequestInfo { 884 cri := &CertificateRequestInfo{ 885 AcceptableCAs: certReq.certificateAuthorities, 886 Version: vers, 887 } 888 889 var rsaAvail, ecAvail bool 890 for _, certType := range certReq.certificateTypes { 891 switch certType { 892 case certTypeRSASign: 893 rsaAvail = true 894 case certTypeECDSASign: 895 ecAvail = true 896 } 897 } 898 899 if !certReq.hasSignatureAlgorithm { 900 // Prior to TLS 1.2, signature schemes did not exist. In this case we 901 // make up a list based on the acceptable certificate types, to help 902 // GetClientCertificate and SupportsCertificate select the right certificate. 903 // The hash part of the SignatureScheme is a lie here, because 904 // TLS 1.0 and 1.1 always use MD5+SHA1 for RSA and SHA1 for ECDSA. 905 switch { 906 case rsaAvail && ecAvail: 907 cri.SignatureSchemes = []SignatureScheme{ 908 ECDSAWithP256AndSHA256, ECDSAWithP384AndSHA384, ECDSAWithP521AndSHA512, 909 PKCS1WithSHA256, PKCS1WithSHA384, PKCS1WithSHA512, PKCS1WithSHA1, 910 } 911 case rsaAvail: 912 cri.SignatureSchemes = []SignatureScheme{ 913 PKCS1WithSHA256, PKCS1WithSHA384, PKCS1WithSHA512, PKCS1WithSHA1, 914 } 915 case ecAvail: 916 cri.SignatureSchemes = []SignatureScheme{ 917 ECDSAWithP256AndSHA256, ECDSAWithP384AndSHA384, ECDSAWithP521AndSHA512, 918 } 919 } 920 return cri 921 } 922 923 // Filter the signature schemes based on the certificate types. 924 // See RFC 5246, Section 7.4.4 (where it calls this "somewhat complicated"). 925 cri.SignatureSchemes = make([]SignatureScheme, 0, len(certReq.supportedSignatureAlgorithms)) 926 for _, sigScheme := range certReq.supportedSignatureAlgorithms { 927 sigType, _, err := typeAndHashFromSignatureScheme(sigScheme) 928 if err != nil { 929 continue 930 } 931 switch sigType { 932 case signatureECDSA, signatureEd25519: 933 if ecAvail { 934 cri.SignatureSchemes = append(cri.SignatureSchemes, sigScheme) 935 } 936 case signatureRSAPSS, signaturePKCS1v15: 937 if rsaAvail { 938 cri.SignatureSchemes = append(cri.SignatureSchemes, sigScheme) 939 } 940 } 941 } 942 943 return cri 944 } 945 946 func (c *Conn) getClientCertificate(cri *CertificateRequestInfo) (*Certificate, error) { 947 if c.config.GetClientCertificate != nil { 948 return c.config.GetClientCertificate(cri) 949 } 950 951 for _, chain := range c.config.Certificates { 952 if err := cri.SupportsCertificate(&chain); err != nil { 953 continue 954 } 955 return &chain, nil 956 } 957 958 // No acceptable certificate found. Don't send a certificate. 959 return new(Certificate), nil 960 } 961 962 // clientSessionCacheKey returns a key used to cache sessionTickets that could 963 // be used to resume previously negotiated TLS sessions with a server. 964 func clientSessionCacheKey(serverAddr net.Addr, config *Config) string { 965 if len(config.ServerName) > 0 { 966 return config.ServerName 967 } 968 return serverAddr.String() 969 } 970 971 // mutualProtocol finds the mutual ALPN protocol given list of possible 972 // protocols and a list of the preference order. 973 func mutualProtocol(protos, preferenceProtos []string) string { 974 for _, s := range preferenceProtos { 975 for _, c := range protos { 976 if s == c { 977 return s 978 } 979 } 980 } 981 return "" 982 } 983 984 // hostnameInSNI converts name into an appropriate hostname for SNI. 985 // Literal IP addresses and absolute FQDNs are not permitted as SNI values. 986 // See RFC 6066, Section 3. 987 func hostnameInSNI(name string) string { 988 host := name 989 if len(host) > 0 && host[0] == '[' && host[len(host)-1] == ']' { 990 host = host[1 : len(host)-1] 991 } 992 if i := strings.LastIndex(host, "%"); i > 0 { 993 host = host[:i] 994 } 995 if net.ParseIP(host) != nil { 996 return "" 997 } 998 for len(name) > 0 && name[len(name)-1] == '.' { 999 name = name[:len(name)-1] 1000 } 1001 return name 1002 }