github.com/mangodowner/go-gm@v0.0.0-20180818020936-8baa2bd4408c/src/crypto/tls/common.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  	"container/list"
     9  	"crypto"
    10  	"crypto/internal/cipherhw"
    11  	"crypto/rand"
    12  	"crypto/sha512"
    13  	"errors"
    14  	"fmt"
    15  	"io"
    16  	"math/big"
    17  	"net"
    18  	"strings"
    19  	"sync"
    20  	"time"
    21  	"crypto/sm2"
    22  )
    23  
    24  const (
    25  	VersionSSL30 = 0x0300
    26  	VersionTLS10 = 0x0301
    27  	VersionTLS11 = 0x0302
    28  	VersionTLS12 = 0x0303
    29  )
    30  
    31  const (
    32  	maxPlaintext    = 16384        // maximum plaintext payload length
    33  	maxCiphertext   = 16384 + 2048 // maximum ciphertext payload length
    34  	recordHeaderLen = 5            // record header length
    35  	maxHandshake    = 65536        // maximum handshake we support (protocol max is 16 MB)
    36  
    37  	minVersion = VersionTLS10
    38  	maxVersion = VersionTLS12
    39  )
    40  
    41  // TLS record types.
    42  type recordType uint8
    43  
    44  const (
    45  	recordTypeChangeCipherSpec recordType = 20
    46  	recordTypeAlert            recordType = 21
    47  	recordTypeHandshake        recordType = 22
    48  	recordTypeApplicationData  recordType = 23
    49  )
    50  
    51  // TLS handshake message types.
    52  const (
    53  	typeHelloRequest       uint8 = 0
    54  	typeClientHello        uint8 = 1
    55  	typeServerHello        uint8 = 2
    56  	typeNewSessionTicket   uint8 = 4
    57  	typeCertificate        uint8 = 11
    58  	typeServerKeyExchange  uint8 = 12
    59  	typeCertificateRequest uint8 = 13
    60  	typeServerHelloDone    uint8 = 14
    61  	typeCertificateVerify  uint8 = 15
    62  	typeClientKeyExchange  uint8 = 16
    63  	typeFinished           uint8 = 20
    64  	typeCertificateStatus  uint8 = 22
    65  	typeNextProtocol       uint8 = 67 // Not IANA assigned
    66  )
    67  
    68  // TLS compression types.
    69  const (
    70  	compressionNone uint8 = 0
    71  )
    72  
    73  // TLS extension numbers
    74  const (
    75  	extensionServerName          uint16 = 0
    76  	extensionStatusRequest       uint16 = 5
    77  	extensionSupportedCurves     uint16 = 10
    78  	extensionSupportedPoints     uint16 = 11
    79  	extensionSignatureAlgorithms uint16 = 13
    80  	extensionALPN                uint16 = 16
    81  	extensionSCT                 uint16 = 18 // https://tools.ietf.org/html/rfc6962#section-6
    82  	extensionSessionTicket       uint16 = 35
    83  	extensionNextProtoNeg        uint16 = 13172 // not IANA assigned
    84  	extensionRenegotiationInfo   uint16 = 0xff01
    85  )
    86  
    87  // TLS signaling cipher suite values
    88  const (
    89  	scsvRenegotiation uint16 = 0x00ff
    90  )
    91  
    92  // CurveID is the type of a TLS identifier for an elliptic curve. See
    93  // http://www.iana.org/assignments/tls-parameters/tls-parameters.xml#tls-parameters-8
    94  type CurveID uint16
    95  
    96  const (
    97  	CurveP256 CurveID = 23
    98  	CurveP384 CurveID = 24
    99  	CurveP521 CurveID = 25
   100  	X25519    CurveID = 29
   101  	CureP256SM2 CurveID = 31
   102  )
   103  
   104  // TLS Elliptic Curve Point Formats
   105  // http://www.iana.org/assignments/tls-parameters/tls-parameters.xml#tls-parameters-9
   106  const (
   107  	pointFormatUncompressed uint8 = 0
   108  )
   109  
   110  // TLS CertificateStatusType (RFC 3546)
   111  const (
   112  	statusTypeOCSP uint8 = 1
   113  )
   114  
   115  // Certificate types (for certificateRequestMsg)
   116  const (
   117  	certTypeRSASign    = 1 // A certificate containing an RSA key
   118  	certTypeDSSSign    = 2 // A certificate containing a DSA key
   119  	certTypeRSAFixedDH = 3 // A certificate containing a static DH key
   120  	certTypeDSSFixedDH = 4 // A certificate containing a static DH key
   121  
   122  	// See RFC 4492 sections 3 and 5.5.
   123  	certTypeECDSASign      = 64 // A certificate containing an ECDSA-capable public key, signed with ECDSA.
   124  	certTypeRSAFixedECDH   = 65 // A certificate containing an ECDH-capable public key, signed with RSA.
   125  	certTypeECDSAFixedECDH = 66 // A certificate containing an ECDH-capable public key, signed with ECDSA.
   126  
   127  	// Rest of these are reserved by the TLS spec
   128  )
   129  
   130  // Hash functions for TLS 1.2 (See RFC 5246, section A.4.1)
   131  const (
   132  	hashSHA1   uint8 = 2
   133  	hashSHA256 uint8 = 4
   134  	hashSHA384 uint8 = 5
   135  )
   136  
   137  // Signature algorithms for TLS 1.2 (See RFC 5246, section A.4.1)
   138  const (
   139  	signatureRSA   uint8 = 1
   140  	signatureECDSA uint8 = 3
   141  )
   142  
   143  // signatureAndHash mirrors the TLS 1.2, SignatureAndHashAlgorithm struct. See
   144  // RFC 5246, section A.4.1.
   145  type signatureAndHash struct {
   146  	hash, signature uint8
   147  }
   148  
   149  // supportedSignatureAlgorithms contains the signature and hash algorithms that
   150  // the code advertises as supported in a TLS 1.2 ClientHello and in a TLS 1.2
   151  // CertificateRequest.
   152  var supportedSignatureAlgorithms = []signatureAndHash{
   153  	{hashSHA256, signatureRSA},
   154  	{hashSHA256, signatureECDSA},
   155  	{hashSHA384, signatureRSA},
   156  	{hashSHA384, signatureECDSA},
   157  	{hashSHA1, signatureRSA},
   158  	{hashSHA1, signatureECDSA},
   159  }
   160  
   161  // ConnectionState records basic TLS details about the connection.
   162  type ConnectionState struct {
   163  	Version                     uint16                // TLS version used by the connection (e.g. VersionTLS12)
   164  	HandshakeComplete           bool                  // TLS handshake is complete
   165  	DidResume                   bool                  // connection resumes a previous TLS connection
   166  	CipherSuite                 uint16                // cipher suite in use (TLS_RSA_WITH_RC4_128_SHA, ...)
   167  	NegotiatedProtocol          string                // negotiated next protocol (not guaranteed to be from Config.NextProtos)
   168  	NegotiatedProtocolIsMutual  bool                  // negotiated protocol was advertised by server (client side only)
   169  	ServerName                  string                // server name requested by client, if any (server side only)
   170  	PeerCertificates            []*sm2.Certificate   // certificate chain presented by remote peer
   171  	VerifiedChains              [][]*sm2.Certificate // verified chains built from PeerCertificates
   172  	SignedCertificateTimestamps [][]byte              // SCTs from the server, if any
   173  	OCSPResponse                []byte                // stapled OCSP response from server, if any
   174  
   175  	// TLSUnique contains the "tls-unique" channel binding value (see RFC
   176  	// 5929, section 3). For resumed sessions this value will be nil
   177  	// because resumption does not include enough context (see
   178  	// https://mitls.org/pages/attacks/3SHAKE#channelbindings). This will
   179  	// change in future versions of Go once the TLS master-secret fix has
   180  	// been standardized and implemented.
   181  	TLSUnique []byte
   182  }
   183  
   184  // ClientAuthType declares the policy the server will follow for
   185  // TLS Client Authentication.
   186  type ClientAuthType int
   187  
   188  const (
   189  	NoClientCert ClientAuthType = iota
   190  	RequestClientCert
   191  	RequireAnyClientCert
   192  	VerifyClientCertIfGiven
   193  	RequireAndVerifyClientCert
   194  )
   195  
   196  // ClientSessionState contains the state needed by clients to resume TLS
   197  // sessions.
   198  type ClientSessionState struct {
   199  	sessionTicket      []uint8               // Encrypted ticket used for session resumption with server
   200  	vers               uint16                // SSL/TLS version negotiated for the session
   201  	cipherSuite        uint16                // Ciphersuite negotiated for the session
   202  	masterSecret       []byte                // MasterSecret generated by client on a full handshake
   203  	serverCertificates []*sm2.Certificate   // Certificate chain presented by the server
   204  	verifiedChains     [][]*sm2.Certificate // Certificate chains we built for verification
   205  }
   206  
   207  // ClientSessionCache is a cache of ClientSessionState objects that can be used
   208  // by a client to resume a TLS session with a given server. ClientSessionCache
   209  // implementations should expect to be called concurrently from different
   210  // goroutines. Only ticket-based resumption is supported, not SessionID-based
   211  // resumption.
   212  type ClientSessionCache interface {
   213  	// Get searches for a ClientSessionState associated with the given key.
   214  	// On return, ok is true if one was found.
   215  	Get(sessionKey string) (session *ClientSessionState, ok bool)
   216  
   217  	// Put adds the ClientSessionState to the cache with the given key.
   218  	Put(sessionKey string, cs *ClientSessionState)
   219  }
   220  
   221  // SignatureScheme identifies a signature algorithm supported by TLS. See
   222  // https://tools.ietf.org/html/draft-ietf-tls-tls13-18#section-4.2.3.
   223  type SignatureScheme uint16
   224  
   225  const (
   226  	PKCS1WithSHA1   SignatureScheme = 0x0201
   227  	PKCS1WithSHA256 SignatureScheme = 0x0401
   228  	PKCS1WithSHA384 SignatureScheme = 0x0501
   229  	PKCS1WithSHA512 SignatureScheme = 0x0601
   230  
   231  	PSSWithSHA256 SignatureScheme = 0x0804
   232  	PSSWithSHA384 SignatureScheme = 0x0805
   233  	PSSWithSHA512 SignatureScheme = 0x0806
   234  
   235  	ECDSAWithP256AndSHA256 SignatureScheme = 0x0403
   236  	ECDSAWithP384AndSHA384 SignatureScheme = 0x0503
   237  	ECDSAWithP521AndSHA512 SignatureScheme = 0x0603
   238  )
   239  
   240  // ClientHelloInfo contains information from a ClientHello message in order to
   241  // guide certificate selection in the GetCertificate callback.
   242  type ClientHelloInfo struct {
   243  	// CipherSuites lists the CipherSuites supported by the client (e.g.
   244  	// TLS_RSA_WITH_RC4_128_SHA).
   245  	CipherSuites []uint16
   246  
   247  	// ServerName indicates the name of the server requested by the client
   248  	// in order to support virtual hosting. ServerName is only set if the
   249  	// client is using SNI (see
   250  	// http://tools.ietf.org/html/rfc4366#section-3.1).
   251  	ServerName string
   252  
   253  	// SupportedCurves lists the elliptic curves supported by the client.
   254  	// SupportedCurves is set only if the Supported Elliptic Curves
   255  	// Extension is being used (see
   256  	// http://tools.ietf.org/html/rfc4492#section-5.1.1).
   257  	SupportedCurves []CurveID
   258  
   259  	// SupportedPoints lists the point formats supported by the client.
   260  	// SupportedPoints is set only if the Supported Point Formats Extension
   261  	// is being used (see
   262  	// http://tools.ietf.org/html/rfc4492#section-5.1.2).
   263  	SupportedPoints []uint8
   264  
   265  	// SignatureSchemes lists the signature and hash schemes that the client
   266  	// is willing to verify. SignatureSchemes is set only if the Signature
   267  	// Algorithms Extension is being used (see
   268  	// https://tools.ietf.org/html/rfc5246#section-7.4.1.4.1).
   269  	SignatureSchemes []SignatureScheme
   270  
   271  	// SupportedProtos lists the application protocols supported by the client.
   272  	// SupportedProtos is set only if the Application-Layer Protocol
   273  	// Negotiation Extension is being used (see
   274  	// https://tools.ietf.org/html/rfc7301#section-3.1).
   275  	//
   276  	// Servers can select a protocol by setting Config.NextProtos in a
   277  	// GetConfigForClient return value.
   278  	SupportedProtos []string
   279  
   280  	// SupportedVersions lists the TLS versions supported by the client.
   281  	// For TLS versions less than 1.3, this is extrapolated from the max
   282  	// version advertised by the client, so values other than the greatest
   283  	// might be rejected if used.
   284  	SupportedVersions []uint16
   285  
   286  	// Conn is the underlying net.Conn for the connection. Do not read
   287  	// from, or write to, this connection; that will cause the TLS
   288  	// connection to fail.
   289  	Conn net.Conn
   290  }
   291  
   292  // CertificateRequestInfo contains information from a server's
   293  // CertificateRequest message, which is used to demand a certificate and proof
   294  // of control from a client.
   295  type CertificateRequestInfo struct {
   296  	// AcceptableCAs contains zero or more, DER-encoded, X.501
   297  	// Distinguished Names. These are the names of root or intermediate CAs
   298  	// that the server wishes the returned certificate to be signed by. An
   299  	// empty slice indicates that the server has no preference.
   300  	AcceptableCAs [][]byte
   301  
   302  	// SignatureSchemes lists the signature schemes that the server is
   303  	// willing to verify.
   304  	SignatureSchemes []SignatureScheme
   305  }
   306  
   307  // RenegotiationSupport enumerates the different levels of support for TLS
   308  // renegotiation. TLS renegotiation is the act of performing subsequent
   309  // handshakes on a connection after the first. This significantly complicates
   310  // the state machine and has been the source of numerous, subtle security
   311  // issues. Initiating a renegotiation is not supported, but support for
   312  // accepting renegotiation requests may be enabled.
   313  //
   314  // Even when enabled, the server may not change its identity between handshakes
   315  // (i.e. the leaf certificate must be the same). Additionally, concurrent
   316  // handshake and application data flow is not permitted so renegotiation can
   317  // only be used with protocols that synchronise with the renegotiation, such as
   318  // HTTPS.
   319  type RenegotiationSupport int
   320  
   321  const (
   322  	// RenegotiateNever disables renegotiation.
   323  	RenegotiateNever RenegotiationSupport = iota
   324  
   325  	// RenegotiateOnceAsClient allows a remote server to request
   326  	// renegotiation once per connection.
   327  	RenegotiateOnceAsClient
   328  
   329  	// RenegotiateFreelyAsClient allows a remote server to repeatedly
   330  	// request renegotiation.
   331  	RenegotiateFreelyAsClient
   332  )
   333  
   334  // A Config structure is used to configure a TLS client or server.
   335  // After one has been passed to a TLS function it must not be
   336  // modified. A Config may be reused; the tls package will also not
   337  // modify it.
   338  type Config struct {
   339  	// Rand provides the source of entropy for nonces and RSA blinding.
   340  	// If Rand is nil, TLS uses the cryptographic random reader in package
   341  	// crypto/rand.
   342  	// The Reader must be safe for use by multiple goroutines.
   343  	Rand io.Reader
   344  
   345  	// Time returns the current time as the number of seconds since the epoch.
   346  	// If Time is nil, TLS uses time.Now.
   347  	Time func() time.Time
   348  
   349  	// Certificates contains one or more certificate chains to present to
   350  	// the other side of the connection. Server configurations must include
   351  	// at least one certificate or else set GetCertificate. Clients doing
   352  	// client-authentication may set either Certificates or
   353  	// GetClientCertificate.
   354  	Certificates []Certificate
   355  
   356  	// NameToCertificate maps from a certificate name to an element of
   357  	// Certificates. Note that a certificate name can be of the form
   358  	// '*.example.com' and so doesn't have to be a domain name as such.
   359  	// See Config.BuildNameToCertificate
   360  	// The nil value causes the first element of Certificates to be used
   361  	// for all connections.
   362  	NameToCertificate map[string]*Certificate
   363  
   364  	// GetCertificate returns a Certificate based on the given
   365  	// ClientHelloInfo. It will only be called if the client supplies SNI
   366  	// information or if Certificates is empty.
   367  	//
   368  	// If GetCertificate is nil or returns nil, then the certificate is
   369  	// retrieved from NameToCertificate. If NameToCertificate is nil, the
   370  	// first element of Certificates will be used.
   371  	GetCertificate func(*ClientHelloInfo) (*Certificate, error)
   372  
   373  	// GetClientCertificate, if not nil, is called when a server requests a
   374  	// certificate from a client. If set, the contents of Certificates will
   375  	// be ignored.
   376  	//
   377  	// If GetClientCertificate returns an error, the handshake will be
   378  	// aborted and that error will be returned. Otherwise
   379  	// GetClientCertificate must return a non-nil Certificate. If
   380  	// Certificate.Certificate is empty then no certificate will be sent to
   381  	// the server. If this is unacceptable to the server then it may abort
   382  	// the handshake.
   383  	//
   384  	// GetClientCertificate may be called multiple times for the same
   385  	// connection if renegotiation occurs or if TLS 1.3 is in use.
   386  	GetClientCertificate func(*CertificateRequestInfo) (*Certificate, error)
   387  
   388  	// GetConfigForClient, if not nil, is called after a ClientHello is
   389  	// received from a client. It may return a non-nil Config in order to
   390  	// change the Config that will be used to handle this connection. If
   391  	// the returned Config is nil, the original Config will be used. The
   392  	// Config returned by this callback may not be subsequently modified.
   393  	//
   394  	// If GetConfigForClient is nil, the Config passed to Server() will be
   395  	// used for all connections.
   396  	//
   397  	// Uniquely for the fields in the returned Config, session ticket keys
   398  	// will be duplicated from the original Config if not set.
   399  	// Specifically, if SetSessionTicketKeys was called on the original
   400  	// config but not on the returned config then the ticket keys from the
   401  	// original config will be copied into the new config before use.
   402  	// Otherwise, if SessionTicketKey was set in the original config but
   403  	// not in the returned config then it will be copied into the returned
   404  	// config before use. If neither of those cases applies then the key
   405  	// material from the returned config will be used for session tickets.
   406  	GetConfigForClient func(*ClientHelloInfo) (*Config, error)
   407  
   408  	// VerifyPeerCertificate, if not nil, is called after normal
   409  	// certificate verification by either a TLS client or server. It
   410  	// receives the raw ASN.1 certificates provided by the peer and also
   411  	// any verified chains that normal processing found. If it returns a
   412  	// non-nil error, the handshake is aborted and that error results.
   413  	//
   414  	// If normal verification fails then the handshake will abort before
   415  	// considering this callback. If normal verification is disabled by
   416  	// setting InsecureSkipVerify then this callback will be considered but
   417  	// the verifiedChains argument will always be nil.
   418  	VerifyPeerCertificate func(rawCerts [][]byte, verifiedChains [][]*sm2.Certificate) error
   419  
   420  	// RootCAs defines the set of root certificate authorities
   421  	// that clients use when verifying server certificates.
   422  	// If RootCAs is nil, TLS uses the host's root CA set.
   423  	RootCAs *sm2.CertPool
   424  
   425  	// NextProtos is a list of supported, application level protocols.
   426  	NextProtos []string
   427  
   428  	// ServerName is used to verify the hostname on the returned
   429  	// certificates unless InsecureSkipVerify is given. It is also included
   430  	// in the client's handshake to support virtual hosting unless it is
   431  	// an IP address.
   432  	ServerName string
   433  
   434  	// ClientAuth determines the server's policy for
   435  	// TLS Client Authentication. The default is NoClientCert.
   436  	ClientAuth ClientAuthType
   437  
   438  	// ClientCAs defines the set of root certificate authorities
   439  	// that servers use if required to verify a client certificate
   440  	// by the policy in ClientAuth.
   441  	ClientCAs *sm2.CertPool
   442  
   443  	// InsecureSkipVerify controls whether a client verifies the
   444  	// server's certificate chain and host name.
   445  	// If InsecureSkipVerify is true, TLS accepts any certificate
   446  	// presented by the server and any host name in that certificate.
   447  	// In this mode, TLS is susceptible to man-in-the-middle attacks.
   448  	// This should be used only for testing.
   449  	InsecureSkipVerify bool
   450  
   451  	// CipherSuites is a list of supported cipher suites. If CipherSuites
   452  	// is nil, TLS uses a list of suites supported by the implementation.
   453  	CipherSuites []uint16
   454  
   455  	// PreferServerCipherSuites controls whether the server selects the
   456  	// client's most preferred ciphersuite, or the server's most preferred
   457  	// ciphersuite. If true then the server's preference, as expressed in
   458  	// the order of elements in CipherSuites, is used.
   459  	PreferServerCipherSuites bool
   460  
   461  	// SessionTicketsDisabled may be set to true to disable session ticket
   462  	// (resumption) support.
   463  	SessionTicketsDisabled bool
   464  
   465  	// SessionTicketKey is used by TLS servers to provide session
   466  	// resumption. See RFC 5077. If zero, it will be filled with
   467  	// random data before the first server handshake.
   468  	//
   469  	// If multiple servers are terminating connections for the same host
   470  	// they should all have the same SessionTicketKey. If the
   471  	// SessionTicketKey leaks, previously recorded and future TLS
   472  	// connections using that key are compromised.
   473  	SessionTicketKey [32]byte
   474  
   475  	// SessionCache is a cache of ClientSessionState entries for TLS session
   476  	// resumption.
   477  	ClientSessionCache ClientSessionCache
   478  
   479  	// MinVersion contains the minimum SSL/TLS version that is acceptable.
   480  	// If zero, then TLS 1.0 is taken as the minimum.
   481  	MinVersion uint16
   482  
   483  	// MaxVersion contains the maximum SSL/TLS version that is acceptable.
   484  	// If zero, then the maximum version supported by this package is used,
   485  	// which is currently TLS 1.2.
   486  	MaxVersion uint16
   487  
   488  	// CurvePreferences contains the elliptic curves that will be used in
   489  	// an ECDHE handshake, in preference order. If empty, the default will
   490  	// be used.
   491  	CurvePreferences []CurveID
   492  
   493  	// DynamicRecordSizingDisabled disables adaptive sizing of TLS records.
   494  	// When true, the largest possible TLS record size is always used. When
   495  	// false, the size of TLS records may be adjusted in an attempt to
   496  	// improve latency.
   497  	DynamicRecordSizingDisabled bool
   498  
   499  	// Renegotiation controls what types of renegotiation are supported.
   500  	// The default, none, is correct for the vast majority of applications.
   501  	Renegotiation RenegotiationSupport
   502  
   503  	// KeyLogWriter optionally specifies a destination for TLS master secrets
   504  	// in NSS key log format that can be used to allow external programs
   505  	// such as Wireshark to decrypt TLS connections.
   506  	// See https://developer.mozilla.org/en-US/docs/Mozilla/Projects/NSS/Key_Log_Format.
   507  	// Use of KeyLogWriter compromises security and should only be
   508  	// used for debugging.
   509  	KeyLogWriter io.Writer
   510  
   511  	serverInitOnce sync.Once // guards calling (*Config).serverInit
   512  
   513  	// mutex protects sessionTicketKeys.
   514  	mutex sync.RWMutex
   515  	// sessionTicketKeys contains zero or more ticket keys. If the length
   516  	// is zero, SessionTicketsDisabled must be true. The first key is used
   517  	// for new tickets and any subsequent keys can be used to decrypt old
   518  	// tickets.
   519  	sessionTicketKeys []ticketKey
   520  }
   521  
   522  // ticketKeyNameLen is the number of bytes of identifier that is prepended to
   523  // an encrypted session ticket in order to identify the key used to encrypt it.
   524  const ticketKeyNameLen = 16
   525  
   526  // ticketKey is the internal representation of a session ticket key.
   527  type ticketKey struct {
   528  	// keyName is an opaque byte string that serves to identify the session
   529  	// ticket key. It's exposed as plaintext in every session ticket.
   530  	keyName [ticketKeyNameLen]byte
   531  	aesKey  [16]byte
   532  	hmacKey [16]byte
   533  }
   534  
   535  // ticketKeyFromBytes converts from the external representation of a session
   536  // ticket key to a ticketKey. Externally, session ticket keys are 32 random
   537  // bytes and this function expands that into sufficient name and key material.
   538  func ticketKeyFromBytes(b [32]byte) (key ticketKey) {
   539  	hashed := sha512.Sum512(b[:])
   540  	copy(key.keyName[:], hashed[:ticketKeyNameLen])
   541  	copy(key.aesKey[:], hashed[ticketKeyNameLen:ticketKeyNameLen+16])
   542  	copy(key.hmacKey[:], hashed[ticketKeyNameLen+16:ticketKeyNameLen+32])
   543  	return key
   544  }
   545  
   546  // Clone returns a shallow clone of c. It is safe to clone a Config that is
   547  // being used concurrently by a TLS client or server.
   548  func (c *Config) Clone() *Config {
   549  	// Running serverInit ensures that it's safe to read
   550  	// SessionTicketsDisabled.
   551  	c.serverInitOnce.Do(func() { c.serverInit(nil) })
   552  
   553  	var sessionTicketKeys []ticketKey
   554  	c.mutex.RLock()
   555  	sessionTicketKeys = c.sessionTicketKeys
   556  	c.mutex.RUnlock()
   557  
   558  	return &Config{
   559  		Rand:                        c.Rand,
   560  		Time:                        c.Time,
   561  		Certificates:                c.Certificates,
   562  		NameToCertificate:           c.NameToCertificate,
   563  		GetCertificate:              c.GetCertificate,
   564  		GetClientCertificate:        c.GetClientCertificate,
   565  		GetConfigForClient:          c.GetConfigForClient,
   566  		VerifyPeerCertificate:       c.VerifyPeerCertificate,
   567  		RootCAs:                     c.RootCAs,
   568  		NextProtos:                  c.NextProtos,
   569  		ServerName:                  c.ServerName,
   570  		ClientAuth:                  c.ClientAuth,
   571  		ClientCAs:                   c.ClientCAs,
   572  		InsecureSkipVerify:          c.InsecureSkipVerify,
   573  		CipherSuites:                c.CipherSuites,
   574  		PreferServerCipherSuites:    c.PreferServerCipherSuites,
   575  		SessionTicketsDisabled:      c.SessionTicketsDisabled,
   576  		SessionTicketKey:            c.SessionTicketKey,
   577  		ClientSessionCache:          c.ClientSessionCache,
   578  		MinVersion:                  c.MinVersion,
   579  		MaxVersion:                  c.MaxVersion,
   580  		CurvePreferences:            c.CurvePreferences,
   581  		DynamicRecordSizingDisabled: c.DynamicRecordSizingDisabled,
   582  		Renegotiation:               c.Renegotiation,
   583  		KeyLogWriter:                c.KeyLogWriter,
   584  		sessionTicketKeys:           sessionTicketKeys,
   585  	}
   586  }
   587  
   588  // serverInit is run under c.serverInitOnce to do initialization of c. If c was
   589  // returned by a GetConfigForClient callback then the argument should be the
   590  // Config that was passed to Server, otherwise it should be nil.
   591  func (c *Config) serverInit(originalConfig *Config) {
   592  	if c.SessionTicketsDisabled || len(c.ticketKeys()) != 0 {
   593  		return
   594  	}
   595  
   596  	alreadySet := false
   597  	for _, b := range c.SessionTicketKey {
   598  		if b != 0 {
   599  			alreadySet = true
   600  			break
   601  		}
   602  	}
   603  
   604  	if !alreadySet {
   605  		if originalConfig != nil {
   606  			copy(c.SessionTicketKey[:], originalConfig.SessionTicketKey[:])
   607  		} else if _, err := io.ReadFull(c.rand(), c.SessionTicketKey[:]); err != nil {
   608  			c.SessionTicketsDisabled = true
   609  			return
   610  		}
   611  	}
   612  
   613  	if originalConfig != nil {
   614  		originalConfig.mutex.RLock()
   615  		c.sessionTicketKeys = originalConfig.sessionTicketKeys
   616  		originalConfig.mutex.RUnlock()
   617  	} else {
   618  		c.sessionTicketKeys = []ticketKey{ticketKeyFromBytes(c.SessionTicketKey)}
   619  	}
   620  }
   621  
   622  func (c *Config) ticketKeys() []ticketKey {
   623  	c.mutex.RLock()
   624  	// c.sessionTicketKeys is constant once created. SetSessionTicketKeys
   625  	// will only update it by replacing it with a new value.
   626  	ret := c.sessionTicketKeys
   627  	c.mutex.RUnlock()
   628  	return ret
   629  }
   630  
   631  // SetSessionTicketKeys updates the session ticket keys for a server. The first
   632  // key will be used when creating new tickets, while all keys can be used for
   633  // decrypting tickets. It is safe to call this function while the server is
   634  // running in order to rotate the session ticket keys. The function will panic
   635  // if keys is empty.
   636  func (c *Config) SetSessionTicketKeys(keys [][32]byte) {
   637  	if len(keys) == 0 {
   638  		panic("tls: keys must have at least one key")
   639  	}
   640  
   641  	newKeys := make([]ticketKey, len(keys))
   642  	for i, bytes := range keys {
   643  		newKeys[i] = ticketKeyFromBytes(bytes)
   644  	}
   645  
   646  	c.mutex.Lock()
   647  	c.sessionTicketKeys = newKeys
   648  	c.mutex.Unlock()
   649  }
   650  
   651  func (c *Config) rand() io.Reader {
   652  	r := c.Rand
   653  	if r == nil {
   654  		return rand.Reader
   655  	}
   656  	return r
   657  }
   658  
   659  func (c *Config) time() time.Time {
   660  	t := c.Time
   661  	if t == nil {
   662  		t = time.Now
   663  	}
   664  	return t()
   665  }
   666  
   667  func (c *Config) cipherSuites() []uint16 {
   668  	s := c.CipherSuites
   669  	if s == nil {
   670  		s = defaultCipherSuites()
   671  	}
   672  	return s
   673  }
   674  
   675  func (c *Config) minVersion() uint16 {
   676  	if c == nil || c.MinVersion == 0 {
   677  		return minVersion
   678  	}
   679  	return c.MinVersion
   680  }
   681  
   682  func (c *Config) maxVersion() uint16 {
   683  	if c == nil || c.MaxVersion == 0 {
   684  		return maxVersion
   685  	}
   686  	return c.MaxVersion
   687  }
   688  
   689  var defaultCurvePreferences = []CurveID{X25519, CurveP256, CurveP384, CurveP521}
   690  
   691  func (c *Config) curvePreferences() []CurveID {
   692  	if c == nil || len(c.CurvePreferences) == 0 {
   693  		return defaultCurvePreferences
   694  	}
   695  	return c.CurvePreferences
   696  }
   697  
   698  // mutualVersion returns the protocol version to use given the advertised
   699  // version of the peer.
   700  func (c *Config) mutualVersion(vers uint16) (uint16, bool) {
   701  	minVersion := c.minVersion()
   702  	maxVersion := c.maxVersion()
   703  
   704  	if vers < minVersion {
   705  		return 0, false
   706  	}
   707  	if vers > maxVersion {
   708  		vers = maxVersion
   709  	}
   710  	return vers, true
   711  }
   712  
   713  // getCertificate returns the best certificate for the given ClientHelloInfo,
   714  // defaulting to the first element of c.Certificates.
   715  func (c *Config) getCertificate(clientHello *ClientHelloInfo) (*Certificate, error) {
   716  	if c.GetCertificate != nil &&
   717  		(len(c.Certificates) == 0 || len(clientHello.ServerName) > 0) {
   718  		cert, err := c.GetCertificate(clientHello)
   719  		if cert != nil || err != nil {
   720  			return cert, err
   721  		}
   722  	}
   723  
   724  	if len(c.Certificates) == 0 {
   725  		return nil, errors.New("tls: no certificates configured")
   726  	}
   727  
   728  	if len(c.Certificates) == 1 || c.NameToCertificate == nil {
   729  		// There's only one choice, so no point doing any work.
   730  		return &c.Certificates[0], nil
   731  	}
   732  
   733  	name := strings.ToLower(clientHello.ServerName)
   734  	for len(name) > 0 && name[len(name)-1] == '.' {
   735  		name = name[:len(name)-1]
   736  	}
   737  
   738  	if cert, ok := c.NameToCertificate[name]; ok {
   739  		return cert, nil
   740  	}
   741  
   742  	// try replacing labels in the name with wildcards until we get a
   743  	// match.
   744  	labels := strings.Split(name, ".")
   745  	for i := range labels {
   746  		labels[i] = "*"
   747  		candidate := strings.Join(labels, ".")
   748  		if cert, ok := c.NameToCertificate[candidate]; ok {
   749  			return cert, nil
   750  		}
   751  	}
   752  
   753  	// If nothing matches, return the first certificate.
   754  	return &c.Certificates[0], nil
   755  }
   756  
   757  // BuildNameToCertificate parses c.Certificates and builds c.NameToCertificate
   758  // from the CommonName and SubjectAlternateName fields of each of the leaf
   759  // certificates.
   760  func (c *Config) BuildNameToCertificate() {
   761  	c.NameToCertificate = make(map[string]*Certificate)
   762  	for i := range c.Certificates {
   763  		cert := &c.Certificates[i]
   764  		x509Cert, err := sm2.ParseCertificate(cert.Certificate[0])
   765  		if err != nil {
   766  			continue
   767  		}
   768  		if len(x509Cert.Subject.CommonName) > 0 {
   769  			c.NameToCertificate[x509Cert.Subject.CommonName] = cert
   770  		}
   771  		for _, san := range x509Cert.DNSNames {
   772  			c.NameToCertificate[san] = cert
   773  		}
   774  	}
   775  }
   776  
   777  // writeKeyLog logs client random and master secret if logging was enabled by
   778  // setting c.KeyLogWriter.
   779  func (c *Config) writeKeyLog(clientRandom, masterSecret []byte) error {
   780  	if c.KeyLogWriter == nil {
   781  		return nil
   782  	}
   783  
   784  	logLine := []byte(fmt.Sprintf("CLIENT_RANDOM %x %x\n", clientRandom, masterSecret))
   785  
   786  	writerMutex.Lock()
   787  	_, err := c.KeyLogWriter.Write(logLine)
   788  	writerMutex.Unlock()
   789  
   790  	return err
   791  }
   792  
   793  // writerMutex protects all KeyLogWriters globally. It is rarely enabled,
   794  // and is only for debugging, so a global mutex saves space.
   795  var writerMutex sync.Mutex
   796  
   797  // A Certificate is a chain of one or more certificates, leaf first.
   798  type Certificate struct {
   799  	Certificate [][]byte
   800  	// PrivateKey contains the private key corresponding to the public key
   801  	// in Leaf. For a server, this must implement crypto.Signer and/or
   802  	// crypto.Decrypter, with an RSA or ECDSA PublicKey. For a client
   803  	// (performing client authentication), this must be a crypto.Signer
   804  	// with an RSA or ECDSA PublicKey.
   805  	PrivateKey crypto.PrivateKey
   806  	// OCSPStaple contains an optional OCSP response which will be served
   807  	// to clients that request it.
   808  	OCSPStaple []byte
   809  	// SignedCertificateTimestamps contains an optional list of Signed
   810  	// Certificate Timestamps which will be served to clients that request it.
   811  	SignedCertificateTimestamps [][]byte
   812  	// Leaf is the parsed form of the leaf certificate, which may be
   813  	// initialized using x509.ParseCertificate to reduce per-handshake
   814  	// processing for TLS clients doing client authentication. If nil, the
   815  	// leaf certificate will be parsed as needed.
   816  	Leaf *sm2.Certificate
   817  }
   818  
   819  type handshakeMessage interface {
   820  	marshal() []byte
   821  	unmarshal([]byte) bool
   822  }
   823  
   824  // lruSessionCache is a ClientSessionCache implementation that uses an LRU
   825  // caching strategy.
   826  type lruSessionCache struct {
   827  	sync.Mutex
   828  
   829  	m        map[string]*list.Element
   830  	q        *list.List
   831  	capacity int
   832  }
   833  
   834  type lruSessionCacheEntry struct {
   835  	sessionKey string
   836  	state      *ClientSessionState
   837  }
   838  
   839  // NewLRUClientSessionCache returns a ClientSessionCache with the given
   840  // capacity that uses an LRU strategy. If capacity is < 1, a default capacity
   841  // is used instead.
   842  func NewLRUClientSessionCache(capacity int) ClientSessionCache {
   843  	const defaultSessionCacheCapacity = 64
   844  
   845  	if capacity < 1 {
   846  		capacity = defaultSessionCacheCapacity
   847  	}
   848  	return &lruSessionCache{
   849  		m:        make(map[string]*list.Element),
   850  		q:        list.New(),
   851  		capacity: capacity,
   852  	}
   853  }
   854  
   855  // Put adds the provided (sessionKey, cs) pair to the cache.
   856  func (c *lruSessionCache) Put(sessionKey string, cs *ClientSessionState) {
   857  	c.Lock()
   858  	defer c.Unlock()
   859  
   860  	if elem, ok := c.m[sessionKey]; ok {
   861  		entry := elem.Value.(*lruSessionCacheEntry)
   862  		entry.state = cs
   863  		c.q.MoveToFront(elem)
   864  		return
   865  	}
   866  
   867  	if c.q.Len() < c.capacity {
   868  		entry := &lruSessionCacheEntry{sessionKey, cs}
   869  		c.m[sessionKey] = c.q.PushFront(entry)
   870  		return
   871  	}
   872  
   873  	elem := c.q.Back()
   874  	entry := elem.Value.(*lruSessionCacheEntry)
   875  	delete(c.m, entry.sessionKey)
   876  	entry.sessionKey = sessionKey
   877  	entry.state = cs
   878  	c.q.MoveToFront(elem)
   879  	c.m[sessionKey] = elem
   880  }
   881  
   882  // Get returns the ClientSessionState value associated with a given key. It
   883  // returns (nil, false) if no value is found.
   884  func (c *lruSessionCache) Get(sessionKey string) (*ClientSessionState, bool) {
   885  	c.Lock()
   886  	defer c.Unlock()
   887  
   888  	if elem, ok := c.m[sessionKey]; ok {
   889  		c.q.MoveToFront(elem)
   890  		return elem.Value.(*lruSessionCacheEntry).state, true
   891  	}
   892  	return nil, false
   893  }
   894  
   895  // TODO(jsing): Make these available to both crypto/x509 and crypto/tls.
   896  type dsaSignature struct {
   897  	R, S *big.Int
   898  }
   899  
   900  type ecdsaSignature dsaSignature
   901  
   902  var emptyConfig Config
   903  
   904  func defaultConfig() *Config {
   905  	return &emptyConfig
   906  }
   907  
   908  var (
   909  	once                   sync.Once
   910  	varDefaultCipherSuites []uint16
   911  )
   912  
   913  func defaultCipherSuites() []uint16 {
   914  	once.Do(initDefaultCipherSuites)
   915  	return varDefaultCipherSuites
   916  }
   917  
   918  func initDefaultCipherSuites() {
   919  	var topCipherSuites []uint16
   920  	if cipherhw.AESGCMSupport() {
   921  		// If AES-GCM hardware is provided then prioritise AES-GCM
   922  		// cipher suites.
   923  		topCipherSuites = []uint16{
   924  			TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256,
   925  			TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384,
   926  			TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256,
   927  			TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384,
   928  			TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305,
   929  			TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305,
   930  		}
   931  	} else {
   932  		// Without AES-GCM hardware, we put the ChaCha20-Poly1305
   933  		// cipher suites first.
   934  		topCipherSuites = []uint16{
   935  			TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305,
   936  			TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305,
   937  			TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256,
   938  			TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384,
   939  			TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256,
   940  			TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384,
   941  		}
   942  	}
   943  
   944  	varDefaultCipherSuites = make([]uint16, 0, len(cipherSuites))
   945  	varDefaultCipherSuites = append(varDefaultCipherSuites, topCipherSuites...)
   946  
   947  NextCipherSuite:
   948  	for _, suite := range cipherSuites {
   949  		if suite.flags&suiteDefaultOff != 0 {
   950  			continue
   951  		}
   952  		for _, existing := range varDefaultCipherSuites {
   953  			if existing == suite.id {
   954  				continue NextCipherSuite
   955  			}
   956  		}
   957  		varDefaultCipherSuites = append(varDefaultCipherSuites, suite.id)
   958  	}
   959  }
   960  
   961  func unexpectedMessageError(wanted, got interface{}) error {
   962  	return fmt.Errorf("tls: received unexpected handshake message of type %T when waiting for %T", got, wanted)
   963  }
   964  
   965  func isSupportedSignatureAndHash(sigHash signatureAndHash, sigHashes []signatureAndHash) bool {
   966  	for _, s := range sigHashes {
   967  		if s == sigHash {
   968  			return true
   969  		}
   970  	}
   971  	return false
   972  }