| // 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 main |
| |
| import ( |
| "container/list" |
| "crypto" |
| "crypto/rand" |
| "crypto/x509" |
| "fmt" |
| "io" |
| "math/big" |
| "strings" |
| "sync" |
| "time" |
| ) |
| |
| const ( |
| VersionSSL30 = 0x0300 |
| VersionTLS10 = 0x0301 |
| VersionTLS11 = 0x0302 |
| VersionTLS12 = 0x0303 |
| ) |
| |
| const ( |
| maxPlaintext = 16384 // maximum plaintext payload length |
| maxCiphertext = 16384 + 2048 // maximum ciphertext payload length |
| recordHeaderLen = 5 // record header length |
| maxHandshake = 65536 // maximum handshake we support (protocol max is 16 MB) |
| |
| minVersion = VersionSSL30 |
| maxVersion = VersionTLS12 |
| ) |
| |
| // TLS record types. |
| type recordType uint8 |
| |
| const ( |
| recordTypeChangeCipherSpec recordType = 20 |
| recordTypeAlert recordType = 21 |
| recordTypeHandshake recordType = 22 |
| recordTypeApplicationData recordType = 23 |
| ) |
| |
| // TLS handshake message types. |
| const ( |
| typeClientHello uint8 = 1 |
| typeServerHello uint8 = 2 |
| typeNewSessionTicket uint8 = 4 |
| typeCertificate uint8 = 11 |
| typeServerKeyExchange uint8 = 12 |
| typeCertificateRequest uint8 = 13 |
| typeServerHelloDone uint8 = 14 |
| typeCertificateVerify uint8 = 15 |
| typeClientKeyExchange uint8 = 16 |
| typeFinished uint8 = 20 |
| typeCertificateStatus uint8 = 22 |
| typeNextProtocol uint8 = 67 // Not IANA assigned |
| ) |
| |
| // TLS compression types. |
| const ( |
| compressionNone uint8 = 0 |
| ) |
| |
| // TLS extension numbers |
| const ( |
| extensionServerName uint16 = 0 |
| extensionStatusRequest uint16 = 5 |
| extensionSupportedCurves uint16 = 10 |
| extensionSupportedPoints uint16 = 11 |
| extensionSignatureAlgorithms uint16 = 13 |
| extensionSessionTicket uint16 = 35 |
| extensionNextProtoNeg uint16 = 13172 // not IANA assigned |
| extensionRenegotiationInfo uint16 = 0xff01 |
| ) |
| |
| // TLS signaling cipher suite values |
| const ( |
| scsvRenegotiation uint16 = 0x00ff |
| ) |
| |
| // CurveID is the type of a TLS identifier for an elliptic curve. See |
| // http://www.iana.org/assignments/tls-parameters/tls-parameters.xml#tls-parameters-8 |
| type CurveID uint16 |
| |
| const ( |
| CurveP256 CurveID = 23 |
| CurveP384 CurveID = 24 |
| CurveP521 CurveID = 25 |
| ) |
| |
| // TLS Elliptic Curve Point Formats |
| // http://www.iana.org/assignments/tls-parameters/tls-parameters.xml#tls-parameters-9 |
| const ( |
| pointFormatUncompressed uint8 = 0 |
| ) |
| |
| // TLS CertificateStatusType (RFC 3546) |
| const ( |
| statusTypeOCSP uint8 = 1 |
| ) |
| |
| // Certificate types (for certificateRequestMsg) |
| const ( |
| CertTypeRSASign = 1 // A certificate containing an RSA key |
| CertTypeDSSSign = 2 // A certificate containing a DSA key |
| CertTypeRSAFixedDH = 3 // A certificate containing a static DH key |
| CertTypeDSSFixedDH = 4 // A certificate containing a static DH key |
| |
| // See RFC4492 sections 3 and 5.5. |
| CertTypeECDSASign = 64 // A certificate containing an ECDSA-capable public key, signed with ECDSA. |
| CertTypeRSAFixedECDH = 65 // A certificate containing an ECDH-capable public key, signed with RSA. |
| CertTypeECDSAFixedECDH = 66 // A certificate containing an ECDH-capable public key, signed with ECDSA. |
| |
| // Rest of these are reserved by the TLS spec |
| ) |
| |
| // Hash functions for TLS 1.2 (See RFC 5246, section A.4.1) |
| const ( |
| hashSHA1 uint8 = 2 |
| hashSHA256 uint8 = 4 |
| ) |
| |
| // Signature algorithms for TLS 1.2 (See RFC 5246, section A.4.1) |
| const ( |
| signatureRSA uint8 = 1 |
| signatureECDSA uint8 = 3 |
| ) |
| |
| // signatureAndHash mirrors the TLS 1.2, SignatureAndHashAlgorithm struct. See |
| // RFC 5246, section A.4.1. |
| type signatureAndHash struct { |
| hash, signature uint8 |
| } |
| |
| // supportedSKXSignatureAlgorithms contains the signature and hash algorithms |
| // that the code advertises as supported in a TLS 1.2 ClientHello. |
| var supportedSKXSignatureAlgorithms = []signatureAndHash{ |
| {hashSHA256, signatureRSA}, |
| {hashSHA256, signatureECDSA}, |
| {hashSHA1, signatureRSA}, |
| {hashSHA1, signatureECDSA}, |
| } |
| |
| // supportedClientCertSignatureAlgorithms contains the signature and hash |
| // algorithms that the code advertises as supported in a TLS 1.2 |
| // CertificateRequest. |
| var supportedClientCertSignatureAlgorithms = []signatureAndHash{ |
| {hashSHA256, signatureRSA}, |
| {hashSHA256, signatureECDSA}, |
| } |
| |
| // ConnectionState records basic TLS details about the connection. |
| type ConnectionState struct { |
| Version uint16 // TLS version used by the connection (e.g. VersionTLS12) |
| HandshakeComplete bool // TLS handshake is complete |
| DidResume bool // connection resumes a previous TLS connection |
| CipherSuite uint16 // cipher suite in use (TLS_RSA_WITH_RC4_128_SHA, ...) |
| NegotiatedProtocol string // negotiated next protocol (from Config.NextProtos) |
| NegotiatedProtocolIsMutual bool // negotiated protocol was advertised by server |
| ServerName string // server name requested by client, if any (server side only) |
| PeerCertificates []*x509.Certificate // certificate chain presented by remote peer |
| VerifiedChains [][]*x509.Certificate // verified chains built from PeerCertificates |
| } |
| |
| // ClientAuthType declares the policy the server will follow for |
| // TLS Client Authentication. |
| type ClientAuthType int |
| |
| const ( |
| NoClientCert ClientAuthType = iota |
| RequestClientCert |
| RequireAnyClientCert |
| VerifyClientCertIfGiven |
| RequireAndVerifyClientCert |
| ) |
| |
| // ClientSessionState contains the state needed by clients to resume TLS |
| // sessions. |
| type ClientSessionState struct { |
| sessionTicket []uint8 // Encrypted ticket used for session resumption with server |
| vers uint16 // SSL/TLS version negotiated for the session |
| cipherSuite uint16 // Ciphersuite negotiated for the session |
| masterSecret []byte // MasterSecret generated by client on a full handshake |
| serverCertificates []*x509.Certificate // Certificate chain presented by the server |
| } |
| |
| // ClientSessionCache is a cache of ClientSessionState objects that can be used |
| // by a client to resume a TLS session with a given server. ClientSessionCache |
| // implementations should expect to be called concurrently from different |
| // goroutines. |
| type ClientSessionCache interface { |
| // Get searches for a ClientSessionState associated with the given key. |
| // On return, ok is true if one was found. |
| Get(sessionKey string) (session *ClientSessionState, ok bool) |
| |
| // Put adds the ClientSessionState to the cache with the given key. |
| Put(sessionKey string, cs *ClientSessionState) |
| } |
| |
| // A Config structure is used to configure a TLS client or server. |
| // After one has been passed to a TLS function it must not be |
| // modified. A Config may be reused; the tls package will also not |
| // modify it. |
| type Config struct { |
| // Rand provides the source of entropy for nonces and RSA blinding. |
| // If Rand is nil, TLS uses the cryptographic random reader in package |
| // crypto/rand. |
| // The Reader must be safe for use by multiple goroutines. |
| Rand io.Reader |
| |
| // Time returns the current time as the number of seconds since the epoch. |
| // If Time is nil, TLS uses time.Now. |
| Time func() time.Time |
| |
| // Certificates contains one or more certificate chains |
| // to present to the other side of the connection. |
| // Server configurations must include at least one certificate. |
| Certificates []Certificate |
| |
| // NameToCertificate maps from a certificate name to an element of |
| // Certificates. Note that a certificate name can be of the form |
| // '*.example.com' and so doesn't have to be a domain name as such. |
| // See Config.BuildNameToCertificate |
| // The nil value causes the first element of Certificates to be used |
| // for all connections. |
| NameToCertificate map[string]*Certificate |
| |
| // RootCAs defines the set of root certificate authorities |
| // that clients use when verifying server certificates. |
| // If RootCAs is nil, TLS uses the host's root CA set. |
| RootCAs *x509.CertPool |
| |
| // NextProtos is a list of supported, application level protocols. |
| NextProtos []string |
| |
| // ServerName is used to verify the hostname on the returned |
| // certificates unless InsecureSkipVerify is given. It is also included |
| // in the client's handshake to support virtual hosting. |
| ServerName string |
| |
| // ClientAuth determines the server's policy for |
| // TLS Client Authentication. The default is NoClientCert. |
| ClientAuth ClientAuthType |
| |
| // ClientCAs defines the set of root certificate authorities |
| // that servers use if required to verify a client certificate |
| // by the policy in ClientAuth. |
| ClientCAs *x509.CertPool |
| |
| // ClientCertificateTypes defines the set of allowed client certificate |
| // types. The default is CertTypeRSASign and CertTypeECDSASign. |
| ClientCertificateTypes []byte |
| |
| // InsecureSkipVerify controls whether a client verifies the |
| // server's certificate chain and host name. |
| // If InsecureSkipVerify is true, TLS accepts any certificate |
| // presented by the server and any host name in that certificate. |
| // In this mode, TLS is susceptible to man-in-the-middle attacks. |
| // This should be used only for testing. |
| InsecureSkipVerify bool |
| |
| // CipherSuites is a list of supported cipher suites. If CipherSuites |
| // is nil, TLS uses a list of suites supported by the implementation. |
| CipherSuites []uint16 |
| |
| // PreferServerCipherSuites controls whether the server selects the |
| // client's most preferred ciphersuite, or the server's most preferred |
| // ciphersuite. If true then the server's preference, as expressed in |
| // the order of elements in CipherSuites, is used. |
| PreferServerCipherSuites bool |
| |
| // SessionTicketsDisabled may be set to true to disable session ticket |
| // (resumption) support. |
| SessionTicketsDisabled bool |
| |
| // SessionTicketKey is used by TLS servers to provide session |
| // resumption. See RFC 5077. If zero, it will be filled with |
| // random data before the first server handshake. |
| // |
| // If multiple servers are terminating connections for the same host |
| // they should all have the same SessionTicketKey. If the |
| // SessionTicketKey leaks, previously recorded and future TLS |
| // connections using that key are compromised. |
| SessionTicketKey [32]byte |
| |
| // SessionCache is a cache of ClientSessionState entries for TLS session |
| // resumption. |
| ClientSessionCache ClientSessionCache |
| |
| // MinVersion contains the minimum SSL/TLS version that is acceptable. |
| // If zero, then SSLv3 is taken as the minimum. |
| MinVersion uint16 |
| |
| // MaxVersion contains the maximum SSL/TLS version that is acceptable. |
| // If zero, then the maximum version supported by this package is used, |
| // which is currently TLS 1.2. |
| MaxVersion uint16 |
| |
| // CurvePreferences contains the elliptic curves that will be used in |
| // an ECDHE handshake, in preference order. If empty, the default will |
| // be used. |
| CurvePreferences []CurveID |
| |
| // Bugs specifies optional misbehaviour to be used for testing other |
| // implementations. |
| Bugs ProtocolBugs |
| |
| serverInitOnce sync.Once // guards calling (*Config).serverInit |
| } |
| |
| type BadValue int |
| |
| const ( |
| BadValueNone BadValue = iota |
| BadValueNegative |
| BadValueZero |
| BadValueLimit |
| BadValueLarge |
| NumBadValues |
| ) |
| |
| type ProtocolBugs struct { |
| // InvalidSKXSignature specifies that the signature in a |
| // ServerKeyExchange message should be invalid. |
| InvalidSKXSignature bool |
| |
| // InvalidSKXCurve causes the curve ID in the ServerKeyExchange message |
| // to be wrong. |
| InvalidSKXCurve bool |
| |
| // BadECDSAR controls ways in which the 'r' value of an ECDSA signature |
| // can be invalid. |
| BadECDSAR BadValue |
| BadECDSAS BadValue |
| |
| // MaxPadding causes CBC records to have the maximum possible padding. |
| MaxPadding bool |
| // PaddingFirstByteBad causes the first byte of the padding to be |
| // incorrect. |
| PaddingFirstByteBad bool |
| // PaddingFirstByteBadIf255 causes the first byte of padding to be |
| // incorrect if there's a maximum amount of padding (i.e. 255 bytes). |
| PaddingFirstByteBadIf255 bool |
| |
| // FailIfNotFallbackSCSV causes a server handshake to fail if the |
| // client doesn't send the fallback SCSV value. |
| FailIfNotFallbackSCSV bool |
| |
| // DuplicateExtension causes an extra empty extension of bogus type to |
| // be emitted in either the ClientHello or the ServerHello. |
| DuplicateExtension bool |
| } |
| |
| func (c *Config) serverInit() { |
| if c.SessionTicketsDisabled { |
| return |
| } |
| |
| // If the key has already been set then we have nothing to do. |
| for _, b := range c.SessionTicketKey { |
| if b != 0 { |
| return |
| } |
| } |
| |
| if _, err := io.ReadFull(c.rand(), c.SessionTicketKey[:]); err != nil { |
| c.SessionTicketsDisabled = true |
| } |
| } |
| |
| func (c *Config) rand() io.Reader { |
| r := c.Rand |
| if r == nil { |
| return rand.Reader |
| } |
| return r |
| } |
| |
| func (c *Config) time() time.Time { |
| t := c.Time |
| if t == nil { |
| t = time.Now |
| } |
| return t() |
| } |
| |
| func (c *Config) cipherSuites() []uint16 { |
| s := c.CipherSuites |
| if s == nil { |
| s = defaultCipherSuites() |
| } |
| return s |
| } |
| |
| func (c *Config) minVersion() uint16 { |
| if c == nil || c.MinVersion == 0 { |
| return minVersion |
| } |
| return c.MinVersion |
| } |
| |
| func (c *Config) maxVersion() uint16 { |
| if c == nil || c.MaxVersion == 0 { |
| return maxVersion |
| } |
| return c.MaxVersion |
| } |
| |
| var defaultCurvePreferences = []CurveID{CurveP256, CurveP384, CurveP521} |
| |
| func (c *Config) curvePreferences() []CurveID { |
| if c == nil || len(c.CurvePreferences) == 0 { |
| return defaultCurvePreferences |
| } |
| return c.CurvePreferences |
| } |
| |
| // mutualVersion returns the protocol version to use given the advertised |
| // version of the peer. |
| func (c *Config) mutualVersion(vers uint16) (uint16, bool) { |
| minVersion := c.minVersion() |
| maxVersion := c.maxVersion() |
| |
| if vers < minVersion { |
| return 0, false |
| } |
| if vers > maxVersion { |
| vers = maxVersion |
| } |
| return vers, true |
| } |
| |
| // getCertificateForName returns the best certificate for the given name, |
| // defaulting to the first element of c.Certificates if there are no good |
| // options. |
| func (c *Config) getCertificateForName(name string) *Certificate { |
| if len(c.Certificates) == 1 || c.NameToCertificate == nil { |
| // There's only one choice, so no point doing any work. |
| return &c.Certificates[0] |
| } |
| |
| name = strings.ToLower(name) |
| for len(name) > 0 && name[len(name)-1] == '.' { |
| name = name[:len(name)-1] |
| } |
| |
| if cert, ok := c.NameToCertificate[name]; ok { |
| return cert |
| } |
| |
| // try replacing labels in the name with wildcards until we get a |
| // match. |
| labels := strings.Split(name, ".") |
| for i := range labels { |
| labels[i] = "*" |
| candidate := strings.Join(labels, ".") |
| if cert, ok := c.NameToCertificate[candidate]; ok { |
| return cert |
| } |
| } |
| |
| // If nothing matches, return the first certificate. |
| return &c.Certificates[0] |
| } |
| |
| // BuildNameToCertificate parses c.Certificates and builds c.NameToCertificate |
| // from the CommonName and SubjectAlternateName fields of each of the leaf |
| // certificates. |
| func (c *Config) BuildNameToCertificate() { |
| c.NameToCertificate = make(map[string]*Certificate) |
| for i := range c.Certificates { |
| cert := &c.Certificates[i] |
| x509Cert, err := x509.ParseCertificate(cert.Certificate[0]) |
| if err != nil { |
| continue |
| } |
| if len(x509Cert.Subject.CommonName) > 0 { |
| c.NameToCertificate[x509Cert.Subject.CommonName] = cert |
| } |
| for _, san := range x509Cert.DNSNames { |
| c.NameToCertificate[san] = cert |
| } |
| } |
| } |
| |
| // A Certificate is a chain of one or more certificates, leaf first. |
| type Certificate struct { |
| Certificate [][]byte |
| PrivateKey crypto.PrivateKey // supported types: *rsa.PrivateKey, *ecdsa.PrivateKey |
| // OCSPStaple contains an optional OCSP response which will be served |
| // to clients that request it. |
| OCSPStaple []byte |
| // Leaf is the parsed form of the leaf certificate, which may be |
| // initialized using x509.ParseCertificate to reduce per-handshake |
| // processing for TLS clients doing client authentication. If nil, the |
| // leaf certificate will be parsed as needed. |
| Leaf *x509.Certificate |
| } |
| |
| // A TLS record. |
| type record struct { |
| contentType recordType |
| major, minor uint8 |
| payload []byte |
| } |
| |
| type handshakeMessage interface { |
| marshal() []byte |
| unmarshal([]byte) bool |
| } |
| |
| // lruSessionCache is a ClientSessionCache implementation that uses an LRU |
| // caching strategy. |
| type lruSessionCache struct { |
| sync.Mutex |
| |
| m map[string]*list.Element |
| q *list.List |
| capacity int |
| } |
| |
| type lruSessionCacheEntry struct { |
| sessionKey string |
| state *ClientSessionState |
| } |
| |
| // NewLRUClientSessionCache returns a ClientSessionCache with the given |
| // capacity that uses an LRU strategy. If capacity is < 1, a default capacity |
| // is used instead. |
| func NewLRUClientSessionCache(capacity int) ClientSessionCache { |
| const defaultSessionCacheCapacity = 64 |
| |
| if capacity < 1 { |
| capacity = defaultSessionCacheCapacity |
| } |
| return &lruSessionCache{ |
| m: make(map[string]*list.Element), |
| q: list.New(), |
| capacity: capacity, |
| } |
| } |
| |
| // Put adds the provided (sessionKey, cs) pair to the cache. |
| func (c *lruSessionCache) Put(sessionKey string, cs *ClientSessionState) { |
| c.Lock() |
| defer c.Unlock() |
| |
| if elem, ok := c.m[sessionKey]; ok { |
| entry := elem.Value.(*lruSessionCacheEntry) |
| entry.state = cs |
| c.q.MoveToFront(elem) |
| return |
| } |
| |
| if c.q.Len() < c.capacity { |
| entry := &lruSessionCacheEntry{sessionKey, cs} |
| c.m[sessionKey] = c.q.PushFront(entry) |
| return |
| } |
| |
| elem := c.q.Back() |
| entry := elem.Value.(*lruSessionCacheEntry) |
| delete(c.m, entry.sessionKey) |
| entry.sessionKey = sessionKey |
| entry.state = cs |
| c.q.MoveToFront(elem) |
| c.m[sessionKey] = elem |
| } |
| |
| // Get returns the ClientSessionState value associated with a given key. It |
| // returns (nil, false) if no value is found. |
| func (c *lruSessionCache) Get(sessionKey string) (*ClientSessionState, bool) { |
| c.Lock() |
| defer c.Unlock() |
| |
| if elem, ok := c.m[sessionKey]; ok { |
| c.q.MoveToFront(elem) |
| return elem.Value.(*lruSessionCacheEntry).state, true |
| } |
| return nil, false |
| } |
| |
| // TODO(jsing): Make these available to both crypto/x509 and crypto/tls. |
| type dsaSignature struct { |
| R, S *big.Int |
| } |
| |
| type ecdsaSignature dsaSignature |
| |
| var emptyConfig Config |
| |
| func defaultConfig() *Config { |
| return &emptyConfig |
| } |
| |
| var ( |
| once sync.Once |
| varDefaultCipherSuites []uint16 |
| ) |
| |
| func defaultCipherSuites() []uint16 { |
| once.Do(initDefaultCipherSuites) |
| return varDefaultCipherSuites |
| } |
| |
| func initDefaultCipherSuites() { |
| varDefaultCipherSuites = make([]uint16, len(cipherSuites)) |
| for i, suite := range cipherSuites { |
| varDefaultCipherSuites[i] = suite.id |
| } |
| } |
| |
| func unexpectedMessageError(wanted, got interface{}) error { |
| return fmt.Errorf("tls: received unexpected handshake message of type %T when waiting for %T", got, wanted) |
| } |