tls.go

Documentation: crypto/tls

  // Copyright 2009 The Go Authors. All rights reserved.
  // Use of this source code is governed by a BSD-style
  // license that can be found in the LICENSE file.
  
  // Package tls partially implements TLS 1.2, as specified in RFC 5246.
  package tls
  
  // BUG(agl): The crypto/tls package only implements some countermeasures
  // against Lucky13 attacks on CBC-mode encryption, and only on SHA1
  // variants. See http://www.isg.rhul.ac.uk/tls/TLStiming.pdf and
  // https://www.imperialviolet.org/2013/02/04/luckythirteen.html.
  
  import (
  	"crypto"
  	"crypto/ecdsa"
  	"crypto/rsa"
  	"crypto/x509"
  	"encoding/pem"
  	"errors"
  	"fmt"
  	"io/ioutil"
  	"net"
  	"strings"
  	"time"
  )
  
  // Server returns a new TLS server side connection
  // using conn as the underlying transport.
  // The configuration config must be non-nil and must include
  // at least one certificate or else set GetCertificate.
  func Server(conn net.Conn, config *Config) *Conn {
  	return &Conn{conn: conn, config: config}
  }
  
  // Client returns a new TLS client side connection
  // using conn as the underlying transport.
  // The config cannot be nil: users must set either ServerName or
  // InsecureSkipVerify in the config.
  func Client(conn net.Conn, config *Config) *Conn {
  	return &Conn{conn: conn, config: config, isClient: true}
  }
  
  // A listener implements a network listener (net.Listener) for TLS connections.
  type listener struct {
  	net.Listener
  	config *Config
  }
  
  // Accept waits for and returns the next incoming TLS connection.
  // The returned connection is of type *Conn.
  func (l *listener) Accept() (net.Conn, error) {
  	c, err := l.Listener.Accept()
  	if err != nil {
  		return nil, err
  	}
  	return Server(c, l.config), nil
  }
  
  // NewListener creates a Listener which accepts connections from an inner
  // Listener and wraps each connection with Server.
  // The configuration config must be non-nil and must include
  // at least one certificate or else set GetCertificate.
  func NewListener(inner net.Listener, config *Config) net.Listener {
  	l := new(listener)
  	l.Listener = inner
  	l.config = config
  	return l
  }
  
  // Listen creates a TLS listener accepting connections on the
  // given network address using net.Listen.
  // The configuration config must be non-nil and must include
  // at least one certificate or else set GetCertificate.
  func Listen(network, laddr string, config *Config) (net.Listener, error) {
  	if config == nil || (len(config.Certificates) == 0 && config.GetCertificate == nil) {
  		return nil, errors.New("tls: neither Certificates nor GetCertificate set in Config")
  	}
  	l, err := net.Listen(network, laddr)
  	if err != nil {
  		return nil, err
  	}
  	return NewListener(l, config), nil
  }
  
  type timeoutError struct{}
  
  func (timeoutError) Error() string   { return "tls: DialWithDialer timed out" }
  func (timeoutError) Timeout() bool   { return true }
  func (timeoutError) Temporary() bool { return true }
  
  // DialWithDialer connects to the given network address using dialer.Dial and
  // then initiates a TLS handshake, returning the resulting TLS connection. Any
  // timeout or deadline given in the dialer apply to connection and TLS
  // handshake as a whole.
  //
  // DialWithDialer interprets a nil configuration as equivalent to the zero
  // configuration; see the documentation of Config for the defaults.
  func DialWithDialer(dialer *net.Dialer, network, addr string, config *Config) (*Conn, error) {
  	// We want the Timeout and Deadline values from dialer to cover the
  	// whole process: TCP connection and TLS handshake. This means that we
  	// also need to start our own timers now.
  	timeout := dialer.Timeout
  
  	if !dialer.Deadline.IsZero() {
  		deadlineTimeout := time.Until(dialer.Deadline)
  		if timeout == 0 || deadlineTimeout < timeout {
  			timeout = deadlineTimeout
  		}
  	}
  
  	var errChannel chan error
  
  	if timeout != 0 {
  		errChannel = make(chan error, 2)
  		time.AfterFunc(timeout, func() {
  			errChannel <- timeoutError{}
  		})
  	}
  
  	rawConn, err := dialer.Dial(network, addr)
  	if err != nil {
  		return nil, err
  	}
  
  	colonPos := strings.LastIndex(addr, ":")
  	if colonPos == -1 {
  		colonPos = len(addr)
  	}
  	hostname := addr[:colonPos]
  
  	if config == nil {
  		config = defaultConfig()
  	}
  	// If no ServerName is set, infer the ServerName
  	// from the hostname we're connecting to.
  	if config.ServerName == "" {
  		// Make a copy to avoid polluting argument or default.
  		c := config.Clone()
  		c.ServerName = hostname
  		config = c
  	}
  
  	conn := Client(rawConn, config)
  
  	if timeout == 0 {
  		err = conn.Handshake()
  	} else {
  		go func() {
  			errChannel <- conn.Handshake()
  		}()
  
  		err = <-errChannel
  	}
  
  	if err != nil {
  		rawConn.Close()
  		return nil, err
  	}
  
  	return conn, nil
  }
  
  // Dial connects to the given network address using net.Dial
  // and then initiates a TLS handshake, returning the resulting
  // TLS connection.
  // Dial interprets a nil configuration as equivalent to
  // the zero configuration; see the documentation of Config
  // for the defaults.
  func Dial(network, addr string, config *Config) (*Conn, error) {
  	return DialWithDialer(new(net.Dialer), network, addr, config)
  }
  
  // LoadX509KeyPair reads and parses a public/private key pair from a pair
  // of files. The files must contain PEM encoded data. The certificate file
  // may contain intermediate certificates following the leaf certificate to
  // form a certificate chain. On successful return, Certificate.Leaf will
  // be nil because the parsed form of the certificate is not retained.
  func LoadX509KeyPair(certFile, keyFile string) (Certificate, error) {
  	certPEMBlock, err := ioutil.ReadFile(certFile)
  	if err != nil {
  		return Certificate{}, err
  	}
  	keyPEMBlock, err := ioutil.ReadFile(keyFile)
  	if err != nil {
  		return Certificate{}, err
  	}
  	return X509KeyPair(certPEMBlock, keyPEMBlock)
  }
  
  // X509KeyPair parses a public/private key pair from a pair of
  // PEM encoded data. On successful return, Certificate.Leaf will be nil because
  // the parsed form of the certificate is not retained.
  func X509KeyPair(certPEMBlock, keyPEMBlock []byte) (Certificate, error) {
  	fail := func(err error) (Certificate, error) { return Certificate{}, err }
  
  	var cert Certificate
  	var skippedBlockTypes []string
  	for {
  		var certDERBlock *pem.Block
  		certDERBlock, certPEMBlock = pem.Decode(certPEMBlock)
  		if certDERBlock == nil {
  			break
  		}
  		if certDERBlock.Type == "CERTIFICATE" {
  			cert.Certificate = append(cert.Certificate, certDERBlock.Bytes)
  		} else {
  			skippedBlockTypes = append(skippedBlockTypes, certDERBlock.Type)
  		}
  	}
  
  	if len(cert.Certificate) == 0 {
  		if len(skippedBlockTypes) == 0 {
  			return fail(errors.New("tls: failed to find any PEM data in certificate input"))
  		}
  		if len(skippedBlockTypes) == 1 && strings.HasSuffix(skippedBlockTypes[0], "PRIVATE KEY") {
  			return fail(errors.New("tls: failed to find certificate PEM data in certificate input, but did find a private key; PEM inputs may have been switched"))
  		}
  		return fail(fmt.Errorf("tls: failed to find \"CERTIFICATE\" PEM block in certificate input after skipping PEM blocks of the following types: %v", skippedBlockTypes))
  	}
  
  	skippedBlockTypes = skippedBlockTypes[:0]
  	var keyDERBlock *pem.Block
  	for {
  		keyDERBlock, keyPEMBlock = pem.Decode(keyPEMBlock)
  		if keyDERBlock == nil {
  			if len(skippedBlockTypes) == 0 {
  				return fail(errors.New("tls: failed to find any PEM data in key input"))
  			}
  			if len(skippedBlockTypes) == 1 && skippedBlockTypes[0] == "CERTIFICATE" {
  				return fail(errors.New("tls: found a certificate rather than a key in the PEM for the private key"))
  			}
  			return fail(fmt.Errorf("tls: failed to find PEM block with type ending in \"PRIVATE KEY\" in key input after skipping PEM blocks of the following types: %v", skippedBlockTypes))
  		}
  		if keyDERBlock.Type == "PRIVATE KEY" || strings.HasSuffix(keyDERBlock.Type, " PRIVATE KEY") {
  			break
  		}
  		skippedBlockTypes = append(skippedBlockTypes, keyDERBlock.Type)
  	}
  
  	// We don't need to parse the public key for TLS, but we so do anyway
  	// to check that it looks sane and matches the private key.
  	x509Cert, err := x509.ParseCertificate(cert.Certificate[0])
  	if err != nil {
  		return fail(err)
  	}
  
  	cert.PrivateKey, err = parsePrivateKey(keyDERBlock.Bytes)
  	if err != nil {
  		return fail(err)
  	}
  
  	switch pub := x509Cert.PublicKey.(type) {
  	case *rsa.PublicKey:
  		priv, ok := cert.PrivateKey.(*rsa.PrivateKey)
  		if !ok {
  			return fail(errors.New("tls: private key type does not match public key type"))
  		}
  		if pub.N.Cmp(priv.N) != 0 {
  			return fail(errors.New("tls: private key does not match public key"))
  		}
  	case *ecdsa.PublicKey:
  		priv, ok := cert.PrivateKey.(*ecdsa.PrivateKey)
  		if !ok {
  			return fail(errors.New("tls: private key type does not match public key type"))
  		}
  		if pub.X.Cmp(priv.X) != 0 || pub.Y.Cmp(priv.Y) != 0 {
  			return fail(errors.New("tls: private key does not match public key"))
  		}
  	default:
  		return fail(errors.New("tls: unknown public key algorithm"))
  	}
  
  	return cert, nil
  }
  
  // Attempt to parse the given private key DER block. OpenSSL 0.9.8 generates
  // PKCS#1 private keys by default, while OpenSSL 1.0.0 generates PKCS#8 keys.
  // OpenSSL ecparam generates SEC1 EC private keys for ECDSA. We try all three.
  func parsePrivateKey(der []byte) (crypto.PrivateKey, error) {
  	if key, err := x509.ParsePKCS1PrivateKey(der); err == nil {
  		return key, nil
  	}
  	if key, err := x509.ParsePKCS8PrivateKey(der); err == nil {
  		switch key := key.(type) {
  		case *rsa.PrivateKey, *ecdsa.PrivateKey:
  			return key, nil
  		default:
  			return nil, errors.New("tls: found unknown private key type in PKCS#8 wrapping")
  		}
  	}
  	if key, err := x509.ParseECPrivateKey(der); err == nil {
  		return key, nil
  	}
  
  	return nil, errors.New("tls: failed to parse private key")
  }
View as plain text